Minimization of free calcium carbonate in hard and medium-hard phosphate rocks using dilute acetic acid solution

Large amounts of low grade phosphate rocks are present in between the layers of Jordanian phosphate rocks and are rejected by crushers. An experimental investigation to reduce the free calcium carbonate in these rocks using dilute acetic acid has been done. The effect of the nature and size of the raw phosphate particles as well as acetic acid concentration, liquid/solid ratio (vol./wt. basis) and the reaction time have been studied. It was found that upon treatment of the ground ore with acetic acid, the tricalcium phosphate (TCP) percent can be raised by up to 28% corresponding to a reduction of up to 67% in the calcium carbonate content of the samples, depending on the conditions of the reaction as well as the nature and size of the raw phosphate particles used for analysis.