The ore is also worked for gold.
The value of the ore reduced annually is about $10,000,000.
They need our ore more than we need them.
If they didn't own the ore mines, they'd be using rocks to fight.
The most extensive fields are in the Mittagong, Wallerawang and Rylstone districts, which are roughly estimated to contain in the aggregate 12,944,000 tons of ore, containing 5,853,000 tons of metallic iron.
His people were starving as the planet died, and soon, the Council would realize the planet produced no ore without its rightful ruler.
This outlet having been closed by small stones and sulphate of lime cement, the pit is filled with sulphur ore, which is heaped up considerably beyond the edge of the pit and covered with a layer of burnt-out ore.
Others, such as Paros, are mainly composed of marble, and iron ore occurs in some.
In the last-named place the assays of ore yielded 22% of mercury.
The dust emitted from mining the ore was poisonous in its raw state.
It is situated on the right bank of the Maros, on the outskirts of the Transylvanian Erzgebirge or Ore Mountains, and consists of the upper town, or citadel, and the lower town.
What we need to make its parts—iron ore to make steel, rubber to make tires, sand to make glass, petroleum to make plastics—is generally a few cents' worth of raw materials.
high, rich in hematite iron ore; valuable limestone deposits are found some 30 m.
It is thus a common mineral in all copper mines, and sometimes occurs in large masses, as in Arizona and in South Australia, where it has been worked as an ore of copper, of which element it contains 55%.
The door pulled him in, and he sat in the doorway, coughing at the ore dust cloud and staring.
Some samples of ore, coal and limestone, obtained in the Mittagong district, with pig-iron and castings manufactured therefrom, were exhibited at the Mining Exhibition in London and obtained a first award.
By "make a car," I mean really make a car: dig iron ore out of the ground, smelt it to steel, wildcat for oil, find oil and refine it into gasoline, and so on.
Vessels go to Porman to land coke and coal, and to load iron ore and lead.
A large brass vessel used as a standard measure for the lead ore, and dating from the time of Henry VIII., is preserved.
Cobalt occurs in New South Wales, Victoria and South Australia, and efforts have been made in the former state to treat the ore, the metal having a high commercial value; but the market is small, and no attempt has been made up to 1907 to produce it on any large scale.
Iron ore is found in the state in the coal hills (especially Laurel Hills and Beaver Lick Mountain), but the deposits have not been worked on a large scale.
Ore of cobalt is obtained in no other locality in India, and although zinc blende has been found elsewhere it is known to have been extracted only in this province.
The celebrated iron ore of Elba is of Tertiary age and occurs indifferently in all the older rocks.
For many years the average output was from 10,000 to 13,000 tons of ore, yielding from 22 to 23% of copper.
For the period of thirty years during which the mine was worked the production of ore amounted to 234,648 tons, equal to 51,622 tons of copper, valued at £4,749,924.
Gothite occurs with other iron oxides, especially limonite and hematite, and when found in sufficient quantity is mined with these as an ore of iron.
In 1859 the mines were worked only for their gold; the ignorant miners threw away the " black stuff " which was really valuable silver ore with an assay value four times as great as that of their ores of gold; and when this was discovered there came a period of unprecedented silver production.
The returns from the copper fields in the state are at present a little over half a million sterling per annum, and would be still greater if it were not for the lack of suitable fuel for smelting purposes, which renders the economical treatment of the ore difficult; the development of the mines is also retarded by the want of easy and cheaper communication with the coast.
In the simplest and crudest method, as practised in Sicily, a mass of the ore is placed in a hole in the ground and fired; after a time the heat melts a part of the sulphur which runs down to the bottom of the hole and is then ladled out.
It lies in the midst of the great red and brown hematite iron-ore deposits of the Mesabi Range - the richest in the Lake Superior district - and the mining and shipping of this ore are its principal industries.
Azurite occurs with malachite in the upper portions of deposits of copper ore, and owes its origin to the alteration of the sulphide or of native copper by water containing carbon dioxide and oxygen.
The ore is kindled from above and the fire so regulated (by making or unmaking air-holes in the covering) that, by the heat produced References.
Iron.The iron-mines of France are more numerous than its coalmines, but they do not yield a sufficient quantity of ore for the needs of the metallurgical industries of the country; as will be seen in the table below the production of iron in France gradually increased during the 19th century; on the other hand, a decline in prices operated against a correspondingly marked increase in its annual value.
Near Lithgow extensive deposits of limonite, or clay-band ore, are interbedded with coal.
For example, in the Gritti and Orlando processes the ore is charged into retorts and the fusion effected by superheated steam, the sulphur being run off as usual; or as was suggested by R.
The long hauls in the United States make it specially important that the cars should carry a load in both directions, and so bcx cars which have carried grain or merchandise one way are filled with wool, coal, coke, ore, timber and other coarse articles for the return journey.
Bollman in 1867 the ore may be extracted by carbon bisulphide.
- To its mineral wealth Nevada owes its existence as a state; but for the richness of its veins of gold and silver ore it would be still little more than an arid waste.
After this last year the output of the Comstock mines declined on account of the exhaustion of the ore supply, the increased expense of mining at great depths, and the decrease in the price of silver.
The principal mining product is mercury, extracted at Idria, while iron and copper ore, zinc and coal are also found.
Very little pig iron is tries US made, most of the iron ore being exported, and iron manufactured consists of old iron resmelted.
Ore was first discovered here in 1864, but it was five years before the mines became productive.
Considerable quantities of the following minerals have been found: barytes (heavy spar), magnetite (magnetic iron ore), and pyrolusite (manganese dioxide) in Humboldt county; roofing slate in Esmeralda county; cinnabar (ore containing quicksilver) in Washoe county; haematite in Elko and Churchill counties; cerussite and galena (lead ores) in Eureka county; and wolframite (a source of tungsten) at Round Mountain, White Pine county.
The Ural industry is the older, and is still conducted on primitive methods, wood being largely used for fuel, and the ore and metals being transported by water down the Kama and other rivers.
The external trade of the Russian empire (bullion and the external trade of Finland not included) since the year 1886 is shown in the following table: The exports rank in the following order :- cereals (wheat, barley, rye, oats, maize, buckwheat) and flour, 49.2%; timber and wooden wares, 7.2; petroleum, 5.8; eggs, 5.4; flax, 5; butter, 3; sugar, 2-4; cottons and oilcake, 2 each; oleaginous seeds, &c., 1.5; with hemp, spirits, poultry, game, bristles, hair, furs, leather, manganese ore, wool, caviare, live-stock, gutta-percha, vegetables and fruit, and tobacco.
The ore generally occurs in the form of oxides, manganite and pyrolusite, and contains a high percentage of sesquioxide of manganese.
The lodes are most frequently of great size, containing huge masses of galena, and so little gangue that the ore can very easily be dressed to 83 or 84%.
The intelligence was made known in April or May; and then began a rush of thousands, - men leaving their former employments in the bush or in the towns to search for the ore so greatly coveted in all ages.
At Meanwhile, the Venetian question was becoming more and ce ore acute.
The output is to-day relatively small in comparison with that of many other fields, but there are one or two permanent gold mines of great value working low-grade ore.
Pharmacosiderite is a mineral of secondary origin, the crystals occurring attached to gozzany quartz in the upper part of veins of copper ore.
Extensive deposits, which are being developed successfully, occur in Tasmania, it being estimated that there are, within easy shipping facilities, 17,000,000 tons of ore.
The kiln consists of two (or more) connected cells which are both charged with the ore.
In the same year the city still retained its position as the greatest ore market in the world and also led in many steel products.
It was along the coast of North Carolina that Europeans in 1585 made the first discovery of iron ore within the present limits of the United States.
Niriz was formerly known for its manufacture of steel from iron ore brought from Parpa, 40 m.
Manganese ore is mined for export, and bismuth is reported to have been discovered.
Ashland has an excellent harbour, has large iron-ore and coal docks, and is the principal port for the shipment of iron ore from the rich Gogebec Range, the annual ore shipment approximating 3,500,000 tons, valued at $12,000,000, and it has also an extensive export trade in lumber.
Lead ore was found and worked on Knaresborough Common in the 16th century.
It is an oxide of iron having the formula Fe 3 O 4, corresponding with 72.4% of metal, whence its great value as an ore.
An interesting deposit of oolitic magnetic ore occurs in the Dogger (Inferior Oolite) of Rosedale Abbey, in Yorkshire; and a somewhat similar pisolitic ore, of Jurassic age, is known on the continent as chamoisite, having been named from Chamoison (or Chamoson) in the Valais, Switzerland.
Most of these were simple records of patient and laborious analytical operations, and it is perhaps surprising that among all the substances he analysed he only detected two new elements - beryllium (1798) in beryl and chromium (1797) in a red lead ore from Siberia.
Copper ore is extracted above the Murgul river (some 30 m.
The export that comes next in value is silk, and after it may be named wheat, barley, manganese ore, maize, wool, oilcake, carpets, rye, oats, liquorice and timber.
It is found also in beds of iron ore, and the haematite mines of the Cleator Moor district in west Cumberland have yielded many extremely fine crystals, specimens of which may be seen in all mineral collections.
There is some iron ore in the eastern and south-eastern parts of the state, and the mining of it was begun early in the 19th century; but the output decreased from 254,294 long tons in 1889 to only 26,585 long tons (all carbonate) in 1908.
Iron ore is extracted in the region of the Saualpe, and is worked in the foundries of St Leonhard, St Gertraud, Pravali, Hirt, Treibach and Eberstein.
In the township are several villages, including Salisbury, Lakeville, Lime Rock, Chapinville and Ore Hill.
high, composed of red soil containing a considerable quantity of iron ore; and the whole tract is for the most part unproductive.
The surrounding country abounds in coal, iron ore, oil, clay, stone and timber, for which the city is a distributing centre.
In minerals Manchuria is very rich: coal, gold, iron (as well as magnetic iron ore), and precious stones are found in large quantities.
CERARGYRITE, a mineral species consisting of silver chloride; an important ore of silver.
RUTHENIUM [[[symbol]] Ru, atomic weight To' 7 (O = 0)1, in chemistry, a metallic element, found associated with platinum, in platinum ore and in osmiridium.
It may be obtained direct from pure and bright coloured portions of the native ore cinnabar, or, artificially, by subliming a mixture of mercury and sulphur.
But this company, after extracting some 150,000 tons of ore in 1888-1889, went into liquidation in the latter year.
The output of ore was insignificant until 1892, when it stood at 178,000 tons; but in 1902 it amounted to 1,074,000 tons.
in a deep ravine in the Hungarian Ore Mountains, and is built in terraces.
Iron ore, lignite, copper, mercury, molybdenite, nickel, platinum and other minerals have been found, but the quantity of each is too small, or the quality too poor, for them to be of commercial value.
Originally it owed its whole importance to the copper mines of the Parys (probably, Parry's) mountain, as, before ore was discovered in March 1768, it was a small hamlet of fishermen.
The mineral wealth of the Cyclades has hitherto been much neglected; iron ore is exported from Seriphos, manganese and sulphur from Melos, and volcanic cement (pozzolana) from Santorin.
In the Tertiary region are found small quantities of iron ore and an indifferent brown coal.
In 1828-1840 about two million dollars' worth of ore was shipped yearly to the United States alone.
metres of the superficial area covering the mine, and a proportional duty varying from I% to 20% of the gross value of metal contained in the ore, according to the kind of metal and the method of extraction of the ore), £T45,141; and tax-papers (Tezkeres), £T58,434.
The campaigns described below are theref ore (a) The Austrian War of 1805 (Ulm and Austerlitz).
Cleveland is the largest ore market in the world, and its huge ore docks are among its most interesting features; the annual receipts and shipments of coal and iron ore are enormous.
The discovery of iron ore in the Lake Superior region made Cleveland the natural meeting-point of the iron ore and the coal from the Ohio, Pennsylvania and West Virginia mines; and it is from this that the city's great commercial importance dates.
They can impose fines for small offences not worth sending bef ore the inspector, and, in cases of high misdemeanour, have the power of inflicting corporal punishment.
What Cardiff lacks is a corresponding import trade, for its imports in 1906 amounted to only 2,108,133 tons, of which the chief items were iron ore (8 9 5,610 tons), pit-wood (303,407), grain and flour (298,197).
Minnesota ranked first among the states in 1902 in the production of iron ore.
Although the iron ranges in the north-east had been explored about 1860 and were known to contain a great wealth of ore, it was not until 1884 that mining was actually begun on the Vermilion Range.
The ore, which in many places is found in an almost pure state, is at or near the surface and the process of mining is one of great simplicity and ease.
The quality of ore in the two ranges differs somewhat, that mined from the Vermilion Range being a hard specular or red haematite, while that taken from the Mesabi Range, largely red haematite, is much softer and in many localities quite finely comminuted.
Galena (q.v.), the principal lead ore, has a world-wide distribution, and is always contaminated with silver sulphide, the proportion of noble metal varying from about o of or less to o 3%, and in rare cases coming up to 2 or i %.
The native carbonate or cerussite (q.v.) occasionally occurs in the pure form, but more frequently in a state of intimate intermixture with clay ("lead earth," Bleierde), limestone, iron oxides, &c. (as in the ores of Nevada and Colorado), and some times also with coal ("black lead ore").
This ore, metallurgically, was not reckoned of much value, until immense quantities of it were discovered in Nevada and in Colorado (U.S.).
The Nevada mines are mostly grouped around the city of Eureka, where the ore occurs in "pockets" disseminated at random through limestone.
The crude ore contains about 30% lead and 0.2 to 0.3% silver.
Stephens's discovery of the ore in 1877 was the making of the city of Leadville, which, in 1878, within a year of its foundation, had over io,000 inhabitants.
The Leadville ore contains from 24 to 42% lead and o I to 2% silver.
In Nevada and Colorado the ore is worked chiefly for the sake of the silver.
The dressed ore is introduced through a "hopper" at the top, and exposed to a moderate oxidizing flame until a certain proportion of ore is oxidized, openings at the side enabling the workmen to stir up the ore so as to constantly renew the surface exposed to the air.
In Cumberland, Northumberland, Durham and latterly the United States, the reverberatory furnace is used only for roasting the ore, and the oxidized ore is then reduced by fusion in a low, square blastfurnace (a "Scottish hearth furnace") lined with cast iron, as is also the inclined sole-plate which is made to project beyond the furnace, the outside portion (the "work-stone") being provided with grooves guiding any molten metal that may be placed on the "stone" into a cast iron pot; the "tuyere" for the introduction of the wind was, in the earlier types, about half way down the furnace.
As a preliminary to the melting process, the "browse" left in the preceding operation (half-fused and imperfectly reduced ore) is introduced with some peat and coal, and heated with the help of the blast.
Some of the roasted ore is strewed upon it, and, after a quarter of an hour's working, the whole is taken out on the work-stone, where the lead produced runs off.
The "browse," after removal of the "grey" slag, is reintroduced, ore added, and, after a quarter of an hour's heating, the mass again placed on the work-stone, &c.
It puts through 9-12 tons of ore in twenty-four hours, reducing the percentage of sulphur to 2-4%, and requires four to six men and about 2 tons of coal.
The cost of smelting a ton of ore in Colorado in a single furnace, 42 by 120 in.
Lead sulphide, PbS, occurs in nature as the mineral galena (q.v.), and constitutes the most valuable ore of llead.
General Phenomena Pieces of a certain highly esteemed iron ore, which consists mainly of the oxide Fe 3 0 4, are sometimes found to possess the power of attracting small fragments of iron or steel.
Ore endowed with this curious property was well known to the ancient Greeks and Romans, who, because it occurred plentifully in the district of Magnesia near the Aegean coast, gave it the name of magnes, or the Magnesian stone.
In Englishspeaking countries the ore is commonly known as magnetite, and pieces which exhibit attraction as magnets; the cause to which the attractive property is attributed is called magnetism, a name also applied to the important branch of science which has been evolved from the study of phenomena associated with the magnet.
Until 1820 all the artificial magnets in practical use derived their virtue, directly or indirectly, from the natural magnets found in the earth: it is now recognized that the source of all magnetism, not excepting that of the magnetic ore itself, is electricity, and it is usual to have direct recourse to electricity for producing magnetization, without the intermediary of the magnetic ore.
The chief exports are chestnut extract for tanning, cedrates, citrons, oranges, early vegetables, fish, copper ore and antimony ore.
The exports cover a wide range of agricultural, pastoral and natural productions, including coffee, rubber, sugar, cotton, cocoa, Brazil nuts, mate (Paraguay tea), hides, skins, fruits, gold, diamonds, manganese ore, cabinet woods and medicinal leaves, roots and resins.
These hills contain good building stone for ornamental architecture, and in some of them iron ore is abundant.
Iron ore is widely distributed and is found in the neighbourhood of all the coal-fields.
It is the shipping place for the iron ore mined at Gellivara, 127 m.
Genera: (a) Ore supero; basi se affigens: Actinia, Ascidia.
(b) Ore antico; corpore pertuso laterali foraminulo: Limax, Aplysia, Doris, Tethis.
(c) Ore antico; corpore tentaculis antice cincto: Holotlturia, Terebella.
(d) Ore antico; corpore brachiato: Triton, Sepia, Clio, Lernaea, Scyllaea.
(e) Ore antico; corpore pedato: Aphrodita, Nereis.
(f) Ore infero centrali: Medusa, Asteria, Echinus.
In one process the purified ore is disintegrated with hot nitric acid to produce nitrates, which are then converted into sulphates by evaporation with sulphuric acid.
The reefs are narrower than those of the Rand, and the, ore is usually very hard.
The Yzerberg near Marabastad in the Zoutpansberg consists of exceedingly rich iron ore, which has been smelted by the natives for many centuries.
Silver is found in many districts, and mines near Pretoria have yielded in one year ore worth £30,000.
Throughout the world, primary deposits of tinstone are in or closely connected with granite or acid eruptive rocks of the same type, its mineral associates being tourmaline, fluorspar, topaz, wolfram and arsenical pyrites, and the invariable gangue being quartz: the only exception to this mode of occurrence is to be found in Bolivia, where the tin ore occurs intimately associated with silver ores, bismuth ores and various sulphides, whilst the gangue includes barytes and certain carbonates.
The calcination is preferably effected in mechanical roasters, it being especially necessary to agitate the ore continually, otherwise it cakes.
The Bolivian tin ore is treated by first extracting the silver by amalgamation, &c., and afterwards concentrating the residues; there are, however, considerable difficulties in the way of treating the poorer of these very complex ores, and several chemical processes for extracting their metallic contents have been worked out.
Of the impurities of the ore the wolframite (tungstate of iron and manganese) is the most troublesome, because on account of its high specific gravity it cannot be washed away as gangue.
The dressed ore is smelted with carbon by one of two main methods, viz.
either in the shaft furnace or the reverberatory; the former is the better suited to stream tin, the latter to lode tin, but either ore can be smelted in either way, although reverberatory practice yields a purer metal.
The furnace consists of a shaft, circular (or more rarely rectangular) in plan, into which alternate layers of fuel and ore are charged, an air blast being generally injected near to the bottom of the furnace through one or more tuyeres.
In this process the purified ore is mixed with about one-fifth of its weight of a noncaking coal or anthracite smalls, the mixture being moistened to prevent it from being blown off by the draught, and is then fused on the sole of a reverberatory furnace for five or six hours.
All tin, except a small quantity produced by the shaft furnace process from exceptionally pure stream tin ore, requires refining by liquation and "boiling" before it is ready for the market.
The output from 1878 to 1891 was 329,218 tons of ore and 53,053 tons of regulus, valued at £2,794,986.
He built other foundries at Ringwood, New Jersey, and at Durham, Pennsylvania; bought iron mines in northern New Jersey, and carried the ore thence by railways to his mills.
The term 1 is not limited to underground operations, but includes also surface excavations, as in placer mining and open-air workings of coal and ore deposits by methods similar to quarrying, and boring operations for oil, natural gas or brine.
Grains of gold or particles of ore may be detected by washing samples of gravel in a prospector's 1 Of doubtful origin.
Irish mein, ore), but the New Eng.
In the case of the cheaper and more abundant minerals, such as coal and iron ore, and of large deposits of low-grade ores, the extent and character of the deposit can generally be determined by surface examinations at comparatively small expense.
In the case of coal, salt, iron ore, pyrite and other homogeneous minerals, boring may give all the information required.
A large number of holes must be bored to obtain, even approximately, the average thickness and value of the ore and the shape and size of the ore bodies.
In the case of such altered deposits surface exploration alone is likely to be misleading, and it is important to push the underground exploration far enough to reach the unaltered part of the deposit, or at least deep enough to make it certain that there is a sufficient quantity of altered or enriched ore to form the basis of profitable mining operations.
The stippled areas represent the ore shoots and the white areas the barren portions of the lode.
In some cases, where the barren areas are large, it may be necessary to have two or three years' supply of ore thus blocked out in advance.
When the roof is weak, or when it is undesirable to leave so much ore in the stopes, false stulls are sometimes erected in the upper part of the stope.
The ore below the false stulls can then be drawn out without waiting for the completion of the top stope.
In this method of mining the different stopes must be kept close together; otherwise there is much added labour in shovelling the broken ore down to the main level.
This method has the advantage of permitting the ore to be sent to the surface as fast as it is mined instead of being left for some months in the stopes for the men to stand upon.
Rock-filling will be used whenever a large proportion of barren material must be mined with the ore.
and each party of contractors has one or more mills or timbered chutes through which the rich ore is conveyed to the level below and loaded in cars.
The ore as mined is hand-picked and the barren material allowed to remain in the stope where it falls.
Above, the ground has been completely worked out from the surface, and the space formerly occupied by ore is now filled with the debris of the overlying strata which has caved in above the block of ore now being worked.
This mat of timber forms a roof under the protection of which the mining of the ore proceeds downward floor by floor.
These winzes serve for ventilation, for the passage of the workmen, and for chutes through which the ore is dumped to the level below.
Haulage roads are driven in the ore so as to divide the floor into areas of convenient size.
The room is driven in this way from one haulage road to another or to the boundary of the ore body.
In this way the whole floor is worked out and the mat of timber and overlying rock is gradually lowered and rests upon the top of the ore forming the floor below.
This system permits the complete extraction of the ore at moderate cost and without danger to the men.
The mining of each floor is carried on in sections with small working-places which are first driven of moderate height to their full length and width, leaving a back of ore above and pillars of ore between to support the upper portion of the upper layer or floor.
backof ore above are then mined in retreating back towards the haulage road.
These pillars are then filled with blast holes which are fired simultaneously, permitting the whole block of ground to the level above to drop. A floor is then reopened in this fallen ore, leaving pillars for temporary support which are blasted out as before.
This is the cheapest of the three caving systems, but is applicable only when the deposit lies between walls of very solid rock, as otherwise wall rock is liable to cave with and become mixed with ore, which adds greatly to the expense of handling.
When rock filling is available, as when the ore contains much barren material to be left behind in mining, the ore body is divided into blocks of convenient height as above, and these blocks are divided into floors, the bottom floor of each block however being attacked.
Instead of mining in horizontal floors the filling method permits the ore to be mined in vertical chambers or slices which extend from one level to the next above and from one wall of the deposit to the other.
Where each floor is timbered by itself with light timbers, as is the practice on the continent of Europe, the consolidation of the rock-filling under pressure gives rise to considerable subsidence of the unmined ore, which has frequently settled 20 ft.
For deep workings the milling method is usually employed, in which the ore is excavated in funnel-shaped pits, each of which connects with underground haulage roads by a shaft.
The ore is mined in the ordinary way, by pick and shovel if soft, or by the aid of powder if necessary, and the funnel-shaped bottom of the pit is maintained at such an angle that little or no shovelling is required to bring the excavated material to the shaft.
When the mine is worked through shafts, hoisting plant must be installed for raising the ore and handling men and supplies.
Skips are sometimes of very large capacity, holding 5, 7, and even 10 tons of ore; such are used, for example, in several shafts at Butte, Montana, in the Lake Superior copper district, and in South Africa.
The lower cut is of a skip for either ore or water; note valve in bottom.
The head-gear is often combined with ore-bins and machinery for breaking and sizing the lump ore previous to shipment to the reduction works.
- Ore and water skips mining cage and car for gold for inclined shaft.
Nevertheless, in very deep and large mines the time consumed in handling the men may make serious inroads on the time available for hoisting ore.
To mine ore or coal at minimum cost it is necessary to work the mine plant at nearly or quite its full capacity and to avoid interruption and delays.
The special difficulties which attend deep mining, in addition to the problems of hoisting ore and raising water from great depths, are the increase of temperature of the rocks and the pressure of the overlying strata.
The valuation of mines then involves the following steps: (1) The sampling of the deposit so far as developed, and assaying of the samples taken; (2) The measurement of the developed ore; (3) estimates of the probable amount of ore in the undeveloped part of the property; (4) estimates of probable profits, life of the mine, and determination of the value of the property.
On the other hand in the case of uncertain and irregular deposits, the value of which varies between very wide limits, as, for example - in most metal mines and especially mines of gold and silver - a very large number of samples must be taken - sometimes not more than two or three feet apart - in order that the average value of the ore may be known within reasonable limits of error.
In the majority of instances, however, the estimates of undeveloped ore contain a large element of uncertainty.
In order to determine the probable profit and life of the mine a definite scale of operations must be assumed, the money required for development and plant and for working capital must be estimated, the methods of mining and treating the ore determined, and their probable cost estimated.
As he is called upon to construct lines of transport, both underground and on the surface, works for water-supply and drainage, and buildings for the handling, storage and treatment of ore, he must be trained to some extent as a civil engineer.
At Silver Islet, Lake Superior, mining was successfully carried on for years under the protection of a coffer dam and an arch of rich silver ore less than 20 ft.
- See C. Le Neve Foster's Ore and Stone Mining (6th ed., London, 1905), or G.
Rickard, The Sampling and Estimation of Ore in a Mine (New York, 1904); Truscott, The Witwatersrand Goldfields - Banket and Mining Practice (London, 1898; G.
The ore is rich in silver as well as in lead.
The material has been considered by some to be magnetic iron ore and by others oxide of manganese.
The ore is smelted at Lubumbashi, where in 1918 were seven furnaces with a producing capacity of 40,000 tons a year.
In the neighbourhood of Millom there are blast furnaces and highly productive mines of red haematite ore.
Second in importance is the carbonate, calamine (q.v.) or zinc spar, which at one time was the principal ore; it almost invariably contains the carbonates of cadmium, iron, manganese, magnesium and calcium, and may be contaminated with clay, oxides of iron, galena and calcite; "white calamine" owes its colour to much clay; "red calamine" to admixed iron and manganese oxides.
Other zinc minerals are willemite, Zn 2 SiO 4, hydrozincite or zinc bloom, ZnCO 3.2Zn(OH)2, zincite or red zinc ore, ZnO, and franklinite, 3(Fe,Zn)0 (Fe,Mn) 2 0 3 .
Metallurgy The principles underlying the extraction of zinc may be summarized as: (I) the ore is first converted into zinc oxide; (2) the oxide is distilled with carbon and the distillate of metallic zinc condensed.
Oxide of zinc, like most heavy metallic oxides, is easily reduced to the metallic state by heating it to redness with charcoal; pure red zinc ore may be treated directly; and the same might be done with pure calamine of any kind, because the carbon dioxide of the zinc carbonate goes off below redness and the silica of zinc silicate only retards, but does not prevent, the reducing action of the charcoal.
Here very clean non-magnetic concentrate of willemite, which is an anhydrous zinc silicate and a very highgrade zinc ore, is separated from an intimate mixture of willemite, zincite and franklinites, with calcite and some manganese silicates.
Neither mechanical nor magnetic concentration can effect much in the way of separation when, as in many complex ores, carbonates of iron, calcium and magnesium replace the isomorphous zinc carbonate, when some iron sulphide containing less sulphur than pyrites replaces zinc sulphide, and when gold and silver are contained in the zinc ore itself.
a pound, is worth from about £2 to £7 per ton of ore.
of zinc, but the dressed zinc ore as sold ranges from 45 to 62 per cent.
of zinc. This region now furnishes the bulk of the ore required by the smelters of Illinois, Missouri and Kansas.
The ore, even if it is not blende, must be roasted or calcined in order to remove all volatile components as completely as possible, because these, if allowed to remain, would carry away a large proportion of the zinc vapour during the distillation.
The mixture of ore and charcoal is put into the crucible around the pipe, the crucible closed by a luted-on lid, and placed in a furnace constructed so as to permit of the lower end of the pipe projecting into the ash-pit.
As each retort in a furnace is in all essentials a separate crucible, and as the metal from only a few of them goes into a single ingot, there can be no uniformity either in the ingots made from the same furnace during a day's run or in those made from several furnaces treating the same ore.
Borchers, trace it to the presence of oxide, produced, for example, either by the use of a solution containing a trace of basic salt of zinc (to prevent which the bath should be kept just - almost imperceptibly - acid), or by the presence of a more electro-negative metal, which, being co-deposited, sets up local action at the expense of the zinc. Many processes have been patented, the ore being acted upon by acid, and the resulting solution treated, by either chemical or electrolytic means, for the successive removal of the other heavy metals.
Zinc oxide, ZnO, is maufactured for paint by two processes - directly from the ore mixed with coal by volatilization on a grate, as in the Wetherill oxide process, and by oxidizing the vapour given off by a boiling bath of zinc metal.
When used for ore smelting, the reduced metal and the accompanying slag were to be caught, after leaving the arc and while still liquid, in a hearth fired with ordinary fuel.
The export of coal in that year was 74,000 tons, and copper ore 937 tons (vide supra, § Minerals).
A smelting plant was erected in the vicinity of Cerro de Pasco designed to treat moo tons of ore daily, a railway was built to Oroya to connect with the state line terminating at that point, and a branch line 62 m.
Timber, pig-iron and iron ore are the leading imports, and coal, produce and iron the chief exports.
above sea-level (whence its name, from an Ojibway Indian word, said to mean "high up"), in the centre of the Marquette Range iron district, and has seven mines within its limits; the mining of iron ore is its principal industry.
The southern half of the province, that portion south of the Yangtsze Kiang, forms part of the Nan-shan, or hilly belt of the south-eastern provinces, and produces, besides cotton, coal and iron ore, large quantities of green tea.
The surrounding country is well adapted to agriculture, and slate, iron ore, cement rock and limestone are found in the vicinity.
The mining of iron ore was begun about 1767 in the vicinity of the present Cranston, and much of the metal was used in the making of cannon during the War of Independence, but the supply was soon exhausted.
were: combined textiles (not including flax, hemp and jute products) in 1900, $77,998,396; in 1905, $103,096, 311; foundry and machine shop products in 1900, $13,269,086; in 1905, $16,338,512; woollen goods in 1900, $5,330,550; in 1905, $8,163,167; rubber boots and shoes in 1 9 00, $8,034,417; electrical machinery, apparatus and supplies in 1900, $5,113,292; in 1905, $5,435,474; silversmithing and silverware in 1900, $4,249,190; in 1905, $5,323,264; gold and silver, reducing and refining (not from ore) in 1900, $3,484,454; in 1905, $4,260,698; cotton small wares in 1900, $2,379,500; in 1 905, $3,944, 60 7; hosiery and knit goods in 1900, $2,713,850; in 1905, $3,344,655; silk and silk goods in 1900, $1,311,333; in 1905, $2,555,986.
Lead ores (chiefly argentiferous galena) and building stone are found, and iron ore is distributed over the hilly country.
Attempts made to work the galena in 1878-79 and 1900 were abandoned, and the iron ore is little worked.
The silver ore was first discovered in 1832 by a shepherd at a place which bears his name, Juan Godoi.
Characteristic of the Rand is the fine white dust arising from the crushing of the ore, and, close to the batteries, the incessant din caused by the stamps employed in that operation.
These buildings were found to cover valuable ore, and in December following the Boer government marked out the site of the city proper, and possession of the plots was given to purchasers on the 1st of January 1887.
The year 1890 was one of great depression following the exhaustion of the surface ore, but the provision of better machinery and cheaper coal led to a revival in 1891.
Magnetic pyrites, copper pyrites, zinc blende and arsenical pyrites are other and less important examples, the last constituting the gold ore formerly worked in Silesia.
In 18 99, 57 62 stamps were in operation, crushing 7,331,446 tons of ore, and yielding £15,134,000, equivalent to 25.5% of the world's production.
When the ore does not contain any considerable amount of free gold mercury is not, as a rule, used during the crushing, but the amalgamation is carried out in a separate plant.
It was at one time proposed to treat the concentrated black iron obtained in the Ural gold washings, which consists chiefly of magnetite, as an iron ore, by smelting it with charcoal for auriferous pigiron, the latter metal possessing the property of dissolving gold in considerable quantity.
Chlorine, generally prepared by the interaction of pyrolusite, salt and sulphuric acid, is led from a suitable generator beneath the false bottom, and rises through the moistened ore, which rests on a bed of broken quartz; the gold is thus converted into a soluble chloride, which is afterwards removed by washing with water.
In the Witwatersrand the ore, which contains about 9 dwts.
The total cost per ton of ore treated is about 6s., of which the cyaniding costs from 2S.
West of the Low Tatra extend the Fatra group, with the highest peak, the Great Fatra (5825 ft.), to the south and east of which lie the Schemnitz group, the Ostrowsky group, and several other groups, all of which are also called the Hungarian Ore Mountains, on account of their richness in valuable ores.
South-east of the Low Tatra extend the Zips - Gomor Ore Mountains, while the most eastern group is the Hegyalja Mountains, between the Topla, Tarcza and Hernad rivers, which run southward from Eperjes to Tokaj.
The chief exports are linen, whisky, aerated waters, iron ore and cattle.
The town lies between the valleys of the Ehen and its tributary the Dub Beck, in a district rich in coal and iron ore.
Of the rarer bismuth minerals we may notice the following: - the complex sulphides, copper bismuth glance or wittichenite, BiCu 3 S 3, silver bismuth glance, bismuth cobalt pyrites, bismuth nickel pyrites or saynite, needle ore (patrinite or aikinite), BiCuPbS 3, emplectite, CuBiS 2, and kobellite, BiAsPb 3 S 6; the sulphotelluride tetradymite; the selenide guanajuatite, B12Se3, Iv.
Bismuth is extracted from its ores by dry, wet, or electro-metallurgical methods, the choice depending upon the composition of the ore and economic conditions.
The extraction from ores in which the bismuth is present in the metallic condition may be accomplished by a simple liquation, or melting, in which the temperature is just sufficient to melt the bismuth, or by a complete fusion of the ore.
In the liquation process the ore is heated in inclined cylindrical retorts, and the molten metal is tapped at the lower end; the residues being removed from the upper end.
It is situated in a deep valley in the Hungarian Ore Mountains region.
In mining, a "gouge" is the layer of soft rock or earth sometimes found in each side of a vein of coal or ore, which the miner can scoop out with his pick, and thus attack the vein more easily from the side.
Coal, textiles and iron and steel goods figure prominently amongst the imports, and emery, leather, lemons, sponges, flour, valonia and iron ore amongst the exports.
Coal lying under the sea below low-water mark belongs to the crown, and can only be worked upon payment of royalties, even when it is approached from shafts sunk upon land in private ownership. In the Forest of Dean, which is the property of the crown as a royal forest,there are certain curious rights held by a portion of the inhabitants known as the Free Miners of the Forest, who are entitled to mine for coal and iron ore, under leases, known as gales, granted by the principal agent or gaveller representing the crown, in tracts not otherwise occupied.
The country is rich in iron ore.
These are little mined at present, only 110 tons of lead ore and 516 tons of zinc ore being taken from the mines in 1908.
MISPICKEL, a mineral consisting of iron sulpharsenide, FeAsS; it contains 40% of arsenic, and is of importance as an ore of this element.
This variety forms a passage to the species glaucodote, (Co,Fe)AsS, which is found as well-developed orthorhombic crystals in copper ore at Hakansboda in Ramberg parish, Vestmanland, Sweden.
Iron ore (haematite) is abundant.
Some iron ore, gypsum, salt and limestone are also produced.
There are blast furnaces in the neighbouring parish of Asfordby for the smelting of the abundant supply of iron ore in the district.
OSMIUM [[[symbol]] Os., atomic weight 190.9 (0= 16)], in chemistry, a metallic element, found in platinum ore in small particles, consisting essentially of an alloy of osmium and iridium and known as osmiridium.
The Swedish, Norwegian, Ontario and Michigan mines yield ores of this kind; and though none of them can be profitably worked as a source of phosphate, yet on reducing the ore it may be retained in the slags, and thus rendered available for agriculture.
In 1750 the mining of iron ore was begun near Monroe, Orange county.
Ore has since been found in most of the eastern counties and as far W.
The ores are principally magnetites (New York is the largest producer of magnetite ore among the states, producing about 45% of the total for the United States in 1907 and 1908), but red haematites occur in the N.
section of the Adirondacks and in the central part of the state, and brown haematites and carbonate ore in the S.E.
Other mineral substances obtained in small quantities are: pyrite, in St Lawrence county; arsenical ore, in Putnam county; red, green and purple slate, in Washington county; garnet in Warren, Essex and St Lawrence counties; emery and felspar, in Westchester county; and infusorial earth in Herkimer county.
There are extensive deposits of iron-sand on the west coast of the North Island, and of iron ore at Parapara in Nelson.
Gold, silver, copper, lead and a little iron (almost entirely brown ore) are the principal ores of commercial importance found in Washington.
The only lead ore is galena.
Of other minerals gold has been found, but up to 1909 was not worked; iron ore exists near Kroonstad and Vredefort, but it also is not worked.
of the city are the Cornwall (magnetite) iron mines, from which about 18,000,000 tons of iron ore were taken between 1740 and 1902, and 804,848 tons in 1906.
The ore yields about 46% of iron, and contains about 2.5% of sulphur, the roasting of the ores being necessaryore-roasting kilns are more extensively used here than in any other place in the country.
The area of ore exposed is about 4000 ft.
The Butte, Anaconda & Pacific railway carries ore from the mines at Butte to the smelters at Anaconda.
Silver was raised in the 12th century, and argentiferous lead is still the most valuable ore mined; tin, iron and cobalt rank next, and coal is one of the chief exports.
Also long ore wagons are used which weigh loaded two tons per ft.
Among the other important manufactures in 1905 were: chemicals, valued at $3,964,726; slaughtering and meat packing, $2,933,877; varnish, $2,893,305; stamped ware, $2,689,766; enamelled goods, $2,361,350; boots and shoes, $2,382,051; reduction of gold and silver, not from ore, $2,361,350; corsets, $2,081,761; paints, $1,812,463; silverware and silver-smithing, $1,780,906; tobacco, cigars and cigarettes, $1,742,862; hardware, $ 1, 6 16, 755; buttons, $1,281,528, and saddlery hardware, $1,151,789.
The yield of iron ore is almost one million tons annually, while gold, silver, tin, graphite and salt are also mined.
The House had proposed to remove also the duties on coal and on iron ore, but the Senate permitted only a reduction in these.
The city is the seat of a Roman Catholic bishopric. Both coal and iron ore abound in the vicinity, and the city has numerous manufacturing establishments.
plumbum, lead) was originally used for an artificial product obtained from lead ore, and afterwards for the ore (galena) itself; it was confused both with graphite and with molybdenite.
The material as mined usually does not contain more than 20 to 50% of graphite: the ore has therefore to be crushed and the graphite floated off in water from the heavier impurities.
There are smelters and cyanide extracters in the district, but the bulk of the ore product is shipped to other places for treatment.
It also enters (as carbonates) into the composition of many minerals, such as chalk, dolomite, calcite, witherite, calamine and spathic iron ore.
It is a constituent of the minerals cerussite, malachite, azurite, spathic iron ore, calamine, strontianite, witherite, calcite aragonite, limestone, &c. It may be prepared by burning carbon in excess of air or oxygen, by the direct decomposition of many carbonates by heat, and by the decomposition of carbonates with mineral acids, M2C03+2HC1=2MCl-FH 2 O+CO 2.
The chief exports are sheep and oxen, most of which are raised in Morocco and Tunisia, and horses; animal products, such as wool and skins; wine, cereals (rye, barley, oats), vegetables, fruits (chiefly figs and grapes for the table) and seeds, esparto grass, oils and vegetable extracts (chiefly olive oil), iron ore, zinc, natural phosphates, timber, cork, crin vegetal and tobacco.
Iron ore has been found in several counties, and an iron furnace was built in Bath county, in the N.
The limestone and iron ore of the vicinity proved to be of inferior quality, and the failure of the enterprise was prevented only by the persistent efforts of George Whitefleld Scranton (1811-1861), aided by his brother Selden T.
Scranton better grades of iron ore and of limestone were procured, and within a decade a rolling mill, a nail factory and a manufactory of steel rails were established, and adequate facilities for railway transportation were provided.
Smelting, brewing and iron-founding are also carried on, as well as the manufacture of portable steam-engines, and iron ore is raised in the vicinity.
GALENA, an important ore of lead, consisting of lead sulphide (PbS).
In the lead-mining districts of Derbyshire and the north of England the ore occurs as veins and flats in the Carboniferous Limestone series, whilst in Cornwall the veins traverse clay-slates.
In the Upper Mississippi lead region of Missouri, Illinois, Iowa and Wisconsin the ore fills large cavities or chambers in limestone.
Coarsely grained galena is used for glazing pottery, and is then known as "potters' ore" or alquifoux.
Copper ore has been found near Francistown.
The production of iron ore, chiefly S.
Manganese ore is the chief mineral, and is extracted for export to the extent of 160,000 to 180,000 tons annually, besides coal, lead and silver ores, copper, naphtha, some gold, lithographic stone and marble.
In mining it is applied to various machines used in breaking and crushing the ore (see ORE-Dressing) .
Lying within the rich agricultural region of the Lebanon and Schuylkill valleys and near vast fields of anthracite coal and iron ore, Reading possesses unusual business and industrial advantages.
I.ocally the Archean contains iron ore, as in the Vermilion district of northern Minnesota, and at some points in Ontario.- The ore is mostly in the form of haematite.
One of these is about Lake Superior, where the formations have attracted attention on account of the abundant iron ore which they contain.
Iron ore occurs in the sedimentary part of the Huronian, especially in Minnesota, Michigan, Wisconsin and parts of Canada.
The ore is chiefly haematite, and has been developeci from antecedent ferruginous sedimentary deposits, through concentration and purification by ground water.
One member of the middle division of the system (Clinton beds) contains much iron ore, especially in the Appalachian Mountain region.
The ore is extensively worked at some points, as at Birmingham, Alabama.
The zinc and lead of the Joplin district of Missouri are in the limestone of this system, and the corresponding limestone in some parts of Colorado, as at Leadville, is one of the horizons of rich ore.
Early in the I 8th century the industry began to extend over New England and into New Jersey, the German bloomery forge being employed for reducing the ore directly to bar iron, and by the middle of that century it had taken a pretty firm hold in the Atlantic colonies.
The ore of the metal occurring in the Mississippi basingalena----is scattered widely and in large quantities, and being easily smelted by the roughest possible methods was much used at an early date.
The ore obtained there and in New Jersey seems to have been mostly shipped to England.
The ore of mercury had been discovered in California before the epoch of the gold excitement, and was being extensively worked, the yield in the year1850-1851being nearly 2,000,000 lb.
The extent and value of the deposits of zinc ore in the Saucon Valley, Pennsylvania, had also just become known in 1850.
The leading products, as reported by the Geological Survey for 1907, were as follows: coal, $614,798,898 (85,604,312 tons of anthracite coal, 394.759,112 of bituminous); petroleum, $120,106,749; natural gas, ~54,222,399; iron ore, $131,996,147 (pig iron, $529,958,000); copper, refined, $173,799,300; gold, coinage value, $90,435,700; buii~..ing-stone, $71,105,805; silver, commercial value, ~272OO,700: lean.
In 1907 iron ore was mined for blast-furnace use in twenty-nine states only, but the ore occurs in almost every state of the Union.
As nearly as can be estimated from imperfect statistics, frirn the total ore production of the country rose steadily from 2,873,400 long tons in, 1860 to 51,720,619 tons in 1907.
The United States became practically independent of foreign ore imports during the decade 1870 to 1879.
From 1889 to 1907 the average yearly percentages of the red haematite, brown ores, rnagnetite and carbonate in the total ore production were respectively 824, I0I, 7.1 and 0.4.
An investigation was made in 1908 for the National Conservation Commission of the ore reserves of the country.
With the reservations that only in the case of certain red haematite bedded deposits can any estimate be made of relative accuracy, say within 10%; that the concentration deposits of brown ore can be estimated only with an accuracy represented by a factor varying between 0.7 and 3; and that the great Lake Superior and the less known Adirondack deposits can be estimated within 15 to 20%, the total supply of the country was estimated at 79,594,220,000 long tons73,21o,415,000 of which were credited to haematite ores and 5,054,675,000 to magnetite.
The lode was an ore channel of great dimensions included within volcanic rocks of Tertiary age, themselves broken through pre-existing strata of Triassic age, and exhibited some of the features of a fissure vein, combined in part with those of a contact deposit and in part with those of a segregated vein.
The gangue was quartz, very irregularly distributed in bodies often of great sizes, for the most part nearly or quite barren of ore.
According to the census data for 1889 and 1902 there was an in Zinc crease in value of product of 184.1% in the interval, and of 109.5% in the quantity of ore produced.
The total product of zinc from domestic ore for the entire country was 7343 short tons in 1873, passed 100,000 tons in 1898, and 200,000 in 1907, when it amouiited to 223,745 tons.
Antimony, bismuth, selenium, tellurium, chromic iron ore, tin, nickel, cobalt, vanadium, titanium, molybdenum, uranium and tantalum are produced in the United States in small amounts, but such production in several cases has amounted to only slight discoveries, and in general they are of little importance in the market.
Coal, iron ore, building materials, lumber, livestock, cotton, fruits, vegetables, tobacco and grain are the great items in the domestic commerce of the country, upon its railways, inland waterways, and in the coasting trade.
The Keewatin and Huronian, consisting of greenstones, schists and more or less metamorphosed sedimentary rocks, are of special interest for their ore deposits, which include most of the important metals, particularly iron, nickel, copper and silver.
In the Rocky Mountains proper no eruptive rocks have broken through, so that no ore deposits of importance are known from them, but in the Cretaceous synclines which they enclose valuable coal basins exist.
Under the stimulus of federal bounties, the production of pig iron and of steel, chiefly from imported ore, is rapidly increasing.
'crin e' L ore to the shell but to sever also a strong elastic ligament, or spring resem bling india-rubber, joining the two shells about the umbonal area.
Three miles north, on Lake Erie, is the village of Fairport (pop. in 1900, 2073), with a good harbour and coal and ore docks.
It has been estimated that in 1788 this mine alone had produced ore worth L2,000,000 and in 1882 ore worth 5,50o,000.
The iron ore (found chiefly in the region of which Birmingham is the centre) is primarily red haematite and (much less important) brown haematite; though as regards the latter Alabama ranked first among the states of the Union in 1905 (with 781,561 tons).
At Toulouse, after the allies had entered Paris, but bef ore the abdication of Napoleon had become known, the last battle of the war was fought.
per annum; fish (15,000,000 lb annually); and iron ore and coal, part of which, however, is handled at Tonawanda, really a part of the port of Buffalo.
Massillon is built among hills in a part of the state noted for its large production of coal and wheat and abounding in white sandstone, iron ore and potter's clay.
Iron ore, ironstone, gold, galena, lead and copper are also found in considerable quantities in many districts.
S.E.) at the mouth of the bay, which is seldom closed in winter, exports iron and zinc ore, timber, wood-pulp and oats.
The deposits of zinc in the vicinity of Beuthen are perhaps the richest in the world, and produce twothirds of the zinc ore of Germany (609.000 tons).
Pennsylvania is by far the most important coalproducing state in the Union, and as much of the iron ore of the Lake Superior region is brought to its great bituminous coal-field for rendering into pig-iron, the value of the state's mineral products constitutes a large fraction of the total value for the entire country; in 1907, when the value of the mineral products of the state was $ 6 57,7 8 3,345, or nearly one-third that of all the United States, and in 1908 when the total for the state was $473,083,212, or more than one-fourth that of the whole United States, more than fourfifths of it was represented by coal and pig-iron.
There are deposits of various kinds of iron ore in the eastern, south-eastern, middle and some of the western counties, and from the middle of the 18th century until near the close of the 19th Pennsylvania.
But the state's iron foundries moved rapidly westward after the first successful experiments in making pig-iron with bituminous coal, in 1845, and the discovery, a few years later, that rich ore could be obtained there at less cost from the Lake Superior region resulted in a decline of iron-mining within the state until, in 1902, the product amounted to only 822,932 long tons, 72.2% of which was magnetite ore from the Cornwall mines in Lebanon county which have been among the largest producers of this kind of ore since the erection of the Cornwall furnace in 1742.
So long as charcoal only was used in the furnaces (until about 1840) and during the brief period in which this was replaced largely by anthracite, the industry was of chief importance in the eastern section, but with the gradual increase in the use of bituminous coal, or of coke made from it, the industry moved westward, where, especially in the Pittsburg district, it received a new impetus by The introduction of iron ore from the Lake Superior region.
Philadelphia, the Atlantic port, exports chiefly petroleum, coal, grain and flour, and imports chiefly iron ore, sugar, drugs and chemicals, manufactured iron, hemp, jute and flax.
Erie is quite unimportant among the lake ports in foreign commerce, but has a large domestic trade in iron ore, copper, wheat and flour.
LIMONITE, or Brown Iron Ore, a natural ferric hydrate named from the Gr.
By the operation of meteoric agencies, iron pyrites readily pass into limonite often with retention of external form; and the masses of "gozzan" or "gossan" on the outcrop of certain mineral-veins consist of rusty iron ore formed in this way, and associated with cellular quartz.
Deposits of brown iron ore of great economic value occur in many sedimentary rocks, such as the Lias, Oolites and Lower Greensand of various parts of England.
Granular and concretionary limonite accumulates by organic action on the floor of certain lakes in Sweden, forming the curious "lake ore."
Larger concretions formed under other conditions are known as "bean ore."
Bog iron ore is an impure limonite, usually formed by the influence of micro-organisms, and containing silica, phosphoric acid and organic matter, sometimes with manganese.
Argillaceous brown iron ore is often known in Germany as Thoneisenstein; but the corresponding term in English (clay iron stone) is applied to nodular forms of impure chalybite.
Thus the yellowish brown ore called by E.
Schmidt xanthosiderite, from 1'avOos (yellow) and otSnpos (iron), contains Fe 2 0(OH) 4, or Fe 2 0 3.2H 2 O; whilst the bog ore known as limnite, from At vn (marsh) has the formula Fe(OH) 3, or Fe203.3H20.
It probably represents the partial dehydration of limonite, and by further loss of water may pass into haematite or red iron ore.
The principal exports are wool, mohair and copper ore, and imports are cotton and woollen goods, indigo, coffee, sugar, petroleum, &c.
424) furnished the ore which was manufactured into articles of commerce.'
The mining industry generally has declined, but there is a trade in arsenic, extracted from the copper ore.
In the mountains near Nanking, coal, plumbago, iron ore and marble are found.
Although it contains a higher percentage of metal (5 2.9%) than any other natural compound, it is not at present employed as an ore, not only because it is so hard as to be crushed with difficulty, but also because its very hardness makes it valuable as an abrasive.
Kaolin thus seems to be the best ore, and it would undoubtedly be used were it not for the fatal objection that no satisfactory process has yet been discovered for preparing pure alumina from any mineral silicate.
Rose also carried out experiments on the decomposition of cryolite, and expressed an opinion that it was the best of all compounds for reduction; but, finding the yield of metal to be low, receiving a report of the difficulties experienced in mining the ore, and fearing to cripple his new industry by basing it upon the employment of a mineral of such uncertain supply, Deville decided to keep to his chlorides.
Two grave disadvantages were soon obvious - the limited supply of ore, and, what was even more serious, the large proportion of silicon in the reduced metal.
The chief mineral deposits in Bavaria are coal, iron ore, graphite and salt.
It is also important for this purpose that the ore should be as free as possible from arsenic (see Sulphuric Acid).
At Rio Tinto the ore is divided into three classes: (I) The poorest, containing an average of about I i% of copper, which is treated locally by leaching with water and liquor containing ferric sulphate, whereby the copper is dissolved out and afterwards precipitated by pig-iron, whilst the residue is exported as ordinary iron-pyrites.
(2) Export ore, with from 2 to 5% of copper, in whioh the sulphur, copper and precious metals are utilized, and the residual iron oxide then sold as "purple ore" for use in iron manufacture.
(3) Smelting ore, which averages about 6% of copper, and is treated metallurgically as described under Copper.
For a modern description of the deposit of pyrites of economic importance reference may be made to A Treatise on Ore Deposits, by J.
Within the Carboniferous rocks, but due to the action of various agencies long after their deposition, are important ore formations; such are the Rio Tinto ores of Spain, the lead and zinc ores and some haematite of the Pennine and Mendip hills and other British localities, and many ore regions in the United States.
Q' Penan?h g Prov.Welleley 3 s 0 -.._ .,.0 1=Higher 2 = Longitude East too ore Arch.
The mineral resources of Holland give no encouragement to industrial activity, with the exception of the coal-mining in Limburg, the smelting of iron ore in a few furnaces in Overysel and Gelderland, the use of stone and gravel in the making of dikes and roads, and of clay in brickworks and potteries, the quarrying of stone at St Pietersberg, &c. Nevertheless the industry of the country has developed in a remarkable manner since the separation from Belgium.
The history of iron may for convenience be divided into three periods: a first in which only the direct extraction of wrought iron from the ore was practised; a second which added to this primitive art the extraction of iron in the form of carburized or cast iron, to be used either as such or for conversion into wrought iron; and a third in which the iron worker used a temperature high enough to melt wrought iron, which he then called molten steel.
But in spite of the activity of the iron manufacture in many of the Roman provinces, especially England, France, Spain, Carinthia and near the Rhine, the little forges in which iron was extracted from the ore remained, until the 14th century, very crude and wasteful of labour, fuel, and iron itself: indeed probably not very different from those of a thousand years before.
Where iron ore was found, the local smith, the Waldschmied, converted it with the charcoal of the surrounding forest into the wrought iron which he worked up. Many farmers had their own little forges or smithies to supply the iron for their tools.
With the second period began, in the 14th century, the gradual displacement of the direct extraction of wrought iron from the ore by the intentional and regular use of this indirect method of first carburizing the metal and thus turning it into cast iron, and then converting it into wrought iron by remelting it in the forge.
Indeed it was the use of water-power that gave the smith pressure strong enough to force his blast up through a longer column of ore and fuel, and thus enabled him to increase the height of his forge, enlarge the scale of his operations, and in turn save fuel and labour.
And it was the lengthen ing of the forge, and the length and intimacy of contact between ore and fuel to which it led, that carburized the metal and turned it into cast iron.
This is so fusible that it melted, and, running together into a single molten mass, freed itself mechanically from the gangue," as the foreign minerals with which the ore is mixed are called.
The second period, by converting the metal into the fusible cast iron and melting this, for the first time removed the gangue of the ore; the third period by giving a temperature high enough to melt the most infusible forms of iron, liberated the slag formed in deriving them from cast iron.
Impurities.-The properties of iron and steel, like those of most of the metals, are profoundly influenced by the presence of small and sometimes extremely small quantities of certain impurities, of which the most important are phosphorus and sulphur, the former derived chiefly from apatite (phosphate of lime) and other minerals which accompany the iron ore itself, the latter from the pyrite found not only in most iron ores but in nearly all coal and coke.
Siderite, or spathic iron ore, FeCO 3, crystallizes in the rhombohedral system and contains 48.28% of iron.
Though it contains far too much sulphur to be used in iron manufacture without first being desulphurized, yet great quantities of slightly cupriferous pyrite, after yielding nearly all their sulphur in the manufacture of sulphuric acid, and most of the remainder in the wet extraction of their copper, are then used under the name of " blue billy " or " purple ore," as an ore of iron, a use which is likely to increase greatly in importance with the gradual exhaustion of the richest deposits of the oxidized ores.
- Professor Tornebohm's Estimate of the World's Ore Supply.
given in 1905 by Professor Tornebohm to the Swedish parliament, credited the world with only io,000,000,000 tons of ore, and that, if the consumption of iron should continue to increase hereafter as it did between 1893 and 1906, this quantity would last only until 1946.
The two assertions are not to be reconciled by pointing out that Professor Tornebohm underestimated, for instance crediting the United States with only 1 1 billion tons, whereas the United States Geological Survey's expert credits that country with from ten to twenty times this quantity; nor by pointing out that only certain parts of Europe and a relatively small part of North America have thus far been carefully explored for iron ore, and that the rest of these two continents and South America, Asia and Africa may reasonably be expected to yield very great stores of iron, and that pyrite, one of the richest and most abundant of ores, has not been included.
What Constitutes an Iron Ore.
- Whether a ferruginous rock is or is not ore is purely a question of current demand and supply.
That is ore from which there is reasonable hope that metal can be extracted with profit, if not to-day, then within a reasonable length of time.
Rock containing 22% of gold is an extraordinarily rich gold ore; that with 21% of copper is a profitable one to-day; that containing 21% of iron is not so to-day, for the sole reason that its iron cannot be extracted with profit in competition with the existing richer ores.
But it will become a profitable ore as soon as the richer ore shall have been exhausted.
When, in the course of centuries, the exhaustion of richer ores shall have forced us to mine, crush and concentrate mechanically or by magnetism the ores which contain only 2 or 3% of iron, then the cost of iron in the ore, measured in terms of the energy needed to mine and concentrate it, will be comparable with the actual cost of the copper in the ore of the copper-mines of to-day.
But, intermediate in richness between these two extremes, the iron ores mined to-day and these 2 and 3% ores, there is an incalculably great quantity of ore capable of mechanical concentration, and another perhaps vaster store of ore which we do not yet know how to concentrate mechanically, so that the day when a pound of iron in the ore will cost as much as a pound of copper in the ore costs to-day is immeasurably distant.
The cost of iron ore is likely to rise much less rapidly than that of coal, because the additions to our known supply are likely to be very much greater in the case of ore than in that of coal, for the reason that, while rich and great iron ore beds may exist anywhere, those of coal are confined chiefly to the Carboniferous formation, a fact which has led to the systematic survey and measurement of this formation in most countries.
In short, a very large part of the earth's coal supply is known and measured, but its iron ore supply is hardly to be guessed.
On the other hand, the cost of iron ore is likely to rise much faster than that of the potential aluminium ores, clay and its derivatives, because of the vast extent and richness of the deposits of this latter class.
In passing, it may be noted that the cost of the ore itself forms a relatively small part of the cost even of the cruder forms of steel, hardly a quarter of the cost of such simple products as rails, and an insignificant part of the cost of many most important finished objects, such as magnets, cutting tools, springs and wire, for which iron is almost indispensable.
Thus, if the use of ores very much poorer than those we now treat, and the need of concentrating them mechanically, were to double the cost of a pound of iron in the concentrated ore ready for smelting, that would increase the cost of rails by only one quarter.
The United States mine nearly all of their iron ores, Austria-Hungary, Russia and France mine the greater part of theirs, but none of these countries exports much ore.
Great Britain and Germany, besides mining a great deal of ore, still have to import much from Spain, Sweden and in the case of Germany from Luxemburg, although, because of the customs arrangement between these last two countries, this importation is not usually reported.
Belgium imports nearly all of its ore, while Sweden and Spain export most of the ore which they mine.
Great Britain has many valuable ore beds, some rich in iron, many of them near to beds of coal and to the sea-coast, to canals or to navigable rivers.
About two-thirds of the ore mined is clayey siderite.
The annual production of British iron ore reached 18,031,957 tons in 1882, but in 1905 it had fallen to 14,590,703 tons, valued at 3,482,184.
The most important British ore deposit is the Lower Cleveland bed of oolitic siderite in the Middle Lias, near Middlesborough.
thick, and its ore contains about 30% of iron.
Most of the British iron works lie in and near the important coal-fields in Scotland between the mouth of the Clyde and the Forth, in Cleveland and Durham, in Cumberland and Lancashire, in south Yorkshire, Derbyshire, and Lincolnshire, in Staffordshire and Northamptonshire, and in south Wales in spite of its lack of ore.
It has the great Cleveland ore bed and the excellent Durham coal near tidewater at Middlesbrough.
The United States have great deposits of ore in many different places.
In 1906 these latter formed 80% of the American production, and the southern states supplied about 13% of it, while the rich deposits of the middle states are husbanded in accordance with the law that ore bodies are drawn on in the order of their apparent profitableness.
Germany gets about two-thirds of her total ore supply from the great Jurassic " Minette " ore deposit of Luxemburg and Lorraine, which reaches also into France and Belgium.
The magnetite ore bodies which supply this industry lie in a band about 180 m.
thick, much ore is sent to Germany and Great Britain.
- Spain has large, rich and pure iron ore beds, near both her northern and her southern sea coast.
She exports about 90% of all the iron ore which she mines, most of it to England.
France draws most of her iron ore from her own part of the great Minette ore deposit, and from those parts of it which were taken from her when she lost Alsace and Lorraine.
Russia's most valuable ore deposit is the very large and easily mined one of Krivoi Rog in the south, from which comes about half of the Russian iron ore.
There are also important ore beds in the Urals, near the border of Finland, and at the south of Moscow.
In Austria-Hungary, besides the famous Styrian Erzberg, with its siderite ore bed about 450 ft.
thick, there are cheaply mined but poor and impure ores near Prague, and important ore beds in both northern and southern Hungary.
Algeria, Canada, Cuba and India have valuable ore bodies.
To make a ton of pig iron needs only about 1.9 tons of ore in the United States, 2 tons in Sweden and Russia, 2.4 tons in Great Britain and Germany, and about 2.7 tons in France and Belgium, while about 3 tons of the native British ores are needed per ton of pig iron.
To put the iron contained in iron ore into a state in which it can be used as a metal requires essentially, first its deoxidation, and second its separation from the other mineral matter, such as clay, quartz, &c., with which it is found associated.
These two things are done simultaneously by heating and melting the ore in contact with coke, charcoal or anthracite, in the iron blast furnace, from which issue intermittently two molten streams, the iron now deoxidized and incidentally carburized by the fuel with which it has been in contact, and the mineral matter, now called " slag."
This crude cast iron, called " pig iron," may be run from the blast furnace directly Ore FIG.
If the pig iron is to follow path 2, the purification which converts it into wrought iron or steel consists chiefly in oxidizing and thereby removing its carbon, phosphorus and other impurities, while it is molten, either by means of the oxygen of atmospheric air blown through it as in the Bessemer process, or by the oxygen of iron ore stirred into it as in the puddling and Bell-Krupp processes, or by both together as in the open hearth process.
7 and 8, of a solid column of lumps of fuel, ore and limestone, which are charged through a hopper at the top, and descend slowly as the lower end of the column is eaten off through the burning away of its coke by means of very hot air or " blast " blown through '?
GG; Flanges on the ore bucket; P, Cinder notch; HH, Fixed flanges on the top of RR', Water cooled boxes; the furnace; S, Blast pipe; J, Counterweighted false bell; T, Cable for allowing conical K, Main bell; bottom of bucket to 0, Tuyere; drop.
holes or " tuyeres " near the bottom or " hearth," and through the melting away, by the heat thus generated, both of the iron itself which has been deoxidized in its descent, and of the other minerals of the ore, called the " gangue," which unite with the FIG.
Drops of Slag Props of Iron Layer of Molten Slag- -- --:€___ Layer of Molten Iron--- * The ore and lime actually exist here in powder.
Interpenetrating this descending column of solid ore, limestone and coke, there is an upward rushing column of hot gases, the atmospheric nitrogen of the blast from the tuyeres, and the FIG.
of lron Ore Lumps of Lime - In the upper part of the furnace the carbonic oxide deoxidizes the iron oxide of the ore by such reactions as xCO+Fe02.
7, before the iron ore has descended very far it has given up nearly the whole of its oxygen, and thus lost its power of oxidizing the rising carbonic oxide, so that from here down the atmosphere of the furnace consists essentially of carbonic oxide and nitrogen.
In its slow descent the deoxidized iron nearly saturates itself with carbon, of which it usually contains between 3.5 and 4%, taking it in part from the fuel with which it is in such intimate contact, and in part from the finely divided carbon deposited within the very lumps of ore, by the reaction 2C0 C+C02.
The duty of the limestone (CaCO 3) is to furnish enough lime to form with the gangue of the ore and the ash of the fuel a lime silicate or slag of such a composition (1) that it will melt at the temperature which it reaches at about level A, of fig.
Of these the silica and alumina are chiefly those which the gangue of the ore and the ash of the fuel introduce, whereas the lime is that added intentionally to form with these others a slag of the needed physical properties.
Thus the more gangue the ore contains, i.e.
the poorer it is in iron, the more limestone must in general be added, and hence the more slag results, though of course an ore the gangue of which initially contains much lime and little silica needs a much smaller addition of limestone than one of which the gangue is chiefly silica.
Below this level the solid charge descends easily, because it consists of coke alone or nearly alone, and this in turn because the temperature here is so high as to melt not only the iron now deoxidized and brought to the metallic state, but also the gangue of the ore and the limestone, which here unite to form the molten slag, and run freely down between the lumps of coke.
There are some very evident disadvantages of excessive height; for instance, that the weight of an excessively high column of solid coke, ore and limestone tends to crush the coke and jam the charge in the lower and narrowing part of the furnace, and that the frictional resistance of a long column calls for a greater consumption of power for driving the blast up through it.
Conceive these gases passing at this great velocity through the narrow openings between the adjoining lumps of coke and ore.
The furnace is made rather narrow at the top or " stock line," in order that the entering ore, fuel and flux may readily be distributed evenly.
From its top down, the walls of the furnace slope outward at an angle of between 3° and 8°, partly in order to ease the descent of the charge, here impeded by the swelling of the individual particles of ore caused by the deposition within them of great quantities of fine carbon, by the reaction of 2C0=C+C02.
After the ascending column of gases has done its work of heating and deoxidizing the ore,.
Before its use in the gas engine, the blast-furnace gas has to be freed carefully from the large quantity of fine ore dust which it carries in suspension.