A Treatise on Metallurgy: Comprising Mining, and General and Particular Metallurgical Operations : with a Description of Charcoal, Coke, and Anthracite Furnaces, Blast Machines, Hot Blast, Forge Hammers, Rolling Mills, Etc., Etc

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D. Appleton & Company, 1865 - Metallurgy - 723 pages
 

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Page 312 - ... zinc are familiar examples. Both these metals are remarkable for their extreme volatility, the first especially so : hence the process of metallurgy adopted in their production is not one of smelting, properly so called, or of roasting as popularly understood, but as one of veritable distillation. Mercury is frequently produced by simple sublimation, without the addition of flux or coal, so also is arsenic; but in most instances carbon, and such substances as decompose the ore, are added. In...
Page 677 - Fio. 348. iron plates are generally used below the tuyere, and are lined with clay or coal-dust, but both these materials for linings are injurious as well to the quality of the metal as to the yield. There cannot be any disadvantage in surrounding a slag hearth with cooled iron plates, similar to a run-out fire for refining iron.
Page 673 - ... may take place. So long as the fluidity of the slag is continued, lead is formed. To render this operation profitable, fluate of lime should be used in a considerable quantity; but as this cannot be obtained always, we propose the substitution of chlorine for fluorine, which possesses in as high a degree as the latter the quality of fluxing sulphates. In this instance, gypsum and common salt may be pulverized together when damp. These form a very fluid slag with barytas, lime, iron, and other...
Page 654 - About a ton of ore is smelted in a day of eight hours. The metal is remelted, cast into iron moulds in the form of ingots, and is now ready for the market. The metal thus obtained is not pure ; but it may be purified by remelting in a flat earthen, or rather a. bone ash-dish, at a low heat, removing the dross as it appears on the surface of the metal. It is advisable to melt the metal thus obtained in a purer form in a blacklead pot, and then cast it into the mould for ingots. Bismuth cannot be freed...
Page 40 - ... be sufficiently large to prevent a permanent bend in the iron. On the opposite side of the windlass is a lever of unequal leverage about one-third at the side of the hole, and two-thirds at the opposite side, where it ends in a cross or broad end in case men do the work. The workmen, with one foot on a bench or platform, rest their hands on a railing, and work with the other foot the long end of the lever. In this way the whole weight of the men is made use of, who work with great ease. The lift...
Page 432 - ... absorb nearly the same quantity of oxygen in forming their oxydes. Nearly all chemical combinations liberate heat. Zinc and copper, when melted together, produce a high temperature. Where a mere mechanical mixture of metals occurs in an alloy, it is characterized by distinct crystals being formed with one metal, between which the other is visible. When an alloy is formed with proper equivalents, no such disconnected crystals are observed. In cooling a melted alloy, that composition which is most...
Page 677 - At the smelting furnaces, particularly at those where the operation is performed at a high heat, a white smoke is thrown out at the tymp, or at the top of the furnace. This may be gathered in condensing chambers, as shown in fig. 349. Similar chambers may be annexed to reverberatories, as will be shown hereafter. This white smoke contains those metals which are in the ore. A reddish dust from a...
Page 667 - ... per cent, of the lead ore primarily charged. This addition stiffens the slag ; which is now withdrawn from the furnace, and subjected to resmelting in the slag-hearth. Nearly all the lead is obtained from the slags in this last operation. In Germany generally the ores are purified by hand ; washed, stamped, and washed again, and roasted with salt, or iron, or iron ore. The roasted ore is smelted in blast-furnaces, which are from 12 to 14 feet high.
Page 465 - NH, furnished 3'1 per cent. As blende is a very common ore in this country, it may be worth while to pay some attention to this ingredient of it. Cadmium is a beautiful metal ; it has the color and lustre of tin, and is susceptible of a fine polish. It is soft, malleable, and soils the fingers or paper like lead ; it is harder and stronger than tin, and produces the tin-cry like that metal. Cadmium is very ductile ; it may be drawn into wires, or hammered into foil like copper ; its sp. gr. is 8'6....
Page 677 - ... both these materials for linings are injurious as well to the quality of the metal as to the yield. There cannot be any disadvantage in surrounding a slag hearth with cooled iron plates, similar to a run-out fire' for refining iron. A little more fuel may be used in smelting, but a more fluid cinder can then be employed than in any furnace, which of course tends to economize fuel ; and causes a purer article of metal. Furnaces of this kind were used in the State of New York, and worked successfully....

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