Characterization of refractory behaviour of complex gold/silver ore by diagnostic leaching

The amenability of a refractory ore to the extraction of gold and silver by cyanide leaching was investigated. Diagnostic leaching tests were also performed to shed light on the refractory characteristics of ore. The leaching tests show that the extraction of gold and silver is consistently low, i.e. ≤47% and ≤19.2%, respectively, over a leaching period of 24 h. Even fine grinding (e.g. ＜38 μm) does not improve the recovery of gold and silver. Diagnostic leaching approach provides information into the cause of the refractoriness of the ore. The findings suggest that the refractoriness is induced by the dissemination and encapsulation of the very fine gold and silver particles largely in the carbonates, oxides and sulfides and, to a small extent, with silicates present in the ore matrix. These findings highlight the practical importance of diagnostic leaching for the understanding of the refractory characteristic of such an ore and for the identification of possible pretreatment options to overcome its refractoriness prior to cyanide leaching.     

某微细粒砷黄铁矿包裹金矿的非氰浸出研究

采用非氰浸化剂(石硫合剂)对含金为2.47 g/t的甘肃某微细粒砷黄铁矿包裹金矿进行浸出试验,研究预处理方式和浸出工艺对金浸出率的影响。结果表明,石硫合剂对金的直接搅拌浸出率低于30%,该矿属难浸金矿石;采用边磨边浸-搅拌浸出的方式,浸出率可提升至68.4%;增加碱式预氧化处理,可将金的浸出率进一步提升到80%以上。采用最优的工艺,边磨边碱式预氧化36 h,经石硫合剂搅拌浸出5 h,金的浸出率可达到91.5%。     

The commercial status of pressure leaching technology

First developed in the 1950s for treating base metal sulfides and refractory gold ores, pressure leaching technology underwent rapid commercial expansion during the 1980s. Initially used to treat nickel concentrates and mattes, pressure leaching has since been extended to the processing of zinc sulfide concentrates and sulfide-containing refractory gold ores. The adoption of pressure leaching in the zinc industry and of pressure oxidation in the gold industry is expected to continue throughout this decade.     

重金属强化含金矿石的氰化浸出

通过分析铊、铋、汞和铅等重金属强化金氰化溶解的电化学原理,对含金氧化物矿石和难浸硫化物金精矿进行了重金属强化浸金研究.结果表明:重金属对金氰化溶解的阳极过程有显著的强化作用,但在常规供氧条件下,金的溶解速率并未显著提高;只有同时采用阴极强化措施,才能使重金属起到显著提高金溶解速率的作用;对于含金氧化物矿石,单独采用重金属强化即可明显提高浸金速率,如果在过氧化氢助浸的基础上添加重金属,金的浸出速率会有更大幅度的提高;对硫化物金精矿而言,单独采用重金属无明显强化效果,只有在添加过氧化氢作为辅助氧化剂的基础上,重金属对金的浸出才能起到强化的作用,该体系中过氧化氢起到了强化阴极过程和氧化硫化物的双重作用.     

难处理高砷金矿的细菌氧化-提金研究

采用经过驯化的HQ0211菌对高砷金矿进行氧化预处理-氰化提金实验研究.该矿石含金128.5 g/t,含砷16.84%(质量分数,余同),含硫21.72%,含铁26.62%,氰化浸出率只有29.35%,是典型的高砷难处理矿.经过细菌氧化预处理,金矿脱砷率达到96.2%,失重率达到43.9%.矿石的金氰化浸出率由原来的29.35%提高到92.57%,效果十分显著.     

A new extraction process of carbonaceous refractory gold concentrate

A new hydrometallurgical process for a carbonaceous refractory gold concentrate at ambient temperature and pressure was presented, including grinding-leaching, intensified alkaline leaching（IAL）, thiosulfate leaching and cementation by zinc powder. The experimental results show that the grinding-leaching and intensified alkaline leaching process result in the selective oxidation of arsenopyrite and pyrite. The oxidation ratio of As is 96.6%, and 46.7 % for S. The total consumption of NaOH in alkaline leaching is only 28 % of that theoretically calculated under the conditions of full oxidization for the same amount of arsenopyrite and pyrite transforming into arsenates and sulfates, and 83.6% of gold is synchro-dissoluted by thiosulfate self-generated during pretreatment. Since the carbonaceous matter in concentrate possesses a strong capability of preg robbing, the cyanidation process is not suitable for the extraction of gold after pretreatment. However, the gold leaching rate by thiosulfate leaching for 24 h is increased to 91.7% from 0 - 3.2% by ultra-fine grinding without the pretreatment. The recovery of gold by zinc cementation gets to 99.6%. Due to the thiosulfate self-generated during alkaline leaching, the reagent addition in thiosulfate leaching afterwards is lower than the normal one.     

硫精矿中难选金银焙烧浸出研究

某高金硫精矿全泥氰化时金和银的浸出率低,一段焙烧预处理会造成金和银的二次包裹。实验结果显示,二段焙烧效果优于一段焙烧效果,能降低氧化铁的烧结程度,减少铁氧化物对金、银的包裹,金、银浸出率分别为79.86%、68.13%。添加剂实验结果表明,焙烧过程加入NaOH,银浸出率大幅提高;加入CaO有利于金的浸出;加入KMnO4能降低焙砂硫品位。以NaOH、CaO、KMnO4为组合焙烧添加剂,金、银浸出率提高至87.43%、85.86%。扫描电镜观察到,加入组合焙烧添加剂有利于焙砂孔隙度的提高,氰化尾渣表面腐蚀较为严重,有利于浸出剂与金、银的接触。 关健词:含金硫精矿;全泥氰化;二段焙烧;焙烧添加剂     

Controlling SO2 emissions in the roasting of gold concentrate

Acid pressure oxidation is generally believed to be the most effective pretreatment for refractory sulfide gold ores and concentrates, although it is ineffective for some ores. For such ores and concentrates (usually those containing both carbonaceous and sulfide materials), roasting remains the most effective pretreatment before cyanidation. However, the serious environmental damage that could result from the emission of SO₂ and As₂O₃ makes roasting an unattractive pretreatment step. In an effort to develop a technique having lower SO₂ emissions, a lime agglomeration roast (LAR) pretreatment process was investigated. The technique involves the agglomeration of calcium-based SO₂ sorbent with the refractory ore or concentrate before roasting. The results of the LAR pretreatment followed by cyanidation indicate that up to 95 percent of the sulfur dioxide can be captured and more than 90 percent gold extraction can be achieved.     

Acid equilibrium during bioleaching of alkaline low-grade sulfide copper ore

This article reports the study on acid equilibrium during bioleaching of alkaline low-grade copper sulfide ore. Adding auxiliary agents 1# （sulfur） and 2# （pyrite） makes bacterial leaching of copper and acid production carried out simultaneously because the auxiliary agents can be oxidized by bacteria and the oxidation products involve acid. The acid required for dissolving alkaline gangue during bacterial leaching is produced, and acid equilibrium is reached during the ore bio-leaching. The recovery of copper reaches more than 95%.     

某金矿热压氧化后氰化浸金氰化钠消耗实验研究

简要介绍了我国难处理金矿资源现状、难选冶原因、预处理方法,详细分析了该类资源中有害元素热压氧化过程的化学过程。针对某金矿热压氧化渣进行了炭浸氰化实验,考察了p H、调浆时间、底炭浓度、浸出时间对氰化钠消耗量的影响。实验证明,经过热压氧化,能够降低炭浸氰化过程中的氰化钠消耗量及氰化时间。针对实验样,氰化钠消耗量仅为0.27~0.29 kg/t,浸出时间为2~4 h,浸出率为95.34%。     

从低品位含金尾矿中回收金的堆浸参数研究

辽宁丹东某铜矿尾矿金品位为1.35 g/t,属低品位难处理金矿。采用柱浸模拟现场堆浸工艺条件,对工艺参数进行了模拟试验。条件实验表明,在浸出剂氰化钠浓度为0.10%、石灰水喷淋调整浸出液pH=11、矿层高度305 mm、在10℃以上浸出120 h,金浸出率为58.14%。放大试验延长浸出时间至480 h,金浸出率达到70%左右。获得的工艺参数可为堆浸生产提供指导。     

微细浸染型金矿强化湿法预处理研究

采用两段充气预处理-非氰化工艺浸出微细浸染型金矿,研究了浸出条件对金浸出效率的影响。结果表明,在氧化和碱浸预处理2个阶段充气可提高金浸出率;氧化预处理2 h后,加入氢氧化钠(20 kg/t)碱浸预处理4 h,加入氧化钙(40 kg/t)替代氢氧化钠,用TY-3浸出剂(8 kg/t)浸出4 h,金浸出率可达87.21%。浸出渣的物相分析、扫描电镜观察及X射线能谱分析结果显示,硅酸盐、碳酸盐中的金可被有效浸出,浸出渣中的石英、黄铁矿表面发生腐蚀,部分黄铁矿氧化。     

Mineralogical characterization and pretreatment for antimony extraction by ozone of antimony-bearing refractory gold concentrates

The mineralogical characterization of antimony-bearing refractory gold concentrates and the antimony extraction by ozone in HCl solution were investigated. The mineralogical study shows that there exist stibnite(Sb₂S₃), arsenopyrite(FeAsS), pyrite(FeS₂) and quartz in the concentrates, and the gold is mainly (67.42%) encapsulated in sulfides. The antimony extraction by ozone in hydrochloric acid was employed and the influences of temperature, liquid/solid ratio, HCl concentration and stirring speed on the extraction of antimony were investigated. High antimony extraction (93.75%) is achieved under the optimized conditions. After the pretreatment by ozone, the antimony is recovered efficiently and the gold is enriched in the leaching residue.     

高砷难处理硫精矿氰化浸出提银实验研究

某硫精矿中的银矿物嵌布粒度非常细小,包裹于硫化物中的银约占50.46%,属于难处理高砷含银硫精矿。采用细磨后化学预处理氰化浸出,银浸出率仍然低于80%;硫精矿经氧化焙烧后,As、S的脱除率都达到90%以上,但银浸出率却较低;对该含银硫精矿添加钠盐焙烧预处理,再采用常规氰化法浸出,银浸出率显著提高,达到85.15%,同时氰化钠耗量降低至2.0 kg/t。     

BIOOXIDATION OF TWO ARSENICAL REFRACTORY GOLD CONCENTRATES AND GOLD CYANIDATION

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有色金属硫化矿中伴生金银资源回收研究进展

有色金属矿产资源中伴生的金银矿物是贵金属金银资源的重要来源,伴生金银的回收一直是各国选矿工作者研究的重点。伴生金银资源主要分布在硫化铜、硫化铜铁及硫化铅锌矿石中,由于共伴生金银嵌布粒度粗细不均,金银捕收剂对矿石的适应能力不强,导致现有浮选工艺及药剂制度难以满足伴生金银回收的要求,严重影响了伴生金银的回收效果。在伴生金银工艺矿物学研究基础上,针对不同矿石中伴生金银资源的回收特点,选矿工作者通过改进和强化磨矿工艺、选择合理的工艺流程及开发多种新型金银捕收剂,显著提高了有色金属硫化矿中伴生金银资源的选矿指标。     

紫金山铜金矿中金铜银的赋存状态研究

采用矿物自动分析仪(MLA)、扫描电镜(SEM)、X射线衍射(XRD)研究了紫金山金铜矿入选矿石中有价元素铜、金、银的赋存状态以及分选过程中的金属走向。结果表明,铜矿物主要有蓝辉铜矿、铜蓝、硫砷铜矿,金银以游离矿物和硫化物包裹体为主。铜矿物常见沿明矾石溶蚀孔洞或碎裂缝隙充填,与黄铁矿密切连生,从原矿中分选铜矿物,理论品位为Cu 69.70%,理论回收率93.55%。中粒金嵌布于铜矿物和黄铁矿矿物粒间或裂隙,可随着铜和硫的回收进入铜、硫精矿,金的理论回收率分别为57.19%和27.27%;微细金粒包裹于明矾石和石英中,随脉石损失于尾矿中。银以显微银为主,多见呈微细粒包裹于硫化矿物中,铜精矿和硫精矿中银的理论回收率分别为56.96%和26.71%。     

低品位铁锰型金银矿的硫脲浸出研究

对铁锰型金银矿采用预先浸锰工艺,使被二氧化锰包裹金银裸露出来,同时降低硫脲浸出金银时的氧化还原电位,有效减少了硫脲消耗量.结果表明,当矿样为200g,经浸锰预处理后,在pH =1.5,电位300mV,亚硫酸钠6g,浸出时间4h的最佳条件下,金、银的浸出率分别为98%、45%,硫脲消耗仅为6kg/t.     

Bioleaching: A microbial process of metal recovery; A review

The present review describes the historical development and mechanisms of bioleaching. Recent development has shown commercial application of the process and, concurrently, details pertaining to the key microorganisms involved in these processes have been described. Bioleaching of metal sulfides is caused by diverse groups of bacteria. The dissolution biochemistry signifies two types of pathways, which are specifically determined by the acid-solubility of the sulfides, the thiosulfate and polysulfate pathways. This sulfide dissolution can be affected by ‘direct’ and ‘indirect’ mechanisms. In the ‘indirect’ mechanism bacteria oxidize only dissolved iron (II) ions to iron (III) ions and the latter can then attack metal sulfides and then be reduced to iron (II) ions. The ‘direct’ mechanism requires the attachment of bacteria to the sulfide surfaces. In the case of thiobacilli, bacteria secrete exopolymer that facilitates attachment of the bacteria to a metal surface, thus enhancing the leaching rate. In terms of eco-friendliness and process economics, within the field of biohydrometallurgy the technology is considered robust.     

Ferric Chloride,Thiourea and Brine Leach Recovery of Ag,Au and Pb from Complex Sulfides

The Bureau of Mines recently investigated a hydrometallurgical procedure to recover gold, silver, and byproduct lead from a complex lead-zinc sulfide ore. A ferric chloride (Fecl₃) preleach, at 40°C for six hours extracted about 50 percent of the zinc and formed insoluble silver and lead chlorides. Subsequent acid thiourea leaching, for one to three hours at 40°C, extracted about 85% of the gold and silver. Lead chloride was solubilized from the remaining residue with NaCl brine solution at 55°C in one hour. Lead was recovered from the brine solution in an electrolytic cell with an anion perm selective membrane at a current efficiency of 95 percent and current density of 100 A/m². Spent FeCl₃ leach solution was reoxidized in the anode compartment at a current efficiency between 75 and 95 percent.