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By Lynn B. Hales, Randy A. Ynchausti

Object-oriented technologies have been developed to more closely model the way we think about the world and our natural approach to solving problems. Higher levels of abstraction, generalization and classification are benefits of an object-oriented approach. Object-oriented programming, design, and expert systems are part of this technology which is shaping the future of real-time supervisory control. Goals of real-time supervisory control systems include: minimizing variations in process operations, improving efficiency, maximizing production, and implementing procedures for starting and stopping the process. Incorporating object-oriented technology in design, development and implementation of real-time supervisory control systems provides new opportunities for these tasks. This paper discusses some of the opportunities and challenges of implementing real- time supervisory control using an object-oriented expert system for a rougher flotation circuit

Jan 1, 1993

By R. Houot, C. Leschevin, G. Gillet

In mineral processing, conventional magnetic separators are equipped with traditional magnetic circuits (magnetic iron yoke with copper coils or iron-clad solenoid) that develop magnetic fields of less than 2 T'. For minerals of low magnetic susceptibility, use of these circuits has many disadvantages. Only a separator with a superconducting magnet can contribute to solving the problems and produce a high magnetic field. This paper presents and describes a magnetic separator having a superconducting magnet with integrated closed circuit for helium liquefaction. The system generator and maintenance are simplified by extensive automation realized by a versatile program- mable autocontrol unit. A comparative study if the results on concentration and purification of different raw materials with the new and with conventional separators is described.

Jan 1, 1987

By D. W. Dew, D. M. Miller, P. C. van Aswegen

The bacterial oxidation (BIOX®) process for pre-treatment of refractory ores for gold recovery is marketed by BIOMIN Technologies S.A. The process was originally developed by GENMIN who are still providing testwork, design and commissioning assistance to BIOMIN. This process offers an alternative to the more conventional roasting or pressure oxidation techniques with the following advantages: • Greatly reduced capital costs for small to medium size plants. • A relatively flexible and easily controllable process requiring relatively unskilled labour for operation. • Improved gold recovery. • A process that is environmentally friendly. The principal disadvantage of bacterial oxidation is the relatively slow kinetics compared to pressure oxidation and roasting, a plant residence time of 4 to 5 days typically being required to obtain complete liberation of gold from refractory sulphide minerals. Bacterial activity is also slow to recover from disruptions such as air supply failure or contamination by toxic species such as cyanide. Optimum plant performance depends on judicious management and sound training of operators.

Jan 1, 1993

The world's largest hydraulic excavator was recently introduced at Syncrude's North Mine at Fort McMurray, Alberta, in Canada. O&K's 826t (910-st) behemoth RH400, with a 42-m3 (55-cu yd) bucket, is capable of loading 72.5 t (80 st) in one pass. Syncrude's Alberta operation is the nation's largest single source of crude oil. It is also the world's largest producer of oil from oil sands. Syncrude produces 205,000 bbl/day, expects to increase production to 225,000 bbl/day by 1999 and to 320,000 bbl/day by 2005. That translates to 73.5 million bbl of Syncrude Sweet Blend (SSB) produced in 1996, 82 million bbl in 1999 and 114 million bbl in 2005. The North Mine is a new development that will replace the current East Mine, to be depleted of oil sand by the end of 1999. The North Mine will feature hydrotransport, a new and unique method of transporting oil sand from the pit to the process plant. Oil sand from the truck-and-shovel operation will be processed through a double-roll crusher and placed in a cyclofeeder where it mixes with hot water. The material is then screened and transported by pipeline to the extraction plant. Hydrotransport will replace conventional conveyor transport for moving raw product from the pit. Mine development will also use two 290-t (320-st) haul trucks to compliment the fleet of existing 218-t (240-st) trucks.

Jan 1, 1998

By J. L. Post, L. Borer

Small seams of fibrous tremolite and actinolite commonly occur in many California counties. A number of larger seams of this fibrous material were mined from 1882 until about 1955. The fibers from these mines were used for making acid filters, battery cases and fire-resistant paint. With increasing population, new residential areas are being developed in the foothill regions, leading to increased contact with seams of fibrous amphiboles. These forms of asbestos can be particularly dangerous to human health. Thus, it is necessary to determine the locations of these mines and adjacent veins and to identify the specific amphibole minerals present.

Jan 1, 2003

By W. V. Bluck

Higher coal quality is being recognized in potentially lowering the cost of power as measured at the bus bar. Assessment of potential coal supplies for most any given power plant is now going beyond buying at the lowest delivered fuel cost and is now taking into consideration other factors such as handling, storage, pulverization cost, boiler fouling, post combustion cleanup, and waste disposal costs. New measurements of quality are being considered now by those producing and those consuming the fuel by assessing numerous variables in the total fuel cycle to achieve the lowest possible power costs.

Jan 1, 1983

By Igor V. Nazarov

INTRODUCTION Tens of deposits in' coal basins of Western and Eastern Siberia are being open-mined with the technology of overburden rehandling into the mined out space of pits by excavators - draglines. This technology is preferred due to the high productive Russian equipment, comparatively low cost, and relatively small Influence exerted on the environment. The basic tendency of the last decades is the aspiration for enlarging the sphere of the' technology application for development of gentle and steeply dipping seams with the use of blast destruction of overburden and with combined winning of loose alluviums and rock partings. Complex technological schemes with multiple rehandling are widely used. In addition to it, stripping workings, intermediate storage of mineral resources, placing of transport dumps, and engineering construction can be realized with the use of draglines. More than ten of dragline faces are simultaneously exploited in some pits, and the rehandling coefficient ranks from 0.1 to 8. Here, conditions of winning and placing (position of a face and existing dump) are varying in space and time; this leads to the necessity of reconsidering the order for conduction of works (schemes) within the current designing. By now, in order to this, it is required to realize complex engineering calculations by graph-analytical methods and definite experience. The need is available for automatization of this process by creation of the corresponding software. The software is to: • Orient on the active pits and use information on the existing geology, equipment, and situation in mine. • Calculate the existing schemes more operative and on a higher qualitative level to model their development in a pit space with parameter optimization. • Predict situations demanding to change the existing technology for mining operations and recommend optimal technological schemes. METHODOLOGICAL FOUNDATIONS FOR MODELING The problem is not new, it has more than fifty year-old history of creating mathematical models algorithms, and programs in Russia, Ukraine, USA, Canada. Australia and other countries with the developed mining branch. Conventionally, all population of programs can be divided into three groups depending on goal and interval of prediction: • Long-term programs used in designing and intended for substantiation of the nine capacity, selection of mining system, establishment of limits for applying the technology of overburden rehandling. Mid-term programs used in current planning for calculation of technological schemes and certificates of face in active mines.INTRODUCTION Tens of deposits in' coal basins of Western and Eastern Siberia are being open-mined with the technology of overburden rehandling into the mined out space of pits by excavators - draglines. This technology is preferred due to the high productive Russian equipment, comparatively low cost, and relatively small Influence exerted on the environment. The basic tendency of the last decades is the aspiration for enlarging the sphere of the' technology application for development of gentle and steeply dipping seams with the use of blast destruction of overburden and with combined winning of loose alluviums and rock partings. Complex technological schemes with multiple rehandling are widely used. In addition to it, stripping workings, intermediate storage of mineral resources, placing of transport dumps, and engineering construction can be realized with the use of draglines. More than ten of dragline faces are simultaneously exploited in some pits, and the rehandling coefficient ranks from 0.1 to 8. Here, conditions of winning and placing (position of a face and existing dump) are varying in space and time; this leads to the necessity of reconsidering the order for conduction of works (schemes) within the current designing. By now, in order to this, it is required to realize complex engineering calculations by graph-analytical methods and definite experience. The need is available for automatization of this process by creation of the corresponding software. The software is to: • Orient on the active pits and use information on the existing geology, equipment, and situation in mine. • Calculate the existing schemes more operative and on a higher qualitative level to model their development in a pit space with parameter optimization. • Predict situations demanding to change the existing technology for mining operations and recommend optimal technological schemes. METHODOLOGICAL FOUNDATIONS FOR MODELING The problem is not new, it has more than fifty year-old history of creating mathematical models algorithms, and programs in Russia, Ukraine, USA, Canada. Australia and other countries with the developed mining branch. Conventionally, all population of programs can be divided into three groups depending on goal and interval of prediction: • Long-term programs used in designing and intended for substantiation of the nine capacity, selection of mining system, establishment of limits for applying the technology of overburden rehandling. • Mid-term programs used in current planning for calculation of technological schemes and certificates of face in active mines.

Jan 1, 2002

By C. Flores, L. G. Twidwell, T. S. Jordan

It is well known that manguniferous silver ores containing manganese intimate) associated with silver are not amenable to conventional extraction methods. The segregation process has been applied primarily to the recovery of copper from oxidized and oxide-sulfide ores. A new alternative process, consisting of segregation roasting followed by flotation to recover the silver from refractory manganiferous silver ores, was studied using a 23-factorial experimental design. Laboratory investigations were conducted on a manganiferous silver ore analyzing 0.02% copper, 0.09% lead, 0.33% zinc, 12.55% manganese and 187 g/t silver. The investigation was designed to study the effects of the addition of salts, coke and copper (11) oxide on silver recovery. The results indicated that 79.3% of the silver can be recovered in the absence of copper oxide and 88.4% of the silver can be recovered with a copper oxide content of 1.5% at 750°C, 2% salt (NaCI). 1 % coke and 30 min of roasting. It was concluded that the addition of copper oxide improves silver recovery.

Jan 1, 1996

By -Ing. Alexander Dohmen, -Ing. Gunter Hagen

In order to improve the thermal environment in deep coal mines, two principles can be applied: firstly, the reduction of heat flow into the air stream, and secondly, cooling of the air current. First of all one should try to minimize the heat-flow rate into the air stream underground by the mining method itself. German coal mines prefer the caving system of advance longwall mining simultaneously on several levels with ascensional ventilation. The effects of descensional ventilation and different face ventilation layouts on the thermal environment are discussed, besides the effects of pneumatic and hydraulic stowing. Application of all mentioned possibilities together instead of today's common mining method would reduce the Basis Effective Temperature considerably. In the future, hydraulic haulage of the raw coal underground substituting belt conveying may be a mean to improve the thermal environment further on. If the working depth of a coal mine exceeds about 1 000 m, cooling of the air stream under-ground will be necessary in addition to the above- mentioned measures. Generally, in German coal mines different types of indirect-contact air coolers located nearby the face are used. Besides such so-called cooling coils, large-capacity spray coolers are used because they work more efficiently if a great cooling duty is demanded. Common designs of both air cooler types and their possible utilizations are demonstrated. Deep coal mines in the Federal Republic of Germany need up to 30 MW of total cooling capacity. Mostly, the needed chilled water is cooled by large-capacity refrigeration plants placed on surface, underground or in combination of the above locations nearby the shaft. Due to the increasing underground cooling demand, the distribution of the chilled water and the control of the air coolers become more important. The conception of a control system is discussed, which is based on the control of the single air coolers. All air coolers of a mine are controlled so as to optimize the supply water-flow rate with regard to the demanded cooling duty of the coolers. On the next upper level of the control system the whole chilled water network and finally the refrigeration plant is regulated. Present research work deals with the use of ice for cooling mines. There are some unsolved problems in this new cooling concept. Some aspects of making, transporting and storing ice are described. The use of ice may probably reduce the cooling costs of German collieries, which are at present approximately 4 DM per ton of saleable coal.

Jan 1, 1989

By Peter I. Brooker

The turning bands method for the simulation of spatially correlated data in two or three dimensions requires that the relation- ship between the covariance obeyed by the realizations first generated on lines, and the covariance of the two or three dimensional process must be solved. In three dimensions the solution is immediate, but in two dimensions the integral equation relating the covariances of the one and two dimensional processes is more complex. This is solved in this paper and is applied to the most common model used in ore deposit description, the spherical covariance.

Jan 1, 1984

By A. M. Raichur, K. Keltner, M. Misra

The removal of oxyanions of arsenic present in mine process water and drinking water to a regulatory level (i.e. below 50 ppb) is a challenging problem. Conventional water treatment methods presently used for controlling arsenic have several drawbacks and limited success. A new adsorbent (LS™) developed at the University of Nevada, Reno, has strong specificity for both arsenate and arsenite species present in process waters. The adsorbent in very selective to oxyanions of arsenic and competition of other indifferent ions is minimum. Water samples from different sources were tested and arsenic was successfully removed to below 50 ppb. This paper describes both batch and packed column tests conducted in the laboratory as well as at the plant sites using LS™.

Jan 1, 1997

By Chun K. Ip, Simon T. Johnson, Robert J. Fowell

Laboratory conducted cutting tests at traverse speeds up to 1 m/s have been undertaken with high pressure water jets assisting the cutting action of drag tools. Four sandstones and one limestone have been investigated, which represents a wide range of compressive strength. Variables investigated include water jet pressure, nozzle diameter, depth of cut, traverse speed, jet position, and tool bluntness. The test programme has allowed a model to be developed which describes the action of water jet assistance for three conditions dependent on the ability of the jet to penetrate the rock: where no significant penetration occurs, where penetration is greater than 50% of the tool depth, and an optimum condition around 30% of tool depth.

Jan 1, 1986

By J. Loeb, R. Ramanathan, P. Cameron

All mining operations, including iron ore, maintain a focus of continuous improvement and asset optimisation in their operations. As all the operations in the Mine-to-Mill value chain are inter-dependent, available technologies that address efficiencies across the value chain are once again in the spotlight as companies are driven to improve productivity and maximise mine site profits to increase return on capital invested. Core to continuous improvement is the need to understand the baseline and the impact of changes to the process. In this paper, we discuss some of the key attributes in the mine to mill process, including their influence on productivity and cost, the need for direct measurement and areas where they should be applied. Many initiatives can be considered to improve mine to mill processes. Mining operations are planned and executed based on designs and models to achieve the operation’s objectives. However, there are many variables in the different parts of the value chain, such as blasting, material handling, crushing and screening. Measurement of the key attributes establishes the baseline for Mine to Mill (or Pit to Plant) performance which is necessary to understand the impact of any proposed improvements to the process design and execution and to monitor the outcomes on an ongoing basis to sustain the improvements that have been implemented. We have focused this paper on two types of measurement – blast movement and particle size of materials through the mine to mill process. Several innovative technologies are already available to measure these attributes and assist operations improve productivity and mine site profits.

Mar 2, 2022

By M. E. Lewellyn

A lower moisture content for a clean coal product means increased Btu content, or increased yields at the same Btu content, and lower operating costs. The conventional surfactant-based dewatering aids effeciently lower the moisture content but often the presence of residual surfactant in the filtrate and recycle water causes problems downstream. ACCOAL-DRI 1000, a surfactant-based dewatering aid, was developed to solve this problem by minimizing the downstream effects while efficiently lowering the moisture content. The theory of the use of surfactants in filtration will be discussed as well as the development and field evaluation of this new product.

Jan 1, 1988

By Robert S. Setren, Jeffrey L. Ambs

The disposable diesel exhaust filter (DDEF) system developed by the U.S. Bureau of Mines and Industry cooperators for heavy-duty permissible, diesel-powered haulage vehicles, effectively reduces in-mine diesel particulate matter concentrations up to 95%. However, there are concerns about the hazards that exist when the filter is used in situations for which it was not designed. This work investigates the exhaust gas temperature limits to which the filter elements can be exposed without posing a safety or health hazard, such as 6re or off-gassing toxic compounds. A filter approved by the Mine Safety and Health administration and after-market filters were evaluated under varying engine exhaust conditions to determine if after-market filters pose an unacceptable hazard when used in a DDEF system. Filters were laboratory tested at engine exhaust temperatures ranging from 77°C to 290°C. Of the seven filter types tested, six appeared suitable for use on water scrubber-based cooling systems and two appeared suitable for use on dry heat exchanger type exhaust cooling systems with exhaust temperatures up to 150°C. Any filter elements used as exhaust filters on permissible diesel machines must be approved by MSHA for that application. Mine operators who wish to use an after-market filter element should request an MSHA field modification. MSHA will work with the mine and filter manufacturer to ensure its use in this exhaust system application does not pose a health or safety hazard.

Jan 1, 1995

By G. L. Schroeder, C. H. Summers, D. B. Lindsay

INTRODUCTION The requirement that is placed on owners and operators of underground mines to protect workers against the health hazard of inhaling radioactive materials which are short-lived decay products of 222Rn can be satisfied by applying a considerable variety of what we may call "engineering" solutions as well as a number of "administrative" remedies to the problem. The most obvious of the "engineering" approaches has always been that of forced ventilation, in which relatively clean (i.e., radon-free) air from aboveground is drawn or pushed through the mine workings by a system of fans and ducts. This relatively clean air, in sweeping through the drifts, stopes and haulageways, dilutes the radon and radon-daughter concentrations in the air of the mine, and performs the added beneficial function of removing the daughter-mixture quickly enought to limit grow-in of the longer-lived nuclides in the group that make up the "toxic trio" on which the Working Level (IM) unit is based. Effective as the dilution-ventilation method is for control of WL in most underground mining situations, however, the increasing strictness of control measures that have been imposed on the mining industry over the last two decades have demanded measures of even greater effectiveness. In times of poor markets for yellow-cake and other products of the mines, mine operators are pressed to reduce operating costs, and the installation of additional primary ventilation capacity can be a severe burden on a mine that is already laboring under an unfavorable earning power. When traditional dilution-ventilation systems alone cannot meet the requirement for WI, control, radiation safety engineers and ventilation engineers begin to look at alternatives and auxiliary methods. Since the radon which produces the toxic daughter products originates in the rock of the mine walls, and since, in most United States mines, that rock is a porous sandstone through which air can move under the effect of atmospheric pressure gradients, and through which radon can diffuse relatively freely, one way to help control the growth of WL would be to hinder the escape of radon from that reservior of porous rock. An appealing; method for hindering that natural flux of radon-polluted air from the walls of the mine has long been apparent; namely, to apply a low-permeability coating over the surface of the rock, thus sealing the radon in place and, in theory at least, preventing its escape into the mine air. Our 1970 report to the U.S. Federal Radiation Council on the subject of cost impacts of proposed changes in the occupational standards for exposure of underground uranium miners to airborne radon daughters noted the possibility of using polymeric wall sealants as a means of controlling radon-pollution of mine air. Since that time a number of reports have appeared in the technical literature advocating this technique for restraining the escape of radon from building materials, mill tailings, and other materials containing 226Ra, in addition to the surfaces of underground mine workings. During this period, some controversy has occurred over the question of the probable effectiveness of wall sealants in limiting the escape of radon from the rock. Our 1970 report speculated that flaws (cracks and "pinholes") in the coating might be all but unavoidable in practice, and that even a conservative estimate of the frequency of such flaws would lead to a prediction of ineffectiveness. Hammon et al, in a laboratory evaluation of radon sealants conducted by Lawrence Livermore Laboratory of the University of California in 1975 on behalf of U.S. Bureau of Mines, concluded that a wide variety of polymeric coatings would provide "nearly 100% effectiveness" in restrain¬ing escape of radon from mine wall surfaces if applied in "thicknesses between 5 and 10 mil" (125-250 [y]pm). John Franklin and co-workers at the U.S. Bureau of Mines laboratories in Spokane, Washington, have carried the experiments with polymeric sealants through additional laboratory tests and into actual mine environments, reporting that selected sealants could provide attenuation of radon flux by a factor of four (75-80% reduction). Robert Bates and John Edwards of USBM developed a computer-assisted mathematical/physical model that predicts a relatively small effect of flaws in a low-permeability coating on the radon flux from a sandstone-type matrix. FIELD TEST Since all actual experimental work with wall sealants showed some beneficial effect on radon attenuation (even if not as exciting as the "nearly 100%" predicted by Hammon), USBM was encouraged to extend its evaluation to an actual operating uranium mine, and awarded a contract for that work to Arthur D. Little, Inc. in September 1979. We were fortunate in obtaining the voluntary cooperation of Atlas Minerals Division of Atlas Corp., who operate a mill and several underground mines in and around Moab, Utah. Atlas made available for our use a small T-shaped drift in their Pandora Mine in LaSal, Utah, and provided space for instrumentation and recordkeeping by our field crew in a surface building near the mine entry. Atlas also provided electricity and water to the test site, together with assistance in establishing necessary ventilation, removing rubble from the site, conducting periodic WL surveys and furnishing auxiliary man-power for the heavy hard work of coating the walls with gunite prior to application of the polymeric sealant. The generous coopera-

Jan 1, 1981

By E. A. Metz

Silicon dioxide, silica, is the most common oxide in the earth' s crust. The health effects of silicon dioxide dust have been known since Biblical times. Agricola's book, published in the mid 1500's on occupational medicine, described a lung disease that afflicted miners. He observed a disease in miners that caused shortness of breath, coughing and wasting. Add fever, chest pains and fatigue and we have the current symptom complex of silicosis. As we approached the 21stcentury, the Labor Department began an aggressive campaign to combat silicosis-a preventable disease. Unfortunately, many publications do not clearly differentiate the polymorphs of silica known to mineralogists. Crystalline silica, i.e., alpha quartz, tridymite and cristobalite need to be considered differently from the amorphous forms of silica. Freshly fractured surfaces of the silica and host specific responses will be examined. Recent research focuses on the biologic interactions of free radicals generated by mineral particles. This results in cell injury and DNA damage, in turn leading to fibrogenesis and possibly carcinogenesis. In addition to particle-cell interactions, emphasis is given to lung defense mechanisms.

Jan 1, 1998

By V. F. Hollister

The Ivanhoe district, Elko Co., Nevada, is located in the northern part of the Carlin trend of epithermal gold-deposits, but it differs from most mines in the belt in that Ivanhoe epithermal gold ores are found in 14 m.y. old Tertiary volcanic rocks as well as in the better known Paleozoic sediments. Within the Ivanhoe district U.S. Steel (USX Corp.) discovered and partly developed an epithermal gold deposit largely hosted by Tertiary rocks that, with a 167-hole program, was found to contain an open ended probable reserve of 4.0 million tons of heap leachable open pit oxide ore averaging .042 opt Au. An additional 4.0 m.t. of open pit sulfide ore averaging .048 opt Au were also developed. The U.S. Steel orebody was a blind discovery in that it just barely outcropped, and it was found by drilling through a premineral but barren cover of altered Tertiary volcanic rocks.

Jan 1, 1988

By Edward D. Elkins

CalMat Co. is one of the largest producers of construction aggregates in the United States. The CalMat Reliance plant is located in Irwindale, California, and is situated on an alluvial fan formed by the San Gabriel River. The fan deposits are of Quaternary age and were derived from granitic and metamorphic bedrock exposed in the San Gabriel Mountains to the north. The sediments are poorly sorted and range in size from large boulders to clay size particles. The coarse material is hard and durable and consists of quartz diorite, granodiorite, granitic gneiss, schist and minor amounts of volcanic rock. The matrix is comprised of silty sand with varying amounts of clay. Thin silt and clay lenses occur sporadically throughout the deposit. The clay content of the matrix and the degree of weathering of the coarse material increases with depth. Based on seismic data, the alluvial fan varies from 200 to 400 feet thick and overlies crystalline bedrock. The Reliance plant was constructed in 1971 and 1972. It has a nominal capacity of 1200 to 1400 tons per hour, and typically produces more than three million tons of aggregate products per year. Alluvial fan sediments are mined from a gravel pit situated adjacent to the plant. The material is fed through a mobile, 48- by 60-inch, in-pit jaw crusher, then transported by conveyor to the main plant to be processed. The plant is modern and highly efficient. It has a typical wet and dry circuit and is capable of producing a wide range of aggregate products. To extend the life of the plant, a 9,000 foot conveyor system is being constructed to connect it to a granite quarry operated by Azusa Rock Inc. The quarry is located north of Irwindale, and is 50 percent owned by CalMat Co. The conveyor will be used to export crushed rock from the quarry to Reliance. The existing plant will be modified to process the crushed rock.

Jan 1, 1995

By D. M. Stephens

Feeder-Breakers were an unknown but much needed piece of machinery when U. S. underground coal mines started converting to more efficient belt haulage of the R.O.M. coal as compared to conventional methods that the 1950's offered. These simple electromechanical machines offered efficiencies in three areas: (1) they contained a surge hopper that allowed a "load' of coal to be dumped without delay; (2) this material was fed horizontally by a drag chain conveyor into a rotating carbide pick breaker that broke all oversize material into a beltable size, and (3) it fed this broken material onto the belt conveyor at a rate conducive to its design. Since its introduction, the Feeder-Breaker has evolved from that first low capacity, low breaking force machine to today's model capable of breaking materials up to 5 MOHS in hardness and having throughput capabilities exceeding 3,000 TPH with availability in the 90 percentiles.

Jan 1, 1985