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To predict the spontaneous combustion potential of bituminous coals using a simple expression based on an easily acquired coal property. Background Approximately 20% of underground coal mine fires in the United States since 1978 have been attributed to spontaneous combustion. Spontaneous combustion fires in underground mines are most likely to occur in gob area; and are difficult to detect and to extinguish by direct fire fighting methods. Often, sections of the mine or the entire mine must be sealed for long periods, at a great economic loss to the mine operator, mine employees, and the surrounding community. It is conservatively estimated that the cost of scaling a large mine is about $50 million.

Jan 1, 1989

By F. Baczek, S. S. Rocks, D. Chaiko, C. Eyzaguirre, S. Asihene, T. Walters

The majority of efforts to improve primary copper sulfide leaching have focused on solution chemistry, temperature, O2 pressure, ultra-fine grinding, the use of catalysts, etc. Historically, very few studies have focused on the solid/solution interface. A new, patent pending approach to catalyzed, copper sulfide leaching has been discovered by FLSmidth that enables manipulation of the 2-D semi-conductor properties of chalcopyrite surfaces to the benefit of higher electrochemical reactivity. Copper dissolution rates are then further accelerated by incorporating a Stirred Media Reactor (SMRt) into the process. By using minute amounts of Cu2+ to "pre-activate" chalcopyrite, leach times have been reduced from >20 hours with incomplete Cu dissolution to <2 hours with 98+% Cu dissolution at 80°C. The pre-activation process takes only minutes to complete at temperatures of 80°C or less. The total atmospheric leaching process, incorporating the pre-activation and Stirred Media Reactor is compatible with existing SX/EW processes. Results of batch leach testing are presented and possible mechanisms are discussed.

Jan 1, 2015

By J Seppelt, B Akerstrom, A Rice, J Bubnich, T Waters

The Concentrator 1 plant at Cadia transitioned from Cadia Hill open pit to the Cadia East block cave ore body in 2013. As a result of this change, major plant upgrades were required to achieve the desired throughput while treating more competent ore. The 40-foot (40’) SAG mill now receives a feed of predominantly high pressure grinding rolls (HPGR) product with a minor component of secondary crushed ore at a combined F80 of 17 mm. The significant reduction in feed size to the SAG mill has markedly changed the operating characteristics of the mill, which has been extensively studied since commissioning in 1998.This paper examines the operation of the 40’ SAG mill in its new configuration in the Concentrator 1 circuit. Operational stability is highlighted as a significant factor in delivering mill performance, which has been achieved through several key improvement projects utilising a theory of constraints framework. Five years of successful project implementation has progressively lifted the maximum processing rate of Concentrator 1 from the design estimate of 2455 t/h to above 3000 t/h. CITATION:Waters, T, Rice, A, Seppelt, J, Bubnich, J and Akerstrom, B, 2018. The evolution of the Cadia 40-foot SAG mill to treat the Cadia East orebody: a case study of incremental change leading to operational stability, in Proceedings 14th AusIMM Mill Operators&#39; Conference 2018, pp 217–232 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By A. George Stern

[In the examination of bentonitic clay suspensions used for oil-well drilling fluids3/ (and for other purposes, such as a core binder for foundry sand) it is important to have comparative tests for evaluating them. A satisfactory clay for these and other purposes should have the property of forming what is commonly called a "gel," but the measurement of this property has been a real problem. To date the solution has not been satisfactory, and some of the difficulties are considered in, this, paper, which describes a simple form of instrument (identified as an eykometer) for measuring the yield point under hydrostatic conditions of non-Newtonian clay suspensions, including those muds that are thixotropic. An oil-well drilling mud serves several functions, many of which depend on the "gel" characteristics of the mud. Among the more important functions are: (a) To plaster the sides of the hole to prevent caving of the walls; (b) to prevent the loss of the circulating fluid out of the hole by seepage; (c) to carry sand and cuttings out of the hole to the surface as they are formed by the rotary drill; and (d) when circulation of the fluid stops for shut-down or other unavoidable cause, to hold the cuttings in suspension by the setting up of the gel, thereby avoiding the difficulties that result when these cuttings are allowed to fall through the fluid and pack at the bottom of the hole.]

Jan 1, 1940

By A. Basçetin

Equipment selection in mining engineering is one of the most important decisions that affects the mine design, production planning and economic parameters in open pit and underground mining. Mine planning engineers generally use their intuition and experiences in decision making. Mostly, linguistic variables (the weather is raining, soil is wet, etc.) come into question and decision-makers may not know how these variables are computed. Since the advent of the fuzzy set theory, these uncertainties are easily interpreted in the decision-making process. The development of computer technology and programming of colloquial language with expert systems have considerably reduced decision-makers? burden. This paper reviews the development of a computer programme software called EQS (EQuipment Selection) that automates equipment selection in mining engineering using fuzzy set theory. The EQS with an introduction of the concepts and theories of multiple attribute decision-making, the fuzzy set theory, and EQS applications to mining industry problems with case studies are presented

Jan 1, 2006

By Juan Kobashicawa, Bernardo Falcón

En este trabajo se explican los controles automáticos desarrollados (In-House) e implementados en el circuito de Molienda de Compañía Minera Antamina, el cual abarca Molinos SAG, de Bolas y los Hidrociclones respectivos. Los controles implementados son basados en el Control por Lógica Fuzzy y las Bandas de Bollinger; así mismo se indican los criterios en el diseño de los controladores y las variables del proceso que se han tomado para la implementación donde se controla un indicador de distancia del centro de masa de la carga respecto al centro del molino de Bolas. Asimismo, se muestra el impacto positivo logrado con la estabilización del circuito.

Sep 1, 2017

By G. S. Scott, W. J. Huff, G. W. Jones, R. E. Kennedy

"INTRODUCTION This report gives preliminary results of field and laboratory investigations made at the request of the War Production Board relative to causes that have occurred during the last 8 months in acetylene-generat72,r plants in shipyards on the Pacific coast.Six acetylene-generator explosions have occurred in four shipyards. These explosions killed five operators, injured six others, and extensive damage to the plants involved and curtailmnent of vital defense Although the occurrence of acetyiene-generator explosions in other section of the United States is not known, it appears, at least, that if such have occurred, they have caused only minor damage and no loss of lives.The use of acetylene in shipyards on the west coast has expanded tremendously during the past 2 years. These shipbuilding, companies erected aletylene-generatcr equipment, which was soon found to be entirely inadequate to meet the needs of their expanding acetylene requirements for welding, cutting, shrinking, and other purposes, and instances found it necessary to operate their equipment at rates greater than deemed consistent with safe operating practice."

May 1, 1944

By Mark K. Larson

A constitutive model for rock interfaces based on the principles of static fatigue is proposed. The model is applicable to weak rock or joints with cohesion. Friction and dilation are decreased as plastic work increases. At equilibrium, the creep time increases by one time-step interval, and interface cohesion at each node decreases according to a power function. A constant-load, direct-shear simulation showed that the model is cap- able of mimicking constant-rate and tertiary creep and predicting failure. Tests on core from a coal mine showed constant-rate and, sometimes, tertiary creep, but also weak transitory creep. The cohesion deterioration function may need modification to simulate primary-phase creep. If model parameters are known for a site, the model can predict the onset of tertiary creep and failure. Such predictions can help engineers make better entry design and support decisions, which will reduce the likelihood of roof falls and increase safety for underground miners.

By Alex Doll, Derek Barratt

"There is a number of comminution tests commonly used in the mining industry. Many of the tests are used for a particular grinding model or mill sizing program and are incompatible with other tests of different models. This paper provides an overview of the commonly used grinding and crushing tests, which models (or practitioners) use a particular combination of tests and draws some relationships between the incompatible tests based on the DJB Consultants Inc. database of projects.Case studies will demonstrate similarities and differences between major mining districts with some comments about homogeneous and heterogeneous behaviour within the grindability results.INTRODUCTIONThere are a number of bench-scale grindability tests in use for sizing and predicting throughput for grinding circuits. Part of the reason for this variety is there are a number of different grinding models in use in the Industry, and those models operate using incompatible test results as input (Doll and Barratt, 2008).By using the database of testwork in the DJB Consultants, Inc. (DJB) Millpower 2000 database (see Table 1), some of the more commonly used tests are compared and relationships will be drawn."

Jan 1, 2011

By Ben Mirabile

Over the past three decades, the U.S. coal mining industry has widely used cable supports to supplement traditional primary bolting systems, especially in difficult ground conditions. However, increased mining activity in adverse conditions has underscored the limited effectiveness of the non-tensioned, partially grouted cable supports used to supplement primary bolts. Roof failures in conditions such as corrosive environments, highly laminated strata, low overburden depth and water intrusion have demonstrated that the need for cable technology has reached beyond the traditional non-tensioned, partially-grouted cable tendon. Furthermore, declining market conditions and increased competition for coal customers has demanded that new cable bolt technology be costeffective and readily adaptable to the mining cycle. Jennmar Corporation has developed several cable bolt technologies that can be used as stand-alone solutions or in concert with one another to mitigate adverse conditions. These technologies include rapid tensioning of cable supports, structural surface control and polyurethane injection. The case studies presented in this paper use one or more of these technologies to address adverse mining conditions or special ground control problems.

Jan 1, 2013

By Louis A. Panek

THE purpose of this paper is to present a method of designing safe and economical arch structures that are to be constructed of concrete or directly of original earth materials. The experimental data used to illustrate the design method are taken from Bucky and Fentress,1,2 and the application of the ideas presented by them is extended by obtaining an additional set of curves from which arch structures may be designed. This design method is based upon the following principles of similitude: A scalar model made of the same material as that of the full sized structure will behave similarly to its prototype if the density of the model is increased in the same proportion as its linear scale is decreased. Let R represent the scale or model ratio, namely, the ratio of a prototype linear dimension to the corresponding model linear dimension. The effect of increased density may be obtained by rotating the model in a centrifuge at a speed such that the centrifugal field exerts on the model an accelerative force R times the accelerative force of gravity. Under these conditions; (I) model unit stresses are equal to corresponding prototype unit stresses, (2) the ratio of the prototype deformation at a given point to the model deformation at a similar point is equal to the scale ratio, R, and (3) the model and the prototype will behave similarly within and beyond the elastic limits of strain. According to the above relations, such models can be used to solve the following problems: I. The dimensions of the most economical safe arch structure for a given load. 2. The maximum safe roof span underground for given geologic conditions. The procedure is described briefly as follows. Tests are made by rotating in a centrifuge a number of models that repIesent a variety of prototype loads and dimensions. From the experimental data, curves are plotted to show the relations between these loads and dimensions. The curves are used to solve directly the problems stated above. Structural design is based upon the working (safe) stress of the material of construction, which is established by applying a factor of safety to the experimentally determined ultimate strength of the material. In conformity with this principle, each model is gradually loaded until failure occurs. A safety factor is then applied to the results. If a safety factor of 4 is used, a given model at failure represents a safe prototype, the linear dimensions of which are equal to one-fourth the model ratio at failure times the corresponding model dimensions. The safe model ratio is computed from the following formula: [Safe R = (rl 47r2n2r _ 7r2n2r~r~ \4/ gg in which: n = centrifuge revolutions per second at model failure; r = radius of rotation of the model in feet; g = 32.2 ft/sect.]

Jan 1, 1947

By John A. Kiefer

Ground fault and overcurrent protection criteria for coal mine a.c. distribution systems were examined under a Bureau of Mines funded investigation. The report begins with a literature review which discusses relaying topics including instrument transformers, ground-fault pickup methods, static relaying, and comparison of relaying techniques. A chapter on ground-fault relaying provides recommendations for maximum and minimum pickup levels as a function of maximum ground current and power system line-to-ground capacitance. Research in the area of phase overcurrent protection has resulted in a complete set of procedural recommendations for the selection and setting of overcurrent relays and current transformers, molded-case circuit breakers, and distribution system fuses in coal mine power systems. The final chapter, which discusses relay system maintenance, introduces a unique test set which was developed by KETRON and used to test the performance of relaying systems in coal mines.

Jan 1, 1980

By Sam Palombo, James José Varela

"Washing can be defined as the process used to eliminate or reduce the dirt (presence of fines or slimes) of one material. It is also the basic and oldest process applied to ore preparation for further concentration. This process, in combination with commnution and screening, form the so called washing plant and in many cases produce end products. This work describes the factors that influence the performance of the washing process and main washing technologies used in the mineral processing industry.The Hydro-Clean represents, since 1998, a state of the art technology in this area and is comprised of one of the most innovative solutions developed at HAVER & BOECKER. HAVER & BOECKER design and manufacture technology for mining and related industries. Today the Hydro-Clean is manufactured and sold throughout the Haver Screening Group (HSG) which is comprised of HAVER & BOECKER Maschinenfabrik Münster, HAVER & BOECKER Latinoamericana – Brazil and W.S. Tyler Canada.The Hydro-Clean is a washing technology based on utilization of high pressure water jets. To follow we will discuss how the Hydro-Clean’s different modes of operation result in several advantages related with mine waste reduction, recovery of saleable product, lower capital costs, superior washing results, less stress for the material, a wider range of application and less maintenance cost. Aside from these positive factors, its lower operation costs related to the consumption of energy and water are presented. It is important to note that the quantities, tonnages, data and management concepts presented in the paper are accurate for the time of writing and are subject to change and modification as operations progress."

Jan 1, 2009

By AIME AIME

BY the end of 1943, the United States will be able to produce aluminum at a rate of 1,150,000 tons a year. How much aluminum is 1,150,000 tons? It is sufficient to replace every railroad passenger car in this country three times a year. Or, it would put a thirty-piece aluminum cooking utensil set in every one of America&apos;s 34,000,000 homes with enough metal left over to make 5,000,000 miles of aluminum transmission cable, such as was used in the electrification of much of rural America. Expansion of aluminum production capacity for the war program has occurred in three steps: (1) expansion by private industry; (2) the letting of contracts by the Defense Plant Corp. for the construction of additional aluminum plants which may remain after the war to compete with existing facilities; and (3) the more recently announced D.P.C. program for the building of emergency plants to make aluminum, using stand-by power available in large metropolitan centers power of relatively higher cost, making it questionable whether such plants, now gravely needed, will be able to compete in a peacetime economy.

Jan 1, 1943

By S. du Plessis

Nationalization is high on the policy agenda in South Africa. This paper considers the case for nationalizing the local mining sector from an evidence-based perspective, which is derived from theoretical considerations and related to the known features of the South African mining sector and economy. A strong case against nationalization emerges, which can be summarized as follows. The mining sector is competitive and therefore a poor candidate for public ownership. Furthermore, the resources sector does not dominate the South African economy nor does it create the risk of a decrease in the competitiveness of the industrial sector via the unintended adverse impact of an appreciating real exchange rate due to a commodity boom (Dutch Disease). Nationalizing the mining sector will cost the government more than it receives. This is not only a bad idea in itself, but it will limit the scope for distributive policies on the national budget. The contemporary international experience demonstrates the risks of fiscal imprudence. Finally, nationalizing the resources sector will undermine support for those very market-based institutions required to achieve a higher long-run growth trajectory.

Jan 1, 2013

By Xuejing Xie, Tianxiang Ren

Paper presented at the 28th International Geological Congress held in Washington DC, July 1989 (International geochemical mapping sessions). Standardised stream-sediment sampling procedures have been used in mountainous and hilly terrains. Special sampling procedures were developed for application in remote environments, such as high mountains, desert, semi-desert, karst and loess-covered regions. The diversified analytical methods used in more than 20 analytical laboratories participating in the project have been unified into two multi-element, multi-method analytical systems. A unified data monitoring procedure was developed based on primary and secondary standard samples. To date the project has covered about 4 000 000 km2 and the aim is to complete the coverage within the present decade

May 1, 1991

By N. Mutemeri, T. -L. Field, M. Chuma

The categorization of artisanal and small-scale mining has a significant impact on perception and understanding of the sector, particularly from a livelihood perspective. Several developing countries classify different types of artisanal and small-scale mining based on legal status. Given the nature such activities, the tragedy of the commons theory has been applied to understand the inevitable environmental, economic, sociocultural, safety, and health negative externalities – which are products of informality and illegality. Consequently, formalization is a panacea to sustainability. This article aims to offer a conceptual organization and foundational knowledge for characterization of artisanal and small-scale mining. It seeks to identify existing literature on the subject to avoid replication and acknowledge other scholars. Moreover, the article aims to place the study within the context of existing literature, establishing relationships with other studies and why the research is necessary. This paper pinpoints gaps left from other studies in so far as the characterization of artisanal and small-scale mining is concerned. Thus, reviewing literature abetted in finding similarities and differences on how artisanal and small-scale mining is defined from a scholarly and legal basis. The paper ascertains major claims made by earlier research on this topic, such as environmental impacts, the lack of adequate regulatory framework, and presents querying and probing questions lacking from other studies.

Jul 10, 2024

THE Phillips River gold and &apos;copper field is situated on the south coast of Western Australia, about 200 miles east of Albany, 180 miles west of Esperance, and: 250 miles south of Southern Cross, forming the southern extremity of what Mr. H. P. Woodward classes as the fourth belt of Pre-Cambrian rocks, and the first auriferous belt, whicf extends northward through Southern Cross, Mount Magnet, and Cue. The field may be considered the premier copper producer of the State. The first mineral discoveries were made about 1892; when gold, copper, and iron pyrites were found; but, owing to the isolation of the district and the scarcity of water, both in the locality and on the route thereto, little work was done for some years. In1899, however, payable gold reefs were opened up, and the district began to attract attention.The southern portion of the district is composed of limestone and sandstone rocks, forming the coastal series, and is for the most part flat, broken only by a few low hills and ridges, except to the west, where Cape Barren and Eyre&apos;s Range stand out...

Jan 1, 1917

By A. R. Miller

A fuel cell locomotive incorporates the advantages of its competitors, namely catenary-electric and diesel-electric units, while avoiding their disadvantages. It possesses the environmental benefits, at the vehicle, of an electric locomotive but the higher overall energy efficiency and lower infrastructure costs of a diesel locomotive. The natural fuel for a fuel cell is hydrogen, which can be produced from many renewable sources or via nuclear energy, and thus a hydrogen-fuel cell locomotive will not depend on imported oil. Hydrogen produced from renewable primary energies or nuclear energy would provide a totally zero-emissions vehicle, that is, with zero carbon in the energy cycle. A project partnership among Vehicle Projects Inc of the USA, and South African partners Anglo American Platinum, Ltd, Trident South Africa, and Battery Electric, has designed and is launching a series of five prototype fuel cell-powered mine locomotives.

Jan 1, 2012

By Corinne Boone

CO2e.com, LLC - launched in November 2000 - aims to be ?the global hub for carbon commerce.? CO2e.com is a subsidiary of the Cantor Fitzgerald Group, one of the world?s leading brokerage firms Recent Investor in CO2e ? Mitsui & Co. Alliance with Cantor Fitzgerald Environmental Brokerage Services Group (CFEBS) Offices in London, Toronto, Tokyo, New York, San Francisco, Los Angeles, Connecticut, Houston Primary Goals/Benefits of ET § Goals of Emissions Trading: ? Permit Industrial Growth/Expansion ? Promote Economic Efficiency and Flexibility in Meeting Air Pollution Standards § Benefits of Emissions Trading: ? Enhance Air Quality w/o Economic Stagnation ? Encourage Development of New Technology ? Foster Most Efficient Use of a Limited Resource -- Clean Air § Contributes to Sustainable Development and objectives of UNFCCC, Kyoto Protocol?.

Nov 1, 2002