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By Bruce D. Hansen

The complexity of large geographically diverse or multicommodity mining companies requires a corporate structure, which provides the maximum long-term effectiveness. Structure models exist along the spectrum of centralization to decentralization. This paper examines the trade-offs of flexibility, cost, decision making, consistent strategies, and corporate control associated with different structural models as applied to mining companies. The mining industry typically lends itself to a business unit model. However, the degree of decentralization depends on size, proximal operations, technical complexity, product mix, geographic spread, mining methods employed, and the inherent capabilities of an organization.

Jan 1, 2001

By Sue W. Wells, James J. Moore, Stephen D. Lynch, R. Hunter White

This paper describes the products and services that Phelps Dodge Corporation desires from solvent extraction reagent suppliers and the partnering relationship that Phelps Dodge wishes to develop with these suppliers. Product topics include: 1) manufacturing concerns, 2) product and process quality control reporting and 3) reagent customizing to meet individual plant needs. Service subjects include distribution, delivery time, emergency re-supply, terms, and tailoring technical support. The partnering relationship discussion reviews mutual benefits, communications, reliability, cross-functional teams for problem solving and developing new opportunities, and long-term commitment.

Jan 1, 1994

By Takashi Sakaguchi, Takehiko Tsuruta, Akira Nakajima

Some attempts were made to recover gold from aqueous systems using immobilized persimmon tannin. This adsorbent adsorbed gold from solutions containing hydrogen tetrachloroaurate (III) with high efficiency, whereas there was minimal adsorption from solutions containing gold (I) sodium thiomalate and sodium dicyanoaurate (I). The adsorption of gold was rapid, and was affected by the pH of the solution, temperature, external gold concentration and amount of adsorbent. Adsorbed gold was easily desorbed with 1 M thiourea solution, indicating that immobilized persimmon tannin can be repeatedly re-used for the recovery of gold using adsorption-desorption cycles.

Jan 1, 1995

By M. J. Hrebar

This paper reviews large dozer stripping techniques and presents results of two field studies. The first is a seven-shift study of a contour block stripping operation where a Caterpillar DII is used as the primary stripping equipment. The second is a two-shift study of two Cat DIIs dozing blast cast material ahead of a dragline operation. Surveys and continuous time studies were used to determine production rates and as a basis for forecasting unit stripping costs in both cases.

Jan 1, 1994

By James A. Everts

Calcined bauxites are classified by their major end uses - abrasives and refractories. Target properties are dictated by application and processing requirements. The chemical and physical properties of premium grade calcined bauxites are far more stringent than metallurgical bauxite and this limits the sources and availability. Premium grade calcined bauxites are considered to be strategically critical to the industrialized countries of the world. Subject to disruptions in the key source countries, adequate supplies of premium grade calcined bauxites are anticipated in the foreseeable future.

Jan 1, 1984

By Ji Changsheng

In a large surface mine design, different kinds of mining equipment can be selected. Even though the major purpose of capital investment is to get more profit from mining activities, there are some other complicated factors which influence the selection of mining equipment must be considered as well. A fuzzy evaluation model with fuzzy set theory is proposed in the paper to make a good selection of mining equipment in which different kinds of factors including quantitative and nonquantitative ones can be taken into account at the same time. With the model, mining equipment selection of a large surface mine can take into consideration not only economic factors but also some other factors which play important role in mining system.

Jan 1, 1996

By Fathi Habashi

CLAYS CONTAIN the mineral kaolinite, a hydrated aluminum silicate. It is an important potential raw material for aluminum, especially for those countries possessing no bauxite deposits. Therefore, there is no surprise to find a large volume of research done for the recovery of aluminum from clays. Kaolinite (Al203?2 SiO2?H20) contains 39.8% A1203; 46.3 % SiO2, and 12.9 % H2O. The analysis of a good-quality dried clay of an Eastern Canadian siliceous shale is shown in Table 8-1.

Jan 1, 1970

By V. N. Sukhov

This set was developed to use the mathematical methods and computers in the data analysis and accumulation of the large amount of geological data to solve the typical geological problems at the deposit exploring stage as well as for planning and managing in the open cast deposit mining. That is to say, the set of tasks ensures the geological data base at the stage of the deposit exploring and also its further use and. updating at the exploration stage. The following main elements may be ear-marked in the complex: (1) geological data base (GDB), (2) the data input system, (3) GDB maintainance, (4) "Geologist" geological application package (GAP). Let us consider now each element purpose. 1) GDB logical structure is determined through five hierarchical substructures with a common root segment.

Jan 1, 1986

By S. L. Jung, T. L. Nichols, K. Prisbrey

The problem was to evaluate the on-line detection of rock properties through acoustic emission sensors. Acoustic emission sensors, when attached to crushers, grinders, and roof bolters, are robust, economical, and relatively maintenance free. Our objective was to relate acoustic emissions to rock fracture mechanisms, including micropore closures, linear elastic deformations, and crack propagation. We evaluated acoustic emissions from steel jacketed rock cores during indentation tests. In addition we attached sensors to the rotating shaft of a rock bolter drill. A back propagation neural network "learned" rock fracture characteristics and rock type with 99% classification accuracy. A neural network's calibration and computational abilities suggest better acoustic emission sensor capabilities.

Jan 1, 1993

By P. R. A. Andrews, G. Heinrlch, V. I. Lakshmanan

The paper describes a simplified method to chemically modify the surface of industrial mineral fillers. Four industrial mineral samples were taken from feedstock of commercial fine grinding operations. These samples were ground in bench scale ball mills and in the presence of various organic solvents. The ground products were measured for particle size distribution, surface area, surface chemistry by oil absorption and degree of organicJminera1 bonding. Where appropriate, the ground products were compared to commercially available surface modified, industrial mineral fillers.

Jan 1, 1990

By Christopher J. Bise

During the past two decades, the emphasis on technological advances in US underground coal mining has focused on longwall mining. But there also has been a steady, although less spectacular, advance in the state-of-the-art in room-and-pillar mining. This has been stimulated by the successes of longwall mining in mine cost reduction, increased availability and improvements in haulage infrastructure, such as conveyor belt haulage. In addition, changes in management practices, such as nine- or 10-hour shifts, and marketing pressures have resulted in changes in the use of equipment. The net result of these changes has been the creation of modern room-and-pillar operations where average production levels currently exceed those considered very good 20 years ago. In fact, current production levels considered outstanding were considered unattainable two decades ago.

Jan 1, 1995

By Henry Brehaut

The International Network for Acid Prevention (INAP) was formed in 1998 by 17 international mining companies to promote significant improvements in the management of sulphidic mine materials and the reduction of liability associated with acid drainage through knowledge sharing and research and development of technology. Since its inception two panels have been formed to identify and move forward with research projects and eight networks have been constituted to initiate interaction and knowledge sharing within the membership in specific areas of technical interest. An INAP web site has been developed to facilitate the sharing of information and to encourage the exchange and development of new ideas.

Jan 1, 2000

By M. Manrique, S. A. Pirzada, P. R. Taylor

A thermal plasma-assisted laminar flow reactor was used to evaluate the kinetics of converting alumina to sodium aluminate in flight. Free energy minimization calculations were used to determine experimental conditions. The experimental variables included alumina particle size, alumina/sodium nitrate molar ratio, temperature and residence time. A mathematical model for the conversion was developed and validated. Experimental and mathematical results are presented.

Jan 1, 1998

By J. B. Yianatos, G. S. Dobby, J. A. Finch, A. R. Laplante, R. Espinosa-Gomez

The question is posed as to why columns typically have a collection zone 10 m high (H) by 1 m in diameter (D). Three geometry dependent factors are considered: degree of mixing, Np; volumetric bias rate, B; and volumetric gas rate, G. Increasing H:D decreased Np and B, which improves performance but decreases G, which causes the column to approach overloading. Taking typical column operating conditions, it is concluded that a collection zone H:D of 10:l is a reasonable compromise.

Jan 1, 1987

By E. Topuz

Mining equipment, like all other equipment, is subject to failure. Since most failures occur at random and are unexpected, corrective maintenance is usually more expensive and causes more down-time than preventive maintenance. In order to reduce the number of failures and thereby increase the availability of an equipment or system, preventive maintenance can be scheduled at predetermined points of time. The preventive maintenance scheduling policies presented in this paper utilize reliability and probability theories. They can be applied to various production bottlenecks where high cost equipment precludes having sufficient quantities of stand-by units.

Jan 1, 1982

By Leopoldo Cortez, Fernando Durão

The dynamic control of a froth flotation section is simulated through a neural network feedback controller, trained in order to stabilize the concentrate metal grade and recovery by applying random step changes to the feed metal grade. The results of the application example show that this controller seems to be sufficiently robust and a good alternative to handle a non-linear process.

Jan 1, 1995

By Taira Emoto, Hikozou Imaoka, Sohta Takatsu, Takeshi Suzuki, Yoshihito Minami

An Oval Section TBM (tunnel boring machine) enables excavation of tunnel with elliptical cross section by inclining the cutterhead. It is developed to utilize the proven conventional TBM technology with minimum modifications. Various types of tunnels which are preferred to have non-circular cross section can be economically excavated, reducing both overbreak and the amount of muck produced. On the other hand, an inclined cutterhead may create a number of new problems, such as in excavation efficiency and steering that are unknown in excavation works using a circular TBM. This paper reports on verification tests carried out to examine the extent of such problems using experimental models of the machine in an attempt to confirm the feasibility of the Oval Section TBM.

Jan 1, 1997

By S. S. Mauney

Natural and synthetic colors are used in almost every facet of daily life as a means of communication and expression. Natural ochres, umbers, hematites and magnetites were once used in their crude or semiprocessed state for their pigment value in construction products and low-end coatings applications. In recent years, though, they have yielded to synthetically produced iron oxides for more sophisticated products. Today, through innovative mining processing and marketing techniques, natural iron oxide pigments are once again gaining strong inroads into products and markets requiring precise chemical and physical characteristics. With the focus on environmental consciousness and resource conservation, value added natural iron oxides provide an economical and responsible alternative to color needs.

Jan 1, 1995

By A. I. Arol, I. Iwasaki

Clay minerals adversely affect the selective flocculation of iron ores. The effect of montmorillonite on a hematite-quartz mixture was studied. Montmorillonite, particularly in the presence of Ca++, caused indiscriminate dispersion of the pulp. Three possible mechanisms were postulated, namely, card-house structure formation, adsorption of dissolved species from montmorillonite, and montmorillonite- hematite interaction. It was determined that hetero- coagulation of montmorillonite on hematite was responsible for the behavior. Flocculation tests, montmorillonite abstraction tests, starch adsorption tests, zeta potential measurements, and surface analysis techniques were used to ascertain the montmorillonite-hematite interaction and to account for the manner in which it affected selective flocculation.

Jan 1, 1987

By Randall D. Peterson

Economic operation of a mine ventilation system must include some means by which operating costs can be quantified and evaluated periodically. Current practice at most mines relies upon the best judgement of foremen, engineers and managers to identify high cost or problem areas in the system and to estimate potential costs and benefits of work proposed to reduce inefficiencies. The problem with this is that significant savings can be overlooked or sub-economic projects may be undertaken when sufficient attention is not paid to the interrelationship between airflow characteristics and corporate financial criteria. In order to accurately determine costs and benefits it is necessary to view the solution of each potential ventilation problem as a separate economic opportunity.

Jan 1, 1993