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By J. Stacey

This study was undertaken to generate a locally relevant guideline for the socio-economic aspects of mine closure for South African closure practitioners and decision makers. It should also represent a resource for interested and involved stakeholders. Mine closure, and its related post-closure social, environmental and economic characteristics, is part of the lifecycle of mining operations, given the finite nature of the ore resource. Many coal mines are anticipated to close in the next ten to fifteen years in Mpumalanga, as the epicentre of the industry shifts towards the Waterberg. Social aspects of mine closure have been historically underplayed, and under researched. Coaltech thus commissioned two studies, the first of which examined the closure dynamics of 36 mines in Mpumalanga and KwaZulu-Natal in 2006. A follow-up study (July 2007) focusing on Mpumalanga3,4 confirmed some of the results of the first study. It also contained broad guidelines for mine closure covering social and labour planning, job creation, the use of mine infrastructure, developmental incentives, and environmental rehabilitation.

Jan 1, 2010

By D. Boshoff

The ability of an explosive to break rock is influenced considerably by the extent of confinement in the blasthole. It is believed that confinement is improved by the use of adequate stemming. The aim of this paper is to present the results of the first and second stages of developing a stemming performance testing rig for small diameter boreholes. The rig was used to compare and contrast the performance of different designs of products. The results showed that different stemming products have differences in terms of their functionality, which can have a major impact on the efficiency of rock breaking. Two test procedures were used, one through the exclusive use of compressed air and the second using a purpose-built high pressure test rig with small quantities of explosives. Both tests were used to identify and evaluate the ability of various stemming products to resist the escape of explosive gas through the collar of a blasthole. An investigation was done to determine the types of stemming products most commonly used in South African underground hard rock mines, and these products were used during the tests. The first stage of tests using compressed air only did not prove adequate to predict with certainty the pressure behaviour in the borehole of a particular product under high pressure conditions. The purpose-built high pressure test rig also did not prove to be a very effective tool to test stemming products under high pressure conditions. The test rig incorporated only the effect of gas pressure on the stemming product, and excluded the effect of the shock wave. This study therefore proved that to take into account only the gas pressure generated in the blasthole is not sufficient to effectively test stemming product performance.

Jan 1, 2011

By Yael Miron

This report describes laboratory studies by the U.S. Bureau of Mines to determine the suitability of a static oxygen (OJ adsorption test for evaluating the self-heating tendencies of coals. Reliable minimum self-heating temperature (SHT) values from adiabatic oven tests were used as standards for comparison and evaluation. A suite of six coals was tested in the adiabatic oven and in sealed flasks. In the latter tests, both undried and dried samples, in a range of four particle sizes, were examined. Miniature pressure trans-ducers monitored pressures in the flasks, and gas samples taken at the end of the tests quantified all the gases present. An excellent correlation was found between the minimum SHT's and amounts of O2 adsorbed over a 7-day period for dried coals, independent of particle size. In addition, a good correlation was obtained between the minimum SHT's and pressure changes in the flasks at the end of the test for the same coals, also independent of particle size. Based on these results, the sealed flask test can be reliably used to determine the self-heating tendency of a bituminous coal sample.

Jan 1, 1990

By Albert Zima

ACCORDING to recently published statistics, it is predicted that as much oil must be produced during the next 16 years as has been produced during the past 75, in order to satisfy the high rate of consumption of petroleum products. During 1934, over 17,000 oil wells were completed in the United States, and it is expected that over 20,000 additional wells will be drilled during the current year. Were it not for the remarkable progress made during recent years in the improvement of drilling technique and in the development of equipment used in the production phase of the oil industry, it is doubtful whether sufficient oil could be produced to meet present requirements. A few years ago, wells seldom were deeper than 3500 to 4000 ft., owing to the limitations of the drilling methods and equipment employed. Today, however, through the application of scientific drilling methods and the adaptation of modern equipment and improved materials, many wells range from 6000 to 8000 ft. in depth, and a few recent completions exceed 10,000 feet.

Jan 1, 1935

The general nature of the special constructional features that are required to provide safety from explosion hazards on machines approved as permissible by the Bureau of Mines is fairly well known to mining men who are at all interested in safety. These requirements are outlined in the schedules under the provisions of which the investigations of such machines are conducted. Also, the method of conducting inspections and tests of such machines has been described in Bureau of Mines Bulletin 305, Inspection and Testing of Mine Type Electrical Equipment for Permissibility, published in 1929. A more detailed knowledge of the special safety features of a particular machine is often useful and sometimes essential for inspectors, safety engineers, maintenance men, and engineers in selecting machines for a particular application. Three bulletins that give information of this nature have been-published by the bureau, viz., Bulletin 313, Permissible Storage-Battery Locomotives and Power Trucks. Bulletin 343, Permissible Coal-Handling Equipment. Bulletin 382, Permissible Coal-Cutting Equipment. Report of Investigations 3309, Permissible Electrically Operated Air Compressors, which contains similar information, was issued in August 1936, and a Report of Investigations 3326, Permissible Electrically Operated Room Hoists, was issued in January 1937. Thus, the present paper is the third to give detailed information concerning permissible machines of types not included in bulletins, and covers all the rock-dust distributors approved prior to October 1, 1936.

Jan 1, 1937

By William J. Miles

The markets and applications of Wyoming bentonite deposits are primarily determined by the functional properties of a bentonite ore which results from the unique mineralogy and chemistry of each deposit. Commercial bentonite products contain sodium montmorillonite as the major mineral component, with minor concentrations of accessory minerals such as quartz, opal (silica hydrate), mica, feldspar, gypsum and zeolites. The chemical composition of the sodium montmorillonite influences the functional properties of the bentonite in significant ways. The type and concentration of various accessory minerals also influence the acceptability of the bentonite in each market.

Jan 1, 1995

By Charles Stone, Hannes Lagger, Dru Desai

The design methodology of the planned Second Avenue Subway Project (SAS) led to development of the initial support design to estimate cost and quantities in the Preliminary Engineering (PE) stage. Careful selection of the cavern design rules that recognized the impact of rock quality, rock cover, excavation geometry, and excavation sequence helped to overcome the design challenges of large, shallow caverns for the initial ground support. In the course of the design verification process prescribed by the design methodology, the design team was continuously reviewing and updating the support quantities. The design procedure includes methods using different approaches of empirical, continuum, and discontinuum analyses, which are currently advanced in the Final Engineering (FE) stage. The paper is a continuation of the RETC 2005 “Trials and Tribulations” and focuses on the procedures that led to the changes in the initial support as a result of the ongoing design development.

Jan 1, 2007

By T. Wang

A new generated NaNO3 ? NaNO2 ? KNO3 ternary thermal energy storage system which has low melting point as 124°C and high specific heat capacity was studied for the short and long?term thermal stability by using the Thermogravimetric Analyzer (TGA). Based on the actual working condition of molten salt in solar two, the simulated cyclic thermal stability measurement was also conducted. The ternary system demonstrates excellent short ? term thermal stability and thermal reliability after cyclic heating and cooling processes. However, in the long ? term as well as the simulated cyclic stability measurement, large amount of weight loss was observed. Moreover, the stepwise long ? term isothermal study reveals that below 440°C the weight change is minimal and this temperature is viewed as the upper limit temperature of thermal stability for this ternary system. To determine the lost phases at high temperature above the upper thermal stability limit, techniques such as XRD and SEM are used to compare the condition of the salt mixture before and after the long ? term thermal stability study. On the basis of the comparison, it can be concluded that the major weight loss was due to the decomposition of sodium nitrite.

Jan 1, 2012

By G. N. Shannon

Keywords: inclusions, slag, modeling, interfacial energy, capillary force, particle flotation, particle separation A previously introduced model of inclusions separating across a steel-slag interface, developed by Nakajima/Okamura and Bouris/Bergeles, is expanded to include different inclusions shapes (octahedral and plate-like, besides spherical) as well as comparison between model ladle-, tundish-, and mold-slags. Investigation of the relation of these shapes with the interfacial capillary force ? which arises due to the dynamic interfacial energy during separation ? has shown that the force has a significant effect on whether the inclusion separates rapidly or settles at the interface. For the slags considered, the most significant physical property is found to be viscosity, which resulted in fast separation times for inclusions in the mold and ladle slags, relative to the more viscous tundish slag. Particle dissolution (using experimental data) is included in separation modeling.

Jan 1, 2005

By Joe Roby

Rolling disc cutters are the business end of hard-rock and mixed-face tunnel boring machines (TBMs). Since their first successful employment on a TBM more than 50 years ago, disc cutter technology has constantly evolved, allowing modern TBMs to excavate very hard and abrasive rock efficiently. Disc cutters have also been employed successfully on earth pressure balance (EPB) and slurry machines, cutting rock under water and ground pressure. The range of materials excavated by machines today is broader, excavation rates are higher and cutter costs are lower than ever before, proving the value of investment in cutter development. Disc cutters are used on a range of tunneling equipment, from pipe jacked slurry micro-TBMs less than 1 m (3.3 ft) in diameter to 15 m (49 ft) in diameter, hard-rock boring TBMs. The geological conditions under which they are employed range from sands and gravels, with several bar of water pressure, to extremely hard, massive rock with UCS up to 420 MPa. Regardless of the type of machine or geology, one thing remains constant: changing worn out cutters is costly. When cutters must be changed in the middle of a tunnel, the contractor incurs the cost of downtime as well as the cost of refurbishing or replacing the cutters. In the case of catastrophic cutter failures, the project can be stopped completely for long periods, and the costs mount up rapidly while tunnel production is at a stand still. Catastrophic cutter failures include the occasion when hard-rock disc cutters are failed in groups (called a ?wipeout? phenomenon) and the operator fails to stop the machine, which results in severe damage to the cutterhead. The cause of this can be either an undetected failed cutter propagating damage to surrounding cutters or operator error in steering. Regardless of the cause, the resulting damage can take days or even weeks to repair. When cutters fail prematurely on EPB or slurry machines in certain geological conditions, it is impossible to evacuate the chamber and, therefore, impossible to get [ ] into the chamber to change the cutters. The solution is frequently an unplanned intervention shaft that must be sunk at great cost. The importance of being able to predict cutter life accurately, and in all geological conditions, cannot be overemphasized. For these reasons, cutters have been developed for specific machine types and sizes, as well as for specific geological operating conditions. Different size cutters are required for different size machines. For example, while 483- and 508-mm (19- and 20-in.) cutters are used on large diameter TBMs, it is impossible to employ cutters so large on a small micro-TBM. Also, the cutter must be designed for the specific geological conditions under which it will be operating. The disc cutter rings required to bore extremely hard rock are the most expensive of cutter rings. However, they provide little advantage in weaker rock formations where less expensive rings will do the job as well. It is important to choose the correct cutter for the machine and the geological conditions in order to get the best balance of cost and risk.

Jan 1, 2009

Jan 1, 1964

By A R. Heath, I Arbuthnot

Feed slurries are typically flocculated in a thickenerÆs feedwell to increase the settling rate, underflow density and overflow clarity. High molecular weight polymeric flocculants are normally used, but present a number of challenges in terms of make up, dilution, delivery and mixing with the feed slurry.Various aspects of the flocculant dilution and delivery system have been studied with a combination of flow visualisation and computational fluid dynamics (CFD). An open topped flocculant dilution/mixing box has been developed to replace a conventional flocculant manifold, with improvements to the mixing, fault diagnosis and ease of determining the flow split to the various dosing points. The addition points to the feedwell have also been studied, both in terms of where the flocculant is added, and how. While conventional multi-hole spargers are effective in dispersing flocculant, they are prone to blocking and have been replaced by open-ended pipes. The required dispersion is provided by an efficient mixing element placed in the dilution port. Adding the flocculant into the feedwell dilution stream prior to mixing with the slurry also provides super-dilution of the flocculant that can further improve the flocculation process and reduce flocculant consumption.CITATION:Heath, A R and Arbuthnot, I, 2013. Advances in thickener flocculant delivery, in Proceedings MetPlant 2013 , pp 86-92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By G. L. Smit

The Buffelsfontein Gold Mining Company is situated in the Klerksdorp district of the Province of the Transvaal in the Republic of South Africa, approximately 100 miles west of Johannesburg. Gold production commenced in January 1957 and Uranium treatment of residue slimes as a by-product started in July 1957. The mining property is 5435 mining claims in extent, the equivalent of 7988 acres or 12.5 sq miles. The mine was initially exploited by the Pioneer Twin Shaft System, consisting of a 26-ft diam down-cast shaft and a 22 ft-diam up-cast shaft, sunk in the north-west area of the mine to cater for the hoisting and ventilation requirements for a milling rate of 150,000 tons per month. To exploit the Eastern zone of the property and assist in increasing production to 200,000 tons milled per month, it was decided to sink a further Twin Shaft System consisting of a 28-ft diam downcast shaft and a ventilation up-cast shaft -22-ft in diam, both monolithic concrete lined — 200 ft apart and 5300 ft deep. This paper deals with the sinking and commissioning of these Eastern Twin Shafts. This was achieved by one sinking crew within a period of 20 months. A) PLANNING 1) Siting: The Eastern Shaft System was sited in the north-east area of the property, 12,000 ft east on strike from the Pioneer System. (Fig. 1). Initially the system was sunk to the 5300 ft elevation to conform with the original Pioneer Shaft System. On completion a sub-vertical main shaft will be sunk to the 8000 ft elevation in the immediate vicinity, and subsequently the surface ventilation shaft will be deepened to this elevation by raising from level to level and sliping to full size. The exact positions of the shafts were chosen after: a) underground development had located certain known water bearing zones, and b) geophysical and topographical surveys had been carried out. The shafts passed through the following geological succession: Surface to 4430 ft - Dolomites of the Transvaal System 4430 to 4470 ft - Quartzites and conglomerates of the Black Reef Series of the Transvaal System. 4470 to 4470 ft - Diabasic Lava of the Venters-dorp System (Ventersdorp Contact Reef at base). 4470 to 5250 ft - Quartzites of the Elsburg Series of the Upper Witwaters-rand System. The shafts were sited to ensure that the least possible water would be encountered during sinking, and this contributed to the rapid rate of sinking. 2) Duties: a) The 22-ft diam ventilation shaft was designed to up-cast 1,400,000 cfm of air (0.060 density) against a resistance of 22 in. water gauge. b) The main shaft was designed to handle 160,000 tons hoisted per month as well as the men, material and down-cast ventilation to serve this tonnage. The 284 diam main shaft is equipped with streamlined buntons spaced at 15 ft centers set in pockets which were left during sinking. There are six compartments, four of which are sewed by two dual purpose hoists, hoisting either, twedeck man cages or 13-ton bottom discharge skips. The other two compartments are served by a single purpose winder hoisting double deck cages accommodating 60 men per deck. (Fig. 2). 3) Timing: Permanent equipment was ordered well in advance to insure continuity in the operation. Development underground reached the shaft positions before the start of sinking operations. From this development, boreholes were drilled into shaft positions to drain off water in the vicinity of the shafts. To ensure complete co-ordination of effort, all relevant data, as well as the allocation of responsibility, were made known to all persons and departments concerned. 4) Models: The extensive use of scale models during the preliminary planning stages proved most useful in deciding on design such as buntons, bunton pockets and guide cleats, and complex layouts concerning loading, spillage and pumping arrangements. (Fig. 3). These models also proved invaluable in determining the walling routine. Normal working conditions could

Jan 1, 1964

The application of biogeochemical methods in mineral exploration in semi-arid to arid environments in Western Australia has been investigated in an area near Norseman.The study involved a comparison of trace element characteristics of rock, soil and plants in the vicinity of the Pioneer BB prospect, where nickel-iron sulphide mineralization occurs in a "greenstone" sequence of ultrabasic, basic and sedimentary rocks.Analyses of unweathered and partly weathered rock from diamond drill cores show the ultrabasic rock to be highly variable with respect to Ni, Cu, Co, Zn and Mn.Samples of weathered bedrock and overlying soil were analysed for total trace element contents and for the trace elements associated with secondary iron and manganese oxides. Approximately 30 per cent of the total nickel content of the weathered basic rock is associated with secondary iron and manganese oxides, compared with approximately 15 per cent in the weathered ultrabasic rock.The soil has a sufficient residual content to provide a reliable indication of the chemistry of the underlying rock. Total trace element analyses of the -89 mesh fraction show strong anomalies for nickel and copper over the mineralized zone. Important amounts of nickel, cobalt and, to a lesser extent, copper are apparently associated with secondary iron and manganese oxides in the soil.Melaleuca sheathiana (tea tree) has been used to study the relationship between soil and plant chemistry. No strong relationship between plant and rock type was observed. Analyses were made of leaves, twigs, wood, bark and roots, and all plant organs were found to have anomalous nickel and copper contents near the mineralized zone. Leaves were found to give the best contrast in the anomalous area and to show fewer erratic values than other organs. It is concluded that the uptake of trace elements by tea tree is low in the semi-arid to arid environment of Western Australia, but that analyses of the plants do reflect the presence of mineralization.

Jan 1, 1973

By S. S. Gajin

The paper deals with parametric vibrations of an axially loaded pile. The dynamic model is derived by means of Hamilton's principle and reduced to a partial differen­tial equation with variable coefficients and corresponding initial boundary conditions, taking into account the influence of the axial force. By means of Galerkin's method, the partial equation is further reduced to a Matheu-Hill's matrix partial differential equation of the second order. Since the problem of the dynamic stabili­ty has been expressed only for standing piles, the paper analyses in detail two stan­ding piles, one which is restreined, whereas the other is hinged at the toe. In both cases it is assumed that head horisontal displacement is prevented. Using Ruunge-Kutt's method, a computer analysis in the time domain is given for the characteristic parameters and possible boundary conditions. The paper analyses the stationariness of the process, as well as the dependance of the critical excitation frequency upon the pile parameters. The results have been illustrated by respective diagrams.

Jan 1, 1989

The Pilbara Block is a nucleus of Archaean rocks which lies in the North West Land Division of Western Australia, and it constitutes a mineral province that has been divided into two areas-the West Pilbara Goldfield and the Pilbara Goldfield.In the West Pilbara Goldfield two contemporaneous environments are represented by laterally equivalent volcanic and sedimentary successions which together comprise the Roebourne Group. The two successions are lithologically similar to the classical Warrawoona (volcanic) and Mosquito Creek (sedimentary) successions of the Pilbara Goldfield; but in the West Pilbara Goldfield there is no sign of the erosional break which separates the Warrawoona Succession from the Mosquito Creek succession. The Roebourne Group and the igneous rocks which have intruded it belong to the Archaean Pilbara System.Evidence of preconsolidation movement and igneous intrusion into unconsolidated sediment suggests that tectonism and igneous activity, localized along lines of fracture in an unidentified basement, beganbefore lithification was complete. Movement was primarily vertical, and persisted into the Lower Proterozoic.Vulcanicity and chemical sedimentation, accompanied by a diminution of detr:tal sedimentation, is thought to have caused a relative enrichment in the metal content of the middle part of the Roebourne Group; and the metal may have been remobilized during diagenesis and metamorphism, and localized in zones of dislocation formed both before and after consolidation of the sediments.INTRODUCTIONThe name "Pilbara" has been widely applied in the area under discussion, and to avoid confusion the various uses are summarized below.1. The town of Pilbara, now abandoned, was a centre of mining between 1888 and about 1914. It lies some 90 miles FJSK of Roebourne (Fig. 1).2. The original Pilbara Goldfield was modified several...

Jan 1, 1965

By Filip Rochette, Yvan De Busscher

Extraction of minerals can be achieved by a variety of technologies; one of them is ion exchange. There are several ion exchange configurations and mechanical set-ups available, but only one technology will provide more process performance and flexibility compared to the other. The multiple column Continuous Countercurrent Ion Exchange (CCIX) technology provides the highest form of process flexibility with also the highest mineral recovery feasible through ion exchange. In comparison with a fixed bed system, the PuriTech CCIX system offers the benefits of continuous counter-current contact mode. This way the resin capacity is fully exploited leading to reduction in resin inventory and, at the same time, in chemicals and water consumption, and product dilution. For any set of operating conditions the mass transfer zone has a characteristic length (MTZL). The MTZL can be expressed in duration, column length, or volume, but is the measure of the quantity of resin in the system that is doing "work" at any given moment in the process. The objective of continuous ion exchange processing is to eliminate all resin volume from the process equipment that is not within a mass transfer zone. In most commercial ion exchange processes for the recovery of metals, CCIX engineering can eliminate as much as 20 - 80 % of the ion exchange resin inventory. Consumptions of water and chemicals are typically brought down around 40% or more. For each type of resin the selectivity/affinity towards a particular metal depends on the basic process conditions such as pH, concentrations of other competing metals in solution. By changing the pH in the ion exchange process phase, the selectivity of the resin can be changed. By doing this, a split elution, or extraction of metals separately can be achieved and the effect of other competing metals (cross-contamination) can be reduced. For example the DOW resin XUS43578 is commonly used for the recovery of copper or nickel/cobalt separation.

Jan 1, 2016

Triboelectric Separation - Beneficiation of Coal The performance of triboelectric separators is highly sensitive to the selectivity of the particle charging process. This paper presents a quantitative study on triboelectric coal beneficiation. The performance of different charging media was studied. Stainless steel was identified as having a work function between that of coal and silicate gangue and found to be the optimum charging medium for coal beneficiation. Recent results from separation tests were performed where silicate gangue was separated from crude coal using a parallel plate free-fall separator are illustrated.

Sep 13, 2010

The project to reopen the Tasmania Mine has centred around efforts to reopen the Hart Shaft to access the high grade reef remaining below the old workings, which extend down to 457 in. Efforts in 1982 and 1987 were frustrated by unstable clay ground around the shaft, which resulted in significant subsidence of the shaft collar and lining. A successful program has since been implemented to solve the problems, stabilize the collar and recover the upper shaft which had collapsed down to 90 m.

Jan 1, 1989

By K. Nielsen

The paper presents a brief overview of the mineral industry in Norway, followed by a description of the mineral policy and relevant legislation including the roles of the Norwegian Directorate of Mining and Geological Survey of Norway in this context. The discussion then proceeds to describe the land use planning framework on a national, regional and local level, the interaction between land use planning and the Directorate of Mining and the Geological Survey respectively, and how this impacts on the mineral industry and the exploitation of mineral resources. Some recent Norwegian examples of land use planning conflicts are also presented.

Jan 1, 2005