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By Neal Schwartz, Robert De Saro, Richard Rosenthal, Ed Kear

"A Stack Melter has been installed and is currently operating at Lexington Die Casting. The Stack Melter consists of a 1 meter (3 foot) diameter refractory tube, 2 meters (7 feet) high. Specification ingots are continuously fed to the top of the melter and piled to nearly the top. A burner fires through the scrap which melts the lower portion and preheats the upper portion. As the lower portion is melted, it is drawn out and the upper preheated scrap falls to a lower level where it in tum melts. The molten metal is fed to one of two holding furnaces for eventual delivery to a casting machine.The Stack Melter's energy use is approximately 2900 joules/g (1,250 Btu/lbm), resulting in an overall energy savings of about 58%. This energy savings is brought about primarily because the flue gases preheat the scrap and the flue gas temperature is dropped to well under 528°C (1000°F)."

Jan 1, 2000

By B. Chambers, M. Yunovich

"Corrosion monitoring is commonly used in a variety of industries as a means of effective corrosion control programs to extend the life of the asset and ensure safe operation of the facilities. The majority of the monitoring tools have limitations and tradeoffs – e.g., sacrificing the longevity of the probe for higher measurement resolution. Linear polarization resistance (LPR) probes have the advantage of providing the operator with accurate, real-time corrosion rate data; however, the probes can only be deployed in conditions where the measured environment possesses certain minimal conductivity. In many instances, utilization of LPR probes in conditions with intermittent wetting (for example, conditions where the temperature fluctuates above and below the dew point) presents a challenge. To address this limitation, a special-design cooled corrosion probe has been developed, commercialized and integrated into the distributed control system in the plants. In addition to high-accuracy measurement of corrosion rates, the probe allows for monitoring of pitting corrosion. The most innovative feature of the probe is the cooling circuit, which brings the temperature of the sensors below the dew point, forcing precipitation of moisture and thus permitting corrosion measurements. Additionally, the probe was found to be well-suited for monitoring corrosion in crude distillation unit (CDU) overhead space, where condensation of hydrochloric acid may take place at relatively high temperatures, which would require relatively moderate amount of cooling to be imparted to the probe sensors. This paper presents laboratory-based data from a test simulating CDU refinery environment. A case study is presented to demonstrate how the cooling probe can be effectively used in the plants for corrosion monitoring.INTRODUCTIONConventional corrosion-monitoring techniques such as weight-loss coupons to assess corrosion damage are commonly used in plants1. However, the use of coupons is not only labor-intensive, but also does not deliver real-time corrosion data, thus effectively serving as a “backwards-looking” monitoring tool. Linear polarization resistance (LPR) probes have the advantage of providing the operator with accurate, real-time corrosion rate data; however, the probes can only be deployed in conditions where the measured environment possesses certain minimal conductivity."

Jan 1, 2012

By Abid O. Adekunte

The design, construction and monitoring of the deep excavation support for the basement of a large-scale commercial development in Cavan, Ireland is presented. Excavation area was adjacent to existing structures and retained height H varied between 4.0m ? 11.0m. In areas where excavation depth H < 5.0m, wall was designed as cantilevered section. However in sections where 5.0m = H = 11m, additional wall supports were required for serviceability reasons. Traditionally, designers often provide additional wall support through the use of tie-back ground anchors, raking props and braces. On the current project, the main contractor was not in support of the use of temporary props so as to maximise working space, while owners of adjacent properties disapproved the use of tie-backs. The limited set-back between the wall line and site boundary also contributed to the complexity of the project. A rare alternative solution has been adopted. This novel approach involved buttressing the wall with steeply raking bored tension piles at regular intervals along the wall. Comparison of the monitored deflections in the cantilevered sections with those recorded at sections where tension piles were used shows the novel solution to be safe and quite effective. This approach is also considered to be more economical when compared with ground anchorage and propping.

Jan 1, 2008

By T Clemens, D Trumm

Adopting environmentally acceptable practices in New Zealand is a crucial requirement for mineral wealth development. Recent planned expansions in the coal industry have increasingly placed mining in the media spotlight. A lack of appropriate national environmental guidelines has resulted in inconsistent responses and assessments of current and prospective mine sites. Such inconsistencies have lead to delays in decisions on developing economic mineral deposits that may have only minor short-term impacts, and have also allowed unacceptable environmental management practices to continue elsewhere. &nbsp; A research collaboration between CRL Energy, Landcare Research, University of Canterbury and University of Otago aims to provide regulator groups and the mining industry with a unified approach to the requirements of the Resource Management Act 1991, which is the legislation that predominantly drives the nationÆs environmental policies and guidelines. The tangible outcome of this research programme will be guidelines for an integrated decision-making framework based upon robust multidisciplinary science. The result of this unified process will facilitate the development of viable mineral deposits and prevent excessive environmental impacts. &nbsp; The framework will be derived from a synthesis of four objectives. Objective 1 identifies potential water quality impact. This objective is based on a targeted geochemical study of the lithology and waterways of the West Coast and Southland. Objective 2 categorises the degree of impacts on the ecology of receiving aquatic ecosystems and determines the processes that drive aquatic ecosystem recovery. Objective 3 identifies best strategies to sufficiently manage impacted ecosystems, and to prevent future unacceptable impacts. Objective 4 combines the findings of Objectives 1 - 3 into a standard decision-making framework. The development of this framework development will include wide consultation with representatives of the mining industry and regulator groups. It is anticipated that this multidisciplinary approach will provide a robust and coherent, standardised system that will assist in achieving industry and environmental targets.

Jan 1, 2004

Atlas Copco is one of the worldÆs leading providers of industrial productivity solutions (Atlas Copco, 2009). Furthermore, the company spans 160 markets and held 34 000 employees at the end of 2008. The company is organised under three ætechniquesÆ whereby the Construction and Mining TechniqueÆs business division is located within +rebro, Sweden. This paper is aimed at briefly facilitating information on how the company and more specifically, the Construction and Mining Technique is run. Also, by sharing my experiences, this paper is intended to encourage and motivate students currently studying for a degree relevant to the minerals industry, to apply for this extremely beneficial scholarship. Through a number of presentations relating to the various divisions, products and aftermarket services of the company, I came to realise that Atlas Copco extends beyond simply selling equipment suitable for the mining and civil industries. This tour through Sweden also contained highlights of visiting the Underground Rock Excavation factory, Surface Drilling Equipment factory and Secoroc divisions. I was also fortunate enough to participate in a tour of the LKAB mine in Kiruna. In addition, time was allocated to less industry related activities, and I was able to go dog sledging, sip vodka cocktails out of ice glasses at the Ice Hotel and enjoy traditional Swedish foods of moose and reindeer. Most important and memorable to me; however, was the ability for employees of Atlas Copco to speak of the company and their products with such passion and enthusiasm, which truly made this a motivational and unforgettable experience.

Jan 1, 2009

By Michael R. Brown

A facilities success or failure of doing well during a regulatory inspection is typically measured by the number and type of citations that result, and financial liability resulting from those citations. The success of a facility during an inspection depends on several factors including, the preparation prior to an inspection, behavior and activities during and inspection, and finally, action taken following the inspection. This paper contains suggestions for improving inspection results and establishing an attitude of compliance at manufacturing and mining facilities.

May 1, 2002

By F. Bahnemann

IN discussing the problem of abnormal magnetic polarization, C. A. Heiland1? emphasized the unfortunate fact that our knowledge of the geological and physical conditions relating to such occurrences is very limited and that a more detailed insight into their physical causes would be extremely valuable for interpreting measured anomalies. He also pointed out that to arrive at quantitative physical formulas that would express the conditions that cause abnormal polarization many more occurrences of the kind would have to be recorded. The first part of this paper is a contribution to such descriptions.

Jan 1, 1935

Portfolio management tends to separate the functions of Asset Allocation and Stock Selection, so the person responsible for reviewing an expert&apos;s report on a company would typically be choosing between companies rather than between a company and cash or bonds. How these choices are made depends on the investment time horizon, philosophy and style. Two styles, momentum investing and value investing are contrasted and the role of valuation methods within the framework of each style is evaluated. Finally, pricing is distinguished from valuation.

Jan 1, 1994

By Meakins R. L, Talaska A, Kenny D, Haycraft J. A, Dickson B. L

A vehicle-mounted radiation detector interfaced to a microprocessor called PRAM (programmable radioactive analyser mobile) has been developed to provide grade control for selective mining of a soft rock uranium ore. The grade of ore over which the vehicle passes is determined and indicated by several coloured lights to a pegman who walks behind the vehicle. Coloured pegs are then laid out to mark the uranium grade ranges on the floor of the mine pit. Comparison between grade ranges determined by the PRAM and by prior drilling and downhole logging at the Yeelirrie deposit, Western Australia indicate good agreement. Use of the PRAM decreases the cost, manpower and time required to grade extensive areas of a mine pit floor.

Jan 1, 1982

A portable electronic instrument was developed which will measure change of longitudinal wave velocity with change of uniaxial stress in rock columns. The instrument is a solid-state device powered by nickel-cadmium batteries. It uses a probe of two piezo-electric crystals spaced inches apart to send and receive a pulse through a stressed rock. A one-inch cathode ray oscilloscope visually displays the longitudinal wave. A reference chart is used to find the stress. Laboratory results have indicated that the average stress on a sandstone column can be found to within 35 psi. The feasibility of using this instrument to determine stresses in mine pillars is to be studied. The instrument may be used to investigate physical properties of rock.

Jan 1, 1970

By W. W. Vaughn

In the technique described and evaluated, detection of mercury is based on the principle of atomic absorption. An analog signal, produced when mercury vapor absorbs ultraviolet light, is converted to digital form and calibrated to mercury concentration. Interferences are eliminated by selectively trapping the mercury on gold. The lower limit of sensitivity, using a 1-gram sample, is 5 parts per billion. A model of the instrument mounted in a station wagon has been tested successfully in the field.

Jan 1, 1964

By John F. Abel

Convergence measurement across the 17.4 m (57ft) high shaft station/loading pocket at Mt. Taylor provided continuing verification of stability and safety. Three levels of instrumentation, consisting of three lines each, were installed and monitored. The instrumentation showed that the flexible lining restrained the adjacent rock. The flexible lining consisted of pea gravel with neat cement between rock and liner plate, wooden crush blocks between liner plate and steel ring beams. The loading pocket is elliptical, 11.6 by 9.6 m (38 by 31 1/2 ft) I.D. The crush blocks were designed to allow 15 cm (6 in.) of convergence. Maximum predicted convergence was 7.0 cm (2 3/4 in.) and 5.7 cm (2 1/4 in.) was measured. Convergence measurements also demonstrated decreasing deformation with respect to elapsed time and distance from the measurement station to the temporary bottom of the shaft excavation.

Jan 1, 1984

By M. Kane, B. Bissonnette, D. Hodouin

"A laboratory cell has been designed for a careful investigation of gold ore cyanidation using mathematical modelling of the process kinetics. The cell is a stirred vessel with continuous monitoring and control of pH, oxygen and free cyanide contents. Samples are automatically extracted for gold analysis. The instruments are connected to a microcomputer which records all the measured variables and calculates the reagent consumption (air or oxygen, cyanide, lime). For cyanide control a sample is automatically extracted and filtered and the solution analyzed, using a specific electrode, by a flow injection technique. The rate of gold dissolution is modelled using a kinetic model the parameters of which are calculated by a non linear least-squares technique. The parameters of an empirical model of reagent consumption are also estimated. The resulting model is used in a simulator for gold cyanidation plant design, tuning and control.INTRODUCTIONThe leaching of gold ores in a cyanide solution is the usual method for gold extraction from raw ores. This process requires long reaction times and leads to very significant consumption of cyanide. The optimization of the cyanidation plant operation is a very important aspect of gold ore processing for increasing gold recovery and decreasing operating costs. The key parameters to the improvement of gold extraction are the selection of an efficient solution chemistry, the design of the size and the arrangement of the equipment and the correct tuning of the operating variables. Automatic control strategies can then be applied to maintain industrial operations at their optimum setpoints.Two approaches can be used for optimizing design and control of cyanidation circuits, either empirical trials for improving process performances or mathematical modelling of the process kinetics for subsequent analysis, simulation and optimization. The advantages of the second approach, which is used in this study, is that it gives a systematic pattern to interpret data and reliable tools, in as much as the models are good, to improve operation performances. In order to determine the structure and the coefficients of cyanidation models, well controlled measurement and calibration procedures must be used. The purpose of the paper is to present an equipment and a test procedure for modelling the kinetics of gold ore cyanidation."

Jan 1, 1990

By J Zhou

This paper discusses the implementation of a mixed integer linear programming model for a coal preparation plant. The plant considered consists of primary and secondary heavy media cyclones, hydrocyclones for intermediate fines and froth flotation for the very fine material. The model is designed to optimise the plant settings and product flows to maximise revenues for a given specification for two product outputs. The model can deal with bonus/penalty aspects of the product pricing for products that exceed or fail to meet specification. We report on a model with two separate coal feeds with parallel circuits for the oversize, intermediate and fines streams. The genesis of this model is more than 30 years old but recent improvements in mixed integer programming solvers make a full mixed integer formulation practical. The original model began as an enumeration of cut points with arbitrary rules for product allocation. The product allocation was improved in a linear programming formulation by Gunn (1982) and Sarker (1991 and 1995). Current mixed integer programming capabilities make it possible to replace the enumeration aspects and solve directly as a mixed integer programming problem. The current implementation uses a general purpose modelling language to formulate the model. Open source and commercial mixed integer programming solvers are compared

Sep 26, 2011

The Department of Mineral Resources is the lead agency in mine site environment management and control inNew South Wales. The Department introduced a Mining, Rehabilitation and Environmental Management Plan (MREMP) process several years ago in order to integrate the activities of other government agencies who may have a material interest at the mine site. The MREMP process has resulted in a spirit of trust and co-operation between agencies and between agencies and mining companies. The spirit of co-operation has been reflected in greater public confidence that mining is environmentally responsible. &nbsp;

Jan 1, 1995

The Department of Mineral Resources is the lead agency in mine site environment management and control in New South Wales. The Department introduced a Mining, Rehabilitation and Environmental Management Plan (MREMP) process several years ago in order to integrate the activities of other government agencies who may have a material interest at the mine site. The MREMP process has resulted in a spirit of trust and co-operation between agencies and between agencies and mining companies. The spirit of co-operation has been reflected in greater public confidence that mining is environmentally responsible.

Jan 1, 1995

By G J. Wilkie, P A. Revell

The R&D landscape for ore pre-concentration technologies within mining is characterised by the development of individual technologies and point solutions. This presents METS and mining companies with the combined challenge of understanding how to apply pre-concentration technologies to create maximum value, and how to sustainably integrate the technologies into their businesses to maintain the value. The paper will consider the requirements of an integrated pre-concentration system and presents a portfolio of R&D projects that have co-developed and integrated a suite of new precencentration technologies and methodologies across the mining value chain. Focus areas include in-situ orebody characterisation, blast design, real time cross belt mineral sensing, and consideration of how much data needs to be acquired in order to make value based decisions between ore pre-concentration options. An ore pre-concentration workflow is presented to demonstrate how additional optimisation opportunities are enabled both by moving decision points further upstream in the value chain, and by integrating the concepts of pre-concentration into the design of mineral processing equipment. Additionally, several research projects examine the non-technical factors that present barriers to uptake of new technologies within mining companies. Organisational culture, risk management and socio-political factors are discussed and a set of management tools are presented that allow organisations to self-assess their readiness for new technology uptake, along with process models to assist management with identifying and navigating the ecosystem of stakeholders that are decision makers in the use of pre-concentration technologies.

Nov 10, 2020

By N. F. Mashinini

Optimization of current control systems, proper maintenance and efficient training of personnel are recommendations made to control the amount of dust that underground employees are exposed to on a daily basis in the coal mining industry. This dissertation forms as part of Sasol Mining?s commitment to protect the health and safety of their employees by suppressing and controlling dust at their mines. This study aims to understand the relationship among mining processes, exposure to dust and dust suppression control measures. The research phase of the project was done at the Sasol Mining Secunda complex where underground visits were undertaken to investigate current control systems and also new systems that are being implemented by Sasol Mining. This work was important because it helped determine the sources of dust underground and also to identify the shortcomings of current control systems and to test the efficiencies of the new systems implemented at Sasol Mining. The most important result of the research work was the identification of which underground operators were exposed the most to dust as this assisted in designing a dust suppression system for the areas where these operators worked. The main conclusions of this study are that the current control systems are sufficient for controlling dust and ensuring dust compliance if they are used efficiently and maintained properly.

Jan 1, 2008

By L. Linzer, J. Oelofse, T. Rangasamy

Extraction of isolated blocks of ground with elevated levels of stress and/or seismicity is a common occurrence in South African gold mines. Isolated blocks of ground that are divorced from the main orebody and are bound by complex, dip and strike parallel, non-persistent geological structures dominate the Klerksdorp gold fields. No quantifiable methods exist to assess the risk associated with mining these and other classes of remnants. A case history, from a gold mine that planned to extract three remnant blocks hosted in a large complex fault system, is used to illustrate the decision making process based on a combination of underground observations, numerical and seismic techniques. Simple risk estimation matrices were developed and used to estimate remnant-mining risk and finally to quantify the decision on which of the three remnant blocks could be extracted at the lowest possible geo-mechanical risk. Il est courant dans les mines aurifères sud-africaines d’extraire des blocs de terrain isolés qui possèdent des niveaux élevés de contraintes et/ou sismicité. Les régions aurifères de Klerksdorp sont dominées par des blocs de terrain isolés qui sont séparés du gisement principal et qui sont retenus par des structures géologiques non continues, à parallèle de pendage et direction, et complexes. Il n’existe pas de méthodes quantifiables pour évaluer le risque associé à l’extraction de ce genre et autres genres de résidus. Une observation de cas, celle d’une mine d’or qui avait l’intention d’extraire trois blocs de résidus qui se trouvaient dans un grand système complexe de faille, est utilisée pour illustrer le processus décisionnel basé sur une combinaison d’observations souterraines, et de techniques numériques et sismiques. Des matrices simples d’estimation de risque furent développées et utilisées pour estimer le risque lié à l’extraction des résidus et finalement pour quantifier la décision sur lequel des trois blocs de résidus pouvait être exploité au moindre risque géo-mécanique. Die Extraktion isolierter Gesteinsblöcke mit erhöhtem Spannugsniveau oder Seismizität ist in südafrikanischen Goldminen üblich. Isolierte Gesteinsblöcke, die von der Haupterzader getrennt und durch komplexe, parallele abfallende und horizontale nicht persistent geologische Strukturen gebunden sind, beherrschen das Klerksdorp Goldfeld. Es gibt keine quantifizierbare Methoden die das Risiko welches mit dem Abbau dieser und anderer Klassen verbunden ist beschreiben. Eine Fallstudie einer Goldmine, welche die Extraktion von drei in einem großem komplexen Verwerfungssystem eingelagerten Einschlußblöcken plante, wird verwendet um den Entscheidungsprozeß zu illustrieren, der auf einer Kombination von Untertag Beobachtungen und numerischen und seismischen Techniken basiert. Einfache Gefahreinschätzungsmatrizen wurden entwickelt und angewendet um das Abbaurestrisiko abzuschätzen und letztendlich die Entscheidung zu quantifizieren, welcher der drei Einschlußblöcke unter dem niedrigst möglichen geo-mechanischen Risiko extrahiert werden konnte .

Jan 1, 2003

By P. Katsabanis

Researchers in the field of blasting have been trying to develop ways of predicting fragmentation in the last few decades. The Kuznetsov equation estimates the average fragment size, XJ~, based on explosive energy and powder factors. Cunningham calculates the uniformity of a fragment size distribution using drilling accuracy, blast geometry and a rock factor A associated with a “blastability index”, which can be estimated from the jointing, density and hardness of the blasted rock mass. Knowing the mean size and the uniformity index, a Rosin-Rammler distribution equation can then be derived for calculating the fragment size distribution in a blasted muckpile. Analysis of existing data has revealed serious discrepancies between actual and calculated uniformity indices. The current integrated approach combines the Kuznetsov or similar equation and a comminution concept like the Bond Index equation to enable the estimation of both the 50% and SOoh passing sizes (X& and X& ). By substituting these two passing sizes into the Rosin-Rammler equation, the characteristic size (Xc ) and the uniformity index (n) can be obtained to allow the calculation of various fragment sizes in a given blast. The effectiveness of this new fragmentation prediction approach has been tested using sieved data from small-scale bench blasts, available in the literature. This paper will cover all tested results and a discussion on the discrepancy between measurement and prediction due to possible energy loss during blasting.

Jan 1, 2001