Rcovery Zinc From Low-Grade Zinc Oxide Ore With Solvent Extraction

In this dissertation, a process of recovery zinc from low grade zinc oxide ore with HL- SX- EW was studied on the research of zinc solvent extraction.The extraction of zinc by a certain kind of alkyl phosphoric acid(HL) in 260# kerosene can be represented by the equilibrium:Where H2L2org represents the extractant molecule, which usually exists as dimer in kerosene. The apparent equilibrium constant(Kex) and activation energy(E) were determined as 10-1.566 and 46.5kJ/mol respectively. The dynamic equation of zinc solvent extraction is as follows:The extraction order observed is Fe3+>Zn2+>Ca2+>Al3+>Mn2+>Cu2+>Cd2+ >Co2+>Ni2+>Mg2+(pH0.5), the ferric ion is strongly extracted before zinc ion begins to be extracted. However the extracted ferric ion in organic is hardly to be stripped by sulruric acid, therefore the separation of Zn( II ) and Fe(HI) is available by selective stripping. While equilibrium pH<1.5, Zn( II ) can be selectively extracted towards other metal ions except Ca(II); While equilibrium pH<1.0 Zn(II) can be separated withCa(II).Compared to stirring leaching with sulfuric acid, the heap leaching of zinc oxide ore has the virtues of low impurities leaching and low acid consume, moreover it cancels the grinding and filtration operation, which shortens the flowsheet. Zinc can be recovered from the leach solution with solvent extraction, the co-extraction impurities in organic can be removed by scrubbing. The zinc concentrate in stripping solution was about 60g/L, very low contamination was detested. The cathode zinc deposits met 0# criterion, the electricity consume was 3060kWh/t, the current efficiency was above 90%.