The conversion of the refined matte into crude nickel.

The so-called Orford process for separating copper and the nickel, devised by J. L. Thomson, R. M. Thompson, and C. C. Bartlett, in 1893, is practised at the Orford Company's Works, at Constable Hook, New Jersey. The process was described by V. von Ehrenwerth. The process depends on the fact that copper sulphide combines with an alkali sulphide, forming a fusible double sulphide, whilst nickel sulphide does not do so; consequently, if a mixture of copper and nickel sulphides be fused with an alkali sulphide and allowed to cool, it will separate into two layers, with most of the copper above, and most of the nickel below. The two products are tapped separately from the melting-furnace. The charge is a mixture of sodium sulphate and coke which forms alkali sulphide in the furnace. By repeating the process on the bottom layer, a mixture of iron and nickel sulphides is produced. The top layers of both operations are allowed to weather and are then fused with more matte, the bottom layer is returned to be treated with the. second fusion with alkali sulphide, while the top layer is leached with water to recover the alkali sulphide by evaporating the soln. to dryness. The insoluble sulphide is then treated for copper. The nickel sulphide still contains iron. It is roasted to remove some of the sulphur, and then melted. This furnishes nickel sulphide freed from iron sulphide and a slag of ferrous silicate mixed with some nickel, and it is rejected. The nickel sulphide is roasted, and a little nitre is added to complete the oxidation, and a little common salt to convert any copper into the chloride. The roasted oxide is washed with water, and it is then ready for reduction to metal. Any platinum metals in the matte are also converted into chlorides during the chloridizing roast, and they pass into soln. during the leaching process. The nickel oxide can be reduced as indicated below. Two samples of nickel oxide obtained from Canadian matte had the compositions:

		(Ni,Co)O	CuO	Fe2O3	As	S	SiO3
Nickel Oxide	I	97.5	0.4	1.5	0.3	0.03	0.3
	II	98.74	0.30	0.70	0.04	0.02	0.20

The so-called Mond process, devised by L. Mond and C. Langer, in 1889, depends on the formation and decomposition of volatile nickel and iron carbonyls under conditions where copper does not form a gaseous carbonvl. The bessemerized matte is crushed and roasted, in the roaster, to produce it as free as possible from sulphur. The crushed and screened product is treated with dil. sulphuric acid which removes about two-thirds of the copper oxide and about 1 per cent, of nickel oxide. The residue contains 45 to 60 per cent, of nickel oxide. The soln. is evaporated and the copper sulphate crystallized out; the iron and nickel sulphates accumulate in the mother-liquor, which is then evaporated to dryness, heated to decompose the sulphate, and the oxides introduced into the main process. The washed and dried residue, containing copper, nickel, and iron oxides, is treated with water- gas, in the so-called reducer, at a temp, below 300°; this reduces the nickel and copper oxides, but not the iron oxide. The product at 50° is then treated with carbon monoxide - obtained by passing the gas from the reducer over red-hot coke. The gas containing nickel carbonyl is then passed through a filter and into a chamber, the decomposer, at about 200°, when the nickel carbonyl is decomposed with the separation of nickel; the regenerated carbon monoxide returns to the volatilizer. The decomposer is a tower containing nickel shot. A layer of nickel forms on the shot. To prevent the granules adhering, they are kept in motion by the constant withdrawal of some of them from the bottom of the decomposing tower by means of a worm conveyor. The granules are passed over a screen. The larger shot are removed, and the smaller ores return to the top of the tower to receive another deposit of nickel. The shot being alternately exposed to and withdrawn from the action of this gas, a series of concentric rings of nickel are deposited about the original nucleus. When a Mond-nickel shot is hammered on an anvil, the various coatings will be broken open, and its structure revealed. The residue in the volatilizer still contains some nickel; and it is returned to the reducer. When most of the nickel has been extracted the residue is returned to the roaster. The process was described by A. P. Coleman, W. C. Roberts-Austen, and G. B. Shipley. Two specimens of nickel obtained by the Mond process had the composition:

		Ni	Fe	S	C	Insoluble
Nickel	I	99.82	0.10	0.0068	0.07	-
	II	99.43	0.43	0.0099	0.087	0.026

Other methods have been suggested for treating the refined copper-nickel matte. V. von Ehrenwerth described a method for removing copper from nickel mattes by blowing in a converter with a lining of a basic material or coke. The iron is first slagged off, then the nickel, and the copper separates out lastly as metal. The process has not been successful. S. H. Emmens proposed a chloridizing roasting of the matte in the presence of steam; extracting the chlorides of copper and other metals with water; and smelting the residue of nickel and iron oxides with sodium sulphide, and charcoal. The nickel matte is roasted, and the resulting nickel oxide reduced to metal. N. V. Hybinette and A. R. Ledoux proposed to separate nickel from its molten matte by adding manganese dioxide, because, under these conditions, manganese and copper combine more readily with sulphur than is the case with nickel. The nickel and its sulphide settle to the bottom, and the layer of sulphides of copper and manganese float on top. The upper layer is removed and the residue again treated with manganese. This completes the isolation of the nickel. The top layers are used for the extraction of copper and manganese.

If the enriched matte be roasted, and the resulting oxide reduced by carbon, an alloy of nickel and copper is formed which may be used for making German silver, or other alloys. The process was described by D. Levat, C. A. M. Balling, C. Schnabel, and G. P. Schweder. Analyses of the nickeliferous copper - Garkupfer - were reported by C. Schnabel, F. A. Genth, G. W. Wille, F. Heusler, G. P. Schweder, C. A. M. Balling, G. Hamprecht and L. Schlecht, and V. Tafel and F. Kleweta. The compositions of a refined matte and the resulting alloy were:

	Ni	Cu	Fe	S	As,Sb
Refined matte	32.59	52.00	0.41	17.71	0.11
Alloy	39.95	59.5	0.64	-	-