Heat Exchangers Recover and Recycle Excess and Wasted Energy
January 2015 - – In copper production, heat generated during extraction processes can be harnessed and transferred back into the system using heat exchangers, resulting in significant energy savings and unparalleled yield.
“Compact heat exchangers, such as gasketed and welded plate heat exchangers, as well as spiral heat exchangers, are the most efficient technology for heat transfer,” says Roger Rusch, CEO of Industrial Water Cooling (IWC). “Their close temperature design, high internal turbulence and large heat-transfer areas combine to recover up to 25% more energy when compared to conventional shell-and-tube heat exchangers. This excess energy can be recycled and used in other applications within the copper processing plant.”
During the initial copper extraction process, plate heat exchangers are used to control chemical temperatures within the autoclave where crushed copper ore is leached with sulphuric acid to produce impure solutions of copper sulphate. Spiral heat exchangers are then incorporated to recycle the rich acid’s low-grade heat, which is then used to pre-heat the lean acid coming back from solvent extraction.
Another area where plate heat exchangers deliver optimum heat recovery is during the electrowinning process where copper ions are extracted from the copper sulphate. The electrowinning cell consumes nearly 80% of total energy required for the production of copper. Here, steam is used to heat rich electrolyte before it enters the electrowinning cell. Gasketed plate heat exchangers reduce net consumption of energy in the plant by recovering low grade heat during the process and using it to preheat the rich electrolyte.
“Plate heat exchangers are low-cost and low-maintenance and are up to 90% smaller than the equivalent shell-and-tube heat exchangers. By replacing costly and bulky shell-and-tube units with compact heat exchangers, copper processing plants are recycling megajoules of wasted energy each year,” says Rusch.
IWC supplies a wide range of SONDEX plate heat exchangers. Established in 1984, SONDEX is a Danish company and a world leader of heat exchangers. Their products include traditional plate heat exchangers, free-slow, semi welded, brazed, plate-and-shell, and spiral heat exchangers. Connection sizes range from Ø15 mm – Ø650 mm and cover a liquid flow rate of 0.05 m3/hour to 5700 m3/hour. IWC, originally founded in 1986 as Industrial Water Cooling, are the leaders in industrial cooling tower systems in Africa, offering fully integrated solutions, from industrial cooling towers to GRP. IWC has extensive experience in delivering cooling solution for the copper mining industry and designed slurry cooling towers for the pressure-leach process used in Kansanhi, Zambia. For nearly two decades, IWC have successfully undertaken more than 80% of all natural draft refurbishment work in southern Africa. Clients include heavyweights such as Eskom, Sasol, ArcelorMittal and Foskor. Some industries in which the company is involved with are:
• Power Generation
• Steel & Aluminium
• Food & Beverages
• Air-conditioning, Refrigeration and many other applications
Contact IWC on +27 (0) 11 466 0699