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By S. C. Bouffard

Barrick's Zaldivar operation in Chile produces copper by heap leaching, solvent extraction, and electrowinning. The heap consists of a dynamic pad, and its stacking and operating conditions have changed over its 11 years of operation. These changes have included pad re-mining midway through the cycle, tightening of the irrigation drip lines, an increase of the coarseness of the particles, and an increase of the heap height. This paper reviews the heap operating data to understand the effects of these changes on the kinetics and recovery of copper minerals. Field tests demonstrated that neither re-mining nor tightening the irrigation grid added value for both low and high grade oxide and sulfide ores. The P80 of the feed ore was increased by 0.8 mm, which did not reduce the copper recovery of oxide and sulfide ores. The increase of the heap height above 8 m lowered moderately the copper recovery from sulfide minerals, and very slightly the recovery from oxide minerals. Despite the lower recovery, the higher tonnage stacked in the taller heap increased the copper output. Optimizing the chemistry of the agglomeration and feed solution holds more promise for increasing the copper recovery than the above physical changes.

Jan 1, 2007

By DALE MacGREGOR, VERA TUREK

lndusmin Limited acquired the St. Donat quartzite deposit in 1967 to produce high-quality silica for use in the sandblasting and silicon carbide industries. The quartzite, of Grenville age, is highly friable and porous. This is due to numerous small, kaolinite-coated cavities in the quartzite; the cavities were formed through leaching, probably by rising hot solutions.

Jan 1, 1984

By Robert B. Parsons

"""I would be a rich man if I had a dime for every man hour spent by the bureaucracy on changing tax legislation."" Anonymous.The mind of a cynic might very well conjure thoughts about ""change for the sake of change"", given the protracted saga of federal sales tax reform in Canada. The latest chapter unfolded this summer when the Commodity Tax Review Group released its important report. Whatever sales tax changes, if any, are finally adopted will have profound effects on many aspects of doing business. The capital-intensive mining industry will not escape these effects.IntroductionThe Federal Sales Tax Review Committee, established by the Minister of Finance earlier this year, has published a report that is sharply critical of the government proposals to shift the incidence of federal sales tax from the manufacturer level to the whole sale level (sales to retailers). The Report recommends a continuance of the present manufacturer's tax, for the present, but with significant changes that would increase the tax cost on certain imports, smooth the administrative machinery and make appeals and determinations more open and equitable. For the longer term, the Report recommends a shift of the tax base to the retail level.Reform of the federal sales tax system has been under consideration for several decades. Briefly the history is as follows: 1940 Report of Rowell-Sirois Commission-proposed the eventual elimination of federal sales tax1956 Report of Federal Sales Tax Committee-proposed a shift in tax from manufacturer to wholesaler level1966 Report of Carter Commission-proposed shift to a retail tax1975 Discussion Paper on Federal Sales and Excise Taxation-concluded that retail tax conceptually best but provincial agreement/administrative problems present a major hurdle-proposed wholesale tax as best practical approach1977 Report of Commodity Tax Review Group"

Jan 1, 1983

By M. Maeda, H. Sasaki

Dissolution characteristics of metals vary significantly when they form alloys with other elements. Because hydrometallurgical processes are essential in separation and refining of non-ferrous metals, it is important to study behaviors of alloys in aqueous solutions. The authors have studied dissolution characteristics of precious metals in acid solutions using electrochemical measurement. When precious metals are alloyed with Zn, its dissolution is promoted by an increase in surface area caused by the preferential dissolution of this metal. The electrochemical study also revealed that precious metals dissolved from some alloys at unusually negative potentials; the underpotential dissolutions are explained by activations of these metals in the dealloying.

Jan 1, 2014

By N. Plint, M. Potgieter

The Anglo Platinum Mogalakwena North concentrator was one of the first three hard rock mineral processing applications to utilise a HPGR circuit in preference to a SAG milling circuit. This was driven by the extreme competence of the ore that had given rise to throughput issues on the original South Plant. Despite more than adequate capacity and performance of the individual comminution units, the circuit has struggled to obtain full design capacity. A thorough review of the integrated performance of the circuit revealed a wide range of bottlenecks and underutilised parts of the circuit arising from design issues. Interestingly, the major opportunities lie in materials handling issues and mismatch of loads about the circuit. This paper presents the high-level outcomes and the associated opportunities, and is pertinent to all HPGR circuit designs.

Jan 1, 2012

By A. E. Reschke

Optimized mine planning of the Leeville Gold Mine, Nevada, necessitated the requirement for an average of 2540 tpd of high quality cemented rockfill (CRF) in primary stoping blocks and underhand cut and fill workings. To meet this requirement, a number of innovative design features were incorporated into the overall batching plant design. Foremost is the use of a dedicated skip to transfer crushed aggregate from surface down through the ventilation shaft to twin underground storage silos. Also, the use of a high shear colloidal mixer on surface to pre-slurry a cement/flyash binder with pipeline delivery to one of two separate underground CRF mixing stations was incorporated. Finally, the binder and aggregate are combined in a 9 m3 twin shaft compulsory type mixer before loading into teleram trucks for placement.

May 1, 2007

By M. Sakamoto

Copper foil is an indispensable material for Printed Circuit Boards (PCBs). PCBs in turn are essential elements of all electronic equipment today and thus important for our living in the new age of IT. The requirements from the copper foil market have lately been increasingly strict and diversified due to the rapid technical advancements in miniaturized high-density electronic equipment and highly integrated semiconductors. Tight control of thickness, metallurgical properties, surface morphology and characteristics is needed. In this paper, both electrodeposited copper foil for PCB and rolled copper foil for the flexible printed circuit board are discussed, and the recent technical developments in these copper foil products are reviewed.

Jan 1, 2007

By John Keay, Douglas R. Shaw, Gregory J. Olson

"The results are presented herein of on-going laboratory investigations of heap bacterial oxidation as a pretreatment method for the recovery of sulfide-encapsulated gold from ore samples of the Rhodes Mining Lahoca deposit, located in northern Hungary. The ore contains just over 2 g Ault and as much as 6% sulfide, mostly as pyrite. Laboratory aerated column tests conducted at Colorado Minerals Research Institute (CMRI) showed that mild to moderate biooxidation of the finely crushed ore occurred rapidly in approximately three months, with cyanide gold recoveries of up to approximately 60%. The results contrast cyanide gold recoveries of less than 30% from non-pretreated ore. Mineralogical examination of biooxidized residues indicated that the mechanism of biooxidation of crushed ore was related to microorganisms following pathways along structural anomalies in the pyrite grains. Such selective biooxidation is an important result to minimize the biooxidation and aeration time and effluent neutralization costs in a commercial operation.IntroductionThis paper describes the development of a heap biooxidation process for the Lahoca gold project The Lahoca deposit is situated in northern Hungary, at the site of a former copper mining area. Lahoca is a large tonnage, relatively shallow, deposit amenable to open-pit mining Lahoca has the potential to produce I 00,000 ounces of gold annually for at least ten years at its minimum reserve base.The laboratory test work conducted initially by Rhodes Mining NL demonstrated that the Lahoca refractory ore is amenable to whole ore and concentrate oxidative pretreatment and cyanidation. Capital and operating costs, however, for such milled ore treatments were considered relatively high. Rhodes Mining subsequently evaluated heap leaching methods, particularly heap biooxidation pretreatment, as a process route that promised superior economics suitable for exploiting lower gold grade refractory ores.This paper focuses on the laboratory column (simulated-heap) biooxidation test work, particularly the proposed mechanism of selective microbial oxidation, wherein only a small amount of the sulfides are oxidized sufficient to allow commercially acceptable gold recoveries by conventional cyanide heap leaching. Selective or minimal biooxidation of sulfides is considered important to minimize biooxidation time and aeration requirements, as well as acid effluent neutralization costs."

Jan 1, 1998

By Bruce W. Downing, Philip G. Claridge

"The availability of environmental data is a major concern in the development of an exploration project through the permitting and feasibility stages. The collection of these data should ideally start very early in a major exploration program. Although a large proportion of the environmental data can also be used for exploration purposes, (e.g. stream-sediment, soil, and rock analyses), environmental sampling will rarely have been initiated at an early date. For the Windy Craggy project, a major environmental concern is the potential for generation of acid rock drainage from waste-rock piles. The project is reviewed with respect to the environment of the deposit, deposit geology, mineralization and reserves, the sequence of exploration activities to the present, the potential for the development of acid rock drainage, the geochemistry and water quality, and the integration of exploration and environmental databases and their application to environmental planning. IntroductionIn the classical sense of exploration of a mineral deposit, the efforts throughout exploration are routinely directed at confirming the existence of the deposit and defining its extent, grade and continuity. Environmental issues are usually tackled separately, possibly by different personnel at a later date. When that is the case, an opportunity is lost to build, from an early date , a comprehensive database that (I) will satisfy the needs of conventional exploration and environmental monitoring, and (2) is usable as a predictive tool for environmental impact assessment.The concept of environmental geochemistry is not complex. The availability of environmental data is a major concern in the development of an exploration project to the feasibility and permitting stages. The collection of data should ideally start very early in any major exploration program. In many cases a significant proportion of the geochemical exploration data gathered early in the life of a project will also be used later for environmental purposes (e.g. stream-sediment, water, soil, and rock analyses). Rarely, however, will the data gathered in a geochemical exploration program provide information as complete as that attainable if environmental objectives had been considered in scoping the work.A knowledge both of local and regional geochemical processes can lead to a better understanding of environmental impacts. This understanding is the basis upon which good environmental management practices may be built. Geddes Resources Limited has undertaken a major study of the natural environment in the Windy Craggy area which includes geology, surface and underground waters, soils, stream sediments, glaciers and geomorphology (Geddes Resources Limited, 1990). This paper deals with the building and integration of the exploration and environmental databases."

Jan 1, 1993

By P. Espinoza, I. Yutronic, J. Olivares

"Compañía Minera Doña Inés de Collahuasi's (CMDIC) Concentrator Plant is located at 4300 meters above sea level, approximately 2000 kms north from Santiago, Chile. The concentrator has three grinding lines. Each one, Lines 1 and 2, have one SAG mill at the primary grinding stage followed by a secondary grinding and classification stage consisting of one ball mill, two hydrocyclone batteries and a sump with two pumps. Line 3 has one SAG mill (Gearless Mill Drive), followed by a secondary grinding and classification consisting two ball mills, four hydrocyclone batteries and a sump with four pumps. Average throughput for these three lines is 150 Ktons per day. Peak values of 180 ktons per day have been achieved.Since late 2008 and throughout 2009 and 2010, Operations and Automation areas developed an optimization program for the grinding process, considering the implementation of Model Predictive Controllers (MPC) for the three SAG mills, and later, extending MPC to the secondary grinding and classification stages. The implementation of a MPC solution was based on stability considerations (high variability of the SAG process, high interaction between sump level control and classification efficiency, etc), requirements for an automated and consistent operation, the need to maximize throughput under timevarying scenarios and, in the long term, optimization of grinding process considering Specific Energy Consumption, among other parameters. MPC solutions had proven control robustness and strong optimizing capabilities in terms of helping in discovering new operational points and so achieving all of the aforementioned goals.On the first stage of the program, MPC implementation considered identification of dynamical process control models based mainly on historical data, in order to know the impact of a group of Manipulated Variables over Controlled Variables. Also, the impact of measured Disturbance Variables was modeled in order to take into account the high impact and interaction of these variables over the processes. At the end of this stage, 4 controllers were successfully operating for the 3 SAG mills and the secondary grinding and classification process. In response to challenges made by the working group, the second stage of the development of control applications in the grinding process required to achieve a design and implementation of a solution capable of governing the milling process, in addition to stabilization and optimization of both processes (SAG milling and secondary grinding), to integrate from a point of view of process control and automation. Therefore, in the second stage, MPC performance was continuously monitored and optimized through advanced tuning, inclusion of more process models (with proper step tests), redefinition of specific optimization criteria and adjustment to new process needs.Finally, successful MPC implementation at Collahuasi has proved that fast development and deployment of process control solutions is possible and allows immediate process stability, higher throughput, specific energy consumption reduction, and successful product size control, among many others."

Jan 1, 2012

By Raynald Vézina, Richard Leclerc, Jean Boissonnault, Louis P. Gignac, Gérald Veillette

Since mid-1989, Cambior has increased its producing gold mines from four to six, having acquired the Chima Mine and brought the Silidor Mine onstream. In June 1990, the company announced that the Mouska project would also be put into production. Gold production reached almost 190 000 ounces in 1989 and is expected to exceed 220 000 ounces this year. Cambior has also a non-gold operation with an interest of 50% in the Niobec Mine and has recently signed an option agreement in the development of the Lac Knife graphite deposit in northeastern Quebec. During the past year, the company has extended its exploration activities to the United States and Indonesia, and now has interests in nearly 80 properties. Last May, Cambior signed an option agreement with Golden Star for a gold deposit in Guyana, the OMAI Project, containing at least 2 000 000 ounces of gold in situ.

Jan 1, 1990

By w. w. Fraser

"In late 1985, Hudson Bay Mining and Smelting Co., Limited announced the Namew Mine/Mill project. Environmental baseline monitoring and planning began in early 1985 while a major drilling program was under way to delineate the ore deposit. This paper overviews the environmental assessment work conducted for the mine/mill operation, and outlines the tailings and water management practices.Planned environmental works and approach were affected in late 1988 when a massive water problem was encountered in the mine. The requirement to depressurize the rock surrounding the underground workings led to the need to develop, on short notice, an environmentally-acceptable procedure to dispose of a large volume of slightly-saline water.Biological toxicity tests performed on the depressurized effluent proved the effluent to be non-toxic and thus allowed resolution of the disposal problem. This resolution includes the conversion of a large water body from native fish species to a rainbow trout fishery."

Jan 1, 1991

By A. P. LeBis

This article attempts to relate the concept of utility to the risk involved when only a small number of projects (compared to their probability of occurrence) are accessible to a firm and to quantify utility when other financial and physical parameters are known.

Jan 1, 1978

By S. Orzecki

The KGHM Copper Refinery Plant, Glogów 1, has operated for 35 years and -increased its capacity almost ten times.Cathode quality, expressed in terms of the total impurity content, has undergone a five-fold improvement. The present refining capacity is equivalent to 240,000 metric tonnes of copper cathode, with a total impurity content of 20 ppm, inclusive of 10 ppm Ag. These accomplishments result from combined implementation of current technological progress in electrolytic refining and KGHM's own solutions applied to the Glogów Refinery. The quality improvement measures feature both lowering actual current density, despite an increase in nominal current density, and diminishing the role of non-ion mechanisms which transfer impurities to cathodes. The paper contains a detailed discussion of these issues and outlines possible measures aimed at further production and quality improvements.

Jan 1, 2007

By R. Ramirez

Atlantic Copper Refinery (Huelva, Spain) has operated the ISA permanent cathode technology since 1995. The current production rates are 260,000 t/y cathodes and 730 t/y anode slimes. These slimes undergo an atmospheric leaching in which their copper content is reduced from an average value of 24 % to 16 %. In June 2005 an optimization study of the leaching conditions was carried out aimed at lowering the copper content in the slimes to less than 8%. At the same time, a new mixer (Outukumpu Technology GLS-mixer) was installed in one of the three leaching reactors. As a result of the improvement of the leaching performance and to prevent the return of tellurium to the tankhouse, a cementation plant was commissioned in July 2005 to ensure a Te content below 50 ppm in the Cu-rich leachate. This paper describes the results of the improvement of the leaching conditions and the operation of the new tellurium removal plant.

Jan 1, 2007

By D. M. Xue, T. B. Li

"With the increase of human engineering activities, global climate change and active plate tectonics movement, the giant landslide frequently occurred in southwest China, which caused huge property and human losses. Besides, the potential landslides pose severely threaten to the construction and operation of airports, railways, highways and power stations etc. In order to provide accurate guidance for the landslide investigation, stability analysis and mitigation, the giant landslide is redefined according to landslide volume, depth of slip surface, complexity of landslide mechanisms, and degree of landslide mitigation difficulty, and classified with the typological classification approach based on the twofold attributes of landslide behavior including formation mechanisms and reactivation features. Finally, the threefold particularity of the giant landslide is also summarized, which enables a more effective landslide mitigation design.INTRODUCTIONWith the increase of anthropogenic activities, global climate change and active plate tectonics movement such as continual uplifting of Qinghai-Tibet plateau and strong earthquakes, the occurrence of giant landslides was in ascending trend in southwest China (Huang, 2009), which caused serious destruction, and greatly endangers such engineering construction from safety, time and economic aspects as airports, railways, highways, power stations, etc. Giant landslides have huge scale, complex formation/reactivation mechanisms and mechanical behavior. They may not be identified during the hazard investigation, but may be firstly initiated or reactivated due to the following engineering activities, heavy rainfall or strong earthquakes. Consequently, the landslide mitigation is inevitable and costly. However, it is difficult to control the deformation of giant landslide with lack of a correct understanding of genetic mechanisms (Marui, 2012; Zhang, 2000) and the excessive large sliding forces of the slide blocks calculated by the conventional limit equilibrium method. For instance, the failure of anchored pile wall for the No.102 giant ancient landslide (Zhu et al., 2012) and stabilization measures for the Sidi Rached viaduct landslide(Guemache et al., 2011); four rows of piles had not prevented the occurrence of the No.12 landslide in a high fill slope in the Panzhihua airport (Li et al., 2012)."

Jan 1, 2015

By S. Balideh

A good understanding of the behavior of broken rock helps to make more informed decisions regarding slope stability and waste dump issues in mines. The cohesion coefficient of rock has little influence on the strength of broken rock; therefore, a criterion based on friction and cohesion of intact materials does not provide an accurate analysis for the strength of broken rock. This paper illustrates the effective strength of broken rock through a brief literature review about failure of intact rock and rock masses. The complete stress- strain curve and some important points of residual strength of rock are summarized in this paper.

Jun 1, 2012

By G. F. Raymond, W. P. Armstrong

"At the time of this study, the Valley mine was producing 23 000 tonnes of ore per day from a large, low-grade porphyry copper orebody. Sulphide mineralization, principally bornite and chalcopyrite, occurs in a stock work of quartz veins in one phase of the Guichon Creek batholith. The property was explored from 1967 to 1982, and was placed in production in 1983.Using a three-parameter lognormal approximation developed by G.F. Raymond at Similkam een and Mount Isa Mines, a geo- statistical conditional probability ore reserve was estimated prior to mining. Comparisons with blasthole kriging and milled ore for the first 17 months of production showed close agreements at all cut-offs between conditional probability estimates and mineable ore. This was not true of either kriging or polygon estimates. An important part of this work was identifying and correcting for bias in both exploration and blasthole samples.IntroductionCominco's Valley lake deposit is a large, low-grade, porphyry copper orebody in the Highland Valley of British Columbia. Total indicated plus inferred ore reserves are 700 M tonnes at ore grade of 0.47070 Cu. At the time of writing, ore milling is at a rate of 23 000 tI d through the old Bethlehem mill. Mining is in 10m horizontal benches using 9.8 m3 shovels and 90 tonne trucks. Since this paper was written, Valley and nearby Lomex have been combined into Highland Valley Copper with a combined oreproduction of about 120 000 tI d.Copper mineralization, principally bornite and chalcopyrite, is regularly distributed throughout the deposit as disseminated low-grade within a granodiorite host rock, and as higher grade veinlets within a stock work of near-vertical quartz veins generally 10 cm or less in width. It is likely that problems with sample variability and sample bias are mainly related to mineralization within quartz veining. Valley geology has been described in detail by Allen and Richardson and by Osatenko and Jones (2). The exploration sampling program and identification of diamond-drill sample bias have been discussed by Armstrong and Newman'»."

Jan 1, 1988

By M. K. Senicie

IN July, 1937, Asbestos Corporation, Limited, installed an automatic conveyor-belt scale at their King mine, Thetford Mines. The equipment was purchased 'on trial' and its performance has proved entirely satisfactory to the staff. The scale was manufactured by the Toledo Scale Company, of Toledo (Ohio) and Windsor (Ont.) and was installed by one of the Scale Company's engineers. The electrical recording equipment was installed by Keith Mercer, Reg'd, of Montreal, Canadian agents for the manufacturers, the Builders Iron Foundry, of Providence, Rhode Island. The recording equipment consists of a duplex weight-transmitter attached to the scale-head, a duplex totalizer with differential relays, a belt-speed compensator, a rate-of-delivery recorder, and a rate-of-delivery indicator. As it was desired to run the mill at maximum capacity, it was necessary to know the rate of feed at all times, so that any lessening of rate of feed or delays would be recorded and could be corrected. After having determined the rate of feed to the mill (100 per cent capacity), it was required to have weighing and recording instruments which would show: (1) The rate of feed per hour. (2) Any variations .in the load. (3) Any delays and the duration and time of the delays. Rate of tonnage recorders in the mill superintendent's office and at the point of feedi.ng were necessary, as was automatic control between the mill superintendent and the feed man. It was desired to have a permanent record of total tonnage fed per shift or day; weighing and recording mechanism had to have sensitivity to record all previously mentioned conditions. Mechanism had to be of rugged construction, and be so built that it would stay in good operating condition, with the minimum amount of adjustment and supervision.

Jan 1, 1938

By T. Guan, G. Fu, X. Zhou, L. Deng

"One kind of tailings from gravity separation of polymetallic mine contains 0.5–0.8% SnO2. The proportion of –0.037 mm size fraction of the tailings is 37.12%, and the distribution rate of SnO2 is 60.32% in it. For this tailings, two processing technology was carried out. One was felt-shaking table gravity separation in which the concentrate with a grade of 30% SnO2 at a recovery of 10% was obtained. Another was flotation-gravity separation in which the concentrate with a grade of 51.20% SnO2 at a recovery of 51.69% was obtained, but the dosage of collectors was as much as 990g/t. Therefore, the experimental research on the influence of grain size composition on the cassiterite recovery were conducted. The results show that: (1) the flotation recovery of the cassiterite distributed in +0.043 mm size fraction is only 10%, flotation recovery is not suitable for it; (2) a portion of cassiterite distributed in –0.01+0.005 mm size fraction could be recovered by flotation, but the tin flotation performance will be worsened rapidly and the dosage of collectors will be increased due to the increase of the content of –0.010 mm size fraction; (3) flotation processing is not suitable for –0.005 mm size fraction of the tailings. According to the results, a new technology has been carried out, that is discarding tailings by gravity separation-hydrocyclone desliming-flotation-gravity separation processing flow. The processing index is close to that of the flotation-gravity separation processing flow, and the collector dosage is decreased to 360 g/t by this processing technology. And, it has been achieved that the cassiterite slime is recovered economically and reasonably.INTRODUCTIONAs the density of cassiterite is higher than that of gangue, gravity separation is considered to be a low cost, pollution free, and effective process for cassiterite recovery (Wills, 2009). However, cassiterite is a kind of fragile mineral, over crushing is easy to take place and a large amount of slime is inevitably produced in the crushing and grinding of cassiterite. For the cassiterite slime exists in –0.043 mm size fraction, the efficiency of gravity separation decreases sharply. The production practice shows that, for the fine cassiterite, the recovery of tin exists in –0.043 mm +0.010 mm size fraction is about 13% through shaking table gravity separation, and the tin exists in –0.010 mm size fraction is almost impossible to be recovered by gravity separation. If flotation is adopted to recover fine cassiterite, the problems of high reagent dosage, high cost, environmental pollution, and poor economic benefit would take place. Therefore, the recovery of cassiterite slime is a worldwide problem. A key way to increase the utilization of tin resource and increase the economic benefit of tin mines is developing suitable beneficiation process for fine cassiterite."

Jan 1, 2016