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By A. R. Zambrano

Equations for Power Draw, Capacity, and Work Input for predicting the performance of industrial grinding mills are derived based on torque measurements obtained in a laboratory instrumented mill. These derivations are based on mechanical principles and on the first order kinetics of the grinding process. Rittinger's, Kick's and Bond's laws express Work Input as Work Index, W;, times a Particle Size Function. These laws are only particular cases of more general expressions having the Particle Size Function raised to an exponent, the Work Exponent We. Case studies illustrate the excellent prediction of the W;-We models, compared to the three mentioned laws.

Jan 1, 2001

By F. Rosenblum, P. Cancilla

The manual moisture determination methods employed today by mineral processing plants falls short in providing timely information required for automatic control. The costs associated with transporting and handling concentrates still represent a major portion of the overall treatment price. When considering the cash flow of a mining operation, that is governed by both the smelter contract, with moisture penalties and the quantity and quality of the concentrates shipped, an efficient method of on-line moisture content would be a welcome tool. A novel on-line determination system for ore concentrate moisture content would replace the normally tedious classic manual procedure. Since the introduction of microelectronic¬based control systems, operators have strived to reduce the treatment costs to the minimum therefore a representative and timely determination of on-line moisture content becomes vital for control set points and timely feedback. Reliable sensors have long been on the "wish list" of mineral processors since the problem has always been that you can only control what you can measure. Today, the task of moisture determination is still done in the classical technique of loss in weight utilizing uncontrolled procedures. These same methods were introduced in the earliest base metal concentrators. Generally, it is acceptable to have ore concentrate moisture content vary within a range of 7 to 9%. Many times, delays in manually achieving reliable feedback on the moisture content results in the moisture varying from 5 to 12% before corrective actions can be made. This paper first reviews the traditional and widely available methods for determining moisture content in granular materials by applying physical principals and properties to measure moisture content. All methods are in some form affected when employed on mineral ore concentrates. This paper describes a unique and promising on-line moisture sensor in two mineral processing applications, which not only automates the tedious tasks but also results in reliable moisture feedback that can be used in the optimization of the de-watering process equipment such as pressure or vacuum filters and fuel-fired driers. Finally, two measurement applications will be presented to indicate the usefulness and to summarize the measurement requirements for the proposed method of employing drag force and mechanical properties of the material itself to determine the moisture content.

Jan 1, 2002

By P. N. Thompson

The past few years have seen the introduction of mini-computers on an increasing scale at collieries in the British coal industry. These are being used for controlling underground transport systems, coal preparation plants and fixed plant (pumps etc.); and for monitoring the mine environment and face operations.. A separate mini-computer (termed a primary computer) is dedicated to each of these functions. The overall system under which these computers operate is a common one which is applicable at all collieries. The information collected by the primary computers, other than that required for immediate control, will be fed to a secondary computer for analysis and processing. This overall concept, called MINOS. (MINe Operating System) is being developed by the National Coal Board's Mining Research and Development Establishment (M.R.D.E.). Eventually most of the data required by the system will be captured automatically. For example, the fact that a delay has occurred on a face, together with the duration of that delay, will be detected automatically via transducers link linked to a primary computer. However, the reason for that delay will, in all likelihood, have to be recorded manually. Such a system is currently under development with the first trial installations now being made.

Jan 1, 1979

By P. Mousset-Jones, G. Danko

Rock thermophysical properties, i.e. heat conductivity and thermal diffusivity, were obtained for reference values at the Waldo Test Mine for mine fire simulation purposes. An in situ measurement method was chosen since it could include the effect of rock fractures. The REKA method (Rapid Evaluation of k and alpha) was used because it can measure conductivity (k) and diffusivity (alpha) simultaneously within an eight-hour measurement period. A total of six measurements were taken in three different holes, and at two different depths from the collar of the hole. Each measurement provided an averaged conductivity and diffusivity for a volume of rock of approximately one cubic meter. The boreholes were driven into the upper and lower limestone, two at right angles to and one parallel to, the stratification of the rock. Significant representative conductivity and diffusivity values were obtained for the whole mine by averaging the six measurement results. The thermal properties for the band of shale in between the two limestones were not measured in situ, but only in the laboratory. Problems were encountered in the evaluation because of unexpected heat conduction on one side of the symmetrically built probe. A modification was made to the previously developed evaluation method together with further testing and correction, before the final results were obtained. As expected, the in situ and lab- oratory measured values of k and alpha compared favorably, since the in situ rock was dry and relatively unstressed.

Jan 1, 1989

By Doug Williams, Kent J. McGrew, Dr. Jack Murphy

For some time, selenate has eluded water treatment by conven­tional means such as precipitation and clarification. This has been due to the nearly universal solubility of all oxidized sele­nium species, the low levels required for surface discharge, and almost identical chemical behavior to all forms of oxidized sul­fur. The last characteristic makes selenate particularly difficult to deal with in acid mine waters where sulfate can easily be on the order of one gram per liter. Approaches such as ion exchange or reverse osmosis often tum into total demineraliza­tion schemes for the sake of removing a "trace" selenium species that may be present on the order of 108 sulfate/selenate. Reduction of selenate to selenite or elemental selenium by chemical means has been relatively unresearched. Some limit­ed success has been reported (Murphy, 1988) using ferrous hydroxide as a reducing agent; however, the reaction time as reported is too slow to be useful in a practical plant design. One significant difference between selenate and sulfate is that selenate has been discovered to be reducible in acid solution by elemental iron when catalyzed by soluble copper. Since the +4 or zero valence states of selenium are rather easy to deal with by coprecipitation with iron salts or alum, the elemental iron dis­solved in the process contributes to the overall process by pro­viding sludge upon raising the pH that can be separated by con­ventional clarification. Commercial production of selenium using copper catalyzed reduction of selenite to selenium metal via sulfur dioxide is well established, however, at the < 5 ppb requirements for surface discharge this reduction process equili­brates at levels far too high to be useful to low level selenate removal criteria. The reaction reported herein uses elemental iron for reduction of selenate with copper acting either as a cata­lyst or as a coprecipitation agent. This method, employed with conventional sludging, clarification and filtration can provide an economic method to achieve non detectable selenium (< 0.005 mg/I). Iron consumptions for the conditions tested have been on the order of 3 lbs/1,000 gallons treated. This represents as little as $0.06 or $2.00 per 1,000 gallons based on using a scrap source of iron or the purchase of electrolytic iron for the process.

Jan 1, 1996

By J. West-Hansen

The problem of long-term production scheduling in an underground coal mine is approached through the concepts of sequencing theory. Based on a typical layout of mining sections, the principles for the approach are: 1. The definition of mining sections as jobs, and mining methods as machines. 2. The reduction of the overall mining activity to the general problem of nonpreemptive scheduling of precedence related jobs on parallel machines. 3. The simplification of the layout to a general type directed network with the nodes representing jobs and the arcs representing precedence relations. 4. The determination of a feasible and near-optimal job schedule given the objective of maximizing the total net present value of the jobs. A general scheduling heuristic is being developed for implementation on an IBM personal computer (PC) as part of an interactive computer system for long-term production planning.

Jan 1, 1986

By A. Fiszer

One of the major problems with deep Polish hard coal mines are deformations of close-to-wall galleries since they are necessary and must he kept open for emergency situations and are largely responsible for work disturbances. In order to ensure safe and effective working operations, it is necessary to often rebuild galleries which, apart from the inevitable stoppage of operations, is greatly disadvantageous for the operation of a mine. The largest problems with maintaining the galleries open occur in Lower Silesian Coal Field mines where sometimes it is necessary to reconstruct the galleries several times [(Fig. 1)]. In light of what has been said above, the aim of this article is to present the reader with methods and ways of determining deformations occurring in close-to-wall galleries. Squeezing or convergence of headings is only a portion of the entire process of ground movement caused by ground disturbance due to workings. The term "squeezing of headings" is to be understood as a shortening of the distance between a point set on the roof of a heading and the corresponding one on the floor. It is very important to know the rules governing the process of squeezing in a particular mining system since it affords possibilities to define changes of the process and its parameters at any moment for a given system. This is of utmost importance because convergence of a heading is one of the most significant manifestations of ground pressure which has already been proved by studies performed by Everling (1). On the basis of those studies it has been observed that there exists an almost linear relation between the rate of convergence and loading [(Fig. 2)]. This, in turn, means that the deformations of the already exploited portion of heading are proportional to the pressure changes.

Jan 1, 1982

By Steve R. La Brooy

Techniques for dealing with copper-gold ores are reviewed. Cyanide has little selectivity of gold over copper, and depending on the reactivity of the copper minerals cut-off grades for gold recovery by direct cyanidation are generally below 0.5% copper for oxide ores and 1 % for sulfide ores. Non-cyanide gold leachants also tend to be reactive to copper. The cheapest option for sulfidic ores is to produce a flotation concentrate for smelting, while transition ores generally need a sulfidisation pre-treatment. The requirement for the concentrate to have a high enough copper grade to be acceptable to a smelter may compromise copper and gold recovery. This can lead to significant gold grades in the flotation tailing, and copper levels in the tailing that are too high for direct cyanidation to be able to recover the gold. Oxidised ores, flotation tailing or other material not amenable to flotation represent the greatest grey area for gold recovery. Copper removal by acid, alkaline or ferric pre-treatment is possible though not generally used. Cyanide pre-leaching to remove copper, followed by copper and cyanide recovery represents a potential option that has been installed at one Australian gold plant, where copper is recovered onto carbon, ahead of the slower leaching gold. Actual cyanide recovery depends on ore mineralogy, allowing for losses as cyanate, thiocyanate, carbonate and ferrocyanide. Alternative options for gold recovery following cyanide leaching include precipitation, ion exchange and solvent extraction of the gold. Ammonia-cyanide leaching may offer another option for more selective gold dissolution from flotation tailing and oxidised materials. A plant is currently under construction in Mauritania.

Jan 1, 1992

By Maribeth Amyot, Y. J. Wang, S. S. Peng

Introduction The impact of computers on individuals and businesses increases each day. And the mining industry is no exception. The growing number of short courses, symposia, and feature articles in journals on the subject of computers is indicative of the developments and interest in their application to mining. Given this interest and the growing importance of computers, a legitimate concern is the computing background of graduating mining engineers. Based on a sample survey, this paper presents the current status of computer education in Accreditation Board for Engineering Technology (ABET)-accredited mining engineering programs in the US. Specific topics addressed include hardware and software available to students, integration of computers into curricula, concerns of mining educators, and historical and anticipated trends in computing education. Methodology Nine of the 19 ABET accredited mining engineering schools (as published in the SME-AIME Guide to Minerals Schools) were surveyed. Interviews consisting of open-ended questions were conducted with a knowledgeable faculty member from each of these schools. This was done to obtain an overall view of computing in mining engineering programs. The intent was not to evaluate nor compare individual schools, so a complete census was deemed unnecessary. The minimal deviations between the responses to the subjective questions reinforces the credibility of the sample as being representative. Results Hardware Most of the mining engineering schools polled had access to hardware on three scales - mainframe computers available university wide, minicomputers available in the college or department, and microcomputers available at all three levels. Without exception, each school had access to mainframe and microcomputers. Minicomputers, however, were not available at every school. The mainframe computers have been in place the longest. The predominant mainframe currently on campuses is the IBM model. Mainframes were once the essence of all applications. But the improved availability and capabilities of smaller machines have afforded users a viable alternative. The increasing practice in education of assessing charges for time used on the mainframe - as opposed to no charge for time on the mini- and microcomputers - makes use of the smaller machines attractive. Conversely, much of the mining engineering software is only operational on mainframes. Sometimes this restriction exists because the requisite speed or storage inherent in the software can only be met by the mainframe. More often, however, it is because the software was developed when mainframes were the only machines available, and it has not yet been adapted to run on a smaller machine. At the schools polled, many mining engineering problems that are well suited to microcomputers are being solved on mainframes simply because microcomputer software is not available. Minicomputers are available at the department or college level in many mining programs. DEC is the most popular make. Often, the minicomputers were installed to alleviate the inconveniences of attempting to access and use an overcrowded mainframe, to avoid being charged for time used on the mainframe, and to meet the needs of a specific research project. The minicomputers are currently used much more for research than for teaching applications. Therefore, minis are seldom used by undergraduate students. Microcomputers have become extremely popular at mining schools within the last five years. Generally, some form of computing policy or strategy was established near the time the first microcomputers were purchased. This was formulated in part to ensure consistency, or at least compatibility, in the type of machines acquired. Microcomputers were subsequently selected based on the established computing policies; ma-

Jan 7, 1985

By Jodie Robertson, Isabel Barton, Cristian Caro

Prior to mining, all rocks contained in a mineral deposit must be placed in one of several categories known as ore types. Each ore type describes a different way that the rock will behave in processing. The ore type determines which process stream a particular mined unit will be sent to, sets expectations for process engineers and metallurgists, and forms the basis for recovery predictions and production estimates. At first, ore types are assigned mainly by geologists based on visible geological criteria (dominant ore mineralogy, estimated grade, rock type, alteration type). As metallurgical tests are carried out and process data accumulate, the resulting criteria may be factored into the ore typing process, typically as assays and recoverable metal using the relevant process(es). Other variables may also be incorporated into ore typing at operations if they are particularly important, such as grindability, preg-robbing, gangue reagent consumption, and the presence of especially deleterious minerals such as talc or smectite. The mine operation department may also redefine ore types and/or process destinations based on economic criteria. A “best” ore type is designated that (in theory) best describes how the rock will behave in processing. Codes representing this ore type are entered into the drill-hole database, then interpreted on cross sections and level plans, and finally added to the block model. Ore types are iteratively reexamined and adjusted over the life of a project. Major difficulties in effective ore typing are (1) lack of communication between geologists and metallurgists, (2) the imprecision inherent in imposing clean categories on messy natural systems without discrete divisions, (3) the need for ore types to provide useful information for a wide range of processes, (4) difficulties in scaling up laboratory test results to mine production, and (5) conflict among geological, metallurgical, and economic criteria for ore typing.

Jul 1, 2024

By F. C. Eberhardt

Systematic planning of underground work is increasingly important in this era of advancement of rapid underground excavation techniques. The day when planning consisted of deciding which men would shovel and which would push wheelbarrows - and the answer to any problem was more men - has faded into the past. The modern underground constructor faces economic and competitive conditions which demand exacting planning, logistics and scheduling; the most efficient operating methods and equipment known; and realistic, comprehensive, analytical risk evaluation with adequate contingencies or other protection. Proper planning to cover all these elements - plus one other element: old fashioned "good luck" - will insure a successful underground project. Underground work, because of its inherent characteristics, is among the most risky types of construction. The forecasting of underground conditions is at this time only educated predictions based on sometimes faulty data, insufficient data, or no data at all. The predicted conditions of numerous operations have deviated far from the actual conditions encountered. Opportunities for error exist in profusion seldom present for surface operations. Other than this unusual risk factor, the planning for underground work does not differ greatly from planning for surface work. In planning and starting an operation there is seldom available the information or time to thoroughly analyze all unknowns. It then becomes necessary to develop a plan predicated on assumptions and trade-offs that appear to be safe and economical and to add time and cost contingencies that will provide some degree of protection. On competitively bid fixed price work, choice of markup on estimated

Jan 1, 1974

By Paul Saxton

INTRODUCTION AND SUMMARY This short paper deals with the history of the Nickel Plate Mine from 1898 to 1987, with the major focus on the time period 1984 to 1987. Operations from 1898 to 1955 are reviewed in a cursory manner with the emphasis on some interesting points in the early 20th century. A review of the major exploration work carried out in 1984 to 1987 is presented and the process of moving the project through feasibility, government permitting and construction is described. The Hedley gold camp is situated approximately 40 kilometres east-southeast of Princeton, in southern British Columbia. The area has had a long history of gold mining and between 1902 and 1955 approximately 1.5 million ounces of gold were won from several mineralized skarn orebodies. Most production came from the Nickel Plate and Hedley Mascot mines. AN EARLY TO MID 20TH CENTURY SUMMARY The Nickel Plate is one of the oldest mines in the province. The mine had operated from 1904 to 1930 and, after a period of shutdown, from 1934 to 1955. The mine was revived in 1967 for exploration and. will resume production during the first half of 1987. In the first period the Yale Mining Company and Daly Reduction Company operated for six years and Hedley Gold Mining Company for twenty-one. In the second period the mine was operated by the Kelowna Exploration Company Limited and Kelowna Mines Hedley Limited for twenty-one years. In the present period the mine has been revived by Mascot Gold Mines Limited.

Jan 1, 1987

By J. Keng, S. T. Chen, T. M. Shih

Kwanyin Tunnel is presently the longest (7.7 km) railway tunnel in Taiwan. Due to heavy railway traffic, a pass-by station will be built inside the tunnel to increase the traffic flow. Since the concentration of toxic gases released by the locomotives may reach dangerous levels, a research program was conducted for the purpose of designing a ventilation system which could dilute and/or remove the toxic gases to maintain an acceptable pollutant level. The program consisted of two parts. The first part was field measurement during which the concentrations of pollutants and wind velocities were measured at various points inside the tunnel to acquire basic data regarding ambient air quality, piston effects for the different types of trains, and existing ventilation conditions. Weather data (temperature, humidity, atmospheric pressure, wind direction and velocity) were gathered at many stations, both on the surface and inside the tunnel. The amount of pollutants released by each type of locomotive for various conditions were also measured. The second part of this study involved establishing mathematical models for predicting the air quality of the various proposed ventilation systems. Three different models were used for this work. The first one is a piston effect model which assumes that the gases and air undergo immediate mixing inside the tunnel. The second one is also a piston effect model which assumes that the diffusion ability of the gases is zero. The third one is a conventional ventilation model which was used for natural and mechanical ventilation conditions. From the result of field measurement and mathematical model studies, a ventilation system was chosen with consideration of both ventilation effects and construction costs.

Jan 1, 1987

By A. Casuge, D. Lee, J. A. Finch, C. C. Sui

The adsorption of copper and lead und their subsequent xanthate uptake were compared at pH 3.0, 6.0 and 9.2 on both fresh and oxidized sphalerite. The extent of adsorption and the rate of adsorption were strongly dependent on pH, with the highest adsorption of Cu and Pb being at pH 9.2. In the presence of both Cu and Pb, Cu adsorption was enhanced and Pb adsorption was suppressed. The adsorption kinetics of Cu and Pb were characterized by two- and three-stage adsorption processes, respectively. The exchange ratio of Cu to Zn was about one and that of Ph to Zn was greater than one and varied with pH. The uptake of xarlthate on "activated" sphalerite was dependent on pH. The rnaximum uptake was found to be at pH 6.0 for Cu-activated sphalerite artd at pH 9.2 for Pb-activated sphalerite. A measure of "activation strength" based on inetal ion adsorption and xanthate uptake was introduced. The activation strength of Cu to Pb was about one at acidic pH, but it was higher at neutral (pH -6) and alkaline (pH -3) conditions. The oxidation of sphalerite decreased Pb and, especially, Cu adsorption and decreased xanthate uptake.

Jan 1, 2000

In analyzing cost performance, managers must initially consider the issue of scope. Is the analysis for a single responsibility center or multiple centers? For a single period or a number of periods? If multiple responsibility centers are being examined, how can managers compensate for differences in their sizes? Several techniques have been developed to analyze the relationships in a set of financial statements at a single point in time and the trends in these relationships over multiple periods. Cross-sectional techniques focus on the first of these, and time-series techniques look at the latter. Although this text focuses on cost performance, these methods also can be used for revenue-related analyses.

Jan 1, 1999

By K. Verghese, H. M. Lee, R. P. Gardner, K. Boateng

Results of work on the development of a phenomenological model for the continuous flotation process wing short-lived radioactive tracer techniques for determining model parameters is reported. A model that incorporates a flotation first-order rate constant and a residence time distribution based on the cross-flow finite-stage (CFFS) model has been derived and investigated. The short-lived radioactive tracer techniques and the nonlinear search methods necessary to extract the model parameters have been developed. The conditions under which all the model parameters can be extracted from a single radiotracer experiment are detailed and illustrated. A micro- computer-based unique data logging system has been designed, assembled, and implemented for collecting the necessary transient radiotracer data. Results are reported for a continuous laboratory flotation process for the two systems, mica ore and coal.

Jan 1, 1987

By A. G. Belova

Conversion of coal into high-value gases via gasification offers significant pollution reduction and efficiency improvement benefits associated with controlled combustion of clean gases for power generation. However, current gasification-based electricity production technologies, such as IGCC do not address carbon dioxide emissions. The focus of the study is CO2 capture on CaO prior to combustion of coal-derived gases. To overcome kinetic and stability limitations associated with its utilization, CaO is distributed on high-surface area -Al2O3 and supported on a ceramic honey-comb monolith. The proposed method allows for efficient capture of CO2 from a gas mixture, as studied in a flow-through reactor system. This novel method of CO2 capture is used here to argue for pre-combustion capture of CO2 in coal gasification-based power plants. When CaO is present during the steam reforming of coal gasification gases, continuous withdrawal of CO2 from the system provides for higher yields of reforming products (hydrogen gas) by influencing the thermodynamic equilibrium of the entire system.

Jan 1, 2009

By Glenn A. Hazen

Longwall mining is the preferred method for removing underground coal since a larger amount of coal can be removed faster and with less waste when compared to the room-and pillar type mining. Thus, the coal tonnage removed each year by longwall mining methods has increased dramatically. However, a high extraction rate results in surface subsidence which has adverse effects on the environment and on surface structures. Predictions of structural damage are dependent on the magnitude of the expected horizontal strains. Three methods for predicting subsidence characteristics are considered in this paper: the graphical method, the profile method, and the finite element method. All three methods can be used to predict ground movements and horizontal strains. However, the finite element method, which takes into account the structural properties of the stratigraphy and equilibrium of the overburden, is theoretically the more logical choice for use in subsidence prediction.

Jan 1, 1987

By Roshan B. Bhappu

In situ mining and extraction is one of the Frontier Technologies that is destined to play an increasingly important role in the recovery of metals and minerals in the future. This premise is based on increasing costs of labor and energy, increasing awareness of environmental considerations and decreasing ore grades in the United States. Up to now, in situ mining has been successfully applied to a few favorable situations for the extraction of some evaporites, copper and uranium. However, because of its unique technical, environmental and economic advantages, this versa tile technology will find broader applications for the recovery of above commodities as well as for others which are currently extracted by hydrometallurgical means. This paper traces the development of in situ mining and extraction; stresses its dependence on interdisciplinary science and engineering; discusses its theoretical, practical and economic aspects; and finally presents potential applications of this Frontier Technology.

Jan 1, 1985

By V. N. Kelly

The ability to link geological sections on a graphics screen to form three dimensional geology representation was implemented at Kidd Creek in 1987. This technique affords an opportunity to optimize metal estimation in ore at the Kidd Creek copper, zinc and silver mine, by applying enhanced interpretation methods. On a series of geological sections varieties of ore are outlined. These are linked from section to section to form polyhedra which closely simulate the three dimensional shapes of the different ore types referred to as mintypes. The orebodies are divided into zones, referred to as domains, that approximate the function of variograrns, for which&apos; preferential continuity of mineralization has been estimated for distances in the width, strike and dip directions. These distances define ellipsoidal volumes of influence. The domains are also linked into polyhedra. Both types, coded by ore variety and zone, are mapped into the block model. Tonnage and metal values are calculated for ten-foot cubical cells of the block model by any of several estimation methods under domain control. In estimating the metal grades for a cell the predetermined search ellipse is applied to select only those drill hole assays of the same mintype as the cell designation. Once grade estimations have been determined for the cubical cells comprising the model, a wide range of stored information can be viewed. For example, in plan at any row elevation or on vertical section at any azimuth, as either printed values for the cells or as contoured data. This flexibility is of particular value in checking and refining the geological interpretation to better conform to ore types and grades actually mined. Combined with three dimensional geological modelling, and correctly chosen domains, the use of mintypes implants essential geological control into the system and prevents assays for one ore type from affecting grade estimation in adjacent ore types. The three dimensional geological modelling and block model segments provide information which is effectively applied to the stope design, production, planning and control parts of the system.

Jan 1, 1989