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By W. A. Ahrens, J. H. McNamara, J. G. Franek

"An economical, pollution-free process has been developed for the hydrometallurgical extraction of copper from sulphide ores. The extracted copper, in the form of cuprous chloride (CuC/), is converted by reduction to copper metal. The metal is melted and fire -refined into wire bars which meet the standards of electrolytic tough pitch (ETP) copper wirebars. IntroductionThe successful development of the Cyprus Copper Process has been an evolutionary series of events covering a time span of some nine years. The original process, based on an electrolytic membrane cell principle , was abandoned in 1975 because of technical, economic and pollution problems. During the past four years, the pilot plant has been reconstructed based on a new flowsheet and operated successfully in several campaigns, some for as long as four months. The pilot-plant hydro section operates at a 225-lblhr copper rate. In October 1977, a feasibility study was completed by Jacobs Engineering, Pasadena, California. The study showed favourable economic and technical feasibility. Jacob's studies in 1978-79 revealed favourable comparative economics with other known pyrohydro processes and favourable economies of scale.The Cyprus Copper Process converts copper concentrates of varying composition into copper metal, which has been proven to be equivalent in every way to electrolytic tough pitch copper, suitable for electrical applications. This is accomplished at capital and operating costs which are estimated to be lower than those associated with any other known currently applicable technology. Also, the total energy requirement is equal to or less than any other known process and the process is essentially pollution free."

Jan 1, 1980

"Real time analysis of conveyed bulk materials can be used to improve process performance by reducing variability and upgrading ore quality through selective removal of increments of flow that do not meet appropriate selection criteria. This paper focusses on proven Prompt Gamma Neutron Activation Analysis (PGNAA) and microwave transmission technologies used to representatively measure conveyed ore quality in real time so that meaningful decisions can be made between the mine and mill. This enables the effective removal by bulk diversion of small increments of conveyed flow such as waste, highly deleterious material or sub-economic material from the mill feed. Improved ore quality in plant feed optimises process performance, reduces processing costs and minimises tailings generation. Analysis is unaffected by particle size, dust, layering or segregation, mineralogy and belt speed. Technologies are explained and performance examples given from installations in copper and iron ore. The technology has been used successfully in bulk sorting for over twenty years typically using measured increments of a few minutes. Improvements in technology and calibration performance have resulted in accurate measurements over increments of thirty seconds and below.INTRODUCTION Ore quality variability exists on a number of scales. Block model grades represent a few hundred to many thousands of tonnes. Grade control at the mine occurs on a scale typically down to the size of a haul truck, which may be a few hundred tonnes. Highly variable ore quality is detrimental to process efficiency and effectiveness. Processing waste or low grade ore when higher quality feed is available represents a lost opportunity to generate higher revenues earlier in the operational life. Measuring ore quality accurately over short time increments during conveying enables small increments to be measured and diverted according to their quality. The paper explains the technology and benefits. Neutron irradiation techniques were considered potentially suitable for conveyed bauxite measurement by Beurton et al, 1995. Tran & Evans (2001) concluded there was no equivalent technology to Prompt Gamma Neutron Activation Analysis (PGNAA) in terms of material penetration power. PGNAA was evaluated by Nelson & Riddle (2003) for possible use in the phosphate industry and recommended its use for further characterisation of the mine’s various ore types to improve stockpile allocation and grade control. Cottle (2007) discussed test work for an iron sinter application and Delwig et al (2011) described the successful installation in 2009 and performance of PGNAA for base-to-acid ratio control in sinter feed with the analyser output used to control lime addition. Geoscan (PGNAA) works very well on iron ore and can “improve control over what is happening in the plant” and that comfort can be provided in knowing that the product is on-spec according to Minnett (2010). PGNAA is not yet used in the minerals sector for tariff purposes as has occurred since 2000 with Coalscan (PGNAA) in coal (Minnett, 2010)."

Jan 1, 2017

By Jessica Egan, Daniel Hodouin, Mohammed Reza Khalezi, Steve Bellec, Claude Bazin, Carl Duchesne

"A model for gold leaching was developed and implemented into a simulator. The simulator uses a description of the ore that is based on the mineral composition and precious metal content. The model accounts for the distribution of minerals and precious metals through the size intervals. An ore texture model based on precious metals and minerals grain sizes within the ore is used to predict the exposed surface of the species in the various size intervals. A model is proposed to predict the rate of dissolution of any species dissolution using the exposed surface, particle size, cyanide and oxygen concentrations, temperature, pH and agitation. The flow of slurry through a leaching tank is modelled using a parallel arrangement of perfect mixers to simulate a bypass and a Cholette-Cloutier mixer model. The simulator can be used for circuit optimization but was developed to provide an environment for learning the basic concepts of process analysis methods. Examples are given to illustrate the application of the simulator for planning tracer tests and sampling campaigns.INTRODUCTIONThe constant pressure to improve the operation of processes that are already close to optimum imposes to plant engineers to be aware of the available process analysis tools and to be able to use them to assess process operation and make a diagnosis to possible problems. Some of these tools are:•,Sampling the streams of a process;•,Data reconciliation;•,Analysis of mixing in reactors;•,Estimation of rate parameters;•,Optimal tuning and flow sheet modification;•,Automatic control and real time optimization.Although some of these tools are part of the curriculum of many university engineering programs, the students are not exposed to actual process analysis problems. In addition the complexity of the ore dressing processes compounded with unavoidable measurement errors and plant disturbances can discourage many motivated engineers. These factors often lead to an incomplete valorization of the collected data and a poor return on the investment associated with the sampling, testing and analysis of the samples.Simulators are readily available for process optimization (Yalcin and Shang, 2006) by allowing:•,The simulation of various flow sheet configurations;•,The simulation of a change of operating conditions;•,The simulation of various control strategies;•,The training of plant operators.However few simulators have been developed with the objective of providing an environment for training plant engineers and technicians to the use of tools for process analysis and optimisation."

Jan 1, 2008

By J. M. Whiting

"North America has entered a period when greatly increased attention must be given to energy .supply and demand by government, industry and individuals. Such increasing concern about energy will be a long-term phenomenon, accompanied by continuing examination of future resource development and utilization. Those engaged in or associated with mining, a major energy consumer, are likely to experience a variety of problems which are associated with the end of an era of low-cost, virtually unlimited energy supply. Their efforts, furthermore, may be subjected to escalating public and government scrutiny, involvement and control. However, ever-growing recognition of the real and urgent necessity to systematically develop new energy supplies within Canada and the United States will provide unusual challenges and opportunities for those companies and individuals with mining expertise. The vast deposits of coal, tar sands and oil shale provide a relative certainty of supply which only stands to gain in attractive ness with time. In order to benefit from this aspect of certain supply, nevertheless, synthetic fuels will have to be produced at a tolerable cost. This will always require excellent process design and engineering. As synfuels development expands to any significant production level, however, and Jess than ideal reserves are scheduled, the usual geologic-productivity complexities encountered in making ore out of low-value rock will tend to become of prime concern. It is for this reason that the services of experienced mining personnel will be in growing demand in energy production."

Jan 1, 1973

By James A. Finch

"I offer a personal view of what the next 30 years holds for mineral processing. Re-stating that mineral processing will remain a vibrant industry in raw material production, growth opportunities in waste management are identified. The processing sequence familiar now (mining -mineral processing -extraction) will become more interwoven. In situ processing (i.e., milling underground) will evolve from concept to demonstration. Opportunities to exploit physical properties altered in chemical (pyro-and hydro-) processing will present themselves. In primary grinding, the path to AG/SAG milling will progress with little deviation but opportunities in regrinding are wide open. Flotation will see the trend to designing bubble/particle reactors accelerate simultaneously with a vigorous response from mechanical cell suppliers. Gravity separation remains a bastion of the lone inventor but I anticipate that the new lines will come from the waste management business. I finish by examining the ""research cycle"", identifying growth in small ""high tech"" companies and university research centres.IntroductionI have been asked to offer a personal view of""where we are going in mineral processing?"". Gazing into crystal balls is quite a cottage industry as we approach the end of the millennium. Academics are often asked to assume the role of visionary, I presume because it is considered in their mandate, to reflect and philosophize (or, less charitably, because they are considered to have the time). Since this is the 30th Annual Canadian Mineral Processors Operators Conference, I am tempted to suggest the next 30 years as my frame of reference. This is about equivalent to one engineer's career or, given it takes typically 15 years to go from concept to realization in mineral process engineering (Napier-Munn, l 997a), about 2 ""invention cycles"". With this length of cycle, much that is familiar now will remain so over the 30 years.Research and development (R&D) is in response to need. The overarching need in mining is to find new ore bodies. Process developments cannot compensate for a depleting deposit or a declining commodity price. Mineral processing R&D is characterized by incremental gains, aimed at pushing the mine down the cost per tonne league table. Breakthroughs are the exception (flotation at the turn of the century was one). This must be kept in mind when trying to predict the future in our business."

Jan 1, 1998

By David M. R. Stone

Underground mining in the gold industry is gaining popularity in Nevada, and with it the use of cemented rockfill is becoming mainstream. Even with today?s high metal prices, however, mining companies are very sensitive to the margins they realize, and are constantly looking for ways to reduce costs or improve efficiencies. Given that the backfill is one of the largest cost centers in underground mining, mines are constantly under pressure to reduce backfill costs. This paper will present an overview of the factors that impact cemented rockfill quality in Nevada mines based on the authors many years of consulting experience. Cemented rockfill quality can be linked directly to binder consumption, hence programs aimed at improving quality generally result in lower binder costs, better performance in the fill (hence less dilution), and improved safety. The paper will conclude with the key elements of a comprehensive program of backfill quality assessments and backfill QA programs. Comparative laboratory and minesite data from a number of operating and proposed mines will be presented.

May 1, 2007

By Craig M. Sams

"Variable speed mill popularity has grown during the last 10 years with almost every SAG mill fitted with a variable speed drive. In addition, many of today’s larger ball mills are running a variable speed drive for various reasons. In the past, motor suppliers, especially gearless drive suppliers, have considered mills as being an overpriced rotor. This has lead to mills demanding more torque than what a motor can generate. This paper identifies the reasoning of what has happened and how to mitigate the mismatch in the future. Technical and economical issues are discussed, allowing mill operators to make an informed decision of which path to take in deciding what motor to put on a mill.INTRODUCTIONIt has been generally accepted in the past that motor suppliers and specialists in engineering companies understand the workings of a SAG mill or a ball mill and although there is a fair knowledge within the industry, in regards to mill torque requirements, the advent of variable speed drives in ball mills has shown the writer that a complete understanding of the mill torque requirements are not fully understood.This paper will discuss two aspects of mill torque requirements, (operating torque at various charge levels and start up torque), and how it relates to specifying the proper motor torque requirements.MILL OPERATING TORQUEMill operating torque at a given charge level and density in a mill is essentially constant throughout the entire speed range. For the purpose of this paper, we will take a 38’x 22.5’, 20’ EGL, SAG mill and provide the power draw at variable speeds but fixed loading conditions.The power draw and mill torque of this mill at 8% ball charge and 28% total loading (Highlighted) is shown below as Figure 1, at variable speeds."

Jan 1, 2007

By M. Kane, B. Bissonnette, D. Hodouin

"A laboratory cell has been designed for a careful investigation of gold ore cyanidation using mathematical modelling of the process kinetics. The cell is a stirred vessel with continuous monitoring and control of pH, oxygen and free cyanide contents. Samples are automatically extracted for gold analysis. The instruments are connected to a microcomputer which records all the measured variables and calculates the reagent consumption (air or oxygen, cyanide, lime). For cyanide control a sample is automatically extracted and filtered and the solution analyzed, using a specific electrode, by a flow injection technique. The rate of gold dissolution is modelled using a kinetic model the parameters of which are calculated by a non linear least-squares technique. The parameters of an empirical model of reagent consumption are also estimated. The resulting model is used in a simulator for gold cyanidation plant design, tuning and control.INTRODUCTIONThe leaching of gold ores in a cyanide solution is the usual method for gold extraction from raw ores. This process requires long reaction times and leads to very significant consumption of cyanide. The optimization of the cyanidation plant operation is a very important aspect of gold ore processing for increasing gold recovery and decreasing operating costs. The key parameters to the improvement of gold extraction are the selection of an efficient solution chemistry, the design of the size and the arrangement of the equipment and the correct tuning of the operating variables. Automatic control strategies can then be applied to maintain industrial operations at their optimum setpoints.Two approaches can be used for optimizing design and control of cyanidation circuits, either empirical trials for improving process performances or mathematical modelling of the process kinetics for subsequent analysis, simulation and optimization. The advantages of the second approach, which is used in this study, is that it gives a systematic pattern to interpret data and reliable tools, in as much as the models are good, to improve operation performances. In order to determine the structure and the coefficients of cyanidation models, well controlled measurement and calibration procedures must be used. The purpose of the paper is to present an equipment and a test procedure for modelling the kinetics of gold ore cyanidation."

Jan 1, 1990

By Véronique Falmagne

The mining sequence at Noranda?s Bell-Allard mine calls for two mining fronts retreating toward a central pillar known as the Retreat Zone between pyramids A and C. It is clear from numerical modeling and rock mass characterization that the induced stress level in the pillar will exceed the rock mass capacity. A mining plan was developed including the re-dimensioniong of stopes in the Retreat Zone, additional ground support and instrumentation in order to ensure the safety of the workforce and to maximize ore recovery while minimizing production delays. The mining strategy consists in allowing the rock mass to fracture and fail progressively while maintaining control of the existing openings with the appropriate support. A systematic analysis of rockbursting and caving hazards was conducted for all accesses and stopes in order to plan ground support and instrumentation needs.

May 1, 2003

By Chris Larsen, Ian Orford, Marilene Renaud, Mike Cooper, Lud Strah

"An AG/SAG mill was commissioned at the Brunswick Mine concentrator in October 1998. This paper discusses the original liner design for the bi-directional AG/SAG mill, observed liner wear, subsequent liner design modifications, and benefits. The mill liners consist of steel top hat shell liners, steel end liners, rubber grates and rubber lined pulp lifters.Lifter profile and plate thickness measurements were made on monthly shop days. Trends of wear rates were used to project when liners required replacement. Wear profile information was also used to determine where liner re-design would improve wear life or minimize scrap loss. Charge motion simulation modeling was used as a tool to assist liner design modifications.INTRODUCTIONThe Noranda Inc. Brunswick Mine, located near Bathurst, New Brunswick, is a large underground lead/zinc mine with a nominal production rate of 10,000 tonnes per day. The Brunswick concentrator commenced operation in 1964 with conventional surface crushing followed by rod and ball milling to reduce run of mine ore to the required size to feed two parallel flotation circuits. In 1998 the AG (autogenous grinding) mill was commissioned for a nominal production rate of 9,000 tonnes per day replacing two surface crushing plants, three rod mills and three primary ball mills. In May of 1999 the mining rate was increased and the service of the AG mill was changed to a SAG (semi-autogenous grinding) mill with the addition of 4 inch steel balls (4% volume). The mill operates in closed circuit with 0.66 meter horizontal cyclones to produce a ground product of 90 micron nominal size (K80).The AG/SAG mill liners are steel (Norsteel, chrome-moly steel) with rubber grates and rubber lined pulp lifters.The original liner design was based on studying other AG/SAG mills and recommendations by the liner supplier, Norcast. Design factors taken into account were total cost of lining (including material and labour), protection of mill shell and impact on operating performance."

Jan 1, 2003

By P. Taskinen, D. Lindberg, H. Viitala

The formation of copper chlorides in flue dust or deposits in heat recovery boiler of copper smelters or waste-fired boilers may lead to formation of corrosive partially molten deposits on walls and heat exchangers of the boilers. These deposits can contain various other metals, such as alkalis, Fe, Zn, Pb together with oxides and sulfates. In the present study, a thermodynamic model for copper-containing binary and ternary metal chloride systems within multicomponent CuCl-CuCl2-FeCl2-FeCl3- PbCl2-ZnCl2 system has been assessed and optimized based on own experimental phase equilibrium data, as well as literature data. The thermodynamic properties of the liquid phase was modelled using the quasichemical quadruplet model and a thermodynamic database was optimized to predict all available experimental data within the experimental error limits. The thermodynamic database allows for more accurate predictions of potential corrosion-related issues in various heat recovery boilers and waste-fired boilers due to formation of copper chlorides. INTRODUCTION In the copper flash smelting, flue dust can cause severe problems in the gas train, used for separating dust from the SO2-rich off gas, by forming corroding accretions on the walls of the heat recovery boiler. Formation of dust build-ups in the boiler need to be cleaned regularly and potential corrosion damage checked, requiring costly and unscheduled shutdowns of the flash smelting process. Compounds of copper and zinc among other elements having high vapour pressures may volatilize during the smelting of the copper concentrate, forming dust when the process gas cools down. Also, particles of solid or liquid iron oxides originating from the ore get transported with process gas to the heat recovery boiler as a result of entrainment in the flue gas (Miettinen, 2008) The dust deposit build-ups on the boiler walls are formed partly by direct impact of particles and partly by vapour condensation on the boiler walls. The initial deposition takes place by the condensation of vapours that contain zinc, lead, arsenic and other metals having high vapour pressures. Also, low melting point eutectic components of alkali salts such as chlorides and sulphates can act as sticky cohesive particles attaching to the boiler walls. The fine particles landing on the surface of the porous dust deposit layer react in the SO2-rich atmosphere of the boiler to sulphates. The process gas within the boiler contains SO2, O2, SO3, H2O and N2 that diffuse into the porous accretions to form a stagnant gas layer within the dust deposit structure. The composition of this gas layer may differ greatly from the composition of the process gas that is flowing on the surface of the accretion layer. Locally HCl and H2SO4 are formed and even a reducing atmosphere may exist within the dust deposit layer, allowing new reactions to take place. The local micro-atmosphere may enable metal sulphates to be reduced to secondary sulphides and even metallic components. Within the accretion layer, components may be formed that would not be stable in the gas atmosphere inside the boiler (Miettinen, 2008). This may be the mechanism by which for instance chlorides of Cu, Fe and Zn are formed within the deposit layer.

Jan 1, 2019

By L. Bloomquist, C. Arnoldi

"This paper describes how Automated Mining Systems (AMS) is evolving the state-of the- art in guidance systems for autonomous underground vehicles. The techniques, tradeoffs, and lessons learned from these systems are described, including the safety regime that has been implemented.First generation autonomous guidance systems for underground vehicles relied on infrastructure for the vehicle to follow. However, there are additional costs associated with that approach.The current generation uses a pair of laser range finders as its only guidance sensors. This system uses a minimum of infrastructure, in the form of a redundant system of location referencing. Advanced steering and drive control algorithms are incorporated into this generation of system.The next generation of infrastructureless guidance systems will be based on a 3D vision sensor, which was originally developed for autonomous Mars rovers and is being adapted for underground mining use. Results of early underground field trials are presented, along with a description of this emerging technology."

Jan 1, 2004

By M. W. Grabinsky

Better in situ performance data is required in order to advance the rational geomechanical design of cemented paste backfill systems. A few in situ test programs have been conducted, but these have suffered from too few measurement locations within the stope and have not used enough different types of transducers to fully capture the information of significance. In this paper the important geomechanical design aspects are listed, the underlying physical phenomena are described, and some previous in situ measurement efforts are reviewed. A new approach to in situ measurement campaigns is then described including measurement techniques, locations, and the logistical aspects of mobilizing transducers in an active mining environment. A work-in-progress is used to illustrate the principles and concepts involved.

May 1, 2007

By Ryan W. Ulansky

This paper presents the conceptual design of a magnetically-levitated skip for use in an underground mine. A skip is used to move rock from an underground mine to its surface processing facility. Conventionally the skip is raised and lowered by cables, similar to an elevator. In a magnetically-levitated skip, the cable is replaced with a linear induction or synchronous motor to provide propulsion and levitation. Removal of the cables in a magnetically-levitated skip provides many advantages over a conventional system including the ability: to negotiate corners, to travel vertically in the shaft as well as horizontally to the mining face, and to move a very large volume of material using multiple skips in a small shaft. A magnetically-levitated skip is a safer, more environmentally-friendly, productive alternative to conventional skipping. It has the further advantage to decrease haulage distances for underground vehicles.

May 1, 2002

By David Evans, David Barnes, Robert Raponi

"The Williams Mine processes, on average, 6,450 t/d of gold bearing ore using two parallel grinding circuits, leaching and C.1.P., carbon stripping, electrowinning and refining. At present, each grinding circuit consists of a SAG mill in closed circuit with a spiral classifier and a ball mill in closed circuit with two stages of cyclones.Since grinding has always constituted the largest portion of milling costs, the Williams Mine has been proactive in trying to reduce such costs through innovative changes. One project under consideration is the replacement of one spiral classifier by a vibrating screen.This paper discusses the testwork performed to evaluate the replacement of one spiral classifier by a vibrating screen, and the preliminary engineering performed to date.IntroductionThe Williams Mine, located in northwestern Ontario, approximately 40 kilometres east of Marathon, is part of the Hernia gold camp. The mine is operated by the Williams Operating Corporation and is owned by the Teck Corporation and Homestake Canada Incorporated. Operation of the mine started in October 1985 at a rate of 3,000 t/d. After a mill expansion in August 1988, throughput increased to 6,000 t/d. Production has increased steadily since the mill expansion and in 1995, an average of 6,450 t/d of ore was processed at a recovery of 95.1 %."

Jan 1, 1997

By L. Bloomquist

This paper describes how Automated Mining Systems (AMS) is evolving the state-of-the-art in guidance systems for autonomous underground vehicles. The techniques, trade-offs, and lessons learned from these systems are described, including the safety regime that has been implemented. First generation autonomous guidance systems for underground vehicles relied on infrastructure for the vehicle to follow. However, there are additional costs associated with that approach. The current generation uses a pair of laser range finders as its only guidance sensors. This system uses a minimum of infrastructure, in the form of a redundant system of location referencing. Advanced steering and drive control algorithms are incorporated into this generation of system. The next generation of infrastructureless guidance systems will be based on a 3D vision sensor, which was originally developed for autonomous Mars rovers and is being adapted for underground mining use. Results of early underground field trials are presented, along with a description of this emerging technology.

Jan 1, 2004

By V. I. Lakshmanan

Process Research ORTECH Inc. (PRO), with its in-depth knowledge on cobalt behaviour in nickel matte smelters and its novel mixed chloride hydrometallurgical processing, is developing a hybrid process to enhance cobalt recovery. PRO’s experimental data is compared with plant information on cobalt behaviour in smelters. In final stages of iron rejection in the converters, the thermodynamics of the matte-slag system dictates the undesirable transfer of the cobalt to the final converter slags. This results in much lower cobalt recovery in the product Copper/Nickel matte (<60%) in present copper and nickel smelters. This information is used to transfer cobalt into desired quantity of converter slag. The enriched cobalt slag is subjected to PRO mixed chloride process to recover nickel, and cobalt as high value salts of importance in lithium ion batteries. From a typical converter slag containing 3.5% Ni, 1.5% Co, and 1.0% Cu, PRO leach process extracts 98 % Ni, and 98 % Co, and 99% Cu. Application of this process to enhance cobalt recovery in typical Copper/Nickel smelters is presented. In addition, this will also enhance the Copper and Nickel recovery. Both these aspects are of interest to the Copper, Nickel, and cobalt producers. INTRODUCTION In pyrometallurgical extraction of copper and nickel from sulphide ores cobalt often occurs with copper and nickel. The requirement of cobalt is increasing due to its need in lithium ion cells used in electric vehicles. Therefore its efficient and economical extraction in a form suitable for use in lithium batteries is of great interest at present. In the pyrometallurgical processing of copper and nickel sulphide concentrates the concentrate is smelted to produce a furnace matte, which is then sent for converting to remove the iron to produce iron free (~1% Fe) matte for further processing to copper or nickel matte. The copper/nickel matte is processed for metals recovery by hydrometallurgical or vapo-metallurgical or oxidation – reduction routes to make market products. As shown in Figures 1 and 2 the slags are produced in the smelting step and in the converting steps. The metal losses in smelting are controlled by the oxygen pressure in that step and slag production which is controlled by concentrate grade. The slag produced in the converting step which is carried out at a higher oxygen pressure contains higher level of metals is often returned to the smelting step to increase value metals recovery.

Jan 1, 2019

By A. R. Barnes, N. O. Lotter

Recoverable economic copper sulphide minerals such as chalcopyrite, bornite, chalcocite and covellite often occur together in varying proportions in the major copper-bearing ores, and have individual flotation requirements and characteristics. Pyrite also occurs in these ores to varying extents as the sulphide gangue, and is problematic because of its natural tendency to float quickly and easily. In a bulk sulphide float, selectivity against pyrite is desirable, particularly if it does not host other paymetals such as gold or silver. At the same time it is a requirement to float all of the copper sulphides despite their electrochemical differences. The electrochemistry and semiconductor properties of these minerals are reviewed, together with implications for flotation with and without collector addition. Mixed collector systems for the improved flotation of these sulphides are proposed as a solution. The use of xanthate and dithiophosphate in the collector suite allows the co-existence of dixanthogen and free dithiophosphate radical because the latter has a higher redox potential requirement than xanthate to oxidise to the dithiolate. Because some of these minerals require dixanthogen, and others, free thiolate, to generate surface hydrophobicity, a bulk flotation of all the species becomes possible in the overlapping area of Eh and pH between the two dithiolate equilibrium lines on the Pourbaix diagram. The arsenic-signature copper minerals are added to the study, since many copper operations encounter arsenic as a penalty element in the saleable concentrate. It is shown that the addition of arsenic to the copper and iron sulphides alters the semiconductor and electrochemistry properties, and in turn, its flotation characteristics. The degree of mineral association and liberation between these minerals can be a complicating factor due to textural associations, and should also be considered in the process as a next step.

Jan 1, 2016

By E. H. Smith

"The El Indio mine treats a complex mixture of copper and gold/silver ores at its plant located in the high Andes in Chile. The plant utilizes conventional crushing, grinding and flotation to produce a copper/gold/silver concentrate. Due to high levels of arsenic and antimony, the flotation concentrate must be roasted prior to custom smelting. The flotation tailings is leached and additional gold recovered from a CIP circuit. Present and future metallurgical developments are discussed in this paper. INTRODUCTIONIn late 1989, LAC Minerals purchased 65 % of Bond International Gold and as a result became controlling shareholder of the El Indio Mine through Bond and San Jose.El Indio is a world class, complex sulphide gold deposit located in the hydrothermal alteration belt of the Andes mountains in the 4th Region of Chile. The mine is located in the high Andes about 185 km east of La Serena at an elevation of 4000 meters. The 1450 workers at El Indio live in the mine camp at 3200 m and on days off are bussed to La Serena.The El Indio mine was started in 1979 by St. Joe Minerals Corp., bought by Bond in 1987 and subsequently by LAC in 1989. The mine has produced 2.7 million oz. of gold, 9.5 million oz. of silver and 170,000 t of copper since start of operation. The mill is currently operating at a rate of 2850 t/d and producing a copper/gold concentrate which is roasted to produce a copper/gold calcine and high quality, saleable crude AS2O3 . A small proportion of the precious metals are also produced as bullion from the leach circuit.Total production during 1989 was 224,197 ounces of gold, 1,309,342 ounces of silver and 26,968 tonnes of copper. The average cash cost of production for the period was U.S. $96 per ounce of gold, net of by-product credits. The average realized price was $5. 30 per ounce of silver and $1.14 per pound of copper."

Jan 1, 1991

By Yuanming Pan, Brett Rogers, Baoquan Hu, Gary Yeo, Christine Austman

The nature and distribution of radiation-induced defects (RIDs) in quartz from the Maw Zone, a yttrium- and rare-earth-element-enriched sandstone breccia complex exhibiting intense hydrothermal alteration, have been investigated by electron paramagnetic resonance (EPR) spectroscopy. EPR spectra show that detrital quartz in sandstone, from five diamond drill holes intersecting the Maw Zone and one above the crest of the so-called Quartzite Ridge, contain only background-level RIDs, indicating that Ubearing fluids were absent in this area. However, close to the sandstone-basement unconformity, in hole WR-194 immediately west of the Quartzite Ridge, the concentration of RIDs in detrital quartz is significantly above background but at least an order of magnitude lower than those at the Key Lake and McArthur River deposits. Widespread drusy quartz at the Maw Zone, which signifies intense hydrothermal alteration, is associated with hematite-, sulfide- and carbonate-bearing mineral assemblages, which exhibit complex crosscutting relationships. EPR spectra of drusy quartz in all three types of mineral assemblages are low in RIDs as well, supporting the EPR evidence that fluids at the Maw Zone did not carry significant U. These EPR results suggest that, in spite of intense hydrothermal alteration and favorable structural geology, the Maw Zone is unlikely to host any significant U mineralization. Moreover, this study shows that the EPR technique is potentially a useful exploration tool, capable of determining whether individual alteration zones in the Athabasca Basin were associated with U-bearing fluids or not.

Jan 1, 2013