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By S. E. Phillipson

During the course of evaluations by the Mine Safety and Health Administration’s Roof Control Division, the controls on ground instability were investigated at surface and underground limestone mines throughout the eastern and southern United States. Structural geologic features, including joints and faults, were identified by basic geologic mapping as primary controls on highwall and back instability in surface and underground limestone mines. By comparing the spatial orientation of discontinuities and internal angle of friction with the orientation of highwalls on a stereonet, the potential for sliding, toppling, and raveling failures was evaluated in a semi-quantitative fashion. Structural geologic mapping identified faults and joints, which dismembered the back and were associated with ground instability, in underground mines. This paper documents the importance of recognizing structural geologic controls on ground stability in limestone mines, advocates basic geologic mapping as a critical component of ground control programs at surface and underground limestone mines, and provides examples of simple stability evaluations using the stereonet method.

Jan 1, 2006

By Dunlop GA

Pilot Plant confirmatory testing of the treatment route developed in the Metallurgical Laboratory is an essential factor in the development of complex ore bodies. Objectives should be well defined to permit the efficient planning and cost effective operation of the pilot plant project. The primary objective for the pilot plant should be to confirm the viability of the developed flowsheet on a continuous basis, examining only major variables such as ore types, quantum changes in grind, comparison between bulk and sequential flotation circuits, use of flotation columns, evaluation of autogenous grinding and production of samples of concentrates for market evaluation. Secondary objectives may include the collection of engineering design data and the production of a comprehensive report to Bankable Document standards to provide technical support for capital financing. The complexity of the ore body and the scale of the final operating project together with the pilot plant objectives will determine the extent of the pilot plant operations. The level of expenditure associated with a pilot plant can vary, in total cost and as a percentage of the total development capital investment required to take the prospect from exploration to a producing mine. Factors contributing to expenditure are discussed. Associated with cost considerations is the level of confidence mining company investors can have that their capital investment will return dividends.

Jan 1, 1990

By M. Ayhan

Drums of a modern longwall shearer are manufactured to include various constructional features conveying extracted material onto the face conveyor as efficiently as possible. Designing a drum with a conical shell or with reduced vane length, consequently with a stepper vane angle, is the most widely employed method in an attempt to increase loading efficiency. This study compares loading performances of two such drums, one having a conical shell with modified loading vanes, the other with a cylindrical shell with reduced vane length. Firstly, the loading performances of drums are predicted and the maximum haulage rate attainable with the drums are calculated. Then the performances of drum are compared by long-term comprehensive underground trials with coal shearers under similar conditions during the production operation of Park Termik Cayirhan coalmine in Turkey. Although higher loading performance is predicted for cylindrical drums, the in situ trials point out that Globoid drums have a slightly higher loading performance than cylindrical drums. Furthermore, the relationship between operational variables, i.e. extraction height, sumping depth, haulage rate and in situ loading performance, were investigated statistically on the basis of data gathered during the underground trials. Keywords: longwall mining, shearer drums, loading performance.

Jan 1, 2006

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

Jan 1, 1981

The Hill 50 Gold Mine is situated at Boogardie, 3 miles on a bearing of 295 degrees from; Mount Magnet township. Mount Magnet lies 300 miles north-north-east of Perth, Western Australia (Fig. 1).The older workings of the mine may be identified with those of Sirdar, Gold Mining Lease 696M The Sirdar had been worked before 1902 though no records remain, and irom 1903 to 1912 about a thousana tons at a grade of 6' 2 dwt. was extracted annually; by the end of 1918 6,225 oz. of gold had been obtained from the milling of 17,852 tons of ore. In view of these yields, and the length and width of the lode, this mine was early recognized as one of the most promising in the district. From 1919 to 1924 the ground,including G.M.L. 1282M, was held as Mt. Zion G.M.L. 1183M.The Hill 50 Gold Mine N.L. company took up the workings as Hill 50 G.M.L. 1282M in 1934 and have continued operations to the date of writing. To the end of 1956 the Hill 50 Gold Mine had yielded 982,106 tons of ore for a return of 448,'602 fine oz. of gold.The mine has been described by: J utson (1915), Feldtmann (1920), Johnson (1949), and Finucane (1953). Finucane (1953) details the mine structure to a depth of 414 ft. The author was able to examine the mine to a depth of 1305 ft. Detailed main level mapping to the 1060 level and a detailed surface examination have revealed aspects of the structure which were previously obscure.

Jan 1, 1960

By C. G. Anderson

"As demand for copper and precious metals continues to grow, the need to develop new supplies increases. In the imminent future, the new large global ore bodies are more complex, with enargite, tennantite and tetrahedrite as the abundant contained mineralogy. These resources also contain considerable gold and silver. As such, direct treatment by conventional smelting is prohibitive due to the potential environmental impacts and copper quality issues. This paper outlines the effective application and associated economics of industrially proven Alkaline Sulfide Leaching (ASL) hydrometallurgical technology to an enargite concentrate for selective removal and recovery of arsenic, antimony, gold and silver, leaving a clean high-grade copper concentrate. The fundamentals behind the technology are described, along with those of hydrometallurgical arsenic fixation and stabilization. Flowsheets and unit operations are elucidated, along with an in-depth economic analysis. INTRODUCTION Hydrometallurgical methods can be employed for treatment of gold-, arsenic-, antimony-, tin- and mercury-containing materials, concentrates and ores, as well as complex ones containing any number of metals (Conner & Anderson, 2013). The alkaline sulfide leaching (ASL) system is one of these. It is essentially a mixture of sodium sulfide and sodium hydroxide with other meta-stable alkaline species as required. This is a unique hydrometallurgical system beause it is a very selective lixiviant for the distinct leaching of tin, gold, antimony, arsenic, tellurium, silver and mercury (Anderson, 2000, 2001a, 2001b, 2002, 2003, 2012, 2014; Anderson & Twidwell, 2008a, 2008b, 2010; Anderson et al., 2004, 2005; Glazkov & Tseft, 1961; Gnatyshenko & Polyvyanni, 1961; Nadkarni et al., 1975; Nadkarni & Kusik, 1988; Polyvyanni, 1963). Worldwide, ASL technology has been employed industrially in the former CIS, China and the United States for the production of antimony (Anderson et al., 1992, 1994; Anderson & Krys, 1993; Holmes, 1944; Kaloc, 1967; Nordwick & Anderson, 1993; van Stein, 1971)."

Jan 1, 2015

By R. J. Jewell

The storage capacity of any given tailings storage facility (TSF) is a function of the volume available for the tailings, for which the geometry of the final upper surface of the tailings is most important. One of the advantages that can be obtained from thickening tailings prior to discharge is that the tailings can be stacked at a steeper beach angle than is obtainable with conventional low-density slurries. However, there is at present no universally accepted method available for the accurate prediction of tailings beach slopes. This paper examines the current situation with the objective of putting the quest for a method for the accurate prediction of beach slopes into perspective. The paper references published reviews of the best-known beach slope prediction methods. However, there do not appear to be any independently verified projects or published references to projects on which a Class A prediction has been validated for any of these approaches, and in those instances where projects have been implemented correlation of actual with predicted slopes has been poor - often due to differences between the properties of the tailings assumed in the design and those actually achieved in the field. The author also concludes that flume-scale testing cannot be taken as a reliable indicator of full-scale performance, and suggests that the outcome of any current predictive method should be used by experienced practitioners as only one of a range of indicators in order to suggest a range of slope angles likely to result for any given operation. Practice has shown that it is possible to manipulate beach slopes by changes to the disposal technique, such as limiting the rate of discharge per discharge point and by increasing or decreasing yield stress, but the impact of these changes cannot readily be predicted. There are also newly emerging technologies, such as the injection of a polymer into the tailings at discharge, that will enhance the dewatering of tailings and hence expedite the consolidation of the tailings, that could well facilitate the development of steeper beach slopes. The overall conclusion is that with the current state of knowledge, the accurate prediction of beach slopes is not possible. Furthermore, in view of the inherent variability of the tailings parameters from any operation, it may well be of more value to concentrate on developing an understanding of the means by which the tailings parameters may be manipulated by the operators to achieve a given beach slope than to concentrate wholly on developing a generic beach slope prediction model.

Jan 1, 2012

By D. A. Bruce

The Deep Mixing Method is a very valuable tool for combating problems related to in situ soil treatment, improvement, and retention. Many different variations are used throughout the world, and there is a correspondingly rich technical literature on the testing and properties of the treated soil. This paper provides a synopsis of these aspects.

Jan 1, 2001

By Brad R. Blair

This paper will review impacts on longwall design and ground stability assessment due to advances in mine automation and sensing technology. Several new approaches to the prediction and monitoring of longwall panel and gateroad stability have recently become mature, and are ready for application in problematic ground control situations. These methods are revealing significant detail regarding deformation and failure mechanics of critical underground structures. Examples of how these technologies have worked successfully will be given, and applications for the use of these tools for cost-effective engineering design and monitoring will be suggested.

Jan 1, 1996

By Khaled Morsy

Cementitious seals are made of foamed cements with strength ranging from 100 to 600 psi. These cementitious seals are usually used at locations where the seal will be subjected to some convergence, assuming that this material can absorb entry closure without compromising the structural integrity of the seal. Prior to 2006, Lake Lynn Experimental Mine (LLEM) conducted full-scale tests on various cementitious seals designed to meet or exceed the 20-psi horizontal static load requirements of the old 30 CFR1 75.335. Both hydrostatic and dynamic loading tests were conducted. The structural response (pressure and displacement readings) obtained from these tests were recorded. The stability of the cementitious seal is based on balancing the load applied to the face of the seal from the explosion against the shearing resistance at the seal/rock interface. Therefore, the properties of the seal/rock interface, such as stiffness, cohesion, friction, etc. are critical to determine the stability of a cementitious seal. These properties are usually assumed by the researchers in their models. This paper emphasizes the importance of having the correct properties of seal/rock interface in the numerical modeling. FLAC 3D models were developed to simulate Celuseal2 cementitious seals subjected to both hydrostatic and dynamic loadings. Using the hydrostatic and dynamic loading test data conducted at LLEM, the static and dynamic properties of the seal/rock interface were back calculated. The FLAC 3D models showed good agreement with the test results.

Jan 1, 2009

By Gordon R. Sima

This contract is concerned with the construction of a Time Resolved Audio Dosimeter System consisting of one readout unit and several dosimeter units. The Time Resolved Audio Dosimeter System was designed and developed by the Bureau of Mines with the purpose of this contract aimed at obtaining additional units for further field testing and evaluation. All construction was in accordance with the Bureau of Mines design and/or Bureau approved drawings produced during the course of this contract. This report contains a summary of the construction efforts, problems encountered, recommendations and all drawings produced under this contract.

Jan 1, 1977

The income of the Institute is derived from dues, subscriptions to MINING AND METALLURGY and sale of publications. These sources are fortunately supplemented by the interest from invested funds now amounting to over $500,000, a considerable portion constituting endowments for especial purposes. Aside from the medal funds the principal endowments are the James Douglas Fund for support of the Library, the Rocky Mountain Fund and the Seeley W. Mudd Memorial Fund. The income from the two last named is available for the support of research and a variety of other purposes. It is allocated by the Board of Directors upon recommendation of standing committees in each case. An active effort is being made to increase the endowments of the Institute, it being felt that unusual opportunities exist for research and public and professional service through the organization.

Jan 1, 1936

By Rajagopala Reddy Kallu

After the Sago and Darby No. 1 mine incidents, the new regulatory standards for the design of mine seals in underground coal mines of the United States require the mine seals to withstand higher explosion standards. This necessitated for the development of new design approaches and standards. For development of any new design standards or approaches a detailed understanding of effect of key influencing parameters on the stability of mine seal is a must. This paper attempts to address one of the factors, i.e. roof convergence, that play an important role in the stability of mine seal under explosion loading. Initially a couple of three dimensional numerical models were built and tested for different levels of roof convergence. These models confirmed that roof convergence has great influence on seal stability. A detailed study is undertaken, with some simple assumptions, to establish typical influence of roof convergence on the stability of mine seal under different levels of static explosion pressures. Three dimensional distinct element code 3DEC is used for this purpose.

Jan 1, 2007

By F. F. Roberto

Many techniques that are used to characterize and monitor microbial populations associated with sulfide mineral bioleaching require the cultivation of the organisms on solid or liquid media. Chemolithotrophic species, such as Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans, or thermophilic chemolithotrophs, such as Acidianus brierleyi and Sulfolobus solfataricus can grow quite slowly, requiring weeks to complete efforts to identify and quantify these microbes associated with bioleach samples. Real-time PCR (polymerase chain reaction) assays in which DNA targets are amplified in the presence of fluorescent oligonucleotide primers, allowing the monitoring and quantification of the amplification reactions as they progress, provide a means of rapidly detecting the presence of microbial species of interest, and their relative abundance in a sample. This presentation will describe the design and use of such assays to monitor acidophilic microbes in the environment and in bioleaching operations. These assays provide results within 2-3 hours, and can detect less than 100 individual microbial cells.

Jan 1, 2009

By D. M. Doyle

A study of the various components contributing to energy costs and their relationships to generally trended operating data, such as tonnage, operating costs, etc., over progressively shorter time periods provides information for an energy audit. A study of annual data gives some insight into the importance of various energy components. As the time frame of the study progresses through monthly, daily and, finally, into quarter hourly data, the variations become more evident and, most important, strategies develop to minimize energy costs. The results of an audit conducted during the summer of 1978 at Wesfrob Mines Limited are reported to illustrate this important phase, prerequisite to a meaningful energy cost avoidance program. The balance of the paper deals with the energy conservation program at Falconbridge Nickel Mines Limited's Sudbury operations, the metering and control equipment, the commitment, the new energy accounting practices and, lastly, the policies. Examples of successful energy conservation endeavours include automatic peak electrical load control, waste heat recovery from mine air and compressor cooling water, energy reductions resulting from lower building temperatures and curtailment of idling loads. The use of pulse meters to measure the flow of gas, steam, compressed air and electrical energy, with their signals interfaced to process computers, allows monthly, daily and, if necessary, immediate reporting of energy and energy per unit of production information The program so reported at Falconbridge's Sudbury Operations is credited with an annual cost avoidance of .9 million dollars in a 14.0-million-dollar annual energy account

Jan 1, 1979

By K. Lombard

"‘Roof support awaiting time’ (RSAT) is a term used at Goedehoop Colliery’s Simunye Shaft to describe the potential production time lost due to the continuous miner (CM) standing idle waiting for roof support to catch up. Investigations revealed that in 2013, Simunye Shaft had approximately1400 hours of RSAT, which suggests that the mine could have potentially produced an additional 280 000 t of coal. This project consisted of two parts. Firstly, the causes of the high RSAT and means to improve the situation were investigated. Secondly, as insisted by mine management, the CM cutting sequence was investigated as a possible cause of high RSAT. Machine-related challenges due to the roofbolter installing support too slowly, geological conditions (mostly hard roof conditions and slips),logistical challenges pertaining to the CM cutting sequence, man-related challenges related to operator fatigue, re-support, operator inexperience, and the absence of support targets were identified as main contributors to RSAT. Furthermore, results showed that the roofbolters in the sections at Simunye Shaft are slower than the CMs. A target of 28% reduction in RSAT was set. Experts from Kennametal and Fletcher were consulted to find solutions for the identified causes. In total, eight solutions for RSAT were identified, but the solution that contributed most significantly to reducing RSAT was to use hard roof drill bits as a standard product at Simunye Shaft. Calculations showed that by using hard roof drill bits, RSAT can be reduced by 43%, which is more than the specified 28% target. The cutting sequences at Kriel, Greenside, and Simunye Shaft, togetherwith three newly developed cutting sequences, were simulated using the UCMS (Underground Coal Mining Simulation) program. A re-aligningprinciple was incorporated into the newly developed cutting sequences toalign the cutting sequences to general support work and to reduce RSAT. A decision matrix revealed that a cutting sequence in which boxing takesplace in R3 (third road to the right of the belt road) and in which the re-aligning principle has been incorporated will be the best option for Simunye Shaft. The recommended cutting sequence will lead to a 5% increase in production.The work presented in this paper was carried out as partial fullfilment for the degree BEng (Mining Engineering)"

Jan 1, 2015

By Harvey T. Gracely, Mark J. Woodhull

DURING the past few years a marked refinement has taken place in the design of electric power shovels for the mining industry, increasing their digging ability and speed of operation without adding to their total weight. The increase in pay load has been accomplished by a more rigid engineering analysis of shovel design, involving the adoption of new special alloy steels, new sections, and new welding methods. Emphasis has been placed on lightness with increased strength, which is most clearly shown in the front-end equipment where dipper, handle and boom are new in design, material, and construction.

Jan 1, 1938

By S. Bellec, P. Champagne, J. Châteauneuf, A. Berton, S. Fortier

"The start-up of new plants, extending from the commissioning of equipment to the production ramp-up, is a critical period where the processing circuit operation must be done in a structured and well controlled way to enable the gradual, safe and rapid achievement of production targets. The magnitude of the many risks associated with this pivotal period is accentuated in the actual context of low commodity prices. However, the implementation of a method that analyzes risks associated with a start-up, their probability of occurrence and their impacts leads to the identification of a series of preventive actions that can be applied in order to reduce potential negative impacts.Soutex has been involved in numerous start-ups over the last few years and has developed a structured methodology to assess this crucial period, maximize the pre-start-up preparation, ensure a smoother and safer ramp-up period and minimize the time needed before reaching commercial production.This paper describes a method to identify preventive actions to apply in order to reduce risks related to a plant start-up. Then, the various steps of the method are demonstrated using the industrial case study of the Canadian Malartic gold plant situated in Abitibi, Québec. The specific preventive actions, during start-up, the organisational measures and the ramp-up plan are detailed as they were effectively achieved. Finally, the post start-up actions are presented as well as some key results illustrating the achievement of their prior defined objectives.IntroductionPlanning a new plant or new circuit start-up in a mine installation involves various risks, both at the economical and safety levels. Unprepared staff and equipment can lead to safety issues that could threaten plant staff as well as the environment. Moreover, a poorly prepared start-up could often lead to equipment break-down, production stoppages and delays, leading to important economic impacts, delaying commercial production and therefore affecting directly the profitability of mining projects.It is common in the industry to have structured commissioning procedures for major equipment taken separately. Technical personnel from the equipment manufacturing company would usually come on site in order to perform the pre-operation verification, dry runs and the first hours of operations. This kind of assistance is usually focussed on one piece of equipment and neglects the interactions between the various equipment of the production chain. The commissioning phase is usually maintenance oriented and the information given by the manufacturing representative seldomly flows through the operation staff (in the case of this paper, the denomination “staff” refers to both managing and operating employees). The global process is usually not taken into consideration by the technical personnel sent on-site by the manufacturer during the commissioning phase. Many papers can be found describing the commissioning of new equipment focussing on the technology (Côté and Adante (2009), Wells et al (2007)) but without dealing with its integration process in the complete production chain."

Jan 1, 2016

Jan 1, 2000

By Jürg Schlumpf

Concrete is one of the decisive construction materials, also for the AlpTransit Gotthard Tunnel. The client has many requirements, and many are the solution possibilities that concrete systems can offer. Cement producers and concrete admixture manufacturers have been challenged to design and test jointly concrete systems for cast and sprayed concrete. The testing operation followed the scenario laid out by the Gotthard AlpTransit Project management?s instructions ?Testing system for concrete mixes.? Various supplier teams have applied for the concrete systems for sections Amsteg/Erstfeld, section Sedrun and/or sections Bodio/Faido and have also followed through with the tests. As was to be expected, the rate of failed mixes matched the level of the requirements. Thanks to this system, it was nevertheless possible to test complete concrete systems for all sections and to get them approved. The joint ventures tendering for the contracts were allowed to include only approved mix designs in their bids. Workability and durability are of paramount importance for cast and sprayed concrete mixes. Durability is influenced by the chosen mix design where binder concept and well-defined water content, i.e., impermeability, are determinant. Aggregates for AlpTransit are to be considered as given. The concrete mix design also determines workability. Because ambient conditions and also requirements with respect to workability are subjected to change, it is necessary that the mix designs include control measures. The choice and number of components for the concrete systems (cement, additives and admixtures) allow adaptation to changing conditions. For AlpTransit such adaptive measures must meet very strict requirements.

Jan 1, 2008