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By Gordon A. Gross

Banded siliceous manganese-iron bearing sediments recognized as distinctive facies of Algoma type iron-formation constitute low grade resources of manganese in many countries. Manganiferous facies associated with oxide and carbonate facies of iron-formation have iron to manganese ratios ranging from 0.2 to 2 and commonly about one. Manganiferous facies up to 30 meters thick occurring separately or with other iron-formation facies are associated with cherts, carbonates, shales, turbidites, tuffs and lavas. Primary cherty manganiferous facies and their gondite metamorphic equivalents represent significant manganese resources and are protores for higher grade deposits derived by secondary enrichment processes.

Jan 1, 1982

By E. A. Noble

In the Western Coal Region, successful reclamation of surface-mined areas includes the protection of groundwater sources. To accomplish this, a complete understanding of the geohydrology of the affected area is imperative. Successful mine design also calls for careful attention to geohydrology. Because the Western Coal Region is semi-arid land used mainly for farming and grazing, groundwater is a particularly sensitive topic. It is especially sensitive where the lignite scheduled for mining is itself the aquifer supplying the farms and ranches. Such is the case throughout much of the Western Coal Region, particularly where there are no near-surface sand and gravel aquifers that are commonly found in the glaciated portions of the Region. Just as mining can adversely affect groundwater supply, so can groundwater adversely affect mining. Mine flooding and highwall instability are examples of this. But, mine operators must realize that procedures they use to remedy geohydrologically-related mining problems can have a dramatic effect upon ground- water conditions in areas adjacent to the mine. A logical precaution is to require the acquisition of complete baseline data prior to making the first cut. We recommend that the mining plan not only incorporate the reclamation plan, but that they be developed as one plan.

Jan 1, 1976

By Daniel T. Hegyan

The employment of continuous rotary vacuum disc filters to filter refuse from the fine coal washing circuits has been increasing as it has become more important to close the water circuits and eliminate sludge holding ponds. This paper will discuss our past experience filtering refuse, effects of solids concentration in the filter feed, use of polymer flocculation aids, effect of flocculation devices, and effects of particle size and ash content on the filtration rate. Detailed tests were performed on existing installations utilizing coal refuse filters to determine optimum flocculant dosage, solids concentration, and disc rotation speed to form a dischargeable cake. Information was also obtained showing effect of flocculant addition on the moisture of the filter cake. Our test work has shown that the continuous filtration dry cake rates for fine coal refuse correlates very well with the data developed and presented by Silverblatt and Dahlstrom1 except that the curves have moved up the scale by use of polymer flocculant additions. These polymers were not available at that writing. Finally, our tests also confirmed the general premise stated by S. K. Mishra2 that controlled additions of polymer flocculants will reduce filter refuse cake moistures somewhat.

Jan 1, 1974

By Robert W. Cope

"Mining began, in the Colstrip area in the 1920's by the Northern Pacific Railroad. The coal was used for steam locomotives until 1957, when the advent of diesel power made them obsolete. In 1959, Montana Power Company purchased the Northern Pacific properties including the mining equipment, coal leases and the town of Colstrip. Western Energy Company, a wholly owned subsidiary of Montana Power Company was formed in 1966 to manage the mining operations in Colstrip. The Rosebud Mine officially re-opened in 1968 to supply coal for Montana Power Company's J. E. Corette Plant In Billings. Since 1970, Long Construction has operated the mine equipment for Western Energy Company". The Rosebud Mine is located in Southeast Montana and supplies coal to two 350 megawatt power plants located in Colstrip and one 180 megawatt plant located in Billings. Approximately 30 percent of Western's annual production is consumed by these plants. The remaining production is shipped to the mid-west and burned by utility companies and municipalities.

Jan 1, 1981

By S. P. Singh

In order to simulate the operation of coal extraction machines, a portable workability instrument has been designed. Initially, the tests were performed with the instrument on modeling material, which were followed by in situ tests on coal in underground mines. The peak and mean cutting resistance and work done to cut a unit length of coal were determined for coal as well as modeling material. In addition, rebound strength and dynamic penetration tests were also performed in situ. On the basis of the cutting characteristics of coal, a "Workability Index" has been developed and its role in the judicious selection of coal cutting machines has been discussed. With reference to prior works and the strength characteristics of coal, it was found that the coal plow may not be suitable for the seams under investigation and the shearer seems to be the only choice. It has been observed that peak cutting resistance and the "Workability Index" in the case of coal as well as modeling material depend upon compressive strength. The peak cutting resistance exhibited certain dependence upon the Schmidt rebound hardness and dynamic penetration strength of coal in situ.

Jan 1, 1984

By G. C. Knutsen

The Post deposit is located in Eureka County, Nevada, about 37 km (23 miles) northwest of the town of Carlin. Post occurs on the Carlin Trend, a northwest alignment of 14 major gold deposits, each containing more than three tonnes (t) (100 000 ounces) of gold. Deposits of the Carlin Trend are epithermal, sediment-hosted, disseminated gold occurrences, collectively containing more than 622 t (20 million ounces) of gold. Three major gold producers active on the Carlin Trend are Newmont Gold Company (NGC) (12.4 t/400 000 ounces of gold per year), Western States Minerals Corporation (WSMC) and Pancana Minerals joint venture (1.56 t/50 000 ounces of gold per year), and Dee Gold Mining Company (1.4 t/45 000 ounces of gold per year). The Carlin Trend has also been referred to as the Lynn-Railroad Mineral Belt. This district is characterized by open-pit mineable, micron-sized gold, hosted in Paleozoic sedimentary rocks. Six geological subdistricts comprise the Carlin Trend, each characterized by differences in host lithology, structural controls, alteration assemblage, or style of mineralization. The six geologic subdistricts include, from south to north, Bullion (Railroad), Rain, Maggie Creek, Lynn, Bluestar-Goldstrike, and Bootstrap. With the exception of the Bullion subdistrict, which was primarily a producer of base metals, each sub-district contained mineable reserves in excess of 31 t (one million ounces) of gold.

Jan 1, 1987

By K. K. Bhattacharyya

In the Gulf Coast area lignite deposits occur in Texas, Louisiana, Arkansas, Mississippi and Alabama. Lignite has been mined in Texas since the early 1800's reaching a production of over 900,000 metric tons (1 million short tons) in 1910. With the availability of inexpensive oil and gas, production fall to as low as 16,000 metric tons (18,000 short tons) by 1950 (Henry, 1976). With the advent of the oil and gas shortage in early 1970, lignite production began to increase again. The purpose of this paper is to discuss the geotechnical considerations of mining lignite in the Gulf Coast area, particularly Texas and Louisiana. Lignite deposition occurs in unconsolidated sand, silt and clay environments. Extensive sand units saturated with water may be present within the potential mining depths. This paper describes the geotechnical considerations for designing a surface mine in this geographical area. These factors include geology, hydrology, mining method, and equipment utilization.

Jan 1, 1982

By B. W. Cavender

Capital investments are made for a variety of purposes, from providing incremental capacity at existing operations to developing and implementing new technologies intended to radically improve a company's capabilities. These projects generate very different business opportunities and create value in distinctive ways. For incremental improvements, the capital budgeting process assures at least a loose fit between short-term goals and readily available resources. However, the criteria used to evaluate capital projects often prevent a company from committing to more aggressive goals that lie beyond the firm's current abilities or resources. Such projects may not have clearly identifiable future cash flows, and the degree of interaction with other projects and the nature of the risk incurred may be difficult to estimate. Additionally, by focusing only on quantifiable benefits, the budgeting process often fails to recognize "soft" improvements such as increased operating flexibility or new knowledge generated by such projects. By rejecting these projects, the capital budgeting process may actually harm the company's future competitive position.

Jan 1, 1998

By J. V. Bymark

It is the intent of this paper to discuss the autogenous grinding circuit at Hibbing Taconite. The scope of the presentation includes; a brief history, the process flowsheet and the steps taken to improve mill productivity, availability and metallurgical performance. Hibbing Taconite is located near the center of the Mesabi Range in Northern Minnesota 100 miles from the Canadian border and 80 miles north of the Lake Superior Port Cities of Duluth and Superior. A 105 mile railroad connects us with the port of Superior, Wisconsin, where our pellets are loaded into lake carriers for lower lake destinations. It is worthy to mention the Mesabi Range's most famous landmark which is immediately to the south of our mine area. This is the Hull Rust Mahoning Mine which operated until the mid-1970's producing more than 700 million tons of red ore between 1893 and 1973.

Jan 1, 1985

By K. F. Unrug

The method of coal pillar design involves primarily two aspects, the geometry of the pillar and the strength of the coal. However, the strength of the coal has to be emphasized with respect to the entire pillar dimension rather than isolated strength values of coal samples taken and measured from different locations. The presently applied pillar design systems do not specify clearly what the coal sample strength really represents. The intention of this paper is to introduce the concept of seam strength as opposed to the current practice of using coal strength as a prime design criteria in the formulation of pillar calculations. Seams are most of ten composed of multiple layers of coal, partings, and bone in different configurations, changing within the vertical section of the seam even in relatively close locations. The difference in strength between the weakest and strongest component of the coal seam could be as much as five times or more. An experimental approach based on multiple compressive tests performed on coal samples from the Coalburg and the Warfield seams from Eastern Kentucky was undertaken. The analysis of the results lead to the conclusion that for pillar calculations both the weighted mean of the seam strength and the strength of the weakest stratum should be considered rather than the relatively vague aspect of coal strength The design of pillar dimensions based on the above mentioned aspects should assure a more realistic design performance.

Jan 1, 1985

By Wilfred M. Kenan

The relationship of various genetic classifications of graphite, their properties and general applications are reviewed. The classifications being amorphous, flake, high crystalline (vein) primary synthetic graphite and secondary graphite. The properties discussed are size, carbon, sulfur, ash content, general chemical analysis and degree of graphitization of each type. The major sources for natural and synthetic graphite powders are discussed in addition to factors which govern the cost as well as the supply. The economics of graphite are basically determined by the consumer and the end application. Graphite is a strategic mineral and is on the government stockpile list.

Jan 1, 1984

By Robert Hochscheid

When the original water-only cyclone patents were established in the 1950?s, the supplies of low cost oil and natural gas were abundant and low selling prices for metallurgical and steam coal provided little incentive for developing more sophisticated coal cleaning systems. Bituminous coal sold for less than $5.00 per ton, and in this period many domestic coal producers discarded to the slurry pond the coal finer than 0.5-mm. For many producers, the selling price would not permit the recovery of the capital and operating costs required for dewatering and drying the fine coal. Water-only Cyclones Clean Fine Metallurgical Coal The first broad interest in the water-only cyclone became evident in the mid- 19601s, and though some work was done on coarser coals, investigators were particularly interested in cleaning coal finer than 0.5-mm. Flotation was the only fine coal cleaning method that was broadly accepted, but short-comings were recognized and investigators were looking for an effective fine coal cleaning device or system. Because of the greater market value and the need for reducing pyritic sulfur in metallurgical coals, much of the development work of the 1960's was done on coking coals.

Jan 1, 1981

By James M. Peay

This paper discusses the recently completed organizational development research project, which was addressed to the underground mining industry. The three specific purposes of the project were as follows: (a) to determine whether Organizational Development approaches are feasible in the mining industry, (b) to provide a demonstration that Organizational Development methods can successfully contribute to the safety of underground mines, and (c) to compare the efficacy of classical Organizational Development methods, which are highly trainer- intensive, with trainer-nonintensive management development approaches. The term "Organizational Development" (OD) is here broadly defined as a management intervention for the purpose of assisting an organization with the solution of problems, which are seen by the organization as important. More specifically, we can define OD as a planned effort to improve the effectiveness of an organization through (a) team building and problem solving, which concentrates on the issues of immediate concern to the organization, and (b) efforts to improve organizational communication at all levels of the organization.

Jan 1, 1983

By P. R. Dugan

The ultimate objectives and interest in removal of sulfur from high sulfur coal include: (a) reduction of the atmospheric load that con- tributes to the problem of acid precipitation; (b) reduction of ash which contributes to decreased energy transfer in boilers and the problem of ash disposal; and (c) alleviating the social and economic dislocations related to uneven geographical distribution of sulfur in coal reserves. The cost of sulfur removal in relation to the value of refined coal will govern the development of an emerging coal-refining industry. The value of refined lower sulfur coal will be influenced by the national commitment to the environment as well as economic considerations.

Jan 1, 1986

By Makoto Terada

The most important consideration in planning the plugging and sealing of a mine for mine water control is to predict the water flow from the mine. For this purpose, a method of numerical analysis on the water behavior in the ground at the concerned mine area was developed and the mine water flows were simulated. A hydrological survey at the surface of the mine determined the recharge rate of ground- water and the apparent permeability of ground.

Jan 1, 1982

Adsorption experiments were conducted at two different solids loadings, to investigate the mechanism of oleate adsorption on apatite. Adsorption density at pH 10 was found to be dependent on solids loading in an oleate concentration region where surface precipitation could occur. Analysis of adsorption isotherms indicated three distinct regions of adsorption. In the region I (below the region of calcium oleate precipitation), molecular adsorption was observed. Simultaneous molecular adsorption and surface precipitation occurred in region II, while surface precipitation was predominant in region III along with some bulk precipitation. Correlation between flotation of apatite with sodium oleate and the mode of oleate interaction with the surface is established.

Jan 1, 1986

By David M. Parkes

The hydraulic movement of coal is here defined as the movement of all sizes of coal in pipes and open flumes, by gravity and against gravity. It is not restricted to coal which is in slurry form. In other words, it is not crushed to a size in the 8 to 20 mesh size range. The top size could be as high as 12 inches. The dewatering of coal which is transported hydraulically is carried out to restore the coal to a suitable form for further cleaning, or for transportation by other methods. The process involves complete separation of all the coal, wood and rock from the water so that the water can be recycled without undue damage to pumps, pipes and monitors.

Jan 1, 1976

By Enrique Rubio Esquivel, Matías Fuentes Bustamante

The transition from open pit to underground mining represents a key strategic challenge in modern mine planning. This paper presents a multicriteria and multivariable methodology to plan such a transition, integrating technical, economic, environmental, and social considerations. The proposed framework focuses on risk reduction (de-risking) through the identification of alternative development paths, the use of stochastic simulation to model geological and technical uncertainty, and different mining strategies such as methods, production rates, sequence, etc. for ultimate underground implementation. The study summarizes the limitations of traditional planning methods—which usually treat the open pit and underground mine designs as independent processes—, also often it considers a single mining method and production rate for the underground option. Instead it is proposed an integrated approach that leverages synergies between both mining methods and scalable production rates. Also the proposed methodology incorporates the definition of critical variables (geotechnical, economic, and social, among others), the construction of multiple operational and technological transition paths, and the evaluation of each path under criteria of economic attractiveness and practical do-ability (capacity to be executed). Using simulation tools (SIMPLAN for operational performance and SIMVAL for economic evaluation), probabilistic distributions of the different path are obtained, enabling the quantification of the project’s Value at Risk (VaR). A subsequent multicriteria analysis weights the expected profitability against the feasibility of execution of each alternative, producing a decision matrix that provides a framework for evaluating the different project path. As a result, the proposed approach identifies OP→UG transition strategies that maximize business value by capturing remaining resources while minimizing financial and operational risks. Finally, strategic conclusions and recommendations for the industry are provided, emphasizing the importance of early transition planning even challenging the open pit sequencing of the latest push backs by introducing early underground operations. Future work includes strengthening the methodology—such as integrating real-time analysis and adaptive decision-making—and providing recommendations for its application in various mining operations. In summary, this paper delivers a technical and professional framework to guide mining companies on when and how to carry out a successful transition from open pit to underground mining, balancing resource recovery with financial, operational, and social security.

Feb 22, 2026

By James D. Bennett

Relationships among mine and injured miner characteristics and HSAC's degrees of injury are examined for 91,404 injuries in under- ground bituminous coal mines in the United States from 1975 through 1982. Injury severity varies by the mining system, geographical region, circumstances surrounding the injury, the injured miner's age, whether the miner was using powered equipment, the year which the injury occurred, and the location in the mine where the injury happened. Injury severity is not related to the injured miner's total mining experience, job experience, and experience in the mine in which the injury occurred.

Jan 1, 1984

By A. P. Mehta

The role of microorganisms in the leaching of metal sulfides is well established (Torma, 1977; Murr, 1980). However, this established knowledge applies mostly to chemolithotropic microorganisms such as Thiobacillus ferrooxidans which function optimally in leaching catalysis between 25-35° C, and in a pH range of 2-2.5. Although leaching with thermophilic microorganisms capable of extending the range of catalytic viability beyond 35° C is also documented, there are few if any attempts to optimize or extend sulfide concentrate leaching with thermophilic microorganisms. When mixed metal sulfides or other materials having different rest potentials (referenced to the standard hydrogen electrode, SHE, in the electromotive series) make contact in a conducting, aqueous medium, the contacting members will act as an electrochemical cell, with the member having the higher rest potential assuming the role of an electrical cathode. In leaching reactions involving such galvanic couples, the cathode becomes passivated, while the anodic member reacts vigorously due to the electro- chemical reaction which occurs (Hiskey and Wads- worth, 1975). Serry, eta1 (1978) observed that when chalcopyrite and pyrite were in intimate contact in natural ores, the chalcopyrite reacted vigorously by galvanic conversion as a result of the higher rest potential (~ 0.63 V) as compared to the chalcopyrite (~ 0.53 V). In addition, it was postulated that because of the elemental sulfur which can form on the anodic chalcopyrite in this galvanic conversion process, reactions in acid-bacterial medium would be expected to have accelerated copper extraction because of the conversion of any sulfur product layer on the chalcopyrite anode to sulfuric acid according to the following general reactions: [MS?M2+ + S° + 2e- (1) and 2S° + 302 + 2H20 bacteria?-2H2SO 4 (2)] where M in reaction (1) designates the metal (or metals in the specific case of chalcopyrite) to be released to solution by galvanic conversion.

Jan 1, 1982