Research On The Development And Mechanism Of The Mixed Depressant In Magnesite Direct Flotation

The decalcification of magnesite direct flotation is a difficult problem in the current purification of magnesite.The development of selective depressants of calcium-bearing gangue minerals such as dolomite and calcite is of great significance to achieve the efficient utilization of magnesite resources.In this research,the effects of depressants on flotation behaviors of magnesite,dolomite and calcite in sodium oleate（Na OL）system were investigated by pure mineral flotation test and real ore flotation test,and the selective inhibition mechanism of the mixed sodium silicate+HEDP depressants on dolomite and calcite was investigated by zeta potential,adsorption amounts,contact angle,X-ray photoelectron spectroscopy（XPS）and atomic force microscopy（AFM）analysis.The main conclusions are as follows.（1）Pure mineral flotation tests showed that single sodium silicate,sodium lignosulfonate,PAPEMP,HEDP,and PBTCA could not inhibit dolomite and calcite simultaneously.The mixed sodium silicate+HEDP depressants presented good inhibition performance,the flotation recoveries of the three minerals were 84.15%,4.75%and 6.95%respectively when the mixed sodium silicate+HEDP were 20 mg/L+15 mg/L.The results of artificially mixed mineral separation tests further confirmed that the mixed sodium silicate+HEDP depressants could achieve the flotation separation of magnesite from dolomite and calcite.（2）The results of zeta potential,adsorption amount and contact angle tests showed that the zeta potential of minerals shifted to the negative direction after the interaction with the mixed sodium silicate+HEDP depressants,indicating the adsorption of the mixed depressants on mineral surfaces.With the addition of Na OL,the zeta potential of magnesite still showed a large negative shift,and Na OL adsorbed more on magnesite surface,and magnesite surface remained hydrophobic,leading to the difference in wettability between magnesite,dolomite and calcite,these results indicated that the mixed depressants hardly affected the adsorption of Na OL on magnesite surface,but significantly reduced the adsorption of Na OL on dolomite and calcite surface.The results of XPS and AFM tests showed that after the interaction with the mixed depressants,the characteristic peaks of Si 2p and P 2p appeared in the spectra of dolomite and calcite,the element content of Si and P increased more,and the adsorption morphology of the mixed depressants on dolomite and calcite surface was more intensive,indicating that the mixed sodium silicate+HEDP depressants had more adsorption on dolomite and calcite.（3）The real ore flotation tests showed that,for raw ore with Mg O content of 43.06%,Ca O and Si O₂ contents of 2.95%,1.65%,the magnesite concentrate with Mg O content of 47.18%and recovery of 77.83%was obtained by using the mixed sodium silicate+HEDP depressants of 800g/t+500 g/t and the reverse flotation of one roughing-one cleaning and direct flotation of one roughing-two cleaning.Figure 45,Table 14,References 94...