Control foaming performance of phosphate rocks used for wet-process of phosphoric acid production by phosphoric acid

Wet-process of phosphoric acid production generates significant amounts of foam which limit plant production efficiency. The control of foaming performance of phosphate rocks and defoaming mechanism has been studied by foaming performance test, X-ray powder diffraction analysis, X-ray fluorescence analysis, contact angle measurement and particle size distribution measurement respectively. The results show that carbonate minerals were digested easily than apatite in phosphoric acid solution. The maximum foam volume (MFV) and equilibrium foam volume (EFV) of phosphate rock could effectively be reduced by Phosphoric acid pretreatment. Pretreatment time and solid content of slurry play a vital role in defoaming process as well. The defoaming efficiency of phosphoric acid was as good as commercial defoamer DF. The foaming performance of phosphate rocks is in directly proportional to the content of carbonate minerals. The defoaming mechanism of phosphoric acid should be attributed to the selective digestion of carbonate minerals in phosphate rocks, not due to the slight change of particle size distribution and surface wettability of phosphate rock.