Photogenerated-hole scavenger for enhancing photocatalytic chalcopyrite bioleaching

The effects of photogenerated-hole scavengers (ascorbic acid, oxalic acid, humic acid and citric acid) on chalcopyrite bioleaching in the presence of visible light were studied using Acidithiobacillus ferrooxidans (A. ferrooxidans). Four sets of bioleaching experiments were performed: (1) visible light + 0 g/L scavenger, (2) visible light + 0.1 g/L of different scavenger (ascorbic acid, oxalic acid, humic acid and citric acid), (3) dark + 0.1 g/L of different scavenger (ascorbic acid, oxalic acid, humic acid and citric acid), and (4) dark + 0 g/L scavenger (control group). The results showed that ascorbic acid and oxalic acid could act as photogenerated-hole scavengers and significantly enhance chalcopyrite bioleaching under visible light. The dissolved copper in the light group without scavenger was only 18.7% higher than that of the control group. The copper extraction rates of the light groups with oxalic acid and ascorbic acid were respectively 30.1% and 32.5% higher than those of the control group. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) analyses indicated that ascorbic acid and oxalic acid as photogenerated-hole scavenger could capture photo-generated holes and inhibit jarosite formation on the chalcopyrite surface, thereby enhancing bioleaching of chalcopyrite under visible light.     

微生物浸出金属硫化矿的动力学研究进展

介绍了微生物浸矿动力学研究进展，重点叙述了微生物浸矿的动力学研究方法及各种动力学模型，并讨论了各模型的意义。     

福建紫金矿业股份有限公司硫化铜矿生物堆浸过程

针对紫金山铜矿的特点 ,进行生物堆浸提铜工业试验研究。结果表明 ,紫金山铜矿生物堆浸效果良好 ,不同浸矿堆累计浸出时间 10 0 0h ,浸出率在 40 %～ 60 % ,浸出半年 ,浸出率达 80 %以上。次生硫化铜矿物的生物堆浸具有两个阶段 ,在浸出前一阶段 ,浸出速率较快 ,而浸出第二阶段浸出速率较慢。随着浸出的进行 ,浸出液 pH连续下降 ,溶液电位逐步升高。微生物的存在加速堆中Fe2 氧化使溶液电位上升 ,同时氧化中间过程的产物元素硫 ,从而加速硫化矿的氧化溶解。     

金堆城低品位辉钼矿的可浸性

采用细菌和化学浸出方法研究金堆城低品位辉钼矿的可浸性。结果表明，酸性（硫酸）介质下的细菌氧化浸出和化学氧化浸出，钼易与一些金属离子（如Fe，Ca，Al）生成不溶性的化合物，钼浸出率很低。低浓度次氯酸钠（NaClO）氧化浸出工艺回收低品位辉钼矿的钼是可行的。保持浸液pH=9～11，有效氯浓度15g／L的NaClO能有效浸出钼.     

铅锑锌铁硫化矿的细菌浸出

研究了脆硫锑铅矿、铁闪锌矿、磁黄铁矿的细菌摇瓶浸出，结果发现，脆硫锑铅矿不能被细菌浸出；磁黄铁矿细菌浸出23d，铁的浸出率为99％；铁闪锌矿细菌浸出29d，锌的浸出率为91％，铁的浸出率为15％。矿浆浓度对磁黄铁矿和铁闪锌矿的细菌浸出有影响。利用X射线分析了3种矿物的细菌浸出机理。     

Bioleaching of metals from sewage sludge: Microorganisms and growth kinetics

Microbial leaching is one of the advantageous methods of removing heavy metals from sewage sludge, however, the microbiological aspects of this technology have not been studied. This study presents the characterization of the naturally occurring microorganisms, responsible for the metal leaching activity, in 21 different sewage sludges. The results obtained indicate that the bioleaching of metals is carried out by successive growth of less-acidophilic and acidophilic thiobacilli. Several species of less-acidophilic thiobacilli participate in the sludge acidification, but Thiobacillus thioparus is the most important species. In contrast, Thiobacillus thiooxidans seems to be the only species involved in the acidophilic group of thiobacilli. The growth kinetics of the two groups of thiobaciili was followed in five different sewage sludges. After 5 days of incubation in shake flasks, the pH of the sludge was decreased to about 2.0 and this pH decrease solubilized the toxic metals (Cd: 83–90%; Cr: 19–41%; Cu: 69–92%; Mn: 88–99%; Ni: 77–88%; Pb: 10–54%; Zn: 88–97%). The maximum specific growth rate (μ_max) for the less-acidophilic thiobacilli varied between 0.079 and 0.104 h⁻¹ and that for the acidophilic thiobacilli varied between 0.067 and 0.079 h⁻¹.     

Characterization of copper bioreduction and biosorption by a highly copper resistant bacterium isolated from copper-contaminated vineyard soil

Copper is an essential but toxic heavy metal that negatively impacts living systems at high concentration. This study presents factors affecting copper bioremoval (bioreduction and biosorption) by a highly copper resistant monoculture of Pseudomonas sp. NA and copper bioremoval from soil. Seven bacteria resistant to high concentration of Cu(II) were isolated from enrichment cultures of vineyard soils and mining wastes. Culture parameters influencing copper bioreduction and biosorption by one monoculture isolate were studied. The isolate was identified by 16S rRNA gene sequence analysis as a Pseudomonas sp. NA (98% similarity to Pseudomonas putida, Pseudomonas plecoglossicida and other Pseudomonas sp.). The optimal temperature for growth was 30 °C and bioremoval of Cu(II) was maximal at 35 °C. Considerable growth of the isolate was observed between pH 5.0 and 8.0 with the highest growth and biosorption recorded at pH 6.0. Maximal bioreduction was observed at pH 5.0. Cu(II) bioremoval was directly proportional to Cu(II) concentration in media. Pseudomonas sp. NA removed more than 110 mg L^− 1 Cu(II) in water within 24 h through bioreduction and biosorption at initial concentration of 300 mg L^− 1. In cultures amended with 100 mg L^− 1, 20.7 mg L^− 1 of Cu(II) was biologically reduced and more than 23 mg L^− 1 of Cu(II) was biologically removed in 12 h. The isolate strongly promoted copper bioleaching in soil. Results indicate that Pseudomonas sp. NA has good potential as an agent for removing copper from water and soil.     

不同品质黄铁矿-生物浸出液制剂浸出软锰矿研究

以两种品质不同的黄铁矿经嗜酸铁、硫氧化微生物菌群浸出形成的不同时期浸出液为添加剂,分别对高、低两种品位的软锰矿与黄铁矿进行了共浸出研究。结果表明,微生物-黄铁矿浸出液的浸出时期,黄铁矿的品质和浸锰反应温度都会影响锰浸出率。第8天生物-黄铁矿浸出液添加剂对两种锰矿中锰的浸出率分别是第6天的1.73倍(品位7%)和2.4倍(品位25%)。高品质黄铁矿体系在处理高品位锰矿时的效果要优于低品质黄铁矿,反之亦然。浸锰反应温度对浸出效率的影响最为显著,90℃下各个体系锰浸出率均高出30℃体系1倍以上。黄铁矿-微生物浸出液添加剂通过提供高ORP环境和酸性环境提高黄铁矿-软锰矿浸出系统中黄铁矿还原态离子的溶出达到提高锰浸出率的作用,反应温度可以明显加速这个过程。     

硫化矿细菌浸出机理及协同作用研究现状

细菌浸出作为一种经济、环保的处理技术,广泛应用于金属硫化物的金属提取和预处理过程中。为进一步理解细菌在硫化物浸出过程中的作用,详细阐述了细菌在浸出过程中的作用机理及其在矿物表面的作用机制,系统描述了金属硫化物溶解的硫代硫酸盐与多硫化合物途径。同时,还重点介绍了常见浸矿细菌的生存环境,并对不同种类浸矿细菌之间的协同作用进行了分析。     

钼尾矿中钼、铜和铁的生物浸出实验研究

使用浸矿微生物对钼尾矿进行生物浸出,在钼尾矿质量10 g、矿浆浓度10%(w/v)、微生物加入量10 mL(微生物初始浓度2×10⁷个/L)、浸出温度28 ℃条件下,经过21 d生物浸矿,钼尾矿中的Mo、Cu和Fe浸出率分别达到82.87%、83.73%和88.78%,钼尾矿中的重金属含量大大降低。物相分析结果表明,浸矿微生物对尾矿中的辉钼矿、黄铁矿和黄铜矿的氧化作用,以及铁离子对辉钼矿的化学浸出作用,实现了尾矿中Mo、Cu和Fe的有效浸出。