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By C. L. Karr, E. J. Gentry

Researchers at the U. S. Bureau of Mines have developed a control algorithm to efficiently manipulate chaotic systems. The control, based on both fuzzy logic and genetic algorithms, prescribes actions that drive the chaotic system to acceptable regions of state space. The use of fuzzy logic enables a person who has limited experience with a chaotic system to establish a set of rules for manipulating the problem environment, and a set of membership functions that define terms used in the rule-set. Genetic algorithms are search algorithms based on natural genetics, and are used in the control algorithm to select membership functions that provide for a suitable level of control. The Bureau-developed algorithm controls the computer simulation of a ball bouncing on an oscillating table, a system that exhibits chaotic behavior.

Jan 1, 1993

By M. J. Klishis

This paper presents the findings of a study on roof bolter's hazard exposure. A "microanalysis" of accident data was combined with ergonomic observations of roof bolter operators to categorize bolting-related injuries, and, from this, a checklist was constructed. Bolting-related problems were identified as situations that could expose bolter operators to hazards. Approaches to avoid these situations were applied at six mining operations to evaluate specific problems in root bolting operations. The research emphasized the importance of analyzing worker behaviors in the context of mining situations and equipment-design problems that lead to human-error accidents.

Jan 1, 1996

By R. W. Smith, S. A. Davis, A. M. Raichur, M. Misra

The flocculation of coal is typically accomplished by the addition of commercially available polymeric flocculants. Recently it was shown that biopolymers derived from microorganisms can also be used. The biopolymers flocculate coal efficiently and make the coal more hydrophobic. This increase in hydrophobicity can be utilized to separate coal flocs and can be used for reducing the moisture content of the flocculated coal. In this regard, flocculation and settling tests using biopolymers and synthetic flocculants were performed on fine coal. The experimental results are discussed and a transport model is presented for the time-dependent settling of fine coal.

Jan 1, 1998

By M. Niinae, Y. Nakahiro, K. Yamaguchi, T. Wakamatsu

The rare earth magnet has a good performance and the production is increasing year by year. Two types of rare earth magnets are presently made as industrial products. One is a Nd-Fe-B intermetallic compound magnet and the other is a Sm-Co alloy magnet. The mixed scraps of Nd-Fe-B intermetallic compound and Sm-Co alloy are sometimes produced in the step of production. Therefore it is desired that a recycling system of mixed rare earth magnet scraps should be established. In the present study, hydrochloric acid leaching of the oxidizing roasted products of Nd-Fe-B intermetallic compound and Sm-Co alloy and solvent extraction of metals such as Nd, Sm, etc. are tested to obtain the fundamental data for the hydrometallurgical treatment of the mixed rare earth magnet scraps.

Jan 1, 1995

By Anis Farah, Khosrow Aref

Pull-out tests were conducted on cable bolts grouted with concrete, and cement paste. The influence of several parameters on the performance of these cables were studied under loading rates varying from very slow to relatively fast. These parameters include water-cement ratio, cable surface conditions, curing time and embedded length. In addition to being more economical, the results indicate that cables grouted with concrete have higher ductility and ultimate bond strength as compared to those with cement paste only.

Jan 1, 1986

By Ross W. Smith, D. L. Taylor, K. A. Altman

Traditional sensitivity analysis of metallurgical data has the potential to overestimate the value of mining projects. Such analyses provide no information about the probability of the results. Simulations that rely on the input of statistical information provide more realistic predictions of the value of future projects and offer additional information regarding the probability of the outcome.

Jan 1, 2003

By S. Zhou

Since the hypothesis of coal and methane outburst mechanism based on elastic mechanics gives no consideration to time, it can not give a satisfactory explanation to the outburst occurrence and its development. A creep mathematical model of coal containing gas has been set up through creep tests and analysis under the condition of tri-axial compression. And the model can explain the phenomena of coal and methane outburst successfully. The tests proved that there is no essential difference between the rheological properties of prone outburst coal and non-prone outburst coal. Outburst can take place in any kind of coal if the rheological conditions of coal containing gas are met. The creep mathematical model provides a basis for establishing a comprehensive index of coal and methane outburst possibility.

Jan 1, 1991

By J. B. Nanor, J. Lorengo, M. Misra, C. B. Bucknam

The dissolution of mercury during the gold cyanidation process is the cause of many environmental, health and processing problems. The removal of mercury-cyanide complexes from synthetic solutions and process water were investigated using sodium and potassium dimethyl dithiocarhamates and sodium sulfide as precipitating reagents. The results have shown that efficient mercury removal can he achieved by the formation of stable mercury compounds with the addition of potassium dimethyl dithioearhamate. The mercury dimethyl dithioearhamate precipitates are stable under plant operating conditions, and they do not have any deleterious effect on gold adsorption by activated carbon. Furthermore, it is possible to stabilize mercury in the heap during cyanidation by adding dimethyl dithioearhomate.

Jan 1, 1999

By David M. Spatz

Team, as defined by Katzenbach and Smith (1993), is a small number of people with complementary skills who are committed to a common purpose, performance goals and approach for which they hold themselves mutually accountable. As the mining industry searches for new ore discoveries increasingly under post-mineral cover, the process of mineral exploration has taken us from prospector to geologist to multidisciplined explorer to multi-disciplinary team. Multidisciplinary exploration techniques have improved in terms of sensitivities and penetration and more than ever before each technique requires specialists with appropriate training and skills to process data and interpret results. To produce a quality product, specialists must collaborate openly and honestly in an atmosphere where the collective result takes into account the knowledge and expertise of each individual and the relationships between all pertinent data sets.

Jan 1, 1998

By P. Arell, D. Folkes

This paper presents the basics of EPA’s Hazard Ranking System (HRS), which is used to evaluate sites for possible inclusion on the Superfund National Priorities List (NPL). The paper describes the surface water, ground water, air, and soil exposure pathways and how they are applied to mining sites. Key factors contributing to the site score include the likelihood of a release, waste characteristics, and the targets for each pathway. Waste volumes, definitions of landfills versus surface impoundments, and background concentrations are of particular importance to mining and smelting sites. Because of the presence of metals, large waste volumes, and observable releases, mining and smelting sites often receive high enough scores to be proposed for the NPL based on a single path-way. Neverthess, owners and operators can take steps to reduce the risk of being scored, and to reduce the potential for high scores.

Jan 1, 2004

By D. J. Shields

The goal of public policies is to connect desired ends with practical means toward their achievement. How the desired ends are determined, and whose goals and objectives they incorporate, depends upon the culture and political system of the country in question. With few exceptions, policies change over time to reflect changed perspectives and understanding of the world around us. This is true regardless of the policy area in question. Thus, how societies view and manage their mineral resources has evolved in response to public attitudes, societal needs, economic circumstance, cultural perspectives, political orientations, technological advancements, and geological knowledge. In this paper we examine how the scope of concern has changed for mineral policy. We then review the overarching issues that have in recent years been considered essential components of mineral policies. We point out how neoclassical microeconomics has influenced recent policy design. We then use a market flow diagram to illustrate how policies can be focused at specific market issues. We next discuss mineral resources in the context of sustainable development. We identify issues that become relevant when the frame of reference is enlarged beyond ensuring supply and capturing economic rent. We show that policy based solely on neoclassical economics may not be able to effectively incorporate these issues.

Jan 1, 2007

By R. W. Smith, D. L. Taylor, K. A. Altman

The importance of metallurgical information in reaching appropriate decisions during the development of mining projects is demonstrated. A financial analysis is calculated using discrete system simulation. The results are compared to the results of a traditional sensitivity analysis. The traditional analysis is shown to have the potential to overestimate the value of mining projects. The type of statistical distribution used in a random number generator affects the results significantly. The statistical method of analysis provides insight into the amount of metallurgical testing needed and provides verification of how representative the samples are.

Jan 1, 2002

By Stanislaw Wasilewski, Zdzislaw Krzystanek, Boleslaw Firganek

The experimental system for mine venti1ation control in Staszic colliery has two - level structure. In the lower - measuring 1evel the existing computer - based early fire detection system has been used completed with a number of additional sensors needed for ventilation parameters monitoring. The higher 1evel is a secondary computer equipped with a suitab1e dedicated software performing data processing according to the control a1gorithm. Direct control of air flow in a selected mine district is performed by means of a remotely controlled automatic regulator. Apart from functional tests of the system and its elements some research work has been carrying out in the colliery based on observations of transient effects caused by changes in air flow distribution.

Jan 1, 1989

By J. Partyka, J. S. Stachulak

Dust produced during blasting in a copper/nickel based mine was studied and characterized. A stope utilizing the crater blasting technique, or the vertical retreat mining (VRM method), was examined. Two dust monitors were used to measure an airborne dust produced during blasting operations. The data collected in situ was primarily used to formulate the boundary value problem for a generalized equation that describes the transportation process of airborne dust from all places where dust is produced by the VRM mining method. The field data was also used to define the analytical forms for the initial and boundary conditions, to provide a simple and reliable equation for flow of dust in a stope vicinity, and to identify the non-measurable constants. The effects of the amount of blasting material and of the ventilation system in use on dust concentration are also discussed.

Jan 1, 1995

By W. E. L. Minter

The most important Witwatersrand gold placers occur on extensive unconformity paleosulfaces that were produced during protracted periods of fluvial degradation. The erosional etches on what was generally unlithified sub-strate indicate that low sinuosity erosion patterns prevailed. The transport systems were dominantly braided fluvial with a minor debris-flow component. The placer sediments were non-cohesive sands and gravels. They were evidently transported by fluctuating, yet perennial, discharges across extensive, low relief braid plains, not far from littoral environments. Progress made in understanding heavy mineral transport processes now emphasizes the importance that selective entrainment probably had in producing concentrations. Cognizance that these characteristics are not unique to the Witwatersrand should be taken into account when designing exploration models.

Jan 1, 1991

By J. A. Organiscak

This paper examines methods for limiting occupational silica exposures for roof-bolting personnel in underground coal mining. A canopy air curtain and an air tube were evaluated as means to provide filtered air over the breathing zone of these personnel. Laboratory testing showed that dust reductions beneath the air curtain and air tube approached 60% and 40%, respectively, with low interference air velocities. The data also showed that dust reductions were highest for positions closest to the device and that these levels decreased with distance. This paper also evaluates a metal rake, a flexible insert and a rigid insert for cleaning the roof-bolter dust collector box. Less dust was produced when using the rigid insert. Surprisingly, the flexible insert was sometimes no better than scraping or raking the dust onto the mine floor. However, little dust got on the workers coveralls when using either of the inserts.

Jan 1, 2003

By R. Gong, R. Bhaskar

The development of a three-dimensional mathematical model for evaluating airflow fields at a continuous miner face is described. The model utilizes three-dimensional incompressible flow, mass continuity, and momentum (Navier-Stokes) equations to predict the airflow velocity at the face. Obstacles and equipment in the face area are modeled using appropriate boundary conditions. Parameters such as flow velocity and face dimensions can be modified and evaluated for various schemes, such as exhausting and blowing ventilation, using either brattice or tubing. A model such as the one described, with additions for local effects, can be used to evaluate novel face ventilation ideas before initiating expensive full-scale tests or field studies. The model described is a step in the direction of advanced predictor models.

Jan 1, 1993

By M. T. Ityokumbul

Flotation columns and their variations are increasingly replacing conventional cells in mineral-processing circuits. While the operational characteristics of columns differ from those of conventional cells, the same scale-up methodologies are being employed. This practice may be attributed to a poor understanding of the factors that control throughput. The use of tall flotation columns is frequently justified because of the need for an increased particle residence time. However, it is shown that longer particle residence times alone do not translate into increased recoveries. In this paper, throughput data from several industrial flotation-column installations is presented. Also, an attempt is made at using dimensional analysis to provide a scale-up methodology for the factors controlling column throughput.

Jan 1, 1997

By M. Li, J. D. Miller

It has been discovered that water insoluble alcoholic solutions of alkyl hydroxamic acids serve as selective collectors for the flotation of phosphate mineral resources (Miller et al., 2000). The effectiveness of the new collector chemistry has been demonstrated by the results from single stage bench scale flotation experiments for feed material from plants in Florida, North Carolina, and Utah. In the best case, from experiments with low grade (5% P20,) coarse feed (16 x 35 mesh), a single stage phosphate recovery of 95% was achieved with a concentrate grade of 31% P20,. Such a separation efficiency could not be achieved using the traditional fatty acid/fuel oil collectors as is evident from a comparison of the respective grade/recovery curves.

Jan 1, 2002

By A. B. Holland-Batt

In the 1960s and 1970s, incremental development rather than innovation was the norm for gravity separation. However, the last 15 years have seen a number of new developments in this area. The article reviews the traditional gravity-separation techniques and then examines the newer developments such as centrifugal separators. Emphasis is placed on novel devices or improvements that offer better control or improved performance.

Jan 1, 1998