Improvements in iron manufacture

Improvements in iron manufacture

Improvements in Iron ~lanufacture. 65 •,he dissolved ferrocyanide of potassium as prussiate of protoxide of iron and potash, the above effect of the...

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Improvements in Iron ~lanufacture.

65

•,he dissolved ferrocyanide of potassium as prussiate of protoxide of iron and potash, the above effect of the carbon might be explained from a conversion of the per- into the protoxide of iron. 4. A solution of the perehloride of mercury, agitated sufficiently long with a suitable quantity of charcoal powder, is rendered tasteless and incapable of furnishing peroxide of mercury with solution of potash. The perchloride is converted under these circumstances into protochloride. 5. A dilute solation of pernitrate of mercury, perfectly free from protoxide, shaken but for a few minutes with charcoal powder, and then filtered, is rendered very turbid by muriatic acid or a solution of chloride of sodium arising from precipitated protochloride of mercury, which proves " •~hat the charcoal converts a portion of the pernitrate of mercury immediately into protosalt even in the cold. By shaking the same solution of pernitrate three or four times in quick succession with fresh portions of charcoal powder, I succeeded in obtaining, in the course of a quarter of an hour, a protosalt perfectly free from peroxide. This property of carbon may be usefiflly employed in freeing soluble protosalts of mercury from any admixture of persalt.~Poggendorfl's dtnnalen, Lxxvm. p. 521.

Improvements in Iron ~Ianufacture.* Sir F. C. Knowles has recently patented an improved method of making iron direct from the ore, which appears to be based on sound chemical principles. The patentee states that the method was suggested to him by a consideration of the fact that coal, in the process of coking, whether in coke ovens, or in the blast furnace, as raw coals~ loses a large portion of its weight in the form of gaseous matter, composed chiefly of carbon and hydrogen, and by considering the well-known superior deoxidizing and cementing power of these elements in the aeriform stat% as compared with their solid and crude condition in coke or bituminous coal. This loss is increased by the action of the blast on the materials in the lower parts of the blast furnace, which has been computed at upwards of eighty per cent. of the entire weight where raw coal is used. In addition to this, only the poor earthy ores have been used, while the nearly pure ores have been neglected; and we import foreign iron for the purpose of conversion into steel. For the first process--that of making the iron direct from the ore, without any previous smelting--the patentee selects those ores most free from earthy matter, and the nearer they approach to pure oxides the better. For another process--the preparing ores by cementation in retorts, to make cast-iron, by smelting afterwards--the ores are taken indifferentl excepting such as contain much sulphur and arsenic. They are fi~t broken into pieces of moderate siz% so as, when placed together in a heap, there may be interstices between them capable of admitting a gas, or vapor, through them without obstruction. They are then placed in" retorts~ rendered gas-tight, and brought up to a red heat, each Of which is connected ,~ith gas-tubes, having stop-cocks for the purpose of inject5 ~* From the LondonArtizan,for February, 1850. 6*

66 .

.Mechanics, Physics, and C/~mistry.

ing and regulating a current of gas among the ore. For this purpose two sorts of gases are used by the patentee--common carburetted hydrogen , or coal gas, and carbonic oxide, prepared by slow combustion of charcoal or coke. The patentee does not confine himself to coal gas, but employs any hydro-carbon which can be produced economically. When the retorts are charged, and the gas generated, the rationale of the process will be as follows:--The ore being mainly an oxide of iron, the hydrogen of the kydro-carbon unites with the oxygen of the ore to form water, while the carbon unites with another portion of oxygen, forming carbonic oxide Or carbonic acid, as the case may be, leaving metallic iron as the result, The ore being so far reduced, the next stage of the process, when malleable iron is the proposed product, is to shut off the gas on both sides of the retorts, and transfer the contents of the retorts to the puddling furnace, where the iron is treated in the common way. It may be cut, piled, reheated, and rolled as usual, according to the nature of its distinction or quality required. If steel be required, the cementation must be carried further, until the reduced metal has absorbed about 1 percent, of carbon. The reduced and cemented ore is then put into crucibles, or melting pots, to be run down into ingots in wind-furnaces, as is now done in the making of east steel. If the earthy matter in the ore require it, some proper flux is to be added; according to the usual method of fluxing iron ores. If east iron be required, the cementation must be carried on until about 3 or 4 per cent. of carbon is absorbed, after which it is transferred to the blast furnace, with a proper flux. The patentee further claims, where cast iron ,or steel is the product required, the separate cementation of iron ores with charcoal, coke dust, anthracite coal, coke,&c., on the following iron ores:--Pure specular ore, red and brown hematite, black oxide, red and brown ochreous ores, magnetic iron ores~ spathose ores, being carbonates of protoxide of iron, and different from the argillaceous iron ores of the carboniferous series of rocks above the mountain limestone. Lastly, the patentee claims the use of spathose iron ores and "soft mine" as a flux, to supersede the use of limestone; the ore is first roasted, to drive out the carbonic acid, and then mixed with other ores in such proportion that the lime contained in the ,aggregate may bear a due proportion to the silica and alumina in the other iron ores to be smelted. Translated for the Journalof the Franklin Institute.

Construction of the Bunsen (Carbon) Battery. M. Delenil suggests ( Comptes Rendus de l'.3cad, des Sciences de Paris, 15th .~pril, 1850,) a modification in the construction of the Bunsen (carbon) battery which is simple and important. The modification consists in replacing the metal collars which rapidly corrode and oxidize, by glass collars, which resist the corrosive action of acids, and thus will ensure almost indefinite duration to these instruments. It may be remarked that these glass collars can support a pressure from within, outwards; that is, upon :the wedge in contact with the carbon of 240 lbs.