贵州省兴义市雄武地区金矿石堆浸的工艺研究

贵州省兴义市雄武地区金矿主要为卡林型,其次为红土型,矿床受断裂构造控制,矿石为中等含硫微细浸染状氧化矿石。目前浅部矿石已基本采完,深部矿石品位较低(0.8~1.8 g/t),因此有效提高低品位矿石浸出率和金回收率至关重要。研究表明,筑堆时矿石粒度和喷淋时氰化钠浓度是堆浸生产中的重要影响因素。矿石粒度大,金浸出率低;氰化钠浓度大,则成本增加。根据矿石物质成分和工艺特征研究,得到矿石冶炼时的最佳工艺条件:筑堆时矿石粒度为15~25 mm,氰化钠浓度为0.05%~0.08%。该研究有效提高了矿石浸出率,降低了运营成本,为金矿石堆浸实际生产提供了理论和实验依据。     

Gold in Egypt: Does the future get worse or better?

Within the Eastern Desert of Egypt, there are more than a hundred vein-type gold deposits and occurrences. Gold was mined in the Dynastic and Roman periods of the Egyptian history and most of the attention was focused entirely on the near-surface high grade parts of these veins. Currently, besides the more problematic sulfide-rich quartz veins, which generally occur in the lower levels of the worked out auriferous quartz veins, some targets including wall-rock alteration, listwaenite, dumps and tailings of ancient mines, by-product gold hosted in volcanogenic massive sulfide deposits and gold-bearing Algoma-type BIF, as well as alluvial gold constitute the new targets for gold in the Eastern Desert of Egypt. In most of these targets, gold displays a bimodal distribution; occurring both as free-milling gold and in the form of sub-microscopic or “invisible” gold in refractory sulfides and sulfoarsenides such as pyrite, chalcopyrite, arsenopyrite, gersdorffite and pentlandite minerals.Characterizing gold in an ore is important in extraction metallurgy. Free-milling gold can be efficiently recovered by crushing, grinding and cyanidation without additional processing. In refractory ores, on the other hand, conventional milling can liberate the sulfides from the gangue allowing a low content of concentrate to be produced by a process such as flotation. However, direct leaching of the concentrate results in poor gold extractions as the cyanide lixiviant is unable to contact the gold locked within the refractory host. Oxidative pretreatment is required for such ores and the methods available for oxidation are roasting (calcination), pressure oxidation, and bacterial oxidation; all oxidize the refractory minerals in the ore to render the gold amenable to cyanidation. While such oxidative methods are capable of achieving reasonable recoveries, they increase the capital and operating costs. An alternative, applicable to the liberation of gold from the refractory host, is to continue the grinding process to reduce the particle size of the host mineral thereby exposing a part of the gold surface for contact with the cyanide solution. A benefit of this technique is that the environmental aspects of the oxidation reaction products are avoided, however the ultra fine grinding also adds more operating costs.Metallurgical studies carried out on some gold deposits, dumps and tailings of ancient gold mines in Egypt, proved that these ores are amenable to percolation leaching (concentration of KCN varies between 0.5 and 1 g/L) for the (− 10 mm) grain size, and consequently heap leaching is a successful technique as the results of these laboratory scale column tests show. In most of these studies, a marked improvement in the percent of gold recovery was gained when the crushed ore is agglomerated by the addition of water, lime and/or cement particularly in ores containing significant quantities of clay minerals and clay-forming minerals (e.g. sericite and muscovite), and by addition of kerosene which passivates the adsorption surfaces on the graphite.Placer gold is recovered by gravity methods utilizing the large difference in specific gravity between gold and commonly associated minerals such as quartz and feldspar. The equipments range from a simple pan to more complex devices used in gold recovery plants and dredges.Modern studies in Egypt point to the presence of different targets of gold; diverse in their gold content, mode of occurrence of gold and the metallurgical treatments required for extracting gold. With the advance of modern techniques such as Electron Microprobe Analyses (EMPA), laser Ablation Microprobe Inductively Coupled Plasma Mass Spectroscopy (LAM-ICP-MS), gold ores in Egypt should be re-characterized precisely to know the specifications of these ores and consequently predict the metallurgical regime required, and with the high world gold price, it has become necessary to take into consideration the presence of refractory gold ores as one of these targets in Egypt. Generally speaking, laboratory experiments conducted on gold processing in Egypt are encouraging to some extent; however the gold extraction rates of the free milling ores with conventional cyanidation and refractory ores with direct and pretreatment techniques can be improved by modifying the conditions of extraction to be consistent with the results obtained from the re-characterization stage. Otherwise any target for gold and whatsoever the mode of occurrence of gold in this target (i.e. free-milling and/or refractory) could be recovered directly by heap leaching technique and we should accept less than ideal gold recovery for any target when weighed against the capital expenditure required for processes such as roasting, and the continuous grinding processes which might improve recoveries by only a small percentage.     

堆浸提金原理与试验研究

本文介绍了堆浸提金原理和在实验室进行金矿石堆浸可行性研究的方法.以我国辽宁猫岭金矿、四川茶铺子金矿和福建紫金山金矿为研究对象,研究了矿石粒度、氰化钠溶液浓度、浸出时间等因素对金浸出率的影响,从而确定堆浸提金最佳工艺条件.通过对上述三类矿石性质及堆浸性能的比较,认为矿石的物质组成和金的嵌布特性对金的浸出率影响较大.     

金矿的细菌浸出处理研究

利用细菌对难处理金矿进行浸出处理,具有成本低廉、环境污染小、处理效率高等突出优点,已成为非常有前途的难处理金矿的预处理方法。笔者以河北遵化滑石峪金矿(含金黄铁矿)样品为例,在几种氧化亚铁硫杆菌中发现D3菌种处理此类难浸金矿有显著的增大提金率的效果。在200目粒度条件下,氰化提金率从单纯氰化的63.9%提高到细菌预处理后再氰化的88.2%,而且对100目以下的大粒度金矿,提金率也普遍提高10%以上;此外,还进行了该菌种处理金矿过程的条件实验,如粒度影响、pH值变化和物理方法强化的研究,得出了金矿在细菌氧化过程中的一些规律和在实际操作时的最优化控制条件。     

Gold Dissolution in Dry Salt Melts in the Presence of SiO<Subscript>2</Subscript> as a Function of Р(O<Subscript>2</Subscript>)

The solubility of gold was measured in dry NaCl salt melt at 860°С in closed systems with SiO₂ (silica glass). The reactions do not occur in a closed system without oxidizer. Reaction of SiO₂ with salt in the presence of an oxidizer (KClO₄) results in the formation of water-soluble sodium silicates (a mixture of meta-, ortho-, and pyrosilicates). Gold mobilization by a salt melt is limited by the diffusion of Na in SiO₂. In a closed system with the addition of a strong oxidizer (dry KClO₄ salt), the solubility of gold increase with increasing amount of KClO₄ and the saturation level is estimated to be ~3 wt % Au. For ampoule configurations used in our experiments, 5.5 g of gold dissolved per 1 g of KClO₄. Only cheap, non-toxic reagents were used in our model experiments on gold dissolution in a salt melt, which did not require elevated pressures. The solubility of 30 g Au per 1 kg NaCl will eliminate geochemical problems associated with the compact leaching of gold ores using cyanide.     

Analysis of the gold recovery profile through a cyanidation plant

Leaching in the grinding circuit is currently practiced in plants that process gold ores with low content of cyanide consuming minerals. The high gold recovery observed in the grinding–classification section of the plant is commonly explained by the inherent high initial dissolution rate of gold observed in gold ore cyanidation, or by the intense agitation prevailing in grinding mills. For understanding this leaching behavior of gold ores, the grinding, classification and leaching sections of a gold processing plant are analyzed through reconciliation of operating data. It is found that gold circulation in the grinding circuit is quite different from the flow behavior of other species due to the strong gold separation effect in the hydrocyclones, which produces quite large residence time for gold-rich particles. The results presented in this study demonstrate that the residence time of these particles in the grinding circuit can be as long as in the leaching tanks and might be the dominant factor in explaining the high dissolution of gold in this section.     

青海某金矿石可选性试验研究

针对青海省某金矿采用常规的氰化浸出效果不佳（金浸出率仅为8.19%）和含较高的砷、硫的情况和特点,进行了可选性试验研究。摇床重选虽然可获得品位较高的金精矿,但其回收率太低。浮选试验表明,采用一粗三精三扫的浮选闭路流程,可获得品位为72.72g/t,回收率为88.74%的浮选金精矿,选别指标较为理想。确定的最佳操作条件为...     

Oxidative pre-treatment in thiosulphate leaching of sulphide gold ores

A diagnostic leaching showed that partial oxidation of the sulphide minerals in a gold ore was beneficial for thiosulphate leaching of gold. A pre-treatment process with oxidative ammoniacal solution enhanced the thiosulphate leaching of the sulphide ore, while the thiosulphate consumption was substantially reduced. The sulphide minerals partially decomposed in the pre-treatment process, exposing gold to the leach solution. Oxygen input by air bubbling and a longer contact time enhanced the oxidative ammonia pre-treatment process and hence accelerated subsequent thiosulphate leaching of the sulphide ore. Gold extraction in 0.8 M ammonia and 0.1 M thiosulphate solution after 24 h increased from 69% without pre-treatment to 81%, 84%, 90% and 94% respectively after 1, 3, 7 and 22 h pre-treatment. The consumption of sodium thiosulphate was 2.37 kg/t after 24 h leaching without pre-treatment, but was negligible after over 1 h oxidative ammonia pre-treatment. A counter-current leaching process was conducted in the leaching of the sulphide ore. The fresh leachant still gave higher leaching rates in contact with the pre-leached ore, while the pre-used leachant had significantly lower leaching kinetics and overall gold extraction in contact with the fresh ore. This 2-step counter-current leaching process proved that the leachant, other than the passivation, was the determinant factor causing the gold leaching rates to decrease after a certain time of leaching. The findings enable the thiosulphate leaching of high sulphide containing gold ores to be more efficient at lower thiosulphate consumption following the oxidative ammoniacal pre-treatment.     

卡林型金矿石中金的赋存状态分析新方法

卡林型金矿富含有机质,金主要呈显微一超显微分散状态存在,利用工艺矿物学参数自动检测分析仪(MLA)及传统化学方法只能大致判断矿石中金的赋存趋势,无法对其赋存状态准确定量.本文利用MLA仪器系统分析贵州回龙卡林型金矿,测得矿石中金主要以显微-超显微状态包裹于黄铁矿和毒砂中,少量被脉石等其他矿石包裹;黄铁矿约66％完全解离,而毒砂仅30％完全解离,载金矿物与其他矿物连生或者被包裹,将不利于硫化物包裹金的浸出.结合回龙金矿石中金的赋存特征和富含有机质的特点,对传统的物相分析流程进行改进,调整了硫化物包裹金和碳酸盐包裹金的浸出顺序,提出裸露金-碳酸盐包裹金-硫化物包裹金-硅酸盐包裹金的浸出流程,在裸露金及碳酸盐包裹金浸出时加入活性炭,利用竞争吸附抑制矿石中有机炭对金的吸附,降低有机炭对分相的影响.对比试验结果表明,采用改进的方法,有机炭含量在1％左右的金矿石分相时加入活性炭对各相测定值的影响不大;先浸出碳酸盐包裹金,再测定硫化物包裹金,各相的测定数据更加准确.改进的方法(加活性炭)用于测定回龙金矿中裸露金和碳酸盐、硫化物、硅酸盐包裹金,含量分别为1.25％、84.17％、11.46％和3.13％,与选矿试验结果相一致,表明该法适合应用于卡林型金矿中金的赋存状态分析.     

Characterization of Kolar gold field mine tailings for cyanide and acid drainage

The gold mining process at Kolar gold field (KGF) mines has generated about 32 million tons of tailings. Gold was extracted from the mined ores using cyanidation technique that involved dissolution of gold in the ore by water soluble alkali metal cyanides (example, sodium cyanide or potassium cyanide). Of the several dumps that received the mine tailings only the Kennedy’s Line dump was active prior to closure of the KGF mines in the year 2000. The Kennedy’s Line dump received sulfide bearing tailings in slurry form that comprised of spent ore and process water bearing soluble alkali metal cyanide. Depending on the pH of the tailing slurry, the free cyanides may exist as aqueous hydrogen cyanide that can escape to the atmosphere as hydrogen cyanide gas or occur as soluble cyanide (CN⁻) ions that can be leached by infiltrating water to the sub-surface environment. Additionally, the presence of pyrite minerals in the Kennedy’s Line dump makes them susceptible to acid drainage. This study examines the potential of gold tailings of Kennedy’s Line dump to release cyanide ions (CN⁻) and acid drainage to the sub-surface environment by performing physico-chemical and leaching tests with tailing samples collected from various depths of the dump, sub-surface soil samples beneath the dump and groundwater samples from vicinity of Kennedy’s Line dump. The chemical mechanisms responsible for the ambient cyanide and pH levels of the tailing dump, sub-surface soil samples and groundwater are also inferred from the laboratory results.     

The preg-robbing of gold and silver by clays during cyanidation under agitation and heap leaching conditions

Laboratory scale leaching tests were carried out in different experimental conditions, with monitoring of gold and silver recovery, the concentration of cyanide used in leaching, solution pH, and precious metal adsorption onto clay. Evidence for the adsorption or re-precipitation of gold from cyanide solutions onto clay minerals is conclusive and indicates that adsorption contributes to the total gold loss from conventional cyanidation. The loss is related to the type of clay, and appears to be affected by the extent of time cyanidation. It was observed that silver adsorption capacity was above 80% and that the degree of adsorption for gold oscillated between 1.68% and 7.49%, depending on the type and characteristics of the evaluated clay.     

松潘两岔河高砷高锑金矿石氰化提金工业试验

高砷高锑金矿石属难处理矿石之一，通过对两岔河高砷高锑金矿石采用碱浸预处理后进行堆浸和池浸氰化提金试验，获得了金浸出率76．80％和86．76％的较好指标，为该矿床的开发利用提供了一个工艺简单、经济上可行的途径。     

锁龙金矿成矿地质特征及找矿方向

锁龙金矿位于礼岷成矿带下二叠统细碎屑岩中,矿体规模为中型。受控于教场坝岩体外接触带之挤压断裂和劈理带,矿体以成分简单、低品位、赤铁矿化蚀变及氧化矿石易于氰化浸出为特征。本文通过分析和总结矿床成因及找矿标志,进一步指出了扩大锁龙金矿床规模的有效途径及寻找该类型矿床的方向,其地质找矿前景较为乐观。     

Mineralogical characteristics and recovery process optimization analysis of a refractory gold ore with gold particles mainly encapsulated in pyrite and Arsenopyrite

To interpret the leaching rules, select suitable treatment methods, or optimize the treatment process of refractory gold ores, an in-depth analysis of ore characteristics using ore mineralogy is required. In this study, the mineralogical characteristics of a low-grade refractory gold ore were analyzed by a variety of analytical techniques and methods. The ore composition was obtained by chemical analysis, and the main minerals include gold, pyrite, arsenopyrite, feldspar, mica, and quartz. Gold exists in the form of sub-microscopic gold with a particle size of fewer than 1.7 μm, of which 56.90 % is encapsulated gold, 16.97 % is semi-coated gold, and 26.13 % is fractured gold. The content, classification, shape, grain distribution, and occurrence state of the main minerals in the gold ore were obtained by microscopic observation and statistical analysis. Based on the results, the leaching rules of the gold ore were predicted, and suggestions for optimizing the pretreatment process were put forward. These results can accurately guide the pretreatment and leaching process of the gold ore and lay a foundation for the effective utilization of comparable gold ores.     

四川某难浸金矿的矿石性质研究

四川某金矿是一种难浸金矿，因为矿石中的金被包裹于含铁硫化矿物中，而且含有机炭质物。细菌Hst能有效氧化金矿中的硫化矿物以提高金的浸出率。如果细菌氧化矿石中铁的浸出率大于90％，金几乎完全解离，金的氰化浸出率大于90％。研究表明，该金矿的难浸特性是因为金包裹于含铁硫化矿物中，有机炭质物和粘土矿物对金浸出影响甚微。     

碳质银精矿氯化浸出工艺的研究与应用

采用氧化焙烧工艺对碳质银精矿进行除碳、除硫预处理,试验确定焙烧温度为650℃。焙砂以3YL--NaCl无氰氯化体系浸出,研究了影响氯化浸出的因素:3YL用量、氯化钠浓度、浸出酸度、时间、温度℃及固液比等,并在试验确定的工艺条件下,进行了公斤级试验,得出Au、Ag、Cu、Pb、Zn的氯化浸出率分别为95.1%、91.6%、85.7%、95.2%、83.8%。     

高粘土质氧化矿石制粒实验研究

通过对黔西南贞丰某一典型的高粘土质低晶位金氧化矿石浸出、粘结剂配比实验和催熟剂Ｎｏ．１浸金实验研究,表明少量复合粘结剂的加入,极大改善矿石的性质,提高浸取液的溶液渗稼性。４％复合粘结剂的掺入量,不仅使成球粒在２４ｈ内的抗坟强度达到４．０ｋｇｆ／ｃｍ＾２,而且在２４ｈ内氰化反应近乎完全,金溶出率高达９６％。     

东大滩锑金矿微生物预氧化提金试验研究

介绍了东大滩难浸金矿石微生物预氧化的方法及结果。东大滩石英脉型锑金矿石因金被毒砂包裹而难浸，采用微生物预氧化处理后全泥氰化金的浸出率由原来的17．04％提高到70．80％，柱浸由15．39％提高到63．02％，且酸耗较低，各项指标合理，是解决该类矿石难浸的理想方法。     

白山地区难选金矿石新方法选金试验研究

研究分析对比了不同类型选金矿石的特点，采用复合处理剂湿法预处理－提金新方法使吉林白山地区微细浸染型难选金矿石选金回收率由27％－57％提高到92％以上。