Improving Productivity and Energy Efficiency in Copper Electrowinning Plants
This paper presents strategies to improve energy efficiency and productivity in copper electrowinning (EW) plants. Plant modeling is based on updated technical data and specific measurements obtained in a tankhouse during a complete production cycle (four to five continuous days). The industrial EW plant site examined produces 180 000 ton/year with an operating current density of 300 A/m2 and a current dispersion of 8.5%. Proposals are based on the use of Optibar intercell bars and the reduction of distance between electrodes. Due to these changes, an improvement of +4.3% in energy efficiency combined with an increase of +3.4% in production can be accomplished. The productivity improvement projected for the plant is U.S.$ 10 million/year.
Rectifier and DC bus systems design for the copper electrowinning industry
It is noted that the use of DC rectifiers and DC bus systems for the copper electrowinning industry has become more widespread during the last 10 years due to the refinement of the solvent extraction process, which has made electrowinning one of the most cost-effective methods of producing copper. The author discusses some of the design features of the large DC rectifier systems, the design basis for the DC bus systems, and some of the problems encountered with the operations of the systems. He suggests means to correct these problems on present and future systems.<<ETX>>
Low-temperature thermal expansion of PEEK, HTA and some of their composites reinforced with carbon fibres
Abstract The thermal expansion of poly(ether ether ketone), a modification of poly (ether sulphone) and carbon fibre reinforced composites of these polymers has been measured over the range −153 to 27°C with a push-rod diameter. Where other measurements are available for comparison, agreement is obtained within experimental scatter. Some multidirectional composites are tested and the measured values of thermal expansion are explained qualitatively. It is thought that the specimen size has had a significant effect on these results. The longitudinal and transverse coefficients of thermal expansion of Hercules AS4 fibre have been calculated.