Abstract :
Metal-bearing wastes have to be carefully treated because heavy metals could be leached out under uncontrolled conditions when disposed of in a landfill. Consequently, heavy metals should be principally recovered and recycled forever. From this standpoint, the author has been trying to develop a technology to recover heavy metals from toxic vitrification fly ash for recycling to smelters. After a number of laboratory-scale experiments, pilot plant tests were successfully carried out and the developed process has been proven to be commercially realized. The main features of the process are that it recovers almost 100% of the heavy metals, simultaneously separating the metals which are recovered in a lead smelter from those in a zinc smelter, and that the output of the process are only metallurgical products recyclable for smelters and the effluent water which can be released into the environment. The process is considered an ideal one for the treatment of toxic fly ash from the viewpoint of not only natural resources but also environmental conservation.
