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At periodic intervals-typically at the end of each month, quarter, and year- the accounting department in each division of a company distributes a set of reports to the division's managers. These reports describe the financial performance of the division and its major departments over the time period. They identify the revenues generated from the division's products and the costs incurred in their production. The results from individual departments are combined to determine divisional results, and the results from individual divisions are in turn consolidated to determine the results for the overall corporation. Cost reports for each of these activities show actual amounts, budgeted amounts, and the differences between the two. This reporting is carried out for the individual period and for the year to date.

Jan 1, 1999

By Kerstin Malmqvist

Simulation technique has been used for a feasibility study of a deep exploration project for massive, sulphides in an old mining district, the Skellefte field. An interactive computerized mathematical model of an ore field and a drilling procedure has been constructed. It is possible to represent varying geological structures. The model also takes in consideration economical factors such as drilling costs and ore values. On this model Monte Carlo simulations and probability calculations are done in order to estimate the outcome of different drilling strategies under varying geological assumptions. Under the specific conditions of the well known Skellefte field, it is found to be possible to even calibrate the mathematical model.

Jan 1, 1979

By Irwin R. Higgins, Richard S. Dennis

Acid recovery employs ion exchange resin as an adsorption media for the separation of inorganic acids from mixtures of acids and their metallic salts. This technology has been used to treat spent pickling and plating liquors to recover acid for reuse in the bath and to reduce waste acid neutralization costs. Acid recovery can also be used for electrolyte treatment to facilitate valuable metal recovery and to improve product quality. Conventional fixed bed ion exchange (I-X) systems are impractical for acid recovery because of complex control design and large resin inventories needed to process strong acid concentrations. TETRA'S CCIX™ continuous I-X contactor has been used successfully in a simple, continuous operating mode to separate acid from its salt. Efficient separation is enhanced by refluxing which allows acid to be produced as a salt-free product at nearly its original strength. Continuous treatment also recovers heat to the bath and improves metal quality due to consistent acid quality.

Jan 1, 1995

By Derek G. Cieplinski

Regenerative conveyors with complex conveyor profiles place unusually stringent demands on the starting drive control. Depending on the nature of the conveyor loading, the drive must either provide a positive driving force to overcome conveyor friction and gravitational forces if the belt is empty or the inclined sections are loaded, or it must provide a retarding force to resist the gravitational load of decline sections to control the acceleration rate. This paper discusses the requirements of regenerative conveyors, reviews the working principals of fluid couplings, and examines their interaction by means of a case study of a 1700 m long regenerative conveyor utilizing a fluid coupling with a proportional brake control to provide controlled starting and stopping under all load conditions.

Jan 1, 1993

By A. F. Klebanov, K. N. Trubetskoy, M. Yu Khoudine, V. L. Postnikov

The information system of monitoring of mine receive layouts is being created In the "ROSUGOL" Company for the prompt analysis of the state-of-the-art of mining operations at under- ground and open cast mines of the Company, rapid and effective decision-making and elaboration of recommendations on the basic directions of enterprise development. The data bank storing the digital mapping and attributive information describing the actual background of mining operations at the enterprises of the Company is the core of the system. The Oracle database management system and the ARC1 INFO geographic information system have been chosen as basic software packages for the Project realisation. The updating of the information will be performed on a regular basis via the transmission of actual digital data on under- ground and open cast mine layouts In ARCIINFO conversion to the central office of the "ROSUGOL" in Moscow. Centralised storage of digital mapping and attributive data, database administration and navigation is effected with the Oracle software package. Access to the data in the operation mode with an interactive display map will be effected with the use of the local computer net of the "ROSUGOL."

Jan 1, 1996

By Kenneth N. Han, Jianshe Liu

Various techniques used in the removal of metal ions from effluent streams have been reviewed. These techniques include recovery of metals by biological treatment, chelating agents, adsorption, ion- exchange and chemical precipitation. The main thrust of this paper however, is concerned with the removal of cadmium and zinc ions from the solution by adsorption utilizing liquid fluidized beds. The bed particles used were silica of 150x200 mesh. The range of the concentration of these ions studied was 10-3 to 10-5 M. Important variables examined included flow rate, concentration of metal ions and amount of bed particles. A mathematical model describing the concentration profile of metal ions in the axial direction in liquid fluidized beds has been developed. The equation of continuity was solved numerically and the results were used to predict the recovery of metal ions in fluidized beds.

Jan 1, 1992

By J. L. Fuentes

The so called 'SISCOM' is a General Purpose, microprocessor-based Monitoring and Control System, developed by AITEMIN to meet the requirements of Spanish Mining Industry in - the field of automation and data -transmission. Typical applications -are automatic control of pumps, compressors, fans and conveyors, as well as environmental monitoring and production monitoring. In relation with the last, the - System has been succesfully installed in a full section roadheader and in a mechanised steep coal face. In both cases, the main objective is to get information about running times, down times and causes, -and monitoring of other important parameters such as ventilation, methane content, power consumption..etc. Measurements concerning the face behaviour from a geomechanical point of view are also monitored. These are different pressures and stresses. All data is transmitted to the - surface and on-line analysed by a -desk-top microcomputer. The paper shows the system structure and the requirements that have - been considered on its design. Attention is given to the mechanical data acquisition problem, involving special development of some transducers. The information provided by the surface microcomputer is shown and its utility discussed.

Jan 1, 1986

By Johann Engelbrecht, Stéfan de Bruyn, Petrus van den Heever

A system for the on-stream X-ray diffractometric determination of mineral phases in slurries was developed in response to the mining industry's need for process control during the beneficiation of industrial minerals. The instrumentation for and results from testwork conducted at a phosphate rock beneficiation plant in Florida are discussed. Results show that the concentrations of the minerals apatite (var. francolite) and quartz can be accurately determined every few minutes, so that adjustments to the flotation circuit can be timeously executed from the control room. The on-stream measurements can ultimately be integrated into an automated plant control strategy. Estimates of savings on reagent and staffing costs, as well as the benefits from consistent grades and greater recoveries, have shown that the investment in such a system could often be recovered in less than a year.

Jan 1, 1999

By Mark J. Schultz, William J. Francart, Gary J. Wirth

Atmospheric Monitoring Systems (AMS) utilizing carbon monoxide sensors have demonstrated their superiority over thermal type fire sensors for early fire detection in underground coal mines. After proving their capability and dependability throughout the 1980's, systems are now evolving and applying new technologies to enhance their effectiveness and reliability. The use of AMS in coal mines which utilize diesel equipment presents unique obstacles. Exhaust gases from diesel equipment not only raise mine ambient CO readings, but also cause numerous nuisance alarms. Both of these conditions reduce the effectiveness of the AMS. New technologies, such as discriminating devices, smoke detectors, and time delays, as well as administrative controls, have been developed and are being utilized to help reduce nuisance alarms produced by the diesel exhaust. This paper will discuss these technologies and administrative controls which are being utilized in coal mines to enhance the effectiveness of the Atmospheric Monitoring Systems. Reference to specific products does not imply endorsement by the Mine Safety and Health Administration.

Jan 1, 1995

By G. A. Munoz, J. D. Miller

Gold leaching of an auriferous pyrite ore from the Portovelo deposit in Ecuador indicates that noncyanide leaching systems, such as thiocyanate and thiourea, are not as effective as the traditional cyanide system. For example, whereas approximately 95% of the gold can be leached from the ore with cyanide, only about 50% gold dissolution can be achieved with a thiocyanate leaching system. Electrochemical measurements indicate that gold is not cathodically protected by pyrite in these systems. Based on the results of preliminary diagnostic experiments, it appears that gold dissolution in thiocyanate and thiourea systems is limited by passivation due to the formation of either elemental sulfur or sulfur compounds on the gold surface.

Jan 1, 2000

By F. Djahanguiri

The US Bureau of Mines con¬ducted research on underground stope leaching of metalliferous ores. Leaching underground would minimize the environmental impact of ore processing on the surface and would maximize minable reserves. An important aspect of this process is the minimization of pregnant solution losses and groundwater contamination by leach solutions. Bulkhead design and construction are important issues for solution control and stope-leaching economics. A reinforced-concrete bulkhead was designed, constructed and tested for solution control in an underground mine near Idaho Springs, CO. This paper presents the bulkhead-design methodology and construction procedure.

Jan 1, 1997

By A. R. Zambrano

Equations for power draft, capacity and work input for predicting the performance of industrial grinding mills are derived based on torque measurements using 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 (Wi) times a particle size function. It is proposed that these laws are only particular cases of more general expressions having the particle size function raised to an exponent, i.e., the work exponent (We). Case studies illustrate the excellent prediction of the Wi - We models compared to the three mentioned laws, and, from the data, the corresponding general mill-sizing equation is derived. Key words: Grinding mills, Comminution, Work index, Mill sizing

Jan 1, 2003

By Alec G. Richardson, S. H. Chiang, Ralph W. Lai, McMahan L. Gray

The potential of coal cleaning by selective agglomeration was examined for a Pittsburgh seam bituminous coal using isooctane as an agglomerating liquid. The effects of particle size, pH, degree of mixing, and dosage of isooctane on the pyrite and mineral matter removal from finely ground coals were investigated. The role of shear-enhanced-hydrophobic-association in the flocculation of fine particles was examined. The degree of liberation of pyrite from coal at different grinds was examined using an automated petrographic image analyzer. The effect of dispersant on slurry rheology during grinding was studied. The results indicate that over 95 percent of the pyritic sulfur can be removed from the coal. Final products containing less than 0.9 percent ash at a combustible recovery in excess of 90 percent have been obtained with multiple stages of cleaning.

Jan 1, 1989

By Pierre Mousset-Jones, Felipe Calizaya, Malcolm J. McPherson

The algorithm presented in this study determines the combination of fans that provide all working districts of a mine with predefined airflows at the minimum operating cost. It is based on an existing ventilation simulator, VNETPC, and a set of linear equations associating fan pressures and the added resistance of regulators. Two assumptions are undertaken: (1) fan locations are predetermined and (2) the number of working districts is equal to or greater than the number of fans. By means of this algorithm, the optimal solution to an n fan ventilation system may be found after n + 1 simulation runs.

Jan 1, 1987

By Lei Zhang, P. Somasundara

The beneficiation of phosphate is complicated due to its sparingly soluble nature. The surface proper- ties of phosphate and associated minerals are determined, in addition to the ionic composition of the solution, by the dissolution of the lattice ions of the minerals and subsequent complexation, hydrolysis, adsorption, and precipitation of the dissolved species. These, in turn, are influenced by the pretreatment of the mineral. These complex interactions determine the interfacial properties of phosphate and associated minerals and thereby the efficiency of beneficiation processes such as flotation and flocculation. Under- standing of the chemistry involved in such systems is helpful to develop the optimum beneficiation schemes. It is shown that desired selectivity can be achieved by controlling the chemistry of the systems. More important, the need to conduct development tests under plant conditions is clearly demonstrated.

Jan 1, 1999

By S. Mason

Many organizations are realizing that continual improvement in health and safety relies on addressing the potential for various forms of human error. Of these, rule violations are often the most frequent form associated with accidents. These occur when an individual (or individuals) deliberately contravenes established and known safety rules. They have been associated with up to 90% of the accidents and other incidents in some industries, and yet they rarely receive the systematic attention they deserve in the promotion of safety. This paper presents underlying motives that cause violations. These can vary significantly from mine to mine and from job to job. Managers need some measure of the attitudes of the violators to determine the underlying motives behind the violations if they are to determine effective strategies for promoting safe behavior. Questionnaires form the starting point to address attitudes and the motives behind rule violations. The choice of the most suitable questionnaire, how- ever, will vary from organization to organization. Guidelines on the choice of questionnaire are offered.

Jan 1, 2000

By Wen L. Cai

This paper examines the effects of different block dimensions and cone bases on the economic open pit limit design based on case studies on a coal deposit consisted of two west- east elongated, near vertical thin seams starting with a base model dimension of 200x170x50 (NX*NY*NZ) with a block dimension of 10mx5mx4m (DX*DY*DZ), the blocks were combined along easting, northing and elevation directions. Two cone bases were used, one with a base radius of 10 meters, the other with a base radius of 0. Two pit design algorithms, one is the floating cone algorithm, the other is an optimum algorithm, were used to see which one of the two pit design algorithms is more sensitive to block dimension and cone base variations. The results are presented and analyzed.

Jan 1, 1992

By C. H. Rawlins

The total amount of ferrous slag generated in the U.S. is about one-third the amount of iron ore mined, thus ferrous slag can be considered a significant mineral body for processing. Steelmaking slag contains up to 30 wt.% metal of which only the >25mm fraction is commonly recovered. A grinding study was conducted of BOF, EAF, and LMF slags using the Bond Work Index method to determine grindability to 106µm. Work Index values obtained were 13.8-24.9 kWh/ST, depending upon the slag type and composition. Steel particles were magnetically recovered from the crushed and ground samples for size-by-size analysis, yielding up to 18 wt.% of the slag weight recovered as magnetic. The recovered material, as characterized by inert gas melting, was found to be 61-96 wt.% metallic.

Jan 1, 2008

By Eddy J. Jacques

When the automatic control of a ventilation process is considered, and supervising expert systems need to be designed, an important problem to address is: what will be the optimal set points of the regulators that should meet a certain number of independently formulated requirements, distributed over a ventilation network? The set of these requirements, expressed in terms of air flow quantities or differential pressures in certain airways, need not be consistent. Their number is not limited by the number of available regulators, nor by their nature, i.e. passive or active. Moreover, they may be subject to upper or lower limit values. The method described here addresses this problem and tries to provide a tool that should allow to calculate the set points of all the regulators as a global and optimal solution with respect to this set of distributed requirements. The pure mathematical developments in this paper are kept as short as possible in order to allow more room for the description of a relevant example.

Jan 1, 1991

By J. W. Leonard, C. L. Jiang, B. K. Parekh, X. H. Wang

The selective depression of pyrite from the Kentucky No. 9 coal seam was systematically examined using various kinds of inorganic and organic chemicals. Most of the organic chemicals tested showed little selectivity in pyrite depression. It was found that both orthophosphate and pyrophosphate were effective for the selective depression of coal pyrite in coal flotation using fuel oil as a collector. At substantially low concentrations of pyrophosphate, the flotation of coal pyrite was completely depressed over a wide pH range, while the coal flotation remained unaffected. The mechanism of the selective depression of pyrite by phosphates was explained with the help of thermodynamic calculations of iron-phosphate-water systems and zeta-potential measurements. It was shown that pyrophosphate reacts strongly with the iron ions of pyrite to form stable hydrophilic iron pyrophosphate complexes on pyrite surfaces.

Jan 1, 1999