草酸酸浸处理钛石膏实验研究

Study on leaching treatment of titanium gypsum with oxalic acid

硫酸法酸浸钛石膏虽能有效浸出铁杂质但易引起石膏相变,对环境影响较大,工艺危险性高。基于此,采用草酸代替硫酸酸浸钛石膏浸出铁杂质,探究了酸浸温度、酸浸时间、草酸质量分数、液固质量比等因素对浸出铁效果的影响。结果表明:在草酸酸浸过程中以扩散过程为主,温度和时间是主要影响因素;在酸浸时间为110 min、酸浸温度为90℃、草酸质量分数为6%、液固质量比为8条件下,草酸浸出铁率可达84%;结合FT-IR、XRD、SEM表征结果发现,钛石膏中铁杂质以絮凝状吸附在石膏晶体表面,适量草酸能有效去除钛石膏中铁杂质,过量草酸则会造成石膏部分溶解并在晶体表面生成草酸钙影响晶体形貌。采用草酸酸浸处理钛石膏可以有效去除钛石膏中的铁杂质,是一种环保、有效的除铁工艺,该实验结果可为钛石膏除铁研究提供参考。

Although the acid leaching of titanium gypsum with sulfuric acid can effectively leach iron impurities,it is easy to cause the phase transformation of gypsum,which has great influence on the environment and high process risk.Based on this,oxalic acid was used instead of sulfuric acid to leach titanium gypsum for iron impurities.The influences of leaching temperature,leaching time,mass fraction of oxalic acid and ratio of liquid to solid on the leaching effect of iron were investi-gated.The results showed that the diffusion process was the main process in oxalic acid leaching,and temperature and time were the main influencing factors.Under the conditions of leaching time of 110 min,leaching temperature of 90℃,mass fraction of oxalic acid of 6%and liquid-solid mass ratio of 8,the leaching rate of iron by oxalic acid reached 84%.Combined with FT-IR,XRD and SEM characterization results,it was found that the iron impurities in the titanium gypsum were ad-sorbed on the surface of the gypsum crystal in a flocculating manner.Appropriate amount of oxalic acid could effectively re-move iron impurities in titanium gypsum,and excessive oxalic acid would cause partial dissolution of gypsum and the forma-tion of calcium oxalate on the crystal surface,which affected the crystal morphology.Oxalic acid leaching treatment of tita-nium gypsum could effectively remove iron impurities in titanium gypsum,which was an environmentally friendly and effec-tive iron removal process.The experimental results could provide reference for the study of iron removal of titanium gypsum.