Nickel from sulfide ores

HydrometallurgicalProcesses. HydrometaHurgical refining also is used to extract nickel from sulfide ores. Sulfide concentrates can be leached with ammonia (qv) to dissolve the nickel, copper, and cobalt sulfides as amines. The solution is heated to precipitate copper, and the nickel and cobalt solution is oxidized to sulfate and reduced, using hydrogen at a high temperature and pressure to precipitate the nickel and cobalt. The nickel is deposited as a 99 wt % pure powder. 

Hybinette A process for extracting nickel from sulfide ores. The nickel ore that occurs in Canada is a mixture of the sulfides of nickel, copper, and iron. Several methods have been used to separate these metals. In the Hybinette process, the ore is first smelted in a blast furnace, yielding a nickel-copper matte (i.e., a mixture of their lower sulfides). This is roasted to remove sulfur and leached with dilute sulfuric acid to remove copper. The resulting crude nickel oxide is used as the anode of an electrochemical cell. The nickel deposits on the cathode, which is contained in a cloth bag. Precious metals collect in the anode slime. The process was invented by N. V Hybinette in 1904 and operated at the Kristiansand refinery, Norway, from 1910. 

Fig. 5. Flow sheet foi Sheiiitt-Goidon process for production of nickel and cobalt metals from sulfide ore.

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. 

More than 200 ores are known to contain cobalt but only a few are of commercial value. The more important are arsenides and sulfides such as smaltite, C0AS2, cobaltite (or cobalt glance), CoAsS, and linnaeite, C03S4. These are invariably associated with nickel, and often also with copper and lead, and it is usually obtained as a byproduct or coproduct in the recovery of these metals. The world s major sources of cobalt are the African continent and Canada with smaller reserves in Australia and the former USSR. All the platinum metals are generally associated with each other and rhodium and iridium therefore occur wherever the other platinum metals are found. However, the relative proportions of the individual metals are by no means constant and the more important sources of rhodium are the nickel-copper-sulfide ores found in South Africa and in Sudbury, Canada, which contain about 0.1% Rh. Iridium is usually obtained from native osmiridium (Ir 50%) or iridiosmium (Ir 70%) found chiefiy in Alaska as well as South Africa. 

Cadmium, as cadmium oxide, is obtained mainly as a by-product during the processing of zinc-bearing ores and also from the refining of lead and copper from sulfide ores (USPHS 1993). In 1989, the United States produced 1.4 million kg of cadmium (usually 0.6 to 1.8 million kg) and imported an additional 2.7 million kg (usually 1.8 to 3.2 million kg). Cadmium is used mainly for the production of nickel-cadmium batteries (35%), in metal plating (30%), and for the manufacture of pigments (15%), plastics and synthetics (10%), and alloys and miscellaneous uses (10%) (USPHS 1993). 

Mond nickel A process for extracting nickel from its ores by the intermediary of the volatile nickel tetracarbonyl. Sulfide ores are first roasted to convert sulfides to oxides and... 

H.4 Write balanced chemical equations for the following reactions (a) One process by which nickel is recovered from nickel(II) sulfide ores is to heat the ore in air. 

Mond nickel A process for extracting nickel from its ores by the intermediary of the volatile nickel tetracarbonyl. Sulfide ores are first roasted to convert sulfides to oxides, and then reduced by heating in hydrogen and carbon monoxide (water gas). The crude metal is caused to react with carbon monoxide at 50°C, producing Ni(CO)4, which is subsequently decomposed at 180 to 200°C. Invented by L. Mond and C. Langer in 1889, piloted at the works of Henry Wiggin Company in Smethwick, Scotland in 1892, and subsequently commercialized on a large scale in Swansea, South Wales, where it still operates (under the ownership of CVRD Inco). A new plant was built in Canada in 1986. 

In contrast to the extensive data collected on trace-mineralized rocks between ore districts, less information is available on the arsenic contents of the ore deposits. Because iron sulfide minerals are typically gangue phases, they are commonly ignored in trace element studies of ore deposits, which tend to focus on ore minerals such as sphalerite and galena. Therefore, there have not been extensive analyses for arsenic in iron sulfides in many of the MVT ore districts or trace-mineralized areas. However, a few studies on trace element contents in iron sulfides from the Ozark region have been performed. Wu et al. (1996) analyzed 80 pyrite and marcasite samples from the Viburnum Trend of the Southeast Missouri Lead District and found arsenic in concentrations of 2 to 900 ppm. Bhati and Hagni (1980) also analyzed iron sulfide minerals from this area, but did not publish results for arsenic. Hagni (1993) described the relatively rare occurrence of nickel-arsenic-sulfide ores from the Magmont-West ore deposit of the Viburnum Trend. Leach et al. (1995) list arsenic as a trace constituent in ores from the Northern Arkansas and Southeast Missouri MVT ore districts, but without abundances specified. 

These topics are discussed in detail in monographs and reviews (NAS 1975, IPCS 1991, Barceloux 1999, Mastromatteo 1986, Sunderman 1984, 2001a). Nickel constitutes less than 0.008% of the Earth s crust. The world s nickel production is obtained primarily from sulfide ores (e.g., pentlandite and nickeliferous pyrrhotite) and, to lesser extent, from oxides ores (e.g., laterite). Nickel sulfide ores, usually mined underground, are crushed and ground, concentrated by physical methods, converted to nickel subsulfide matte, and roasted to nickel oxide. The nickel oxide may be refined electrolytically to yield nickel cathodes or refined by the Mond process, which involves reduction with hydrogen, reaction with carbon monoxide to yield nickel carbonyl, and thermal decomposition to deposit pure nickel. Nickel oxide ores, usually mined in open pits, are smelted to produce ferronickel for use in stainless steel. 

Many of the non-ferrous metals such as copper, lead, zinc, and nickel are obtained from sulfide ores. One of the final stages of the extraction processes for these metals is the separation or removal of sulfur by roasting sulfur is recovered in the off-gases. 

Primary nickel is produced from both lateritic and sulfidic ores. Although currently the majority of nickel is produced from sulfidic ores, the production of nickel from lateritic ores is increasing and may overtake nickel production from sulfidic ores [1]. Lateritic ores are formed by prolonged weathering of ultramafic rocks. Typical mineralogical profile of nickel laterite ore bodies is as follows [2, 3] ... 

ACTIVOX A hydrometaUurgical process for extracting copper from sulfide ores, also suitable for nickel and gold. It involves fine grinding, low temperature, and low pressure. Developed in Australia by Western Minerals Technology, now Norilsk Process Technology. Piloted but not yet licensed. 

The treatments used to recover nickel from its sulfide and lateritic ores differ considerably because of the differing physical characteristics of the two ore types. The sulfide ores, in which the nickel, iron, and copper occur in a physical mixture as distinct minerals, are amenable to initial concentration by mechanical methods, eg, flotation (qv) and magnetic separation (see SEPARATION,MAGNETIC). The lateritic ores are not susceptible to these physical processes of beneficiation, and chemical means must be used to extract the nickel. The nickel concentration processes that have been developed are not as effective for the lateritic ores as for the sulfide ores (see also Metallurgy, extractive Minerals recovery and processing). 

Nickel sulfide, NiS, can be prepared by the fusion of nickel powder with molten sulfur or by precipitation usiag hydrogen sulfide treatment of a buffered solution of a nickel(II) salt. The behavior of nickel sulfides ia the pure state and ia mixtures with other sulfides is of iaterest ia the recovery of nickel from ores, ia the high temperature sulfide corrosion of nickel alloys, and ia the behavior of nickel-containing catalysts. 

PGM Concentration. The ore mined from the Merensky Reef in South Africa has a maximum PGM content of 8.1 g/1, of which 50—60% is platinum, and 20—25% palladium. The PGMs are in the form of a ferroplatinum alloy, or as their sulfides, arsenides, or teUurides. The aim of the concentration process is to separate from the ore a cmde metal concentrate, having a PGM content of 60%. The majority of other metals, such as nickel and copper, are separated out at this stage for further refining. 

In metallurgy, hydrogen sulfide is used to precipitate copper sulfide from nickel—copper-containing ore leach solutions in Alberta, Canada, or to precipitate nickel and cobalt sulfides from sulfuric acid leaching oflaterite ores in Moa Bay, Cuba (120) (see Metallurgy, extractive metallurgy). 

---