ABSTRACT

Metallurgical slags are produced in large quantities all around the world as a result of smelting, refining or  alloying  processes  applied  to  metals,  ores  and  recycling  material.  The  slag  phase  serves  different purposes  in  metallurgical  processes.  It  prevents  heat  losses  and  protects  the  metal  phases  from contaminations and absorbs gangue and extracted impurities. Due to achievable metallurgical efficiencies certain  amounts  of  valuable  metal  contents  always  remain  in  the  residual  slag.  Recycling  of  these metallurgical  slags has  several positive effects, such  as  optimized ecological  and economical compliance of the producing industry. If recycled metal contents can be reintroduced into existing processes, required inputs of raw material can be lowered. High metal prices enable the economic recovery of metal contents in  metallurgical  slags  by  applying  different  non­metallurgical  processing  methods.  Conventional processing  of  metallurgical  slags  utilizes  processes  such  as  hand  picking,  selective  comminution, screening and magnetic separation. Those state of the art processing techniques have limitations in terms of achievable metal recoveries and required energy demand. The approach for an optimized processing of metallurgical slags targets enhanced metal recoveries in combination with lower specific treatment costs. Processes  such  as  coarse  and  ultrafine  density  separation,  as  well  as  sensor­based  sorting  as  a  preconcentration stage are used to enable an efficient recovery of metal contents in slags. By applying these methods a completely dry working process is possible. This paper reviews the commonly used methods and  describes  approaches  for innovative  processing  of  metallurgical  slags  to  enhance metal  recoveries. Focus of this paper is laid on sensor­based sorting as well as on processes for dry density separation.