Removal of Phosphorus from Leach Liquor of Steel Slag: Adsorption Dephosphorization with Activated Alumina

Leaching dephosphorization is an effective way to remove the harmful element phosphorus from steel slags. In order to recycle the leach liquor, static phosphate adsorption with activated aluminum oxides was investigated in this work. It was demonstrated that, for an initial phosphorus concentration of 25.95 mg/L, a phosphorus removal rate of 88% and an adsorption capacity of 0.72 mg/g can be reached under the optimal conditions of adsorption time of 34 h, adsorbent dose of 40 g/L, pH of 6.3, and adsorbent particle size of 1.18–2 mm. The Freundlich model and pseudo-second-order-kinetic model can describe the adsorption process well. It was shown that adsorption of phosphorus on the surface of activated alumina particles was a multi-molecular-layer process whose kinetics was controlled by the adsorption reaction.