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By J. Richard Kyle

The Pb-Zn ore bodies in the Pine Point district are localized in paleo-solution structures that developed as the result of post-middle Givetian subaerial exposure of the carbonate barrier complex. Sulfides are concentrated in transgressive pale-solution structures that acted as natural bypasses between aquifers and loci for mixing of fluids of different character, one of which contained metals and the other reduced sulfur. Complex ore textures indicate rapid early sulfide precipitation followed by slower sulfide growth. Evidence for both sulfide-carbonate equilibrium and disequilibrium conditions suggest fluctuations in ore fluid composition. District and ore body metal distribution patterns may reflect the nature and movement of mineralizing fluids.

Jan 1, 1979

By J. M. Wempen, M. K. McCarter

"Differential Interferometric Synthetic Aperture Radar (DInSAR) is a satellite-based remote sensing technique capable of measuring centimeter-level surface displacement with high spatial resolution over large areas. Regular monitoring of subsidence due to underground mine development is one potential application of DInSAR, and in this study, the application of DInSAR for subsidence monitoring is evaluated for two mining regions in the mountain west of the United States. In general, DInSAR has potential to identify the shape and extent of subsidence; in some cases, magnitudes and rates of subsidence can be defined. Importantly, the effectiveness of DInSAR for subsidence monitoring depends on the radar band (wavelength), the subsidence rate and the time between image acquisitions, and the topographic and vegetative surface characteristics. INTRODUCTION Differential Interferometric Synthetic Aperture Radar (DInSAR) is a satellite-based remote technique that can be used to measure small surface displacements. Under good conditions, centimeter-level displacements can be measured with subcentimeter accuracy (Buckley, 2000; Massonnet and Feigl, 1998). Additionally, DInSAR data have relatively high spatial and temporal resolutions. Pixels in Synthetic Aperture Radar (SAR) images can have a ground resolution as small as about 3 m, and images often include tens to hundreds of thousands of pixels and cover tens of kilometers. Regions are imaged regularly, and periods between images typically range from weeks to months. In DInSAR, phase measurements from two radar images acquired over the same region at different times are used to precisely measure relative distances (Rosen, 2014). Surface deformation, topography, and changes in the satellite position all contribute to differences in the length of the path that the radar wave travels in each image. SAR sensors use radar with relatively long wavelengths; L-band (24 cm wavelength), C-band (6 cm wavelength), and X-band (3 cm wavelength) radar are used most commonly. Because the wavelengths are long, small changes in the path length of the radar signal can be quantified by measuring the change in the phase of the radar signal between the images. In general, changes in the path length due to changes in the satellite position and topography are known or can be estimated, and centimeter-level changes in the path length due to deformation are measurable. This study evaluates the effectiveness of DInSAR for measuring subsidence in two mining regions in the mountain west of the United States. L-band data from the Advanced Land Observing Satellite (ALOS) and X-band data from the TerraSAR-X mission are evaluated. Imaging characteristics, including the radar band and the time between image acquisitions, are important for effective subsidence monitoring."

Jan 1, 2017

By D. R. Taylor

Treatment of bentonite clay with mineral acids yields a modified clay product of high surface area and acidity which exhibits enhanced adsorptive and catalytic properties. A highly specialized segment of the clay industry based on this process has evolved into worldwide business with a capacity of about one-half million tons/yr. This paper will present data on the chemistry, mining, manufacturing and applications for acid- activated clays.

Jan 1, 1986

By S. J. Schatzel, V. Gangrade

A ventilation research study was conducted by the National Institute for Occupational Safety and Health and a cooperating trona mine in the Green River basin of Wyoming, USA. The mine operation uses the longwall mining method in trona bed 17, a commonly mined unit in the region. The longwall face length is 228 m (750 ft), and caving on the face occurred up to the back of the longwall shields. The mine is ventilated using a main blowing fan and a bleeder shaft. For this study, sulfur hexafluoride (SF6) tracer gas was released in two separate monitoring experiments. For the first experiment, tracer gas was released on the face, this test focused on airflow along the longwall face of the active panel. Face test showed the airflow patterns to be more complex than just head-to-tail flow in the main ventilation air stream on the active panel. For the second experiment, tracer gas was released 2 crosscuts inby the face on the headgate side, this test focused on gas transport in the mined-out portion of the same active panel. Gob test showed a pathway of movement through the front of the active panel gob that moved outby from the tailgate corner. The primary pathway of tracer gas movement in the active panel gob was towards the headgate and tailgate bleeders and out of a bleeder shaft. The rate of movement towards the back of the gob was measured to be 0.19 m/s (37 fpm).

By J. L. Heaver

All complete plant foods require phosphorus, nitrogen and potassium. And phosphate rock is the primary source for the phosphorus of the inorganic fertilizers. As more and more world food production is grown with these chemical fertilizers and since the Florida field supplies over 30% of the phosphorus component, let us look at the vital phosphate industry. Mining of phosphate rock in Central Florida began in 1891 and production has continued to grow at a steady pace. In 1965 a phosphate mine was opened in Hamilton County, North Florida and one in Beaufort County, North Carolina in 1966 . Since the beginning of mining in 1891, approximately 700 million metric tons of phosphate rock have been produced of this amount one-half was mined in the last 11 years. While the field was not deliberately "high-graded," the best of the known deposits were mined first. Those now being mined, and those yet to be mined, cost more to operate and the product is of lower grade. The U. S. Bureau of Mines' data for 1977 lists "Florida" phosphate rock production as 40.6 million tons; 86% of U. S. production and 85% of "Florida" capacity. The U. S. Bureau of Mines includes North Carolina production in "Florida" statistics so as not to reveal individual data for the one mine operating there. Approximately one-half of "Florida" production is exported, either as rock or as rock equivalent in upgraded products. Deposits of phosphate rock necessary to support present and future production are catalogued as: reserves, paramarginal reserves and resources. Reserves denote deposits which can be mined at a profit now. Paramarginal reserves are defined by the U. S. Bureau of Mines and the U. S. Geological Survey as: that portion of sub-economic resources that a) borders on being capable of production economically, or b) is not commercially available solely because of legal or political circumstances. The " b)" part of this definition may now be expanded to include environmental controls and requirements. Resources are deposits which cannot be mined at a profit at present. Listed in Table I are reasonable values for each of the three categories of phosphate deposits in the northern and southern parts of Central Florida. North Florida and North Carolina.

Jan 1, 1978

By Eric Sitorus, Septian Prahastudhi, Roy William, Wieda Azani

In July 2020, massive slope failure occurred in the southeast corner Grasberg open pit. This was the final episode in the breakthrough of Production Block 2 South (PB2S) of the Grasberg Block Cave to connect to the surface. This breakthrough had been rapidly evolving during the first half of 2020 and occurred as expected with no adverse impacts to safety or operations. To manage and safeguard the exposure to the workforce and operations, numerous hazards were identified and anticipated. The failure of the sill pillar between the open pit and PB2S cave was identified as the main area of interest and was closely watched during the failure process. This paper reviews the systematic approach developed to convert monitoring data into information around the collapse of the GBC PB2S cave sill pillar. The data that was interpreted consisted of micro-seismic, piezometric, ground-based radar and observational inspections. Geological structures on the boundary of the PB2S cave were clearly involved in the breakthrough process. As the cave propagation reached these structures and triggered instability, the resulting acceleration and breakdown were clearly shown by IBIS radar units associated with high movement in the slope. The focus of this paper is on the evolution of changes seen in the micro-seismic data and how it was used to understand the rapidly changing conditions of the sill pillar. The seismic parameters evaluated were event distribution, Es/Ep value, and the seismic moment tensor inversion. The changes of breakthrough indication seen in these parameters were substantiated by Shear Wave Splitting (SWS) analysis that showed a close correlation with the fractured zone above the PB2S cave as indicated by the increasing anisotropy.

Jan 1, 2022

By A. D. Hammond

"The drop in iron ore prices has claimed an unwitting casualty in vanadium. Vanadium is dominantly produced as a coproduct of steel production. The recent shutdown at EVRAZ’s Mapochs steel-vanadium operations in South Africa has cut off 10 percent of the world’s vanadium output. In February 2015, Australia’s Atlantic Ltd. suspended operations at its Windimurra iron-vanadium complex after a fire caused severe damage at the plant. Since then, challenging market conditions has resulted in the permanent closure of this operation.This decoupling of vanadium production from integrated iron ore producers presents an opportunity for vanadium exploration companies to target single-product deposits. This trend is manifested in the increasing number of pure-play vanadium ventures around the world.The mine production of vanadium is dominated by three countries — China, South Africa and Russia, which collectively produce 96 percent of the world’s vanadium. While the use of vanadium as an alloy in the steel industry remains the largest application for this metal, growth in demand is expected to come from the renewable energy industry in the form of batteries for energy storage.This article summarizes the current state of vanadium exploration, briefly describes the vanadium market and lists sources of future demand for the metal.Trend in vanadium explorationThe most active participants in the current vanadium exploration are pure-play vanadium ventures in Brazil, South Africa and Australia. These ventures are targeting deposits with higher vanadium grades than those typically mined in titaniferous magnetite operated by integrated steel-vanadium producers.The 10 percent shortfall in vanadium production resulting from the shutdown at EVRAZ’s Mapochs is expected to be partially compensated by Largo Resources’ Maracás Menchen vanadium operation located in the state of Bahia in Brazil. It commenced operation in August 2014 and is expected to produce between 7.6 and 8.6 kt (8,421 and 9,523 st) of V2O5 in 2016 at a target production cost of $3.71/lb (Largo Resources, 2016). This is the first primary vanadium operation to be placed in production in the Western Hemisphere in more than 35 years."

Jul 1, 2016

By R. F. Davis

The evaluation and selection of coals for producing metallurgical coke is indeed a com- plex process simply because coal is a complex and variable substance which is sensitive to how it is treated from the time it is mined until it is transformed into coke. A review of the the more common evaluation tests made on coal and how the test results are applied in commercial practice. Parameters used to select coal blends for wet and preheated charges should also be of interest.

Jan 1, 1980

By T. Karalis

Perlite is a generic term for naturally occurring siliceous rock. It is a form of natural volcanic glass the main constituent of which is amorphous silica (70-76%). Perlite, when heated rapidly to its softening temperature range, expands from four to twenty times its original volume, due to the presence of 2-6% ?combined? water, in a manner similar to popcorn as the H2O molecules vaporize and create countless tiny bubbles, which account for its exceptional physical properties: light weight (30-150 kg/m3), low thermal conductivity, cellular structure, in general. These properties make perlite adaptable for numerous end-uses, which can be distinguished into 2 categories: Expanded perlite applications in: a) Construction Materials market (e.g. Acoustical Tiles, light-weight insulating Mortars, self-levelling Concrete), b) Agriculture (e.g. Hydroponics), c) Food and Chemical industry (e.g. Filtration Media, Filler, etc.), d) Insulation and Heat resistance technology (e.g. Cryogenic vessels, Refractory Bricks, etc.). Unexpanded Graded perlite applications in: a) Phosphoric Fertilizers industry (additive in H3PO4 production), b) Foundry technology (slag-aid, insulating and heat resistance agent).

Jan 1, 2006

By Manuel R. Lastra

Critical to successful dump and heap leaching for gold, silver, copper and uranium are factors such as permeability, solution delivery to the ore, and solution recovery. This paper deals with possible techniques for successful accomplishment of these three factors. New developments as well as older techniques are discussed, together with rationale for use of some techniques in reference to others. The authors hope to present a checklist so that the ideal application to individual mine situations can be achieved. This involves a discussion of the merits of each different method and the situations for most logical application. It is hoped that such discussion will broaden the geographic areas where dump and heap leaching can be applied to include greater winter cold and tropical regions of large amounts of rainfall.

Jan 1, 1984

By C. Ek

Tailings originating from the gravity concentration of a gold ore containing about 14 g/t Au have been treated by various beneficiation methods. These tailings have been screened on the 147 and 74 micron sieves and the two coarsest fractions have been separated on shaking tables with unsatisfactory results, but the concentrates have been examined in polished sections for mineragraphic analysis. Very simple flotation flowsheets have been applied to collect most of the gold, recovery and grade varying with the regrinding time in a ball mill. Cyanidation tests have shown that this type of treatment is also applicable to such tailings.

Jan 1, 1991

By Hillary W. St. Clair

In a previous report 1/the author showed that the essential information from particle size analyses of grinding mill products can be represented by three or four parameters derived from the first four moments of the particle size data. These parameters may be used in gamma or beta distribution functions to estimate the weight fraction in any given size range. Moment analysis was used to study the progressive changes that take place in particle size distribution when a homogeneous isotropic mineral such as quartz is reduced in size by impact crushing. 2/ This report briefly reviews the essential features of moment analysis and describes extension of this method to size reduction by ball mill grinding.

Jan 1, 1972

By R. W. Sims

"He?s an SOB, but he's my SOB." Many of us have heard this line in reference to attorneys, and can appreciate the humor. However, the thought reflects a deeper attitude that lawyers should be used for attack purposes in the legal system or the regulatory process. Often, more permitting progress can be made with tact and flexibility than with inflexible, overly aggressive strategies. Usually, administrative hearings or other litigation work to the disadvantage of the applicant. Thus, I have concerns about approaching any permitting system with a hard-line attitude. On the other hand, the project team must always be prepared to defend permit applications and present a legally adequate case at public meetings, administrative hearings, or judicial proceedings. This paper discusses a number of strategies intended to increase the probabilities for successful permitting, whether opposition is informal or highly organized.

Jan 1, 1990

By J. W. Parkinson

With most of the coal currently mined in the eastern U.S. already requiring cleaning to meet electric utility coal specifications, the question remains how medium- and high-sulfur coal producers will provide the even better quality coal expected to be demanded if pending acid rain legislation is enacted. One emerging approach is to crush the coal to liberate additional ash and sulfur so that better quality coal can be produced at equal yields. This paper discusses how to measure liberation. the premiums the utility market is willing to pay for lower sulfur coal, and a staged middlings crushing scheme that promises the benefits of total raw coal crushing but at lower costs. For some coals, cautious application of liberation concepts may be the only way to produce a product that can be quality and cost competitive in the future utility coal market.

Jan 1, 1988

By R. L. Grayson

For the years 1990 and 1991, West Virginia's underground coal small-mine fatality rate « 20 employees) was approximately ten times higher than the national coal industry rate. Although the total number of fatalities decreased to 17 in 1992 (from 22 in 1991), West Virginia still led ,the nation in coal mining fatals. A team of mining and safety professionals from West Virginia University studied the problem over the past year, interfacing with the Mine Safety and Health Administration and the West Virginia Office of Miners' Health, Safety and Training. A clear path for 'formal intervention was determined and is presented here.

Jan 1, 1994

By Victoria Vaccarezza, Corby Anderson

The demand for rare earth elements for everyday technology and applications has initiated much research into the extraction and recovery of these rare earth elements. An otherwise unknown group of minerals, eudialyte is a zircon silicate consisting of rare earth oxides (REO), contained in a unique mineral structure and represented by a complex chemical formula. Research into extraction and recovery of rare earth elements involves various beneficiation and hydrometallurgical techniques. The goal of beneficiation being to efficiently liberate and upgrade the REO content, followed by hydrometallurgy to extract the desired elements. This overview will discuss previous research on treating eudialyte group minerals via different mineral processing and extraction techniques.

By Samer Sadek, Phoebe Cheng, Changmo Kwon, Myat Ohn

BART Facilities Standards (BFS) Structural Criteria is a living document that governs planning, design, and construction of all BART projects. Since its development, the document undergoes incremental changes and updates to reflect policy changes, changes in local, State, or national design codes and guidelines, advancements in engineering and technology, or based on the performance of past built infrastructure. In 2020, the BFS-Structural Criteria underwent a comprehensive update and was released with BFS version 3.2. This paper summarizes the updates to the Tunnels and Underground Structures Section of the Structural Criteria, and provides insights to the basis and logic of the requirements.

Dec 1, 2022

By Ronald P. Wright

ARAMIDS UNDERGROUND COAL MINING

Jan 1, 1993

By Marco Sonnenschein

Belt conveyors for tunnelling are industry standard and key to high performance of TBM drives. Conveyors reduce traffic in the tunnel and increase safety in the tunnelling process. This paper will illustrate the state of the art of tunnel belt applications in very long and curvy tunnels like the Coxwell Bypass Tunnel Project in Toronto, Canada.

Jun 23, 2024

By Charles A. Beasley

Increased technical and legislative analysis by all parties of interest could result in more efficientand better directed regulatory legislation in the mining industry. Efforts to forestall or frustrate legislation through massive lobbying and public relations efforts are seldom effective over time and often lead to more stringent and far reaching legislation than necessary. The Federal Coal Mine Health and Safety Act of 1969 is perhaps an outstanding example of such insufficiences; a future example may well be regulatory surface mine legislation. Although a lack of extensive hard data seldom enables rapid or sophisticated analysis early in the legislative process, even preliminary analysis may be sufficient. Simple statistical analyses of available data, assessment of the legislative rationale, and subjective appraisal of other non-quantifiable constraints to improved mine safety. An average of 115 underground fatalities at an exposure frequency rate of 0.67 can be reasonably expected in the immediate future, under existing levels of technology, degree of regulation, and economic conditions. If gross unrefined estimates of 6 preparation plant, 5 surface, and 30 strip mining fatalities are assumed, the total fatality industry level could be expected to approximate 156 Serious professional, economic, and technical constraints within the the industry probably preclude any major decrease of these accident levels within the near future

Jan 1, 1972