Conform and the recycling of non-ferrous scrap metals

Abstract

There is a continuing search for more effective means for reprocessing scrap metals to return them once more into fully acceptable marketable products. Clean non-ferrous scrap arisings could be recycled directly if a means were available to metallurgically bond together the individual particles to produce a homogeneous product. Extrusion is a process which appears to have much to offer in this way, the generation of high pressures and the plastic deformation of the metal as it flows through the die ensures a homogeneous structure in the final product. A continuous extrusion process would offer environmental advantages and energy savings in eliminating the need for melting. The UKAEA Springfields Laboratories are currently developing a continuous rotary extrusion process known as Conform which has considerable potential for the direct recycling of scrap non-ferrous metal in various forms. The process uses mechanical friction both to feed stock up to an extrusion die and to generate the pressure necessary to extrude it through the die. This is accomplished in practice by the combination of a rotating grooved wheel with a stationary shoe arranged to overlap a portion of the wheel circumference. The shoe holds the die and the feedstock is carried along in the wheel groove as it rotates. This type of machine has been used to extrude both aluminium and copper particle feeds into solid products such as round wires, various shapes, and — in the case of aluminium — into tubing. These products have good mechanical properties and depending on the condition of the feed may have good electrical properties. The particle feeds have included powders, granules, machining swarf, chopped wire, and chopped copper cathode. The Conform process is basically simple and offers the possibility of almost 100% yield. The machines are compact, easily operated and relatively cheap and the process offers the opportunity for considerable cost savings in recycling. Development work is continuing at the UKAEA laboratories and at the works of the licensed machine builders.