黄铜矿半导体电学特性对其中等嗜热菌浸出行为的影响

为了研究黄铜矿半导体电学特性对其生物浸出的影响机制, 采用霍尔效应测试技术分析了3种不同来源黄铜矿的半导体电学特性, 并在45 ℃、170 r/min、2%矿浆浓度条件下进行了中等嗜热混合菌浸出试验。结果表明, 黄铜矿A的载流子浓度为-9.190×10¹⁸ cm^-3, 绝对值明显高于黄铜矿B和C的载流子浓度(-3.065×10¹⁸ cm^-3和-2.183×10¹⁷ cm^-3); 黄铜矿A的电阻率为0.054 65 Ω·cm, 明显低于黄铜矿B和C的电阻率(0.146 9 Ω·cm和0.930 6 Ω·cm); 黄铜矿的载流子浓度、电阻率与其铜浸出率存在明显联系, 黄铜矿的载流子浓度越高、电阻率越小, 铜的浸出速率就越高, 浸出19 d后, 3种黄铜矿纯矿物(A、B、C)的铜浸出率分别为66.1%, 25.3%和21.4%; 电化学试验结果表明, 3种黄铜矿的氧化还原反应过程基本相同, 但黄铜矿A的腐蚀电流密度明显高于另外两者。     

亚氯酸钠氧化浸出黄铜矿研究

为了实现黄铜矿的高效浸出，研究了酸性条件下亚氯酸钠氧化浸出黄铜矿的适宜工艺条件，并进行了浸出动力学研究和浸出机理分析。结果表明，在亚氯酸钠与黄铜矿的物质的量之比为6、浸出液的pH=4、浸出温度为55 ℃、浸出时间为0.25 h时的铜浸出率为82.36%；亚氯酸钠在酸性条件下高效氧化浸出黄铜矿与亚氯酸钠能分解出氧化活性高的物质ClO₂、ClO^-₃和Cl₂有关；亚氯酸钠氧化浸出黄铜矿的过程由界面化学反应控制，活化能为42.69 kJ/mol。     

中温嗜酸硫杆菌浸出低品位硫化铜矿

研究了中温嗜酸硫杆菌的生长条件, 对黄铜矿进行了细菌浸出试验研究。研究表明, 中温嗜酸硫杆菌最适宜的生长条件为: pH值为2, 温度为30±1 ℃, 此条件下细菌浓度为2.24×10⁷个/mL。接种量、矿浆浓度对黄铜矿中铜的浸出率有显著的影响, 随着接种量的增加, 铜的浸出率提高。在相同浸出时间内, 矿浆浓度5%左右时, 黄铜矿中铜的浸出率最高。低品位硫化铜矿柱浸试验结果表明: 细菌浸出75 d, 铜的浸出率为45%。     

黄铜矿的浸出及其动力学研究

为揭示黄铜矿的浸出规律,进行了黄铜矿矿物粒度、矿浆pH、矿浆浓度和NaCl浓度对铜浸出过程的影响,并对黄铜矿浸出动力学进行了研究。结果表明:1黄铜矿适宜的浸出粒度为38~75μm,矿浆pH=1,矿浆浓度为10 g/L,NaCl浓度为1 mol/L。2矿浆中NaCl的存在可以有效提高黄铜矿的浸出速度和浸出率,NaCl浓度不超过1mol/L的条件下,随着NaCl浓度的增大,这种促进效果越来越好。3在试验确定条件下,黄铜矿的浸出数据契合表面反应模型,即黄铜矿的浸出速率主要由矿物表面的反应速率决定。     

排土场黄铁矿促进黄铜矿浸出研究

为合理利用低品位铜矿石及其废石资源,进行了黄铜矿排土场中黄铁矿促进黄铜矿浸出的反应热力学分析及浸出试验。结果表明,黄铁矿反应所需的溶液电位范围涵盖了Fe²⁺促进黄铜矿浸出的电位范围,无氧条件下黄铁矿促进黄铜矿是可行的;黄铁矿的参与加速降低了Fe³⁺与Fe²⁺浓度之比,促使电位降低,进而促进黄铜矿的浸出;排土场中深部缺氧条件下黄铁矿促进黄铜矿浸出方式以上部浸出液为母液,上部溶液中Fe³⁺、Cu²⁺及Fe ²⁺是黄铁矿促进黄铜矿浸出的前提条件。     

银离子在细菌浸出黄铜矿中的催化行为研究

对银离子催化细菌浸出黄铜矿进行了研究。在银离子存在下, 矿粒越细, 浸出率就越高;浸出溶液pH 值在1.5～2 时浸出率较高;银离子浓度在10 mg/ L 时浸出效果最好。在实验范围内, 不论银离子初始值大小如何, 银离子在加入浸出体系后主要是以硫化银形式存在, 以离子形式存在于溶液中只占很小一部分。     

杂质离子对黄铜矿浸出的影响机理研究

为探究杂质矿物对黄铜矿浸出的影响,考察了不同种类离子对黄铜矿浸出的影响。研究发现:Al2(SO4)3对铜浸出起促进作用,而Na2SO4、K2SO4、MgSO4对铜浸出起抑制作用;相比于SO2-4,Cl-由于可在黄铜矿表面产生疏松多孔硫层,加快浸出剂的扩散,从而对铜浸出起促进作用。动力学分析表明,添加Na+、K+、Al3+时,黄铜矿浸出过程由界面化学反应控制;而Mg2+存在时黄铜矿浸出由扩散反应控制;添加Cl-时,黄铜矿浸出受界面化学反应控制;添加SO2-4时,黄铜矿浸出由扩散反应控制。试验结果可以为黄铜矿湿法冶金过程提高铜浸出率提供参考。     

用中等嗜热细菌常规和电化学生物浸出黄铜矿精矿

《Hydrometallurgy》2011年106卷第(1/2)期发表Ali Ahmadi等人文章,介绍用中等嗜热细菌常规和电化学生物浸出黄铜矿精矿的研究结果。在各种矿浆浓度以及在有和无细菌的情况下,进行了从Sarcheshmen黄铜矿精矿中提取铜的常规和电化学生物浸出试验。浸出条件:一台2 L搅拌式电生物反应器,矿浆含固量为0.2 kg/L,初始pH     

机械活化黄铜矿浸出动力学研究

研究了机械活化对黄铜矿浸出率的影响并进行了动力学分析。利用X射线衍射仪、激光粒度分析仪测试了机械活化对黄铜矿晶体结构、粒度的影响。结果表明:机械活化可细化黄铜矿颗粒粒径、破坏黄铜矿晶粒完整性、降低黄铜矿活化能、提高黄铜矿反应活性。黄铜矿机械活化1h后,浸出活化能从29.27kJ/mol降低至16.87 kJ/mol。当黄铜矿与氧化剂(NaClO_2)共磨相同时间后,活化能降至12.31kJ/mol,黄铜矿反应模型从化学反应转变为扩散反应。     

浸出黄铜矿的新工艺研究

研究了银离子催化、过硫酸铵浸出黄铜矿的新工艺及机理,并分析和讨论了浸出温度、浸出时间、过硫酸铵浓度、粒度、银离子浓度、pH等因素对浸出率的影响。试验结果表明,在过硫酸铵初始浓度0．50mol／L、黄铜矿粒度-74 58／μm、浸出温度368K、浸出时间100min、搅拌转速600dmin和矿浆密度25g/L的浸出条件下,铜的浸出率可达到98．00％以上。对浸出渣分别采用电子探针和XRD进行表征,发现加入的银离子以硫化银的形式均匀残留在渣中,且有大量元素硫产生并均匀地分布在浸出渣中;此外,原料中的黄铁矿仍残留在渣中,说明在浸出试验中没有随黄铜矿一起被浸出。机理分析表明,浸出过程中加入的微量Ag^ 与黄铜矿反应生成A＆S,并能均匀夹杂在产物硫层中,改善了元素硫层的导电性能,是加快了反应速度的主要原因。     

永平低品位黄铜矿矿石细菌浸出的银离子催化效应

为了提高用氧化亚铁硫杆菌和氧化硫硫杆菌混合菌对永平铜矿低品位黄铜矿矿石细菌浸出的效果,通过摇瓶实验,研究了银离子的催化效应。研究表明,在细菌浸出的初始阶段,添加银离子可以大大加快铜的浸出速度和提高铜的浸出率,其中添加初始银离子浓度10 mg/L时,最有利于铜的浸出,在600 h时内铜的浸出率可以从20%增加到65%,比不添加银离子时提高了45%。添加初始银离子使矿石中铁的浸出和溶液中二价铁的细菌氧化明显受到抑制。当有银离子时,低品位黄铜矿矿石在低氧化还原电位下比高氧化还原电位更有利于铜的浸出。     

黄铜矿细菌浸出机理及钝化原因研究进展

细菌冶金技术由于成本低、污染少、流程短等优点,越来越受到人们重视,由于在常温下黄铜矿的细菌浸出速率较慢,有必要研究提高黄铜矿浸出速率的方法。综述了黄铜矿的细菌浸出机理以及黄铜矿的钝化原因。研究结果表明黄钾铁矾、硫层、中间产物层、高的溶液还原电位和黄铜矿稳定的晶体结构可能是黄铜矿细菌浸出过程中的钝化原因。     

一株氧化亚铁硫杆菌的系统进化分析 及其浸矿效果研究

从低品位黄铜矿浸矿菌液中分离到14株嗜酸、亚铁离子氧化菌株, 并对菌株进行了Fe^2＋氧化率及其对低品位黄铜矿铜浸出率的测定。实验表明, YK12菌株的氧化活性最高, 对该菌株进行系统进化分析表明, 该菌株与分离自德国某废铀矿堆中的Acidithiobacillus ferrooxidans D2菌株(嗜酸氧化亚铁硫杆菌)相似性最高, 可鉴定为嗜酸氧化亚铁硫杆菌菌株(Acidithiobacillus ferrooxidans)。     

Cooperative bioleaching of chalcopyrite and silver-bearing tailing by mixed moderately thermophilic culture: An emphasis on the chalcopyrite dissolution with XPS and electrochemical analysis

In this work, the interactions between one sample of silver-bearing tailing (223 g/t silver) and chalcopyrite during bioleaching by mixed moderately thermophilic culture were investigated. Bioleaching results showed that copper can be almost totally extracted from chalcopyrite as the result of addition of the silver-bearing tailing, and silver (Ag) extraction can be significantly improved with the addition of chalcopyrite. Hence, cooperative bioleaching process of chalcopyrite and the chosen silver-bearing tailing was feasible. Ag mainly occurred as silver sulfate (Ag₂SO₄), and further work of enhancing the Ag extraction and its recovery is currently in progress. The catalytic effect of the silver-bearing tailing on chalcopyrite dissolution was investigated mainly with X-ray photoelectron spectroscopy (XPS) and electrochemical analysis. Results proved that the presence of the silver-bearing tailing enhanced the oxidation rate of chalcopyrite and also eliminated the passivation effect of polysulfide, thus resulting in an extremely high copper extraction.     

Extracellular polymeric substances (EPS) from bioleaching systems and its application in bioflotation

The use of EPS-producing heterotrophic and chemolithotrophic bacteria in bioflotation processes have been investigated for the last two decades. These studies have mostly been confined to laboratory microflotation tests using pure cultures. In this study the use of EPS, extracted from bioleaching consortia, to float chalcopyrite was evaluated and key process parameters such as pH, flotation time and the concentration of collector, bacterial cells and EPS were optimised. Analyses of the EPS extracted from various bioleach systems indicated that the EPS consisted mainly of carbohydrates, proteins and uronic acids. Microflotation tests using free EPS yielded a chalcopyrite recovery of 77% when chalcopyrite was floated alone and 70% during the separation of a mixture of pure chalcopyrite and pure pyrite compared to 32% when using SIBX only. The results obtained suggested that the flotation of chalcopyrite could be significantly increased in the presence of EPS extracted from bioleaching populations.     

Role and contribution of pure and mixed cultures of mesophiles in bioleaching of a pyritic chalcopyrite concentrate

This study compares the capacity of pure and mixed cultures of mesophilic bacteria for bioleaching of a low grade, pyritic chalcopyrite concentrate. In pure culture form, Acidithiobacillus ferrooxidans was found to have a higher bioleaching capacity than Leptospirillum ferrooxidans and Acidithiobacillus thiooxidans with the capability of the latter to bioleach copper being very limited. Mixed cultures, MixA (At. ferrooxidans, L. ferrooxidans and At. thiooxidans) and MixB (L. ferrooxidans and At. thiooxidans) were shown to perform better than the pure cultures with the highest extraction of copper (62.1% Cu) being achieved by MixA. Copper bioleaching performances of the cultures were observed to agree with their respective growth pattern. The results also indicated that the increase in the pulp density (1–5% wt/vol) adversely affected bioleaching process regardless of the pure and mixed cultures used having led to the decrease in the extent of final copper extraction i.e. 50.3% Cu recovery at 1% wt/vol for At. ferrooxidans compared with 38.6% Cu at 5% wt/vol. This study underlines the importance of mixed cultures and, iron and sulphur-oxidising activity of a bacterial culture to efficiently oxidise chalcopyrite.     

Cooperative effect of chalcopyrite and bornite interactions during bioleaching by mixed moderately thermophilic culture

The cooperative interactions between chalcopyrite and bornite during bioleaching by mixed moderately thermophilic culture were investigated mainly by bioleaching experiments and electrochemical experiments. Bioleaching results showed that a cooperative effect existed between chalcopyrite and bornite. When the mass ratio of chalcopyrite to bornite was 3:1, an extremely high copper extraction of more than 88% was achieved after bioleaching for 27 days. One of the major reasons for the cooperative effect was that a certain redox potential range (370–450 mV vs. Ag/AgCl) could be maintained for a long period of time during bioleaching due to the mixture of chalcopyrite and bornite. Electrochemical measurements revealed that chalcopyrite was much easier to be reduced than oxidized, while bornite was prone to be directly oxidized. Hence, galvanic effect between chalcopyrite and bornite enhanced the reduction of chalcopyrite to secondary copper-iron species and promoted the oxidative dissolution of bornite. Therefore, redox potential controlling and galvanic effect both contributed to the cooperative bioleaching of chalcopyrite and bornite.