Study On Treatment And Reuse Of Wastewater From Phosphate Ore Flotation

During the flotation process of phosphate rock,the phosphate flotation wastewater contains a large amount of inorganic ions,residual chemicals and solid suspended matter due to the dissolution of mineral components and the dissociation of flotation reagents.Phosphate flotation wastewater is directly treated to the flotation without treatment,which will adversely affect the flotation index.Studying the treatment of phosphate rock flotation wastewater and its impact on flotation is of great significance for the clean and efficient use of phosphate rock resources.Based on the water quality of a medium-low grade siliceous calcium phosphate colloidal ore flotation wastewater in Guizhou,the effects of SO₄^2-,PO₄^3-,F^-,Ca²⁺and Mg²⁺on the flotation efficiency of flotation wastewater reuse were studied.The effects of the above inorganic ions on the reverse flotation of phosphate rock were investigated by means of surface tension,zeta potential,contact angle,adsorption measurement,infrared spectroscopy,X-ray diffraction analysis and molecular simulation.The wastewater is treated by coagulation sedimentation method to reduce the influence of inorganic ions in the wastewater on the positive and negative flotation of phosphate rock,and the reused wastewater test results are compared with the fresh water flotation index to determine the appropriate wastewater treatment and reuse.The main useful minerals for the ore samples used in the test are fluoroapatite.The main gangue minerals are quartz and dolomite.The P₂O₅ content in the ore is 24.26%,the Mg O content is 2.91%,the Ca O content is 37.55%,and the Si O₂ content is 17.26%.Through the flotation condition test,it is determined that the appropriate grinding fineness is-0.075mm,accounting for86.16%,sodium carbonate is 5 kg/t,sodium silicate is 4 kg/t,and positive flotation collector YS₁is 2.6 kg/t..the amount of sulfuric acid is 14kg/t,and the amount of reverse flotation collector WOS₂ is 0.5kg/t..The whole process test finally obtained the grade of P₂O₅ of concentrate 30.59%,the recovery of P₂O₅ was 87.69%,the content of Si O₂was 11.42%,and the content of Mg O was0.82%.The effect of inorganic ions on the positive and negative flotation of phosphate rock shows that:Ca²⁺and Mg²⁺can greatly reduce the grade and recovery rate of phosphate flotation concentrate P₂O₅.Ca²⁺has a great influence on the grade and recovery rate of phosphate flotation concentrate P₂O₅.Mg²⁺to phosphate rock reverse flotation concentrate.The recovery rate of P₂O₅has a great influence;PO₄^3-has a great influence on the recovery rate of P₂O₅ of phosphate ore flotation concentrate;SO₄^2-will reduce the grade and recovery rate of P₂O₅ of phosphate ore flotation concentrate;F^-pair of phosphate rock The effect of reverse flotation is small.Phosphate ore reverse-flotation wastewater is treated by coagulation sedimentation method.For positive flotation wastewater,when calcium oxide 2800 mg/L,sodium carbonate 2800 mg/L,PAC 2000 mg/L,PAM 300 mg/L,the removal rates of Ca²⁺,Mg²⁺,SO₄^2-,PO₄^3-in wastewater are83.1%,69.7%,46.7%,96.5%;For reverse flotation wastewater,when calcium oxide 5600 mg/L,sodium carbonate 3200 mg/L,PAC 2400 mg/L,PAFC 2400 mg/L,the removal rates of Ca²⁺,Mg²⁺,SO₄^2-,PO₄^3-in wastewater were respectively 81.4%,65.2%,48.0%,96.7%;For positive and reverse flotation mixed wastewater,when calcium oxide 4200 mg/L,sodium carbonate 3200 mg/L,PAC 2400 mg/L,PAM 450 mg/L,the removal of Ca²⁺,Mg²⁺,SO₄^2-,PO₄^3-in wastewater The rates were 81.7%,65.3%,45.2%,and 97.3%,respectively.Considering that the composition of the wastewater after mixing is more complicated,and the reuse index after the wastewater is treated separately is better than the reuse index after the mixed treatment,the phosphate ore flotation and reverse flotation wastewater are separately treated and reused.Through surface tension test,zeta potential test,contact angle measurement,adsorption test,infrared spectroscopy test,X-ray diffraction analysis and molecular simulation study,it is concluded that Ca²⁺,Mg²⁺,SO₄^2-,PO₄^3-,F^-will make the collector solution surface As the tension increases,the contact angle of the mineral surface decreases,resulting in a decrease in the floatability of the phosphate rock and dolomite.Ca²⁺and Mg²⁺can precipitate a large amount of collector,which reduces the adsorption amount of the collector on the surface of the phosphate rock and dolomite,and also inhibits the adsorption of the collector on the mineral surface,reducing the collector and selectivity of the collector;Under alkaline conditions,PO₄^3-will inhibit the reaction between the collector and the collophosphate,and inhibit the flotation of phosphate rock;Under acidic conditions,SO₄^2-will react with Ca²⁺and Mg²⁺to form a precipitate attached to the surface of the phosphate rock,so that the originally inhibited phosphate rock is selected with dolomite.