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By N. S. Shan

This report presents the results of a study to determine compaction criteria for coal waste embankments. The purpose of this study is to evaluate the costs and resulting effects on the engineering proper-ties of coal waste materials, utilizing different compaction methods, equipment passes, and lift thickness. Based on the results of the study, a cost efficient compaction method that will attain the desired results will be recommended to the coal mining industry. The report describes a comprehensive literature search into the compaction of coal waste materials, field compaction programs, laboratory investigations, analysis of test data as well as conclusions and recommendations for establishing the compaction criteria. The findings obtained in this investigation are intended to supply much needed information and to justify the guidelines that have been recommended.

Jan 1, 1981

By G. Luttrell

Coal preparation plants play an important role in modern society by providing high quality feeds for coal-fired utilities, industrial boilers and metallurgical coke facilities. Unfortunately, field data indicate that preparation plants are often not operated under optimum conditions, resulting in lower productivity and lost profits. In many cases, this shortcoming can be attributed to a failure by plant operators (i) to recognize the importance of correctly adjusting plant operating conditions to accommodate requirements dictated by coal sales agreements within different coal markets and (ii) to properly account for variations in product moisture with particle size across different plant circuits. This paper discusses the important influence of moisture constraints on preparation plant optimization and provides a case study to illustrate the potential gains that can be realized via proper understanding of plant moisture control.

Jan 1, 2009

By K. Sasaki

Diffusion phenomena in mine airways are important to trace gas and dust introduced into mine ventilation flows. Authors have carried out tracer gas measurements to check mine ventilation using concentration-time curves measured in mine airways, however dispersion mechanism to enhance effective diffusion have not been cleared. A numerical model using discrete tracer points dosed into tube flow has been presented to simulate their movements in consideration of turbulent velocity profile and fluctuation. Numerical simulations have been carried out to predict distributions of dosed points in tube flows with turbulent velocity profile, turbulent intensity profile and Reynolds stress. The numerical simulation results show that a combination of turbulent velocity profile and fluctuation creates extremely large dispersion of points in longitudinal direction and concentration curve with long tail was observed. This dispersion by velocity profile and fluctuation contributes large effective diffusion coefficient compared with original diffusion coefficient dominating in uniform velocity fields. Furthermore, the effect of Reynolds stress on the concentration-time curves is discussed.

Jan 1, 2009

By A. Taylor, J. Shelegey, H. Sullivan, J. Doucet

"Historically, performance at Vale’s Clarabelle Mill was measured by Mill throughput and Mill recovery. After the economic collapse in 2008, a series of reviews were performed to drive improvements in business efficiency. These identified that product quality (e.g., concentrate grade, variability in concentrate grade) had a profound impact on downstream processes and suggested that improved control of these parameters would generate the greatest value for the customer (the Copper Cliff Smelter) and the company (Vale). Consequently, a movement was initiated to transform the Mill operating philosophy to consider customer needs as paramount. Systems and strategies used to drive the transformation are described. In 2011, an unexpected furnace failure resulted in decreased capacity at the Copper Cliff Smelter. In response, a two-stage change in production strategy was developed at Clarabelle. The first stage was to modify the ore blend feeding Clarabelle so that the concentrate grade could be significantly increased with minimal impact on recovery. The second stage was a circuit modification to ensure the elevated concentrate grade could be sustained. Execution of the first stage was complete five days after the failure and the second stage was complete within 10 weeks. Steps involved in each stage are outlined and the overall benefits are presented.INTRODUCTION Clarabelle Mill is located in Copper Cliff, Ontario, Canada (approximately 350 km north of Toronto). The Mill treats copper (Cu) and nickel (Ni) sulphide ores. The primary diluents are pyrrhotite (Po) and non sulphide gangue rock (Rk). The process description of the circuits at Clarabelle is documented in the paper by Taylor, Doucet, Blanchette, Barrette & Lawson (2012) in this Proceedings and will not be repeated. The Mill treats ore containing Cu, Ni and platinum group elements (PGE’s) and produces two concentrates; a Cu concentrate and a bulk Cu/ Ni Concentrate (referred to as nickel concentrate). The Cu concentrate is sold to market while the Ni concentrate is thickened at the Mill and pumped to Vale’s smelter complex in Copper Cliff Ontario for further processing. Since commissioning in 1971, Clarabelle Mill has undergone many circuit changes to suit the changing needs and wants of our customers, both internal and external. The Mill processes ores of varying quality, based on mineralogy and size and until 2009 the Mill daily performance was primarily based on throughput. The second key performance indicator (KPI) of “good” or “bad” performance was quality of the concentrate and third; Mill metal recoveries. There were other plant level KPIs such as flotation feed grind size, slurry densities and mass flows to the separation circuit, but for the most part each day was good or bad depending on how many tons were processed through the Mill."

Jan 1, 2012

By Heikki Laurila, Sirkka-Liisa Jämsä-Jounela, Jarkko Karesvuori

"Artificial Intelligence includes excellent tools for the control and supervision of industrial processes. Several thousand industrial applications have been reported worldwide. Recently, the designers of the A1 systems have begun to hybridize the intelligent techniques, expert systems, fuzzy logic and neural networks, to enhance the capability of the A1 systems. Expert systems have proved to be ideal candidates especially for the control of mineral processes.As successful case projects, an expert system based on on-line classification of the feed type using neural data analysis is described in this paper. The essential feature of this expert system is the classification of different feed types and their distinct control strategies at the plant. In addition to the classification, the expert system has a database containing information about how to handle the determined feed type. This self-leaming database scans historical process data to suggest the best treatment for the ore type under processing. The system has been tested in the Outokumpu Finnmines Oy, Hitura mine. Other projects have been reported to be in progress.INTRODUCTIONIn the past ten years considerable researches have been done in the application of artificial intelligent methods in process industry. The technologies of fuzzy logic, neural networks and expert systems have received several thousand applications worldwide: monitoring and analysis of process operations, fault diagnosis, supervisory control, feedback control and scheduling and planning of operations. Recently, the designers of these systems have begun to hybridize these intelligent techniques to enhance the current capability of expert system. Complex signal processing, neural networks, fuzzy logic and rule-based systems are also implemented to develop new so-called smart or intelligent sensors, actuators or components. Field buses are playing a more and more important role in automation systems and in imbedded systems. The development of field buses has allowed the distribution of smart components over networks."

Jan 1, 2000

By Bernard Baum

Combined preservative/fire retardant systems were pressure impregnated into Douglas fir and Ponderosa pine samples and evaluated for decay, flammability, and mechanical properties. The objective of the evaluation was to identify cost-effective systems for use with mine timber, and to provide an information and data base from which Federal code regulations could be established. Thirty systems, based on combinations of commercially available preservatives and fire retardant impregnants and coatings, were applied to Douglas fir samples and evaluated for decay and flammability. The ten most promising systems were ap¬plied to both fir and pine and reevaluated for decay and flammability before and after water leaching. The five best systems were given a thorough laboratory evaluation using both pine and fir. Evaluations included flame spread, smoke density, toxic gases, decay, compressive strength, flammability after artificial weathering, and cost. All systems had acceptable toxic gas levels and smoke densities, but flame spread was only borderline acceptable for most of the samples tested. A trade-off analysis showed Acid Copper Chromate/Fyrprufe with Albi-107A/144 intumescent paint and Koppers NCX to be the-best systems. Recommendations are made for further large-scale testing using the two best Systems.

Jan 1, 1978

By Kenneth Trelewicz

This report describes the total effort that went into developing environmental test criteria for general mine instrumentation. The project was a two-phase effort. Phase I consisted of research and mine visits to develop an environmental profile for mine instrumentation. The profile was translated into general requirements and then into test requirements. A review of existing government and commercial specifications was performed to determine if they matched mine instrumentation test requirements. Finally, a set of environmental test procedures was developed for the testing of mine instrumentation. Phase II consisted of selecting and purchasing sample mine instrumentation and subjecting them to the previously developed tests. The purpose was twofold: (1) to evaluate the criteria developed for use as an instrumentation test document and (2) to determine the effects of the various criteria on a representative sample of both proven and newly developed instrumentation. The test criteria were then modified, based on the results of the testing, and are listed therein.

Jan 1, 1981

By P Meehan, R McAree, Z Guan

Equipment maintenance is 30 - 50 per cent of the operating costs for a typical mining company. While this is substantial, its importance is beyond its significance as a cost heading. Modern mining requires large amounts of investment in capital infrastructure and equipment to produce a product sold at a low unit cost. To stay competitive, such a business has to focus on full realisation of its capital investment, ie sustained production at high levels. Maintenance plays an essential role in achieving this goal. Mining companies typically use a mix of breakdown or corrective maintenance, planned maintenance, and some condition-based maintenance. The share of breakdown maintenance has been coming down through more effective planned maintenance and better condition monitoring tools. Planned or preventive maintenance (PM) is playing an increasingly important role in todayÆs mining maintenance. This is the suite of inspection and repair/replacement actions performed at scheduled time intervals as part of a preplanned activity. The activities are scheduled well in advance and, usually, the current wear-state of the machine is irrelevant. For example, the replacement of a major gear may have been planned 18 months in advance; replacement is carried out when the time comes regardless of the actual condition of the gear. The PM costs are significant and include direct cost of parts and labour as well as the opportunity cost of lost production while the machine is under maintenance. It is important to identify the optimum PM effort because over-maintenance should be avoided as much as under-maintenance. A new concept called severity-based maintenance is introduced in this paper. We have seen that measuring equipment ageing in mining merely by counting the engine hours is a very imprecise way of planning and scheduling maintenance because the damage accumulated in one hour varies enormously from operator to operator and with changing pit conditions. We recommend continuous monitoring of duty on all major equipment. This is feasible without having to fit out the machine with an army of sensors because most of the physical sensors required by dutymeters are already installed and maintained as part of the existing performance monitors. While the investment is modest, the potential benefits are huge and can be grouped under three headings:Immediate benefits will come from providing operators with direct feedback on the effect of their behaviour on machine health and training them to use this feedback to correct their operating style. The equipment can operate closer to the limits of capacity, producing more without unduly sacrificing the availability by monitoring and controlling the severity of the operation, ie the duty on the machine. Longer term benefits accrue from establishing correlations between actual time to failure data and measured equipment duty and using these correlations to optimise maintenance effort as well as planning new equipment purchases and warranty conditions.

Jan 1, 2002

By A. Demirci, A. Keçeciler, Y. S. Durutürk

"This paper deals with the results of the variation of thermal conductivity of rocks with pressure on a laboratory scale. For this purpose, the authors have added a pressure-supplying unit to the apparatus developed by Mousset-Jones and McPherson (1986), Önder (1995), Ashworth and Ashworth (1979), and Innaurato and Occella (1989) in order to measure the thermal conductivity under pressure. The values obtained from the tests performed by this new apparatus have been stated using a regression analysis and the related graphs have been drawn. Results have shown that the thermal conductivity of rock varies digressively with pressure. The same results have been obtained in different rocks types. IntroductionOne of the most important tasks of mining engineers is that of establishing, maintaining and sustaining safe and healthy working conditions in underground mines.Heat can have a profound effect on safe and healthy working conditions and is one of the main problems in deep underground mines. In this regard, the temperature of the air passing through the mine openings increases steadily and causes a decrease in the efficiency of workers due to the unwanted physical effects to human bodies in the working area. At the same time, the hot and humid environment resulting from heat and temperature rise causes some important occupational diseases and increases the accident risks in the related openings."

Jan 1, 2002

By John E. Rourke, O&apos

This paper describes some of the results of a project for the design and demonstration of subsidence monitoring systems for underground coal mines. The project was designed to test monitoring systems described in an earlier feasibility report (O'Rourke and others, 1979). General objectives of the project were to develop reliable cost- effective monitoring systems for use above caving- type mining operations, over supported mines, and in urban undermined areas. Topics selected for discussion in this paper include a description of the instrumentation systems, the site conditions, problems of installation, resulting recommendations and an over- view of subsidence performance data obtained. There were some particularly difficult problems of installation to overcome at this site. Some of these could be experienced at any surface or under- ground project, others are probably more directly related to Western coal fields. Almost any subsidence monitoring program may face the following difficulties:

Jan 1, 1982

By J. Engelbrecht

South Africa?s re-entry into the fast moving and competitive global economy calls for some careful strategic planning and a good deal of co-operation between suppliers and end-users. The issues that need addressing are generally well known and include: ?South Africa was ranked 45th out of 46 i.r.o. productivity ?SMMEs contribute 1% to exports compared to 40-60% for the ?tigers? ?High unemployment ?Limited skills of the majority of workers ?Slow growth rate of the economy ?The vast majority of suppliers are not world-class ?The vast majority of suppliers are not export or marketing orientated. In order to survive, all parties, i.e. government, labour and business, will have to play their part.

Jan 1, 1999

"This paper describes some of the methods and equipment used for fine milling of minerals, and gives particular attention to the Vibro Energy system.In addition, the paper describes a specific application in the gold mining industry. This is the 200 tpd plant built by Anglo American Corporation at the President Brand Mine in South Africa in 1985, now a division of Freegold. This plant treats a gold bearing pyrite flotation concentrate which is finely ground to 15 microns prior to cyanidation and carbon-in-pulp (CIP). l .0 INTRODUCTIONFree milling gold ores are those that yield acceptable dissolution and recovery of the gold following grinding to what can be described as normal fineness, frequently between 50% and 90% passing 74 microns.Increasingly, gold metallurgists are faced with ores that are refractory. The traditiona1 treatment route for refractory gal d ores and concentrates has been by roasting, but for environmental reasons this is becoming less acceptable, or in some areas of the world, totally unacceptable. New methods of treating refractory gold ores are being developed and applied in practice. These new methods include pressure and biological oxidation. Higher gold liberation can also be attained by increasing the fineness of grind, although with conventional systems there are economic limits to this.In flowsheet development and test programs on new deposits, a standard procedure is to establish the relationship between the grind and subsequent go 1 d extraction. The normal situation is that gold extraction increases as the ore, or concentrate, is ground finer. Typically, this relationship is as shown in Fig. l, where the incremental additional extraction is very small once an optimum, or economic, grind has been achieved. This generally app1ies whether the material is free milling or refractory. The limits to grinding are set by the type of equipment which is commonly in use, usually ball mills. These mills have the obvious advantage of high capacity, however, they are increasingly inefficient as finer grinds are required. In general, ball mills are used to reduce ore to some agreed percentage passing 74, or possibly 53 microns."

Jan 1, 1988

By A P. Tinnelly

This paper explores the structural/physical and policy based issues that have lead to the apparent resource conflict between Forestry and Mining on the West Coast. Both industries are important to the West Coast and bear many similarities, particularly at the corporate end of the mining scale. However there are very distinct structural differences which set the scene for friction at the boundaries. Examples of how mining impacts upon forestry illustrate where some of the friction arises and provides some insight as to where some solutions are or may be found.

Jan 1, 1996

By Kenneth R. Sites

Under this program two tape recording and triggering systems were developed and delivered for use in the Bureau of Mines microseismic program. The systems are designed to improve the effectiveness of the Bureau owned Sangamo 3500 series and SABRE VI instrumentation tape recorders. The system is designed to capture random microseismic data, digitize and temporarily store these data, start the tape recorder; and then transfer the data to magnetic tape for permanent storage. The system is designed to pack data on tape such that the tape may be simply played back through galvo drivers onto an oscillograph such that a continuous series of analog records, with corresponding time of day information, are reproduced without excessive oscillograph paper waste or the need for the operator to search for valid events.

Jan 1, 1980

By Vance G. Leak

Leaching of manganese from low-grade Minnesota ores was studied over the temperature range 25° to 225° C at atmospheric and elevated pressures to demonstrate that good recoveries of manganese could be achieved from unroasted ores using reagents available nearby. Various combinations of ore, pyrite, lignite derivatives, and sulfuric acid were tested on a small scale. Pyrite alone required the highest temperature to effect a good extraction, but the combination of pyrite, lignite char, and sulfuric acid solubilized 99 percent of the manganese after 30 minutes of reaction at 75° C.

Jan 1, 1971

By W. Kracht

Frothers are surfactants used in floatation to aid generation of small bubbles. Studying events at the moment of bubble creation is a challenge because of the short time frame. This presentation introduces a novel acoustic approach. The technique has the resolution capable of detecting events that occur within 1-2 ms. The transition from coalescence to non-coalescence is tracked as a function of surfactant concentration and gas rate through the capillary. Results are given for some common flotation frothers and n-alcohols (C4-C8). A stress model is used to give a qualitative explanation to the observed action of frothers on coalescence prevention. Results for salt (sodium chloride) are included for comparison).

Jan 1, 2009

By Floyd Varley

In deep and highly-stressed coal mining, advanced design practices are used to minimize the potential for damaging events to occur. Despite these design efforts, the hazard of coal mine bumps can not be completely eliminated. This paper will review current and historic work practices used internationally to minimize the hazard to miners from mining in conditions which could produce a bump. These site specific work practices have a common base in monitoring for conditions which could result in a bump and application of controls to prevent the occurrence or minimize the severity of an event where miners are working. Monitoring practices range from purely observational to semi quantitative. Control methods attempt to initiate events in a controlled manner, absorb the energy of a potential event or reduce the potential for or magnitude of an event by altering the stress conditions of the mine workings. Building from the experiences of other coal fields, an empirical framework to manage the potential hazard of coal mine bumps can be developed to enhance the level of safety provided by prudent mine design.

Jan 1, 2008

By J. Nell

An overview is given of the matte melting process used for the beneficiation of South African platinum group metal (PGM) ores. Most producers use six-electrode furnaces to melt the concentrate and Pierce Smith converters to oxidize excess iron sulphide from the furnace matte. Concentrates from two reef types (the so-called Merensky and UG-2 reefs) dominate the feedstock supply. Concentrate from the Merensky Reef is low in chromium and does not pose significant melting problems. Concentrates from the UG-2reef contain much higher levels of chromium, which results in the formation of chromium-rich spinels during melting. This is attributed to the low solubility of chromium in furnace slag under typical operating conditions (an oxygen partial pressure of 10-8?10-9bar at temperatures of 1550°C to 1600°C). During the converting process, care is needed to avoid excessively oxidizing conditions, which result in cobalt, nickel and copper losses to the slag. High nickel losses result in the formation of Fe2NiO4 (trevorite), which often forms solid solutions with FeCr2O4and Fe3O4. In future, the main challenge in the processing of South African PGM ores will be to cope with ever-increasing levels of chromium in the concentrate. A short-term solution to the problem would be to melt the concentrate under slightly reducing conditions to promote the formation of CrO, which is more soluble in the slag than Cr2O3.A longer-term solution to the problem would be to abandon the current matte-smelting process in favour of an alloy-based process, which would offer total flexibility with respect to the amount of chromium that can be tolerated in the feed. Keywords: Merensky, UG-2, furnace, slag, matte, converting, spinel, chromium

Jan 1, 2004

By Ernest Baafi

A simulation model RoadSIM using the ARENA modelling system has been developed to evaluate roadway development options for a given development panel configuration. The RoadSIM simulation system has provisions for variability/randomness in operations including cutting and loading at the face, tramming and discharge of coal to the boot end and availability of equipment. The modelling system provides a means for assessing the operational limitations of roadway development practices at a particular coalmine. It is a ?what if? tool that allows a range of equipment, configurations and operating practices to be assessed in terms of achievable advance rates and equipment utilisation. Output from the system is in the form of a dynamic visualisation as well as summary reports and detailed logs of operations over time.

Oct 1, 2009

The Dynamics and Thermodynamics of Absorbing Lithium of Ion Sieve Preparing Pollymetallic Nodules

Sep 13, 2010