3种典型能量代谢菌浸出黄铜矿及其硫形态的转化

比较了3种典型嗜中温铁/硫代谢菌——Acidithiobacillus ferrooxidans、Leptospirillum ferriphilum及Acidithiobacillus thiooxidans单独及混合浸出黄铜矿过程中细菌硫氧化、铁氧化情况。同时利用XRD、硫的K边X射线吸收近边结构光谱(XANES)等分析手段研究3种细菌单独/混合浸出黄铜矿过程中矿物组成成分和矿物表面硫的形态变化。结果表明:在浸出初期电位低于400 mV(vs SCE)时,黄铜矿的浸出速率较快,此后电位迅速升高至540 mV,黄铜矿浸出速率明显变慢。混合菌浸出时体系的硫/铁氧化活性较单一菌高,根据XANES拟合分析发现,混合菌浸出时矿物表面元素硫及黄钾铁矾积累量明显减少,浸出初期辉铜矿产量明显高于单一细菌浸出的。     

某微细粒砷黄铁矿包裹金矿的非氰浸出研究

采用非氰浸化剂(石硫合剂)对含金为2.47 g/t的甘肃某微细粒砷黄铁矿包裹金矿进行浸出试验,研究预处理方式和浸出工艺对金浸出率的影响。结果表明,石硫合剂对金的直接搅拌浸出率低于30%,该矿属难浸金矿石;采用边磨边浸-搅拌浸出的方式,浸出率可提升至68.4%;增加碱式预氧化处理,可将金的浸出率进一步提升到80%以上。采用最优的工艺,边磨边碱式预氧化36 h,经石硫合剂搅拌浸出5 h,金的浸出率可达到91.5%。     

古菌生物浸出黄铜矿过程中的表观硫氧化活性表征

对4株纯的极端嗜热古菌及它们的混合菌在生物浸出黄铜矿过程中的硫氧化活性进行对比研究。结果表明,混合菌比纯菌拥有更高的硫氧化活性,它大幅度促进黄铜矿浸出率的提高。表征嗜热古菌硫氧化活性的参数值通常受很多因素的影响,以致在不同的硫氧化菌和不同的条件下生物浸出黄铜矿时,这些参数很难准确地反映出相应的硫氧化活性。因此,期待找到一种能有效表征浸矿菌硫氧化活性的方法。     

聚乙二醇对氧化亚铁硫杆菌浸出黄铜矿的影响

为提高黄铜矿生物浸出率,研究聚乙二醇(PEG)对Acidithiobacillus ferrooxidans strain XZ11 Fe2+氧化活性和黄铜矿生物浸出过程的影响,并采用SEM和EDS对浸出后矿物表面形貌和相组成进行表征。结果表明:相对分子质量大于200的PEG对Acidithiobacillus ferrooxidans Fe2+氧化活性具有一定的促进作用,添加30 mg/L PEG 2000时,浸出20 d后,铜浸出量高达451.70 mg/L,较不添加FEG时提高了1.11倍;添加PEG时,黄铜矿表面的侵蚀面呈沟壑状,出现溶蚀坑,并生成Fe3+的羟基化多聚物Fe(Ⅲ)—O—OH。PEG的添加提高了浸出体系中细菌浓度和Fe3+浓度,加速了黄铜矿的溶解。     

难处理含金硫精矿的焙烧氧化-硫代硫酸盐浸出

为了提高难处理含金硫精矿中金的浸出率,采用同步热分析仪研究在马弗炉中焙烧氧化难处理含金硫精矿的最佳条件,通过优化实验确定硫代硫酸盐浸出的最佳工艺参数。结果表明:在马弗炉中焙烧氧化难处理含金硫精矿最佳条件为在700℃温度下焙烧2 h,难处理含金硫精矿硫的去除率可达94.7%。焙烧后,金的浸出率大幅度提高。使用组成为0.03 mol/L CuSO4、1.0 mol/L NH3·H2O、0.3 mol/L Na2S2O3、0.1 mol/L(NH4)2SO4和0.3 mol/L Na2SO3的硫代硫酸盐溶液作为浸出剂,最佳浸出工艺参数如下:浸出时间18 h、液固比2:1、振荡速度250 r/min、浸出温度50℃。在此浸出工艺参数下,金浸出率达71.2%。     

从脱铜阳极泥中浸出贵金属的预处理工艺研究

采用硫代硫酸盐浸出脱铜阳极泥中的贵金属金、银和钯,研究氧化焙烧、碱预浸出和酸预浸出的预处理工艺对提高浸出率的影响。结果表明,3种预处理方式可在不同程度上降低硫、砷、锑、铅等元素对浸出效率的影响,采用氧化焙烧-酸预浸出-硫代硫酸盐浸出的方案,金、银和钯的浸出率分别达到了93.45%、96.32%和76.04%。     

高通量测序技术分析不同温度下赞比亚低品位铜矿生物浸出过程中的微生物多样性

与传统微生物生态学分析方法相比,近几年高通量测序以速度快、通量高、低成本等特征在微生物多样性检测方面得到了充分应用,并采用此方法研究温度对微生物浸出赞比亚一种低品位铜矿的效率和群落生态的影响。结果表明:在30℃和45℃浸出条件下,铜浸出率分别为64.2%和69.4%,45℃条件下获得了较高铜浸出率。采用高通量Illumina Miseq测序技术分析30℃和45℃浸出条件下微生物群落结构及其动态变化,当浸出温度为30℃,Acidithiobacillus caldus和Acidiphilium sp.是主要浸矿菌;当浸出温度为45℃时,Sulfobacillus sp.和Acidithiobacillus caldus是优势种群。     

阴离子对嗜酸氧化亚铁硫杆菌生长和硫氧化活性的影响

以嗜酸氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans, ATCC23270)为对象,研究NO_3~-、SO_4~(2-)、Cl~-和PO_4~(3-)对Acidithiobacillus ferrooxidans生长和硫氧化活性的影响.结果表明:不同阴离子对Acidithiobacillus ferrooxidans硫氧化表观活性的影响效应不同,其影响由大到小的顺序依次为Cl~-,NO_3~-,SO_4~(2-)和PO_4~(3-);在高浓度PO_4~(3-)的胁迫(300 mmol/L)下,细菌所表达蛋白质的总数量减少,但同时表达一些特异性蛋白质,这说明细菌可通过抑制一些在正常条件下表达的蛋白质,同时表达一些新的蛋白质来应对无机离子的胁迫效应.     

表面活性剂Tween-80对Acidithiobacillus ferrooxidans硫氧化和硫代谢相关蛋白质基因表达的影响(英文)

研究了表面活性剂 Tween-80 对 Acidithiobacillus ferrooxidans ATCC 23270 生长、硫氧化和硫代谢相关典型基因表达的影响。结果表明,当培养基中含有 10 2g/L Tween-80 时,A. ferrooxidans 的生长以及其对不溶性底物(S0和 CuFeS2)的代谢得到了促进。在该条件下,经过 24 d 的生物浸出,黄铜矿的铜离子浸出率比对照组(不含 Tween-80)高 16%。FT-IR 光谱分析表明,这可能是由于 Tween-80 的存在而导致胞外多聚物成分发生变化而引起的。用 RT-qPCR 来分析 17 个硫代谢相关基因在 Tween-80 存在时的表达差异。胞外蛋白质基因表达下调表明了Tween-80 对细菌硫吸附作用的影响。硫代谢相关酶基因表达水平的变化为硫代谢的研究提供了参考。     

Effects of microorganisms on surface properties of chalcopyrite and bioleaching

The alteration of surface properties of chalcopyrite after biological conditioning with Acidithiobacillusferrooxidans and Acidithiobacillus caldus was evaluated by Zeta-potential, adsorption studies, FT-IR spectra and contact angle measurement. The Zeta-potential studies show that the iso-electric point（IEP） of chalcopyrite after bacterial treatment moves towards the IEP of pure cells, indicating the adsorption of cells on chalcopyrite surface. The FT-IR spectra of chalcopyrite treated with bacterial cells show the presence of the cell functional groups signifying cells adsorption. Due to the formation of elemental sulfur and intermediate copper sulphides on chalcopyrite surface, the contact angle and surface hydrophohicity of chalcopyrite increase at the initial bioleaching stage. Chalcopyrite bioleaching by Acidithiobacillus ferrooxidans has higher copper extraction, which agrees with the fact that Acidithiobacillus ferrooxidans adsorbed on chalcopyrite surface is much more than Acidithiobacillus caldus. The results support the direct mechanism of sulfide oxidations in bioleaching chalcopyrite.     

Control of redox potential by oxygen limitation in selective bioleaching of chalcocite and pyrite

Based on the bioleaching mechanism and electrochemical studies of metal sulfides, the dissolution rates of chalcocite and pyrite are controlled by redox potentials. Experiment on the bioleaching of chalcocite and pyrite under constant redox potential by sparging with nitrogen gas was demonstrated. By leaching at low and constant redox potential（〈760 mV, vs SHE）, copper recoveries of 90 %–98 % are achieved, which are 10 times more than iron recoveries. The iron-oxidizing bacterial populations are observed to continue to reduce under oxygen limitation conditions, but the Acidithiobacillus that have only sulfur-oxidizing capabilities are an attractive alternative for redox-controlled bioleaching of chalcocite.Thus, the described redox control technique might be one of the effective approaches to balance acid and iron in Zijinshan copper bio-heap leaching practice.     

Liquid-nitrogen cryopreservation of three kinds of autotrophicbioleaching bacteria

Three kinds of autotrophic bioleaching bacteria strains, including mesophilic and acidophilic ferrous ion-oxidizing bacteria Acidithiobacillus ferrooxidans （A. ferrooxidans）, mesophilic and acidophilic sulfur-oxidizing bacteria Acidithiobacillus thiooxidans （A. thiooxidans）, and moderately thermophilic sulfur-oxidizing bacteria Acidianus brierleyi, were cryopreserved in liquid nitrogen and their ferrous ion- or sulfur-oxidizing activities were investigated and compared with the original ones. The results revealed that ferrous ion/sulfur oxidation activities of the strains were almost equal before and after cryopreservation. Glycerin was used as cryoprotective agent. In conclusion, liquid-nitrogen cryopreservation is a simple and effective method for autotrophic bioleaching microorganisms.     

Bacterial leaching of chalcopyrite and bornite with native bioleaching microorganism

A native mesophilic iron-oxidizing bacterium, Acidithiobacillus ferrooxidans, has been isolated （30 ℃） from a typical, lead-zinc concentrate of Dachang Mine in the region of Liuzhou located in the southwest of China. Two typical copper sulfide minerals, chalcopyrite and bornite, were from Meizhou Copper Mine in the region of Guangdong Province, China. Variation of pH and cell growth on time and effects of some factors such as temperature, inoculation cell number, and pulp density on the bioleaching of chalcopyrite and bornite were investigated. The results obtained from the bioleaching experiments indicate that the efficiency of copper extraction depends on all of the mentioned variables, especially the pulp density has more effect than the other factors on the microorganism. In addition, the results show that the maximum copper recovery was achieved using a mesophilic culture. The copper dissolution reached 51.34% for the chalcopyrite while it was 72.35% for the bornite at pH 2.0, initial Fe（ Ⅱ ） concentration 9 g/L and pulp density 5%, after 30 d.     

Bioleaching of chalcopyrite by pure and mixed culture

The bioleaching of chalcopyrite in shake flasks was investigated by using pure Acidithiobacillusferrooxidans and mixed culture isolated from the acid mine drainage in Yushui and Dabaoshan Copper Mine in China, marked as YS and DB, respectively. The mixed culture consisted mainly of Acidithiobacillus fOrrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum spp. （Leptospirillum ferriphilum and Leptospirillum ferrooxians）. The results show that the mixed culture is more efficient than the pure Acidithiobacillus ferrooxidans because of the presence of the sulfur-oxidizing cultures that positively increase the dissolution rate and the recovery of copper from chalcopyrite. The pH value decreases with the decrease of chalcopyrite leaching rate, because of the formation ofjarosite as a passivation layer on the mineral surface during bioleaching. In the bioleaching using the mixed culture, low pH is got from the sulfur oxidizing inhibiting, the formation ofjarosite. The copper extraction reaches 46.27% in mixed culture and 30.37% in pure Acidithiobacillusferrooxidans after leaching for 75 d.     

Isolation and identification of moderately thermophilic acidophilic iron-oxidizing bacterium and its bioleaching characterization

A moderately thermophilic acidophilic iron-oxidizing bacterium ZW-1 was isolated from Dexing mine, Jiangxi Province, China. The morphological, biochemical and physiological characteristics, 16S rRNA sequence and bioleaching characterization of strain ZW-1 were studied. The optimum growth temperature is 48 ℃, and the optimum initial pH is 1.9. The strain can grow autotrophically by using ferrous iron or elemental sulfur as sole energy sources. The strain is also able to grow heterotrophically by using peptone and yeast extract powder, but not glucose. The cell density of strain ZW-1 can reach up to 1.02×108 /mL with addition of 0.4 g/L peptone. A phylogenetic tree was constructed by comparing with the published 16S rRNA sequences of the relative bacteria species. In the phylogenetic tree, strain ZW-1 is closely relative to Sulfobacilus acidophilus with more than 99% sequence similarity. The results of bioleaching experiments indicate that the strain could oxidize Fe2+ efficiently, and the maximum oxidizing rate is 0.295 g/(L·h). It could tolerate high concentration of Fe3+ and Cu2+ (35 g/L and 25 g/L, respectively). After 20 d, 44.6% of copper is extracted from chalcopyrite by using strain ZW-1 as inocula.     

Catalytic effect of activated carbon on bioleaching of low-grade primary copper sulfide ores

The catalytic effect of activated carbon on the bioleaching of low-grade primary copper sulfide ores using mixture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was investigated. The results show that the addition of activated carbon can greatly accelerate the rate and efficiency of copper dissolution from low-grade primary copper sulfide ores. The solution with the concentration of 3.0 g/L activated carbon is most beneficial to the dissolution of copper. The resting time of the mixture of activated carbon and ores has an impact on the bioleaching of low-grade primary copper sulfide ores. The 2 d resting time is most favorable to the dissolution of copper. The enhanced dissolution rate and efficiency of copper can be attributed to the galvanic interaction between activated carbon and chalcopyrite. The addition of activated carbon obviously depresses the dissolution of iron and the bacterial oxidation of ferrous ions in solution. The lower redox potentials are more favorable to the copper dissolution than the higher potentials for low-grade primary copper sulfide ores in the presence of activated carbon.     

绢云母对黄铜矿微生物浸出的影响

采用以Acidithiobacillus ferrooxidans为主的混合菌,研究绢云母对微生物浸出黄铜矿的影响。结果表明,铜的浸出率随着绢云母粒度的减小而增加,随着绢云母质量分数的增加而呈先升高后降低的趋势。在添加粒度为-33μm、质量分数为5.0%的绢云母时,铜的最高浸出率为54.88%,比不添加绢云母时的铜浸出率提高了约12%,表明绢云母能促进黄铜矿的微生物浸出。绢云母的加入可使浸出体系pH值降低,最终pH值低于1.22。在浸出过程中,新生成的物质主要是铵黄铁矾,它覆盖于黄铜矿的表面,对微生物浸出铜有一定的阻碍作用。     

Comparative study on bioleaching of two different types of low-grade copper tailings by mixed moderate thermophiles

The bioleaching of two different types of low-grade copper tailings, acid-leaching tailings (ALT) and copper flotation tailings (CFT) by mixed moderate thermophiles, and the variation of mineralogical and microbiological characteristics during their dissolution processes were comparatively investigated. Results showed that bioleaching behaviors of the two types of tailings were significantly different. In ALT bioleaching, lower redox potential, higher [Fe³⁺]/[Fe²⁺] ratio and higher cell density in solution were obtained. These resulted in higher total copper, primary copper sulfide and secondary copper sulfide extractions, compared with CFT bioleaching. X-ray diffraction analysis suggested that gypsum and some metal organic complexes were detected in CFT bioleaching, which could cause the sluggish oxidation of sulphide minerals. The shifts of microbial community in the leachates and leaching residues varied greatly between ALT and CFT bioleaching. The percentage of iron-oxidizing bacteria in ALT bioleaching was higher than that of CFT, but the sulfur-oxidizing bacteria percentage was the opposite. The archaeon F. thermophilum L1 was detected in ALT but not in CFT.     

嗜酸氧化亚铁硫杆菌（ATCC 23270）浸出黄铜矿过程中的EPS、Cu2+和Fe3+的相互作用机制（英文）

采用超声-离心方法提取嗜酸氧化亚铁硫杆菌(ATCC 23270)胞外多聚物(EPS)、EPS中的Cu2+、Fe3+离子,研究生物浸出黄铜矿过程中Cu2+、Fe3+和EPS的相互作用机制。结果表明:与Fe3+离子相比,Cu2+离子可刺激细菌产生更多的EPS;当Cu2+离子浓度从0.01mol/L增加到0.04mol/L时,EPS中Fe3+/Cu2+质量比从4:1降低到2:1;从1%黄铜矿的无铁9K介质中提取的EPS中铜铁含量是从含0.04mol/LCu2+离子的9K介质中提取的量的2倍。在生物浸出黄铜矿过程中,黄铜矿表面结合黄铁钾钒的EPS层减弱了Cu2+、Fe3+离子的迁移,逐渐成为离子扩散壁垒。