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By R. L. Wiegel, G. R. Oswald

The processors of Florida phosphate rock face constraints similar to those of other mineral operations--leaner ore, more complex treatment schemes and a product which sells for a penny a pound. IMC Fertilizer is a dominant producer in this market with its current operation of five processing plants. An emphasis by their management in maintaining and improving plant performance has continued unabated for some 15 years. This has resulted in a commitment to the importance of routine automatic sampling of product and in process streams, the generation of reliable assay and size distribution data, the accurate measurement of process flows, and the computerized "rendering" of this information into weekly and monthly material balances which provide consistent measures of process performance. In addition, there has been a parallel program to monitor and improve the performance of flotation reagents and to evaluate process modifications or changes in equipment. This paper will describe the evaluation techniques that have evolved over this period and indicate how the historical data base is used to identify plant problems early and help in their solution.

Jan 1, 1991

By Munson R. McKinney, Bryan A. Slim

To date some 1,000 exploration targets (by way of adits, mine dumps, shafts, outcrops and unstoped mine areas) have so far been identified using an interactive data base system to query a digital data base comprising topographic, cadastral geological and mine components developed as a compilation of old plans, records, surveys and recently flown aerial photography. The exploration targets are intended for early follow-up as part of a 1987 exploration programme to investigate the reserve potential of the former producing property located in southern Utah. Of further interest is the unscrambling of old mine plans to provide drill targets for investigation of unstoped reserves with one target being a possible 800,000 tons in part of the lower workings. The project site encompasses about 3,200 acres of mainly patented lode claims covering most of the claims and mines of the Gold Mountain mining district formed in 1889. Turn of the century mining saw several mines operating whose total production was at least 143,000 oz. gold and 460,000 oz. silver from steeply dipping veins up to 20 ft. or more in thickness.

Jan 1, 1987

By J. J. Moore

Combustion synthesis, or self-propagating high-temperature synthesis (SHS), reaction systems are discussed with respect to thermodynamics and kinetics. In particular, the effect of the process parameters, e.g. particle size, [All] ignition and combustion temperatures, on these self-sustaining reactions is discussed. Combustion theory is used to investigate the effect of the overall actuation energy of the SHS reaction on the combustion front propagation rate and in obtaining a clearer understanding of the transition from stable to unstable propagation. Finally, examples of the application of combustion synthesis to advanced materials processes are made, in particular the synthesis of Ni-Ti-X intermetallic shape memory alloys, TiC-AI2O3 and ZrB2-AI203 ceramic composite materials.

Jan 1, 1992

By J. Herbst, K. Fallenius, G. Poling

Since 1970 a new series of pneumo-mechanical flotation machines has been developed by Outokumpu Oy. The cells have a completely new type of mechanism based on a recently-developed theory of conditions necessary for dispersion of large amounts of air. The mechanism was developed in 3 cu m cells and scaled to 16 cu m cells. Rotor and stator description, scale-up theory, and practical experience with the 16 cu m cell are presented.

Jan 1, 1976

By M. J. Virnig, C. P. J. Van Vuuren, A. J. Botha

The Zadra, AARL and organic elution processes and variations of them are presently widely used to recover gold from activated carbon. Despite this the study of the kinetics of elution have received relatively little attention. It is the aim of this study to investigate the rate processes taking place during elution in both inorganic and organic solutions. Batch adsorption and elution rate and equilibrium experiments were performed. The spatial concentration of gold inside carbon particles at various stages of the adsorption and elution processes were measured with a scanning electron microscope using an image analyzer to control and manage the micro-analysis data. The activated carbon particles exhibited film and intra-particle mass transfer rate- controlled behaviour during adsorption in a caustic aqueous solution at 95°C. Elutions in the aqueous caustic acetone solution at 30°C and the caustic aqueous solution at 95°C were unaffected by change in stirring rate. Elution was modelled by desorption reaction rate-control at the outer surface of the carbon particle. Adsorption and elution isotherms under duplicated solution conditions showed reasonable agreement for the inorganic solution and a large disparity for the organic solution.

Jan 1, 1993

By Bruce W. Cavender, Brian L. Granger

The leaching characteristics of non-homogeneous ores have traditionally been difficult to assess in laboratory tests. A result of the large sample size necessary to ensure representativity, this difficulty is most acute for ores containing nuggets or other irregular occurrences of precious minerals. Consequently, small-scale leaching tests are often regarded as indicative rather than conclusive. The predictive nature of leaching tests can be improved by applying the experimental design concepts of blocking and randomization. In the case of column leaching, experimental 'blocks" are constructed with the same number of columns as there are separate test conditions. These blocks are treated identically throughout the test, with differences between columns within each block being the variables of interest. To maximize the uniformity of the blocks, randomization procedures are employed in the preparation of the sample and conduct of the test. The initial ore sample is screened and individual column charges composited from randomly selected increments from each size fraction. The leaching order, daily solution analyses, and processing of leach residues are similarly randomized. The observed differences in leaching performance between the columns in each block are compared to determine the over-all outcome of the test. A statistical analysis using t distributions gives a quantitative measure of the reproducibility of the outcome.

Jan 1, 1995

By B. Ceccarelli

Many public domain programs useful in mining engineering, e.g., MULSIM, DZTAB, and EXPAREA, require tedious data input and generate pages and pages of printed output. To eliminate the tedium and to enhance the output, ETI U.S., Inc. developed GEM, Graphics for Engineering and Mining, a collection of application programs and underlying interface tools for VAX/VMS computers. This paper presents an example of how an application program in GEM enhances a specific public domain program. It describes how GEM provides automated graphics assisted input and output. The paper describes how this program uses the GEM User Interface: the 3D GKS device independent graphics, server and drivers, various mining, mathematical and statistical algorithms, the means of handling graphics, data including IGES, and the foreign language interface.

Jan 1, 1992

By R. Larry Davis

Over the past decade there has been a continual decrease in domestic oil reserves accompanied by a sharp increase in the demand for energy. Even with increased imports of foreign oil, the energy demand has not been met. This has forced many users to turn to substitute fuels. Of the many substitute fuels available most users are turning to and creating an increased demand for low sulfur coal. Because of the increased demand for low sulfur coal as well as the inherent problems in producing eastern coal, many producers have turned their attention to the large deposits of low sulfur coal in the western United States. Western coal mining is, however, not without its problems such as high moisture content, high ash content, highly variable sulfur content, multiple seams, and/or pitching seams. It is to aid in the solution of these problems that this chapter is directed.

Jan 1, 1979

By Jim M. Johnson

INTRODUCTION The facility water balance and maintenance of sufficient excess storage volume in the solution control system are often amongst the most critical facets of design and operation of heap leach facilities in cold, snowy climates. The purpose of this paper is to summarize and discuss climatic and operational factors which have a significant impact on heap leach water balance evaluations in high snowfall climates. Example water balance simulations are presented for proposed heap leach projects located in areas subject to high snowfall in the northwestern United States. The climatic data input to these simulations represent both net evaporative and net precipitation climates. FACTORS AFFECTING WATER BALANCE EVALUATIONS The combined effects of seasonal operations, re1atively low evaporative losses, and potentially large inflows to the solution control system from snowpack and spring storms require an enhanced awareness of the factors which impact facility water balance. Unlike operations at mines in more arid climates, seasonal excess water rather than a shortage of make-up water is the rule. A thorough understanding of a number of factors, including regulatory constraints, climatic influences, and impact of operating philosophy and techniques, is critical to successful development of an incident-free heap leach operation under high snowfall climatic conditions. A process water circuit schematic for a typical heap leach operation is shown on Figure 1.

Jan 1, 1988

By Van Zyl Brink

A longwall-based coal mine in Australia, referred to in this paper as AusMine Colliery, experienced windblasts resulting from goaf falls. Windblasts were the cause of serious injuries and threatened the continued operation of the mine. A microseismic early warning system was installed and a significant success rate in providing early warning of large roof instability resulting in high velocity windblasts, has been achieved. Early warning of goafing is accepted as an operational tool on the mine. Severe demands are placed on the operator in terms of 'real time' interpretation. The development of an expert system allowed for a probabilistic approach to achieve automatic alarms. This paper will quantify the success, failure and false alarm rates achieved by manual operation and automatic expert system-based decisions making, respectively.

Jan 1, 2002

By Michael J. Sapko, Robert A. Cortese

A flame powered trigger device has been developed to explosively activate suppression barriers to quench gas and coal dust explosions. The important feature of the device is a silicon solar panel, which collects 0.3 p to 1.1 D wavelength radiation from the developing explosion, and generates electrical energy to initiate a detonator, which in turn causes the rapid explosive release of an extinguishing agent into the advancing flame front. Solar panels that are rated to produce 20 w of electrical power when exposed to the sun light are producing about 200 w when exposed to full-scale dust explosion propagating in the U.S. Bureau of Mines' Lake Lynn Experimental Mine. The solar panel is electrically isolated from the detonator by a pressure sensitive switch until the arrival of the precursor pressure pulse, which always precedes a deflagration. This combination of pressure arming and flame powered photo generator prevents false barrier activation and requires no external power supply.

Jan 1, 1991

By K. M. Belingheri, M. E. Smith

Pinson Mining Co. operates a conventional mill and two heap leach operations in north-central Nevada. The latest of these heap leach operations, the Preble project, is a low-grade, low-tonnage property made profitable through several innovative capital reduction techniques. Rapid return on investment was a prime factor in design. To facilitate this, fast-track design and construction techniques were employed. The project is a seasonal 1.5 kt/d (1 700 stpd) crush/agglomerate heap leach plant using both clay and plastic leach pads. Construction and startup were achieved through cooperative arrangements between local contractors and in-house construction personnel, with few items put out to bid. An interactive approach to design minimized lost time and construction costs.

Jan 1, 1987

By Robert Snow, Yingxue Yu, Patrick Zhang

The FIPR/SAPR process is FIPR's third approach to develop a viable alternative to the Crago "Double Float" process for phosphate flotation. SAPR stands for Single-collector, All-anionic Phosphate Recovery. The FIPR/SAPR process - offers a universal flowsheet for any anionic reagent system and flotation feed of varying sizes. For an unsized or fine flotation feed, the FIPR/SAPR process consists of the following steps: 1) high-solids conditioning with an anionic collector; 2) anionic rougher flotation, with the rougher concentrate sized at 48 (or 65) mesh and the +48 mesh recovered as a final product; and 3) cleaning flotation of the -48 mesh fraction from step 2. In a variation of step 2, the rougher concentrate from the first two cells may be collected as a final product, and the rougher concentrate from the last two cells sized at 48 or 65 mesh. The new process was tested with a blend of anionic collectors, achieving single-digit Insol at 85 + % recoveries.

Jan 1, 2002

By W. M. Schafer, C. F. Luckay, D. A. King

Monitoring devices have been installed at several mine sites to assess the potential for the development of acid rock drainage (ARD) in waste rock, spent ore and tailings material. In addition, instrumentation has been designed for monitoring changes in water quality in pit lakes. These devices monitor temperature, oxygen, water movement and water chemistry in the waste rock pile. This information can be used to evaluate the current and future ARD risks and the effectiveness of caps and covers. The information can also be used in the design of other reclamation strategies that limit ARD development. The instrumentation includes nested thermistors and oxygen sensing ports, neutron access tubes, heat dissipation units (HDUs) and lysimeters. Many of the monitoring devices can be linked to a data logger and telemetry systems, enabling monitoring data to be downloaded from the office.

Jan 1, 1999

By S. A. K. Forson, Newton A. Amegbey

In order to investigate production decline in Tarkwa Goldfields Ltd., located in a tropical rain forest, amongst other areas, a health survey was conducted with the aim to see 1. The health status of the workers. 2. Which parameters carry the most information about the health situation and which of them can be applied easily during screening programmes. 3. What steps could be taken to improve the situation. In all 249 workers were investigated. A non-invasive method involving taking of body weight and arterial blood pressure was used. All subjects were required to answer a questionaire. Emphasis was placed on the history of malaria and diarrhoea within the last six months. Both management and workers co-operated fully. Another set of 110 workers from a neighbouring tyre factory were also investigated for control. Among the underground workers, the percentage body weight loss during a shift increased with decreasing body weight. Dehydration levels could be as much as 4 to 5% of body weight. This could be attributed to the fact that workers took insufficient or no water during the shift. The health status of the mine workers was generally poor and in our opinion malnutrition combined with malaria severely threatens the health and well-being of the workers. Hypertension is also a problem. An improvement in production is intimately linked with the well-being of the workers.

Jan 1, 1989

By A. K. Bakshi, Komar S. Kawatra

A plant trial of a new on-line pressure vessel rheometer for slurries, developed at Michigan Technological University, was carried out at a nearby copper concentrator. The rheometer measured the flow curves (shear stress vs. shear rate) of chalcocite slurries. Viscosity of non-Newtonian slurries changes with shear rate and so, for such slurries viscosity measurement at a single shear rate (often seen in the literature for grinding and classification studies) cannot be correlated to process performance. For these slurries, viscosity at various shear rates can be measured from flow curves generated by the pressure vessel rheometer. Other rheological properties, such as flow type and yield stress can be determined by this rheometer to better characterize the slurries. The slurry at the copper concentrator consisted of ground chalcocite ore. The solids content in the slurry varied between 30-60 % by weight. Top size of the particles was 125 micron, and 80% passing size was 34 micron. Measurements by the pressure vessel rheometer showed that most of the slurries had pseudoplastic flow at shear rates below -3000 sec-l, where the viscosity of the slurry decreased with increase in shear rate. Above -3000 sec-l, like a Newtonian fluid, the viscosity of the slurry remained steady. Flow curves and viscosity from the pressure vessel rheometer were verified with a Brookfield viscometer and a vibrating sphere viscometer, and the results were found to be accurate.

Jan 1, 1997

By John A. Ferguson

John Ferguson of Phelps Dodge provides us with a case study of how his company approaches its computing and hardware decisions. Senior management is the target audience for this contribution which discusses computer employment strategy at Phelps Dodge and how it may differ from the practices followed by other companies. The computer professional is well advised to read this subsection also to gain insight into the way in which management looks at computers in support of company operations. The following pages take us through a progression of developments and expectations brought about by the computer: the tremendous versatility of this new tool and its swift development; the widespread changes and problems it introduced; the new and revolutionary management theories it prompted and the widely supported centralized service concept it introduced to information processing. It continues with a discussion of Phelps Dodge's early experience, its ,operating environment, and its strategy development-attention to operating units and later headquarters with stress on service needs of users. It concludes that for computing to be effective it must fit in with the bay in which the company operates and must be sensitive to the needs of the people it serves.

Jan 1, 1979

During 1997-2001, an EC funded project investigated the environmental consequences of the use of industrial waste and sewage sludge based artificial top soils (ATS) in rehabilitating large coalmine waste dumps in the Saar region of Germany. Both the laboratory leaching tests and field lysimeter data analysis carried out by the research partners have shown that the amount of dissolved heavy metals in the leachate was low, and generally below the regulatory limits. However, the dissolved amount of nutrients, especially mineral nitrogen, was found to be relatively high. The hydrological properties of waste rocks and ATS mixtures were established through history matching of the laboratory column tests and the field measurements. 1D column models and 3D field models were used to numerically simulate pollutant transport at the ATS rehabilitated waste dumps. This paper presents the findings of the numerical modelling research carried out for the characterisation of hydrological and pollutant transport properties of rehabilitated coalmine waste dumps in the Saar coalfield.

Jan 1, 2003

By A. Zorychta, T. Cyrul, Z. Kleczek

INTRODUCTION Underground mining causes disturbances of the primary state of stresses. Resulting from those disturbances a loss of stability of rocks that surround excavation may occur interrupting the production and creating life danger for the personnel. One of the manifestations of such an instability is a rock burst phenomenon which mainly occurs at great depths. From the mechanical mint of view the rock burst is a loss of stability /Filcek et a1.,1984; Pietuchow and Linkow, 1976/ due to : - quasi-static stress changes in the surrounding rocks; we will call it s seam burst , - dynamic stress changes in the surrounding rocks caused by rock shocks ; we will call it roof burst. Possibility of the rock burst occurrence Is uniquely determined by the state of stresses existing in the rock mass. In the following sections of the paper we will consider different aspects of this question. Moreover distributions of displacements and failure criteria for a coal seam at longwall mining will be defined. STATEMENT OF THE PROBLEM Determination of the vertical stresses and displacements resulting from longwail mining will be based on the Budryk’s idea of a stress wave /Salustowicz, 1955/. The idea originates from the analysis of a roof plate /beam/ resting on the deformable foundation /Sean/ and subjected to the cylindrical bending. Equation of the bending lice uniquely defines vertical stresses and displacements which are induced in the seam. The equation will account only the shear force effect. Elimination of the bending moment has been shown and discussed by Zorychta and Bcrecki /Zorychta, 1985; Borecki and

Jan 1, 1986

By Charles P. Lazzara, Alex C. Smith, Mark W. Ryan

The U.S. Bureau of Mines conducted a study to evaluate the effect of ventilation on the performance of automatic sprinkler systems in extinguishing wood crib fires. Experiments were conducted at airflows of 0, 0.76, 1.5, 2.5, and 4.1 m/s. Two experiments were conducted at each airflow, using 74° C fast response pendent sprinklers in one experiment and 74° C fast response horizontal sidewall sprinklers in the other experiment. In the experiments at airflows of 0 and 0.76 m/s, sprinklers were located directly above the fire and 2.4 m upstream and downstream of the fire. The sprinkler directly above the fire was the only sprinkler to operate with no discernible difference in the suppression capability of the pendent and horizontal sidewall sprinklers. In the experiments at airflows of 1.5 and 2.5 m/s, sprinklers were located directly above the fire and 2.4 and 4.8 m downstream of the fire. The sprinkler located 2.4 m downstream was the only sprinkler to operate with the horizontal sidewall sprinkler being more effective in extinguishing the wood crib fire. The average response times of the sprinklers at airflows of 0.76, 1.5, and 2.5 m/s were 3-1/2 times the average response time of the sprinklers at 0 m/s. The results of this study will help enhance the safety of the nation's miners.

Jan 1, 1993