Nickel matte

The matte can be treated in different ways, depending on the copper content and on the desired product. In some cases, the copper content of the Bessemer matte is low enough to allow the material to be cast directly into sulfide anodes for electrolytic refining. Usually it is necessary first to separate the nickel and copper sulfides. The copper—nickel matte is cooled slowly for ca 4 d to faciUtate grain growth of mineral crystals of copper sulfide, nickel—sulfide, and a nickel—copper alloy. This matte is pulverized, the nickel and copper sulfides isolated by flotation, and the alloy extracted magnetically and refined electrolyticaHy. The nickel sulfide is cast into anodes for electrolysis or, more commonly, is roasted to nickel oxide and further reduced to metal for refining by electrolysis or by the carbonyl method. Alternatively, the nickel sulfide may be roasted to provide a nickel oxide sinter that is suitable for direct use by the steel industry. 

Pyrometa.llurgica.1 Processes. Nickel oxide ores are processed by pyrometaHurgical or hydrometaHurgical methods. In the former, oxide ores are smelted with a sulfiding material, eg, gypsum, to produce an iron—nickel matte that can be treated similarly to the matte obtained from sulfide ores. The iron—nickel matte may be processed in a converter to eliminate iron. The nickel matte then can be cast into anodes and refined electrolyticaHy. 

Ma.nufa.cture. Several nickel oxides are manufactured commercially. A sintered form of green nickel oxide is made by smelting a purified nickel matte at 1000°C (30) a powder form is made by the desulfurization of nickel matte. Black nickel oxide is made by the calcination of nickel carbonate at 600°C (31). The carbonate results from an extraction process whereby pure nickel metal powder is oxidized with air in the presence of ammonia (qv) and carbon dioxide (qv) to hexaamminenickel(TT) carbonate [67806-76-2], [Ni(NH3)3]C03 (32). Nickel oxides also ate made by the calcination of nickel carbonate or nickel nitrate that were made from a pure form of nickel. A high purity, green nickel oxide is made by firing a mixture of nickel powder and water in air (25). 

Nickel sulfide concentrates are first subjected to an oxidizing treatment and then converted to nickel matte which is processed by hydrometallurgical methods. These methods have been indicated as A, C, and D in Figure 5.6. 

Nickel matte Nickel concentrate Exit gas Alloy scrap... 

Figure 6.28 Electroextraction of nickel from nickel matte anodes (principally based on Thompson Refinery Plant practice).

Oxidative pressure acid leaching is also applied to copper-nickel mattes. Nickel recoveries of >99% are obtained when leaching is carried out at 135-160 °C at oxygen partial pressures of 140-350 kPa,... 

In the Falconbridge process, copper-containing nickel mattes produced by preliminary pyro-metallurgical processing of ore concentrates (see Figure 2) are oxidized by chlorine in reactions in which Cu11 is responsible for electron transfer to the metal. 

Slow-cooled matte A process for extracting platinum metals from copper-nickel matte. The molten matte is cooled slowly, over several days. This causes the platinum metals to enter a nickel-iron phase which can be separated magnetically from the other components. Operated by Rustenberg Platinum Mines in South Africa, and INCO in Canada. 

Xu, B. and Huang, K., 1995. Role of a-amino aryl phosphorated organic depressant in flotation of high nickel matte. Nonferrous Metals, 1(47) 21-23 (in Chinese)... 

Copper-nickel matte obtained in this stage is allowed to cool slowly over a few days to separate mineral crystals of copper sulfide, nickel sulfide and nickel-copper alloy. The cool matte is pulverized to isolate sulfides of nickel and copper by froth flotation. Nickel-copper alloy is extracted by magnetic separation. Nickel metal is obtained from the nickel sulfide by electrolysis using crude nickel sulfide cast into anodes and nickel-plated stainless steel cathodes. 

Sulfide ores are processed by a number of pyrometallurgical processes roasting, smelting, and converting. During these processes, sulfur and iron are removed to deld a sulfur-deficient copper-nickel matte. Especially after roasting and converting, the nickel in the matte may consist primarily of nickel subsulfide. After physical separation of the copper and nickel sulfides, the nickel is refined electrochemically or by the carbonyl process. The treatment of the matte depends on the end use of the nickel. Alternatively, the sulfide can be roasted to form a nickel oxide sinter that is used directly in steel production. 

The composition of nickel matte has been studied by Bomemann (MetaUurgie, 1908, 5, 61), who shows that several double sulphides of iron and nickel are capable of existing pnder well-defined oopditions,... 

The Savelsberg-Wannschaff Process2 consists in treating with chlorine an intimate mixture of nickel matte and water or calcium chloride solution. The matte employed contains some 65 to 70 per cent, of nickel and some iron, but is, commercially speaking, free from copper. The solution thus obtained contains iron and nickel in the form of their chlorides. Sulphuric acid produced by the oxidation of the sulphur is thrown out as insoluble calcium sulphate. The liquid is filtered free from suspended matters, heated to about 65° C., and fresh powdered ore is added. A blast of air is now blown through, whereby the iron is oxidised and precipitated as insoluble ferric hydroxide. The clear solution containing nickel chloride is separated by filtration and electrolysed between graphite anodes and sheet metal cathodes, at a cathodic current density of 1-0 to 1-2 amperes persq. dem., and with a potential difference of from 4-0 to 4-5 volts. 

Double sulphides of iron and nickel are present in nickel matte, and are hence of commercial importance. Double sulphides with potassium, K2S.3NiS, and barium, BaS.4NiS, may be obtained by fusing nickel, sulphur, and an alkali at a high temperature.8 They are crystalline compounds. Cobalt yields only the sesquisulphide, Co2S3, in like circumstances. Nickel thus resembles palladium and platinum, whilst cobalt resembles rhodium and iridium in these respects. The position of nickel after cobalt in the Periodic Table thus receives further justification. 

Platinum from Nickel Matte.—Platinum occurs in traces in the nickel ores of Sudbury (see p. 82), and is to some extent recovered from these in commercial practice by more or less secret processes. During the fiscal year ending March 31, 1916, the Canadian Copper Company produced 56,405 tons of nickel matte, the average sample of which contains ... 

The application of ammonia pressure leaching as a method of refining nickel-cobalt matte has been studied (Bll, P3) and is considered an economically attractive process. Nickel-copper mattes with low cobalt content have been found to be readily leached with ammonia (P3). A high-nickel matte with a composition of 77% Ni, 0.1% Cu, 1.8% Co, 0.7% Fe, and 20% S is amenable to both acid and ammonia leach, but the sulfur deficiency can be made up more economically by circulation of ammonium sulfate solution within the process than by providing the sulfur through addition of sulfuric acid. 

Operation of the nickel matte refining cell is similar to that of the metal anode cell except that the anodes are enclosed in bags to collect the voluminous sludge. The cathodes are placed in conventional cathode compartments. The anode spacing... 

Precipitation of cobalt as sulfide is done in ammoniacal nickel matte leaching. From sulfate or sulfate/chloride solutions, cobalt is nowadays normally removed by using solvent extraction [46]. Phosphine-based solvent extraction reagents such as di-2-ethylhexylphosphoric acid (D2EHPA) are used to extract cobalt from nickel sulfate solutions. From pure chloride electrolytes, solvent extraction is done with a tertiary amine such as tri-isooctylamine. 

A variant of this process was developed in Australia by AUSMELT in 1998 their process used a closed induction furnace but with an air feed to bum the cadmium in the furnace and recover it in the form of cadmium oxide. The process produced nickel matte which had to be sent to the nickel refiners and highly contaminated cadmium oxides that had to be sent to the producers of primary cadmium. This required a higher investment than closed furnaces and the products extracted were somewhat less effectively recyeled than the nickel-iron and cadmium metal residues. 

Faye G.H., Inman W.R. The determination of platinum and palladium in copper-nickel matte and ore concentrates A fire assay method using tin as a collector. /Analytical Chemistry 1961 33 278-283. 

Work involving exposure to dusts, fumes and sprays produced during the roasting and electro-refining of cupro-nickel mattes. 

All industrial processes which are listed in aimex I of the carcinogens and mutagens directive 90/679/EEC, now 2004/37/EC (e.g., manufacture of auramine, work involving polycyclic aromatic hydrocarbons, roasting and electro-refining of cupro-nickel mattes, strong acid process for the manufacture of isopropyl alcohol, work involving exposure to hardwood dusts, see also Section 6.4). 

Y.Y. Sheng, G.A. Irons and D.G. Tisdale, Transport Phenomena in Electric Smelting of Nickel Matte Part I. Electric Potential Distribution, Met. Mater. Trans. B. Vol. 29B, 1998, 77-83. 

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