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By L. Yuan, J. H. Rowland, D. Bahrami, R. Thomas

Blasting is the main method of production in many non-coal underground mining operations and produces multiple toxic gases as a result. The Mine Safety and Health Administration (MSHA) requires mine operators to measure the level of toxic gases in mines as frequently as necessary to ensure they are below regulatory safety limits. The current practice uses portable gas monitors to check the concentrations of toxic gases after a fixed post-blast time. This paper studies the application of a gas monitoring system in the return entry of a limestone mine to determine a safe re-entry time. The National Institute for Occupational Safety and Health (NIOSH) conducted such a monitoring program in a limestone mine from September 2016 through May 2018. NIOSH/PMRD (Pittsburgh Mining Research Division) is endeavoring to develop workplace solutions to improve detection of and reduce the risk of hazardous conditions. This study showed that the use of gas monitoring in the return air can be a useful tool at the mine operator’s disposal to detect and reduce the risk of hazardous conditions and also to reliably estimate the re-entry time.

By Prosper Lamothe

El presente texto describe la metodología ad-hoc para evaluar proyectos de Inversión estratégicos a través de la flexibilidad y la teoría de opciones reales. La clave de dicho enfoque metodológico radica en realizar la mejor proyección del precio de los metales aplicando las mejores prácticas mundiales al respecto. Para ello, se analizan una gran variedad de modelos concluyendo que el mejor modelo a aplicar, debe ser la simulación del precio del metal con reversión a la media con saltos de tipo aleatorio.

Sep 9, 2007

OBJECTIVES ??REDUCE OPERATING COSTS ??INCREASE LIFE COMPONENTS ??EXTEND LIFE of THE DOZER ??REDUCE MAINTENANCE COST ??REDUCE DOWNTIME ??IMPROVE DURABILITY & RELIABILITY ??IMPROVE BOLD JOINTS PREFORMENCE ??IMPROVE SAFETY

May 1, 2004

By Christopher Mark

Knowledge of in situ stresses is fundamental to many studies in earth sciences, and coal mine ground control is no exception. During the past 20 years, it has become clear that horizontal stress is a critical factor affecting roof stability in underground coal mines. The theory of plate tectonics and the World Stress Map (WSM) project has been extremely helpful in explaining the sources and the orientations of the horizontal stresses observed underground. Recently, WSM geophysicists studying deep-seated stresses have developed a model of how stress magnitudes vary with depth in the crust. They have devoted relatively little attention to near-surface stresses, however. This paper explores the relationships between deep-seated and shallow in situ stresses in several of the world?s coalfields, using a data base of more than 350 stress measurements from underground coal mines. The analysis indicates that distinct regional trends exist, corresponding roughly to the regional stress fields identified by the WSM. The paper presents equations for estimating stress magnitudes that were developed by treating depth and elastic modulus as independent variables in regression analysis. The magnitude of the horizontal stress increases with depth, at rates that range from 0.8 to 2.0 times the vertical stress, just as the WSM ?critically stressed crust? model predicts. Overall, it seems that the stress regimes encountered in underground coal mines are closely linked to those that exist deep in the earth?s crust.

Jan 1, 2008

By Jamal Rostami, Ataollah Rahbar

"Uma Oya Multipurpose Development Project is under construction in Sri Lanka. This project involves 2 Rolled Concrete Core (RCC) Dams connected through a tunnel currently under construction by Drill and Blast method. The water is transferred from first diversion dam to the 2nd regulatory dam and from which, it will be transferred through a 14 km headrace tunnel to the top of a 650 m deep drop shaft that feeds the high pressure water to an underground powerhouse and turbine chamber for generation of 120 MW of electricity. The Headrace and Tailrace tunnels are being excavated by two 4.4 m diameter double shield TBMs. The headrace tunnel has already passed 5km milestone and is mined in hard rock, while the tailrace tunnel has been completed in rather weak and fractured ground. This paper will review the history of the project along with the geology of the site. The operation of TBM in headrace tunnel will be discussed in more detail, focusing on the challenges of excavating through very strong and abrasive quartzite and gneiss on this site, as well as reaches of tunnel in high inflow of water reaching 400 L/Sec. INTRODUCTION This paper aims to introduce the Uma Oya Multipurpose Development Project (UOMDP) as a hydro mechanical project in Sri Lanka, targeted generating hydro-electric power, transferring water for irrigation purposes and controlling seasonal devastating flood. This project lies in the south-eastern part of the central highland region of Sri Lanka (Figure 1). The main part of the project is located in the south-western part of the Badulla district in the province of Uva. The south-eastern end of the project site is in the central west of the Moneragala district (province of Uva). Bandarawela is the largest urban setting within the project area, located halfway between the upstream and the downstream ends of the planned hydropower plant and combination of dams, tunnels, and downstream facilities. The Multi-Purpose Project Of Uma Oya is planned to convey water from Uma Oya to Kirindi Oya Basin for hydroelectric energy generation includes Puhulpola RCC Dam on the Uma Oya river, Dyraaba RCC Dam on the Mahatotilla Oya river, a conveyance tunnel from Uma Oya to Mahatotilla Oya (L=3750m), a long feeder tunnel from Mahatotilla Oya to Kirindi Oya. The feeder (power) tunnel Lot consists of a headrace tunnel (L=15554m), the surge shaft (L=200m) and tank on the upstream of the vertical shaft, a vertical shaft with steel lining (L=650m), an underground powerhouse and a tailrace tunnel (L=3650m)."

Jan 1, 2016

Coagulation-Neutralisation Technology to Treat Wastewater from Lead-Zinc Concentrator

Sep 13, 2010

By A. Baldwin

This report describes the engineering feasibility and economic advantages of a unique new mining machine using cutting bits that take a constant-depth linear cut in the coal face. The studies show that this innovative new cutting concept, being developed by the Bureau of Mines, can be designed into the basic continuous mining machine. The resulting miner would be attractive to mine owners because coal could be mined with minimum generation of airborne respirable dust, substantial increases in productivity, and elimination of methane ignition due to cutting.

Jan 1, 1977

By Marlene Olivares Cruz

The particles that make up the deep-sea sediments have two main sources: 1) those that are created in situ from dissolved components and 2) those that are washed into the ocean in solid phases from the continents, atmosphere, space and interior of the Earth. Many particles as they sink through the water column reaches the seabed and are known as pelagic sediments with terrigenous, biogenic, authigenic, and cosmogenic components. Among the minerals found in the terrigenous fraction of pelagic sediments are quartz, clay minerals, feldspar, micas, ferromagnesians, and the biogenic fraction with remains of siliceous organisms, such as, radiolarian and diatoms. The chemical nature of marine sediments is controlled by the contribution of particulate matter derived from various sources with varying compositions for the fixing of elements during deposition and the compositional changes carried out within the sediments during diagenesis. In the last decade there have been several studies on the mineralogical composition of seabed sediments, suspended particulate materials and cores, together with paleontological and geochemical data are used for paleoclimatic and paleoenvironmental reconstructions, analyze changes in sea level, stratigraphic correlations and identify past and present sources of sediment and terrigenous input pathways and to describe the current ocean mass (Martins et al., 2001, Oliveira et al., 1998). There is also a scientific and economic interest in the authigenic fraction of pelagic sediments formed from other materials for polymetallic nodules. The study of sediments associated with polymetallic nodules helps to know the genesis, evolution and occurrence of these deposits (De Koven et al., 2003, Dubinin et al., 2008).

Jan 1, 2011

By Warren Howes, A. B. Campbell, W. H. Ode

"INTRODUCTION The mines in the eastern part of the now active region of the Tri-State zinc district of Missouri, Kansas, and Oklahoma have unusually acid water, which during periods of moderate or no rainfall is used in the mills to replace losses from evaporation, seepage, and tailings disposal. Its use has caused difficulties by corrosion of equipment and by interference with flotation.The growing importance of flotation, which requires good water, and the increasing troubles caused by the corrosion of the milling equipment have prompted the Mississippi Valley Experiment Station of the United States Bureau of Mines, in cooperation with the Missouri School of Mines and Metallurgy, Rolla, Mo., to investigate the action of the waters on flotation and to undertake to develop means of obviating their harmful effects.The work was under the immediate direction of W. T. Schrenk, consulting chemist, United States Bureau of Mines, and professor of chemistry, Missouri School of Mines and Metallurgy, and Will H. Coghill, supervising engineer of the ore dressing section of the United States Bureau of Mines.ORIGIN OF ACID MINE WATERSRain water, carrying oxygen and carbon dioxide in solution, finds its way into the pores and crevices of the earth's crust and percolates downward through the rocks. This water and its dissolved gases exert a solvent action on many minerals, the extent of which depends upon the nature of the associated minerals.The iron sulphides are the chief sources of the 'trouble with sulphates and sulphuric acid because they oxidize so freely and contain more sulphur than is required to satisfy the iron when ferrous sulphate is formed. Galena and sphalerite may oxidize to sulphates without liberating acid. A few of the common reactions occurring in the Tri-State mine waters may be illustrated by the following equations:"

Mar 1, 1932

By Patterson B. G

The small party of mining men who formed the original Mount Morgan Syndicate in 1882, commenced operations on the top of the mountain with what were practically nothing more than small hillside quarries, It was not until 1891 that underground stoping began, and open-cut mining therefore commenced with the commencement of operations. This hillside quarrying, however, seems to have been quite haphazard and unsystematic ; there is no trace or sign of any properly devised mining scheme. This can be seen plainly enough from an examination of old mine plans; for in less than five years after stoping was; adopted, the open-cut was down into the stoped-out ground. The following table, prepared from these old plans, shows the downward trend of the excavation in the past fiftyseven years:-

Jan 1, 1939

By W. H. MacLean, S. Liaghat

Abstract- The Key Tuffite is a thick (0.3 m to 6 m) and laterally extensive (-10 km) cherty, sulfide-bearing tuff unit in Archean greenstones in the Matagami mining district in northwestern Quebec. It lies at the contact of the Watson Lake Group and overlying Wabassee Group volcanic rocks, and is host to major Zn-Cu volcanogenic massive sulfide deposits. The tuff component is highly altered and its volcanic precursors are not identifiable by petrographie means. The tuff is mixed with a volcanic exhalative component comprising chert, carbonate and sulfides (pyrite, pyrrhotite, and minor sphalerite and chalcopyrite). The normative mineral composition of the Key Tuffite is 33% quartz, 28% sulfides, 16% sericite, 8% carbonate, 60Jo chlorite and 9% other minerals. In the vicinity of the Bell Allard and Orchan mines, the precursor tuff components are identified using immobile major and trace elements, as Watson Lake tholeiitic rhyolite (Zr/Y = 1.5 to 3.5, LaN/Ybn. = 1.7 to 2.8, Si02 = 72.5 ± 1.2 wt %, and Wabassee calc-alkaline andesite (Zr/Y =9, LaN/Ybn. = 4 to 8, Si02 = 56% to 65%). Immobile element computation techniques were used to calculate mass additions and losses in the conversion of the tuff to the Key Tuffite. Average net amounts of Fep3 (27% total iron), Si02 (14%), CaO (8%), S and K20 ( + 2%), were added, Na2O was removed (-2.8%), and MgO was over-all unchanged. Total net mass change was +63%, which comprises mainly exhalative additions, but also includes changes owing to hydrothermal alteration of the tuff component.

Jan 1, 1992

By John D. VandeKraats

Yielding rock bolt support systems have been developed to accommodate ground movement in shifting ground such as in coal operations; in creeping ground such as salt, trona, and potash; and in swelling ground associated with some clays. These systems, designed to remain intact despite ground movement, should enhance mine safety and help contain costs in areas where rebolting of rigid non-yielding systems is typically required. Four such systems were tested in straight tensile pulls in the laboratory. They include the Slip Nut System from Dywidag Systems International USA, Inc., Ischebeck's bolt mounted Titan Load Indicator, Rocky Mountain Bolt Company's Yielding Cable Bolt, and a rock bolt installed variation of the yielding steel post developed by RE/SPEC Inc. The first two systems are currently marketed products and the latter two are prototype systems. Each system responds to load and displacement by yielding in a unique manner. All are designed to yield at predetermined loads. A description of each system and its yield function is provided. Each system was tested over its prescribed yield range in a test machine. At least five tests were performed on each system. Each system yielded and continued to provide support according to its design. Each shows promise for ground control use in shifting or creeping rock. This work helps to illustrate the comparative differences in performance between these specialized systems and the applications where they may be most useful.

Jan 1, 1996

By K. B. Bengtson

This task report provides the process technology, preliminary design, capital and operating costs for a 25 TPD pilot plant to produce cell-grade alumina using a clay/hydrochloric acid extraction - HCI gas induced crystallization process. The report consists of six volumes: I - Process Technology and Costs; II and III - Equipment Lists, Specifications and Quotations; IV and V - General Specifications; VI - Drawings. The process was selected by the Bureau of Mines as the more promising method to produce cell-grade alumina from clay based on the results of the two previous task reports under this contract: Task I - Comparison of Six Processes (alunite, anorthosite-lime sinter, clay/sulfurous acid, clay/nitric acid, clay/hydrochloric acid evaporative and gas-induced crystallization) and Task 2 - Comparison of Two Processes (clay/nitric acid and clay/hydrochloric acid - gas induced (crystallization). The pilot plant process utilizes a unique dual crystallization process to produce aluminum-chloride-hexahydrate crystals having sufficient purity when decomposed to meet stringent alumina product specifications. The size of the 25 TPD pilot plant has been selected to permit scale-up to commercial size plants of equipment, technical and economic parameters. The capital cost estimate for the pilot plant, exclusive of fee and escalation, for a southeastern U.S. location is $52,311,000 expressed in 1979 dollars. The total time required to construct the pilot plant including engineering and procurement is 32 months. The operating cost to produce the estimated 9,000 tons of alumina required for testing in Hall cells is $40,91[0],190 expressed in 1979 dollars.

Jan 1, 1979

By N T. Moxon, L W. Armstrong

Explosive manufacturers have for many years provided a service to the mining industry which has,until recently, been unchallenged by mine operators. Today mine operators are more aware of the properties of explosives required to perform particular tasks within their operations. These properties can be reliably quantified using the test procedures described in this paper for emulsion adn ANFO based explosives. Details of an end-user sampling programme desgined to provide quality checks on explosives supplied to a mine site are also discussed.

Jan 1, 1991

By K. P. Fournier

This report describes work on the problem of predicting oil recovery from a reservoir into which water is injected at a temperature higher than the reservoir temperature, taking into account effects of vis cosity-ratio reduction, heat loss and thermal expansion. It includes the derivation of the equations involved, the finite difference equations used to solve the partial differential equation which models the system, and the results obtained using the IBM 1620 and 7090-1401 computers. Figures and tables show present results of this study of recovery as a function of reservoir thickness and injection rate. For a possible reservoir hot water flood in which 1,000 BWPD at 250F are injected, an additional 5 per cent recovery of oil in place in a swept 1,000-ft-radius reservoir is predicted after injection of one pore volume of water. INTRODUCTION The problem of predicting oil recovery from the injection of hot water has been discussed by several researchers. l-6,19 In no case has the problem of predicting heat losses been rigorously incorporated into the recovery and displacement calculation problem. Willman et al. describe an approximate method of such treatment. 1 The calculation of heat losses in a reservoir and the corresponding temperature distribution while injecting a hot fluid has been attempted by several authors.7'8 In this report a method is presented to numerically predict the oil displacement by hot water in a radial system, taking into account the heat losses to adjacent strata, changes in viscosity ratio with temperature and the thermal-expansion effect for both oil and water. DERIVATION OF BASIC EQUATIONS We start with the familiar Buckley-Leverettg equation for a radial system:* This is sometimes referred to as the Lagrangian form of the displacement equation. If the injection water is at some temperature Ti which is above reservoir temperature TR, then lw, the flowing fraction which is water, is a function of both water saturation and fluid temperature at any given time and position in the reservoir. The temperature dependence of lw results from the temperature dependence of the viscosity ratio µo/µm of which lw is a function. Thus:

Jan 1, 1966

A simple process for making filter aids from coal by controlled carbonization at 800-1200·C is described.Several possible variations in reactor design have been used experimentally, involving fluidized beds of carbon or inert material, reaction of the particles while entrained in air, and a combination of entrainment and fluidization.Product yields depend upon the composition of the parent coal but are always less than the sum of the ash and fixed carbon values determined by the proximate analysis. The product yield also depends on the air-to-coal ratio, which affects the amount of coal substance burned and the temperature attained. Particle residence time and reactor temperature affect the degree of devolatilization of the product and hence its wettability. The filtration behaviour of carbonaceous filter aids is greatly influenced by the size distribution, shape and physical properties of the particles-parameters which are largely determined by fue type and particle sizing of the coal used.Carbonaceous filter aids are distinctly different from other types commonly used and extensive industrial applications are anticipated in a wide range of industries ranging from food to mineral processing.

Jan 1, 1970

By F. X. Prins, L. R. Nelson

Tight control of electrode paste additions, hard and soft paste levels, baked zone position and electrode temperatures are integral to superior Söderberg electrode management practices. Paste addition is typically effected through briquettes, cylinders or large blocks. Each electrode paste form has its advantages and disadvantages, but probably a more crucial element from an electrode control perspective is the frequency and amount of electrode paste addition into a Söderberg electrode column. The detrimental effects of excessive soft paste levels leading to Stokes? Law segregation of paste in the electrode column are well documented, while several operators have effectively implemented the use of electrode thermocouples to monitor paste temperatures and automated slipping algorithms to control baking conditions within electrodes. Somewhat less well appreciated are the negative influences of inadequate soft paste levels, especially when coupled with excessive paste cylinder or block additions and resulting high hard paste levels. The alternative of insufficient hard paste levels and associated overheated electrode paste must also be considered, and can contribute to paste segregation directly. This condition also has the potential to generate gas mixtures in the electrode column that are concurrently a potential health hazard, while being prone to spontaneous combustion. Results of industrial trials on electric furnaces using Söderberg electrodes in a variety of applications from ferrochromium, to ferromanganese and even platinum-bearing base metal sulphides smelting are presented to illustrate the influence of paste loading practices on the dynamics of hard and soft paste levels. Possible electrode failure mechanisms attributable to inadequate paste level control will be discussed through some industrial examples. Suitable paste loading practices to mitigate the risks of inappropriate paste levels and associated electrode incidents are presented.

Jan 1, 2004

By Axel Preusse

Underground coal mining can cause seismic events. There is currently no way to predict such phenomena reliably, in particular stronger events. That is why, according to the current state of the art, empirical methods are employed in this field. Some assessment criteria, which relate to the geological and mining situation and either stimulate or rather help to avoid seismic events, are presented in this paper. These criteria are examined for a practical mining situation in Germany, with a view to estimate possible seismic events.

Jan 1, 2009

By Wood W, Bell A

Brown coal production in Victoria's Latrobe Valley Region (Figure 1) continues to rise and currently stands at around 50 Mt per annum. With the exception of around 2 Mt used to produce some 700 Kt of brown coal briquettes, this coal is mined by the State Electricity Commission to fuel large thermal power stations with a total installed capacity of just over 5 000 Megawatts. The moisture content of the coal as mined typically exceeds 60 per cent, making Latrobe Valley coal a markedly low rank fuel. The lack of heating value is, however, compensated for through power station design and by the fact that ash yield is very low, usually within the range of one per cent to four per cent on a dry basis. This means that compared with most other coals, the burning of Latrobe Valley brown coal produces relatively small quantities of waste products and discharges a minimal level of pollutants into the atmosphere. Even so, the inherent quality of Latrobe Valley coal does vary significantly from one area to another (Gloe, 1991; Barton et al, 1992) both on a local and a regional scale. Such variations need to be recognised and understood in order to not only realise efficiency gains in existing power stations but to properly assess resource potential for future utilisation and the application of new technologies. The principal aim of this paper is not to describe coal quality variation in detail or to speculate on the nature of and reasons for such variation. Rather, it is to simply underscore that significant differences do occur and that this is clearly a factor which needs to be considered in any evaluation of Latrobe Valley brown coal as a resource for the future.

Jan 1, 1992

IN the recent monograph on Broken Hill, N.S.W., by E. C. Andrews,* two independent petrological reports appear as Appendices 1 and n, by W. R. Browne and F. L. Stillwell respectively. In these considerable differences of opinion occur. Andrews contributes to some of the questions at issue, but no analytical review of the differences appears in the body of the report. Their development may invite question, and the following notes have been prepared partly in explanation and partly as a summary of some of the divergences. The soope of Browne's report extends over the whole district of Broken Hill, while Stillwell's deals with the rocks within 25 chains of the main lode. The more difficult and important rock-types occur in both areas, raising similar questions. In both cases observations extended beyond the limits of the prescribed areas. Broadly, Browne faces his problem as a study of a series of primary igneous rooks, acid and basio, whioh are intrusive into a series of sillimanite gneisses. The development of the sillimanite gneisses is regarded as belonging to an earlier period than the intrusion of the igneous rooks, while the gneissio structures of the latter are features which are incidental to their orystallization, and are not acquired subsequent to their consolidation. He finally produoes a picture in which his views of igneous injection and differentiation takes a prominent place. One direct result is the claim that three separate periods of metamorphism have oocurred in the Broken Hill area. Stillwell primarily examines the rooks as schists and gneisses since their present dominating features have been acquired during metamorphism. The effort is made to understand suoh differences as might arise from differing conditions of metamorphism upon rocks of similar and different oonstitution. The aim is to divest the rocks of those oharaoters which are due to metamorphism before approaching the questions of intrusive relatio'nships between igneous rocks andsediments.

Jan 1, 1924