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By J. Dienenthal

Automatic Charging and Stoking Machines for use at ferroalloy furnaces are in operation for more than 20years. Dango & Dienenthal Maschinenbau GmbH (short: DDS) has developed several machine generations. Today advanced solutions help to achieve better charging and stoking results to minimize cost and to improve the working environment around the furnaces. Three different alternatives can be considered: Rail-mounted solution The machine(s) travel(s) on an overhead monorail to one or several furnaces and is locked in the desired working position from where charging and stoking is performed. Mobile solution This machine travels on the charging platform and is also locked at the respective working position to perform charging and stoking. Automation of a standard mobile charging and stoking machine A standard charging and stoking machine can be adapted for automation. A reliable navigation system is included. Charging and stoking is performed with the moving machine. Advantage versus other solutions: considerable lower investment cost and possibility to upgrade the mobile charging and stoking machine for later automation. Overall, automatic charging and stoking can save up to 10 per cent of the specific smelting energy. A better and more consistent furnace operation can be achieved. Different programs are used to cope with different furnace conditions and changing raw materials. All machine movements can be recorded and correlated to other furnace parameters. Working environment on the charging platform is greatly improved.

Jan 1, 2007

By M. E. Poad, J. K. Whyatt, T. J. Williams

Researchers at the U.S. Bureau of Mimes monitored rock mass response to mining of an experimental underhand longwall stope in Hecla Mining Co.'s Lucky Friday Mine, Mullan, ID. This stope design, the Lucky Friday underhand longwall (LFUL), was proposed as a means of controlling rock bursting while also allowing increased mechanization of mining operations. Instruments were specifically manufactured to monitor three geomechanical factors (backfill performance, ramp stability, and rock mass response) that directly affect the success of stope design. Despite considerable difficulties with instrument installation and survival in the harsh mine environment, especially within the stope fill, sufficient information was collected to suggest that the LFUL method was successful in achieving project goals. This conclusion, in addition to favorable economic and operational evidence, led the mine to adopt the method throughout the mine. Indeed, this study and mining experience suggest that underhand longwall mining could be considered a feasible mining method for rock-burst-prone ground throughout the Coeur d'Alene District. Further Reports of Investigations (RI) in this series present in-depth analyses of the effects of backfill on rock bursting and calibration of a stope numerical model.

Jan 1, 1992

By Iara Patricia Vieira de Oliveira

O coque desempenha três principais funções no Alto-Forno sendo elas: física, térmica e química, em se tratando do papel físico, a função estrutural é de primordial importância, pois não pode ser assumida por outro combustível, com isto as indústrias avaliam a resistência mecânica a frio para garantir uma marcha estável no reator, porém os ensaios padronizados não são suficientes para avaliar a resistência do coque. Neste contexto este trabalho desenvolveu uma metodologia para avaliar de forma individual a resistência mecânica a compressão do coque nas granulometrias típicas do coque metalúrgico e como os principais defeitos, poros e trincas governam a resistência do material. Foram realizados testes de compressão, análise de microestrutura, microtextura, inspeção visual de trincas, MEV. Os resultados das análises realizadas no coque mostraram que a tensão média de ruptura aumenta com o aumento da granulometria.

Oct 30, 2017

By K. A. Lewandowski

Agglomeration techniques are widely used by industry to form fine particles into larger masses that are easier to handle and process. One area where agglomeration is potentially useful is in heap leaching operations. With-out agglomeration, fine particles travel through the heap, clogging the spaces between the larger particles and resulting in poor leach solution flow. Poor flow of leach solution will result in long leach rates and/or decreased metal recovery. Agglomeration immobilizes the fine particles and therefore improves heap permeability to fluid flow. Additional additives (binders) are needed to prevent agglomerates from breaking up as leaching solution percolates through the heap. Type II Portland cement and lime are two well-known binders used in gold and silver leaching, but these are limited to alkaline leaching environments. Various other products have been tested as binders, including polymers. This paper summarizes the benefits of agglomeration in heap leaching and the results obtained from the testing of several different agglomeration binders in heap leaching operations.

Jan 1, 2009

By I. Mihajlovic

This paper investigates a potential method for arsenic removal from copper concentrates using hypochlorite leaching. The problems concerning pyrometallurgical processing of copper concentrates with high arsenic contents are discussed. A possible solution to the problem by leaching of natural enargite crystals with sodium hypochlorite under alkaline oxidizing conditions, with enargite converted into crystalline CuO and the soluble arsenic forming AsO43-, was experimentally investigated and results are presented. Kinetic parameters were calculated for enargite leaching, using a model-free approach. Advanced isoconversional methods were used to investigate the dependence of activation energy (Ea) on reaction rate (a). Keywords Enargite, copper concentrate, isoconversional method, kinetics, activation energy.

Jan 1, 2011

By A. Adu-Acheampong

A geotechnical study was conducted to identify the cause(s) of stope instability at the Ashanti Mine (Obuasi, Ghana). As part of the investigation, laboratory testing of rock was performed and the rock mass was classified according to the Q-System (Barton et al., 1974).Numerical analyses were performed using the computer program FLAC (Itasca, 2001). The observed failure zone around the stopes was simulated using both Mohr-Coulomb and Hoek-Brown (Sheorey,1997) models. Yielding along peripheral graphite bands and tensile failure were clearly identified to be the major contributors to stope instability.

Jan 1, 2003

By C. J. Martin, M. P. Hay

"A methodology was developed in the mid-1980’s to predict plant performance from standard laboratory flotation tests. The technique is based on a simple, empirical kinetics model, and is tailored for use by the practical metallurgist.To date the performance of more than 20 flotation plants has been predicted, including copper, lead, zinc, phosphate, pyrite, graphite, cassiterite, platinum, nickel and various slags. The method has successfully been used to predict and size four flotation plants directly from bench-scale laboratory flotation testwork. All have since been commissioned, and have performed as predicted.The technique has now received broad acceptance within the South African mining industry, for example in the last year alone it has been used to drive flowsheet development for at least seven new plants. It is also being used to assist in the optimisation of existing operating plants.The methodology is described in this paper and verification of the methodology is presented using case studies of porphyry, polymetallic and PGM operations.INTRODUCTIONThere is considerable interest these days in the use of modelling to simulate flotation circuits, for process design and plant optimisation purposes. Although these models are proving to be useful tools for plant design and optimisation, their complexity can make them cumbersome – expensive to use and difficult for metallurgists to visualise and mentally absorb, without a background in each specific technique. In “SUPASIM” no attempt is made to measure flotation fundamentals, rather to use empirical relationships between laboratory flotation kinetics and plant performance – relationships that hold up well to validation exercises as will be demonstrated later in this paper. Although not designed to be as comprehensive as other models, “SUPASIM” is easily understood by the operating metallurgist and can be quickly and easily applied."

Jan 1, 2004

By P. Choquet, F. Miller

"The development and testing of a simple low-cost gauge for measurement of tension in a cable bolt grouted in a borehole are presented. Its principle is based on a resistance wire which is wound on a 70 cm length into the spiral grooves of the wire strand cable bolt. Readings are then taken by a robust automatic data logger with a several day autonomy or by a portable readout. In order to have a complete profile of tension along the cable bolt, a number of tension gauges can be installed along its length.This paper provides a description of the development and laboratory calibration of the tension gauge and addresses the two modes of loading for a cable bolt in a rock mass, namely pure tension and shearing at a joint location.In the second part of the paper, four field tests in underground and open pit mines are reported. The first test was used to substantially modify both the gauge and the readout unit principles while the other tests which are still on-going show a very satisfactory behaviour of the modified version of the tension gauge. IntroductionCable-bolting is often used as ground support in Canadian mines for a variety of applications. In underground mines, cable bolts can be installed vertically at the back of cut and fill stopes or in an inclined fashion in the walls of large open stopes. Alternatively, cable bolts at Mines Gaspe (Noranda Inc.) are used in a fan-shaped pattern from a drill drift to stabilize the inclined roof in 25 m wide open stapes. This new application oriented our research efforts toward the design of a novel instrumentation to monitor the efficiency of most commonly used 5/8-inch cable bolts."

Jan 1, 1988

By R. F. Shurtz

The problem of estimating the precision of systematic samples from a mineral deposit is attacked by interpolating the quality, or other attribute measured, by using Fourier approximation. Such approximation using trigonometric functions yields a particularly simple expression for the variance of the mean value of the attribute sampled. The increasing volume of publication in which the science of statistics has been applied to the problem of predicting the quality of an ore deposit from sets of samples taken from it might lead one to believe that engineering judgment can be replaced by statistics. There is, in fact, an implicit application of the principle of indifference or of "no advance knowledge" which has been discredited in modern statistical theory and practice. These pages will show that it is not always advantageous, efficient, or safe to apply this principle. This problem will be dealt with by using series of orthonormal functions to describe the distribution of the quality of ore in space as contrasted with the more commonly used distribution of quality as a frequency function. Mining engineers are rarely well acquainted with the use of such series or of the functions comprising them. These uses are commonplace in the fields of communication and information theory and it is not surprising that applications taken from these fields should be found appropriate for the analysis of the information contained in a set of samples from an ore deposit. It is hoped that presentation of the following basic, but incomplete, results will generate wider interest in this method and a fuller development of it as well as of the necessary computational techniques. FUNDAMENTAL PREMISES Random variables in the strictest sense are not very common in mine sampling. The sets of samples are almost always taken systematically and are, hence, not subject to all the laws governing random events. Therefore, unless there is indeed random experimental error in the determinations of quality, the treatment of systematic samples of n members as though they were random samples of n members often leads to calculation of confidence limits for the mean quality which are larger than they should be with the result that unnecessary additional sampling is done. The reason for this will emerge in the following discussion leading to Eq. 24 and its generalization. In order to inquire into such questions on a rigorous basis and at the same time avoid arithmetic complications that would obscure the concepts involved, a one dimensional distribution of quality will be assumed. The quality, Q, in suitable units is expressed as a function of the distance, x, along some straight traverse of the deposit. Such a function

Jan 1, 1967

By M. Visser

Keywords: Pyrometallurgy, furnace, ferrochrome, Samancor, ferrochrome process Samancor Chrome has been, and continues to be, a major player in ferrochromium production. The company has a proud history and possesses benchmark technology and operations. Currently five business units are operating: two sets of mines and three smelter plants. Samancor Chrome produces around one million tons of charge chrome annually. Chrome ore, intermediate-carbon ferrochrome, and low-carbon ferrochrome, form part of the portfolio. Electrode paste is also manufactured through a joint venture with Highveld Steel and Vanadium. Samancor Chrome has a balanced approach towards operational strategy, and has entered into a number of joint venture partnerships. Through its access to quality raw materials, knowledge, and experience of various production technologies, and its strategic abilities, Samancor Chrome is well positioned to reap the benefits from opportunities in the current and future industry context.

Jan 1, 2006

By David R. Beadman

This paper discusses how modern techniques of design and construction were used to create the deep stations for the Copenhagen Metro. The deep stations are located in small squares within the city adjacent to many old and sensitive buildings. The architectural design provides a large open atrium to allow natural light to reach the column free platforms to give the citizens of Copenhagen a feeling of safety and security and encourage them to use the Metro. The design and construction contract was undertaken using the relatively new and untried Eurocodes. The resulting stations set new standards of design for underground metros and have pushed forward the frontiers of what is appropriate construction practice to protect the existing and enhance the future environment.

Jan 1, 2000

By B. Hilscher, P. Nayak, N. Yoon

"The mining industry is currently facing challenges with declining feed grades and is struggling to find solutions to improve the project’s economic value. By means of pre-concentration, ore sorting aims to separate the barren material from the valuable ore to reduce energy consumption and tailings generation, while increasing the feed grade, concentrate grade, mill recovery, and revenue. In addition, ore sorting allows the modification of deposit geometallurgy in order to allow the creation of an optimal mill feed.This paper evaluates the applicability and challenges of ore sorting by utilizing the results from four different mines, and reviews them in detail. The mines include two underground and two open pit mines that are base metal and precioius metal operations. In order to understand the applicability of ore sorting in these operations, initial rock-by-rock test results and different types of assays (atomic adsorption [AA], inductively coupled plasma [ICP], and fire assay) are utilized. Using the assay results, the grade recovery curves for ore sorting are generated and they are further improved by using and developing an ore sorting algorithm, which is discussed in this paper. The application and evaluation of ore sorting in greenfield and brownfield properties will also be discussed.The state of the art ore sorting technologies for both rock-by-rock and bulk sorting are reviewed in this paper. The future technologies on the horizon, including different combinations of sensors, are explained. The sorting technologies include, X-ray transmission (XRT), X-ray fluorescence (XRF), colour, infrared, electromagnetic, and laser induced breakdown spectroscopy (LIBS).IntroductionOre sorting is a sensor-based sorting technique introduced between the excavation stage and processing stage, where the unwanted waste is diverted to the waste dump and only the ore is sent to the mill for further processing. As a result, the quality of the material entering the mill is improved and the dilution of the ore is reduced. In greenfield projects, sensor-based ore sorting provides an opportunity to reduce the capital cost of the project and increase the return on investment (ROI). With most operations currently facing the challenge of finding a high grade deposit, having a sorting unit provides several advantages while keeping the cost at minimum."

Jan 1, 2017

This paper reports on recent field observations on the performance of support systems under different corrosion environments in Canadian underground mines. Phenomenological data are used to gain a better understanding of the main causes of corrosion in underground metal mines. Preliminary field data collected from five metal mines have been complemented by atmospheric and water sample analysis as well as fractography and metallographic studies. This has identified dominant factors that control the corrosion of support systems. The data are analysed in order to develop a support strategy for mines operating in corrosion environments.

Jan 1, 2008

By K. C. Viveros, R. R. Ambriz, C. García, F. De Villèle, A. Talha, D. Jaramillo

Cold hole expansion on base metal, weld metal and heat affected zone of 6061-T6 aluminum alloy welds was simulated by means of finite element method. Three dimensional compact test models with a previous fatigue crack length with a relation of ??= a/W = 0.3, were used to analyze the hole expansion process. Considering the local mechanical properties for each zone of the welded joint, the optimal expansion degree (1.64 to 2.46 %) was determined. The residual stress field, through thickness, after the expansion process in all welding zones, were correlated with the crack opening displacement obtained by finite element analysis. It was observed, that compressive residual stress fields for a post-expansion, in different crack lengths, provided a crack closure mechanism for base metal, weld metal and heat affected zone. Contrary, the crack remained open when residual stresses are positive. The results are given as tangential stresses versus distance from the edge of the cold expansion and crack opening displacement as a function of applied load.

Jan 1, 2014

By Harry: Lobb Verakis

Mining operations have made tremendous strides in improving the safety of blasting as shown by the significant and continual decrease in fatalities and serious injuries. Advances in blasting technology and blasting practices have played a significant role in reducing fatalities and injuries. However, even with the decline of fatalities and injuries blast area security continues to be by far the leading factor in blasting accidents. Even though there continues to be an increase in the use of industrial explosives and blasting agents in the U.S.A., the decline in fatalities and injuries from blasting accidents has persisted.

Jan 1, 2010

By A. J. Davidson

A Cu-conducting solid electrolyte was used to develop the sensor. Instead of measuring the potential across the electrolyte from the reference material to the Cu-containing phase, a potential was applied and the stable current measured. This gave reasonable readings for copper-tin alloys, which agreed with the theoretical calculations, but was less satisfactory in the case of mattes because the surface area of electrolyte presented to the matte phase varied from sensor to sensor. To overcome this problem the potential was applied, the current was measured and then reversed and remeasured and the ratio of the currents was calculated. The current ratio is shown to be independent of the resistance of the electrolyte and the surface area of the electrolyte offered to the melt, but strongly dependent on the activity of the copper

Jun 21, 1905

By Graham Davey

"Ultrafine grinding of minerals has been in wide spread use in the industrial mineral field for over 30 years. Within the last 10 years the metalliferous industry has shown interest in the ability to produce ultrafine particles, as chemical, physio-chemical and physical separation processes have advanced to be able to treat ultrafine metalliferous particles. Also as the primary mineral deposits are depleted, new more difficult deposits must be mined. Existing operations are also looking to maximize economic return from existing deposits, requiring new thinking and technologies.The recent development of industrially proven and cost efficient technologies for ultrafine grinding has opened up another processing option for the treatment of finegrained metalliferous and refractory gold ores. The current commercial designs are variations of stirred mills used in the industrial minerals sector for the past 30 years. For the purposes of this paper ultrafine grinding is considered to be P80 of less than 15 microns.Attrition milling to fine grind sizes presents some challenging issues relating to scale-up including the dearth of information on the quantitative impact of feed and operating conditions, as well as the precise and accurate measurement of particle size distributions. Two examples from recent installations will be analyzed including Thalanga Copper and Century Zinc Mines. Both have diverse grind size targets for the SMD, yet both have realized significant metallurgical gains."

Jan 1, 2002

By Daryl E. Radcliffe, Raymond M. Stateham

The Bureau of Mines, under a Cooperative Agreement with the Bear Coal Company, Somerset, Colorado, conducted a large scale evaluation of the effect of time lapse on roof stability. Time lapse in this study is the interval between exposure and permanent support of the mine roof. The study indicates that time lapse is not a critical factor in roof stability provided permanent support is installed before catastrophic failure begins. Concurrently with the time lapse study, investigations were made of stress distribution around resin-grouted bolts, the regional stress field, and anomalous geologic conditions. The behavior of the resin-grouted bolts, at least in the Bear mine, appears to fit the Coulomb-Navier Theory. Geologic conditions are primary factors in trends of roof stability that extend across the mine.

Jan 1, 1982

By G. W. Jones

As a part of its general safety program the Bureau of Mines has investigated various means useful for the elimination or mitigation of the explosion hazards in connection with combustible gases incident to the mining industry. Information has been obtained relative to the explosibility of numerous simple and complex gaseous combustible atmospheres. Although experiments along this line have pertained largely to combustible gases in the mining and allied industry, considerable information has been obtained relative to the explosive hazards of combustible gases and vapors used as anesthetics.

Jan 1, 1939

By G. W. Jones

As a part of its general safety program the Bureau of Mines has investigated various means useful for the elimination or mitigation of the explosion hazards in connection with combustible gases incident to the mining industry. Information has been obtained relative to the explosibility of numerous simple and complex gaseous combustible atmospheres. Although experiments along this line have pertained largely to combustible gases in the mining and allied industry, considerable information has been obtained relative to the explosive hazards of combustible gases and vapors used as anesthetics.

Jan 1, 1939