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By W. M. Snoddy

The Montana Tunnels diatreme is a low-grade polymetallic ore body containing economically mineable quantities of gold, silver, lead, and zinc. Widely varying gold grades combined with the general erratic nature of the mineralization create a complex sampling, assaying, and ore control problem. In order to maximize productivity and profitability, a variety of procedures have been used. These include differing sample size, frequency and method. In addition, assay techniques have been adjusted and refined to fit specific requirements, the result of which is an accurate, functional sampling and ore control system.

Jan 1, 1991

By Robert J. Timko, R. Lincoln Derick

The Bureau of Mines evaluated the integrity of escapeways in a three entry underground coal mine. A center conveyor belt entry (secondary escapeway), was flanked by an intake (primary escapeway) and a return entry. Diesel equipment was used throughout the mine for material and personnel haulage. A carbon monoxide monitoring system, tied to a data recording computer on the surface, was deployed throughout the belt entry and at selected sites in the intake and return entries. Previously, the company had a fire of unknown origin in another mine, which prompted an interest in the performance of their escapeways. An initial, qua1itative evaluation was performed by burning approximately 14 kg of coal at the mouth of the intake entry. The first test was followed by a similar burn at the mouth of the belt entry. These initial trials showed a high quantity of leakage between entries. In several follow-up evaluations, simulated fires, using a tracer gas, were set in the intake and belt entries. Tracer gas concentrations were obtained in all entries at four different underground locations. The results of these tests showed that permanent stoppings could not guarantee isolated, contaminant-free escapeways.

Jan 1, 1989

By S. Hearn, S. Boskovic, A. Smethurst

"The digestion of minerals in strong acids or at elevated temperatures can result in the release of large amounts of silicic acid which can polymerize in solution to form colloidal silica and gels. Colloidal silica can cause a number of problems including interfering with flocculation, initiating crud formation in solvent extraction (SX), decreasing SX extraction kinetics and increasing SX phase disengagement times. Huntsman’s POLYSIL® polyether coagulants have a “lock and key” relationship with the surface of colloidal silica to help lower the concentration of these particles in solution, improve process efficiency and reduce reagent losses by minimizing crud formation. This paper investigates some of the issues caused by colloidal silica in hydrometallurgy processes and illustrates how the use of POLYSIL® coagulants has helped to improve process outcomes. INTRODUCTION Coagulation differs from flocculation in a number of ways. Coagulants are relatively small molecules that modify the surfaces of fine particles, weakening repulsive forces between them and allowing particles to stick together, while flocculants are generally molecules that are large enough to bridge the boundary layers between the particles. With flocculation, addition rate and mixing all make a difference to the flocs formed. Coagulation, on the other hand, is an equilibrium process. With coagulation it is only necessary to achieve good mixing, and coagulates will form as Brownian motion pushes the particles into each other. In real systems, this process is complete within seconds. Huntsman’s POLYSIL® polyether based coagulants have a strong affinity with the surface of colloidal silica formed by the polymerization of silicic acid. While silica found in minerals has a low aqueous solubility, large amounts of silica as silicic acid can be released as these minerals are digested in strong acids at elevated temperatures. The solubility of free silicic acid is about 150 ppm under pH conditions typical in acid leach environments (1), so the bulk of the silica will polymerize in solution to form colloidal silica. Colloidal silica can pass through a hydrometallurgy process without affecting any of the operations. However, it can cause a number of problems. These include gelling in a leach, interfering with flocculation or crystallization, initiating crud formation (2,3,4), decreasing extraction kinetics and increasing phase disengagement times (5,6) in solvent extraction. In these cases, coagulating the silica with POLYSIL® coagulants can reduce or eliminate the problem by enabling these particles to be flocculated and removed from the solution."

Jan 1, 2015

By L. Adler

When systematically compared to other engineering fields, mining engineering is distinctive in 1) having a total systems concern. 2) dealing with encumbered space and 3) requiring full spectrum practice. The total systems concern results from having to design and then co-ordinate in space and time several major systems: excavating and bulk handling, ground control, life support and normal support. This requirement favors a generalist rather than a specialist approach. In coping with encumbered space especially in underground coal mining, the uncertainties of geologic conditions are compounded by tightness, roughness, remoteness and hazards. Into this difficult setting the total systems * complex is "stuffed," adding congestion and interference. Because of significant ground deterioration a flexible "rapid in-out" approach is usually vital to mining. Full spectrum practice arises from the need to manage, as well as to plan and design, a labor intensive operation. Since market conditions can also fluctuate most aspects of administration are needed in many respects, mining engineering functions relative to civil engineering in a way similar to industrial to mechanical engineering, with encumbered space being crucial. On this basis stress is placed on: 1) personal relations, 2) field work and 3) entrepreneurship, viewing time as money. Specific recommendations for improving engineering, safety and management and leadership are made. Since most new deposits are marginal, by applying these recommendations with high technology they could possibly now be mined on a widespread basis.

Jan 1, 1985

By Hajime Kitamura, Nobuharu Isago, Yuta Yamanishi, Kosuke Kawata, Hiroshi Yagi, Akira Matsuoka

Mountain tunnels are generally considered to be stable during earthquakes, however, it is known that the portal areas are prone to seismic damages. Characteristics in portals such as the location of the slope, modulus of ground deformation, and the change of overburden are different for each tunnel, and damage degrees are unclear. In this study, we reproduced the seismic behavior to investigate the effect on the tunnel portal by considering some parameters above, using simple static model tests and numerical analysis. As a result, the conditions of the slope condition and minimum distance from slope was confirmed to influence on the mechanical behavior of the tunnel portal during earthquakes.

Dec 1, 2022

By Jodie Robertson, Isabel Barton, Cristian Caro

Prior to mining, all rocks contained in a mineral deposit must be placed in one of several categories known as ore types. Each ore type describes a different way that the rock will behave in processing. The ore type determines which process stream a particular mined unit will be sent to, sets expectations for process engineers and metallurgists, and forms the basis for recovery predictions and production estimates. At first, ore types are assigned mainly by geologists based on visible geological criteria (dominant ore mineralogy, estimated grade, rock type, alteration type). As metallurgical tests are carried out and process data accumulate, the resulting criteria may be factored into the ore typing process, typically as assays and recoverable metal using the relevant process(es). Other variables may also be incorporated into ore typing at operations if they are particularly important, such as grindability, preg-robbing, gangue reagent consumption, and the presence of especially deleterious minerals such as talc or smectite. The mine operation department may also redefine ore types and/or process destinations based on economic criteria. A “best” ore type is designated that (in theory) best describes how the rock will behave in processing. Codes representing this ore type are entered into the drill hole database, then interpreted on cross sections and level plans, and finally added to the block model. Ore types are iteratively reexamined and adjusted over the life of a project. Major difficulties in effective ore typing are (1) lack of communication between geologists and metallurgists, (2) the imprecision inherent in imposing clean categories on messy natural systems without discrete divisions, (3) the need for ore types to provide useful information for a wide range of processes, (4) difficulties in scaling up laboratory test results to mine production, and (5) conflict among geological, metallurgical, and economic criteria for ore typing.

Nov 8, 2023

By A. Probst, N. Moores, J. A. Finch

In 1994, McGill University and INCO Ltd. (Sudbury operation) initiated the transfer of technology originally developed to detect levels in equipment ranging from flotation columns to thickeners. A conductivity probe was installed in a concentrate thickener to monitor the mud line and the solids load. The probe consisted of a vertical tube with 32 equally spaced electrode rings connected in pairs to give 31 conductivity cells. Conductivity was measured as a function of depth to produce a conductivity profile. From the conductivity profile, the mud line and the percent solids can be inferred. The probe was installed in October 1994, and it has been successfully detecting profiles since then. This paper includes a description of the incidents that occurred and the experiences gained during this technology-transfer process. Discussed is probe installation and startup; software modifications to accommodate both operating conditions and the needs of the operators; and calibration procedures to adjust to changes in performance as a consequence of long-term use. Also included are preliminary observations of the still-in-progress last stage, i.e., signal interpretation and use to facilitate operation, particularly by providing early reaction to upstream disturbances.

Jan 1, 1999

By J. M. Goris

The U.S. Bureau of Mines, in cooperation with the Homestake Mining Co., and the University of Utah, is conducting a field demonstration to evaluate the behavior of rock masses supported with cable bolts. One of two rock masses being studied is supported with both conventional and birdcage cables. This rock mass is located between the 6500 and 6650 levels of the 45-4BN stope. 21 ledge. The second rock mass is the hanging wall of the D-limb stope between the 3500 and 3650 levels near the Ross Shaft and is supported with conventional cables. The primary objectives of the project are to monitor the behavior of the two rock masses during mining using extensometers and cable support strain gauges, after which the rock will be modeled using the finite-element code UTAH III. Field data will be used to verify the modeling. In addition. a comparison between the effectiveness of conventional and birdcage cables will be made.

Jan 1, 1991

By Robert Dimock

The successful management of large dispersed mineral operations is dependent upon accurate and timely decision making. The plant locations providing the data to support the decision making process are generally separated by distances which elongate the time required to accumulate the data at a central focus. The need exists to examine operational data in context with total mining operations, and in relation to target projections and historical trends. The use of microcomputers for local information tasks is an established capability. Grouping microcomputers into local-area networks is rapidly becoming established. Interconnecting multiple local-area networks to provide a free flowing stream of information between all operational locations of a mining enterprise is possible with use of some emerging technologies. The benefit of the potential interconnections and rapid transfer of information can readily be seen from a production reporting perspective. Numerous other advantages exist' by providing routing to enable a workgroup to be established between separated work functions.

Jan 1, 1989

By Clayton Vernon Deutsch, Marcel Antônio Arcari Bassani, João Felipe Coimbra Leite Costa, Vanessa Cerqueira Koppe, Pedro Henrique Alves Campos

Traditional linear approaches oversimplify the complexities of ore blending. Adopting nonlinear blending models in mining and mineral processing is critical to enhancing prediction accuracy and allowing optimization regarding nonadditive variables, such as metallurgical recovery. This study implements a simulated annealing algorithm in short-term mine planning that seeks to optimize the metal recovery by considering how to blend the ore in the mine better. Two nonlinear metallurgical recovery models are used as inputs to the algorithm to represent synergistic and antagonistic blending. The results of the case study demonstrate that the optimized schedule exhibits improvements in both blending behaviors when contrasted with conventional linear-based scheduling plans.

Jan 1, 2025

By Charles M. Hauptman

The Karst asbestos deposit, discovered seventy years ago, is 32 miles south of Bozeman in southwestern Montana. The deposit is about one-half mile west of the Gallatin River which flows in a deep V-shaped valley flanked on either side by rugged mountains. The Madison range is west of the river and the Gallatin range lies to the east. A busy all-weather highway, U.S. No. 191, follows the river and is the major north-south route between Bozeman and the Gallatin valley to the north and Idaho and the west entrance of Yellowstone National Park to the south. The asbestos deposit is a large body of serpentinized peridotite in which anthophy11ite.occurs, both as distinct veins and as a disseminated mineral in the peridotite mass. The known exposures of the asbestos-bearing rock occur on a steen south slope at an "elevation of about 7000 feet, an elevation 'which is about 1200 feet above the Gallatin River. Over the years, a number of small companies have attempted to exploit the Karst asbestos deposit without continuing success. The present operator, Galaxy Mining Corporation, has attempted a systematic approach to the problem by utilizing geologic and engineering surveys to determine the economic and technical feasibility of a mine and plant to produce a finished asbestos pro-duct. The results of this work indicate a high probability of success for the project. However the company now faces that dilel1lJllB so common to the non-metallic mineral business; that is, whether to continue a research program of further mineralogical and technological studies in conjunction with detailed market surveys or to rely on the work done to date and embark on a pilot progril1n

Jan 1, 1971

By James Parkes

"The proposed Baltimore Red Line light rail system includes a 3.4 mile downtown tunnel (DTT) with five underground stations. The design of the underground stations involved overcoming several challenges, including limited right-of-way, high groundwater and uplift pressures, and metamorphic rock within the station depths. An innovative design was developed to maximize the internal station space while minimizing cost. The station designs use slurry walls for temporary and permanent support and groundwater control. Depths within rock are supported with cast-in-place concrete walls, the thickness of which are minimized through the use of permanent rock anchors for support of the rock mass and slurry wall toes. Permanent tiedown anchors are used for uplift resistance, which minimizes the station depths, volume of rock excavation, and the volume of deadweight concrete. Design considerations regarding individual elements and overall integration of the slurry walls, CIP walls, and multiple anchor types are presented.INTRODUCTION The Baltimore Red Line (BRL) project is a proposed light rail transit line for the Maryland Transit Administration (MTA) that runs east to west through Baltimore City and County. The project includes the Downtown Tunnel (DTT) consisting of 3.0 miles of twin running tunnels, two portals, five underground stations, and a pedestrian tunnel, as shown in Figure 1. The tunnels have an outside diameter of 21.8 feet and are designed to be mined using pressurized face tunnel boring machines (TBMs). The stations, portals, and the pedestrian tunnel are designed as cut-and-cover structures using slurry walls (concrete diaphragm walls) for both temporary support of excavation (SOE) and permanent structural walls. The dimensions of the five underground stations are summarized in Table 1. Design challenges included limited right-of-way (ROW), challenging soils conditions, strong metamorphic rock within the station depths, and high groundwater conditions. The final station designs included innovative use of slurry walls, tieback anchors, rock anchors, and tiedown anchors."

Jan 1, 2016

By Byron C. Hardinge, Michael Sokaski, Paul F. Sands, W. Loring III Mc Morris, David J. Akers

INTRODUCTION In the early days of coarse-coal cleaning by the dense-medium process in Europe, loess was one of the materials used for medium solids. Newly developed cyclones were used to reclaim and thicken the loess suspension. On occasion, when the cyclone thickener at the Maurits mine in the Netherlands plugged, the overflow was found to be filled with clean coal free of impurity. From this observation stemmed the concept of the cyclone as a cleaning device. Development took place during World War II in the laboratory of the Dutch State Mines under the direction of M. G. Driessen. A 15-tph (13.6 t/h) pilot plant was in operation in the laboratory by 1945, when, in September, Driessen made the first public disclosure of the process in a paper presented to the Institute of Fuel in London.51 In April 1945, operation of this pilot plant was observed by H. F. Yancey, who was so impressed with the potential of the cyclone process that, on his return to the United States, a research program on the cyclone was immediately started by the US Bureau of Mines (USBM). This work led to an AIME paper in 1946 in which the first details of cyclone operation on American coals were made available.52 Commercial adoption of the cyclone proceeded in Europe, initially in the Netherlands, Germany, and France. In the United States, where coal is less costly and most of the coals are easy to clean and respond well to simpler cleaning processes, the first cyclone plant was not built until 1961.53 THEORY Before discussing the theory of a dense-medium cyclone, a brief description may be helpful to some readers who are not familiar with its basic operation. In a typical dense-medium cyclone, illustrated in Fig.7-51 a mixture of medium and raw coal enters tangentially near the top of the cylindrical section, thus forming a strong vortical flow. The refuse moves along the wall of the cyclone and is discharged through the underflow orifice. The washed coal moves toward the longitudinal axis of the cyclone and passes through the overflow orifice, or vortex finder, to the overflow chamber. Washed coal is discharged from this chamber, usually through a tangential outlet.

Jan 1, 1991

By Lawrence Neal Post

Introduction Synthetic soda ash production began to decline in the late 1930s. This was due to high operating costs and waste disposal problems. Since soda ash was used as a major component in manufacturing glass, an alternate method of producing that chemical was necessary. A process to produce soda ash from trona was developed by FMC Wyoming Corp.'s predecessor, as well as an economical way to obtain trona. Existing trona operations are located about 40 km (25 miles) west of Green River, WY. Five operators presently mine trona in this area. FMC's property has 153 km2 (59 sq miles) leased. Its eight shafts reach 488 m (1600 ft) deep to the uniform trona deposit. The seam ranges in thickness from 2.4 to 3.6 m (8 to 12 ft). History Egyptian tombs, dating from 4000 to 3000 BC, contained mummies preserved by an embalming process using soda ash. For many years, soda ash was produced by burning marine plants, then dissolving the soluble material (sodium carbonate) from the ashes. The name soda ash is derived from this method of production. In 1791, Nicola LeBlanc developed black ash, or salt cake, from salt, sulfuric acid, coal, and limestone. This process remained in use until 1863, when Ernest Solvay developed a method for producing soda ash from salt, coke, and limestone with ammonia as a catalyst. This Solvay process was widely used. And, in the 1930s, there were 17 plants in the US alone. High plant operating costs and waste disposal problems, however, necessitated finding an alternative to the Solvay process.

Jan 10, 1985

By Richard Newcomb

It is four years since the seminal study of demand for rapid excavation by the National Academies of Sciences (NAS) and Engineering outlined this technology's opportunities, requirements and significance to the challenges of urbanization and natural resource conservation. The demand study was quite simple. Opportunities were valued at market while requirements to produce new technologies were valued at cost. The significance of new technology in economic terms was measured by the net discounted gains to users over time. The Academy view in 1968 was that these gains, even most modestly estimated, appeared large enough to justify the bill for research proposed by that Committee (1). In 1970 the question of demands became international in what is recognized as the first international experiment in technological policy analysis, terminating in the Advisory Conference on Tunneling of the Organization for Economic Cooperation and Development (OECD)(2). A monumental demand survey formed the basis for its economic assessment. The twenty-two OECD nations also made an impressive attempt to measure the magnitude of existing research and development efforts. In their recommendations periodical statistical demand forecasting and collection of demand data (Recommendation 1) was given central importance for public planning (Recommendation 2), the financing of public construction (Recommendation 3) and the encouragement of technological advance (Recommendation 4). Their program for international cooperation led to OECD's establishment of a Directorate for Environmental Affairs, and influenced the organization of the World Environmental Conference meetings now held in Stockholm under United Nations auspices. The OECD Conference was the first example of "an attempt to apply the concept of technological policy analysis to a 'civilian' technology having potentially

Jan 1, 1997

By Robert P. Moodry

It was attempted to revitalize an old sulfide leach dump by increasing the oxygen content within the dump. Compressed air was introduced into the old dump. This was accomplished by drilling 300 foot angle holes into the dump surface with an Aardvark drill which holes are then cased with 1-1/2 inch perforated PVC pipe. Compressed air is injected through these cased holes during a 10 day rest cycle. The second case consists of bedding perforated polyethylene pipe at the interface between the old dump surface and the next Lift of a new dump. Compressed air is then blown through the bedded perforated pipe on a continuous basis while leach solution is applied.

Jan 1, 1976

By J. B. Cabezas

The metallurgical processes that are frequently applied today use strong solutions and are of alkaline, acidic, or organic nature. These play a very important part in recovery of values from many ores. These solutions are of such a chemical nature that they are generally corrosive, flammable, and contaminating. In most cases, they are highly dangerous to the environment. Within the extractive metallurgical industry, it is also very common to have to deal with the handling of contaminating solutions with a high content of cyanide, arsenic, mercury, lead, copper kerosene, acid and many other components whose temporary or permanent confinement within the process must be adequate and absolute.

Jan 1, 1986

By George C. Trevorrow

It is a pleasure to appear on this program and discuss a subject which is of particular interest to me. In my regular duties as Safety Director of Bituminous Coal Operators' Association, I am called on by member companies to discuss matters affecting face ventilation. As a member of the Joint Industry Safety Committee, as I will later describe, I have a part in processing requests for the use of auxiliary fans for face ventilation. The use of auxiliary fans in bituminous coal mines for this purpose came into rather wide use in the late. '20's when conveyor mining was introduced. In this application, the equipment consisted of a chain conveyor with a face chain conveyor parallel to the face on which the coal was loaded by hand and, in turn, was discharged onto the room conveyor and thence to a loading point on the entry at the mouth of the room. Another method was to use a shaker conveyor with a duckbill which was maneuvered across the face of the room from which the coal was loaded and transported by the shaker to the loading point. In either case the equipment did not readily lend itself to driving crosscuts or breakthroughs with the result that rooms were driven to depths of 250 or 300 feet without adequate means of ventilating the face area with the main split of air. It was, therefore, necessary to use other means of ventilating this area as the rooms were being driven and during retreat work if pillars were extracted. Auxiliary fans of the blowing type were utilized for this purpose. They were of very small capacity using small diameter tubing. By the time the room was driven half way to its projected limit ventilation was very poor or practically nonexistent. To compound the problem the fan was usually set up at the mouth or neck of the room and in many cases the intake air to the fan was the return air from the room. It is small wonder, therefore, that there is on record 12 cases where auxiliary fans were given as the cause of explosions. In 9 of these occurrences, arcs or sparks from open-type motors or accessory equipment on these fans were given as the primary ignition source. They fell into such ill repute that in a number of cases they were blamed as the ignition source even though smoking was strongly suspected as the primary cause.

Jan 1, 1967

The Carlin Trend is North America's premier gold producing district. It is located in northeastern Nevada's Elko and Eureka Counties along a northwest trending belt about 65 km (40 miles) long and 8 km (5 miles) wide (Thorstad, 1989; Jones, 1989). This trend is the worldwide reference site for epithermal, sedimentary rock-hosted microscopic gold deposits. At least 19 deposits have been discovered to date, varying in size from 933 kg to 1.08 kt (30,000 to 35 million contained oz) of gold (Fig. 1). Newmont Gold Co. and its parent, Newmont Mining Corp., jointly constitute the largest mineral right holders in the district. They own or control more than 1000 km'- (386 sq miles) in and around the Carlin Trend and own all or part of 16 out of the 19 mines and prospects identified to date. Since the initiation of Newmont's exploration activities in the Carlin Trend in 1961, 2.24 kt (72 million oz) of cumulative gold resources have been identified. Cumulative production from all mines since the start-up of Newmont's Carlin mine in 1965 to the end of 1989 was about 202 t (6.5 million oz) (Jones, 1989). The incentive of sustained high gold prices and innovation in processing technology resulted in a significant acceleration of gold output over the last few years. Newmont Gold alone produced more than 43.5 t (1.4 million oz) in 1989. That is equal to 22% of the cumulative 1965 to 1988 output, and an almost 200% increase over its 1986 output.

Jan 1, 1991

By Fred A. Glover

It's a pleasure to be included with this group. I am not here to sell my services, but rather to share with you some ideas and considerations on using environmental consultants. Environmental consultants have developed some problems as well as created new costs for companies that are as legitimate as engineering costs. Each day the mining industry is becoming more affected by the proliferation of environmental regulations and their interpretations by federal and state agencies. How does a modern mining company cope with all the demands for environmental consideration by regulatory agencies and special interest environmental groups-- yet produce a product and make a profit? One way is to make efficient use of environmental consultants. But, as everyone here knows, this approach has been fraught with seemingly inherent frustrations, difficulties, and much justified criticism.

Jan 1, 1979