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By K. Pirapakaran

The Geotechnical Engineering research group at James Cook University has been working closely with all the leading mines in Australia in the area of minefills. They have carried out substantial research and consulting work on the drainage and stress developments within hydraulic fills. The objective of this paper is to summarize their work during the past five years on hydraulic fills. The paper will serve as a one-stop reference, pointing to relevant literature including the authors? own publications, on various issues covering drainage and stress developments within hydraulic fills. More than 15 different hydraulic fills, representing five major mines in Australia, were studied. Their grain size distributions and placement characteristics including permeability, porosity and dry density were studied and comparisons were made with the limited in situ data available in the literature. Stress development within hydraulic fills has been studied to minimize the risk associated with barricades failure. FLAC and FLAC3D were used to model stress developments within the hydraulic fills and were compared against the approximate closed form solutions available in the literature. A laboratory model was developed to study arching effects within the hydraulic fills.

May 1, 2007

By J. Reed

The RockWorks EarthApps represent a free collection of 74 geology-related programs that read data from a built-in datasheet and create diagrams within Google Earth. EarthApps also includes programs that extract data from Google Earth. The programs that create diagrams include: point mapping (e.g. borehole locations), proportionally scaled icons (e.g. geochemistry), and strike & dip symbols. Line mapping utilities include; polylines, parabolas and pipelines. Polygon mapping programs include; thematic mapping (e.g. geology), mining claims, and public land survey sections. Image overlay capabilities include; draping (e.g. geologic maps) and time-based animations. Vertical image display capabilities are centered on either midpoints (e.g. drill-hole logs) or stretched between endpoints (e.g. cross-sections). The Flyover programs create virtual tours for site presentations. The cell-mapping includes a variety of algorithms (e.g. geochemical and geophysical contouring). Survey programs convert and export survey data to Google Earth as points and polygons. Programs that extract data from Google Earth include; points, lineations, polylines, and polygons. The RockWorks/EarthApps collection is developed by RockWare Incorporated based in Golden, Colorado.

Feb 27, 2013

By E. F. Koppe

The Upper Freeport coal in the Freeport and New Kensington quadrangles, Pennsylvania, varies from a bony streak to a thick coal deposit often exceeding ninety inches, the "Double" or "Thick Freeport". Distinctive basal partings, a central bone layer, and a canneloid top bench may be present. The appearance of a sandstone roof, sandstone rolls, and bony coal at the top of the main coal bench can be anticipated in thin Freeport areas when basal partings are absent. When the two basal partings are present, a shale roof is normal. These effects are correlated with the original topography upon which the coal was deposited. The original depositional high areas tend to coincide with present structural highs. Preliminary data indicate that coal quality, in part, is affected by the deposi-tional setting. In "high" areas, a tendency exists for the main coal bench to contain higher percentages of fusain and mineral matter. Within limits, some-what higher ash fusion temperatures appear to correlate with paleotopographic highs. As a result of these findings, critical examination of the paleotopography and related sediments is indicated in other areas and other coals. The Upper Freeport coal is quite variable both in thickness and composition in the Freeport and New Kensington quadrangles of Pennsylvania (Figure 1). The coal horizon in these quadrangles is marked either by a thin carbonaceous shale bed or by a single bed containing a variable number of partings (binders). The complex coal zone known locally as the "Double" or "Thick Freeport" contains the Upper Freeport Coal Bed at the base; but in addition, it has an overlying bone layer and an upper coal bed occasionally capped with a canneloid layer. The "Thick Freeport" often exceeds 90 inches in thickness, whereas the normal Upper Freeport coal usually varies between 34 and 50 inches.

Jan 1, 1961

By R. T. Jones

The largest known platinum group metal (PGM) deposit in the world is the Bushveld Complex in South Africa, with the Great Dyke in Zimbabwe also being one of the biggest. It is therefore not surprising that the majority (just over 5 million troy ounces or 156 metric tons per annum) of the world's platinum is produced in Southern Africa. Primary smelting of ore concentrates is carried out in that region by five companies, namely Anglo Platinum, Impala Platinum, Lonmin Platinum, Northam Platinum, all of South Africa, and Makwiro Platinum in Zimbabwe. The only other primary smelter of platinum group metals is Stillwater Mining of Montana, USA, although very significant quantities of PGMs are produced as co-products by Norilsk Nickel of Russia. Smaller (but still significant) quantities of PGMs are produced by Falconbridge and Inco of Canada, also as co-products from nickel sulphide smelting. There are many similarities between PGM smelting and nickel sulphide smelting, and the range of technologies in use includes six-in-line rectangular electric furnaces, three-electrode circular AC furnaces, Peirce-Smith converters, and Anglo's ACP (based on Ausmelt technology). PGMs are also recovered from residue materials using DC arc furnace technology.

Jan 1, 2005

By David Brown, Dirk van Dyk

Horizontal rotating mills are being used all over the world associated with different mineral and power generation industries. David Brown South Africa, with over 140 years of experience in gear manufacture and design, has been supplying these industries with innovative designs at exceptional quality. The gearing systems associated with these industries are challenged daily with operating conditions with are not always fully understood. Failures are therefore experienced, over time in the industry, which can therefore not always be fully explained. David Brown South Africa has developed a gear monitoring system, the Intelligent Gearing System, in association with Transmission Dynamics (UK), in order to monitor and analyze these operating conditions in real time. The system has been designed on the principles of Six Sigma, incorporating Design for Six Sigma. The purpose with this system design is to monitor the operating conditions on the pinion, record the information and analyze the data in relation to the rate of fatigue damage to the girth gear and pinion. This is done in real time and unattended. The output from the Intelligent Gearing System can be fed back into the operating system of the mill user, in order to display an alarm for operating conditions exceeding the design criteria as well as information on the rate of fatigue damage due to these operating conditions. When the mill operating conditions are better understood, and the effect on the fatigue life of the mill gearing components, mill users can forecast critical spare holding levels with an increased accuracy. The Intelligent Gearing System also allows early actions to remove reasons for system overloads.

Jan 1, 2007

By James R. Dunn

Samples were taken of industrial mineral waste materials which are potentially capable of being used for filling underground coal mines for subsidence control in the Pittsburgh and the Scranton-Wilkes Barre areas of Pennsylvania. The samples were subjected to potentially relevant standard tests which are commonly used 1n the evaluation of soil materials and mineral "aggregate materials. Measurements of plasticity, liquid limit, and gradations, particularly in the -200 mesh size range, indicated a comparative lack of clay minerals. Cementitious reactions between sources of alkali, such as calcium hydroxide or portland cement stack dust, and of silica, such as clay or fly ash, were found to occur in various mixes of high-bulk materials. Strengths of up to about 400 psi at 84 days were observed. The possibility of emplacement of high-bulk material by both turbid flow (or density currents) below water and by mud flows above water were considered and both appear to be reasonable and possibly simpler than the current mechanisms of emplacement.

Jan 1, 1977

By Elliott A, Kingsnorth D. J

The development of a large high grade spodumene orebody, in excess of 30M tonnes containing at least 7M tonnes at 4.0% Li20, by Lithium Australia Ltd at Greenbushes, Western Australia is significantly increasing the world consumption of lithium minerals. The availability of two low cost sources of lithium, spodumene concentrates (7.5% Li20) and glass grade spodumene (4.8% Li20) has been welcomed by the ceramic and glass industries as it assists them to lower their raw material costs at a time when they are facing severe competition from alternative materials. While there is no shortage of lithium reserves in the world, there has been a shortage of high quality lithium minerals. The Lithium Australia development has filled this need. The favourable factors of high grade, low impurities, open cut mining and existing infrastructure make this an ideal low cost source for a long term downstream lithium industry. The Lithium Australia mine development has filled the need for a reliable long term supply of lithium minerals. The long term viability of this resource is ensured by the unique combination of the following key attributes of the development : High grade reserves of 7.OM tonnes of 4.0% Li20 within 130 metres of the surface, contained within a total proven reserve of 30M tonnes of 2.8 % Li20. Open pit mining with stripping ratio of less than 2.5:1 waste:ore. Low impurities levels, particularly in those elements, that have a detrimental effect on the colour of glass/ceramics i.e. iron, manganese, titanium and chromium. An existing mine infrastructure that includes an adequate water supply for all foreseeable processing requirements. A sophisticated spodumene concentrator utilizing statistical process control to produce a consistently high grade product with minimal impurities. A technically qualified stable workforce fully acquainted with spodumene processing techniques. Greenbushes high grade concentrates have found ready acceptance in the specialty ceramic and glass industries during the past four years. The consistency and high grade/low impurity level of the product has enabled its use in the production of television tubes, oven to table ware, glass fibres, specialty glasses and ceramic glazes.

Jan 1, 1989

By Mark Lawshe, Shosie Serata

The conventional method of mining underground, using narrow rooms and wide pillars, has proven to be poorly adapted to the powerful earth forces that act on underground openings. The high costs of roof bolting, timbering, steel arching, and other means of artificial roof support for both room-and--pillar operations and longwall gate roadways attest to the limitations of traditional mine design. Too often, productivity halts when corners buckle under "cutter roof' stresses, floors heave, and roof strata fall. In the 1960s, an entirely different approach to strata control was developed. The Stress Control Method (SCM) stabilizes failing roofs and heaving floors by removing the cause of failure - highly concentrated stresses around the openings. This is achieved by regrouping three to 10 rooms into a single entry where the rooms are separated by very narrow yielding but stable pillars. SCM employs a specified excavation sequence to redirect earth pressures away from the mine openings. The yield pillars act as scaffolding until a permanently protective secondary stress envelope forms around the entry (lower part of Fig. 1). The result is a dramatic improvement in roof stability and a significant reduction in artificial support costs. Some roof bolting must still be done, mainly to meet Mine Safety and Health Administration (MSHA) requirements. Potash, salt, coal mining The stress control method was first applied to the deep potash mines of Saskatchewan. The new SCM design actually increased room widths to enlarge the stress envelope, redistributing the stress concentration away from the entries (Serata and Schultz, 1972). This resulted in a turnaround from pervasive roof fall/floor heave conditions that threatened operations in the eight new mines opened in the Saskatchewan potash field during the 1960s. In addition to eliminating all roof bolting, SCM successfully stabilized ground conditions and substantially increased productivity over the original design (Serata, 1976, 1982). Similarly, the deep Boulby potash mine of Yorkshire, England, was about to close after various conventional means of combating roof failure had failed. An SCM test area was excavated that resulted in the ground quickly stabilizing without need o artificial support (Serata, 1982; Chilton and Laird, 1982). Another example is the Diamond Crystal salt mine in Louisiana. Here, multiple level mining was being extended from the third to the fourth level downward in the Jefferson Island salt dome. Extensive roof failure was occurring at 396 m (1300 ft) ii the third level. SCM design principles in creased the room size from 24 to 49 m (80 t( 160 ft) on the fourth level at a depth of 457 m (1500 ft). This unprecedented expansion of room width was first questioned and later ap¬proved by MS HA, which expressed satisfaction in seeing the improvement documented by field validation data in 1973. The most recent SUM application to salt mining has been in the Michigan Basin a: Goderich, Ontario. The anticipated abandonment of Domtar Chemicals Group/Sifto Salt Division's deep operation in bedded sale was prevented by a multi-year SCM implementation. The success of SCM in dry mining[lecc] to its application to solution mining of salt This adaptation of the method is now being implemented in bedded salt at Fort Saskatchewan, Alberta by Dow Chemical Co., and in St. Clair, MI by International Salt Co. Application of SCM to solution mining in a salt dome is proceeding at Napoleonville. LA by Dow Chemical. The same technology has also been applied to cavern design for the Louisiana Offshore Oil Port (LOOP), and the compressed air energy storage (CAES)

Jan 1, 1989

By John Watson

New Technologies, New Challenges and New Opportunities For quite some time now, numerous explosive manufacturers have spent untold man-hours and millions of dollars trying to develop a blast initiation technology that would “once and for all” provide users with what was once believed to be only a theoretical possibility...nominal timing. Zero “cap scatter” (the amount of variation of delay timing from the targeted nominal) has been the industry’s goal ever since delays were first introduced into the marketplace. Just as adding delay time between blast-holes improved blast performance since their introduction, having the wrong delay or a poorly timed blast has proven to be very inefficient and in many cases hazardous. The question of how precise a blast initiation system needs to be still remains unanswered, but electronic detonator systems being used today indicate that significant improvements can be achieved over conventional pyrotechnic detonators. These systems can typically provide single digit millisecond ranges of variability, if not sub-millisecond in some cases.

Jan 1, 2003

R. C. BUCKETT (Lake View and Star Limited) : At the outset I should like to add my congratulations to those already extended to Mr..Norwood on his excellent paper, which has given us all an inspiration to strive further to improve our plant recoveries. In some respects this paper has left us so little to discuss without considerable time spent on. further research work. At all points one is met by a baffling array of facts which leave one feeling hesitant to speak.The careful and methodical way in which Mr. Norwood went along step by step until all channels of research presenting themselves were tested to his own satisfaction leaves me with but a few comments to make. Particularly striking to me is the explanation of the residual gold values in calcines by recrystallization of haematite and here is a line to be attacked by future studies. This will be mentioned again later.Particularizing on the paper, the first point that struck me was the method of change of pyrite through to the final haematite. I have never been able to satisfy myself that a sample taken from various positions along a roaster when cooled, as described on p. 397, represented a fair sample of the conditions at that point, but I must confess that I have not found a substitute that did satisfy me.However, the following figures are illuminating... But to fill dry a receptacle of known volume with calcines, as described by Mr. Norwood, gives the following apparentspecific gravities:

Jan 1, 1940

By R. J. Hundermark

Keywords: Anglo American, Anglo Platinum Ltd, Waterval, Mortimer, Polokwane, ACP, pyrometallurgy, platinum, PGMs Anglo Platinum Ltd is the largest primary platinum producer in the world and operates three smelters in South Africa: Waterval, Mortimer and Polokwane. The operational details of the smelters are covered in previous reviews, thus only unit operations that have been upgraded are discussed. The most significant of the upgrades include the installation of a second ACP converter at Waterval Smelter in 2006 and the anticipated upgrade of Mortimer Smelter to 38MW in 2011. Several advances have been made in the smelting operations to improve the furnace stability and longevity. Control of the chromium input to each of the smelters has substantially allowed continued operations at levels below the spinel saturation point in slag, which results in lowered matte and slag temperatures. Mogalakwena concentrate, arising from the Platreef ore, is used to dilute high chromium-containing concentrates. In addition, furnace controls have improved in terms of crucible temperature and condition monitoring, improved feeding control, management of alarms and trips and having the quality of instrumentation and operational rigour required to support this. Advances have been made on the ACP converter in terms of good converter matte quality, and increased intensity and efficiency of operation. Combined with improvements to both the conventional and tower sulfuric acid plants, the emissions from Waterval Smelter have been reduced substantially since the introduction of the ACP. This is in spite of increasing metal throughput. The Anglo Platinum Ltd smelting operations have made significant progress since 2006 and further advances are envisaged to further improve on safety, reduce costs, increase efficiencies and throughput, while reducing emissions.

Jan 1, 2011

THIS has been a much-neglected branch of engineering. With the majority of industries labour is the chief item of trouble and expense. Anything that will reduce trouble and increase efficiency is well worth considering. It is only of recent years that any attempt has been made on a scientific basis to improve conditions sporadic attempts having been made from time to time, privately and by law. Some have been successful, others unsuccessful not necessarily the fault of those who initiated the ideas, though naturally mistakes were made in some cases for want of experience, but those whom it was desired to benefit were not always prepared for the change, and by their distrust hampered schemes instead of assisting them.Man power is generally more expensive than machinery, though there are exceptions, such as when a small amount of work has to be done in a place where machinery does not exist, and it would not pay to instal any or where labour is cheap, and skilled workmen are scarce as in some tropical countries. When machinery is first introduced it generally causes the suspicion that it will deprive men of their work. It may cause men to vary the conditions of their work, and in some individual cases, when men are unable to conform to changed circumstances it may result in a certain amount of hardship; but, after all, the less competent must not hold back progress for the general good. Besides, changes as a rule do not take place suddenly, so old hands can generally find work at their particular calling 'till nature requires them to retire. In cases where men take to machinery, they not only find that they are relieved of the...

Jan 1, 1918

By D. T. Bergado

The uppermost subsoil profiles of the Bangkok plain can be divided into four layers, namely: weathered clay, soft clay, stiff clay, and dense sand layers. The soft Bangkok clay is a normally consolidated marine clay with built-up preconsolidation effects and overlain by a weathered crust. Up to the present, a large number of full-scale tests on excavations and pile foundations has been made by numerous investigators. Based on these results, the available data are reviewed and evaluated. The results show that for test excavations, the excess pore pressures were overpredicted by the existing theories. The vertical and lateral movements in the excavations can be predicted by the bilinear and non-linear finite elements using appropriate modulus values. Relationships among probability of failure, safety factor, and safety margin of the excavation were also obtained. In the case of pile foundations, good agreement between the measured and predicted ultimate pile capacities were obtained for long piles. The adhesion factors ranged from 0.4 to 1.0 while the average skin friction factor was found to be 0.33. The ultimate capacity of the pile was also predicted successfully by using the Dutch cone data. For lateral deflection of piles, Davisson and Gill's theory predicted well in the low deflection zone while Poulos' theory agreed well in the high deflection zone. From the probabilistic analysis of ultimate pile capacity, the probability of failure was related to the central factor of safety. The piles usually used in Bangkok area are mainly precast concrete piles

Jan 1, 2010

By J. -P. Tshibangu, A. Vervoort, A. Lavrov

Abstract: The aim of the research presented is to study the effect of complex loading schemes on the fracturing process during loading and/or unloading. A first set of experiments was done using a poly-axial cell. These experiments in combination with numerical simulations showed a difference in micro-fracturing (shear and tensile cracks), but not in macro-failure between various loading/ unloading schemes. The second set of experiments was based on the three-point bending test and several cycles with or without rotation between cycles were applied. If the specimen was rotated by 90° or 180° about its long axis between the first and second cycle, no Kaiser effect was observed. Résumé: Le but de la recherche présentée est d’étudier l’effet de schémas de charge complexe sur le processus de fracturation durant la phase de charge et de décharge. Une première série d’expériences était réalisée utilisant une cellule polyaxiale. Ces expériences combinées avec des simulations numériques ont montré une différence de micro-fracturation (fissures de cisaillements et de traction) pour les différents schémas de charge et décharge, mais en ce qui concerne la macro-fracturation ce n’est pas le cas. La deuxième série d’expériences était basée sur des essais de flexion trois points avec plusieurs cycles, avec ou sans rotation entre les cycles. Si l’échantillon est tourné de 90° ou 180° selon le grand axe entre le premier et le second cycle, l’effet Kaiser n’est pas observé. Zusammenfassung: Der Zweck der vorliegenden Forschung bestand darin, den Einfluß von komplizierten Beanspruchungsschemen auf den Bruchprozess im Laufe von Belastung und/oder Entlastung von Gesteinen zu untersuchen. Der erste hier beschriebene Satz von Experimenten wurde mit einer dreiaxialen Belastungsmaschine angestellt. Diese Experimenten zusammen mit dazugehörigen numerischen Simulationen zeigten Unterschiede zwischen Be- und Entlastungsbeanspruchungen in Bezug auf mikrobruchmechanische Mechanismen (d.h. Scher- oder Zugrisse) an, aber nicht in Bezug auf den Makrobruchprozess. Der zweite Satz von Experimenten umfasste Gesteinsbeanspruchung in mehreren Zyklen von Drei-Punkt-Biegung, indem die Gesteinsproben zwischen den Zyklen um einen angegebenen Winkel (0°, 90° oder 180°) gedreht wurden. Falls die Probe um 90° oder 180° gedreht wurde, wurde kein Kaiser-Effekt im zweiten Zyklus beobachtet.

Jan 1, 2003

By L. B. Hales

Expert control of grinding and flotation plants has been successfully used in the minerals industry since the 1970?s. The earliest of these systems were written in a hard-coded fashion in FORTRAN, BASIC or Pascal. Second generation systems were built using the first experimental expert system shells that were being developed in the artificial intelligence community. Later systems were deployed in expert system shells designed for real-time processing plants that also included the ability to model the process with neural network models and optimize setpoint selection through the use of genetic algorithms. Significant performance increases have been achieved using these systems, but in general, they suffer from the static nature of their rules and to a degree the process models also. Typical improvements quoted in the literature suggest throughput rate increases of 4 to 8 percent and recovery increases of 1 to 4 percentage points. In over 30 years of designing and installing expert systems we have never seen performance numbers less that these but have often seen numbers in excess of the high values. However, once the system has been installed and tuned up the performance usually does not improve much thereafter. Granted, the initial increases in throughput rate and recovery are significant but a question always lingers, that is, can the expert strategies be modified further to squeeze a little more improvement out of the system. The answer to this question is a resounding yes, however a complete understanding of what we do well as designers and operators of expert control systems is required as well as how we can improve upon our best practices is required to move us from the performance plateau we have been on for a number of years to a new higher level of performance.

Jan 1, 2009

The methods and equipment developed and used at the Mount Isa mine to obtain samples of uncemented hydraulic fill lying above major horizontal pillars are described. From existing underground development, samples were obtained at distances up to 50 m, of which up to 30 m was through hard rock. Samples were used to predict fill behaviour as it affected mining security during recovery of the pillars.Specialized equipment for difficult sampling situations and also other sampling exercises are described.

Jan 1, 1976

By James F. Reynolds

Introduction There are 1.4 Gt (1.5 billion st) of recoverable coal under less than 914 m (3,000 ft) of cover in Colorado in pitching seams. Snowmass Coal Co., in cooperation with the US Department of Energy, introduced the longwall mining method in pitching seams to North America. This venture is a coal mining research program directed toward the profitable production of coal under difficult mining conditions as found in pitching seams of the western US. Snowmass Coal classifies pitching seams into the following categories for longwall on the strike in seams 3 m (10 ft) or less thick: • Flat = 0 to 10°: Normal continuous mines and shuttle cars work efficiently. • Slight = 10° to 22°: The maximum pitch that rubber tired equipment will function. • Moderate = 22° to 40°: The angle of repose of mined coal. • Steep = 40° to 60°: The limit of safe use of this roof support. • Vertical = over 60°. The longwall roof support covered here will work in all pitches except vertical. The shearer and conveyor will work in flat through moderate conditions. Longwalling across strike with this equipment in seam pitch over 60° could be accomplished with an inclined face. Development of the first longwall panel began in 1979 and was completed in 1981. The longwall equipment was installed and mining began on Aug. 11, 1981. Mine Planning and Development The original mine plan took advantage of old works abandoned in the 1960s. The gates were developed on a two-entry system with the entries rising 2° to the strike, allowing water to drain from the face. The mining method was by Alpine F6A road header continuous miners with bridge conveyor type coal transport into 5.4-t (6-st) bottom dump coal cars hauled on 1.1-m (42-in.) gauge track by 7.2-t (8-st) battery locomotives. The initial concept was to haul coal from the longwall by battery locomotive. Lack of discipline, however, was shown in the irregular direction of the gate entries, and local rolls in the coal seams severely limited the capacity of battery locomotives. Current mining law prohibits using an intake escapeway for belts or trolley locomotives. A two-entry system is the simplest method of panel development in a pitching seam. A continuous miner cannot be trammed from one entry to another because of steep "X" cuts. Thus, the development requires a continuous miner in each entry. The configuration of the old mine works resulted in a first panel longwall block of three 108 m x 1.6 km (355 ft x 5,400 ft). In panel development, the use of battery locomotives for coal hauling became evermore costly. When the panels were completed and the setup room finished, the lower gate entry was changed to a belt entry and battery locomotives were abandoned. A new slope was driven and the mine supply system was converted to rubber tire diesel supply. The latest generation of roadheader and standard high powered shuttle car-to-belt system is now used for development. Selection of Longwall Equipment Longwall mining across the strike on pitching seams is currently practiced in many nations. Equipment similar to that used by flat seam longwalls is available for pitching seam use in Great Britian and Germany. Face equipment includes a twin outboard armored face conveyor. It was selected to give maximum retention of coal on the conveyor due to flight rigidity and to prevent coal from sliding down the face and jamming the lower belt gate. Also selected was a 22-mm (0.9-in.) Dowty twin-outboard face conveyor for a 106-m (350-ft) face with a single 112-kw (150-hp) drive

Jan 12, 1983

By Arnold O. Tanner

Tables based on 1985 data, which were not available in time for publication of the "1985 Minerals Yearbook," are included in this chapter; corresponding tables for 1986 are not yet available. Raw nonfuel minerals produced in the United States during 1986 had an estimated value of $23.5 billion, an increase of $0.25 billion over the 1985 value. This is the fourth consecutive year that the value has increased, and except for a de- crease in 1982, the value each year has increased since 1971, or 14 out of 15 years. Industrial minerals growth slowed from a 3% increase in value in 1985 to a 1.5% increase in 1986, reflecting the slow growth in the domestic economy. The value of industrial minerals, more than three times larger than the value of metals, easily offset the less than 0.5% decline in the value of metal mine production. Although the decline was small, this decrease makes 1986 the fourth year in the past 6 years in which a drop in the value of metal mining production occurred in the United States. U.S. production continued to lag behind the growing world production. Overall, the estimated raw nonfuel mineral production rose 1% over that of 1985. Domestic mine production of ferrous metals declined as follows, in decreasing order of production: nickel, iron ore, tungsten, and molybdenum. All remaining domestic primary nickel and tungsten mines had closed down by yearend. Nonferrous metals that similarly declined included titanium, rare-earth metals, lead, silver, zinc, and magnesium. For the second consecutive year, aluminum, produced predominantly from imported bauxite, declined in production, while imports reached record-high levels. Somewhat modest gains were made in beryllium and copper. As has been the case for a number of years, gold was a bright spot in the domestic and internation-al metal mining industry. Gold production was spurred on by the increasing usage and development of heapleaching techniques that make lower grade ores, which were previously uneconomical, profitable. Additionally, various mining companies, the U.S. Mint, individual States, and a number of foreign countries began production of gold bullion and commemorative coins. Gold output in the United States increased from 2.43 million troy ounces (revised) in 1985 to about 3.73 million troy ounces in 1986, a dramatic 54% rise.

Jan 1, 1988

By J. Morkel

During research on mainly the weathering of kimberlite, it became evident that its mineralogical composition is an important factor in the complex process of physical and chemical disintegration. The mineralogy of tuffisitic kimberlite breccias from two localities, the Cullinan and Venetia mines, is compared with special reference to the occurrence of associated clay minerals. The clay mineral composition influences the engineering properties of these rock types. It is illustrated how the presence of swelling clay components can be confirmed by ethylene glycol treatment and chlorite minerals by heat treatment using X-ray diffraction. Smectites are present in both tuffisitic kimberlites, dominant at Venetia while chlorite is more frequent at Cullinan. More tuffisitic kimberlite breccias samples from venetia were also characterized. It was found that kimberlite disintegration is correlated with the presence and abundance of smectite.

Jan 1, 2006

By H. E. James

Much has been said and written about the need to reduce South Africa's dependence on gold. To compensate for the decline in the country's foreign-exchange earnings resulting from the phasing out of gold, which must inevitably occur at some future date, a far higher priority will have to be placed on the mining, beneficiation, and export of the 59 other mineral commodities produced in South Africa. The basic strategy of the mining and metallurgical industries should be to move from the traditional approach of establishing a resource base to the establishment of a market base; to turn from production orientation to market orientation; and to rely less on exploration and economies of scale and more on process innovation and product development. The enthusiasm, entrepreneurial spirit, and commitment of the leaders in the mining and metallurgical industry will clearly be of decisive importance in the establishment of new industries for the beneficiation and export of added-value mineral-based products. The State can make a significant contribution by the provision of a welldeveloped and efficient infrastructure, including rail and harbour facilities, communications and health services, roads, and of electricity and water supplies. In our search for a new development strategy for the beneficiation and export of South Africa's minerals, we need to recognize that no one nation has all the mineralresources that it needs. Commercial and strategic manipulation of mineral supplies should no longer be tolerated. The future of the human species lies in international cooperation and in a greater understanding of the limitations of the world we live in.

Jan 1, 1985