Kinetics of dephosphorization from steelmaking slag by leaching with C6H8O7-NaOH-HCL solution

Abstract

It is well-known that the recycling of steelmaking slag in iron and steel industry would bring out a problem of phosphorus enrichment in hot metal, which will do harm to steelmaking process. In the present paper, dephosphorization from steelmaking slag by leaching with solution composed of citric acid, sodium hydroxide and hydrochloric acid was studied. Kinetic parameters including temperature, slag particle size and solution pH were optimized. The results showed that temperature has no obvious effect on dissolution of phosphorus. The dephosphorization rate increase with the decrease of slag particle size and pH value of solution. 90.0% of phosphorus can be dissolved in the solution while the corresponding leaching ratio of iron was only 30.0% in the optimal condition. Leaching kinetics of dephosphorization follows the unreacted shrinking core model with a rate controlling step by the solid diffusion layer and the corresponding apparent activation energy is 1.233 kJ mol-1.