Kinetics Investigation of Phosphorus Leaching from Steelmaking Slag

The removal of phosphorus is essential to recycling steelmaking slag in metallurgical processes. In this study, dilute nitric acid was selected as the leaching agent for dissolving steelmaking slag. The effects of the variables on leaching percentage of phosphorus were investigated. Experimental results showed that, the leaching percentages of phosphorus increase as the concentration of nitric acid increases. Increasing the liquid/solid ratio and decreasing the slag particle size increased the leaching percentages of the phosphorus. However, the temperature and stirring speed had minor effects on the dissolution of phosphorus. Diffusion through the product layer was the rate-limiting step of the leaching process, and the corresponding apparent activation energy was determined to be 1.61 kJ/mol. Based on experimental results, a semi-empirical kinetic equation was established.