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By Launa Mallett, Charles Vaught, Jr. Brnich

This paper introduces a technique for incorporating employee participation into the prevention component of a contingency plan. Companies sometimes focus so much energy on response that they forget to put resources into the basics of emergency prevention. The training program discussed here was designed to make employees part of the prevention system. Examples of training materials from the program are provided, a sample method for introducing risk assessment to employees is shown, and a strategy to address limited training time using short videos is explained. Methods for tailoring the training to any worksite and for specific risks are also included. The program is being designed and tested by the Pittsburgh Research Laboratory/NIOSH and employees of an underground coal mine. Examples are taken from the implementation of the program at the mine during the summer and fall of 1998. Results of the program evaluation and lessons learned during the implementation are discussed.

By Chisholm J. M

Why go to the CIS? The vast mineral potential of the Commonwealth of Independent States (CIS) has long been recognised, but it has taken the lowering of the iron curtain to open up the region to serious mineral development consideration by the Western World. The advent of a free market economy and the emergence of the Independent States with pressing needs for foreign investment has led to a greatly improved investment climate. Coupled with the desire for some of the more entrepreneurial resources companies to head the wave of investment to the region, this sequence of events has promised a great deal, but delivered only modest progress to-date. Potential gold project development has provided the major focus, for three reasons: the region is highly prospective for gold, gold projects tend to have a relatively lower start-up capital cost compared to base metal and fossil fuel projects and finally bullion or refined gold is more readily transportable and easier to sell.

Jan 1, 1996

By Claire A. Chanenchuk

Catalytic Extraction Processing (CEP), a technology commercialized by Molten Metal Technology, Inc., a US.-based company, can convert industrial, household, and government wastes into commercial resources. CEP is an innovative elemental recycling technology that uses a molten metal bath to completely dissociate hazardous or toxic components of a feed and convert them to valuable products. The catalytic action of the molten metal bath converts the feed to its elemental constituents and the reducing atmosphere prevents the formation of any dangerous byproducts (NOx, SOx, dioxins, furans, etc.). Selective reactant addition allows engineering of valuable products from otherwise unexploited resources. Synthesis gas is generated from hydrocarbon feeds, ferro-alloys from metallic wastes, and ceramics from select inorganic species. Commercial-scale processing of multiple wastes and waste surrogates has been carried out at a destruction and removal efficiency exceeding 99.9999 wt.%, validating theoretical predictions. Unlike conventional hazardous waste treatment technologies, CEP offers resource recovery, minimal byproduct generation, and the potential for closed-loop recycling.

Jan 1, 1994

By Alfred Jr. Petrick

Modelling of cash flows and calculation of net present value of rate of return over the expected life of a mine/processing unit continues to be the accepted basis for mineral investment decision-making. The computer and spreadsheet programs have greatly improved ability to perform sensitivity and risk analysis, hence our ability to deal with key analytical problems. These problems of cash flow analysis result from the necessity of forecasting an uncertain and risky future. Cash flow models begin with the critical assumption of a "design basis", then integrate all of the variables relevant to the investment decision including forecasts of price, cost, taxation, financial conditions, and company strategy. Alternate "scenarios" portray possible future outcome of the investment decision. The potential for straying from reality is enormous. The computer has eliminated the time consuming hand calculations from the cash flow analysis, but the analyst still struggles with the risk of trying to predict "how the project will really turn out".

Jan 1, 1991

By John D. Price

In the constant search for ways and means of improving the quality of coke and thus making its use at the blast-fornace more satisfactory and economical, it has become increasingly evident that the present laboratory tests do not show the full picture of a coke's value as a blast-furnace fuel. This fact was recognized by Dr. A. C. Pieldner thirty-five years ago: (Ref. 1) here is perhaps no phase of fuel technicology which has aroused more discussion or regarding which there is more difference of opinion than the properties of coke which make it most suitable for blast-furnaces and other uses." Dr. Fieldner followed this assertion with a statement to the effect that men who write on this subject today (1923) have, because of conflicting experimental evidence brought forth in recent years, far less positive opinions on the matter than did writers of some years past. One is led to wonder if these statements are not just as true now as they were when first made.

Jan 1, 1959

By P. D. Kovscek

The Bureau of Mines equipped a longwall shearer with a water-jet-assisted mechanical cutting system to determine the effect of the high-pressure sprays on machine performance, airborne dust levels generated, and size of particles formed. Testing was conducted on a simu-lated coal block (coalcrete) while cutting at a water pressure of 190 psi and at water-jet-assisted pressures ranging from 1,000 to 6,000 psi. The shearer motor energy used by the shearer while cutting coalcrete was determined for each cutting condition. Results indicate that the motor energy required by the shearer for each ton of material cut did not vary significantly as the water pressure was increased. Results of dust measurements recorded near the cutting drum indicate that at water pressures above 3,000 psi, dust reductions up to 85 pct were achieved com-pared with cutting with conventional sprays. Analysis of the particle size distribution during cutting showed that increasing the water pres-sure resulted in increased median particle size. In light of these results, various mechanisms for water-jet-assisted cutting are discussed.

Jan 1, 1986

By Antonella Rocha Ponseggi

O desenvolvimento dos materiais dos eletrodos (anodo e catodo) e do eletrólito de células a combustível de óxido sólido (SOFC) com o intuito de que estas possam operar de forma estável com combustíveis diferentes do hidrogênio é um objetivo central da pesquisa em SOFC. Dessa forma, o objetivo deste trabalho é evidenciar as características microestruturais e o desempenho de materiais para uso de combustíveis hidrocarbônicos e alcoóis em SOFC. Neste trabalho são avaliados, à luz da caracterização eletroquímica e elétrica de SOFC unitárias e estruturas em bicamadas anodo-eletrólito, sistemas materiais do tipo Ni/Cu-Céria/YSZ-LSM sob a alimentação de diferentes combustíveis. Os melhores resultados foram obtidos com o uso de hidrogênio ou etanol, mas novos desenvolvimentos em engenharia microestrutural são prementes. Também ficou evidenciado os problemas de degradação e instabilidade advindos da presença de sulfurados no biogás combustível.

Aug 16, 2017

By S. H. Ash

The Pennsylvania anthracite region is composed of four fields, namely, the Northern, Eastern Middle, Western Middle, and Southern. It is in the eastern part of Pennsylvania and is shown on figure 1. The anthracite industry is confronted with a crucial problem of inundation by water impounded in underground pools in many mines and by infiltration of water from streams and pools on the surface (3). The deposits of anthracite in the United States are limited virtually to Pennsylvania, and the difficulties of this industry have been commonly considered as a State problem rather than a national one (1, 4, 6, 7). Anthracite was discovered in Pennsylvania in 1762, and the first mining company was formed in 1793. It was not until 1812 that anthracite began to receive recognition in the Philadelphia market as a domestic fuel, and by 1838 the annual production was nearly 1 million net tons. Since anthracite mining began, mine water has become progressively more difficult and costly to handle because of the extraction of anthracite both underground and along the outcrops of the beds, until at the present time mine drainage is a major anthracite-mining problem. Mine water is handled at the anthracite mines as follows: (a) by pumping, (b) by drainage tunnels, (c) by combination of pumping and drainage tunnels, and (d) by water hoists (hoisting water by means of large buckets) (4, 5,6, 7). This paper covers removal of the water from mines by means of pumping plants. Pumping is indispensable in the production of anthracite (5). The cost of pumping mine water has increased progressively since anthracite mining began. Some collieries have been forced to discontinue mining because of the high cost of pumping.

Jan 1, 1950

By Ira L. Wright

This paper describing the milling practice of the Black Hawk Consolidated Mines Co., is one of a series being prepared by the United States Bureau of Mines. ACKNOWLEDGMENTS Part of the information contained in this paper was furnished by I. H. Stanley, mill superintendent, Black Hawk Consolidated Mines Co., Hanover, M. M., and a part by the South-western Engineering Corporation, Los Angeles, Calif. The assistance of T. G. Chapman in arranging the paper for publication is also acknowledged.

Jan 1, 1930

By Leslie Perterson

O trabalho teve o objetivo de analisar a atual condição de descarepação da empresa X e fornecer a melhoria no processo por meio da substituição dos chuveiros, troca dos bicos de descarepação e até mesmo a combinação desses dois fatores. Para isso, foram avaliadas a velocidade do escoamento interno dos chuveiros, a turbulência gerada e eficiência dos atuais bicos instalados por meio de análise CFD (Computational Fluid Dynamics). Em posse desses dados, foi possível sugerir a configuração ideal dos chuveiros no que diz respeito ao diâmetro da tubulação, espaçamento de bicos e o bico de descarepação adequado para otimização do impacto, tendo o objetivo final de melhorar a eficiência da descarepação do processo de laminação da empresa X.

Aug 16, 2017

By Eduardo Cabral

A nova política de resíduos sólidos, imagem positiva da empresa, utilização consciente de recursos com a consequente redução de custos e preservação do meio ambiente têm levado as minerações e siderúrgicas a adotar uma gestão responsável com relação aos seus coprodutos. Em consequência, esses coprodutos (escorias e lamas da mineração, lamas de aciaria, pós da sinterização, calcinação, coqueria, carepas e outros resíduos da siderúrgica) estão sendo economicamente reintroduzidos no processo produtivo. Esse trabalho pretende fazer um resumo de possíveis tratamentos que esses materiais podem sofrer, como umectação, aglomeração, briquetagem, granulação, pelotização ou extrusão.

Aug 16, 2017

By Bernardo de Oliveira Costa

O tempo de mistura em panelas de aciaria foi avaliado em diversos trabalhos através de modelamento físico e matemático. A maioria destes trabalhos está focada em analisar os efeitos da vazão de gás e localização dos plugs porosos usados para injeção. Em artigos recentes, o uso de dois plugs de injeção foi investigado, mas ainda há uma controvérsia significativa sobre a melhor posição para injeção de gás. Nestes artigos, a vazão de gás é distribuída igualmente entre os dois plugs de injeção. Neste trabalho, foi feito modelamento físico para avaliar os tempos de mistura de panelas de aciaria equipadas com dois plugs porosos. O modelo físico foi construído na escala de 1:5 de uma panela de 170 toneladas usada em uma planta brasileira. Os tempos de mistura foram apurados usando a injeção de um traçador. Diferentes combinações de posição dos plugs porosos e distribuição da vazão de gás foram ensaiadas. Experimentos de visualização do escoamento também foram desenvolvidos utilizando tufts e injeção de corante. Estes experimentos foram úteis para análise dos resultados.

Jul 30, 2018

By C J. Carr

The Ernest Henry Mine (EHM) is owned and operated by Xstrata Copper and is located in North-West Queensland, Australia. The mine is currently undergoing a transition from an 11 Mtpa open pit mine to a large sublevel cave underground mine producing 6 Mtpa. Due to a number of factors, including geometry of the pit and crusher depth, the decision has been taken to develop a hoisting shaft rather than inclined conveyors.During the feasibility study the strip and line shaft sinking methodology was preferred over blind sinking due to scheduling opportunities and interactions with level development. Other methods of sinking considered included large-diameter raise boring, which was rejected due to concerns relating to centreline accuracy. The strip and line decision was reviewed during the tender process where better than anticipated blind sink advance rates and costs were presented. This in turn enabled the higher cost of the blind sinking method to be justified by a combination of reduced risks including schedule and ground water management. This paper discusses the pros and cons of both strip and line and blind sinking methodologies in the Ernest Henry context including sinking rates and total schedule impacts of the two methods, the key risks associated with each method, cost implications of blind sinking and safety implications of the work methods in general. The paper then concludes with the reasoning behind the decision to change to blind sinking for the EHM shaft.

Mar 21, 2011

By L. R. Burdick, R. Wiggers, J. F. Berkley

"INTRODUCTION On February 23, 1944, Solid Fuels Administrator Harold L. Ickes stated that the existing fuel shortage made it necessary to utilize a great surplus of freshly mined anthracite ranging in size from Barley (No. 3 Buckwheat) downward through the smaller sizes. As a part of the program to increase the use of such coal, field trials of mixtures of bituminous slack coal and anthracite Barley were made on industrial-size stokers at many fuel-burning plants. The following covers the test information it was possible to accu-mulate during the work of initiating the use of these mixtures at the plants.SUMMARY AND CONCLUSIONSField tests of various mixtures of bituminous slack coal and anthracite Barley on industrial-type stokers show that the use of such mixtures is very practicable and that it is possible to change and usually to adjust to an improved condition the characteristics of a fuel bed of eastern bituminous slack coal by the addition of proper amounts of anthracite. The improved uniformity of the fuel bed of single-retort stokers makes possible less manual attention to the bed. Air flow through the fuel bed is affected.Smoke is decreased. In general, the fly ash and also the unburned combustible in the fly ash and refuse are increased. Clinkering in the fuel bed is generally lessened. The peak-load carrying capacity of the stoker is definitely affected, usually adversely for the higher percentages of anthracite."

May 1, 1946

By Jorge Blázquez, Paulo Couceiro, Patricio Vergara, Luis Martínez, Juan Navarro

This study introduces the X-2Mill solution, a refined two-step methodology aimed at optimizing blast designs by aligning explosive energy with rock properties. The approach employs the X-4Traits Model, which uses drill-monitoring data from both autonomous and manual drilling modes to develop two critical indexes: the Drilling Rock Factor (DRF) and the Drilling SAG Power Index (DSPI). The DRF integrates the Size-Energy Fan Model with rock fragmentation results and blast design parameters, while the DSPI adjusts Specific SAG Energy (SESAG) based on Bond’s theory, incorporating ore X80 results, SAG mill capacity (TPH), and power draw to estimate milling difficulty. To enhance prediction accuracy, the X-2Mill solution incorporates, to a Principal Component Analysis of the normalized drilling data, a Meta Machine Learning model with a 3D spatial function, accounting for information from surrounding drill holes. This integration improves the precision of the DRF and DSPI estimates. The methodology unfolds in two main steps: Step 1: Bench-Scale Pattern Design, involves defining the target P80 size for ore based on the SESAG and the DSPI. It also establishes target X80 sizes for waste and oxide materials and iterates to determine the optimal Burden x Spacing (BxS) using the Size-Energy Fan Model and the DRF. Step 2: Blast-Scale Selective Explosive Density/Energy focuses on refining explosive density on a hole-by-hole basis to achieve the specified X80 values for ore, waste, and oxide materials. The X-2Mill Solution was developed at Minera Escondida Limitada (MEL) using data from 162,761 blastholes across 356 blasts conducted over three mine expansions. This solution addresses the challenges of blasting harder and more difficult rock, particularly in the lower levels of the mine. By adapting the blast pattern and explosive density to the specific rock properties and ore/waste designation, the X-2Mill Solution aims to achieve precise size distributions and improve overall blasting performance. The results demonstrate that the X-2Mill Solution balances ore fragmentation to meet SAG mill throughput requirements while optimizing powder factor costs for waste material and maintaining digging efficiency. By efficiently distributing explosive energy, the solution not only enhances throughput but also improves blasting efficiency while ensuring stable slopes and minimizing fault activation.

Jan 21, 2025

By J. Richard Kyle

The Pb-Zn ore bodies in the Pine Point district are localized in paleo-solution structures that developed as the result of post-middle Givetian subaerial exposure of the carbonate barrier complex. Sulfides are concentrated in transgressive pale-solution structures that acted as natural bypasses between aquifers and loci for mixing of fluids of different character, one of which contained metals and the other reduced sulfur. Complex ore textures indicate rapid early sulfide precipitation followed by slower sulfide growth. Evidence for both sulfide-carbonate equilibrium and disequilibrium conditions suggest fluctuations in ore fluid composition. District and ore body metal distribution patterns may reflect the nature and movement of mineralizing fluids.

Jan 1, 1979

By Jael Moutinho dos Santos

Em função do elevado consumo de corpos moedores de alto Cromo e do alto custo de sua fabricação com matéria prima nobre, busca-se o desenvolvimento de novas ligas de corpos moedores na busca de um melhor custo benefício. Devido ao efeito sinérgico do perfil de desgaste envolvendo fenômenos corrosivos e abrasivos em bolas de moinho, o desenvolvimento de novas ligas de ferro fundido branco alto cromo tem sido uma alternativa para suportar o desgaste precoce provocado por tais fenômenos. As amostras de corpos moedores, analisados mediante ensaio de análise química, dureza, análise micrográfica e seguidos de ensaios de moagem (úmido e seco), servirão a um desempenho comparativo para se designar a melhor liga a ser aplicada nos processos de moagem secundária de minério de ferro a úmido.

Oct 30, 2017

By José Lucio Gonçalves Junior

A simulação laboratorial do desgaste é fundamental para o desenvolvimento de pesquisas que objetivem otimizar revestimentos e modificações superficiais utilizados em cilindros de laminação reais. Este trabalho objetivousimular laboratorialmente os mecanismos de desgaste em cilindros de laminação a frio. Para tanto, foram feitas réplicas metalográficas dos cilindros de trabalho antes e após campanhas de laminação normais. Foram utilizadas amostrasde aço VC10 temperadas, texturizadas e cromadas. Para reproduzir os mecanismos de desgaste,foram utilizados cilindros e esferas de aço AISI 52100 como contracorpos em ensaios de deslizamento alternado, com cargas normais de 51,01 e 100,06 N para contracorpos cilíndricos e 31,39; 51,01 e 100,06 N para contracorpos esféricos. Os resultados obtidos com contracorpos cilíndricos, carga normal de 100,06N e tempo de ensaio de 5h e contracorpo esférico, 29,4 N foram os que melhor reproduziram as tendências de alteração de topografia de superfíciesencontradas nas réplicas dos cilindros após uso. Após, realizou-se a análise tribológica dos pares, constatando-se que a utilização de contracorpo cilíndrico não remove completamente a camada de cromo duro, permitindo assim ver diferenças de comportamento tribológico em função da posição sobre a trilha e a análise experimental da evolução das tribocamadas formadas.

Aug 16, 2017

By Lucas Gonçalves Generoso, Larissa Rodrigues de Carvalho Rocha, Gerson Evaristo de Paula Júnior, Beatriz Fausta Gandra

A eficiência na redução dos minérios de ferro no alto-forno é governada pela estrutura e permeabilidade das camadas de carga. A zona granular do alto-forno é a região onde a carga mantém a sua estrutura estratificada, decorrente do carregamento, sob a forma de grãos sólidos. Nessa região, as condições de permeabilidade determinam o perfil de distribuição do gás e, consequentemente, a eficiência térmica e química do reator. Na Usiminas, foi desenvolvido um ensaio de permeabilidade que permite avaliar a perda de carga em leitos formados pelas matérias-primas utilizadas nos altos-fornos, buscando as condições mais favoráveis ao fluxo gasoso. A partir deste ensaio, foi possível avaliar cargas compostas exclusivamente por sínter, pelota ou minério granulado, ou ainda combinações binárias entre estes. O sínter apresentou a maior perda de carga, seguido da pelota e do minério granulado. Apesar disso, o sínter foi o material que permitiu maior acréscimo de vazão do gás. Os ensaios realizados indicaram que 5% de material com granulometria menor que 5 mm é o limite para a concentração de finos do sínter, situação em que foi observado acréscimo de aproximadamente 50% na resistência à passagem dos gases para as velocidades correspondentes àquelas dos altos-fornos. O leito de melhor permeabilidade foi formado por 95% de sínter e 5% de pelota, seguido pelo de 100% de sínter, sem diferença significativa entre essas condições. Em geral, a combinação de sínter e pelota é mais benéfica para a permeabilidade do leito.

Oct 1, 2019

By Alessandro de Castro Corrêa

A comparação de processos de soldagem é uma tarefa complexa por envolver diversos atributos. A designação dos pesos dos atributos a serem avaliados é uma etapa fundamental na análise de problemas multicritérios; contudo, por vezes, a única informação que se obtém é a ordem de prioridade. O objetivo deste trabalho foi calcular os pesos das propriedades destinadas à comparação de processos de soldagem em aço inoxidável AISI 316L para o reparo de eixo naval com base na ordenação fornecida pelo tomador de decisão. Os atributos considerados foram taxa de deposição, energia de soldagem, rendimento econômico, diluição e relação reforço-largura. Os métodos de atribuição de pesos aplicados foram o de ponderação igual (Equal Weights), ordenação recíproca (Rank Reciprocal), somatória (Rank Sum), ordenação exponente (Rank Exponent) e o método do centroide (Rank Order Centroid). Para se verificar o efeito da escolha dos pesos estimados numa avaliação multicritério, avaliaram-se dados reais, aplicando-se a Ponderação Aditiva Simples (Simple Additive Weighting). Os resultados indicaram que diferentes atribuições de pesos podem alterar a posição das alternativas. Foi sugerido que a elaboração tabela ou gráficos com as distribuições de pesos pode ser útil para que o tomador decisão identifique a que melhor reflete as suas preferências.

Oct 30, 2017