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By Ming-Gao Qian

How to monitor and control the support and surrounding strata system on a longwall face effectively is one of the major research problems in ground control. Based on observations on movements of the support and surrounding strata of face No. 2703 of Dongpang colliery, the relationship between the downtime related to support and surrounding strata and other influential factors is analysed systematically in this paper. Monitoring indices and control measures are then determined by taking corresponding downtime as an objective function. When the monitoring method, developed from the above findings, was used on face No. 2703, the downtime due to support and surrounding strata was remarkably reduced, and the face advanced normally.

Jan 1, 1992

Operational effectiveness is fundamental to any operation, becoming highly topical in those experiencing less than optimal output from their fleets. It is all encompassing aiming to identify those factors that could be improved within production and suggesting solutions in order to optimise the existing fleet and obtain the greatest capital return on expenditure.Argyle Diamond Mine (ADM) is a large open cut diamond mine located in the East Kimberley region of Western Australia, approximately 180 km south of Kununurra. It is owned and operated by Rio Tinto on a two week on/two week off roster fly-in/fly-out from Perth or drive in/drive out from Kununurra. Through benchmarking the operation between January and June 2002, a study was undertaken allowing identification of areas falling below target. Following this, analysis of annualised hours and production downtimes were undertaken to quantify the potential gains of improvements in these areas. Strategies were then identified as stated in the 2002 mine plan, in operational effectiveness meetings, and by staff members. This project aimed to maximise direct working hours through determination of the main issues hindering performance. External and internal factors were considered and a continuous improvement program (CIP) was developed. The CIP aimed at internal site-based improvement teams to identify and implement solutions for improvement on a day-to-day basis.

Jan 1, 2003

By Carlos Roberto Silva Mamede

A flotação é um dos principais processos de concentração, tendo sido empregada há mais de um século, viabilizando a obtenção industrial de diversos bens minerais, como sulfetos, óxidos, fosfatos, carvão, sais, platinas e outros. Na indústria de minérios de ferro, a flotação reversa de quartzo tem sido empregada com sucesso para obtenção de concentrados (pellet feed) com elevados teores de ferro (próximos de 69%) através de células mecânicas e colunas de flotação. Amidos de milho ou mandioca como depressores, aminas como coletores e hidróxido de sódio como modulador de pH são os principais reagentes atualmente empregados nos circuitos de flotação de minérios de ferro. O esgotamento das reservas de elevados teores de ferro, levando a necessidade de concentração por flotação de minérios de baixos teores, a necessidade de otimização de custos operacionais e a maximização da recuperação metálica são os alguns dos desafios da indústria de minérios de ferro. Além disto, a variedade mineralógica e a ampla faixa granulométrica (0,300 mm a 0,010 mm) são outros desafios desta indústria. O estudo de coletores de flotação mais seletivos para os diferentes tipos de minérios de ferro pode contribuir para aumento da seletividade desta operação unitária.

Aug 1, 2018

By Phillip N. Yasnowsky

This Bureau of Mines report examines the percentage depletion allowance rate structure in relation to several criteria that are indicative of U.S. mineral import dependence. These criteria are the minerals considered as strategic and critical for stockpiling purposes, the ratio of reserves to forecast cumulative demand (1976-2000) for selected minerals, and the U.S. net import reliance as a percentage of apparent consumption (1978), also for selected minerals in general, it was Found that there does exist a direct, although not perfect, relationship between the percentage depletion allowance rates and the degree of import dependence as indicated by these three criteria. The higher percentage rates tend to he associated with those minerals for which the United States is, or will likely he, heavily dependent on foreign sources. In addition, a basic discussion of the mineral depletion allowance is provided, including numerical examples illustrating the computation of the allowance under several assumptions. Also, the percentage depletion allowance rates for individual minerals are tabulated.

Jan 1, 1980

By Fernanda Lourenço Fábia de Lima

O presente trabalho estuda a corrosão seletiva em chapas de aço inoxidável dúplex UNS S31803 (SAF 2205) imerso em solução de 1 mol. L-1 HCl a 60°C, com o intuito de extrair a fase ferrita, para se obter austenita e então criar padrões desta fase, gerando resultados mais confiáveis na sua quantificação, através das técnicas de difratometria de raios-X (DRX) e de espectroscopia de energia dispersiva (EDS). Este estudo foi realizado com 6 amostras, nas quais a temperatura de solubilização variou de 1.000°C até a 1.250°C, a fim de se obter diferentes frações volumétricas de ferrita, podendo assim avaliar o comportamento de extração desta fase de cada amostra pela sua perda de massa em função do tempo de imersão. Os produtos de corrosão obtidos no ataque seletivo foram analisados pelas técnicas de DRX e EDS, onde se constatou o fenômeno de corrosão seletiva. Nas amostras solubilizadas foram feitas quantificações de fases pelas técnicas de DRX, estereologia quantitativa e ferritoscópio e verificou-se que todas apresentaram resultados distintos sendo que a que mais se aproximou da condição de equilíbrio calculada por Thermo-Calc foi a técnica de estereologia quantitativa.

Aug 7, 2018

By Michael W. Oakland

Deer Island is the site of the Massachusetts Water Resources Authority (MWRA) wastewater treatment plant which, when completed in 1999, will serve 43 cities and towns in central eastern Massachusetts. Deer Island is located in the Boston Harbor, as shown on Figure 1. The existing wastewater treatment plant on Deer Island is being upgraded to include secondary treatment to comply with Federal require­ments. The new treatment facilities will process an average of 455 million gallons of sewage per day; total capacity will be about one billion gallons per day. The new treatment facilities will cover virtually the entire island. [ ]

Jan 1, 1994

By Fred C. Bond

A study of the settling and thickening of finely divided pulps was undertaken with the object of obtaining certain fundamental relationships, with resulting improvements in the design and operation of mechanical equipment. The subject has been treated in two parts: testing and batch thickening, and continuous thickening, including calculations of capacity and dimensions. Part 1. ? Testing and Batch Thickening The usual method of making thickening tests is to agitate the pulp with a plunger in a graduated glass cylinder and let it settle, while recording the time rate of settling. The settling rates corresponding to different pulp dilutions are found, the ultimate dilution obtained is measured, and the necessary thickener area in square feet per ton of dry solids per 24 hours is calculated, for each pulp dilution. The largest area found is used in selecting the proper thickener size.

Jan 1, 1946

An efficient and portable mathematical model has been developed for simulating heat transfer in six-in-line slag-resistance-heating electric furnaces for smelting sulphide ores to produce base metals and platinum group metals. This model is a steady-state one relating furnace conditions and performances to various control and input parameters. Some transient effects occurring in electric furnaces are neglected for computation efficiency. This article describes the model development and modelling results. The present model is capable of predicting: (i) temperatures at various locations in a six-in-line furnace, such as slag bath, matte bath, solid charge, freeboard space, freeze lining, cooling water, and air gaps between solid material components, etc. (ii) freeze lining thickness, (iii)smelting rate, and (iv) heat loss rate, etc. A typical feature of the model is that it is easily portable to different application platforms and sufficiently efficient with execution times less than a few seconds. Therefore, it is possible to apply the model for online prediction and control of heat transfer and freeze lining thickness in industrial electric furnaces.

Jan 1, 2011

By AIME AIME

APROXIMATELY one third of the world's iron ore is mined in the United States; and about 80 per cent of this third is mined in the Lake Superior ore region, and about 60 per cent in Minnesota. The Lake Superior iron ore region covers a vast area in the vicinity of Lake Superior that contained in early geological times large areas of iron-bearing sediments, which today form metamorphosed iron-bearing rocks, such as jasper, chert, taconite, and slates. Concentration of the iron content chiefly through solution and resultant removal of silica produced the ore bodies we find today in rock folds as on the Menominee range, at dike or impervious wall intersections such as on the Gogebic range, and blanket-type enriched ore bodies ly¬ing on or within the ore formation, such as occur on the Mesabi and in steeply pitching ore lenses elsewhere. In many places, folding and subsequent erosion of the tops of the folded areas has resulted in steep dips in the ore formation and contained ore bodies. The upper eroded edges are mostly buried under glacial over-burden. The slightly dipping Mesabi formation is the principal exception as to steeply dipping ore bodies.

Jan 1, 1941

By Raquel Dei Agnoli

Membranas a base de polímeros perfluorosulfonados, como o Nafion® (DuPont), vêm sendo extensivamente usadas como membrana de troca protônica em células a combustível. Contudo, o elevado custo e a baixa condutividade em temperaturas superiores a 80oC restringem o uso destes dispositivos. Em opção ao uso da membrana Nafion®, membranas a base da blenda polindeno sulfonado/polifluoreto de vinilideno (SPInd/PVDF) foram desenvolvidas, investigando o efeito da composição na performance das membranas. As membranas foram produzidas por evaporação de solvente da solução dos polímeros precursores. As blendas foram caracterizadas por termogravimetria e calorimetria exploratória diferencial. A caracterização das membranas eletrólito envolveu medidas de grau de inchamento, capacidade de troca iônica e condutividade protônica. Foi possível observar que o PVDF confere boa resistência mecânica e aumento da estabilidade térmica das membranas. Membrana com 50% em peso de PVDF apresentou a maior condutividade protônica (1,89.10-3S.cm-1). Membranas de SPInd reforçadas com PVDF mostraram resultados promissores para uso como eletrólito em células a combustível.

Aug 17, 2017

By B. P. Baruah

A good deposit of high sulphur coals of tertiary origin is existent in North eastern region of India. These coals are known to have indifferent characteristics in comparison to other Indian coals. The general Physico-chemical characteristics are low ash and high volatile matter, calorific value and sulphur content. Sulphur in these coals (70-95% of organic) is mostly affixed to the structure of the coal. Owing to the stringent environmental regulations, the utilization of these coals has severe limitations due to high sulphur content. In the present investigation, sulphur incorporation in to these coals has been discussed along with possible organic sulphur functionalities. The various desulphurization techniques carried out for removing sulphur from these coals have been discussed. Two step oxidative desulphurization processes has been found to be most efficient for organic sulphur removal along with mineral matter and potential toxic elements. Keywords: oxidative desulfurization, potential toxic elements, sulfur incorporation

Sep 1, 2012

Jan 1, 1967

By A J. Gunson

The Norman B Keevil Institute of Mining Engineering, or the Department of Mining Engineering (the Department), at CanadaÆs University of British Columbia (UBC) is addressing the integration of sustainable development concepts into mining education and research on behalf of industry and society. Over the past decade, the DepartmentÆs education and research model has been evolving to incorporate collaborative and multidisciplinary strategies, where sustainability initiatives are taught in classes, supported in research and discussed in a voluntary collective of mostly graduate students û the Sustainability Working Group (SWG). The SWG has brought together a diverse array of disciplines from academia, industry, government, non-governmental organisations (NGOs) and mining communities. The operational mechanisms and structure of the SWG have enabled momentum to be gained through several multidisciplinary educational and research networking initiatives. It acts to attract new students with diverse backgrounds, foster innovative research, develop relationships and networks, and create the space to discuss progressive ideas and projects. The original cohort of SWG graduate students laid the foundation for sustainable research initiatives within the Department at UBC. Novel research has incorporated topics such as: community resilience, artisanal small-scale mining, sustainability indicators and corporate social responsibility, environmental assessment and impact benefit agreements and the recycling of waste. Propelled by the support of the Department and inspired by the works completed, a host of new graduate students have embarked on their research quests to integrate sustainability principles into their projects. Such projects include: social impacts and benefits of mining, artisanal small-scale mining, community health, the production and transport of mine pollutants, mine waste management, mineral process plant design and the evolution of community education and mine policy. This paper reports on the departmentÆs continuing research and development towards an understanding and evaluations of the ongoing contributions of mining to sustainable development.

Jan 1, 2009

By G J. Lyman

The theory of sampling has progressed slowly over the last century. The concepts of correct sampling were known to mining engineers such as D W Brunton in the 19th century. It was recognised early in the 20th century that the Poisson distribution of particles carrying the target analyte was the key to the uncertainties between samples of a given mass. However, no efforts were made until the 1980s to determine the entire sampling distribution as a function of sample mass. The variance of sampling was made clear by Gy and others, but none attempted to determine the entire sample assay density function until J H Venter in South Africa applied the method of characteristic functions to the problem.Venter applied the method to a specific case of very low analyte concentrations in samples of very fine particle size where his assumption of constant sample mass was justified. When his general methodology is applied to the more general problem, it can be shown that the assumption of constant sample mass is no longer justified and leads to some anomalous results for sampling variance. Venter’s method can be expanded to allow for a statistically variable sample mass and to take into account the size distribution of particles that carry no analyte.This paper presents the basis of Venter’s work and shows how the approach can be easily modified to yield results for the variance that are consistent, for example, with the work of Gy. It is also demonstrated that the entire sampling distribution can be determined without undue computational burden when sufficient information on the material heterogeneity has been collected.CITATION:Lyman, G J, 2014. Determination of the complete sampling distribution for a particulate material, in Proceedings Sampling 2014 , pp 17–24 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By B. Valentim

Policies for reducing NOx emissions have led power plants to restrict O2, resulting in high-carbon fly ash production. Therefore, some potentially useful fly ash, such as the economizer fly ash, is discarded without a thorough knowledge of its composition. In order to characterize this type of fly ash, samples were collected from the economizer of a Portuguese power plant burning two low-sulfur bituminous coals. Characterization was also performed on economizer fly ash subsamples after wet sieving, density and magnetic separation. Analysis included atomic absorption spectroscopy, loss-on-ignition, scanning electron microscopy/energy-dispersive X-ray spectroscopy, optical microscopy, and micro-Raman spectroscopy. Key words: Fly ash; Petrology; Petrography; Economizer fly ash

Jan 1, 2009

By Fabricio Reis de Almeida

O presente trabalho tem como objetivo mostrar os ganhos financeiros e produtivos do Laminador de Aços Longos da CSN através da otimização do plano de passes. Analisando a árvore de calibração identificamos a possibilidade de ganhos com a unificação de famílias de bitolas. No laminador temos duas famílias: Família Ø 5,5 mm (bitolas 5,5; 7,0; 9,0; 11,0; 14,30) e Família Ø6,3mm (bitolas 6,3; 8; 10; 12,5 e 16) para a fabricação destas bitolas utilizamos até 18 passes no laminador duo horizontal/vertical e mais ate 10 passes no laminador acabador cantilever. Após um estudo detalhado do plano de passes existente, verificou-se a possibilidade da eliminação e unificação de passes entre as duas famílias. Para corroborar as alterações propostas, decidiu-se utilizar um modelo matemático que representasse os passes e realizasse os cálculos para verificar as reduções e capacidades dos equipamentos visando minimizar os riscos e custos adicionais com modificações de ferramental. Após mais de 60 horas de simulações e testes, foi desenhado um novo plano de passes para a Laminação eliminando-se a necessidade de troca de 8 cadeiras, o que representa um aumento de 6 horas no tempo disponível para produção por mês e também a redução de 8 pares de cilindros de laminação, redução de guias e roletes, e tempo de preparação na oficina de cilindros. Só após verificação e aprovação desta etapa foram iniciados os testes no laminador que confirmaram os resultados obtidos nas simulações.

Aug 16, 2017

By Ricardo dos Santos Oliveira

Devido ao grande aumento da concentração de gases do efeito estufa, a criação de uma energia limpa tem sido um desafio para a ciência e as indústrias. Após identificar possíveis soluções para este problema uma alternativa seria a utilização de biomassa vegetal com capacidade térmica como fonte energética redutora no processo de redução do minério de ferro em altos-fornos. Este trabalho teve como objetivo utilizar capim elefante (Pennisetum purpureum) e carvão mineral na injeção de finos pulverizados pelas ventaneiras de altos-fornos nas siderúrgicas a fim de reduzir custos da produção de ferro gusa e reduzir a dependência de combustíveis fósseis no processo. O capim elefante é uma fonte renovável e de rápido crescimento que através da fotossíntese captura o CO2 da atmosfera, reduzindo a poluição causada pelos altos-fornos. Para simular a injeção dos materiais estudados foi construído na Escola de Minas - UFOP um modelo de partículas de combustão para analisar as amostras. Outras técnicas são utilizadas para caracterização como combustão, calorimetria, análise de gás, análise química imediata e elementar. Assim, em teoria, esta pesquisa mostra que o capim elefante misturado com carvão mineral através de sua injeção em altos-fornos mostrou-se viável em termos metalúrgicos e ambientais.

Aug 17, 2017

By A. Noble

The design of separation circuits can be a complex, labor-intensive and costly process. While the engineer?s experience along with extensive data sets and simulation are crucial tools for determining the final solution, a more fundamental approach is suitable to compare preliminary options and reduce the number of potential alternatives. In light of this need, the authors have developed the Circuit Analysis Reduction Tool (CART?). This software package relies on the fundamental principles of linear circuit analysis; however, the solution methodology has been streamlined to automatically incorporate stream splitting and unique separation performance for each unit. The resulting tool allows preliminary analysis of circuit designs without the need of detailed feed characterization. In addition to the basic analytical approach, this paper supports the veracity of the methodology with several simulated examples for various separation models.

Feb 27, 2013

By R. L. Derick

On a regular basis, mine personnel should obtain air samples directly from active underground areas as well as remotely from sealed locations. These samples provide mine officials with data relative to the makeup of the various atmospheres. Should conditions underground change, these results can provide a baseline that can assist officials in determining the extent of change. Relating the concentrations of individual gases to time, applying gases to equations, and examining their change over time are tools that have been successfully used to determine if a heating event exists and, if so, the extent of the emergency. These atmospheric status equations have either been developed for the mining industry or adapted from other industries. They serve as tools to assist personnel in determining the condition of underground mine atmospheres. As long as the problem area continues to be ventilated, certain gases, gas ratios, and equations can be used to determine if a fire exists, what type of material could be burning, and what quantity of coal is burning. Once the mine or the involved section has been temporarily sealed, gases, ratios, and gas-derived equations can assist personnel in determining how conditions within the sealed volume are changing over time. To alleviate potential explosions when fresh air is once again introduced into the sealed volume, equations and a diagram have been developed to predict the likelihood of an explosive atmosphere. Similarly, prior to commencing recovery of a mine or section, equations exist that can assist in determining if the fire will rekindle when air is reintroduced. This paper serves as an overview to remind and/or instruct readers about gas-sampling methodologies and gas analyses to assist in determining the status of underground atmospheres.

Jan 1, 2006

By A P. Wilkinson

This paper reports on the implementation of the critical control concept to manage material risks in the mining and metals industries. The critical control management (CCM) approach assumes it is better to identify weaknesses in risk controls before an incident happens as opposed to discovering weaknesses from an investigation after an incident occurs. The first is sometimes referred to as active monitoring and the second as reactive monitoring (Health and Safety Executive and Chemical Industries Association, 2006). Both are needed. However, whilst methods for both active and reactive monitoring of risk controls are well established in many high hazard industries, such as oil and gas, petroleum and chemical industries, until the publication in 2015 of the International Council on Mining and Metals (ICMM) guides, (Good Practice Guide and the subsequent Implementation Guide) (ICMM, 2015), there was no specific mining and metals industry guidance on critical control management. This paper reports on progress in implementing the ICMM guidance drawing on two main sources. First, a benchmarking survey of a representative sample of coal and metalliferous mines, both underground and open cut/pit), sponsored jointly by the Queensland Resources Council and the Queensland Commissioner for Resources Safety and Health in the context of a recommendation that the Queensland mining industry adopts high reliability organisation (HRO) principals (Queensland Resources Council and Commissioner for Resources Safety and Health, 2022). Second, it draws on Noetic’s experience of implementing critical control management in mining and other high hazard industries in Australia, Africa, China and North America (Wilkinson, 2018). The paper describes good practices found and where significant improvements can be made, providing specific and actionable examples of both. From this it also identifies how future guidance on this topic could be improved.

Apr 16, 2024