Search Documents

By Clay Haynes, Tim Pearia, Robert Robinson, Judy Cochran

A 1.89 km-long, 4.5 m-I.D. tunnel was successfully constructed through saturated hard clay, and highly abrasive dense sand and gravel, with groundwater heads ranging from 10 to 20 m. In order to address these conditions, a Lovat earth pressure balance TBM was used, with soil conditioning by foam, water and various polymers. Support was provided by a single-pass segmented concrete lining. Groundwater inflows of 400to 1,600 lpm at times created challenges for changing cutting tools. Surface settlements were generally less than measurement thresholds, except under very low cover at startup. This project provides a pivotal case study of the successful application of EPBM technology in saturated, abrasive glacial soils and the successful application of soil conditioners.

Jan 1, 2003

By Robert Dunne, Paul Gelfi, Vernon Martins

The New Celebration Gold Mine is located 32 km south of the regional mining centre of Kalgoorlie. The current mill throughput is 1.7 million tonnes per annum with a gold production of around 120,000 ounces per year. The main source of ore for the mill comes from the Hampton Boulder and Pernatty pits. Over the last two years the oxide reserves from these pits have been depleted and the harder primary sulphide ores are now being processed. This change has led to a decrease in cyanide extractable gold.

Jan 1, 1991

By Pierre Louis, Jacques Duparque

ACTIRED is a new process for gold and silver elution from activated carbon based on the addition of hydrazine, needing no extra investment and which generates a systematic increase in elutions kinetics. This process either operates at a lower temperature and maximizes financial gain or reduces elution time or operates at a compromise between these two options taking into account the needs of each plant. Industrial use of the process at SNC Lastours, France (Zadra elution column 3,5 bars -125°C) has proved at 95 ° C the following points:

Jan 1, 1995

By R. J. Snoby, P. Grotjohann

In processing heavy-mineral sands, the low feed concen¬tration and respective high value of the desired minerals require high-capacity production and sharp classification/ separation techniques to reduce the specific production costs. This paper describes the new allfux® separator, which can economically accomplish these criteria. The separator is a two-stage process that combines rising current and fluidized-bed technology. This allows for the treatment of ex¬tremely high mass flows in a single unit. This paper reports on test work performed on coal, iron ore and heavy minerals.

Jan 1, 2000

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 D. C. Panigrahi

The paper presents the application of Object Oriented Programming approach for the development of a network simulation model based on nodal pressure method using linearised flow equations. The convergence and computational efficiency of the algorithm have been investigated. Finally the paper re- ports the validation of this algorithm in actual field conditions.

Jan 1, 1996

By W. Trask

The state of the art in crawler transporters for loads to 3 kt (3300 st) is sufficiently advanced to allow compilation of job cost figures showing the economics of tracked vehicle use under a wide variety of circumstances. Initial costs, cost per ton of capacity, and operational and maintenance expenses are presented. Data is derived from participation by the Neil F. Lampson Co. in more than 3 Mt - km (2.05 million st - mile) of crawler operation during the past 16 years. The effects of economics on future design trends will be examined with particular reference to versatility, portability, and capacity.

Jan 1, 1987

By D. E. Ranta, Ora H. Rostad

Ore reserve estimation, from the earliest "quick and dirty" estimates made at the first consideration of a possible project down to periodic revisions of detailed estimates made during the life of a mine, should take into account many geologic and allied factors in order to obtain results that will provide proper guidance for necessary economic decisions. Factors include: sample collection and analysis, character of the vein and associated wall- rock, mineralogy, pre and post mine oxidation effects, core loss, sample correlation, internal vein structure, wallrock controls, geologic factors affecting dilution in mining and interrelated mining and milling problems.

Jan 1, 1992

By J. W. Mahar, E. J. Cording, F. L. Gau

INTRODUCTION The Washington, D.C. rapid transit system (METRO) when completed will consist of 98 miles of double track rail. Fifteen miles will be tunneled in rock and 12 large underground rock chambers will be constructed at station locations. The University of Illinois is under contract to Metro to provide observations and instrumentation services in the initial phase of construction. The work is coordinated through DeLeuw, Cather & Co., the General Engineering Consultant to Metro. The program is designed to monitor construction conditions as well as to provide information useful for the design of future rock tunnels and rock chambers in the Metro system. This paper presents the results of observations in the rock tunnels constructed to date. Most of the observations are in a 5000-ft-long, 30-ft-wide, double track tunnel in downtown Washington, D.C. Observations were also made in single track tunnels, shafts, enlargement areas, and pilot tunnels, and are being made in a large rock chamber 700 ft long, 76 ft wide, and constructed at shallow depth in a schistose gneiss. One of the major objectives of the observational program was to determine the orientation and character of joints and shear zones and to evaluate their effect on support requirements for various tunnel orientations and configurations. The consistency of geologic features throughout the Washington area has made the results of the initial study applicable to evaluation of support requirements on future tunnel contracts. The first section of this paper summarizes the geologic conditions in the tunnel and their effect on overbreak and rock movement.

Jan 1, 1997

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 P. A. Tuzinski, L. J. Dahl, N. R. Adamson, S. E. Brink, R. L. Blake

The US Department of the Interior, Bureau of Mines is developing a process to selectively extract manganese from oxide ores as part of its in situ mining research program. The Bureau is conducting site characterization studies of two manganiferous iron-formation deposits. These studies include: drill core, regional stratigraphic relationships from the existing geologic database, ore body geometry, geologic structure, hydrologic conditions, accessibility of ore minerals to leach fluid, surface subsidence potential and data collected from laboratory leaching experiments. This information is being used to evaluate the technical, environmental and economic feasibility of in situ mining of manganese for these two deposits. This paper will focus on the stratigraphy, mineralogy, ore textures, fractures, permeability and porosity as they relate to in situ mining.

Jan 1, 1994

By Thomas Fenner

Surface and underground mining operations are often hindered by unknown tunnels and slopes and the precise locations of adjacent workings. Mine safety and planning are adversely affected especially in previously undermined areas where historical records are incomplete or nonexistent. The results of several ground penetrating radar (GPR) studies for the detection of known mine tunnels in underground coal, salt and gold mines are presented. A case study to locate unknown, abandoned mine workings at a surface gold mine successfully located all workings to a depth of 11 m (36 ft).

Jan 1, 1996

By G. Y. Li, D. Farahmand

The dilemma of a numerical analyst not only concerns the problem of modelling the non-linear behaviour of intact rock, but also the non- linearity contributed by structural discontinuities. In this light, it is the intention of this paper to examine some aspects of the non-homogenity and structural discontinuities of rock and incorporate this behaviour into boundary element numerical solution. Non-homogeneous material is considered piecewise, thus homogeneous and is modelled by using sub-regions. The Mohr- Coulomb failure criterion is employed to model the non-linear behaviour of the major discontinuities. A computer program is developed based on the procedure for combining the direct boundary element method and the displacement discontinuity method. A linear element type is employed in the formulation of numerical solution. The computer program is used to study the stress distribution in a gold mine.

Jan 1, 1986

By D. R. Tweeton, L. W. Lake

A modified push-pull field test and a computer model of cation exchange were developed to aid in evaluating cation exchange parameters prior to in situ mining. Reliable determination of these parameters is essential when modeling restoration of ground-water quality. The field test involves a much larger volume and much less disturbance to the ore sample than is feasible with laboratory measurements. This test can be per¬formed in two or three weeks. It is relatively inexpensive, requiring one injection-production well and two or more wells for collecting samples of leach solution. The use of the model in interpreting test results is illustrated with field data from an in situ uranium mine. Much of the research was performed by the University of Texas at Austin and was partially funded by the US Bureau of Mines.

Jan 1, 1987

By B. Day, L. Elinson

There is general agreement among those involved in occupational and public health that work-related diseases are under-diagnosed and under-reported. Highmark is particularly well positioned to carry out industry health analysis as it provides medical insurance for approximately three quarters of the insured population of Western Pennsylvania including some of the areas largest employers. The purpose of this study is to gain a more accurate understanding of the mining industry rates of respiratory diseases that maybe occupationally related and identify those inflated respiratory disease and hearing loss rates. Conditions examined included COPD, asthma, and pneumoconiosis.

Jan 1, 2004

By O. Fernandez, M. Vesely

Abrasive grinding, leading to ultrafine product and "critical size" material buildup inside the mill, is proposed as the cause of high power consumption and low capacity in many fully autogenous grinding processes. Addition of steel balls (hence, semiautogenous grinding) or pebble removal and separate crushing have been used, with different efficiencies, to overcome the problem. Information and data for the conceptual analysis, basic design, and operation of a pebble crusher at the Los Bronces semiautogenous grinding plant is presented along with data showing a production increase of 1000 t/d (1100 stpd) and significant operating costs savings.

Jan 1, 1987

By Richard Keith Corbin

Canadian junior mining companies whose gold exploration and exploitation programs take them across the border into the western United States should be prepared to deal with the myriad of title issues involved in acquiring unpatented gold mining claims. The purpose of this paper is to serve as an introductory outline for Canadian junior mining companies to mining laws of the United States, as well as to relevant laws of some of the western gold mining states. Topics will include the five w's (who, where, what, why and when) of Canadian junior mining companies1 rights and responsibilities in acquiring interests in U.S. gold mining properties by claim staking, lease or purchase. Historic terms of common parlance among U.S. miners, such as "claimjumping" are defined and discussed. Various legal doctrines, such as "pedis possessio" and "good faith" in the location of claims are covered as well. Controversial subjects of contemporary interest are addressed in some detail, such as whether to locate a bulk-mineable disseminated gold deposit with placer claims or lode claims, and whether lodes may be staked over placers. By thus heightening the awareness of Canadian junior mining companies, it is hoped that they can be properly prepared to avoid title disputes, and to win lawsuits when they are unavoidable.

Jan 1, 1988

By A. C. Burrow, R. P. King

A dynamic model that predicts the variation of carbon content with time in the argon-oxygen decarburization (AOD) process has been developed. The model recognizes three distinct zones in the AOD vessel: the tuyere region in which the blown oxygen reacts very rapidly with the metal components in the molten alloy; a region in which bubbles of inert gas and oxide drop lets rise through the molten alloy; and a zone in which the slag layer can interact with the molten alloy. The process is dynamically controlled by the rate at which dissolved oxygen, produced on the surface of rising oxide droplets, and dissolved carbon diffuse through the molten alloy to react at the surface of the rising bubbles. The rate at which carbon and oxygen react on the bubble surface is assumed to be intrinsically very fast. Predicted decarburization rates compare reasonably well with rates measured in the AOD vessel at Middleburg Steel and Alloys. The model has been developed primarily to allow development of a time-optimal blowing stategy for the AOD vessel.

Jan 1, 1990

By M. J. Sanzotti, C. J. Bise

This paper examines the potential for controlling longwall-induced subsidence by pneumatically backstowing waste rock into the void created by mining. The paper also examines scheduling the process as a unit operation of the mining activity. Based on a review of background literature and interviews with representatives of various mining companies, public-interest groups and state and federal regulatory agencies, a hypothetical case-study evaluation of pneumatic stowing at a southwestern Pennsylvania mine was conducted. The study indicated that current stowing technology cannot keep pace with the production potential of longwall systems in the United States. Further, at the mine used in this case study, concomitant stowing would reduce subsidence by only 50% of what would normally be incurred during full longwall caving, and the longwall coal-production rate would decrease from 3,630 t (4,000 st) per shift in the nonstowing case to 1,360 t (1,500 st) in the stowing case. A preliminary cost analysis reveals that pneumatic stowing would add from $5.79 to $11.57 per t ($5.25 to $10.50 per st) to the operating cost of producing coal at the case-study site.

Jan 1, 1997

By T. R. Ellis

The author is the leader of the Extractive Industries Task Force of the International Valuation Standards Committee. The Task Force has developed an Extractive Industries section for inclusion in the International Valuation Standards (IVS). The Extractive Industries Guidance Note provides comprehensive standards for valuation of all minerals and petroleum industry property types for all valuation/appraisal purposes. The document is scheduled for release as an exposure draft for public comment by December 2003, then it will be finalized for publication in the IVS in mid-2004. This paper discusses the content and philosophy of the Extractive Industries Guidance Note within the context of the framework of the IVS. It also discusses the international implications and implementation of this IVS addition.

Jan 1, 2004