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By Linda Dufour

"Autoclaves have been in commercial use in the mining industry since the early 1950's the initial applications included tin, uranium, cobalt, nickel and copper extraction under both acidic and alkaline conditions. These circuits varied in batch or continuous operation. The geometry has been spherical, vertical, and horizontal type with up to six agitators, with throughput as high as 1000 stpd.Presently autoclaves are a good process selection for many refractory sulphide gold bearing ores. The first application of pressure oxidation in the gold industry was at the Homestake Mcglaughlin's Mine which was commissioned in 1985. This was an acidic pressure oxidation process treating 3000 stpd in three four compartment horizontal autoclaves 14' diameter and 53' long. Since the initiation of autoclaves for the treatment of gold bearing sulphides, there are presently 16 gold autoclaves operating worldwide varying in size up to 18'4"" inside diameter. There are seven autoclaves for the treatment of refractory sulphide gold bearing ores to be commissioned in 1997 and 1998.Autoclave technology has progressed extensively since the mid-eighties. Operational experience has made rapid progress and the result is much smoother and safer autoclave operation. There have been many advances in autoclave technology design. For example, the use of exotic materials for corrosion resistance to reduce down time for maintenance. The instrumentation involved in autoclave operation is very sophisticated which allows for many safety features. The advanced design has allowed for greater availability and as a result operating costs and maintenance costs have decreased. These technological advancements have made autoclave technology more safe and this has resulted in a greater acceptance of this type of operation. Many of the gold autoclave facilities operate up to 9 months continuously without shutdowns. The advancement of autoclave technology has inspired many new applications.Because of the outstanding operation of autoclaves in the gold industry, many other applications for autoclave technology are being considered. The following is a list of autoclave applications:"

Jan 1, 1997

By G. Winkel

Safety conditions in industry have greatly improved over time. However, around the world, in Canada, and in each province or territory, people are still the victims of serious industrial accidents. The increasing safety of people at work then continues to be an imperative in industry today.<p> So how do we achieve a workplace where no one gets hurt? Well, in simple terms, folks need to be protected from unplanned exposures to equipment or energy sources that can do harm. If you think about it, all of our efforts in loss management and safety should then be directed toward avoiding these uncontrolled events. And it works! Our safety performance over the years has enjoyed tremendous improvement due to this support for loss management and safety. We now explore best practices toward achieving that next step in safety improvement.<p> As shown following, a large combination of loss management activities act together to support safety performance. Many of these activities are interrelated and some people have described them as the ?inputs? into an approach or program for achieving safety. Using this description, it follows that the ?outputs? of the program are some of the advertised measures of safety we see around us today, such as injury frequency rates. <p> It is asserted that a leadership focus to regularly measure safety and loss management activites (so-called ?inputs?), as a basis for taking supportive actions to ensure their effectiveness, is the basis for safety results (so-called ?outputs?) that consistently achieve high standards of excellence.<p> The concept of managing input activities, as enabled by effective measurements, can significantly act to transform our focus and priorities in the workplace. Supporting input activities like strategies, plans, or procedures with our best efforts will get us to our intended goals. Tracking outputs alone will not.<p> Safety and production have traditionally been cast as competing objectives. When both objectives are mutually supported and considered, however, people will invent ways of doing work that support both safety and production, and any other business parameter. When done right, innovation through meaningful involvement of affected people in the workplace will support safety excellence in a manner that in turn improves business efficiency overall.<p> For a workplace to be safe, it then requires everyone?s help and participation to make it happen, a collaborative effort by management, leaders, and frontline folks with the power and responsibility to take appropriate action at every level in the organization. In this way, everyone becomes a leader in safety.<p> The achievement of commitment to loss management input activities by folks in the workplace is the basis for attaining safety excellence. A workplace founded on commitment supports a safety culture with a vision for safe work performance at outstanding or world-class levels of achievement.<p> One may ask if injury incidents will be eliminated with this commitment and focus on workplace safety? Well, despite our best efforts in this area, there is never a guarantee that things can?t go wrong. We are simply not perfect. There remains in our workplace complexities and unanticipated risks that can have disastrous consequences if not managed at every moment. And when it goes wrong, we need to know we?ve truly tried our best, and now we have more to learn so we can get even better. <p> That?s the challenge represented by the safety imperative, a challenge to take safety performance that next step, a fulfillment of our commitment to the moral obligation we have to each other?s safety. It?s an effort that will continually raise the bar of world-class safety performance achievement for future generations. It?s a legacy we can be proud to be part of.

Sep 1, 2004

By Marc C. Bétournay

Under the requirement to define the economic advantages of using hydrogen fuelcell vehicles, a broadscoped project was initiated to quantify the costs associated with operating fuelcell vehicles and diesel vehicles. While ventilation savings are clearly an advantage for the former, a complete and detailed analysis of this and other operational and capital cost elements was undertaken in order to provide the mining industry with factual information in considering the changeover from one technology to another. This article outlines the results of the investigations to date defining the costs/benefits associated with: capital purchases, operations (electrical/diesel, mine air heating fuel, ventilation, openings, surface and underground infrastructure, maintenance, labour, etc.), delivery of energy, regulatory obligations, and mine production. Considerations are given to the type and size of a mining operation, the depth, and location in North America. Significant ventilation power, equipment and infrastructure savings are possible with the application of fuelcells for shallower mine applications. At depth, where heat is an issue, there is a reduction in benefit. Specific qualifiers such as minimum air velocities, dust dilution, shaft and heating system velocity limits must be considered on an individual mine basis. While the capital cost for fuelcell mining equipment is currently higher than diesel versions, the high cost of fuelcells is anticipated to be reduced significantly in the near future with the intensification of manufacturing. In either case the operational savings would probably be sufficient to balance the supplementary capitalization costs. A comprehensive cost-benefit report will be issued in the near future.

May 1, 2003

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 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

"The Key Lake mill was commissioned in 1983 to process the two Key Lake ore deposits. With the depletion of these ore bodies in 1999, the plant was converted to mill the exceptionally rich McArthur River deposit located seventy eight kilometers northeast of the Key Lake mine site. This paper describes in detail the Key Lake milling process. The mill consists of a grinding circuit, a leachkounter current decantation circuit, a solvent extraction circuit, a yellowcake precipitatiodcalciner circuit, an ammonium sulphate crystallization circuit, and a waste treatment circuit. The paper also describes process changes to handle McArthur River ore, including the ore receiving stationLOCATIONThe Key Lake mill is located 78 kilometres south of the McArthur River mine. It is located at latitude 57' N in northern Saskatchewan, within the southern boundary of the Athabasca formation. The nearest town is Pine House, located 240 kilometres to the south. Access to the mine is by an all weather road and by a private airstrip.HISTORYAND DESCRIPTION OF OPERATIONThe Key Lake mill was commissioned in October 1983 to process ore from the Gaertner and Deilmann ore bodies. The mill was designed to produce twelve million pounds of uranium oxide (U308) a year from a feed grade of 2.4% U3O8.Following grinding, the uranium is leached in a two stage leach circuit using oxygen and sulphuric acid. An eight-thickener counter current decantation (CCD) circuit is used to separate the uranium bearing solution from the solid waste residue. The uranium is further purified in a solvent extraction circuit and then precipitated using ammonia. It is then calcined at 840' Celsius, and packaged into drums for shipping to refineries. There is a crystallization circuit to recover ammonium sulphate produced in the process and a waste treatment circuit."

Jan 1, 2001

By A. Saigal

A finite element analysis based investigation using DEFORM software was undertaken to model the extrusion of 15% alumina and 15% silicon carbide reinforced aluminum metal matrix composites. The study dealt with predicting the extrusion load as a function of ram displacement and initial billet temperature. The finite element simulation was also used to determine the maximum extrusion load, temperature distribution, maximum temperature, strain rate, velocity and stress distributions in the billet during the hot extrusion process. The constitutive equation used was of the type: Z = E exp(Q RT) = A{sinh(ao-)}" where Z is the Zener-Hollman parameter (temperature compensated strain rate), s is the strain rate, Q is the activation energy, R is the gas constant, T is the absolute temperature, a is the flow stress and A, a and n are constants. Based on the work of Davies et al and McQueen and Konopleva, the values of Q (KJ/mol), a (MPa-1), n and A for aluminum 6061 composites reinforced with 15% alumina and 15% silicon carbide used are 181, 0.024, 4.15 and 1.33x10&apos;2 and 233, 0.052, 2.60 and 1.26xl0&apos;4, respectively. Even though the individual parameters are quite different, it was found that the predicted maximum extrusion load, temperature distribution, maximum temperature, strain rate, velocity and stress distributions are quite similar and differ by no more than 1-2 percent between the two composites indicating that the deformation behavior is primarily controlled by the matrix material and is not a function of the type of reinforcing ceramic particulates.

Jan 1, 2004

By W. J. Tough

THIS paper offers examples of some of the typical calculations which occur in the ventilation of metal mines. The fi.rst section of the paper discusses the problems associated with natural-draft pressure; the second section presents the more common of the calculations concerned with the operation of mine fans; the third section illustrates the integration of the individual problems covered by the preceding sections into the larger problem of determining the operating characteristics of a fan for a particular mine duty. There is a very definite limit to the extent to which pure arithmetic can be successfully applied to the solution of min<; ventilation problems. As mines advance from the exploration, development, and initial production stage to the rime when underground workings become exceedingly complex, there is a considerable increase in the relative importance o theory and judgment in the solution of ventilation problems. These calculations illustrate the application of mathematics to ventilation, but they also in-elude examples of instances where arithmetic cannot be conveniently applied, and important estimates, based on judgment compounded of experience and a knowledge of the theoretical consideration involved, must be made. The inclusion of such estimates is intended as a guide and a warning to the reader; a guide in assisting him to recognize and estimate his own incalculables; and a warning that the solutions must not be blindly applied to his apparently similar problems. These sample calculations are intended to assist the reader in applying the theory contained in the standard texts on metal-mine ventilation. They have been selected from the ventilation experience of a British Columbia mine.

Jan 1, 1942

By David Whittle

When does a project with questionable viability, warrant further investment? There are cases in which projects, which evaluate to a negative mean probable value, are worth investing in. There are also cases in which projects that evaluate to a positive mean probable value, should not be invested in. The author will present a model for ?project-control?which includes an adaptation of a well know grade-control concept. Comments on Resources and Reserves ?Resource and Reserve estimates are based on positive information (43-101). ?Reserve and Resource confidence qualitatively assessed. ?U.S. Geological Survey (USGS) recognizes Undiscovered Resources (U.S. Geological Survey 2003).

May 1, 2006

By William Petruk, J. R. Schnarr

The behaviour of minerals during flotation of a fine-grained pyrite-rich base metal ore was investigated by studying the feeds. concentrate and tailings from every flotation cell in the mill of Brunswick Mining and Smelting Corp. Ltd. Bathurst. New Brunswick. The samples were analyzed for Zn, Pb, Cu. Fe, Ag. Sb, Sn, Bi, In. Hg, Mo and As. Mass balances were computed and recoveries of all metals from each cell. from each circuit and from the mill were calculated. The percentages of sphalerite. galena and chalcopyrite occurring as free grains in each product were determined with an image analyser, as were size analyses for free mineral grains and middling particles, and compared with screen analyses. The results show that the behaviour of minerals is defined much better by the recovery of free mineral grains than by the recovery of elements. The recovery of free sphalerite in the zinc circuit is 96 wt %, whereas Zn recovery from the same circuit is 88 wt %. the difference being due to unliberated sphalerite. The recovery of free sphalerite from the mill feed is 88 wt % and Zn 78 wt %. The recovery of free galenafrom the mill feed is 88 wt % and Pb 64 wt %. The recovery of free chalcopyrite is 75 wt % and Cu 45 wt %. Size analyses show that more sphalerite and chalcopyrite can be liberated by regrinding. but the galena is so fine grained that regrinding would not necessarily improve liberation. Silver occurs mainly in tetrahedrite and galena; the main loss in the tailings is due to large (+ 26 um) and small (-1 um} free and unliberated tetrahedrite grains.

Jan 1, 1981

By Pierre Gaucher

It is possible to selectively mine an orebody by combining the use of the SSW probe with any bulk mining methods as well as narrow vein exploitations. In other words, thanks to the use of the SSW probe, mining operators will be able to reduce and control dilution that is generally associated to every mining operation. Already, quick and substantial savings have been obtained. Falconbridge mines have demonstrated in Sudbury and Raglan operations, that the SSW probe can log nickel, copper and iron sulphides in blast holes. They have raised the grade and reduced dilution by outlining the limits of the ore zones before selectively loading explosives in the blast holes. By lowering the probe in a blast hole, a profile of the ore content is instantly measured and recorded. Logging cored diamond drill holes at the mine have demonstrated that the ore content (nickel, copper, cobalt, PGM) as assayed is proportional to the intensity of the probe?s electromagnetic response (EM), probably because the nickel / pyrrhotite ratio is uniform within a given orebody. The probe also measures the intrinsic conductivity of the sulphides and the percentage of magnetite. All probe readings are displayed and automatically stored at a 10-cm interval within the same reading unit. A 30-meter blast hole takes less than 2 minutes to survey. The whole instrument is light (12 kg) and very simple to use. One operator can carry the SSW system and survey either down or up-holes. The probe works from ?40°C to +50°C. Plotting the measurements of the SSW probe in blast holes (2-3-4-6-10 inches in diameter) before blasting allows to determine the exact shape of the orebody within the waste rock and uneconomic low-grade ore. Thus, only the portion of the holes that contains ore is blasted. The dilution is then much reduced and, by leaving the waste and low-grade ore in place, the mine saves on transportation, blasting, crushing, backfilling, milling, etc. Thousands of dollars are thus saved. Some savings may also be achieved during the development of stopes by guiding development drifts and by replacing diamond drilling by percussion drilling. In some circumstances, when the probe shows that some of the rich ore was not drilled-off, additional blast holes will allow to recover pockets of rich ore that otherwise would have been abandoned in the walls of a stope.

Oct 1, 2001

By Richard C. Banting

Excessive vibration is known to have an adverse affect on soft body tissue and operators of heavy mining equipment can be exposed to vibration that exceeds levels recommended in international guidelines (ISO 2631-1, for example). Research has found that many of the seat and suspension systems currently used in mine haul trucks and load haul dump vehicles are actually amplifying the vibration. This overview presentation will outline the current research being conducted at Laurentian University and the University of Western Ontario, and the roles of partners in rating the ability of a number of commonly used mine vehicle seats to isolate harmful vibration.

Oct 1, 2010

By G. Griffiths

"P. WitteWitteck DevelopmentThe implications of using a tower mill for fine grainding in the ore processing of tailings are significant. What can those of us who are in a research and development situation do when we recommend this equipment to a client? When this prototype is placed on stream next to a conventional grinding mill as you suggest how do we estimate the power requirements and the grind which will be achieved?ReplyLet me explain the Macassa circuit. The tower mill here was running in parallel with one of the ball mills. The feed entering the tertiary system is scalped in a primary cyclone. The finial cut is made in a secondary cyclone. The actual feed to the tower mill is the underflow from the two cyclones and was split to the ball mill and tower mill. During the testing we were unable to isolate the tower mill to determine its contribution to the overall system. We then started to look at the amount of material produced across the mill. We entered the mill at between 17% and 20% finished material and exiting at between 36% and 40% finished material. We were able to project, with a high efficiency classification system, and arrived at 6 Kwh/ton or better."

Jan 1, 1984

By M. Veiga, L. Lavkulich, R. Pakalnis, M. Ghomshei, S. Baldwin, J. A. Meech

"On July 26, 2000, the Canada Foundation for Innovation announced an award of $1.3 M dollars for The Centre for Environmental Research in Minerals, Metals and Materials, CERM3, at The University of British Columbia. Additional funding was also provided by the British Columbia Knowledge Development Fund ($1.3 M) and the UBC Stewart Blusson Fund ($0.7 M). Annual industrial grants and contracts are providing support funding for the on-going research projects. Corporate membership in CERM3 entitles each participant to a seat on the technical advisory committee (TAC) as well as access to the five laboratory facilities currently under construction. Both the federal and provincial governments will also participate in the TAC through NRCan-CANMET and the BC Ministry of Energy and Mines, respectively. CERM3’s mission is:• to develop innovative methods to deal with environmental problems created by mining activity;• to promote sustainable development as a hallmark of management decision-making; • to produce mining and processing engineers with the required environmental skills; and• to enhance the image of mining in society as a vibrant and necessary component of a modern economy and society which disturbs the environment for the benefit of mankind.CERM3 brings together a multi-disciplinary team of researchers from over 12 departments at The University of British Columbia (UBC) to work on mining-related environmental problems. These include: chemistry; soil sciences; chemical and biological engineering; earth and ocean sciences; microbiology; civil engineering; electrical engineering; metals and materials engineering; mechanical engineering; mining and mineral processing, the Westwater Research Centre; the Institute for Resources and the Environment; and the School of Occupational and Environmental Hygiene. The centre intends to interact with scientists from industry, governments and other universities across Canada and around the world. CERM3 aims to become Canada’s leading environmental research facility for the mining industry. This paper describes the evolution of CERM3 and its coordinated multi-disciplinary approach to mining and the environment. Some of CERM3’s research projects include:• developing new protocols for environmental analyses to provide consistent and reliable assays;• isolating a natural virus for Thiobacillus ferrooxidans and other bacteria responsible for acid rock drainage (ARD);• designing bio-remediation and adsorption techniques for mine effluents;• promoting and enhancing the use of hydrometallurgy to reduce environmental pollution;• examining new approaches to comminution to decrease energy consumption;• developing a magnetically levitated hoisting system to reduce the footprint of a mine operation;• building a state-of-the-art supercomputer network laboratory for mine/mill simulations; and• designing intelligent bulkheads to seal tunnels following mine closure to survive for 1000 years.This latter project involves the establishment of a research station at the Britannia mine site, 45 km north of Vancouver, which will provide a full-scale facility to design the “Millennium Plug” and contribute directly to the solution to one of North America’s worst ARD-contaminated sites."

Jan 1, 2003

By Vanessa C. Koppe

During ore body modeling normally additional samples are required to improve resources evaluation and mining planning. At this stage one rises the question about where additional samples should be located. Regular sampling pattern seems to be a reasonable choice, since all the regions within the deposit receive the same number of samples without a clear clustering. Nevertheless, values for certain attributes (grades for instance) from a mineral deposits may behave more erratic in some regions than others. Consequently, by adding samples to these regions could bring more benefit for reducing the uncertainty related to a transfer function such as Net Present Value (NPV), instead of adding samples to location of low grade uncertainty. Thus, for a given number of additional data, the test of a regular pattern and a pattern which add samples on areas of high uncertainty of the attribute of interest is worth. This paper presents an algorithm that allows the construction of these two patterns, automatically, on a software commonly used in the mining industry. The algorithm leads to a fast analysis on the efficiency of the two patterns in reducing the uncertainty associated with a transfer function.

Oct 1, 2009

By J. A. Finch, T. Weber

"Bubble size in flotation is strongly influenced by frother concentration in the pulp liquor. There is no accepted method of judging the dosage and thus how effectively frother is being distributed to control bubble size is not known. This will hamper certain plant test work where constant bubble size (e.g., when comparing reagents) is implicit. Bubble size is not easy to measure in plant and gas holdup is suggested as a surrogate in the development of a proposed “meter” to estimate frother concentration. The meter is calibrated to enable frother concentration to be estimated on samples drawn from any location in the flotation circuit. The meter and its calibration are described.As general background the action of frothers in reducing bubble size by retarding coalescence is discussed and the bubble generation systems for which the effect will be important are considered.INTRODUCTIONBubble size is an important variable in flotation. The flotation rate constant k has been related to mean bubble size Db by k % Db -n with n ranging up to 2 (Ahmed and Jameson, 1989) and even 3 (Yoon, 1993). Recent work has introduced k % Sb, the bubble surface area flux, given by Sb = 6 Jg / Db (where Jg is the superficial gas velocity or volumetric gas rate per unit cell cross-sectional area), i.e., n = 1 (Gorain et al., 1998). Regardless of the exact value of n, the significance of bubble size in flotation remains. In many plant trials it will be implicit that bubble size has not changed and attention will focus on other process variables. The measurement of bubble size, or a surrogate, would be useful addition to any test work.The size of the bubbles is influenced by several variables, gas rate, gas injection system (e.g., impeller design and rotation speed in a mechanical cell) and pulp composition (chemicals added, percent solids), but the most important is frother concentration (Harris, 1976). The frother functions by retarding coalescence (see appendix), which acts to preserve the small bubbles generated in the pulp (and permits a stable froth to form on top of the pulp). The measurement of bubble size is thus related to measuring frother concentration. The distribution of frother and whether sufficient (to control bubble size) is reaching the intended parts of the circuit then become important considerations. At present there is no simple way to judge frother concentration in a plant. In this communication we introduce a possible methodology, a “frother concentration meter”."

Jan 1, 2003

By Alan D. Akerman

This paper describes the significant advantages and improvements in operational availability, reduced breakdowns, and overall cost reductions that can be achieved through the application of a Reliability Centred Maintenance (RCM) program, including Condition Based Maintenance (CBM) and Equipment Health Monitoring (EHM), in a mine environment. It uses a case study to illustrate the essential elements that constitute the basic requirements to establish such programs. This CBM case study analyzed the Load-Haul- Dump (LHD) vehicle sub-systems and their dominant failure modes, as a precursor to the development of condition indicators. The case study describes a disciplined process to enable condition indicator development and qualification in support of a CBM program. The identified condition indicators vary from readily applicable off-the-shelf monitoring systems and techniques, through to "leading edge" technologies that require further research and development. The paper also explores the developments that have been made in the combination of expert system software associated with modern computer based control systems, and the availability of "intelligent? sensor technology that complement the control system capability.

May 1, 2002

By D. Brisebois, J. M. Fecteau, S. Poirier

"This paper focusses on new developments regarding thermal rock fragmentation applications. The technology consists of a strong burner powered by diesel fuel and air. The thermal reaction that is created allows for the enlargement of 125 mm to 450 mm holes by breaking the rock in a spalling effect. It has been used for over 30 years in Russian open pit mining. Following an agreement between Dynamitage T.C.G. Inc. and the owner of the technology, major improvements have been brought to this technology, allowing for the fabrication of a prototype suitable for the Canadian industry. In Russia and the Ukraine, thermal rock fragmentation is actually used to drill large diameter holes in surface mining. Upon having acquired a better knowledge of this technology, it seems that it presents a great potential for selective mining in narrow-vein operations, for either surface or underground mining.Rocmec International Inc., a subsidiary of Dynamitage T.C.G. Inc., and Natural Resources Canada are technical partners in the evaluation of the operational parameters and environmental aspects such as gas, heat, dust and fog emissions. Furthermore, Canada Economic Development is a financial partner in this project.This paper presents the technology and its history. It also reports on the changes brought to the equipment to adapt it to North American environments. A summary of the tests carried out since 1995 is provided, along with the main conclusions obtained. The anticipated applications for the use of this technology in both surface and underground environments are described such as open pit mining, bulk sampling and narrow-vein ore extraction. An estimate showing a comparison between the thermal fragmentation mining concept and the long-hole mining method is presented and, finally, the future developments planned are listed."

Jan 1, 2003

By R. N. Murarka

"Hydrocyclone modelling and selection procedure is illustrated. Computerized procedure for hydrocyclone cut size determination for grinding and non-grinding applications is described.A standard procedure for evaluating operating hydrocyclones is described in detail. Many case studies are illustrated comparing actual plant performance with the computer simulation output in terms of overflow product size distributions.INTRODUCTION Cyclones are widely used for applications such as: close circuit grinding, backfill, tailings and dewatering. Normally, cyclones are used for very fine separations where screens are not suitable or too expensive. Figure 1 shows the separation size range of various classifying devices. Cyclones are popular because of their low capital and operating cost. Cyclone selection procedure for different applications depends on the amount of information available on the cyclone feed slurry characteristics. Closed circuit grinding applications will be discussed in detail in this paper. The Cut Size:The size of the material in the feed which reports 50% to each product stream (i.e. underflow and overflow), after correcting for the feed solids by-passing with the underflow liquid, is termed the cut size or ""d50c"". This is often used as the criterion and the basis for cyclone design.When the corrected recovery to underflow of each mesh size in the feed is plotted against the geometric mean size in microns on a log scale, the micron size corresponding to 50% recovery is the d50c size."

Jan 1, 1992

By Chris Brown

"The Island Copper plant was designed and built by Fluor Utah Ltd, in conjunction with Utah design staff, Originally designed to treat 33,000 tons/day (t/d) of ore, the current average milling capability is 38,000 t/d (Nov'74). The first of six semi-autogenous grinding lines was brought on line in October 1971, startup of the remainder being governed by equipment delivery schedules.The summer of 1973 saw the start-up of an additional three ball mills, and attainment of the present production level. The current process flowsheet is shown in simplified form.CRUSHINGThe crushing circuit is relatively simple, comprising single stage crushing of the ore followed by screening to fine and coarse fractions.The crusher is a 54 x 74in. Allis Chalmers Superior Gyratory with a setting of 9-lOin., driven by a 500-hp motor. Trucks dump on three sides of a rectangular dump pocket. An 84in. x 20ft. link belt apron feeder draws crushed ore from a 250-ton surge bin below the crusher, discharging onto a 72in. wide inclined steel cord conveyor belt. A fixed splitter box at the conveyor discharge separates feed to two parallel Jeffreys 6 x 20ft. vibrating grizzlies for screening into +4in. and -4in. fractions. The fractions are collected on short reversible conveyors which feed the coarse and fine ore stacker conveyors. Trippers distribute ore to outside stockpiles adjacent to, and above, the concentrator grinding 'floor."

Jan 1, 1975