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Rotary melting flexibility

In response to demand for furnaces capable of melting more than one metal without contaminative carry over between different product batches, Monometer has demonstrated the effectiveness of rotary furnaces to melt both copper and aluminium in close succession while maintaining target product specification for each metal.

In the example, a 1000kg copper capacity rotary furnace, previously applied exclusively to the production of high purity copper and copper alloys, was trialled successfully in the production of aluminium of various grades including LM24 and LM27, attaining copper levels well below the upper tolerance for these alloys. Following the aluminium cycle, a short intermediate slag wash to Monometer specification effectively cleaned the furnace to allow return to high purity copper production.

Demonstrating the flexibility of rotary melting afforded the foundry an opportunity to diversify and expand into new markets while economically utilising existing melting equipment, and it is notable how such diversification in the UK is typically supported by operating permits that allow a change of process without notification, provided there is no increased adverse environmental impact.

In related developments, Monometer has successfully applied economical tailored techniques in secondary aluminium melting to consistently limit dioxin and furan emissions concentrations to below 1ng/m3 (the most recent BAT-AEL, down from 5ng/m3) prior to entry to the exhaust gas abatement plant, without need for relatively costly capital expenditure.

For the trials, an oxy-fuel burner system was dynamically adjusted in response to conditions in the furnace, maintaining combustion conditions suitable to exclude the formation of PCDD/F volatiles. Conditions were assisted by targeted injection of activated carbon and continuous conditions to promote quenching beyond the furnace exhaust, all in accordance with BAT 83 (as summarised on page 1035 of the BAT Reference Document for the Non-Ferrous Metals Industry, EUR 28648 EN, 2017). Results demonstrated the use of existing Monometer rotary furnace equipment to obtain results comparable with methods typically associated with costly investment in furnace abatement ancillaries.

Monometer metal melting furnaces remain popular across the range of burner technology and refractory designs offered, including air-fuel, oxy-fuel and electric plasma. Process temperatures range from around 900°C for aluminium and tin, rising to around 1700°C for specialist processes, offering controlled process environments and thermal efficiency typically in the range of 45 to 55 per cent.

Contact: Dr Christopher Hall, PhD, BEng, DiplEng, FICME, Monometer Holdings Ltd, Monometer House, Rectory Grove, Leigh-on-Sea, Essex SS9 2HN UK. Tel. +44 (0) 1702 472201, Mob: +44 (0) 7867 500341, website: www.monometer.com