Nickel base metal recovery

Deposits. Selenium forms natural compounds with 16 other elements. It is a main constituent of 39 mineral species and a minor component of 37 others, chiefly sulfides. The minerals are finely disseminated and do not form a selenium ore. Because there are no deposits that can be worked for selenium recovery alone, there are no mine reserves. Nevertheless, the 1995 world reserves, chiefly in nonferrous metals sulfide deposits, are ca 70,000 metric tons and total resources are ca 130,000 t (24). The principal resources of the world are in the base metal sulfide deposits that are mined primarily for copper, zinc, nickel, and silver, and to a lesser extent, lead and mercury, where selenium recovery is secondary. 

Like selenium, tellurium minerals, although widely disseminated, do not form ore bodies. Hence, there are no deposits that can be mined for tellurium alone, and there are no formally stated reserves. Large resources however, are present in the base-metal sulfide deposits mined for copper, nickel, gold, silver, and lead, where the recovery of tellurium, like that of selenium, is incidental. 

The use of organophosphorus acids, such as di(2-ethylhexyl)phosphoric acid (D2EHPA di(2-ethylhexyl) monohydrogen phosphate 2 R = C4H9CH(Et)CH2), is now well established in the recovery of base metals. This reagent has found commercial application in the separation of cobalt from nickel,67 68 the separation of zinc from impurities such as copper and cadmium,69 the recovery of uranium,68 beryllium70 and vanadium,71 and in separations involving yttrium and the rare-earth metals.72 73... 

The use of solvating extractants in the recovery of gold and platinum-group metals (PGM) was described in the previous section. These extractants have also found some specialized applications in the extractive metallurgy of base metals. For example, they have been used in the recovery of uranium, the separation of zirconium and hafnium, the separation of niobium and tantalum, the removal of iron from solutions of cobalt and nickel chlorides, and in the separation of the rare-earth metals from one another. 

Most base-metal sulfides are very insoluble compounds and, in principle, processes based on the differences in their solubilities can be used in the selective precipitation of sulfides. For example, the strong affinity of copper ions for sulfide ion is used to good effect in the removal of traces of copper from leach liquors in the recovery of nickel,406 cobalt407 and manganese.408 For manganese, other impurity metal ions such as cobalt, nickel and zinc are also selectively precipitated by the use of sulfide ions. 

Methane sulfonic acid is used as an electrolyte for electroplating of tin onto sheet steel, for plating tin and tin/lead alloy onto nickel or other base metal substrates in the manufacture of lead frames and bump-contacts for microelectronic devices.It can also be used for copper deposition during the manufacture of microprocessors. Other alkanesulfonic acids have also found use in electroplating applications. Disodium methanedisulfonate and other alkanedisulfonate salts are used in chrome plating.As discussed previously, several processes for the recovery and recycle of alkanesulfonic acids from spent metal plating baths have been described. 

A recent and extremely important development lies in the application of the technique of liquid extraction to metallurgical processes. The successful development of methods for the purification of uranium fuel and for the recovery of spent fuel elements in the nuclear power industry by extraction methods, mainly based on packed, including pulsed, columns as discussed in Section 13.5 has led to their application to other metallurgical processes. Of these, the recovery of copper from acid leach liquors and subsequent electro-winning from these liquors is the most extensive, although further applications to nickel and other metals are being developed. In many of these processes, some form of chemical complex is formed between the solute and the solvent so that the kinetics of the process become important. The extraction operation may be either a physical operation, as discussed previously, or a chemical operation. Chemical operations have been classified by Hanson(1) as follows ... 

A conventional wastewater treatment system with an average flow rate of 160,000 gpd produces effluent suitable for NPDES discharge. Metal hydroxide sludges are dewatered in a 15 cu. ft filter press producing more than one half ton of filter cake per day. The filter cake is further dewatered in a 7 cu. ft, batch-type sludge dryer. Based upon recommendations by their consultant, the firm also uses the sludge dryer to dehydrate nickel strip solutions. Two reverse osmosis systems are used for partial nickel recovery. Trivalent chromium is recovered by drag-out control and evaporation. 

It is used in the mining industry to recover metals such as copper and nickel. Parasite plants, based on solvent extraction, are used in the phosphate industry to recover by-product uranium from crude phosphoric acid. The uranium concentration in phosphoric acid is very low but, because of the high volume of phosphoric acid that is produced to meet agricultural needs, considerable uranium can be recovered using solvent extraction. In the nuclear industry [5], solvent extraction is used to purify uranium and plutonium [using the plutonium and uranium recovery by extraction (PUREX) process], zirconium from hafnium, and for many other applications. It is also used in environmental applications to clean soil, say, to remove polychlorinated biphenyls (PCBs), dioxins, pesticides, and other hazardous pollutants. 

Cobalt and Nickel Recovery. Cobalt and nickel are relatively valuable metals often found in complex ores such as laterites or deep sea nodules. The metals can only be extracted from these ores by hydrometallurgy. A proposed recovery scheme based on coupled transport is shown in Figure 9.29. The first membrane contains LIX 54, which produces a nickel and copper concentrate and a cobalt raffinate stream. The concentrate stream is then passed to a second Kelex 100 membrane, which produces a copper and nickel stream. The cobalt III raffinate stream is neutralized and reduced to cobalt II, which can then be concentrated by a LIX 51 membrane. 

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