IRON 987 



In Styria and Austria, where the coke used is very impure, containing 3 per cent, 

 of sulphur, only about J to | of the total manganese is reduced. 



At Newark, in New Jersey, spiegeleisen is made from the residues obtained in the 

 treatment of the mixed zinc and iron ores of Franklin, in the same State. The ore is 

 an intimate mixture of franklinite and red zinc ore, with a massive green variety of 

 willemite or silicate of zinc. It occurs in crystalline limestone, forming an irregular 

 bed, which in places is 52 feet thick, the different minerals being very intimately 

 mixed. A mixture of finely-crushed ore, with lime and anthracite, is treated in au 

 oven-shaped calciner, having a cast-iron bed perforated with numerous narrow slits, 

 through which air is blown by a fan in sufficient quantity to burn the coal and 

 oxidisfe the zinc-vapour as it forms. The oxide of zinc produced in this process passes 

 through a long series of condensing-tubes and cooling-chambers, the current being 

 kept up by exhausting-fans until it is sufficiently cooled to be collected by bags made 

 of cotton cloth. The residue remaining in the furnace after the removal of the zinc is 

 a black cindery mass, containing the whole of the iron and manganese of the frank- 

 linite, and the silica of the willemite, besides some undecomposed zinc oxide : it is 

 estimated to contain 25 per cent, of iron, and 4 per cent, of zinc, and is smelted for 

 spiegeleisen. The furnaces employed are very small, being only 20 feet high, and 

 7 feet across the boshes ; the hot-blast is of about 200 temperature, and a pressure 

 of 4 Ibs. is used. The fuel used is anthracite, and some limestone is added as a flux. 

 Four blank charges of clean slags are made in twenty-four, to prevent scaffolding. 

 Great difficulty is experienced in working the furnaces, owing to the large amount of 

 zinc remaining in the ore, which deposits in the gas-flues at the throat, and necessi- 

 tates the use of an elaborate system of wrought-iron condensers for separating the 

 oxide of zinc from the gases, before they can be burnt in the hot-blast stoves and 

 steam-boilers. The oxide of zinc obtained in cleaning out the condenser being too 

 much discoloured to use as paint, is sent to the spelter furnaces for reduction, and 

 makes a very high quality of zinc. The consumption of fuel is very high, being at 

 the rate of 3^ tons per ton of iron. The weekly make of the furnace is about 25 

 tons. 



"When making spiegeleisen, the slags are of the usual bright-green colour charac- 

 teristic of manganese ; but when the furnace is too heavily burdened, and produces 

 No. 2 iron, corresponding to the German Weisstrahlig, the colour changes to a deep 

 brown. Owing to the large relative proportion of manganese to iron in the residues, 

 the spiegeleisen produced is very rich in manganese, and at times is said to contain as 

 much as 10 per cent. 



In connection with the production of spiegeleisen, sundry improvements in the 

 manufacture of manganese have been proposed. Among others, the following pro- 

 cesses are said to be most advantageously used in America : 



Manganese may be produced in a condition pure, or nearly so, without melting, and 

 used in the manufacture of ferrb-manganese and spiegeleisen in a manner producing a 

 better quality of product, in less time, and at less expense than by the old processes. 

 The process consists in a thorough mixture of pulverised oxide of manganese 10 parts, 

 and 3 parts of solid carbon, like coke or charcoal. These ingredients are inclosed in 

 metallic or earthen cases, large enough for the desired charge, and having the opening 

 temporarily closed with a metallic sheet, or covering of earth, to prevent the admis- 

 sion of air while allowing the escapement of gases. These cases are charged in an 

 ordinary furnace to a bright red, bare yellow, and are subjected to this heat for twelve 

 or fifteen hours, according to quantity. In the process the carbon unites with the 

 oxygen, and passes off as carbonic acid gas, and gives as a product nearly pure man- 

 ganese. To secure spiegeleisen the pig-iron is melted, and about 12 per cent, of the 

 manganese is charged into it and melted. The proportion of ingredients is run off 

 when melted into ingots, as spiegeleisen, when it is used in the ordinary way. Ferro- 

 manganese is produced by charging a greater per cent, of manganese into the molten 

 pig-metal, say 25 or 30 per cent. The manganese counteracts red shortness in the 

 steel, apparently by uniting with the free oxygen or metallic oxides which may be in 

 the steel, being particularly useful in the manufacture of boiler-plate steel. 



The inventor considers his process will be most valuable to those using an open 

 hearth steel-melting furnace, such as the Siemens, as it has been for a long time a 

 great desideratum to obtain a pure metallic manganese, especially in manufacturing 

 the softer grades of steel, such as roller-plate, tank-plate, &c. He claims that the 

 use of ferro-manganese conduces to the life of the furnace, because when rails are 

 desired containing from ^ to ^ of one per cent, carbon, the bath of molten metal has 

 to be run down in carbon as low as wrought iron, otherwise when the spiegeleisen is 

 added the percentage of carbon will be higher than desired, and also adding some 

 silicon, which is injurious. It is well known that a much greater heat is required to 

 keep a bath of molten metal liquid, containing no more carbon than wrought iron, 



