The Regulation Of Foaming Behavior And Explanation Of Defoaming Mechanism In The Production Of Phosphoric Acid Through Wet Process

In The generation of excessive foam during dihydrate wet-process phosphoric acid would increase the difficulty in controlling extraction technology,protecting the environment from being polluted,lowering the use ratio of the devices.As such,it is urgent and important to regulate the foaming behavior reasonably.The flotation collector is the main reason for the foaming of the flotation phosphate concentrate during the production of wet phosphoric acid.Sodium oleate is widely used in the flotation of phosphate ore.The main objectives of this work are to:reveal the relationship between the sodium oleate concentration and maximum foam volume and half-life period using modified Bikerman method under two phases;investigate the optimal parameters to decompose the sodium oleate through Fenton oxidation process and reveal the kinetics of decomposition;use Fenton oxidation process to mitigate the detrimental effects of foam and reveal the effect of different parameters on defoaming performance and explain the defoaming mechanism;find the optimal conditions to reduce foam generation through pretreatment by means of phosphoric acid and explore the effect of pretreatment on extraction process.The results demonstrate that the degradation of sodium oleate through Fenton oxidation process is highly up to p H value,Fe SO₄·7H₂O dosage,H₂O₂ dosage and reaction time.The maximum foam value and half-life period are proportional to the concentration of sodium oleate.The decomposition of sodium oleate matches well with the first order reaction kinetics and its activation energy could reach 37.60 KJ/mol.When p H is 3,H₂O₂ and Fe SO₄·7H₂O dosages are 1200 g/t and 189 g/t,the Fenton oxidation process could reach the same effect compared to that of traditional defoamer in terms of defoaming performance.The selective digestion of carbonate minerals and degradation of sodium oleate are ascribed to the two main factors that reduce the foam generation,and former plays the leading role.Under three phases,when the ratio of acid and mass of concentrate is 1:1 and pretreatment time is 1 h,the defoaming performance is superior to that of DF defoamer.The acid pretreatment could selectively digest carbonate minerals like dolomite and calcite and transfer the minerals to CO₂ gases,thereby reducing the foam generation.Compared to traditional wet process phosphoric acid,the acid pretreatment could not only reduce the foam generation,but also reduce the phosphorous contents in gypsum from 0.86%to 0.59%,which is beneficial to extraction process.