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By B. K. Kejriwal, A. K. Ghose

Under specific geological environment, the full extraction of a coal seam is not possible either because of its extraordinary thickness or the presence of surface structures and bodies of water or because of the conditions prevailing in upper seams. Not uncommonly, therefore, for working such seams, pillars of coal are left for the permanent support of the overburden, and voids around the pillars are filled with sand to strengthen the pillars and prevent their deterioration with time. However, the paucity of river sand has focussed attention on the need for alternate strategies including trials with partial filling of the voids. This study has sought to examine in the laboratory the effects of partial and complete filling on the ultimate load bearing capacity and post-failure behaviour of small, tall pillars using artificial material.

Jan 1, 1986

By Wang Dianzuo, Luo Lin, Hu Yuehua, Qiu Guanzhou

This paper introduces a novel classification approach named the flotation classification approach which works by controlling interactions between particles. It differs considerably from the conventional classification processes operating on mechanical forces. In the present test, the micro-bubble flotation technology is grafted onto hydro-classification. Selective aggregation and dispersion of ultrafine particles are achieved through governing the interactions in the classification process. A series of laboratory classification tests for -44 pm kaolin have been conducted on a classification column. As a result, about 92 percent recovery for minus 2 pm size fraction Kaolin in the final product is obtained. In addition, two criteria for the classification are set up. Finally, a principle of classifying and controlling the interactions between particles is discussed in terms of surface thermodynamics and hydrodynamics.

Jan 1, 1995

By Ernest K. Yanful, Paul H. Simms

The lysimeter is a useful tool for evaluating the performance of mine waste covers or liners. A major problem with its application is the possibility for preferential flow into or away from the lysimeter, if the lysimeter soil is finer or coarser than the barrier soil or sub-base soil. Analysis of a field lysimeter using a two-dimensional unsaturated-saturated liquid flow model suggested that preferential flow would occur and little or no water would be collected; however, in the field, the lysimeters collected significant amounts of water. A similar discrepancy was found between the observed and predicted water balance of a simple laboratory test simulating the lysimeter design. Vapour flow and partial flow, two phenomena not generally simulated in conventional flow models, are possible explanations for the difference between field and laboratory observations.

Jan 1, 2000

By Brij M. Moudgil

Lack of understanding the major process parameters and inadequate scale-up factors have led to the belief that fundamental knowledge is not important for successful flotation plant operations. Flotation of simple and easy to process ores may not require a strong fundamental knowledge base for day to day operations. However, as low grade complex ores are mined and process control is integrated into flotation schemes, it is imperative for a plant operator to acquire a strong background in the basics of the flotation process at hand and/or have access to such a knowledge base at short notice. In order to meet the challenges of unexpected changes in the feed, reagent quality, water chemistry, physical, mechanical and hydrodynamic conditions, the flotation plant superintendent/chief metallurgist must have a strong background in the flotation fundamentals.

Jan 1, 1993

By John L. Watson, Suren Mishra

Many of the wastes produced by modern steel plants are pulps or sludges containing significant concentrations of iron and displaying some ferromagnetic characteristics. These waste materials are often suited to treatment by magnetic cycloning to produce a high solids content underflow and a clean water overflow. Alternatively in the classification mode, the magnetic cyclone can produce a high iron underflow product for recycling by discarding fine non-magnetic material to the overflow. Results for the treatment of a variety of steel plant wastes in 5.0cm, 2.5cm and 1.25cm diameter cyclones, operating with and without an applied magnetic field, are presented. It is demonstrated that the magnetic cyclone increases solids recovery to the underflow product, especially at finer particle sizes and for higher solids content feed pulps.

Jan 1, 1992

By Leo Langland

One of the primary functions of the Geotechnical Services-Materials section of the Arizona Department of Transportation (ADOT) is locating, sampling, and evaluating potential aggregate deposits throughout the State. This information is essential in designing, estimating, and bidding highway construction projects. The nature of materials used for aggregate varies greatly within Arizona. The northeastern or plateau section is famous for its scenic sedimentary formations that are, how- ever, too soft to make suitable aggregate. Volcanic materials are widely used in place of more conventional geologic units. In contrast, the southwestern, or Basin-and-Range section, contains a relative abundance of good aggregate, especially a diversity of gravels. The paper will review the off ice, field, and laboratory methods used by the ADOT Materials Section in satisfying its needs for aggregate information in Arizona.

Jan 1, 1987

By C. Anderson, K. Nikkhah

This paper outlines the role of simulation software in design and operation of a typical metallurgical plant with mineral processing and hydrometallurgical units, to produce concentrate and pure metal. It addresses the role of simulation and mass balance software in the conceptual, feasibility and detailed design stages. It discusses the use of JKSimMet for sizing of mineral processing units, and METSIM and IDEAS for development of energy and mass balances. In detailed design of a plant, the complex interaction and variation in performance of various units makes it difficult to predict overall system performance and availability. Simulation is used to: assess operating strategies that affect surge capacities at various stages compare different ore types and mining strategies that affect concentrate product quality. optimize transportation logistics for raw materials, concentrate and metal products

Jan 1, 2001

By M. S. Klima, A. Simard, M. L. Turek

Laboratory testing was carried out to evaluate several devices for recovering clean coal from bituminous coal refuse material. The bulk of the testing focused on using a dense-medium cyclone to process -0.6-mm refuse material. A hindered-settling column and a spiral concentrator were also used to process nominal 1.2 x 0.15-mm material. Product yields and ash contents were obtained for all tests, while partition curves were generated for selected tests from which the characteristic performance parameters (relative density of separation and probable error) were determined. The results indicated that the dense-medium cyclone was capable of cleaning down to 0.037 mm, while the other devices were effective to 0.15 mm. Keywords: Coal recovery, Coal refuse, Dense-medium cyclone, Hindered settling, Spiral concentration

Jan 1, 2003

By N. Oswald

As coal mines age and become more developed, ventilation modeling becomes more important for the planning and continued operation of the system. Numerous studies have been performed and presented that address the collection of data and measurement of airway friction factor and resistance per unit length values. However, a quantitative analysis of the resistance for stoppings in coal mines for different construction materials and methodologies has not been adequately addressed. In order to develop an accurate/realistic ventilation model both airway resistances and stopping resistance values need to be determined. Over the course of the past two decades Mine Ventilation Services, Inc (MVS) has measured the resistance of stoppings of various construction types in mines throughout the world. An analysis of this data is presented in this paper along with a discussion of measurement methodology.

Jan 1, 2009

By G. Raspa

This article describes a procedure for calculating the recoverable reserves of stratified orebodies characterised by a thin and irregular layers. An application on the phosphate deposits in the N'Zeto region of the Popular Republic of Angola is also described. The procedure consists in building a block model of the deposit through the conditioned multivarial geostatistical simulation of small areal units. The recoverable reserves are then calculated and defined by applying to the model a selection processes based on measured geological/economic parameters taken from the drillholes: thickness of overburden and mineralised layers, economic grain-size fraction, grade. The procedure also takes account both of the geometrical constraints of the mining method and dilution. For reasons of confidentiality, a multiplier has been applied to the values adopted for the sampling data.

Jan 1, 1992

By D. Tao, B. K. Parekh

Fine coal particles are difficult to separate effectively from liquids or other solids. Ultrasonic energy may be used to enhance the efficiency of the conventional fine-particle separation processes widely used in the coal and mineral industries. Flotation, settling and dewatering tests were conducted using several fine coal samples to study the effects of ultrasonic treatment on these processes. Process variables such as particle size, ultrasonic treatment time and solids concentration were investigated for their impacts on ultrasonic treatment effectiveness. The results obtained from this study showed that ultrasonic treatment is an effective approach for enhancing solid/solid separation in flotation and solid/liquid separation in sedimentation and dewatering of fine coal. SEM microphotographs demonstrate that ultrasonics cleaned particle surfaces, which is, in part, responsible for the observed improvement in fine coal separation processes.

Jan 1, 2000

By M. Prasad, A. K. Majumder, T. C. Rao

The depletion of high-grade phosphate ores is bringing about a search for a suitable, economically viable technique that con process the abundant low-grade phosphate reserves. About 75% to 80% of the world's low-grade phosphate reserves are associated with carbonate gangue that is not amenable to treatment by the simple techniques of physical separation. The processing of sedimentary dolomitic/calcareousphosphate ore has numerous problems, including similar surface properties of the carbonate and phosphate. Two-stage reverse anionic flotation of carbonates (dolomite/calcite) has appeared to be a promising separation technique ,for the removal of carbonates from sedimentary rock phosphate. In reverse fatty-acid anionic flotation, the depression of phosphate mineral with orthophosphoric acid produces satisfactory results for calcareous as well as dolomitic phosphate ores from several locations of sedimentary origin.

Jan 1, 2000

By Robert J. Timko, R. Lincoln Derick

This report presents a Bureau of Mines evaluation which examined the extent of gas leakage from sealed areas in underground coal mines and measured the effectiveness of commonly used structures for controlling the quantity of gas exchange from these areas. Evaluations were performed on five abandoned areas in two operating underground mines within the same coal seam. Methane and oxygen levels inby the seals were monitored to determine if the gas leakage was unidirectional or bidirectional. Results from this and prior work dealing with minimizing gas leakage were then applied to a newly abandoned area. Also discussed are bulkhead site preparation, construction plans, techniques for monitoring the status of the atmosphere within the sealed volume, and a modified European method for controlling gas migration from the sealed volume to the active mine.

Jan 1, 1991

By G. Barbery

A review is given of the present applications of random sets and integral geometry in fragmentation and liberation models of ores and minerals. Although attempts have been made in the past to apply such mathematical techniques to the comminution of solids, it is shown that it would not result in major progress. In liberation modeling, it is demonstrated that the approach can lead to fruitful results. Following a recent paper by Davy (1984), a model of liberation prediction is developed that can be calibrated for ore texture and breakage using image analyzers. The model is demonstrated for the case of a Poisson polyhedra ore texture and monodisperse fragment size. The model enables prediction of the complete composite particle distribution and thus is valuable for integration of ore breakage models with minerals separation models.

Jan 1, 1988

By C. E. Zebula, F. F. Aplan, R. S. Datta

The hydrophobicity of oil shale was found to follow the sequence R-5 > Mahogany >> Eastern. Further, hydrophobicity was found to correlate with the total organic carbon (TOG) content, decreasing with increasing specific gravity of raw oil shale pieces. Differences in hydrophobicity from piece to piece indicate that gravity preconcentration would be much more effective for Western than for Eastern oil shales. Purified kerogen concentrates and low specific gravity fractions (<2.0) of raw Western oil shale samples show critical surface tension of wetting values of [y]c = ~35 mNm -1, and for a kerogen concentrate from an Eastern oil shale [y]c = ~46 mNm-l. This infers that dust from oil shale mining operations can be suppressed by surfactant solutions similar to those used to suppress coal dust.

Jan 1, 1988

By R. A. Bergman, P. G. Thornhill

Development of the Falconbridge Ferronickel Process for treatment of lateritic nickel ores began with laboratory work in 1955, the year the Company commenced exploration of its concession in the Dominican Republic. Process development centred on selective reduction originally directed to producing calcines amenable to ammonia leaching, but later found suited to electric smelting. The reduction step of the process was developed in a 25 tpd shaft furnace pilot plant located in the Dominican Republic, to which was later added an electric melting furnace. After almost 3 years of development work on this scale the plant was expanded to 100 tpd for fixing design data for a commercial plant. This took the form of the 30,000 ton per year Nickel Ferro-nickel Complex of Falconbridge Dominicans, which started up in 1971.

Jan 1, 1979

By Michael Karmis, Emily A. Sarver, Ellen S. Gilliland, Leigh-Anne H. Krometis

"Public engagement is increasingly important in ensuring the success of projects related to energy development, particularly with regard to issues of environmental protection, public health, and socio-economic impacts. This is due to concurrent trends in public behavior, including a rise in public interest in these projects that is not matched by a rise in science literacy, and increasing organization and participation of the public through social media, citizen science, and grassroots initiatives. In recent years, several high-profile incidents have demonstrated that when public concern is ignored or met with a passive response from industry, it can rapidly grow into organized opposition that negatively impacts or wholly derails a project. Engaging, listening to, and educating stakeholders during early planning and development phases are therefore essential to earning credibility and trust. Moreover, maintaining two-way lines of communication throughout the lifespan of a project demonstrates social responsibility and facilitates cooperation, acceptance, and even support from communities and others. Positive experiences with specific projects at a local, community level can influence the larger public opinion of an entire industry sector. This paper presents cases studies of public engagement related to shale gas development (including hydraulic fracturing and pipeline construction), mountaintop removal mining, and management of mixed-use watersheds near surface mining operations. The experiences highlighted in these case studies are used to draw best practices of public engagement for sustainable energy development.Introduction Within the scientific research community, the importance of public engagement has gained increasing recognition. In a 2007 article in Nature, medical researcher, Patrick Taylor, stated that public engagement has both “gone viral” and “gone global” and has the ability to make real impacts to research (Taylor 2007). Nancy Baron, the science outreach director for COMPASS, an organization providing communications training for scientists, provides further evidence for the increasing focus on engagement, including shifting attitudes observed during her own experience as a communications coach and documented in surveys, the recent inclusion of communication and engagement activities in academic tenure review, and the surge of workshops, materials, and other resources available on the subject (Baron 2016). In addition to COMPASS, a number of organizations and institutes have been developed to train scientists for communication and engagement with the public, perhaps most notably the Alan Alda Center for Communicating Science at Stony Brook University, and academic fellowship programs, such as the Leopold Leadership Program at Stanford University and the Wilburforce Fellowship Program, have been established for the same purpose."

Jan 1, 2017

By D. M. Milne, H. H. Kanduth

INTRODUCTION The past few years has seen an increased interest in the determination of statistically valid properties of a rock mass. The increased use of computer modelling for the study of rock excavation behaviour has created a need for upper and lower statistical bounds for the properties of a rock mass being modelled. Obviously, to determine the statistical properties of a large volume of rock, many samples must be tested - an expensive proposition when using conventional testing facilities and procedures. As a result of high costs per sample, sufficient tests for statistically valid results are rarely done. In an effort to reduce both sample preparation and test facility costs, an instrument called the Bemek Advanced Rock Tester (BRT) was developed in Sweden. With a total weight of approx. 35 kg, the BRT is portable and sells at a small fraction of the cost of a conventional testing machine. It is comprised of a small 65 KN loading frame with attachments for a variety of tests (see Table 1) , a hand operated hydraulic pump, an electronic balancing unit and a programmable microprocessor. The microprocessor is capable of storing data, performing arithmetic operation on, and printing signals from, a transducer and two strain gauges. A detailed description of the apparatus is given by G. Swan et al. (1). The proposed test strategy involves first a 3-point flexure test on a notched core specimen, followed by a 4-point flexure test on the separated specimen halves. Finally, point load and Brazilian tests can be carried out on the quarter parts of the original specimen. Thus specimen preparation is kept to a minimum. These and other perceived advantages have prompted the purchase of this machine and an evaluation of its suitability to provide data on mechanical properties of intact rock for numerical modelling and rock mechanics design at Noranda&apos;s underground mines. Details of its performance evaluation and experiences with the unit are discussed in the following sections. [ ] INITIAL OPERATING EXPERIENCE During the commissioning stage the BRT had, or developed, a series of problems, some of which seriously affected its operation. Below are some examples. Poor documentation was the most serious problem encountered. Confusing instructions for the 4-point bend test installation and its microprocessor programing, as well as poor and ambiguous information on the calculation of gauge factors, are some of the difficulties which had to be overcome. Meehan~cal problems occurred, including failure of the hydraulic pump, as well as electronic difficulties with the microprocessor. Other problems with the printer, requiring its replaceqent, were fortunately covered under warranty.

Jan 1, 1986

By Nora M. Hutt, Kevin A. Morin

The Sobek humidity cell has been in use with minor modification for more than 30 years to determine bulk primary-mineral reaction rates. As a result, it has become a key tool for predicting the bulk rate of sulphide oxidation, the Carbonate Mole Ratio (CMR) of neutralization-potential (NP) consumption to sulphide oxidation, and the rates of metal leaching. Most humidity cells are operated for less than a year, with the resulting rates extrapolated into the future for years or decades. The validity of these extrapolations was tested by examining longer trends from cells that have operated for three to seven years, as found in the International Kinetic Database (IKD). Additionally, large batches of cells for two minesites in the IKD (45 and 46 cells each) were examined to determine if regular, predictable trends were obtained across ranges of geochemistry at a minesite. The long-term cells show that the rates of sulphide oxidation and acid generation, based on sulphate production, have a 50% chance of stabilizing within one year, with the remainder fluctuating significantly throughout their test periods. Despite the fluctuations, the CMR, which is critical for defining site-specific or rock-unit-specific ABA criteria, remains relatively steady in many cases between 1.0 and 2.0 as expected from principles of aqueous geochemistry. However, if the sulphate-production rate falls below 10-30 mg/kg/wk, the CMR value can increase significantly. At and below these low rates, physical factors like flow rates of surface waters and groundwaters will determine the rate of NP consumption, rather than geochemical factors. Also, if weekly rinse pH falls to acidic values, the CMR will decrease below 1 .O, reflecting the exhaustion of fast- neutralizing minerals. The two batches of multiple cells also confirm these trends across arange of geochemistry. The long-term cells show that copper leaching often stabilizes within a narrow range as long as rinse pH remains relatively constant. Also, there is no strong dependence of leaching on the sulphate rate. However, the rate of copper production often increases sharply if rinse pH falls to acidic values. This suggests the measured copper-production rate in some cases is not a true primary rate, but a lower secondary rate after secondary- mineral precipitation within Sobek cells. As with the long-term cells, the batches of multiple cells show that copper production often increases gradually with decreasing rinse pH, with no clear dependence on sulphate production. However, high rates can also occur at near-neutral pH, so secondary-mineral precipitation of copper is not necessarily common.

Jan 1, 2000

By David S. Bolin, Bruce Kennedy, Leigh A. Readdy, Graham Mathieson

INTRODUCTION The estimation of ore reserves is a process that begins with the earliest exploration stages on a property and continues throughout any subsequent evaluation and exploitation of the deposit. During exploration and preliminary evaluation, the results of these reserve estimates constitute the basic data for prefeasibility studies and economic analysis. The decision to continue exploration and development or to abandon a prospect is often based upon these studies. During the active life of a mine, reserve computations are continuously revised to assist in development planning, cost and efficiency analyses, quality control, and improvement of extraction and processing methods. Accurate reserve estimates are also required when financing a project, purchasing or selling a property, and for accounting purposes such as depletion and tax calculation. It is important to remember that the reliability of ore reserve estimates varies progressively through time as more and more information becomes available. The lowest order of reliability of estimation of reserves exists at the time of discovery. The maximum level of certainty concerning the ore reserves within a deposit is reached when the deposit is completely mined out. Between these two extremes are variable levels of certainty as to the tonnage and grade of the resource. This is particularly true of that portion of the mineral resource that constitutes the "minable reserve," as this portion is dependent upon economic as well as geological and technological factors. In the following discussion, several of the factors affecting ore reserve computation and some of the commonly used methods of calculation are presented. The first part of the discussion is confined to classical methods of hand calculation utilizing level maps and sections. The second part of the discussion presents an overview of somewhat more sophisticated methods of geostatistics which have been developed within recent Years. Geostatistical methods frequently provide the best ore re- serve estimates for many deposits. However, a digital computer is required for such geostatistically derived estimates due to the number and complexity of the cornputations involved. For many properties the classical nongeostatistical methods are adequate, particularly in the early exploration stages. In fact, it is the author&apos;s contention that even at those properties where the geostatistical approach is employed for reserve estimation, the geological and engineering staffs should prepare an estimate by traditional means. This provides an internal audit for the reserves and at the same time requires a continuing close appraisal of geologic problems that influence the presently known geostatistically estimated reserves and production at the mine.

Jan 1, 1982