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By J. W. Wang

This article first explains the mechanism of forming strength in the Jet grouting reinforced foundation, and points out the function of cement hydrates and clay minerals in clayey soil, the reinforced body with the character of long-term growth of strength. Secondly, regarding the strength and the deformation characteristics of compound foundation, the article points out that the stress-strain curve of the jet grouting pile is approximate to hyperbolic curve. Finally, the article cites three examples of application in the construction of the metallurgical industry.

Jan 1, 2010

By F. T. Cawood

Inauguration of the new political dispensation in South Africa in1994 initiated a dynamic shift in the ownership, management and development of the country?s affluent mineral heritage. The process of substituting the old South African regime with a new equitable system started soon after the 1994 election of the African National Congress (ANC) to parliament. The Congress?s Freedom Charter revealed the intent of the new dispensation when it called for radical transformation of mineral development. However, since then there have been important changes affecting the rules of mineral development. These are: ?A drastic change in politics ushered in by negotiation, a spirit of reconciliation and a desire to settle disputes peacefully ?The globalization of the South African mining industry in tandem with the opening of domestic mineral resources to foreign capitalists and ?The introduction of sustainable development as a holistic approach to mineral development in order to replace traditional narrow-minded environmental management. Each of these significantly shaped the new mineral investment environment of South Africa. This paper represents a summary of the historical developments leading to the current Mineral and Petroleum Resources Development Act No. 28 of 2002, its regulations, the much publicised Broad-Based Socio-Economic Empowerment Charter, its associated Scorecard, and the Draft Royalty Bill.

Jan 1, 2004

The Kingsgate molybdenite pipes are considered on petrochemical data and field occurrence to be, possibly, epi-magmatic plutonic offshoots grading into hydrothermal bodies. There is reason to believe that the ore is derived from a highly acid granite of type similar to that of the tin bearing areas of northern New England. The mineralogy, microtextures and paragenesis of the ore are discussed.INTRODUCTIONThe Kingsgate Mining Field is situated in steep, heavily timbered terrain 18 miles E.N.E. of Glen Innes and 430 miles north of Sydney. Bismuth and molybdenum ores were discovered at Kingsgate (Yarrow Creek) in 1877. Subsequently some 50 pipes were developed yielding tonnages which at the peak of operations, 1905 to 1920, rivalled production from the rich deposits of northern Queensland.Attempts to revive the field have been made periodically and small parcels of ore have been forthcoming.' During World War II demand for piezioelectric quartz again focussed attention on Kingsgate but twinning and other imperfections of the quartz prevented all but a minor exploitation of the otherwise noteworthy crystals of this locality.There is reason to believe that the ore at Kingsgate is not exhausted through exploration and mining costs would probably be high due to the capricious nature of the pipes and to the irregular distribution of rich ore shoots within them.

Jan 1, 1962

By Douglas Kathol

Coal in the 1990?s Exit of the integrated oil company [Shell Arco Mobil Exxon Mapco Kerr McGee Hansen Nerco Sun] Continued decline in coal prices Significant mergers & acquisitions (M&A) activity ?Most properties traded, some twice ?Significant consolidation ?Massive recapitalization ?New industry leaders ?Frustrated expectations

Jan 1, 2002

By Valentín Choquenaira Bombilla

El presente trabajo describe el proceso de automatización de la planta concentradora BHPBilliton deTintaya desde el punto de vista del usuario final y así proporcionar una visión global sobre los aspectos relacionados con la automatización de nuestro proceso a través de sistemas de control distribuido (Distributed Control Systems, DCS) e inteligencia artificial (Sistema Experto).También se describe la arquitectura del control, las formas de conexión (Hardware) y la función que desempeña dentro del sistema cada uno de los componentes del sistema de control distribuido instalados en la planta concentradora de sulfuros de BHPBilliton Tintaya S.A. así como algunos conocimientos básicos de manejo del sistema composer y conductor NT (Software) para realizar las funciones de configuración, monitoreo y control del proceso desde unidades remotas y estaciones de trabajo.

Sep 12, 2005

By Edmond Chin

The area encompassed by the political entities included in this study com-prises 11 million square miles or about 15 percent of the total Earth's land area. The bulk of the region is contained on the Asian continental land mass. Australia, the world's largest is-land or the world's smallest continent, alone is almost as large as the continental United States. The islands of New Zealand, New Guinea, Borneo, Sumatra, and Honshu are among the largest in the world. Collectively, they constitute a land area of 1.1 million square miles or an area about one-fourth the size of the United States. The region is noted for its great rivers. The Chang, Huang, Amur, and Mekong are respectively the fifth, sixth, eighth, and eleventh longest rivers in the world. The Ganges-Brahmaputra has created the world's largest delta, which covers 30,000 square miles. Abutting East Asia are the Sea of Japan, Dong Hai, Nan Hai, Bay of Ben-gal, and Arabian Sea. In the Southern Hemisphere, there is the Indian Ocean and the South Pacific Ocean. The Continental Shelf adjacent to the region constitutes a large proportion of the world's readily accessible shelf area. On the other hand, the Philippine and Java trenches and, further out, the Mariana Trench reach to formidable, abyssal depths, downward to 6,000 fathoms. Contrasting to this is Mount Everest, which reaches a lofty height of 29,028 feet. And then there is Xizang, whose high plateaus have been called the roof of the world.

Jan 1, 1992

By S. Al-Hassan

The deposit has been exploited for Mn oxide and carbonate since 1916. Known reserves of MnO, however, are almost depleted and the survival of the mine will depend on the exploitation of the carbonate. Kriging, inverse distance weighting (IDW) and cross-sectional methods have been applied to the evaluation of the carbonate resources and reconciliation of the estimates obtained shows that kriging and IDW give almost identical block values. A comparison using conditional probability indicates that there is virtually no difference between the global reserve estimates derived from the cross-sectional and kriging methods. The physical causes of these similarities are highlighted and the problems of dealing with multimodal distributions are discussed together with the difficulties of semi-variogram modelling

Jun 19, 1905

By Chen-Luh Lin, Jan D. Miller, Sindhoora Puvvada

The depletion of good-quality phosphate resources, coupled by a need to supply acceptable products at a rapid rate, while meeting the specifications of fertilizer chemical plants, is of significant concern to the phosphate industry, particularly the production of concentrates with tolerable dolomite content. Tremendous efforts have been made in the past to develop an efficient and economical process that can effectively reject dolomite. However, dolomite removal continues to plague the phosphate industry due to several process-specific challenges being encountered with various beneficiation technologies. In this regard, detailed characterization of phosphate reserves is crucial to understand textural limitations and help design appropriate strategies to achieve quality products. In this paper, the development of procedures to establish dolomite rejection/francolite recovery curves for gravity preconcentration of pebble phosphate from Central Florida is described using high-speed X-ray computed tomography (HSXCT). The developed procedure is illustrated with the analysis of high MgO pebble phosphate samples (10.39 mm × 1 mm) received from South Pasture and Four Corners locations operated by the Mosaic company. The rejection/recovery curves were calculated for each sample for five different particle size classes to observe the trend in rejection/recovery with variation in particle size. In order to evaluate the reliability of the HSXCT data, analysis using the high-resolution X-ray computed tomography (HRXCT) technique was performed on one particular sample (FC-3-1). Finally, to assess the separation efficiency, the HSXCT and HRXCT rejection/recovery curves obtained were compared to experimental gravity preconcentration results reported in the literature. In this way, liberation limitations for gravity preconcentration in the processing of pebble phosphate have been established based on X-ray computed tomography analysis.

By D Thorburn

This paper reviews the history of environmental assessment in New Zealand with reference to mineral developments. Emphasis is given to larger more controversial projects particularly metal mines. The changing role and application of the Environmental Protection and Enhancement Procedures is examined in the context of changes in the government's environmental administration and the response of the Ministry of Energy's resource allocation group. Conclusions are drawn on the effectiveness of the present environmental assessment activities and on the allocation of administration of priorities in the Ministry. The Ministry of Energy has effectively ceased to exist.

Jan 1, 1990

By R. Patrick

As a unique South African organisation, CSIR: Division of Mining Technology (Miningtek) strives to support the mining industry by improving health, safety and productivity through developing, adapting and transferring technology. Considerable effort is currently directed towards the development of potential non-explosive mining methods with the potential to allow continuous mining in narrow reef conditions. Besides improving productivity, continuous mining results in concentrated mining which has a significant impact on reducing infrastructural costs. Impact Ripping and Water Pulse Rock Breaking have been tried on gold mines, whereas Activation, Mini-Disc? cutting and the Plasma Holemaker are currently being tested on platinum mines. The organisation?s many years of experience in novel rockbreaking, together with its world-wide collaborator network, has placed it in a unique position to assist the mining industry and manufacturers in developing and/or adapting existing technologies for application underground. Currently a range of technologies are being investigated, which have reached different stages of maturity. The main technologies under investigation are; - Impact ripper system - Water pulse rock breaking - Activated undercutting rollers - Mini disc cutters - Electric rock breaking

Oct 1, 2001

South Africa remains the largest global producer of gold, accounting for 11.3 per cent of total world mine production, which amounted to 2520.2 t in 2005. The benefits and disadvantages associated with hedging practices in general, and among South African gold producers is examined. The wide variety and unique nature of risks faced by the mining industries provide a strong case for hedging. Only the principles of hedging, such as selling ounces of gold in the ground at a pre-agreed price for delivery at a future date as a cost-effective mechanism for price risk management, is discussed. Progressive and cumulative increases in the volume of forward sales in the major producing countries are considered by many to be the cause of the declining gold price over the past decade. In spite of negative publicity, forward selling continued as an industry-wide practice until recently (2002) when the global hedge book contracted by 352 t; contraction amounted to 158.6 t in first quarter of 2006. The objectives and benefits of hedging include continuity and stability of cash flows, stability in price achieved, reduction of frictional costs, and creating an effective management tool. The importance of a defined hedging strategy in reducing uncertainty about the hedging objectives is essential to a successful hedging policy. Historical patterns in hedging revenues at an industry level indicate five distinct periods during which the fortunes of hedgers have fluctuated. Finally, since 2001 the rising gold price and reduced price volatility through the consolidation in the global price means that the need to stabilize revenue flows is less urgent. This has meant that hedging is becoming progressively less important for the mining industry at large.

Jan 1, 2007

By R. T. Jones

Base metals and platinum group metals can be collected in metallic alloy form, via a wide variety of smelting processes. The recovery, or degree of collection, of the valuable metals is a function of the extent of reduction in the furnace, which, in turn, is indicated by the fraction of iron present in the feed materials that report to the alloy. An equation has been developed that relates the recovery of various metals (such as Ni, Co, Cr, and PGMs) to the recovery of Fe. This recovery equation (for each metal) is characterized by a single parameter (K?) that can either be empirically fitted to the data, or expressed in terms of the equilibrium constant and the ratios of the activity coefficients involved. Data from a number of varied DC arc furnace campaigns are presented to illustrate this behaviour.

Jan 1, 2009

By G. Price

The Building Research Establishment installed a base load cell in a driven cast-in-place pile prior to it being tested under vertical load. The monitored base loads were found to be significantly less than could have been predicted by current design methods. The less than expected capacity was attributed to the drilling out procedure. An electro-level system installed in a second similarly formed pile, provided detailed information on the performance of the pile under lateral load. The information obtained was used to check several current design methods for laterally loaded piles. The findings show the potential dangers of attempting to improve design parameters from only limited performance data.

Jan 1, 2010

By R. F. Hinds

A pressurizing system was designed and built to apply a radial pressure of 5.000 psi to rock samples. Samples of the Bradford, Weir and Kirkwood sandstones were subjected to radial pressures parallel and perpendicular to the bedding in the system and the changes in conductivity, porosity and permeability were deter-mined. Asymptotic decreases in conductivity, porosity and Klinkenberg permeability were observed over the 0- to 3,500-psi range. From these data, the increase of formation factor over the same range was calculated. The cementation exponent expressed in the Archie equation was found to increase with pressu,re. The rate of change varied from formation to formation. Only small differences were observed for samples taken parallel to the bedding as comnared to those taken perpendicular to it except for the Bradford sand. Above 3,500 psi the data are not good enough to tell if the properties continue to fall-off asymptotically or in a different manner. A possible explanation for the probable litnit of the asymptotic rate around 3,500 to 4,500 psi is that this represents the maximum pressure which the formations have unrdergone during their geological life as a result of burial. INTRODUCTION For many years measurements have been made in the laboratory of the properties of oil-bearing sandstones with little consideration being given to whether these properties had been changed when the samples were moved from their original position in the ground to the laboratory. Relatively little has been reported in the literature on the effect of pressure on the properties of sandstones. The changes in permeability for eight typical consolidated oil-bearing sandstone samples with overburden pressure (0- to 15,000-psi range) was presented by Fatt and Davis' in graphical form. In 1953 Fatt' also reported the relationship between porosity and overburden pressure for four typical consolidated oil-bearing sandstone samples (0- to 5,000-psi range). Fatt later described the changes of formation factor and porosity of 20 typical oil-bearing sandstone samples with overburden pressure changes (0- to 5,000-psi range) giving the values of the coefficients and exponents in the Archie' equation, and the more general Winsauer equation', where C, k and m are empirical constants, F is the formation factor, and + is the porosity. During the experiments of this investigation the core was contained in a neoprene rubber sleeve as shown in Fig. 1. It was held between two steel end members which were mounted in a steel cylinder. The unassembled pressure cylinder with its component parts is shown in Fig. 2. The core was insulated from the two steel end members by a Teflon sleeve with a small hole in the

By J. R. Parga

In mineral processing, poor froth-flotation performance translates into both an enormous loss of revenue and an unnecessary waste of the ore reserve. In this context, Bacís Mining Company developed a versatile new, high-performance flotation-cell design that can be incorporated into various flotation circuits. The main feature of this circular cell is that it is comprised of two separate sections, namely, a flotation cell that uses wash water to minimize the entrainment of fine gangue particles into the froth product and an external bubble generator that produces small bubbles of relatively uniform size at a specified aeration-rate. The air/water mixture is blended with the pulp by gentle agitation, so as to enhance particle-bubble aggregate-stability. Comparative metallurgical performance with conventional flotation cells show that the power requirements and operating costs for precious metal flotation are three times lower, while the concentrate grade is 7% higher and the recoveries of precious metals are 5% higher.

Jan 1, 2009

By A. Boniface

The International Tunnel and Underground Space Association (ITA) has a number of working groups (WG) that meet at least once a year. One of these is WG12, ?Use of Shotcrete?, of which the author is a member. The purpose of this paper is to draw attention to a number of topics that were discussed at the WG12 meetings held in April and September 2008; and also to a number of other matters that arose from the presentation of thirty-four papers at the 5th International Symposium on Sprayed Concrete held in Lillehammer, Norway between 21 and 24 April 2008.

Jan 1, 2008

By Tim O’Neil

If you build a big truck, build a big tire to match it. Let that haulage synergy aid the economics, productivity and lessened maintenance for the unit. Now, Cater-pillar and Michelin have done just that. Discussions began in 1996. Caterpillar was making plans for its 797 ultra-class haul truck. The development team realized the need for a tire that could withstand extreme loads. The 797 would weigh 558 t (615 st) and be capable of 64 km/h (40 mph) speeds. So Caterpillar approached Michelin. The two companies realized the benefits of jointly developing a tire for the 797.

Jan 1, 2002

By R. L. Howell, L. C. Atkinson

Typical sedimentary sequences overlying coal seams consist of interbedded sandstones, siltstones, shales, and rider coal seams. In many surface coalmine settings, these sediments are saturated; and prior dewatering of them is necessary for effective and economic mining, including the stacking of saturated spoils. Such sedimentary sections usually have a very low vertical hydraulic conductivity that does not allow them to drain in a timely manner prior to their being stripped. One potential solution is installation of drainwells. Drainwells are small diameter wells that can collect water laterally from the various more permeable layers in the overburden and then gravity drain it to a lower layer – often the coal seam being mined – where it can be removed by pumping wells or sumps located in the bottom of the pit. A ground-water flow model utilizing the 3-dimensional finite element code MINEDW has been used to evaluate the effectiveness of usingdrainwells in a hydrogeologic setting that is typical of the Powder River Basin. A series of numerical simulations were completed using various combinations and spacings of drainwells and pumping wells to dewater the overburden and coal seams. The numerical simulations suggest that drainwells can be a very effective method of overburden dewatering.

Jan 1, 2000

By J. Daavittila

In the latter part of the 1980s Outokumpu Chrome in Tornio, Finland, was in a situation when its twenty-year-old ferrochrome plant was becoming too inefficient to sustain economically sound production. The company made extensive studies on the then available processing methods to find out the best possible processing route. As a result, the whole plant was practically rebuilt and expanded. When equipment was proven in practical operation, an application for FeMn production was developed. Now as the Tornio FeCr-plant is considering expansion, the same type of exercise is to be performed with today?s challenges, which will be discussed in the paper. These challenges include increasing costs or decreasing quality of raw materials, increasing energy costs, stricter environmental regulations and demand for better working conditions. The possibilities of resolving to these challenges will be discussed in the paper. The future and continuing development with FeCr includes the better utilization of process dusts and a lower consumption of energy. By adapting the latest automation tools to better control the process, even higher efficiencies can be achieved with present technology. New processes are considered for development in the future and some possible technologies will be described.

Jan 1, 2004

By G. Bierie

The conveying of bulk materials is prone to problems. These problems can reduce the capacity and efficiency of the plant, and even threaten the health and safety of the workforce. This presentation will look at new conveyor technologies systems, and how, used separately or in combination, they can improve material handling.

Jan 1, 2007