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By Asbjørn Solheim

The service life for aluminium reduction cells is often limited by the cathode carbon, due to preferential wear along the periphery of the cell leading to the so-called "W" wear pattern. The reason for this preferential wear is not well understood. Two mechanisms are suggested in the present paper; 1) non-stationary dissolution of aluminium carbide into a layer of sludge that periodically forms and disappears, and 2) electrochemical formation and dissolution of aluminium carbide within an aluminium carbide layer containing bath-filled pores. The latter mechanism may be related to the high local current density at the periphery of the cathode.

Jan 1, 2011

A study was made to determine the effect of increasing concentrations of dissolved oxygen on the floatability of galena pyrite and chalcopyrite. Adsorption, flotation and contact-angle tests were done in deoxygenated, in air-saturated and in oxygen-saturated solutions. The results showed that the adsorption of collector increased as the concentration of oxygen increased. Adsorption followed the exponential law r = kC'/"• Discontinuities in the curves were observed after the adsorption of several monolayers of collector. Although adsorption increased with increasing oxygen concentration, the floatability of the pyrite minerals did not increase, because oxidation had adverse effects on the floatability of these minerals. The floatability of galena was maximum in oxygen-saturated solutions, pyrite was depressed and chalcopyrite was also slightly depressed. Contact-angle tests proved that a bubble could not be attached to large flat surfaces in deoxygenated solutions, because sufficient surface free energy was not available for adhesion after the deformation of the bubble. In the presene of air, all the minerals yielded the same maximum angle of 72 degrees, characteristic of isopropyl xanthate.

Jan 1, 1970

By J. L. Dion

"A study of the techniques to integrally cast copper tubes in copper tuyeres for use in blast furnaces has been carried out. The work has been performed in support of current efforts to produce two-compartment tuyeres having improved water-cooling capacity. A test pattern corresponding to a vertical section of a two-compartment tuyere, and including a cast-in-place copper tube, was used to investigate such variables as tube preparation, tube coolant, pouring temperature, pouring rate and gating design. Successful castings, either with a good metalfurgical bond or good intimate contact between the tube and the casting, were produced, with all combinations of gating system and position of the tube tried. However, the pouring temperature, the pouring rate and the effectiveness of the coolant are interrelated and must be controlled to produce a good metallurgical bond.IntroductionAs part of its contribution to, and in collaboration with, the Copper Casting for the Steel Industry Committee, CANMET has undertaken research into the methods and techniques needed for the integral casting of copper tubes into high-conductivity copper castings.The objective was to produce two-compartment copper blast furnace tuyeres in which the water-cooled nose compartment consists of a copper tube metallurgically bonded to the wall of the high-conductivity copper casting. This design, developed in the UK, has demonstrated a much extended service life with attendant economies; unscheduled shutdown of blast furnaces due to tuyere failure is a significant problem in the steel industry. The Canadian steel industry believes that this design will replace the currently used single-compartment tuyere in blast furnaces within a few years.The technology to produce these tuyeres does not exist in Canada. One of the main features is the inclusion of a smooth-walled cooling channel in the nose, which permits high velocity cooling water to be employed. A second compartment acts as a reservoir backup, should failure in the nose occur. This would allow continued use of the tuyere for a period of time, permitting a scheduled shutdown for repair s. To assist the Canadian producers of tuyeres to maintain their market, and the Canadian steel industry to have a reliable domestic supply, it is important that the necessary technology for the production of two-compartment tuyeres be developed and transferred to industry."

Jan 1, 1982

By K. B. Han, S. Winkler, M. J. Benoit, M. J. Worswick

"Automotive heat exchangers are fabricated by forming multi-layered aluminum (Al) alloy brazing sheets into the desired geometry and subsequently passing the assembly through a furnace for brazing. As manufacturers seek to use thinner gauge and higher strength sheet to reduce vehicle weight, forming of the Al alloy sheets has become a challenge. Warm forming has previously proven to allay these forming concerns, but no consideration was given to the effect of increasing the forming temperature on brazing. Recently, it was shown that annealed sheet was more susceptible to the detrimental phenomenon of liquid film migration (LFM) during brazing if formed above 150°C, while work hardened sheets showed no increased susceptibility to LFM with increasing forming temperature, up to 250°C. In the current study, the brazing performance of simulated battery cooling plates was investigated. The plates were fabricated both from fully annealed and work hardened sheets. Brazing was assessed by microstructural evolution during a brazing cycle. The post-brazed microstructure varied with strain and forming temperature in plates made from annealed sheets, while no variation in microstructure with location or forming temperature was observed in plates formed from work hardened sheets.INTRODUCTION Since the 1970’s, one common method of fabricating automotive heat exchangers has been by forming multi-layered aluminum (Al) alloy sheets, and subsequently brazing the formed components together in a controlled atmosphere furnace. The Al alloy sheets used are comprised of at least two Al alloys roll bonded together, but can consist of additional layers, depending on the application; at minimum, the sheets are comprised of a core and clad layer. The core layer, often an AA3xxx alloy, remains solid throughout processing and provides strength to the assembly. The clad layer is always one of the AA4xxx series alloys which, due to their high silicon (Si) content, have a melting temperature range well below that of the core alloy. When the sheet is passed through the brazing furnace, the clad alloy melts to provide the brazed joint filler metal throughout the assembly, while the core alloy remains solid. In order to achieve cost and weight savings, heat exchanger fabricators have used Al alloy sheets with reduced thickness. However, deformation and brazing of these increasingly thin components remains a concern (Zhao & Woods, 2013). Furthermore, springback has been observed after forming sheets of higher initial strength (i.e. work hardened conditions), leading to flatness issues of formed components. Consequently, the ability to form high quality brazed joints is difficult in components formed from higher strength brazing sheets."

Jan 1, 2018

By Baisheng Nie

The process of gas diffusion through coal particles and the mathematical physical model under the third kind boundary condition was determined to obtain the rules of gas diffusion through coal particles of different sizes. The analytical solution of the equation was obtained by the Method of Mathematical Physics. The parameters of analytical solutions and the implications of parameters were analyzed. The Biot criterion (Bi) and the Fourier criterion (F0) of mass transfer can represent and reflect the features of gas diffusion field of coal particles. Moreover, the measurement method of gas diffusion coefficient and surface mass transfer coefficient is introduced and an example of measurement is given. The achievement can provide the support to prevent disasters related to methane in coal mines.

Aug 1, 2013

By G. P. Gu

The in-service 90/10 cupro-nickel tubes in a water-chiller system suffered from severe corrosion damage during their relatively short service life causing unexpected down time. In addition to downtime, the environmental risk associated with losing refrigerant was also a concern that initiated this investigation, Microstructural investigation using SEM and electron microprobe indicated that pitting corrosion had resulted in local nickel depletion, During the corrosion process, copper appeared to have re-deposited around the corrosion pits accelerating the local corrosion.

Jan 1, 2005

By Mohamed Hamoud

Relative permeability curves represent an important element of special core analyses, but challenges remain in obtaining valid results and the extrapolation and use of existing permeability results is problematic. This situation is compounded in cases where core properties are altered from changes in effective stress. During the production of oil and gas reservoirs, the effective stress changes as a result of changes in pore pressure or temperature. Therefore, changes in rock properties such as porosity and permeability will occur and will consequently influence reservoir performance calculations. An experimental program was carried out to understand the behavior of dense, reconstituted sand samples at low effective stress states. Drained triaxial compression tests were set up to study the effect of stress alteration on relative permeability data through porous media. Initially, a saturation stage was performed followed by isotropic loading to bring the core sample to reservoir fluid and stress conditions. Then, while axial (deviatoric stress) loading was applied to the sample, a series of absolute and relative permeability tests was performed under steady state flow at different levels of strain during pre and post peak shearing stress. The stress-strain behavior results from the study revealed that the absolute permeability decreased during isotropic loading (compaction) and increased during shearing (dilation). However, the shape of relative permeability curve changed from contraction to dilation and showed higher initial kro and the lower initial kro respectively. The goal of this project was to understand the behavior of both absolute and relative permeability at different stresses. It is expected that geomechanical processes will be adopted for special core analyses to support the current integration of geomechanics into reservoir engineering. This will be required if, during SAGD, conventional and/or unconventional reservoir simulation, reservoir engineers implement a proper set of relative permeability data at each in situ state of stress, instead of constant curves throughout the field?s life.

Jun 1, 2012

By K. N. Subramanian, H. Kanduth

"It is well known that chalcopyrite can be dissociated into simple sulphides by heating with elemental sulphur at about 475°C:CuFeS2 + S -> CuS + FeS2Experimental work was undertaken to determine whether this ""activation"" could be used to advantage in the selective leaching of copper from chalcopyrite concentrate.A method of treating copper concentrate with molten sulphur was developed and the activated product was leached in dilute sulphuric acid using oxygen, ferric iron or manganese dioxide as the oxidant. The object was to obtain a solution suitable for electrowinning with minimal purification, but it was impossible to obtain rapid extraction of copper without simultaneously dissolving a large proportion of iron. This was attributed to the fact that some of the copper was present as a low iron-copper sulphide (idaite) and that the pyrite formed during the ""activation"" step was more easily oxidized than natural pyrite."

Jan 1, 1973

By Marek Mika

This Paper has been prepared to be presented at the 23rd World Mining Congress & Expo ? Montreal 2013. It presents the idea how to carry out the shaft sinking operation, going through highly water-bearing and very weak rock strata, giving as an example one specific shaft sinking project which is being executed for one of the Polish collieries by our Shaft Sinking Company Content 1. Introduction. 2. Hydrogeological conditions within the area of the shaft. 2.1. Hydrogeological conditions assumed at the stage of designing. 2.2. Hydrogeological conditions encountered in the course of sinking. 3. Designed shaft lining. 4. Procedures for the shaft sinking. 4.1. Designed procedures of the shaft sinking. 4.2. Procedures for preservation and strengthening of the shaft lining and the surrounding rock strata. 5. Technological guidelines for proceeding with the shaft sinking ? selection of special methods. 6. Options for mechanization of work for the selected method. 7. Conclusions.

Aug 1, 2013

By M. M. Papic

"This paper describes the Sasol coal liquefaction process, as used in South Africa. It covers coal supply, coal gasification, gas purification, Fischer-Tropsch synthesis, the major utility systems involved and the economics of the process.IntroductionThe Sasol coal liquefaction process is based on Fischer-Tropsch synthesis of liquid fuels from carbon monoxide and hydrogen, which are in turn obtained by gasification of coal with steam and oxygen. The process is shown schematically in Figure I.The first step in the process is coal preparation, in which the coal is crushed and screened to a 3-50 mm size for gasification on one side and to -3 mm size for steam and power production on the other. Oxygen needed for coal gasificatoin is produced in the air separation plant.Coal is gasified under pressure by steam and oxygen in the Lurgi gasification plant, where raw, impure gas is produced . The raw gas is first washed in a scrubber with a circulating gas liquor, heat is then recovered from it in a waste heat recovery boiler and the gas is further cooled for purification. Water-insoluble materials (tar oils) in the gas liquor are separated from aqueous solution and sent to tar refining for the recovery of tar products. The aqueous portion of the gas liquor goes to a Phenosolvan solvent extraction process, where phenols and ammonia are recovered. Water then proceeds to the effluent treatment plant.The scrubbed and cooled raw gas goes to a Rectisol gas purification plant, where all components other than hydrogen, carbon monoxide and methane are removed as completely as possible by absorption in refrigerated methanol. The acid gases (CO2, H2S) stripped from the methanol in the Rectisol unit are processed in a Stretford plant for recovery of sulphur. Regenerated methanol is returned to the process. The purified synthesis gas is passed to the fluidized-bed Synthol reactors, where Fischer-Tropsch synthesis reactions take place.The synthesis products are recovered in a product recovery unit as separate streams of decant oil containing higher-molecular- weight hydrocarbons, light oil comprised of lower-molecular- weight species, the aqueous stream containing water solubles, a C3/C4 stream, a C2 stream , a methane stream and a hydrogen-rich stream. Most of the hydrogen is recycled to the Synthol reactors; a major portion of the methane is reformed to hydrogen and carbon monoxide for recycle; the C2 fraction goes to an ethylene plant; and liquid streams proceed to the product refinery.The product refinery is used to upgrade and purify the Synthol products to specification fuels and chemicals.Sasol l, the first coal liquefaction plant in South Africa , was built in 1955. It is still operating and has a product output of about half a million tonnes per year. The Sasol II plant is in a commissioning stage and will be in full operation in 1981. It is about five times the size of Sasoll. It uses over 12 million tonnes of coal and produces more than 2 million tonnes of saleable products annually (1,2,3). The Sasol llI plant, which is a mirror image of Sasol II, is under construction and scheduled for completion in 1983."

Jan 1, 1981

By J. E. Nesset

"As an alternative to conventional dewatering by vacuum filtration and oil-fired rotary dryers, Brunswick Mining conducted extensive pilot-scale testwork on its copper, lead, zinc and bulk concentrates using a Larox Oy (Finland) automatic pressure filter. The results showed that pressure filtration readily produced final cake moistures of 6-8.5 per cent on this very fine sulphide material.An in-depth analysis examines pressure filtration in terms of metallurgical performance and projects energy savings of 78 per cent for pressure filters over the current dewatering operation. Potential energy and operating cost reductions are also estimated.IntroductionVacuum filters followed by oil-fired rotary dryers are one of the most common means of dewatering mineral concentrates. They represent, however, a level of technology which is exceedingly wasteful in terms of manpower, space utilization equipment and fossil fuel dependence. In addition, the use of thermal dryers is leading to increased environmental concerns both in plant and out.These were the primary factors which prompted Brunswick Mining to consider alternative dewatering methods as the existing equipment came up for replacement and upgrading. In late 1979, company engineers were encouraged by automatic Larox pressure filters seen at several Scandinavian operations. Subsequent laboratory tests by the manufacturer (Larox Oy of Finland) on several concentrate samples were sufficiently promising for Brunswick and Noranda to lease a trailer mounted filter-lab unit and a technician from Larox for a five-week period. Extensive on-site testwork on all four Brunswick concentrates (zinc, lead, copper and 'bulk' lead-zinc) confirmed the potential of pressure filtration."

Jan 1, 1982

By T. R. Yu, D. B. Counter

"In an effort to increase productivity, the use of fly ash as a binder for consolidated backfill was studied. From laboratory and underground tests f or its cementitious properties and environmental effects, it was found that a portion of Portland cement could be replaced by the same amount of type ""C"" fly ash to produce an acceptable consolidated rockfill product for use at Kidd Creek.The environmental concerns in terms of dust control and emanation of radon gas were unfounded from measurements. The dust count was comparable to the use of Portland cement only, or with ground blast furnace slag, and the radiation readings were low, averaging one-seventh the regulation level.Since May 1984, a total of over 100 000tonnes of fly ash has been consumed as a binder blended with Portland cement, producing over four million tonnes of consolidated rockfill. To date, the fill in the stopes has performed very satisfactorily, while yielding considerable cost savings.IntroductionThe Kidd Creek minesite, located 27 km north of the city centre of Timmins, Ontario, produces 4.5 million tonnes of base metal sulphide ore annually. The mining method for both No. I and No .2 mines is mainly sub-level blasthole stoping with delayed backfilling.No. 1 mine was developed with a shaft to a depth of 930 m in 1973 to recover the ore between the floor of the open pit at the 216 m horizon, and the 792 m horizon. Stopes are normally 18 m wide, 22 m to 65 m long, with heights varying from 90 m to 135 m. Vertical rib pillars between stopes are typically 24 m wide and sill pillars are 30 m thick.Pillar recovery is implemented after the consolidated rockfill placed in the mined stopes has cured for a period of at least three months. This allows a maximum recovery of the ore with a minimum of dilution, while also maintaining safe working conditions.No. 2 mine was developed from a second shaft, sunk to a depth of 1530 m in 1978, for the recovery of ore beneath the No. I mine. Sub-level stoping in No .2 mine is similar to No.1 mine in methodology, yet differs in sequencing, as no rib pillars are left."

Jan 1, 1988

By P. W. Udo Graefe

"An interactive computer model of a dragline, windrow and spoil pile has been developed for modelling oil sands mining operations. The model is to be used in conj unction with models of other oil sands mining equipment, such as bucket-wheel excavators and reclaimers, conveyors, hoppers, bins, trucks and shovels, to study mining operations on a minute-by-minute basis. From the orebody description and mining selectivity, layers of ore and reject are determined and mined by the dragline. Reject is dumped on the pit floor; ore is either dumped on a windrow for later removal by a bucket-wheel reclaimer or directly dumped into a hopper feeding a conveyor. The model allows for the presence of pads as a dragline base, key cuts and a number of interruptions to the mining operation such as shift changes, boom checks, engineering services, repairs, delays, preventative maintenance, etc. A CRT display keeps the model operator informed about equipment status and performance. The model operator can direct the course of the simulation by issuing commands to the model at any time during the simulation.IntroductionThis paper describes an interactive computer model of a dragline, windrow and spoil pile. The model was designed by the author based on information and specifications provided by Canstar Oil Sands Ltd. The model design was implemented and tested on Petro-Canda's IBM computer system by DMR and Associates Ltd. of Calgary, Alberta.The model was designed to form three components of an oil sands mining operations model, described in reference I. Figure 1 shows the interaction of those components with the remainder of the oil sands mining model.An ""Ore/Waste Body"" data base provides information to the dragline model about the location and composition of or e and waste in the mine. The dragline model is used to simulate mining this ore/waste body, to build up spoil piles for center reject (waste) and to dump ore onto windrows or hoppers (situated over conveyors) to deliver the ore to the extraction plant. The windrow model component provides a data base which will be used by a model of a bucket-wheel reclaimer which simulates the loading of ore from the windrow on to a conveyor via a bridge."

Jan 1, 1982

By A. Zarei-Hanzaki, O. Golmahalleh, S. M. H. Hosseini, H. Azizi-Alizamini

The main importance of acicular ferrite microstructures arises from their desired combination of mechanical properties in comparison with the bainite and ferrite-pearlite microstructures. Several factors affect the microstructural transition from bainite microstructure into the acicular ferrite one. As is well established any factor corrupting the prior austenitc grain boundaries nucleation potential, such as the thin layer of allotriomorph ferrite and the austenitc deformation inhomogenities may promote the acicular ferrite formation instead of bainite. Accordingly, this study deals with the effects of the aforementioned features on the acicular ferrite formation in low carbon microalloyed steel. The results indicate that the formation of strain-induced ferrite at the prior austenite grain boundaries accompanied by deformation inhomogenities in the austenite grains change the effectiveness of allotriomorph ferrite on acicular ferrite formation from active to inert one.

Jan 1, 2004

By M. A. Mahtab, A. S. Burgess, R. G. Charlwood, P. O. Sandstrom, J. L. Ratigan

"Addressing a current operating and environmental concern, this paper first presents an overview of the design program for an underground radioactive waste storage vault. It then reviews the construction, operational and thermal-mechanical aspects of such a project. The relevant experience from major underground construction projects is reviewed and the paper concludes with brief comments on the design-oriented research and development requirements . 1. IntroductionA program to develop techniques for the ultimate disposal of high-level radioactive waste into geologic formations was announced by AECL in 1975 (Tamrnernagi, 1976), and is discussed more fully in a later document (Boulton, 1978). Our paper summarizes the studies caried out, as part of the AECL waste management program, by the authors and associates on the development of design concepts for a vault situated in crystalline rocks of the type present in the Canadian Shield.The design studies have been carried out in three phases, the elements of which are described in Section 2.1 (also see Fig. 1). The general vault designs are presented in Section 2.2. These provide for emplacement of either immobilized fuel or solidified reprocessing wastes in a room-and-pillar facility at a depth of 1,000 m.Section 3 reviews the principal design considerations from the construction, operation and thermal-mechanical response aspects. The concepts have been studied in both temporal and spatial domains, and the requirements and responses assessed in each as appropriate.Section 4 briefly reviews the availability of relevant experience from previous major underground construction projects. Finally, in Section 5, brief comments are given regarding design-oriented research and development requirements."

Jan 1, 1980

By Lin Li, Ahmad Ghahremaninezhad

"In this paper, the electrochemical behavior of ferric and ferrous couple on the pyrite surface was studied by application of the chronoamperometry technique in an acidic solution at room temperatures and atmospheric pressure. The effects of the pyrite origin, ferric and ferrous ions concentration on the electron transfer kinetics of Fe3+/Fe2+ reaction were probed. Tafel behavior of all the test conditions were developed. The results showed that the ferric-ferrous reaction on pyrite electrodes with different origins have a common mechanism, despite different reaction kinetics. The exchange current densities of the redox reaction have the same magnitude of about 10-5 A·cm-2, which is far lower than the value reported for the gold and platinum electrodes, but larger than that of the chalcopyrite electrode. The cathodic transfer coefficients are between 0.4 and 0.5, while the anodic transfer coefficients appear unusual with the lowest value being 0.23. It was also demonstrated that an increase of one order of magnitude of iron concentration has no clear effect on the exchange current density and cathodic transfer coefficients of Fe3+/Fe2+ redox reaction.INTRODUCTIONPyrite, FeS2, is mostly considered as a gangue mineral which frequently coexists with valuable minerals and metals, such as gold, copper and nickel. Its separation from valuable minerals can be a costly process (Chandra & Gerson, 2010). In refractory gold ores, the fine gold particles are locked inside the pyrite structure. Oxidative leaching of pyrite is a hydrometallurgical method to destroy the structure of pyrite and expose the fine gold particles to the cyanide solution in the downstream cyanidation circuit. Pyrite oxidative leaching can be achieved by oxidation of pyrite via oxygen and ferric ion(McKibben & Barnes, 1986). In fact, pyrite oxidation by oxygen and ferric is a significant source of acid mine drainage(AMD), which adversely causes serious environmental problems(V. P. Evangelou, 1995).The pyrite oxidation mechanism is accomplished in three consecutive steps: (i) pyrite is oxidized by oxygen and ferrous ion formation (Eq. 1); (ii) ferrous oxidation by oxygen and ferric ion formation (Eq. 2); (iii) pyrite oxidation by means of ferric ions (Eq. 3). Hence, both oxygen and ferric participate in the pyrite oxidation process (Moses & Herman, 1991):"

Jan 1, 2016

By Kurt D. Mitchell

"This paper discusses general application for A C variable frequency drives in the mining industry. A review of induction motors characteristics, adjustable frequency controller fundamentals, and three commonly used controllers is presented. General application guidelines for the three different types of controllers; variable voltage input , current source input and pulse width modulated are then reviewed in detail, and an example of the economic benefit of this technology is discussed. IntroductionSoon after static DC variable speed drives were well established in industry, a need for static AC variable speed drives was seen. The first technical papers describing possible systems appeared in the mid-1960s, with commercially available units arriving in the early 1970s. Without exception, static AC drives are substantially more complex than their DC counterparts, but they have some very desirable properties. As compared to DC motors, AC motors are less costly, physically smaller, more reliable, require less maintenance , easily sealed, have good load regulation, are able to run at higher operating voltages, and have little danger of over-speed runaway . These properties are particularly desirable in explosion-proof, submersible or difficult accessibility applications.Variable speed AC drives are now a proven technology. available in packages from Sub-horsepower to hundreds of horsepower, from 115VAC to 4160 VAC. This paper covers the principles of operation of three common types of controllers, application criteria, motor consideration and finally an example of how an AC variable speed drive can pay for itself in terms of energy savings."

Jan 1, 1986

By Dave N. K., T. P. Lim

"A fast, reliable and accurate method for radium-226 determination in environmental water samples has been devised, using an alpha spectroscopic technique. The correlation between barium-133 and radium-226 in the barium-radium sulphate precipitation mechanism was studied and in the limited experimental recovery range, the coefficient of correlation was r = 0.986. A self-absorption study for various barium carrier concentrations was also undertaken to obtain the least broadening of alpha energy line widths. An optimum value of 0.3 mg barium carrier was obtained for chemical recovery in the range of 85%.IntroductionWith the increase in uranium mining activities, the migration and spread of radioactivity via various environmental pathways is of great concern. Because of its inherent biological hazard and relatively long half-life, (approximately 1620 years), raidum-226 is frequently monitored as a measure of radioactive contamination of the environment. It is, therefore, necessary to modify existing methods for rapid determination of radium-226 in environmental samples for quick corrective measures in the event of seepage, dam leakage or discharge violations."

Jan 1, 1981

By K. G. Markkola

Since 2005, Compafifa Contractual Minera Candelaria (CCMC) has defined various strategies which aim to optimize the usage of the available energy in each of the SAG grinding circuit modules (SABC-A configuration). For this purpose, the use of larger size balls along with operating with an optimum balls/load ratio has been implemented. Additionally, in the ball mills, the amount of balls in relation to the equipment's usable diameter has been optimized. In the pebble crushing circuit, the percentage of material passing 12 mm (112 in) product has been increased by 15% by: (1) modifying the crusher mantle profile, (2) implementing a strategy for maximizing the power in each crusher, (3) using continuous improvement tools (Lean - Six Sigma), (4) redesigning SAG mills discharge grates, and (5) changing discharge grates in order to control the crusher feed size distribution profile. All these activities have improved plant throughput by 1,000 t/d with no significant capital investment. As part of the energy consumption optimization study, we have considered determining the optimum operational rate of each SAG mill, in relation to the mill liner life and also the improving the control strategy in conventional grinding.

Jan 1, 2007

By R. M. Porter

PILLAR extraction at the Sullivan Mine bas been in progress for over twenty-five years and bas .involved progressively larger pillars. The largest pillar blasted to date exceeds one million tons and is described in this paper. This blast is believed to be one of the largest to take place entirely under-ground. The Sullivan Mine, owned by The Consolidated Mining and Smelting Company of Canada Limited, is located in the southeastern corner of British Columbia on the east flank of the Purcell range overlooking the twenty-mile wide Rocky Mountain Trench (Figure 1). The orebody is a bedded replacement deposit in argillites, varying in thickness up to 300 feet, but averaging about 80 feet. Above the 3900 Level, the dip varies from nearly horizontal to 40 degrees; be-low the 3900 Level it varies from 45 to 20 degrees (Figure 2). Pillar extraction follows a plan of retreating outward from caved areas. The size of each blast is determined by the effect which the removal of support

Jan 1, 1961