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By K. Y. Haramy

A scale-invariant theory of the strength and deformability of rock masses in static equilibrium and at incipient failure is proposed. The theory provides a rationale for designing structures in rock. This paper presents results of experiments conducted by the U.S. Bureau of Mines and theoretical methods to determine and interpret in situ strength of rock masses using the borehole shear tester.

Jan 1, 1995

By Ronald C. Severson

Crystals of native gold occur in placer-type deposits. Gold, as a pure metal, is the most malleable metal known; therefore, delicate gold crystal forms should not survive mechanical transport and concentration processes involved in placer formation. To test the hypothesis that the crystalline gold is currently forming in place, two active gold-placer operations and an unmineralized background area in Alaska were examined. At these sites, rock outcrops, soil profiles, and native vegetation were sampled. At one sampling site, the soil was panned and yielded crystalline gold, as well as the more common rounded nuggets. The plants and soils were analyzed for their major, minor, and trace-element contents, especially gold. Two procedures, one a simple demineralized water leach and the other a partial digestion with acetic acid and hydrogen peroxide, were also used to extract gold and various anions from soils. The water-extractable gold ranged from <0.02 to 15.0 ppb Au in the extracting solution. This represents as much as a 104 enrichment in gold over average river water. This extractable gold is probably available to the native vegetation. Gold concentrations in the unashed dry plants from the two placer sites ranged between 0.4 and 106 ppb compared to a background range of <1 to <4 ppb Au. The presence of dissolved organic matter in the soils is thought to be responsible for the dissolution, transportation, and precipitation of gold in these placer soils, and this process is presently active in these soil profiles.

Jan 1, 2013

By R. L. Garrett

The quality of mineral additives used 1n a drilling fluid (mud) can dramatically affect the fluid&apos;s properties and the overall cost of drilling an oil or gas well. The principally used minerals are bentonite, barite, barite/hematite blends and hematite alone. The high specific gravity minerals, barite and hematite, are used to increase drilling fluid density. Bentonite clay is used to increase drilling fluid viscosity, gel strength and to provide a low permeability filter cake. A multi-million dollar investment in a well and the safety of the personnel on the drilling rig can depend on how effectively these mud additives perform with other constituents in the mud. This paper points out effects caused by small amounts of certain carbonate and sulfide mineral impurities in barite or hematite and how polymeric extender additives in bentonites contribute to unpredictable behavior of a mud. Effects like these are the reason why oil companies who use these materials sometimes set their own quality standards beyond those already specified in API Spec. 13A. Also discussed in this paper are the current standardization activities in API Committee 13 on these minerals.

Jan 1, 1986

By Francois E. Heuze

This paper summarizes the geomechanics programs conducted in two hard rock underground mining operations in the Western United States, between 1966 and 1981. The two projects were directed towards understanding the behavior of the rock masses, at the scale of the caverns. To this end, the emphasis was put on large scale field measurements, complemented by limited laboratory testing. The results of these observations were used to build realistic finite element models of the underground chambers. In the marble mine, at Crestmore, California, the models were applied to the structural optimization of the room-and-pillar pattern. In the granite mining, at Climax, Nevada Test Site, the models explained some unusual stress changes observed during excavation. Based on the large number of geomechanical techniques employed, specific conclusions and recommendations are offered regarding the quality, applicability, and usefulness of the various methods. The two case histories clearly indicate chat numerical models are extremely useful for a detailed understanding of the structural behavior of mine openings. To be realistic, these models must be based first and foremost on large scale field observations. The lessons Learned on these two projects also are directly applicable to the design and analysis of nuclear waste repositories in hard rocks such as basalt, granite, and welded tuff.

Jan 1, 1982

By Cody Giroux, Homer Scurlock, Michel Wasag

Silica and Crystalline Quartz exposure continues to be a serious health threat to nearly 2 million workers in the United States, including more than 100,000 working in high risk jobs such as abrasive blasting, foundry work, stonecutting, rock drilling, quarry work, mining and tunneling. The primary focus of this study is to identify the best methodology to reduce particulate-laden air and limit/eliminate exposure to respirable dust with silica/crystalline quartz during tunneling operations. This study focuses on two de-dusting systems employed on similar tunnel construction projects. The first project is the Coxwell Bypass Tunnel located in Toronto, Ontario Canada. The second project is the Westerly Storage Tunnel located in Cleveland, Ohio. The Toronto project is utilizing a wet de-dusting system. The Cleveland project is using a dry de-dusting system. The objective is to determine which system provides the best protection and suitability to capture, remove and ultimately reduce respirable concentrations of silica/ crystalline quartz to safety and healthy levels in underground tunneling activities.

Jun 13, 2021

By T. A. Oberhellmann

The Wobbler Feeder is a comparatively new materials handling and separating device. It is essentially a materials separating or scalping machine, particularly adaptable to separation of oversize particles from mine-run ore and to the separation of oversize materials from overburden, where the removal of oversize materials is necessary, as is the case in conveyor stripping. In construction, the Wobbler Feeder is simply a set of transverse bars of manganese steel, or other wear-resisting alloy steel, each having an elliptical cross-section with the major axes of adjacent bars displaced by ninety degrees so when rotating in unison, the pre-determined space between the bars remains constant.

Jan 1, 1959

By T. W. Peterson

There are two approaches to developing a minicomputer based application for an industrial grinding circuit. Usually, the control program is coded and compilation-debugged on a large-scale scientific computing system or the minicomputer itself if the machine is available. Final debugging and testing must wait for installation and checkout of the entire minicomputer system. Two immediate disadvantages of this approach are the need to obtain, install and check out the hardware before the final debugging stages of program development can begin, and interference with normal mill operation during such final testing. This work reports on an alternative to the usual procedure. Here both compilation and execution bugs are eliminated from the application program before hardware installation by testing the control program against a reasonable dynamic simulation of the entire process. Thus, software development can be completed before the target mini is installed. Such off-line development requires a reasonably accurate mathematical model for the entire process system as well as a suitable simulation package for communication between the simulated environment and the minicomputer application program. Specific data describing the design configurations and dimensions of the mills, cyclones, sumps, pump characteristics and analog controller configuration were supplied by ANAMAX for a grinding division consisting of a rod mill followed by two ball mills in parallel. This information was used to set up a plausible model structure. Steady state ANAMAX data on particle size analysis at various points in the circuit and corresponding values of flow rates, pump speeds, sump heights and slurry densities were used for model parameterization. The preferred operating control strategy - "best grind at operator-set rod mill feed rate" - was set by ANAMAX. An inferential particle size analysis technique using the cyclone cluster as an on-line particle size sensor was used in a novel control strategy_ to achieve the stated objective. Two disturbances common in the ANAMAX circuits - rod mill scoop pluggage and shut down/start up of one of the ball mills - were studied in detail. This report out- lines the steps in system development and testing and the results obtained.

Jan 1, 1974

By Christopher Mark

Successful longwall gate entry design requires control of both vertical and horizontal stresses. Vertical, or overburden, stresses are most severe in the tailgate where they are concentrated by longwall panel extraction. Horizontal stresses, which are generally tectonic in origin, can be highly destructive during the development and headgate phases of longwall mining. The goal of this paper is to present the current state-of-the-art in detecting and controlling horizontal stresses. The information presented was collected through site investigations at 45 U.S. longwalls and an international literature review. The paper begins with a discussion of the present knowledge of regional in situ stress fields in the U.S. A review of available underground stress measurements from coal mines is presented, along with data collected by structural and petroleum geologists. The combined evidence indicates that a persistent ENE-EW trending stressfield is present throughout the eastern coalfields. Experience with horizontal stress in longwall mines is addressed next. The paper focuses on the northern Appalachian region, where the effects of horizontal stress have been most evident. Three case histories are discussed in detail, and the solutions each developed are highlighted. Observations made in the Southern Appalachian, Alabama, and Illinois coalfields are also described.

Jan 1, 1991

By M. Ge

Pattison Mine is a small sandstone mine located in Iowa. The sandstones produced by the mine are not common construction and aggregate materials. The stones are used to produce a special type of sand for hydraulic fracturing, a critical technique for recovering tight gas and shale gas. These sandstones are very different from the minerals and rocks which have been studied extensively in mining. On the one hand, they are brittle as characterized by an unusually high friction angle, up to 69°, and steeply curved failure envelopes. On the other hand, they are friable, possessing extremely low, and in most cases zero cohesion. The scarcity of the ground control techniques for this particular mining environment has created many difficulties for the mine operators. In order to resolve these problems, a research program was set up by the mine and Missouri University of Science and Technology. This paper discusses the preliminary results of this investigation.

Jan 1, 2012

By Siddhartha Roy, Hemant Agrawal, Ram Madhab Bhattacharjee, Devi Prasad Mishra

The paper addresses heat stress in underground coal mines, which poses significant threats to miners’ health, safety, and productivity. It involves a comprehensive ventilation survey in three deep and mechanized underground coal mines in India. Using VentSim software, 3D simulation models were developed to predict heat stress conditions and explore the application of auxiliary ventilation and spot coolers to reduce heat stress.

Oct 1, 2023

By Howard Lum, Sergio Valles, John Bednarski, Gordon Enas, Jay Arabshahi

"Water drawn from the Sacramento-San Joaquin Delta provides water supply to 66 percent of California’s population and supports the state’s agriculture industry. The existing through-Delta water system is outdated and unreliable with environmental risk to some fish and wildlife species. The Bay-Delta Conservation Plan (BDCP) has been established to environmentally retrofit and modernize California’s water delivery system through the Delta by restoring habitats, constructing new diversion points in the north Delta and providing a means to transport water supplies under the Delta, rather than through sensitive natural channels.Under BDCP, the Delta Habitat Conservation and Conveyance Program (DHCCP) has developed several alternatives to convey water from the Sacramento River in the north to the existing pumping facilities in the south Delta through an isolated conveyance system. The new conveyance system would become an integral part of the State Water Project (SWP) and the federal Central Valley Project (CVP) by transporting water to the export pumping plants for each of these projects. The DHCCP is managed by the California Department of Water Resources (DWR), while state and federal water contractors provide technical support to the program.The initial conceptual study efforts on the overall program commenced in 2007 and examined various options for the proposed conveyance system. Several conveyance alternatives were analyzed at that time. The Conceptual Engineering Report published on Oct. 1, 2013 identified the modified pipeline/tunnel option (MPTO) as the preferred alternative to be included in the BDCP environmental documents. MPTO includes three river intakes and pump stations along the Sacramento River, various sizes of pipelines and tunnels, junction structures and two forebays that are capable of delivering up to 4 million gpm (9,000 cfs) from the Sacramento River to the SWP and CVP. The river intakes are located near Hood in Sacramento County approximately 64 km (40 miles) from Clifton Court Forebay (CCF) in Contra Costa County. This route would cross portions of Sacramento, San Joaquin and Contra Costa counties. Figure 1 depicts the configuration of the MPTO alternative."

Apr 1, 2016

By James J. Scott

Introduction Friction Rock Stabilizers, trade name Split Sets, are presently under research and development by Ingersoll-Rand Company and Dr. James J. Scott, inventor. Conceived in 1953, the system is a patented process undergoing extensive field and laboratory testing. The author has published papers on the Split Set System earlier (References 4, 5, 6) The Split Set System holds promise to be a revolutionary development in the field of ground control. The system produces an interior reinforcement to a rock mass which: 1. Is simple in its concept. 2. Adjusts to the degree of restraint needed to match rock properties. 3. Provides a yieldable support and, later, a more rigid support as it is needed. 4. Pre-loads the rock in compression to increase stability. 5. Is a full-contact, fully tensioned device to resist rock loads. 6. Minimizes the stress concentration effects inherent in many interior support devices. 7. Improves safety for the miner. 8. Is cheaper than a grouted system. 9. Offers the rock mechanics engineer an opportunity to design in a fashion not before possible.

Jan 1, 1977

By Don Opacic

The disposal of sludges and other similar industrial wastes is a major problem. Liquid wastes from industrial operations, when treated, produce significant volumes of sludge which are difficult to dispose of, because of the chemical and physical properties of the sludge. In the mining industry sludge is produced from various water treatment operations, in particular mine drainage neutralization. Waste water from coal preparation plants also produces a sludge however the sludge is in fact a slurry containing clays, coal fines and coal impurities. In many areas the disposal of these sludges is producing a serious problem. Mine drainage sludge consists of a variety of hydrous iron oxides, usually ferric oxides, contaminated with other neutralization products such as calcium sulfate. The volume of sludge from mine water or mine

Jan 1, 1973

The structure of a mine ventilation network (M.V.N.) can be represented graphically using either the mine plan (map) itself or a number of other types of diagrams. In the U.S., the two most common approaches are the line and the schematic diagrams (see Figures 1 and 2). The purpose of this paper is to introduce another type of diagram, called the canonical diagram (6). The method of M.V.N. representation which uses canonical diagrams is used extensively in Europe, and especially in Poland, where it was developed. The canonical diagram is a noncalibrated topological image of a ventilation system. It gives a simple representation of the ventilation network, allows for the classification of currents within it and enables rapid computer analysis and computation, as well as the representation of the results. It is especially useful in studying and controlling the air flow, and it may be a life saving tool in conducting rescue operations during and after mine fires.

Jan 1, 1986

By F. J. Hurst

Phosphate rock, which is a prime source of phosphate used in fertilizer manufacture in the United States, contains uranium. In general, the uranium content of the rock increases with the phosphate content and most high-grade phosphate deposits (>30% P2O5) contain 0.01- 0.02% U3 8. The large tonnages of rock being mined represent a significant potential source of uranium that lends itself to recovery as a by-product of the wet-process phosphate industry. For example, in 1953, the U. S. Geological Survey estimated that recoverable phosphate reserves in the U. S. totaled about 5 billion tons and contained 600,000 tons of uranium. I This estimate did not include any rock from North Carolina which has since been estimated at about 2 billion tons. For the most part, the known, economically mineable U. S. reserves - estimated at about 7 billion tons - are concentrated in a few areas: 43% in the western states of Idaho, Montana, Utah and Wyoming; 28% in each of Florida and North Carolina and less than 1% in Tennessee. In the past, Florida has supplied about 80% of the total U. S. production, practically all of which is land pebble phosphate. All forecasts indicate increased production rates from North Carolina and the western states.

Jan 1, 1976

By A. W. Czarnowsky

More than ever before, mining projects are besieged from growing regulatory, political, public, and special interest group pressure. Administrative and legal appeals to permits and environmental documents can delay project start-up and add tremendous cost to mineral development. Some mining projects have been canceled given undue external constraints. Successful managers must learn to cope with these constraints. This paper will discuss controversy and present a number of environmental management tips to minimize the potentials for delay and to lessen the impacts from government and anti-mining pressures.

Jan 1, 2001

By L. Adler

To properly analyze and apply mining equipment, a systematic, current, inclusive, and simple classification scheme is required. This paper provides such a classification for Roadheaders. This Roadheader classification is based on factors, such as the rock cutterhead, the boom type, and the chassis configuration. It first assigns Roadheaders as an equipment type within the larger group of Integrated Excavators. The Roadheader type is then delineated into the following subtypes: the standard, the extended boom, the tunnelers, and the miscellaneous. Next, these subtypes are devolved into kinds, and finally variants and attachments are considered. To resolve inconsistencies in characterizing the Roadheader, cross-referencing is employed within the classification scheme.

Jan 1, 1996

By A. S. Azman

The mining workforce experiences high rates of hazardous noise exposure and hearing loss. However, previous studies have identified specific behavioral and attitudinal barriers that keep miners from effectively acting to prevent their own hearing loss. NIOSH has developed several new hearing loss prevention tools and interventions that specifically target these barriers to prevention. The NIOSH Hearing Loss Simulator addresses motivation to take action and knowledge about the consequences of noise exposure. The QuickFit earplug test device and QuickFitWeb online hearing protection tester address barriers to effective earplug and earmuff use by verifying at least 15 decibels of protection. The NIOSH Roll-Pull-Hold technique helps miners obtain better protection through an easy-to-remember set of steps that improves attenuation by 9 decibels. The ?Inquiring Ears Want to Know? fact sheet helps miners to understand audiograms and to use them to maintain their hearing health. Each of these interventions can be used within the context of a comprehensive hearing loss prevention program.

Jan 1, 2010

By C. J. Hall

I would like to congratulate Professor Gershon on an idea that is obviously valuable and is certainly new to me. It has, however, to be further developed, in that one can get fallacious results by limiting oneself to positional weights. In the example problem, the positional weight of one block was 8.6 (the 8.0 value in the paper was incorrect) for 36 units in the cone, for a mean block value of 0.239. The positional weight of the second block was 4.4 for 15 units, for a mean block value of 0.293. Surely one would expect the second block to be rated higher. Additionally, the time value of money adjustment cannot be determined by depth, because the time that a block is mined is determined by the mining sequence, not depth. Figure 1 shows a slightly altered version of Professor Gershon&apos;s pit. The overall value of the pit is the same, as are the total values under each of his blocks. The values in the right-hand cone have been reversed top to bottom, and the values in the rest of the pit adjusted to keep the central cone total unchanged. All values have been multiplied by 10. Figure 2 shows the sequence of mining, at three blocks per year, for Professor Gershon&apos;s pit, and Fig. 3, the sequence for a pit under the other block. Table 1 shows the value and discounted value (15%) of Professor Gershon&apos;s pit, and Table 2 shows similar values for the second pit. It is apparent that the second pit schedule is more valuable than the first.

Jan 1, 1988

By Harry Perry

U. S. consumption of sulfur and sulfur products is expected to increase at a rate of 8 percent per year between now and 1980, largely as a result of their use in fertilizer markets. World consumption is also increasing rapidly, but at a-lower rate, about 6-percent per year. In 1965, sulfur recovered in the United States from purification of natural gas; nearly doubled from the 1956-1960 average; production from pyrites declined; and production of elemental sulfur increased 15 percent. Concern about air pollution resulting from sulfur oxides produced from the combustion of fossil fuel has lead to intensive research on methods of removal before combustion, during combustion (in-process methods), and from the resulting flue gases. If all the sulfur in fossill fuels were recovered, more sulfur products would be produced than were consumed in the United States in 1965. Removal of sulfur from coal before combustion could result in a product sufficiently-high in sulfur to be a suitable raw material for sulfuric acid manufacture. In-process methods produce solid sulfates, some of which may have commercial value. Flue gas removal&apos; methods for sulfur oxidest generally result in the production of a byproduct either of sulfuric acid or sulfur. The projected sale of these materials significantly lowers the anticipated cost of sulfur dioxides pollution abatement. Alternate methods for sulfur dioxide reduction are discussed. The various proposed processes are described and costs are given for the various methods for which estimates have been made.

Jan 1, 1967