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By B. Kolonja

This paper considers simulation of truck dispatching system designs using maximum expected production of the truck-shovel system as the measure of performance. Two methods are utilized, multiple comparisons with the best (MCB) and the combination of MCB and the variance reduction technique known as common random numbers (CRN). These two techniques are compared via simulation experiments. The results show that the combined procedure of MCB with CRN is the superior tool to reduce the total number of replications needed to ensure the specified probability of correct selection over the finite number of designing systems. In this case study, MCB with CRN reduces the variance by 29% and the number of required replications by 48%. Also, the MCB with CRN procedure narrowed the confidence interval by 18%.

Jan 1, 1994

By T. J. Durbin

At some surface and underground mines, control of ground-water inflow involves significant costs. These costs include the capital costs for installing a dewatering system, power and other costs to operate and maintain the system, and costs to treat and dispose of the water that is collected. To minimize these costs, design of a dewatering system utilizing wells has been formulated in terms of a nonlinear operations research problem using quadratic programming. Using this formulation, the locations, depths, pumping rates, and pumping schedules of wells are selected so as to minimize the total costs of the dewatering system.

Jan 1, 1993

By Norman Weiss

The purpose of this paper is to relate progress in the engineering field called Minerals Beneficiation to undergraduate and graduate education in our colleges and universities. So mach has been written recently about the education of scientists and engineers that I've had to struggle against the temptation to repeat what has been often said before, particularly because man like Robert Mehl of Carnegie Tech, Antoine Gaudin of MIT, H. M. Davis of Penn State, and John Vanderwilt of Colorado School of Mines have recently written many quotable paragraphs on the subject. In the matter of progress, the rapidity of proliferation in the area of physical and chemical beneficiation is convincing proof that this is indeed a lively art, and having been a millman for 35 uninterrupted years I prefer to lean on personal observations to some extent, rather than on statistics and charts v culled from the journals. I propose in this paper to talk first about the progress we've made in our branch of the mining industry in the last 3 decades--particularly in the last few years--and try to show that future progress will depend upon the quality of education and capacity for research possessed by our colleges. The second part will deal with some of the problems the colleges encounter in trying to fulfill these responsibilities.

Jan 1, 1959

By I. E. Odom

A study was made of the physical and chemical nature of silica minerals found as natural impurities in bentonites and montmorillonitic Fuller&apos;s earth clay products as well as in <10 micron dust from eight processing plants. The results show that the silica minerals present in these clay materials are totally encapsulated or encased in clay. No "free" silica minerals could be observed in SEM images of either granular or powder products or in dust samples collected for MSHA crystalline silica analysis. Silica minerals, such as quartz, are identifiable by SEM and EDS analysis only after removing the clay coatings by vigorous washing. After washing it can be observed that all crystalline quartz grains also have diagenetic overgrowths of what is probably opaline silica. The clay and opaline silica encapsulation of quartz plus the strongly hydro scopic nature of montmorillonite are believed to be responsible for there not being a single confirmed case of silicosis among workers in the subject plants after more than 65 years of production.

Jan 1, 1996

By R. J. Good

It is well known that the elimination of impurities such as iron pyrite, shale, clay, silica, etc., from coal, by floatation [Sun, 1954; Aplan, 1983] and selective oil agglomeration [Keller and Burry; 1990] depends on the fact that coal is hydrophobic, and the impurities are hydrophilic. The water contact angle has long been used to evaluate the hydrophobic nature of coal, first by Brady and Gauger (1940), who demonstrated that the contact angle of water on coals increases with rank, and passes through a maximum at about 88% carbon. Brown (1962) found that the contact angle of coal decreased with increasing ash content. Sun, and also Aplan, have reported a direct relationship between values of the contact angle and rank, and have related the contact angle to coal floatability. Horsley and Smith (1951) first demonstrated that the captive bubble contact angle may be used to characterize the hydrophobicity of a coal containing more than 80% carbon DAF, while Parekh and Aplan (1978) have shown that the sessile-drop technique may be used to evaluate the hydrophobicity of coal of any rank.

Jan 1, 1992

By Zhang Youdi

A two-step approach has been developed for surface mine short term planning by the authors. The first step is mid term control and planning by the use of Goal Programming. This step gives optimal results for mid term planning (i. e. yearly or quarterly mine plan) as well as a macro control for short term planning (i. e. monthly or weekly plan.) The second step of the approach deals with short term production scheduling by the application of CAD technique and Systems Simulation. An interactive color character graphic design system has been developed with a software package. The menu-driven and module- structured package provides sufficient functions for surface mine short term planning and makes the model very flexible and user-friendly. This model has been applied to a large surface coal mine for short term planning optimization. Satisfactory results have been obtained. It is concluded that for complicated mining conditions this two-step combined approach gives an optimal control of mid term planning, makes the short term planning easier to avoid blindness; it has been proven that the Goal Programming is a powerful tool for solving multi-objective decision-making problems; guided by GP mid term planning, the CAD technique and simulation software package for short term planning are able to be concentrated on their practicality and flexibility.

Jan 1, 1992

By Jair Carlos Koppe, João Felipe C. L. Costa, Luis Eduardo de Souza

United Nations (UN) has been leading an international committee to define the guidelines in reporting resources and reserves. The system proposed by UN is very similar to the guidelines currently in use in Australia known as JORC guidelines (Joint Organisation Reserves Committee). The JORC guidelines show major differences in relation to the Brazilian system current in practice. The important aspects differing JORC from the current Brazilian guidelines for reporting reserves is the required sampling spacing. The JORC system requires the points of observation to be closer spaced than the Brazilian system for any class of resources. All classification systems share some common aspects in terms of defining the classes of resources based on distance separating samples and on the degree of confidence or accuracy associated with the results reported. Despite of being very clear in terms of stating sample distances, all the systems of classification do not provide clear definitions on how confidence limits should be calculated. This paper proposes a geostatistical framework to measure the uncertainty associated with the reported tonnages and grades. Results demonstrate that the error associated with an estimate can be approximated using multiple simulated deposits to define confidence limits. The methodology is illustrated in a large Brazilian coal deposit and proved to be appropriate to address the issue of quantifying the uncertainty necessary to be incorporated in the systems of reserves classification.

Jan 1, 2002

By Oren Tranbarger

The ability to sense or detect the coal/non-coal interface during mining can provide numerous advantages for improving net coal recovery and quality, for increasing productivity, and for mining coal which would otherwise be ignored. This is particularly true when considering multiple, pitching, and thin coal seams. This paper discusses the application of coal interface sensing and examines several potential coal interface sensing techniques with respect to state-of- the-art, design, performance, and cost criteria. Four interface boundaries are considered: the roof, the floor, the rib, and the forward region.

Jan 1, 1982

By Gary W. Hausler

Bergbau AG Niederrhein, a subsidiary of Ruhrkohle AG; Essen, Germany, is working coal mines on both sides of the Rhine River. The Prosper Mine in the City of Bottrop has a production of about 13,000 tons per day and has been in operation since the turn of the century. Mining has moved to the north as coal deposits south of Bottrop are exhausted. To facilitate ventilation, material handling, and transportation new shafts are being constructed in the northern coal fields. The Prosper 10 shaft is being sunk to develop the Prosper - Haniel coal field which has reserves of 280 million tons. In October, 1976 Bergbau AG Niederrhein awarded the shaft sinking contract for the 1047 m deep, 8 m inside diameter Prosper 10 shaft to Gewerkschaft Walter; Essen, Germany. Construction costs will amount to about 40 million DM with construction completion scheduled for 1981. GEOLOGY The shaft, located near the town of Kirchhellen north Bottrop, is being sunk in the Grafenwalder Horst between two faults on the south west flank of the Kirchheller Anticline. 270 m of upper cretaceus sands and marls overlay sandstone bedrock at the shaft location. The upper 124 m of this section contain highly saturated sands interspersed with marl. In order to successfully sink the shaft through this section, ground stabilization by freezing was used.

Jan 1, 1979

By H. Peter Knudsen

Karst hosted lignite deposits are characterized by variable thickness of lignite that was deposited in depressions in the karst topography and by the variable extent and shape of the lignite pods. Since the lignite to be mined will feed a mine mouth generating plant, an extremely important criteria in the mine plan is to assure continuous feed to the plant. The variability in both the extent of the pods and the thickness of the lignite within the pods must be taken into account in any mine design in order to quantify the risk that an area being developed will have enough lignite to feed the plant for the specified period. Indicator kriging was used to create a model of lignite thickness of the deposit. Pod boundaries were determined from the indicator kriging model by two methods. First, contour maps showing the probability that the lignite is above a minimum mining thickness were prepared. Using these maps the mine planning engineer can determine either conservative or optimistic boundaries. The second method recognized that the most costly error that can be made in the mine plan is to run out of lignite. Thus, a loss function was determined from the costs of overestimation and underestimation. Using this function, the probability that minimizes the risks of overestimation versus underestimation was calculated.

Jan 1, 1989

By J. R. B. Lima

The present work emphasizes the selection in the separation of the apatite/calcite by the direct anionic flotation versus the double flotation, with a reverse second stage of the Jacupiranga phosphate ore. The double flotation would allow the obtaining of two concentrated solutions: one of them mainly constituted by a calcium carbonate material (CaCO3) and the other one, phosphatic (apatite). The calcium carbonate concentrated solution is used for the production of cement. The presence of phosphatic material in the calcium solution is not desirable, phosphor being a harmful element to cement. On the other hand, smaller quantities of calcite in the phosphate concentrate would represent a substantial economy in the processes of production of phosphated fertilizers. These processes make use of sulfuric acid to the solubilization of the apatite and the presence of calcium material consumes acid. Also that, when carbonates are solubilized, unwanted products are formed resulting in losses in the process and diminishing the quality of the fertilizer produced. These characteristics are discussed in the paper and are compared to another Brazilian phosphate ore, the reverse route of which can be considered more adequate. The results are discussed according to recent discoveries, and special emphasis is given to the use of corn starch and its crucial role in promoting the selection in the direct flotation process.

Jan 1, 1993

By Robert T. McKnight

Introduction The minerals exploration business, like many businesses, is faced with the problem of valuing future, risky cashflows. These cashflows are derived from those mineral deposits which have been successfully commercialized. Many deposits, however, do not have the quantities or grade of ore to be considered economic at the projected metal prices using the traditional tools of the Capital Asset Pricing Model and discounted cashflow analyses. If one calculates the future revenues, costs and cashflows of one these marginal properties, and discounted it at the appropriate risk-adjusted discount rate, it may have a negative present value. Yet such a property may still have real, positive value in the marketplace. Why would a firm pay money for a property with an (apparent) minus present value? Mining properties such as these are bought and sold in arms- length transactions on a regular basis. Why is this so? Part of the reason relates to the nature of ore reserve information. To generate cashflows, the analyst must t assume that the reserve information is known with certainty when, in fact, reserves are not known with certainty. Mineral reserves are a function of commodity price, extraction costs and the level of (usually drilling) information about the reserves. Stated, or currently known, mineral inventories may vastly understate the true state of nature. Some firms may therefore be buying a property based on a completely

Jan 1, 1988

By J. A. Herbst

Ball mill grinding circuits can be subject to upsets that arise from variable characteristics of the feed ore. These upsets are transients in critical circuit variables such as ball mill mass holdup, circulating load, sump level, cyclone efficiency and product particle size. They may occur frequently so that the operation is continuously fluctuating or they may be of such magnitude that some of the equipment is overloaded, resulting in shutdown, or an undesirable product particle size. The feed ore characteristics that influence ball mill circuit behavior in this manner include the grindability of the ore, the eventual transport characteristics of the ore in the mills and the feed ore size distribution. Control strategies for grinding circuits using conventional proportional-integral (PI) control have limitations to their effectiveness in controlling against feed ore disturbances. The first of these are the interactive nature of two or more control loops on a single circuit. Under some circumstances they begin to fight each other, increasing control error and settling time. PI control loop gain constants can be tuned to give best response for some set of conditions but once these change, as they would with a change in the feed ore, they are no longer the "best" ones (Shinsky, 1967). Due to these limitations, alternatives to conventional PI control strategies have been investigated for grinding as well as other mineral processing operations. These alternatives, all computer-based, include self tuning regulators, decoupling control and optimal control (Herbst and Bascur, 1983).

Jan 1, 1984

By Joseph M. Chelini

The report shows the sensitivity that nine different cash-flow factors have on the discounted rate of return calculated from feasibiliity- studies on potenital open-pit orebodies of silver, copper, and uranium. Cash-flow factors of "grade", "market value", and "recovery" are. the most sensitive. This verifies the need of reliable estimates for these factors. The cost of evaluation of "preproduction cost" is the least sensitive. This gives credence to the fact that more consideration should be given to compiling sufficient data, as the largest financial losses are not in the cost of evaluation but rather in the abandonment of an unprofitable mining operation after a commitment of capital is made on the basis of an incomplete evaluation. Sensitivity analysis of cash-flow factors enhances evaluation programs by disciplining the collection of data and allowing more realistic distribution of evaluation monies.

Jan 1, 1971

By G. V. Borquez

For many years drilling and blasting has been considered more of an art than a science. This is still true in some respects, but today scientific approaches to drilling and blasting design must be used to plan an efficient operation which achieves desired fragmentation within constraints. These constraints involve minimizing damage to the wall or nearby permanent structures and avoiding undesirable fragmentation and mine dilution which can adversely affect operation costs. The degree of fragmentation by blasting is the most important single factor in any attempt to optimize the overall cost of the mining operations. The mining cycle begins with the drilling and blasting operations, which result in a given blasted rock size distribution. While this operation represents only about 20% of total mining costs, the efficiency and costs of the subsequent operations are strongly dependent on the fragment distribution obtained.

Jan 1, 1986

By A. Juganda, Jr. Bogin, S. A. Lolon, J. F. Brune, J. W. Grubb

"A longwall gob is mainly filled with broken rocks from the collapsed roof and becomes a porous medium where explosive methane-air mixtures can accumulate. In bleeder ventilation systems, this mixture can migrate out of the gob into the longwall face and other active areas in the mine during barometric or ventilation-induced pressure changes. When external pressures change, the gob does not perceive this disturbance instantly but with a delay due to air flow resistance in the porous gob material. The delay of gob response to outside pressure changes increases the pressure differential across the gob and may cause an outflow of explosive air mixtures from the gob into the adjacent bleeder entries. With computational fluid dynamics (CFD) modeling, researchers at the Colorado School of Mines have evaluated the impact of gob pressure fluctuations on the outgassing of the explosive gas zones (EGZs), the magnitudes and rates of pressure changes, the volumes as well as the potentials location of outgassing if it occurs. INTRODUCTION The air pressure field in underground mines is controlled by many factors such as operating fan settings, ventilation controls, surface atmospheric conditions, and other local events that can intermittently disturb mine pressure, including blasting, roof falls, or inundations. Mine fan settings are rarely changed. Mine atmospheric pressure fluctuations due to adjustments in ventilation controls occur more often during the mining process. Atmospheric conditions and barometric pressures can generate fluctuations in mine pressure on a large scale. Atmospheric pressures change regularly every day but can fluctuate abruptly and become increasingly hazardous in adverse weather conditions. Investigations conducted in coal mines in the United States, Australia, Poland, and South Africa observed higher methane emissions from the gob during periods of falling atmospheric pressures, which led to mine explosions (McIntosh, 1957; Boyer, 1964; Kissell et al., 1973; Fauconnier, 1992; Belle, 2014; Wasilewski, 2014; Lolon et al., 2015). Falling external pressures are understood to cause potential outflow of explosive mixtures from the gob, while rising pressures may push fresh air into the gob. This phenomenon is widely known as gob breathing. The actual processes that trigger gob breathing are not fully understood, nor are the parameters that contribute to the process. Other major events such as roof falls or fan failures can also change the pressure conditions in the mine. In contrast to atmospheric pressure changes, these events can change mine pressures much more rapidly or immediately. TIME LAG AND GOB BREATHING CONCEPT In a bleeder ventilation system, the pressure in the gob is designed to be lower than that of the headgate entries and the longwall face. Air from the gob and gate entries flows towards the tailgate-bleeder returns. When the external pressures are disturbed, this designed pressure arrangement may change, potentially resulting in increased outflow from or inflow into the gob."

Jan 1, 2017

By L. F. Engle

There continues to be a certain magic attached to the word "Automation". When properly planned for, engineered, installed, and operated, the magic truly does take place - witness certain publicized mineral processing, metallurgical, and chemical plants. They operate successfully with few people, instead of previous dozens as in similar facilities not automated. Production quality has improved. Maintenance costs have been lowered. When such welcome results are achieved, it&apos;s proved to be a function of method and procedure in establishing criteria for choosing the intelligence and control systems followed by skilled choice of the specific elements used. The criteria, the bases for decision, are associated with design, construction, startup, operations, and maintenance. How to go about automating any process system to achieve the optimum profit depends on attention to all those aspects of a project. None of them can be forgotten if maximum satisfaction is to be gained. Control loops that look wonderful on an equipment. Piping, and Instrumentation diagram can suddenly turn into costly and. annoying problems in the field if there has been too little coordination of design. Panel boards that are literally works of art just before startup can become the largest of white elephants if an air header is inadequately sized and the pneumatic control circuits are sluggish. Conveyor belt replacement costs can skyrocket if a critical discharge chute far away from immediate operator attention lacks a simple yet effective clog-chute switch. Planning, execution, and followup of the work, the skills, and function of-the automating material can make any new project a success. An integrated owner contractor, producer-engineer approach is the key.

Jan 1, 1963

By K. Anderson

There is a credible, cogent, and responsible argument that mining can be part of a sustainable future in countries with freely elected governments, transparent and enforceable laws, a closure plan with an adequate bond, and a small handful of other measures. This perspective, built largely upon the understanding of mining as a temporary use of the land, is coupled with a growing understanding of economic diversification as a tool to level out the ‘bust’ side of the boom and bust cycle. There are verifiable signs of progress that the sector has, at least in some venues, begun to embrace this view of ‘sustainability’ both in philosophy and practice. While laudable, there remains a conundrum not yet fully explored. It is conceivable that companies can fulfill all legal requirements, practice corporate responsibility in its broadest and most liberal interpretation, and yet leave behind, after the gates are closed and the lights turned off, a situation which is not only unsustainable, but far worse off than before mining started. Having observed this outcome, repeatedly, some critics have concluded that all mining should be stopped. Others recommend that it be vastly curtailed until regulatory regimes are re-vamped, communities fully empowered, and companies brought to heel. Yet others, including many within the industry, are looking to hold back this dark prospect with peer pressure, branding and competition for good will. In this paper, I propose to focus on this discontinuity, that gap wherein the chain of logic breaks and reasonable policies, reason-able choices, reasonable actions, may fail to deliver expected results. I suggest that any meaningful definition of post-closure sustainability must include the concept of human welfare, and increasingly, human security, over and above meeting the requirements of law, beyond retaining shareholder value and reputation, beyond discussions of subsequent land use and diversified employment. I suggest that self-determination, that ability of a people to hold for themselves the vision of their own future, and to have a sense of their power to implement it, may be both the most difficult and the single most important determinant of long-term sustainability in a community. The particulars will vary; a Canadian junior or an Australian multinational, a highly regulated state in the American west or a ‘failing state’ in Africa’s west, gold or sand and gravel. But the recommendation is the same: this must be a collective endeavor, a shared responsibility involving some combination of government, companies, communities, local and international NGOs (non-governmental organizations), each contributing in the ways most able.

Jan 1, 2004

By William E. Wallace, Michael J. Keane

This review summarizes three sets of ongoing studies which we are performing in collaboration with a number of researchers associated with the Dept. of Interior - Generic Mineral Technology Center for the Study of Respirable Dusts, concerning surfactant-particle interactions studied using this surrogate surfactant. These topics are: (A) the suppression of mineral particle cytotoxic potential by DPL adsorption and the persistence of this effect under conditions of enzymatic digestion; (B) surfactant suppression of organic particle cytotoxicity by DPL adsorption and the effect on subsequent expression of genotoxic potential; (C) potential effects of surfactant on heterogeneous structured complex respirable particles. The references list some of our reports which can provide additional information on these studies. Further, those reports provide references to the literature of the field and to the works of others on these topics. Deep lung airspaces, the pulmonary alveoli and respiratory bronchioles, are coated with a hypophase which is rich in surfactant biomolecules secreted by the alveolar type II epithelial cells. The surfactant is known to be critical to maintaining stable low surface tensions on the inner surfaces of the alveoli by forming a surfactant layer on the airliquid interface of the alveolar hypophase. Upon deposition in the acinar regions of the lung a respired particle&apos;s initial contact will be with this surfactant coating over pulmonary tissue. A primary component of this surfactant is the phospholipid diacyl glycerophosphorylcholine, commonly called lecithin. A surface layer of dipalmitoly lecithin on saline will act much as full pulmonary surfactant in decreasing surface tension and producing a hysteresis in surface tension behavior with surface area. We have used dipalmitoyl glycerophosphorylcholine, or dipalmitoyl lecithin (DPL), a major component of that surfactant, dispersed in physiologic saline as a surrogate for studying interactions of both mineral and organic respirable particles with pulmonary surfactant and consequent effects on particle toxic behavior. A. DUST CYTOTOXICITY AND LECITHIN SURFACTANT ADSORPTION Respirable quartz and kaolin clay particles are found to be comparably cytotoxic in a number of in vitro bioassays including lavaged rat pulmonary macrophage release of cytosolic and lysosomal enzymes, and red blood cell hemolysis as a measure of dust membranolytic potential. These direct and prompt cytotoxic activities do not account for the distinctly greater potential for quartz to induce pulmonary disease. When respirable quartz and kaolin are incubated with a dispersion of DPL in saline at 37C it is found that the prompt cytotoxicity of both dusts is fully suppressed as measured in vitro by pulmonary macrophage release of lactate dehydrogenase, beta-N-

Jan 1, 1991

By Ronald E. Feltman

Most engineering firms engaged in the design and manufacture of milling components and systems have established, through the years, a relatively well defined system design procedure. The process design engineer has at his disposal several alternative approaches to the successful completion of this task. Unfortunately, while these alternatives, at first glance, appear to be rather straight Forward, any attempt to implement them into a fully integrated commuter design program becomes increasingly more complex when one addresses himself to the problem in total. This paper summarizes Kennedy Van Saun&apos;s approach to the solution of this problem through a planned system design. Following the problem definition and discussion, a detailed analysis and system design synthesis is presented; the major aim here being to provide a system design which may be programmed and run on a relatively inexpensive computer installation such as the IBM 1130 system currently in use at Kennedy Van Saun. A summary section is also included, which Provides a general outline guide to the program systems design of equipment which, while quite different from milling system functionally, nevertheless lends itself to the approach used in this paper.

Jan 1, 1969