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By Mark Springett

Microcomputers have rapidly evolved to the level at which they can perform almost all of the computational tasks required for exploration, evaluation and exploitation of mineral deposits. The present capabilities of microcomputers are reviewed by examining their use on typical projects from the initial capture of exploration data to the subsequent technical and financial evaluation by microcomputer. Emphasis is placed on the need for compatible software and on the importance of a consistent hardware acquisition policy.

Jan 1, 1987

By P. Somasundaran, D. R. Nagaraj, Jing Wang

Polysaccharides have been widely used as depressants in mineral processing for decades. They constituent one of the most abundant family of biopolymers. However, only a small number of them have been used by industry so far because of a general lack of understanding of interactions between these polymers and minerals. In this work, adsorption tests, electrophoretic mobility measurements, microflotation and fluorescence spectroscopic tests were performed along with computer simulation to explore the mechanistic aspects of guar gum adsorption and conformation on talc as a function of relevant variables such as ionic strength, pH, solvent composition and polymer molecular weight. From microflotation tests, it was found that talc hydrophobicity decreased markedly due to the adsorption of guar gum even at very low concentrations and reached a plateau below moximum adsorption. Guar gum adsorption on talc was found to be not affected significantly by changes in solution conditions such as pH and ionic strength, ruling out electrostatic force as controlling factor for adsorption. Fluorescence spectroscopic studies showed no evidence of the formation of hydrophobic domains at talc-aqueous interface. Also urea, a hydrogen bond breaker, reduced the adsorption of guar on talc. All of the above results suggest that one of the main driving forces for guar adsorption on talc is hydrogen bonding in preference to electrostatic or hydrophobic force. This information should help toward designing reagents of optimum molecular architecture for efficient depression, dispersion or other such surface modification of particles.

Jan 1, 2005

By Scott G. Britton

In the real world of coal mining, the bottom line for almost every support project decision is economic (i.e., what is it going to cost?). Up to this point, I have discussed the methods to improve the performance of typical support projects by better installation, materials, and techniques, thus lowering the impact of the bottom line cost. In this chapter, 1 shall explore what costs are relevant in mining construction, and how these costs are developed. The chapter centers around two major discussions: (I) developing cost accounting techniques, and (2) cost-estimating procedures for support construction. Each focuses on the fundamentals of practical cost considerations necessary for decisions on construction projects underground. Since cost accounting, economics, and investment planning are all subjects which warrant complete discussions on their own, this chapter will focus on distilling the important concepts required by a planning engineer into an easily understandable presentation.

Jan 1, 1983

By Klados. T.

MSC.Software assessed the performance of the drive end and non-drive end bearings on a ball mill using the finite element method. The assessment included the effect of mill and pedestal deformation on the performance of the bearings. Oil film thickness, oil pressure distribution and power requirement were of interest. A solution approach coupling a structural solver to a Reynolds equation solver was specifically developed for the project. Results showed that the deformation of the bearing surfaces had a significant influence on the performance of the bearings. For example, for the non-drive end bearing, the minimum oil film thickness computed for the deformable bearing surfaces was significantly lower than calculated for the non-deformable case. The results also showed that cavitation was likely in both the drive end and non-drive end bearings (severe negative pressures were obtained in both bearings). Other design variations were also assessed, e.g. a case with a modified radial clearance which improved the results.

Jan 1, 2006

By K. Irmscher

During the last years, using modular computer models on the software and distributed computer capacities on the hardware side has become quite common in the mining industry. When tackling real mining problems under the condition of heterogeneous systems, however, some problems become obvious: the incompatibility of the heterogeneous platforms in connection with the heterogeneously structured information and the necessity of interpreting the data. Knowledge based approaches are employed for solving different planning problems in the field of mining industry. The main problems here consist in the knowledge representation and data acquisition. Starting point of the investigation form classifications of mining planning problems and the corresponding models which can be transformed into information models for evaluation. With help of an expert system a practical solution is represented. Distributed systems with mobile computing and communication facilities for immediate access can be used as an additional support for planning and processing. On the base of public or private computer networks (including mobile networks) the foundation is given for a computer supported treatment of planning tasks. Additionally the use of teleworking scenarios in regions of mine planning and data collection in geological applications is prepared. Foundation forms a workflow system on an object-oriented distributed platform.

Jan 1, 1996

By John R. Turney

MARY KORPI: Harry Hinds will be filling in for John Turney today. Harry is an exception to the industry these days, in more ways than one. He has worked for the same mining company for 33 years. That is something very few of us can claim. He is currently metallurgical superintendent for Homestake Mining Company in Lead, South Dakota. Harry is also the envy of many of us as he will be retiring this year and working on lowering that handicap! Harry will be discussing the "Role of Consultants."

Jan 1, 1998

By S. D. Thompson, J. C. Dzurino

This investigation mainly focused on designing a bunker system for a large underground coal mine. The primary purpose of this bunker system was to keep high- and low-sulfur coal segregated on the underground belt system. These bunkers were also required for protecting the mine faces from out by belt delays. Methodologies used in developing this plan are briefly discussed. The final design and the procedures formulated for implementing it are also presented.

Jan 1, 1987

By John A. Herbst, William T. Pate, Ruben Tello Flores, Humberto Arreola Zarate

Plantwide control is the networking and coordination of individual control systems throughout the plant to enhance plant performance. The high level decision making involved in this coordination is used to achieve overall plant optimization. Decisions must be based on knowledge and information moving between control systems in both downstream and upstream directions and on management information systems containing financial data on the impact of coordinating actions. For example, certain quantitative descriptors of upstream operations are passed to the downstream control systems to prepare those operations for the feed material they will receive. Likewise, other quantitative descriptors of downstream operations are passed to upstream control systems to modify their output. In this case, setpoints are determined throughout the plant which maximize profitability, given current ore conditions and plant operating constraints. Due to the wide area coverage of this coordinator, it is forced to draw on several diverse information and knowledge bases. Such a coordinator, then, must rely on a combination of heuristic logic, model-based control and neural networks to unify the knowledge bases as well as to take advantage of their strengths and to compensate for deficiencies. A description is given of control systems for primary and secondary grinding and flotation at a large copper concentrator and how they are being integrated to achieve plantwide control. Financial implications are discussed.

Jan 1, 1995

By K. Wangerud, B. S. Caruso

A water-balance model with deterministic and stochastic components was developed and used for the Gilt Edge Mine Superfund Site in South Dakota. The model was developed to evaluate the risks of contaminated runoff discharging to surface waters based on assumed water treatment plant (WTP) rates, for different remedial alternatives. The objectives of the modeling were to use a stochastic approach for the analysis of precipitation based on historic records and to make a probabilistic estimation of annual and monthly runoff from disturbed/mining activity areas that now require, or will need, treatment at the WTP, water storage and changes in a major pit, and risk of contaminated water bypass of the WTP to a downstream drainage. Subareas/source areas generating contaminated runoff requiring treatment were delineated. A simple water-balance model was used based on precipitation inputs and evapotranspiration and groundwater losses. Annual and monthly precipitation records for Lead, South Dakota, were used to estimate precipitation at the mine site. A lognormal distribution was estimated for monthly precipitation. The stochastic software package/ Excel add-in "@Risk" was used to generate random monthly precipitation values using a Monte Carlo method based on the distributions. The average annual and monthly distribution of pan and lake evaporation and of groundwater losses were also estimated for the site. Stochastic outputs from the model for the end of each month and year included contaminated runoff requiring treatment, water storage in mine pits and the risk of WTP bypass given different assumed WTP rates. The probability of the time required to dewater the pits was also modeled.

Jan 1, 2003

By Jerry C. Tien

An overcast is a form of air bridge which permits one air current to pass another without mixing. It is an essential and indispensable ventilation device for underground air distribution in horizontal mineral deposits. Overcasts are also a major source of shock pressure loss under- ground. However, a well thought out overcast plan, and a well constructed overcast, will give minimum shock loss, which in turn can save money (Tien, 1986). So far, most research on shock losses has been concentrated on splits and junctions, and bends and turns, or on underground regulators. Practically nothing could be found in the literature regarding losses caused by overcasts (see reference on shock losses). In this investigation, shock losses are quantified for an overcast with different configurations, which will give useful clues toward an aerodynamically designed overcast.

Jan 1, 1987

By R. R. Oder, R. J. Gray

We report measurements of the effects of rank, type, and grade of coal on grinding energy and grinding media consumption in a Pitt Mill. The rank of coal has a greater effect on grinding energy than does coal type. The effect of coal grade on grinding energy depends upon the relative grindability of the mineral matter and of the hydrocarbon components of the coal. The mineral matter is primarily responsible for abrasive media wear in a Pitt Mill. The widely recognized HGI test for coal breakage may yield misleading results, particularly for multiple-banded bright and dull coal where the screening procedure used in sample preparation favors the testing of the hardest coal fraction. The work reported here indicates that the Pitt Mill, which grinds the whole coal in a single stage and which yields easily interpreted results, is an excellent candidate for testing coal pulverization characteristics including energy requirements and equipment wear. The measurements of the effects of coal characteristics on grinding energy and on media consumption have been used to estimate the cost of fine grinding in a Pitt Mill. The results, based on a conceptual level evaluation of grinding at the rate of 1 TPH, show that there are trade-offs possible between the cost of energy and cost of media consumption which involve choice of grinding media size. The use of fine-size grinding media to lower grinding energy and to increase throughput can be deceptive because the total cost of grinding must consider both energy and media consumption.

Jan 1, 1992

By John W. Scott

INTRODUCTION The design criteria for a particular concentration and dewatering project will provide the formal basis for design of the process, equipment and facilities. These criteria will specify the required capacities and operating schedules for the equipment, as well as the quantity and quality of the feed to be processed and products obtained. The general climatic and geographical conditions at the site, specific information on soil or rock conditions; and applicable design standards and codes will also be included. The design criteria will generally be based on an interpretation of testwork carried out on the particular ore and site, and will thus parallel in detail and completeness this testwork. As the project moves from the early conceptual phases through to final detailed design, the design criteria will be developed and become more detailed as information is generated and made available for use. The design criteria are critical to the design effort as the formal specification to the designer of what and how much is to be processed, what and how much is to be produced, and where and under what conditions. The actual design criteria will be a formal tabulation of the design basis information developed for the project in question. For a preliminary study, this may consist of a single page of data; for a feasibility study several pages and for a detailed design up to several hundred pages and multiple volumes. Depending on the complexity of the process and the level of detail included, each project will be unique to some degree. The design process for a project normally progresses from preliminary conceptual phases through to a final detailed design. The criteria used for the initial concepts are generally developed from rough data and preliminary testwork on the ore in question. Regardless, the plant throughput and products are defined, thus giving a scope and definition to the study phase. In some studies a range of throughputs may be analyzed in order to arrive at the most economically attractive size for the proposed operation. This optimum size is then used as the design throughput for the more detailed design phases. Similarly as more testwork results are available and the ore characteristics and process become more well defined a continuous updating of the design criteria is undertaken.

Jan 1, 1986

By Paul Chamberlin

Management has assorted roles to play, many of which are listed, that may call for consultant input. Consultants also play various roles, and some of these are discussed as well. The relationship between management and the consultant depends mainly on management's preparation for the assignment and on their monitoring during the assignment. Consultant costs are discussed briefly and suggestions for keeping consultant costs under control are given. In addition, some qualities of a good consultant are covered.

Jan 1, 2001

By P. Tanaskovic

This is presentation of a model which simplifies application of project management in control of the construction procedure of industrial units (mines, power stations etc). The model is made for further referrence of investors. The most demanding problem in large units is to find the best way of locating all activities within a network. The model uses term "line" (which refers to a construction unit) for a serie of activities which are to be sequentially executed (up to 1000 lines, each with 10-20 activities). The lines are coded in advance. Each line is described by a competent expert. Team of experts provide liason between lines on the basis of computer drawings. The method proved to be extremely effective. In order to provide smooth monitoring at all management levels, graphic documentation is given at 4 levels. The initial level is the third one, made based on input data (more than lo listings per one drawing). By condensation of activities along one line, another level is obtainable. Grouping of lines gives the first level (1-2 listing) for the highest management level. More detailed information is given for a limited (shorter) period at the forth level for the purposes of operational management. Each activity has three phases: prior to contracting, post contracting and accomplishment. All phases are presented at all levels, which enables investor to be continually well informed about construction advancement. Model is written in FORTRAN language. Programs comprise: maintenance of data base, calculation of time and costs and elaboration of graphic and other documentation.

Jan 1, 1986

By L. Xu, R. Bhaskar

While a NIOSH accepted procedure exists for determination of quartz in the respirable dust samples from coal mines, no specific procedure has been defined for quartz determination in bulk samples. In this study, the effect of particle size on the estimation of quartz using the infrared technique was evaluated. Several laboratory tests were performed to determine the dependence of the infrared absorbance peak height on the different sizes of quartz particles. The significant dependence observed between quartz particle size and the measured peak height indicates the potential for erroneous interpretation of the quartz in bulk samples depending on how the samples are prepared. A procedure to reduce the effect of size in the determination of the quartz content is suggested.

Jan 1, 1994

By J. B. Rubinstein, V. J. Badenicov, S. T. Hall

A simulation technique of the flotation process and models for the solution of various problems are developed. A modular model of column flotation is constructed taking into account the kinetic relationship of the process and the hydrodynamic regime in the cell. Based on this, a technique of calculating the column parameters based on laboratory tests is developed (scaling-up), and applied for calcetest results is developed (scaling-up), and applied for calculating the design of commercial-scale columns.

Jan 1, 1996

By Harrison R. Cooper

INTRODUCTION AND SUMMARY Phosphate matrix beneficiation is the process of providing a mineral product suitable for downstream chemical processing to yield high analysis chemical fertil- zers. Extraneous contaminants, clays and gangue solids, are separated by screening and flotation. Reject materials always carry with them some phosphate mineral values, however. A continuing objective is minimizing phosphate losses discarded with tailings as a principle factor in maintaining beneficiation efficiency. The quest for efficiency, and improved productivity, during beneficiation is hampered by disturbances arising from among the following: o Natural variance of phosphate deposit compositions, o Minimal control over managing ore matrix supply to the plants, o Screening and flotation mechanical upsets and inefficiencies. Production personnel, in recognizing these factors, attempt corrections for changed process conditions. This response usually has limited effect. Efforts of product- ion personnel to correct for upsets of the process may often diminish efficiencies rather than improve them. Lack of prompt data for analysis of process streams is an important contributing cause of inefficient operation. Discussion in this paper examines methods for improved process control in Florida phosphate beneficiation with particular emphasis on use of on-stream analysis to aid gaining productivity. The Florida Institute of Phosphate Research has supported demonstration of on-stream analysis applicable to improved process control. Concurrently, work is proceeding world-wide in the phosphate industry toward practical on-line analysis technology. Table 1 summarizes viable methods for real-time analysis data as result of work by individual companies and research organizations. A recently completed investigation (sponsored by the Florida Institute of Phosphate Research) of beneficiation efficiency was carried out in two Florida beneficiation plants using a newly developed on-stream analyzer for phosphorus (1). BPL measurements were taken at frequent intervals over two to three weeks of routine operation. Grades are expressed in "BPL", with one BPL, or bone phosphate of lime unit, equal to 0.46 P^Y2^YO^Y5^Y. The time series of feed and tailing BPL data were evaluated by statistical procedures. Results show avoidable losses can be five per cent or greater of mineral values in feed. Use of modern process control methods in Florida phosphate mining began several years ago (2, 3). Benefits of stabilizing control used in one of the two plants where data were collected for the investigation, in comparison to manual control in the other, are outlined. Process control technology developments reported from European and South African phosphate mining operations are also noted (4, 5). It is now well accepted that advanced control techniques can increase beneficiation productivity by better management of losses. However, to make advanced control effective, real-time measurements are needed of feed and tailings BPL as well as mass flow rates.

Jan 1, 1993

By Michael J. Virnig, Kathryn C. Sole, Murdoch W. MacKenzie, Michael R. Davis

A solvent-extraction process has been developed for the removal of copper cyanide complexes from aqueous copper/gold cyanide solutions formed in gold-recovery circuits that treat ores containing cyanide-soluble copper. The process uses LIX® 7820, one of the LIX® 7800 reagent series developed by Henkel. It is based on a mixture of Aliquat® 336, a quaternary amine, modified with an alkylphenol, 4--nonylphenol. Extraction and stripping data for the base metal cyanides and thiocyanate are presented. Methods for the recove1y of copper and cyanide from the upgraded strip liquor are reviewed. A flowsheet based on this chemistry and a preliminary economic evaluation of a solvent-extraction circuit combined with the cyanide-recovery process developed by Metallgesellschaft Natural Resources (MNR) are also presented.

Jan 1, 1999

By G. Van Weert

Oxygen transfer from dispersed air in agitated slurries represents an important unit operation in the minerals processing industry. Gold leaching, iron precipitation and especially bio-oxidation come readily to mind. However, little engineering information is available on the variations between impeller types on such O2 transfer. Engineering literature on the subject, i.e. information which relates slurry density and energy input to O2 transfer, is reviewed and compared to current experimental work. The latter was carried out with minus 50 micron sand/water slurries in a 64 I laboratory tank of standard proportions, equipped with a variable speed drive with torque meter. A standard Rushton turbine and a specifically sized A315 were compared. Results confirm an increasing impairment of O2 transfer with increasing slurry density for both impellers. The volumetric mass transfer coefficient, k,a, in a 10 vol. % slurry shows a decrease of 30% compared to the k,a in water. At 20 vol. % sand this decrease is near 50 %, depending somewhat on superficial gas velocities. Power efficiency, i.e. the kg O2/kWh, decreases about 25 % more rapidly for the Rushton turbine than for the A315 with the addition of sand. However, for equivalent O2 transfer the Rushton turbine was more efficient in this work. Experimental results are presented and their significance for slurry bio-oxidation discussed.

Jan 1, 1996

Little knowledge is available that considers the effects of continuous miner position on the possible respirable dust exposure of the remote mining-machine operator. Such information could be very useful for increasing the awareness of the remote operator as to those parts of an extended cut that generate higher levels of respirable dust. This data could be used to develop guidelines for positioning the remote operator to reduce his potential exposure. This work details the effects of continuous miner position on dust levels measured on the machine and at the remote continuous miner operator location.

Jan 1, 2000