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By P Kovacs, D. L. Flock

For the purpose of reservoir-performance calculations a balance can be made between the materials with-in the reservoir and the production from the reservoir. The material balance equation, a relationship which holds under or near equilibrium conditions, has been used in many forms by the Petroleum Engineer for the determination of initial oil-in-place in the reservoir and the calculation of performance into the future. One of the more recent methods developed by Tracy, utilizes a modified form of the Schilthuis material balance. In the latter case, values of incremental production are assumed for a particular pressure drop, a value of the gas-oil ratio found and a check of this estimate made by calculation"' the initial oil-in-place. Tracy's method utilizes an estimation of the instantaneous gas-oil ratio and by trial and error a value of the gas-oil ratio is

Jan 1, 1961

By Z. D. Yu, J. E. Gebhardt, D. I. Phillips, S. X. Jiang, R. Z. Zhang

The potential application of flotation for the treatment and processing of a fine-particle coal stream was investigated for the Chaili Coal Washery of the Zaozhuang Coal Mine Administration, Shandong Province, China. A goal of the test work was to evaluate the application of the Microcel™ flotation column and compare its performance to conventional flotation. Small-scale flotation tests were performed in the laboratory and on-site with fine coal slurry samples from the plant thickener underflow, i.e., the washing plant's undersized reject material. Flotation tests were conducted on-site with a 7.6-cm diameter Microcel™ column and with small-scale conventional cells. Column flotation tests were performed to determine a recovery-grade relationship for the fine coal feed, which contained about 24% ash, and to obtain sufficient data to enable scale-up to a large diameter unit. A primary objective as to establish the maximum throughput capacity of a Microcel™ flotation column while operating to produce a clean coal product with ash content of 7.5-7.8%. Results of the test work indicate that this product quality could be achieved at feed rates of 15-19 tph to a 3-m diameter Microcel™ flotation column. Lower ash products, i.e., 5-7% ash, were obtained but at lower column throughput capacities. Comparative flotation tests, conducted with conventional flotation cells, indicated that a product ash of only 8% or greater was achieved in a single-stage test.

Jan 1, 1995

By P. V. Avotins, I. Djurkovic, D. R. Nagaraj, M. Grunjic, A. Day

"As part of a major reconstruction and expansion of the Majdanpek Copper Mine, an investigation and optimization of the flotation collector regime was undertaken. The flotation response of the major minerals to various reagents and the effect of pulp chemistry was studied from both a fundamental and practical point of view. These studies led to plant trials and the eventual adoption of a modified collector suite which improved both copper and gold recoveries.INTRODUCTIONThe Majdanpek Copper Mine processes 40,000 tons per day of ore containing about 0.43% cu. In addition to copper, the ore also contains recoverable quantities of molybdenite and gold. The mine has been in operation since 1961 and is the largest in Yugoslavia. It is currently undergoing major reconstruction and expansion. The flowsheet of the Majdanpek concentrator is shown on Figure 1.The ore body is variable in composition and changes in mill feed require proper control of operating variables to achieve the optimum metallurgical results. A detailed study including grindability, flotation response, and solid-liquid separation was carried out on several samples of the ore. Flotation response and the choice of reagent chemistry were found to be very important in achieving the highest recoveries of metal values. An automatic reagent control scheme insured that optimum dosages were used in the plant.The flotation collectors used at the present time include sodium isopropyl xanthate (SIPX), AERO 3302 Promoter and AERO 5415 Promoter. The addition of AERO 5415 to the reagent suite is a recent development and was based on the favorable results obtained in the extensive laboratory testing program conducted to establish the optimum reagent combination and dosages. Subsequent plant tests confirmed that AERO 5415 provided significant improvements in copper and gold recoveries. A description of the mineralogy of the Majdanpek ore and details of laboratory and plant metallurgical data are given in this paper. The chemistry of AERO 5415 Promoter and its interaction with minerals relevant to Majdanpek ore are also discussed."

Jan 1, 1992

By Pathan AG

This research work is concerned with an investigation of the fracture toughness of sandstone, siltstone, and coal. Tensile failure trades have been examined with three different specimen geonetries, i.e; rectangular bar, round bar (in three point bending), and diametral compression discs. The Stress intensity approach, and J-integral methods were used to evaluate fracture toughness. Results from both approaches are discussed. True crack length was determined after pre-cracking, using the compliance calibration technique. Fracture toughness results of sandstone are independent of crack length and the size of the specimen. Fracture toughness may hence be regarded as a material property for sandstone. In cxnntrast fracture toughness values for !siltstone and coal are dependent on crack Length.

Jan 1, 1986

An Evaluation of Froth Recovery Measurement Techniques

Sep 13, 2010

By Claude Hubert, Alex C. Brown, Pascal Marquis, D. M. Rigg

"Numerous studies of the Bousquet mining district, Abitibi, Quebec, mainly following the successive discoveries of new gold deposits over the past two decades, have led to a broad range of genetic hypotheses for their gold deposition. A compilation of petrographic, structural, and geochemical data indicates that the gold deposits are composed chiefly of pyritic schists derived from felsic and mafic volcanic and volcaniclastic protoliths, and of auriferous massive pyrite hosted by pyritic schists of felsic affinity. The deposits are typically located within zones of local pyrite enrichment and advanced-argillic alteration which are in turn enclosed within much larger zones of disseminated pyrite included in regional-scale, commonly anastomosing, zones of sericitic alteration.Overprinting relationships between three sets of folds and foliations indicate that the host-rocks of the gold deposits have retained the imprint of three successive generations of ductile deformation resulting from regional dynamothermal metamorphism. Sericitic and advanced-argillic alteration, together with massive sulphide deposition, are interpreted to have taken place prior to the onset of the ductile deformation, based on observations 1) of altered fragments of wallrocks which are enclosed within massive sulphide bodies and were thus preserved through regional metamorphism, 2) of the syntectonic deformed pyrite, and3) of the syn-tectonic porphyroblasts of andalusite, garnet and plagioclase. The orebodies are oblate to prolate, and the pyrite-gold mineralization is typically vein-type, distributed in foliation-oblique and foliation-parallel veins. The gold-bearing structures postdate all foliations, and are associated with retrograde alteration assemblages that are pseudomorphic after pea~-metamorphic porphyroblasts in host-rocks, and with cataclasticfabrics that overprint syn-metamorphic pressure-solution features and annealing fabrics in pyrite.Retrograde gold-bearing assemblages indicate a chemical disequilibrium between the ore-forming fluids and their host rocks. This disequilibrium rules out the possibility that gold was remobilized from its own host, and suggests, instead, that the ore-forming fluids and their metal contents had an allochtonous source. Stable and radiogenic isotope analyses indicate that the fluids had a metamorphic origin, and that the associated alteration took place after the culmination of the Kenoran orogeny."

Jan 1, 1990

By R. N. Guest

The Tromp distribution curve was used in an evaluation of gravity separators treating a synthetic ore made up of silica and marker minerals of various relative densities. The results pinpoint differences in the concentration of particles of different sizes, and indicate how the grade of a concentrate is likely to vary with particle size. An increase in the feed rate increased the efficiency of the 'waterless' spiral concentrator that was tested, but the multiport spiral concentrator tested was more efficient. Both spiral concentrators were found to be more efficient than the pinched sluice and the shaking table that were tested. The method was found to be a useful way of evaluating gravity concentrators, but, for ease of analysis, care must be taken in the choice of marker minerals.

Jan 1, 1985

By T. Lamb, T. Aston

"The Gays River Mine is located within a complex hydrological regime and underground mining environment. Early in the mine history, the operation was' affected by an inability to control mine water inflows. More recently, the reopened mine operation had been unable to maintain consistent drainage of groundwater to the mine workings and sustain low groundwater levels.In 1992, a series of investigations were completed, which in part Were funded under the Canada-Nova Scotia Mineral Development Agreement. The studies undertaken included: hydrochemical and drainhole well screen assessments, an air photo study of sinkhole features, numerical modelling studies and a major piezometer installation and overburden soil study. The results indicate that the water draining to the underground workings is comprised of two distinct components: precipitation over the drawdown cone catchment area and seepage from the nearby Gays River. In addition, a third ""balance"" component was' also found, which represents uncertainties in the areal extent of the drawdown cone and river seepage components.After outlining the history of the groundwater problems experienced at the Gays River Mine, this paper examines the various studies undertaken during 1991-1992 and concludes that control of groundwater levels in the mine area is achievable. A number of recommendations are also proposed for future study ."

Jan 1, 1993

By W. R. Davison, C. A. Brown, J. P. Carstens

INTRODUCTION The phenomenon of heat-weakening of rock with 10.6 micron radiation from a continuous-wave C02 gas laser has been investigated in detail at the Massachusetts Institute of Technology for over 5 years. The programs at MIT have explored the basic nature of the heat-weakening phenomena and rock fracture caused by heating (e.g., Refs. 1 and 2), and have resulted in quantitative estimates of the relationship between the amount and parer level of heating and the resulting decrease in the modulus of rupture of a rock beam in a three-point bend test (Ref. 3). Results of the tests reported in Ref. 3 indicate a greater than 90% reduction in the modulus of rupture for granite beams heat-weakened by a laser. These results prompted the U. S. Department of Transportation to seek an assessment of the expected feasibility of employing the heat- weakening concept in a full-scale tunnel boring operation. Present- day continuous rock-tunneling machines have demonstrated tunneling time and cost savings over drill-and-blast methods, when used in rock types that are easily broken by the cutters. However, cutter bits have not yet been developed which can easily penetrate very hard rock

Jan 1, 1971

By Howard C. Turnage, Dana T. Updyke, Wayne C. Muhler

The objective of this project was to develop technical data and evaluate performance and utility of leaky feeder communications systems currently used in North American underground mines. The desired information was obtained principally through on-site surveys. Altogether, six of the seven mining companies known to be using leaky feeder communications were visited. This report covers the findings of these surveys. In addition, the report provides a brief background summary of mine communications, a technical discussion of leaky feeder systems, and conclusions and recommendations based on the results of the survey.

Jan 6, 1980

By J. A. Organiscak

This paper examines methods for limiting occupational silica exposures for roof bolting personnel in underground coal mining. A canopy air curtain and an air tube were evaluated as means to provide filtered air over the breathing zone of these personnel. Laboratory testing showed that dust reductions beneath the air curtain and air tube approached 60 percent and 40 percent, respectively, with low interference air velocities. The data also showed that dust reductions were highest for positions closest to the device and that these levels decreased with distance. This paper also evaluates a metal rake, a flexible insert, and a rigid insert for cleaning the roof bolter dust collector box. Less dust was produced when using the rigid insert. Surprisingly, the flexible insert was sometimes no better than scraping or raking the dust onto the mine floor. However, little dust got on the coveralls when using either of the inserts.

By J. A. Organiscak

This paper examines methods for limiting occupational silica exposures for roof bolting personnel in underground coal mining. A canopy air curtain and an air tube were evaluated as means to provide filtered air over the breathing zone of these personnel. Laboratory testing showed that dust reductions beneath the air curtain and air tube approached 60 percent and 40 percent, respectively, with low interference air velocities. The data also showed that dust reductions were highest for positions closest to the device and that these levels decreased with distance. This paper also evaluates a metal rake, a flexible insert, and a rigid insert for cleaning the roof bolter dust collector box. Less dust was produced when using the rigid insert. Surprisingly, the flexible insert was sometimes no better than scraping or raking the dust onto the mine floor. However, little dust got on the coveralls when using either of the inserts.

Jan 1, 2002

By T. Bajpayee, J. Ellenberger

Microseismic monitoring and evaluation is one aspect of the National Institute for Occupational Safety and Health (NIOSH) research program. Roof falls are often preceded by a period of elevated microseismic activity, but not all periods of elevated activity result in a roof fall, nor do all roof falls occur after some amount of elevated activity. The objective of this study is to review periods of elevated microseismic activity and determine whether fracture activity rate can be used to anticipate the initiation of roof falls. The study was carried out at an underground limestone mine where major roof falls are associated with excessive horizontal stress. The progression of roof falls was detected by the microseismic signature produced by the rock falling from the mine roof onto the mine floor, which is termed a roof fall impact event. A total of nine elevated fracture activity periods that resulted in seven major roof falls were examined. It was observed that elevated fracture activity preceded the initial roof fall impact event in three out of four major roof falls. The initial impact event was not identified for the remaining three roof falls. Fracture event rates were analyzed and a roof fall alarm trigger of five fracture events in a ten minute time period was established for this test case. The fall alarm trigger was tested against six of the elevated activity periods. Four roof falls occurred in the six periods of elevated activity, and two would have triggered the alarm before the roof fall occurred, while two false alarms were generated. The results show that limited success would have been achieved by the microseismic system as a roof fall alarm trigger. However, the trigger would have been successful at warning of the onset of elevated activity, allowing mine employees to respond appropriately. The study highlighted some issues with implementing such a system in an operating mine, including the need for real time identification of fracture related microseismic signals among mining induced signals, and accurate location and identification of fracture clustering.

By T. Bajpayee, J. Ellenberger

Microseismic monitoring and evaluation is one aspect of the National Institute for Occupational Safety and Health (NIOSH) research program. Roof falls are often preceded by a period of elevated microseismic activity, but not all periods of elevated activity result in a roof fall, nor do all roof falls occur after some amount of elevated activity. The objective of this study is to review periods of elevated microseismic activity and determine whether fracture activity rate can be used to anticipate the initiation of roof falls. The study was carried out at an underground limestone mine where major roof falls are associated with excessive horizontal stress. The progression of roof falls was detected by the microseismic signature produced by the rock falling from the mine roof onto the mine floor, which is termed a roof fall impact event. A total of nine elevated fracture activity periods that resulted in seven major roof falls were examined. It was observed that elevated fracture activity preceded the initial roof fall impact event in three out of four major roof falls. The initial impact event was not identified for the remaining three roof falls. Fracture event rates were analyzed and a roof fall alarm trigger of five fracture events in a ten minute time period was established for this test case. The fall alarm trigger was tested against six of the elevated activity periods. Four roof falls occurred in the six periods of elevated activity, and two would have triggered the alarm before the roof fall occurred, while two false alarms were generated. The results show that limited success would have been achieved by the microseismic system as a roof fall alarm trigger. However, the trigger would have been successful at warning of the onset of elevated activity, allowing mine employees to respond appropriately. The study highlighted some issues with implementing such a system in an operating mine, including the need for real time identification of fracture related microseismic signals among mining induced signals, and accurate location and identification of fracture clustering.

Jan 1, 2007

The imbalance between the coal resources contained in thin seams (1,5 m or less) and the production from them is outlined. It is suggested that an Increase In the exploitation of thin coal seams is necessary, and that drum-type continuous miners can produce a substantial amount of any increase. Continuous miners are employed in a number of mining methods including bord-and-pillar, pillar extraction (stooping), rib-pillar extraction, and shortwalling. These techniques of mining are evaluated with respect to production rates and the cost of extraction for South African conditions included in these evaluations are the types of equipment used to transport coal from the mining machine to the section conveyor belt. Computer simulation techniques are used to generate the required production levels, and interpretations are made of other results from the computer modelling. For thin, coal seams, bord-and-pillar mining utilizing continuous haulage is apparently the most productive and cost-effective of all the methods using the continuous miner. The relative efficiencies of the other techniques of mining and of coal-transportation vehicles are also outlined.

Jan 1, 1984

By Dr. Anthony J. Konya

The modern era has seen a boom in virtual training platforms. This study details the effectiveness & applicability of online training in comparison to in-person training for the drill & blast industry.

Feb 1, 2020

By D. Warkentin, M. Tomlinson, A. Nacu

"This study focuses on comparing the “blinding” effectiveness of various organic additives as part of a general review of using organic additives to mitigate preg-robbing and improve gold recovery during cyanide leaching of carbonaceous gold ores. The laboratory results compared the impact of various organic additives on the prevention of gold adsorption using both activated carbon and ore samples containing carbonaceous matter, generally referred to as total carbonaceous matter (TCM). Although several organic reagents were found to have a significant blinding effect on activated carbon, these results did not translate into increased gold leaching efficiencies with actual ore samples.INTRODUCTION Preg-robbing refractory ores, which contain carbonaceous matter, have been problematic in cyanide plants for many years. In industry, preg-robbing by carbonaceous matter may be mitigated using various techniques including flotation, to remove the carbonaceous matter; addition of blinding agents, to passivate the carbon surface and prevent adsorption of gold cyanide complex; roasting, to partially or fully destroy the carbonaceous matter; chemical oxidation (Abotsi & Osseo-Asare, 1986); pressure oxidation; or microbial deactivation (Dunne, Staunton, & Afewu, 2013). Carbon-in-Leach and Resin-in-Leach are also used as process alternatives in which activated carbon or resins are used to compete with the carbonaceous matter for gold cyanide adsorption. For highly preg-robbing ores, thiosulphate leaching may be considered as an alternative to conventional cyanide chemistry (Baláz, et al., 2000). Natural carbonaceous matter is composed mainly of hydrocarbons, organic acids, and graphitic/amorphous elemental carbon. Natural elemental carbon that behaves as activated carbon is considered to be the main reason for preg-robbing, although the true nature of this phenomenon is not fully understood (Tan, Feng, Lukey, & van Deventer, 2005). In general, the hydrocarbon fraction is assumed to have negligible interaction with gold, while organic acids, such as humic acids, may form complexes with gold, inhibiting its extraction in cyanide solutions. Organic reagents have been used for blinding carbonaceous matter in gold ores prior to cyanidation. Abotsi & Osseo-Asare (1987) tested various organic compounds, with two possible effects in mind. First, the organic compounds were expected to adsorb onto the surface of the solids as anionic/cationic species; the resulting electrostatic interactions between the Au(CN)2- anion and the negatively/positively charged surface would inhibit/enhance the gold uptake. Second, the organic reagents were expected to coat the surface of the carbonaceous component in the ore, limiting the available adsorption sites and reducing gold losses. Optimal reagent dosage depends on ore mineralogy, maturity and surface area of the carbo"

Jan 1, 2019

By J. D. Miller, D. M. Catarious, F. L. Stanley

The quality of cleaned products from coal preparation plants is often variable due to natural fluctuations in the washability characteristics of the plant feed. To combat this problem, many modern plants have installed on-line analyzers that provide feedback for the real-time control of product quality via the adjustment of circuit cutpoints. Unfortunately, optimization studies show that this approach may actually lead to increased losses of saleable coal. This paper discusses the problems associated with the real-time manipulation of circuit cutpoints and suggests alternative modes of operation that are better suited for plant optimization. A case study involving an eastern U.S. coal plant has been used to compare the economic impacts of these different approaches for plantwide control.

Jan 1, 2000

The Crown Minerals Act provides a new+framework for the management of Crown owned minerals and requires that regard be had for the principles of the Treaty of Waitangi. The Act requires the preparation of Minerals Programmes to achieve the Act's objectives of efficient allocation of rights and the recovery of a fair financial return on its minerals. Efficient allocation requires that a permit is allocated to the party which values it most highly. A fair financial return to the Crown must be considered in the context of the economic rent available from individual mineral projects, with the proviso that a nil return to the Crown as the owner of the resource will not be considered a fair return from the community's perspective.

Jan 1, 1992

By C. L. Lin

Linear grade distribution measurements determined from polished sections of randomly oriented particles can be used to estimate the extent of liberation for multiphase particles of specified size. Two techniques, optical image analysis and microprobe analysis, have been used to establish linear grade distributions. Both techniques were evaluated and compared using variable grade samples of products from a copper porphyry flotation circuit. The statistical significance of the linear grade distribution data obtained by optical image analysis was assessed. The average chalcopyrite content of these samples, as determined by chemical assay was used to estimate the variance of the experimental procedure. For a given accuracy, the number of particles required to obtain an unbiased representation of the sample was determined.

Jan 1, 1985