Search Documents

By H. E. Urtubia

"BHP-Billiton’s Minera Escondida Limitada, in Chile, is one of the world’s largest copper producers. It treats a combined 10,500 tph of copper ore through its two concentrators: Los Colorados and Laguna Seca. The performance of the rougher circuit at each concentrator was measured and analysed using the JKTech flotation optimisation methodology. This involved developing a flotation model for each concentrator based on cell operating parameters (for example bubble surface area flux and froth recovery) and feed ore floatability characteristics. The rougher circuit performance was evaluated in terms of traditional measures, such as grade and recovery. The operation was also analysed using the measured cell operating parameters and ore floatability and the effect of these with regard to performance (grade / recovery) was assessed.This paper presents a comparison of the rougher circuit at each concentrator in terms of these parameters. The main differences in rougher circuit performance between the two plants were attributed to differences in feed ore floatability characteristics and froth recovery. The comparison highlighted opportunities where performance improvements could be made. The study also showed the usefulness of separating the flotation process into easily measurable subprocesses to further identify the different mechanisms occurring in each rougher circuit. Traditional measures like grade and recovery are useful for monitoring flotation operation but this data lacks the depth to determine the root cause behind operational issues. Determining the operating parameters and ore floatability provides the operating plant metallurgist better tools to assess and manage these issues."

Jan 1, 2006

By G. C. McKerrow

"Mr. G.C. McKerrow, Assistant Manager of Noranda Mines and formerly Smelter Superintendent attended the meeting to answer questions as to why smelters imposed penalties for too much zinc in a copper concentrate or too much copper in a zinc concentrate, etc.D.W. Bridges -Mattagami Lake MinesWhat limits do you set on zinc and lead in a copper concentrate?G.C. McKerrow - At Noranda, we allow 5% zinc free and charge 25 cents for every unit above that. For lead, it is 1% free and 25 cents per unit above that. Lead is a much more harmful impurity than zinc because it tends to recycle more in the smelter circuit and creates a greater health hazard in the plant.E. Thornton - Sullivan GroupWHat harm does fluorine do in the smelting process?G.C. McKerrow - Fluorine usually does not occur in harmful concentrations in non-ferrous smelters. Fluorides are present in exhaust gases in the aluminum and phosphate industries. If these fumes escape into the atmosphere, they may settle out on forage grasses in concentrations that are harmful to livestock.Thorton - Sullivan GroupI have asked this question other places and have been told that it is hard on brick linings and causes gold and silver to be lost up the stack.G.C. McKerrow - Almost any volatile constituent in a smelter charge will aid in carrying other metal values. To this extent it may be harmful.E. Thornton - Sullivan GroupMr. Tait mentioned before a smelter where they have a copper-tin ore and they pay for copper, tin, bismuth and silver but object strongly to indium in the concentrate. Why would this be?G.G. McKerrow - 1 can't see why indium would be a serious impurity. It does tend to concentrate in flu dusts and if you get enough of it you can recover it and sell it but I have never heard of anyone putting a penalty on it.Question - I once ran into a small copper mine in Peru that had cadmium in the copper concentrate but no zinc. The copper smelter charged a penalty for the cadmium. Why would this be?"

Jan 1, 1971

By Philip A. Dirige

This paper presents the variability of responses of paste backfill specimens that have been prepared with varying binding agent and binder combinations, when subjected to uniaxial compressive strength testing. A testing program conducted for an underground operating mine to produce cost efficient paste fill recipes using four different binding agents, in various ratios and combinations, is presented to illustrate the responses. These binding agents are Normal Portland Cement Type-10 (NPC T-10), oxidation or sulphide attack resistant binder (Binder A), replacement binder B (Binder B), and replacement binder C (Binder C). The paste fill recipes were prepared at 2, 3.5 and 5% binder content at varying binder combinations, at fixed size and tested in a Material Testing System (MTS) under constant strain rate conditions following cure times of 7, 14, 28, 56, 90, 112, 180 and 240 days. The results of tests suggested that the strength data clearly shows a trend of increasing strength with increasing binder content but not necessarily cure time. It is noted that all the blends achieved dramatic increases in strength up to 28 days of cure and then either increased or decreased moderately beyond 28 days curing, depending on the binder content and binder combination. The moderate decrease is apparent for the 2% paste fill blends and in some binder combinations of the 3.5 and 5% blends, which indicated lackluster performance beyond 28 days curing. This lackluster strength performance indicated that the binder content and combination may not be sufficient for the paste fill to achieve complete hydration and acquire adequate strength performance beyond 28 days. This study indicated that economic paste fill recipes can be designed with confidence using affordable alternative binders. However, it is noted that these alternate binders cannot be used as stand alone binders but should be used in combination with NPC to facilitate hydration of the paste fill.

May 1, 2006

By Christian Ottergren

"Modern crushers offer double the capacity and performance of classic models. In some cases crushers are replacing SAG circuits, the advantages being smaller investment and lower operating costs. Is Tertiary crushing replacing SAG milling as the most optimal grinding method? Does tertiary crushing achieve the same outcomes as SAG milling? This paper considers these questions and provides an assessment of the strengths of tertiary crushing in comparison to other methods. Two case studies: a Scandinavian Platinum Project, and CODELCO, are also presented.INTRODUCTIONResearch on basic parameters in crushing started at Chalmers University in 1993. The initial project has developed and now involves several related areas. Modelling in accordance with new theories has resulted in modified designs which have been implemented and shown improved performance at operating mines in Chile. Sandvik Rock Processing is a partner and a major supporter of this program. This paper will cover some of the achievements and give references to the research reports.The mining industry has for many years mainly used crushers of the traditional 7’crusher concept, with thread adjustment of the setting and with a spring or hydraulic overload system. This machine type has been the workhorse for crushing throughout the world. The explanation for the dominance of this machine is that it has a reliable mechanical design. It can be estimated that about 2000 crushers of this design are still at work.Technical development in all fields utilizes new technologies like high-strength materials, advanced control systems and more extensive use of hydraulics. This is the reason why today’s motorcars, for example, are more efficient, more reliable and more environmentally friendly than their predecessors in the 1950s. Crushers are no exception. This paper will cover experience from the latest-generation cone crushers developed by Sandvik Rock Processing.The parts in this paper related to the CODELCO ElTeniente copper mine in Chile are coauthored with responsible personnel from the operation at the mine."

Jan 1, 2004

By Kjell Winther

"Hydralift Scanmec introduced early in the eighties a new and different mill design for very large grinding mills. The design described has actually no size limitation upwards and is so far suggested with motor power up to 40 MW. The mill is furnished with gearless ring motor drive transmission. It is totally fabricated, without heavy castings. The first installation, an 8, 1 MW ball mill dia. 6,5 m x 9,65 m length, has been in continous operation in 13 years without problems. Total grinding costs has been reduced with 3 0% compared to traditional smaller mills. Reductions has been achieved in maintenance cost, power consumption, liner wear and grinding media consumption.So far 3 ball mills of the described design are delivered and in operation, one grinding Iron ore and two grinding Nickel ore.IntroductionThe design of mills for mineral ore dressing has basically been unchanged since grinding in mills started some I 00 years ago, in spite of the fact that mills have grown larger and larger. This has resulted in structural and mechanical problems, causing expensive failures and loss of production.Hydralift Scanmec engineers were designing mills for more than 20 years according to the old «rules». As they experienced interest for an increase in the mill size at the time when reports about failing mills were published, they started analyzing the different mill parts to find new solutions. One goal was to only use elements from proven technology in the new design. Two key items were ring motor (wrap around motor)(Isch et al. 1977, Meintrup and Klein 1982, Ranze 1983) and large diameter pad bearings (wrap around bearings)(Fuller 1984), both acknowledged from other industries."

Jan 1, 1995

By M. Tarvainen

"Lately, the development work in closed circuit grinding has mainly been focused on mills and on different types of instrumentation, mathematical models and automation in spite of the fact that the poor efficiency of the classifier is well known. It has also been proven by several investigations that by improving the sharpness of classifier separation, remarkable technical and economical advantages can be achieved. Some attempts to improve the performance of the most common classifier, hydrocyclone, have been made, among them injection of wash water above the spigot cyclone and retreatment of either or both of the products of the primary classifier. No method has been successful enough to achieve general adoption in the industry. The purpose of this paper is to introduce some industrial results achieved by two-stage classification where the coarse product of the turbulent-flow classifier, hydrocyclone, is cleaned in a laminar-flow cone classifier.The main target of the adoption of the two-stage classification circuit it naturally to improve the sharpness of size separation. This again leads to the following advantages in the grinding process:- lower circulating load and increased capacity- lower energy consumptionnarrower size distribution in the fine product- less overgrinding and less slimes- reduced specific surface areaThese improvements, no doubt, reflect on the subsequent concentrating process in the following aspects:the rate of flotation is improved, less reagents and energy is neededthe recovery and grade of valuable minerals in concentrates is improved- savings in dewatering can be expected- less fines in tailings improve the conditions for water recirculation."

Jan 1, 1980

By Mohamed Ourriban, Yongjun Peng, Qi Liu, Denis Cotnoir

"In the flotation of fine particles, there are two difficulties in general: low recovery of valuable minerals and high recovery of gangue minerals. The low recovery of fine valuable minerals is attributed to low bubble-particle collision and attachment efficiencies, while high recovery of fine gangue minerals is attributed to mechanical entrainment through water films between gas bubbles. Over the last five years COREM has been actively developing fine particle flotation techniques with the objective of improving fine particle flotation separation efficiencies.The fine particle flotation techniques with both generation of micro bubbles and enlargement of sizes of fine particles have been developed to increase bubble-particle collision efficiency. For oxidized fine sulphide minerals, both physical and chemical techniques have been developed to modify the hydrophilic surfaces and therefore increase bubble-particle attachment efficiency. To reduce mechanical entrainment of fine gangue minerals, a new approach, polymeric depression and flocculation, has been developed. By selecting the high molecular weight polymeric depressants to make fine gangue minerals hydrophilic and also enlarge their sizes, entrainment can be minimized. By combining these techniques, we are able to improve both flotation recovery and selectivity in some fine ore flotation systems.INTRODUCTIONWith depleting mineral resources and their declining grades, ores leaving grinding circuit for froth flotation are becoming increasingly finer to achieve mineral liberation. Together with the increasing demand for minerals, ever-increasing tonnages of fines are being produced. Therefore, flotation of fine particles is an immense challenge to be tackled by researchers all over the world today."

Jan 1, 2006

By J. W. Austin

"Introduction The Brenda dust collection system was originally designed to handle air at the 5000 ft. elevation with less than 1 grain of dust per cubic feet of air handled. The temperature variation is from 32°C in the summer to -20°C in the winter.DUST COLLECTIONOriginal Equipment 1. Primary Crusher 2 compartment baghouse, shaker type design capacity - 17,000 cfm2. Primary Screening 3 compartment baghouse, shaker type design capacity - 30,000 cfm3. Secondary Crusher 4 compartment baghouse, shaker type design capacity - 45,000 cfm4. Secondary Screening 4 compartment baghouse, shaker typedesign capacity - 60,000 cfmThe original dust collecting equipment was designed using a napped terylene fabric at an air to cloth ratio of 5:1. The ducting was designed to handle the dust laden air at 3200 ft. per minute with all elbows and blast gate sections rubber lined. The hoods and the pickup velocities were designed to handle the anticipated low dust counts."

Jan 1, 1976

By Karl Hoover, Cassandra Spence, Brent Bachewich, Jaakko Levanaho

"Since year 2000 the gold recovery into copper concentrate at Hudson Bay Mining and Smelting has reduced considerably during the summer months. This initiated a testwork program in the fall 2003 to find reasons and solutions for such change. During the testwork mineralogical factors, water quality effects and different reagents were evaluated. The reason for the lower recovery appeared to be the sensitivity of some collectors to pulp temperature. As a result of the work different collectors are being used in the mill in the summer than in the winter. A modification to the water system was also made to provide cooler water to the mill in the summer months.INTRODUCTIONHudson Bay Mining and Smelting (HBMS) is located in Northern Manitoba, just on the border of Manitoba and Saskatchewan. The complex consist of four different mines, Callinan, Trout Lake, Konuto Lake and 777 mine including copper smelter and zinc hydrometallurgical plants producing metallic copper and zinc. Gold is a very important byproduct providing about 30% of the mine revenue. In early 1990s when the company was facing declining ore reserves and was starting to gradually close down the operations, the 777’th exploration drill hole discovered a new orebody, which initiated a $0.5 billion expansion program. The main projects were a new 777 hoist with underground development and a new zinc cell house. About $30 million was used to increase the mill throughput to the present 2.27 million tonnes or 2.5 million short tons per year. The expansion programs were finished by the end of the year 2003.Historically the gold recovery at HBMS has varied between 60 and 70%. The recovery has been somewhat lower during the summer months. Gold recovery improvement projects were conducted throughout the 1990s, but were not focused on the seasonal gold recovery variance. However, since 2000, when the water system modifications to meet the increased water demand were completed, the gold recovery during the summer has been much lower than in the past. In August 2003 gold recovery fell below 30%, which initiated a metallurgical research program to discover the reasons behind the low gold recovery in the summer."

Jan 1, 2005

By S. Stefanizzi

In the present paper, numerical simulations based on a finite/discrete element approach are used to study deformation and failure process during standard rock mechanics. FEM/DEM modeling has been used as available with the ELFEN code, which explicitly model the transition from continuum to discontinuum. The transition is simulated through a crack nucleation and propagation that obeys to the Griffith?s failure criterion. If the fracture criterion within the intact rock (represented by FEM) is met, a new crack (represented by DEM) is initiated. Remeshing allows the fracture process through the FEM mesh to be tracked and visualized, thus contact properties can be assigned to pre-existing fractures and newly generated fractures. In this study, compressive tests of rock samples are simulated. The applicability of ELFEN to properly and efficiently simulate typical laboratory rock mechanics tests, with reference to the rock fracture process, is described in detail. In addition, an indirect validation of the extensional strain criterion proposed by Stacey (1981) is given.

May 1, 2009

By Peter Dunn

London Mining Plc. is developing an iron ore project in Sierra Leone. The Marampa mine is a brownfield development effort, having been operated by others since the 1930?s until low iron ore prices forced closure. Peak production of the prior operations was approximately 2.5 Mt/a in the 1960?s. Following civil war In Sierra Leone, London Mining obtained the mining license in 2006 and commenced activity to redevelop the Marampa mining and processing operations. There are two ore deposits of interest for development as well as a resource comprised of tailings from previous operations. Phase 1 will be the mining of the tailings resource with a 1.8 Mt/a plant producing 66 per cent Fe sinter feed, expandable to 3.6 Mtpa. The first phase is currently under construction with start-up expected in the third quarter of 2011. Phase 2 will include development of the two ore deposits. These deposits are weathered secondary ore and the main primary ore resource. Phase 2 is currently under prefeasibility study and targets a final 16 Mt/a concentrate production in 2016. Outotec partnered with London Mining on testing efforts to develop the magnetic separation flowsheet using SLon VPHGMS machines to process the Marampa material. This paper explains the flowsheet development process for the weathered and primary ores commencing with sample characterization and detailed parametric investigations to evaluate SLon performance. The final flowsheet configuration is explained, including expected circuit recoveries and concentrate quality, clearly demonstrating the performance of the SLon VPHGMS circuit in iron ore tailings treatment applications.

May 1, 2011

By D. J. Hallbom

This paper presents a novel methodology for the hydraulic design of mine backfill distribution systems. The ?operating range? method uses the concepts of the hydraulic grade line and equivalent pipe length to determine flows and pressures as the pipeline route and static head change over the life of the mine. The operating range method is easy to learn because it is semi-graphical and uses well-known design concepts (e.g., the hydraulic grade line) and slurry design models (e.g., the Durand deposition velocity model). However, by changing the paradigm in which these concepts are used, the operating method allows all potential pipeline cases to be analysed simultaneously without the need to know the exact pipe routing. It also allows the hydraulics engineer to quickly identify ?pinch points? and ?slack flow? zones, to estimate the effect of changing the size or length of any given section of pipe, to assess the impact of changing the material properties of the backfill slurry, to size the slurry pumps, and to size and locate rupture discs when required.

May 1, 2007

By Matthew A. Baumann

Tooth-wear on mining shovels requires continuous monitoring. Worn teeth impede excavation performance, increase energy usage, and increase the risk of lost or broken teeth and adapters. A machine-vision-based automated tooth-wear monitoring system is presented. The system employs a rugged boom or stick-mounted camera to capture images of the shovel teeth. An onboard computer processes the images in real-time to determine the length of each tooth. The current wear state is available via a network-accessible log for on-demand status updates. By continuously recording tooth length changes over time, the logs can be used to estimate wear rates and patterns, permitting comparisons between different G.E.T. configurations, operator behaviour patterns, or material types. This detailed, quantitative data permits site-specific optimizations to wear packages and maintenance scheduling. Automating wear monitoring offers the crucial wear information necessary to minimize maintenance costs and reduce unscheduled downtime. A 37-day field trial in a copper-gold mine demonstrated the ability of the system to measure tooth lengths, compute wear rates, and detect differences in tooth wear based on their position on the bucket.

Nov 1, 2011

By T. Yalcin

"This paper describes the development of a mathematical model for determining the liberation of an ore at various grinding sizes, based on the combined results of microscopic counting, grinding tests, and chemical analysis.The method is illustrated with an application to the magnetite ore of Sherman Mine in Temagomi, Ontario. For this ore, a degree of liberation of 98.7% was determined at a grinding size of 90% passing 44 microns, which closely corresponds to the final grinding size employed at the Sherman Mine Concentrator.Introduction Liberation characteristic of ores have direct and significant bearing on overall economics of concentration processes.Target grades and recoveries can be achieved only it minerals are adequately liberated prior to separation. Degree of liberation depends on the extent of size reduction. However, due to the high costs associated with size reduction processes, it is important to keep size reductions within limits of satisfactory liberation. Prevention of excessive size reduction is also necessary because of inefficient mineral separations in very fine sizes. Hence, a study of reduction size — liberation relationship is essential for optimum profit from milling operations.A number of procedures have been developed for liberation studies (1-12), but there is lack of method for universal adoption.A new approach is presented in this paper that might provide a realistic estimate of liberation and give a practical guidance as to the degree of size reduction required for satisfactory liberation."

Jan 1, 1985

By D. Stone

"The Beal Mountain mine near Anaconda, Montana, is an interesting case history of a mine that has continued operations despite several large pit wall failures over a period of approximately 10 years. The largest event involved some 3.9 million tons of rock that has moved steadily at a rate of about 0.05 ft/day since 1992. This paper documents the geotechnical instrumentation and monitoring programs implemented at Beal to provide the company with a comfortable baseline that supported ongoing operations. The success and failure of a variety of stabilization measures will be discussed, along with typical instrumentation responses for several significant events. The success of Beal Mountain serves as a good model for mines faced with serious geotechnical challenges."

Jan 1, 2002

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 J. A. King, D. A. Knight

"The Porgera orebody is located in mountainous terrain in Enga Province, Papua New Guinea. An underground mine has been developed which produces up to 2000 t/d of ore grading over 2 ozs Au/t. Some 79% of the gold in the ore is free, with the balance in a highly refractory form as sub-microscopic gold evenly disseminated within a pyrite matrix.This paper describes the metallurgical plant that uses flotation and cyanidation circuits to effectively recover the free gold in the ore feed, allowing for wide variation in the gold head grade. The refractory gold component in the ore is stored as leached pyrite flotation concentrate and this concentrate will be later treated by autoclaving techniques to recover the contained gold.The ProiectThe property is located in the Porgera Valley 600 Km North West of Port Moresby. The remote location is 2500 m above sea level. The mine area has 3600 mm of annual rainfall and a temperate climate with temperatures ranging from 10° c to 22° c throughout the year.Alluvial gold was reported in the Porgera area in 1938 and has been an important source of revenue for the area for many years. Intermittent exploration was carried out until the 1960 1 s when Placer (PNG) Pty. Ltd. with Mt. Isa Mines commenced an extensive exploration program. The property was brought to production in 1990 by the Porgera Joint Venture group consisting of Mount Isa Mines Ltd, Rennison Goldfield Consolidated Ltd. and Placer Dome Inc, each with a 30% ownership and the Government of Papua New Guinea with a 10% share. Placer Dome Inc. is the manager of the property with construction under the direction of the Placer Dome Technical Services group."

Jan 1, 1992

By J. T. Furey

"A pilot plant study was conducted to evaluate the performance of column flotation in the recovery of gold from a gold/tellurides bearing sulphide ore, and to compare the performance of column flotation to conventional ""mechanically agitated"" flotation.Tests were conducted in a 60 liter glass column with ground flotation feed split from a concurrently operating conventional pilot plant, thus permitting direct comparison between the two processes. During the test program, the effects of wash water rate, gas holdup, froth depth, residence time and flow bias were examined in detail.The ore had an average ""as tested"" feed grade of about 5 g/t gold and 1 % sulphur, with the gold occurring primarily as inclusions of montbragite (Au2Te3) in pyrite, with minor amounts of native gold. Conventional flotation using 60 minutes residence time across four roughing stages recovered about 97% of the gold into concentrates grading about 50 g/t Au. A single stage of column flotation roughing using 25 minutes residence time matched the conventional circuit recovery of 97%, but produced grades of+ 150 g/t Au. INTRODUCTIONColumn flotation is the most significant innovation that has occurred in the mineral processing industry in recent years and has become an important alternative to mechanical flotation. Column flotation has been most widely accepted and applied in cleaning service where it has frequently proven to be superior to mechanically agitated flotation. Roughing in columns has not been ignored, but early testing indicated that columns may not be capable of achieving adequate recovery and, to date, columns have not been seen as serious competitors for mechanical roughers."

Jan 1, 1990

By Chuck Edwards

Whatever your opinion of the validity of the scientific case for global warming, or of the wisdom of the Kyoto Protocol, it would seem judicious to err on the side of caution and try to sensibly minimize global climate change. To this end, we should take prudent steps to minimize our emission of greenhouse gases. Cameco is the world's leading supplier of uranium for use as fuel in nuclear power plants. Cameco’s uranium production fuels nuclear power plants in 16 countries. Nuclear power plants generate clean electricity without greenhouse gas emissions. This presentation describes the role that uranium and nuclear power can have in meeting the growing demand for electricity and at the same time combating global climate change.

Jan 1, 2004

By Michel Rodrigue, Sylvain Duchesne, Louis Racine

"LocationThe Louvicourt mine is located 20 km east of Val d'Or in Abitibi, in the northwest part of the province of Quebec. The mine is located on Highway 117 connecting Val d'Or to Montreal and very close to the main railway networkHistoryFive successive exploration attempts by Aur Resources resulted in the discovery of the large Louvicourt orebody in June 1989. Construction of the surface and underground infrastructures commenced in the spring of 1991. Milling operations commenced in July 1994. The entire project cost CDN$290 million, almost CDN$20 million less than initially estimated. The concentrator infrastructure cost CDN$64 million.Louvicourt mine is owned in partnership by Novicourt Inc. (45%), Teck Corporation (25%), and Aur Resources Inc., the administrator (30%).Brief DescriptionLouvicourt mine is the largest producer of base metals (Cu and Zn) in Abitibi-Temiscamingue. Its average daily production is nearly 4300 t of ore, for an annual production of 200 000 t of copper concentrate (28% Cu) and 33 000 t of zinc concentrate (57% Zn). After only a few weeks of operation, it had attained its objectives for the most part, and operations continue to be improved."

Jan 1, 2000