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By Walter Küng

The Henderson Coarse Ore Conveying System is a three flight belt conveyor system transporting primary crushed molybdenum ore 24 km (15 miles) underneath the North American Continental Divide. One of the conveyors is 16.8 km (55,200fi) in length with 8,200 kW (11,000 HP) of installed power. The overland conveyor contains 11 vertical curves and 9 horizontal curves, some with radii as small as 1,500 m. he system began full operation in December 1999 and is one of the longest and most complicated belt conveyor systems yet constructed. he design of this conveyor system utilized many innovative engineering concepts including low-energy belt covers, low-resistance idlers, torque-controlled tail drives, combined gravity and active winch take-up systems, small radius horizontal curves and belt turnovers. his paper reviews the start-up of the system, discusses the success of the design and addresses the lessons that can be learned from the first 4 years of operation of this unique conveyor system

Jan 1, 2004

By H. Polat, S. Chander

Relatively large amounts of hydrocarbons such as fuel oils are often needed in the flotation of low rank coals. The amount of oil can be decreased considerably by using surfactants as promoters. The reagents that are good candidates as surfactants to promote hydrophobicity can also act as emulsifying and wetting agents. Because the physical and chemical variables influence various subprocesses in different ways, their influence on the performance parameters is complex. The results of laboratory tests are presented to show that the dual role of reagents can be judiciously exploited to increase both the recovery and grade of the clean coal. The mode and order of reagent addition is critical in enhancing their efficacy as flotation promoters. The results demonstrate the benefits of proper conditioning of the pulp prior to flotation.

Jan 1, 1999

By K. Hanumantha Rao, P. K. Sharma

A pure strain of Paenibacillus polymyxa and mineral- adapted strains are used to bring about surface chemical changes on pyrite and chalcopyrite and, thus, theirflotation. Paenibacillus polymyxa was adapted by repeated subculturing in the presence of pyrite and chalcopyrite. The surface chemical changes of bacteria due to adaptation and of minerals after their interaction with bacterial cultures are evaluated by electrokinetic and infrared spectroscopy and are discussed with reference to their flotation responses. Interaction of bacterial cells, bacterial metabolites and whole bacterial cultures affected the Hallirnondflotation behavior of the sulfide minerals. The Xanthate flotation results show that pyrite, but not chalcopyrite, is depressed when the tests are carried out after interaction with chalcopyrite-adapted Paenibacillus polymyxa. This investigation demonstrated that the surface chemical properties of bacteria can be manipulated successfully to achieve the desired effects in the flotation process.

Jan 1, 2000

By P. Legast

Serpentinite minerals are available in large quantities from asbestos mining activity. The granular or fibrous serpentite, at temperatures greater than 700°C, will recrystalize into olivine, forsterite and enstatite. These minerals have been used and studied for decades and are environmentally safe. The thermal process changes the composition and properties of the original mineral. Therefore, the substitution of the original mineral cannot simply be made and the applications for these new synthetic minerals need to be redeveloped. The two original mineral forms allow a wide range of new synthetic raw materials which can be adjusted to specific applications or custom needs.

Jan 1, 1993

By C. O. Brawner

INTRODUCTION My first major involvement on a rock mine slope stability project was in 1966 after I had become a principal of Golder Brawner & Associates in Vancouver, Canada. I received a request from Kennecott to evaluate two serious rock slope failures adjacent to the concentrator on their British Columbia molybdenum property near Alice Arm, BC, which was under construction. A rock slope up to 200 ft* high had been excavated at a design angle of 700. The inspection indicated that several large blocks of about 1000 cu yd each had failed on steeply inclined joint surfaces. Stability was reduced by extensive seepage caused by heavy rainfall. In addition, considerable overbreak had occurred, indicating excessive blasting had been used to excavate the slope. A program was developed to rock bolt potentially unstable blocks that could slide on dipping discontinuities. Some rock was scaled back to the inclined joints, and drain holes were drilled to reduce water pressures. The project was completed successfully and within reasonable economics. As a result of this success, enquiries were received regarding other mining projects. This indicated the potential demand for rock slope engineering. As a result, I took one month off to meet and discuss rock mechanics and slope stability with various people internationally. These included D. Coates in Canada, E. Hoek in England, K. John and L. Mueller in Germany, M. Rocha in Portugal, and the US Bureau of Mines in Denver, CO. Early misconceptions Based on involvement in projects during the next few years, it was concluded that there were a considerable number of misconceptions that existed among some geologists and mining engineers dealing with surface rock mechanics. Some of these included: • Water is a lubricant. This is incorrect. Water reduces the shear strength along discontinuities due to buoyancy, which reduces frictional strength. It also reduces the cohesion of clayey-type rocks. • The optimum pit slope angle in rock is 45°. The optimum slope angle for safety and economics is variable and is influenced particularly by structural geology, water pressures, mine blasting practices, and the depth and degree of weathering. • The flattest angle for slope stability is dictated by the angle of repose of broken rock, about 370. Where clayey-type rocks or clayey infill in discontinuities exists, failure can occur at much flatter angles, requiring flatter slopes or artificial stabilization. • Uniaxial and triaxial tests provide the necessary shear strength parameters to design rock slopes. Most failures in rock slopes are controlled by directional discontinuities. Therefore, the direct shear test is the correct test to evaluate strength parameters for most problems.

Jan 1, 1987

By T. Ko, K. N. Han, C. S. Park, N. S. Kim, C. Yoon, H. Yoon

Quantitative analysis of Platinum Group Metals from ore samples and industrial materials using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS), Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES), Atomic Absorption Spectrometer(AAS), and X-ray Fluorescence (XRF) techniques was conducted and the performance of various techniques was compared. The effects of different matrices in the sample materials were compared and discussed for each analytical technique. The ICP-AES technique exhibited better accuracy than AAS but showed limitations in its application due to strong spectral interference in the presence of common matrix elements such as iron. The ICP-MS showed the lowest detection limit and less spectral interferences than the previous two techniques. The XRF technique was also applied to examine the total amount of PGM from industrial materials. Results from each analytical method on various sources were presented and discussed.

Jan 1, 2003

By Stephen R. Pogorski, Nicholas Busigin, Colin R. Phillips

The movement of radon away from its source in porous media is determined by two key parameters: the fraction of the total radon formed which enters the intergranular pore spaces, termed the emanation coefficient, and the transport processes which exist in these pores such as diffusion and convection. The first parameter, the emanation coefficient, is of primary importance since it is a measure of the actual amount of radon which is free to migrate within the media. The effects of particle size and radium concentration on the emanation coefficient were examined using a quartz-pebble conglomerate ore from the Elliot Lake mining district of Ontario. It was found that the smallest particle size examined (<74 µm) had the highest radium concentration and contributed the most to the radon emanation. A one-to-one correspondence between radium concentrations for the various particle size fractions and radon emanation was not observed. Samples were examined using scanning electron microscopy and very small particulates were observed to be present on the particle surfaces. When these very small particulates were removed from the host particle surfaces by rinsing, the radon emanation decreased by a factor of 17. This result indicates that most of the emanation comes from the very small particles. The effect of moisture on the emanation coefficient was examined qualitatively and a trend of increased radon release with moisture content was noted.

Jan 1, 1981

By G. Hargrave, K. W. Moloney, M. R. Stokes

In recent years drivage advance rates in the UK have in- creased from 35m per week in the 1980&apos;s to 100/150m per week possible today. These extended rates of advance have resulted in an increase in the potential methane, dust and heat generation at the drivage face. In order to disperse this additional pollutant load requires an increase of fresh air at the face. Although advance rates have changed, current auxiliary ventilation practice has not. UK mining law requires that the fresh air must be delivered to within 5m of the face. This has lead to the wide spread use of overlap auxiliary systems, since a pure forcing system set at this distance would lead to excessive airborne dust. UK mining law does not at present consider on-board mounted exhaust scrubber fans to constitute an effective overlap fan within mechanised drivages. In an attempt to determine whether working conditions could be safely and economically improved within mechanised drivages, a series of preliminary full scale gallery trials were con- ducted. A summary of the principal findings of these trials are presented together with an outline of a series of representative CFD simulations, scale model experiments.

Jan 1, 1997

By A. E. Hall

INTRODUCTION Underground gold mining operations are found in South Africa, U.S.S.R., Canada, the United States, Zimbabwe, Ghana , Brazil. Australia, China and many other countries. The methods used for extraction differ from highly mechanized trackless mining in the developed countries to the labour intensive systems of the third world nations. The climatic conditions in which mines are situated vary from equatorial to arctic. The rock temperatures and the depth of workings also vary significantly from shallow to extreme depth. The Western Deep Levels mine in South Africa is the deepest and exceeds 4.000 metres in depth with strata temperatures above 55°C. These major differences between mining fields result in significantly different ventilation problems in underground gold mines. The ore types also vary and some deposits have high silica contents while other mines extract sulphide ores. Methane may also be encountered in underground gold mines and can have a large influence on the ventilation practice. Several topics are currently of concern to operating mines and are reviewed here:- a) Air circulation and fans b) Mine cooling c) Permafrost operations d) Mine heating e) Control of diesel exhaust f) Gases, fires and explosions

Jan 1, 1988

By G. Adel, J. M. Richardson

Mine-to-mill optimization is a holistic approach to the optimization of mining and processing operations. Developed at the Julius Kruttschnitt Mineral Research Centre, it attempts to minimize energy consumption through the optimization of the particle size reduction process. The approach involves sampling and modeling of blasting and processing, computer simulation to optimize the operation and develop alternatives, implementation of the most promising alternatives, and sampling to quantify energy savings. The primary objective of the present effort is to adapt mine-to-mill technology to the aggregates industry. This paper presents an update of work being conducted at quarries operated by the Luck Stone Corporation of Richmond, Virginia.

Jan 1, 2006

By R. G. Eggert, M. R. Walls

A mining CEO&apos;s willingness to participate in risky investment opportunities significantly affects a company&apos;s strategic-investment decisions. Decision-analysis techniques provide a mechanism for measuring a CEO&apos;s risk tolerance and ability to make formal comparisons of risk propensity among mining firms. The authors developed a methodology for measuring CEO risk tolerance. The findings from a confidential survey of mining CEOs are presented. The results from the survey suggest that: •mining CEOs are overwhelmingly risk averse when considering investment decisions; •CEOs of small mining firms are significantly more risk averse than CEOs of large mining firms; and •there appears to be some differences between Australian and non-Australian CEOs regarding their willingness to participate in risky investments. The results of this survey suggest that CEOs are pursuing objectives other than, or in addition to, maximizing shareholder wealth and that they act to reduce the financial exposure associated with strategic investments.

Jan 1, 1997

By Pedro Marques Bernardo, Carlos Dinis da Gama

This paper presents a methodology for design and simulation of underground ventilation networks, based on the analysis of real situations, followed by the careful interpretation of the obtained results in order to implement their optimization. The method involves two basic steps: the construction of a complete ventilation data base for the mine, upon a series of care- fully previous surveying studies in order to determine the values of its ventilation parameters, and the simulation of relevant situations for the ventilation system optimisation. A simulation model, modified after the Hardy Cross method, allows the testing of various mechanical means located at different points of the network, aiming to determine the technical-economical feasibility of each solution. These simulations obey the directions of air flow in each point of the mine, as determined by the directions of the natural ventilation flow established in the data base that represents the network. The methodology was validated upon studies developed in ventilation network of the Panasqueira Mine (Portugal), in two situations: regular production (mechanical ventilation) and care- maintenance (natural ventilation).

Jan 1, 1997

By E. H. Cho, Q. Luo

Pittsburgh No. 8 coal, cleaned by conventional froth flotation, was oxidized in a 2-L Parr stirred bench-top autoclave. Autoclave tests were carried out for up to 5 hrs under the following conditions: 150 to 225ºC, 60 to 500 psi 02 and 15 to 60 g of coal per 600 mL of distilled water. The oxidation of coal was evaluated by measuring the total acidic group formed on the surface of the coal and by measuring the adsorption (under standard conditions) of calcium ion from a solution. The degree of oxidation of the coal increased continuously, without much leveling off, with increasing oxygen pressure. With increasing temperature, the oxidation of the coal increased sharply between 150 to 175ºC and then leveled off above 175 °C. The adsorption of calcium was >3% on coal oxidized under the most favorable conditions. The adsorption of calcium on coal increased sharply with increasing equilibrium pH. The loss in Btu was found to be sensitive to oxidation temperature. This study concluded that the optimum oxidation of coal is achieved over 3 hrs at high oxygen pressures (e.g., 500 psi) at ~170ºC. This study also concluded that, when measured in terms of calcium adsorption, Btu loss and reaction time, the oxidation achieved in an autoclave is far superior to that achieved in a fluidized bed.

Jan 1, 1996

By R. V. Ramani, K. V. K. Prasad, M. Swaminathan

Engineering design involves, in addition to numerical calculations, considerable amount of expertise and judgement. The expertise and judgement is required to conceptualize and idealize the problem, select a suitable mathematical model for the problem and to interpret the model results in terms of stipulated design constraints. In recent years, knowledge based systems (KBS) have provided the capability to integrate the qualitative experiential and expert knowledge with the quantitative knowledge for improved analysis and design of systems. A possible KBS architecture for mine ventilation system design was discussed by Ramani and Prasad (1987). The expert system (ES) component of the KBS supports the analysis and interpretation phases of the ventilation design process with an algorithmic program used for the solution of alternate designs. The purpose of this paper is to discuss the data and knowledge needs for developing such a system and a formal means of their representation on the computer. A number of ES shells were evaluated to explore possible development and delivery environments for the system. A brief summary of this evaluation is also provided.

Jan 1, 1989

By S. J. R. Lowrie, J. S. Edwards, A. D. Jones

A small scale model has been constructed to simulate air and gas flows on a full scale retreat longwall coal face. Scaling relationships were derived to define how the main aerodynamic properties of the full scale could be preserved in the small scale model. These scaling requirements include: a minimum value for the Reynolds number for the flow on the face in order to maintain turbulent flow with a constant non-dimensionalised coefficient of turbulent dispersion; a constant Richardson number to maintain similitude for the formation of layers of buoyant gas; scaling of the permeability of the waste so as to obtain the same proportion of seepage flow through the waste; pressure gradients due to the ventilation and to the density difference (between the air and the gas layer) were kept in proportion; and in the waste, the relative contributions of inertial dispersion and molecular diffusion were approximately in proportion. The complementary roles of computational fluid dynamics (CFD) and aerodynamic scale models for simulating mine ventilation are discussed. The physical model is described and an example presented of simulations of the effect of changes in mining condition on the effectiveness of gas control in retreat longwall coal faces.

Jan 1, 1995

By B. J. I. Adair, K. R. Weller

The bulk scavenger tailing from Aberfoyle&apos;s Hellyer Concentrator, which represents about one-third of the total tailing, runs about 2.5-3 g/t gold and 140-200 g/f silver. Both values are very finely disseminated, particularly the gold. Aberfoyle wished to establish whether ultra-fine grinding followed directly by cyanide leaching could be applied to the tailing for recovery of gold and silver. The work comprised the determination of gold and silver recoveries as a function of grind size and leaching time, the specific energy consumption required for continuous wet grinding of the tailing to the specified product size in a small horizontal continuous stirred mill, and an estimate of the rate of media consumption. The maximum extraction of gold, 23.3% was obtained from the finest product, with the highest cyanide concentration and longest leach time, confirming earlier work. A similar result was obtained for silver. The specific energy requirement for milling rose from 27.7 kWh/t for a P80 of 8.1 um to 219 kWh/t for a Pea of 2.3 um. The consumption of ceramic media was about 1.6 g/kg of final product. An extensive QEM&apos;SEM Trace Mineral Search on the unground tailing failed to identify any gold-bearing particles but did identify silver-bearing particles which displayed a variety of textural associations and liberation characteristics.

Jan 1, 1998

Jurist, educator and historian Neil Reynolds will be the keynote speaker at the National Mining Hall of Fame&apos;s 11th annual induction banquet on Sunday, Oct. 11,1998 at the Pointe Hilton Resort in Phoenix, AZ. Reynolds is Municipal Court Judge for the City of Leadville, CO, home of the National Mining Hall of Fame & Museum, and a fifth-generation resident of the community. His family staked mining claims on nearby Mount Massive in 1862. Judge Reynolds is a fulltime faculty member at Colorado Mountain College, Chairman of the Lake County Historic Preservation Advisory Board and practices law in Leadville. In announcing the speaker, Board Chairman Richard Moolick said seven inductees into the National Mining Hall of Fame will join 138 mining greats previously honored in the annual ceremonies. This year&apos;s inductees will be enshrined by Thomas Falkie, president and chief executive officer of Berwind Natural Resources of Philadelphia, PA. Moolick also announced that Jeffrey Clevenger will be the master of ceremonies for the induction banquet. Clevenger is executive vice president of Cyprus Amax Minerals, Englewood, CO and president of Cyprus Climax Metals, Tempe, AZ. A cocktail reception at 6:30 p.m. will precede the black-tie (optional) dinner, to begin at 7:30 p.m. For additional information, contact Esther Mellott at 719 486 1229. Here are the biographies, then, of this year&apos;s seven inductees to the National Mining Hall of Fame & Museum.

Jan 1, 1998

By C. F. Meyer

The recirculation of mine air in an underground colliery, has always been regarded as a hazardous practice in South African collieries. The Mines and Works Act and Regulations states that fresh air, flowing Into an underground section, must flow out directly into the return airways after being utilized once in the section. One of the largest producing underground collieries in South Africa, Initiated a project on controlled recirculation with the permission of the South African Government Mining Engineer. The project involves the recirculation of 65 m3/s of air inside a ventilation district which serves a total of six production areas. The aim of the project was to increase the airflow to the sections without altering the existing ventilation system. Tracer gas studies were carried out to determine the actual distribution of the recirculated air to the individual areas. The results showed that an effective 54,18 m3/s of the recirculated 65 m3/s reaches the sections. This gives an air utilization figure of 83,4 per cent. Dust surveys were also carried out as part of the project to determine the effect of the recirculation of the return air on airborne dust levels. The results showed that the dust levels remained constant in the main intake and return airways and that no hazardous situation was being created. The project proved to be successful and showed that controlled recirculation can be executed and used as a solution for the supply of air to sections without endangering any lives.

Jan 1, 1993

By David M. Mchaina, Michel Grenier, Stephen G. Hardcastle

An airborne dust survey was conducted at the Arthur W. White mine of Dickenson Mines Limited by CANMET/MRL and Dickenson Mines Limited Staff in April 1990 for the purpose of evaluating environmental conditions underground and in the surface mining plants. The survey was designed to measure respirable silica, total arsenic and lead concentrations at several workplaces. In addition, settled dust and rock samples were collected from workplaces and analysed for total arsenic content. More importantly, arsenic exposure data were needed to evaluate the impact of Ontario Regulation 176/86 as amended by Ontario Regulation 23/87. A total of 165 area and personal air filter samples were collected during the study. Of these, 85, 67 and 13 samples were for arsenic, silica and lead respectively. Sampling aid analyses were performed according to the Ontario Ministry of Labour Regulations. More than 90% of the workplaces sampled for respirable silica, total arsenic and lead were below the Ontario Ministry of Labour Regulations; and 10% of the workplaces sampled for arsenic shaved concentrations above the Threshold Limit value (TLV) proposed in the Ontario Regulation 176/86 as amended by Ontario Regulation 23/87. These results were used to identify occupations and/or workplaces where more sampling and control measures were required respirable silica, total arsenic and lead. This paper describes the results of the dust sampling program conducted at Dickenson Mines Limited.

Jan 1, 1991

By R. V. Ramani, R. Srikanth

A three-part study was conducted to relate the dust generation propensity of a coal sample, defined here as the dust generation rate (grams of dust generated per tonne of coal broken), to its characteristics, in order to rank coal seams according to their respirable dust generation potential. In this paper, the results of a single breakage study on a variety of coal samples encompassing all coal ranks, and samples from operating mines are discussed. Further, where data are available, the primary dust generation rates of coal samples collected from underground coal mines are compared with the in-mine dust generation rates. The results of this analysis are then used to apply the results of this study to longwall face ventilation design. Vitrinite reflectance, and level of organic metamorphism are highly correlated with primary respirable dust generation rates of bituminous coal samples. The dust generation rates in underground coal mines are an order of magnitude higher than the primary dust generation rates in the laboratory. Depending on the type of coal, production rates, and dust control procedures, the air quantity required for airborne dust control can vary significantly. The air quantities on some high production longwalls are approaching the limits beyond which it may not be possible to reduce ambient ARD concentrations to less than 2 mg/m3 by dilution ventilation alone. In these cases, the miner&apos;s exposure should be controlled through the use of personal protective de- vices and administrative practices.

Jan 1, 1997