Advanced Materials Research Vol. 828

Abstract: Copper electro-refining (Cu-ER) is the principal method for producing >70% of high or 99.97% pure copper cathodes from 97-99% pure blister/fire refined-scrap copper anodes. While the inert and most of less soluble impurities settle as anode slime/sludge, other soluble impurities, particularly the metalloids (group VA/15 elements or Q: As, Sb and Bi) and some transition metals (Mt) co-dissolved with Cu(II). Since the soluble impurities build up in the copper refining electrolyte (CRE) which need monitoring and control to prevent contamination of the cathodes and passivation of the anodes before bleeding for spent CRE reprocessing. There is a high demand for pure electrorefined copper and electrolyte additives are added to the CRE to prevent nodulation or control the chemical and physical properties of copper cathodes. Various hydrometallurgical methods such as precipitation, adsorption, electro-dialysis, electro-winning, ion exchange and solvent extraction have been developed with some success to control the CRE impurities. So some emerging technologies for improved monitoring and control of the metalloid impurities in CRE and slime as well as development of saleable byproduct recovery (As, Sb, Bi) are briefly reviewed with particular emphasis on the precipitation for the metalloid slime resource recycling and product development.

Abstract: A biphasic leaching operation was employed for the extraction of copper and zinc from the GMDC polymetallic bulk concentrate (PBC). Biogenerated ferric was used in cyclic manner for fed batch metal extractions from the PBC for four cycles under the pre-optimized conditions. Zn extraction was gradually decreased with each succeeding fed-batch cycle and it resulted in 67.89, 62.46, 47.37 and 14.74% of Zn extraction in 1^st, 2^nd, 3^rd and 4^th cycle respectively. In case of copper the extraction pattern was 86.63, 81.98, 75.58 and 46.51% Cu extraction in 1^st, 2^nd, 3^rd and 4^th cycle respectively. The leachate generated in each cycle was added in 15.0 L down flow packed bed column reactor having biofilm of developed consortium SR-BH-L for the ferrous bioregeneration and the obtained maximum IOR was 2650 mg/L/h. Overall results indicated that use of bioregenerated ferric iron from the leachate yielded as high as 52.2 and 2.6 g/L Zn and Cu respectively in the solution at the end of 4^th cycle. This metal concentration in the leachate is quite acceptable for economical solvent extraction process.

Abstract: Tungsten-copper(W-Cu) alloy is employed for manufacturing heavy duty contactors, relays,switches etc. During production of such components, W-Cu turnings/borings aregenerated. At CSIR-NML, a process for recovering tungsten and copper fromtungsten-copper borings containing 46.01% W, 53.78% Cu, 0.13% Fe and otherminor metals as high purity tungsten powder and copper powder has beendeveloped. In the present work, a detailed investigation on reduction ofammonium paratungstate (APT) having purity 99.95% by hydrogen gas to produce highpurity tungsten powder is presented. The various process parameters such astemperature, time and flow rate of hydrogen gas have been optimized. At the temperatureof 800°C and 0.1 lpm flow rate a reduction of 77.78% was observed upto 2h time. At 900°C, with increase in flow rate from 0.1 lpm to 0.3lpm the increase in reduction was found to be from 63.88% to 99.99% at 1h time.At still high temperature of 1000°C, almost complete reduction was obtainedat 0.1 lpm flow rate in 1h time. The effect of bed-depth was also carried out. Atall temperatures chemical reaction was the rate determining step.