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。     

泥型废弃铜矿的细菌浸出试验研究

研究了细菌对Cu²⁺、Fe²⁺离子的耐受性能及其氧化活性, 对泥型废弃矿进行了细菌浸出研究。结果表明, 细菌对Cu²⁺、Fe²⁺有较强的耐受性能, 但要保持其高效的氧化活性, 其浓度应分别控制在2 g/L和4 g/L以内。泥型废弃矿经脱泥处理后, 采用柱浸和堆浸法, 50 d后铜的浸出率高达62.2%和65.5%。     

不同磨矿体系下新生阳离子存在行为及其对黄铜矿可浮性的影响

磨矿过程会使矿浆溶液中离子的种类及含量发生较大变化,进而对矿物浮选溶液化学性质及其可浮性 产生难免影响。 通过磨矿试验、原生离子和新生阳离子含量检测试验、单矿物浮选试验和浮选溶液化学计算,考察了 不同磨矿体系下新生阳离子的存在行为及其对黄铜矿可浮性的影响。 结果表明:黄铜矿不同磨矿体系下矿浆溶液中 存在的新生阳离子为 Cu²⁺、Fe²⁺和 Fe³⁺,且干式磨矿体系下产生的新生阳离子含量高于湿式磨矿体系;适量的 Fe²⁺和 Cu²⁺在黄铜矿表面能够形成新的活性位点,可增强黄铜矿表面与丁胺黑药的键合作用,从而提高黄铜矿的可浮性;适 量的 Fe³⁺在 pH 值为 5~ 7 时对黄铜矿有轻微活化作用,但过量的 Fe³⁺会增大 Fe( OH) ₃(aq) 和 Fe( OH) ₄ ^-组分在溶液中 的含量,使得矿物表面亲水性增强,从而对黄铜矿产生抑制作用。 研究结果可为黄铜矿不同磨矿体系的选择及其对 浮选环境的调控提供一定的借鉴。     

氯化咪唑铁基离子液体的物化性能及脱硫机理

采用变温拉曼光谱、红外光谱探针及XRD等现代分析技术研究疏水性氯化咪唑铁基离子液体的酸性特征及循环热稳定性,结果表明,氯化咪唑铁基离子液体可以在不超过240 ℃的条件下循环使用;具有Bronsted酸和Lewis酸的共同特点;Fe³⁺/Fe²⁺离子对具有很好的氧化还原可逆性,可以在酸性条件下直接氧化硫化氢脱硫,所得硫磺产物属于单斜晶系;升高温度可以显著提高其硫容和脱硫效率。由此,以氯化咪唑铁基离子液体为酸性脱硫液的非水相湿法氧化脱硫机理是活性成分Fe³⁺氧化硫化氢生成单质硫磺并转化成还原态Fe²⁺,经氧气氧化再生后Fe²⁺回到氧化态Fe³⁺。上述脱硫过程不需添加辅助试剂和调控pH。     

黄铜矿在硫酸介质中浸出的电化学行为

以天然黄铜矿为研究对象,运用三电极电化学体系,对在硫酸介质中黄铜矿的浸出过程电化学行为进行了研究。结果表明,黄铜矿首先氧化成缺铁硫化物,覆盖于电极表面,使电极表面发生钝化。随着电位的升高,缺铁硫化物继续氧化,最终以硫酸根形式于溶液中。当电位小于-0.85 V(vs. SCE)时,黄铜矿阴极还原反应电流大,晶格中的Fe³⁺完全溶解出来。黄铜矿的阴极反应较强烈,且对黄铜矿氧化浸出具有重要意义。此外,随pH值降低,H₂S加速生成,氧化还原峰电流增强。说明在研究的pH值内,降低体系的pH值有利于黄铜矿的氧化。     

较低温度下细菌浸出黄铜矿工艺影响因素研究

以黄铜矿为研究对象,在温度较低的浸出条件下（15℃）采用正交试验的方法考察了矿石粒度、矿浆浓度、酸度、接种量以及起始Fe²⁺浓度对氧化亚铁硫杆菌（T.f菌）摇瓶浸出黄铜矿浸出过程的影响。试验结果表明：初始Fe²⁺浓度对细菌浸铜工艺影响最为显著;在15℃下的最佳浸出工艺条件为初始Fe²⁺浓度为6g/L,酸度控制在pH=2.0,接种量保持在15%,矿浆浓度为15%,矿石粒度为-200目。     

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。     

pH值与温度对氧化亚铁硫杆菌氧化Fe2+影响的研究

采用自行采集的氧化亚铁硫杆菌(T f)应用于地浸矿山代替双氧水作氧化剂氧化吸附尾液中的Fe²⁺, 研究了温度、pH 值对其氧化Fe²⁺的影响。研究结果表明, T f 氧化Fe²⁺最适宜的温度为30 ℃, 当温度低于7 ℃或高于50 ℃时, 氧化亚铁硫杆菌氧化Fe²⁺速度很慢;T f 氧化Fe²⁺最适宜的pH 为2.0～2.5 。     

酸性H2O2氧化预处理浮选金精矿及其机理研究

酸性 H₂O₂ 氧化法是一种有效的难选金精矿预处理方法,可以使黄铁 矿、毒砂等载金矿物被有效溶解, 从而使金暴露出来,提高金浸出率。 研究了酸性 H₂O₂ 体系中黄铁矿的氧 化机制,并探究了该系体中温度、矿浆浓度、 H₂SO₄ 和 H₂O₂浓度等对浮选金精矿的预处理效果。 结果表明:H₂O₂ 氧化 过程中没有固相生成物,黄铁矿中的 Fe 转 化为 Fe²⁺和 Fe³⁺ 于溶液中,Fe²⁺ 与 H₂O₂ 可发生 Fenton 反应生成氧 化性极强的羟基自由基(·OH);氧化过程中有 H₂SO₄ 生成,体系的 pH 值随着反应进行逐渐降低;黄铁矿主要被酸性 H₂O₂ 、·OH 和 Fe³⁺氧化,体系中 S 最终转化为 SO₄ ^2-或 HSO₄^- 。 浮选金精矿在温度为 30 ℃ 、矿浆浓度为 100 g/L、 H₂SO₄ 初始浓度为 0. 18 mol/L 和 H₂O₂ 初始浓度为 1. 76 mol/L 的条件下氧化预处理后,Fe 浸出率、试样失重率分别为 95. 33%和 51. 42%;浮选金精矿直接浸出时金浸出 率仅为 11. 68%,而经过酸性 H₂O₂预处理—浸出后,金浸出率可达 92. 69%。     

黄铁矿生物氧化过程的阶段性

以氧化亚铁硫杆菌为实验菌株，研究了黄铁矿的Fe³⁺氧化和生物氧化过程中溶液铁离子浓度、pH值以及Eh值的变化。结果表明，Fe³⁺由于自身很快会被消耗，因而对黄铁矿的氧化速率较低；而在细菌的作用下，Fe²⁺可以不断被氧化成Fe³⁺，从而使黄铁矿的氧化速率明显加快，因此生物氧化具有更高的效率。基于间接作用机制，结合黄铁矿生物氧化过程中pH值及Eh值的变化规律，提出了黄铁矿生物氧化的阶段性特点，即将氧化亚铁硫杆菌对黄铁矿的氧化过程分为黄铁矿无机氧化、Fe²⁺生物氧化和黄铁矿稳定生物氧化3个阶段。     

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.     

Mathematical modeling of thermophilic bioleaching of chalcopyrite

Previous studies have shown that the different preferences of thermophiles to oxidize S⁰ or Fe²⁺ is reflected by different [Fe³⁺]/[Fe²⁺] levels in solution. In those studies it was concluded that [Fe³⁺]/[Fe²⁺] governs the thermophilic bioleaching of chalcopyrite rather than temperature or pH. Therefore, the proposed model is mainly based on the finding that thermophilic bioleaching of chalcopyrite is governed by [Fe³⁺]/[Fe²⁺] that result from the activity of thermophiles. A direct interaction between chalcopyrite and thermophiles is neglected because it has been reported that this is not a general behavior for all thermophiles. The case of constant temperature, initial pH 1.5–2.5, and chalcopyrite concentrates is considered. The main assumption is that chalcopyrite can be anodically oxidized or cathodically reduced depending on [Fe³⁺]/[Fe²⁺] in solution. When chalcopyrite is oxidized at high [Fe³⁺]/[Fe²⁺] levels, Cu²⁺ is formed directly at low rates: CuFeS₂ + 4Fe³⁺ → Cu²⁺ + 5Fe²⁺ + S⁰. Whereas, when chalcopyrite is reduced at low [Fe³⁺]/[Fe²⁺] levels, an intermediate (Cu₂S) is formed at higher rates: CuFeS₂ + Fe²⁺ + Cu²⁺ + 2H⁺ → Cu₂S + 2Fe³⁺ + H₂S. Because the oxidation of Cu₂S is relatively fast: Cu₂S + 4Fe³⁺ → 2Cu²⁺ + S⁰ + 4Fe²⁺, its accumulation is assumed to be negligible. To take into account the possibility of chalcopyrite being oxidized or reduced depending on [Fe³⁺]/[Fe²⁺] in solution, the principle of mixed potentials is used. The model is validated by comparing the calculated and measured values of copper extraction, total iron in solution, and pH.     

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。     

Enrichment and characterisation of thermophilic acidophiles for the bioleaching of mineral sulphides

Thermophilic acidophilic Archaea were enriched from samples collected from geothermally active sites in Papua New Guinea. Pure cultures (JP2 and JP3) were obtained from mixed culture enrichments and were characterised and tested for their bioleaching ability. All cultures possessed Sulfolobus-like morphology, and the presence of distinctive cyclized tetraether lipids. The two pure cultures were identified by their 16S rRNA gene sequences as being most closely related to Sulfolobus solfataricus. Each isolate was able to oxidise both Fe²⁺ and sulphur, and grow on both pyrite and chalcopyrite under autotrophic conditions. Leaching experiments showed that the isolates were capable of rapidly leaching a chalcopyrite concentrate (up to 91% Cu release in 108 h). Optimal temperatures for growth and chalcopyrite leaching were determined for each strain. Chalcopyrite dissolution rates for JP2 at different temperatures were determined using a previously described kinetic model. An Arrhenius plot to investigate the relationship between dissolution rate and temperature, showed that for JP2, an increase in temperature from 70 to 83 °C resulted in a 6.6-fold rate increase. Studies with both mixed and pure cultures showed that these cultures were capable of rapidly leaching a chalcopyrite concentrate at very high temperatures (up to 90 °C), but also were capable of bioleaching at 50 °C. These thermophilic acidophiles possess the ability to bioleach over a wide range of temperatures. They are potentially well suited to industrial leaching applications where considerable temperature fluctuations limit the growth of other non-thermophilic bioleaching microorganisms.     

The influence of cathodic reduction,Fe2+ and Cu2+ ions on the electrochemical dissolution of chalcopyrite in acidic solution

The electrochemical behaviour of chalcopyrite has been studied in sulphuric acid solutions with the carbon paste electrode technique. Cyclic voltammetry were performed and the effect of cathodic scan limit, Fe²⁺ and Cu²⁺ ion concentrations were followed. The presence of Cu²⁺ ions in solutions leads to an increase in both the oxidation and the reduction currents, but in either case further increases in currents were observed when Fe²⁺ ion was added in admixture to the electrolyte. Chalcocite was identified as a product of reactions at extremely high cathodic potentials. The morphology and structure of the produced products after anodic or cathodic treatments of chalcopyrite were examined by the scanning electron microscopy.     

Comparison of the electrochemical mechanism of chalcopyrite dissolution in the absence or presence of Sulfolobus metallicus at 70 °C

The electrochemical mechanisms of chalcopyrite dissolution in the absence and presence of Sulfolobus metallicus at 70 °C were studied using cyclic voltammetry and Tafel methods. The cyclic voltammetry experiments show that S. metallicus does not change the oxidative and reductive mechanisms of chalcopyrite dissolution. The initial oxidation potentials of chalcopyrite dissolution are equal in the absence and presence of S. metallicus. However, the current density of oxidation in the presence of S. metallicus increases significantly. At about 0 V, the products on the surface of chalcopyrite are CuS, elemental S⁰, and Fe²⁺. At about 0.384 V, CuS may be oxidized, and chalcopyrite may be transferred to CuO, Fe₂O₃, and elemental S⁰. The Tafel experiments show that S. metallicus may increase the corrosion potential and corrosion current density of chalcopyrite. S. metallicus may also reduce the polarization resistance of chalcopyrite in bioleaching. These results indicate that S. metallicus may accelerate the oxidation of chalcopyrite.     

Dissolution and passivation mechanisms of chalcopyrite during bioleaching: DFT calculation,XPS and electrochemistry analysis

In this work, density functional theory (DFT) calculation, X-ray photoelectron spectroscopy (XPS) and electrochemistry analysis were carried out to investigate the dissolution process and passivation mechanisms of chalcopyrite in the presence of sulfur and iron oxidizing microorganisms. Both DFT calculation and XPS analysis indicated that the formula of chalcopyrite should be Cu + Fe³ + (S²⁻)₂. Disulfide (S₂²⁻) and polysulfide (S_n²⁻) can be easily formed on the surface of chalcopyrite due to the surface reconstruction. The dissolution process of chalcopyrite in bioleaching was mainly dependent on redox potential. Chalcopyrite was predominantly directly oxidized to polysulfide when redox potential was lower than about 350 mV vs. Ag/AgCl and resulted in low dissolution rate. When redox potential was in the range of about 350–480 mV vs. Ag/AgCl, chalcopyrite was mainly transformed to intermediate species of Cu₂S rather than polysulfide, thus resulting in high dissolution rate. When redox potential was higher than about 480 mV vs. Ag/AgCl, chalcopyrite was principally directly oxidized to polysulfide which caused the passivation of chalcopyrite. Finally, a model of dissolution and passivation mechanisms of chalcopyrite in the presence of sulfur and iron oxidizing microorganisms was provided.     

Bioleaching of chalcopyrite by Acidianus manzaensis under different constant pH

The bioleaching of pure chalcopyrite by thermophilic Archaea strain Acidianus manzaensis YN-25 under different constant pH was first comparatively investigated. Then the relevant sulfur speciation was analyzed by synchrotron radiation based X-ray diffraction (SR-XRD) and S K-edge X-ray absorption near edge structure (XANES) spectroscopy. The acidity of the leaching solution was monitored at 3-h intervals to make it steady at pH 1.25, 1.50, 1.75, 2.00, 2.25 and 2.50, respectively. Leaching results showed that the copper ion extraction increased during chemical leaching but decreased during bioleaching when pH value decreased from 2.50 to 1.25. SR-XRD analysis showed that, during bioleaching, new elemental sulfur (S⁰) phase was detected at all tested pH cases; new jarosite phase was detected at cases of pH 1.50 to 2.50; and jarosite gradually became a major phase when pH value increased. XANES analysis further showed that covellite was detected during bioleaching at cases of pH 1.25 to 2.00 at higher redox potential (ORP) value, while chalcocite and bornite were detected at cases of pH 2.25 and 2.50 at lower ORP value. These results suggested that the formation of S⁰ was mainly accounting for hindering the dissolution of chalcopyrite while the formation of bornite could accelerate the dissolution of chalcopyrite by A. manzaensis.