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By Jasper L. Stuckey

PYROPHYLLITE, first identified as soapstone,' later as agalmatolite,2 and finally as pyrophyl-lite, has been known to occur in North Carolina for more than 130 years and has been produced intermittently in commercial amounts for the past 100 years. Pyrophyllite mining, however, has become a major industry in North Carolina only during the past 25 years. North Carolina and California are the chief producing states. Current annual production averages 125,000 tons, of which slightly more than 90 pct comes from North Carolina. Distribution and Geologic Setting: All known pyrophyllite deposits in North Carolina are associated with rocks of the Carolina Slate Belt,' which is composed of a vast series of metamorphosed volcanic and sedimentary materials, occurring as two zones extending in a northeast-southwest direction across the state. The larger of these zones, lying in the central Piedmont region, varies from 8 to 50 miles wide. The smaller zone lies along the eastern edge of the Piedmont region and is partly covered by coastal plain sediments. The rocks in both zones consist of a great volcanic-sedimentary series, composed of air-laid and water-laid tuffs and breccias, lava flows, and slates. On the basis of composition, they may be classed into three groups: 1) tuffs, breccias, and lava flows of acid or rhyolitic composition; 2) tuffs, breccias, and lava flows of a basic or andesitic composition; and 3) water-laid slates composed of fine grained materials derived chiefly from the acid tuffs and breccias and

Jan 1, 1959

The mining industry worldwide is currently facing a significant restructuring process. In most underground mines, widespread mechanization of the mining processes increases production while reducing staff numbers. At the same time, mining depths as well as the lateral spread of the mine workings are increasing. This ever-changing mining environment requires sophisticated solutions for the design and operation of underground mines. In fact, a reduced number of mining engineers is taking responsibility for everincreasing mine operations. This applies not only to the excavation of the minerals, but also to all other aspects of the mining operation, including health and safety, disaster management, and mine rescue organization. Most mining engineering graduates entering the industry lack experience in mine emergency management. Young engineer trainees must learn mine emergency management and rescue work in addition to their normal training experience on the job. Often, and unfortunately, emergency and rescue training at different mining companies is not carried out to the highest level and standard and with the best possible training outcomes. The tasks and challenges a young engineer faces while being trained in a new position do not leave much room for additional training in mine rescue and emergency management. At the same time, experienced, ?old hands? are retiring and cannot easily be replaced due to limited graduation numbers. Strategies are being developed at mining universities worldwide to train mining engineering students in handling mine emergency situations and to provide hands-on experience for managing potential accident and disaster scenarios underground. Two of these strategies, from the USA and from Central Europe, are presented in this paper. These specific strategies have to be seen under special consideration of the local and regional boundary conditions, but might serve as case studies for mining schools and universities in other countries.

Jan 1, 2014

By G. F. Vander Voort

The accident at Unit No. 2 of the Three Mile Island nuclear reactor (TMI-2) on 28 March 1979 was the worst nuclear accident in US history and crippled the nuclear industry. An international Vessel Investigation Project was formed to assess the integrity of the vessel. However, it was not possible to remove specimens from the lower head until January?March 1990. Fourteen of the fifteen specimens removed by electrical discharge machining were from under the debris pile that accumulated on the lower head due to melting of approximately 19 000 kg (45%) of the core. Specimens were previously cut from the lower head of a cancelled reactor of very similar size and design destined for Midland, Michigan. These specimens were subjected to controlled heating cycles with peak temperatures from 800°C to 1100°C for periods of 1 to 100 minutes. The initial study qualitatively compared the structures in the 15 specimens from TMI-2 to the control specimens from the Midland lower head. The writer used the same specimens and employed microindentation hardness traverses, electron microprobe analysis, and selective etching followed by quantitative metallography (by image analysis) to obtain a far more detailed description of the thermal exposure experienced.

Jan 1, 2013

By N. Henderson, J. Weyer, J. F. Brune

"The mining industry worldwide is currently facing a significant restructuring process. In most underground mines, widespread mechanization of the mining processes increases production while reducing staff numbers. At the same time, mining depths as well as the lateral spread of the mine workings are increasing. This ever-changing mining environment requires sophisticated solutions for the design and operation of underground mines. In fact, a reduced number of mining engineers is taking responsibility for everincreasing mine operations. This applies not only to the excavation of the minerals, but also to all other aspects of the mining operation, including health and safety, disaster management, and mine rescue organization.Most mining engineering graduates entering the industry lack experience in mine emergency management. Young engineer trainees must learn mine emergency management and rescue work in addition to their normal training experience on the job. Often, and unfortunately, emergency and rescue training at different mining companies is not carried out to the highest level and standard and with the best possible training outcomes. The tasks and challenges a young engineer faces while being trained in a new position do not leave much room for additional training in mine rescue and emergency management. At the same time, experienced, ’old hands’ are retiring and cannot easily be replaced due to limited graduation numbers.Strategies are being developed at mining universities worldwide to train mining engineering students in handling mine emergency situations and to provide hands-on experience for managing potential accident and disaster scenarios underground. Two of these strategies, from the USA and from Central Europe, are presented in this paper. These specific strategies have to be seen under special consideration of the local and regional boundary conditions, but might serve as case studies for mining schools and universities in other countries."

Jan 1, 2014

By R. J. Balfour, T. L. Papucciyan

"INTRODUCTIONCapital Cost considerations are basic to feasibility in the achievement of success for Mineral Processing Projects as much as or more than in many other industries. Capital cost is an important factor ae it 1R the unit of measurement for process engineering economic decisions. As a result of ever increasing complexity, alternatives of process and remoteness of site, there is an ever increasing emphasis on accurate estimating and the attendant cost control systems in the international market of today for the Mineral Industry where initial plant costs are becoming a more important factor than operating costs. An undervaluation means trouble ahead. An over-cautious assessment may bring an unnecessary abandonment of a project. Consequently, the ultimate cost must be predicted early and accurately and must be controlled to this parameter during the design and construction phases. Cost Est!~ mating is one of a variety of project management tools used to assist in planning and achieving the optimum balance between Quality, Cost and Time, the eternal triangle of evaluation, namely obtaining a project of acceptable quality at minimum cost and on time. In order to attain these established objectives, proper planning, organizing, coordinating, monitoring, adjusting and controlling the design, procurement and construction elements of the project are essential.This project management approach based upon the principle of a Task Force under single management, comprising a complete service organization, requires a substantial number of qualified individuals specialized in their own field and capable of working together as a team to perform their various functions effectively. The Task Force is supported by their chiefs of discipline and performs in accordance with established procedures and standards under the leadership of a Project Manager.General Engineering Company Limited with the backing of the full resources of Surveyer, Nenniger & Chenevert and its total staff of approximately 1,0009 offers the complete project management service to the Mineral Processing Industry of North America and the rest of the world. As mine sites become more remote and difficult of access, the need for an experienced team of specialists who work under the Task Force principle, with well established standards and procedures becomes even more important. Our long history of successful pro1ecta in this field has been our training ground for the fulfillment of this need."

Jan 1, 1972

By G J. Corbett, T M. Leach

Approximately 42 t of mercury were produced from Puhipuhi from the late nineteenth century until the end of World War II, with no significant gold or silver production. Sinter, eruption breccias and veins, mined for mercury at Puhipuhi and essentially barren of gold, are inferred in many geological models to represent the surficial levels of adularia-sericite style low sulfidation gold-silver systems. These systems may contain economic gold-silver mineralisation at depth. Conceptual geological models have been employed at Puhipuhi in the search for buried gold mineralisation. Homestake Mining utilised a McLaughlin model for exploration from 1982 to 1987, targeting mainly the vicinity of the sinter deposits. From 1987 to 1989 BHP sought deeper structurally controlled gold mineralisation within the basement greywackes, utilising models derived from studies of Round Mountain, USA and Hishikari, Japan. Macraes Mining Company Limited have accessed the previous work and applied a conceptual geological which invokes a north-south structural control for the emplacement of high-level felsic intrusions at depth. Dextral movement on these structures associated with oblique convergence facilitated the formation of a pull-apart basin in which lacustrine sediments overlie basement greywackes and are in tum overlain by Pliocene basalts. Continued activation of the NS structures created a series of inferred NE-trending dilational structures, which are targeted as fluid upflow centres for the surficial outflows. Upflows occur as eruption breccias (e.g., Plumduff) and outflow as silica sinters (eg Mt Mitchell, Williams) which are also partly obscured by the basalt cover. Argillic alteration and mercury mineralisation occur at elevated crustal levels (eg Puhipuhi mine). Modelling from structure and alteration zonations have targeted a fluid upflow in the vicinity of Bush Hill, which was not accessed by previous workers. This target was subsequently supported by surface geology and multi-element soil geochemistry.

Jan 1, 1997

By L. F. Ruppert, W. D. Watson, S. J. Tewalt, L. J. Bragg

The U.S. Geological Survey recently completed a digital coal resource assessment model of the Upper Pennsylvanian Pittsburgh coal bed which indicates that of the original 34 billion short tons [31 billion tonnes] of coal, 16 billion short tons [14 billion tonnes] remain after subtracting mined-out coal. When technical, environmental, and social restrictions are applied to the remaining Pittsburgh coal model, only12 billion short tons [11 billion tonnes] are available for mining. Our assessment models estimate that up to 0.61 billion short tons [0.55 billion tonnes], 2.7billion short tons [2.4 billion tonnes], and 8.5 billion short tons [7.7 billion tonnes] could be available for surface mining, continuous mining, and longwall mining, respectively. This analysis is an example of a second-generation regional coal availability study designed to model recoverability characteristics for all the major coal beds in the U.S.

Jan 1, 2000

By D Brouwer, P Wild, B Belle

Due to the steep geo-thermal gradient in Bowen Basin area, as underground coalmines reach increased depths of extraction, the Bulk Air Cooling (BAC) requirements will increase as opposed to cooling the workplace using the ventilation means alone. One such mine has already been using a 4 MW surface BAC plant for the last six years to manage the working temperatures with reduced cooling efficiency as the mine expands. Due to the horizontal nature of the longwall mine layout, distances from the working face to intake shafts are rapidly expanding to over 6 km as opposed to the vertical mine layout of a hard rock mine. To improve the positional cooling efficiency, reduced panel pressure differentials, improved rib emission gas management, and intake dust management, small diameter intake shafts were located on the inbye end of production panels and halfway up the development panels with localised mobile small BAC plants. This paper summarises the results of extensive underground data of this innovative cooling concept for development and retreating longwall face heat management compared to a larger remote BAC plant.CITATION:Belle, B, Brouwer, D and Wild, P, 2017. The use of mid-panel ventilation shafts to improve positional cooling efficiency in a Bowen Basin longwall mine – a case study, in Proceedings Australian Mine Vent Conference 2017, pp 217–224 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By R. S. Bowman, G. S. Austin, J. M. Barker, P. S. Freeman

The physical, chemical and mineralogic characteristics of zeolites allow commercially important applications. While adoption of zeolite technology is slow in the United States compared to other regions of the world, continued testing and research has shown a wide range of uses for these minerals. They are important catalysts in petroleum refining, molecular sieves able to separate gases, and chemically inert carriers of reactants. The zeolite clinoptilolite produced by St. Cloud Mining Company (clino) (SC) is used in animal hygiene and animal feed, especially concentrated animal feeding operations (CAFOs), horticulture, water treatment, floor dry, aquariums, air and other filters, and odour control. Clino can remove cations from solution, and surface-modified zeolite (SMZ) is a sorbent for the removal of anions and neutral organics from water. Specific clino applications are: control of chemical pollution in groundwater, removal of organic compounds from oil field waters, and elimination of pathogens from sewage effluent. Combining the sorption capabilities of SMZ with chemical or biological transformations can yield complete removal of toxic materials from contaminated water. Continued development and marketing of zeolite products will be a growth market far into the future. The CAFO market for zeolites is the most significant growth area in the United States over the next few years. SMZ, currently less than 1% of St. Cloud sales, will continue to gain market penetration for many years.

Jan 1, 2004

By A Hollweg, K H. Esbensen, M Lischka

Two new splitter designs for intercepting moving streams of matter are presented, the variable cross-stream splitter (vCSS) and the rotary stream splitter (RSS), which are intended for implementation in a fully automated modus. The vCSS facilitates obtaining up to three subsamples with different splitting ratios from automated laboratory flow paths, while the RSS divides the intercepted sample into 16 equal analytical aliquots. The splitters can process a wide range of dry, granular and free-flowing materials (<5 mm). The required weight for each subsample can be set without mechanical adjustments in the case of the vCSS. Typical applications are subsampling/splitting for X-ray fluorescence pelletisation (or fused beads) or splitting for average shift composite sampling or grain size analysis. The vCSS combines the advantages of riffle splitting (three user-defined subsample masses) with miniature bed blending and can accept up to 15 kg in total incoming sample mass. In practice, the automated vCSS can deal with unlimited ingoing mass fluxes, while the RSS is designed to operate at a user-defined fixed subsampling rate (1/16th in the tested version). Both splitters have the potential to be optimised and evaluated according to an application/user-defined total sampling error (TSE) + total analytical error (TAE) threshold. Both splitters were tested under adverse conditions and with compositions involving three components with properties representing typical mass fluxes and components concentrations in industrial and technological systems: phosphate concentrate 89.00 per cent (<500 µm), slag ten per cent (>2 mm) and glass spheres one per cent (750–1000 µm). The slag particles vary widely in particle shape, aspect ratio and surface roughness, while the glass spheres are extremely prone to bouncing and segregation (spillage). This test system is extremely difficult to split and thus constitutes a realistic worst-case scenario. While the vCSS does not comply strictly with Theory of Sampling demands for correctness, both splitters may well be able to deliver fit-for-purpose representative results if/when tested properly. Average relative mass deviations ranged from 1.89 per cent for phosphate concentrate (relative standard deviations of 20-fold repeated splitting) to 4.72 per cent for glass spheres and 13.04 per cent for slag. For the RSS, the average replication experiment splitting variation was 2.89 per cent for phosphate concentrate, 4.82 per cent for glass spheres and 11.1 per cent for slag. Both new automated online splitters would therefore appear to be able to be tuned to fit-for-purpose representivity (defined here as maximum relative reproducibility <5 per cent) for many non-extreme materials; however, it is always imperative to test every new type/class of material empirically. There is a wide commercial potential for important materials and commodities sectors, including food, feed, drugs (pharmaceutical), secondary raw materials, recyclates, agricultural products and seeds.CITATION:Lischka, M, Hollweg, A and Esbensen, K H, 2017. New online/atline splitter designs for laboratory automation – feasibility results, in Proceedings Eighth World Conference on Sampling and Blending , pp 159–166 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

The modelling of lithological domains is a critical step in mineral resource and reserve evaluation. Deterministic models rely on an interpretation of the available drill hole data and expert knowledge, but do not account for the uncertainty in the spatial extent of the lithological domains. Instead, probabilistic models based on conditional simulation can be used to map the probabilities of occurrence of the domains within the deposit, which reflect the uncertainty in their presence or absence at unsampled locations. The mineral grade model is then obtained by weighting the predicted grades associated with each lithological domain by the probability of occurrence of this domain. Such an approach accounts for the continuity of the grades proper to each lithological domain and for the uncertainty in the spatial extent of these domains within the deposit. An application to a porphyry copper deposit is presented. Keywords: spatial uncertainty; plurigaussian simulation; geological control; kriging; geostatistics.

Jan 1, 2007

By M. E. Rossi, J. E. Camacho

"Geostatistical conditional simulations are becoming increasingly popular as tools that provide models of uncertainty at different stages of a mining project. They have been used as grade control tools in daily operations to assess the uncertainty of mineable reserves at the project’s feasibility stage, and to assess mineralization potential in certain settings. Other applications include assessment of recoverable reserves, resource and reserve classification, and drill hole spacing optimization studies. All large-scale applications of conditional simulations intend to benefit from the correct (or accurate) characterization of uncertainty, adequately describing the variability observed from the data and its effect on the final objective.The objective of this paper is to compare the ad-hoc uncertainty model provided by a traditional classification scheme with the probability intervals resulting from a conditional simulation model. It is argued that the uncertainty model derived from the use of classification schemes is of little practical use to the mining company or operation. The paper emphasizes differences in uncertainty based on the size of the mining unit considered, the extraction method, and local geological differences. Most importantly, it discusses confidence intervals for these mining units, as compared to the relative precision envisioned by a typical classification scheme.The application described in this paper is taken from a medium-sized Cu open pit and underground mine in northern Chile, and demonstrates the impact of several variables on the resulting conditional simulation models. It also compares a more traditional resource classification scheme applied, and the wide difference in local confidence intervals for each mining unit."

Jan 1, 2004

By D. D. Munro

Finsch Mine is a kimberlite diamond mine located at Lime Acres in the Northern Cape Province of South Africa. The mine was founded in 1961 and started surface mining in 1964. Underground production commenced in 1990 using a modified blast-hole open stoping method for the mining of Blocks 1, 2 and 3. Block 4 is currently being mined as a block cave. The process of identifying and optimizing a method to mine the Block 5 orebody started in 1991, and in 2006 incline caving was identified as being technically feasible. This paper aims to document the process employed in developing this method by the Block 5 prefeasibility team as well as discuss the technical challenges encountered during this process. The paper commences with a history of Finsch Mine and highlights the complex geology and threat of sidewall failure that prompted the decision to use block caving as the mining method for Block 4. A literature study of mines that implemented mining methods upon which the incline cave was conceptualized is then presented. These practices were then used to form the basis for the designs on which the initial geotechnical modelling was done and built upon through an iterative process of modelling and design changes. The ventilation of the mining area, initial productivity simulation results, and the applicability of automation and comminution processes in the incline cave are also presented. The paper concludes with an investigation into some of the challenges of the mining method, and shows that that incline caving is a technical option available for further investigation in determining the optimal mining method to be employed at Block 5, Finsch Diamond Mine. Keywords massive mining, incline caving, geotechnical modelling.

Jul 1, 2013

By E. Douglas, D. N. Collins, J. R. Stevens

E. Douglas (Dept. of Scientific and lndustrial Re-search, Warren Spring Laboratory, Hertfordshire, England) — The authors are to be congratulated on the considerable improvements they have made in tailoring efficiency and selectivity terms which are generally superior to the alternative forms in current use. However, I feel that their efficiency expression is limited to lower-grade feeds; its accuracy reduces as the feed grade increases. For example, its application to such processes as the beneficiation of glass sands, refractories and clays will invoIve considerable inaccuracies. The reason for this lies in the direct use of recovery, which, with high-grade feeds, biases their empirical expression, R(1 - c/h). With a 90% grade feed, the recovery weighting for the slightest degree of beneficiation, over a zero efficiency sampling operation, will be 90+%+ I disagree with their second basic requirement which states that there can be no fundamental basis for any single quantifying expression. A formula giving a comprehensive representation of concentra- tion efficiency can be derived fundamentally accord-to the procedure outlined in the literature. '' This formula, called the Basic Efficiency formula, is

Jan 1, 1963

Jan 1, 1994

By Axel Preusse

On the basis of the Law on Financing Hard Coal Mining dated 28 December 2007, the subsidized German hard coal mining industry will be shut down to the end of the year 2018 in a socially acceptable manner; in 2012 this decision will be reassessed. Even after the abandonment of all mining activities subsequent burdens are inevitable. In this paper, the possible long-term effects resulting from a mining industry history, which is spanning more than 200 years, and their possible consequences are pointed out, in particular in connection with the abandonment of mine water drainage measures which is economically meaningful in the long term. According to the decision situation as it presents itself today, this point in time will be far beyond 2018. In preparation for this, an action framework is to be developed in areas possibly affected.

Jan 1, 2008

By A T. Yuniar, C A. Brannon, N D. Pascoe, H H. Firdausi

This paper describes the key components of the Grasberg Block Cave (GBC) mine design and the development and construction status of the mine. Drawpoint production from GBC will be initiated in 2018 following the closure of the Grasberg open pit. Full production of 160 000 t/d is planned for 2024, which will make it a 20-year time period between initial access development in 2004 and full production.Diluted ore reserves are about 1 Bt at a grade of 1.0 per cent Cu and 0.78 g/t Au. The mine plans some 2400 drawpoints on a 20 m × 30 m drawbell spacing in a 700 000 m2 footprint using the El Teniente layout. The drawpoint opening sequence includes five production blocks, the first two of which are scheduled to be undercut simultaneously in 2018. Ore is transported using diesel-powered load-haul-dumps to a series of orepasses and then delivered via loading chutes to a rail haulage system, which delivers the ore to a three gyratory crusher complex. Crushed ore is transported to the mill stockpiles via dual inclined conveyors.Development and construction of the substantial fixed facilities are now well underway. Primary access for personnel and materials is via the 6 km Ali Boediardjo (AB) adits. A service shaft will hoist personnel and materials from the AB adits level to the various operating levels. Shaft commissioning is scheduled for late 2015. The rail haulage system installation and construction is in progress and is due to be commissioned in 2017, which is timed to coincide with the commissioning of the ore handling system. Ventilation is provided through a series of large intake and exhaust drifts, and two of the four main fans have been commissioned. A 1600 L/s pumping system will manage drainage from the mine.Other key facilities include separate shops for rail and rubber-tired equipment, warehousing, a powder magazine, a main control centre and an underground concrete batch plant.CITATION:Brannon, C A, Firdausi, H H, Pascoe, N D and Yuniar, A T, 2016. Development and construction update of the Grasberg block cave mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 625–634 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

"Quang Ninh province is located in the north east of Vietnam and the coal mining in the province generates two thirds of the province’s GDP. The coal is extracted from both open pit and underground mines for the country’s complete coal export and by a share of more than 90% for domestic coal usage. Overburden generated through open pit mines is piled up nearby in the form of large waste rock dumps. The side-hill fill dumping near open pit mines is the source of environmental degradation in the region. Among the current problems at solid waste rock dump sites are dust emissions during and after dumping as well as Acid Rock Drainage (ARD). One of the major existing problems at waste rock dumps is dump stability (comprising erosion, sliding and subsidence issues). The RAME R&D project (Research Association Mining and Environment in Vietnam) is - among other activities - actively involved in the research for stabilisation and rehabilitation of mine waste rock dumps in Vietnam in the form of several sub-projects. The Institute of Mining Engineering I of RWTH Aachen University is leading the sub-project of mine waste dump stabilisation in co-operation with Chair of Geotechnical Engineering and Brenk Systemplanung GmbH. Mine waste dumping in the form of layers as an alternative to the side-hill fill dumping is expected to bring up environmental and economical benefits by minimising the problems of dump sites with the contribution to a sustainable development. Reduction of the post construction settlements, long term stable dump profile with minimum erosion, improvement of material parameters for geotechnical slope stability through compaction from hauling trucks as well as economical evaluation of new dumping concepts are the areas of the current research. The project has been financed by German Federal Ministry for Research and Education (BMBF). The ultimate aim of the sub-project is the compilation of the project results in the form of a "Best Practice Guide" and software based "Decision Support System" for planning and management of solid mine waste dumps."

Jan 1, 2011

Mine ore, reduced to minus 71/2 in. by primary crushers, is stockpiled. Size reduction of the reclaimed material by secondary and tertiary crushers is achieved in a closed circuit crushing and screening plant. Screen products of minus 30 mm plus 6 mm lump, and minus 6 mm fines are stockpiled by conveyor and stacker systems prior to rail despatch 10 port facilities at Dampier. Crusher settings, determined from experience, are closely maintained to obtain the desired lump/fines ratio. Chemical and sizing analyses from automatically taken samples are used to maintain product specifications. The beneficiation plant upgrades the fines product when this is necessary. The recorded wear life of individual plant components is the basis of a planned maintenance programme.

Jan 1, 1970

By C. G. Dunn

James, Jones, and Leak (JJL) conclude that growth-rate and orientation-distribution data obtained in a steep thermal gradient should be used with caution to account for isothermally produced recrystallization textures. I agree. However, it is not clear whether they conclude a) that the orientation dependence of rate of growth of secondaries in (commercial) silicon iron depends on both temperature and a temperature gradient or b) that, in applying rate data obtained in a steep thermal gradient, the isothermal annealing temperature must be close to the temperature for which the rate data apply. Also, it is not clear what tem-

Jan 1, 1967