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By Whiten W. J

A simulation model was used to study the performance of various types of screen cloth on industrial vibrating screens. The model takes into account the effect of loading upon screen performance and predicts both themass flow rate and size distribution of the screen products.It was found that the use of the simulation model allowed the reconstruction of data for identical conditions and hence has simplified the analysis of the comparative performance of the screens. The dependence of performance upon operating conditions was found to vary markedly with screen cloth type.

Jan 1, 1977

By Bruce D. Hanson

A computer model capable of simulating the basic production system in a variety of underground mining methods has been developed at the Twin Cities Mining Research Center. This Bureau of Mines paper describes the simulation of the basic production system at the working face, which includes drilling, blasting, mucking, and roof bolting. The model is event-oriented; that is, the status of the system is updated at the occurrence of an event. All event or activity times, including failure and repair of equipment, are treated as stochastic variables. A location dimension, in addition to the time dimension, is used, allowing the simulation of multiple location systems. To aid the user in determining the efficiency of his system, the model provides several reports. An event or activity report gives the frequency of occurrence total active time, and cumulative delay statistics for each event. An equipment report delineates the availability and utilization of all equipment. A production report provides information on various performance measures such as tons produced and holes drilled. The cost report gives the cost of various elements in the system. Operating data from an actual mining situation were used in validating the model. In addition to the description of the model, examples of simulation experiments which were performed on a room-and-pillar mine system are given. Use of the model to determine methods for improving the efficiency of the system is discussed.

Jan 1, 1974

By G. Gavan

Analysis of reported injuries for off-highway haul trucks indicated that 42.7% were slip and fall, and of these 34.1% occurred mounting and dismounting the machine. Redesign of the lower steps was concluded to provide the most overall improvement for increased safety and accident reduction. Various existing, innovative and conceptual designs were reviewed and evaluated. The most promising candidate designs were the four-spring supported lower steps and the center tube mounted lower steps. Both configurations proved to be viable designs as they passed successfully human factors and survivability tests conducted at a large copper mine.

Jan 1, 1979

By G. Balletto, C. Furcas

"The mineral raw materials industry is a key-component of the Gross Domestic Product of industrialised economies, closely related to both the building and the industrial sectors. Despite this, at local level mining and quarrying are associated with both irreversible environmental damage and several visual alterations affecting the natural landscape. In this sense, SIA (Social Impact Assessment) has become a strategic tool that can not only improve the prediction but also the assessment of the social impact by involving the local communities in a participatory process. Taking into account the SIA experience, together with the examination of some relevant international case studies, it is possible to draw up a list of good practices for mining project management, from exploration through to closure and beyond, with quarry restoration. Such good practices will complement the existing studies, focusing on environmental issues, with the social issues arisen considered in SIA application."

Jan 1, 2011

By A. Cambitsis

We show that the prioritization of business improvement and performance management decisions may be significantly improved by taking into account the systemic effects of changes made in a single process area. To do so we build a model of a mining value chain, taking into account consequential downtime that arises from downstream and upstream starvation and choking effects of each activity. Introducing the concept of internal capacity, this approach yields insight into the relative importance of key metrics such as loading and hauling rates. We suggest that a holistic view of this type should be a core component of business improvement and performance management decisions. Keywords value driver trees, production constraints, throughput analysis, capacity analysis, TOC (Theory of Constraints), activity interdependencies, unit cost reduction.

Oct 1, 2013

By L Soares, W T. Hennies, F Fujimura

A methodology of environmental performance evaluation in mining developments is proposed, as well as guidelines and procedures for obtaining information to improve their environmental performance. Environmental performance is the results of the mining activities and their relation to environmental issues. If this evaluation is carried out on an on-going basis, it is possible to anticipate or to identify the formation and development of an environmental impact in its early stages. Evidence or trends identified by environmental evaluation provide valuable information to prevent further damage. The proposed methodology is based on the significant environmental aspects of a selected monitored job site by environmental indicators which are then compared with previously defined environmental criteria and targets or goals. The methodology procedures also take into account the environmental accounting of the investments and expenditures.

Jan 1, 2003

By R. Karl Zipf

Highwall mining is an important coal mining method. Upwards of 60 highwall miners are presently in operation, and they may account for approximately 4% of total U.S. coal production. A review of the Mine Safety and Health Administration (MSHA) accident data over the 20 year period from 1983 to 2002 identified 9 fatalities attributable to auger and highwall mining of which inadequate ground control accounted for 1/3. In the past 5 years, 1 fatality occurred in highwall mining. Estimates of the manpower requirements in highwall mining suggest that its fatality rate is essentially the same as for surface coal mining, thus highwall mining appears to be a very safe modern mining method. Highwall stability is the major ground control related safety concern, and operators are required to develop and follow an appropriate highwall mining ground control plan. The plans usually specify the following geotechnical parameters: hole width, maximum hole depth, maximum overburden depth, seam thickness, web pillar width, barrier pillar width and number of holes between barriers. Calculated web pillar stability factor exceeded 1.3 for most designs evaluated. This study examined records from 5,289 highwail miner holes with a total completed footage of about 2,560,000 feet to understand the reasons for early pull out. Average lost footage is typically about 20% of planned footage. Only 35% of the holes reached planned depth, and 20% were short due to rockfalls. Water and adverse geology accounted for 15% of the losses. Mechanical/electrical problems, guidance, and slope stability problems accounted for the remaining 30%. Web pillar stability factor for these holes also exceeded 1.3 in 95% of cases. Trapped highwall miners present a safety hazard to workers during their recovery. Best practices to avoid trapped highwall miners include: avoid mining in stream valleys, avoid mining near outside corners, careful alignment of each hole and the use of an onboard guidance system, Several issues in highwall mining ground control require further investigation including highwall mining through old auger workings, highwall mining near old underground mines, multiple-seam and multiple lift highwall mining and finally the size and frequency of barrier pillars.

Jan 1, 2004

By M. T. Baquera

A comparison of microstructures associated with W single-crystal ([001], [011], [111]) rods prior to deformation (as grown), and after quasi-static compression (at a strain rate of ~1/s) by transmission electron microscopy (TEM) shows several orders of magnitude difference in dislocation density. Dislocation substructures were not significantly different amongst the deformed sample orientations. In contrast, [001] W rods penetrated into steel targets, at impact velocities of ~1.3 km/s, exhibited heavy dislocation densities and dynamic recrystallization as very distinct microstructural regimes accommodating the penetration process. Twinning on {112} also occurred as a precursor to, or remnant of, these microstructures near the projectile head. These results suggest that deformation accommodating the extreme strains and strain rates associated with the penetration of a single-crystal rod into a metal target is not adequately represented by conventional deformation

Jan 1, 2006

Resources and reserves are critical inputs into the determination of an operating mineÆs financial results and balance sheets, but how well understood is this fact. Do the investors, directors, accountants and geologists/engineers responsible for preparing or relying on relevant aspects of the end results properly understand the inputs and outputs and the associated risks that may be established. The first step is to understand how financial reports are impacted. The most obvious, and best known, impact is in the calculation of depreciation and amortisation charges against long term assets. In addition, however, there is a requirement to regularly determine whether asset book values are impaired û this is nearly always performed globally by the preparation of a discounted cashflow model for a mine which is usually based on a mine life as determined from the resource and reserve statement û the particular driver here is normally the short and long term production plans. A key aspect of the short term production plan is that it would normally not assume that the reserve and resource statement implies consistent grade, stripping ratios, etc. However, outside of the early years of a plan, more generic assumptions of these variables are often made in conjunction with the reserve and resource statement. Depending on the timeframe of the detailed production plans, this can have a large impact on a projectÆs net present value. Other financial balances that may also be impacted include restoration and rehabilitation provisions, retrenchment provisions and deferred or equalisation stripping accounts. The age old question of whether all reserves should be used or whether some or all of the resources should be included for financial reporting purposes has never been adequately resolved. It is our view that there should be no prescriptive answer to this question but judgement of all professionals involved in the process needs to be included. Furthermore, the company needs to be able to support their conclusions with well thought out and appropriate answers. This may not be in line with the approach that certain accounting standard setters may be proposing or taking, and this paper will outline the current status of global requirement and the likely future directions. Whether reserves or resources are utilised, does not change the key requirement that those preparing or using reserve and resource statements need to understand key aspects. For example: geologists/engineers do they know how reserves or resources will be used? have they imparted information on variability of key drivers such as grade or depth or dilution? do they know that major financial/business altering decisions may be made based on the analysis? accountants do they understand where the numbers have been derived from and the assumptions that may have been made in their determination? do they understand the degree of accuracy (or inaccuracy) that may exist particularly with resources)? do they understand the history of resource reconciliations and what it may mean for the future? directors do they understand the processes undertaken by the company to prepare the financial report and the interaction between the geologists/engineers and accountants? do they understand the potential sensitivity of results to the input variables? Financial reporting is extremely reliant on the use of the reserves and resources, however, the geologists/engineers, accountants and directors do not always understand the interactions between themselves which may lead to misleading public reporting. More education and communication between various parties is needed.

Jan 1, 2002

By J. W. C. Wong, S. D. Miller, J. J. Jeffery

Pre-mining identification of acid forming mine and waste materials is of concern to the mining industry because of the potential for the generation of acid mine drainage, acid rock drainage, and soil acidity problems. Accurate identification of acid forming material is essential for developing appropriate waste management strategies to reduce environmental problems related to acid generation from sulphide containing wastes. The acid-base accounting procedure, in its various forms , is commonly used for pre-mining screening of mine and mine waste materials. The procedure is generally effective when used and applied correctly but is prone to incorrect interpretation of results which can have significant financial and environmental implications. This paper examines the acid-base accounting Procedure and the possibility of misuse of this method with special emphasis on the sampling method, the sulphide forms, the acid neutralization capacity, and the interpretation of results. Data from numerous coal, base metal, and gold mining operations are used to illustrate the application of the acid-base account. The data base indicates that overall, approximately 1/3 of all waste generated by mining and mineral processing is potentially acid forming indicating the need for correct identification and management. Problems associated with simple application of 'absolute' acid-base criteria for classifying acid forming material are highlighted and the need for developing site specific or 'relative' criteria is discussed and illustrated by case study.

Jan 1, 1991

By John J. Ginty

The objective of the work reported herein was to evaluate state-of-the-art repeaters used in wireless communications to determine their suitability for use in extending the range of portable and mobile communications in underground mine applications. The scope of the work included wireless repeaters in the frequency range from LF (500 kilohertz) up to the one giga-hertz range. These repeaters included not only single-channel repeaters, that is F1/F1 repeaters for short range simplex party line communications, but in addition, F1/F2 type repeaters currently commercially available in the HF, VHF and UHF bands.

Jan 1, 1975

By J. J. Forbes

Since 1910 the Bureau of Mines has given training in the care and use of oxygen breathing apparatus under conditions that may exist during mine fires and after mine explosions. In 1929 the Bureau supplemented this instruction by initiating a course in advanced mine rescue training to prepare mine officials and others to organize men for mine rescue and recovery operations. The course of instruction has been developed and expanded since its inception to keep abreast with new ideas, methods, and equipment. Four miners' circulars were issued to be used in the training course. The first of this series (Miners' Circular 33) deals with mine gases and the various methods of detecting them; the second (Miners' Circular 34) gives instructions for sampling and analyzing mine atmospheres; the third (this circular) describes methods and equipment for protection against mine gases; and the fourth (Miners' Circular 36) explains procedures in sealing and unsealing mine fires and in conducting recovery operations, These circulars have been revised from time to time to keep them up to date.

Jan 1, 1954

By M. Hertzberg

The Bureau of Mines measured the energy requirements for the spark ig-nition in air of Pittsburgh seam bituminous coal dust, lycopodium spores, and polyethylene powder with a 1.2-L furnace and 8-L and 20-L chambers. Thermal autoignition temperatures of the same dusts were mea-sured in the 1.2-L furnace. Electrical ignition requirements are given in terms of both effective spark gap energies, [ ] and stored circuit energies, 1/2 CE2. The measured order of electrical ignitability for the three dusts is consistent with the data of other researchers; however, the absolute values are systematically higher, probably because of higher flow and turbulence levels in the chambers used and lower electrical efficiency in the circuit used here. The temperature dependence of the lean limit of flammability for lyco-podium was measured wi th the 1.2-L sys tem, and those measurements con--firm the applicability of the modified Burgess-Wheeler law to a dust. Due to experimental complexities, the minimum ignition energies for dusts may not reflect intrinsic flammability behavior. However, some valuable information may be obtained from the relative ignition energies of various dusts at ambient and elevated temperatures. In addition, the concept of minimum electrical ignition energies for homogeneous gas mixtures is reevaluated theoretically.

Jan 1, 1985

By J. H. East, D. Harrington

"INTRODUCTION Mining at its best is not a clean occupation for either surface or underground employees; and this applies alike to coal, metal, and non-metallic mines. The employees are handling minerals that have been blasted, or broken by some means and are subjected to mineral dust, whether it is coal, quartz, or talc. The employees usually wear clothes specifically adapted to the work in which they are engaged, and frequently these clothes are not suitable for use away from the mine. Many mines are wet, and employees must wear rubber boots to remain at least partly dry, and even on relatively dry mines, some parts of the mines usually have water falling from overhead, there are accumulations of water, or the floor or other surfaces are wet or muddy, Some mines are dusty, and the air-borne dust quickly settles on the clothes and body of the miner, especially, when he is working in confined areas, or in places that are hot, humid, or poorly ventilated. Most occupations around a coal tipple, anthracite breaker, or a mill at a metal or nonmetallic mine have their own problems of cleanliness as to skin or clothes or both. Mining in any of its phases is inherently dirty work, and the employees dress accordingly while at work.In the early stages of mining it was the custom or workers to wear their dirty clothes home and change there. This necessitated their going home after work in dirty clothes which were usually damp from perspiration or from contact with wet or muddy matelials or surfaces, and, in addition to being inconvenient this was a frequent cause of colds, pneumonia, other pulmonary diseases or, possible skin ailments. Men working in very wet mines found that it was more satisfactory to change into dry clothes in the boiler room at the mine after work and allow their wet clothes to dry overnight. The mining companies later provided the first of the so-called ""dry-houses"" which were heated but had, few, if any, conveniences, such as showers, lockers, or latrines. The miners changed into dry clothes after work, but would not bathe or ""clean up"" until they reached their homes. Later, progressive mining companies provided bathing facilities for the employees, and eventually the present modern wash and change houses were evolved. Unfortunately, many mines, still have no bathing accommodations, and many have only makeshift accommodations."

Dec 1, 1947

By D. Harrington

"FOREWORDVirtually all government agencies undertook many additional responsibilities during the period immediately preceding World War II; these responsibilities increased vastly in importance and scope after the actual declaration of war following the attack on Pearl Harbor. The Bureau of Mines was one of the agencies thus affected, and it was called upon to perform many duties foreign to its normal peacetime activities.The Health and Safety Division of the Bureau of Mines, at that time designated the Health and Safety Branch, was given several important and difficult duties and responsibilities of an unusual nature because of the war while of necessity-continuing its normal functions of assisting the mineral industries in the preservation of life and health and the protection of property, this being of especial importance in wartime because of the pre-eminent importance of having maximum output of essentially all types of mineral products. Some of these additional functions were given to the Health and Safety Division because the organization of the Division, with its field set-up dividing the Nation into districts with competent, experienced personnel in charge of its work, provided the nucleus of personnel and procedure through which rapid and smooth expanded functioning was feasible.In addition to the responsibilities directly attributable to definite war activities, such as the administration of the wartime Federal. Explosives Act and the Mineral Production Security Branch a new branch (then designated division) was formed to investigate coal-mine health and safety problems after the enactment of the Federal Coal-Mine Inspections and Investigations Act, which became a law on May 7, 1941, but which actually began to function actively after the declaration of war in December 1941.The purpose of this publication is to provide a brief historical record of the activities of the Health and Safety Division as a whole and of its individual branches during the war. The detailed record has been filed in the Archives Building, Washington, D. C."

Jan 1, 1949

By G. C. Price

This study traces the development of the bucket-wheel excavator, points out the differences in the German- and American-type wheels, and gives the major design criteria and the advantages and disadvantages of bucket-wheel operations. A computer program, written in FORTRAN IV for use with an IBM 360 computer, simulates the operation of the digging components of a bucket-wheel excavator. By supplying certain mining dimensions, soil characteristics, and machine design specifications, this program will print out a time study of the various components of an operation, power calculations for the operation, and production data. This program, when combined with a truck, belt, or rail program, should be helpful in planning a complete mining system In material suitable for a bucket-wheel excavator operation.

Jan 1, 1973

By R. G. B. Pickering

The purpose of this report is to chronicle the interaction between Anglo Platinum and Sandvik Tamrock during the development and application of Long Hole drilling as a viable, practical method of narrow reef mining. Appendix I identifies the people from Anglo Platinum and Sandvik Tamrock who participated in the project. Experiments in long hole drilling and blasting were conducted in a number of mines during the late 1950s and early 1960s. Some of the advantages envisaged were: ? The face would require no daily examination ? No barring down or immediate face support required ? No sockets to clean ? Only a few well drilled holes rather than large numbers of short blast holes ? Avoidance of poorly-marked holes, inaccurate drilling and improper charging ? Better supervision and better face advance. Holes 50 mm in diameter were drilled parallel to the stope face by pneumatic rock drills from advance strike gullies. Holes were charged with amon gelignite cartridges. All holes were traced with detonating cord to ensure propagation of the explosive along the entire hole length. Rock was blasted onto a rolling scatter pile. A number of reasons have been cited for the failure of this mining method. The two most important were: ? problems in controlling hole deviation which was exacerbated by the fractured ground ? difficulty of charging up holes in fractured ground, due to relative movement of rocks along fracture surfaces over the hole length. The idea of drilling a few long holes parallel to the face rather than a large number of short blast holes perpendicular to the face was an attractive option to mechanize narrow reef mining. This particular project started in 1998. Initial trial The Union Section of Anglo Platinum purchased a Solo H 606 RA long hole drilling rig from Sandvik Tamrock in 1997. In order to evaluate long hole drilling as a basis for face mechanization. The Solo series of drill rig was selected because it combines high drilling performance and good drilling accuracy with high versatility with a compact size. The mining method proposed by a consultant to Anglo Platinum was based on the current trackless mining method practised by Union Section. The trackless mining method is better described as a trackless development and transport method. Reef strike drives were installed approximately 40 metres apart on dip using trackless equipment. Reef was mined using hand-held pneumatic rock drills and scraper winches and the excavation was supported by sticks and crush pillars at the top of the panel. Rock scraped from the panel was loaded by Lad Haul Dumps (LHDs), trammed to an inclined haulage, and loaded into trucks for transport to the surface. It was intended that the Solo would drill from the bottom advance strike drive to the top advance strike drive. Blasted rock would still have to be scraped from the panel. It is also difficult to understand how well the support would have survived. In the initial motivation it was stated that drilling accuracy was of the utmost importance. Previous work by Sandvik Tamrock had shown that, in other parts of the world, 20 metre long holes could be drilled with a deviation not exceeding 100 mm provided that: ? holes were collared with low thrust pressure ? operating percussion pressure was kept low -often not ? exceeding 10 MPa ? drilling was to be with tubes, not rods. In early 1998 initial trials with the Solo H 606 RA were inconclusive; attempts were made to drill 40 metre long holes from one advance strike drive to another. Difficulty was experienced in measuring hole straightness and accuracy, there was no survey of the holes, and no blasting was done to expose hole barrels. A long hole mining system was then defined, with a corresponding face mining system, which led to the design of a test programme for the Solo drilling rig. Earlier experience at Telfer The proposed face mining system was based on a mining method that is practised at Telfer Gold Mine in Western Australia. Telfer has a series of domed reefs that dip at angles of less than 20° to more than 40°. The ore bodies are all thin, with widths from 0.6 metres to 0.8 metres. Figure 1 shows the face layout. Experience at Telfer indicated the following: ? The spacing and size of the dip pillars should be based on the rock mechanics of Union Section ? The length of the face is determined by the ability to correctly position the blast holes. Positioning of blast holes is a function of hole straightness and hole direction. Blast holes in Telfer were drilled 64 mm diameter with retrac bits from Sandvik. Extension steel was T38 by 1.8 metre lengths. A guide rod was fitted immediately behind the bit. To achieve greater accuracy' operators drill at relatively low percussion and thrust pressures. Results show that very good accuracy is achieved in 20 metre stopes and only fair accuracy in longer stopes. In 34 metre long stopes 10-15% of the holes are not sufficiently accurately positioned and have to be re-drilled. All blast holes are

Jan 1, 2006

"Exploitation of an ore deposit can be optimized by adapting the beneficiation processes to the properties of individual ore blocks. This can involve switching in and out certain treatment steps, or setting their controlling parameters. Optimizing this set of decisions requires the full conditional distribution of all relevant physical parameters and chemical attributes of the feed, including concentration of value elements and abundance of penalty elements. As a first step towards adaptive processing, the mapping of adaptive decisions is explored based on the composition, in value and penalty elements, of the selective mining units.Conditional distributions at block support are derived from cokriging and geostatistical simulation of log-ratios. A one-to-one log-ratio transformation is applied to the data, followed by modelling via classical multivariate geostatistical tools, and subsequent back-transforming of predictions and simulations. Back-transformed point-support simulations can then be averaged to obtain block averages that are fed into the process chain model.The approach is illustrated with a ‘toy’ example where a fourcomponent system (a value element, two penalty elements, and some liberable material) is beneficiated through a chain of technical processes. The results show that a gain function based on full distributions outperforms the more traditional approach of using unbiased estimates."

Jan 1, 2015

By D. H. Gurinsky, D. G. Schweitzer

The empirical equilibrium constantsd the heat of reaction for the reduction have been determined from 300° to 500°C. The mechanisms of the oxidation of uranium and magnesium from dilute bismuth solutions have been investigated. The kinetics of some of the reactions were affected by air adsorbed on the uranium oxides. THE Liquid Metal Fuel Reactor studied at Brook-haven National Laboratory uses a solution of uranium in bismuth as the fuel. Corrosion and stability problems require that the fuel solution contain corrosion inhibitors and deoxidants. Of the additives tested, magnesium has been found to be the best deoxidant and zirconium the best corrosion inhibitor in bismuth. Some experiments1 indicate that magnesium may play a secondary role in increasing the effectiveness of zirconium in inhibiting corrosion. The work reported here was intended to determine the relative concentrations of Mg and U required to prevent oxidation of the uranium fuel in the event of an air leak. In addition, an attempt was made to identify some of the mechanisms of the oxidation and reduction reactions occurring in the liquid bismuth solutions. EXPERIMENTAL Apparatus and Procedure—The equipment shown in Fig. 1 was designed so that the reaction kinetics could be studied as functions of temperature, melt composition, pressure, and flow rate. At the start of a run, the 10-liter bell jar (F) is removed by opening the bottom Dresser fitting (L), and the bismuth and additives are placed in a pyrex crystallizing dish (I). The bell jar is replaced, the system is evacuated to 10-5 to 10-6 mm Hg and then the heater (J) is turned on. When the selected temperature is reached, the oxidizing gas is admitted to the system to the desired pressure as read on the manometer (D). Gas is introduced through the slide tube (Q) which has a pyrex frit (R) sealed to its bottom. Stirring is accomplished by immersing the end of the tube in the melt. To maintain a constant pressure under flow the input and evacuation rates must be equalized. To obtain this condition stopcock (C) is closed and flowmeters (B) are matched. The reaction is "stopped" by closing the inlet flowmeter and quickly evacuating the system. To obtain a liquid metal sample, the system is evacuated with the sampler positioned near the surface of the liquid. The sampler, Fig. 2, is then immersed until its thermocouple reading matches thermocouple (G) Fig. 1. The system is then pressurized with helium which forces the solution through the frit. Twenty to 30 min elapsed between the time the system was evacuated and sampled. During evacuation and pressurization of the system, the temperature variations did not exceed ± 5°C. While bubbling occurred the temperature remained constant to within 1/2 oC. The volume of the equipment was determined by adding a known volume of air at atmospheric pressure to the evacuated system and noting the resulting pressure.

Jan 1, 1962

By David M. R. Stone

Underground mining in the gold industry is gaining popularity in Nevada, and with it the use of cemented rockfill is becoming mainstream. Even with today?s high metal prices, however, mining companies are very sensitive to the margins they realize, and are constantly looking for ways to reduce costs or improve efficiencies. Given that the backfill is one of the largest cost centers in underground mining, mines are constantly under pressure to reduce backfill costs. This paper will present an overview of the factors that impact cemented rockfill quality in Nevada mines based on the authors many years of consulting experience. Cemented rockfill quality can be linked directly to binder consumption, hence programs aimed at improving quality generally result in lower binder costs, better performance in the fill (hence less dilution), and improved safety. The paper will conclude with the key elements of a comprehensive program of backfill quality assessments and backfill QA programs. Comparative laboratory and minesite data from a number of operating and proposed mines will be presented.

May 1, 2007