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By James S. Redpath

INTRODUCTION Background Early in 1972 our firm was asked by Cominco, managers of Arvik Mines Limited, to carry out an underground exploration programme referred to as the "Polaris Project" on a zinc-lead deposit in Canada's High Arctic. We had carried out numerous projects in the far north but this was to be the first long decline driven in perma-frost. Despite the short notice it was possible to meet the quickly approaching summer shipping deadline. We were able to do this by drawing heavily on our own and Cominco's background in Arctic operations. The project was an excellent example of owner-contractor co-operation and this spirit was responsible for the success of the project. Unusual Aspects There were a number of unusual aspects of the Polaris Project which are discussed in this paper. The extremely remote location, the short shipping season, and the fact that the work was carried out in permanently frozen ground, when combined with the lack of handy fresh water and a very severe climate, make it unique in many respects. Despite these handicaps, a record was set during the driving of the exploration decline.

Jan 1, 1974

By Sushil Bhandari

A computer model is developed for the problem of dispersal of dust (suspended particulate matter) resulting from blasting operations in surface mines. Undulated surface (lower boundary) simulation was carried through sixth order polynomial by least square approximation. Segmentwise terrain simulation was linearly added to build ground feature extending either side of the blast location. Assuming the initial dust concentration in the vertical column to. be uniform and treating the finite vertical line sources as a series of point sources to height, H varying from zero to top of the dust mushroom, integration was done of the concentration effects from H = 0 toL tan[0] (L = horizontal distance of the blast location and [0] is the angle of the top of dust cloud from the point of observation). Using frame of reference moving with the mean wind, the ground level 'concentration (GLC) has been computed over the undulated terrain. Standard deviation (s) of concentration has been parameterized based on mixed layer similarity theory in convective boundary layer.

Jan 1, 2002

By Scott G. Britton

Thin-seam mining presents unique challenges when management or economic conditions require significant productivity increases. These challenges can be further amplified depending on such factors as labor unions, federal and state regulations and market characteristics. This article explores the turnaround situation occurring at Tanoma Mining Co. (TMC), a medium-sized, underground coal mining company in central Pennsylvania. The company has used a systematic approach of improving management controls and direction, labor relations and communications to improve its cash flow from negative to positive within a projected five-year span. An intensive upgrade-rebuild-replacement program for mining equipment and systems has also been established to support other management activities. Discussion Thin-seam coal mining is an industry within the broader industry of coal mining. Thin seam mining faces the same cost pressures and engineering problems as its higher-seam competitors, without the advantages of moving volume per foot of extracted material. To stay at economic parity with others requires additional creativity within the management team to extract higher productivity gains from the existing workforce and mining systems. The Tanoma operation is a deep mine in Indiana County, PA, about one hour northeast of Pittsburgh. Coal is extracted from the Lower Kittanning "B" seam. It lies about 91 m (300 ft) below the surface and averages 0.9 m (I ft) in height. Continuous mining units using mobile bridge conveyors or shuttle cars

Jan 1, 1991

By William R. Nash

The scope of work for the fast track construction of the Weeks Island Replacement Facility, Weeks Island, Louisiana included the design and construction of two salt mines. Mine #1 - An interim underground mining level consisting of a 975 m (3200 ft) incline and 3520 m of 5.5 m x 7.3 m (11560 ft of 18 ft x 24 ft) drill and blast excavation; raise boring; core drilling; roadheader excavation; complete bulk material handling facilities utilizing an existing production shaft. Mine #2 - Simultaneous with the interim mine construction a new one million ton per year underground salt mine was constructed consisting of: two 5.5 m diameter x 381 m (18 ft diameter x 1250 ft) deep shafts; 76450 cu m (100,000 cu yd) of drill and blast bottom excavation; surface and undergound bulk material handling systems (conveyors, skip loaders, shaft equipment, hoisting); ground freezing for water control for both the production and service shafts; the design of the first underground doublewall slipform installation of a dynamic bitumen shaft lining system; the emergency grouting of both the existing production shaft and the interim mining level in the salt dome; 227 mt x 64 m (250 ton x 210 ft) high structural steel production headframe; 2.2 MW (3000 hp) double drum mine hoist; service shaft headframe; and service buildings.

Jan 1, 1987

By I. S. Parrish

Reserve audits have increased in recent years as more companies, especially juniors, enter the ranks of producers. Corporate and individual investors are seeking corroboration of stated reserves. The reserve audit satisfies this need. An audit assures investors that the reserves, as presented, are a reasonable and accurate approximation of the quantity and grade of the economically viable material present. The reserve audit verifies that there are no fundamental errors in logic, style or the data base, and that the reserves, as given, may be used for mine planning or economic forecasting. Reserves that pass an audit may be used with confidence in preparing cash flow projections and in deriving net present value or internal rate of return on any given project. This article describes what a consultant does while performing the reserve audit. In performing an audit there are four general areas of concern that must be checked: definitions, parameters, data and procedures. In each of these, the auditor must convince himself that the reserve study has complied with governmental regulations and guidelines, professional standards and industrial practices. Any deviation from these norms must be identified and its effect upon the appropriateness of the reserves evaluated. By concluding that a reserve study passes his audit, the reviewer is stating that there are no fundamental errors in logic or style and that spot checks have revealed no substantive errors in procedure or mechanics. The responsibility for the reserves remains with the entity that compiled the original study.

Jan 1, 1990

By James H. Boettcher

Inflation and increasingly complex tax laws in the United States combined with rising national ism overseas have made the structuring of viable financing plans which meet the requirements of the various parties involved equally important in determining project success as the design of an efficient mining plan or selection of the optimal size equipment. Whereas the use of computerized analysis to design and evaluate the technical parameters of resource ventures is well accepted, computerized evaluation of the investment criteria (qualitative and quantitative) of the various parties to the project (mining firm, financial institution, product buyer, host government, etc.) is a more recent application which can make a material impact in strengthening project economics. By identifying the objectives of the parties and critically evaluating and testing them with the technical and economic/financial constraints on the project the sponsors can design a financial structure tailored to the attributes of the deposit. A myriad of new financial techniques have evolved for financing natural resource ventures, from "Commodity-backed bonds" to tax based limited partner- ships, but in every case the structure of the financing mechanism depends on carefully matching the parameters of the financial structure with the economic characteristics of the project and the objectives of its sponsors. This presentation outlines a methodlogy for computer based project evaluation in the design and structuring of stronger financial plans for natural resource ventures.

Jan 1, 1982

By M. Gaft, G. Panczer, R. Reisfeld, L. Nagli

Laser-induced luminescence and breakdown spectroscopy methods appear to be a good tool for real-time evaluation of dolomite content on moving belt. The distinctive feature for time- resolved luminescence is Dy3+ emission in apatite, which is excited by 251 nm laser light and detected with delay time of 5 ms and gate width of 1 ms. The distinctive features for breakdown spectroscopy are 604 nm line of F and P in apatite and 518 nm line of Mg in dolomite. The representative sampling of more than 200 pebbles has been studied by both methods. By luminescence method 100% of dolomite will be identified, while approximately 15-20% of apatite with extremely week Dy3+ luminescence may be mistakenly counted as dolomite. By breakdown spectroscopy the identification is 100% correct both for dolomite and for apatite.

Jan 1, 2002

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 Robert N. Evans, Delon Hampton

During construction of the Washington Metropolitan Area Transit System, the hand-mining of a mixed-face condition was anticipated on a portion of tunnel located in the downtown area of Washington, D.C. The Section, consisting of two circular tubes, extends from Station 12+80, heading in a westerly direction, traverses along a curve under Lafayette Square, and ends in a northwesterly direction at Station 37+62 (see Fig. 1a). It was near the northernmost portion of the section that the mixed-face condition was encountered. Decomposed rock was first encountered in the invert at Station 31+00. From this point the rock gradually increased in height until it intersected the springline at Station 37+62, the project limit. Summarized within this paper are measurements of the soil load on a horseshoe-shaped portion of tunnel located in the mixed face condition. These measured loads are compared to the soil load on tunnels as determined by current design methods. The paper also discusses rib and surface movements associated with the post loading process. Comments will be made on how the presence of a mixed face condition might help or hender the tunnel design and construction procedures.

Jan 1, 1974

Liebherr Mining Equipment Co., of Newport News, VA and Baxter Springs, KS, introduced the T282, a new two-axle, diesel-electric, AC drive haul truck with a payload capacity of 327-t (360-st). The T282 was unveiled at a press briefing in October 1998 at the company's Baxter Springs research and development1 manufacturing facility. In addition to an increase in pay- load capacity, the truck's AC drive system has been de- signed to allow for easy configuration to a trolley-assist system with minimal additional equipment. The T282 provides fuel savings, reduced maintenance requirements, and reduced downtime and maintenance costs, providing the mine operator with increases in productivity. Basic dimensions and weight of the T282 are: ? Overall length, 14.5 m (47.5 ft). ? Overall width, 8.7 m (28.7 ft). ? Loading height, 6.5 m (21.2 ft). ? Height - body up, 13.9 m (45.9 ft). ? Empty vehicle weight, 201 t (221 st). ? Operating weight - loaded, 528.6 t (582.6 st). ?Engine, Detroit Diesel 16V4000 at 2 MW (2,750 hp). ?Electric drive system, Siemens/Liebherr.

Jan 1, 1999

The application of Kirchoff's laws to two adjoining mine ventilation network meshes containing fans results in the construction of two general quadratic equations. These equations may be solved to give the resultant airflows and hence fan duties within the system for given network parameters and fan characteristics. This technique has a wide application for calculating the duties of fans in various combinations within a mine ventilation system. Recent difficulties in economically maintaining environ- mentally safe conditions in underground working areas distant from main ventilation fans has led to increasing interest in the use of controlled partial recirculation of ventilation. This paper develops a recirculation model which can be solved directly using mathematical techniques obviating the need for iterative techniques such as the Hardy-Cross method. The advantage of a direct mathematical analysis is that mathematical algorithms may be constructed to completely describe the ventilation system under a wide range of operating conditions. This technique is applied to controlled partial recirculation ventilation systems to demonstrate its advantages for mine ventilation planning.

Jan 1, 1989

By Alain Broussaud, Guy Fourniguet, Jacques Franck, Pierre Conil

Steady-state simulation is now in current use to assist mineral processing plant design and optimization. However, the reliability of results generated by simulators has not until now been seriously investigated. A simulator supervision algorithm was designed and programmed to study both the influence of the reliability of experimental data on the accuracy of unit operation model calibration, and the influence of unit operation model accuracy on the results of direct plant simulations. An application to a grinding flotation plant is described and discussed. The approach may open the way to the quantitative analysis of the risks taken in mineral processing projects, which would be similar to the application of geostatistics to mining projects.

Jan 1, 1990

By Fernando Concha, Arturo Barrientos

The flow in a hydrocyclone is divided into a boundary layer around the walls, an exterior inviscid flow and an air core in the center of the equipment. The boundary layer flow over the lateral walls is associated with the short circuit of particles to the underflow, while the boundary layer over the top of the hydrocyclone and the outer part of the vortex finder tube is related to the short circuit of particles to the overflow. Classification takes place in the exterior flow. The model can be validated with pilot or industrial data and simulates the performance of hydrocyclones in a wide range of design and operating variables.

Jan 1, 1992

By R. W. Hutson

One of the fundamental precepts of experimentation is the isolation of a single variable to quantify its individual effect. Unfortunately, the variability of natural rock joints has frustrated such isolation. This variability and the high cost of securing a large member of natural joints has lead to increasing experimental dependence on stage shearing, artificial tension fractures and/or model materials. The new apparatus described herein allows for the first time replication of real joints with field scale asperities. It employs a diamond band-saw blade with computer controlled feed table to cut joints with high precision. The feed system is capable of placement to tolerances similar to those of a high quality computer plotter. The accompanying software allows the table to cut any desired joint shape (repeating or non-repeating) within certain, over-all size limitations. Resulting joint surface dimensions and roughness as well as shear resistance indicates that the joint surfaces are reproduced with a precision similar to that possible for the control of other experimental variables such as normal and shear forces.

Jan 1, 1986

By J. R. Mattern

The engineering geology of the Rio Tinto Borax Boron Mine creates challenges in providing practical slope design recommendations to mine planning engineers. Low strength sedimentary units interbedded with very low strength lakebed clays surround the orebody. Faulting has offset and juxtaposed these units into variably adverse orientations, while groundwater is compartmentalized both vertically and horizontally within fault blocks. A collective program of geologic data collection, geomechanical strength testing, geologic modeling, slope depressurization, confirmation of underground stope locations, and documentation of slope behavior provides vital information for design investigations and sensitivities. Analysis results lead to risk assessments and operational procedures that add value to the business by optimizing slope configurations and minimizing risk.

Jan 1, 2004

By J. J. Carlson

Studies were carried out to determine whether filtration rate changes observed in an iron ore concentrator were due to variations in particle shape. It was confirmed that ores mined from different locations differed in filtration rates by as much as 60%. However, when image analysis was used to quantify the shapes of the individual particles in the filtration feed, it was found that the particle shapes showed almost no variation, and the shapes did not correlate with the filtration rate. It was also determined that the filtration rate variations were not caused by changes in particle size distribution. These results suggest that the differences in filtration rate are due to factors other than size and shape, such as surface chemistry.

Jan 1, 2008

By Rudrajit Mitra, Wesley B. Johnson, Erik C. Westman

The ability to understand stress redistribution within a mine allows greater extraction efficiency with reduced safety concerns. Stress redistribution has been examined at the laboratory scale using ultrasonic tomography and numerical modeling using PFC3D. A data acquisition system was built to obtain tomograms as samples are loaded in uniaxial compression. Limestone samples were loaded to failure. Three-dimensional tomograms of the samples correlate to various stress distributions. The tomograms are compared to analytical and PFC3D results.

Jan 1, 2005

By D. B. Dreisinger, H. J. Sohn, J. S. Sohn, G. A. Kordosky

The transport of lithium through a supported liquid membrane was studied with a mixture of D2EHPA and TBP in kerosene as a mobile carrier. In the flat- sheet supported liquid membrane(SLM) system, experiments were carried out to investigate the effects of concentration of mobile carriers in the membrane solution, hydrogen ion in the feed solution, and temperature on the transport of lithium. Experimental results agreed well with a transport model for permeating lithium across the liquid membrane. The permeation rates of lithium can be explained in terms of diffusion of a Li-complex through the membrane phase. For a practical application of an SLM method, a hollow fiber module has been used and lithium can be concentrated more than three times in 24 hours.

Jan 1, 1993

By C. R. Copeland

Water sprays are a common method used to reduce particulate matter (PM) emissions. Various factors such as wettability, surface area coverage, fine particle engulfment rates, interparticle adhesion forces, suppressant penetration, and suppressant longevity have all been suggested as critical factors in achieving effective PM control. However, it has not been established which of these factors are the most important. Experimental work indicated that suppressant penetration is the most critical of these factors. Suppressant effectiveness was also improved using hygroscopic reagents which retained moisture, improving longevity. Maximizing suppressant penetration and improving suppressant longevity led to an average 86% reduction in PM10 concentrations in laboratory dust tower tests.

Jan 1, 2008

By L. E. Baker, M. J. Leck

OSIRIS is a continuous monitoring system for respirable dust which has been specifically designed for mining and related industries. By using the latest microprocessor technology, OSIRIS provides a sophisticated dust measuring system which is a cost effective alternative to regular gravimetric sampling. The system is certified intrinsically safe for use underground. Up to eight underground OSIRIS sensors can be controlled and monitored by a single IBM PC computer located at the mine surface. This computer provides continuous and instantaneous information about the dust concentrations at the sites being monitored. Information is available in tabular and graphical form. The paper gives details of proving trials of the OSIRIS system in some UK coal mines. During these trials, adjacent OSIRIS sensors placed on the same underground roadway cross-section gave virtually identical results. Throughout a good correlation was obtained with conventional gravimetric dust samples. The OSIRIS equipment proved both reliable and easy to operate. OSIRIS was designed and developed by the Safety Engineering Laboratory of the UK Health and Safety Executive. It is now available commercially and is being

Jan 1, 1987