不同成因类型黄铜矿细菌浸出钝化

利用嗜酸氧化亚铁硫杆菌为浸矿菌种,采用SEM,XRD和XPS等手段研究2种不同成因类型黄铜矿(黄铁矿型和斑岩型)表面钝化机理.研究结果表明:2种类型黄铜矿表面形成的钝化层性质不同.黄铁矿型黄铜矿浸渣中产生S8和硫砷铜矿,其表面结构疏松;而斑岩型黄铜矿浸渣中出现Cu18.32Fe15.9S32和Cu2S,表面结构致密.黄铁矿型黄铜矿浸渣表面阻碍层为硫及其多聚物,斑岩型黄铜矿浸渣表面为富铜贫铁层.它们阻碍黄铜矿的继续浸出,且富铜贫铁层对黄铜矿的钝化能力强于硫层对黄铜矿的钝化能力.     

黄铁矿促进黄铜矿微生物浸出影响因素

采用摇瓶实验,以氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,At.f)浸出黄铁矿--黄铜矿,重点研究了基础培养基、矿物配比和粒度组成等因素的影响.黄铁矿能促进黄铜矿的微生物浸出,以采用无Fe 9K培养基效果较好,它对应铜浸出率是9K培养基的1.68倍;采用宽粒级矿物时铜浸出效果较好,且铜浸出率与黄铁矿和黄铜矿的质量比有关,当质量比为2∶2时铜浸出率最高可达45.58%;黄铁矿含量大小是影响铜浸出率高低的实质,当质量比小于等于5∶2时以At.f菌的氧化作用为主,当质量比为10∶2时以硫化矿间的原电池效应为主.浸渣的X射线衍射分析表明,采用无Fe 9K培养基时浸渣中生成的钝化物黄钾铁矾较少,故黄铁矿可以很好地替代9K培养基中的FeSO4,并能与黄铜矿形成原电池效应,从而促进铜的浸出.     

Acidithiobacillus ferrooxidans对黄铜矿和镍黄铁矿的浸出

以黄铜矿和镍黄铁矿为研究对象,初步探讨了Acidithiobacillus ferrooxidans对黄铜矿和镍黄铁矿的浸出.结果表明:有细菌参与下,黄铜矿的浸出率是无菌体系浸出率的2.41倍;镍黄铁矿的浸出率是无菌体系浸出率的1.91倍,细菌在矿物的浸出过程中起到了很好的促进作用.浸出过程中会有黄色的黄钾铁矾(K[Fe3(SO4)2(OH)6])沉淀产生,黄钾铁矾附着在矿体表面,产生"钝化现象",严重阻碍矿物的氧化.     

石英对微生物浸出黄铜矿的作用

为探明石英在微生物浸出铜过程中的作用与影响,选择粒度<43μm的石英,与黄铜矿和黄铁矿形成矿浆浸出体系,考察了石英质量浓度对黄铜矿浸出效果的影响.结果表明:适量的石英,其粒度越细越能促进黄铜矿的浸出.当石英质量浓度为50g·L-1、粒度<43μm时,黄铜矿的浸出率最高可达54·09%,比不添加石英的浸出率提高了近20%;通过对微生物浸出过程的氧化还原电位、pH值、Fe2+、Fe3+变化分析,以及浸渣的扫描电镜和能谱分析发现,石英促进黄铜矿浸出主要表现在能缩短微生物浸出的延迟时间,它对浸出过程新生成的沉淀具有吸附作用,能在一定程度上减轻沉淀对黄铜矿浸出的阻碍.     

细菌-矿物接触/非接触模式下黄铜矿浸出溶解行为

研究细菌-矿物接触模式及利用透析袋将细菌和矿物隔离的非接触模式下嗜酸氧化亚铁硫杆菌对黄铜矿浸出溶解的影响,并对黄铜矿浸出过程表面钝化的原因进行分析。研究结果表明:在细菌-矿物接触模式下,黄铜矿的浸出行为包括细菌对黄铜矿表面硫的催化氧化及细菌氧化Fe2+生成的Fe3+对黄铜矿在于氧化溶解;在细菌-矿物非接触模式下,黄铜矿主要通过细菌氧化Fe2+生成的Fe3+氧化浸出;浸出体系电位是影响黄铜矿浸出速率的主要因素,且较高的电位更有利于黄铜矿的浸出。比较细菌-矿物接触模式和细菌-矿物非接触模式,细菌-矿物接触模式比非接触模式更有利于提高浸出体系电位及氧化消除黄铜矿表面生成的硫膜,因而促进了黄铜矿的浸出;易于在较高电位下生成的黄钾铁矾沉淀是导致这2种模式下黄铜矿表面钝化的主要原因。     

Triton X-100对氧化亚铁硫杆菌氧化活性及浸出黄铜矿的影响

为提高黄铜矿的微生物浸出效果,研究了非离子表面活性剂Triton X-100对氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)氧化Fe2+和S0的活性以及浸出黄铜矿的影响,并采用XRD对浸出后的产物进行了表征.结果表明,Triton X-100对氧化亚铁硫杆菌氧化Fe2+有一定的抑制作用,而对氧化S0则显现出促进作用;Triton X-100可显著改善黄铜矿的微生物浸出效果,当其质量浓度为30 mg·L-1时,黄铜矿中铜的浸出率提高了52.15%.Triton X-100的加入提高了氧化亚铁硫杆菌对黄铜矿浸出过程中间产物硫的生物利用性和消解作用,从而提高了浸出体系中细菌浓度和Fe3+浓度,进而促进了黄铜矿的溶解.     

生物浸出中黄铜矿与铁离子间的相互影响

使用中等嗜热兼性自养细菌在不同反应体系下进行黄铜矿浸出的研究,通过监测反应过程中p H、氧化还原电位和铁、铜离子质量浓度的变化,以及对矿渣进行扫描电镜观察及微区分析(SEM-EDS)和X线衍射(XRD)分析,进而分析黄铜矿与铁离子间的相互关系。研究结果表明:在细菌存在的条件下,向Fe2+与Fe3+质量浓度相同(ρ(Fe2+):ρ(Fe3+)=1:1)的溶液中加入黄铜矿后,Fe2+的氧化速率迅速升高,氧化还原电位快速升高,在较短时间内,Fe2+基本被氧化完毕,并且黄铜矿促进Fe3+水解生成沉淀;铁离子对黄铜矿的生物浸出具有重要影响,较高质量浓度的且具有一定Fe3+与Fe2+质量浓度比的溶液,在前期可以提高黄铜矿的浸出速率,但在中后期会加剧黄铜矿的钝化反应,最终降低铜的浸出率;在黄铜矿的微生物浸出中,有铁矾类物质生成,铁矾的形成与铁离子质量浓度有关,高质量浓度的铁离子加速铁矾的生成。     

低品位镍磁黄铁矿镍浸出特性及回收方法

对我国某高硅低品位镍磁黄铁矿进行直接酸浸、焙烧--酸浸和细菌浸出比较,并考察硫酸用量及氧化亚铁硫杆菌对浸出率的影响.以稻壳为硫酸盐还原菌固定化载体构建连续上升流固定填充床反应器,以连续上升流方式处理浸出液.结果表明:焙烧使矿物发生烧结,镍被包裹,不利于浸出;细菌浸出Ni2+浸出率为92.16%,质量浓度可达973.22 mg·L-1·T·f.菌在矿物表面形成生物膜,直接与矿物发生作用使矿物溶解,将浸液中Fe2+氧化为Fe3+,Fe3+进一步溶解矿物·浸出液以2200~3600 mL·L-1·d-1的速率经过反应器,Ni2+以NiS的形式吸附于稻壳上,回收率在98%以上,使原矿中NiO质量分数由1.69%上升至稻壳中的11.84%.浸液中98%的Mg2+留在溶液中,利于金属分离.     

紫金山铜矿浸出过程黄铁矿的氧化行为

针对紫金山铜矿堆浸过程中,在辉铜矿和铜蓝等有用矿物浸出的同时,有黄铁矿被大量浸出,造成浸出液中Fe3 浓度过高的现状,研究了细菌浸出黄铁矿的氧化行为和机理,重点考察了Fe3 的化学氧化以及细菌浸出黄铁矿过程的影响因素.研究结果表明,在有菌条件下,pH值为1.6时,混合矿浸出初期,黄铁矿的浸出率仅为5%～8%;随着浸出时间的增加,氧化还原电位升高,浸出15d后,氧化还原电位上升到500mV以上时,黄铁矿的浸出率可达25%.说明氧化还原电位是细菌浸出黄铁矿过程的重要影响因素.机理研究表明,细菌浸出黄铁矿是以间接反应为主,细菌在黄铁矿表面的吸附对黄铁矿的浸出具有协同作用.     

难处理金矿中伴生矿物对氰化浸出的影响

对金矿石中常见的几种伴生矿物在氰化浸出中的影响进行了分析,同时采用化学试剂配制标准液的方式,考察了Fe2+,Cu2+,As3+对氰化物消耗的影响.试验结果表明:铁矿物中,磁黄铁矿对氰化浸出的影响较大,使溶金速率下降28.1%,氰化物耗量增加4倍,而黄铁矿与赤铁矿对氰化浸出的影响较小;铜矿物中,黄铜矿与辉铜矿对氰化浸出都具有很大影响,其中辉铜矿可使溶金速率下降36.81%,氰化物耗量增加10倍;砷矿物中,雄黄与雌黄对氰化浸出极其有害,使溶金速率分别下降41.95%和49.90%,氰化物耗量分别增加13.8倍和15.0倍,相反毒砂在氰化体系中比较稳定,对氰化浸出的影响较小.离子耗氰试验中,Fe2+...     

Bioleaching of two different types of chalcopyrite by Acidithiobacillus ferrooxidans

Two different types of chalcopyrite (pyritic chalcopyrite and porphyry chalcopyrite) were bioleached with Acidithiobacillus ferrooxidans ATF6. The bioleaching of the pyritic chalcopyrite and porphyry chalcopyrite is quite different. The copper extraction reaches 46.96% for the pyritic chalcopyrite after 48-d leaching, but it is only 14.50% for the porphyry chalcopyrite. Proper amounts of initial ferrous ions can improve the efficiency of copper extraction for the two different types of chalcopyrite. The optimum dosage of ferrous ions for the pyritic chalcopyrite and porphyry chalcopyrite is different. The adsorption of ATF6 on the pyritic chalcopyrite and porphyry chalcopyrite was also studied in this paper. It is found that ATF6 is selectively adsorbed by the two different types of chalcopyrite; the higher adsorption onto the pyritic chalcopyrite than the porphyry chalcopyrite leads to the higher copper dissolution rate of the pyritic chalcopyrite. In addition, the zeta-potential of chalcopyrite before and after bioleaching further confirms that ATF6 is more easily adsorbed onto the pyritic chalcopyrite.     

低品位黄铜矿的磁场强化细菌浸出

针对低品位黄铜矿进行了磁场强化细菌浸出实验研究。重点研究了磁场对细菌生长和细菌浸矿的影响。实验结果表明,磁化处理后的培养基能促进细菌的生长繁殖,提高其氧化活性,用于浸矿试验,提高了低品位黄铜矿中铜和铁的浸出率。磁场强化细菌浸出的可能机理是通过改变水的结构,促进氧气在水中的溶解,提高矿石成分的溶解性,增强细菌细胞生物膜的穿透性。     

Mechanochemical leaching of chalcopyrite concentrate by sulfuric acid

This study aimed to introduce a new cost-effective methodology for increasing the leaching efficiency of chalcopyrite concentrates at ambient temperature and pressure. Mechanical activation was employed during the leaching (mechanochemical leaching) of chalcopyrite concentrates in a sulfuric acid medium at room temperature and atmospheric pressure. High energy ball milling process was used during the leaching to provide the mechanochemical leaching condition, and atomic absorption spectroscopy and cyclic voltammetry were used to determine the leaching behavior of chalcopyrite. Moreover, X-ray diffraction and scanning electron microscopy were used to characterize the chalcopyrite powder before and after leaching. The results demonstrated that mechanochemical leaching was effective; the extraction of copper increased significantly and continuously. Although the leaching efficiency of chalcopyrite was very low at ambient temperature, the percentages of copper dissolved in the presence of hydrogen peroxide (H₂O₂) and ferric sulfate (Fe₂(SO₄)₃) after 20 h of mechanochemical leaching reached 28% and 33%, respectively. Given the efficiency of the developed method and the facts that it does not require the use of an autoclave and can be conducted at room temperature and atmospheric pressure, it represents an economical and easy-to-use method for the leaching industry.     

华南某花岗岩型铀矿床矿石地质特征对铀浸出动力学的影响

华南花岗岩型铀矿床是我国重要的铀资源之一,主要采用堆浸法提取铀.本文实验研究了铀矿石的地质地球化学特征对铀浸出的影响.根据地质地球化学特征,铀矿石可以分为2个类型,Ⅰ类是发育赤铁矿化,呈暗红色,Fe2O3含量较高,Ca、Ma、Al含量较低;Ⅱ类是发育绢云母化和碳酸盐化,呈灰绿色,Fe2O3含量较低,Ca、Ma、Al含量较高.铀浸出动力学受表面化学反应控制,矿石的地质地球化学特征对铀的浸出有显著影响,Ⅰ类矿石铀的浸出率、铀浓度和浸出速率常数显著高于Ⅱ类矿石.矿石中的赤铁矿为铀浸出提供氧化剂Fe3＋,从而促进铀的浸出;碳酸盐矿物一方面消耗酸,另一方面形成沉淀物,从而对铀浸出产生不利影响.     

柠檬酸强化黄铜尾矿的生物浸矿

通过摇瓶试验研究混合硫杆菌浸出黄铜矿尾矿砂,并初步探讨不同矿浆质量浓度和柠檬酸质量浓度对浸提实验的影响。研究结果表明,添加柠檬酸在一定质量浓度范围内对黄铜矿尾矿砂的硫杆菌浸提有促进作用。在整个浸提实验中,浸矿效率最高达到44.8%,溶液中柠檬酸质量浓度和矿浆质量浓度都会直接影响细菌的氧化活性和浸矿效果。     

Kinetics of chemical leaching of chalcopyrite from low grade copper ore: behavior of different size fractions

The kinetics of the chemical leaching of copper from low grade ore in ferric sulfate media was investigated using the constrained least square optimization technique. The experiments were carried out for different particle sizes in both the reactor and column at constant oxidation-reduction potential (E_h), pH values, and temperature. The main copper mineral was chalcopyrite. About 40% of Cu recovery is obtained after 7 d of reactor leaching at 85℃ using -0.5 mm size fraction, while the same recovery is obtained at 75℃ after 24 d. Also, about 23% of Cu recovery is obtained after 60 d of column leaching for +4–-8 mm size fraction whereas the Cu recovery is as low as about 15% for +8–-12.7 and +12.7–-25 mm size fractions. A 4-stage model for chalcopyrite dissolution was used to explain the observed dissolution behaviors. The results show that thick over-layers of sulphur components cause the parabolic behavior of chalcopyrite dissolution and the precipitation of Fe3+ plays the main role in chalcopyrite passivation. In the case of coarse particles, transformation from one stage to another takes a longer time, thus only two stages including the initial reaction on fresh surfaces and S0 deposition are observed.     

Comparative study on the passivation layers of copper sulphide minerals during bioleaching

The bioleaching of copper sulphide minerals was investigated by using A. ferrooxidans ATF6. The result shows the preferential order of the minerals bioleaching as djurleite>bornite>pyritic chalcopyrite>covellite>porphyry chalcopyrite. The residues were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is indicated that jarosite may not be responsible for hindered dissolution. The elemental sulfur layer on the surface of pyritic chalcopyrite residues is cracked. The compact surface layer of porphyry chalcopyrite may strongly hinder copper extraction. X-ray photoelectron spectroscopy (XPS) further confirms that the passivation layers of covellite, pyritic chalcopyrite, and porphyry chalcopyrite are copper-depleted sulphide Cu₄S₁₁, S8, and copper-rich iron-deficient polysulphide Cu₄Fe₂S₉, respectively. The ability of these passivation layers was found as Cu₄Fe₂S₉>Cu₄S₁₁>S₈>jarosite.