South African based Industrial Water Cooling (IWC), along with its wholly owned subsidiary Tektower, has been providing cooling tower and heat exchanger solutions to Zambian and DRC mines for many years. Solvent extraction (SX) and electrowinning (EW) processes are typical to these mines. Heat generated by SX-EW plant processes either needs to be rejected or harnessed and transferred back into the system.
Cooling Towers
Cooling towers form the heart of a plants cooling system and provide the necessary heat rejection for SX-EW plants to operate effectively and efficiently. Dependant on the design conditions and required duty, cooling towers can either be smaller factory assembled package type cooling towers or large field erected cooling towers. Given the corrosive environment within SX-EW plants, cooling towers need to be robust and corrosion proof to ensure the maximum return on a mine’s CAPEX spend; while ease of cooling tower operation and maintenance, along with readily available and competitively priced cooling tower spare parts, impact directly on a mine’s OPEX spend.
Procurement managers, along with engineering and maintenance teams, need to ensure that any cooling towers will meet the required duty and adhere to all the necessary plant specifications but also need to ascertain:
- how readily available spare parts are (in an emergency ex-stock parts will ensure production continuity while long lead parts can bring production to a standstill),
- are spare parts sourced locally or regionally, or do they need to be imported from abroad, and
- have the full tower specifications and spare parts lists been made available by the original supplier in a language that the end user understands?
Regular comprehensive preventative maintenance of cooling towers is key to cooling towers delivering the duties and performance they were designed for.
Heat Exchangers
Heat generated during SX processes can be harnessed and transferred back into the system using heat exchangers. Gasketed and welded plate heat exchangers are arguably the most efficient technology for heat transfer. They offer close temperature design, large heat transfer areas and are up to 90% smaller than equivalent shell-and-tube heat exchangers. Plate heat exchangers are also low cost and low maintenance.
In the SX 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 can then be incorporated to recycle the rich acid’s low-grade heat, which in turn can then be used to pre-heat the lean acid coming back from solvent SX.
In the EW process plate heat exchangers can deliver optimum heat recovery by recovering low grade heat generated during the process and using it to preheat the rich electrolyte.
IWC are the leaders in industrial cooling tower systems in Africa and has extensive experience in providing cooling solutions for the copper mining industry. IWC has successfully undertaken more than 80% of all natural draught cooling tower refurbishment work in southern Africa.
Deon Fawell
Key Accounts Manager
+27 – 11 – 466 – 0699
deon@iwc.co.za
