:METALLURGY. When niekcliferous ores of lead, cobalt. copper, or silver containing arsenic are smelted. the nickel combines with the arsenic to form speiss: should arsenic not be present. the nickel enters the various intermediate products of the smelting process., such as matte, blister cop per, tough pitch copper, and dyes. From all these metallurgical products nickel may he extracted as well a, from the ore,. The principal ores from which nickel is extracted are the sulphur COM p01111(1, and the silicates. The chief sulphur com pounds are the nickel pyrites of iron and copper, of which one of the most notable deposits is at Sudbury, Canada. The Sudbury ores are the principal source of the world's nickel supply.
The extraction of nickel is performed by (1) the dry method, (2) the wet method, and (3) eleetro-metallurgically. The dry method is the one chiefly used to extract the metal from the ores, the use of the wet method and eleetro metallurgical proeesses being confined almost entirely to extraction from metallurgical products and time matte and spei,s resulting from the dry processes. Most attention will therefore be given to the dry method of extraction as applied to the principal ore of nickel; that is, the com bined nickel, iron, and copper pyrites. In smelt ing these ores in the dry way, after getting rid of the gangue, the metallurgist is chiefly (4)1mA-tied with the separation of the nickel from the sulphur, iron, and, in most cases, from the copper also. When no copper is present the process becomes simple. Considering first ores free from copper, the task is to get rid of the iron and sulphur. The first operation consists in roasting the ore, which converts the metallic sulphides into a mixture of oxides., sulphates, and
undecomposed sulphides. The roasted ore is then smelted in a shaft furnace with coal and siliveous matter, which removes the great bulk of the iron as slag, leaving a matte consisting of sulphide of nickel mixed with a small proportion of iron sulphide. Generally, to get a matte rich enough in nickel for the succeeding operations, these roasting and smelting processes are re peated one or more times. The raw nickel matte is next submitted to an oxidizing fusion in hearths, reverberatory furnaces, or converters to remove the remaining iron, leaving nickel sul phide. When copper is present in the ores as well as iron, the iron is removed exactly as before, the result being, however, a matte of nickel sulphide and copper sulphide mixed. This matte may be oxidized by roasting and then smelted to produce a nickel-copper alloy, or to secure nickel alone the matte is smelted with a Ibex, which the copper. or is treated with chemicals, which permit time separation of the copper. This latter method is the chief use made of the wet method of reduction. which, as previously stated, is used mostly for reducing the mattes, speiss, and slags resulting from the smelling process. As in wet methods of extrac tion g,enerally, the process in time case of nickel consists in dissolving the metals from the matte, etc., by acids. and than in precipitating sepa rately the various metals from this solid ion. The nickel compounds resulting from the proc esses mentioned are redneed to metallic nickel by smelting in crucibles with variant. See 1)r. Carl Schnaldt.'s Handbook of Metallurgy (New York, 1898),