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The relationships between backfill-transportation parameters (solids concentration, velocity, and pipe diameter) and the wear rate of backfill-transportation pipelines is well understood. However, the degree of wear experienced by a pipeline depends not only on the transportation parameters, but also on the characteristics of the solids making up the backfill, i.e. the particle-size distribution, hardness, shape, and sharpness of the particles. Therefore, unless data corresponding to the specific wear rate of the solids are available, the determination of the wear rate for pipes transporting an uncharacterized backfill is largely guesswork. This paper describes an evaluation of particle characteristics with special reference to particle sharpness so that pipe wear rates can be correlated with solids of different size distributions and sharpnesses.

Jan 1, 1993

Open pit mines in the Yilgam Craton have unique hydrogeological characteristics resulting from a combination of geology, mineralisation and the complex and extended development of the regolith. The principal features of this geological relationship are:ò deep and complex multi-stage development of the weathering profile; ò steeply dipping rock layering;ò supergene enrichment; andò mining across the regolith/rock interface.These features result in large changes in permeability horizontally across rock layers; vertically through the weathering profile and along-strike in association with mineralisation and the mineralised Structure.

Jan 1, 1993

Pictured on these pages are the seven RMCMI Scholarship Award Winners for the 1992-93 year followed by a brief profile. All winners were present as guests of the Institute at the June convention in Beaver Creek, Colorado to receive recognition at the Institute Awards Luncheon Monday, June 28. 1993. Each state vice president served as the host for the collegiate winner. In addition to receiving a plaque from the Scholarship Chairman, Alan Czarnowsky, each winner receives $750 tuition credit for the coming academic year. As this is a continuing award, the winners from the previous year will receive another $750 for tuition credit in their senior year if they have maintained good academic standing and are recommended by their university. A resident from each of the eight RMCMI member states is selected from among Board approved institutions. Criteria for these awards to be made in the spring annually is (1) That the award be made to a sophomore student and used as tuition during the junior year. (2) That the recipient be both a U.S. citizen and a resident of the member state. (3) That the recipient have good academic standing, be pursing a degree in a mining related field and have an expressed interest in Western coal as a possible career path. The scholarship program includes curricula other than those in the mining departments, but in engineering disciplines, such as geology, mineral processing and metallurgy. Contributions to this worthy project are tax deductible to each individual RMCMI member or his firm. Through annual donations of $100 or more, the Patrons of the Institute fund the scholarship pro- gram and the various vice presidents contribute the travel expenses to convention for these outstanding young collegiates. Donations to this worthwhile program may be made payable to RMCMI Scholarship and mailed to the RMCMI Office, 3000 Youngfield Street, Suite 324, Lakewood, CO 80215. Profiles of the 1993 Scholarship Winners follow. [ ] ARIZONA WINNER Kevin Shirley University of Arizona Tucson, Arizona A member of the Student Chapter - Society of Mining Engineers, Mr. Shirley also belongs to the Campus Crusade for Christ organization. He enjoys baseball, basketball and football. He states, "Miners are meeting the demand of the public by providing energy fuels and minerals to support the standard of living we enjoy. It is sad to see people out of work in this country, but the third world is largely undeveloped, and many jobs are moving abroad." 'I consider winning the RMCMI scholar- ship a great motivator; your belief in me will help me become my best." [ ] COLORADO WINNER Derek Rawson Colorado School of Mines Golden, Colorado "1 have been enthusiastic about the mining industry since I lived in Divide, Colorado and spent time exploring the old mine sites." Derek says. "President Clinton may hit the mineral industry with many reforms, but I believe self sufficiency is important ... we need to produce here in the U.S. what we consume." Mr. Rawson is involved with intramural sports and varsity track. He is a member of the Society for Mining, and Exploration, Inc.; Colorado School of Mines Caving Club; Colorado School of Mines Shooting Club; and Alpha Tau Omega Leadership Fraternity.

Jan 1, 1993

During foundry sand reclamation process development, molds formed from reclaimed chromite sand showed a rapid decline in tensile strength during thermal cycling tests. Because this characteristic could limit reuse of chromite sand in the foundry, the sand was examined in detail. Scanning electron microscopy, x-ray mapping, magnetic susceptibility, and x-ray diffraction were utilized to evaluate processed chromite sand. It was found that process variables such as binder composition, reclamation temperature, and processing method had a significant effect on the chromite sand particle surface. X-ray diffraction indicated a crystallographic change in the processed sands. Magnetic susceptibility also increased after processing. Diffusion of iron to the particle surface and increased surface roughness were identified as potential causes of the decreased tensile strength in the molds.

Jan 1, 1993

After the Loma Prieta Earthquake, which caused major damage to viaducts in the Bay Area, the California Department of Transportation set up a test programme for foundation piles. Funderingstechnieken Verstraeten B.V., beter known as Fundex, was approached, since one of the piling systems of Fundex, named Tubex, is extremely suitable in areas sensitive to earthquakes and we were very much interested to prove the capabilities of this piling system. Equipment For the installation of Tubex and Tubex grout-injection piles special piling equipment is required. Since our company is not only a contractor, but also a designer and manufacturer of piling equipment, all special equipment for our range of foundation techniques is designed and built by our own piling equipment department. For the installation of both Tubex piles and Tubex grout-injection piles for the Caltrans test programme, the following pieces of equipment were selected: a) Fundex F12 piling rig b) Drill table c) Hydraulic powerpack d) Grout mixing unit and high pressure pump

Jan 1, 1993

By Robertson GE, McLaughlin JD

An extensive laboratory campaign was conducted to find a suitable water soluble collector to replace diphenylguanidine (DPG) in the matte separation process. The examination of the collectors was done by measuring the rate of flotation and the best candidate collectors were selected on the basis of the rate parameters. As a result of this search mercaptobenzothiazole (MBT) was selected for a plant trial. A plant trial of two weeks duration confirmed that MBT will produce separations at least as good as those obtained with DPG.

Jan 1, 1993

The winning and upgrading of mineral raw materials necessarily includes size reduction, which serves the liberation and production of marketable products from highly valuable and bulk materials. For crushing, the following factors can be duly accounted for depending on material type and the selection of the suitable machine: ò producing a particular size distribution, ò producing a particular grain shape, ò selective comminution, ò gentle comminution, and ò producing a size range required by a specific process and/or for a specific product.

Jan 1, 1993

By Thomas J. Ferree

"There has been a major evolution of mineral processing technology in the past decade. The evolution has been driven by recognition of broad environmental changes which have impacted various areas of the world. Numerous government regulations have required many mining and mineral processing organizations to introduce changes to reduce the undesirable effects on the environment; many mining companies have voluntarily introduced new technologies and practices which surpass the limits imposed by the regulations. Surprisingly, some of the 'new' technologies are modifications of concepts developed decades earlier. Gravity separation technology is in this category.Mineral Deposits Limited, an Australian company, has been a world leader in the development of mining concepts, reclamation practices and equipment technology that is environmentally suited to today's requirements. This paper relates to equipment used for gravity concentration and electrostatic separation systems, including Reichert cones, spirals, and electrostatic separators. The basic devices and technologies were developed more than forty-five years ago, but use of the systems was quite limited until environmental and conservation practices were recognized and introduced. Spiral concentrators, for example, were patented in the mid-l940s by I.B. Humphreys in Denver , Colorado. The two types of spirals marketed (the Model 24A for minerals and the Model 24C for coal) remained essentially unchanged until expiration of the patents. During this early period most spirals were used in iron-ore wash plants on the Mesabi Range to recover fine iron which previously had been discarded. About the same time sand mining plants in Florida incorporated spirals to recover titanium minerals and zircon from lowgrade beach sands. The Labrador Trough opened new opportunities for spirals when hard-rock iron-ore deposits were developed; approximately 10 000 Model 24A Humphreys spirals were installed between 1958 and 1966. About 5000 spirals of this model are still operating in the same capacity, in spite of the fact that extensive improvements have since been made in gravity separation technology."

Jan 1, 1993

By S. Paul Singh

The implications of blast damage are harmful in both economic and physical sense. To understand the mysterious nature of blast damage assessment and prediction, field work was done by driving an experimental tunnel in the bench of a quartzite quarry. On the basis of the blast vibration monitoring records, a model was developed to predict the PPV at different distances from a blasthole. Critical particle velocity for damage and the output of the prediction model were used to delineate the extent of damage for different explosives. The predictory model was tested by designing a special blast and the burdens for the back holes have been recommended. The relationship between the critical particle velocity for "Fall Off' and the critical particle velocity for damage has been established. The existing criteria for blast damage have also been renewed in this paper.

Jan 1, 1993

By R. R. Oder

Reported are weight, particle size, gross chemistry and magnetism measurements for lithic, mineral and fused soil components separated from five lunar soils using dry, open-gradient, magnetic separation. Pure diamagnetic anorthite, a feedstock for the electrochemical separation of oxygen and metals, has been separated from anorthistic highland soils. In addition, paramagnetic ilmenite has been separated from high-titanium, basaltic mare soils. Ilmenite, a feedstock for oxygen preparation by hydrogen reduction, may also serve as a source of He3 for use in fusion power generation. Agglutinates (vesicular, glassy components containing metallic iron) have been separated from all of the soils. Iron and refractories can be used for space construction. Metallic iron is easily detected in lunar soils by magnetic susceptibility measurements. Based on the exploratory laboratory results, conceptualizations of innovative magnets for processing lunar soils are presented.

Jan 1, 1993

By Charles D. Litton, Ronald S. Conti

This report describes the results of research conducted in the Bureau of Mines Experimental Mine at Lake Lynn Laboratory to determine the effects of air velocity, sensor spacing, and stratification of CO levels on the detection of slowly-developing coal/conveyor belt fires. In general, the time to detect a developing fire is calculated assuming an average CO level that has mixed completely with the ventilated airflow. The data indicate that CO sensors placed near the roof of an entry take advantage of buoyant- induced stratification of combustion products, resulting in earlier detection of developing fires. Even during the low-temperature, smoldering stage of a fire, the combustion products will tend to stratify near the roof, and once flaming occurs, the degree of stratification increases markedly. As one would expect, at higher air velocities, the degree of stratification is less than at lower air velocities, although still significant, especially during the flaming stages of the fire

Jan 1, 1993

By Reeves I. And Farquhar J, Pearce S

The irregular shape of the Rosebery orebody, coupled with the inconsistencies in grade over short strike lengths, has meant stoping blocks have had to be small to combat dilution and stability problems. In the past, each lens was divided into regular block sizes and developed up to five years before production commenced. There were two major drawbacks to this practice; firstly, existing development deteriorated over time therefore requiring rehabilitation prior to production. Secondly, the pre-determined blocks could not be easily changed to incorporate changes in mining technology or economic circumstances. Bearing these problems in mind, it was evident that any new lens development had to be designed to allow maximum flexibility. The lens being currently developed is J lens. It represents approximately 50 per cent of the current reserves tonnes, and 65 per cent of the zinc metal. Its importance to the mine's future cannot be over emphasised. At its core the lens is up to 25 m thick at grades of over 30 per cent zinc. The practice of dividing the orebody into levels and sublevels, with consequent crowns was no longer acceptable because of restrictions in stope design and potential loss of ore. To assist in the development planning of J lens, a geostatistical block model was applied in long section to graphically represent the lens. Areas of high zinc concentration, as well as zones of uneconomic material were identified by using the model. This has meant that the development could he targeted, enabling stope delineation to occur in the lens without significant ore loss. Because of limited development resources, and the need to bring J lens on-line in the near future, the development strategy has had to focus on 'just-in-time' principles, rather than accessing the whole lens from bottom, and progressing upwards. Tight development schedules have required individual stoping block to be developed on such factors as grade and available tonnes rather than as a vertical sequence.

Jan 1, 1993

By E. A. Lauha

The Goldstrike Mine is in Eureka County, Nevada, U.S.A., approximately 23 miles northwest of the town of Carlin. The mine is at the north end of the Tuscarora Spur of the Tuscarora Mountains at elevations of 5,300 feet to 5,950 feet. It is part of the Bluestar/Goldstrike sub-district of the Carlin Trend, a northwest alignment of sediment hosted, disseminated gold deposits. The Carlin Trend includes over 15 major gold deposits with production, reserves and geological resources of approximately 65 million ounces of gold (Figure 1). In the Bluestar/Goldstrike sub-district, there are seven major deposits: Betze, Lower Post, Post, Genesis, Bluestar, Purple Vein and Deep Star, plus numerous smaller deposits (Figure 2). Production, reserves and resources for the sub-district are approximately 40 million ounces. Betze and Purple Vein are located on property controlled by Barrick Goldstrike Mines and Bluestar and Genesis on Newmont Gold property. Post, Lower Post and Deep Star occur both on Barrick and Newmont property.

Jan 1, 1993

By Suresh K. Bhatt

A mathematically simulated modeling technique is used in this U.S. Bureau of Mines report to represent a hypothetical mining operation with existing mining technology and prevalent mining costs. Mining scenarios were prepared and evaluated for potential benefits and costs available through computer-assisted mining. Base criteria, parameters, and methodology are described.

Jan 1, 1993

By Talaat A. B. Lawendy, Guerry H. McClellan

Batch laboratory-scale flotation tests were conducted on some carbonate-containing sedimentary phosphate ores to obtain concentrates suitable for chemical processing. The phosphate samples tested contained both calcite and dolomite. The calcitic phosphate ore was from Israel and the dolomitic ores were from China, India, Egypt, and Pakistan. The phosphate sample from Pakistan also contained a significant amount of silica. Several flotation techniques that have been proposed for upgrading carbonate -containing phosphate ores and concentrates were tested. Two processes gave better results compared with the other processes tested: a modified IMC anionic process and a. phosphoric acid depression process. At the best flotation conditions tested, phosphate concentrates assaying 32.5%-36.5% P205, 44.0%-51.0% CaO, and 0.6%-1.0% MgO were obtained at 69%-76% overall P205 recoveries from run-of-mine (ROM) ores containing 16.0%-25.0% P205, 40.0%-52.0% CaO, and 1.0%-11.6% MgO.

Jan 1, 1993

By G. Schriever, H. Thiel, E. J. Foell

A long-term, large-scale, disturbance-recolonization experiment with relevance to the environmental effects of deep seabed mining is described. The study is funded by the German government and was launched in the abyssal eastern tropical South Pacific Ocean in February-March, 1989. After obtaining pre-impact baseline environmental data, a 10.8 km2 (4.2 sq miles) circular area of seafloor was disturbed using a specially designed "plow-harrow" device. An initial post-impact sampling series was carried out immediately after disturbance followed by a second post-impact sampling series six months after the disturbance. Plans call for repeated visits to the site at two year intervals to monitor the anticipated slow recolonization process until the area is inhabited by a new, stabilized community.

Jan 1, 1993

By Roger E. Melley

Since startup of the Syncrude Canada Ltd. (SCL) oil sands facility in northern Alberta 15 years ago, numerous improvements have been made in the ore conveying system and equipment. The unique nature of the material conveyed coupled with the wide range of environmental conditions encountered results in a number of unparalleled challenges. Most of the improvements have been brought about through the use of detailed field evaluation. Numerous publications are available that detail the various aspects of conveyor technology, and a significant list of papers are presented each year adding to the knowledge in this field. In the area of power formulae in the mid- 1970s, there were two major sources for use in the design of the SCL conveyors: the Conveyor Equipment Manufactures Association Handbook, 1988, and DIN Specifications 22101: Belt Conveyors for Bulk Materials, 1982. These sources were supplemented by the knowledge of the belt and conveyor equipment vendors and from the general literature. The SCL design was based on the CEMA formula. However, it was accepted that this empirical approach had been developed for use with more conventional materials in more reasonable climates. To accommodate

Jan 1, 1993

By Richard D. Hagni

The techniques of reflected light microscopy and cathodoluminescence microscopy are uniquely suited to the study of the products from many important industrial problems. Ref1 ected 1 ight microscopy provides the means to rapidly identify the mineralogy of an industrial sample, determine the abundance of each phase, and examine the mineral intergrowths or textures. Cathodoluminescence microscopy is a relatively new instrument that provides the means to cause many minerals to cathodoluminescence under the microscopy. The cathodoluminescence of a mineral allows it to be readily distinguished from other phases that differ in cathodoluminescence but are similar in optical properties. Cathodoluminescence microscopy is especially useful to detect cathodoluminescence minerals that are present in only small quantities. Reflected 1ight microscopy and cathodoluminescence microscopy have been successfully applied in studies of beneficiation products, prediction of beneficiation and leaching problems, phosphatic iron ores and mill products, pyrometallurgical products, roasted refractory gold-bearing sulfides, ceramic build-ups, electric arc furnace and smelter dusts, and other industrial products.

Jan 1, 1993

By Feng Gao

A general unsteady- state model, based on a cracked substrate, has been developed to account for reaction and diffusion within porous substrate during oxidation of Carbon Fiber Reinforced Carbon matrix (CIC) composites. The effects of several parameters, such as diffusion and reaction rate ratio, oxygen concentration, and composite density, on oxidation process are explored. Also, theoretical results for a set of parameter values of the CIC composites are compared with experimental data. It shows that the model predicted values agreed well with the experimental data in weight loss. Based on this model, quantitative predictions of oxidation of a composite with cracked substrate can be made.

Jan 1, 1993

By S. W. Ip

Over the years, the importance of surface and interfacial phenomena has been neglected by the copper-nickel industry. As a result, little data on the surface and interfacial tension of the Ni matte and slag system are available in the literature. In view of the scarcity of information in this area, the surface tensions of the Ni-Fe-S system together with the Ni-Fe-S and fayalite type slag system were measured using the sessile drop technique. Drop images were obtained by X-ray radiography. For the Ni-Fe-S system, the results showed that the surface tension of the matte increases with matte grade. The surface tension behavior with changing matte grade showed a slight negative deviation from ideality. This indicated that FeS is slightly surface active in the nickel matte system. Results also indicated that small increase in sulphur content in the matte can decrease the surface tension quite significantly. The measured surface tension of the Ni-Cu-S system showed a linear relationship with the Cu2S content in the matte. The surface tension decreased with Cu2S content. Interfacial tension measurements showed a similar trend. That is, interfacial tension increased with increasing matte grade. The presence of MgO (-1.5%) and A12O3 (-6%) in the slag does not affect the interfacial tension value. Effects of matte surface tension on phenomena such as entrainment of matte in slag and infiltration of matte into refractory pores are discussed. The calculated flotation coefficients indicated that flotation of nickel mattes cannot be avoided by changing the matte grade. Filming of matte on bubbles can occur below a matte grade of about 19% Ni3S2. As for infiltration, refractory bricks containing high Cr2O3 will be easily wetted by matte regardless of matte grade. Therefore, bricks containing high Cr2O3 can easily be infiltrated by liquid matte.

Jan 1, 1993