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By Edgar E. Vidal, Patrick R. Taylor

Standard textbook equations for heterogeneous kinetics typically utilize a constant driving force to solve for rates and times of reactions. In order to more closely model real systems, equations and solutions are presented for particle leaching kinetics in which the driving force is decreased as the reactions proceeds. In addition, models for continuous co-current and continuous counter current aqueous-solid reactions are presented.

Jan 1, 2005

By Ulf Svensson, Donald E. Zipperian

This paper reviews commercial installations of FLOTAIRE Column Flotation Machines for metallic, nonmetallic, and coal flotation. Second generation FLOTAIRE Column Flotation Machines employ dual aeration systems to provide a mixture of air bubble sizes. Operating data presented in this paper shows that optimum grade and recovery relationship for each rougher, cleaner, and scavenger application are obtained by adjusting the ratio and volume of aspirator air bubbles and micro diffuser air bubbles.

Jan 1, 1988

By Antonieta Middea, Rupen Adamian, Fernando F. Lins

This work presents the results obtained with aggregation of fine talc (-19 m), a naturally hydrophobic mineral, in the presence of KC1 solutions. The classical DLVO theory describes well the aggregation of talc in dilute KC1 solutions. Beyond 1 M KCI we have found indications that a non-DLVO interparticles force is operative, say an hydration (repulsive) force. This structural force could be responsible for the unexpected re-dispersion of talc suspension. However, no repulsive force (depression) has been observed in salt flotation of talc at higher ionic strength, up to 3 MKCI.

Jan 1, 1995

By P. K. Berger, G. T. Lineberry, H. P. Cole, J. V. Haley

Sixty-five simulation exercises were developed for teaching and testing problem solving and decision making skills to miners and mining engineers. The exercises focused on judgment and decision making for preventing and controlling mine emergencies. The structure and field testing of the exercises are described, and sample frames of individual exercises are presented. Empirical data are summarized about the effectiveness of these simulations based on the performance scores of a national sample of miners and mining engineers.

Jan 1, 1994

By James L. Vanderbeek

The Chino concentrator commenced operation in 1982 as a SAG-ball mill circuit which could process 37,500 stpd of ore. Since 1982, a series of process improvements such as the addition of two stages of SAG recycle crushing, allowed throughputs to increase to more than 48,000 stpd, at the expense of significantly coarser flotation feed sizing and reduced recovery. To compensate a third (tertiary) stage of grinding consisting of four 1250 hp Vertimills was installed which has allowed the flotation feed size and recovery to return to historical levels. The design and operational characteristics of the Tertiary Grinding Circuit are described.

Jan 1, 1998

By Lothar Baumann, Wilhelm Knickmeyer

In mechanized roadheading predominantly two methods of rock breakage are applied at present: the cutting method by means of picks and the cutting/crushing method by means of roller cutters. Both systems meanwhile reached a high degree of technical development and consequently show very few possibilities of further improvement. While application of hard-metal picks is limited by rock hardness, the roller cutters require a high specific thrust, and, accordingly, heavy carrier systems. Roller-cutter equipped tunneling machines are therefore only cost-effective in hard-coal mining if the high investments for transport and assembly are justified by a corresponding length of road to be headed. The limit for acceptable cost-effectiveness is at present a minimum heading length of approximately 3 km. In order to improve the specific cutting performance of roller cutters by activation, Bergbau-Forschung carried out a research project sponsored by the Commission of the European Communities and the provincial government of

Jan 1, 1981

By Edward S. Frohling

Va a ser discutida la información que se requiere para un estudio preliminar de viabilidad y la información adicional que se requiere para el estudio final de viabilidad de un nuevo depósito de mineral. El estudio preliminar de viabilidad se realiza con muy poca información y con un mínimo coste para el propietario. Sin embargo, el diseno del informe preliminar es similar al utilizado para el informe final. En este momento, se supone que el resultado del estudio preliminar es favorable y el propietario autoriza el estudio final de viabilidad a una compañía de ingeniería. Se describirá el tipo de organización para completar el estudio final de viabilidad. El informe final incluirá toda la información y datos relativos al nuevo depósito de mineral. La información presentada debe ser entendida lo mismo por el personal financiero que por el técnico.

Jan 1, 1982

By Lynn B. Hales, John A. Herbst, Thomas L. Gabardi

A system for a continuous determination of the charge volume of grinding media in ball mills and SAG mills has been developed. The system, comprised of a unique measurement device and a model based Kalman filter algorithm, determines grinding media level within a mill and calculates media and liner wear rates. The signal from an instrumented washer mounted on the exterior of the mill shell is used to provide the measurement that, along with mill power and on-line models for media mechanics, result in estimates of mill parameters that can be used in media addition control strategies. Data are presented for a 12.5 x 15 ft. ball mill.

Jan 1, 1990

By S. K. Kawatra

Various types of mathematical descriptions of the flotation process are used in the design of a full scale flotation circuit. Mechanistic descriptions developed under controlled laboratory conditions establish theoretical residence time requirements. Empirical models, describing flotation performance as a function of full scale operating variables, are established from one flotation system and applied to another hypothetical system. Problems of design by mechanistic modeling, such as scale up factors, can be alleviated if the model is developed from a full scale flotation circuit. However, the numerous uncontrollable variables encountered in a full scale operation would preclude the practical application of such a model. Incorporating empirical relations into the full scale mechanistic model will facilitate its effective use as a guide for flotation circuit design. A semi-empirical model has been developed that promises to offer a more effective means of flotation circuit design.

Jan 1, 1982

By R. D. Miller, D. W. Steeples

Seismic reflection is a powerful geophysical exploration method that has been in widespread use in the petroleum industry for more than 60 years. This paper addresses some basic principles of the method and its application at depths shallower than 30 m (100 ft). Since 1980, the shallow reflection technique has been increasingly used for engineering and environmental problems, such as mapping bedrock beneath alluvium and delineating intra-alluvial features near hazardous waste sites, detecting voids in coal and karst, defining the top of the saturated zone and mapping shallow faults. New applications will be added with improved resolution and increased cost-effectiveness.

Jan 1, 1994

By Alexander Filimonov, Yury Bloshteyn

Ventilation of gas mines keeps necessary sanitation and hygienic conditions for labor in mines and increases the safety by dilution and removal of hazardous and dangerous gases in accordance with the safety rules. Several different concepts exist at the present time to design mine ventilation control systems. But technical ideas have been developed inadequately and technological solutions have not been investigated experimentally enough to build a serviceable system. This paper presents a new concept of high- efficiency mine ventilation process control system (MVPCS). The methods of modern system engineering (Kalman, 1969) are used to establish its functional and algorithmic structure. A three level hierarchical principle of system building is considered.

Jan 1, 1991

By Paulo Roberto, S. M. Roberto, Francisco Valadares Póvoa, Evandro C. Silva

The market of mineral goods worldwide is characterized by a growing pressure on suppliers for better quality products, lower prices and productive processes which are energetically efficient and environmentally friendly. These pressures force the mineral industry to re-think not only the present models of exploitation of natural resources and production, but also their own model of techno- logical development. This paper outlines the model and the experience of Technology Strategic Planning (TSP) adopted by CVRD to face these demands, warranting and expanding its participation in the current markets and developing new businesses.

Jan 1, 1998

By J. J. Davis, C. A. J. Fletcher, M. Li, T. Jancar

This paper summarises the experimental approach to spiral modelling at the Julius Kruttschnitt Mineral Research Centre, University of Queensland, involving the use of plastic density tracers to determine partitioning performance on three models of coal spiral. This work has led to phenomenological models of the three spiral profiles most widely used in the Australian coal industry. The results from a parallel computational fluid dynamics approach to spiral modelling currently underway at the University of New South Wales are also presented. The computational simulation has been successfully applied to generic spiral geometries and is capable of predicting the fluid phase three dimensional flow fields and corresponding free surface profiles for moderate Reynolds' number and Froude numbers. Simulation predictions are compared with experimental results from a Mineral Deposits LD9 coal spiral.

Jan 1, 1995

By Peter J. Huck, Swpan Bhattacharya, Madan M. Singh

This paper reviews the state-of -the-art techniques for estimating the duration of post- mining subsidence arising from different mining techniques and evaluates existing post-mining liability systems in the United States and abroad. For each mining technique (room-and-pillar and longwall) the mechanism of subsidence development is examined and the critical factors influencing the duration of subsidence are evaluated. These are followed by a comprehensive summary of field data on the duration of subsidence movements collected in various parts of the world. Using this information, graphical charts are developed to depict the relationship between the time duration and critical controlling factors. Also included are any mathematical relationships that may exist between the different variables. Finally, a survey of current state, federal and foreign legislation on mine operator liability time spans is provided. These laws are evaluated for their applicability in light of the data on duration of residual subsidence. On the basis of this evaluation, guidelines are suggested for the establishment of the mine operator liability structure for the United States.

Jan 1, 1986

By Paul H. Lu

This paper proposes a novel method, "integrity factor approach," of mine-pillar stability evaluation based on in situ triaxial-loading measurement. The pillar integrity factor is defined as the quotient resulting from division of integrated total pillar strength across the critical dimension by the integrated total pillar load across the same dimension. The integrity factor is dynamic, while the conventional safety factor is static. With this approach, the pillar stability can be evaluated at any stage of mining progress during panel operation. It automatically considers the progressive failure of the pillar and post-failure strength without the need to clearly define the boundary between yielded and intact zones of the pillar. Based on two case studies, the integrity factor approach is shown to be a practical, effective technique for evaluating stability of conventionally designed pillars. It is suggested that a more realistic estimate of in situ pillar strength could be made based on the combination of in situ triaxial-loading measurements and laboratory true triaxial compression tests, rather than through the traditional combination of biaxial-loading measurements and conventional triaxial compression tests.

Jan 1, 1986

By H. R. Weischedel

The art of wire rope inspection has advanced rapidly over the past decade. Present electromagnetic (EM) wire rope inspection instruments provide an important and often vital element of wire rope inspection. Some instruments are easy to operate and offer simple and clear data interpretation. Simultaneously, wire rope inspection and retirement standards are becoming simpler and more lucid. Future guidelines will he easy for inspectors to apply and for rope operators to fulfill. The thrust of evolving regulations is clearly toward periodic EM inspections supported by visual inspections. These development sallow even moderately skilled personnel to perform EM inspections of wire ropes. Therefore, it is now possible and cost effective for wire rope users to have EM and visual inspections performed by in-house personnel. In-house EM inspections have many advantages and offer an excellent return on the initial investment. Since EM inspections can detect rope deterioration in its beginning stage, wire rope users recognize that they are an effective preventive maintenance tool. For instance, the early detection of wear or corrosion allows immediate corrective action. This can easily double, or even triple or quadruple, the service life of a rope.

Jan 1, 1991

By Rene Padilla, Siyanda B. Mngadi, Gerrie van Aswegen, Peter Stonestreet

While many mine tunnels are developed through ground that must be riddled with the sources of small (and larger) mining induced seismic events, recorded by the mine seismic monitoring systems, we do not see planar discontinuities classified as seismic sources in the geotechnical databases. Here we list criteria that may be useful to identify discontinuities in drill core which are dynamic slip surfaces, parts of mining induced seismic sources. Such shear rupture surfaces in core would generally be powdery, cohesionless, and rough on cm scale. Finely broken rock and rock flour may be found in the core boxes at the discontinuities. Slickensides would be soft (easily destroyed) and kinematically consistent with the local stress field. In some cases, a cross fabric would be present, orthogonal to the slickensides, being the intersections of en-echelon extension fractures, within the dynamic shear zones, with the shear zone walls.

Apr 26, 2022

By Jacques Mongrain, Serge Barbeau, Gary Brierley

The Communaute Urbaine de Montreal is currently involved in construction of the South Interceptor which consists of 53 kilometers (33 miles) of 1,800 mm (6.0 ft) to 5,400 mm (18.0 ft) diameter tunnels for the purpose of collecting, storing, and delivering sanitary and combined sewage to the treatment plant. Work is divided into ten separate contracts; nine of which have already been bid. The purpose of this paper is to describe construction activities that have been performed through the end of 1986 with emphasis on a general layout of facilities, a summary of subsurface conditions, and brief descriptions of actual construction activities for the six contracts where tunneling has been performed. All projects are being excavated with tunnel boring machines.

Jan 1, 1987

By R. Krishna

The basic ventilation equation of power equal a constant times quantity to the power three (P=constant x quantity3) makes it an extremely costly palliative as a long term measure. Provision of increased airflow is also limited by maximum tolerable levels of air velocity, the effect upon respirable dust and, in case of coal mines, spontaneous combustion. The paper high lights amelioration measures for climatic improvements at a lower cost. The paper has also shown a method for monitoring air pollution using laser technology.

Jan 1, 1997

By Edehran Lotfi, Terrence Stobbe

INTRODUCTION Mobile excavating and handling equipment are important 'tools of trade' in the mining and construction industries. The handling of this equipment must be mastered so that its limitations are learned and its harmonic use with other pieces of equipment is practiced. he sudden growth in mobile excavating and handling equipment type, size, complexity, and application started after the Second World War. This growth has not been accompanied by pertinent human factors research. Investigations into the proper and safe handling of such equipment with due regard for human and machine limitations are lacking. One such piece of equipment is the front-end loader (FEL), which during one cycle of operation excavates, loads, and hauls, (Lotfi and Adler, 1981). The diversity of action by FEL is archetypical among excavating and handling equipment. Front-end loaders are the most rapidly proliferating type of equipment in the industry. Also, front-end loaders are involved in the highest number of accidents involving mobile excavating and handling equipment. In the period 1970 to 1978, FEL's were involved in 27% of all mobile equipment accidents in surface mining (Adkins, 1980). Improving operational safety and efficiency will reduce the frequency of accidents. The performance of the operators can be evaluated and improved by the following steps: first, define the operating conditions and the operator workload intensity (Adler and Lotfi, 1983), second, monitor the operator to evaluate his task performance, and third, make recommendations based on the findings. The stressful nature of the equipment operating task is an acknowledged fact (Field, 1980). However, a systematic measurement of stress evaluation is lacking. In this paper, methods for measuring mental stress and fatigue, are defined, the mental load which caused the stress is outlined, and stress measurement methods are proposed. MENTAL STRESS Mental stress has been described as a "specific somatic response to damage or the threat of damage by several environmental agents"

Jan 1, 1986