Hydrometallurgical method

Although substantial work has been carried out on the recovery of lead from battery residues by electrolytic means, no system has been adopted for large-scale commercial operations. Companies such as Engitech Impianti in Italy and RSR in the USA have patents on electrolytic systems, whilst a European consortium, led by Tecnicas Reunidas in Spain, has developed the chloride-based PLACID and FLINT lead recovery processes. 

Electrolytic processes can potentially produce lead of greater purity than secondary pyrometallurgical routes, without passing through a conventional smelting and refinery process, and they have fewer waste products. The disadvantage of this type of operation is the high cost of electricity and/or other consumables that are needed to yield a metal that is often priced at below US 500 per tonne. 

In all of the above processes, pre-treatment of the battery paste is required so that compounds, such as lead sulfate and lead dioxide, can be accessed by electrolytic methods. Short summaries of the three processes are given below. 

These technologies may prove to be of importance in the future, as environmental regulations become tighter and place more emphasis on cleaner processes and minimizing hazardous waste arisings. 

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Nickel sulfide concentrates are first subjected to an oxidizing treatment and then converted to nickel matte which is processed by hydrometallurgical methods. These methods have been indicated as A, C, and D in Figure 5.6. 

Hydrometallurgy has frequently been praised for not having any highly adverse impact on the environment. The problems associated with sulfur dioxide emission to the atmosphere from the roasters and the smelters of sulfidic sources have created much interest in treating these resources by hydrometallurgical methods. Moreover, the extreme amount of effort that has gone into the development of hydro-based processes for the sulfidic sources... 

Hydrometallurgical methods are normally employed for recovery of gold from oxidized deposits (heap leach), low-grade sulphide ores (cyanidation, CIP, CIL) and refractory gold ores (autoclave, biological decomposition followed by cyanidation). 

Most of the oxide copper deposits are located in the former Republic of Zaire (Katanga) and Zambia. Only a few deposits are located in Chile, Peru, Canada and the United States. From most of the south and North American deposits, oxide copper is recovered using a hydrometallurgical method. 

Metals recycling, 21 385—419 economic aspects of, 21 402-406 ferrous metals, 21 407-417 hydrometallurgical methods of,... 

Hydrometallurgical methods can be applied when low-grade oxidized (oxide) or mixed (oxidized and sulphidic) ores are available. These methods have advantages of high selectivity disadvantages are the relative slowness of leaching and the large volume of solution per unit mass of copper. 

Related hydrometallurgic methods may allow the use of bacteria to release copper from low-grade ores, or the use of algae to concentrate precious metals such as gold (see Chapter 19). ... 

Hydrometallurgical methods use reactions in aqueous solution (often involving metal complex formation) to concentrate and/or separate the metal ions of interest. A commercially important example is the heap leaching of low-grade copper ores with acid. 

The hydrometallurgical methods have been tested many times over, and one of them is still used to day by SAFT AB in their plant in Oskarshanm (Sweden) in addition to their thermal process and for the treatment of their sludge. 

The combined recycling capacity world wide was about 25,000 metric tons of Ni/Cd batteries per year in 1993, but this was significantly underutilized because of inefficient collection systems and low prices for nickel and cadmium. Both pyrometallurgical and hydrometallurgical methods are used to recycle cadmium from a variety of waste materials in plants in North America, Europe, and Japan [24]. Cadmium is relatively easy to separate from other materials because of its low melting point and chemical activity. 

The hydrometallurgical method this involves leaching the PGM from the substrate with strong acids and subsequent... 

Cementation from aqueous solutions is widely used for metal coatings and powders production. It is the foundation of hydrometallurgical methods used for metal regeneration and purification of wastewaters. 

During the last years, an extensive amount of time and energy has been consumed developing an alternative hydrometallurgical method to handle the paste and to ensure the continuation of its efficient recovery. This is of vital importance if the dumping of waste batteries is to be avoided. Several processes (2), as shown in Table I, have been published in the past but none of these reached industrial size operations. 

Batteries recycling hydrometallurgical methods HCl system, 198-199 H2SO4 system, 197-198 sulfuric acid leaching, 196-197, 196/ molten salt electrolysis, 199-200 Bis(phthalocyaninato)lutetium(III) complexes, 84, 135-136, 139... 

Partition functions, 328 PC-88A reagents, 173, 192 Permanent magnets separation hydrometallurgical methods Nd-Fe-B magnets, 170-175 Sm-Co magnets, 167-169 physical separation... 

M. Rodriguez and B.J. Wedderbum, Hydrometallurgical Method for the Extraction of Nickel and Cobalt fi om Laterite Ores (World Intellectual Property Organization, WO 2007/016737 Al, 2007). 

The slags are tapped from the kettle, granulated, and then subjected to separation by hydrometallurgical methods. The initial step is leaching with water, which will readily extract excess sodium hydroxide and sodium chloride leaving a residue of the salts of arsenic antimony and tin. The solubility of these salts is illustrated in Figure 12.6, with tin the most soluble, followed by arsenic and with antimony relatively insoluble. 

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