Search Documents

By P. J. Routledge

THE purpose of this paper is to discuss the practical aspects of locating gravel deposits and of establishing efficient, portable concrete aggregate beneficiation plants for use on construction projects where limited amounts of high-quality gravel and sand are required. Certain projects are listed, in order to demonstrate the wide variety of problems encountered. Routledge Gravel Contractors Limited, North Vancouver, have supplied concrete aggregate for construction projects in British Colum-bia since 1957. In tl1at year, in sup-plying aggregate for a small project at a site on the northern coast of British Columbia, our quote was as follows: Concrete aggregate to specifications, f.o.b. scow, North Vancouver$ 1.75 per cu. yd. Scowing charges to site. $16.00 per cu. yd. At that time, our company realized that more attractive quotations could be submitted if local gravel was utilized where available. Port-able equipment was then acquired and a simple screening plant (Figures 1 and 1a) was at first used. This was later replaced by heavier, more versatile equipment. The use of suitable equipment, the keeping of cartage to a mini-

Jan 1, 1962

By Rafael Henrique Alves Gomes

A automação em processos industriais agrega qualidade, padronização e segurança aos produtos e pessoas envolvidas. Entretanto, as demandas de mercado, custos agregados e a concorrência exigem melhorias que podem ser alcançadas através de métodos de otimização. Este artigo apresenta algumas metodologias e ferramentas para otimização de processos industriais que visam desvincular a obrigatoriedade de que Técnicas de Controle Avançado em métodos de otimização são a única solução capaz de oferecer resultados satisfatórios para aumento de produtividade. Os recursos expostos abordam a gestão de malhas de controle, gestão de alarmes e o cálculo do indicador global de eficiência, o OEE.

Aug 17, 2017

By D. P. Lindroth

The Bureau of Mines is engaged in research on ground probing radars for detection of geologic hazards in advance of mining. Penetration distances and interpretation models depend on the dielectric properties and wave propagation characteristics for coal measure stratified media. Relative dielectric constants and dissipation factors were measured under ambient conditions for Pittsburgh Seam coal measure rock over the frequency range of 20 to 100 MHz by the susceptance-variation method. The rock types measured were representative sedimentary rock located above the Pittsburgh Coal Seam. Extreme values for the computed attenu-ation distance ranged from 1.7 m at 100 MHz for siltstone to 230 m at 20 MHz for a particular limestone.

Jan 1, 1984

By I D. Gregson, A S. Garcia, K M. MacAndrew

The design work undertaken by Rock Mechanics Technology (now part of Golder Associates (Golder)) has played a major part in successfully establishing mechanised room and pillar working in Indian coalmines, both for the development of new districts and for the re-establishment of old districts prior to pillar extraction on panel retreat.Golder has used appropriate design of pillars, extraction sequences and final snook sizes to minimise ground control risks during pillar extraction. Where the strata will not cave reliably, partial extraction systems leaving either a crush pillar or a substantial yield pillar have been adopted.Remote monitoring of selected pillars during the extraction process using stress cells, extensometry and convergence measurements provides confirmation of pillar behaviour and verification of designs.A new telltale device, giving a visible warning of impending caving, is now installed at all Indian pillar extraction sites and is proving very successful.CITATION:MacAndrew, K M, Garcia, A S and Gregson, I D, 2014. Coalmine pillar design and performance during mechanised pillar extraction in India, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 347–358 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By Yong Pan, Srivatsan Jayaraman Sridharan, Purushotham Tukkaraja

Block cave mining method poses unique ventilation challenges compared to other underground metal mining methods. This research study focuses on assessing the airflow behavior in regulated airflow distribution systems by developing a 1:100 scaled block cave experimental model and a numerical model. This study also investigated gas flow behavior under various airflow conditions. Based on our findings, we observed that reduction in particle size and porosity of caved materials, decrease in cave footprint, and closure of undercut drifts would increase cave airflow resistance. The increased airflow is found beneficial for gas dilution regardless of its source locations, while the regulated airflow distribution system might deteriorate gas dilution situation when the source is located in the extraction drifts.

May 12, 2022

By G. E. Vaninetti

During its modem era, the southern Powder River Basin (PRB) in Wyoming has grown from meager origins in the early 1970s to become one of the most important coal-producing regions in the United States. In 1993, production and sales of southern Powder River Basin coal exceeded 190 Mt (209 million st), or about 20% of the US coal industry. Despite the remote location of the PRB relative to its potential markets, most coal industry observers anticipate continued strong growth to meet utility compliance plans for Phases I and II of the Clean Air Act Amendments (CAAA). This article is an overview of supply and demand issues concerning the marketing of southern PRB coal. It reviews the events leading up to the recent run on spot coal and offers a forecast of demand and prices.

Jan 1, 1994

The Beginning ! The status quo simply isn?t sustainable ! Our social license is at risk ! The bar keeps rising ? We must improve our performance, both operational and social ? We must improve stakeholder judgement of our industry by taking action collectively Implementing TSM " TSM Guiding Principles " Performance Indicators " Crisis communications " External Outreach " Tailings management " Energy management " Performance manuals, guides " Reporting " Communities of Interest Advisory Panel

May 1, 2004

By Donald F. Smith

This report describes the construction and calibration of two ice calorimeters and includes results of high-temperature heat-content measurements, made by the Federal Bureau of Mines, on rubidium fluoride, hafnium tetrafluoride, cesium chloride, and cesium iodide. The heats and entropies of fusion of rubidium fluoride, cesium chloride, and cesium iodide have been calculated at their respective melting points using equations derived from the experimental heat-content data. Hafnium tetrafluoride did not melt within the range of temperatures investigated. Heat and entropy of transition of cesium chloride from the alpha to the beta form were also determined. INTRODUCTION Free-energy data usually afford the cheapest and quickest means of determining the feasibility of experimentally untested reactions. For known reactions, free-energy data show the variation of the equilibrium constant with temperature and make it possible to calculate, without experiment, the maximum ratio of product to raw material for a given chemical process.

Jan 1, 1961

By W. J. Mahoney

A good quality assurance program at a coal mine or power plant is accurate, timely and consistent. The quality analysis is accurate due to a complete sampling of the coal stream loaded into the unit train. The sample analysis is accurate because standardized testing procedures are applied. Once an analysis is completed, the results must be communicated to the electric utility in a timely manner. The electric utility needs the results to better manage the coal inventory at its power plants. A quality assurance program can also help a mine deliver a consistent product to a utility's power plants. The importance of accuracy, timeliness and consistency are based on major changes that are taking place in the electric utility industry.

Jan 1, 1994

By A. J. Kraemer

The properties of crude petroleum continue to interest the Bureau of Mines and constitute an important phase of its major studies on the mineral resources of the United States. The Bureau's interest in the subject has been intensified by frequent requests for information on the characteristics of crude petroleum from various producing fields. Since its inception the Bureau of Mines has collected and analyzed samples of typical oils and at present has surveyed and classified crude petroleums from nearly all the known oil fields of the Western Hemisphere. Results of these surveys have been presented in various Bureau of Mines publications. (See bibliography, appendix A, p. 145.) The nature and comparative value of crude oils from various countries and the extent to which these oils may be considered potential competitors for markets are of manifest importance to the petroleum industry in all lands, largely because all crude oils, wherever produced, are either actual or potential competitors for a market with all other crude oils. The numerous discussions of foreign production of oil that have appeared in the technical press in the past indicate the great interest of the United States in this subject.

Jan 1, 1937

By S. Mohanta, S. Chakraborty, B. C. Meikap

"An air dense medium fluidized bed separator is an efficient dry process for the removal of undesirable gangue material from run-of-mine coal. Its cleaning performance depends on a variety of operating parameters that are interrelated in unknown, complex ways. A literature review showed that these parameters' effects had been experimentally investigated using a traditional one-variable-at-a-time approach, which is highly inefficient and sometimes misleading because many of the parameters often interact with each other to alter the overall equipment performance. Also, it is realized that the interrelationship among these parameters can have a significant effect on equipment performance. Therefore, to correctly evaluate the effects of individual parameters as well as their interactional effects on the separation performance of an air dense medium fluidized bed, we conducted a scientific study based on response surface methodology. Empirical models for two key response variables, namely, product ash and combustible recovery, were developed and subsequently used for identifying an appropriate operating region to achieve optimum separation performance. Furthermore, the optimum performances predicted from the empirical models were validated against experimental data. Preliminary results show a strong interaction among the operating parameters investigated in this test program.IntroductionFluidization is widely applied in industry for its various useful features. In the coal industry, it is used in the air dense medium fluidized bed (ADMFB) separator for the beneficiation of run-of-mine coal. In this separator, a medium is created by suspending fine magnetite particles in an upward air flow, and this pseudo-fluid is used as the beneficiation medium, with the lighter coal particles floating to the medium’s surface while heavier particles sink to the bottom. This separation technique had been receiving a significant amount of attention worldwide in recent times for its specific advantages of low operating cost and less restriction for small capacities (Luo and Chen, 2001; Sahu et al., 2009; Dwari and Hanumantha Rao, 2007; Van Houwelingen and de Jong, 2004), but it is still not a well-established industrial practice because of the availability of efficient wet processing technology. However, with a revival of interest in the dry beneficiation of coal, in general, and ADMFB, in particular, there is once again a concerted effort to improve the efficiency of the ADMFB process, and successive improvements have been made to make this process a competitive and viable option. The existing literature reveals that most of these research efforts had been essentially focused on the identification of a single parameter that has a key influence on separation performance, without taking notice of parameter interactional effect. For example, Luo et al. (2004) proposed a pressure drop number to distinguish separation performance without considering the bed height and gas velocity, which are intimately related to this proposed pressure drop number."

Jan 1, 2015

By Louis Frost

"A FIRE which forced the sealing -of the east side of Dominion No. 16 Colliery in the Town of New Waterford, Nova Scotia, occurred on October 6th, 1952 (Figure 1).So far as can be ascertained, the fire was first noticed in the roof of No. 7 East Lateral, after a brushing shot had been fired in the pavement. There appears to .be no doubt that this shot •blew out, igniting a small feeder in the roof.Regular air measurements and air samples, taken over a long period prior to the fire, indicated that the ventilation was adequate, for at no time had the percentage of CH4 in the general air current exceeded one per cent in this location. The last regular monthly samples and air measurements, taken at the end of September, showed the condition of the ventilation to be:Return at the Top of No. 8 East WallQuantity .... 27,700 cu. ft. per min.CH4 .......................... 0.32 per centC02 ................................ 0.10 per centHowever, in the week preceding the fire the mine examiner on four occasions had reported small feeders of gas at the face of the brushing in No. 7 East Lateral.Figure 2 is a diagram of the working place where the shots were fired. The face brushing had been shot down at 3 :45 p.m. and cleaned up. Two 'hurdle screens' had also been erected, one close to the face brushing and the other fifteen feet from the face."

Jan 1, 1953

By George O. Lower

The use of cyanides in the extraction of gold and silver is well known.1 Such extractions employ con¬centrations of cyanide in the range of 0.02-0.25 % sodium cyanide equivalent in leaching cycles of 24-48 hours and frequently longer. Copper minerals, even though minor components of precious metal ores, dissolve in these cyanide leaching solutions, consume cyanide, cause fouling of mill solutions, and thus interfere with the precipitation and recovery of gold and silver. 2,3,4 This paper presents a summary of laboratory investigations on the use of cyanide solutions as extractants for copper from various copper-bearing ore fractions. In view of the metal contents involved, it will be apparent that larger quantities of cyanide are required to extract copper than for the extraction of precious metals. In cyanide solutions of concentrations generally favorable to copper extraction, sulfide and oxide copper minerals were found to dissolve rapidly at room temperature and atmospheric pressure. For example, on products in the flotation size range, the major portions (e.g. 65-85%) of the extractable copper frequently dissolved in 2-10 minutes. At coarser grinds, e.g. 100% minus 28 mesh and 100% minus 10 mesh, 75-85% of the total copper was extracted in 30 minutes.

Jan 1, 1966

By Arne Landsberg

The Bureau of Mines measured the vapor pressure of FeC12 , FeBr2, FeI2, Sb, Bi, Cd, Mg, Pb, FeC13 , and VCl2 using the Knudsen-and torsion-effusion methods, and on FeC13 -NaC1 mixtures, Au2Cl6, and MgNi2 using only the Knudsen method. Apparent vapor pressures calculated from the experimental data vary with orifice size and method of determination. Reaction with residual oxygen in the instruments was noted to have an effect on the iron halide data. Vapor pressure curves plotted as log P versus 1/T (where P is pressure and T is absolute temperature) for one substance using several orifice sizes tended to converge at a single point when extrapolated beyond the experimental region. All of the data, except those of VC12, agree with previously published results. The importance of comparing effusion measurements with those obtained by other methods and the variations encountered with various orifice sizes are discussed.

Jan 1, 1977

By William G. Pariseau

A small displacement-small strain finite element technique utilizing the constant strain triangle and incremental constitutive equations for elastic-plastic media that are nonhardening and obey a Coulomb yield condition has been applied to the analysis of gravity flow initiation in a V-shaped hopper containing a powder under lunar environmental conditions. Three methods of loading were examined. Of the three, the method of computing the initial state of stress in a filled hopper prior to drawdown by adding material to the hopper layer-by-layer is superior (as expected). Results of the analysis of a typical hopper problem show that the initial state of stress, the elastic moduli, and the strength parameters have an important influence on material response subsequent to the opening of the hopper outlet.

Jan 1, 1971

By David H. Carlson

The paper presents background information including data on diesel exhaust pollutants, amounts produced and standards, a desscription of mine characteristics that affect air monitoring techniques and a review of portable measurement techniques and instruments for gas and particulate matter sampling. A general review of the laboratory and field research being conducted at Michigan Technological University in the area of diesel emissions is presented. The facilities involved with this research are also described. These are the Experimental Mine, the diesel dilution tunnel test cell, the Mine Air Monitoring Lab (MAML), the portable instruments and the production mines used.

Jan 1, 1979

By Lincoln A. Stewart, P. S. Haury

"INTRODUCTION AND RESUME Arizona asbestos mines are the only sources on the American continents of iron-free chrysotile spinning fiber that meets the Navy specifications for asbestos fiber for use in covering electrical cables. Rhodesia normally supplies the bulk of this grade of asbestos at about half the Price of Ari zona spinning fiber. The acute submarine menace in 1942 focused attention on the danger that imports might be cut off and that a sudden demand for greatly expanded production might fall on the Arizona mines to supply the tonnage of this essential material needed for war production.A joint preliminary investigation of Arizona asbestos deposits was made in August 1941 by J. R. Thoenen, senior mining engineer of the Bureau of Mines and A. E. Granger, a geologist of the United States Geological Survey. A more extended investigation of the numerous asbestos mines and prospects, which are scattered over 25 townships of difficult terrain in Gila County, was begun by the senior author in August 1942.The Geological Survey assigned two geologists (Newton Chute and A. F. Shride) a few weeks later to study the geology as an aid in selecting the mines for the Bureau's exploration projects. Six mines were selected for exploratory work because it was desired to prove reserves of ore where production could be started quickly if urgent demand should arise. Acceleration of production is normally slow because of adverse operating conditions. First, the mines are at distances of 35 to 100 miles from Globe, the shipping and supply point, and the roads are few and poor. The mine openings start in steep canyon walls, so that mining supplies usually have to be packed in and the product packed out over 0.5 to 5 miles of burro trail. Second, most of the ore deposits are small, and the ratio of rock broken to spinning fiber recovered is very high, usually exceeding 200."

Aug 1, 1947

By John A. Meech

In many multiple-sulphide ore flotation processes, it is desirable to concentrate each of the various valuable minerals into separate products. Although there are a variety of techniques and chemicals which can be employed to produce efficient separation, two basic types of flotation circuits are used: The Differential Flotation Circuit and the Bulk/Selective Flotation Circuit. Figure I depicts these two circuits in their most simplified form for the production of two concentrates and one tailing product. If three or more valuable minerals are present in an ore, a variety of combinations or extensions of these two basic flowsheets may be used. There are many examples of the successful application of both circuit types with ores containing similar minerals. Each ore must be tested individually to decide on which circuit is best. However, the following general statements can be made: 1) The differential circuit will have higher capital and operating costs than will the bulk/selective circuit due to higher rougher capacity requirement. 2) The differential circuit will achieve better separation than will the bulk/selective circuit since it is usually easier to reactivate a depressed mineral than it is to depress an already active mineral. If the deactivation problem with the bulk/selective circuit . . in can be overcome, there is a clear economic argument for its use

Jan 1, 1977

By N. Jovanovic, A. Vazirizadeh

"The main objective of this study is to find a solution to design a mass flow observer system with the minimum required sensors and maximum observability for a mineral processing plant. The second objective is designing a mass flow observer configuration with high reliability to manage sensor failures. This configuration will provide a robust monitoring system that increases plant availability and process measurement fault detection. Furthermore, the monitoring system is expected to improve process efficiency. In this investigation, the procedure of designing an observer system is presented along with three models to design the sensor network. The advantages and disadvantages of each models are discussed and finally the models result for an industrial case are presented and analyzed. INTRODUCTION The concepts of observability and redundancy of mass flow are directly linked with the ability to solve and estimate the mass flow. There are hundreds of streams in a process plant flowsheet, and for technical and economic reasons it is not possible to measure all mass flows. It is thus important to know for a set of measured streams, which of the unmeasured streams can be estimated. The concept of observability deals with this issue. It is also valuable to know whether a measured mass flow of streams can be estimated even if a sensor fails for some reason. Redundancy deals with this failure question. A stream is said to be observable if it can be estimated by using the measurements and/ or mass conservation equations. Also, a stream is redundant if it is observable even when its measurement is removed. Observability and redundancy analysis can be exploited for adding new measuring instruments. It can also play a useful role in efficient decomposition and data reconciliation problem (Narasimhan and Jordache 1999). The value of an observer system cannot be justified without considering its benefits. This justification is done through evaluation of data reconciliation, gross error detection and improving process performance such as outlined below:"

Jan 1, 2018

By Peter Chou, Pooyan Asadollahi, Danny Lin

To maintain flexibility and ductility of tunnels crossing active faults, various mitigation measures are being utilized depending on fault offset movements and seismic design criteria. Examples of those approaches are simple bell and spigot joint, articulated joint, and complex deformable longitudinal bolt and spring joint system with seismic isolation washer. This paper presents a summary of tunnel fault crossing mitigation approaches and design considerations using previous relevant experiences in California as well as case histories from Japan, Taiwan, Turkey, Greece, and Italy found in literatures. Comparisons are made between large and small diameter tunnels, transportation, and utility tunnels, as well as bored, mined and cut-and-cover tunnels. Recent innovations, such as Japanese and Italian techniques, for tunnels crossing active faults are also discussed.

Jun 13, 2021