Effects Of Polyethylene Glycol(PEG) On The Reverse Cationic Flotation Of Phosphate Rock

Two gangue minerals,silicate and dolomite,must be removed during the phosphate beneficiation.For the removal of silicate gangue minerals,direct flotation or reverse flotation could be employed.Direct flotation usually uses anionic collectors,which often need consume a large amount of collector and produce large amount of strong foam,causing difficulty to eliminate,and need to adjust the slurry to alkaline p H,which has a greater impact on the subsequent dolomite reverse flotation.Thus reverse cationic flotation of silicate using cationic collector is preferred because the slurry p H is weakly acidic,which has little effect on the subsequent dolomite reverse flotation,and the consumption of collector is usually very low.However,cationic collector also has its shortcomings.Its thick and viscous foam during flotation provides a big challenge to handling and highly sensitive to the slime,which greatly limits its commercial application.In view of the above shortcomings of cationic collectors,suitable surfactants are used to adjust foam,improve flotation selectivity,and reduce the consumption of collectors.The specific research contents are as follows:A phosphate ore from Sichuan Leibo with P₂O₅content of 22.41%,Si O₂content of23.56%and Mg O content of 3.60%was studied by comparison of mixed surfactants and amine and a single amine collector.The optimal flotation conditions of double reverse flotation were also studied.The test results show that optimal conditions for dolomite reverse flotation are 12kg/t sulfuric acid,1.5kg/t phosphoric acid,and 2.25kg/t PA-67collector at a grinding fineness of 90.14%minus 0.074mm;the best condition for silicate reverse flotation is 1.2kg/t water glass,0.2kg/t collector WZ-15 with conditioning time of20min,0.15 kg/t synergist A350 and 0.1 kg/t dodecylamine.When the ratio of surfactant to amine collector,i.e.PEG1000:dodecylamine is 1:4,the best double reverse flotation result obtained is a concentrate with Mg O 1.62%,P₂O₅28.18%,and P₂O₅recovery of 77.53%by the chemical way at yield of 61.76%.The flotation mechanism of the mixed collector of polyethylene glycol?PEG?surfactant and amine cationic collector is studied by means of foam properties,surface tension,contact angle,Zeta potential and infrared spectroscopy.Foam performance tests showed that under high concentration and weak alkaline conditions the foaming ability and foam stability of dodecylamine is enhanced;the addition of polyethylene glycol is beneficial to the foaming ability and foam stability of cationic collector;The foaming stability of the composite collector,mixed dodecylamine and polyethylene glycol,is weaker than dodecylamine,and the foaming ability of PEG600 is stronger at the same p H,but the stability of PEG1000 foam is better;The addition of A350 reduces the foam stability of the composite collector.The surface tension test showed that the critical micelle concentration?CMC?of dodecylamine was 1.07×10^-2mol/L,and the surface tension of dodecylamine at this concentration is 32 m N/m.The ability of polyethylene glycol to reduce the surface tension of dodecylamine solution at a ratio of 1:4 is better than 1:3.The contact angle test shows that the polyethylene glycol reached the lowest value at8g/L,i.e.the hydrophobicity is the weakest.When the concentration of the dodecylamine solution is 0.4g/L,the contact angle of the dodecylamine solution reach the maximum value of 84.7°at p H 10.12.when the ratio of polyethylene glycol to dodecylamine is 1:5,the contact angle of quartz is the largest,the hydrophobicity is the strongest,and the ratio of polyethylene glycol in mixed collector is the most suitable.When the ratios of A350 to the mixed collector?polyethylene glycol+dodecylamine?are 1:8,1:6,1:5 and 1:4 the contact angles are larger than that at other ratios?polyethylene glycol:dodecylamine?.At a right concentration synergist A350 is beneficial to flotation.Both infrared spectroscopy and zeta potential test showed that the dodecylamine adsorbed physically on the surface of quartz.PEG1000 does not adsorb on the surface of quartz.However,PEG1000 does adsorb on quartz after the adding dodecylamine,thus producing certain promoting effect on the collecting ability of dodecylamine.