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By C. C. Li

Traditionally, strong and stiff devices, such as fully encapsulated rebar bolts and concrete lining and arches, are preferred for underground rock support. The attention is paid to the strength of the devices in such support designs. It has been observed in engineering practice that support systems composed of stiff devices are often subjected to premature failure in high stress rock conditions. In the past decade, yield support devices have been employed to improve the performance of rock support systems. A rock support system usually consists of both internal and external devices that are installed within the rock mass and on the free surface of the rock, respectively. Great efforts have been made to make support devices yieldable in the past years, but the efforts are focused on different aspects in the tunneling and mining branches. In the tunneling branch, the focus has been put on the development of external yield devices, such as Lining Stress Controller (LSC), Honeycomb element and compressible concrete, which are embedded in shotcrete liners, while in the mining industry the efforts has been on the development of yield rockbolts, such as the cone bolt and the D-Bolt. The internal and external support devices are not compatible in their deformation capacities in the current rock support systems even though yield devices have been employed. All the devices in a support system should be deformable and compatible in deformation capacity. With such a support system, premature failure of individual support devices could be avoided and the service life of the support system is prolonged. It is a trend at present to take into account the energy absorption capacity, instead of simply the strength, of support devices in rock support design.

Jan 1, 2015

By H. Staton, V. Suontaka, E. Sharifi

"Flotation circuits are typically controlled using on-line elemental assays obtained from the slurry lines. In base metal applications, X-ray fluorescence (XRF) analyzers are the most common instruments for elemental analysis of the slurries. Eagle Mine has been utilizing a Courier XRF Analyzer since 2014. Typically, in XRF analysis, the sampling rate is 10-25 minutes which is good enough for manual process control. In 2018, Eagle Mine upgraded the Courier XRF analyzer with the Rapid Measurement module that is based on reflectance spectroscopy. This option reduces the sampling rate to 10-15 seconds, while maintaining the superior accuracy of the XRF analyzer. This paper presents the results from implementation of Rapid Measurement at Eagle Mine.INTRODUCTION Eagle mine is an underground mine producing nickel and copper concentrates. Eagle Mine is owned by Lundin mining and located in the Upper Peninsula of Michigan, USA. The Humboldt Mill, previously an iron ore processing facility, was refurbished in 2014 and is used to process the ore and produce separate nickel and copper concentrates. Approximately 2,000 metric tonnes of ore is milled per day. Ore is processed using a conventional crushing followed by single stage ball mill and flotation. Nickel and copper concentrate are transported to facilities in North America via rail car. A bulk copper-nickel concentrate is produced by separating the copper and nickel minerals from gangue material by flotation. The copper-nickel bulk concentrate is reground, followed by one stage of cleaning to reject further gangue minerals. The bulk cleaner concentrate is then subjected to a final flotation stage where the copper and nickel minerals are separated from one another through the addition of lime. Final concentrate grades are 14% Ni and 2% Cu in the nickel concentrate and 31% Cu and 0.8% Ni in copper concentrate."

Jan 1, 2019

By C. Desmeules

"Carbon addition in the oxide pelletizing process is a big concern at the Sidbec-Normines pelletizing plant since 1976.Laboratory pot-grate testing carried out before the initial start-up of the Port-Cartier plant indicated that the nominal pelletizing grate capacity could be increased by fifteen per cent with a suitable carbon addition. Also an improved induration cycle offered the possibility of a significant energy reduction within the process with no adverse effect on pellet quality. A one-month plant scale program duplicated the lab test results and confirmed the anticipated cost saving by using these techniques. Since March 1980, Sidbec-Normines used coke addition as a current operation.This paper reviews briefly earlier laboratory and in-plant test work carried out to investigate the effects of adding carbon materials to the Fire Lake hematite concentrate, and presents operation techniques and plant results of carbon addition in the Port -Cattier pellet plant.IntroductionThe Sidbec-Normines pelletizing plant at Port-Cartier, Quebec, is designed to produce six million ton s per year of oxide pellet s. It is a Dravo-built two-line plant; one line to produce three million s tons per year of blast furnace grade pellets averaging 5.5 per cent silica, and another line of three million ton s to produce direct reduction grade pellets of about 2.0 percent silica.The laboratory pot-grate test program was conducted in 1977 at the British Steel Corporation Research Laboratories in England, with the assistance of J .E. Appleby, consultant to British Steel Corporation (overseas services) Limited.The purpose of that test program was to determine the optimum energy saving cycle and to study the physical and metallurgical effects on blast furnace and direct reduction pellets."

Jan 1, 1983

By G. M. Ritcey, M. Silver

"The processing of uranium ores produces tailings that could constitute environmental problems. At most operations the tailings are dumped into a designated area, with the ultimate acid drainage occurring if sulphides are present, together with the release of metal constituents to the rivers and streams. If the chemical reactions occurring within the tailings could be predicted, perhaps methods could be developed to either increase or decrease 'the rates of reaction. One such study has been in progress at CANMET during the past three years. The paper describes the use of Iysimeters containing low-grade and complex uranium tailings to determine the effects and interactions of bacteria, sulphides and solvent extraction organics on the release of radionuclides and on acid production. A simulated rain cycle nine-fold the normal was used and the Iysimeters were subjected to timed intervals of light and darkness. As a result, the tests simulated a 25-year period.IntroductionAlthough Canadians derive major benefits from uranium, there are environmental and health consequences, not yet fully understood, from the associated mining and milling operations. A major project at CANMET (Canada Centre for Mineral and Energ y Technology) has the ultimate goal of ensuring that any adverse effects on man and environment, now or in the future, resulting from the processing of uranium should be acceptably low. The magnitude of the task was exacerbated by the fact that the increased demand for electrical energy and the resultant increased prices for uranium oxide during the 1970s led to a rapid expansion in the industry. Annual world demand for uranium was expected to increase 12-15 fold in the next quarter century, with annual requirements of between 200,000 and 300,000 metric tonnes anticipated by the year 2000. Currently, the demand is low and the prices for the oxide have decreased."

Jan 1, 1982

By Minoru Fujita, Ian M. Johnson

"A helicopter-borne geophysical survey was flown in 1978 over selected areas on Kyushu Island, Japan. The principal sensors were a moving source electro-magnetic system and a magnetometer. Maps of apparent resistivity were generated from the EM data. Based on the resistivity signature of known deposits within the survey areas, targets were selected for ground follow-up. Drilling of one such target in late 1980 resulted in the discovery of a gold deposit from which full production will begin in the summer of 1985. The deposit contains a minimum 120 tonnes (3.86 million ounces) of recoverable gold and is the largest in Japanese history. The deposit is in a geological setting previously unsuspected of hosting precious metal deposits. The case history suggests a preferred exploration strategy which might be employed in other similar geological environments.IntroductionThe Hishikari area is located some forty-five kilometres north of Kagoshima city, Kagoshima Prefecture, Kyushu Island, Japan (Fig. I). The area and its environs is one with a number of gold deposits which have been worked with varying results since the late 1800s. The large st deposit in terms of recovered gold is the Ohkuchi (or Oguchi) Mine (Fig . 2) which was recently closed due to exhaustion of reserves. The Ohkuchi Mine started production in 1896. A total of 22.2 tonnes (714 ,000 ounces) of gold, with an average ore grade of 13.6 grams/tonne (0.39 ounces/ton), was extracted over the Life of the mine.In an attempt to discover new deposits , the Metal Mining Agency of Japan (MMAJ) carried out a regional geologic mapping program of the area between 1975 and 1977. This was followed by a helicopter-borne electromagnetic and magnetic survey. The airborne survey was flown by Scintrex and the compiled results presented to MMAJ in early 1979."

Jan 1, 1985

By Chaluvadi K. Sridhar, Prashanta K. Chatterjee

"IntroductionThe planning of an underground coal mine requires a complex blend of technical expertise, experience and subjective design criteria implemented by the mining engineer. Currently the procedure is largely manual and requires considerable resources to generate a single mine plan. Often three or four people are assigned to work in the development of a single draft layout. Evaluation of the layouts is also tedious as it requires many repetitive calculations. The evaluation of layouts developed manually generally attempts to derive a single economically feasible solution. Operational constraints in underground coal mining such as manpower, time, equipment, etc., do not allow the generations of more than one alternative layout. As a result, the first plan is generally the only one considered.Computer-aided mine planning can automate many of the manual procedures and calculations involved in mine planning thus allowing to evaluate man y layouts and mining strategies and to select the optimum plan with confidence. An optimized planning procedure will also provide the capability to evaluate mine performance continuously and critically, thereby helping to maximize return on investment. Although recent advances in computer graphics have provided the hardware necessary for developing and evaluating min e plans rapidly, software that will allow the mining engineer to make use of the new technology is slow in developing. The need for such software packages has been recognized and ackowledged.At several sessions in recent conferences on the applications of computers in the mining industry, the use and benefit s of computer-aided mine planning were discussed. However, there were few papers presented that referred to actual applications of interactive graphics to underground mine planning. The emphasis of this study is toward the development of a completely integrated computer-aided underground mine planning package that integrates geological modeling, engineering design and planning"

Jan 1, 1986

By C. Gravel, A. Fathi, P. Rivard, G. Ballivy, Z. Moradian, M. Quirion

Numerous schemes have been proposed in the past to evaluate the shear strength of rock discontinuities based on in situ and laboratory testing. Due to scale effects, in situ testing is the most reliable way to assess the shear strength parameters. However, practical reasons often impede this kind of testing. This is unfortunate because advances in theoretical rock mechanics are still dependant on qualitative experimental works. This paper presents a mobile high capacity shear apparatus developed for in situ direct shear testing of discontinuities along with testing methodology. The apparatus has the advantage of being simple, although of high capacity, and can be moved to different site locations for other tests. The in situ test was performed on a natural rock outcrop of schist with subvertical schistosity. A concrete block 50 x 50 cm with a base layer of high strength mortar was cast on the rock surface. Prior to the test, the concrete block was lifted and repositioned to have an unbonded joint but with interlocking asperities. The shear load was applied perpendicularly to the schistosity direction. The test was conducted in a constant normal load (CNL) condition. Both normal and shear loads were applied manually. The instrumentation consisted of two load cells for shear and normal loading, eight displacement laser extensometers for shear, normal, and lateral displacements and fourteen acoustic emission sensors for monitoring evolution of asperities’ degradation during the test. The friction angle obtained is 72° for the peak and 58° for the residual. The high values of friction angle indicates that first-order roughness and good interlocking of the joint surfaces can result in high shear strength parameter values in a rock generally regarded to have low values.

Jan 1, 2015

By Yue hua Hu, Wei Sun, Pan Chen, Li Wang, Runqing Liu, Central South University

"The flotation separation of muscovite from quartz was investigated using mixed sodium oleate/dodecylamine (NaOL/DDA) collectors. The flotation experiments were conducted on single minerals and their collecting performances were studied by means of adsorption amounts and molecular dynamics simulation. Flotation results show that muscovite presents good floatability while quartz exhibits poor floatability in alkaline condition. Adsorption amounts show that both NaOL and DDA can absorb onto surfaces of muscovite and quartz in presence of mixed surfactants. Molecular dynamics simulation indicates that DDA plays an important role in the adsorption of mixed surfactants on these two mineral surfaces. The molecules of mixed NaOL/DDA are arranged in a rigid and well-ordered packing on muscovite (001) surface. Only a few DDA adsorb on quartz directly, and rest DDA and NaOL molecule exist near by the quartz surface, forming a hydrophilic cylinder-like structure. This study may provide guidance for the flotation mechanism and application of mixed anionic/cationic collectors.INTRODUCTIONIn the past decades, there has been an ever-increasing demand for muscovite (KAl2(Si3Al)O10(OH)2) because of its potential applications in cosmetics, construction and metallurgy industries (Barlow & Manning, 1999). Besides, muscovite is an important carrier for some rare metals, including vanadium, titanium and lithium (SsuerrN, 1979). Quartz (SiO2) occurs as the main gangue mineral in muscovite ores, which results in a low purity of muscovite and limits its wide applications. Therefore, there is an urgent need for the beneficiation of low grade muscovite ores. Many studies remove quartz by screening and gravity separation in virtue of their differences in shape, hardness and density. However, these methods undergo poor efficiency in case of small particle size (below 50µm) of muscovite and quartz (Liubakka, Sullivan, Lamphere, Corradi, & Dykhuis, 2011; Santos, Franca, & Ogasawara, 2011)."

Jan 1, 2016

By N. A. McPherson, P. C. Stevens, A. J. Rigby

"There has been a consistent move in recent years to continuously cast small billets while utilizing ceramic stream protection between tundish and mould. The need to have ceramic stream protection has developed from a need to improve billet surface quality by submerged pouring. The need to protect the ladle to tundish stream in conjunction with tundish to mould protection is explained.The continuous casting of thin slabs is at the development state and will require a great deal of ceramic development to ensure the economic viability of the project. An insight is given to the main problems.IntroductionDuring the early development period o f the continuous casting of steel in the late 1940s and 1950s, much of the work was carried out on small cross section products. For example, the continuous casting of 50 mm square billets was carried out on a production scale in the United Kingdom at Barrow. Slab casting was initiated on a production basis on 100 mm thick stainless steel slabs at Atlas Steel, Weiland, Ontario. In the case of slab casting the thickness increased gradually until it was similar to Slabbing Mill feedstock , i.e. in the range 200 mm to 250 mm , although stainless steel continued to be lower at around 185 mm thick.For billets , a significant proportion of steel is now cast at around 100 mm square which creates specific difficulties when casting with a submerged pour - mould powder practice. The move back to smaller cross sections is further emphasized by the current interest in "" Near Net Shape Casting"" . If this move continues, then significant development will be required to create the refractories used between tundish and mould in the continuous casting process.Two specific areas which will receive attention are; (I) the casting of small cross section billet s; and (2) the casting of thin slab."

Jan 1, 1990

By M. Walmsley, D. Maynard

"This paper describes the use of terrain and soil information in the planning of mine developments, particularly in satisfying many of the existing provincial regulatory requirements. It is also noted that, if properly used, this will provide a solid data base for cost-efficient and environmentally acceptable land use.IntroductionIn planning the development or expansion of a new or existing mine, engineering alternatives are judged on many factors, one of which is the environmental influence. Ecological investigations, ensuring consideration of a rational approach to managing land use and environmental impacts, should be carried out prior to a final decision being made on mine development. The Pit Slope Manual (CANMET, 1976) suggests that both baseline aquatic and terrestrial data be collected and interpreted in such pre-mining surveys. In British Columbia, planning procedures now exist which incorporate biophysical studies to help identify, assess and manage major environmental impacts associated with mine development.Methods outlined in the Guidelines for Coal Development (E.L.U.C., 1976) have been successfully applied in recent years. Following this example, the Inspection and Engineering Division of the B.C. Mineral Resources Branch prepared guidelines to help expedite the development of new base metal mines (Procedures for Obtaining Approval for Metal Mine Development; Ministry of Energy, Mines and PetroleumResources, 1979).The metal-mine guidelines require the proponent of a new mine development project to prepare a two-stage assessment proposal which systematically moves from a preliminary feasibility study (Stage I) to a final project design (Stage II), including application for regulatory approvals. One purpose of the Stage I report is to provide a description of the existing environmental conditions that could be affected by the proposed development. A preliminary environmental impact assessment should also be reported. The Stage II report will contain detailed assessment and management of environmental impacts."

Jan 1, 1981

By Richard S. Allen

"The casual visitor is not apt to think of the Adirondacks as a one-time hive of mining and manufacturing activity. However, where there are mountains there are usually minerals and northern New York State is no exception.The Adirondacks are a rocky shield, a great stone cap pulled down over what is now northern New York. The bedrock consists of layered metamorphic rocks which were once sandstones or limestones on the bottom of a shallow sea that covered the region 1000 million years ago. The highlands are composed for the most part of the igneous rock anorthosite. Ancient earth upheavals at temperatures of at least 750°C mixed molten masses of anorthosite and the minerals it contained with the older metamorphic rock, resulting in deposits of iron-titanium oxide s, red garnet and other valuable minerals. Of these, the most readily recognizable was iron.The first hint of the existence of iron ore in the Adirondack Lake Champlain region of upper New York State seems to have come from a Swedish naturalist, Peter Kalm (1716-1769), who travelled through French Canada and visited the military outpost of Fort St. Frederic in 1749. In July of that year, Kalm wrote:""Among the kinds of sand which are found on the shores of Lake Champlain; one is black and the other garnet-colored... and they sparkle when the sun shines. All the grains of this sand without exception are attracted to the magnet, the uppermost or black sand being about a quarter inch deep...""Concerned primarily with the fur trade, the officers and men who occupied this remote bastion of La Belle France were apparently unaware of the industrial and commercial possibilities beneath their feet. No deposit of iron was then known to exist any closer than the Three River s area in Lower Canada."

Jan 1, 1983

By T. Alan O'Hara

"The decision to invest capital in developing a mine and constructing a mineral processing plant and services is usually made after a feasibility study shows 'that the estimated future cash flow from mine operations will yield an adequate return on the estimated capital expenditures.The actual return on investment may differ substantially from that estimated in the feasibility study, because of the probabilities of errors in estimating capital costs, ore reserves, operating costs, mineral revenue and operating productivity. This paper outlines the R.S.S. (root sum of squares) risk analysis procedure of computing the overall probability of the actual project D.C.F. (rate of discounted cash flow), differing from that estimated in the feasibility study.Variation in Project D.C.F.It is assumed that a feasibility study of the project has been completed which has defined the estimated values for all the project parameters, such as ore reserve tons and grade, capital cost, concentrate recovery, metal revenue, daily milling capacity and operating costs.The financial analysis of the mining project will have determined that the cumulative cash flow will yield an expected D.C.F. on the capital cost if all project parameters attain the estimated values. If, however, the actual value of any parameter varies from that estimated, the actual project D.C.F. will vary from the estimated D.C.F. Risk analysis methods attempt to determine the overall effect of probable variations in the estimated values of all project parameters on the D.C.F. of the mining project. This overall effect is expressed as a probability profile, which shows the likelihood of actual D.C.F. values greater or less than that estimated.Thus, a completed risk analysis of a mine project, with an expected D.C.F. of 15.51%, would display the characteristics shown in the preceding diagram."

Jan 1, 1982

By Alan R. Holt

"This paper provides an overview of the use of uranium and coal in Ontario Hydro's generation program. The dynamics of available supply sources including mining and transportation infrastructures and regional considerations are described. Included is a discussion of needed procurement strategies, both in place and planned, to meet fluctuating fuel requirements while ensuring adequate supply security and cost effectiveness. IntroductionDuring the first half of this century, Ontario Hydro or the Hydro Electric Power Commission of Ontario, as it was then known substantially supplied all of the province's electricity needs from a large number of hydraulic generating stations. Although hydraulic power still provides a very significant part of Ontario energy requirements, this paper will concentrate on the role of uranium and coal in their generation program. To provide a perspective on the importance of these two fuels, Figure I shows the approximate value of each for the past few years in relation to Hydro's total operating costs. The trend toward increasing nuclear output and a corresponding decline in coal use is also clearly illustrated.Figure 2 shows the currently installed capacity of their three main energy sources, hydraulic, nuclear and coal and the 1986 production totals for each, followed by Table I which compares the average operating or running cost on the basis of dollars per megawatt hour for each type of plant. It demonstrates dramatically why Ontario Hydro base load s its hydraulic and nuclear plants, and why coal has become the swing fuel on the system. Although they have a 1200 megawatt plant in Toronto with natural gas-burning capability, and a 2000 megawatt oil-fired station near Kingston, both are presently mothballed and have not been considered in this paper.This paper starts with a user's perspective of the nuclear fuel supply situation which will be discussed in relation to the usual considerations of security, flexibility and cost."

Jan 1, 1988

By Robert B. Parsons

"The pendulum in Ottawa has swung dramatically from fiscal policy to monetary policy over the last several years. International trends indicate that the pendulum has to start its swing the other way, if Canada's mining industry is to maintain its preeminent position in the global mining arena. This article, which is based on a paper presented by the author at the 37th Annual Meeting of the Newfoundland Branch of CIM, identifies these trends and how they could interact with Canadian policy.IntroductionThe title of this paper is not a very imaginative or catchy one, but it states the topic quite succinctly, if not tersely. This paper looks into a crystal ball to see what might be in store for mine financing over the balance of the current decade.In the event that the reader feels some trepidation about the prospect that such a paper could seek to be the definitive work on the subject, it should be made clear at the outset that this is not the case. The author is, after all, not an economist, a scholar, a financial analyst, or a soothsayer, but is rather a simple accountant who has been closely involved with the mining industry, and the financing thereof, for some twenty years.The paper recognizes that, while a mine may be born when production begins, the mine is conceived when exploration starts. As this act of conception is obviously an essential part of mining, the financing of exploration is also covered in this paper. To attain a focus, this paper approaches the topic of mine financing in the nineties as follows: first, the major emerging forces in the industry are identified: and, second, the implications of each of these forces on financing are considered."

Jan 1, 1991

By D. P. Wilkinson

There are significant global environmental and supply issues with existing energy paths today . Global emission and fuel regulations, global fuel and power structure, energy security, and cost are driving new technology and non-conventional approaches . Fuel cells will play a significant role in the strategy to effect positive global change, increase fuel efficiency and decrease dependency on traditional fossil fuels. Fuel cells do not require recharging, just refuelling and a wide range of fuels are possible with hydrogen being the most desirable. Technical progress as well as investments in fuel cells for transportation, stationary, portable, and micro fuel cell applications have been dramatic in recent years. The present view is very optimistic for fuel cell power generation and the status is presently at the field trial level, or early commercialization stage, moving into volume commercialization. A number of demonstration programs are in progress worldwide such as the California Fuel Cell Partnership which involves original equipment manufacturers (OEMs), fuel providers, transit authorities, state and government bodies. Fuel cells and a hydrogen infrastructure are key to a long-term solution to global energy issues. Fuel cells will need to be competitive on an economic basis with the established and highly developed internal combustion engine and other forms of power generation There has been significant technical progress in a number of fuel cell areas including power density, transient / dynamic response, multiple fuels, cost potential, reliability and durability. However, significant technology gaps still remain today. This presentation will focus on the status and progress of the fuel cell today, current fuel cell research and development, the challenges going forward, and the future view of the fuel cell and it's impact on global energy issues.

Jan 1, 2005

By Robert B. Parsons

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

Jan 1, 1983

By R. Tessier, R. Grant, C. Bazin

"Brunswick Mining has investigated grinding media optimization for the purpose of improving the flotation feed and regrind product size distributions to enhance metal recoveries. The paper presents findings in the on-going testing of various sizes and shapes of grinding media. Breakage rates are used as an aid to assess the effect of grinding media. Results of empirical and phenomenological analyses demonstrate the importance of adequate selection of media sizes on the milling operation.INTRODUCTIONBrunswick Mining and Smelting operates one of the world's largest lead and zinc mine near Bathurst, New-Brunswick. The No. 12 ore body is an extremely fine grained volcanogenic massive lead, zinc, copper, silver, iron sulphide body between two metamorphosed sedimentary and felsic volcanic rock units. Pyrite content is about 60% with 20% non-sulphide minerals, mainly silica and chlorite. The operation is currently processing 10,500 tonnes of ore per day in conventional crushing, grinding, differential flotation and dewatering circuits. Details on the circuit can be found elsewhere (e.g. Hendriks and Ounpuu, 1985; Grant et al., 1991).The mill has operated for more than 25 years and despite the past milling experience, there has been much disagreement as to the required grind size. Since 1964, fineness of the flotation feed ranged from 60% to 80% passing 400 mesh (37µm) and averaged slightly over 71%in1992. Results from mineralogical analysis (Petruk and Schnarr,1981; Coleman, 1988), Brunswick metallurgical laboratory (Grant et al., 1991; Shannon et al., 1992) and Lakefield pilot plant tests (Hendriks, 1984; Hendriks and Ounpuu, 1985) clearly indicate that improved metal recoveries can be achieved by an increase in the fineness of grind, and more specifically by maximizing the amount of material in the 15-25µm range."

Jan 1, 1993

By C. L. Reichardt

Pressure exerted on gold producers by regulators, project financiers and civil society in the wake of the Baia Mare tailings spill in Romania during 2000 prompted most responsible gold companies to sign up to the International Cyanide Management Code for the Manufacture, Transport and Use of Cyanide in the Production of Gold (the Code). The Code stipulates a ?cradle to grave? approach more comprehensive than that applied to any other mining reagent and poses particular challenges for operators who use cyanide-bearing tailings for backfill. This paper examine some of the challenges for Code compliance facing deep underground gold mines that employ backfill technology, most particularly the requirement to demonstrate that the potential migration of cyanide (and its degradation products) from emplaced backfill will not have an unacceptable impact on worker health and safety or the receiving environment, either during mine life or after closure. Although the Code only contains a single reference to backfill, more careful consideration confirms that most sections of the Code that deal with tailings management are potentially applicable to mines where tailings material is used for backfill, as are certain principles pertaining to aspects of operations, worker safety, emergency response, training and dialogue with stakeholders. For gold mines of the Far West Rand, the most significant cyanide-related risks associated with backfill operations relate to worker exposure to cyanide-bearing seepage and HCN gas. There is potential for seepage of cyanide-bearing water from backfill to compromise the beneficial use of surface and groundwater, and thus impact on downstream users and ecosystems. However, the extreme depth of mining and the specific geological and hydrological controls on the Far West Rand suggest that the potential environmental risks associated with backfill are likely to be considerably less significant than the cyanide-related risks to the workforce.

May 1, 2007

By So-Yeong Lee, Moosang Lee, Seung Hwan Ahn, Ho-Sang Sohn, Jongshin Chang

It is necessary to understand the characteristics, phase changes and chemical reactions of flue dusts introduced from a furnace to an off-gas line in order to achieve the stable operation and the improvement. This study is to develop the dust reaction model for chemical reactions of dusts in an uptake shaft of smelting furnace and a waste heat boiler. Phase equilibria and reaction paths in this system were determined by thermodynamic calculation with experimental and industrial data. The oxidation reaction rate of dusts was determined by the gas film mass transfer controlling. And the sulfation reaction rate was evaluated by the unreacted shrinking core model. Kinetic parameters were estimated by reference data including industrial ones. The present study with the developed model shows various effects of temperatures, dust particle sizes, and O2 gas partial pressures on dust reactions. INTRODUCTION The flue dusts from a copper smelting furnace move along a furnace off-gas stream into an uptake shaft and a waste heat boiler (WHB) and electrostatic precipitator(s). It is necessary to control the dust quality in order to stabilize the operation because the sticking behaviors differ depending on the phase of dusts. Phase changes of dusts are caused by chemical reactions at given conditions such as temperature and partial pressure of gases. Therefore, it is required to understand the phase changes and chemical reactions of dusts in order to perform the improvement and stable operation. The present study carried out the investigation to understand their fundamental knowledge. Especially, this study was focused on the kinetics of chemical reactions of flue dusts, developed the model. In particular, the scope of development and utilization of the model was defined as the uptake shaft of the Mitsubishi S furnace and the S-WHB radiation section in the Onsan smelter. Information needed for the modeling work referred to data from these processes.

Jan 1, 2019

By Bertrand Wolfman, William E. Stanley

"This paper reviews the traditional mine accounting systems, including ""custodial accounting"" and unit costing, and then suggests that the use of flexible budgets represents a more suitable method of reporting costs in order to assist the mine manager in improving productivity. Examples of various applications are given to show that the result is a clear reporting structure.Custodial Accounting is Emphasized in Traditional SystemsTraditional mine accounting has been mainly concerned with the accuracy of financial reporting to ""head office"" for the use of the directors and the company's bankers and shareholders. This is often called custodial accounting and it represented the main purpose of accounting when first developed in Europe hundreds of years ago. This important development permitted the establishment of enterprises which were separated from their owners because they could rely on accurate financial reports of management's stewardship.As custodial accounting is fairly broad and historical in nature, it is often not very useful to the mine manager for ongoing monitoring of performance of mining, milling, maintenance, and other support and staff groups. In spite of the considerable investment in accounting staff and computer support, many accounting systems have not been upgraded so that they accurately reflect workplace performance on a weekly or monthly basis.Budgets are Often FixedMany mines today also still emphasize fixed budgets. Thus, the mine plan which is set in the fall of one year is converted to a monthly tonnage and detailed dollar budget for periods of up to sixteen months in the future. The only certainty in this plan is that actual events will differ; timing, mix of mining methods and production volumes will differ on a monthly basis.Unfortunately, the fixed budget has no capability to reflect these operational changes. It is frozen for the full year. The result is that actual results will inevitably be compared to an outdated target."

Jan 1, 1982