Search Documents

By Bryan Ulrich

Knight Piésold and Co. hosted its annual roundtable discussion on March 17, 2011 at the Stockman Hotel and Casino in Elko, NV. The theme for Roundtable 2011 was, ?High density tailings, paste, and filtered tailings,? although the topic may well have been subtitled, ?Don?t prematurely rule out any technologies before they are given their day in court.? Bryan Ulrich, Knight Piésold?s local representative, as well as Tom Kerr from Knight Piésold?s office in Denver, CO, were on hand to help facilitate the discussion. Ulrich and Kerr are senior vice president and president of Knight Piésold?s U.S. practice, respectively. The event played host to more than 30 attendees from several western states. Attendees included personnel from a dozen mining properties and various corporate offices. There were also attendees from manufacturing and specialist consulting firms who have been providing services to various high-density tailings, paste and filtered tailings operations worldwide. It may be noted that the term ?filtered tailings? is used in this discussion. Alternative terms, such as ?dry stack? or ?dewatered tailings,? should be avoided whenever possible, as such terms tend to give a false sense about the nature of the material since these materials typically still retain a significant amount of moisture.

Jan 1, 2011

By A. G. Yapo, T. W. Camm

"Mining plays a key role in the development of modern civilization as a source of essential raw materials and provider of essential fuels, producer of jobs and a factor in support of the international balance of monetary payment (Camm, 2014). Professionals in mining locate, develop, design and manage ore deposits in an environmentally safe and profitable manner. As mineral deposits become increasingly scarce, new challenges face the industry. A current trend is to an increased emphasis on underground mining techniques for deeper deposits. Operations are safer now than before as companies understand better their work environment and the importance of mining responsibly.A continual challenge for the industry is accurately reflecting the costs and selling price of ore. An enduring characteristic of mining is the situation where the market typically determines the price of a commodity; the main control a company has on the bottom line is to control the cost of production.An attempt to bring light and clarity to the cost of their business will give a better idea to investors on the true profitability of the mining business. Gold producers face this struggle to accurately reflect the cost of production while also seeking to attract the interest of the investment community (Hill, 2013). In order to have a consistent format to report on their production costs, leading gold producers, through their alliance inside the World Gold Council (WGC), worked on the adoption of a new cost framework: the all-in sustaining cost (AISC) and all-in cost (AIC).Since 1996, the traditional cash cost reporting has focused only on the mining and processing costs incurred in mining an ounce of gold, which included the costs of goods sold (labor, energy, and consumables costs) and royalties (Table 1). But cash cost reporting ignores many important aspects, like sustaining capital, general and administrative expenses and site rehabilitation at the end of the mine life (Whelan, 2013). The cash cost was used to attract many investors into the business. In fact, the high gross margin (sales minus cash costs) has been promoted in past decades by the industry instead of the net or operating margin. As a result, even when the gold price was high, nearly $61/g ($1,900/oz) in August 2011, gold producers were not reporting excessive profits in their cash flow/income statements, to the disappointment and incomprehension of investors (Milstead, 2014). The truth was simply that the other costs omitted in the traditional cash cost were reducing the apparent profits.The disconnect led to a need for more accurate cost reporting in order to win back investor confidence and provide better understanding of gold mining economics. In 2012, the senior gold mining companies, including Gold Fields, Barrick Gold Corp. and Newmont Mining Corp., worked with the WGC to develop a new measure. This resulted in the June 2013 publication of the new framework AISC and AIC, which has been widely embraced by the sector since Jan. 1, 2014 (WGC, 2013).The adoption of the new cost template would have the dilemma of showing the real profitability of gold mine properties, which might alleviate taxes from governments and legislators, but it might also scare off investors toward more lucrative industries if not winning back their confidence."

Jan 9, 2017

By R. C. A. Minnitt, A. Akpabio

This study presents a rigorous comparison between ordinary kriging and commonly used machine learning algorithms, those being, linear regression, support vector regression, decision trees, random forests (RF), and k-nearest neighbours for spatial interpolation of platinum grade estimates in a complex ore body within the Bushveld Igneous Complex. Using only X and Y coordinates as predictors, both ordinary kriging and machine learning models were evaluated at point and block supports under traditional and spatial block cross validation frameworks. While naive validation results suggested superior performance for k-nearest neighbour and random forest (R² = 0.92 and 0.86, respectively), these were revealed to be overly optimistic under spatial dependence. Spatial block cross validation results demonstrated substantial declines in model performance, with R² often falling below zero, particularly for decision trees and k-nearest neighbour, indicating strong overfitting and limited generalisability. Ordinary kriging exhibited more stable, albeit modest, performance under spatial validation, reflecting its strength in geostatistical interpolation when contextual geological variables are unavailable. The study underscores the critical importance of spatially aware validation in resource estimation and highlights that machine learning models constrained to spatial coordinates behave as interpolators rather than true learners of geological variability. Recommendations are provided for future work incorporating geological information to enhance predictive robustness.

Mar 30, 2026

By M. Rylatt, E. Legault-Seguin, C. Mohns

"With energy costs increasing and ore grades diminishing, the role of preconcentration in hard-rock mining operations has gained greater interest. Dense medium separation is a process that can be conducted at particle sizes from 250 to 0.50 mm with high separation efficiency, depending on liberation characteristics of the valuable minerals. Pilot-plant case studies conducted at the SGS Lakefield site are presented, including mineral systems such as spodumene, sulfide-bearing gold ores, and complex sulfide ores. These case studies demonstrate that, for amenable ores, mass rejection of 20–60% is possible while maintaining recoveries of greater than 90%.RÉSUMÉ Au vu de la hausse des coûts liés à l’énergie et du déclin de la teneur des minerais, le rôle de la préconcentration dans les exploitations minières en roche dure présente un intérêt croissant. La séparation (ou concentration) en milieu dense est un processus pouvant être mené sur des calibres de grains de 250 à 0.50 mm avec un rendement élevé de séparation, en fonction des caractéristiques de libération des constituants des minéraux métallifères. Sont présentées dans cet article des études de cas menées dans des usines pilotes du site de Lakefield de SGS, lesquelles incluent des systèmes de minéraux tels que le spodumène, les minerais aurifères sulfurés et les minerais sulfurés complexes. Ces études de cas montrent que pour les minerais présentant les caractéristiques de libération appropriées, il est possible d’atteindre un rejet en masse de 20 à 60 %, tout en maintenant des récupérations supérieures à 90 %.INTRODUCTIONPreconcentration is the process of rejecting gangue minerals while ensuring recovery of valuable minerals prior to more intensive, downstream processing. Preconcentration has been practiced in the industry for many years, and is gaining greater interest as the industry copes with processing lower grade, more difficult ores, which typically require finer grind sizes and incur higher energy costs.The benefits of preconcentration are:• lower mining costs, which allows for nonselective mining;• lower process capital and operating costs (e.g., resulting from reduced grinding, flotation, and fines disposal stages);• increased ore reserves, which provides the potential to treat lower grade ore;• increased mine production without expansion of the existing plant or concentrator;• reduced overall tailings impoundment by converting the reject into a byproduct (e.g., underground backfill or aggregate);• improved efficiency of downstream processes (e.g., silica removal in electric arc furnace feed, removal of softer sliming minerals prior to grinding);• potential application to brownfield operations and greenfield projects; and• a “green” process option, which reduces processing energy consumption;– reduces mill feed;– increases stage metal recovery (higher grade feed);– increases mill metal output per tonne processed;– reduces surface plant, tailings dump, and tailings pond requirements because the plant has a small footprint and can be installed underground; and– can be applied to retreatment of old tailings dumps to recover metal values and reduce environmental impacts (e.g., dissolved metal runoff, acid drainage)."

Jan 1, 2017

By Frieda Saicla Barros

Argamassas feitas com cimento são comumente usadas para revestimentos de paredes, pisos e tetos. Para proteção radiológica, estas argamassas são acrescidas de pó de bário, elemento atenuante contra radiações ionizantes. Este trabalho tem como objetivo principal comparar argamassas usuais utilizadas como revestimento de paredes com a argamassa baritada, cuja finalidade é proteção radiológica em ambientes sujeitos a radiação ionizante. Com base no objetivo proposto, estabeleceu-se a metodologia do trabalho constituída das seguintes etapas: caracterização dos materiais constituintes das argamassas por meio dos ensaios de análise química por fluorescência de raios-X, análise granulométrica, determinação das densidades experimental pelo método de pesagem e medição volumétrica manual dos corpos de prova, moldagem dos corpos de prova das argamassas normais e argamassa baritada (material comumente utilizado para proteção radiológica), avaliação das propriedades mecânicas e avaliação da atenuação da radiação X utilizando o programa Xcom. Por meio deste programa, foram simulados os coeficientes de atenuação em massa das composições, gerando curvas de atenuação, no intervalo de energia estimado a cada 0,01 keV. Em função destas curvas de atenuação em massa, verificou-se o desempenho das argamassas comparando-as com outros materiais desenvolvidos e com materiais de referência (chumbo).

Aug 8, 2018

By Bruce I. Thomas

The occurrence of tin-bearing gravels along Tozimoran Creek in central Alaska has been known for a number of years. In September 1944 the Bureau of Mines investigated an area approximately 1,000 feet long and 200 feet wide along Tozimoran Creek to deter-mine the cassiterite content of the stream gravels, which are about 4 feet deep and covered by 3 feet of overburden. Nine trenches and two shafts were excavated, from which samples of the underlying gravels were taken. This report contains a discussion of sampling methods and tables giving the results of analyses.

Jan 1, 1948

By AIME AIME

T HE Mining Methods Committee held its initial meeting* on Tuesday afternoon, with F. W. Bradley in the chair and W. Y. Westervelt as vice- chairman. The first paper to be presented was "A Plea for a U. S. Court of Patent Appeals," for which Kenneth W. Greenawalt ably pleaded. The paper (which was published in full in last month's issue) is so carefully prepared that no synopsis can do it justice. It discusses the opposed views of some patent lawyers and other lawyers and members of the judiciary as, for example, Chief Justice Taft who is quoted as saying in 1921: "I think it is a great deal better to take a first class lawyer and a first-class judge and make him a good patent expert than it is to take a patent expert and try to make him a first-class lawyer and a good judge." Mr. Greenawalt argued the need for specialized scientific and engineering interest and understanding to enable a lawyer or judge to prepare or interpret patent specifications and decide the originality necessary for a valid invention. He proposed the special U. S. Court of Patent Appeals to also counteract the costly confusion and injustice now ruling where a patent may be declared valid in the courts of certain States and invalid by the courts of other States.

Jan 1, 1930

By Francisco Belmino Romero, Walney Silva Araújo, Vitória Lima de Souza, Edilberto Rocha Silveira, Adriana de Oliveira Sousa Leite

O uso de inibidores verdes na corrosão do aço carbono SAE J403 1020 configura-se como uma alternativa econômica e ambientalmente acessível, pois, em relação aos inibidores comerciais geralmente utilizados, são de fácil obtenção, já que são adquiridos a partir de vegetais, portanto, não oferecem risco ao meio ambiente. Assim, o presente trabalho tem como objetivo avaliar o uso das folhas de aroeira como inibidor de corrosão para o aço carbono SAE J403 1020, o qual é bastante utilizado na indústria e possui baixa resistência à corrosão. A escolha da aroeira se deu devido ao fato de a planta ter origem no Brasil e abundância no Nordeste do País, principalmente no Ceará. Para análise, foram utilizados como meio corrosivo: H2SO4 0,1 M, NaCl 3,5% e NaCl (ph = 4,0); as concentrações do inibidor foram: 50, 200, 500 e 1000 ppm. Em relação aos ensaios eletroquímicos, utilizou-se: Potencial de Circuito Aberto (OCP), Espectroscopia de Impedância Eletroquímica (EIE) e Curvas de Polarização Linear (CP). Dessa forma, por meio da análise das técnicas mencionadas, conseguiu-se obter o comportamento do inibidor em relação ao material e ao meio, bem como avaliar qual o melhor meio para a utilização da aroeira como inibidor verde de corrosão.

Mar 1, 2019

By Robert L. Frantz

The U.S. Bureau of Mines (USBM) established on August 15, 1983, a Generic Mineral f Technology Center (GTC) for Respirable Dust within the Mining and Mineral Resources Research Institutes (MRIs) at The Pennsylvania State University (PSU) and West Virginia University (WW) in association with participating MRIs at Massachusetts Institute of Technology (MIT) and the University of Minnesota (UMN). The primary goal of the Center is to reduce the incidence and severity of respirable dust disease through researching and advancing the fundamental under- standing of all aspects of respirable dust associated with mining and milling and the interaction of dust and lungs. Other Center activities include the training of engineers and scientists, graduate students and undergraduate students through their respective institutions, and the technology transfer to the industry. The Center also serves as the reference center for publications in the respirable dust area.

Jan 1, 1986

By P. W. J. Delport, E. Du Toit

Investing in a mining venture can be risky and stakeholders need transparent, unbiased reports to understand the Mineral Resources and Mineral Reserves a mining company holds. Readability and textual choice can be used consciously to manipulate perceptions, or it can be done unconsciously. This exploratory study investigates the readability and textual choice of supplementary Mineral Resources and Mineral Reserves Reports of companies listed on the Johannesburg Stock Exchange. The results indicate that narrative manipulation occurs in these reports through word choices that make the reports difficult to read, as well as specific narrative selections. This reduces the informational value of the reports. The results of the study will be useful to various stakeholders, such as mining company management, investors, investment specialists, financial analysts, and even employees and the general community, who all use these reports to make important decisions. It is also useful for the preparers of the Mineral Resources and Mineral Reserves Reports, Competent Persons, and other technical specialists to be aware of readability and that certain textual choices can affect the interpretation of these reports. It is recommended that bodies such as the JSE and the SAMREC and SAMVAL Code committees consider adding a plain language requirement to regulations, guidelines, and codes to ensure transparent, unbiased, and objective reports.

Mar 1, 2021

By Andrea Gambi, Giancarlo Olivucci, Maurizio Lenzi

"In the paper a criterion for the evaluation of the sharing of the lateral loads in a piled foundation is presented. It relies on the the compatibility condition between the rotation of the rigid pile cap and the rotations of the pile heads, following in that the criterion suggested by the Eurocode 8 - Part 5. This assumption leads to an analytical solutions which allows to deal with the sharing of the lateral loads and moments by means of two main interaction parameters only. A sharing domain is also derived and it shows the role played by the eccentricity of the lateral load on the values of the axial forces and of the bending moments at the head of the piles.INTRODUCTIONIt is well known that the interaction among soil, piles and foundation is one of the most complex subject to deal with in Geotechnical Engineering. Its rigorous study needs to employ suitable finite element software nowadays available and able to take into account the non linear behavior of the soil as a continuum and the inelastic response of the structure. A deep insight to the topic of the sharing of the loads cannot obviously renounce to this approach.On the other hand it is a daily need of the designers to have at their disposal simple tools that allow to make preliminary evaluations of the basic equilibrium conditions. To this purpose many methods of analysis have been developed in the past to face the sharing of the loads in a simplified version. The present contribution follows this way trying however to introduce some improvements that leads to find a solution that satisfies both the equilibrium of the forces and the compatibility of the movements (Lenzi, Gambi, Olivucci, 2002). The proposed model allows to identify the basic parameters which govern the sharing of the lateral load and it allows to perform also parametric analysis and quick checks that may be useful in the design of the piles."

Jan 1, 2005

By D. Harrington

The fiscal year which ended June 30, 1932, although one of acute financial de ression was, nevertheless, one of distinct encouragement to those who have long struggled against the much too prevalent occurrence of accidents in coal mines, especially of coal mine fire and explosion dis- asters, both of which are now known to be readily preventable. Table 1 summarizes some important information about explosions in the United States coalies for the fiscal year which ended June 30, 1932, insofar as such information is available to the safety division of the United States Bureau of Mines, the personnel of which are under instruction to get in touch with and report on all mine explosions in their respective districts, including not only those occurrences with loss of life but also those in which for- tunately no lives, are affected. Table 1 gives data on 33 ignitions in 10 States with a total of 87 deaths for the year; the number of ignitions (33) is considerably groater than the number (26) for the previous fiscal year, and is exactly the aver- age number for the past four fiscal years; the mumber killed in the 33 ignitions (57) is materially lower than that (217) for the preceding fiscal year or the average (150) for the past four fiscal years. The States with the greatest number of deaths from explosions in the fiscal year ending June 30, 1932, were Virginia; 54; West Virginia, 11; Pennsylvania, 7 (6 being in anthracite mines); Alabama and Colorado, 4 each; Illinois and Kentucky, 3 each; and Maryland, 1. The greatest number of ignitions listod wes that for West Virginia, 7; then came Pennsylvania with 6 (2 being in anthracite mines); Alabama with 5; Colorado, Illinois, Tennessee and Virginia, 3 each; and California, Kentucky, and Maryland, 1 each. The 1931-32 record as given in Table 1 includes several States which were not listed in the previous year: Colorado, Kentucky, Maryland, Tennessee,

Jan 1, 1933

By W. Fander, Zhonghan Zhang, T. Choo, J. Enraght-Moony

"This paper describes the mineralogical and metallurgical procedures used to determine the recovery and concentrate grade of heavy oxide minerals occurring in lode deposits. The data produced also provide vital information to the processing engineers, which allows them to develop the most suitable flow sheet for that particular heavy mineral, here called an Economic Oxide Mineral (EOM). It demonstrates how results are interpreted to ensure that the proper process is used at each treatment stage to optimise recovery and to produce the most suitable concentrate at that point. Reference is made to some of the current equipment and techniques that can be used to process EOMs. The paper shows that when assessing the economic potential of a new ore body, or existing ore treatment plant, ore characterisation (OC) is necessary. This is especially true for EOMs such as cassiterite (SnO2), wolframite ((Fe, Mn, WO4,) pyrochlore ((Na,Ca)2Nb2O6(OH,F)), and tantalite (MnTa2O6) where often what seem to be small changes in ore types can have major effects on recovery and concentrate grade. Due to advances in flotation technology scheelite (CaWO4) in some deposits can be less vulnerable to OC variability than other EOM’s. Thorough mineralogical examination is shown to be the fundamental basis of correctly undertaking OC. This is because mineralogical analysis identifies each of the steps required to ensure that all ore types and zones are recognised, and differences explained, and shows the benefit in using reference samples to compare differences in the ores. The OC methods used for EOMs containing metals such as tantalum, tin, tungsten and niobium are similar; if two or more of these EOMs occur in one deposit as separate minerals, then OC will show when and how these minerals should be separated. The OC techniques described for EOMs can also be tailored for other heavy minerals, precious metals and graphite."

Jan 1, 2014

By Kenneth R. Hancock

The importance of "Mineral Pigments" can best be shown by noting that the world production is estimated to be in excess of 47 billion kilograms (52 million st). This quantity if pack- aged in the common 22.6 Kg (50 Lb.) bag and placed end to end would circle the world over 500 times. This world production figure is based on a broad concept that pigments, extenders, and fillers have essentially similar functions. In this paper mineral pigments are products produced synthetically or from selected minerals and through pulverization have characteristics of pigments.

Jan 1, 1985

By Pedro Boson Gambogi

Aços com microestrutura completamente perlítica são utilizados para fabricação de componentes submetidos a condições severas de carregamento mecânico frequentemente combinado com atrito. Estes aços têm desempenho mecânico afetado principalmente pelo espaçamento interlamelar da perlita. O objetivo deste trabalho foi demonstrar os benefícios do uso da Microscopia de Força Atômica para determinar o espaçamento interlamelar da perlita de um aço eutetóide laminado a quente. Para tal, imagens da microestrutura de amostras retiradas na direção longitudinal e transversal à laminação foram obtidas e processadas com auxílio de um Microscópio de Força Atômica. Como resultado, destaca-se o fato da técnica utilizada ter se mostrado uma ferramenta versátil para caracterização quantitativa do espaçamento interlamelar da perlita. Foi observado espalhamento dos valores medidos do espaçamento interlamelar principalmente influenciado pelas condições de resfriamento do aço durante a transformação austenita-perlita.

Aug 16, 2017

By Christopher J. Bise

The objectives for the research project, "Coal Mine Injury Analysis: A Model for Reduction Through Training," were to identify and develop a means to indicate deficiences in human performance, job skills, and/or knowledge at a given mine site that are amenable to alleviation through training or job redesign, and to provide ;I set of analytical tools and training resources that will enable mine training personnel to effectively incorporate the noted deficiencies into a personalized model training program. The findings of this research project are contained in Light separate volumes. Volume I represents the Executive Summary of the study and provides a broad overview of the project's individual areas of emphasis and deliverables. The additional eight volumes provide greater detail on the development of a Model Mine Training Program based upon Professional Database Analysis, Incident Reporting, Loss Control, Job Safety Analysis, Risk Assessment, Cost/Benefit Analysis, and Mine Safety Management.

Jan 1, 1993

By Priscila Graziela Melo Martins

O tamanho de grão austenítico é um parâmetro que influencia o desempenho de tratamentos térmicos em aços, assim como suas propriedades. Neste contexto, este trabalho investigou o uso de um reativo para ataque por imersão (240ml de água destilada, 2ml de HCl, 2g de ácido pícrico e 5 gotas de detergente neutro) para avaliar a influência da temperatura e do tempo de austenitização sobre o tamanho de grão austenítico de um aço ABNT1045 austenitizado nas temperaturas de 860ºC, 950ºC e 1100ºC por intervalos de tempo de 40, 90 e 180 minutos. As amostras austenitizadas foram temperadas em água, metalograficamente preparadas e atacadas com o reativo proposto com o objetivo de se revelar os antigos contornos de grãos austeníticos. Os tamanhos de grãos foram medidos com a utilização do software UMIAS de forma a possibilitar a determinação de distribuições estatísticas com quinhentas medidas para cada condição de tratamento. As amostras foram novamente preparadas e então atacadas com Nital 2%, sendo possível avaliar a influência do tamanho de grão austenítico sobre a morfologia da martensita. Pôde-se observar que, para o aço ABNT1045, a influência da temperatura de austenitização sobre o tamanho de grão austenítico é muito evidente e mais significativa do que a do tempo. Os valores de tamanho de grão se mostraram exponencialmente dependentes da temperatura, de forma que quanto maior o tamanho de grão austenítico, mais grosseira é a estrutura martensítica e menor é a dureza do material após a têmpera em água.

Aug 7, 2018

By R. J. Pine

Procedures are described for the application of risk analysis or probabilistic methods to mining geomechanics. The methods are widely applicable to existing mine design models. Detailed examples are given of plane slope failure and of pillar design based on displacement-discontinuity stress modelling and empirical strength assessment. The modelling techniques assessed are the Latin hypercube sampling method, incorporated in a spreadsheet environment, and the general point estimate method (GPEM), programmed in TurboBasic. An example GPEM program listing is included. Both methods are very convenient to use. Probabilistic acceptance criteria for slope stability after Priest and Brown are examined and alternatives are proposed where output distributions of factor of safety are approximately normal or lognormal and output distributions of safety margin are normal. The reliability index is included as a useful measure of variability with proposed acceptance criteria.

Jan 12, 1992

By Donald W. Scott

Chemical thermodynamic properties for the ideal gas state from 0 to 1500 K are tabulated for all of the alkane hydrocarbons through C10. These properties are based on correlations of the extant data for the entropy, vapor heat capacity, and enthalpy of formation of individual alkanes and the equilibrium constants of alkane isomerization reactions.

Jan 1, 1974

This report is a compilation of all information obtained in accordance with the requirements of contracts SO122076 and H0232056. A series of eight coal mines were visited to determine their communications usage and requirements. Presently available equipment was surveyed and evaluated to determine its applicability to the needs of the mines. The equipment studied includes that made by the following companies : Anaconda Telecommunications Division Andrew Antenna Bendix Communications Division Collins Radio Group of Rockwell International Executone Communication and Sound Systems Gau-tronics Mine Safety Appliances Company Motorola Communications and Electronics, Inc National Mine Service Company Plessey Communications Systems Corp Pye Electronics Limited Reach Electronics Set Com Corporation Sonex Incorporated Mine visits and in-depth interviews were made alt the following sites: Robena No. 4, Pennsylvania Greenwich Colliery Mines, Pennsylvania Somerset Coal Mine, Colorado Keystone No. 1, West Virginia Harris Mine No. 1, West Virginia Baldwin Underground No. 1 Mine, Illinois Lovilia No. 4 Coal Mine, Iowa Orient No. 3 Coal Mine, Illinois

Nov 15, 1974