From sulfides

AH the operations in the winning of copper from sulfide ores are controUed oxidations using air or oxygen. An important effort has been made to... 

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

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. 

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. 

Silver sulfate decomposes above 1085°C into silver, sulfur dioxide, and oxygen. This property is utilized ia the separation of silver from sulfide ores by direct oxidation. Silver sulfate is reduced to silver metal by hydrogen, carbon, carbon monoxide, zinc, and copper. 

Metallurgical (smelter) plants and spent acid decomposition plants usually produce acid of good (low) color because the SO2 feed gases ate extensively purified prior to use. In some cases, however, and particularly at lead smelters, sufficient amounts of organic flotation agents are volatilized from sulfide ores to form brown or black acid. Such acid can be used in many applications, particularly for fertilizer production, without significant problems arising. 

Cupric ion concentration is kept at an acceptable but low level by direct air oxidation of the solution. SoHds formation from sulfides in the feed gas is also possible therefore, pretreatment for sulfur removal is required. 

Fig. 1. Recovery of copper from sulfide ore. The residue from electrolytic refining is processed to recover gold, silver, and selenium. Courtesy of Kennecott...

When alloy steels do not give adequate corrosion protection— particularly from sulfidic attack—steel with an aluminized surface coating can be used. A spray coating of aluminum on a steel is not likely to spall or flake, but the coating is usually not continuous and... 

A few of the oxide ores of copper can be reduced directly to the metal by heating with coke, but the bulk of production is from sulfide ores containing iron, and they require more complicated treatment. These ores are comparatively lean (often 0.5% Cu) and their exploitation requires economies of scale. They are therefore obtained in huge, open-pit operations employing shovels... 

The isolation of zinc, over 90% of which is from sulfide ores, depends on conventional physical concentration of the ore by sedimentation or flotation techniques. This is followed by roasting to produce the oxides the SO2 which is generated is used to produce sulfuric acid. The ZnO is then either treated electrolytically or smelted with coke. In the former case the zinc is leached from the crude ZnO with dil H2SO4, at which point cadmium is precipitated by the addition of zinc dust. The ZnS04 solution is then electrolysed and the metal deposited — in a state of 99.95% purity — on to aluminium cathodes. 

Sulfinic esters, aromatic, by oxidation of disulfides in alcohols, 46, 64 Sulfonation ot d,l camphor to d,l-10-camphorsulfomc acid, 45,12 Sulfoxides, table of examples of preparation from sulfides with sodium metapenodate, 46,79 Sulfur dioxide, reaction with styrene phosphorus pentachlonde to give styrylphosphomc diclilonde, 46,... 

Cyclohexenyl-, (l-cyclohexenylmethyl)lithium and others are prepared in good yields from sulfides with lithium naphthalenide or lithium 1-(dimcthylamino)naphthalenide32. 

The halide is not the only metal compound used as source of metal. Metal oxides and sulfides are employed to prepare vanadium, chromium, iron and nickel borides in this way from sulfides at lower reaction T than those required by reaction sintering of the elements . 

Today, zinc and other metals can be extracted from sulfides by aqueous conversion processes that avoid the generation of SO2. Aqueous acid reacts with the sulfides to generate free sulfur or sulfate ions rather than SO2. ... 

Changing the substrate from gold to silver has been shown to strongly affect the structure of the first few layers of CdS grown by ECALE. STM measurements carried out on the first CdS layer on Ag(lll) revealed a much less compact structure than the one found on Au(lll). This disparity was tentatively attributed to the different structure of the first S layer on Ag(l 11), as obtained by oxidative UPD from sulfide ion solutions, due to a higher affinity of sulfur for silver than for gold. The Cd layers were attained on S by reductive UPD from cadmium ion solutions. Precursors for both elements were dissolved in pyrophosphate/NaOH at pH 12 [43 5],... 

Before examining selenium in some detail, as an illustration of the phenomena under consideration, let us note here that although oxidative UPD of sulfur can be achieved from sulfide solutions, the oxidative UPDs of Se and Te are complicated by the fact that, unlike sulfides, the Se and Te species are not very stable in aqueous solutions they tend to react with even traces of O2, to form the corresponding element. 

Marutani and Takenouchi (1978) clarified the variations in homogenization temperature and salinity of inclusion fluids in quartz from stockwork siliceous orebodies at the Kosaka mine (Fig. 1.35 Urabe, 1978). They showed that the temperature decreases stratigraphically upwards from stockwork ore zone (280-320°C) to bedded ore zone (260-310°C). Pisutha-Arnond and Ohmoto (1983) carried out fluid inclusion studies of the stockwork siliceous ores from five Kuroko deposits (Kosaka, Fukazawa, Furutobe, Shakanai, and Matsumine) and revealed that black ore minerals (sphalerite, galena, barite) and yellow ore minerals (chalcopyrite, quartz) formed at 200-330°C and 330 50°C, respectively, and salinities of the ore fluids remained fairly constant at about 3.5-6 equivalent wt% NaCl. They analyzed fluids extracted from sulfides and quartz Na = 0.60 0.16 (mol/kg H2O), K = 0.08 0.05, Ca = 0.06 0.05, Mg = 0.013 0.008, Cl = 0.82 0.32, C (as CO2) = 0.20 0.15 and less than 6 ppm each for Cu, Pb, Zn and Fe. 

Contributions both from sulfide sulfur leached from volcanic rocks and marine sulfate in Green tuff. 

Alkyllithium reagents can also be generated by reduction of sulfides.32 Alkenyl-lithium and substituted alkyllithium reagents can be prepared from sulfides,33 and sulfides can be converted to lithium reagents by the catalytic electron transfer process described for halides.34... 

Blister copper, produced from sulfide ores by matte smelting and converting, is refined to the grade known as tough pitch copper by a multistage operation known as fire refining. 

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