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 P. Somasundaran, S. E. El-Mofty

A comparison of the IMC Anionic Process and the CLDRI Process, based on pilot plant testing of waste pebble by Jacobs Engineering is presented. Estimated costs for constructing and operating a beneficiation plant utilizing dolomite flotation are given. Research to develop practical flotation processes for removing dolomite from low-grade phosphate rock has been a high priority for the Florida Institute of Phosphate Research. The Institute funded the above pilot plant programs in 1998 and 2000. The Florida Phosphate industry currently deals with the increasing dolomite content of ore reserves by practicing selective mining. Heavy media separation plants installed at two mines to remove dolomite from pebble are not being operated. The flotation separation of dolomite from waste pebble requires that the flotation feed be ground. Grinding liberates the mineral species and produces particle sizes small enough to be floated. Only two dolomite flotation processes, the IMC Anionic Process and the CLDRI Process, have been successfully demonstrated on flotation feed that has not been deslimed after grinding. Deslimed flotation feed, relative to undeslimed feed, has improved flotation performance and reduced reagent consumption. However, for the above mention processes, undeslimed ground feed increases the yield of concentrate because the phosphate desliming losses are avoided.

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 A. D. Davis, C. J. Webb

Brohm Mining Company's Gilt Edge Mine in the northern Black Hills was a surface heap-leach operation that was active from the 1980s until 1999. Financing problems and acid drainage concerns at the mine were reported in the late 1990s. In February of 1999 the Governor of South Dakota announced plans to request the U.S. Environmental Protection Agency to help clean up acidic water at the mine and reclaim the site. In July 1999 the parent company of Brohm, Dakota Mining, filed for bankruptcy in Canada. Because of the bankruptcy and environmental problems, the State of South Dakota intervened and began water treatment. The mine was declared a Superfund site in 2000. Hydrologic issues include the potential for acidic drainage from the site. The mine is at the headwaters of Strawberry Creek, which drains into Bear Butte Creek. About four miles downstream, Bear Butte Creek loses its discharge to swallow holes in the karstic Madison Limestone aquifer, a regionally extensive and valuable ground-water reservoir. Other concerns at the site include treatment of acidic water in mine pits and a waste rock dump.

Jan 1, 2002

By Robert Snow, Francisco Sotillo

Six types of amines were evaluated in the cleaning step of the rougher concentrate for the Crago “Double Float” process in terms of relative selectivity. Selectivity of these amines was ranked based on both batch and locked cycle flotation tests. Two parameters were used for selectivity ranking, the Selectivity Index, SI, and the ratio of insol rejection to the tailings weight percentage, R*. The comparison of the flotation results of the batch tests of the cleaning step of the Crago process for an unsized amine feed generated the following ranking from the most selective to the least selective mine: Quaternary > Primary [ ]Tertiary [ ] Condensate > Ether > Secondary(?).

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 G. H. Schnakenberg Jr.

In response to the underground mining industry's growing concern with the exposure of workers to the diesel particulate matter (DPM) component of diesel exhaust, a method was developed to estimate the average workplace concentration of DPM that could be expected from using the new lower DPMemitting engines now being approved by the US Mine Safety and Health Administration (MSHA) when these new engines are equipped with state-of-the-art exhaustcontrol technology for filtering and combusting DPM. The resulting estimate uses the MSHA-reported particulate index for these engines, the prevailing rule-of-thumb ventilation rate of 150 cfm/hp and the available diesel-exhaust filter technology that has been shown to be at least 80% effective in reducing tailpipe DPM. In the estimate calculation, every engine used in an underground mine is assumed to be equipped with this control technology. Under the stated reasonable conditions, an average DPM level of 90 µg/m3 (mass) is predicted as technically feasible.

Jan 1, 2002

This paper deals briefly with productivity-enhancing advances in shaft sinking technology in South Africa post-World War II in general and the developments and application of long rounds since the 1980s in particular and is amply illustrated.It touches on the conversion to circular section, concrete lined shafts, the introduction of tungsten carbide drill bit inserts and grab lashing; expounds the rationale driving the development of longer rounds; and then describes the evolution of long rounds using hand-held and mechanically mounted rockdrills in South Africa and Canada by both local and foreign contractors. The recent experience gained on the sinking of the South Deep Main Shaft follows. Results obtained from this experiment are tabulated and commented upon. The paper concludes with the postulation of æwhat nextÆ and æwhere toÆ scenarios. Addenda include a list of shaft rounds in excess of three metres in length blasted in the Main Shaft at South Deep and their results, typical round design, manufacturerÆs specifications for the 6 m shaft jumbo and rock drills.

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 J C. Furness, F S. Cannon

Metal casting operations are a significant source of hazardous air pollutants. In particular, high production iron foundries emit significant quantities of volatile organic compounds (VOCs) during pouring, cooling and shakeout of iron castings made in green sand molds. End-of-the-pipeline capture and destruction methods to reduce VOC emissions add crippling costs to foundries. Alternately, the incorporation of advanced oxidants (AO) into metal casting green sand systems has been shown to reduce emissions from high production iron foundries in the US, and at the same time reduce operating costs. Cost savings are driven by the benefits of AO in clay recovery systems. Emissions reductions are the direct result of cascading AO-based reactions taking place in green sand molds. This sustainable greening of the metal casting process is a prototype for the development of other AO and non-AO process-based solutions for sustainable high temperature processing of materials. Fundamentals of AO technologies will be discussed along with the performance characteristics of AO processing systems in the metal casting industry and the breadth of other processing and remediation applications for which AO technologies have the potential to be successfully employed.

Jan 1, 2002

By R. C. Guimareãs

Serrana's deposit contains three types of ore: oxidized, micaceous and silicate-carbonate. The results presented refer to characterization and fundamental studies performed on fractions resulting from the purification of five samples from the silicate-carbonate type collected in the mine. Each type was purified and submitted to mineralogical characterization, zeta potential determinations, and microflotation experiments. The samples, with exception of the barite, are mineralogically complex and the selectivity between apatite and gangue minerals is poor. Under the current state of art, it is impossible to feed the plant with the silicate-carbonate ore, unless it is blended with the standard oxidized ore.

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 A B. Bell

The health and in some cases survival of mineral exploration and mining companies is, in today's markets, more dependant than ever on the effective use of information technology. The need for speedy collection, organisation, maintenance and distribution of corporate and project information is a phenomenon that will continue to strengthen with market thirst.Geographic Information Systems (GIS) provide a medium for storage, maintenance and retrieval of data, and Internet Mapping adds a technology for effective distribution of that data. Combining these technologies can return benefits both fiscally and technically by reducing costs of ownership in IT infrastructure and increasing the efficiency and effectiveness of both internal and external information delivery.GIS and Internet Mapping technologies have reached a practical stanza in their evolution and will continue to develop as a key business tool in the natural resources sector.

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 Frank R. A. Jorgensen

Flash smelting is used to smelt a large proportion of the world's copper and nickel and some lead/zinc concentrates. Understanding the factors controlling the ignition of these concentrates is an important consideration in designing burners and maximising the throughput of the flash smelting process. The literature on the subject is briefly reviewed and techniques for the measurement of ignition temperature discussed. The mineralogy of the concentrates and the role of thermodynamics and phase diagrams in interpreting and predicting ignition behaviour are emphasised and applied to interpreting results obtained on a nickel concentrate.

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