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。     

混合嗜热古菌在65°C生物浸出黄铜矿过程中活性炭的催化作用和钝化现象的相关性（英文）

研究活性炭对四株典型嗜热古菌混合培养物(Acidianus brierleyi,Metallosphaera sedula,Acidianus manzaensis和Sulfolobus metallicus)在65°C时浸出纯黄铜矿过程中活性炭的催化作用和钝化现象的相关性。浸出实验表明,活性炭能够有效地促进黄铜矿的生物浸出和化学浸出。基于同步辐射技术的X射线衍射、铁的L-边和硫的K-边X射线吸收近边结构光谱学分析表明,在生物浸出过程中当氧化还原电位较低((27)400 mV)时,活性炭能通过原电池反应改变电子传递途径,生成更易溶解的次生矿物辉铜矿,从而增强黄铜矿的浸出。在添加活性炭的生物浸出过程的前期,黄钾铁矾迅速累积但铜离子的浸出速率未受到抑制,然而在生物浸出的后期,大量黄钾铁矾沉淀在矿物表面,从而抑制黄铜矿的进一步溶解。在添加活性炭时检测到了更多的单质硫,但由于嗜热古菌混合培养物具有很强的硫氧化活性,所以生成的单质硫被其消解,因此,未检测到其对黄铜矿浸出有显著影响。     

黄铁矿对砷黄铁矿生物浸出的影响

为探明黄铁矿在砷黄铁矿生物浸出过程中的作用与影响,选择纯黄铁矿和砷黄铁矿组成的矿浆浸出体系,考察黄铁矿和砷黄铁矿质量比以及黄铁矿粒度对体系中砷的浸出率以及砷的氧化状态的影响。结果表明：砷的浸出率随黄铁矿与砷黄铁矿质量比的增加而升高,随黄铁矿粒度的增加而减少。当黄铁矿的粒度小于74μm、黄铁矿与砷黄铁矿质量比为10：2时,砷的最高浸出率为97.7%,比不添加黄铁矿时砷的浸出率提高了约43.18%。且黄铁矿可以加速As(Ⅲ)转化为As(Ⅴ),降低矿浆对细菌的毒害,使生物浸出体系细菌密度提高、pH下降、氧化还原电位φh升高并与砷黄铁矿形成原电池效应,从而促进砷黄铁矿的浸出。     

元素硫对黄铜矿生物浸出行为及群落结构的影响(英文)

研究3种典型铁/硫代谢菌—Acidithiobacillus ferrooxidans,Leptospirillum ferriphilum及Acidithiobacillus thiooxidans混合浸出黄铜矿过程中铁/硫氧化活性、群落结构(PCR-RFLP)的变化,以及不同浓度的元素硫对其影响。结果发现,加入3.193g/L元素硫能促进细菌的表观硫氧化活性,改变浸矿体系的群落结构,并进一步影响钝化层的形成、金属离子的溶出,其浸出率(71%)较未添加硫的(67%)有一定程度的提高。而过量的元素硫会抑制铜的浸出(浸出率44%)。     

黄铁矿对硫砷铜矿化学浸出的促进作用

为了考查黄铁矿对硫砷铜矿浸出的影响,在添加黄铁矿、常压化学浸出条件下研究硫砷铜矿的浸出动力学和电化学。采用自制浸出装置在H_2SO_4-Fe_2(SO_4)_3体系中开展混合矿物化学浸出实验。结果表明:添加黄铁矿后硫砷铜矿的表观活化能降低至48.15kJ/mol;随着黄铁矿加入比例的升高,硫砷铜矿的浸出率逐渐提高,当硫砷铜矿与黄铁矿质量比为1:6时,12天硫砷铜矿的浸出率可达23.6%。通过XPS分析了混合矿物表面化学浸出前后硫和砷形态的变化,加入黄铁矿后促进砷转化为五价砷,降低毒性。电化学工作站测定硫砷铜矿的静止电位为0.48 V,无菌条件下的电化学行为解释了黄铁矿和硫砷铜矿混合化学浸出时形成原电池,促进了硫砷铜矿的溶解。     

利用生物质从黄铜矿和辉铜矿混合矿中可持续提取铜（英文）

本文阐述提铜工艺的可持续性。实际上,针对混合硫化矿(黄铜矿和辉铜矿),尝试在33.3℃下使用中温混合菌群的提铜工艺和三价铁浸出过程。其中,生物浸出实验是在矿石粒径-75+53μm范围内完成的。采用细菌作为催化剂,铜收率达65.50%。另一方面,在三价铁浸出过程中,矿石粒径为-53+38μm,温度升高至70℃时,铜收率提高到78.52%。与高温浸出过程相比,中温生物浸出过程在铜的提取中显示出明显的优势。通过SEM-EDS、FTIR和XRD表征,结合各种热力学分析,可以认为间接机理是主要的浸出机理。对于黄铜矿-辉铜矿混合矿而言,浸出机理分为三种过渡产物机理,即多硫化物机理、硫代硫酸盐机理和元素硫机理。铜形态转变为Cu_2S-Cu S-Cu_5Fe S_4-Cu_2S,最后转变为Cu SO_4。在发生亚铁氧化和硫酸铁生成反应的同时,细菌消耗掉硫化矿物,形成强酸,最后在低温下形成Cu SO_4,这种铜生产方案要求室温下氧化还原电位高于550m V,以便有效地提取铜。     

硫铜钴矿生物浸出过程中细菌的作用及其溶解反应途径（英文）

研究硫铜钴矿生物浸出过程中细菌的作用及其溶解反应途径。结果表明,间接作用机制和接触作用机制均对硫铜钴矿生物浸出过程产生影响。当细菌吸附到矿物表面时,矿物溶解速率显著加快,说明浸出过程中接触作用机制对硫铜钴矿的溶解有重要影响。浸出过程中硫元素氧化价态的变化顺序为S-2→S0→S+4→S+6,并有单质硫沉淀在矿物表面,说明硫铜钴矿生物浸出过程按照多硫化物途径进行。硫铜钴矿表面被细菌严重腐蚀,出现许多大小不一的腐蚀坑洞,并有单质硫、硫酸盐及亚硫酸盐生成。这些氧化产物在矿物表面形成一层钝化层。     

硫铜钴矿生物浸出过程中细菌的作用及其溶解反应途径

研究硫铜钴矿生物浸出过程中细菌的作用及其溶解反应途径。结果表明,间接作用机制和接触作用机制均对硫铜钴矿生物浸出过程产生影响。当细菌吸附到矿物表面时,矿物溶解速率显著加快,说明浸出过程中接触作用机制对硫铜钴矿的溶解有重要影响。浸出过程中硫元素氧化价态的变化顺序为S?2→S0→S+4→S+6,并有单质硫沉淀在矿物表面,说明硫铜钴矿生物浸出过程按照多硫化物途径进行。硫铜钴矿表面被细菌严重腐蚀,出现许多大小不一的腐蚀坑洞,并有单质硫、硫酸盐及亚硫酸盐生成。这些氧化产物在矿物表面形成一层钝化层。     

镍黄铁矿电化学生物氧化过程的分解机理(英文)

应用表面粘附和没有粘附Acidithiobacillus ferrooxidans的镍黄铁矿粉末微电极进行电化学测试,以说明镍黄铁矿氧化分解的机理。循环伏安CV结果显示,在-0.2V的低电位区域,在镍、铁离子析出时镍黄铁矿转变为中间相Fe4.5-yNi4.5-xS8-z;当电位在-0.2V到0.2V区间时,有不稳定的紫硫镍矿Fe3Ni3S4和FeNi2S4形成并在表面伴有元素硫的产生;当电位增加到0.2V以上时,不稳定相将全部分解;在高电位0.7V时,析出的亚铁离子被氧化为高铁离子。嗜酸氧化亚铁硫杆菌Acidithiobacillus ferrooxidans的存在使峰电位增高,反应起始电位负移,并对表面形成的元素硫有氧化去除作用。这一过程可通过-0.75到-0.5V电位区间发生的的还原反应证实。生物浸出和电化学实验结果均表明当pH2时溶液酸度的增加对氧化过程有轻度的阻碍作用。     

黄铜矿表面生物氧化膜的形成过程

在细菌浸出黄铜矿的过程中,浸出速率缓慢的原因是矿物表面会形成一层阻碍矿物与浸出液之间物质交换的钝化膜,这层膜的组成会随着浸出的进行而变化.利用SEM,EDS,XRD和XPS等对细菌浸出黄铜矿的过程中,矿物表面的形貌、组成及物相变化进行了研究.结果表明,黄铜矿在细菌浸出过程中依次形成了缺铁铜硫化物Cu_1-xFe_1-yS_z（x0.氧化铁,羟基氧化铁和黄钾铁矾.由于浸矿混合细菌ASH-07对硫的氧化作用.硫化物层和单质硫层都是氧化膜形成过程中的中间产物,致密的黄钾铁矾层则对黄铜矿的浸出产生钝化作用.     

XPS characteristics of sulfur of bio-oxidized arsenic-bearing gold concentrate and changes of surface nature of bio-oxidation residue

During bio-oxidation of sulfides, the chemical state change of sulfur is a complex and key factor. It is not only an indicator of the extent and intensity of the bio-oxidation, but also controls the property of bio-leaching medium and the period of oxidation. The chemical state of sulfur in sulfides oxidized by leaching bacteria was studied with XPS. Sulfide minerals in the arsenic-bearing gold concentrate consist of pyrite, arsenopyrite, chalcopyrite, galena, sphalerite and so on. In order to probe the pattern of the chemical state change of sulfur in the bio-oxidation residue of arsenic-bearing gold concentrate, the structure of the grains, and the surface nature of the residue, XPS test was carried out through different sputtering duration. The study of XPS clearly shows that: sulfides is progressively oxidized from the surface of minerals to the core by leaching bacteria; the chemical valence of sulfur changes from S^2- or [S2]^2- to [SO4]^2- ; sulfur in the core is in a reduction state, S^2- or [S2]^2- , but exists in an oxidation state S^6 on the surface; due to the chemical state change of sulfur, mineral phase of the bio-oxidation residue is also changed(sulfides inside, while sulfates outside); the layered structure is found in the grains of the bio-oxidation residue.     

Acid equilibrium during bioleaching of alkaline low-grade sulfide copper ore

This article reports the study on acid equilibrium during bioleaching of alkaline low-grade copper sulfide ore. Adding auxiliary agents 1# （sulfur） and 2# （pyrite） makes bacterial leaching of copper and acid production carried out simultaneously because the auxiliary agents can be oxidized by bacteria and the oxidation products involve acid. The acid required for dissolving alkaline gangue during bacterial leaching is produced, and acid equilibrium is reached during the ore bio-leaching. The recovery of copper reaches more than 95%.     

硫化锌精矿常压富氧直接浸出行为

借助工艺矿物学分析对常压富氧直接浸出条件下锌精矿中主要硫化物的浸出行为进行研究。结果表明,除黄铁矿外,其他硫化矿均会明显溶解。基于对浸出渣中单质硫与反应残余硫化物之间关系的分析,认为闪锌矿、黄铜矿、铜蓝、方铅矿的溶出可能遵循间接氧化方式,即硫化物首先酸溶,生成的H2S脱离矿物表面并迁移至溶液本体中进而氧化成单质硫。上述硫化矿的浸出过程可能受界面化学反应控制。对于磁黄铁矿的溶出,直接电化学氧化可能起主导作用,其浸出过程可能受产物层单质硫的扩散控制。     

Relatedness between catalytic effect of activated carbon and passivation phenomenon during chalcopyrite bioleaching by mixed thermophilic Archaea culture at 65 °C

The relatedness between catalytic effect of activated carbon and passivation phenomenon during chalcopyrite bioleaching by mixed thermophilic Archaea culture (Acidianus brierleyi, Metallosphaera sedula, Acidianus manzaensis and Sulfolobus metallicus) at 65 °C was studied. Leaching experiments showed that the addition of activated carbon could significantly promote the dissolution of chalcopyrite for both bioleaching and chemical leaching. The results of synchrotron-based X-ray diffraction, iron L-edge and sulfur K-edge X-ray absorption near edge structure spectroscopy indicated that activated carbon could change the transition path of electrons through galvanic interactions to form more readily dissolved secondary mineral chalcocite at a low redox potential (<400 mV) and then enhanced the copper dissolution. Jarosite accumulated immediately in the initial stage of bioleaching with activated carbon but copper dissolution was not hindered. However, much jarosite precipitated on the surface of chalcopyrite in the late stage of bioleaching, which might account for the decrease of copper dissolution rate. More elemental sulfur (S⁰) was also detected with additional activated carbon but the mixed thermophilic Archaea culture had a great sulfur oxidation activity, thus S⁰ was eliminated and seemed to have no significant influence on the dissolution of chalcopyrite.     

Electro-generative mechanism for simultaneous leaching of pyrite and MnO2 in presence of A. ferrooxidans

A dual cell system was used to study the output power, output voltage, galvanic polarization of anode and cathode, and the relationship between the electric quantity（Q） and some factors, such as the dissolved Fe2＋ magnitude, the time in the electro- generative simultaneous leaching with bacteria（BEGSL） and without bacteria（EGSL）. A three-electrode system was adopted to study their individual self-corrosion current, which was smaller compared with the galvanic current. The results show that the output power and voltage in BEGSL are higher than those in EGSL. The accumulated sulfur on the surface of sulfides produced in BEGSL can be oxidized by A. ferrooxidans, and the ratio of biologic electric quantity reaches 51.50% in 72 h. The first stage both in EGSL and in BEGSL is the dissolution of pyrite on the surface to ferrous ion and sulfur element, which was oxidized by A. ferrooxidans in the further procedure.     

微细浸染型金矿强化湿法预处理研究

采用两段充气预处理-非氰化工艺浸出微细浸染型金矿,研究了浸出条件对金浸出效率的影响。结果表明,在氧化和碱浸预处理2个阶段充气可提高金浸出率;氧化预处理2 h后,加入氢氧化钠(20 kg/t)碱浸预处理4 h,加入氧化钙(40 kg/t)替代氢氧化钠,用TY-3浸出剂(8 kg/t)浸出4 h,金浸出率可达87.21%。浸出渣的物相分析、扫描电镜观察及X射线能谱分析结果显示,硅酸盐、碳酸盐中的金可被有效浸出,浸出渣中的石英、黄铁矿表面发生腐蚀,部分黄铁矿氧化。     

Effect of initial pH on chalcopyrite oxidation dissolution in the presence of extreme thermophile Acidianus manzaensis

The influence of initial pH on the chalcopyrite oxidation dissolution at 65 °C was investigated by bioleaching and cyclic voltammetry experiments, and the oxidation products were investigated by XRD and Raman spectroscopy. Bioleaching results show that chalcopyrite dissolution rate increases with the decrease of the initial pH in chemical leaching, while the influence of initial pH on bioleaching is on the contrary. The presence of Acidianus manzaensis does not promote chalcopyrite dissolution under initial pH 1.0, which mainly results from serious inhibition of high acidity to the growth of Acidianus manzaensis. Electrochemical experiments results show that anodic oxidation currents of electrolyte with or without Acidianus manzaensis both increase with the increase of initial pH, and covellite and sulfur are detected on the electrode surface. The results confirm that chalcopyrite dissolution in chemical leaching is under the combined action of oxidation and non-oxidation of proton, with conversion of chalcopyrite to covellite and elemental sulfur.     

Bioleaching of chalcopyrite with Acidianus manzaensis YN25 under contact and non-contact conditions

In order to investigate the contributions of contact and non-contact cells of Acidianus manzaensis(A.manzaensis) YN25 to the bioleaching of chalcopyrite,three experiments were carried out in the modified shake flasks.The redox potential,pH,cell density,copper and iron ions in the solution were monitored,and the morphological feature and chemical composition of the leached residues were analyzed.The highest leaching efficiency of Cu and Fe was reached in the experiment where the A.manzaensis YN25 could contact the surface of the chalcopyrite.There was no precipitation of jarosite in the leached residues of three experiments,but there was elemental sulfur in the leached residues when the cells could not contact the chalcopyrite.From these results,it is apparent that the leaching of the chalcopyrite is the cooperative action of the contact and non-contact A.manzaensis YN25.     

Dynamics in simultaneous electro-generative leaching for sphalerite-MnO2

The principle for the electro-generative leaching was applied to simultaneous leaching of sphalerite-MnO2. A galvanic system for the bio-electro-generative leaching was set up. The effects of grain size and temperature on rate of zinc extraction fi＇om sphalerite under the conditions of presence and absence ofAcidithiobacillusferrooxidans （A.ferrooxidans） were studied, respectively. The results show that with bacteria, the maximum extraction of zinc fi＇om the ores with grain size of 16.6 μm can reach 32.01% after leaching for 12 h, while to obtain the same extraction ratio in the traditional bio-leaching route （i.e. not electro-generative one）10 d is needed to ore granules with same size. The unreacted shrinking core model was used for describing the reaction-relative and diffusion-relative phenomena presented in the process of the electro-generative leaching with and without bacteria, which is considered to be diffusion controlled. The activation energies of the anodic reaction for leaching system in the presence and absence of bacteria are 11.97 and 14.39 kj/mol, respectively, indicating that leaching rate can be decreased by A. ferrooxidans. SEM was used to study the effect ofA. ferrooxidans on the ores in the simultaneous electro-generative leaching, which indicates that the produced sulfur on the surface of the sulfides can be oxidized by A. ferrooxidans after bio-electro-generative leaching for 24 h, and the transferred charge due to the bacterial oxidation is up to 17.86%, which is an important part of the output electric quantity.     

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.