Aluminium alloy melting and production processes generate a by-product called aluminium dross, which is a mixture of entrapped aluminium metal, aluminium oxide and impurities. Depending on the raw material and melting process, dross can contain 30%-70% of aluminium metal or more. Collecting the metal from dross is a key challenge and a necessary step to save resources, reduce costs and improve a firm’s financial standing. The most common Aluminium Recovery Systems, or in other words ways to process the dross, are by dross press, rotary furnace and the growing method of thermite-reaction and centrifugal force utilisation + agitation. This last method is catching up fast with molten metal manufacturers.
Major aluminium molten metal manufacturer HOEI Shokai in Aichi, Japan was looking to improve its treatment process of aluminium dross. As of April 2014,Hoei’s consolidated sales were approximately 36.5 billion yen with molten metal sales volume at 8,000 MT per month. For optimized dross treatment, the newest model of Sanshin’s High-Speed Dross Processing Plant has been installed in Hoei’s Hekinan factory, which is Hoei’s base factory for molten aluminium production.

Photo #1: Hot dross processing in operation                 Photo #2:  Recovered aluminium alloy metal 

Originally, all hot dross processing was outsourced, but in order to cut costs, Hoei started manually processing dross from 2006. Manual dross processing is a burden on the workers, and from an environmental perspective leads to airborne dust. To mitigate these issues, Hoei installed its own company-developed aluminium dross processing machine from 2008.

After these methods were found to be inefficient, Sanshin Industry’s dross processing system was installed in Hekinan’s factory. The system installed was the Automatic High-Speed Aluminium Dross Processing Plant, Model 350, making the aluminium dross’ treatment process completely automatic. Its processing capability is over 90% (of available metal within dross) in 5 minutes, which far exceeds any other method in the market, including dross press and traditional methods of pit or rotary furnace. From an environmental standpoint, the plant controls dust diffusion by at least 80% while also requiring minimal electrical power usage.

Hoei Shokai doubled recovery yields to 40-50%, amounting to 40-60 tons per month. Compared to manual dross processing, monthly costs decreased by 5million JPY and compared to Hoei’s company-developed dross processing machine, monthly costs decreased by 3 million JPY after installing Sanshin’s plant.

The second Sanshin plant will be installed in Hoei’s headquarters factory between March and April 2015 in order to enhance factory’s environment conditions and production efficiency.

Sanshin Sanwa Group’s hot dross processing aluminium recovery system (SSG ARS) is a Japanese-developed and manufactured hot dross processing technology for aluminium melting operations. Since its development in the late 1970s, Sanshin Sanwa Group has been continually improving the ARS to perfection for its users in a country with marginal natural resources and stringent environmental regulations. The Sanshin ARS holds several utility model patents in both Japan and China. Over 400 system sets, translating to an over 80% market share, have been commissioned in Japan alone.

(By Michie Rushlander, Manager, International Sales Team, ARS — Hot Dross Processing Aluminium Recovery Sanshin Sanwa Group)