Among the borough's manufactures are stoves and furnaces, malt liquors and silk.
These small furnaces are frequently arranged for direct coal firing, but regenerative gasfired furnaces are also employed.
The shores of all the lakes which filled the depressions during the Lacustrine period abound in remains dating from the Neolithic Stone period; and numberless kurgans (tumuli), furnaces and so on bear witness to a much denser population than the present.
On account of its transparency and its resistance to fire and sudden changes of temperature, mica has been much used for the windows of stoves and lanterns, for the peep-holes of furnaces, and the chimneys of lamps and gas-burners.
The Venetian furnaces in the island of Murano are small low structures heated with wood.
There are blast furnaces, iron foundries, engineering works, iron ship-building yards, extensive saw-mills, flour-mills and a manufactory of "blue and white" pottery.
The Monteponi Company smelts its own zinc, but the lead is almost all smelted at the furnaces of Pertusola near Spezia.
The first steel plant in the southern states was established at Birmingham in 1897; in 1902, at Ensley, one of the suburbs, there were 10 furnaces controlled by one company.
There are smelting furnaces in several districts, as at Alfreton, Chesterfield, Derby, Ilkeston.
At the Charlestown navy-yard (1800) there are docks, manufactories, foundries, machine-shops, ordnance stores, rope-walks, furnaces, castingpits, timber sheds, ordnance-parks, ship-houses, &c. The famous frigate " Independence " was launched here in 1814, the more famous " Constitution " having been launched while the yard was still private in 1797.
Plantations have increased greatly in size (and also diminished in number), greater capital is involved, bagasse furnaces have been introduced, double grinding mills have increased by more than a half the yield of juice from a given weight of cane, and extractive operations instead of being carried on on all plantations have been (since 1880) concentrated in comparatively few " centrals " (168 in Feb.
In 1888 the Dowlais Iron Company (now Messrs Guest, Keen & Nettlefold, Ltd.) acquired here some ninety acres on which were built four blast furnaces and six Siemens' smelting furnaces.
deep, and of the furnaces where they melted copper, tin and gold, are very numerous; their weapons of a hard bronze, their pots (one of which weighs 75 ib), and their melted and polished bronze and golden decorations testify to a high development of artistic feeling and industrial skill, strangely contrasting with the low level reached by their earthenware.
Many forms of apparatus have been tried for ascertaining the temperature of glass furnaces.
In the next stage of the process, the glass is raised to a high temperature in order to render it sufficiently fluid to allow of the complete elimination of these bubbles; the actual temperature required varies with the chemical composition of the glass, a bright red heat sufficing for the most fusible glasses, while with others the utmost capacity of the best furnaces is required to attain the necessary temperature.
In Germany, Austria and the United States, gas furnaces are generally used.
In England directly-heated coal furnaces are still in common use, which in many cases are stoked by mechanical feeders.
The furnaces are driven to a white heat in order to fuse the mixture and expel bubbles of gas and air.
The temperature required in the fusion of sheet-glass and of other glasses produced in tank furnaces is much lower than that attained in steel furnaces, and it is consequently pos Since the discovery of the Rntgen rays, experiments have been made to ascertain the effects of the different constituents of glass on the transparency of glass to X-rays.
The fusion of sheet-glass is now generally carried out in gas-fired regenerative tank furnaces.
In Europe the gas burnt in these furnaces is derived from special gas-producers, while in some parts of America natural gas is utilized.
Thus the dimensions of the largest glass tanks greatly exceed those of the largest steel furnaces; glass furnaces containing up to 250 tons of molten sible to work glass-tanks continuously for many months together; on the other hand, glass is not readily freed from foreign bodies that may become admixed with it, so that the absence of detachable particles is much more essential in glass than in steel melting.
This workman stands upon a platform in front of special furnaces which, from their shape and purpose,.
The process of sheet-glass manufacture described above is typical of that in use in a large number of works, but many modifications are to be found, particularly in the furnaces in which the glass is melted.
In some works, the older method of melting the glass in large pots or crucibles is still adhered to, although the old-fashioned coal-fired furnaces have nearly everywhere given place to the use of producer gas and regenerators.
For the production of coloured sheet-glass, however, the employment of pot furnaces is still almost universal, probably because the quantities of glass required of any one tint are insufficient to employ even a small tank furnace continuously; the exact control of the colour is also more readily attained with the smaller bulk of glass which has to be dealt with in pots.
Except for making bottles of special colours, gas-heated tank furnaces are in general use.
The glass to be used for the production of plate is universally melted in pots or crucibles and not in open tank furnaces.
- Glass for this purpose, with perhaps the exception of the best white and tinted varieties, is now universally produced in tank-furnaces, similar in a general way to those used for sheet-glass, except that the furnaces used for " rolled plate " glass of the roughest kinds do not need such minutely careful attention and do not work at so high a temperature.
These small furnaces are usually heated by an oil spray under the pressure of steam or compressed air.
Many of the examples of these processes exhibit surprising skill and taste, and are among the most beautiful objects produced at the Venetian furnaces.
In the 16th century it had become a trade of great importance, and about 1764 twenty-two furnaces were employed in the production of beads.
It appears that as early as 1295 furnaces had been established at Treviso, Vicenza, Padua, Mantua, Ferrara, Ravenna and Bologna.
Beginning in Sussex, Surrey and Kent, where wood for fuel was plentiful, the foreign glass-workers and their descendants migrated from place to place, always driven by the fuel-hunger of their furnaces.
They can be traced by cullet heaps and broken-down furnaces, and by their names, often mutilated, recorded in parish registers.
Slingsby for burning coal in furnaces, and coal appears to have been used in the Broad Street works.
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.
The bagasse so used is now commonly taken straight from the cane mill to furnaces specially designed for burning it, in its moist state and without previous drying, and delivering the hot gases from it to suitable boilers, such as those of the multitubular type or of the water-tube type.
The chief industrial establishments are smelting furnaces for cobalt, meat-preserving works at Ouaco, sugar-works and distilleries at Noumea and La Foa, tobacco, oil and soap factories at Noumea.
Pliny explicitly speaks of a mineral Katiµ€ia or cadmic as serving for the conversion of copper into aurichalcum, and says further that the deposit (of zinc oxide) formed in the brass furnaces could be used instead of the mineral.
The furnaces are square and open in front, to allow the outlet ends of the retorts to project; they are grouped together by fours; and their several chimneys are within the same enclosure.
When hydraulic pressure to the amount of 2000 to 3000 lb per square inch is applied, the saving is unquestioned, since less time is required to dry the pressed retort, its life in the furnaces is longer, its absorption of zinc is less, and the loss of zinc by passage through its walls in the form of vapour is reduced.
The primary advantages of gasfiring are that less fuel is required, that there is better control of the heat in the furnace, and that larger and more accessible furnaces can be built.
In Silesia the introduction of gas-firing has led to the use of furnaces containing eighty muffles.
In the United States, Belgian furnaces of type (a) are built to contain 864 retorts; of type (b), to contain 300 to 400 retorts; and of type (c), preferably about 600 retorts.
The use of gas-fired furnaces greatly simplifies manual labour.
Again, in direct-fired furnaces there are commonly seven or eight rows of retorts, one above another, so that to serve the upper rows the workman must stand upon a table, where he is exposed to the full heat of the furnace and requires a helper to wait upon him.
Furthermore, with the large furnaces which gas-firing makes possible mechanical appliances may be substituted for manual labour in many operations, such as removing and replacing broken retorts, mixing and conveying the charge, drawing and casting the metal, charging and emptying the retorts, and removing the residues and products.
A redistilled zinc, from an ordinarily pure commercial zinc, is often called chemically pure, but redistillation is seldom practised except for the recovery of zinc from galvanizer's dross and from the skimmings and bottoms of the melting furnaces of zinc rolling mills.
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.
Much of the earlier electrometallurgical work was done with furnaces of the (a) type, while nearly all the later developments have been with those of class (b).
- Independently of the question of the application of external heating, the furnaces used in electrometallurgy may be broadly classified into (i.) arc furnaces, in which the intense heat of the electric arc is utilized, and (ii.) resistance and incandescence furnaces, in which the heat is generated by an electric current overcoming the resistance of an inferior conductor.
Practically the first of these furnaces was that of Despretz, in which the mixture to be heated was placed in a carbon tube rendered incandescent by the passage of a current through its substance from end to end.
Many of the furnaces now in constant use depend mainly on this principle, a core of granular carbon fragments stamped together in the direct line between the electrodes, as in Acheson's carborundum furnace, being substituted for the carbon pencils.
It is not necessary that all electric furnaces shall be run at these high temperatures; obviously, those of the incandescence or resistance type may be worked at any convenient temperature below the maximum.
Again, the construction of electric furnaces may often be exceedingly crude and simple; in the carborundum furnace, for example, the outer walls are of loosely piled bricks, and in one type of furnace the charge is simply heaped on the ground around the carbon resistance used for heating, without containing-walls of any kind.
The arc furnaces now widely used in the manufacture of calcium carbide on a large scale are chiefly developments of the Siemens furnace.
The class of furnaces heated by electrically incandescent materials has been divided by Borchers into two groups: (I) those in which the substance is heated by contact form at least so much carbide as would suffice, when diffused through the metal, to render it brittle, practically restricts the use of such processes to the production of aluminium alloys.
For further information the following books, in addition to those mentioned at the end of the article ELECTROCHEMISTRY, may be consulted: Borchers, Handbuch der Elektrochemie; Electric Furnaces (Eng.
Among the other manufactures are food preparations, wooden ware, wagons and carriages, stoves and furnaces, boots and shoes, tobacco and cigars, flour, candy, gloves, bricks, tile and pottery, furniture, paper boxes and firearms. Utica is a shipping point for the products of a fertile agricultural region, from which are exported dairy products (especially cheese), nursery products, flowers (especially roses), small fruits and vegetables, honey and hops.
It is near the great mineral deposits of Virginia, Tennessee, West Virginia, Kentucky and North Carolina; an important distributing point for iron, coal and coke; and has tanneries and lumber mills, iron furnaces, tobacco factories, furniture factories and packing houses.
In Colorado the pyritic ores containing gold and silver in association with copper are smelted in reverberatory furnaces for regulus, which, when desilverized by Ziervogel's method, leaves a residue containing 20 or 30 oz.
The precipitate is collected in a filter-press, and then roasted in muffle furnaces with nitre, borax and sodium carbonate.
yd., are removed monthly, their gold content being from 0.5 to 1 0%, and after folding are melted in reverberatory furnaces to ingots containing 2 to 4% of gold.
The trees were formerly felled for building the ships of the navy and for feeding the iron furnaces of Sussex and Hampshire.
The mining of these, together with blast furnaces and engineering works, occupies the large industrial population.
Among the leading products are those of the furnaces, foundries and machine shops, flour and grist mills, planing mills, creameries, bridge and iron works, publishing houses and a packing house; and brick, tile, pottery, patent medicines, furniture, caskets, tombstones, carriages, farm machinery, Portland cement, glue, gloves and?hosiery.
The fusion process is preferably carried out in crucible furnaces; shaft furnaces are unsatisfactory on account of the disintegrating action of the molten bismuth on the furnace linings.
Calcination in reverberatory furnaces and a subsequent smelting in the same type of furnace with the addition of about 3% of coal, lime, soda and fluorspar, has been adopted for treating the Bolivian ores, which generally contain the sulphides of bismuth, copper, iron, antimony, lead and a little silver.
It is especially used for drying hops and malt, and in blast furnaces where a high temperature is required, but it is not suited for reverberatory furnaces.
Coals richer in hydrogen, on the other hand, are more useful for burning in open fires - smiths' forges and furnaces - where a long flame is required.
In this portion of the pit are generally placed the furnaces for ventilation, and the boilers required for working steam engines underground, as well as the stables and lamp cabin.
The material for filling may be the waste from earlier workings stored in the spoil banks at the surface; where there are blast furnaces in the neighbourhood, granulated slag mixed with earth affords excellent packing.
Besides the iron furnaces, situated in the south near the Lorraine plateau, there are tanneries, weaving and glove-making factories, paper-mills for all sorts of paper, breweries and distilleries, and sugar refineries.
Among towns next to the capital, Luxemburg, are Echternach and Diekirch, both worthy of note for their blast furnaces.
There are blast furnaces in the neighbouring parish of Asfordby for the smelting of the abundant supply of iron ore in the district.
in height, is placed on the crucible to allow room for long bars to be melted in the crucible and to prevent the surrounding and C is the flue, common to two furnaces and leading to the stack.
Gas is used as fuel for the melting furnaces at Philadelphia.
They are heated in circular furnaces 21 in.
Here A is the iron cover surrounding the furnaces, B is the revolving lid of a furnace, save time and to reduce the loss of the precious metals.
before it reaches the burners at the furnaces.
Silver blanks, however, are passed through rotary gas furnaces in which no attempt is made to exclude the air.
The great industries are coal-miningsome of the pits extending for a long distance beneath the firthiron-founding (with several blast furnaces) and engineering, but it has also important manufactures of salt, soap, vitriol and other chemicals.
Other products exceeding $1,000,000 in value were: leather ($14, 0 74,397), Milwaukee being second in the manufacture of leather among the cities of the United States; foundry and machine shop products ($10,232,723); iron and steel ($7,010,793); flour and grist-mill products ($6,320,428) slaughtering and meat-packing products ($5,95 8, 5 1 5); men's clothing ($4,759,54 8); boots and shoes ($2,929,405); electrical machinery, apparatus and supplies ($2,257,229); chewing and smoking tobacco ($1,966,930) and cigars and cigarettes ($1,540,019); furniture ($1,767,290); trunks and valises ($1,623,310); hosiery and knit goods ($ 1, 535, 1 7 6); confectionery ($1,379,668); stoves and furnaces ($1,288,931); leather gloves and mittens 41,207,633); structural iron work ($1,037,217); wooden packing boxes ($1,024,750); and paints ($ 1, 01 5,774).
This is one of the chief manufacturing centres in the United Kingdom, and the name arises from the effect of numerous collieries and furnaces, which darken the face of the district, the buildings and the atmosphere.
Their blast furnaces produce 1,700,000 tons of pig-iron annually.
The value of its factory products in 1905 was $ 1 7, 1 4 6, 33 8 (1 4.3% more than in 1900), the more important being those of steel works and rolling mills ($4,528,907), blast furnaces, steam railway repair shops, cigar and cigarette factories ($1,258,498), foundries and machine shops ($953,617), boot and shoe factories ($922,568), flouring and grist mills, slaughtering and meat-packing establishments and silk mills.
The principal manufactures are hardware, furnaces, agricultural implements, carriages and chemicals.
A soft, unctuous form results on treating carbon with ash or silica in special furnaces, and this gives the so-called "deflocculated" variety when treated with gallotannic acid.
The products of greatest value in 5905 were: custom-made men's clothing; fruits and vegetables and oysters, canned and preserved; iron and steel; foundry and machine-shop products, including stoves and furnaces; flour and grist mill products; tinware, coppersmithing and sheet iron working; fertilizers; slaughtering and meat-packing; cars and repairs by steam railways; shirts; cotton goods; malt liquors; and cigars and cigarettes.
By the glass factories and iron furnaces the country was being rapidly depleted of wood, while no attempt was being made to replace the damage by planting.
The manufacture of lumber and timber gave employment to the largest total number of workers; and this industry, together with those of foundry and machine shops (including locomotives, stoves and furnaces), cotton goods (including small wares), railway car and repair shops, and iron and steel, were (in order) the five greatest employers of labor.
Thus, of silk goods, worsteds, the products of blast furnaces, of rolling mills and steel works, glass, boots and shoes, hosiery and knit goods, slaughtering and meat products, agricultural implements, woollens, leather goods, cotton goods and paper and wood pulp, four leading states produced in each case from 88~5%, in the case of silk goods, to 58.6% in the case of pulp.
About 1789 there were fourteen furnaces and thirty-four forges in operation in Pennsylvania.
This waste, however, is decreasing, the coal abandoned in the mine having averaged, in the beginning of mining, two or three times the amount taken out; and the chief part of the remaining waste is in imperfect combustion in furnaces and fire-boxes.
Magnetites were also early employed, at first in Catalan forges, in which by means of a direct process the metal was secured from the ores and forged into blooms without being cast; later they were smelted in blast furnaces.
When these fires occur while the trees are full of sap, a curious mucilaginous matter is exuded from the half-burnt stems; when dry it is of pale reddish colour, like some of the coarser kinds of gum-arabic, and is soluble in water, the solution resembling gumwater, in place of which it is sometimes used; considerable quantities are collected and sold as " Orenburg gum "; in Siberia and Russia it is occasionally employed as a semi-medicinal food, being esteemed an antiscorbutic. For burning in close stoves and furnaces, larch makes tolerably good fuel, its value being estimated by Hartig as only one-fifth less than that of beech; the charcoal is compact, and is in demand for iron-smelting and other metallurgic uses in some parts of Europe.
The city has various manufactures, including iron, engines, furnaces, reapers, threshers and bottles.
Many dyers' furnaces, a little silver refinery, and perhaps a bakery have also been noticed.
There are limestone quarries in nearly two-thirds of the counties and great quantities of the stone are used for flux in the iron furnaces, for making quicklime, for railway ballast and for road making.
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.
The child-labour law of 1909 forbids the employment of children under eighteen years of age in blast furnaces, tanneries, quarries, in managing elevator lifts or hoisting machines, in oiling dangerous machinery while in motion, at switch tending, as brakesmen, firemen, engineers, motormen and in other positions of similar character.
It was soon discovered that the faculty of inducing dissociation possessed by the current might now be utilized with some hope of pecuniary success, but as electrolytic currents are of lower voltage than those required in electric furnaces, molten alumina again became impossible.
Darwen is a centre of the cotton trade and has also blast furnaces, and paper-making, paper-staining and fire-clay works.
The management of the furnaces is relatively easy, and consists in adapting the volume and intensity of the fires to particular needs.
Traces of thallium, which are present in some pyrites, may be detected in the flues of the furnaces where the metal is roasted.
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 indirect process once established, the gradual increase in the height and diameter of the high furnace, which has lasted till our own days, naturally went on and developed the gigantic blast furnaces of the present time, still called " high furnaces " in French and German.
Of late furnaces have been built even as wide as 17 ft.
In the very swift-running furnaces of the Pittsburg type this outward flare of the boshes ceases at about 12 ft.
To this very plausible theory it may be objected that in many slowrunning furnaces, which work very regularly and show no sign of scaffolding, the outward flare of the boshes continues (though steepened) far above this region of pastiness, indeed nearly half-way to the top of the furnace.
Indeed, one important reason for the difficulties in working very high furnaces, e.g.
Thus some 1700 tons of materials are charged daily into each of these furnaces without being shovelled at all, running by gravity from bin to bucket and from bucket to furnace, and being hoisted and charged into the furnace by a single engineer below, without any assistance or supervision at the furnacetop.
An excess of silicon or sulphur in the cast iron from one blastfurnace is diluted by thus mixing this iron with that from the other furnaces.
Should several furnaces simultaneously make iron too rich in silicon, this may be diluted by pouring into the mixer some low-silicon iron melted for this purpose in a cupola furnace.
At Hourpes, in order to save the expense of this remelting, the molten cast iron as it comes from the blast-furnace is poured directly into the puddling furnace, in large charges of about 2200 lb, which are thus about four times as large as those of common puddling furnaces.
To bring them to a temperature suitable for rolling, these ingots must be set in heating or soaking furnaces (§ 125), and this should be done as soon as possible after they are cast, both to lessen the loss of their initial heat, and to make way for the next succeeding lot of ingots, a matter of great importance, because the charges of steel follow each other at such very brief intervals.
Here each mould and each ingot was handled as a separate unit twice, instead of only once as in the car casting system; the ingots radiated away great quantities of heat in passing naked from the converting mill to the soaking furnaces, and the heat which they and the moulds radiated while in the converting mill was not only wasted, but made this mill, open-doored as it was, so intolerably hot, that the cost of labour there was materially increased.
- These furnaces are usually stationary, but in that shown in figs.
A locomotive carries a train of these cars to the track running beside a long line of open-hearth furnaces.
Electric steel-making processes, or more accurately processes in which electrically heated furnaces are used, have developed very rapidly.
In steel-making, electric furnaces are used for two distinct purposes, first for making steel sufficiently better than Bessemer and open-hearth steels to replace these for certain important purposes, and second for replacing the very expensive crucible process for making the very best steel.
The advantages of the electric furnaces for these purposes can best be understood after examining the furnaces themselves and the way in which they are used.
The most important ones are either " arc " furnaces, i.e.
It is by forming calcium sulphide that sulphur is removed in the manufacture of pig iron in the iron blast furnace, in the crucible of which, as in the electric furnaces, the conditions are strongly deoxidizing But in the Bessemer and open-hearth processes this means of removing sulphur cannot be used, because in each of them there is always enough oxygen in the atmosphere to re-oxidize any calcium as fast as it is deoxidized.
But if we rely on this means we have difficulty in reducing the sulphur content of the metal to 0.03% and very great difficulty in reducing it to 0.02%, whereas with the calcium sulphide of the electric furnaces we can readily reduce it to less than 0.01%.
This furnace may be used also for purifying the molten metal, but it is not so well suited as the arc furnaces for dephosphorizing.
Electric furnaces are at an advantage over others as regards the removal of sulphur and of iron oxide from the molten steel, because their atmosphere is free from the sulphur always present in the flame of coal-fired furnaces, and almost free from oxygen, because this element is quickly absorbed by the carbon and silicon of the steel, and in the case of arc furnaces by the carbon of the electrodes themselves, and is replaced only very slowly by leakage, whereas through the Bessemer converter and the open-hearth furnace a torrent of air is always rushing.
Indeed, the freedom of the atmosphere of the electric furnaces from oxygen is also the reason indirectly FIG.
In short the electric furnaces can be used to improve the molten product of the Bessemer converter and open-hearth furnace, essentially because their atmosphere is free from sulphur and oxygen, and because they can therefore remove sulphur, iron oxide and mechanically suspended slag, more thoroughly than is possible in these older furnaces.
Further, the electric furnaces, e.g.
In short electric furnaces replace the old crucible furnace primarily because they work more cheaply, though in addition they may be made to yield a better steel than it can.
Thus we see that the purification in these electric furnaces has nothing to do with electricity.
The electric furnaces are likely to displace the crucible furnaces completely, because they work both more cheaply and better.
They are not likely to displace either the open-hearth furnace or the Bessemer converter, because their normal work is only to improve the product of these older furnaces.
It is still in great demand for certain normal purposes for which either great ease in welding or resistance to corrosion by rusting is of great importance; for purposes requiring special forms of extreme ductility which are not so confidently expected in steel; for miscellaneous needs of many users, some ignorant, some very conservative; and for remelting in the crucible processAll the best cutlery and tool steel is made either by the crucible process or in electric furnaces, and indeed all for which any considerable excellence is claimed is supposed to be so made, though often incorrectly.
In a very few places the molten cast iron as it issues from the blast furnace is cast directly in these moulds, but in general it is allowed to solidify in pigs, and then remelted either in cupola furnaces or in air furnaces.
Heating Furnaces are used in iron manufacture chiefly for bringing masses of steel or wrought iron to a temperature proper for rolling or forging.
Many of the furnaces used for this heating are in a general way like the puddling furnace shown in fig.
But in addition there are many special kinds of furnaces arranged to meet the needs of each case.
Huge blast furnaces are in constant activity, and the output of rolled iron and steel is constantly increasing.
In 1840 this had grown to 241,000 tons, in 1845 to 475, 000 tons and in 1865 to 1,164,000 tons, almost the height of its prosperity, for in 1905 the product of 101 blast furnaces only amounted to 1,375,125 tons, and in the interval there were years when the output was below one million tons.
In 1901 the number of persons engaged in working of the raw material was 23,263, of whom 8258 were employed in steel smelting and founding, 7781 at blast furnaces in the manufacture of pig-iron, and 7224 at puddling furnaces and rolling mills.
On the island of Palau Brani stand the largest tin-smelting works in existence, which for many years have annually passed through their furnaces more than half the total tin output of the world.
The counts of Mansfeld, who, many years before, had started the mining industry, made a practice of building and letting out for hire small furnaces for smelting the ore.
The ancient wootz, and the products of the native furnaces of Africa are first cast, then hammered out thin.
The process is carried out either in hand-wrought furnaces,or mechanical furnaces, both called " decomposing " or " salt-cake furnaces."
This requires more time and fuel than the work in " open " furnaces, but in the muffles the gaseous hydrochloric acid is separated from the fire-gases, just like that evolved in the pot, and can therefore be condensed into strong hydrochloric acid, like the pot-acid.
This drawback has been overcome by the construction of " pluspressure " furnaces (figs.
Since the work with ordinary hand-wrought salt-cake furnaces is disagreeable and costly, many attempts have been made to construct mechanical salt-cake furnaces.
Mactear's furnaces (fig.
This has led some factories which had introduced such furnaces to revert to hand-wrought muffle-furnaces.
Gossage to the condensation of hydrochloric acid, are still nearly everywhere in use, frequently combined with a number of stone tanks through which the gas from the furnaces travels before entering the towers, meeting on its way the acid condensed in the tower.
It is called a " black-ash " furnace, and belongs to the class of reverberatory furnaces.
These furnaces possess a large cylindrical shell (e), lined with fire-bricks, and made to revolve round its horizontal axis by means of a toothed wheel fixed on its exterior; (if) are tire-seats holding tires (gg), which work in friction rollers (h).
These mechanical furnaces do the work of from four to ten ordinary furnaces according to their size, with comparatively very little expense for labour, but they must be very carefully managed and the black-ash from them is more difficult to lixiviate than that from hand-wrought furnaces, because it is less porous.
The washed-out calcium carbonate, which always contains much calcium hydrate and 2 or 3% of soda in various forms, usually goes back to the black-ash furnaces, but it cannot be always used up in this way, and what remains is thrown upon a heap outside the works.
The Hartville iron deposits are worked by the Colorado Fuel & Iron Company, which ships large quantities of ore to its furnaces at Pueblo, Colorado.
The man who brought the grain from Africa to the public stores at Ostia, the baker who made it into loaves for distribution, the butchers who brought pigs from Samnium, Lucania or Bruttium, the purveyors of wine and oil, the men who fed the furnaces of the public baths, were bound to their callings from one generation to another.
Its industries include iron foundries, rolling mills, puddling furnaces, and manufactures of iron, steel and brass wares and of machines.
The town owes much of its prosperity to its coal mines, which employ a large proportion of the inhabitants and supply the factory furnaces.
Roasted ores may be smelted in reverberatory furnaces (English process), or in blast-furnaces (German or Swedish process).
The matte is treated either in reverberatory furnaces (English process), in blast furnaces (German process), or in converters (Bessemer process).
The " American process " or " Pyritic smelting " consists in the direct smelting of raw ores to matte in blast furnaces.
The " English process " is made up of the following operations: (i) calcination; (2) smelting in reverberatory furnaces to form the matte; (3) roasting the matte; and (4) subsequent smelting in reverberatory furnaces to fineor white-metal; (5) treating the fine-metal in reverberatory furnaces to coarseor blistercopper, either with or without previous calcination; (6) refining of the coarse-copper.
The " AngloGerman Process " is a combination of the two preceding, and consists in smelting the calcined ores in shaft furnaces, concentrating the matte in reverberatory furnaces, and smelting to coarse-metal in either.
The process is effected either in heaps, stalls, shaft furnaces, reverberatory furnaces or muffle furnaces.
Shaft furnaces are in use for ores rich in sulphur, and where it is desirable to convert the waste gases into sulphuric acid.
Muffle furnaces are suitable for fine ores which are liable to decrepitate or sinter.
Reverberatory furnaces of three types are employed in calcining copper ores: (I) fixed furnaces, with either hand or mechanical rabbling; (2) furnaces with movable beds; (3) furnaces with rotating working chambers.
Hand rabbling in fixed furnaces has been largely superseded by mechanical rabbling.
Of mechanically rabbling furnaces we may mention the O'Harra modified by Allen-Brown, the Hixon, the KellerGaylord-Cole, the Ropp, the Spence, the Wethey, the Parkes, Pearce's " Turret " and Brown's " Horseshoe " furnaces.
Blake's and Brunton's furnaces are reverberatory furnaces with a movable bed.
Furnaces with rotating working chambers admit of continuous working; the fuel and labour costs are both low.
Shaft calcining furnaces are available for fine ores and permit the recovery of the sulphur.
In the Gerstenhoffer and Hasenclever-Helbig furnaces the fall is retarded by prisms and inclined plates.
In other furnaces the ore rests on a series of horizontal plates, and either remains on the same plate throughout the operation (0111vier and Perret furnace), or is passed from plate to plate by hand (Maletra), or by mechanical means (Spence and M`Dougall).
Some of these furnaces are straight, others circular.
The M`Dougall-Herreshoff, working on ores of over 30% of sulphur, requires no fuel; but in furnaces of the reverberatory type fuel must be used, as an excess of air enters through the slotted sides and the hinged doors which open and shut frequently to permit of the passage of the rakes.
The quantity of ore which these large furnaces, with a hearth area as great as 2000 ft.
Shaft calcining furnaces like the Gerstenhoffer, Hasenclever, and others designed for burning pyrites fines have not found favour in modern copper works.
In reverberatory furnaces it is smelted by fuel in a fireplace, separate from the ore, and in cupolas the fuel, generally coke, is in direct contact with the ore.
When Swansea was the centre of the copper-smelting industry in Europe, many varieties of ores from different mines were smelted in the same furnaces, and the Welsh reverberatory furnaces were used.
In Butte, Montana, reverberatories have in the past been preferred to cupola furnaces, as the charge has consisted mainly of fine roasted concentrates; but the cupola is gaining ground there.
At the Boston and Great Falls (Montana) works tilting reverberatories, modelled after open hearth steel furnaces, were first erected; but they were found to possess objectionable features.
Now both these and the egg-shaped reverberatories are being abandoned for furnaces as long as 43 ft.
Furnaces of this size smelt 200 tons of charge a day.
In 1900 the furnaces were 35 ft.
In Mansfeld brick cupola furnaces are without a rival in size, equipment and performance.
They are round stacks, designed on the model of iron blast furnaces, 29 ft.
The low percentage of sulphur in the roasted ore is little more than enough to produce a matte of 40 to 45%, and therefore the escaping gases are better fitted than those of most copper cupola furnaces for burning in a stove.
Blast furnaces of large size, built of brick, have been constructed for treating the richest and more silicious ores of Rio Tinto, and the Rio Tinto Company has introduced converters at the mine.
As greater size has been demanded, oval and rectangular furnaces - as large as 180 in.
The largest furnaces are those of the Boston & Montana Company at Great Falls, Montana, which have put through soo tons of charge daily, pouring their melted slag and matte into large wells of io ft.
The furnaces used were of ordinary design and built of brick.
It is smelted raw with hot blast in cupola furnaces, the largest being 2 10 in.
A similar operation is conducted when arsenic is present; basic-lined reverberatory furnaces have been used for the same purpose.
The iron ore raised in the various countries, and in the most productive counties, is here shown: The number of furnaces in blast (fractions showing the proportion of the year furnaces were in blast) was: in England 298162, Wales 19,; Scotland 852, total 403 i '.
The total number of existing furnaces in 1900 was: in England 456, Wales 42, Scotland 106; total 604; so that 33% of the number stood unused.
In 1905 furnaces in blast numbered: England 244, Wales 13, Scotland 87A z; total 345A z; and those existing: in England 412, Wales 31, Scotland tor; total 544; and the percentage unused was thus 36.
Among its industrial establishments are rolling mills, tube and pipe works, furnaces, steel mills, a brass foundry, and manufactories of electrical railway supplies, boxes, asbestos coverings, enamel work and ice.
The city has electric car and steam car shops and various manufactures, including stoves and furnaces (the most important), bottles, table glass-ware, cigars, rope halters, machine furniture and bent wood.
Finding that the bad quality of the steel then available for his products seriously hampered him, he began to experiment in steel-manufacture, first at Doncaster, and subsequently at Handsworth, near Sheffield, whither he removed in 1740 to secure cheaper fuel for his furnaces.
The roasting is carried on in hand and mechanical reverberatory furnaces, and occasionally in muffle-furnaces.
The apparatus for drying ore and salt varies greatly, drying-floors, dry-kilns and continuous mechanical reverberatory furnaces with stationary and revolving hearths being used.
The values of the other leading manufactures in 1905 were as follows: products of foundry and machine shops, $49,425,385; iron and steel 2 (including products of blast furnaces and rolling mills), $23,667,483; wire (exclusive of copper wire), $11,103,959; petroleum refining, $46,608,984; tanned, curried and finished leather, $21,495,329 (5th in the United States in 1900 and 1905); malt liquors, $ 1 7,44 6, 447; slaughter-house products and packed meats, $17,238,076; electrical machinery, supplies and apparatus, $13,803,476 (5th in the United States in 1900 and in 1905); chemicals, $13,023,629; rubber belting and hose, $9,915,742; jewelry, $9,303,646 (4th in the United States in 1900 and in 1905); tobacco, cigars and cigarettes, $8,331,611.
The inhabitants are employed chiefly in the iron mines, at forges and blast furnaces, and in charcoal burning and the manufacture of blacking from firewood.
An anti-smoke injunction in 1908 closed the furnaces in the immediate vicinity of Salt Lake City.
It has coal mines, iron furnaces, steel and boiler works, and soap, glass and chemical factories.
The district abounds in blast furnaces.
The furnaces within the port produce some 2,500,000 tons of pig iron annually.
This operation is both more costly and more delicate than the roasting of pyrites, but it is now perfectly well understood, and gas is obtained from blende furnaces hardly inferior in quality to that yielded by pyrites kilns.
In America, and quite exceptionally also in Europe, mechanical furnaces are used for the roasting of blende.
In the earlier part of his life he and his relation Dr Newton of Grantham had put up furnaces, and had wrought for several months in quest of the philosopher's tincture.
But it is not very well adapted to large furnaces, and especially not to those cases where all the space round the furnace is required for manipulating heavy, white-hot masses of iron, or for similar purposes.
The gas-producers constructed by Messrs Siemens Brothers, from 1856 onwards, were provided with a kind of brick chimney; on the top of this there was a horizontal iron tube, continued into an iron down-draught, and only from this the underground flues were started which sent the gas into the single furnaces.
Until 1830 the fur-trade, controlled largely by John Jacob Astor's American Fur Company, continued to be the predominating interest in the Wisconsin region, but then the growing lead mining industry began to overshadow the fur-trade, and in the mining region towns and smelting furnaces were rapidly built.
It was owing to the existence of this ore that the town of Barrow grew up in the 19th century; at first as a port from which the ore was exported to South Wales, while later furnaces were established on the spot, and acquired additional importance on the introduction of the Bessemer process, which requires a non-phosphoric ore such as is found here.
The hematite is also worked at Ulverston, Askam, Dalton and elsewhere, but the furnaces now depend in part upon ore imported from Spain.
The first place is occupied by the iron industries, embracing foundries, furnaces, engineering and machine shops, &c. Next come cotton spinning and weaving, calico printing, yarn-spinning, dyeing and similar textile branches, besides a variety of other industries.
Bilston contains numerous furnaces, forges, rolling and slitting mills for the preparation of iron, and a great variety of factories for japanned and painted goods, brass-work and heavy iron goods.
It is obtained commercially by roasting arsenical pyrites in either a Brunton's or Oxland's rotatory calciner, the crude product being collected in suitable condensing chambers, and afterwards refined by resublimation, usually in reverberatory furnaces, the foreign matter being deposited in a long flue leading to the condensing chambers.
Ironstone is worked at several places and there are some blast furnaces.
The large furnaces for the distillation of mercury at Almaden were at one time heated solely with charcoal obtained from the Cistus ladaniferus.
Iron, coal and limestone abound in the vicinity, and the borough has large manufactories of stoves and furnaces, and of iron and steel, in one of which in 1845 a "T"-rail, probably the first in America, was rolled.
It is the capital of the Altai mining districts, and besides smelting furnaces possesses glassworks, a bell-foundry and a mint.
Manufacturing is the principal industry; and among the manufactures are rattan goods, hosiery, stoves and furnaces, boots and shoes, and pianos.
A recent application is in the cooling and drying of the air blast for blast furnaces.
Among the manufactures are stoves and furnaces, foundry and machine shop products, carriages and wagons, flour and grist mill products, malt liquors, dairymen's and poulterers' supplies, showcases, men's clothing, agricultural implements, saddlery and harness, and lumber.
In the early history of Tennessee iron of superior quality was produced, in small charcoal furnaces, from the brown hematites of the central part of the state.
After the close of the Civil War (1865) the iron resources of the state attracted renewed attention, particularly the brown and red hematites, and large and modern furnaces were erected in the Chattanooga district to reduce these ores.
The capital invested in blast furnaces in 1905 was $5,939,7 8 3, they employed 1486 persons, and the value of their products was $3,428,049.
But in all those languages the word has a more extended meaning than in English, as it covers every variety of heating apparatus; while here, in addition to furnaces proper, we distinguish other varieties as ovens, stoves and kilns.
Our bakers' ovens, hot-air ovens or stoves, annealing ovens for glass or metal, &c., would all be called fours in, French and Olen in German, in common with furnaces of all kinds.
Furnaces are constructed according to many different patterns with varying degrees of complexity in arrangement; but all may be considered as combining three essential parts, namely, the fire-place in which the fuel is consumed, the heated chamber, laboratory, hearth or working bed, as it is variously called, where the heat is applied to the special work for which the furnace is designed, and the apparatus for producing rapid combustion by the supply of air under pressure to the fire.
In the simplest cases the functions of two or more of these parts may be combined into one, as in the smith's forge, where the fire-place and heating chamber are united, the iron being placed among the coals, only the air for burning being supplied under pressure from a blowing engine by a second special contrivance, the tuyere, tuiron, twyer or blast-pipe; but in the more refined modern furnaces, where great economy of fuel is an object, the different functions are distributed over separate and distinct apparatus, the fuel being converted into gas in one, dried in another, and heated in a third, before arriving at the point of combustion in the working chamber of the furnace proper.
Furnaces may be classified according as the products of combustion are employed (i) only for heating purposes, or (2) both for heating and bringing about some chemical change.
The furnaces employed for steam-raising or for heating buildings are invariably of the first type (see Boiler and Heating), while those employed in metallurgy are generally of the second.
Metallurgical furnaces of the first class are termed crucible, muffle or retort furnaces, and of the second shaft and reverberatory furnaces.
(a) Height of furnace greater than diameter=shaft furnaces.
(a) With blast =- furnaces.
(b) Height not much greater than diameter=hearth furnaces.
(2) Substance heated by products of combustion = reverberatory furnaces.
(a) Charge not melted =roasting or calcining furnaces.
(b) Charge melted=melting furnaces.
(a) Heating chamber fixed and forming part of furnace= muffle furnaces.
(b) Crucible furnaces.
(c) Retort furnaces.
In this article the general principles of metallurgical furnaces will be treated; the subject of gasand oil-heated furnaces is treated in the article Fuel, and of the electric furnace in the article Electrometallurgy.
For special furnaces reference should be made to the articles on the industry concerned, e.g.
In the old copper-smelting district of Arabia Petraea, clay blast-pipes dating back to the earlier dynasties of ancient Egypt have been found buried in slag heaps; and in India the native smiths and iron-workers continue to use furnaces of similar types.
The development of blast furnaces is practically the development of iron-smelting.
Hearth furnaces are employed in certain metallurgical operations, e.g.
Blast furnaces are, from the intimate contact between the burden to be smelted and the fuel, the least wasteful of heat; but their use supposes the possibility of obtaining fuel of good quality and free from sulphur or other substances likely to deteriorate the metal produced.
Such furnaces are known by the general name of reverberatory or reverbatory furnaces, also as air or wind furnaces, to distinguish them from those worked with compressed air or blast.
Originally the term cupola was used for the reverberatory furnace, but in the course of time it has changed its meaning, and is now given to a small blast furnace such as that used by iron-founders - reverberatory smelting furnaces in the same trade being called air furnaces.
furnaces are connected with the same chimney stack, the damper takes the form of a sliding plate in the mouth of the connecting flue, so that the draught in one may be modified without affecting the others.
According to the purposes to which they are applied, reverberatory furnaces may be classed into two groups, namely, fusion or melting furnaces, and calcining or wasting furnaces, also called calciners.
Calcining furnaces have a less extended application, being chiefly employed in the conversion of metallic sulphides into oxides by continued exposure to the action of air at a temperature far below that of fusion, or into chlorides by roasting with common salt.
In some processes of lead-smelting, where the minerals treated contain sand, the long calciner is provided with a melting bottom close to the fire-place, so that the desulphurized ore leaves the furnace as a glassy slag or silicate, which is subsequently reduced to the metallic state by fusion with fluxes in blast furnaces.
Reverberatory furnaces play an important part in the manufacture of sodium carbonate; descriptions and illustrations are given in the article Alkali Manufacture.
A third class of furnaces is so arranged that the work is done by indirect heating; that is, the material under treatment, whether subjected to calcination, fusion or any other process, is not brought in contact either with fuel or flame, but is raised to the proper temperature by exposure in a chamber heated externally by the products of combustion.
These are known as muffle or chamber furnaces; and by supposing the crucibles or retorts to represent similar chambers of only temporary duration, the ordinary pot melting air furnaces, and those for the reduction of zinc ores or the manufacture of coal gas, may be included in the same category.
These are almost invariably air furnaces, though sometimes air under pressure is used, as, for example, in the combustion of small anthracitic coal, where a current of air from a fan-blower is sometimes blown under the grate to promote combustion.
Types of muffle furnaces are figured in the article Annealing, Hardening And Tempering.
The materials used in the construction of furnaces are divisible into two classes, namely, ordinary and refractory or fire-resisting.
The former are used principally as casing, walls, pillars or other supporting parts of the structure, and includes ordinary red or yellow bricks, clay-slate, granite and most building stones; the latter are reserved for the parts immediately in contact with the fuel and flame, such as the lining of the fire-place, the arches, roof and flues, the lower part if not the whole of the chimney lining in reverberatory furnaces, and the whole of the internal walls of blast furnaces.
In Belgium the clay raised at Andenne is very largely used for making retorts for zinc furnaces.
These bricks are specially used for the roof, fire arches, and other parts subjected to intense heat in reverberatory steel-melting furnaces, and, although infusible under ordinary conditions, are often fairly melted by the heat without fluxing or corrosion after a certain amount of exposure.
It has been found to stand well for the linings of rotatory puddling furnaces, where, under long-continued heating, it changes into a substance as hard and infusible as natural emery.
They are intended for use at the extreme temperatures obtainable in steel furnaces, or for the melting of platinum before the oxy-hydrogen blowpipe.
Ferric oxide, though not strictly infusible, is largely used as a protecting lining for furnaces in which malleable iron is made, a portion of the ore being reduced and recovered in the process.
In the construction of furnaces provision has to be made for the unequal expansion of the different parts under the effect of heat.
This is especially necessary in the case of reverberatory furnaces, which are essentially weak structures, and therefore require to be bound together by complicated systems of tie rods and uprights or buck staves.
Puddling furnaces are usually entirely cased with iron plates, and blast furnaces with hoops round each course of the stack, or in those of thinner constructions the firebrick work is entirely enclosed in a wrought iron casing or jacket.
Such parts as may be subjected to extreme heat and the fretting action of molten material, as the tuyere and slag breasts of blast furnaces, and the fire bridges and bed plates of reverberatory furnaces, are often made in cast iron with double walls, a current of water or air being kept circulating through the intermediate space.
This method has received considerable extension, notably in furnace-smelting of iron ores containing manganese, where the entire hearth is often completely water-cased, and in some lead furnaces where no firebrick lining is used, the lower part of the furnace stack being a mere double iron box cooled by water sufficiently to keep a coating of slag adhering to the inner shell which prevents the metal from being acted upon.
The introduction and withdrawal of the charges in fusion furnaces is effected by gravitation, the solid masses of raw ore, fuel and flux being thrown in at the top, and flowing out of the furnace at the taphole or slag run at the bottom.
With reverberatory calciners, however, where the work is done upon a horizontal bed, a considerable amount of hand labour is expended in raking out the charge when finished, and in drawing slags from fusion furnaces; and more particularly in the puddling process of refining iron the amount of manual exertion required is very much greater.
To diminish the item of expenditure on this head, various kinds of mechanical furnaces have been adopted, all of which can be classified under three heads of gravitating furnaces, mechanical stirrers and revolving furnaces.
In gravitating furnaces the bed is laid at a slope just within the angle of repose of the charge, which is introduced at the upper end, and is pushed down the slope by fresh material, when necessary, in the contrary direction to the flame which enters at the lower end.
There are many other furnaces in which the same principle is utilized.
Mechanical stirrers constitute a second division of mechanical furnaces, in which the labour of rabbling or stirring the charges is performed by combinations of levers and wheel-work taking motion from a rotating shaft, and more or less perfectly imitating the action of hand labour.
They are almost entirely confined to puddling furnaces.
Revolving furnaces, the third and most important division of mechanical furnaces, are of two kinds.
Furnaces of the second kind were first used in alkali works for the conversion of sulphate into carbonate of sodium in the process known as black ash fusion, but have since been applied to other processes.
Mechanical furnaces are figured in the article Alkali Manufacture.
In reverberatory and air furnaces used in the different operations of iron manufacture, where an extremely high temperature has to be maintained in spaces of comparatively small extent, such as the beds of puddling, welding and steel-melting furnaces, the temperature of the exhaust gases is exceedingly high, and if allowed to pass directly into the chimney they appear as a great body of flame at the top. It is now general to save a portion of this heat by passing the flame through flues of steam boilers, air-heating apparatus, or both - so that the steam required for the necessary operations of the forge and heated blast for the furnace itself may be obtained without further expenditure of fuel.
1 2 a In iron-smelting blast furnaces the waste gases are of considerable fuel value, and may render important services if properly applied.
Small air-furnaces with hot plates or sand bath flues were formerly much employed in chemical laboratories, as well as small blast furnaces for crucibles heated with charcoal or coke.
The use of such furnaces has very considerably diminished, owing to the general introduction of coal-gas for heating purposes in laboratories, which has been rendered possible by the invention of the Bunsen burner, in which the mixture of air and gas giving the least luminous but most powerfully heating flame is effected automatically by the effluent gas.
Furnaces of this kind may be used for melting cast iron or bronze in small quantities, and were employed by H.
It has mineral springs, and the industries comprise fisheries, ironworks and foundries, sulphur furnaces, silkmills, rope walks, match factories, brickworks, flourmills and furniture.
Both carbon and alloy steels are produced in electric arc furnaces and scrap rather than molten metal is used as the base material.
Carnforth Haematite Iron Company had four blast furnaces at work in 1870.
The new blast furnaces were technically superior and increased productivity.
Lewis, John H. The charcoal-fired blast furnaces of Scotland: a review.
early blast furnaces were tiny, maybe a dozen feet high, but modern ones have grown and grown to hundreds of feet.
The Lowther HÃ¦matite Iron and Steel Works are in close proximity to the Lonsdale Dock, and consist of three large modern blast furnaces.
Then the furnaces fire up to prepare the molten bronze - a mix with 22 or 23% tin is used.
cementation steel furnaces at Masbrough, tho the production of iron products remained their chief concern.
cupola furnaces installed here which were unusual in Yorkshire.
electric furnaced alloy steels are produced in electric arc furnaces and scrap rather than molten metal is used as the base material.
electric furnacecan produce over 100,000 tons per annum in two 90 ton electric arc furnaces.
bucket elevators move the " batch " into hoppers above the furnaces, from where the material is gravity fed into them.
Rotary Furnaces The Holwell site was later expanded to include a foundry to cast the pig iron produced by the furnaces.
Remains of these smelting furnaces were found among the slag pieces.
Coal fed the furnaces of British industry for 150 years.
More modem buildings were erected with modem machinery, including reverberatory furnaces and round buddles.
puddling furnaces were set up in the 1830's to meet the demand for malleable iron for the rail tracks for the railroad expansion.
These are small conical mounds or horseshoe shaped mounds of slag associated with bloomery furnaces geographically situated in the Highlands of Scotland.
Each ton of glass returned to the melting furnaces reduces our demand on raw materials by 1.2 tons.
Solar furnaces: solar radiation is concentrated on a small point by hundreds of reflecting surfaces called heliostats.
The heat soon became insupportable within the circle of furnaces, the rumbling of which resembled the rolling of thunder.
But you can still peer through the gates of the builders ' yard and see the engine manufactory and the great masonry furnaces.
puddling furnaces and rolling mills.
Three sizes of vacuum pyrolysis furnaces for cleaning screens, dies etc complete the range.
reheat furnaces are used to heat up slabs of steel produced by the blast furnace process or an electric arc process.
reverberatory furnaces and round buddles.
slag cakes is related to the size of the smelting furnaces, which must have been quite large.
smelting furnaces were found among the slag pieces.
smelting in granite furnaces fired with wood.
splint coal and blackband ore needed to feed these furnaces.
steeple of the parish church the flames of no fewer than fifty blast furnaces may be seen.
It is situated on the right bank of the Ostrawitza, near its confluence with the Oder, and it derives its importance from the neighbouring coal mines, and the blast furnaces and iron-works which they have called into existence.
The tanned complexion, that amorphous crag-like face; the dull black eyes under the precipice of brows, like dull anthracite furnaces, needing only to be blown; the mastiff mouth accurately closed; I have not traced so much of silent Berserkir rage that I remember in any man."
In many instances it has been replaced by mechanical furnaces, which are now common in roasting sulphide copper ores (see Sulphuric AcID).
The furnaces (fig.
The temperature required in the fusion of sheet-glass and of other glasses produced in tank furnaces is much lower than that attained in steel furnaces, and it is consequently pos Since the discovery of the RÃ¶ntgen rays, experiments have been made to ascertain the effects of the different constituents of glass on the transparency of glass to X-rays.
In practice, in these furnaces, it is possible for small local arcs to be temporarily set up by the shifting of the charge, and these would contribute to the heating of the mass.
In the remaining class of furnace, in which the electrical resistance of the charge itself is utilized, are the continuous-current furnaces, such as are used for the smelting of aluminium, and those alternating-current furnaces, (e.g.
In ordinary reverberatory and other heating furnaces the burning fuel is without the mass, so that the vessel containing the charge, and other parts of the plant, are raised to a higher temperature than would otherwise be necessary, in order to compensate for losses by radiation, convection and conduction.
The earth surface above these natural furnaces has been hardened, cracked and sometimes melted into a reddish slag, called scoria, which, on account of its resemblance to lava, has given rise to an incorrect impression that the region was once the centre of volcanic disturbances.
The ceaseless activity of the Black Country is most readily realized when it is traversed, or viewed from such an elevation as Dudley Castle Hill, at night, when the glare of furnaces appears in every direction.
As an artificial product, graphite is well known as dark lustrous scales in grey pig-iron, and in the "kish" of iron furnaces: it is also produced artificially on a large scale, together with .carborundum, in the electric furnace (see below).
The boiling down is most economically performed by means of large iron pans covered with a brick arch and heated from the top by the waste flame issuing from the black-ash furnaces (see figs.
The dry method consists in an oxidizing roasting of the ores, and a subsequent chloridizing roasting with either common salt or Abraumsalz in reverberatory or muffle furnaces.
Before the introduction of coal and coke as fuel in the forges and furnaces the cutting of young trees for the manufacture of charcoal was a profitable industry, and the process of deforestation reached its maximum.
The proximity of coalfields and iron mines has made Chattanooga an iron manufacturing place of importance, its plants including car shops, blast furnaces, foundries, agricultural implement and machinery works, and stove factories; the city has had an important part in the development of the iron and steel industries in this part of the South.
Such furnaces are very wasteful, and have little to recommend them (see Schnabel, Metallurgy, 1905, vol.
These burners, or modifications of them, have also been applied to muffle furnaces, which are convenient when only a few assays have to be made - the furnace being a mere clay shell and soon brought to a working temperature; but the fuel is too expensive to allow of their being used habitually or on a large scale.
The size of the slag cakes is related to the size of the smelting furnaces, which must have been quite large.
The invention of huge blast furnaces, capable of smelting iron, was the first step toward making of the new weapons of war.
The ore was then crushed with stones ready for smelting in granite furnaces fired with wood.
They had also acquired control of the lion's share of the vital splint coal and blackband ore needed to feed these furnaces.
From the steeple of the parish church the flames of no fewer than fifty blast furnaces may be seen.
We also recommend vacuuming all air ducts and changing filters in air conditioners and furnaces.
Class C RVs range between $5,000 to $100,000, depending on ownership status, size and integrated items like refrigerators and furnaces.
Peat, which is burned in furnaces, is an example of dirty coal.
Whole house furnaces, as part of a central air conditioning and heating system, are typically fueled by natural gas because it is one of the cleanest-burning fuels both readily available and inexpensive.
Since many basements, especially in older homes, were built for housing furnaces and storing vegetables, the staircases weren't built with comfort in mind.
These mixtures are heated in gas-fired furnaces.
In order to ensure that air flows through the air supply ducts, attention must be paid to the system's other parts, including furnaces, air conditioning pumps, registers, fans and coils.
This is due to the passing of a regulation by the Department of Energy (DOE) in 1992 to help control the amount of pollution being given off by gas powered furnaces.
Today's high efficiency furnaces are available with an AFUE of up to 96.7%, which translates into a serious savings on your gas bill each winter.
Since 1992, when the DOE tightened its standards, most furnace manufacturers have declared their furnaces to be "high efficiency", since they meet the minimum standard.
Truly high efficiency model furnaces can cost anywhere from $500 to $1000 more than mid-efficiency units.
However, provided these furnaces are installed properly, you can expect to see that money back very quickly in lowered gas bills that will continue over the life of the furnace.
Dry air, like that in airplanes or from forced hot air furnaces, can make the throat sore.
Nosebleeds occur more frequently in the winter when the air is cold outside and homes are filled with dry air from furnaces and other heating sources.
Today, Oreck sells several cleaning appliances such as vacuums, air purifiers, and personal furnaces.
Murano is primarily dedicated to its glassblowing industry, as it has been for several centuries (the glass furnaces were installed on this island in 1291).
Elba was famous for its mines in early times, and the smelting furnaces gave it its Greek name of A' OaNia ("soot island").
Bangor has various manufactures, the most important of which (other than those dependent upon lumber) are boots and shoes (including moccasins); among others are trunks, valises, saws, stoves, ranges and furnaces, edge tools and cant dogs, saw-mill machinery, brick, clothing, cigars, flour and dairy products.
A similar process is used in Carinthia; only the furnaces are smaller and of a somewhat different form.
In large works the silver-lead alloy is removed when it contains 60-80 silver, and the cupellation of the rich bullion from several concentration furnaces is finished in a second furnace.
The latest cupelling furnaces have the general form of a reverberatory copper-smelting furnace.
The efficiency of such ventilating furnaces is low, and they cannot safely be used in mines producing fire-damp. They are sometimes the cause of underground fires, and they are always a source of danger when by any chance the ventilating current becomes reversed, in which case the products of combustion, containing large quantities of carbon dioxide, will be drawn into the mine to the serious danger of the men.
On account of their dangerous character furnaces are prohibited by law in many countries.
Electrical furnaces have not as yet been employed for ordinary glass-making on a commercial scale, but the electrical plants which have been erected for melting and moulding quartz suggest the possibility of electric heating being employed for the manufacture of glass.
The word usage examples above have been gathered from various sources to reflect current and historial usage. They do not represent the opinions of YourDictionary.com.