微生物硫氧化-硫还原回收垃圾焚烧飞灰中Cu和Zn

Recovery of Cu and Zn from waste incineration fly ash through integrated sulfur bio-oxidation and bio-reduction

利用正交实验确定了飞灰中重金属生物淋滤浸出的最佳条件:pH 4.0、飞灰固体浓度1%和硫粉添加量5 g·L^(-1)。在此条件下,飞灰中Cu、Zn、Pb和Cd的去除率分别为47.3%、72.9%、12.4%和75.8%。通过氮气吹脱硫酸盐生物还原产生的H_2S,在pH为2.2和4.0时可分别以硫化物沉淀形式选择回收生物淋滤产生的淋滤液中的Cu和Zn。X射线能谱分析发现,沉淀得到的铜和锌纯度分别达90.6%和99.9%。X射线衍射分析铜沉淀的晶体类型主要为靛铜矿(CuS)、蓝辉铜矿(Cu_7S_4)和雅硫铜矿(Cu_9S_8);锌沉淀主要为纤维锌矿(ZnS)。综合分析,微生物硫氧化-硫还原可以以纯净硫化物形式回收飞灰中47.3%的Cu和64.0%的Zn。

In this study,the optimum conditions for heavy metal bioleaching from waste incineration fly ash,being determined through the orthogonal test,were following:pH 4.0,fly ash solid concentration of 1%and sulfur concentration of 5 g·L-1.Under these conditions,the removal rates of Cu,Zn,Pb and Cd in fly ash were47.3%,72.9%,12.4%and 75.8%,respectively.For H2 S produced from the bio-reduction of N2 stripped sulfate,it could be used to selectively recover Cu and Zn in the leachate through forming sulfide precipitation at pH 2.2 and 4.0,respectively.The X-ray energy spectrum(EDS)analysis indicated that the purity of copper or zinc in its own precipitate was 90.6%and 99.9%,respectively.XRD analysis confirmed that copper precipitate consisted of covelline(CuS),anilite(Cu7 S4)and yarrowite(Cu9 S8),and zinc precipitate primarily consisted of wurtzite(ZnS).Ultimately,47.3%of Cu and 64.0%of Zn in the fly ash could be recovered as pure sulfides through the integrated sulfur bio-oxidation and bio-reduction.