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By Roy H. Patten

When driving a shallow soft ground bore, the appearance of surface craters along the tunnel alinement indicates trouble, particularly when a major highway is intersected. During the excavation of a 3.7 m diam tunnel in Seattle, Washington a chemical grouting program was implemented to stabilize soil conditions sufficiently to allow advancement of the mole without loss of ground. Unanticipated mixed face conditions consisting of saturated running sand and some boulder pockets bedded on top of dense glacial till created excavation difficulties. A discussion of problems and corrective measures is presented.

Jan 1, 1987

By K. F. Hollberg, D. Graehl, L. Despain

OCI Wyoming's recent expansion of its surface Soda Ash production facilities outstripped the mine's ability to supply Trona ore necessitating infrastructure changes to the mine. A computer simulation of the mine's production systems along with the surface facilities was created to determine the most economic investment alternatives to increase mine production. This paper describes the development of the simulation model; the results obtained, and discusses the issues involved in using simulation modeling for mine production system design.

Jan 1, 2002

By I. Andras

The paper deals with the application of artificial intelligence methods in assessing the effectiveness of longwall shield support. A fuzzy sets based method is used to derive response surfaces/curves representing the dependence between basic parameters of the shield, as the initial setting pressure and the stiffness on the response metric, i.e. the convergence and load increase during a working cycle.

Jan 1, 2008

By S. El-Mofty, P. Zhang, N. A. Khalek

This article reviews different technologies used for beneficiation of siliceous and calcareous phosphate ores of different origin. The review sheds light on recent trends suggested for solving problems associated with separation of different impurities from phosphates. Applications of recently modified flowsheets as well as new reagents in the flotation of phosphate ores of sedimentary origin are highlighted.

Jan 1, 2003

By W. J. Halvorsen

Means for minimizing the disadvantages of thermal drying are suggested. The other ap¬proach of substituting other techniques in place of thermal drying is also discussed. Recent devel¬opments in fine coal screening dry down to 3.2 mm (0.125 in.) and 2.0 mm (10 mesh) offer an econom¬ical means in certain cases.

Jan 1, 1988

By Janusz Cygankiewicz, Marian Branny, Józef Wactawik

The paper presents mathematical model of concealed fire. We consider a porous medium (goaf, coal fissures) through which air flows. The set of equations is constituted by transient, two dimensional mass, momentum and energy balance equations with sources describing oxygen loss and heat generation caused by coal oxidation. Paper presents several examples illustrating the phenomenon of spontaneous heating in goaf areas behind longwall faces.

Jan 1, 1997

By H. S. Kibler, A. E. J. Gallagher, J. J. Sebesta

A review will be made of the nature, value, costs, and factors associated with industrial minerals production in general. Comparisons will also be made between some of these data and similar criteria for metallic mineral production.

Jan 1, 1987

By D. Y. Jiang, X. S. Tan, S. S. Peng

Expansion strain and stress that exist in floor rocks and that are due to the presence of water, were derived from a basic theory of mechanics. The results indicate that water stress and strain are the important factors that cause failure of the floor rocks and induce floor heave.

Jan 1, 1994

By T. N. Singh, M. M. Singh, R. B. Singh

Fly rock is common when blasting shallow holes and during secondary blasting. Although the required quantity of explosives for secondary blasts is less, noise and fly rock can have an enormous environmental impact. This paper mainly deals with field experiments on blast-design parameters and addresses some precautionary measures that can be taken when pop shooting.

Jan 1, 2000

By J. Dasher

Regarding the March 1991 ME technical paper by De Souza and Moore: For more than a decade since my February 1981 article on how to use modern metric, which SME-AIME had decided to do, I have monthly pointed out metric errors to the editors. In part, I do this because there has been no action to al low editors to fix figures and tables or to allow them to require authors to do so. The latest resulting atrocity provokes this discussion of vibrating drill handle units being stated in decibels.

Jan 1, 1991

By L. G. Austin

The data of Dunn and Martin (1978) is reanalyzed using a rigorous application of Hertzian theory to the impact process. The Young's modulus of steel required to fit their data to the theory is a factor of about 10 3, too low compared to the values quoted for steels. Thus, doubt is thrown on the validity of their experimental technique, and it is possible that their values for maximum impact force and stress are far too low.

Jan 1, 2002

Mining employment, gross output, local economic contributions and productivity are typical economic indicators. However, these economic indicators play a much bigger role in the overall capacity of the industry to be heard in decision-making on a national scale. Total mining employment in the USA has decreased significantly in the last 20 years. Gross output from most of the mining sectors has also declined, except in the case of construction aggregate. However, significant gains have been made in productivity. This paper explores these statistics and comments on their overall impact on academic institutions and political decision-making.

Jan 1, 2003

By C. J. Barbee, P. J. Bethell, C. J. Wood

Heavy medium cyclones (HMCs) are commonly used to clean run-of-mine coal in the 50 x 0.5 mm size range. Unfortunately, field studies suggest that industrial HMC circuits are often poorly designed or improperly operated, resulting in significant losses of recoverable clean coal. To assist plant engineers in overcoming these problems, a spreadsheet-based simulation package has been developed to predict HMC performance based on mathematical expressions originally developed by Wood (1990). A case study is provided to illustrate the predictive capabilities of this simulation package for an industrial HMC.

Jan 1, 2004

By R. W. Smith, A. Raichur, M. Misra, I. A. H. Schneider

The concept of microorganisms as chemical reagents (flocculants, flotation modifiers and flotation collectors) is quite new. Potential uses for microorganisms include their use in place of certain conventional flotation reagents and as flocculating agents in minerals engineering processes. In addition, in some studies micro-organisms have been used to modify mineral surfaces and, thus, the flotation or flocculation of the minerals.

Jan 1, 1995

By James F. ` King

This paper reviews the changes which have taken place in the supply of smelter-grade alumina and refinery-grade bauxite over the past twenty years. It highlights the current situation and identifies some trends which are to be expected in the medium- and longer-term future.

Jan 1, 1986

By M. L. Young, M. S. Klima

Hindered-settling columns are used throughout the minerals industry for both size and density separations. In this study, the performance of a continuous laboratory-scale hindered-settling column was evaluated for various particle systems. The test variables included solids composition, water rate and column height. Column performance was evaluated using partition curves and corresponding performance parameters.

Jan 1, 2000

By Joseph Corvetti

This paper is of conceptual nature. The authors present their idea of creating an integrated and intelligent excavation design system. Research work has just been started and the results will be addressed during presentation of this paper. The authors are currently engaged in a pilot study and expect to build a feasibility prototype expert system (establishing the numerical-cognitive coupling in excavation design) by the end of this year.

Jan 1, 1996

By Dennis K. Mortensen

Improvements in flotation technology are continually being made in the attempt to achieve the mineral processor's goal of maximum mineral concentrate grade and recovery at zero cost. Technology that cannot be totally proven in the laboratory must be tested under plant conditions either in a pilot plant or in the existing circuit. Problems associated with new technology can be solved effectively by the mineral processor who approaches each of the problems objectively.

Jan 1, 1989

By D. Farahmand

This paper focuses on formulating a practical procedure for forming long-range production and development schedules in underground mining. A computer program developed to be run on a microcomputer is presented and discussed in detail, and a practical case study is analyzed to demonstrate the suitability of the procedures discussed in the paper. The intent of the computer scheduling model is to have quick access to vital information when changes in development and production are under consideration by management.

Jan 1, 1986

By Ahmed A. El-Saie

To reduce the problem of overbreak and its associated added costs, a new technique is proposed to make a slot around the tunnel profile in hard rock. The Finite Element Method was used to investigate the effect of the slot on the stress field and deflection of the tunnel core. Beam theory was also applied to calculate the stresses and deflections of a slotted tunnel for several different slot depths.

Jan 1, 1981