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By T. Malterer, R. Adams

Peat has unique physical, chemical and biological properties. These include high porosity and water retention, high absorption and adsorption properties, and high buffering capacity. In addition, peat is a rich medium for microorganism activity. Peat has traditionally been used for horticultural purposes. However, in recent years, peat is increasingly being used for waste- treatment purposes. This paper reviews North American literature on the use of peat for waste-treatment applications. The literature indicated that peat has potential for use in the treatment of municipal and on-site effluents, for the removal of low concentrations of heavy metals and for the adsorption of liquid and gaseous hydrocarbon pollutants.

Jan 1, 1997

By Ugo Preti, Gianfranco Ferrara, Mark C. Williams, Thomas P. Meloy

Theoretical and experimental lockedness profile curves are the same when the model assumptions are met. They appear different because of the way the data is presented. Continuous theoretical lockedness profile curves present all the data, including the wings of the curves giving them the deep U-shaped configuration. Experimental lockedness profile curves, because of the measurement methods, are discretized, obscuring the wings. If the continuous theoretical curves are discretized, they are similar to the experimental curves. When a float sink test is used to measure an interval of locked particles, the integrated averaging of the separation process obscures the wings of the continuous theoretical curve. To disclose the wings with experimental data, narrow density or measurement intervals must be used.

Jan 1, 1992

By G. Mbuyi Kamba, J. Patigny, E. Jacques

Traverse anemometry is still widely used today. In this paper an investigation of the influence of three factors which are believed to contribute to the resulting error of the method, is reported. They are the shape of the traversing path, the size of the vane anemometers and the air velocity pattern. These factors are experimentally studied on a test facility developed specially for this purpose. Taking into account the results of 576 measurement sessions, as well as published information, some preliminary conclusions are drawn, and additional questions are raised.

Jan 1, 1993

By E. J. Miller

The Ventilation Branch is engaged in a project to determine if low level carbon monoxide monitors used for early detection and warning of fire in a coal mine conveyor belt entry can provide protection equivalent to that of thermally actuated point type heat sensors commonly used for fire detection. A series of tests were conducted to determine the required operating parameters, such as sensor spacing and alarm levels of detected carbon monoxide to provide equivalency between' these methods of fire detection. This report summarizes the results of these tests.

Jan 1, 1980

By T. Y. Yan

An effective elution technique has been developed for recovering uranium from ion exchange resins loaded in the carbonate leaching process. The procedure employs direct elution with acid. In comparison with conventional base elution, the procedure yields eluate of higher uranium concentration, results in a more complete elution, keeps the performance of the ion exchange resin at the fresh stage, reduces acid consumption, eliminates carbonate consumption, and reduces waste for disposal. The technique has been successfully demonstrated in the field and patented. It lends itself to commercialization.

Jan 1, 1987

Traditional finance theory recommends discounted cash flow (DCF) analysis as the tool to value mineral properties. Yet, the calculated values by this method are usually lower than the market value. Finance theory also advises us to develop an undeveloped project immediately if its net present value is positive. Most projects are, however, only developed when the economics are highly favorable. This paper uses insights from option-pricing theory to explain these divergences between market behavior and finance theory and presents simple modifications to discounted cash flow analyses that will lead them to produce correct valuation and development timing advice.

Jan 1, 1999

By W. V. Harper

The travel path of a freed radioactive particle in an aquifer must be estimated from a limited number of available samples. This paper discusses geostatistical methods that minimize the 'uncertainty' associated with the predicted hydrologic surfaces and the predicted travel path. However, any estimation method will produce a single smooth predicted path. This 'sensitivity' will he evaluated using a geostatistical simulation method. The techniques will be illustrated using published data from the Wolfcamp and Pennsylvanian aquifers in the northern Texas Panhandle.

Jan 1, 1990

By S. Svoronos, B. Moudgil, R. Stana, A. El-Midany

Due to their similar surface properties, it is not always easy to separate carbonate minerals from other salt type minerals by froth flotation. A particular example is the difficulty of separating dolomite impunities from phosphate minerals. Such challenging fundamental and practical problems have inspired several research efforts in various laboratories around the globe to find methods for economically removing the dolomite. However, a universal and cost effective process is not in commercial use. In this paper, a new process for separation of carbonate minerals (dolomite or calate) from other associated minerals is presented. Differential solubility of carbonates in slightly acidic solution is utilized to generate micro GO, bubbles at the carbonate mineral/ water interface. Particle (e.g., dolomite)/ bubble aggregates float to the surface leaving phosphate concentrate with low MgO content. Interestingly, up to 6.0 mm particles can be floated by such micro bubble/particle aggregates. Different sutface-active agents were tested to stabilize the bubbles. Results of these tests are presented and the mechanisms involved are discussed.

Jan 1, 2005

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 B. K. Parekh, W. M. Goldberger

Sludge obtained during the production of magnesium (Mg) from molten MgCl2 by electrolysis contains entrapped magnesium particles. The sludge containing the magnesium particles is a friable, continuous matrix of frozen salts that may also contain some oxides and impurities. Due to the high reactivity of magnesium metal with water, a dry process was developed to recover magnesium metal from the sludge. The process utilizes mineral-processing unit operations. The steps include selective comminution, screening, attritioning and tabling. Recovery of the high-grade (>90%) metal was in the 70% range. The novel process was also successfully applied to a magnesium-alloy for the recovery of metal from the sludges.

Jan 1, 1997

By Tetevi B. Wilson

Analysis of the distribution of ore-bodies in space can be useful generally in the estimation of mineral resources or the management of exploration. This study is di¬rected to analysis of the undiscovered potential of well known areas of mining district size, referred to as metallogenic units (MUs). The analysis employs an effort¬ adjusted and truncated probability model for number of occurrences within a subdivision (quadrat) of a MU and Monte Carlo sampling to generate an approximation to the probability distribution for number of occurrences and number of mines within an MU when it is totally explored. Exploration potential for Monitor, Bodie, Au¬rora and Camp Douglas MUs (Walker Lake quadrangle of Nevada and California) are estimated to be 9, 4, 7 and 4 mines, respectively.

Jan 1, 1992

By H. Sis, D. Dahlin, S. Chander, C. Summers

Bench-scale selective-flocculation tests were conducted on samples of Florida phosphate and Western phosphate process tailings to recover upgraded phosphate concentrates. After physical and mineralogical characterization, the slurry samples were treated with a broad suite of flocculants with a range of molecular weights and anionic functional groups. Parameters investigated included pH, dispersant and flocculant types, and dose; conditioning parameters and settling times were, for the most part, held constant. Where selectivity was achieved, phosphate minerals remained dispersed, whereas silicate minerals flocculated and settled. Single-stage tests using reagents with low to medium anionic characteristics produced upgraded phosphate concentrates at moderately elevated pH. Two- stage site-blocking tests, in which low-molecular-weight flocculants were used as site-blocking agents, gave improved results.

Jan 1, 2002

By J. D. Miller, C. L. Lin

Liberation of valuable minerals during size reduction is an important aspect of mineral processing technology. In practice, most quantitative information on liberation is based on the application of stereological theorems for the analysis of image data from two-dimensional polished sections. On this basis an estimate of the volumetric grade distribution is made. Recently, a new method based on cone-beam xray microtomography has been used for direct determination of the three-dimensional liberation spectrum of multiphase particles 100 microns in size or less. Preliminary results for a packed bed of particles indicate that high spatial resolution (approximately 15 microns) and the direct processing of raw volumetric data are two important benefits offered by this new method. Three dimensional liberation analysis by microtomography provides an excellent opportunity to overcome many of the limitations of currently used polished section techniques. For example, detailed textural information is provided. Of course microtomography provides an independent method to verify current procedures used for analysis and transformation of polished section data into an estimate of the volumetric grade distribution. More important, however, is the possibility that this method could be developed as a routine procedure for liberation analysis in the 21st century.

Jan 1, 1997

By R. Y. Wan, Corby G. Anderson, L. Ernest Krys, M. C. Fuerstenau

Since 1942, refractory precious metal concentrates at the Sunshine mine have been processed for antimony metal recovery using a novel leach-electrowin method. This is counter to most antimony production facilities where pyrometallurgical techniques are usually relied upon. The key step for removal of the antimony has been an ambient pressure alkaline sulfide leach. In 1990, a comprehensive laboratory study was undertaken to better understand this process. Factors studied included temperature, agitation, concentrate regrind, alkaline species concentrations, sulfur species concentrations and solids concentration. Details of these studies, as well as a brief description of Sunshine metallurgical processes, will be presented.

Jan 1, 1993

By Lijun Xu, Ragula Bhaskar

The transport of dust particles from a turbulent air stream on to the surface of a mine entry is mainly due to the effect of diffusion, sedimentation and inertial impaction. While the literature in aerosol science contains many references on particle deposition, most studies apply to smooth surfaces in small, short tubes. The deposition data from those experiments may not be applicable to deposition in mine airways that have large areas of rough surfaces and extend several thousand meters. This paper describes the mechanisms of mine dust transportation and deposition, specifically, by estimating the turbulent deposition velocity for coal dust in mine airways. Data from in-mine experiments on ambient dust concentration and dust deposition along a straight entry were used. A statistical model for dimensionless turbulent deposition velocity was developed, and compared with the models developed by other researchers. The model shows that the distance from the dust source is an important factor in the turbulent deposition of mine dust.

Jan 1, 1995

By G. F. Friel, J. C. Edwards, C. C. Hwang

In the implementation of a mine fire alarm and location strategy, the Interpretation of the fire signature Is Important. Smoke and CO are the two dominant fire signatures, and many mine fire detection systems utilize sensors which respond to smoke or CO through a diffusion mode or a mechanical pump mode. The fire signature may be modified during its transport along airways and at crosscuts. The modification occurs through dilution of the contaminants. In this Investigation, computer codes were employed to compute the effects of contaminant dilution on the contaminant signature when a straight flow passage has one dead-end crosscut. The model predicted the airflow within always and the entrainment of contaminants into the crosscut from the airway. One application of the model is to determine the most suitable location for CO detectors for early mine fire detection.

Jan 1, 1995

By R. Larry Grayson

A survey of 1250 surface and underground coal mines across the United States was made according to a stratified sampling technique based on national coal districts. A total of 171 responses (13.7% response rate) have been returned and summarized, giving a picture of computer usage in the coal industry. Overall, 63.5% of the respondents use computers, but the percent varied from 100% for large mines to only 44.1% for small mines. As expected, a proliferation of microcomputers has pervaded the industry. Importantly, in spite of the high usage of computers in the industry, sophisticated engineering applications have not yet burgeoned.

Jan 1, 1989

By J. Bouchard, V. Aubé, A. Desbiens, R. del Villar

The metallurgical performance of column flotation is determined by the concentrate grade and recovery. Although the former can be continuously measured using an on-stream analyzer, the latter must be estimated by a material balance calculation based on seldom verified steady-state assumptions. Consequently, the automatic control and optimization of flotation columns should be performed using secondary variables having a strong influence on the metallurgical performance, such as froth depth, gas hold-up or bubble surface area flux and bias. The aim of this paper is to present a method to get froth depth and bias measurements using virtual sensors. Fractional factorial experiment design for the neural network calibration of the bias sensor, pilot plant results, and eventual industrial applications – including the possibility of achieving effective real-time optimization from bias and froth depth measurements – will also be discussed.

Jan 1, 2003

By Gordon M. Elliott

Health risk underlies all of today's environmental regulations. Mine Manager's are no strangers to risk, but risk in the context of mine management is not the same as risk in the context of environmental regulation. One of the risks facing the mine manager is whether the mining operations meet environmental compliance standards. These standards are defined in terms of the frequency of occurrence of adverse health effects in an exposed population (i.e., health risk). Demonstration of compliance necessarily involves mathematical modelling and selection of values for input variables. What is not immediately apparent is that the method of estimating the human health risk has a significant influence on remedy selection and the amount of money spent at suspected contaminated sites. Using a hypothetical, mining-related example, this paper illustrates the disassociation between the current deterministic approach to health risk assessment and cost-effective decision making. This paper also illustrates how the probabilistic approach to health risk assessment provides a more realistic characterization of health risk and enables mine managers to identify cost-effective remedial strategies for the site.

Jan 1, 1992

By L. E. Krys, K. D. Harrison, S. M. Nordwick, C. G. Anderson

Since 1984, nitrogen-species catalyzed pressure leaching has been utilized at the Sunshine Mining and Refining Company for the recovery of precious metals from a refractory sulfide concentrate, The process operates without the use of cyanide. The plant is now the only industrial-scale commercial application of this technology. Since the inception of the process, changes have been implemented to improve efficiencies and throughputs. Two of these changes, the replacement of nitric acid by sodium nitrite and a concentrate regrind, have recently been implemented. This paper will discuss the outcomes of these recently patented plant-process changes. In particular, a comparison between the previously used method and the new leach method is made. Also discussed is the potential applicability of the process to other materials. A companion publication (Anderson, Harrison and Keys, 1996) indicates possible mechanisms responsible for the success of these process changes.

Jan 1, 1997