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By S. C. Howell

The mining of taconite, to provide feed for a processing plant, requires that the flow of material continue uninterrupted. This means first, that the crude must be of a size acceptable to the primary crusher in order to reduce the delays caused by plugging the crusher with chunks. Secondly, elimination of oversize in the pit will reduce costs of all wear parts used in the mining and processing of taconite. Savings in wear parts is readily recognized in dipper teeth, bases, buckets, truck boxes, and crusher parts, both primary and secondary. During the early days of taconite mining, it was soon recognized at reserve mining company's Babbitt operations that experience in mining other ores was not always (or ?necessarily??) Applicable to excavating taconite. This was especially true in drilling and blasting. Blasting of small tonnages in single or double rows simply filled the pit with scattered chunks and provided very shallow banks for shovel loading. It also created problems for the jet piercers, since all drilling had to be performed in fractured areas. Drilling efficiency suffered and costs were extremely high. Shovel and truck efficiencies were also low and again costs were high. A high percentage of secondary breakage was required. This necessitated the use of numerous man hours to jackhammer holes in chunks, preparatory to loading and blasting. After the chunks were reduced, bull- dozer and grader hours were needed to pile the taconite for acceptable shovel loading.

Jan 1, 1968

By D. R. Gibbons

This morning I would like to speak to you about an area of chemistry that is enjoying a revival-organometallic compounds. This renewed interest, principally stimulated by defense needs, has already created new markets for the products of the mineral industry. Although the consumption of metals in these new products is modest at oresent, several hold promise of importance. Because this is a new and growing market, I am sure the Council of Economics is aware of many of its facets and is interested in new developments. Of course, the chemical industry has been a significant consumer of minerals for many years. I estimate that in 1957 the chemical-industry purchased a total of $1175 million worth of minerals as raw materials (not including fuels). This estimate can be broken down as follows: [Metals and metallic minerals $375 million Nonmetallic minerals (excluding hydrocarbons ) 330 million Hydrocarbons 470 million $1175 million]

Jan 1, 1958

By R. D. Grove

The control of Florida phosphate flotation plants is largely based on the visual observations of experienced operators, both in recognizing good and bad froth conditions and in making judgments about the composition of feed, concentrate and tailing streams. Chemical analyses lag the process by at least two hours and therefore only assist in recalibrating the operators' vision when major deviations occur. An image analysis system has been developed by IMC Fertilizer to improve upon the accuracy and precision of the composition estimation process. It still relies upon the operator taking a representative sample, but provides a measurement in about 15 minutes after that sample is obtained. This paper describes the system and its use and presents comparative results for various process streams.

Jan 1, 1993

By Malcolm D. Flavel

As indicated in the introduction to this paper, it is a sequel to that which I gave to the last annual meeting in Atlanta in march. This paper goes further into aspects of crushing and screening, primarily from the standpoint of circuit control. There has been little published by equipment manufacturers on this subject and this is the first paper on crushing circuit control to be sponsored by Allis-Chalmers corporation. By proper control over the use of crushing energy, we will be able to produce finished products from feed materials uti¬lizing minimum capital for the lowest cost of production. The subject will be discussed as follows. Firstly, we will look briefly at what we are trying to accomplish; Secondly, what is presently available in the way of technology; Thirdly, we will look at a suggested new system of control which will best fit the parameters of the normal crushing and screening operation; As a conclusion, I will summarize the advantages of the new system.

Jan 1, 1977

By W. Nahas, T. C. Watson, A. R. Maycock

The development of roasting technology for the oxidation of sulfides in refractory gold ores is discussed. Case studies covering operations dating from the mid-1930's to the present day are used to illustrate this development. The roasting of ores and concentrates is reviewed and various gas cleaning flowsheets are discussed with particular reference to environmental requirements. A sequence chart is provided to show the development path of a potential roasting project.

Jan 1, 1990

By S. W. Clark, R. Meglen

A seismic refraction survey of selected environs of Brewster Phosphate's Lonesome mine near Bradley, FL identified various layers of overburden, minable matrix (ore body) and basement (i.e., bedrock) that correlated with core logs. Bivariate correlation procedures determined that statistical relations existed between mining parameters and seismic velocities. For instance, a correlation of approximately -0.6 was inferred between P wave velocity and ore grade.

Jan 1, 1990

By A. de Ferran

Is the Brazilian gold rush over? Judging from the situation in Brazil over the past few decades, the answer is almost certainly yes. The picture of swarms of Brazilian prospectors or "Garimpeiros" crowding or, more correctly, overcrowding the gold regions of the Amazon jungle using the time-aged empirical approach to gold exploration has finally run its course. There are two fallacies that have lead to a reduction in the discovery of new gold fields in Brazil. The first fallacy is that "Brazil's geology is largely unknown." The extreme depth of weathering and the general lack of understanding of the shield deposits are at the origin of this misconception. The second fallacy is that "Brazilian prospectors (`garimpeiros') are very naive, have very little technical knowledge and can only produce gold at very low recovery rates." This is more of a result of wishful thinking for the purpose of justifying limiting exploration programs than it is a real consideration. In this paper, the author takes a methodical heuristic approach to gold exploration in Brazil and offers this as an alternative to the empirical approach of the garimpeiros.

Jan 1, 1997

By L. Wilfley, G. A. Calboreanu

"Wear resistant 25% Cr hard cast iron is a heterogeneous material containing 1,600 HV hard chromium carbides embedded into martensitic matrix. It is the most used cast alloy in wear operations of mining industry, chemical industry, fracking, etc. During the last decade the hard iron manufacturers increased wear resistance in the following ways: • Reduce / eliminate harmful retained austenite and chromium + carbon depleted areas especially within eutectic carbide cells. In Max5A the improved 25% Cr alloy brittle carbide eutectic cells are removed which increases toughness. • Delay delamination between chromium carbides and matrix particularly during sliding abrasion wear. Delamination commences at the weakest chromium carbide – matrix contact lines exposing chromium carbide to localized bending stresses which gradually chip carbides away. Once the chromium carbide base is removed accelerated wear degradation occurs. • Evenly randomize and avoid discontinuities in the chromium carbide network. When chromium carbides are perpendicularly positioned to the wear surface wear rate is minimized. On the contrary the highest wear rate takes place when 3D oriented chromium carbides are parallel with the wear surface. In this case chromium carbides cover top network discontinuities being just matrix supported which leads to rapid carbide cracking. The new hard iron discussed in this paper fulfils and exceeds the above requirements increasing the casting service life around 250% in various wear operations. Physical and mechanical properties of Max5A are compared with well manufactured Industry Standard 25% Cr hard iron. The paper presents practical accomplishments obtained in the USA, South America and India. INTRODUCTION The chemical composition of Max5A and Industry Standard 25% Cr are identical like specified by ASTM A532 Class III Type A requesting C = 2.0-3.3% and Cr = 23.0-30.0%. Manganese, silicon, nickel, molybdenum and copper contents are limited by maximum accepted quantities.[1] According to published data the eutectic chromium carbides chemical composition of 25% Cr hard iron is Cr = 54% and C = 8% which indicates strong depletion of chromium and carbon along chromium carbide - matrix interfaces. [2] The optimized Max5A microstructure has minimized retained austenite, is devoid of harmful carbide eutectic cells and has the most advantageous chromium carbide and secondary chromium carbide morphology. This favorable microstructure increases wear resistance, mechanical properties and corrosion resistance. The paper compares the Max5A microscopic features and mechanical – physical properties with similar properties of high quality Industry Standard 25% Cr."

Jan 1, 2017

By Alexander Filimonov, Yury Bloshteyn

The development of a high-efficiency control system for mine ventilation is a complicated scientific and engineering problem. As a result of high-costs and difficult conditions involved in experiments for the development and investigation of mine ventilation systems, simulation is a critical task in cost reduction and productivity. The paper presents the description of a universal simulation model for controlled aerodynamic processes in an Underground ventilation Network (UVN). The high-efficiency programming tool to design and investigate mine ventilation control systems (MVCS) is also suggested.

Jan 1, 1991

By R. A. Jankowski, R. Gong, R. Bhaskar

The control of respirable coal dust in continuous mining sections involves careful analyses of the generation and transport of the dust, including airflow pattern analyses. Potential dust control devices must be evaluated based on their effect on both local dust transport and potential dust exposure of face personnel. The development of larger and more productive continuous miners increases the need for research on dust control and improvement of visibility in the face area. Two studies relating to underboom dust control are discussed. The first study involved the valuation of potential underboom dust control techniques to reduce operator exposure to dust and determining the relationship between the positioning of exhaust ventilation and the exposure of face personnel as a function of face and operating variables. The study involved full-scale laboratory experiments using a state- of-the-art data acquisition system. The second study related to the use of foam under a continuous miner boom and its effect on silica concentration and respirable dust. The foam study was performed in a coal mine. The laboratory studies involved the fabrication of a full-scale test facility and development of a computer based data acquisition system. This was followed by baseline data collection, smoke trace tests, detailed performance testing of various underboom dust control measures and data analyses. The underground foam test involved the design and installation of the foam generation and delivery system, testing, and data evaluation. The results of the studies are summarized in this paper.

Jan 1, 1991

By N. L. Parduhn

Populations of Bacillus cereus spores are elevated in soils over four subsurface gold deposits in the western United States. Large deposit-to-background ratios of B. cereus populations were obtained in soil traverses over the Minnesota vein deposit, Empire District, Colorado (maximum 50:1); the Shasta (maximum 3,500:1), and Evening Star maximum 18,000:1) vein deposits, Shasta County, California; and the Hog Ranch disseminated gold deposit (maximum 40,000:1) in Washoe County, Nevada. Small increases in the concentration of toxic metals in the soil may be responsible for the elevated spore populations. The observed elevation of B. cereus spore populations near these gold deposits indicates that the method should be further investigated as a potential exploration tool.

Jan 1, 2013

By John G. Oldsen

During the last several years, implementation of trusses, in lieu of wood cribs, has been successful for supplemental tailgate support in the Pittsburgh seam. This paper reviews the truss support system provided by the new high strength 0.6" tensioned cable truss, which is now also being used in cribless tailgates. Cable loading and roof deformation were monitored to evaluate roof and floor performance. The test results indicate that the cable truss system successfully controlled the roof and floor during the first and second panel extraction. This paper will describe the advantages of cable trusses and their load transfer mechanism as well as mine evaluation.

Jan 1, 1997

By I. S. Parrish

As noted by McKinstry (1948), "How to deal with erratic high samples is one of the knottiest problems in ore estimation." He described a variety of approaches and methods to alleviate the problem through the averaging and weighing of assay data and by "cutting" or "clipping" of the erratic assays. Bird (1991) elaborated on ways of dealing with the nugget effect (erratics). He listed several procedures for cutting. Bird's list has been reproduced and/or added to by several authors including Vallee (1992) and Stone and Dunn (1993). Missing from each of these otherwise excellent reviews is a definition, description or guideline to recognition of an "erratic," or just where or when cutting is warranted or justified.

Jan 1, 1997

By S. K. Kawatra, T. C. Eisele

A horizontal-baffle arrangement has been developed to prevent excessive axial mixing in flotation columns. These baffles have been shown in previous work to improve the grade/recovery performance of both a laboratory-scale column and a pilot-scale column (Kawatra and Eisele. 1993). In this paper, results are given for continuous on-line operation of the pilot-scale baffled column in a commercial coal- cleaning plant. These results show its ability to operate for extended periods without plugging, to produce a consistent-quality product even while the feed quality was fluctuating, and to remove much of the pyritic sulfur from the coal.

Jan 1, 1995

By O. Akinkugbe

The safe, productive exploitation of coal in multiple-seam situations requires specific design technology. At present, there are two general design approaches that the mining engineer can use to analyze the multiple-seam problem in question, either simple empirical relationships or complex numerical models. Often, the empirical approaches are too general for the specific problem and the numerical models require too much time and expertise for the practicing engineer. In this paper, a new program designed for quickly and easily calculating the stresses, strains, and safety factors associated with basic multiple-seam mining situations is presented. The program implements a simplified, two-dimensional boundary-element method in order to model the complex multiple-seam stress and displacement interactions. The program incorporates automatic coal and gob property generation to simplify the input, and inherently calculates pillar safety factors to enhance the output.

Jan 1, 2004

By A. F. MacDonald

The rugged foothills of the Allegheny Mountains in Washington County, Southwestern Pennsylvania, lend their terrain very well to the use of aerial tram systems to carry refuse from Bethlehem Mines' two preparation plants to disposal areas some distance from the plant site. Bethlehem Nines Corporation has three deep mines in this area, all of which are mining the Pittsburgh Coal Seam, The raw coal is prepared for metallurgical use in a preparation plant at each mine, Trio of these preparation plants, Mine No, 51, Ellsworth and Mine No. 58 Marianna, use aerial tram systems to dispose of reject material.

Jan 1, 1966

By R. D. Hagni, R. T. Brandom

An ore microscopic study of the Boss-Bixby, Missouri, copper-iron deposit has shown that the mineralization formed as a simple sequence of oxides followed by cobaltian sulfides, copper-iron sulfides, and then oxides. The hypogene ore minerals found by this study are magnetite, hematite, ilmenite, rutile, chalcopyrite, bornite, covellite, cobaltian pyrite, carrollite, sphalerite, clausthalite, galena, electrum, scheelite, wolframite, and a Pb-Bi-Se-Te mineral. Textural evidence indicates that some of the early oxides were original constituents of the host syenites and oxidized during cooling. The remainder of the mineralization formed as breccia fillings and replacements. Subsequent partial oxidation has formed martite, covellite, rutile, and anatase.

Jan 1, 1987

By David Martell, Wilf Ingram

For over 100 years mine hoists have been used in Cape Breton Coal mines which are situated on the eastern coast of Canada. Most of the coal seams have been inclined and as the mine advanced, longer lengths of haul were required. This paper describes the successful operation of slope hoists with rope capacities of up to 6100 m (20,000 ft.) at Cape Breton Development Corporation. A general description of the hoists is given. The braking systems, controllers and man riding cars used are discussed. The operational problems of using such long lengths of rope are described.

Jan 1, 1981

By Sadatoshi Ohmori, Simin Zhai, Devini Abeyawardena

A road tunnel is planned to be constructed in soft, high overburden ground of around 600 m in Japan by using the center drift advancing method. The dodging effect and early ring closure of the center drift were expected to reduce the displacement and deformation of tunnel and promote safe construction. The measurement result during construction was analyzed and those effects, which the displacement and deformation after the widening excavation decreased and its effect increased as the center drift radius increased, were confirmed by numerical analysis. Also, the effect of the early closure of center drift after widening excavation did not have much effect.

Jun 23, 2024

By L. Wade, D. R. Pearce

A detailed account is given of the spectral ratio laboratory method for the determination of seismic velocity and attenuation through rock cores under simulated in-situ stress conditions. An account of a computer program called AUTOQ is described for automatic processing of a complete set of laboratory results. Some of these results are shown and discussion is directed to- wards the suitability of in-situ velocity or attenuation measurements in determining rockmass condition or stress regime.

Jan 1, 1996