Efficiency of slag cleaning in a magnetically in- duced stirring reactor

Slags generated in pyrometallurgical copper processes are mineral by-products governed by the regulations applicable in the building and construction industries. To extend the range of applications and safeguard its EU product classification, sustainable purification and homogenisation of the slag is required. Experiments in two reactors were carried out as part of a collaborative project funded by the Federal Ministry of Education and Research (BMBF). The fundamentals and theoretical background to this were published at EMC 2011. A pilot-scale stirring reactor, integrated in the industrial process, was operated in a number of weekly campaigns and treated two tons per hour of slag at AURUBIS, Hamburg in a semi-continuous operation. Reproducible results prove the effect of the magnetic and electric field on the settling behaviour of metal/matte droplets in fayalitic slags. A second, smaller demo-scale stirring reactor was designed and installed at IME, RWTH Aachen University. It facilitates shorter campaigns with synthetic slags of steady qualities and short response times. The aim is to examine the physical and metallurgical principles behind this process in more detail. This test unit allows throughputs of about 0.5 ton molten slag per hour in a 1 MW electric smelter or a 0.5 MW TBRC.