Study On The Mechanism Of Inhibition Of Apatite Flotation By Sulfuric And Phosphoric Acid Mixed Aci

Phosphate rock is an important strategic mineral resource in China,providing important support for the country’s grain production,chemical and military product manufacturing.Guizhou Province is rich in phosphate rock resources,accounting for about 16%of the national reserves.However,there are few rich phosphate rock resources and more collophosphate rock.The useful minerals and gangue minerals coexist closely,making it difficult to beneficiation.Using the reverse flotation process to effectively inhibit the floating of apatite under weak acid conditions is the key to the flotation of calcium-magnesium phosphate ore.It is of great significance to study the high-efficiency inhibitors and mechanism of apatite for realizing the high-efficiency utilization of low-grade calcium-magnesium phosphate ores.In this study,purified mineral flotation experiments were used to study the effects of sulfuric acid,phosphoric acid and sulfur-phosphorus mixed acid inhibitors on the flotation separation of apatite and dolomite.On this basis,contact angle measurement,inductively coupled plasma atomic emission spectroscopy（ICP-OES）,confocal Raman spectroscopy（Raman）,X-ray photoelectron spectroscopy（XPS）,infrared spectroscopy（FTIR）,Zeta Potential measurement were applied to study the inhibition mechanism of sulfur-phosphorus mixed acid on apatite.The results of purified mineral flotation test show that sulfur-phosphorus mixed acid has a good inhibitory effect on apatite in apatite-dolomite artificial ore,and can obtain a concentrate with a P₂O₅grade of 32.53%and a recovery of 88.92%.The study of dissolution kinetics shows that the dissolution process of apatite surface has a composite model of both chemical reaction type and product diffusion type when sulfur-phosphorus mixed acid is used as an inhibitor.Compared with sulfuric acid or phosphoric acid,the amount of substances formed on the surface of apatite under the action of sulfur-phosphorus mixed acid is larger,and the composition of the product is mainly Ca HPO₄,followed by Ca SO₄.When sulfur-phosphorus mixed acid is used as an inhibitor,the contact angle of apatite surface is the smallest,which is 39.5°,and the Zeta potential of which is negative and the absolute value is the largest.Molecular simulation calculations show that,by using sulfur-phosphorus mixed acid,the arrangement of water molecules at the apatite-water interface is more orderly and stable,and the adsorption of water molecules on the surface of apatite is relatively strong.Sulfuric acid,phosphoric acid and sulfur-phosphorus mixed acid as inhibitors can significantly reduce the adsorption capacity of sodium oleate on the surface of apatite,among which the adsorption capacity of sodium oleate is the lowest by using sulfur-phosphorus mixed acid.This may be due to the lowest Zeta potential on the surface of apatite under these conditions,which weakens the non-selective adsorption of anionic oleate.In this study,the surface dissolution characteristics,surface material composition,surface wettability and surface electrical properties,surface water molecule adsorption characteristics and collector adsorption characteristics of apatite under the action of sulfuric acid,phosphoric acid and sulfur-phosphorus mixed acid were compared and analyzed.The research results comprehensively reveal the inhibitory mechanism of sulfur-phosphorus mixed acid on apatite,which provides a certain scientific reference for the efficient utilization of low-grade calcium-magnesium phosphate rock.