How to use Ore in a sentence
The value of the ore reduced annually is about $10,000,000.
The dust emitted from mining the ore was poisonous in its raw state.
His people were starving as the planet died, and soon, the Council would realize the planet produced no ore without its rightful ruler.
In the last-named place the assays of ore yielded 22% of mercury.
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.Advertisement
The door pulled him in, and he sat in the doorway, coughing at the ore dust cloud and staring.
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.
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.
The kiln consists of two (or more) connected cells which are both charged with the ore.
Bollman in 1867 the ore may be extracted by carbon bisulphide.Advertisement
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.
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.
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.Advertisement
Niriz was formerly known for its manufacture of steel from iron ore brought from Parpa, 40 m.
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.
In the neighbourhood of Millom there are blast furnaces and highly productive mines of red haematite ore.
Pharmacosiderite is a mineral of secondary origin, the crystals occurring attached to gozzany quartz in the upper part of veins of copper ore.Advertisement
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.Advertisement
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.
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.Advertisement
In the township are several villages, including Salisbury, Lakeville, Lime Rock, Chapinville and Ore Hill.
The surrounding country abounds in coal, iron ore, oil, clay, stone and timber, for which the city is a distributing centre.
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.Advertisement
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.Advertisement
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).Advertisement
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 %.Advertisement
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.
In Nevada and Colorado the ore is worked chiefly for the sake of the silver.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 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.
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.
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 .
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
M, Ore bucket receiving ore for stock pile.
As present way of getting the iron of the ore into the form of wrought` iron and steel by first making cast iron and then purifying it,, i.e.
Now in the series of operations, the blastfurnace, puddling and crucible processes, through which the iron passes from the state of ore to that of crucible tool steel, it is so difficult to detect just which are the conditions essential to excellence in the final product that, once a given procedure has been found to yield excellent steel, every one of its details is adhered to by the more cautious ironmasters, often with surprising conservatism.
But Massenez and Richards, following the plan outlined by Pourcel in 1879, have found that even 3% of silicon is permissible if, by adding iron ore, the resultant silica is made into a fluid slag, and if this is removed in the early cool part of the process, when it attacks the lining of the converter but slightly.
The " pig and ore " or " Siemens " variety of the process works chiefly by oxidation, the " pig and scrap " or " Siemens-Martin " variety chiefly by dilution, sometimes indeed by extreme dilution, as when Io parts of cast iron are diluted with 90 parts of scrap. Both varieties may be carried out in the basic and dephosphorizing way, i.e.
In some British and Swedish " pig and ore " practice (§ 98), on the other hand, little or no scrap is used, and here the removal of the large quantity of carbon, silicon and phosphorus prolongs the process to 17 hours.
The pig and ore process is held back, first by the large quantity of carbon, and usually of silicon and phosphorus, to be removed, and second by the necessary slowness of their removal.
The gangue of the ore increases the quantity of slag, which separates the metal from the source of its heat, the flame, and thus delays the rise of temperature; and the purification by " oreing," i.e.
A cold lump of ore chills the slag immediately around it, just where its oxygen, reacting on the carbon of the metal, generates carbonic oxide; the slag becomes cool, viscous, and hence easily made to froth, just where the froth-causing gas is evolved.
The oxygenated metal is prepared by melting cast iron diluted with as much scrap steel as is available, and oxidizing it with the flame and with iron ore as it lies in a thin molten layer, on the hearth of a large open-hearth furnace; the thinness of the layer hastens the oxidation, and the large size of the furnace permits considerable frothing.
Yet frothing is not excessive, because the slag is not, as in common practice, locally chilled and made viscous by cold lumps of ore.
But cast iron for the basic open-hearth process can be made from almost any ore, because its requirements, comparative freedom from silicon and sulphur, depend on the management of the blast-furnace rather than on the composition of the ore, whereas the phosphorus-content of the cast iron depends solely on that of the ore, because nearly all the phosphorus of the ore necessarily passes into the cast iron.
Iron ore is found in abundance near Coblenz, the Bleiberg in the Eifel possesses an apparently inexhaustible supply of lead, and zinc is found near Cologne and Aix-la-Chapelle.
Among minerals, iron ore, sulphur, copper, coal, tin, lead and diamonds are the most imported.
Erie is the commercial centre of a large and rich grape-growing and agricultural district, has an extensive trade with the lake ports and by rail (chiefly in coal, iron ore, lumber and grain), and is an important manufacturing centre, among its products being iron, engines, boilers, brass castings, stoves, car heaters, flour, malt liquors, lumber, planing mill products, cooperage products, paper and wood pulp, cigars and other tobacco goods, gas meters, rubber goods, pipe organs, pianos and chemicals.
The staple export trade is in fish and their products; other exports are butter, copper ore and hides.
Coal and iron ore abound in the vicinity, and the city, manufactures iron, steel, tin plate, electrical and telephone supplies, shovels, boilers, leather, flour, brick and tile, salt, furniture and several kinds of vehicles.
Helsingborg ranks among the first manufacturing towns of Sweden, having copper works, using ore from Sulitelma in Norway, india-rubber works and breweries.
Copper is found principally in the Mansfeld district of the Prussian province of Saxony and near Arnsberg in the Sauerland, the ore yielding 31,713 tons in 1905, of which 5000 tons were exported.
The output of the ore has enormously increased of recent years, and the production of pig iron, as given for I 905, amounted to 10,875,000 tons of a value of 28,900,000.
Copper ore was once exported in as great quantities as 25,000 tons annually, but the best days of the mines were in the middle of the 19th century.
The province supplies over two-thirds of the iron ore mined in the Dominion, but much is still imported.