Search Documents

By W van der Westhuizen

Mining professionals recognise the need and application for reconciliation and value tracking. It is necessary however to examine our current reality, and evaluate the following. Do our reconciliations really balance correctly, and are we able to track value effectively throughout processes? If we are honest, in most operations the answer is a resounding no. This means that we are surrounded by fluctuation and deviations that we do not account for and do not understand. This is astounding, because given our level of scientific knowledge and the technological tools at our disposal we should have a good understanding of our environments and be able to manage them effectively. How do we manage effectively if we are surrounded by so much uncertainty? The purpose of this paper is to describe, at high level, the principles of reconciliation and value tracking, to highlight some areas where deviations are introduced into the mining process, and to propose a different approach to the apparent reconciliation and value tracking conundrum. The paper also poses several questions that need to be critically addressed at most operations. Instead of making the same mistakes each month in reconciliations, mining professionals need to acknowledge two facts. Firstly there will be uncertainty that we need to accept, since all our estimates are based on sampling, an orebody is not homogeneous and peopleÆs behaviour will influence the process, etc. Variability will always exist and lead to uncertainty. What is the current approach in the reconciliation process when a deviation occurs and how do we use reconciliation and value tracking to manage and improve our business? The second fact is that we need to stop using reconciliation and value tracking to only measure and report. We need to adopt a new approach to manage mining throughput, where reconciliation and value tracking are enablers to the success of the business. In most mining operations, significant effort goes into planning and measurement for the purposes of reconciliation and value tracking. The importance of accurate and effective reconciliation and value tracking should be to ensure the maximum utilisation of the resource, maximising throughput and enabling the business to deliver a product to its client, of the correct quality and in a timely manner.

Jan 1, 2002

By T. G. Joseph, G. W. Hansen

"This paper considers the duty cycle of an electric cable shovel and correlations with measured passive seismic responses of the underfoot oil sands material in-pit. It has been observed that the cyclic activity during operation of any shovel in the oil sands environment causes the material to deteriorate and provide a less than ideal footing for this large item of equipment, whose dead weight approaches 1500 tons with a footprint of merely 75 sq. yd. Consequences are manifested in the form of carbody and side frame cracks, and associated downtime, maintenance activity, cost, and subsequent loss of availability.The objective of these considerations, as part of the Oil sands-Equipment Interaction Program (OsEIP), currently a joint venture between Syncrude Canada Ltd., James Progithin International (JPi) Ltd., Caterpillar Inc., P&H MinePro and the University of Alberta, is to identify and provide feedback to the manufacturer and end user of adverse shovel-ground conditions. This would enable the manufacturer to incorporate greater knowledge into the design process and the end user to direct operations in an enhanced proactive maintenance stance."

Jan 1, 2002

By D. Bedell, J. Robitalle, D. Macgilliveray

Agnico Eagle (Cadillac Quebec, Canada) selected the new Eimco PEC E – CAT™ clarifier thickeners for their counter-current decantation circuit, which handles approximately 200tph leached gold/silver ore. The E-CAT is based on rakeless ultra-high rate thickening technology that originated in South Africa. Four 9m diameter and two 10m EIMCO E – CAT ultra high rate, rakeless thickeners were installed in the fall of 2000. Thickening and clarification performance has been excellent. Problems with level control have been resolved and the plant personnel continue to improve the operating control techniques. The CCD circuit is critical to the success of the operation and good recovery. Data will be presented showing the wash ratios and recovery achieved. A brief history of the operation and the decision to utilize the CCD system will be presented.

Jan 1, 2002

By Maurice Deul

For the first half of the 21st century, the United States will rely on the same mix of fuels it has for the past 50 years. Petroleum for the United States will cost more and availability will decline as developing nations modernize. Increased use of natural gas for electric power generation will result in stress on the gas supply. Coal will be the fuel of last resort. More than half the petroleum used is imported, about the same amount as used for transportation. Only coal can provide relief by fueling railroads through electrification while encouraging “piggy-back” trailer haulage, co-generation for manufacturing and expanded passenger service.

Jan 1, 2002

By John E. Tilton

Real copper prices during the past several decades display two striking characteristics. First, they are highly volatile. Within a year or two, copper prices can rise or fall by 30% or more. Second, over the longer term, they are falling. Indeed, since 1970, the secular trend price for copper is down by more than 50%. Figure 1 highlights both of these characteristics. It shows the average annual US producer price for copper since 1970 measured in constant 2001 US dollars. While the London Metal Exchange (LME) copper price is not shown, it and the US producer price have for some time moved more or less together. So pronounced short-run fluctuations around a significant long-run decline describe copper prices, not only in the United States, but around the world.

Jan 1, 2002

By E. A. Barrett, L. L. Rethi

Throughout all segments of the United States mining industry, 163 independent contractor employees were fatally injured between 1990 and 1997. Factors that contributed to these injuries were identified after reviewing descriptive information contained in Mine Safety and Health Administration fatality reports for each of the incidents. Thirty-three unique contributing factors were identified and multiple factors were noted for each fatality. Those most frequently discerned were "failure to follow `standard operating procedures"', (35% of the fatalities), "poor positioning of employee" (26% of the fatalities) and "failure to maintain equipment" (23% of the fatalities). Contributing factors were then associated with the accident and job classifications of the victims. Factors having the highest frequencies in the top five accident classifications where most fatalities occurred were as follows: powered haulage - "failure to maintain equipment"; machinery - "poor positioning of employee"; slip/fall of person - "inadequate fall protection" and "failure to wear safety line"; electrical - "equipment contact with power line"; and falling/rolling/sliding rock - "poor positioning of employee. " Among the job classifications in which most fatalities occurred, leading contributing factors were as follows: truck driver - "failure to follow standard operating procedures" and "poor positioning of employee"; laborer/utility man/pumper - "poor positioning of employee"; mechanic/ repairman and welder - "failure to follow standard operating procedures." Recommendations for utilizing contributing factor information as a basis for safety training are proposed. Training programs may be developed that inform independent contractor employees of factors which, in the past, have contributed to fatal injuries in their job classifications. Then, by combining this information with contributing factors identified in "related" accident classifications, a truly focused training intervention that addresses very specific workplace hazards may he developed.

Jan 1, 2002

By R. J. Durrheim

The DEEPMINE Collaborative Research Programme was established to create the technological and human resources platform that would make it possible to mine gold safely and profitably at depths of 3 to 5 km. The DEEPMINE Programme has four goals: to acquire knowledge of and develop appropriate technology for new ultra-deep level mines, to stimulate education and training, to establish a culture of innovation, and to encourage rapid technology transfer and implementation. The research programme was launched in July1998 and will be completed in March 2002, with the final year focusing on the transfer of knowledge to the industrial partners. DEEPMINE represents a new model for conducting mining research: it is driven by industry needs; emphasizes collaboration between industrial partners, research organizations and tertiary education institutions; and has a novel joint-funding mechanism. DEEPMINE has employed a range of vehicles to transfer knowledge to its industrial partners. Novel aspects include: (a) electronic publication of Summary Reports and Guideline Handbooks that seek to consolidate the huge body of knowledge comprehensively and concisely, (b) a series of DEEPMINE Schools designed to enable industry practitioners to apply the knowledge to their current work situation, and (c) Consultancy Reviews, where DEEPMINE specialists seek to apply knowledge to specific real problems on mines.

Jan 1, 2002

By D. J. Hutchinson, S. Nickson

Cable bolts are used as a means of rock support around underground excavations in many mines across Canada and around the world. A substantial body of research on cable bolting was conducted at a number of Canadian universities and mines from the mid-1980s through the 1990s. Since then, research into selected areas of cable bolting practice has continued in Canada. The research has focussed on cable bolt instrumentation and on the inclusion of cable bolts in empirical stope design techniques. A review of cable bolting practice is now warranted at many mines. It has been five years since the completion of the previous substantial body of Canadian academic research and the associated advancement in understanding of cable bolt design, implementation and verification practice. Attempts were made at that time to transfer the new design procedures and performance assessment technologies to mine-site personnel. In some cases, this was effective, and ground control personnel continue to improve on their cable bolting practice at each specific mine site. However, at other sites, experienced people have moved on, and the new, less experienced personnel do not have access to the training or technical resources required to improve their understanding of the subject. In other cases, the technology was not transferred effectively to practitioners, with the result that substantial improvements can be made to the cable bolting practice at those mines. Guidelines for auditing cable bolting practice are provided in this paper. The guidelines include a discussion of the objectives of the audit, suggestions for audit procedure and a summary of the possible outcomes of a cable bolt audit. The objectives of an audit might include assessing the reasons for unexpected cable bolt failures, evaluating the quality of the installation procedures, quantifying the efficiency of the cable bolt system and assessing training requirements and procedures. A cable bolt audit should include consideration of all aspects of the cable bolting cycle, including the design, implementation and verification phases of the operation. At the end of the audit, a ranking should be assigned to the components of the cycle. The ranking system can then be used to identify items that require immediate attention, others that could be improved and others that are adequate. Following completion of a cable bolt audit, increased confidence in the support system and its application is generally, found, along with the potential for cost savings in many cases.

Jan 1, 2002

By Todd M. Ruff

Researchers at the National Institute for Occupational Safety and Health are investigating technologies that could be used to detect objects, small vehicles, and pedestrian workers that may be in the blind areas of haulage equipment used in mining and construction. A detection system that warns the equipment operator that there is an obstacle nearby could prevent collisions and save many lives each year. One popular technology for collision warning systems is radar. Several different types of radar have been tested in the laboratory and on mining equipment. Early in the study, questions arose concerning the best way to test radar systems. Many factors affect the performance of radar, including the size, shape, and composition of the object that is to be detected; the height of the radar antenna(s); and the relative motion of the radar system and/or object. This report discusses several different test procedures and test targets and recommends methods to determine how effective a radar system will be in detecting a person near heavy equipment.

Jan 1, 2002

By D. Mishra

Electric arc furnace dust (EAFD) generated during the recycling of steel- scrap is classified as a hazardous waste for landfilling. This is because it contains leachable heavy metals such as zinc, lead,... Recovery of these metals could result in both resources conservation and resolving waste disposal problems. A study of the thermal reduction of a sample of EAFD was carried out in an inert gas atmosphere using coke as a reducing agent. Preferential volatilization of zinc and lead was achieved during the reduction process at about 800 "C. More than 96 % of both zinc and lead were removed from the dust and were recovered in the condensates. The treatment residue was essentially composed of iron oxides and almost free from heavy metals.

Jan 1, 2002

By Steve Kral

The domestic mining industry may be in the doldrums but there appears to be hope, at least from a regulatory standpoint. At least one US senator believes that the events of Sept. 11, 2001 made many citizens see the need for the country to become more self-reliant on its growing energy needs. Even before that tragic day, however, the Bush administration was making a strong push to open up more public land for energy and natural resource development.

Jan 1, 2002

By C. O. Brawner, J. Kalejta II

The classical approach to control rock fall and ravel in open pit mining has been to use catch benches. The width and volume of benches is most dependent on the bench height, size of loading equipment, blast damage to the face and mining regulations. This was compatible with open pit slopes of less than about 45°. As our understanding of rock mechanics and blasting control has improved over recent years, much steeper rock slopes can be developed at many open pit mines. However, narrower benches result with less rock fall capacity. The transportation industry has been very successful in using catch fences to protect highways throughout North America and Europe for years. The authors recommend that cable and ring net fences have a potential major application in open pit mining to allow steeper rock slopes with significant economic benefit. This paper outlines the application, design and operation of catch fences in surface mining for specific conditions. Typical case examples are presented.

Jan 1, 2002

By Thomas J. DeMull

Development of the Batu Hijau copper project was completed in the fourth quarter of 1999 with the formal handover and start-up of ore processing facilities. The project began in August 1996 when the owner, PT Newmont Nusa Tenggara (PTNNT), awarded an engineering, procurement and construction (EPC)contract to Fluor Daniel (FD) for the development of the project. This included a copper concentrator, port, power plant, town site and infrastructure. PTNNT managed the development of the mine and the procurement of the mine equipment. In 1996, Batu Hijau was the largest mining project ever undertaken. Developing the Batu Hijau Mine was complex. It involved the work of thousands of people in all parts of the world to plan, engineer, procure, fabricate and manufacture equipment, supply and deliver materials and equipment, and build the plant.

Jan 1, 2002

In 1991, Placer Dome Venezuela established a 70% stake in Minera Las Cristinas, to mine the Las Cristinas gold deposits in Bolivar. This case study examines the multi-sectoral partnership arrangement that was developed to improve health services near the proposed Las Cristinas gold mine. The investment climate in Venezuela is uncertain and the socio-economic circumstances are potentially hostile. Despite that, the partnership between the mining company, local communities, government agencies and an international health nongovernmental organization (NGO) collectively leveraged nearly $2.5 million to build and operate a community health center.

Jan 1, 2002

By J. D. Noll

Elemental carbon (EC) is used as a surrogate for regulating the exposure to diesel particulate matter (DPM) of underground metal/non-metal miners. EC was chosen as a surrogate because EC is selective to DPM and is a major component of DPM. Using EC as a surrogate also gives one the advantages of no sampling artifacts and being able to sample at all locations in the mine. Currently, EC represents DPM well in underground mines. Some control technologies have been shown to possibly alter the relationship between DPM and EC and characteristics of DPM. Therefore, future work will investigate the relationship between DPM and EC as new control technologies are implemented.

Jan 1, 2002

By Robert Snow, Yingxue Yu, Patrick Zhang

The FIPR/SAPR process is FIPR's third approach to develop a viable alternative to the Crago "Double Float" process for phosphate flotation. SAPR stands for Single-collector, All-anionic Phosphate Recovery. The FIPR/SAPR process - offers a universal flowsheet for any anionic reagent system and flotation feed of varying sizes. For an unsized or fine flotation feed, the FIPR/SAPR process consists of the following steps: 1) high-solids conditioning with an anionic collector; 2) anionic rougher flotation, with the rougher concentrate sized at 48 (or 65) mesh and the +48 mesh recovered as a final product; and 3) cleaning flotation of the -48 mesh fraction from step 2. In a variation of step 2, the rougher concentrate from the first two cells may be collected as a final product, and the rougher concentrate from the last two cells sized at 48 or 65 mesh. The new process was tested with a blend of anionic collectors, achieving single-digit Insol at 85 + % recoveries.

Jan 1, 2002

By A. I. Kalugin, A. A. Abramov, D. E. Kozlov, D. V. Magazanik

Based on theoretical and experimental researches of phosphate and carbonate minerals flotation in the presence of soluable glass at various pH values and sodium silicate concentrations, it has been established that the presence of soluble glass in solution leads to formation of silicate compounds on the surface of phosphate and carbonate minerals causing change in their floatability for the worse. The harmful influence of soluable salts is done by tying of collector as metallic soaps, forming precipitates on the surface of minerals to be floated and causing their depression of flotation, and breaching of the froth etc. Depressing action of slimes and products of interaction with collector depends on the ratio of values and signs of potentials of the mineral surfaces. The possibility of phosphate and gangue minerals separation can be evaluated by comparing the minimum-necessary concentrations of collector required for their flotation.

Jan 1, 2002

The relationship between comminution testwork results and the milling circuit that is subsequently selected is not a direct one and frequently involves recourse to databases of past test results. This in itself reflects the lack of a systematic engineering approach in the design process. This paper reviews comminution tests for SAG mill design in an attempt to identify where the essential information comes from that will be used in mill selection. The conclusion is that results from traditional test methods, including obscure and little used procedures like the Mokken test, are more valuable from an engineering perspective than parameters for breakage rate based modelling. Suggestions are made on ways in which existing test procedures can be enhanced in order to generate parameters that can be directly related to characteristics of the milling circuit being designed.

Jan 1, 2002

Novel flotation reagents were developed to improve the flotation of coarse particles. Laboratory tests conducted on an anthracite coal sample from Kyung-Dong Coal Company, Korea, showed that the reagents can successfully clean 2?3 mm top-size materials. Pilot-scale tests conducted on a 1.41 mm x0 coal gave substantially better results than those obtained using kerosene as collector. The pilot-scale test results were used to develop a flowsheet, in which the 1.41 mm x0 fraction is cleaned by flotation and the 4 x1.41 mm coal is cleaned by single-stage spirals. The performance of this circuit was compared with another flowsheet, in which the 0.5 mm x0coal is floated using the conventional flotation reagent, with the 4 x0.5 mm material being cleaned using two separate spiral circuits. The performance of the two flowsheets was compared by computer simulation. The results showed that the flowsheet consisting of the coarse particle flotation circuit can give substantially higher yield sat a given product grade. Keywords: coal flotation, coarse particle flotation, collector, spirals, computer simulation.

Jan 1, 2002

Over years of exploration the massive and tabular orebodies in the area to the South West of Western Areas Gold Mine had been assessed as containing about 50 million ounces of gold û a world class orebody. Planning initially was for a surface and subvertical shaft system to exploit this area but because of cost, a single lift shaft to an area which could be accessed ex Western Areas was planned to intersect the reef at 2760 metres. It was also planned to mine out the shaft pillar area long before the deep shafts would reach that position. This is not the normal practice in South African Gold Mines. The stoped out shaft pillar was backfilled to minimise movement in the shaft sites. The result of a competitive tender/adjudication process was that Cementation Mining û Skanska won and was awarded the R192 million contract to sink the Main and Ventilation Shafts on 15 June 1995. On 1 April 1999 Western Areas and Placer Dome SA formed a Joint Venture, which now owns and operates the mine on which the South Deep Shafts are situated. This situation prevails today.

Jan 1, 2002