Bioleaching of low-grade copper sulfide ores by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans

The grown conditions of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were investigated,and then experiments were conducted to research the bioleaching behaviors of crude ore of copper sulfide and hand-picked concentrates of chalcopyrite by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans.The experimental results show that the bacteria grow best when the temperature is(30±1) °C and the pH value is 2.0.The bacteria concentration is 2.24×107 mL-1 in this condition.It is found that the copper extraction yield is affected by the inoculum size and the pulp density and the extraction yield increases as the inoculum size grows.The bioleaching rates reach their highest point in sulfide copper and chalcopyrite with a pulp density of 5% and 10%,respectively.Column flotation experiments of low-grade copper sulfide ores show that the bioleaching recovery reaches nearly 45% after 75 days.

Bioleaching of complex polymetallic sulfide ores by mixed culture

Bacterial leaching of single sulfide minerals and polymetallic sulfide ores was operated in shake flasks and small-scaled columns.The results show that bioleaching of jamesonite is not accessible,the iron extraction rate of pyrrhotite bioleaching reaches 98.2% after 26 d,and the zinc extraction rate of marmatite bioleaching reaches 92.3%,while the corresponding iron extraction reaches only 13.6% after 29 d.Pulp density has a significant effect on metal extraction of pyrrhotite and marmatite bioleaching.The corresponding metal extraction rate decreases with the increase of pulp density.For the polymetallic sulfide ores,zinc extraction of 97.1% is achieved after bioleaching in shake flasks for 10 d,while only 7.8% is obtained after bioleaching in small-scaled column.Analytical results of scanning electron microscopy(SEM) and energy dispersive X-ray analysis(EDX) reveal that large amount of calcium sulfate is formed on the mineral surface.

Catalytic mechanism of manganese ions and visible light on chalcopyrite bioleaching in the presence of Acidithiobacillus ferrooxidans

The bioleaching of chalcopyrite is low cost and environmentally friendly,but the leaching rate is low.To explore the mechanism of chalcopyrite bioleaching and improve its leaching rate,the effect and mechanism of manganese ions(Mn^(2+))and visible light on chalcopyrite mediated by Acidithiobacillus ferrooxidans(A.ferrooxidans)were discussed.Bioleaching experiments showed that when both Mn^(2+)and visible light were present,the copper extraction was 14.38%higher than that of the control system(without Mn^(2+)and visible light).Moreover,visible light and Mn^(2+)promoted the growth of A.ferrooxidans.Scanning electron microscopy(SEM)and energy dispersive spectrometer(EDS)analysis revealed that Mn^(2+)promoted the formation of extracellular polymeric substance(EPS)on the surface of chalcopyrite,changed the morphology of A.ferrooxidans,enhanced the adsorption of bacteria on chalcopyrite surface with light illumination,and thus promoted the bioleaching of chalcopyrite.UV–vis absorbance spectra indicated that Mn^(2+)promoted the response of chalcopyrite to visible light and enhanced the catalytic effect of visible light on chalcopyrite bioleaching.Based on X-ray photoelectron spectroscopy(XPS),the relevant sulfur speciation of chalcopyrite before and after bioleaching were analyzed and the results revealed that visible light and Mn^(2+)promoted chalcopyrite bioleaching by reducing the formation of passivation layer(S_(n)^(2-)/S0).Investigation into electrochemical results further indicated that Mn^(2+)and visible light improved the electrochemical activity of chalcopyrite,thus increasing the bioleaching rate.

Inhibition of hematite on acid mine drainage caused by chalcopyrite biodissolution

Even though biodissolution of chalcopyrite is considered to be one of the key contributors in the formation of acid mine drainage(AMD),there are few studies to control AMD by inhibiting chalcopyrite biodissolution.Therefore,a novel method of using hematite to inhibit chalcopyrite biodissolution was proposed and verified.The results indicated that chalcopyrite biodissolution could be significantly inhibited by hematite,which consequently decreased the formation of AMD.In the presence of hematite,the final biodissolution rate of chalcopyrite decreased from 57.9%to 44.4%at 20 day.This in turn suggested that the formation of AMD was effectively suppressed under such condition.According to the biodissolution results,mineral composition and morphology analyses,and electrochemical analysis,it was shown that hematite promoted the formation and accumulation of passivation substances(jarosite and Cu2-xS)on chalcopyrite surface,thus inhibiting the biodissolution of chalcopyrite and limiting the formation of AMD.

不同晶型磁黄铁矿活化PDS降解工业废水中常见的罗丹明B:性能差异和机理

本文研究了天然六方磁黄铁矿(HNP,Fe_(0.93)S)与天然单斜磁黄铁矿(MNP,Fe_(0.85)S)活化过硫酸盐(PDS)降解罗丹明B(RhB)的性能差异及其机理。结果表明,在酸性和弱碱性条件下,MNP/PDS体系的降解效率(pH=4时为97.15%)均高于HNP/PDS体系(pH=4时为86.91%),且两个体系的降解效率均随pH的升高而降低。MNP/PDS体系较高的降解效率与体系中较高的溶解铁浓度和MNP表面较强的反应性有关,且后者是主要因素,即降解反应主要发生在磁黄铁矿的表面及近表面处。MNP较强的表面反应性首先体现在其相对较高的Zeta电位,这使得MNP与PDS之间的静电引力更强,PDS更容易被MNP活化。其次,MNP表面具有更高的腐蚀电流密度,这有利于Fe(Ⅱ)对PDS的非均相活化以及表面还原性硫物种(如S^(2-)和S_(2)^(2-))作为电子给体将Fe(Ⅲ)还原为Fe(Ⅱ)(或Fe^(3+)还原为Fe^(2+))。此外,MNP表面的疏松氧化层在降解过程中容易脱落,进而暴露出新的表面活性位点。

微生物作用下含银固体废弃物催化黄铜矿浸出动力学研究

银能有效地催化黄铜矿浸出,本文使用含银固体废弃物作为催化剂,研究了不同黄铜矿/含银固体废弃物配比下的浸出动力学行为。体系的生物浸出行为表明,含银固体废弃物能有效催化浸出黄铜矿。固体废弃物的加入使得体系的氧化还原电位远高于其他学者所提出的最适电位区间(380~480 mV vs Ag/AgCl),体系浸出温度与铜浸出率呈正相关性。在此浸出条件下,黄铜矿的生物浸出主要由扩散控制,表面活化能Ea为28.24 kJ/mol。本工作对推广微生物作用下银催化黄铜矿浸出的工业应用有参考价值。

中等嗜热混合菌介导的不同产地斑铜矿浸出差异的比较

本文通过嗜铁钩端螺旋菌、嗜酸喜温硫杆菌以及嗜热硫氧化硫化杆菌三种中等嗜热混合菌对三种不同产地的斑铜矿进行生物浸出,结合X射线光电子能谱(XPS)、X射线衍射(XRD)和扫描电子显微镜(SEM)研究了不同产地斑铜矿浸出行为的差异性。浸出实验结果表明,与空白组相比,生物浸出组的浸出效率和氧化还原电位有显著提高。三种斑铜矿的铜浸出率在前12天一直快速增长,18天后不再增长,此时浸出率分别83.7%,96.5%,86.6%。浸出渣的XRD结果表明,三种斑铜矿在浸出后期均产生黄钾铁矾,其中大冶和云南的浸出渣中含有大量的硫元素。XPS分析和扫描电子显微镜实验结果表明,矿渣表面是黄钾铁矾,浸出渣中几乎没有铜。

极端嗜热菌群在70℃柱浸反应器中浸出低品位硫化铜矿

本文研究了分别引入具有不同Cu^2+抗性的M.sedula菌株对极端嗜热菌群(由A.brierleyi DSM1651和M.hakonensis HO1-1组成)在70℃柱浸反应器中浸出硫化铜矿的影响。引入Cu^2+敏感的M.sedula cop A突变菌株对硫化铜矿的浸出几乎没有影响,铜浸出率没有提高。然而,引入Cu^2+抗性M.sedula ARS50-2能显著地强化浸出过程,铜浸出率在第58天提高了27.77%。第24天后浸出液的pH表明M.sedula ARS50-2的加入能提高极端嗜热菌群的硫氧化活性。定量PCR数据表明在浸出过程中,各反应器中矿物表面与浸出液中的极端嗜热菌群群落结构不同。极端嗜热菌在浸出过程中主要吸附在矿物表面。M.hakonensis HO 1-1是浸出过程中各个反应器矿物表面的主要菌株。M.sedula ARS50-2在浸出的第34天仍然是矿物表面的主要的菌株。A.brierleyi DSM1651是浸出过程中各柱浸反应器浸出液中的主要菌株。相关数据表明加入高Cu^2+抗性菌株有利于极端嗜热菌在高浓度Cu^2+胁迫条件下对硫化铜矿的浸出。

黄铜矿与黄铁矿的生物浸出过程中Sulfobacillus thermosulfidooxidans ST胞外DNA的差异性研究

选取Sulfobacillus thermosulfidooxidans ST用于黄铁矿和黄铜矿的生物浸出实验。吸附实验表明,相较于黄铜矿,细菌更多地吸附在黄铁矿的表面。实验使用DNaseI特异性去除胞外DNA(eDNA)来研究e DNA在生物浸出过程中的作用,eDNA的缺失使吸附在黄铜矿和黄铁矿表面的细菌数量大量减少,菌种生长周期延长,并且黄铁矿和黄铜矿的最终浸出率分别降低了11.6%和20.5%。同时,基于荧光染料的方法评估生物浸出过程中分泌的eDNA的形成和分布,并选择共聚焦激光扫描显微镜(CLSM)可视化了矿物表面的吸附菌和e DNA。eDNA的产量随着生物浸出时间的延长而增加。此外,吸附在黄铁矿表面的ST菌比吸附在黄铜矿表面的Sulfobacillus thermosulfidooxidansST菌有更高的e DNA产量。综上结果表明,eDNA的去除对黄铜矿的生物浸出比对黄铁矿的生物浸出具有更大的影响。

硫化矿物生物冶金:微生物-化学协同湿法冶金过程及酸性矿山废水的环境保护情况

生物冶金是用于处理低品位矿物的一项必要的技术,与传统的火法冶金方法相比,它具有成本低和环境友好的优势。然而,生物浸出过程中矿物表面有钝化膜生成,使得其浸出效率较低。因此,对微生物存在下硫化矿物的溶解和钝化机理的研究有着重要意义。生物冶金有利于金属的提取,但它也是一把双刃剑,会引起一系列严重的环境问题,例如产生酸性矿山废水等。本文概述了一些常见硫化矿物生物浸出过程的研究以及对酸性矿山废水的环境保护情况。

PEG-2000液氮保藏混合浸矿菌对黄铜矿生物浸出的影响

首先,富集到具有浸矿能力的混合培养物,然后,以PEG-2000作为保护剂,对混合培养物液氮冷冻保藏6个月和12个月,对其保藏前、后黄铜矿的浸出能力、活性和多样性进行比较。结果表明,当用原始培养物浸出黄铜矿时,20天内铜的浸出率为95.7%。冷冻保藏6个月后,混合培养物的铜浸出率在25天内为94.9%,保藏12个月后,在35天内为93.6%。保藏6个月和12个月后,混合菌种的活性分别达到87%和41%。此外,对原始培养物进行生态学分析,鉴定得到Acidithiobacillus ferrooxidans,Acidithiobacillus caldus,Sulfobacillus thermotolerans和Pseudomonas aeruginosa。冷冻保藏12个月后,混合培养物的群落组成发生了变化,但优势菌群依然存在。

极端嗜酸古菌Ferroplasma thermophilum合成胞内含钴铁纳米颗粒

本文研究一种极端嗜酸古菌Ferroplasma thermophilum合成胞内含铁钴的纳米颗粒。通过冷冻切片和透射电镜发现纳米颗粒的大小在20~60nm,其数目在每个细胞中平均超过30个,这表明Ferroplasma thermophilum不仅可以合成胞内纳米颗粒,还是一种高产菌。更有趣的是,通过EDS X-ray分析表明,纳米颗粒的元素组成包含铁与钴,这表明铁与钴都参与了纳米颗粒的合成。更重要的是,在不同能源物质由硫酸亚铁与黄铜矿的培养下,发现Ferroplasma thermophilum所合成的纳米颗粒大小与形态不同。进一步研究表明,这一现象与培养基中最初铁离子浓度和电位有关,在高初始铁离子浓度培养下,Ferroplasma thermophilum所合成的纳米颗粒较大,低电位导致纳米颗粒形态不均一,原因在于高初始铁离子浓度与低电位促进了Ferroplasma thermophilum铁离子的吸收。我们的研究丰富了磁性细菌的趋磁种类,增加了微生物合成胞内纳米颗粒的多样性,尤其是钴的参与。

氧化还原电位在黄铜矿生物湿法冶金中的作用及其调控:综述

黄铜矿是一种重要的铜资源,但由于黄铜矿晶格能较高,溶解动力学较低,导致其在湿法冶金过程中浸出效率不理想。为了解决这一问题进行了一系列新技术的研究,包括对高效菌株的选育,抑制在矿物表面钝化膜的生成,以及控制溶液氧化还原电位在最佳区间内。目前,对前两个技术的研究工作已有大量的总结,而对于控制氧化还原电位这一过程的工作总结较少。本文通过研究近年来的相关工作,介绍了铜湿法冶金过程中溶液氧化还原电位的定义、作用以及对氧化还原电位的控制等相关内容。

黄铁矿生物浸出过程中在不同生长时期引入Leptospirillum ferriphilum YSK对土著浸矿微生物群落结构和功能的影响

在含有0.5%(W/V)黄铁矿的改良9K培养基中,添加Leptospirillum ferriophilum YSK到天然生物浸出菌群中,包括Acidithiobacillus caldus,A.thiooxans,Sulfobacillus thermosfidooxans,Acidiphilium spp.和Ferrodium thermophilum,浸出率明显提高,并用实时荧光定量PCR和功能基因芯片监测群落结构和基因表达的变化。加入L.ferriophilum YSK后群落内不同种群间的动态变化不同,促进A.caldus S1,A.thiooxans A0,Acidiphillum spp.DX1-1的生长,抑制了Ferroplasma L1和S.Thermosulfidooxidans ST的生长,但对A.ferrooxidans CMS的影响不大。功能基因芯片分析发现:来自L.ferriphilum的编码ADP heptose,phosphoheptose isomerase,glycosyltransferase,biotin carboxylase和protoheme ferrolyase的基因,以及来自Acidiphillum spp编码的acetyl-Co A carboxylase和来自A.caldus的dox D基因在引种后0~20 h内表达水平上调;来自A.ferrooxidans编码的lipid A disaccharide synthase Lpx B,glycosyl transferase和ADP heptose synthase的基因在引种后0~8h表达水平上调,在8~20h下调;来自Ferroplasma sp.编码的ferredoxin oxidoreductase的基因在引种后0~4 h表达水平上调,而在4~16 h表达水平下调,在16~20 h表达上调;来自A.ferrooxidans的Cbb S基因在引种0~20 h表达水平下调。