Copper–gold ore processing with ion exchange and SART technology

Anglo Asian Mining has developed a 50,000 oz Au/yr open pit gold mine at Gedabek in Western Azerbaijan. The deposit at Gedabek is a copper–gold porphyry, comprising both oxide and sulphide ore mineralisation, which is being mined at the rate of about 1 million tons of ore per year. Ore processing is by conventional cyanide heap leaching, which produces a pregnant leach solution (PLS) containing 1–2 ppm of gold, together with 1000 ppm or more of copper. The PLS is treated by column ion exchange, using Dow’s gold-selective MINIX resin. Loaded resin is stripped with an acidic thiourea solution, from which gold and silver are electrowon on to stainless steel mesh cathodes. Copper concentrations in the leach solutions are controlled by passing part of the PLS flow through a SART process, where the acronym stands for “Sulphidisation, Acidification, Recycling and Thickening”. The product from the SART process is a copper/silver sulphide precipitate, which is thickened, filtered and dried and then sold for copper smelting.     

Textural,mineralogical and chemical characteristics of copper reverb furnace smelter slag of the Okiep Copper District,South Africa

The Okiep Copper District in South Africa has produced more than 110 million tons at a grade of 1.71% Cu from several small mafic ore bodies. The ore was smelted on site and generated ∼5 mt of slag. During the life of mine attempts to recover copper from the slag by flotation had limited success. After mine closure the challenge of environmental rehabilitation and the possible disposal of the slag, triggered a reinvestigation into the viability of slag as a copper resource. Characterisation of the slag as a contribution to the potential copper recovery is the objective of this study.The slags are hard, vitreous with a matrix of Si–Fe–Al–Mg–Ca glass and laths of Mg–Fe–olivine, Fe–Mg–orthopyroxene and minor Cr-spinel. Copper grade varies between 0.11% and 0.42% with minor nickel, cobalt, molybdenum, zinc and tungsten. All economic elements are hosted by disseminated spheroidal prills which consist mainly of the copper sulphides bornite, chalcocite, covellite and chalcopyrite with exsolved sulphide phases of the minor base metals as well as rhenium and silver. Prills consisting of metallic copper and alloys are minor constituents. Prill diameter is highly variable with most in the 40–60 μm range and the historically poor copper recovery is attributed to the small prill size. Crushing of slag to −45 μm as opposed to the previous −75 μm should significantly increase sulphide liberation and recovery of copper and minor base metal sulphides by conventional flotation.Provided the operation is economically viable, redistribution of the processed slag to environmentally acceptable sites will resolve the present pollution and rehabilitation challenge related to the dumps in the Okiep Copper District. The operation will also have a positive socio-economic impact on this poverty-stricken part of South Africa.     

西藏多龙矿集区拿若铜(金)矿控矿因素与找矿方向

拿若铜矿是较为典型的斑岩型铜矿床,是多龙矿集区的重要组成部分,位于班公湖-怒江缝合带上。该矿床成矿母岩为花岗闪长斑岩,矿体产于花岗闪长斑岩体及蚀变长石石英砂岩中,大部分铜矿体由蚀变长石石英砂岩组成。该铜矿床中含有大量隐爆角砾岩,角砾为蚀变长石石英砂岩和少量岩体。拿若矿床发生过大量岩浆热液作用,岩浆岩主要以岩株和岩脉的形式产出,具有有力的成矿条件。主要的控矿因素有地层、构造和岩浆岩,矿区内的找矿标志较为显著,例如岩石、化探和围岩蚀变等。     

Effect of amine and starch dosages on the reverse cationic flotation of an iron ore

In iron ore concentration, reverse cationic flotation of quartz has been successfully employed for particles below 150 μm previously deslimed. Amine and starch are used, respectively, as quartz collector and iron oxides depressant. Understanding the mechanisms of reagents interaction is relevant to improve the separation selectivity, especially for high amine dosages. The term clathrate was used to explain this interaction, meaning a molecular compound in which molecules of one species occupy the empty spaces in the lattice of the other species, resulting in the depression of hydrophobic minerals. Laboratory scale experiments were carried out with itabirite iron ore in three different size ranges. The clathrate formation between molecules of amine and starch may explain the increase of SiO₂ content in the concentrates of the coarse size range (−150 + 45 μm) due to an increase in amine dosage.     

Effects of quartz addition on chalcopyrite bioleaching in shaking flasks

This paper studies the effects of quartz on bioleaching of chalcopyrite by Acidithiobacillus ferrooxidans, LD-1 through shaking flask experiments. The results showed that quartz concentration can affect the copper extraction. After 32 days, copper extraction of the leaching system at 50 g L⁻¹ quartz concentration increased by about 20%, compared with that of the leaching system without quartz. XRD analysis showed that the amounts of jarosite on the chalcopyrite surface may reduce by the mechanical friction action between fine particles of quartz and chalcopyrite. The analysis of SEM indicated that the surfaces of chalcopyrite particles were eroded by different degrees and the degrees of change were the same as the effects of quartz concentration on copper extraction.     

Investigating heap bioleaching: Effect of feed iron concentration on bioleaching performance

This paper describes an investigation into the effect of iron concentration in the leach solution on the bioleaching of a low grade copper ore, where chalcopyrite was the dominant copper sulphide. The concentration of dissolved iron is primarily controlled by pH and the relative proportion of ferric to ferrous iron, with significant jarosite precipitation occurring above pH ≈ 1.8 in a highly oxidised system. The solution pH may be increased by the dissolution of acid soluble gangue and when iron oxidation is significantly higher than sulphur oxidation. The study was approached using two experimental systems. In the former, the leach solution was recycled through an ore bed of low aspect (reactor height divided by diameter) ratio for a portion of the experiment. During the recycle phase, no acid was added to the system and acid consumption by gangue material led to a pH increase (1.6–2.2). The resulting jarosite precipitation reduced soluble iron from 2.5 g/l to less than 250 mg/l. Copper recovery decreased, but not in proportion to the decrease in iron. This was partly attributed to adsorption on, or entrainment within, the jarosites. To study the effect of reduced iron concentration on leach performance under more controlled conditions, bioleaching was performed in packed bed column reactors with feed iron concentrations ranging from 5 g/l to 200 mg/l. Observations indicated an initial decreased rate of copper liberation with reduced iron concentration in the feed. The relationship between available Fe³⁺ concentration and copper liberation was not proportional. However, with time, the liberation of copper became independent of iron concentration in the percolation liquor. Further, the specific rate of copper liberation was consistently below the theoretical value on a basis of ferric iron concentration. The highest values of copper liberation were reported at the lowest iron concentrations. In summary, while increased iron concentration in solution may enhance the initial rate of leaching, mineral availability appears to dominate CuFeS₂ leach kinetics through the majority of the leach. Furthermore, high iron concentrations in solution aggravate jarosite formation with concomitant retention of copper in the ore bed.     

Changes in an Australian laterite ore in the process of heat treatment

This paper examines an Australian garnieritic-type ore and changes in phase composition and morphology caused by heating in argon at 400–1000 °C using XRF, XRD, DTA/TG, SEM/EDS and BET analyses. The mineral phases detected by XRD in the original ore include chlorite, talc, hematite and quartz. Traces of iron silicate, Fe–Cr spinel and monoxide phase (predominantly manganese oxide) were observed by EDS. Nickel was detected in chlorite, talc, iron silicate and monoxide phase. Heat treatment at 400–500 °C did not change XRD patterns. At 600 °C, dehydroxylation of the brucitic phase of chlorite occurred. Chlorite was converted into olivine (forsterite) and enstatite at 600–800 °C. Upon heating to 900–1000 °C, talc was also converted into olivine and enstatite. Ni-bearing phases after heat treatment at 800–850 °C were forsterite, enstatite, talc, iron silicate and monoxide.     

Recovery of indium from sphalerite ore and flotation tailings by bioleaching and subsequent precipitation processes

Flotation tailings dump material of the former lead–zinc mine near Freiberg (Germany) consists of fine grained quartz, feldspar, mica as well as the sulphide minerals pyrite, galena and sphalerite not recovered by flotation. Sphalerite contains, aside from iron, copper and cadmium, significant amounts of indium (up to 0.38% (w/w)) leading to indium contents up to 70 mg/kg in the mine tailings. Preliminary thermodynamic assessment showed a comparatively small Eh–pH-range where bioleaching is possible and indium is not hydrolytically precipitated. Shake flask bioleaching of original polymetallic sphalerite ore from the Freiberg mining district (400 mg/kg indium) showed maximum zinc and indium recovery rates of almost 100% or 80%, respectively. First bioleaching tests on tailings material achieved zinc and indium yields of up to 80%. A stepwise precipitation process is being developed for indium recovery from the PLS (pregnant leaching solution) consisting of combined iron/indium precipitation and subsequent processing of the indium pre-precipitate.     

Research in quantitative mineralogy: Examples from diverse applications

Developed for the mining industry and applied to oil and gas projects, quantitative mineralogy also has enormous potential as a research tool. The Advanced Mineralogy Research Center at Colorado School of Mines was developed for this purpose, and several representative ongoing research projects using QEMSCAN^® techniques are described herein. Geomet applications relate mineralogy and geology to potential processing attributes such as hardness and grind characteristics. For kimberlite exploration and development, and diamond petrogenesis, quantitative mineralogy reveals the complex secondary silicate mineralogy in volcanic and mantle materials, and provides a means of viewing garnets from exploration samples. In Carlin-type gold deposits, the distribution of arsenian-pyrite can serve as a proxy for the distribution of gold. Monzonites from porphyry copper deposits reveal pervasive potassic alteration and quartz veining, which may impact the behavior of the materials during processing. A new view of feldspar zoning in granites not only has broad implications for understanding the petrogenetic evolution of magmatic systems, but is of relevance in processing feldspar-bearing materials. Environmental and biological applications include soil mineralogy, the effect of soil chemistry on vegetation, and studies of mammalian tissues. These examples illustrate how automated mineralogy allows researchers a means of quantifying mineralogical relationships in a wide variety of materials.     

The effect of seawater based media on copper dissolution from low-grade copper ore

Due to the scarcity of water in the north of Chile, there is interest in small-scale mining using seawater to leach the minerals. This situation has led to this research aimed to determine the effect of different process variables on the extraction of copper based on the ore type of these small-scale mining activities. The extraction of copper from finely ground (<150 μm) low-grade mixed ore (0.36% Cu) was studied in different acidic media (H₂SO₄ and HCl). The effects of water quality (tap water, seawater and synthetic process water) and lixiviants on copper leaching were investigated at three temperatures (25 °C, 35 °C and 45 °C). Synthetic process water was prepared by adding Na⁺, Cl⁻, Cu²⁺ and SO₄²⁻ to seawater. Copper extractions between 70% and 80% were achieved in 48 h using seawater, similar to the extractions obtained using tap water. Rapid copper dissolution occurred when synthetic process water was used, from 90% to 97%. This marked increase was related to the addition of Cu²⁺, which promoted the formation of CuCl⁺. Seawater was comparable to freshwater in terms of leaching kinetics and yield potential by raising the chloride concentration and increasing the formation of copper chloride ions. The findings of this study also expanded our understanding of the consequences of substituting seawater for freshwater at industrial leaching operations.     

Effect of water quality on the leaching of a low-grade copper sulfide ore

Copper extractions from a low-grade, ground copper sulfide ore (0.7% Cu) leached in three media were freshwater < seawater > double-strength seawater and pH 1.5 ⩾ pH 2; 84% extraction was achieved in pH 1.5 seawater in 28 days at 23 °C. Cu-oxide and carbonate dissolved completely and chalcocite was altered to secondary covellite, some of which persisted in all media for the duration of the 28-day experiment. Chalcopyrite and bornite were both oxidised more readily in saline water. Iron, sodium, potassium and sulfur (sulphate) concentrations in leach solutions diminished and the amounts of insoluble iron(III) reaction products increased with increased salinity and increased solution pH. While, overall, silicate dissolution was small, the amounts of poorly crystalline phases (both iron(III) and silica-rich phases) increased with increased salinity and were greater in pH 1.5 media. In the context of heap leaching, the increased amounts of secondary precipitates formed if saline water was used could result in lower extraction efficiency and the increased total dissolved solids, density and viscosity could result in increased energy costs for solution management at operations.The software package Geochemist’s Workbench was evaluated by modelling the synthetic seawater – pH 2 test. It was possible to predict the evolution of the solution composition, the main species and phase boundaries at the start and end of leaching, and the formation of three reaction products in accord with experimental data by applying the React sliding function.The tests were conducted using a pulverised ore sample to increase dissolution reaction kinetics, particularly for chalcopyrite. Future tests should be conducted using ore particle sizes appropriate to heap leaching. The copper distribution within particles indicated that the test ore may not be suited to heap leaching because the surface exposure of copper sulfide grains is limited. Therefore reactor designs better suited to smaller sized particles with/without pre-treatment should be considered.     

湖北省大冶市叶家庄矿区铜多金属矿成矿地质特征及下步找矿方向

叶家庄铜多金属矿区的矿体受阳新岩体石英正长闪长岩与碳酸盐岩围岩接触带控制,主要赋存于接触带矽卡岩和近接触带蚀变岩体中.矿床与燕山期石英正长闪长岩浆活动有紧密成因联系.石英正长闪长岩与碳酸盐岩接触带是寻找铜多金属矿的有利部位,矽卡岩化和硅化是重要的找矿标志.通过类比周边矿床认为,叶家庄矿区北西向接触带及深部有扩大矿床规模...     

Metal ions released from fluid inclusions of quartz associated with sulfides

The release of fluid inclusions has a strong potential for the unintentional activation of minerals during flotation. The present study aims to characterize fluid inclusions in natural quartz from a complex sulfide ore deposit. The results indicate that many fluid inclusions exist in the quartz. Under the experimental conditions of 2 g of quartz cleaned in 40 ml of pure deionized water under an inert atmosphere, the concentrations of Cu, Pb, Zn and Fe in aqueous solution reach concentrations of 1.92 × 10⁻⁷, 8.88 × 10⁻⁷, 8.31 × 10⁻⁷ and 90.33 × 10⁻⁷ mol/L, respectively. These values are significantly greater than those from the experimental non-oxidative dissolution of the quartz. In addition, the concentrations of metal ion released from fluid inclusions in the quartz sample at conditions approached “typical” industrial flotation environment are determined. The results indicate that the fluid inclusions of quartz represent the considerable sources of Cu, Pb, Zn and Fe in the aqueous solution. The present investigation provides a new understanding for the source of the unavoidable metal ions in the flotation pulp and may benefit understanding of the flotation theory.     

Possibilities for Co(III) dissolution from an oxidized ore through simultaneous bioleaching of pyrite

Solubilisation of Co(III) from a heterogenite met in copper cobaltiferous oxide ore has been realized through reductive leaching using ferrous iron generated via bio-oxidation of pyrite. Biotic and abiotic experiments at various pulp densities and redox potentials have been performed and results compared. Cobalt leaching at elevated redox potential is possible, offering cost reduction benefits due to reduced consumption of ferrous iron. At elevated potential of 625 mV, however, the initial rate of cobalt leaching has been found as 115 mg/(g ore)⋅(24 h), lower than the rate of 865 mg/(g ore)⋅(24 h) registered at 505 mV. Less stochiometric amount of ferrous iron was required when cobalt leaching was coupled to pyrite bioleaching, with 75% of cobalt recovered for 12 h at the optimally found conditions. It could be inferred that the Fe³⁺–Fe²⁺ cycle exists and is efficiently maintained through bacterial presence in the studied system.     

江玛—赛登地区铜多金属矿点地质特征及找矿前景

藏北阿里江玛—赛登地区铜多金属矿点位于班公湖—怒江成矿带西段,通过开展矿产调查工作在该地区发现了赛登铜矿点、江玛铜金矿点、江玛南铜银矿点。为明确区内下一步找矿方向和工作重点,首先对区域成矿背景进行了系统分析;然后分别从矿体形态及产出、矿物组合、矿石结构构造、控矿因素、围岩蚀变等方面总结了矿床地质特征;最后分析了成矿机理,初步建立了矿床模型,总结了区内地层、岩体、构造、蚀变等找矿标志,并对区内找矿前景进行了探讨。研究结果表明:1去申拉组地层对区内铜多金属矿化的控制作用十分明显,其中蚀变安山岩与成矿关系密切;2赛登铜矿化体主要产出于NW—SE向顺层产出的蚀变破碎带内,江玛南铜银矿化体受火山机构控制明显;3江玛铜金矿化、金矿化主要产出于蚀变安山岩和蚀变石英闪长玢岩中;4矿区剥蚀程度较小,矿床保存尚好,寻找斑岩型-浅成低温热液型矿床前景良好,下一步工作重点是被地表安山岩覆盖的深部含矿隐爆角砾岩筒及含矿玢岩体。     

Leaching of chalcopyrite (CuFeS2) with an imidazolium-based ionic liquid in the presence of chloride

The effects of independent variables such as, temperature, concentration of ionic liquid (1-butyl-3-methyl-imidazolium hydrogen sulphate, [bmim][HSO₄]), chloride and sulphuric acid on copper extraction from chalcopyrite (CuFeS₂) ore were studied by surface optimization methodology. The Central Composite Face approach and a quadratic model were applied to the experimental design. The optimal copper extraction conditions given by the above methodology were 20% (v/v) of [bmim][HSO₄] in water, 100 g L⁻¹ chloride, and 90 °C. The concentration of chloride and the temperature together exert a synergistic effect in enhancing chalcopyrite dissolution. Experimental data were fitted by multiple regression analysis to a quadratic equation and analyzed statistically. A model was developed for predicting copper extraction from CuFeS₂ ore with variables such as Cl⁻, [bmim][HSO₄], H₂SO₄ concentrations and temperature in the range studied. The activation energy was calculated to be 60.4 kJ/mol (temperature range 30–90 °C), indicative of chemical control of the reaction and [bmim][HSO₄] acts as an acid in the reaction.     

玉龙斑岩铜矿带北段ASTER遥感蚀变信息提取与优选

玉龙铜矿带是我国迄今已发现的最大的斑岩型铜(钼)矿带,发现了多个大型斑岩铜(钼)矿床。蚀变矿物是斑岩型铜矿重要的找矿标志,利用遥感数据可定量获取蚀变信息。论文选取玉龙铜矿带北段恒星错-玉龙-莽总一带为研究区,基于ASTER数据采用常用的比值法、主成分分析法提取的蚀变信息存在多解性,而采用波谱特征拟合的方法提取的蚀变信息具有综合性,结合矿床围岩、与中酸性岩体有关的环形构造和蚀变信息分布的环带特征,对提取结果进行优化和筛选,认为位于甲丕拉组、波里拉组地层、花岗斑岩岩体上,或位于环形构造周围,环带特征明显的围岩蚀变信息,指示矿产存在或成矿有利部位的可靠性更高。     

Stability of As(V)-sorbed schwertmannite under porphyry copper mine conditions

Arsenic (As), a very poisonous inorganic pollutant is a major toxicant in tailings of porphyry copper deposits. Retention of As by Schwertmannite (a ferric-oxyhydroxysulfate mineral) has attracted much attention in recent years due to its strong binding affinity to toxic As species. The stability of As(V)-sorbed schwertmannite under copper mine waste conditions is not fully understood. The present study investigates the effect of Cu²⁺, Fe²⁺, pH, and ageing time on the stability of As(V)-sorbed schwertmannite (Sch-As). The results indicate that Cu²⁺ has no significant effect on the stability of Sch-As and that the As(V) incorporated in schwertmannite can retard or significantly inhibit Fe²⁺-catalyzed transformation of schwertmannite to goethite under acidic conditions (pH 3–4). The Sch-As aged at different pHs from 3 to 11 at 25 °C exhibits no mineralogical phase changes even after ageing for 120-days; however the concentration of As released from the solid phase appears to be strongly pH-dependent even after ageing for only 24 h. The release of As was negligible at pHs from 2 to 7, and there was considerable release of As at extremely acidic and alkaline conditions. This indicates that the release of As from Sch-As was controlled by environmental factors such as pH, Cu²⁺, and Fe²⁺ rather than time.     

河北省承德某斑岩型铅锌矿床外围及深部找矿意义研究

老旧矿山外围及深部找矿已成为当前及今后一段时期地质找矿的重点,如何利用现有理论或结合实际工作成果来实现老旧矿山外围及深部找矿突破,亟待深度研究。对于河北省承德地区某斑岩型铅锌矿床 ,以往勘查工作集中在斑岩体本身及其与碳酸盐岩的接触带（矽卡岩型矿床）,忽略了外围构造裂隙内矿体及深部铜钼矿体的研究。近年来的地质勘查工作表明,该区铅锌银等元素地球化学异常发育,激电异常与控 制矿体延伸一致。钻探工作发现,斑岩体外围石英砂岩中分布有热液脉型铅锌银富矿体,深部存在铜钼矿体,岩芯原生晕样品分析显示该矿床矿化具有垂直分带性。通过对区域地质、矿区地质及矿体围岩蚀变、矿化 分带等特征的总结研究,并将这些特征与斑岩型矿床典型矿化分带模型进行对比,发现其与斑岩型矿床成矿系列特征一致,找矿潜力巨大,从而明确了该区外围寻找铅锌银矿,岩体内浅部寻找铅锌银矿、深部寻找铜 钼矿的找矿方向。在此基础上,结合物化探异常划定了2处找矿靶区,为预测该斑岩型铅锌多金属矿床外围及深部找矿前景和指导今后地质勘查工作提供了重要参考。     

Selective sulphidation and flotation of nickel from a nickeliferous laterite ore

The sulphidation of a nickeliferous lateritic ore was studied at temperatures between 450 and 1100 °C and for sulphur additions of 25–1000 kg of sulphur per tonne of ore. The experiments demonstrated that the nickel could be selectively sulphidized to form a nickel–iron sulphide. It was found that both the grade and the sulphidation degree largely depended upon the temperature and the sulphur additions, with temperatures above 550 °C exhibiting the highest nickel sulphidation degrees and grades. A DTA/TGA with mass spectrometer was used to further elucidate the nature of the phase transformations that occurred upon heating of the ore in the presence of sulphur.It was found that at low temperatures, the Fe–Ni–S phase was submicron in nature and heating to temperatures between 1050 and 1100 °C allowed for the growth of the particles, due to the increased sulphide mobility associated with the formation of a liquid sulphide matte phase, containing dissolved oxygen. Flotation studies conducted on 60 g samples showed that the sulphides responded to flotation with maximum grades of up to 6–7 wt.% nickel being achieved. Recoveries were approximately 50% on a sulphide basis and it was determined that the low nickel grades were due to the entrainment of magnetite fines.