Search Documents

"Liberation is a key requirement for efficient separation in mineral processing. As a consequence of this an understanding of the inherent textural features of an ore is no longer possible since during the process of liberation, texture is destroyed. Knowledge of key textural features, such as mineral grain size and distribution, prior to breakage processes provides the opportunity to understand the textural drivers for ore hardness. Modern characterisation methods, including automated SEM-based techniques, provide the possibility of measuring mineral characteristics at a range of scales. This paper discusses how textural features of two different ore types in a porphyry copper deposit can be measured and interpreted at a number of scales. Standard breakage tests conducted on the ores indicate that one of the ores can be characterised as hard and the other as soft. The impact of mineral grain size and the presence and scale of vein type structures in the two ores have been used to determine the extent to which these features influence ore hardness.INTRODUCTIONIn order to effectively convert ore into metal, knowledge of both the processing stages and the characteristics of the ore are essential. Prior to the advent of technologies that enabled the fundamental understanding of the sub-process at each stage of processing and the measurement of appropriate ore properties the most effective way to understand how an ore would respond to a process was to put it through that process, for example the way to determine how an ore would break was to first break it. Existing comminution models seek to predict the size distribution of rock fragments as the result of applied energy based on knowledge of the rock strength. It is common for these models to consider the rock as homogeneous and despite providing important data for the design and optimisation of industrial comminution circuits these models are only applicable within a narrow range of operation. In order for reliable predictive models to be developed that account for the inherent ore characteristics, a step change is required in the type of measurements that are carried out to characterise an ore and the type of data that is extracted and used as model inputs."

Jan 1, 2016

By R. A. Hemstock

"Simple classification systems are now being used which will describe adequately the surface vegetation, the topography and the peat for any muskeg condition. Good progress is being made in determining some of the mechanical properties of muskeg and it is apparent that the science of soil mechanics will apply largely to these studies. Correlation is also indicated between shear strength as determined by the shear vane tester and vehicle performance. Several tracked vehicles are now available which perform well in muskeg and advances in this field have come rapidly in the past few years. Testing is under way on the largest of all muskeg vehicles -the thirty-five ton Musk Ox. This vehicle will fill the last gap for the oil industry and will make possible the movement of large drilling rigs at any season of the year."

Jan 1, 1960

By Yulin Zhou, WenFeng Li, Wen Chen

"In this article, with the help of the X-ray photoelectron Spectroscopy (XPS), a modern test method, all the characteristics of the chlorite,and adsorption collector A6 on the surface of chlorite have been studied. There exist abundant carboxylic C-O and C=O structures in the Carbon XPS atlas with strong adhesive ability after the reaction between new collector A6 and chlorite, which indicates that the ring structure and ether-base functional groups can strengthen the reaction between collector A6 molecule and chlorite surface. The results of XPS analysis indicate that the photoelectron spectroscopy peaks of Mg2p and Al2p moved towards low energy after collector A6 absorbed on chlorite surface, which indicates that chemical bonding through electron cloud transfer happened between collector A6 and Mg, Al ions of chlorite surface. The chemical reaction promoted the adsorption of A6 on chlorite surface and eventually improved the ability of A6 to float and collect chlorite.INTRODUCTIONThere are a large amount of iron-bearing silicate minerals such as chlorite in different types of gangue minerals in iron ore from different areas besides quartz (Yingyong et al, 2012; Qiang et al, 2009). There always exist Mg2+, Al3+ Fe3+ and other metallic ions due the isomorphic replacement among the irons of this kind of minerals. The dissolution often occurs on the surface of minerals with abundant metallic ions during grinding process, and some ions are exposed on the surface, such as Mg2+, Fe3+, Al3+, Si4+, which can increase the surface electrical behaviour of iron-bearing silicate minerals (Wanzhong & Chuanyao, 2002; Yuping et al., 2007), making it easy for the surface to react preferentially with the depressants such as causticizing starch which making it impossible for the surface to reach with conventional anionic fatty acid collector (Mowla et al, 2008). Thus, the beneficiation efficiency is dramatically decreased and the improvement of concentrate grade becomes very difficult. The conventional aliphatic acid collector has some defects such as poor selectivity, poor low temperature resistance, sensitive to water hardness, etc. Thus, the addition of synergist (Liu, & Yu, 2015) or other compound reagents (Zhou et al, 2015) can promote the adsorption of reagents to mineral surface, and improve the collecting capacity and selectivity of aliphatic acid collector to minerals. The addition of polar group to nonpolar group in aliphatic acid can improve the water solubility, dispensability and hard water resistance (Tian et al, 2013). The nitrogen atoms in amid ate aliphatic acid collector can adsorb on mineral surface by itself and supply coordinate electron which can form chelating keys to improve the collecting capacity of collector. There exist coordinate electron in oxygen atoms of ether acid collector, which, along with the oxygen on carboxyl compose chelate with metal (Luo et al, 2015). There are also exist some opinions that the ether acid can arrange into similar crown ether structure which can absorb on mineral surface. A new alicyclic unsaturated ether acid compounds collector A6 is adopted in this paper, the structural formula is listed in Figure 1. The A6 has a strong collecting ability to chlorite with strong water solubility and low temperature resistance."

Jan 1, 2016

By D. P. Bishop, G. J. Kipouros, R. L. Hexemer Jr., I. W. Donaldson, W. F. Caley

Aluminum powder metallurgy (APM) is an advanced metal forming technology frequently employed to fabricate complex structural components in a near-net-shape fashion. Exhibiting nearly 100% material utilization, APM continues to rise in popularity. Recent research initiatives in this field have emphasized the development and processing of advanced 2xxx and 7xxx series alloys. In particular, APM equivalents to wrought 7075 and 2024 have been sought. An overview of work completed in this area is presented. Included are data on the various production stages (powder compaction, sintering, forging, and heat treatment) as well as the microstructure and mechanical properties of the finished products.

Jan 1, 2010

By S. Beskri, N. Geoffroy

When metallurgical plants are designed, a lot of consideration is almost always given to material selection and possible damage mechanisms. Materials engineers are generally involved and will strive to select optimal alloys or refractories for the design conditions. Once in operation however, things often change. Equipment is overstressed to increase production, corrosive leaks are not always promptly addressed, proper welding procedures are disregarded, etc. This paper describes various cases from the mining and metals industry where serious mishaps, associated consequences, and costs could have been avoided if simple and proactive steps had been taken. It also presents a strategy, based on safety reviews, to help predict and prevent damage to critical pieces of equipment.

Jan 1, 2015

By L. Tikasz

The primary purpose of ore hauling model studies is to capture the variability of the ore delivery ? stockpiling process in order to improve the estimation of equipment capacities and achievable throughputs. The operation of a mine-to-site ore delivery system is the subject of a number of challenges. Typically, ore is hauled by a given combination of trucks, conveyors and trains. In addition, ore loading, ore transferring to another means of delivery, stockpiling, reclaiming, and further deliveries involve many other types of equipment. The concurrent operation of all these units is scheduled; nevertheless, they are subject to planned maintenance and random breakdowns. To support our engineering design work on ore hauling operation, discrete event type models were built for each specific task. Then, due to recurring demands, an ore hauling library was gradually compiled. The now available model library allows fast and efficient simulation of various mine-to-site hauling arrangement, adaptable to various mining and mine construction operations (e.g. bauxite, iron ore, copper ore and coal).

Aug 1, 2013

By K. A. Clark

A meeting between representatives of the Scientific and Industrial Research Council of Alberta and the Deputy Minister of Mines for Canada was held at Edmonton in May, 1929, for the purpose of formulating a co-operative plan for carrying forward studies in aid of the development of commercial methods for utilizing the bituminous sands of Alberta. It was agreed that to the Alberta Research Council should be allocated the general problem of investigation of the processes for the separating of bitumen from the sands, including studies of methods of emulsifying, dehydrating and otherwise preparing separated bitumen for industrial applications. It was further agreed that during the present year the work of the Alberta Research Council should be to continue its laboratory investigations of points of design of its separation plant; to further perfect its separation procedure; to recondition its existing separation plant at Dunvegan Yards, Edmonton, in the light of laboratory studies and to operate it for the purpose of demonstrating its efficiency; to carry on tests in emulsifying and dehydrating or otherwise preparing separated bitumen for industrial application; and on the basis of the experience gained in the operation of the preliminary plant at Dunvegan Yards to prepare and design and, as far as possible, to proceed with the erection of, a semi-commercial separation plant at a site to be chosen, probably at the bituminous sand deposits near McMurray, Alberta. This paper presents, in the main, a progress report of the carrying out of this programme.

Jan 1, 1929

Some examples of the results of research projects, conducted in the KOMAG Institute of Mining Technology are presented. Special attention is paid to mining machines and equipment, and improving work safety and comfort of miners in underground workings. From numerous scientific and technical achievements of the KOMAG Institute within the last 2 years, a few design solutions have been selected for a presentation. Some results of European projects on innovative solutions are described as well, highlighting KOMAG?s role in the national and international research area.

Aug 1, 2013

By Walter I. Nelson

THE geology of the Copper Mountain mine has been ably described by Dr. Victor Dolmage in Memoir 171 of the Geological Survey. Reference is invited to that paper for a more extended description of the geology of the ore deposits than will be given here. The important orebodies of the mine occur in fragmencal volcanic rocks, parallel with and adjacent to the gabbro of the Copper Mountain stock. In the mine area, the contact strikes N.45°W. and dips either vertical or steeply co the southwest. For a distance of 500 feet or more from the contact, the fragmental rocks have been intensely metamorphosed both dynamically and hydrothermally. The dynamic effects are reflected in the foliation and fracturing parallel with the contact, which occurs throughout the mine, and the volcanic rocks within this foliated zone are, in places, highly schistose. Superimposed upon thi.s structure is a system of fine, straight, parallel frac-tures that strike nearly normal to the foliation (and contact) and dip between 65° and 75° to the north; it is with this last-described fracture system that the ore minerals are structurally associated. The fractures are mineralized with bornite and, to a considerably less extent, with chalcopyrite and some pyrite. A notable characteristic is the extreme fineness of the fractures; even in high-grade ore they are rarely larger than pencil lines. The tenor of the ore, therefore, varies directly with the fracture spacing. Replacemcnr of the host-rock between two or more fractures, varying in degree from finely disseminated sulphides to masses of nearly solid bornite up to 18 inches wide and 2 to 3 feet long, is not uncommon in the higher-grade portions of the orebodies. Two structural types of orebody are recognized in local nomenclature: the 'contact' orebodies, so-called because they occur along the contact; and 'outlying' orebodics, which are enclosed in the volcanics. The former arc tabular or lenticular bodies elongated along the strike and dip of the contact. The 'outlying' orebodies are coniform, chimney-like masses roughly elliptical in plan; with depth, their roots plunge at steep angles toward the contact. All of the orebodies are cut by a number of light-coloured granophyre and felsite porphyry dykes. These dykes-the so-called 'mine' dykes -enter the mine area from the north, curve gently southeasterly across the orebodies, and then cross the contact into the gabbro at the south end of the mine. All the dykes dip vertical to steeply east.

Jan 1, 1941

"The Waite-Amulet, an important copper-zinc mine, lies astride the Duprat-Dufresnoy township boundary about 8 miles northwest of Noranda, Quebec. It is an amalgamation of two properties, that of the former WaiteAckerman- Montgomery Mines to the north and that of Amulet Mines, Limited, to the south. This amalgamation took place in 1933. The description that follows is confined to the Amulet section.Ore was first discovered on the Amulet property in the autumn of 1924. The C Shaft and Upper A orebodies were found in 1925 and the F orebody in 1929, the latter by diamond drilling under a swamp. Under the present management, Lower A ore body was discovered by diamond drilling at a depth of 700 to 1,200 feet in 1938, and new ore was found from the old C Shaft workings between 1943 and 1945.From April 15th to October 20th, 1930, 60,291 tons of ore was produced from the Amulet. During the second half of this period, the ore averaged 4.2 per cent copper, 16.3 per cent zinc, and 0.02 oz. gold and 3.35 oz. silver per ton. Due to the prevailing low prices of metals, there was no further production until July, 1937. Output was greatly accelerated in 1940 when the newly found Lower A orebody assumed the main burden of production. Up to January 1st, 1946, mill reports indicate the treatment of the following ore: GENERAL GEOLOGYFig. 1 shows the geology of the entire property. To the east is the Lake Dufault granodiorite stock and to the west the Flavrian Lake granite mass. Around the granodiorite and separating the Waite from: the Amulet section is an older diorite intrusion. The ore occurs in a series of lavas that form a broad anticline pitching eastward at a relatively low angle into the Lake Dufault intrusives. There are several steep east-west faults. The late Powell diabase dyke is shown, also the general areas of strong dalmatianite alteration, a type closely associated with the sulphide mineralization."

Jan 1, 1954

By Carrasco .. P. J. A., R. Parada, I. Saavedra, F. Parada, R. Parra, E. Balladares

In most of the smelters, the management of flue dust has a double objective: the control of minor elements in the anodes and the management of volatiles compounds that can cause contamination due to fugitive gas emissions. This is a special concern when high content of Va elements (As, Sb & Bi) are present in concentrates. We present the results of the experimental study to prove the principle of a novel process that recovers, via volatilization, the As, Sb and Bi in the flue dust as gaseous sulfides, due to a previous sulfidization. In the case of as control any further classical treatment for its stabilization is possible from the gas. The clean calcine can be returned to the smelter avoiding any concentration of these minor elements in the circuit. This process is now tested at pilot scale and shows better indices on carbon footprint than the classical hydrometallurgical process for flue dust.

Jan 1, 2011

By L. Tong

"The oxidation of Quebracho was evaluated by acid-butanol assay, which indicates depolymerization of Quebracho. Anthocyanidin, an oxidation product of Quebracho, is stable at 95?C for up to 2 h. The ionization, complexation, and oxidation properties of Quebracho were discussed. Complexation of metal-Quebracho occurs at ambient temperature. The formation of complex precipitates is influenced by the acidity of the solution. Temperature is another important parameter that influences the oxidation and the complexation of Quebracho. Quebracho-ferric complex precipitate forms at 90?C, 0.1 mol/L H2SO4. The formation of Quebracho-metal complex in the leach solution is a possible reason for the consumption of Quebracho. Quebracho molecules adsorption on the mineral surface is reduced by consumption of Quebracho, resulting in poor sulfur dispersing effect in the leaching process. INTRODUCTIONQuebracho is used as a sulfur dispersing agent (SDA) in the pressure leaching of zinc concentrate as stated in U.S. Patent No. 3,867,268 (1975). It prevents the zinc sulfide particles from being coated with molten sulfur, thus preventing the inhibition of the zinc leaching reaction. Recently, the sulfur dispersing effect of Quebracho was investigated in the oxygen pressure leaching of nickel concentrate. The oxygen pressure leaching of pentlandite can be represented by reactions 1-3."

Jan 1, 2012

This paper presents a case study where Cenozoic age detritals and an ancient buried landslide have been modelled in the final walls of an iron ore pit. Orebody 25 is located in Western Australia’s Pilbara region and is an operating pit where a redesign of the final wall cutback was required. The existing slope design utilised a simplistic geological model of mixed conglomeratic, calcretic and clay –dominated detritals overlying deformed bedrock sequences. This simplicity resulted in a conservative design that was not reflective of the slopes performance to that point. Further field investigation was carried out with the results assessed in conjunction with historic drilling, mapping and laboratory testing. A detailed geotechnical model was developed including three conglomerate and two clay dominated units and laterstage calcrete overprinting. The clay units were of significant importance to the stability assessment and resulting slope design due to the thickness and poor strength conditions indicated by the laboratory and field testing. However, the drilling investigation shed only limited understanding as to the origin of the clays and thereby how they should be treated as a component in the stability analysis. A comparison of the ratio of various geochemical elements measured by assay was made between the clays and 1) shale bedrock and 2) clays of known detrital origin from other nearby sites. This indicated the clays had a strong affinity with weathered bedrock. This and other textural features resulted in the interpretation that the clay units were relic debris preserved following ancient landslides in bedrock shale. Using laboratory testing data and calibration of results for a landslide origin, stability analyses were run, resulting in a steeper slope design being implemented. Excavation of the final cutback is now in progress with the model confirmed as appropriate.

Jan 1, 2015

About Barrick Paste Backfill at Barrick Goldstrike Rodeo Paste Plant Cyclone Lab Testing Challenges and Lessons Learned Future Barrick Projects

May 1, 2013

By Paul W. Shelley, Daniel J. Hodges

The mining industry is undergoing a period of rapid transformative change.  This is the result of the social and financial accountabilities that the industry is faced with because of the world’s desire to cap average temperature increase to 1.50C above pre-industrial levels (UNFCC, 2016).  To limit global warming to 1.50C, greenhouse gas emissions must peak before 2025 at the latest and decline 43% by 2030.  In hard rock mining, comminution is identified as the major energy consumer, being responsible for 40-60% of the electricity use.  It follows that comminution is the major greenhouse gas emission process of the mine.  All effort is being made to radically reduce the carbon emissions of comminution. Grinding media plays a large role in the energy consumption and carbon emission story.  In recent years industry practitioners have attempted to quantify the grinding media carbon footprint.  This paper makes a definitive contribution to that discussion.  The grinding media carbon footprint is quantified in Scope 1, 2 and 3 emission terms in the context of a grinding media supplier.  Major emission contributors, steel, natural gas and electricity are discussed in detail.  The steel industry transition is a key factor. The paper will explore the steel industry transition and its effect on grinding media manufacturing.  The carbon footprint of heritage steel process routes are analysed and compared with the process routes of the future.  Emerging steel making technologies are presented and discussed.  The future of the steel manufacturing and procurement route for grinding media is proposed. This narrative allows for a comparison between the heritage carbon footprint and the future carbon footprint of manufactured grinding media.  Of equal importance is the opportunity of reducing the grinding media carbon footprint in the field.  The paper explores possibilities of reducing the grinding media carbon footprint at the customer site.  Media in use options are presented that take account of the mineral characteristics, the mill dynamics, and the product metallurgy to optimise both carbon footprint and media performance. It is intended that this is a landmark paper in the discussion of the carbon footprint of grinding media.

May 4, 2025

By J. L. Jambor, J. E. Dutrizac, J. B. O'Reilly

The present-day metallurgical community is quite familiar with the use of jarosites [MFe3(S04)2(0H)6 where M = K, Na, NH4, Ag, 1/2Pb, etc.] as a means of controlling iron, alkalis and sulphate in hydrometallurgical circuits. This modern precipitation technology has found an increasingly widespread application in the zinc industry111 and is gradually also being extended into the hydrometallurgical processing of copper and cobalt121 . The chief advantage of jarosite precipitation is that the iron precipitate settles and filters well, and gives low losses of divalent metals in the washed residue. Although this jarosite precipitation technology was developed only within the past twenty years, man's involvement with jarosites extends back to antiquity, and jarosites have played an important role as a source of silver in several ancient metallurgical centres. In the early days of this century, argentojarosite was an important local source of silver at the Tintic Standard mine, Dividend, Utah, where over 200 000 oz of silver were recovered from highgrade natural jarosite over a three-month period 131 . At the Matagente mine in Peru, pockets of argentiferous plumbojarosite up to 40 m thick were mined and processed by the Indians prior to the arrival of the Spaniards14-51 . In Cyprus there are vast jarosite deposits associated with the ancient mining sitesl51 , but exploitation of these jarosites has been insignificant because of their low silver values. The most extensive mining of silver-bearing jarosite, and certainly the oldest documented instance of such jarosite exploitation, was in the vast pre-Roman workings at Rio Tinto, Spain. This mine, the greatest single miningmetallurgical site currently known from the ancient world and also the oldest site of more or less continuous metal production, has witnessed many metallurgical firsts. Aside from the initial processing of jarositic ores for their silver values, the development of large-scale hydrometallurgy also seems to have occurred at Rio Tinto. As early as 1737, copper was recovered by cementation on scrap iron from the mine waters at Rio Tintol51 . Large-scale heap leaching of calcined ore commenced with the British operations in 1876 and, by 1900, raw pyrite was heap leached to recover associated copper values161 .

Jan 1, 1999

By Forrest A. Kerr

Introduction During recent years the work of the Geological Survey in northwestern British Columbia has been in the nature of reconnaissance and exploratory mapping, largely for the purpose of gaining knowledge of the potential mineral-producing zones known to occur along the eastern side of the Coast range, and also to gather such data as might facilitate their exploitation. Commencing with fairly detailed mapping in the more accessible parts, the work has been continued and expanded until now an understanding has been gained of the more general features of a continuous section along the range for a distance of about two hundred miles. Geographically, northern British Columbia is more or less isolated. It is cut off from the central part of the Province by a rugged and mountainous country which, except for the telegraph line and a rarely travelled trail along it, is not penetrated by any developed routes or lines of communication. To the west, it is cut off from the Pacific by the Coast range, an extremely rugged area sixty to eighty miles in width which, except along the few navigable rivers cutting across it, cannot be readily traversed. Politically, it is further isolated in this direction by the narrow strip of south-eastern Alaska which borders the coast and extends inland to the axis of the range.

Jan 1, 1931

By R. Cammack

"A fundamental component of the Hoek–Brown empirical rock failure criterion is assessing an appropriate mi constant. In developing their empirical criterion Hoek and Brown normalised triaxial test results by dividing the principal stresses at failure by the uniaxial compressive strength to provide mi values for typical rock types. Experience shows that Hoek triaxial tests for individual lithology types commonly have a large inherent scatter. In addition, tests are often conducted on core from random locations, which although being of one parent rock type, display variations in density as well as minor variations in grain size and alteration.This paper presents experience from projects the authors have been involved in which large sample populations of triaxial and UCS tests on similar rock types were available. Geophysical logging data was also available for some projects. The methods used to estimate the compressive strength for each sample and the effects on normalising the data sets are described. The variability of the data and uncertainties and assumptions involved in the process of assigning a mi value from the normalised data are also discussed."

Jan 1, 2015

"Yara Siilinjärvi in Finland is the Western Europe's only apatite mine. Annually it produces one million tons of apatite concentrate, which creates 10 million tons of tailings. At the beginning of 2017, Yara replaced their conventional TSF with a new tailings treatment plant, which increased the solids content of the slurry from 45–48% to 66–68%, making it possible to deposit as a paste. This extended the life-span of the current TSF from 2020 to 2035. This paper presents the storyline of the Yara paste plant project. The project began with laboratory testing and then progressed to pilot-scale thickening and beaching trials. After successful pilot trials, the final process design was implemented. Process automation played a key role in the project. An advanced control system is needed to maintain process stability and the desired operation point in various operational circumstances. Since commissioning the paste plant has been running consistently with an underflow solids content of 66-68%, with average beach slope angles of 3.5 degrees in the tailings disposal area. Robust thickener operation also leads to the trouble-free high-density pumping and high availability of the plan. During first year of operation the plant’s availability has been very good, over 97%, and currently, the plant is operated remotely from the main concentrator plant.INTRODUCTION The Yara Siilinjärvi Plant is owned by Yara International, a Norwegian fertiliser company. Yara Siilinjärvi is Western Europe's only apatite mine, and it primarily produces apatite concentrate for its Siilinjärvi phosphoric acid plant. A portion of the concentrate is also dried and shipped to other Yara fertiliser plants. The site annually produces one million tons of apatite concentrate, which creates approximately 10 million tons of tailings. Extending the lifespan of the 1150-hectare tailings storage facility has been studied in Siilinjärvi for a long time. The aim has been to use the same tailings area footprint, without any new land purchases or major dam increases. An important part of the process has been to study the possibilities for using new technologies, especially thickened tailings technology (Ruhanen, 2014)."

Jan 1, 2019

By L. V. Chugaev, Y. M. Shneerson, P. V. Zaytsev, I. V. Fomenko, M. A. Pleshkov

"Pressure oxidation (POX) is one of the most common and reliable methods of processing gold-bearing sulfide concentrates. However, when processing concentrates that contain natural carbonaceous matter, substantial gold losses occur due to autoclave preg-robbing. The latter involves formation of gold chloride complexes under typical POX conditions (high temperatures, high acidity and high ORP) and subsequent sorption of these complexes by carbonaceous matter. Naturally, chloride ion plays a significant role in the process of autoclave preg-robbing; its concentration in POX solution has a well-marked effect on subsequent gold recovery during cyanidation of POX residue. The previous research done by SRC Hydrometallurgy showed that autoclave preg-robbing of gold could be significantly inhibited by the addition of mercury(II) compounds to POX slurry. The positive effect of mercury(II) was well pronounced both at high (>20 mg/L) and low (<5 mg/L) Cl concentrations in POX solution. The successful bench-scale laboratory testing was followed by pilot plant trials at Ore Test Facility in Blagoveshchensk, Russia. The present paper provides the results of these trials. The bench-scale testing results were verified; the optimum oxidizing parameters and reagent dosage were specified. The behavior of mercury (II) at POX pilot plant was found to be in good consistency with industrial practice described in the literature.INTRODUCTION Pressure oxidation (POX) is one of the most common, reliable, and commercially proven methods of processing gold-bearing sulfide ores and concentrates. However, when processing double refractory materials that contain natural carbonaceous matter, POX technology advantages are compromised by autoclave preg-robbing of gold. The latter occurs when natural organic carbon and soluble halides are both present in autoclave feed. Strongly oxidizing conditions of POX (high temperature, oxidation-reduction potential or ORP, and acidity) favor formation of gold-halide (mostly, gold-chloride) complexes, which tend to bond with carbonaceous matter. The exact nature and mechanism of this bonding is unknown, but as the result of this, cyanide is unable to leach gold from POX residue and the precious metal is lost to the tails (Axenov et al., 2014; Dimov, Chryssoulis, & Sodhi, 2003; Fomenko, Zaytsev, Pleshkov, Chugaev, & Shneerson, 2013)."

Jan 1, 2017