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By Lit-Mian Chan, David H. Carlson, John H. Johnson

This paper presents an apparatus and procedures to implement a methodology for controlling ambient air quality in a confined working environment, such as an underground mine, an underground storage area, or a tunnel. The air quality control methodology is directed at limiting the quantities of exhaust pollutants emitted by diesel-powered vehicles into the confined space by identifying vehicles that are excessive polluters. The methodology is based on tailpipe and ambient air measurements in the confined space, and the ambient air threshold limit values (TLVs) for the various diesel exhaust pollutants. The methodology consists of two computational methods; a deterioration criteria computational method to identify excessive polluting vehicles, and an engine performance computational method to determine engine performance and to provide information needed to diagnose engine faults. The methodology is designed for implementation in conjunction with a preventive maintenance program. The first part of the paper describes the mine air and tailpipe emissions measurement apparatus and techniques used to obtain data. This is followed by sections discussing the deterioration criteria and the engine performance computational methods. A section discussing some common engine emissions-related faults is also presented. Lastly, a proposed procedure to implement the methodology including a possible hierarchical structure for mine personnel involved to implement the procedures is presented.

Jan 1, 1993

By D. J. Kennedy, W. G. Klinowski

Over the past few years the Cape Breton Coal Research Laboratory's staff designed, built, tested and proved the necessary hardware, software and methodology of tracer gas based surveying techniques applied in the field of mine ventilation. These methods are now used routinely in a variety of applications where traditional anemometric methods do not provide the required accuracies or cannot be effectively employed. Irregular or highly turbulent flows, leakages, geometrically complicated or highly obstructed airways are just a few examples where traditional anemometry can produce unacceptable errors in calculated ventilation parameters. Tracer gas based ventilation techniques have been used in many problematic situations where the standard ventilation methods are inadequate. One such problem, faced by many mine operators, is the emergency imposed by the ever present threat of a mine fire. An understanding of the propagation of smoke contaminants and the demonstrated integrity of appointed escape routes can save lives and property during a fire. That knowledge can be gained quickly and inexpensively by the application of tracer gas smoke simulation methods. The concept of controlled air recirculation has recently gained considerable attention in the mining industry. While mathematical models can be used to predict performance, the ultimate proof of a ventilation system's performance can best be provided by a tracer gas based simulation of contaminant levels. Fan performance tests and assessment of auxiliary ventilation systems are highly dependent on accurate definition of airflows; precise data can be easily obtained by tracer gas based volumetric surveys. This paper contains a brief description of the equipment and the methodology of tracer gas based ventilation techniques and presents typical examples of their use

Jan 1, 1991

By Keith G. Wallace, Gary K. Rogers

As a supplement to an analysis involving methodologies for the estimation of airflow resistance in shafts used for both ventilation and hoisting, a detailed shaft characterization survey was distributed worldwide. The survey provided detailed information which enabled verification of recommended velocities and established limitations on fill factors and relative velocities. This paper evaluates the information obtained for 37 shafts and presents a statistical evaluation of the results. Apart from airflow rates, conveyance rates, and physical characteristics, qualitative information regarding means of conveyance stability and velocity control techniques at unloading and loading points are also presented. Calculations of fill coefficient, free area velocity, and most importantly, relative velocity between the airflow and hoist, are conducted. These results are presented by frequency diagrams which illustrate the trends, as well as provide limitations for these parameters. The data illustrates that, commonly, the fill coefficient for two or more conveyances, does not exceed 30 %. A limit of 50% is suggested for a single conveyance shaft. A recommended free area velocity of 10 m/s (1,970 ft/min) for combined ventilation and hoisting shafts, is sup- ported by these results. Relative velocities of 30 m/s (5,905 ft/min) are most frequent and 50 m/s (9,840 ft/min) being a practical maximum.

Jan 1, 1987

By Glenn L. Krum

Inflation has received much attention due to its effect on capital budgeting, associated cost overruns, and declining real profits. This study focuses on the effects of inflation on the evaluation of a mining investment and the estimation of a mining project's revenues. The study indicates that the best method for estimating future returns is the fore- cast dollar scheme. In this scheme, the metal price was held constant, and the operating costs were "inflated" along a historical regression line. The conclusion was reached by comparing the "actual" performance of a 3000 tpd (tonnes per day) lead mine model with 'its estimated performance during four time periods (1950-1960, 1955-1965, 1960-1970, 1965-1975). The individual data files for each time period and estimating method (6 files by 4 time periods) were pro- cessed by a suite of cash flow computational and investment analysis sub- routines. The analysis presumed that the mine was part of a large corporation which could utilize the expensed, development and exploration costs and any investment tax credits, in the year that they were incurred.

Jan 1, 1979

By N. S. Tanious

This paper summarizes results from an investigation into possibly the largest coal pillar failure in the USA. The newly opened coal mine worked an 3.35 m (11 ft) seam under overburden depth that ranged from 91 to 671m (300 to 2200 ft) . The mine main entries, and the enclosed pillars, experienced a massive slow squeeze. The squeeze could not be controlled and the mains were lost. A new set of mains were driven. Entry convergence (closure) measurements were carried out behind the advancing face to monitor stability. Pillar stresses were also measured under four different depths of overburden: 229.433, 472.579 m (750,1420,1550, and 1900 ft). The strength of pillars in the new mains was calculated from the loads that triggered the failure in the old mains, using three pillar strength formulas. The stress measurements showed that the new pillars supported more load than their predicted strength, indicating that current strength formulas are inadequate under deep conditions.

Jan 1, 1992

By Gordon I. McPhail, John D. Nelson

Tailings management represents a major portion of the cost associated with extraction of gold. For each gram of gold extracted, 150 to 200 kg of waste material is produced. Because of environmental concerns and unwillingness of society to accept environmental damage caused by poor waste management practices it has become essential to follow responsible and safe practices in tailings management. This paper presents general aspects of tailings management and discusses different techniques utilized. Characteristics of tailings and the effects that these have on stability and environmental aspects are discussed. The paper also discusses the effect of mine back-filling practices on the surface disposal of the remaining tailings fraction.

Jan 1, 1987

By E. Grygiel, J. Haynes, T. McNider

Jim Walter Resources Blue Creek No. 3 Mine was opened in one of the most gassy coal beds in the United States. Although face ventilation requirements exceeded 14,000 cfm (6 .6m3/s) air, continuous miner sections experienced an unacceptable frequency of frictional ignitions. Modifications offered primarily by the U. S. Bureau of Mines such as diffuser fans, water spray fans, and slow speed cutting motors were used with little success. However, laboratory tests conducted at the U. S. Bureau of Mines indicated that an increase in bit attack angle from 50° to 55°-57° significantly reduced the chances of the bit causing a frictional ignition. An experimental miner drum was built using this concept coupled with a new bit designed by the Bureau and manufactured by Hughes Tool Company that better protected the bit steel shank with a carbide cap. It was installed on a continuous miner and placed in an area of the mine prone to ignitions. 50,000 tons (45,500 metric tons) of coal were cut without a frictional ignition. When the miner was withdrawn for rebuild and a machine with an unmodified cutting drum placed in service, two ignitions occurred before 10,000 tons (9,100 metric tons) were mined. Other machines have been rebuilt and are in service, and to date none have been known to cause an ignition.

Jan 1, 1987

By James L. Hendrix, R. Y. Wan, David W. Kappes, Jinrong Zhang, M. C. Fuerstenau, Terence E. Albert

A sulfidic flotation tailings ore, containing 1.14 gpt Au and 242.53 gpt Ag, was treated by low temperature chlorination roasting followed by cyanide or chloride leaching. Eighty per cent of Ag was recovered by cyanide leach when the ore was roasted at 350°C with 50 kg/ton calcium chloride. About seventy per cent of Au was made cyanide amenable by chlorination roasting at 400°C. A better Ag recovery, ninety per cent or over, was achieved by chloride (NaCl+HCl) leach. However, Au recovery was very poor by chloride leach. Ferric chloride, calcium chloride, and cupric chloride were compared as chlorinating agents for their effect on Au and Ag recovery. The study found that low temperature chlorination roasting is very effective for recovering Ag associated with stibnite and stannite. The best chlorinating agent for the test ore was found to be calcium chloride. Parallel roasting-leaching tests indicated that chlorination roasting was far superior over oxidation roasting for both gold and silver recovery.

Jan 1, 1993

By Roe-Hoan Yoon

Froth flotation is widely used for separating particulate materials from one another in aqueous media. The basis of this important separation process is to control the hydrophobicity of particles. However, it is difficult to predict the kinetics of flotation based on contact angle (?), which is a thermodynamic property. A solution to this difficulty would be to develop a relationship between ? and the gradient of the hydrophobic forces across the solid-liquid and bubble-liquid interfaces. Such information can be obtained using the surface force apparatus (SFA), the atomic force microscope (AFM), and the thin film balance (TFB). The present communication reviews the results of the measurements conducted using these methods, and offers a methodology for deriving a rate equation for bubble-particle interactions

Jan 1, 1999

By D. Altizer, E. Thompson, K. F. Unrug

Because of frequent sudden changes in the geologic composition of strata, the extrapolation of rock properties obtained from core samples to the surrounding areas can cause problems. To address this issue, a method of rapid strength testing in situ using a borehole penetrometer is being developed. This method, as opposed to conventional laboratory testing, does not require rock samples to be retrieved and handled/machined before testing. Rock strengths are determined di¬rectly on the drill-hole wall. The latest development is a borehole penetrometer that requires only a 38.1-mm- (1.5-in.-) diam hole. The small diameter of the penetrometer body allows for the drilling of test holes with production mine equipment such as a roof bolter. The new penetrometer allows for the possibility of a broad application in coal mines, as well as in hard rock mines and tunneling. The principles of the apparatus are described and are illustrated with examples of its applications.

Jan 1, 2002

In the hierarchy of performing mine planning tasks, production scheduling is naturally at the bottom. Yet good production scheduling is probably the most demanding and difficult task to achieve for various reasons. Being the last task in the mine planning hierarchy, a proper production schedule must not only conform to both the long-range and the short- range mine plans but also satisfy many practical details that are unique to day-to-day operations. For example, the averages which were good enough for both long-range and short- range mine planning are no longer good enough for production scheduling. Instead, the variations become the overriding concern. The answer must also be obtained quickly and on time, thus adding another dimension to the overall problem. Because of these considerations, many production scheduling problems have been begging for solution during the past decade. Many attempts were made to solve the production scheduling problems in the past using computers and the available operations research (OR) techniques, particularly among academic groups. However, it is probably true that, compared with the current full-time computer usage in long-range and short-range mine planning, very little computer usage is being made in production scheduling to date.

Jan 1, 1979

By Allan D. Fernie

Many long conveyors, 2 - 20 km plus, have been installed over the past 10 years. Conveyor belt life, depending on the conveyor length and material handled, will generally range from 10 - 15 years. To replace long conveyors splicing one or two rolls into a conveyor run on an intermittent basis can be prolonged in an operating system involving considerable downtime and scheduling problems. This paper presents some of the methods used to- date and highlights forward planning for such an event. Special belt handling equipment required and the execution of a belt change operation are described in detail. Wright Engineers Limited have worked in collaboration with Canada Conveyor to design and implement the methods described herein.

Jan 1, 1993

By Arthur B. Steiker

Digital simulation was used to model a proposed underground' train system. The trains are to haul ore from numerous loading points beneath the production area of the mine to a central underground dump location, and then return to the mine. The purpose of the simulation was to aid mine engineers in studying various alternatives and configurations regarding track layout, crusher (dump point) specifications, dispatch procedures, fleet size, and train length, among others. The simulation' model can also be used to study the same aspects of existing haulage systems. To accommodate a wide and initially unknown range of system designs, a modular model structure was developed with major components devoted to track routing, train movement, loading process, dumping process, and dispatch. Key statistics tabulated were number of trains dumped during a simulated week, queueing delays in the mine and at the crusher, crusher utilization, cycle time, and percent of time for each: activity (loading, moving, dumping, etc.). The simulation results were instrumental in identifying a train system design which would reduce queueing delays and meet production goals with a minimum of trains and track mileage.

Jan 1, 1982

By Kumara S. Rachamalla

Mineral activity in Ontario represents an annual production in excess of $4 billion. The Ontario government encourages the mining industry to undertake mineral development through grant programs and incentives offered by mineral resource taxation. Computers are playing an increasingly important role in improving productivity in the administration of incentive programs and the Mining Tax Act in Ontario. This has meant speedier processing of grant applications and tax returns which is resulting in a streamlined approach to incentives and taxation in Ontario. The use of computers has resulted in significant contributions to key areas of concern such as assessment of mining tax returns, analysis of the changes, if any, to the Mining Tax Act and modeling of the Ontario Mineral Exploration Program (OMEP). Implementation of state-of-the-art technology such as Local Area Networks (LAN's), fourth generation languages and integrated micro-mainframe information processing has resulted in improved productivity as well as lower costs. As a result, the respective services provided to the mineral industry by these two programs are now delivered in an efficient and cost-effective manner utilizing the latest available computer technology.

Jan 1, 1986

By S. W. Kan, M. G. Kakarkis, J. Zelanco

Grouting has been used in underground mining for more than 20 years. Chemical grouting is often used as a remedial measure when the implemented ground-control program is unable to completely prevent structural failures or when there is a need for preventing a structural member from unraveling. The utilization of polyurethane grout is restricted by its limited range of physical and mechanical properties. To overcome some of the drawbacks of polyurethane, research is being conducted on a newly developed polyester based grout. The polyester resin, identified by Sandvik as Strata Grip, provides a number of features, including variable gel times and a much-reduced chemical hazard. Equally important are the mechanical properties of the product. The strength and deformability of any chemical grout must be compatible with the intended purpose of grouting and the expected deformation of the rock that is to be grouted The assessment of the mechanical properties of polyester grout is the focus of this work. Field experiences and laboratory research defined the properties of an effective grouting material. Experimental results indicate that the polyester grout meets or exceeds the recommended properties for many injection applications. Furthermore, the results suggest that the ability to adjust mechanical properties via resin formulation has the potential to expand the applicability of chemical grouting in ground control.

Jan 1, 1999

By M. R. Peterson, C. R. Ferguson, T. H. Jeffers

The ability of microorganisms such as yeast, bacteria, and various aquatic flora to sorb metals from dilute aqueous solutions is well documented. Although microorganisms have significant potential in decontaminating waste waters, techniques and equipment suitable for bioassisted decontamination are limited. The Bureau of Mines has investigated the use of microorganisms immobilized in porous polysulfone beads for extracting toxic and heavy metals from dilute waste streams. The minus 8- plus 12-mesh beads were fabricated from high-density poly- sulfone dissolved in dimethylformamide (DMF). Dried, thermally killed yeast, algae, duckweed, xanthan gum, and alginates were blended into the polysulfone-DMF, and spherical beads were formed by injecting the mixture into water. Microscopic analysis revealed microorganisms immobilized within the bead pores. The beads had excellent handling characteristics and were tested in stirred reactors, fixed bed columns, and fluidized bed columns for their ability to remove metal contaminants from several waste waters. The effluents resulting from these waste waters met or exceeded the National Drinking Water Standards for cadmium, copper, manganese, and zinc. Other heavy metal contaminants readily sorbed by the beads included arsenic and mercury. Elution of metal values from the beads was accomplished using dilute nitric acid or sodium carbonate.

Jan 1, 1989

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

A mining CEO's willingness to participate in risky investment opportunities significantly affects a company's strategic-investment decisions. Decision-analysis techniques provide a mechanism for measuring a CEO'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 S. S. Peng, Luo. Y.

In a shearer longwall mining operation, the longwall hits are responsible for breaking into and chipping the broken coal blocks away from the coal face. However, underground observations found that the bits being used were working under various degrees of wear. This wear can be reduced by using better-designed longwall bits and by properly selecting shearer operating parameters. A computer program was developed to simulate the performance of the longwall bits. The information required by the program are the shape of the bit head, the installation of the bits on the drum and the operation parameters. Through the simulations, the main factors affecting the bit-wearing process are identified. Suggestions are also made for improving the design of the longwall bits.

Jan 1, 1998

By B. Cavender

Investments in new technology are often intended to improve the production or cost performance of existing operations. The economics used to justify these projects can be flawed, however, if they do not adequately consider the potential benefits of the alternative: the fully optimized use of the facility's present equipment and personnel. While new technology can be effective, dramatic improvements in production performance can also be achieved through the rigorous application of standard industrial engineering and operations management practices. An intermediate approach may also be effective: many basic improvements in the mine or plant necessary to support new technology will be equally effective when implemented for the facility's present operators. Firms that optimize their present operations are able to save the capital and avoid the risk associated with new technology. These firms will also be able to capitalize more quickly on new technology when it is implemented.

Jan 1, 2000

The development of economical and effective treatment processes for solid and aqueous waste is a critical issue facing the mining industry today. Cyanide, nitrates and acid rock drainage are environmentally sensitive effluents that require treatment or containment for acceptable disposal. In situ biotreatment processes are an emerging technology (Thayer) for cyanide oxidation, denitrification, sulfide mineral alteration and metal re- mineralization. Biological cyanide oxidation is competitive with chemical treatment processes (peroxide, alkaline chlorination) for process solutions, spent ore and tailings detoxification. Microbial denitrification treats mine waste contaminated with nitrates from blasting, processing or nitrification of the host rock. Bio-alteration of sulfide minerals and metal re-mineralization may present the most cost-effective and environmentally acceptable method of dealing with sulfide tailings and leachate solutions. Field test programs for cyanide bio-degradation and denitrification of spent ore and process solutions were designed and run at two mines. Although the treatment bacteria and the application processes are similar, each waste presented site-specific problems for adapting the biotreatment processes. Some of the site problems include climate, ore geochemistxy, field bacteria production, waste microbiology and application engineering. This paper compares treatment design and results for cyanide oxidation and denitrification in heap detox treatments.

Jan 1, 1992