Lead and zinc removal from deep reduction roasting of lead-zinc bearing hematite-limonite after oxidative roasting and desulfurization
Sulphur(S),lead(Pb) and zinc(Zn) are the harmful impurities in iron and steel smelting process,and deep reduction roasting followed by low intensity magnetic separation is an effective method to recover iron and remove lead and zinc impurities. In the sample of Pb-Zn bearing hematite-limonite from Xinjiang after oxidative roasting and desulphurization,the total iron(TFe),lead,zinc and sulphur contents were 48.33％,1.06％,1.24％ and 0.25％,respectively. Thus,different analyses were conducted before and after roasting process,including thermodynamic reduction analysis and electro probe micro analysis-energy dispersive spectroscopy(EPMA-EDS). Further methods such as magnetic separation,removal process of lead and zinc impurities with the analysis of its mechanism during deep reduction roasting were also carried out. The results show that at the roasting temperature of 1200 ℃,time of 60 min,C and O mole ratio of 2.25,grinding size mass fraction of lower than 74 μm accounts for about 90％ of the total,and a magnetic field strength is 82.80 kA/m for magnetic separation. Iron grade is from 89.53％ to 90.18％,and iron recovery is from 90.82％ to 91.84％. The sulfur decreases to the range of 0.030％ to 0.031％. In addition,the lead and zinc mass fraction of iron ore concentrate are 0.16％ and 0.12％,respectively,and removal rate of lead and zinc are 84.91％ and 90.32％,respectively. The zinc removal effect is much better than the lead removal effect due to the increase of roasting temperature,and increasing the partial pressure of CO enhances the chemical reaction effect of iron,lead and zinc. Iron minerals transform into bright white metallic iron particles with rounded edges during deep reduction. Sulfur,lead and zinc impurities which are in the form of PbS,ZnS and FeS are oxidized into PbO,PbSO4,ZnO and Fe2O3 after oxidative roasting process,and then reduce to flue gas containing lead and zinc impurities,and the part of PbS is encapsulated in silica,which is difficult to remove.
hematite-limonitedeep reduction roastingthermodynamic analysislead and zinc removalmechanism of reduction
罗立群、杨隆川、刘江、贾婷、MUSTAFA Sayaf、NIYONZIMA Jean Christophe
万方数据
维普
