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This paper presents an analysis of the production data for the period 1861 - 1953 from hydrothermal gold-silver deposits of the Hauraki Goldfield. To directly compare the metal content of the deposits a figure of ounces of gold equivalents (oz gold equivalent) is calculated from the value of the gold-silver bullion produced from each deposit. Frequency distributions for ore tonnage and oz gold equiv. appear to be lognormal and show a high proportion of very small deposits, with 90 per cent less than 100 000 tonnes. The deposits when plotted in order of size fall roughly on a smooth curve which suggests that the size distribution is not random. A large proportion (68 per cent) of the total gold-silver extracted from the Hauraki district was contained in the largest deposit û Waihi. A technique used for predicting undiscovered mineral resources is ZipfÆs law, which relates the size of an item to its rank order. The figures for ounce gold equivalents from the major Hauraki deposits fit ZipfÆs law remarkably well. Taking Waihi at 6.8 million oz gold equivalent as the rank one deposit, Thames is number five and Karangahake number seven. A Zipf plot indicates that down to rank 100 (68 000 oz gold equivalent) only 28 per cent of the total gold-silver resource in the Hauraki Goldfield has been extracted. A further 72 per cent or 25.4 million oz gold equivalent, including the deposits of rank 2, 3, 4, 6, 8, 9 and 10, are undiscovered. However, since some deposits will be deeply buried under younger rocks and others will be under the sea only a proportion of the total resource will be discoverable.

Jan 1, 1981

Virtual reality (VR) simulators represent a powerful tool for training humans to perform tasks which are otherwise expensive or dangerous to duplicate in the real world. The idea is not new. Flight simulators have been used for decades to train pilots for both commercial and military aviation. These systems have advanced to a point that they are integral to both the design and the operation of modern aircraft (Adams, Klowden and Hannaford, 2001; Mastaglio and Callahan, 1995). This technology has been successfully extended and utilised in the mining industry in a range of successful applications (Bise, 1997; Denby and Schofield, 1999a; Schofield, 2005; Henning et al, 2002; Kaiser, Vasak and Suorineni, 2005). There are a number of lessons that can be learned from other industries that have successfully utilised virtual technology for a number of years. Specific rules of thumb regarding the specification, development, application and operation of these simulators can be garnered from other industrial training systems and examined in a minerals industry context (Tromp and Schofield, 2004; Schofield, 2006). This paper intends to discuss some of these generic rules in the context of a number of recently developed virtual reality mining applications.

Jan 1, 2008

Higher commodity prices and environmental considerations will make selective narrow-vein mining more attractive in future. Unfortunately, hand-held airleg (jackleg) mining is a mature technology that has safety and productivity limitations. Despite decades of attempted innovation, no obvious successor to airleg mining has emerged. A review of some of the possible technologies is followed by a speculative description of the mine of the future, intended to stimulate thinking and discussion during the conference.

Jan 1, 2008

By Daniel R. Shawe

Epigenetic ore deposits in Nevada and Utah occur in clusters or belts in a variety of tectonic settings. Many are concentrated in the western half of Nevada in a region containing numerous, relatively large intrusive bodies. Throughout Nevada and Utah, they tend to be clustered in elongate zones or belts. Some of these belts are well defined by the distribution of mineral deposits, patterns of igneous rocks, alinements of faults, and aeromagnetic anomalies, whereas others are equivocal. The Pioche belt in eastern Nevada and western Utah, the Eureka belt in central Nevada, and the Manhattan belt in western Nevada exemplify the general characteristics of these belts, the close relation of some belts to geologic structure, and the lack of a clear correspondence in other belts. Some of these belts are characterized by alined or en echelon faults that disrupt the north-trending Basin ranges, by belts of Cretaceous and Tertiary granitoid and porphyry intrusive rocks near which the ore deposits occur, and by alined magnetic anomalies generally related to the Cretaceous and Tertiary intrusive rocks. All the mineral belts have produced precious and base metals and tungsten; the Manhattan belt in addition has produced magnesite and brucite; and the Pioche belt, uranium, fluorspar, and alunite. The belts in Nevada and Utah may be related to a variety of factors, such as zones of structural weakness in Precambrian rocks, transverse zones of lateral faulting, localized areas of igneous activity, or a combination of these and other factors. Specific types of ore deposits in Nevada and Utah seem related compositionally to the intrusive bodies with which they are associated. Iron deposits, for example, are associated with mafic intrusive rocks such as diorite or gabbro, whereas copper deposits generally and tungsten deposits almost exclusively are associated with granitic intrusive rocks such as quartz monzonltc and granodiorite.

Jan 1, 1976

By R. Schmidt

The computational fluid dynamics (CFD) technique was used to analyze and optimize the design of the dynamic air classifier integral to Raymond® Bowl Mills. Flow patterns and particle behaviors were modeled in the RB Bowl Mill equipped with various classifier designs. These CFD simulations resulted in the development of a hybrid turbine classifier that has now been field-tested, yielding significant improvements to both mill throughput and product size distribution. This paper demonstrates the viability of CFD as a tool for air classifier design and as a technique that can be extrapolated for use with other pulverizer and classifier arrangements.

Jan 1, 2004

By T. C. Page

The Yarnell gold depoSit, located in the Weaver mining district of Yavapai County, Arizona is found within a structurally controlled, hydrothermally altered zone that occurs within a 1700 Ma granodioritic intrusive. Both potassic and sericitically altered rock that occur around and above the low-angle northeast striking Yarnell fault are known to host economic gold mineralization; a wider envelope of weakly-propylitic alterred rock also occurs in this area. During mineralization, strong sericitization accompanied several stages of quartz ± adularia veining, stockwork formation, and localized silicification and potassic replacement, in association with deposition of specularite, pyrite (now oxidized), and gold. The footwall of the fault is also sericitically altered but poorly mineralized. Mineralization along the Yarnell fault continues both northeast and southwest from the main deposit although the thickness of the zone and associated alteration envelope diminish away from the orebody. A sample of undeformed illite taken from the Yarnell fault zone was K/Ar dated at 69 ± 1.6 Ma; this date reflects a minimum age for both mineralization and latest movement on the fault. Gold mineralization is accompanied by modest increases in Ag, As, Cu, and Mo content. Both CO2-and H20-rich fluid inclusions were studied and suggest mesothermal pressures and temperatures of formation for the deposit.

Jan 1, 1992

By Thomas M. Barczak

The era of the shield-supported longwall face began in the United States a little over 25 years ago. The most fundamental development of the shield in the past 25 years has been an increase in size and capacity and a progression toward two-legged designs in favor over four-legged shields. Is the “bigger-the-better” design philosophy justified? The advantage of the two-legged design is largely attributed to its active horizontal force caused by the forward orientation of the leg cylinders. How do we know this? You might be surprised to learn that shield loading data may suggest otherwise. In addition, what about setting pressures? Should they be set as high as possible? Some people have advocated that setting pressures should equal the yield pressure. Does this make any sense? Is yielding a good or bad thing? These are some questions still worthy of investigation that are addressed in this paper. The first major change in gateroad support was the use of cable bolts to replace conventional wood cribbing particularly in Western mines. Standing support changed very little until the mid-1990s, when Strata Products1 introduced the Hercules and Propsetter supports in Eastern mines and Burrell Mining Products introduced the Can support in Western mines. Since then, there has been a dramatic increase in new roof support technologies for longwall gateroad support. Historically, standing support, including shield supports, have been designed based on a simplistic model requiring the support to have sufficient capacity to support the gravity loading of a perceived detached rock mass. This approach ignores the stiffness of the support and the resulting ground deformation that is known to be critical to roof stability. Recently, a new approach based on the ground reaction concept has been promoted by the National Institute for Occupational Safety and Health (NIOSH) to account for the interaction of the support with the rock mass behavior in achieving ground stability. In addition to gateroad support design, this concept has ramifications for shield capacities, setting pressures, and recovery room support design that challenge current practices in these areas. Although longwall mining has matured into the safest and most productive underground mining method used today, traditional concepts of roof support design and practice should still be evaluated and challenged. Ultimately, advancements in the science of ground control are made by recognizing deficiencies in current theories and thinking outside the box.

By G. A. Nyamekye

Two major Inco matte constituents, chalcocite and heazlewoodite, are separated by differential flotation with diphenylguanidine as collector. A new reagent system involving the use of dextrin as a modifying agent which provides better selectivity has been studied for the last three years. Adsorption tests reveal that while dextrin exhibits high affinity towards heazlewoodite, the adsorption isotherm for dextrin on chalcocite shows only weak interactions. Our electrokinetic measurements confirm such conclusions. Since dextrin interaction with solid surfaces seems to be especially strong when such surfaces are covered by hydroxide layer, our electrokinetic measurements are in line with other researchers' findings who postulated that copper hydroxide is not a stable product on the surface of copper sulphides.

Jan 1, 1992

By Joseph Gersic

MINFO has been developed to serve as a frontend for three databases created to store basic minerals information gathered during the minerals resource assessment conducted by U.S. Bureau of Mines(USBM) for the Malheur and Jordan resource areas of southeastern Oregon(MJRA). The primary database is the Minerals Location Inventory (MLI.DBF) which contains of information assembled from field work performed during this project, the USBM Minerals Availability System/Mineral Information Location System(MAS/MILS) database, the Oregon Department of Geology and Mineral lndustries(DOGAMT) Mineral Information Location(MILOC) database, and the U.S. (Geological Survey(USGS) Mineral Resource Database System(MRDS), In addition, assay results are contained in the geochemical database (ELEMENTS.DBF) and modified X-ray diffraction analysis information is contained in the minerals database (MINOR.M.DBF). MINFO includes four types of program modules: ? Enter/Edit Data was developed to allow the addition of new information and to encourage correction of errors by providing a convenient means of entering and editing data and a large degree of automatic checking and filtering of entries. ? ACAD/DBF Link links each site symbol posted on the map in the drawing file to a record in the database. This provides the user with the ability to use a mouse or other pointing device to graphically select a site for viewing and editing. Edits are performed directly in the database file, ? Reports contains 7 formats of data output for creating files for printing, transfer to other database formats, and exporting to other software packages such as spreadsheets and word processing programs. ? Maps includes 5 programs for creating AutoCAD script files which can be used to create maps of selected information in conjunction with AutoCAD. Mineral location mapping files derived from MLI.DBF can be created in 2 formats. Mapping files can be generated from each of the 2 sets of geochemical analyses contained in ELEMENTS.DBF. X-ray diffraction analyses can also be translated into instructions for creating and posting piecharts at sampling sites.

Jan 1, 1994

By J. C. W. M. de Wit

An excavation, within which a tunnel is sunk as a part of the Centraal Station underground station (platform section) of the Noord/Zuidlijn ('North/South Line'), is to be created beneath the Amsterdam Centraal ('Amsterdam Central') station. The section beneath Amsterdam Centraal Station is characterised by the application of a particular technology in the form of, inter alia, the so-called 'sandwich wall'. This is a composite wall consisting of two rows of Tubex piles with a body of jetgrout columns in-between. This wall acts both as an excavation support wall and also provides vertical bearing. The installation of the wall, including both Tubex piles and jetgrout columns, within these specific conditions (limited height, sensitive historical building), within the design requirements set in terms of construction tolerance and water and soil retention, may be regarded as being a pioneering achievement. The environmental constraints are that the trains should continue to run, the inconvenience to passengers should be kept to a minimum and the historic station should not suffer any damage. Because of the complexity of the working conditions, the project is being overseen by a steering group of experts in the specified construction processes. In order to manage the project risks, jet grouting trials were initially carried out, in order to highlight and control execution problems; the practicability of the design is then tested. Work commenced on the sandwich wall in 2003, when the wooden piles were extracted at the locations where the sandwich wall was to be constructed; in 2004, the steel Tubex piles for the southern wall sections were installed. From May 2005, the construction of the sandwich wall got under way; in addition to the described process supervision, an extensive measuring programme was established, so that the process could be adjusted as necessary and the quality of the finished product determined. This applied to both individual columns and for the end product, the sandwich wall. The measurement results were processed for each column, interpreted and the effect on the work still to be conducted was assessed for each future column. Preventative and corrective measures were, if necessary, taken in order to control or counteract the measured defect. In addition to the process-oriented and qualitative measurements, various independent measurement systems at the station building served as a further control in order to prevent damage to the building.

Jan 1, 2006

By L. E. Shiffman

This paper describes the operation of two kerosine flotation plants in Alabama for cleaning —10 mesh bituminous coal. One plant treats washer sludge, the other raw coal. Data on capacity efficiency and capital and operating costs is given. Methods for increasing cell capacity are discussed. IN cleaning coal it has long been recognized that methods which give excellent results for the coarser sizes may give poor or even no cleaning for the finer sizes. Effective cleaning of the fines, therefore, is usually a separate and distinct problem. For many years the problem of fines was considered of relatively minor importance. Now there is growing interest in methods of cleaning the fine sizes of coal because: 1. There are more fines. Increasing mechanization and the adoption of full seam mining methods have resulted in the production of a greater percentage of smaller particles than were produced by hand loading methods. 2. The fines have deteriorated in quality. The same causes that have led to increased quantity have also operated to decrease quality through greater contamination with slate, rock, and other diluents. 3. The fines have become more valuable. When coal was comparatively cheap, loss of the finer sizes was tolerated but, with the rapid increase in the cost of mining coal, it has become imperative that the maximum amount of clean coal be recovered from the mixture of coal and rock delivered to the tipple. 4. In many cases, the fines have become a stream pollution problem. Increasing governmental activity and legislation to prevent stream pollution often have made it necessary to retain the fine material which formerly was permitted to escape with the washer effluent into flowing streams. The Sloss-Sheffield Steel and Iron Co. operates four coal mines, all within a 20-mile radius of Birmingham, Ala., with a total annual production of 1,-250,000 tons of washed coal. Three of these mines are in the Mary Lee seam and one in the Jefferson seam. Although some steam and domestic coals are produced, the major portion of the coal is used to make coke for blast furnace operation. Fine coal is desirable for coking, and all the coal so used by Sloss is crushed to 1/4 in. Therefore, there is no problem of an outlet for even the finest sizes of coal. Since the coal is used for metallurgical purposes, low ash is of greater importance than would be the case if it were used for steam generation or domestic heating. Based on present blast furnace practice at Sloss, it is calculated that each percentage of ash in the coal carries a penalty of $0.22 per ton of coal. Thus there is a considerable margin for operating costs in a fine coal cleaning method that will result in materially lowering the ash content of the cleaned coal. Development of Fine Coal Cleaning Problem In 1942 Sloss reopened its Bessie mine and constructed at this location a new preparation plant to clean 11/4 in. x 0 coal from the Mary Lee seam.

Jan 1, 1951

By L. E. Shiffman

This paper describes the operation of two kerosine flotation plants in Alabama for cleaning —10 mesh bituminous coal. One plant treats washer sludge, the other raw coal. Data on capacity efficiency and capital and operating costs is given. Methods for increasing cell capacity are discussed. IN cleaning coal it has long been recognized that methods which give excellent results for the coarser sizes may give poor or even no cleaning for the finer sizes. Effective cleaning of the fines, therefore, is usually a separate and distinct problem. For many years the problem of fines was considered of relatively minor importance. Now there is growing interest in methods of cleaning the fine sizes of coal because: 1. There are more fines. Increasing mechanization and the adoption of full seam mining methods have resulted in the production of a greater percentage of smaller particles than were produced by hand loading methods. 2. The fines have deteriorated in quality. The same causes that have led to increased quantity have also operated to decrease quality through greater contamination with slate, rock, and other diluents. 3. The fines have become more valuable. When coal was comparatively cheap, loss of the finer sizes was tolerated but, with the rapid increase in the cost of mining coal, it has become imperative that the maximum amount of clean coal be recovered from the mixture of coal and rock delivered to the tipple. 4. In many cases, the fines have become a stream pollution problem. Increasing governmental activity and legislation to prevent stream pollution often have made it necessary to retain the fine material which formerly was permitted to escape with the washer effluent into flowing streams. The Sloss-Sheffield Steel and Iron Co. operates four coal mines, all within a 20-mile radius of Birmingham, Ala., with a total annual production of 1,-250,000 tons of washed coal. Three of these mines are in the Mary Lee seam and one in the Jefferson seam. Although some steam and domestic coals are produced, the major portion of the coal is used to make coke for blast furnace operation. Fine coal is desirable for coking, and all the coal so used by Sloss is crushed to 1/4 in. Therefore, there is no problem of an outlet for even the finest sizes of coal. Since the coal is used for metallurgical purposes, low ash is of greater importance than would be the case if it were used for steam generation or domestic heating. Based on present blast furnace practice at Sloss, it is calculated that each percentage of ash in the coal carries a penalty of $0.22 per ton of coal. Thus there is a considerable margin for operating costs in a fine coal cleaning method that will result in materially lowering the ash content of the cleaned coal. Development of Fine Coal Cleaning Problem In 1942 Sloss reopened its Bessie mine and constructed at this location a new preparation plant to clean 11/4 in. x 0 coal from the Mary Lee seam.

Jan 1, 1951

By A. F. van Weele

In general cast-in place piles will have an irregular pile shape. However, it is possible that these irregularities are so large that they may lead to pile deficiencies. It is very rarely possible to examine the pile foundations visually. Also the performance of a static or dynamic load test on each individual pile is not practical and much too expensive. This is the reason why pile integrity tests have been developed: to reduce the risk of inadequate pile foundations by performing a simple test. Pile integrity tests are non destructive tests which are carried out after a pile has been installed. Over the years a number of techniques have been developed of which the most important techniques are briefly described in this paper. Of all pile integrity testing methods, Sonic Integrity Testing is the most widely used method in western Europe. This method has been developed by TNO some 15 years ago. Since then the method has been improved, largely due to advances in micro-processing. A major improvement was made by the introduction of digital signal processing techniques. This made the Sonic Integrity Testing method more accurate (smaller defects can be detected), faster (more than 200 piles can be tested on a single working-day) and more reliable (the results are easier to interprete). A few cases will be presented which will show the usefulness of the Sonic Integrity Testing method. In one of these cases, a helpful tool for interpretation of the results is explained: the Sonic Integrity Testing Simulation program TNOWAVE. Notwithstanding the fact that Sonic Integrity Testing is a powerful method, it has also some strict limitations. These will be discussed at the end of the paper.

Jan 1, 1987

By Alfredo Valencia-Toledo

This study delves into the satisfaction levels of indigenous communities in Apurimac-Cusco, Peru, concerning mining activities in their region. Our primary objective is to elucidate the interrelationships among observable variables, which are conceived as linear combinations of multiple factors. Employing the statistical methodology of exploratory factor analysis, we aim to pinpoint the pivotal factors influencing the progress of mining activities in Apurimac-Cusco. Through our analysis, we have identified eight key factors that exert a significant impact on mining’s sustainable development in the area. These factors encompass diverse facets, ranging from the support offered by mining company to communities, environmental considerations, education, economic factors, provision of basic services, transportation and communication, support for social organizations, and social-health-related aspects. This research endeavors to provide a comprehensive understanding of the complex dynamics surrounding mining activity satisfaction among the indigenous population, offering a basis for further exploration and policy development.

Feb 17, 2024

Develop rugged, cost-effective fire protection for hydraulic shovels and backhoes. Approach Automatic fire sensing and suppression systems were designed and built for use on hydraulic shovels and backhoes. How It Works A line-type temperature sensor is mounted in the machine's engine and hydraulic pump areas to detect the heat from a fire while it is still small and easy to control. Two systems were tested. In one, the inside of the sensor consists of two conductors separated by a ceramic material whose electrical resistance decreases with increases in temperature. When heated to a predetermined temperature) the control circuit responds to the resistance drop. In the second system, the detection element of the sensor is comprised of a thin metal tube containing a hydrogen charged metal hydride wire. The tube is sealed at one end and is connected to a sensitive pressure switch at the other end. When exposed to the heat from a fire, hydrogen gas released from the metal hydride wire actuates the pressure switch.

Jan 1, 1980

By Norman Lecuyer, Jacque Nantel

"The Chadbourne Project, located within the limits of the town of Noranda, Quebec, will make use of backfill materials to fill the voids left by the mining of stopes and pillars. A series of tests were conducted on different mixtures of slag and pyrrhotite tailings materials to evaluate their properties. The tests are described and some pertinent results are given in the paper.IntroductionThe Chadbourne Project is located in the centre of the Town of Noranda, Quebec, with houses as close as 120 m from the blasting operations. The ore is mined using the vertical crater retreat method. The voids left by mining activities will be filled. A program of pillar recovery will follow.Considering the proximity of houses and the need to recover pillars, the backfill program must be carefully laid out. No subsidence can be tolerated on surface.With these objectives in mind, a test program was undertaken by Nantar Engineering Limited and Queen's University to evaluate the possible ba ckfilling alternatives available to Chadbourne. One of the possibilities retained was the use of a backfill composed of broken slag material from the Horne Smelter and pyrrhotite tailings deposited on the Horne's pond a number of years previously.The back fill used at the Horne Mine until the mine closed in 1975 was composed of a mixture of 97% granulated slag and 3% pyrrhotite tailings. The tests leading to its use underground at the Horne Mine were described by Patton in 1952. The structural properties of the Horne backfill were ""intuitively"" known; it was agreed by all at the Horne Mine that the backfill was behaving remarkably well. Some were labeling it ""the best backfilling material in the world"". Its strength was said to be that of a weak concrete. All of the preceding indicate that the Horne backfill had never had its structural and other properties determined in the laboratory."

Jan 1, 1983

By S. Foged

Umicore and MWH jointly demonstrated that mechanical dewatering of goethite and neutralised tailings significantly increased the life of a 30 ha tailings pond and improved the operation of the pond. Umicore operates one of its zinc production plants in Balen, Belgium. As part of its production process, an excess of neutralised and goethite¬containing tailings is generated. These have historically been stored inside large lined ponds. As the storage area of the current goethite pond was nearing its capacity, Umicore studied the potential for an extension to the existing embankment. However, this extension would face intense regulatory scrutiny, because the environmental and safety impacts were considered important. Together with Umicore, MWH suggested and investigated an alternative treatment approach consisting of mechanical dewatering prior to storage. A feasibility study was prepared where wet storage was compared to dry storage. Differences in safety risks, environmental impacts and economic costs were outlined. The study demonstrated that the life of the tailings pond could be increased from 6 to 22 years, seriously reducing the environmental impacts and safety risks at no significantly higher cost than would have been incurred with the continued operation of the existing pond. The results of the study are presented in this paper.

Jan 1, 2006

By H. S. Chiang, Y. Luo, S. S. Peng

"IntroductionThe way in which the particle sizes distribute in the airborne coal dust plays an important role in the transportation of the dust in the mine air and human respiratory systems. Though the particles of a size less than 10 microns could be inhaled, the real distractive portion of the dust is that the sizes range from 1 to 5 microns since only they can reach the lungs and be retained there. Those with an equivalent diameter larger than 5 microns will settle on the membranes of the branchial tubes(1) while those with diameter less than 1 micron can either be exhaled out of the lungs or the settled quantity is so insignificant that does very little harm to the lungs. In the transportation process, the finer dust will fly farther away from the sources than the coarser ones. Thus once the fine dust is generated and becomes airborne, it will spread out to a larger area.In this paper, the coal samples collected from two longwall faces were analyzed statistically for size distribu¬tion. A mathematical model is proposed and the effects of different conditions on the dust size distribution were analyzed using the mathematical model.Sampling and Statistical AnalysesSampling Instrument and ProcedureThe instrument used in the sampling were Mine Safety Appliance (MSA) personal sampling units equipped with 10-mm nylon cyclones, pre-weighed MSA PVC filters and constant-flow pumps.Two longwall operating faces were selected for the dust sampling. The two faces were located in two coal mines ex-tracting Pittsburgh seam. The double-ended ranging-drum shearer applying the unidirectional cutting sequence was employed. The two-leg shield supports were used for face support. The width of the two faces was about 215 meters.In each of the two faces, four sampling stations were set up. The stations were located at the cross-cut immediately outby the headentry side, the 15th support (25 m), 65th support (107 m) and 111th support (182 m) from headentry T-junction, and numbered as #1, #2, #3, and #4 station, respectively (Figure 1). At each sampling station, a group of three sampling units was hung at proper position. At cross¬cut (#1) station, the units were hung about one foot under the roofline in the center of the cut (Figure 2a), and at the stations in the face, the units were position near the hydraulic legs and one foot below the support canopy (Figure 2b).One complete set of 12 samples was collected for each day. The sampling were performed for five consecutive days. All the samplings were conducted in the morning shifts. The time duration of the sampling for each day was about five hours. During that time, the shearer might complete 5 to 7 mining cycles."

Mar 1, 1989

By R. D. Cromarty, J. Du Toit

"Penetration of matte into tap-hole bricks causes detrimental refractory wear, which can lead to furnace breakouts. The ability of the tap-hole clay to form a protective layer on the brick, thereby limiting matte penetration was investigated by examining the interaction between platinum group metal (PGM) matte, tap-hole clay, and alumina-chrome refractory bricks on a laboratory scale.Samples containing clay and brick as well as samples containing clay, brick, and matte were heated to different temperatures to establish the clay-brick interaction and the extent of matte penetration. The greatest degree of physical contact between the brick and clay was achieved at curing temperatures of 600°C. Poor clay-brick contact was observed in the sample that was heated to 900°C.Matte displaced the clay in the clay-brick-matte sample that was heated to 1350°C, with significant matte penetration into the brick. Less matte penetration was observed when the clay-brick-matte sample was heated to 1500°C. Less matte penetration was also observed in the claybrick- matte sample in which the clay and brick were pre-baked at 800°C, and the sample then reacted with matte at 1350°C. IntroductionFloatation concentrate from ore from the eastern Bushveld Complex of South Africa, specifically the Platreef, Merensky, and UG2 reefs, forms the feed to the Polokwane platinum smelter (Hundermark, De Villiers, and Ndlovu, 2006). The ore from the UG2 Reef has a high chromite content, which requires high operating temperatures (1500–1700°C) to avoid chromium spinel build-up in the furnace hearth. These high operating temperatures lead to matte superheats in the vicinity of 500– 600°C, which put increased demands on the refractory materials (Nelson et al., 2005).Upon tapping, the matte moves through the tap-hole, which consists of an aluminachrome refractory brick-lined tapping channel (Hundermark, De Villiers, and Ndlovu, 2006). The flow of molten matte is stopped by the injection of tap-hole clay to form a plug in the tap-hole. The tap-hole clay hardens and strengthens during curing to obtain the required hardness and refractoriness against penetration, corrosion and erosion (Nelson and Hundermark, 2014)."

Jan 1, 2016

By L. Diestelow

Evaporation and crystallization processes are used extensively in the mining industry to provide many pro-ducts. In the case of solution mining evaporators are used to concentrate, or to concentrate and crystallize the raw materials being mined. In the case of underground, or strip mining dissolving and crystallization are used in many processes in order to purify the ore to saleable materials. Presently evaporators and crystallizers are being used in the production of sodium chloride, potassium chloride, sodium carbonate, sodium sulfate, lithium chemicals, aluminum, and many others. The evaporator is a device designed to remove water or solvent from a solution. In an evaporator the energy released by steam condensing on one side of the heat transfer surface is transferred to the product solution on the other side of the heat transfer surface. As long as the boiling temperature of the product liquor is below the condensing temperature of the steam, the product solution will absorb heat. This heat absorption causes vaporization of the water (solvent) in the product solution resulting in concentration of the product. The simplest evaporator is the single effect evaporator. If we assume the feed introduced into the single effect evaporator is at its boiling point, ignore radiation losses, and assume the steam into the heat exchanger is dry and saturated, then the heat transferred will correspond to the latent heat of vaporization. Therefore, one kilogram of condensing steam will produce one kilogram of evaporation. Economies in energy usage compared to the single effect evaporator can be made by using multiple effect evaporators, or vapor recompression evaporators.

Jan 1, 1993