POTENTIAL OF CFB PROCESSES FOR CADMIUM REMOVAL FROM PHOSPHATE ROCK

摘要

As one of the global leaders in minerals and metals processing technologies, Outotec has nearly 350 alumina calcination and roasting reference plants in operation, all based on proprietary fluidized bed processes.In addition, a technology for removing toxic pollutants from ash and minerals, known as the ASH DEC process, was acquired and integrated to the company's process portfolio.These technologies provided the rationale for investigations on decadmiation of rock phosphates.In a basic test program performed in 2012-2013, thermal treatment of Moroccan rocks K09, K12, K20 and Youssoufia at temperatures of 900 and 1000℃ has proven to effectively oxidize organic carbon, destroy carbonates and remove about 80％ of the initial cadmium mass fraction from the solid (product) fraction.These results support the assumption, that an integrated calcination and Cd-removal process as proposed in this paper, may be an economically viable and technically feasible option to obtain a rock phosphate concentrate almost free from organic and carbonate compounds as well as a reduced cadmium concentration of ＜20 mgCd/kg P2O.