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By James C. Fowler

The use of ground-probing radar as a reflection mapping tool has expanded greatly in the last few years. This tool can now be used to produce near surface information which is very useful to geotechnical engineers. Using the lightweight field equipment now available, it is possible to use the radar within mines and tunnels to obtain information which may impact the safety and production of these operations.

Jan 1, 1979

By Gerry Norton

The purpose of this paper is to make the most complete assessment of coal cleaning methods, both process and equipment related to modern-day production and environmental requirements. In order to achieve this primary objective, a number of interdependent aspects of coal cleaning technology require evaluation and analysis. 1.0 CLASSIFICATION OF SEPARATION PROCESSES Processes and cleaning equipment can be categorized according to the important parameters of 1) mechanics of separation, 2) size range application, 3) range or variance in accuracy of separation related to 2) above, and 4) feed-size ratio affecting 3) above.

Jan 1, 1977

By Robert C. Freas

Lime, the versatile chemical is, generally speaking, a calcined or burned form of limestone commonly known as quicklime, calcium oxide or, when water is added, calcium hydroxide or slaked lime. Almost 40 different lime products are available, a fact which has contributed to the rather loose use of the term lime as well as to confusion and misunderstanding. The term is frequently, albeit erroneously, used to denote almost any kind of calcareous material or finely ground form of limestone or dolomite. Lime is made from high calcium or high magnesium limestone, generally having a minimum of 97% combined carbonate content. Normally, high calcium lime has less than 5% MgO. When the lime is produced from a high magnesium limestone, the product is referred to as dolomitic lime. Calcination/Hydration Calcination, or the production of lime, has its origins in the earliest days of alchemy, with the general reaction class having been identified in an Arabic text printed in 1000 AD. It was much later, however, in the mid-1700s to the mid-1800s before this basic reaction became understood from scientific perspective. The pro- duction of lime has been so basic and simple that its underlying scientific principles have over the years received only intermittent investigation. Rather, much of the thought and inquiry has been directed toward the development of kilns. Thus, it has only been in the last 25 to 30 years that lime has received any concentrated scientific investigation relative to the thermodynamics and kinetics of the calcination and hydration reactions. Particular emphasis has been focused upon energy consumption and fuel efficiency. Calcination refers to a broad class of reactions, of which the limeflimestone reaction is just one, wherein a substance is heated to less than its melting point, resulting is a weight gain or weight loss. In the calcination of limestone to produce lime, the basic chemical reaction is as follows: [ ] While there is nearly universal agreement bout the equilibrium conditions related to the limestone/lime reaction above, there have been numerous and varied calcination models developed for the reaction. Recent investigations have resulted in the development of the model shown in [Fig. 1]. From this model it can be seen that calcination is a function of both temperature and CO, pressure. It does not, however, provide any indication of the rate at which the reaction takes place. Calcination is strongly time variant with different limestones. In a very broad sense this relates to the fact that the calcination reaction starts on the exterior surface of the limestone and then proceeds toward the center. As the calcination reaction takes place, the CO2 released at the interface must make its way through the lime to the exterior surface. Since calcination is limited by gas diffusion to the surface of the partially calcined limestone, the natural impurities in the stone, differences in crystallinity, grain boundary chemistry, density variations, and imperfections in the atomic lattice all play a significant role in calcination rate. Therefore, the suitability of a given limestone as a source material for lime production can be determined only after completion of adequate burn tests designed to evaluate the various limiting factors. When a coal-fired kiln system is considered, the entire process of calcination is made even more complex by the introduction of additional chemical constituents into the calcination environment. The reader is referred to the references for a more detailed description of the complete calcination reaction and the differences inherent between differing kiln systems. In the foregoing discussion it was noted that CO2 is released during the reaction. This release results in a 44% weight loss during the complete calcination of a high calcium limestone, or a 48% weight loss for a highly dolomitic limestone. The trade term for this weight percent loss is loss on ignition, or LOI. This weight loss is frequently used as a measure of the completeness of calcination. Because the calcination reaction is chemically reversible, quicklime or burned lime is frequently referred to a being highly reactive, or unstable. The more stable form of lime, hydrated lime, is commonly preferred and generally specified by the user. Hydrated lime is obtained by adding water to quicklime to produce a dry, fine powder. Quicklime's affinity for moisture is then satisfied, although it still retains a strong affinity for CO2.

Jan 1, 1994

Micro-computers have made it practical to install a high-speed acquisition system to collect data from a longwall face in near real-time. By simultaneous data analyses using neural networks and fuzzy sets, information regarding longwall mining performance and underground behavior can be provided and forecasting longwall instability and detecting geological anomalies is feasible. This paper presents details of the application of neural networks and fuzzy sets in developing on-line evaluation of longwall roof behavior. Techniques for interpreting longwall shield pressures and characterizing roof conditions are discussed.

Jan 1, 1996

By Z. J. Hladysz

The Hladysz Rock Tester was developed at the South Dakota School of Mines as a portable rock strength tester. The hand held device is placed against a rock surface and struck by a hammer. The impacted force causes a steel ball in the device nose piece to indent the rock and simultaneously indent a standard steel bar also contained in the nose piece. By comparing the two indented diameters the compressive strength of the rock can be calculated using laboratory determined correlation coefficients.

Jan 1, 1984

By A. Warren Wilson, Hugh R. Wilson

This paper describes the evolution of the Waste Management Program at the Lupin Mine through the years 1982 - 1986. Echo Bay Mines' Lupin Mine is located on the western shore of Contwoyto Lake in Canada's Northwest Territories about 80 km. south of the Arctic Circle. The gold mine commenced production in 1982 and the Waste Management Program was based originally on the total containment concept. Due to an expansion of the mill circuitry and increased throughput, it was apparent that total containment was no longer applicable and therefore studies were undertaken to characterize the tailings, to evaluate the effectiveness of natural degradation of contaminants in the tailings pond and to determine what additional treatment steps would be necessary to meet the requirements of the mine's Water Licence. These studies indicated that arsenic and cyanide concentrations in the tailings pond decant water would not meet Water Licence discharge limits unless certain measures were under taken. As a result of this work, in late 1984 a decision was made to create a two-ponds-in-series system and the necessary civil work was started in 1985. In addition, a series of dykes were constructed to contain the solids portion of the mill tailings in a confined area of the first pond. To remove cyanide, the ponds are operated in a sequential fill and decant mode to take maximum advantage of natural degradation. For arsenic removal, a chemical feed system was constructed for iron salt addition to the decant stream from the first to the second pond. Decanting of the ponds is accomplished by means of a series of 500 mm (20 inch) Sclairpipe syphons.

Jan 1, 1987

By Dale C. Matthews

Pressure oxidation of refractory gold ores is becoming more popular in our environmentally sensitive society. This paper will discuss some specific process problems and solutions involved with starting up and operating an autoclave circuit.

Jan 1, 1991

By D. Malhotra

Most primary-molybdenite producers use a selective-flotation process in which molybdenite is floated from the ore while other sulfide and non-sulfide gangue minerals are depressed in the same step (Figure 1). The process was developed at the Climax mill. Reagents used in the rougher-flotation stage include vapor oil (collector), syntex (surfactant), pine oil (frother) and occasionally sodium cyanide and Nokes reagent (depressant). Rougher concentrate is upgraded by cleaner flotation to produce market-grade molybdenite concentrates. Reagents used in the cleaner flotation stage are Dowfroth 250, vapor oil, sodium cyanide and Nokes reagent. The development of the flotation reagent scheme at Climax and the role of the reagents have been well described by Born, et al, (1976) and Malhotra, et al, (1976, 1977a, 1977b, 1977c, 1980). The hydrocarbon collector, vapor oil, accounts for approximately 50 percent of the total molybdenite-flotation reagent cost. Because vapor oil sources are limited, and the cost of vapor oil has increased significantly over the last decade, several studies have been done to evaluate alternate oil-based collectors and/or blends of collectors which would produce similar metallurgical results at a reduced cost, or increase the overall molybdenite recovery at the same cost (Smit and Bhasin, 1983; Hahn, 1969; Smith and Bhappu, 1971). The approach taken in the present study was to evaluate alternate non-oil based collectors and collector systems that are less expensive than vapor oil.

Jan 1, 1985

By J. G. Pippenger

The Coteau Properties Company's Freedom Mine is a surface lignite mining operation utilizing large draglines, trucks and shovels, tractor-scrapers, and bulldozers to uncover a single coal seam. In 1989, a work order system was instituted to record data by equipment type, cost, productivity, and distance, and to provide historical information for planning the most efficient and economic use of each equipment type in the mining operation. This report explains how the work order system was initiated, what data is tracked, and how the data is utilized for equipment and project scheduling.

Jan 1, 1994

By N. Dahmen

The Robbins Mobile miner has been in development for more than ten years. Two machines have been trialed in mining environments. While day to day performance to date has fallen short of the levels anticipated, instantaneous performance has been impressive for given rock conditions and continues to encourage further development. The Pasminco mobile miner has been committed for a 1.8km main decline extension at Broken Hill. M.I.M. Holdings, parent company of Mount Isa Mines, owner of the first mobile miner, are considering a new machine for McArthur River. Robbins, Pasminco, and The Centre for Mining Technology and Construction have, joined forces to accelerate development of .mechanical rock cutting techniques in general, and of the Mobile Miner in particular.

Jan 1, 1995

By J. Mastoris

The determination of the surface area that may be impacted by underground mining is an important consideration in subsidence engineering. A number of parameters have been utilized to identify this influence area, most notably the angles of draw and break. This paper discusses the implications of selecting an appropriate "damage angle" for defining a potential damage area due to mining, within which surface structures may be impacted. Furthermore, the influence of both mining and geological factors (i.e., mining width, depth and overburden lithology) on this angle is examined using the Surface Deformation Prediction System (SDPS) software. Finally, recommendations are given for applying these concepts in subsidence control.

Jan 1, 1995

By John E. Caffrey

United States Steel Corporation began mining coal in southern West Virginia at the turn of the century, and until the late 40's production was confined to underground mines. Surface mining was initiated in our southern West Virginia -holdings as a means of recovering coal that could not be obtained by underground mining methods. After observing and evaluating surface mining methods employed by other companies, some of which operated on lands of U. S. Steel on a lease basis, we undertook the establishment of a surface mining operation. Our method, as, initiated in the early 50's, remains basically the same today. Variations have come about primarily by equipment modifications. The method consists' of a pioneer cut to establish the coal outcrop, a drill bench for drilling, blasting, and removal of the overburden from the top of the coal. The land is rugged except for the flood plains of some of the larger streams. The mountains have steep slopes, averaging 30 degrees, with relatively sharp ridges and very narrow valleys,. Geologically, the coals_ lie in the Pocahontas formation of the Pottsville group in the Pennsylvanian system. This means that the coals in our area of operation lie at the base of. The coal measures in the Appalachian range. The coal that we have mined is primarily the Pocahontas nos. 3 and 4 seams. We have mined negligible amounts of other seams in the Pocahontas groups above the no. 4 seam. The Pocahontas no. 3 seam, which is the lowest mineable seam geologically in this area, lies anywhere from 700 feet below: the valley floor up to 400 feet above the floor. This is occasioned by the Anticlinal formation which gives us grades Of about 9% at the anticline, decreasing to about 1 to 1-1/2% on the extreme flanks. We have the opportunity to engage in surface mining where the coal seams intercept the surface above the valley floors.

Jan 1, 1972

By R. J. Sweigard, R. V. Ramani

The effects of postmining land use planning are addressed in this paper. These effects may include savings in reclamation costs and increased value of reclaimed land. However, this may result in greater planning costs and possible delays in production. Therefore, an economic analysis was undertaken in an effort to determine the importance of each potential result and to quantify the overall economic impact of postmining land use planning. A discounted cash flow analysis was performed using a surface mine cost model to analyze the sensitivity of selling price to changes in various postmining land use planning parameters. As a result of this analysis, it was determined that the profitability of a project is most sensitive to delays in production, particularly if the delay occurs after major investments have been made. Many methods have been proposed for evaluating postmining land use alternatives (Sweigard and Ramani, 1981). Both quantitative methods, such as benefit-cost analysis (Brock and Brooks, 1968), and nonquantitative methods have been proposed. The application of one specific analytical method is pursued in this paper.

Jan 1, 1988

By Xiaoting Li, Richard Adasiak, Benjamin Mirabile

Pumpable J-Crib stopping walls and Jennmar high-strength (HS) stopping panel walls are widely used for resisting high-ventilation air pressures and roof support in underground mines due to their installation efficiency, convergence allowance, and better performance than traditional concrete block stopping walls. Based on the different entry dimensions and required maximum ventilation air pressures of up to 36-in. water gauge, 24-, 27-, 30-, and 36-in.-diameter pumpable J-Crib stopping walls, or 18- to 30-in. thick Jennmar HS stopping panel walls can be designed, and their support capacities and convergence allowances are evaluated for better roof control. Pumpable J-Crib stopping walls consist of 0.187-in.-diameter steel wire reinforced, JCrib material-filled bags, and non-wire-reinforced filler bags in between. Jennmar HS stopping panel walls consist of two, 20-gauge (0.04-in.-thick), galvanized, cold-formed steel panels with J-Seal materials pumped in between. Based on the fundamental structural design principles and specifications of ACI 318-19(22), the compression and flexural strength, and shear resistance of the walls can be checked to be compliant with the codes and specifications following the load and resistance factor design (LRFD) method. Specifically, the 0.187- in.-diameter steel wires in the pumpable J-Crib walls and 20-gauge steel panels in the HS stopping walls are integral parts of the walls and are considered to effectively confine the J-Crib or J-Seal materials. These steel elements play a significant role in reinforcing and improving the strength or support capacity of the stopping walls from a structural design perspective. Because of the high ductility of low-density J-Crib/J-Seal materials and steel elements, these walls are good at accommodating or absorbing the roof convergence (≥5% entry height), which cannot be matched by a traditional concrete block stopping wall (Figure 1). Based on the successful design and application of these stopping walls in different mines for improving roof stability and avoiding the air leakage, the authors have formulated the design methodology and verified independently by the finite element analysis (FEA) simulation technique. This design methodology combines the fundamental structural design principles with specific wall dimensions and material properties, facilitating mine engineers and government agencies to understand the in-depth working mechanism of these stopping walls.

Jul 1, 2023

By D. S. Bird

The Kennecott Utah Copper Modernization Project, initiated in 1986, was directed to provide an expansion and modernization of mining and process facilities at the property's Bingham Canyon Mine and ore concentrators. Major components in the project included installation of an in-pit ore crusher, transfer conveying system, and construction of a new copper ore concentrator with a design capacity basis of 70,000 tonnes/day. The Copperton Concentrator was commissioned in February 1988. A principal feature of the plant is the grinding circuit, comprised of three identical lines, each consisting of a 10.37 m (diameter) by 4.57 m (length) Semi-Autogenous Grinding (SAG) mill and two 5.54 m (diameter) by 8.62 m (length) ball mills. The SAG mills are driven by two variable-speed 9,000 kW DC motors coupled through a clutch-pinion gear-ring gear assembly. The ball mills are driven by 4,125 kW synchronous motors coupled through a typical clutch-pinion gear-ring gear system. The expansion and particularly the Copperton Concentrator performance was so successful that by early 1989, management began examining options to further expand production capacity. With regards to the concentrator, numerous alternatives were considered, ranging from installation of a grinding line similar to one of the existing lines, to a "super" line consisting of a 12.8 meter (diameter) SAG mill and a 20,000 kW motor with a capacity of 50,000 tonnes per day. The technical and economic analysis of the various scenarios indicated that one "large" 11.0 meter (diameter) by 4.88 meter (length) SAG mill with a production capacity of 32,000 tonnes per day and a 12,000 kW drive would be optimum. The key question to be answered in the project was whether to continue with the pinion-ring gear combination, or install a gearless drive. The following paper outlines many of the items that were evaluated in the mill selection process followed by actual plant performance, and a discussion of ongoing plant continuous improvement projects.

Jan 1, 1995

By Al. Valero, A. Domínguez

This paper appraises the energy requirements for mineral production through an exergy approach taking into account the long-term decline in ore grades. In this context, the exergy required for restoring resources from the dispersed state of the so called Crepuscular Earth into the physical and chemical conditions in which it was delivered by the ecosystems in light of the available technology, is known as exergy cost. The exergy cost is the point of reference in order to evaluate in a single variable, characteristics such as composition, concentration (ore grade) and the state of technology. The ratio between the exergy cost and the minimum thermodynamic cost required to accomplish the same process is called unit exergy cost and provides a measure of the irreversibility of the analyzed processes. Otherwise, the ore grade is one of the main issues which affects directly the costs associated with mining the ore. Hence, the unit exergy costs to produce minerals from progressively lower ores grades by the current technology is analyzed. The unit exergy cost curves are presented for some important minerals such as aluminium, chromium, cobalt, copper, gold, lead, manganese, nickel and zinc, in order to know the trend when the ore grade decreases.

Jan 1, 2011

By Edward M. Downs

This paper is a brief review of the lubrication requirements of enclosed gearing on earth moving equipment, particularly as they apply to intermediate and large draglines and shovels used in open pit mining operations. It discusses the requirements of spur, helical and herringbone gearing in both horizontal and vertically mounted applications. The effects of base stock, oil viscosity, additive treatment, quantity of oil and method of application are considered. In addition, a newly designed circulating oil system for enclosed swing gear cases and the reasons for its development are discussed.

Jan 1, 1968

By E. J. Wasp

An upsurge of interest in slurry pipelines to move coal from Wyoming, Montana, and Colorado to markets in the southwest, west, midwest and northwest has recently developed. Specific pipelines have been proposed to serve these markets; the routes of these lines are depicted in Exhibit I. It is, therefore, timely to discuss some technical aspects of the terminal facilities for these western coal pipelines. The discussion will be based on experience with the Ohio and Black Mesa pipelines as well as detailed planning and testing for a proposed 1,000-mile system from Wyoming to the middle south area. The economics of the pipeline terminal processes are heavily depend¬ent on site, type of process used, and other specifics of the situation. However, the following approximate breakdown of costs for a 1,000 mile, large capacity pipeline will be useful for orientation purposes. [Water supply 4 Coal cleaning 5 Feed preparation 10 Slurry transportation 72 Dewatering terminal 9 100%]

Jan 1, 1976

By Heinz C. Dittmar

The phenomenon of radioactivity has been known since the turn of the last century. Scientists of many nations, intrigued by the strange effects of radioactivity, have engaged in research to probe the heretofore presumed, but largely unknown world of atomic structures and subatomic- particles. A theory evolved of splitting the atom, thus providing insight into the structure of matter and opening the way to possibly create new materials. Many years of effort culminated in the first chain reaction in 1942. The beginning of the atomic age was drastically demonstrated by the flash of the large scale chain reaction of the first atom bomb. It was actual proof of the incredible energies contained in matter.

Jan 1, 1966

By R. F. Winkle

Shortly after World War II, considerable impetus was given to use of truck haulage in open pit mines by the manufacture of large off-highway trucks. Mine management was quick to utilize this more flexible approach to open pit operation and in the ensuing years much time and energy has been spent to improve the basic concept. Dramatic progress has been made in drilling, blasting, loading and hauling with much emphasis placed on equipment improvement. In general, haul roads in open pit mines and quarries have received rather perfunctory treatment in studies of surface mining operations. Their importance to the successful pit operation requires more than a brief sentence saying, "Good haul roads must be maintained." Haulage costs account for approximately one-third of total mining costs including general costs and about 90 percent of the total loading-haulage cycle time is consumed in travel, hence, good haul road planning, construction and maintenance are mandatory for a viable operation.

Jan 1, 1976