Electrolytic zinc plant

By far, the largest appHcation of zinc powder is for solution purification in electrolytic zinc plants. This appHcation consumed an estimated 17,700 t of powder in 1980. Zinc powder is also used in primary batteries, frictional materials, spray metallizing, mechanical plating, and chemical formulations. 

V. Ramachandran and co-workers, MLMRCOV Corpus Christi Electrolytic Zinc Plant, Hydrometallurgy Symposium, AIME, Adanta, Ga., 1983, p. 982. R. Capps and co-workers. Zinc Eead Kesidue Treatment and Solution Purification at the National Zinc Company, AIME, BardesviUe, OHa., 1984, paper A84-30. 

Peacey, J. G. Hancock, P. J. Review of pyrometallurgical processes for treating iron residues from electrolytic zinc plants. Iron Control and Disposal, Proceedings of the International Symposium on Iron Control in Hydrometallurgy, 2nd, Ottawa, Oct. 20-23, 1996, 17-35. 

Electrolytic zinc plants, 12 555 Electrolytic zinc process, 26 565-566 Electrolyzers, industrial, 18 281 Electromagnetic applications, for bulk materials, 23 865-870 Electromagnetic assisted material processing, 23 856-857 Electromagnetic brush (EMB) technology, 7 59... 

Air pollution problems and labor costs have led to the closing of older pyrometallurgical plants, and to increased electrolytic production. On a worldwide basis, 77% of total zinc production in 1985 was by the electrolytic process (4). In electrolytic zinc plants, the calcined material is dissolved in aqueous sulfuric acid, usually spent electrolyte from the electrolytic cells. Residual solids are generally separated from the leach solution by decantation and the clarified solution is then treated with zinc dust to remove cadmium and other impurities. 

V. Ramachandran and co-workers, ASARCO s Corpus Christi Electrolytic Zinc Plant, Hydrometallurgy Symposium, AIME, Adanta, Ga., 1983, p. 982. 

Over the period 1955-1961, the electrolytic plant processed only calcined zinc oxide having a composition of 60% Zn, 3-4% Pb and 0.03% Cd. The zinc oxide was produced by calcination of the fumes from the Waelz process at temperatures from 1420 to 1470 K. Zinc carbonate ores, Zn-Fe residues and other zinc-bearing materials were used as raw materials in the Waelz process. After enhancement of the electrolytic zinc plant in 1962, the importance of roasted sulphide concentrates was continuously growing in the feed. Currently, only the calcine from fluid-bed roasters is processed. Table I shows the analysis of the raw materials processed over the period 1998-1999. 

At the same time, changes were introduced in the feed residues from the electrolytic zinc plant are processed with some addition of zinc-bearing materials from the waste water treatment plant, and other secondaries like EAF dusts coming from steel mills (electric arc... 

Metal is separated from the drosses on a drum screen and is recycled to the furnace. Ashes are utilized in the production of Zn compounds. The BOLESLAW Electrolytic Zinc Plant produces zinc with the analysis shown in Table V. 

T. Yamada, R. Togashi and T. Aichi, Development of Automatic Material-Handling and Monitoring Systems in an Existing Electrolytic Zinc Plant, Aqueous Electrotechnologies. D. Dreisinger, Ed., The Minerals, Metals and Materials Society, Warrendale, PA, U.S.A., 1997,89-100. 

IMPROVEMENTS AT THE ELECTROLYTIC ZINC PLANT OF BIG RIVER ZINC CORPORATION, SAUGET, ILLINOIS, U.S.A. 

Significant modifications to the electrolytic zinc plant operated by Big River Zinc Corporation were made at the end of the 1990 s resulting in increased oqtacity and improved efficiencies. A new cell room, with the innovative use of acid-resistant concrete cells and a modem ventilation system, was installed to raise the capacity fiom 80,000 tonne/y to 106,000 tonne/y of finished zinc. Improvements to the leaching section include the conversion from a single to a two-step process, with associated equipment changes, to improve the quality of the residues produced. Another key change is the constmction of a facility to allow the use of zinc oxides fk>m secondary sources as a feed to the plant. This paper describes these improvements and the current operations. 

O.H. Bahne, R.K. Carpenter and C.R. Paden, Electrolytic Zinc Plant of American Zinc Company, AIME World Symposium on Mining Metallurov of Lead Zinc - Vol. II Extractive Metallurgy of Lead Zinc. C.H. Cotterill and J.M. Cigan, Eds., The Metallurgical Society of AIME, New York, NY, U.S.A., 1970,308-328. 

Apart from bulk concentrates, the remainder of the concentrates fed to ISP smelters tend to be materials that are less acceptable to electrolytic zinc plants or to straight lead smelters. Thus ISP smelters can bid competitively for zinc concentrates with high lead, magnesia or iron oxide levels or lead concentrates containing appreciable quantities of zinc. 

The ISP now accepts a wide range of secondary zinc materials including Waelz oxides, electrolytic zinc plant residues, galvanisers ashes and non-ferrous flue dusts. These materials are mainly either incorporated in the sinter plant feed or are hot briquetted and charged directly to the ISF. 

Environmental considerations play an increasingly important role in non-ferrous smelting. The ISP does possess an advantage in this context because it is a considerable consumer of wastes from other processes. Mention has already been made of the use of electrolytic zinc plant residues, steel plant dusts, galvanisers ashes and car battery paste. Nevertheless, in the operation of the ISP itself, great attention has to be paid to the avoidance of pollution of the working atmosphere the external atmosphere, and receiving waters. 

Operation of the Kidd electrolytic zinc plant commenced in 1972 with a cellhouse capacity of 105,000 tonnes of zinc cathode. The original cellhouse layout consisted of 42 parallel rows for a total of 588 cells. As leaching capacity increased, the cellhouse was expanded to 630 cells. Zinc cathode was manually stripped from plant start-up until the development of a mobile automated stripping system in 1994. Machine development continued until a second unit was placed in production in 1996, from which point, 60 % of the cellhouse was being stripped with the automated system. The final phase of the project was implemented in 1999 with the commissioning of two more automated strippers. This paper describes the implementation of the automated stripping system and its impact on cellhouse productivity. 

In a smelting process some of the contaminants that are a serious concern in electrolytic zinc plants e.g., Mn, Fe, Co, Ni, Ge, Hg are of minor consequence. The distribution of arsenic, antimony and bismuth cannot be fully defined imtil a prototype plant is operated, but a matte and an iron-rich slag should provide a good outlet for them. 

The process for treating the baghouse dusts consists of leaching the dusts with a sulphuric acid solution, generating a lead and silver residue as a by-product, which is returned to the lead smelter, and a zinc sulphate solution, that is purified to remove Pb, Fe, Cd and As. Zinc extraction is carried out by a solvent extraction process based on Lurgi technology. The zinc-rich solution obtained in the solvent extraction plant is sent to the electrolytic zinc plant for zinc recovery and an ammonium sulphate and chloride salt is obtained fix>m the raffinate for agricultural applications. The plant has a capacity of 5,000 totmes Zn/year. 

TREATMENT OF SECONDARY ZINC OXIDES FOR USE IN AN ELECTROLYTIC ZINC PLANT... 

In an electrolytic zinc plant, magnesium contained in the zinc concentrate becomes soluble and would accumulate in the electrolyte. Different techniques have been employed, such as the selective zinc precipitation process and the releaching of concentrates, to reject magnesium from the zinc circuit (2,3). The original design for magnesium control at the Pasminco Clarksville Zinc Plant was to strip the zinc content in the electrolyte from 55 g/l to about 25 g/l and then to bleed the stripped electrolyte, approximately 100 mVday, to the... 

I. G. Matthew, O. M. G. Newman and D. J. Palmer, Water Balance and Magnesium Control in Electrolytic Zinc Plants Using the E. Z. Selective Zinc Precipitation Process , TMS Paper Selection A-79-15. 1979. 

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