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By O. Celep, H. Deveci, Ersin Y. Yazici, F. Ahlatci

"There are increasingly stricter environmental regulations imposed for use of cyanide leaching for the extraction of gold from ores. Alternative lixiviants to cyanide, preferably with low toxicity, have been extensively studied. Thiosulphate has emerged as one of the most suitable alternative leaching agent in place of cyanide due to its low toxicity and technical attributes e.g. fast leaching kinetics, high gold extractions from carbonaceous ores in particular. High solubility of most copper minerals in cyanide solutions results in low gold extractions due to excessively high consumption of cyanide. In contrast, low reactivity of copper minerals in thiosulphate solutions makes thiosulphate leaching potentially suitable alternative for treatment Cu-bearing gold ores. The extraction of gold/silver from a copper-bearing pyritic gold concentrate (62 g/t Au, 110 g/t Ag and 0.3% Cu) in thiosulphate solutions was investigated in this study. The concentrate is composed of predominantly quartz (25%) and pyrite (32.7%) as well as sphalerite (5.37%), galena (2.12%) and anglesite (1.13%). Other minor minerals are arsenopyrite, chalcopyrite, covellite and bournonite. Previous studies by the authors indicated that the concentrate did not respond well to cyanide leaching (i.e. 45-46% Au/Ag at 1 g/L NaCN). The effects of concentration of ammonia (0.2-1.5 M NH3), thiosulphate (0.1-0.75 M S2O3) and copper (0-20 mM CuSO4) on the extraction of gold and silver over 8 h. was investigated. Increasing the concentration of thiosulphate and ammonia substantially improved the rate and extent of gold leaching while high copper levels produced an adverse effect particularly at low concentration of thiosulphate (i.e. 0.1 M). Complete extraction of gold was achieved under suitable conditions. In contrast to gold, silver extractions remained consistently at low levels (i.e. 28%). These findings demonstrated that thiosulphate leaching could be used to achieve acceptable levels of gold extraction from the copper-bearing pyritic gold concentrate."

Jan 1, 2018

By Zofia Swierczek

This paper reports the results of a detailed mineralogical study of typical, low-grade Australian nickel laterite run-of-mine ores. Successful development of an effective beneficiation process for upgrading such low grade laterite ores relies on good knowledge of the laterite mineralogy and the value metal(s)? distribution characteristics. Both QEMSCAN and quantitative X-ray diffraction techniques were used to conduct the mineralogical analysis of three types of laterite ores, and the results were compared with those obtained by chemical analysis. Some of the major challenges faced included accounting for the mismatch between the nickel values measured by QEMSCAN and those recorded by chemical analysis. This was primarily due to the relatively low concentration of nickel in the ores and its wide dissemination among several major host minerals in complex association. Careful analysis showed that the limit of nickel detection in iron oxide host mineral grains under normal operating conditions was around 4%. Keywords: nickel laterites, mineralogy, characterisation, QXRD, QEMSCAN

Sep 1, 2012

By Hamid-Reza Manouchehri

"The triboelectric charge attributes of feldspar, quartz and wollastonite minerals, after contacting different triboecharging medium made of different materials, were considered. Their charge acquisitions by different size fractions of minerals were monitored and accordingly their energetic work function values were estimated. Moreover the separation behaviours of these minerals through the electric field of a laboratory free falling separator were determined and the effects of some chemical reagents on separation their separation characteristics were studied.Finally an attempt was made to translate the findings from single mineral systems to a complex silicate ore, containing quartz, feldspars, wollastonite and some other silicates. The results show favourable prospect to apply the triboelectric separation technique for beneficiation such a complex raw material."

Jan 1, 2003

By Alexsandro Berger

Many thickener operations continue to be constrained by their ability to process consolidated underflows with high yield stress and associated rheological characteristics. To maximise separation efficiencies within a thickener operation the use of both engineering and reagents are always considered. BASF is developing a Novel Flocculant Technology (NFT), which combines both of these aspects to enhance the performance of the thickener operation, improving the areas of pumping efficiency, underflow density and throughput. The development progression through stages of laboratory scale batch test work to pilot scale dynamic testing has demonstrated the ability of BASF NFT to maintain effective flocculation performance whilst increasing the rate of underflow consolidation, and significantly reducing the associated underflow yield stress of the treated material. This paper will present application data through full scale dynamic testing conducted on a granite washing circuit to demonstrate the performance benefits that NFT offers to a thickener operation. Compared to the conventional flocculant treatment, within the operation parameters and conditions employed during the full scale trials, the NFT produced a reduction in underflow rheology (yield stress) of around 45 % relative to a given solids and improved the underflow consolidation by providing at least 20% relative higher underflow solids loading than the upper limit of the given typical thickener operation. Keywords: flocculation, thickener operation, rheology, yield stress, underflow density, throughput, slump test

Sep 1, 2012

By Z. Pokrajcic

The traditional comminution circuit is a major consumer of energy ? both as electrical energy and through consumption of media and wear resistant liners. Up to 40% of electrical energy con-sumed at a mine site is attributed to comminution however only a few percent of this energy is used in the generation of new surfaces from size reduction. This paper describes the evaluation of modifications using simulation models based on two operating comminution circuits. The aim of these modifications is to decrease both the amount of electrical energy consumed in the size reduction process, known as direct energy, as well as to decrease the consumption of grinding consumables such as steel grinding media and mill liners, designated as indirect energy. The approach is two-fold: ??Employ, where possible, autogenous grinding techniques to eliminate the need for grinding media and reduce mill liner wear. ??Optimise the use of the grinding energy distribution in the comminution circuit by using more energy efficient grinding devices to target typically problematic features of a comminution circuit such as critical size material from the primary mill and overgrinding in the secondary mill. The investigations show that significant total energy savings, as high as 50% in some cases, can be achieved by employing the techniques described while maintaining circuit throughput and product size. Investigations also show potential benefits in downstream flotation processes as the product size distribution generated from the eco-efficient circuit is generally ?narrower? in shape for improved flotation performance and containing less material in the coarse fraction for overall better liberation.

Jan 1, 2014

By B. J. Zhang

Conventional spirals are capable of providing excellent clean coal recovery, although at a relatively high ash content. Compound spirals, which provide two stages of spiral cleaning in a single taller unit, have been commercialized in recent years to improve upon the cleaning performance obtained from conventional spirals. The present study aimed at optimizing the performance obtained from a compound spiral for cleaning especially high sulfur fine and ultrafine coal. Industrial-scale spiral units were utilized for this study in a pilot-scale facility at the Illinois Coal Development Park. A statistically designed experimental program was conducted to optimize ash and sulfur cleaning performance of the compound spiral. It was found that significant cleaning of ultrafine coal (i.e., 150 microns × 45 microns and even 45 microns × 25 microns size coal) is achievable with the compound spiral. However, operating conditions for cleaning finer coal fractions (-150 microns size coal) have to be significantly different from those used to clean coarser coal fractions (+150 microns size coal). The sulfur rejection trends were different from ash separation efficiency trends in all size fractions except 45 microns × 25 microns. The probable error (Ep) and effective specific gravity of separation (SG50c) determined for the compound spiral cleaning of the overall particle size were as low as 0.07 and 1.62, respectively. However, the bypass of a small percentage of clean coal to the tailings stream of the compound spiral, may need further adjustment of the key process parameters.

Jan 1, 2014

By Sanjay Agarwal

Polymetallic sea nodule is a good source of manganese having 22.3% Mn, 5.4% Fe, 6.14% Si, 1.1% Cu, 1.15% Ni, 0.076% Co & others. These nodules are available in plenty on the sea beds, generated over thousands of years. Nodules mainly consist of manganese dioxide and iron oxide phases and other metals are entrapped in the complex cage of these Mn-Fe oxides phases.World-wide research is going on sea nodules as an alternative future source of many metals, which has led to intensified efforts to develop practical and economical processes for recovery of these metals. Very little attempt has been made world over on manganese extraction from sea nodules. We at CSIR-NML, India have developed a direct reduction smelting process of nodules to recover manganese as Fe-Si-Mn alloy. This alloy is extensively used in the steel industry as deoxidizer and as an alloying element to make different grades of steel. Lab scale experiments were conducted to study the manganese distribution between Fe-Si-Mn alloy and FeO-SiO2-MnO-CaO-Al2O3-MgO slag at different temperatures by varying the basicity of the slag. The direct reduction smelting of nodules is carried out on 1 kg scale in 50 kVA electric arc furnaces to have Cu, Ni and Co alloy and Mn rich slag. This manganese rich slag is further treated in 50 kVA arc furnace to produce Fe-Si-Mn alloy. The composition of Fe-Si-Mn alloy obtained is in the range of Mn: 60-65%, Si: 14-17%, C: 1- 2%, S: 0.03% and the balance iron which is acceptable grade for industrial use. The equilibrium amount of MnO in the final slag is controlled by the temperature of the final melt and the silica, lime, alumina content of the final slag. Increasing the basicity of the slag plays a major role in minimizing the loss of MnO to slag, increasing the amount of SiO2 of the slag, increases the manganese loss in the slag. Increasing the CaO/ Al2O3 ratio of the slag decreases the manganese loss in the slag. Increasing the MgO/CaO ratio of the slag increases the manganese loss in the slag. Thus by adjusting

Sep 1, 2012

By I. A. Khabarova

The paper presents the results of experimental investigations of the effect by high-power nano-second electromagnetic pulses (HPEMP) on change of surface composition, physical-chemical and flotation properties of pyrrhotite, and search of optimal combination of flotation reactants providing increase of metal extraction from disseminated copper-nickel ores. Preliminary electropulse effect on products before flotation allows to create optimal conditions for flotation separation of pentlandite and pyrrhotite owing to forming the new phases and defects on the surface of sulphides. It was established, that the yield of monomineral fractions of pyrite, pyrrhotite and chalkopyrite increases by 5%~15 %, compared with flotation with one butyl xanthenes (BX), during usage of combination of thionic carbamate (isopropylmethylthionocarbamate (ITC) or isopropylethyl- thionocarbamate (Z-200) with butyl xanthate (BX). Sorption of investigated reactants and strength of their fixing on the surface of minerals are examined; it helped to reveal the cause of rise of floatability of sulphide minerals for the case of combination of reactants. Preliminary high-pulse processing and reactant conditions with usage of combination of thionic carbamate and xanthate have been tested on the sample of disseminated copper-nickel ore from Norilsk region.

Jan 1, 2014

By X. G. Liu

Bentonite is an excellent sealant mineral material because of its desirable swelling and self-healing characteristics, low permeability, sorptive qualities, and longevity in nature. A new type of water-swelling building sealant made from bentonite was studied in this paper. The building sealant is prepared by Na-base bentonite, vaseline and paraffin wax under different mass fraction of bentonite (which is 60%,65%,70% respectively). Under unrestricted state, some properties of samples were investigated. The volume expansion ratio at 24 h is 211%, 222%, 256% , and permeability coefficient is 2.86×10-8 cm/s, 4.15×10-8 cm/s and 4.78×10-8 cm/s respectively; low temperature flexibility of the sample (bentonite quality is 65%, 70% respectively) is good, and it does not flow heated for 2 h under 80?. The results of XRD and SEM indicate that bentonite is coated preferably by vaseline, and the spacing of layers of bentonite do not changed. The sample can keep full water swelling ability, and has good molding process. The test results prove that the properties of samples may reach the standard of building sealant.

Jan 1, 2014

By M. Z. He

Attractive particle interactions which underpin the sliming of gangue mineral particles onto valuable mineral phases are encountered in a number of flotation circuits. Sliming leads to poor flotation recovery of the valuable minerals and high recovery of the gangue particles in the concentrate. To mitigate sliming, low molecular weight poly-electrolytes are commonly used as dispersants during pulp conditioning prior to flotation separation of the valuable and gangue mineral phases. In the present work, the sliming mechanism of sericite onto chalcocite and the influence of interfacial chemistry and two anionic copolymer dispersants (carboxylate substituted polyacrylamide, polymer Cyquest 3223 and sulfonate substituted polymaleic acid, polymer P80) on the sliming interactions were probed in the pH range 5~9. It was shown that the sliming occurred under solution conditions where both chalcocite and sericite particles were negatively charged, as evidenced by their apparent particle zeta potentials. The suspension pH had a profound effect on sliming process as the extent was markedly greater at lower than higher pH. The sliming was found to be due to the chalcocite dissolution, Cu (I) release and oxidation to Cu (II), followed by hydrolysis and specific adsorption, leading to sericite particle surface charge reversal and the formation of electropositive sites on chalcocite surface in the pH range 5~9. Addition of polymer Cyquest 3223 or P80 not only increased the magnitude of zeta potentials of both sericite and chalcocite particles but also reduced the formation of Cu (II) ions and complexes, which mitigated the sliming behaviour. The adsorption of polymer Cyquest 3223 or P80 at 3 g polymer / kg solid or more had a significant impact on the zeta potentials of both sericite and chalcocite particles. Sericite-chalcocite particulate adsorption studies showed that sliming was completely suppressed via an electro-steric repulsion mechanism resulting from anionic polymeric dispersant adsorption at dosages > 3 g polymer / kg solid.

Jan 1, 2014

By Ö. Genç

In this paper, full-scale mill data collected from three different circuit configurations in cement plants demonstrated the size reduction performance of dry ball mills in relation with the ball size classification achieved by the classifying liners used in the grinding compartments. Findings indicated that, breakage rates at the last 2 ~ 4 meters of the mill are not sufficient to give reasonable size reduction ratios for the production of fines. Application of only damming rings without classifying liners resulted in inverse ball size classification which lead to reduction in size reduction performance thus specific breakage rates.

Jan 1, 2014

By A. Deepatana

This study compares the use of an aminophosphonate chelating resin Purolite S950 and a sulphonic acid strong cation exchange resin Purolite C160H to recover nickel and cobalt from the synthetic bioleach solutions. Batch adsorption of metal citrate is performed as a function of metal citrate concentration (15~2000 mg/L) and solution pH (0.01M and 0.1M citric acid). The adsorption mechanism as inferred from the fit to Langmuir (LM), Freundlich (FM) and Redlich-Peterson (RP) models demonstrates that nickel citrate adsorbed onto C160H appears monolayer in comparison to that adsorbed onto S950 exists multilayer. In contrast, cobalt citrate adsorption onto both C160H and S950 agrees with the LM model. The results have shown that loading capacities of nickel and cobalt citrate onto C160H are 60 and 65 mg/g whereas those observed onto S950 are 16mg/g and 6 mg/g respectively. These are achieved in metal citrate prepared in 0.1 M citric acid. Resin regeneration is conducted in using 2 M nitric acid solution. The results show high efficiency of nickel and cobalt citrate elution from Purolite C160H. Findings from this study suggest Purolite C160H is a suitable adsorbent for recovering nickel and cobalt from bioleaching solutions.

Jan 1, 2014

By V. A. Luganov

The processing of pyrite concentrates may be accomplished with a preliminary enrichment due to withdrawal of iron sulfides from initial concentrate. The withdrawal of iron sulfides is possible with the help of magnetic separation when the magnetic iron sulfides (pyrrhotites) separate from non-magnetic fraction?the sulfides of non-ferrous metals. The conversion of non-magnetic pyrite to magnetic pyrrhotites of adjusted structure occurs because of roasting with the withdrawal a part of sulfur. The resultant pyrrhotites are strong ferromagnetic with hexagonal structure. This paper contains results of studying magnetic properties of pyrrhotites, findings of the de-composition of initial pyrite with the consequence homogenizing of product and hardening of product of decomposition in liquid nitrogen. Define the type of pyrrhotites super lattice structure, was established that at increasing of sulfur contention the magnetic properties of pyrrhotites are change ? pyrrhotite begin evince the properties of antiferromagnetic material and magnetic susceptibility of material is interruptive changing from 0 to 1.7×10-3~1.9×10-3 SI units/g system. The paper contains results of technological researching of pyrrhotizing-magnetizing roasting of pyrite concentrates in different condition: in unoxidizing, with the decreasing contention of oxygen and in autogenous regime in air atmosphere. Established that the magnetic susceptibility of products depend of pyrite degree dissociation and achieve 2×10-3~3×10-3 SI units/g system at 40%~45% desulphurization. Defined the conditions of steady regime autogenous roasting, at resultant products possess coefficient of magnetization, and this can be used magnetic separation for separating ferromagnetic pyrrhotites from gangues and non-magnetic sulfides of non-ferrous metals. This technology of pyrrhotizing roasting is recommended for effecting in industrial condition. The initial materials and products of roasting subjected to chemical, thermogravimetric, Moss-bauer spectroscopy and X-ray analysis, defined the magnetic properties.

Jan 1, 2014

By E. Lee

With the growing environmental concern, as well as the increasing concern for sustainability of natural resources, the need of improving the performance and efficiency of today?s crushers is be-coming increasingly important. However, the development of existing crushers requires an extended basic knowledge about the crushing process itself. The aim of the present study is therefore to find the theoretically optimal way of crushing compressively under given circumstances. In the present paper, optimizations have been performed with the purposes of maximizing product yield and minimizing energy consumption. Performed on an ideal crushing stage free from physical limitations, the optimization results have been obtained in terms of number of compressions and their corresponding compression ratios. Complementing earlier results on interparticle breakage (Hulthén et al., 2006), presented here are thus the results from corresponding optimizations with single particle breakage and interparticle breakage. It is concluded that modern crushers are not working optimally in any of the studied aspects for gneiss. In fact, optimizations indicate that a lowering of the compression ratio, as well as a shortening of the crushing sequence, are theoretically favourable. The outcome of this study is therefore highly promising as to giving new ideas and suggestions of improvements in existing crushers, and can even result in redesign of compression crushers.

Jan 1, 2014

By Z. He

Based on full investigation of the characteristic of sphalerite in the residue obtained from cyanidation leaching process and the study of the mechanism of the interaction between flotation reagents and sphalerite with the aid of electrochemical analysis, the reagent named YO was developed for eliminating the depression effect of CN- on sphalerite and reducing the dosage of CuSO4. The achievements have been used in commercial production for the treatment of the cyanidation residue to recover the zinc minerals, obtaining a zinc concentrate with grade of 56.49% Zn and recovery of 86.63% Zn.

Jan 1, 2014

By F. M. Zafar Kaifi

Magnesite producing companies rely on high grade purity MgO. The mineralogy of magnesite has a significant impact on the manufacturing of magnesite bricks. The manufacturing process of bricks companies utilizes 90% magnesite from 85%~90% MgO. The main objective of the magnesite bricks was to utilizes the indigenous raw material available in bulk quantity. With better under-standing of chemistry of the mineral species and strict control of bricks manufacturing/processing conditions can be better produce efficiently, a low cost high quality bricks with minimum detrimental environmental impact.

Jan 1, 2014

By A. P. Das

Biomining technology focuses on achieving effective recovery of precious metals from their ores and concentrates using microbial techniques. Biomineral extraction of manganese from low-grade manganese ores using bioleaching was investigated in this paper. Five fungal strains were selected for screening of bioleaching of low-grade Mn ore collected from Sanindpur iron and manganese mines, Koira Sector, Keonjhar, Odisha, India. A fungal strain, Aspergillus niger was selected as it showed high efficiency of manganese leaching. Growth of the fungus was determined in terms of sbiomass dry weight and the final pH was monitored. The selected fungal strain was used for bioleaching of low-grade manganese ore of -150µm size particle size at 2 % pulp density with 2g/100ml sucrose concentration for duration of 20 days. About 60 % of Mn bioleaching was obtained with A. niger. The fungal species proved to be useful for manganese biomining.

Sep 1, 2012

By Jun Xiao, Jianwen Yang, Yanhong Dong, Daixiong Chen

"MANGOTE Surface oxidizied mine is a gold-bearing deposit in Congo's Mai-Ndombe Province. In the past decades, the ore has been exploited in a crude way by local farmers, which directly causes the severe processing difficulty and lack of economy of cyanide leaching. Hunan Research Institute for Non-ferrous metals (HRIM) is currently investigating options to recover gold through understanding the mineralogical characteristics of MANGOTE surface oxidized ore. Chemical analysis , X-ray diffraction(XRD) and Quantitative Evaluation of Minerals by SCANing electron microscopy (QEMSCAN ) were conducted on samples from mine site. The bulk analysis results showed that gold separation of gold from gangue minerals was feasible after grinding the ore samples to 86.53% -74µm and adjusting the pulp specific weight at 100g/L, and gravity separation was conducted with using spiral chute after grading of fine particles. The research results highlight relationship between mineralogical characteristics of abandoned ore and economy of comprehensive utilization that might be directive experience to similar cases. INTRODUCTION The occurrence state of gold in natural gold minerals determines the basic recovery and recovery effect of gold(Komnitsas, C., & Pooley, F. D. 1989). The occurrence of gold in the ore refers to the form of gold in the ore.Generally the existing state of gold can be divided into four major categories according to the viewpoint of the dispersion system: independent minerals and gold, a coarse dispersed system;colloidal gold, a colloidal dispersion; solid solution gold, is atomic ion dispersion; adsorptive gold, according to the adsorbed particle is the micelle or ion, respectively is a colloidal dispersion or ion dispersion(Mao, S. D., & Yang, R. S. 2009; Liu, J. J. et al. 2007; Horisberger, M., & Rosset, J. 1977; Li, Y., & Audétat, A. 2013).With the increasing technology of comprehensive utilization of resources,varied plants can now process different gold ores with various occurrence states(Neesse, T. 2014; 7. Ogundare. et al.2014)."

Jan 1, 2018

"The most common comminution testing methods and the associated analytical procedures provide average values and do not capture the variability in breakage behaviour of ore particles. Therefore, plant designs and process performance predictions use only average values; hence, the inherent variability that exists within an ore domain translates into variation in process performance. This paper discusses the drawbacks of using the average approach to impact comminution testing and plant design. It considers breakage intensity from a single-particle testing perspective. To clearly delineate breakage behaviour of each broken particle, an experimental technique using the JK Drop Weight Tester (JKDWT) has been developed by which actual comminution energy per particle and breakage intensities were measured directly. Four different ore types in ranges of -45+37.5mm and -22.4+19mm were tested at three energy levels of 0.1, 0.25, 0.5 kWh/t and six energy levels of 0.5, 1.0, 2.0, 2.5, 3.0 and 4.0 kWh/t, respectively. Sieved results of individual particles, notionally, t5, t10 and t50 showed the presence of large variability in their breakage behaviour, which was not captured by the standard JK impact breakage testing approach. In addition, the original JKMRC model is modified by introducing a third parameter, ‘Emint10’ which describes the minimum energy required to produce the minimum percent t10 for a given ore type and its significance is tested statistically. These results suggest that the analysis of breakage variability may lead to more robust plant designs. Perhaps, the most useful insight from this work is to extend single particle breakage model developed by JKMRC to a comminution percentile envelope which may provide a more detailed picture of ore breakage variability. INTRODUCTION Rock consists of mineral grains, pores, voids and cracks that may differ markedly in size/density which make rock a heterogeneous material by nature. The degree of heterogeneity in rock affects its breakage characteristics where these variations increase local differential strain and stress within a stressed rock (Scholz, 1968) and it depends on many factors such as rock genesis, alterations, etc. One important aspect of this heterogeneous feature is presence of a large amount of experimental scatter in rock breakage results when considered from a quantitative perspective (Bieniawski, 1967; Liu, Roquete, Kou, & Lindqvist, 2004)."

Jan 1, 2018

"A sulfide ore containing 2.19 g/t Au and 13.13 g/t Ag was studied for the deportment and extractive metallurgy of pay metals. The ore is composed mainly of non-sulfide minerals with approximately 10% pyrite and minor amounts of marcasite, chalcopyrite, galena, sphalerite, and arsenopyrite. The deportment study using a comprehensive approach showed that gold and silver minerals in the ore are mainly native gold (Au), electrum (Ag, Au), petzite (Ag3AuTe2), hessite (Ag2Te) and volynskite (AgBiTe2) with minor amounts of acanthite (Ag2S) and argyrodite (Ag8GeS6). At current grinding fineness (P70@150µm), the majority of liberated native gold and electrum particles are larger than 20µm with 85% >40µm, some of them are even larger than 150µm, indicating that extended leach time may be required to dissolve these coarse gold grains to completion and gravity concentration needs to be considered. Petzite is relatively fine with all liberated particles being less than 80µm in size. Gold distribution and leach testwork results showed that liberated gold accounts for 50% of the head assay, exposed gold associated with sulfide and non-sulfide minerals accounts for 30% and 11% of the head assay, respectively. Gold locked in sulfide and non-sulfide accounts for 4.8% and 4.1%, respectively. Thus, it is recommended that cyanide leaching be considered for extracting gold in this ore. This paper presents the detailed results of the gold and silver deportment study and extractive metallurgy testwork, and discusses the impact on process selection and flowsheet development.INTRODUCTION Gold and silver have been found in various geological environments and ore types. In terms of the gold deportment and extractability, gold ores can be classified into two categories and 12 types. Their extractive metallurgy is largely driven by mineralogical factors such as particle size, association with other minerals, coatings and rimmings, presence of cyanicides, oxygen consumers and preg-robbers, presence of refractory gold minerals and locking of submicroscopic gold in sulfide and sulfarsenide mineral structures (Zhou et al., 2004; Marsden & House, 2006; Zhou, 2013a, 2013b). Compared to gold, silver mineralogy is more complex and metal extraction is more challenging due to its presence in over 200 Ag-bearing minerals (a silver-rich ore body would typically contain 5 to 10 different silver minerals) (Gasparrini, 1984), presence of refractory silver minerals (such as pyrargyrite, prustite and stephanite) and submicroscopic silver in sulphide minerals (such as galena and copper minerals) (Chryssoulis et al., 1985; Di Prisco et al., 2002). The presence of these issues often causes problems in Ag-bearing ore processing. Therefore, knowing the deportment of gold and silver in the ores and metallurgical products is important for flowsheet development and process optimization."

Jan 1, 2018