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Mining steeply dipping coal seams is a difficult task in the mining industry. Prior to 1996, fully mechanized longwall mining methods along the seam strike direction were tried in China and other countries. Due to its larger coal reserve in steep seams, China made more but still limited progresses on mining in such seams than the other major coal-mining countries. In the last two decades, accelerated research efforts have been made to improve the mining technology in steeply dipping coal seams. Based on these works, a dynamic model of ?R-S-F? system under asymmetrical constrains in mining steep seam is established and the theory of strata control and hazard prevention begin to be formed. The key technologies for mining steep coal seams include: global and regional strata control methods in longwall face, methods for the longwall face machines to sustain static and dynamic loads, and flexible protection technology. These theory and technologies have been successfully applied to mining of steep coal seams of varying thickness and hardness, with hard and soft roof and floor, and with high potential of spontaneous combustion in China. In the recent years, the technology has been introduced to Russia, India, Uzbekistan and other countries where steep coal seams are mined.

Jan 1, 2012

By Constance F. Acton

Based on laboratory structure analyses, a pilot plant investigation was undertaken to evaluate a Michigan conglomerate native copper ore. Comminution or sized feed was accomplished using wet, closed circuit autogenous grinding with and without crushing of the recirculating load. Coarse metallics were concentrated in two stages of jigging with fine metallic copper being recovered in a three-stage xanthate flotation circuit. With a feed averaging 2.09 % Cu, copper recovery ranged from 86-93 % Cu with an average grade of 55.5 % Ca. An evaluation of the processing flowsheet is made in terms of pertinent independent, dependent, and external variables and design factors. Rate equations are developed to describe the grinding and flotation circuits separately as well as the entire circuit as a whole. Performance equations for the overall operation and for the unit operation of autogenous grinding alone are developed in terms of suitable capacity, efficiency and energy consumption terms. Thus, the effects of feed rate, recirculating load and flowsheet design can be rationally evaluated. Energy consumption for various conditions in the pilot plant is compared to the laboratory value. Additionally, size and scale up factors are discussed. Recommendations are made for further studies to be undertaken to further quantify the ore characteristics and the nature of the autogenous grinding operation. However, the feasibilty of beneficiation of this type of native copper ore by means of an autogenous grinding/jigging/flotation circuit is clearly established.

Jan 1, 1977

By Andrew A. A, Hamilton P. J

Constraints on pore water evolution in the aquifers of a sedimentary basin may be realised through stable isotope analyses of present day waters, and their comparison with water compositions calculated to have been in isotope equilibrium with the products of diagenesis during burial. Integrated with detailed petrographic observations, and thermal, structural and stratigraphic analyses, fluid migration patterns at various stages in a basin's history can be identified. This has important implications for modelling basin hydrology, hydrocarbon distribution, and reservoir quality in the Latrobe Group, Gippsland Basin, and oil-prone successions Elsewhere.

Jan 1, 1992

By Sidney Katell

This Bureau of Mines study estimates capital investment, operating costs, and selling prices for three underground bituminous mines producing coal with annual production ranging from 1.03 to 3.09 million tons. It is assumed that the mines have a 20-year life. Wages and union welfare payments are considered as of November 12, 1973, under the Bituminous Wage Agreement of 1971, and costs for material and equipment are based on 1973 indexes. Initial capital investment ranges from $12,938,200 for the 1.03-million-ton-per-year (MJ.Vl tpy) mine to $31,435,500 for the 3.09 MM tpy mine. Total capital investment ranges from $21,607,200 to $51,982,000 for the same mines. Corresponding selling prices for the coal range from $9.11 to $8.06 per ton, assuming a 12-percent discounted cash flow rate of return after Federal income taxes.

Jan 1, 1974

By K. Severin, B. Flanigan, P. Marion

“Plutonic-related” gold deposits in Interior and SW Alaska (Tintina Gold Belt) vary significantly in size, grade, vein/deposit morphology, depth of emplacement, distance from causative pluton and metal association. Metal associations such as Au-Bi and Au-As-(Sb-Hg) are a good empirical indicator of depth of emplacement and distance from causative pluton and have been used successfully in exploration. Results from a variety of analytical techniques also suggest a phenomenological cause for these metal associations, e.g. gold and bismuth have linked metallogenesis at high temperatures and thus are best correlated at deposits that are deep and/or close to causative intrusions.

Jan 1, 2000

By Jason Ryan, Stephen Harria

Q.E.D. (QED) is a blast design and evaluation model that allows full three-dimensional design specification including the development of unique “live” terrains and an unlimited variety of complex charge configurations. QED’s analysis package allows the examination of likely outcomes resulting from changing various design variables in terms of vibration, fragmentation, rock-mass damage and muck-pile profile. Especially applicable to use cautious blasting applications, QED’s damage model uses vibration to estimate rock damage beyond excavation boundaries. This relates directly to operations such as Yucca Mountain Nuclear Waste Repository in Nevada, where damage beyond the excavation perimeter must be tightly controlled. The U.S. Department of Energy (DOE) h as b een studying a site at Yucca Mountain, NV to determine its suitability for long term storage of nuclear waste. The main mechanism of waste isolation will be the natural barrier of the host rock Total Systems Performance Assessment (ISPA) is used to model the excavation design and its behavior over time. Of importance to TSPA is quantifying the condition of the rock-mass before and after excavation. Ideally, there should be no excavation-induced changes to the rock-mass’ structure (removing the requirement to model the effects). At the least it may be possible to keep excavation-induced damage far enough away from waste packages so that modeling of these effects will not be required. QED can calculate a prediction of the extents of blast induced damage to the rock-mass. By using this metric as a design parameter, it may be possible to complete excavation of the repository more rapidly and inexpensively than previously thought, without jeopardizing the structural integrity of the waste containment areas or requiring blast damage to be modeled by the TSPA. This paper will explain the structure of the QED blast modeling system and show the analysis of historical data from Yucca Mountain. Processing of the historical data and the subsequent results will demonstrate how blast modeling can be used on an ongoing basis to assist the excavation process at Yucca Mountain.

Jan 1, 2000

By D. W. Nel

Nanofiltration (NF) has attracted much attention over the past few years due to the reduced energy consumption compared to reverse osmosis (RO) and better separation performance compared to ultrafiltration (UF). Although research has been done in the area of NF of nickel ions, sodium ions, and acid separation, not much attention has been given to the separation of high nickel concen¬trations from sulphuric acid streams. The use of NF for the separation of nickel and acid from a spent nickel electrolyte is an innovative process alternative for future industrial application within a base metal refinery. In this study, the separation performance of a composite polyamide NF membrane on a spent nickel electrolyte was investigated by varying the sodium sulphate concentration in the feed (50-150 g/l), the trans-membrane pressure (35-55 bar), and cross-flow velocity (1.5-3.5 m/s), and measuring quantities such as total permeate flux, acid rejection, nickel rejection, and sodium rejection. The nickel and acid concentration in the feed were kept constant with variations between 40-60 g/l and 25-40 g/l respectively, while the temperature of the experiments was kept constant at 50°C. The membrane was found to be very selective for nickel ions, with the rejection of nickel ions varying between 54.4% and 98.2%. The rejection of acid ions varied between -5.9% and 21.8%. The rejection of sodium ions varied between 16.6% and 72.4% at a cross-flow velocity of 2.5 m/s and sodium sulphate concentration of 50 g/l in the feed solution. An increase in trans-membrane pressure increased the rejection of nickel, sodium, and acid ions, while an increase in sodium sulphate concentration decreased the rejection of nickel and acid ions. The total permeate flux was found to increase with an increase in trans-membrane pressure and decrease with an increase in sodium sulphate concentration. The cross-flow velocity had an insignificant effect on the total permeate flux and the rejection of nickel, sodium and acid ions.

Jan 1, 2013

By G. R. Hopkins

"Refiners are generally considered solely as fuel producers, but actually they also comprise a group one of the largest consumers of fuel. For example, during the year 1929 the refineries-burned 51,544,000 barrels of oil as fuel, or the equivalent of over 5 per cent of the crude oil processed in that year. In addition enough other fuels - coal, natural gas, refinery or still gas, and petroleum coke - were utilized to raise the total fuel consumption based on B. t. u. equivalent to more than 10 per cent of the heat value in the total crude oil run to stills. Refineries utilize fuel chiefly as the heat-forming element distillation, but also under-boilers in the formation of steam used in refining, for the heating of buildings, and in the generation of electricity.In the early days of refining, the problem of fuel utilization and fuel economy was of scant importance to the refiners. Margins of profit were comparatively high and the major portion of the operatros1 attention was directed toward increasing their throughput. However, the keen competition that has prevailed in the refining industry over the past five years or more has taught the refiners that their expenses, one of the largest items of which is the cost of fuel, must be curtailed. Thus in 1925 the refiners used an average of 829,000 B. t. u. to refine a barrel of crude oil, wheras by 1929 this average had been reduced to 639,000 B. t. u., a decline of 23 per cent (see fig. 1)Since 1925 oil has ranked first as a refinery fuel (see fig. 2). The use of natural gas increased during 1926 and 1927 but declined in 1928 and 1929. On the other hand, the use of refinery gas has grown rapidly in importance. Coal has shown a steady decline in use at refineries since 1925. Petroleum coke has never supplied more than a very small fraction of the total fuel requirements, although there has been a steady increase in its use."

Sep 1, 1930

The objective of this study was two-fold: 1. To perform a world literature search pertinent to the analysis, selection and design of hoisting systems and their components and to codify the search into a literature compendium. The search resulted in a technical data file of over 1500 hard copy items. The compendium index was also suitable for establishing a comprehensive computer-loaded data base on the subject. 2. To develop a comprehensive system of guidelines to cover salient aspects of analysis, selection and design of electrical, mechanical and structural components of a hoisting system with a view to establish parameters for maximum safety and efficiency of operation, installation and revision of the system. 3. Major mechanical components in the hoist and mechanical drive train are considered. Design and specification criteria based on American standards and practices are developed as they apply to typical mine hoist arrangements.

Jan 1, 1988

By Arthur M. Langer

Since the promulgation of the first Federal Asbestos Standard by the Occupational Safety and Health Administration in 1972, other federal agencies have modified the standard to better carry on their own unique missions. The instruments used to identify and measure asbestos, the sampling protocol, and the criteria used to define asbestos, have been modified to some degree. The Mine Safety and Health Administration regulates and controls asbestos dust in the mining and mineral commodity industries. However, crushed stone and processed ores contain mineral fragments that are frequently difficult to distinguish from asbestos. Mineral nomenclature, instruments for particle analysis, and sampling strategy must be accommodated to some degree to make asbestos control workable and meaningful. Precedent in other agencies has made consideration of these changes possible. Newly identified amphibole asbestos minerals have further complicated the agency?s regulatory charge. Changes in its Asbestos Standard are now being considered. Crushed taconite ore in the Eastern Mesabi highlights many of these issues. ©2008 Published by Elsevier Inc. Keywords: Amosite; Grunerite asbestos; Crocidolite; Riebeckite asbestos; Tremolite asbestos; Actinolite asbestos; Winchite asbestos; Richterite asbestos; Arfvedsonite asbestos; Fluor-edenite asbestos; Asbestos defects; Cleavage fragment; Mineral habit; Mesabi amphiboles

Jan 1, 2008

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 11rogresses 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 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 Sudbury Operations, the material and control equipment, the commitment, the new energy accounting practices and lastly, the policies. Examples of successful energy conservation endeavors include automatic peal electrical load control, waste heat recovery from mine air and compressor cooling water, energy reductions resulting from lower building temperatures and curtailmen: 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 Y. I. Yang, Y. -B. Tang, D. -J. Ma

Chlorine-containing minerals are commonly present in coal. Associated minerals such as pyrite can undergo exothermic reactions. Consequently, it is of great significance to study the effect of inorganic chloride on the spontaneous combustion of coal. In this study, the effects of five inorganic chlorides (sodium chloride, magnesium chloride, potassium chloride, calcium chloride, and zinc chloride) on the spontaneous oxidation of coal were investigated. Analysis of the gaseous products of coal oxidization at low temperatures (323K to 453K) showed that the presence of inorganic chlorine in coal markedly decreases O2 consumption and the generation of CO and CO2. Samples of raw coal and chlorine-loaded coal were oxidized for 36 hours under the same experimental conditions. Infrared diffuse reflectance spectroscopy results showed that inorganic chloride can inhibit the oxidative decomposition of some functional structure components (methyl, methylene, methine, and hydroxy) in the coal. The influence of inorganic chloride on the oxidation characteristics of the functional groups in coal during spontaneous combustion was investigated using benzyl alcohol and 1-phenylpropanol as model compounds, which were tested under the same experimental conditions as the coal samples. The oxygen consumption of model compounds with and without the addition of inorganic chloride further suggested that inorganic chloride may hinder the oxygenolysis of these structures during low-temperature oxidation. This phenomenon can be attributed to the radical reaction from the perspective of radical chemistry. It can therefore be concluded that inorganic chlorides play an inhibitory role in the spontaneous combustion of coal.

Jan 1, 2015

By R. A. Cattell

The conditions under which the researches of the Bureau of Mines on petroleum and natural gas were conducted in 1952 were little changed from those indicated in the last report,2/ which dealt with activities during 1951, immediately after crossing of the 38th Parallel by the North Korean Army. Although only a small part of the program was classified in the military sense, there was a feeling of the clash of world forces which called for even cheer scrutiny of the research problems so that the emphasis could be placed without delay where the greatest needs for na¬tional defense seemed to be. The reports of the work accomplished were so directed as to have the greatest immediate value to persons charged with supply planning for the military forces and included information on the availability and characteristics of a wide variety of crude oils, fuels, and other petroleum products. Actually, the approach, direction, and conduct of the work do not differ greatly under the two circumstances, as has been pointed out in earlier reports; only the tempo changes.

Jan 1, 1953

By O. F. Ochonogor

Laser metal deposition (LMD) is an additive manufacturing technique whereby a stream of metal powder is consolidated by a focused laser beam on the surface of a substrate or engineering component. The interaction zone between the laser beam and powder particles is scanned superficially, generating tracks of deposited material. The tracks are overlapped in a deposition strategy in accordance with slices of a CAD model. Successive layers of material are built up to fabricate a near net shape part. In this work, the technique is used to fabricate metal matrix composites (MMCs) by using an elementally blended feedstock combining metal and ceramic powders in the melt pool, which melt and solidify to create the required morphology. Ti6Al4V + TiC MMCs were produced with 10, 20, and 30 vol.% reinforcing ceramic, and Zr + TiC MMCs were fabricated with 10, 20, and 30 vol.% TiC. The deposited thin walls were analysed using optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and indentation testing. In both systems, the analysis revealed the presence of partially melted TiC particles embedded in the metal matrix along with fine dendrites of re-solidified ceramic. The dendritic structures in the Ti-based composites were confirmed as TiC, whereas in the Zr-based composite the Zr metal reacts with theTiC to form ZrC, leaving Ti in solid solution. Both the MMCs show an increase in microhardness with increasing ceramic (carbide)content, reaching a peak HV0.1 value of 500 in the Zr- based MMC and HV0.1 of 550 in the Ti based MMC.

Jan 1, 2012

By William G. Hedling

The operation of electric face equipment in underground coal mines has proven to be extremely hazardous to mining personnel, including equipment operators and others working in the vicinity of active equipment. Recent industrial engineering studies* of accidents and fatalities indicate that a major contributor to this hazardous situation is noncompliance with modern principles of human engineering, particularly lack of standardization of control configurations. Control configurations differ not only among different machine types, but also among the same machine types produced by different manufacturers. This lack of standardization can produce a high incidence of error in the operation of electric face equipment, thus creating a potential source of accidents. Other examples of non-compliance with human engineering principles are the widespread use of identical black, round control knobs (regardless of the function being performed), and the inappropriate location, spacing, and labeling of controls. Any or all of these factors may place the operator in a "negative transfer" situation, which means that control manipulations appropriate for one type of machine are different from (or even the reverse of) the control movements required to produce the same effect on other machine types. This situation increases the accident potential to the operator, as well as to others in the vicinity. Accident potential is further increased by circumstances which do not allow for large error tolerance-specifically, emergency procedures. Reports of accident statistics cite operator inexperience as a primary cause of most accidents involving underground electric face equipment. Several factors contribute to operator inexperience, including: 1. High personnel turnover 2. Employee absenteeism 3. Current union practice of bidding for jobs.

Jan 1, 1974

Properties of coal which are significant in relation to preparation for carbonization and conversion are reviewed, and existing coal preparation technology which has been used for production of cleaned coal of suitable ash content and petrographic composition for carbonisation, pyrolysis, hydrogenation and similar processes is described. Possibilities for application of this technology to some Australian coal seams is examined briefly. It is concluded that further survey work is required related to the optimization of selective crushing and concentrating operations, with the aim of maximizing production of quality products for carbonisation, etc mainly from Australian seams with only moderate coking characteristics.

Jan 1, 1980

SOME notes on the works of the Electrolytic Refining and Smelting Company of Australia will no doubt be of interest to members of the Institute, more especially as much of the work is new to Australasia. As many of the members who may read this paper have not been in a position to visit works of this kind, and are consequently not thoroughly acquainted with all the operations carried on, the author has taken the liberty, in some cases, to enter into explanation which would otherwise be unnecessary. The works are situated at Port Kembla (New South Wales), about fifty miles south of Sydney, and are approachable both by rail and water. The Government has recently built a low-level jetty upwards of five hundred feet long, and intends installing at an early date an electrically operated portable crane to facilitate the handling of material to and from the boats. This will mean: a considerable reduction in the length of time that boats are laid up at the jetty. There are also under construction two breakwaters, which, when complete, will materially assist shipping operation...

Jan 1, 1910

By Charles Vaught

The U.S. Bureau of Mines evaluated the self-contained self-rescuer (SCSR) donning proficiency of 243 miners. These workers were from eight underground coal mines in the eastern United States. The objectives of the study were (1) to gather information on skill levels, since all miners in the study had prior instruction and opportunity to practice donning the apparatus, and (2) to summarize a quality control procedure useful in conducting periodic evaluations of donning proficiency. The sampling procedure used proved to be both reasonable and efficient in gathering information on training effectiveness_ It also provided a good statistical base for making informed site-specific decisions regarding SCSR training needs. Results from the observed samples at each of the eight mines indicate a wide variability across sites. The rate at which miners failed to isolate their lungs varied from 33 to 40.0 pct. Concomitantly, proficiency rates (miners either performing adequately or demonstrating a perfect 3+3 sequence) ranged from 13.3 to 63.3 pct.

Jan 1, 1991

Effects of High Pressure Grinding Rolls on Platinum-Bearing Ores and the Flotation Response as Compared to the Conventional Ball Mill Three major PGM ore types from the Bushveld Complex of South Africa: Merensky, UG2 and Platreef were comminuted with the use of the high pressure grinding rolls (HPGR). The influence of the feed characteristics and the various operational and design features of the HPGR on energy consumption, throughput, mineral liberation and PGM flotation recovery were investigated. The test work variables included two feed top sizes of 12 mm and 6 mm, specific grinding forces ranging between 3 - 7.5N/ mm2 and zero gaps of 1.5 mm and 3 mm. The results show that the influence of the HPGR operational and design features on energy consumption, throughput, mineral liberation and PGM recovery are ore dependent. The size reduction-specific energy relationships show that the most energy efficient utilisation of the HPGR for Platreef ore was at the lower specific grinding force of 3N/mm2 and the zero gap at 3 mm. For Merensky and UG2 ore on the other hand, the most energy efficient operation was at the higher specific grinding force of 7.5N/mm2 and the zero gap of 1.5 mm. At a specific energy input of 3 kWh/t, reduction ratios (F50/P50) of 6.5, 3.8 and 10 were obtained for Merensky, UG2 and Platreef, respectively for feed top sizes of 12mm. Further application of the HPGR as a pregrinding stage to a ball mill showed a 25 - 30 per cent increase in throughput for Merensky and UG2 ore. Batch flotation tests performed on selected samples appear to indicate that ore comminuted with the ball mill had superior grades compared with that ground with the HPGR. However, Merensky and UG2 ore comminuted at different HPGR operating conditions showed distinctions in PGM recovery. Platreef on the other hand did not appear to show any differences. Therefore, this study highlights the significance of ore type and operating variables in HPGR applications with regards to energy efficiency, throughput and PGM recovery.

Sep 13, 2010

By D. E. G. Maschmeyer

The operation of the pilot plant for the S-C Copper Process during 1976 has provided the basic data for the design of a commercial-scale plant. This paper introduces the commercial aspects of the S-C Copper Process through the presentation of a process flow diagram, a schematic flow diagram and basic design parameters for 75,000 tonnes per year (tpy) copper rod production from chalcopyrite concentrate. Basic operating requirements are outlined and a preliminary estimate of operating and capital costs for a Western Canadian location are summarized. The results have been compared with a modern smelter/electrorefinery to highlight the advantages and disadvantages of these two alternatives and to show why the new S-C Copper Process technology should be of interest to the copper industry.

Jan 1, 1978