Potential of industrial de-dusting residues as a source of potassium for fertilizer production - A mini review

The several dusts generated in high-temperature processes like cement kiln dust or sinter dust are enriched in potassium which limits the possibility of recycling back to the process where the dust originates from. The sector which consumes the major part of potassium produced from mined potassium ore is the fertilizer industry. Therefore, processing of these dusts to recover potassium for fertilizer production is an obvious option. This review summarizes relevant information from the primary potassium ore processing as well as available data on cement kiln dust and cement kiln by-pass dust, dust from iron ore sinter plants and fly ashes from biomass combustion plants. The results from various studies and a few industrial-scale plants confirm that the “Hot leach – cooling crystallization” process exploiting the temperature dependence of the solubility of potassium chloride can be applied for processing of the dusts.