Gold losses from cyanide solutions Part I: The influence of the silicate minerals

Shale material from Beatrix Gold Mine in South Africa has been found to be capable of adsorbing gold from cyanide solutions. Black shale bands occur in the reef zone at Beatrix Mine, but because of the mode of occurrence of the shale bands selective mining cannot be practised and ore delivered to the plant is contaminated by shale. Petrographical investigations and gold adsorption experiments were undertaken on samples of these shales, in an attempt to quantify their gold adsorption properties.Mineralogically the shales comprise muscovite, chlorite, pyrophyllite, and chloritoid which suggest that the shale is a low grade metamorphic rock. Gold adsorption experiments have shown that over time there is a drop in pH of the gold cyanide solutions. This is caused by decomposition of the phyllosilicates in the strongly alkaline solutions. Analysis of these solutions showed that high amounts of Si and Al are present. No Mg and Fe have been detected in the solutions which suggests that any dissolved Mg and Fe precipitate immediately on the surface of the solids so that gold can co-precipitate with colloidal Mg(OH)₂ and Fe(OH)₃. It was found that a tendency exists for high gold adsorption values to be preferentially related to high percentages of FeO (corrected for pyrite) + MgO + Al₂O₃ (corrected for muscovite) in the shales.     

The cyanide leaching of gold in solutions containing sulfide

A large proportion of the gold processed in the 21^st century will be recovered from sulfide ores. Since the sulfide minerals are to some extent soluble in cyanide solutions, there will always be some sulfur species present in the leach solution. It has been shown that soluble sulfide hinders the rate of gold leaching, forming a protective layer of the type Au/S_x. Electrochemical studies of the constituent half reactions: gold oxidation; and oxygen reduction, were consistent with this view. The effect of sulfide and cyanide concentrations on the leaching reaction were investigated, and it was shown that the sulfur formed is chemically attacked by cyanide, resulting in higher leach rates at higher cyanide concentrations. The effect of lead was also studied and is discussed in detail.     

The characterisation and behaviour of carbonaceous material in a refractory gold bearing ore

Sulfide ore and a flotation concentrate from Fosterville contained 0.76% carbonate carbon, 0.18% native carbon and 0.20% organic carbon of which 4.5 ppm were n-alkane hydrocarbons. The concentrate yielded 0.99% native carbon, 0.28% carbonate carbon and 0.11 % organic carbon of which 19.7 ppm was n-alkane hydrocarbons. IR spectroscopy of the fulvic acid fraction of the flotation concentrate showed it to be similar to humic acid.The addition of representative levels of n-alkane hydrocarbons, carbonate carbon and humic acid to the oxidised ore indicated that these components had negligible effect on gold recovery. The addition of 0.2% native carbon decreased gold recoveries from 84.4% to 68.8% while 0.2% activated carbon reduced recovery to 3.1%. Native carbon when acidified, mimicking the environment of bacterial oxidation, resulted in recovery dropping from 84.4% to 61.0%.Gold recovery for a standard sulfide float was 92.5%. Sodium naphthalene sulfonate (SNS) was the only depressant to lower native carbon levels in the concentrates without reducing gold recovery. 275 g/t SNS depressed 45% of the native carbon and gold recovery was unchanged. Nitric acid oxidation and subsequent cyanidation of the SNS concentrates lead to overall gold recovery improving from 88.3% for a standard sulfide float to 92.0%.     

土酸对页岩溶蚀率影响的试验研究

利用X射线衍射晶体鉴定技术,首先确定页岩试样主要矿物成分,根据矿物成分确定酸化试验所用的酸液。利用质量分数为3%的HF和10%的HCL混合而成的土酸溶液酸化20mm×20mm×50mm的块状的钠长石、石英试样。利用超景深三维显微系统初步分析试样表面的腐蚀程度,并用Image-Pro Plus计算表面积溶蚀率的变化以及测量pH的变化规律,以分析页岩酸化的机理。设置对比实验,确定HF和HCL分别对溶液的贡献。本文是酸化压裂对含气页岩渗透性能的影响的基础室内试验研究,研究成果可以为实际工程应用提供理论依据。     

青海某难选冶金矿提金工艺试验研究

青海某金矿为中硫、含砷和碳的微细粒难选冶金矿。在查明矿石物质组成的基础上，对矿石进行了选矿方法、工艺条件及流程方案试验研究，确定采用浮选—重选—精矿焙烧—氰化浸出提金工艺，获得了满意的技术经济指标。该成果已被建厂设计采用，建成投产后经济效益较好。     

Cyanide recovery in hydrometallurgical plants: use of synthetic solutions constituted by metallic cyanide complexes

Cyanide compounds are widely used in gold ore processing plants in order to facilitate the extraction and subsequent concentration of the precious metal. Owing to the high cyanide concentrations employed in gold processing, effluents generated have high contents of free cyanide as well as metallic cyanide complexes, which lend them a high degree of toxicity. The process under study, developed in laboratory scale with the use of a distillation apparatus, consists of highly decreasing the pH of the solution by adding sulfuric acid. Thus, the cyanide present in either free form or as a metallic complex is made volatile and the resulting cyanide gas is absorbed in an alkaline solution for reutilization. This work aims at recognizing the chemical relations between the cyanide and metals during distillation. The regeneration of cyanide from gold processing proved to be a viable procedure. Cyanide recoveries pointed to the fact that if a method for reutilization of cyanide contained in mining effluents is employed, the precious metal processing will become more efficient. Also, the environmental conditions in the area of the operation will be improved.     

Solvent extraction of gold(I) from alkaline cyanide solutions by the cetylpyridinium bromide/tributylphosphate system

This paper explores the solvent extraction of KAu(CN)₂ from alkaline cyanide solutions using quaternary ammonium cetylpyridinium bromide (CPB) as an extractant with the addition of tributylphosphate (TBP) as a modifier. It also investigates the influence of several variables on gold extraction, including the molar ratio (β) of CPB to Au(I), the volume percentage of TBP (φ_TBP), NaCl concentration, phase ratio (AQ/ORG), and gold concentration in the aqueous phase. The results indicate that nearly all of the Au(I) (>98%) was transferred from the aqueous phase into the organic phase when β = 1 and φ_TBP = 30 vol%. We also carried out experiments for treating 20 L synthetic aurocyanide solution containing 10 mg/L Au(I) with column-shaped extraction equipment. The results demonstrated the recovery of more than 94.5% of Au(I) after two successive stages of extraction, and the Au(I) concentration in the raffinate was less than 0.5 mg/L. KSCN solution was used to strip the gold-loaded organic phase, and about 90% of Au(I) could be reverse extracted into the aqueous phase when the KSCN concentration reached 3.0 mol/L. The results obtained in this paper establish that the CPB/TBP extraction system has potential for practical application in the extraction and separation of gold from alkaline aurocyanide solutions.     

射孔对页岩水力裂缝形态影响的物理模拟实验

通过XRD、扫描电镜及力学强度测试等实验对龙马溪组页岩的物理力学性质进行分析,并采用真三轴压裂改造模拟器开展水平井水力压裂物理模拟实验,探究射孔参数及页岩物理力学性质对裂缝形态的影响规律。实验结果表明:(1)具有3种不同射孔类型的试样,在压裂后主要形成4种水力裂缝的形态模式,其中组合型射孔对于复杂裂缝的形成具有一定的促进作用。当射孔间相位角和间距过小时,缝间应力干扰增大,不利于扩大裂缝规模。(2)试样在压裂过程中的泵压-时间曲线,会因射孔类型的不同而呈现出明显的差异,曲线的波动程度和裂缝的复杂程度呈一定的正相关。(3)水力裂缝在延伸过程中与结构面相交时出现的穿透、分叉等现象是形成裂缝网络的前提。各向异性、微裂缝和微孔隙、脆性指数等页岩的物理力学性质会影响裂缝的扩展路径和迂曲度。     

The effect of zinc cyanide on the flotation of gold from pyritic ore

In gold processing plants, the process water contains a considerable amount of weak acid dissociable (WAD) cyanide species. The cyanide-containing water recycled to flotation circuits has a deleterious effect on mineral flotation. Zinc cyanide can be a major constituent of the process water due to the cyanide leaching of zinc minerals and the zinc cementation applied to precipitate gold and silver. In the present study, the effect of zinc cyanide on the flotation of gold from a pyritic ore was evaluated and the competitive adsorption between zinc cyanide species and the collector, potassium amyl xanthate (PAX) or Aerophine promoter (3418A), on gold was studied by surface enhanced Raman spectroscopy (SERS). It was found that free cyanide did not depress the flotation of liberated gold, but zinc cyanide with a CN/Zn ratio of 2 did. The depression of gold flotation by zinc cyanide was due to the preferential adsorption of Zn(CN)₂ on gold surface over either 3418A or amyl xanthate in the solution, rendering gold surface hydrophilic.     

预热器废气中窑灰对生料率值的影响

对新型干法水泥生产系统预热器废气中的窑灰和生料的化学成分进行了分析,研究了窑尾废气中的窑灰对生料率值的影响.结果表明,在原料磨不同的运行情况下,窑灰对生料率值的影响程度不同,在原料磨产量大幅降低或停产时,出磨生料率值应进行调整,以保持熟料率值的稳定.     

长宁地区五峰组底界微断裂识别及对页岩气开发工程的影响

四川盆地长宁页岩气田是中国页岩气勘探的先导靶区之一。受地震分辨率的限制,前人主要识别断距大于20m的断层,会忽略断距小于20m的微小断裂,然而长宁地区普遍发育断距小于20m的微小断裂,容易造成其长水平井开发中出层、卡钻、压窜、套变等复杂工程情况,因此,如何进行长宁页岩气储层微小裂缝的识别,并进一步细化断裂分级成为了当前工作的重中之重。本研究在前人的断裂解释认识上,通过井震结合,综合运用相干、蚂蚁体等多种方法,提高了微小断层的识别和刻画精度,总结了继承型、伴生型、走滑型三种微裂缝成因分类,并在原有的四级分类基础上增加了第五级断裂（微断裂）的分类原则和识别方法。结果显示,该区发育大量走向北东向、北西向的微断裂,与I-IV级断裂的方位一致,符合成因规律,且能够匹配解释前期钻井、压裂过程中出现的工程问题,证实了微断裂识别方法的可靠性和微断裂对页岩气开发工程的不利影响。通过对微裂缝的有效识别,可以为轨迹优化、钻井及压裂施工提供预警处理依据,并为地质甜点分析、页岩气产量提升提供技术支持和保障。     

A kinetic and electrochemical study of the ammonia cyanide process for leaching gold in solutions containing copper

One of the biggest challenges for the gold industry in the 21st century is the presence of copper in gold containing ore bodies. This is because copper consumes large quantities of cyanide. In addition, copper cyanide species are more stable than free cyanide, and hence are problematic in events of tailings spillage. One of the methods which has been suggested for treating copper containing ores is to leach with an ammonia cyanide solution. The effect of copper and ammonia addition on gold leaching kinetics was studied in the present paper. It will be shown that when the solutions do not contain copper, the addition of ammonia decreases the rate of gold leaching. When copper is added to solution, the leach rate does decrease due to the formation of the copper cyanide complexes. However it will be shown that under conditions of zero free cyanide, gold does leach readily via the Cu(CN)₃²⁻ complex. It was found that the addition of ammonia had little effect on the leaching of gold by Cu(CN)₃²⁻, but did increase the leaching kinetics when the major cyanide species present is Cu(CN)₂⁻. Under these conditions, leaching in the absence of ammonia is very slow. The effect of copper(II) addition was also studied, and it was found that in the absence of free cyanide the presence of copper(II) increases the leach rate, provided there is enough ammonia to stabilise it against reaction with the copper(I) cyanide complexes.     

被动围压下层理角度对页岩动态强度及耗能的影响

页岩在围压条件下的动力学特性,对页岩的高效致裂至关重要.采用分离式霍普金森压杆(SHPB)系统对页岩进行冲击试验,分析被动围压条件下页岩试件的强度特征、损伤特性和能量耗散规律.试验结果表明:在不同应变率下,页岩的损伤程度随冲击速度的提高显著提高,试件承载能力降低;在被动围压条件下,岩石材料的延性和抗破坏能力均得到提高,...     

由中国稀土贸易现状而引发的战略思考

本文通过对中国稀土产业的生产与消费关系，生产量与出口量变化具体数据的分析，探讨了中国稀土产业结构，出口量增长以及稀土出口产品价格下降等问题，进而提出中国应尽快建立起一个适应加入WTO的非传统产业经济新模式，新的，非传统模式对于中国稀土产业实行可持续发展战略的运行体制，推进稀土行业中企业改革的深化，理顺出口渠道，加快稀土矿产品在高新技术产业中应用的进程等方面进行了进一步分析和讨论。     

油页岩原位开采井距影响数值模拟研究

近年来,随着我国能源消费水平的提高,油气资源进口量逐年上升,寻找替代能源逐渐受到世界各国关注。油页岩是一种重要的石油替代能源,其储量巨大,分布广泛,开采前景广阔。地下原位转化开采油页岩具有低污染、占地面积小的优点。本文采用CMG-STARS数值模拟软件建立油页岩地下原位开采模型,通过原位注入热蒸汽法模拟了油页岩地下原位转化过程中的产油动态,并分析不同井距对开采的影响。结果表明,井距对油页岩开采有重要影响,井距越大,油页岩长期开采效果越好,但短期开采效果越差。最后对井距进行敏感性分析,结果表明井距40 m左右时产油效果最好。     

五峰组—龙马溪组储层特征及甜点层段评价——以昭通页岩气示范区A井为例

以昭通页岩气示范区A井五峰组—龙马溪组一段页岩为主要研究对象,利用薄片、氩离子抛光-场发射电镜、核磁共振、液氮吸附、X衍射及地化分析等多种测试手段,从岩石学、有机地化、矿物组成、孔隙类型及结构、物性特征及含气性等方面,系统评价了五峰组—龙一段各小层储层特征,并优选了页岩地质与工程甜点层段。结果表明:五峰组—龙一段以硅质页岩为主,优质页岩主要形成于海侵期-海退早期的深水陆棚相贫氧-厌氧环境;有机质孔和黏土矿物层间粒内孔最为发育;五峰组—龙一段储层孔隙以中孔为主,微孔对比表面贡献最大,而中孔和微孔提供了主要的孔体积;龙一11—龙一21小层相对其他层段,具有相对高的TOC含量、孔隙度、含气量及压力系数,且各项指标具有向上减小或降低的趋势。同时,龙一11—龙一21小层具有高脆性指数、高杨氏模量、低泊松比的岩石力学特征;基于地质与工程综合评价,优选龙一11—龙一21小层即富碳高硅页岩段为纵向上甜点层段,为昭通页岩气示范区水平井的靶体层段。     

烧结温度对掺杂CZTSe靶材性能的影响

采用真空烧结技术制备了RbF∶CuZnSnSe(Rb-CZTSe)的陶瓷靶材,当RbF掺杂量为0.4%(质量分数)时,研究了不同烧结温度对CZTSe陶瓷靶材微观结构、致密度、电阻率及断面形貌的影响.结果表明,当烧结温度在660℃下所制备的陶瓷靶材表现出最优的各项性能,其电阻率188 kΩ·cm和相对密度为94.68%.表明此方法所制备的Rb-CZTSe陶瓷靶材能更好的应用于工业生产.     

川南地区下古生界页岩气储层微观孔隙结构表征及其对含气性的影响

运用普通扫描电镜、氩离子抛光—场发射扫描电镜、Image J2x软件分析、高压压汞、低温CO_2和N_2吸附实验方法,对川南地区下寒武统筇竹寺组和下志留统龙马溪组两套页岩气储层微观孔隙成因类型、孔隙结构特征及其对页岩含气性的影响进行了研究。结果表明,川南地区下古生界页岩微观孔隙主要发育粒间孔、粒内孔、有机质孔和微裂缝等多种成因孔隙类型;下古生界页岩微观孔隙总面孔率为3.95%~7.48%,筇竹寺组页岩总面孔率和有机质孔面孔率低于龙马溪组页岩;下古生界页岩总孔容为(3.93~24.96)×10~(-3)m L/g,总比表面积为2.727~29.399 m~2/g,孔径为0.35~1.00,2.5~4.7和55~75 nm的孔隙是总孔容的主要贡献者,孔径为0.3~1.0,2.5~5.5 nm的孔隙主要提供了总比表面积,筇竹寺组页岩总孔容和总比表面积均较龙马溪组页岩要低;页岩微观孔隙的面孔率、有机质孔、孔容、比表面积、孔径分布均会影响页岩含气性。下古生界筇竹寺组和龙马溪组页岩在微观孔隙结构特征的上述差异,为揭示川南地区筇竹寺组与龙马溪组页岩含气性的差异提供了依据。     

Analysis of the mechanical property of mudstone/shale in paralic coal measures and its influence factors

The mechanical property of mudstone/shale in coal measures is a key factor of engineering mechanics that influences the development of shale gas. A rock mechanics test was performed in order to analyze the complete stress-strain mechanic characteristics and influence factors of mudstone/shale in paralic coal measures, from the Carboniferous-Permian periods in a coal field of Northern China. The relationship between the mechanical properties of mudstone/shale in coal measures, and its chemical component, water content are established, and their models are constructed. Research results show that mudstone/shale has low mechanical strength, low elastic modulus and a high Poisson’s ratio. The complete stress-strain curve has apparent elastoplastic deformation characteristics, and after reaching peak strength, it exhibits obvious strain softening characteristics. The uniaxial compressive strength of mudstone/shale and its elastic modulus increases exponentially with the increase of SiO₂ content, and as the ignition loss increases, the uniaxial compressive strength and elastic modulus of mudstone/shale will decrease according to the law of power function. The compressive strength of mudstone/shale and its elastic modulus will decrease with the increase of water content in mudstone/shale.     

中国页岩气勘查投入的成本问题研究

中国页岩气勘查开发成果显著,截至2015年底,页岩气累计产量超过60亿m3,成为全球第三大页岩气生产国,与此同时,勘查投入成本高,降低了中国页岩气勘查开发的社会和经济效益。通过对页岩气勘查投入核算理论的梳理,定义中国页岩气勘查投入成本概念,理清投入核算范围和构成,分析区域地质调查、地震采集及处理、钻探等不同技术手段的成本单价,对比美国页岩气、中国石油和天然气勘查成本,讨论中国页岩气成本高的主要原因,针对政策和技术造成中国页岩气勘查成本高的现状,建议政府出台页岩气勘查投入标准的规范政策,加大财政补贴力度的激励政策,鼓励企业投资页岩气钻探技术。