利用锌浸出渣制备铊吸附剂

Preparation of thallium adsorbent using zinc leaching residue

火法冶金工序中,含铊物料易挥发进入烟气洗涤工序,从而产生了大量含铊废水,带来环境污染风险;同时,铅锌行业每年产出总量达数百万吨以ZnFe2O4为主要成分的浸出渣废料,需要妥善处置。基于此,本文提出以锌浸出渣为原料,通过酸浸法提取其中的有价值元素锌和铁,通过氨络合选择性沉铁工艺实现锌铁分离,最后将沉铁产物经过冷冻干燥处理,制得铁基铊吸附剂。稀硫酸逆流浸出法处理锌浸出渣可实现较高的锌、铁浸出效率,分别达到97.05%、99.31%,得到的浸出液中锌、铁浓度分别为86.54 g/L、77.86 g/L;采用本研究提出的络合沉淀法选择性沉铁工艺可以将浸出液中99.78%的铁沉淀分离,且锌损失率控制在0.5%;冻干处理后的沉铁产物是优秀的铁基铊吸附剂,3 g/L铊的水溶液中铊去除率为98.9%,采用pH值1.5的稀盐酸可以洗脱95%的吸附铊,为铊的进一步回收和资源化利用提供了有利条件。该工艺不仅实现了对锌浸出渣的绿色、高值化回收利用,而且成功制备出性能优异的铊吸附剂。

During pyrometallurgical processes,thallium is easily volatilized and entered into flue gas scrubbing operations,resulting in a large amount of thallium⁃containing wastewater and posing environmental pollution risks.Additionally,millions of tons of leaching residue waste,mainly composed of ZnFe2 O4,are generated in the lead⁃zinc industry.Therefore,this study proposes the Preparation of high⁃efficiency thallium adsorption materials from zinc leaching residues.Initially,the zinc and iron are extracted from the residues using an acid leaching method.Thereafter,iron is separated from the leachate through a selective precipitation process.Ultimately,the iron precipitate is subjected to freeze⁃drying to produce thallium adsorbent.The counter⁃current leaching method achieves high leaching efficiencies of zinc and iron(Zn:97.05%and Fe:99.31%).The concentrations of zinc and iron in the leachate are 86.54 g/L and 77.86 g/L,respectively.The selective iron precipitation process is capable of precipitating 99.78%of the iron from the leachate,with the zinc loss controlled to below 0.5%concurrently.Upon treatment with the freeze⁃drying process,the iron precipitate exhibits exceptional performance in the adsorption of thallium,achieving a removal rate of 98.9%in an aqueous solution with a concentration of 3 g/L thallium.A dilute hydrochloric acid solution with a pH value of 1.5 can desorb 95%of the adsorbed thallium,providing favorable conditions for the further recovery and resource utilization of thallium.This process not only achieves green and high⁃value recovery of zinc leaching slag but also successfully prepares an iron⁃based thallium adsorbent with competitive performance.