Electrowinning of zinc

Zinc. The electrowinning of zinc on a commercial scale started in 1915. Most newer faciUties are electrolytic plants. The success of the process results from the abiUty to handle complex ores and to produce, after purification of the electrolyte, high purity zinc cathodes at an acceptable cost. Over the years, there have been only minor changes in the chemistry of the process to improve zinc recovery and solution purification. Improvements have been made in the areas of process instmmentation and control, automation, and prevention of water pollution. 

Electrowinning The earlier works on electrowinning of zinc from ore or waste are well described [92]. 

Traditionally, glues [362, 381-383] and arable gum [384] were used as organic additives in the electrowinning of zinc. Hosny [385] and Karavasteva et al. [386, 387] used surfactants to improve the deposit morphology and current efficiency. 

Lead-cobalt anodes used for electrowinning of zinc from sulfate solutions were investigated by Rashkov et al. [404]. 

The extracted zinc is transferred to a sulfate medium, which is preferred for the electrowinning of zinc, by stripping with a solution containing sulfuric acid (being spent electrolyte from the electro winning plant) ... 

Cementation, the process by which a metal is reduced from solution by the dissolution of a less-noble metal, has been used for centuries as a means for extraction of metals from solution, and is probably the oldest of the hydrometallurgical processes. It is also known by other terms such as metal displacement or contract reduction, and is widely used in the recovery of metals such as silver, gold, selenium, cadmium, copper and thallium from solution and the purification of solutions such as those used in the electrowinning of zinc. The electrochemical basis for these reactions has been well established414 and, as in leaching reactions, comprises the anodic dissolution of the less-noble metal coupled to the cathodic reduction of the more-noble metal on the surface of the corroding metals. Therefore, in the well-known and commercially exploited44 cementation of copper from sulfate solution by metallic iron, the reactions are... 

The electrowinning of zinc is done from highly acidic-purified electrolyte. Purification of the solution is done by adding... 

Today, hydrometaUurgy is well established as the principal method for extraction of many important industrml metals. Hydrometallurgy for the direct treatment of base metal sulfide concentrates, as a widely used technology, must yet prove itself. The roast-leach electrowinning of zinc is a noteworthy exception and is evolving as standard practice hi the zinc industiy worldwide. Relatively recent developments by way of jarosite and iron oxide hydrolysis and precipitation processes have improved recovery and helped secure zinc hydromemllurgy as standard in the industiy.w... 

H. Nozaka, K. Tozawa, and Y. Umetsu, "Improvement of Behavior of Lead Alloys as Insoluble Anode for Electrowinning of Zinc in Acidic Sulfate Solutions", Zinc and Lead 95. T. Azakami, N. Masuko, J. E. Dutrizac, and E. Ozberk, Eds., The Mining Materials Processing Institute of Japan, Tokyo, Js )an,1995,384-393. 

SPOUTED BED ELECTROWINNING OF ZINC FROM CHLORIDE ELECTROLYTES... 

M. Karavasteva and St. Karaivanov, Electrowinning of Zinc at High Current Density in the Presence of Some Surfactants, J. Annl. Electrochem.. Vol. 23,1993, 763-765. 

Saba AE, Elsherief AE (2000) Continuous electrowinning of zinc. Hydrometallurgy 54 91— 106. doi 10.1016/S0304-386X(99)00061-4... 

Electrowinning of zinc. The electrowinning of zinc from the mother liquor is performed in an electrolyzer made of PVC whose operating parameters are presented in Table 3.23. 

Karavasteva, M. Karaivanov, St. (1993) Electrowinning of zinc at high current density in the presence of some surfactants. /. Appl. Electrochem., 23(7), 763-765. 

Salas-Morales JC, Evans JW, Newman OMG, Adcock PA. Spouted bed electrowinning of zinc Part 1. Laboratory-scale electrowinning experiments. Metall Mat Trans B 28 59-68, 1997. 

Figures 7.9 shows a 3-D surface plot of Bestetti el at. [14] reported data on electrowinning of zinc. This 3-D plot indicates that energy consumption (7) decreases with increasing efficiency e at fixed values of potential E. On the other hand, keeping e constant, 7 increases with increasing E. Therefore, the...

Electrowinning of zinc is from sulphuric acid leach. The solution is purified from more noble metals by two methods one is to add scrap iron, oxidize it to the ferric state which is precipitated, carrying down many impurities. The other method is to add zinc dust, thus precipitating the more noble metals. Cadmium, as well as other metals, are usually recovered at this stage. The electrolysis is between lead-silver anodes and aluminium cathodes the product is generally 99-9% pure. 

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