The machining of aluminum castings such as auto wheel hubs or engine blocks results in tens of thousands of tonnes of aluminum chips every year. These chips can be remelted and processed into new aluminum alloys. But first the cutting fluids used for milling and drilling have to be removed along with any iron residues. The conventional method of cleaning aluminum chips involves burning off the organic residues. DvB Aufbereitungs-GmbH in Töging, Germany has developed a new chemical-physical process which delivers higher-quality end products at lower cost. "Compared with the thermal method, our process costs less to run, requires less capital expenditure and allows the recovery of high-purity aluminum", explains DvB managing director Dr. Manfred Render.

The patented cleaning principle is similar to that of a washing machine. In a pre-treatment stage, the tangled chips are size reduced and the emulsion largely removed in a centrifuge. In a second step - the actual cleaning process - the residual emulsion adhering to the chips is rinsed off in a washing drum using hot tenside solutions. Once the chips have dried, any loose iron is separated out by magnetic drums. The end product has a residual iron content of less than 0.1 percent and can be melted down without any problem. The recycling rate is almost 100 percent. Cutting fluids and a sludge containing oil and aluminum oxide are by-products of this process which are currently incinerated.

The first customer for this new service from DvB is VAW-Imco Guß und Recycling GmbH, an aluminum smelter. Further metal recycling services from DvB include the thermal processing of chips and shredder products and the recycling of salt slag.