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By Gerald L. Dollinger, Joseph A. Roby, David Krauter, Kenneth Deering

Three high performance TBM's equipped with large diameter (483mm) disc cutters are currently operating in Norway. This paper summarizes the design philosophy, field performance and ongoing technical development of these cutters. Included are discussions of the early problems encountered with their usage and the solutions to these problems that have been developed. Also included are discussions of the penetration rates and cutter usages observed. From this data it is concluded that high performance TBM's with large diameter cutters can produce significant improvements in both overall performance and in cutter costs under hard rock conditions.

Jan 1, 1991

By M. Cai

Transformation of the measured borehole deformations induced by stress relief relies on the traditional assumption that the rock is continuous and homogeneous. Systematic and quantitative tests were carried out to check the performance of devices commonly used for measuring borehole deformations within different types of discontinuous rock conditions. Test results provide a reliable basis for considering the influence of discontinuities on in situ stress measurement and for choosing the best measuring device for a given rock type and condition.

Jan 1, 1998

By James P. Cooney

What is required for the mining industry to grow and prosper in a politically challenging world? The answer to this can be summarized as “the industry’s three priorities.” The first priority is gaining access to the world’s mineralized jurisdictions. The second is establishing a measure of security and predictability in government treatment of mining. Confidence in the stability of the fiscal and legal framework within which mining operates is necessary to encourage the investment of large amounts of capital in mine development. The third priority is sustaining the industry’s welcome during the long term in those jurisdictions worthy of investment.

Jan 1, 1996

By H. M. Ray

The discovery of the New Lead Belt in the mid-'50s began a search for mill design criteria that is continuously updated. The opportunity to design, construct, and operate four new mills in the span of 20 years provided fertile areas for new concepts. The central theme for design parameters encompassed simplicity, functional, and economic consideration. Ore characteristics for each plant remained relatively constant, providing stable criteria for grinding circuits. Bond index nominally 10-12. Flotation circuit parameters were based upon power application with 10-20% excess capacity built-in to protect recovery. Newer equipment exhibits greater power application efficiency lowering horsepower requirements per ton. Instrumentation was installed to stabilize circuits, protect equipment, and improve products. With ever increasing requirements of higher quality products, environmental considerations, and operating cost pressures, the upgrading of operating procedures is in a constant state of flux. Installation of more efficient equipment, chemical processing, or any other technique would be considered as feasible. Current practice is for St. Joe to design and engineer in-house its own plant design. The exception being detailing of structural steel. It is felt that familiarity with past design criteria serves as a valuable foundation to incorporate changes. Also, direct contact with operator provides specific data, and feedback for constructive criticism that is utilized for defining and correcting problems. The results are in reality an operator's plant with the benefit of advancing technology that meets the demands for improved products without sacrificing the economies of throughput or recovery.

Jan 1, 1977

By L. M. English

A basic model has been developed to help assess methane control needs for longwall mining of coal in gassy areas. Rather than depending upon reservoir and rock mechanic theory, it uses an empirically-determined gas emission rate as an input and operates on the assumption that, within a specific region and zone, gas emissions will be relatively equivalent for uniform incremental volumes of gob created by mining. The computer program divides longwall panels into segments, keeps track of the face advance, and generates emission rates and volumes for both the entire panel and for individual zones within the panel by summing values for all undermined segments. This model can aid the determination of the number, size, and location of vertical wells or other methane control applications that are needed for gob gas control.

Jan 1, 1998

By D. C. Ridenour

The pressure system of ventilation with large diameter bore holes has been very effective in the ventilation of two gaseous mines, the Olga No. 1 and No. 2 Mines in McDowell County, West Virginia. The No. 4 Pocahontas Coal Seam on the Olga property lies 580 feet below the valleys. The seam is very gaseous as well as dry and dusty, which makes good ventilation all the more essential. Irregular and often extensive areas of the coal seam have been replaced with impervious shales and sandstones in "Fault" or "Want" areas. The replacement materials have sealed the methane in the coal seam and thus increased the quantity of gas that must be handled as mining is done. Often the No. 5 Pocahontas Seam comes down to meet the No. 4 Seam at the Faults and considerable methane is sometimes released from the upper seam. The factors mentioned, together with the irregular and unpredictable lateral shape' of the faults, result in long narrow stringers of coal that are very gaseous and difficult to mine. So far as the Olga Coal Company is concerned, the most effective ventilation under the conditions outlined has been the use of large diameter bore holes with a pressure ventilation system. The ventilation of a mine can be accomplished in two fundamental ways. The mine atmosphere maybe reduced below atmospheric pressure by an exhaust fan; or it may be raised above atmospheric pressure by a pressure fan. In either case, the coursing of the air is so planned as to have the haulage and traveling ways on intake air. While the majority of the coal mines in the United States, no doubt, use the exhaust system of ventilation, there are several advantages of the pressure system which are extremely beneficial.

Jan 1, 1960

By C. L. Lin

Linear grade distribution measurements determined from polished sections of randomly oriented particles can be used to estimate the extent of liberation for multiphase particles of specified size. Two techniques, optical image analysis and microprobe analysis, have been used to establish linear grade distributions. Both techniques were evaluated and compared using variable grade samples of products from a copper porphyry flotation circuit. The statistical significance of the linear grade distribution data obtained by optical image analysis was assessed. The average chalcopyrite content of these samples, as determined by chemical assay was used to estimate the variance of the experimental procedure. For a given accuracy, the number of particles required to obtain an unbiased representation of the sample was determined.

Jan 1, 1985

By James B. Lincoln

The Schaffer linear kimberlite complex and Aultman kimberlite diatremes comprise a major part of the State Line kimberlite district of Colorado and Wyoming, which encompasses approximately 200 sq mi (500 km2). The district is located along the eastern flank of the northern Front Range and is underlain prin- cipally by Precambrian granites (approx. 1.4 b.y.) which have been intruded into an older (approx. 1.75 b.y.) metamorphic complex. The kimberlite occurrences are Devonian in age and are related to older Precambrian linear structures. The Schaffer kimberlite complex is a dike or fissure system with enlargements or blows developed at the intersections of cross faults; the two Aultman occurrences are diatremes. Kimberlite within the Schaffer complex is predominately grey to green phlogopite-calcite kimberlite breccia and tuffisitic breccia. Carbonate is abundant in some phases. Inclusions of host granite are common and locally abundant. Upper mantle peridotite, pyroxenite, and eclogite and lower crustal granulite xenoliths are present at many localities. Four phases of tuffisitic kimberlite breccia occur in the Aultman diatremes. These breccias are characterized by high carbonate and serpentine contents. Xenoliths of upper crustal granite, lower crustal granulite, and upper mantle assemblages are abundant locally. Lower Paleozoic sedimentary rock xenoliths are also abundant in the Aultman diatremes but are absent in kimberlite of the Schaffer complex. From 1979 through September 1982, Cominco American, Inc., conducted geologic mapping, petrographic studies, geophysical surveys, geochemical surveys, and auger drilling in the Schaffer-Aultman project area as part of an extensive evaluation program of kimberlite occurrences. Forty bulk samples (approx. 8,000 metric tons) were excavated from the occurrences and then were processed for diamonds at Cominco American's heavy media separation and diamond recovery test plant at Fort Collins, Colorado. Indicated grades from the Schaffer and Aultman kimberlites range from approximately 0.5-1.0 carat per 100 metric tons and as such, the occurrences do not appear to approach economic viability at this time.

Jan 1, 2013

By Matthew Deutsch

A common casualty of modern openpit mine optimization is the assurance that the resulting design is actually achievable. Optimized mine plans that consider value and a bare minimum of precedence constraints do not, in general, translate into practical, operational mine designs that can be used in the field. Ultimate pits may come to a sharp point at the bottom. Schedules may require taking small parcels of material from many disparate areas of the pit in a single period, and grade control polygons may be ragged, narrow and not minable with realistic equipment. In this paper, these three fundamental openpit mine optimization problems are addressed by encoding them as maximum satisfiability problems. Maximum satisfiability provides a useful framework for problems that are nonlinear and may guarantee the optimality that metaheuristics cannot.

By Y. Zhang, M. Yekich, C. Zhou, C. Jobes, J. Galanko, D. Tuchman, J. Srednicki, J. Carr

The continuous personal dust monitor (CPDM) is an essential instrument for working in hazardous environments, is used to monitor real-time coal dust exposure, and is mandated by the Mine Safety and Health Administration (MSHA) for underground coal mines. Researchers from the National Institute for Occupational Safety and Health (NIOSH) found that it is possible for electromagnetic interference (EMI) between a CPDM and a proximity detection system (PDS) to occur. Various approaches have been taken by researchers and manufacturers to address this EMI issue. Administrative controls were recommended to keep the CPDM six inches away from the wearable PDS device. Shielding pouches were made to contain the electromagnetic (EM) emission from the CPDM. Metal shielding was added to major EM emitting components. EMI filtering with large capacitors was introduced to mitigate EMI. Most recently, a novel magnetic-field-cancellation-based approach was developed and achieved remarkable results. In this paper, we provide a comparison between these approaches. The pros and cons of each approach are presented and discussed, so that mining device manufacturers and operators can best evaluate the technology and controls that improve the health and safety of mine workers.

Feb 1, 2023

By T. D. Murphy

In the fall of 1988 it became evident that the accuracy of sulfur forecasts for Monterey Coal's No.1 Mine needed to be improved. In addition, it became necessary to predict if any individual train shipments during a month would exceed a contract sulfur limit. The challenge was to develop a forecasting process that would take into account the variability of the coal in the ground as well as the difference between laboratory and preparation plant sulfur reduction efficiency, and the effects of mining coal with multiple units. This paper describes how geostatistics and simulation techniques were used to meet this challenge.

Jan 1, 1992

By S. C. Carniglia

Bayer-process alumina hydrate becomes in turn the source of a host of special products in addition to the calcines that feed aluminum reduction cells. Though relatively smaller in tonnage, specialty aluminas serve important industrial markets in an exciting and growing variety. Production methods and applications are discussed for: (1) trihydrate as flame retardant in organic materials; (2) high-surface-area transition aluminas as desiccants and scavengers, catalysts and substrates; (3) calcines for industrial ceramics, refractories, and abrasives; and (4) tabular alumina for refractories, bed supports and other uses.

Jan 1, 1977

By W. J. Miles

Diatomaceous earth or diatomite is a sedimentary rock of organic origin that is composed principally of the silicious skeletal remains of diatoms. Diatoms are microscopic single cell acquatic plants that are related to algae. Diatoms first became abundant in the Cretaceous period from about 65 to 135 million years ago. Most of the commercial deposits are of Pliocene through recent age, and are younger than 35 million years. Diatoms are still abundant in present day lakes and seas. The living diatom is supported and protected by two half cell walls or valves united by a connecting band or girdle. These valves are composed of opaline silica extracted from the water in which the diatom lives. After death of the diatom, the silicious remains settle in the lake or sea and accumulate at variable rates approaching several millimeters per year for very active diatom colonies. This accumulation of silicious sediments, after decay of the organism, burial, and uplift, can result in the formation of diatomaceous earth deposits.

Jan 1, 1987

The introduction of nitro-carbo-nitrate (NCN) blasting agents has been one of the most significant innovations in the explosive industry in the last twenty years. The most commonly used blasting agent is a rather narrowly proportioned mixture by weight of 94% ammonium nitrate (AN) and 6% No. 2 diesel fuel oil (FO) that is generally designated as ANFO. Other formulations have been developed but none of these have been as extensively used as ANFO. The relative safety of the nitro-carbo-nitrate (NCN) blasting agents almost immediately suggested bulk loading techniques to obtain economies in materials handling. The first attempt at bulk handling was to pneumatically load boreholes with ANFO. When the initial experiments were made in 1957, it was apparent that there were three problem areas which needed study to minimize potential hazards. These were: 1. Static Electricity 2. Fumes 3. Safe Handling Procedures Since those early days, considerable work has been performed in evaluating these problem areas and in arriving at procedures and recommendations that would provide the required safety. Despite the relative insensitivity of ANFO type products, all normal practices for the safe handling of explosives should be obselved. Smoking should not be tolerated in the vicinity of blasting agents and misfires should be handled in the same manner as a misfire with a dynamite charge. The purpose of this Technical Report is to discuss the problems of static electricity and fumes and the solutions that have been developed. Safe handling procedures have been discussed by the Bureau of Mines and are specified by various state and local regulations. Since regulations vary from state to state, the local, applicable regulations must be followed within the area of their jurisdiction. General information is contained in a U. S. Bureau of Mines report, IC 8179, "Safety Recommendations for Sensitized Ammonium Nitrate Blasting Agents" (1963).

Jan 1, 1973

By P. D. Morrell

Jetbelt is the trade name for the air supported belt conveyor. It does not use troughing rollers. Jetbelt conveyors support the conveyor belt on a thin film of air. The belt rides in a steel trough which has small holes equally spaced along the bottom of the trough. Air comes through the holes under the belt, thereby supporting the belt. The air pressure is provided by a single centrifugal blower that creates very low pressure, between 249 Pa and747 Pa [10" and 30" water column], depending upon the tonnage being conveyed. The volume of air required ranges between .001415 m3/S and .00283 m3/S [3 and 6 CFM] per lineal foot of conveyor. Therefore, depending on tonnage being conveyed, a 304.8m[1000'] conveyor might require as little as 1.415m3/S [3000 CFM] or as much as 2.83m3/S [6000 CFM.]. (See Figure 1) Horsepower requirements can be less than troughing idler conveyors and considerably less than some other forms of bulk conveying. Savings are most significant in horizontal and down hill (regenerative) conveyor designs. Horsepower to lift material, of course, does not change.

Jan 1, 1984

By Francis J. Kiessling

Energy and the conversion of potential energy into alternate forms is becoming a topic of household conversation for a larger segment of the world's population as mankind's desire for products derived from the vast array of technological developments continues to expand. The world's use of steel and the high energy consumption related to the production of steel promotes an awareness of the limitations of existing technology and a search for more economical alternates. Terminology such as (BF) Blast Furnace, (BOP) Basic Oxygen Furnace, (EAF) Electric ARC Furnace, (DR) Direct Reduction, (DRI) Direct Reduced Iron and (FC) form coke is becoming commonplace as alternates are being sought to alleviate the energy crunch. Coke production by various methods was developed as early as the seventeenth century in Europe to replace the disappearing hardwood forests that supplied the initial blast furnace fuel in the form of charcoal. In 1880, the Semet Solvay by-product coke oven design was introduced to the United States at Syracuse, New York, to supply coke for use in the production of soda ash, coke oven gas and its by products as the primary source of many organic processes. Although the Semet Solvay coke oven has not been marketed for decades, these coke oven batteries are in use today producing metallurgical coke, coke oven gas, and related by-products.

Jan 1, 1980

By K. J. Stanaway

Concentrations of minerals between 3.5 and 5 specific gravity such as ilmenite, rutile and zircon in large accumulations of sand constitute "heavy mineral" placers. Two fundamentally different modes of formation characterize "trap" and "bed" placer variants. Smaller and generally higher grade trap placers form during sediment erosion or reworking. Because of their smaller size, they rarely yield economic heavy mineral deposits. They become economic, either if they contain more valuable "heavies" such as gold, or, if they occur within or near much larger but lower grade bed placers. Bed placers form during sediment accumulation episodes in any environment and lithofacies where mineral supply and fluid dynamics are favorable. Three heavy mineral deposits are discussed to illustrate bed placer geology and how trap placers occur with and relate to them.

Jan 1, 1991

By David Yankovich, Geoff Hughes, David Haug, Jon Kaneshiro

"In March 2013, the Sanitation Districts of Los Angeles County began final design of the Joint Water Pollution Control Plant (JWPCP) Effluent Outfall Tunnel project. The new, approximately 7-mile, 18-ft internal diameter tunnel will provide additional capacity and redundancy for the existing 8- and 12-foot diameter tunnels, which were built in 1937 and 1958, respectively. Connections to an existing, active 14-foot arch force main and four existing ocean outfalls ranging from 5- to 10-foot diameter are required. This paper will present geological features for the project, and details of the proposed post-tensioned tunnel liner and associated structures. INTRODUCTION The Sanitation Districts of Los Angeles County (Sanitation Districts) are 23 independent special districts serving approximately 5.3 million residents in Los Angeles County. Seventeen of the districts that furnish sewerage services to the metropolitan Los Angeles area are signatory to a Joint Outfall Agreement that provides for a regional, interconnected system of facilities known as the Joint Outfall System (JOS). The JOS service area is shown in Figure 1. The JOS serves an area that encompasses 73 cities as well as unincorporated territory and parts of the City of Los Angeles. The JOS provides wastewater collection, treatment, reuse, and disposal for residential, commercial, and industrial users, and it includes seven treatment plants, the largest of which is the JWPCP, located in the City of Carson. Currently, secondary treated effluent is conveyed through two 6-mile long parallel tunnels, 8- and 12-feet in diameter, from the JWPCP to a manifold structure located at Royal Palms Beach, near White Point on the Palos Verdes (PV) Peninsula, from which four seafloor outfalls extend offshore. The two main outfalls, 90- and 120-inches in diameter, extend approximately 1.5 miles offshore and discharge at a depth of approximately 200 feet below sea level. The other two outfalls, 60- and 72-inches in diameter, are used for additional capacity during heavy rain events and extend a shorter distance offshore and discharge at shallower depths. A schematic of the existing system with the proposed tunnel and structures is shown in Figure 2, and the proposed 18-ft diameter tunnel alignment is shown in Figure 3. Both existing tunnels and main outfalls are required to be in service at all times."

Jan 1, 2016

By R. K. Young

Producing a sound plant design for a major project requires hundreds of engineers and many drawings. Economical accomplishment of this task is based upon careful and orderly organization of the design team so that at all times there is a complete and workable staff but at no time a surplus of costly talent. This paper will describe the various stages in the development of plant design which normally follow the laboratory and pilot plant investigations discussed in other papers today. An outline of the procedures used in the assembling of a project design group, within an established engineering organization will be presented. Actual procedures may vary according to the size and character of the plant, the special requirements of the owner, and the make-up of the engineering organization performing the design, but most of the points covered will be found to be basic to any plant design project.

Jan 1, 1960

By J. W. Butwell

Anaconda has been active In the Bingham mining district near Tooele, Utah since 1914 when the company acquired International Smelting & Refining Co. Over the years both custom ores and complex Pb-Zn-Cu ores from the district were milled and smelted at International. In 1948 Anaconda acquired the property that covers the present Carr Fork ore body. Since that time active exploration took place in the 50's followed by detailed geological evaluation in the 60's. Convinced that high grade Cu deposits would be found at depth, a deep drilling program commenced in the late 60?s, with intersection of the ore zone in 1969. Following extensive deep drilling in the early 70?s, a feasibility study was conducted in 73-74 with board approval given Sept. 6, 1974. The 9,000 t/d mine-mill complex was budgeted at $217 MM over a 5 year schedule with start-up in Sept., 1979. The following discussion includes the concentrator and surface facility portion of the budget or approximately $60 MM of the scope. Special emphasis will be made on equipment selection and layout.

Jan 1, 1980