A new extraction process of refractory gold arsenosulfide concentrates

A new hydrometallurgical process for the refractory gold arsenosulfide concentrates under normal temperature and pressure was presented. The experimental results of a refractory gold concentrate show that the total consumption of NaOH in alkaline leaching is only 40% of those theoretically calculated under the conditions of full oxidization at the same oxidation of arsenic to arsenate and sulfur to sulfate. After alkaline leaching, cyanidation and adsorption were carried out for 24 h. The dissolution of gold by NaCN is increased to 95.3% from 12.8% before pretreatment, and meanwhile 99.3% of the adsorption of gold by activated charcoal.The consumption of NaCN for one ton ore is 10 kg, which is 1.2 times less than that before pretreatment. As it is carried out under normal temperature and pressure, the investment of installations is also decreased.     

Biooxidation-thiosulfate leaching of refractory gold concentrate

A process of biooxidation followed by thiosulfate leaching of gold from refractory gold concentrate was investigated. Mineralogical studies on the concentrate showed that very fine gold grains(10 μm) were encapsulated in pyrite and arsenopyrite, while the proportion of monomer gold was only 21%. The gold-bearing sample was identified as a high-sulfur fine-sized wrapped-type refractory gold concentrate.The gold leaching efficiency obtained by direct cyanidation was only 59.86%. After biooxidation pretreatment, the sulfide minerals were almost completely decomposed, 92 wt% of the mineral particles of the biooxidation residue were decreased to 38 μm, and the proportion of monomer gold in the biooxidation residue was over 86%. Meanwhile, the gold content in the biooxidation residue was enriched to 55.60 g/t,and the S, Fe, and As contents were reduced to approximately 19.8 wt%, 6.97 wt%, and 0.13 wt%, respectively. Ammoniacal thiosulfate was used for gold extraction from the biooxidation residue of the refractory gold concentrate. The results showed that the optimal reagent conditions were 0.18 M thiosulfate, 0.02 M copper(II), 1.0 M ammonia, and 0.24 M sulfite. Under these conditions, a maximum gold leaching efficiency of 85.05% was obtained.     

Pretreatment and thiosulfate leaching of refractory gold-bearing arsenosulfide concentrates

A hydrometallurgical process for refractory gold-bearing arsenosulfide concentrates at ambient temperature and pressure was presented, including fine grinding with intensified alkali-leaching (FGLAL), enhanced agitation alkali-leaching (EAAL), thiosulfate leaching and displacement. Experimental results on a refractory gold concentrate showed that the total consumption of NaOH in alkaline leaching is only 41% of those theoretically calculated under the conditions of full oxidization for the same amount of arsenides and sulfides transformed into arsenates and sulfates, and 72.3% of gold is synchro-dissoluted by thiosulfate self-generated during alkaline leaching. After alkaline leaching, thiosulfate leaching was carried out for 24 h. The dissolution of gold is increased to 91.9% from 4.6% by cyanide without the pretreatment. The displacement of gold by zinc powder in the solution gets to 99.2%. Due to an amount of thiosulfate self-generated during alkaline leaching, the reagent addition in thiosulfate leaching afterwards is lower than the normal.     

含铜难处理金矿选择性浸出试验研究

针对某含铜难处理金矿进行了碘化法和石硫合剂(lime sulfur synthetic solution,LSSS)法的选择性浸金的研究。结果表明,在碘单质质量浓度为8g/L,浸出时间为2h的条件下,碘化法浸出金的浸出率为88.1%,而且铜的浸出率不足1%。在石硫合剂质量分数为25%,浸出时间为6h的条件下,LSSS法浸出金的浸出率仅为73.5%。对比碘化浸出和石硫合剂浸出效果可知,碘化法对该含铜难处理金矿不仅浸出速度快、浸出率高而且铜几乎不被浸出,具有很强的选择性浸金作用。     

Pretreatment of copper-bearing refractory gold ores by bio-heap leaching

The refractory gold ores associated with rich copper and trapped in pyrite and quartz were studied. With conventional technique (all-sliming cyanidation), the gold recovery rate is only 51.78%. To eliminate the negative effects of copper and pyrite on cyanidation and increase the gold recovery rate, the investigation on bio-heap leaching pretreatment was made, by which Cu would be dissolved and gold would be liberated from pyrite. The experiment adopted mixed bacteria, mainly Thiobacillus ferrooxidan (named T. f1), as the bacterial catalyst for bio-preconditioning and was carried out in a PVC column with a diameter of 20 cm and a height of 1.3 m loaded with gold ores. The temperature was controlled between 28 and 30℃, the pH value was kept between 2.0-2.5,and the flux of sprinkling bacterial liquid was maintained 0.80 L/h. After 45-day's bio-oxidization, among the samples sizing from 0to 5 mm, the oxidation rates of Cu, Fe and S were respectively 44.62%, 28.16% and 25.46%, and the gold recovery rate by cyaniding increased to 80.35%. The bio-heap leaching pretreatment can therefore effectively dissolve Cu and liberate gold from pyrite and lead to the increase of gold extraction.     

Kinetics of leaching refractory gold ores by ultrasonic-assisted electro-chlorination

The resources of refractory gold ores are abundant, and their effective treatment can bring good economic benefits. This paper investigated the kinetics of leaching gold from refractory gold ores by ultrasonic-assisted electro-chlorination. The effects of ultrasound time ratio, initial hydrochloric acid concentration and leaching temperature on the kinetic parameters were discussed. It is found that the leaching ratio goes up with all the factors increasing. The reaction kinetics is controlled by diffusion. When ultrasound improves the diffusion by reducing the diffusion resistance, the activation energy increases to 37.1 kJ/mol.     

含砷难浸金矿次氯酸钠一步法浸金理论与技术

简单地评述了含砷难浸金矿处理技术的方法和特点,对次氯酸钠浸金的一步法问题进行了初步的讨论,并对次氯酸钠浸金的基础理论作了综述。     

用草酸在硫酸溶液中从中性浸出渣中还原浸出铟

The present study evaluates the reductive leaching of indium from indium-bearing zinc ferrite using oxalic acid as a reducer in sulfuric acid solution. The effect of main factors affecting the process rate, including the oxalic-acid-to-sulfuric-acid ratio, stirring rate, grain size, temperature, and the initial concentration of synergic acid, was precisely evaluated. The results confirmed the acceptable efficiency of dissolving indium in the presence of oxalic acid. The shrinking-core model with a chemical-reaction-controlled step can correctly describe the kinetics of indium dissolution. On the basis of an apparent activation energy of 44.55 kJ/mol and a reaction order with respect to the acid concentration of 1.14, the presence of oxalic acid was found to reduce the sensitivity to temperature changes and to increase the effect of changes in acid concentration. Finally, the equation of the kinetic model based on the factors under study is presented.     

Reductive leaching of indium from the neutral leaching residue using oxalic acid in sulfuric acid solution

The present study evaluates the reductive leaching of indium from indium-bearing zinc ferrite using oxalic acid as a reducer in sulfuric acid solution. The effect of main factors affecting the process rate, including the oxalic-acid-to-sulfuric-acid ratio, stirring rate, grain size,temperature, and the initial concentration of synergic acid, was precisely evaluated. The results confirmed the acceptable efficiency of dissolving indium in the presence of oxalic acid. The shrinking-core model with a chemical-reaction-controlled step can correctly describe the kinetics of indium dissolution. On the basis of an apparent activation energy of 44.55 k J/mol and a reaction order with respect to the acid concentration of 1.14, the presence of oxalic acid was found to reduce the sensitivity to temperature changes and to increase the effect of changes in acid concentration. Finally, the equation of the kinetic model based on the factors under study is presented.     

碘化浸金过程的基本理论

碘化浸金被证明是一种有效环保的非氰浸金方法,但金溶解过程中的基本理论目前研究很少。结合热力学数据,计算了实际的浸金体系中主要反应平衡电位,建立了可能存在的化学反应及电位和pH之间的关系式,完整地做出了实际浸金体系的V—pH图,并对碘化浸金机理进行分析。该研究为碘化浸金的工业化提供了理论指导。     

高压脉冲放电预处理强化卡林金浸出效果分析

A high-voltage pulsed discharge (HVPD) pretreatment was used to strengthen the leaching effect of Carlin-type gold ore containing arsenic. Optimal results of the pretreatment experiments were obtained at the following operating conditions: a spherical gap spacing of 20 mm, pulse number of 100, and voltage of 30 kV. The leaching rate of gold was increased by 15.65% via the HVPD pretreatment. The mass fraction of –0.5+0.35 mm and –0.35+0.1 mm was increased by 10.97% and 6.83% compared to the untreated samples, respectively, and the Au grade of –0.1 mm was increased by 22.84%. However, the superiority of the HVPD pretreatment would be weakened by prolonged grinding time. Scanning electron microscopy results indicated that the pretreated products presented as a melting state and then condensation, accompanying by some pore formation. More micro-cracks were generated at the interface of the ore and the original crack were expended via pulsed discharge pretreatment, with the contact area between the leaching reagent and ore increased, the leaching reaction rate enhanced and the leaching effect strengthened.     

Strengthening leaching effect of Carlin-type gold via high-voltage pulsed discharge pretreatment

A high-voltage pulsed discharge(HVPD) pretreatment was used to strengthen the leaching effect of Carlin-type gold ore containing arsenic. Optimal results of the pretreatment experiments were obtained at the following operating conditions: a spherical gap spacing of 20 mm,pulse number of 100, and voltage of 30 k V. The leaching rate of gold was increased by 15.65% via the HVPD pretreatment. The mass fraction of –0.5+0.35 mm and –0.35+0.1 mm was increased by 10.97% and 6.83% compared to the untreated samples, respectively, and the Au grade of –0.1 mm was increased by 22.84%. However, the superiority of the HVPD pretreatment would be weakened by prolonged grinding time.Scanning electron microscopy results indicated that the pretreated products presented as a melting state and then condensation, accompanying by some pore formation. More micro-cracks were generated at the interface of the ore and the original crack were expended via pulsed discharge pretreatment, with the contact area between the leaching reagent and ore increased, the leaching reaction rate enhanced and the leaching effect strengthened.     

Extraction of metals from complex sulfide nickel concentrates by low-temperature chlorination roasting and water leaching

The recovery of valuable metals from complex sulfide concentrates was investigated via chlorination roasting followed by water leaching. A reaction process is proposed on the basis of previous studies and the results of our preliminary experiments. During the process, various process parameters were studied, including the roasting temperature, the addition of NH₄Cl, the roasting time, the leaching time, and the liquid-to-solid ratio. The roasted products and leach residues were characterized by X-ray diffraction and vibrational spectroscopy. Under the optimum condition, 95% of Ni, 98% of Cu, and 88% of Co were recovered. In addition, the removal of iron was studied in the water leaching stage. The results demonstrate that this process provides an effective approach for extracting multiple metals from complex concentrates or ores.     

难处理铜钴合金的氧化酸浸出

采用硫酸和盐酸的混合酸在有氧化剂存在的常压条件下对磨细后的铜钴合金进行浸出.试验结果表明:在溶液初始酸度为5.0～6.5 mol/L,硫酸与盐酸摩尔比较低,酸过量系数φH为1.2,氧化剂加入量ψn为理论量的1.2倍,反应温度为80 ℃,反应时间为70 min,搅拌速度为200～300 r/min的条件下,铜钴浸出率均能达到97%以上,浸出过程中不会有硅胶产生,过滤性能良好,实验重现性好.     

镍钼矿提钼渣中镍的浸出工艺

在硫酸溶液中,使用常压氧化浸出法处理镍钼矿提钼渣以回收有价金属镍。考察搅拌速度、液固比、硫酸用量、氧化剂用量以及浸出时间对镍浸出过程的影响。试验结果表明:搅拌速度与液固比对浸出过程影响不明显;在未加入氧化剂时,主要发生镍氢氧化物简单的酸溶反应,而添加氧化剂后硫化物也被氧化浸出;此外,镍浸出率随浸出时间、温度及硫酸用量的增加而增大。最佳工艺条件如下:搅拌速度为500 r/min,液固比为4:1,氧化剂加入量为矿量的0.2倍,浸出温度为90℃,硫酸浓度为0.4 mol/L,浸出时间为8 h,镍浸出率可达95%左右。     

铜阳极泥碱性加压氧化浸出渣的硫酸浸出过程

针对铜阳极泥碱性加压氧化浸出渣开展硫酸浸出过程研究,考察硫酸浓度、温度、时间、液固比、搅拌速度和氧化方式等因素对浸出渣渣率和金属浸出率的影响.研究结果表明:金属浸出率随硫酸浓度的增加而提高,银的溶解尤为明显;硫酸浸出渣中未溶解的铜主要以单质存在,采用空气氧化方式可以提高铜的浸出率;在最佳条件即硫酸浓度为2.7 mol/L,温度为85℃,液固比为5∶1,时间为2h,空气压力为0.1～0.2 MPa和搅拌速度为300 r/min下,硫酸浸出渣率为60.0％,Cu和Te的浸出率分别为97.65％和77.53％,Ag和Sb的浸出率分别为8.95％和2.0％.     

从难处理金矿中回收金:黄铁矿对硫脲浸金体系稳定性的影响

The extraction of gold from refractory gold ores (RGOs) without side reactions is an extremely promising endeavor. However, most RGOs contain large amounts of sulfide, such as pyrite. Thus, investigation of the influence of sulfide on the gold leaching process is important to maximize the utilization of RGOs. In this work, the effects of pyrite on the stability of the thiourea system were systematically investigated under different conditions. Results showed that the decomposition rate of thiourea was accelerated sharply in the presence of pyrite. The effect of pyrite on gold recovery in thiourea leaching systems was then confirmed via a series of experiments. The decomposition efficiency of thiourea decreased by 40% and the recovery efficiency of gold increased by 56% after the removal of sulfide by roasting. Under optimal conditions, the efficiency of the gold recovery system increased to 83.69% and only 57.92% of thiourea decomposition was observed. The high consumption of thiourea by the leaching system may be attributed to not only adsorption by mineral particles but also catalytic decomposition by some impurities in the ores, such as pyrite and soluble ferric oxide.     

Recovery of gold from refractory gold ores: Effect of pyrite on the stability of the thiourea leaching system

The extraction of gold from refractory gold ores(RGOs) without side reactions is an extremely promising endeavor. However, most RGOs contain large amounts of sulfide, such as pyrite. Thus, investigation of the influence of sulfide on the gold leaching process is important to maximize the utilization of RGOs. In this work, the effects of pyrite on the stability of the thiourea system were systematically investigated under different conditions. Results showed that the decomposition rate of thiourea was accelerated sharply in the presence of pyrite. The effect of pyrite on gold recovery in thiourea leaching systems was then confirmed via a series of experiments. The decomposition efficiency of thiourea decreased by 40% and the recovery efficiency of gold increased by 56% after the removal of sulfide by roasting. Under optimal conditions, the efficiency of the gold recovery system increased to 83.69% and only 57.92% of thiourea decomposition was observed. The high consumption of thiourea by the leaching system may be attributed to not only adsorption by mineral particles but also catalytic decomposition by some impurities in the ores, such as pyrite and soluble ferric oxide.     

锗烟尘浸出过程热力学分析

贵州、云南锗烟尘主要含锌、铅、锗、银等有价金属。对锗烟尘酸性浸出过程进行了热力学分析，讨论了锗烟尘中主要物质在浸出过程的行为。     

电解锰渣固结体中重金属浸出毒性及其在模拟酸雨下的淋溶特性分析

以一种硅铝基胶凝材料为固结剂,对某电解锰厂的锰渣进行固化处理,分析在不同养护周期下锰渣固结体中重金属的浸出毒性,通过动态淋溶试验,研究养护周期和模拟酸雨pH值对固结体淋溶特性的影响,并通过SEM和XRD手段,分析酸雨淋溶前后固结体的形貌和成分,探讨固结体淋溶过程中重金属的溶出机理。结果表明,固化处理可有效固定锰渣中的重金属,固结体的养护周期对其在酸雨淋溶过程中Mn的溶出影响较大,其中养护28天的锰渣固结体在不同pH值酸雨淋溶条件下,淋溶液中Mn和Zn的最高浓度分别为0.189、0.116mg·L~(-1),其它重金属含量也较低,均低于国家标准浓度限值;酸雨淋溶过程中,固结体的晶体结构没有受到破坏,大部分的重金属被包裹在晶体内部或以更稳定的化合态存在,不易被溶出。