微波对黄铜矿浸出的强化作用与机理研究

黄铜矿在湿法浸出过程中由于硫层等钝化层的生成,浸出效率低。为提高黄铜矿精矿的浸出效率,在分析了常规加热体系下的最适宜浸出条件基础上,引入微波加热强化黄铜矿的浸出,并进行了动力学研究和浸出渣形貌分析,揭示了微波的作用机理。研究结果表明:常规加热体系适宜条件下铜的浸出率仅为31.17%,在微波体系下可显著提高黄铜矿的浸出效率和理论最大浸出率,且提升幅度随微波功率的增加而增加。微波作用可剥离浸出过程中生成的硫层,减弱浸出过程的钝化作用,提高黄铜矿的浸出效果。     

黄铜矿和黄铁矿微生物浸出差异性研究

采用搅拌浸出法,搅拌转速350 r/min、搅拌温度45℃,使用相同菌种对黄铜矿与黄铁矿浸出差异性进行了研究。结果表明,在相同生物浸出条件下,黄铁矿较黄铜矿更易浸出。黄铜矿生物浸出后期,浸出速率减慢的决定因素并非黄钾铁矾钝化层的罩盖。两种矿物浸出差异性产生的根本原因在于由其自身晶体结构所决定的生物浸出机理不同。     

黄铜矿生物浸出过程中的钝化作用研究进展

要实现黄铜矿的高效浸出,在湿法冶金效率低、且存在环境污染问题的背景下就必须大力发展工艺简单、节能且绿色环保的生物浸出技术,而生物浸出过程中的钝化作用严重影响黄铜矿的浸出。为了控制和消除钝化膜对黄铜矿浸出的影响,在介绍了硫层、多硫化物层、黄钾铁矾层等钝化膜及影响其产生的p H值、铁离子浓度、铜矿物的晶体结构、温度、氧化还原电位等因素的基础上,有针对性地介绍了控制和消除钝化膜形成的手段,包括添加催化剂、表面活性剂、黄铁矿、不同菌种或是超声波等方法,并指出在保证细菌能够正常氧化浸出的前提下,可通过合理配置铁浓度和p H值、温度等外因来减小钝化膜的生成量,从而提高铜的浸出率,其中浸矿条件的调控和合适菌种的使用是解决黄铜矿钝化的有效方法。     

低温和高温下黄铜矿细菌浸出机理的新资料

《Hydrometallurgy》2003年第71卷第1～2期刊登了Rodriguez Y．等人的文章，介绍了有关低温和高温下黄铜矿细菌浸出机理的新资料。为了测定黄铜矿细菌浸出的直接和间接特性，对其浸出机理进行了研究。同时研究了减少这种硫化矿物溶解速率和抑制其被化学浸蚀的可能的原因。还进行了黄铜矿的电化学研究，包括消除或溶解在矿物表面可能形成的扩散膜。     

黄铜矿的细菌氧化

研究了氧化亚铁硫杆菌对黄铜矿的浸出行为。在酸性介质中，黄铜矿被氧化成CuSO4和Fe2（SO4）3。加入0．4％的FeSO4·7H2O，加快了黄铜矿的最初浸出速率，更高的Fe2 浓度反而抑制最初浸出速率。加入Fe2（SO4）3使浸出速率增加。加入Fe2 和Fe3 使最终浸出率达到78．7％，而仅用细菌浸出的最终浸出率只有69％。通过研究细胞质酶对S2-的氧化，发现细胞色素C参与了S2-的氧化，从而间接证明了细菌对黄铜矿的直接作用。     

中温及嗜热菌对不同成因黄铜矿浸出行为的影响

以斑岩型黄铜矿和矽卡岩型黄铜矿为研究对象,考察了嗜酸氧化亚铁微螺菌(L f)和嗜热硫氧化硫化杆菌(S t)对不同成因黄铜矿浸出行为的影响。结果表明,在2种不同细菌浸出体系中矽卡岩型黄铜矿均表现出比斑岩型黄铜矿浸出率高;S t浸出2种不同成因黄铜矿的效率均比L f的好。通过对不同浸矿时间黄铜矿浸出渣的XRD检测并结合黄铜矿浸出过程反应步骤的分析表明,2种细菌浸出不同成因黄铜矿的机制相同,细菌的代谢途径及反应温度是影响同类成因黄铜矿浸出率和代谢产物差异的主要原因。S t作用下浸出后期黄铜矿表面有黄钾铁矾生成,而L f浸出体系黄铜矿表面主要是S的不断积累。同种浸矿菌种浸出不同成因黄铜矿时,矽卡岩型黄铜矿在浸出第15 d有S生成,斑岩型黄铜矿在S t浸出体系S生成的时间更晚,在L f浸出体系S的生成量则更少,推测矿物性质是引起其差异的主要原因。     

添加纤维素对硫化铜矿细菌浸出过程的影响研究

将硫酸水解处理后的秸秆纤维添加到硫化铜矿细菌浸出过程中,考察其对浸出过程及浸出效率的影响。结果表明,采用50%硫酸处理后,纤维素水解产物为还原糖,有利于混合菌种的培养,提高细菌数量和活性;水解物可降低浸出液氧化还原电位,抑制矿物表面钝化层的产生;黄铜矿单矿物中Cu浸出率提高了36.35%;云南某低品位铜矿中的Cu浸出率提高了11.91%。     

氢氧化铁对黄铜矿生物浸出的钝化作用

《Minerals Engineering》2 0 0 0年 1 0～ 1 1期发表 Stott M.B.等人文章 ,介绍铁矾沉淀对黄铜矿生物浸出的钝化作用。黄铜矿 (Cu Fe S2 )是丰度最高 ,但又是最难处理的硫化铜矿物。当对其进行生物浸出时 ,初始溶解速率快 ,但约 5 0 h后铜的溶解速率明显降低。作者以一种中度嗜温的铁 -硫氧化菌 ,在酸性硫酸盐营养介质中研究了铁矾在生物浸出过程中的钝化作用。用 S.thermosulfidooxidans、S.acidopilus和 A.ferrooxidans3种中等嗜温菌研究了从黄铜矿表面对铁矾沉淀去除 (即还原 Fe( ) )的可能性 ,以考察铜浸出率可否恢复至原有水平。…     

中等嗜热菌浸出德兴黄铜矿的试验研究

对中等嗜热菌在45 ℃下浸出德兴黄铜矿的情况进行了试验研究。结果表明,添加适量（4 g/L）的Fe²⁺有利于中等嗜热菌的生长和黄铜矿的浸出;中等嗜热菌活性高有利于提高黄铜矿的浸出率;在试验酸度范围内,pH=1.50时中等嗜热菌的活性最高;矿浆浓度越低、粒度越细,越有利黄铜矿的浸出。在最佳试验条件下,黄铜矿49.2 d的铜浸出率为73.32%。浸出渣的XRD分析结果揭示,在浸出一段时间后,黄铜矿慢慢发生钝化的原因在于硫单质和黄钾铁矾在其表面的附着。     

白银含铜废石常温生物可浸性试验

从白银铜矿矿坑水中筛选分离的BY 1#细菌对黄铁矿有较好的氧化效果,也具有较好的抗剪切性和金属离子抗性。生物浸出综合试验表明该细菌在对黄铜矿的生物氧化溶解过程中,矿物表面可能存在某种钝化膜层,导致铜浸出率偏低,延长浸出时间所获得的效果也较差。在接种浓度10%、矿浆浓度5%、矿样粒度D70=400、摇床转速175rpm的试验条件下,浸出60d可获得的铁浸出率为57.24%,铜浸出率为42.16%。     

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。     

Pretreatment of chalcopyrite ore with alkali: A simple technique to improve the leaching mediated by thiobacillus ferrooxidans

A simple method to promote the extraction of copper and iron from chalcopyrite ore using the bacterium is reported. The method involves prior treatment of the ore with alkali. The alkali treatment also altered the rate of iron precipitation during the leaching process. An alteration of the microenvironment caused by removal of any inhibitory gangue material is suspected to be the reason for the observed improvement in the leaching rate. The alkali wash method may be a more efficient substitute for “ore regrinding”, the technique suggested by Torma [1] for removal of the inhibitory effect of a passivation layer that prevents further microbial attack onto the ore surface.     

Enhanced leaching of copper from chalcopyrite in hydrogen peroxide–glycol system

The dissolution of copper from chalcopyrite was investigated in the presence of hydrogen peroxide and ethylene glycol. Hydrogen peroxide was used as oxidant in the leaching process. Addition of a small amount of ethylene glycol significantly improved the copper dissolution. The copper leaching mechanism was established by examining the influence of various parameters on the reaction rate in the presence of ethylene glycol. The effect of temperature on the reaction kinetics suggests that the leaching reaction follows the surface reaction-controlled model. The linear relationship between the log of reaction rate constant and log of particle radius supports the proposed reaction model. The reaction order was calculated with respect to hydrogen peroxide which indicates that hydrogen peroxide has greater influence on the leaching kinetics. Stirring speed and sulfuric acid concentration are not important variables. Most of the sulfide ions were transformed to elemental sulfur during the reaction. The elemental sulfur was present on the surface of chalcopyrite residue as discrete crystalline particles instead of a coating of continuous film which causes the passivation of chalcopyrite surface. Ethylene glycol was found to stabilize the hydrogen peroxide at elevated temperature which could be another reason for enhanced recovery.     

Passivation of chalcopyrite during its chemical leaching with ferric ion at 68 °C

The passivation of chalcopyrite in the presence of ferric sulphate solutions was investigated at 68 °C. The effect of different variables (pulp density, pH and the presence of oxygen) on both the copper dissolution rate and the formation of solid compounds was studied. The leaching tests were carried out in stirred flasks at 180 rpm with 100 mL of a Fe³⁺/Fe²⁺ sulphate solution, varying the pulp density between 0.1 and 5% and the pH between 0.5 and 2.0 and both in aerobic and anaerobic conditions. Ferric ion seems to be responsible for the oxidation of chalcopyrite but also promotes its passivation. Ferrous ion plays a key role in the process by controlling the nucleation and precipitation of jarosites, which finally cause the passivation of chalcopyrite.     

Acidic sulphate leaching of chalcopyrite concentrates in presence of pyrite

Copper concentrates with mineralogy dominated by chalcopyrite have slow leaching kinetics at atmospheric pressure in sulphate media because of the formation of passivation layer on its surface during the leaching. To enhance the leaching rate of the copper concentrate, pyrite was added to act as a catalyst. Pyrite and copper sulphide minerals then form a galvanic cell which increases both the copper leaching rate and yield. Effect of parameters such as solution redox potential, temperature, initial acid concentration, solids content, total initial iron concentration and pyrite to copper sulphide minerals mass ratio were investigated. Mineralogical analyses by XRD were performed on selected leach residues and the feed materials. A copper recovery higher than 80% in 24 h was achieved at a redox potential of 410 mV vs Ag, AgCl, a temperature of 85 °C, 15 g/L of initial acid concentration, a solid content of 7.8% (w/v), a total initial iron concentration 5 g/L and pyrite to copper sulphide minerals mass ratio 2:1. XRD patterns on leach residues showed that candidates for surface passivation, i.e. jarosite and elemental sulphur, were formed at high total initial iron concentrations.     

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。     

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。     

低电位生物浸出黄铜矿研究

在酸性溶液中,高浓度Fe²⁺离子的存在有助于溶解氧对黄铜矿的氧化浸出。试验驯化培养具有单一硫氧化性的高效浸矿细菌,运用其对单体硫的高效氧化性能,结合Fe²⁺离子对黄铜矿氧化浸出的促进作用,开展黄铜矿低电位生物浸出研究。研究发现硫氧化菌可有效利用黄铜矿氧化溶解的产物--单体硫,将其氧化为硫酸并补充溶液H⁺离子消耗。同时,清除黄铜矿表面氧化溶解产物--单体硫后,有助于离子扩散和黄铜矿的进一步氧化溶解。