Phosphorus removal from high phosphorus oolitic iron ore by acid leaching

This paper reports the phosphorus removal of high phosphorus oolitic iron ore by acid leaching and its influence factors. The experimental ore is Exi high phosphorus oolitic iron ore with 0.5% phosphorus, 51.7% iron and 0.34% sulphur. After acid leaching, the P content decreases to about 0.07%, the iron loss during acid leaching is about 0.18%, and the S content is 0.35%, which can meet the requirements of steel production. Through analyzing the ore surface before and after acid leaching by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), it is found that apatite is almost completely dissolved, but iron oxide phase hardly reacts, which is also proved through thermodynamic calculations. The optimal experimental parameters are determined to be the leaching time of 1 h, the liquid-solid ratio of 100 mL:8 g, the acid concentration of 0.2 mol·L^-1, and the oscillation frequency of 150 Hz. Micro cracks appear in the ore by microwave preheating, the specific area of the ore is increased, but little improvement in dephosphorization is induced during acid leaching. The recycling of the waste acid solution is feasible. Through adding fresh acid to the waste acid solution, the acid solution after treatment can leach phosphorus to the satisfied extent again. The dephosphorization rate is controlled at 80%. The recycling can reduce the cost obviously and protect the environment.