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By C. C. Clark

The national Institute for Occupational Safety and Health (NIOSH), Office of Mine Safety and Health, Ground Control Engineering Branch is investigating the use of shotcrete in weak rock mass mines with the objective of reducing fatalities and injuries resulting from rock fall accidents. When shotcrete is used as part of a multi-element ground support system, it is necessary to know when the material has developed a compressive strength of approximately 1 MPa (145 psi), the early threshold for safe re-entry of miner and machine into shotcreted mine workings at this value, the material has developed enough strength to be self-supporting and to allow for installation of other ground support components that require drilling of the shotcrete layer without degradation. NIOSH researchers have developed methods and portable test equipment to measure shotcrete strength on site in the first six hours after application using a partial beam test standard, a STM C 116-90 (1990). These advances were demonstrated in tests with five commercially available shotcrete mixes, sprayed as dry shotcrete using field expedient methods and equipment. The strength values from these tests allowed for real-time identification of the early strength threshold and were consistent with strengths reported using laboratory-type equipment. Measuring the early strength properties of shotcrete directly at the mine site can improve mine safety by identifying appropriate re-entry times and providing a convenient means of conducting on site quality control during shotcrete applications.

Jan 1, 2011

By T. J. Smolik

The Golden Sunlight Mine started full-scale operations in February 1983, with a conventional open-pit mine supplying 4464 tonnes (5000 tons) per day of milling ore. After crushing and grinding, the ore is leached with cyanide solution in large agitation tanks. Soluble gold values are removed from the sand portion of the leached ore with five stages of countercurrent washing cyclones. After thickening of the cyclone-wash overflow slurry, the gold is recovered in activated carbon with a six-stage carbon-in-pulp circuit and a five-stage upflow carbon column circuit. Pressure stripping, carbon reactivation, electro-winning and refining complete the gold recovery process.

Jan 1, 1984

By Enrico Pavese, Tim Kearney, Stefan Lemke

Watertightness is of central importance in hydraulic and underground structures but has always been associated with a risk, as demonstrated by the very high impact that water inflows have on the damage of linings and infrastructure (Howard, 1991; Sandrone and Labiouse, 2011). Concrete is vulnerable to groundwater and chemical contaminants in the soil. These can leach into the pores and cracks of the concrete and degrade its integrity, causing spalling and corroding the reinforcing steel. Moisture migrating into the building can also degrade structural elements over time and lead to mold and other hazards to occupants’ health. In this connection, the demands placed on the setup and detailed design of the seal depending on the negative influence by water on the one hand and on the other hand on the function of a construction in view to its watertightness classification. Thus, the reliable functioning of a seal is of particular significance in the case of traffic tunnels, which are not easily accessible for all subsequent repairs after the construction in seepage water and especially when located in a pressure water zone (risk–cost assessment). Requirements for the long-term efficiency and quality of underground structures have increased in recent decades. Today, the standard lifetime requirement for an underground infrastructure project is 100 to 120 years and, in some cases, even higher. This calls for high increased attention to the durability of the whole structure and of each individual element. Standards, which started as application guidelines given by the manufacturers, are available in the market since the 1980s and are constantly adapted to the current developments in various technical committees. Differentiations are made between: Manufactures application guidelines, case studies or published articles Test standards for the laboratory to guideline the testing procedures (air temperature, type of test equipment, dimensions, test speed, test duration, concentration, type of liquids, monitoring, tolerances, interpretation of results, documentation, etc.), developed by committees based on material and laboratory experts Application standards, which include test standards but also the related minimum performance requirements (values) for material, processing, and quality assurance (practical tolerances), developed by committees based on a wide range of experts (e.g., designers, construction companies, applicators, manufactures, owners, test institutes, quality engineers) and therefore also based on a wide field of experience, different views and up-dated case studies. In the following there are some examples of guidelines and published information’s, ranked according to the year of issue, which are relevant for the development of waterproofing specifications in the tunnel industry:

Jun 13, 2023

By Catherine C. Kilgore

The Bureau of Mines investigated the availability of fluorspar from 35 domestic and 50 foreign, mines and deposits in 13 countries. Only 6 domestic properties are considered to be economic reserves, as 29 domestic deposits were found to have an average total cost of production that was uneconomical at a breakeven (0 pct) DCFROR. The 50 foreign properties evaluated were selected to represent at least 85 pct of the known demonstrated fluorspar resources located in market economy countries and China. All evaluated foreign operations were found to be economic to marginally economic in January 1984 dollars. World demonstrated ore reserves of 344 million metric tons (mt) containing 123 million mt of CaF2 were evaluated for the 56 operations. Average total costs needed to cover all costs over the life of each operation were determined for all recoverable fluorspar products. Comparisons of mining, beneficiation, and transportation costs per mt of fluorspar concentrate illustrate advantages between countries. Of the three largest producing countries, China, with its high-grade, low-cost operations had the lowest weighted average total cost of production ($38/mt concentrate). Mexico was next at $54/mt concentrate, and South Africa needed an average of $90/mt of concentrate to cover all costs of production for its low grade deposits.

Jan 1, 1985

By P. James

Blue Planet Strategies (BPS) focuses on improved resource utilization and targets converting wastes into resources. New BPS capability (DEMET) wrings extra value from mining and processing wastes by enabling new production from waste and residual sources. This powerful platform technology provides considerable processing flexibility and enables various new economical treatment options to extract key metals from low level and process byproduct stream sources normally left as waste by traditional processing methods.[1]

Feb 23, 2014

By A. A. Dor

Recent developments in the design of concentration plants have reflected the increased recognition that has been given to the economic and metallurgical advantages of autogenous grinding. This has manifested itself in the increasing adoption of primary auto genous grinding in iron ore 'beneficiation plants in North America. Table 1 lists eleven major iron ore beneficiation plants which have either been put in operation since 1961 or are under construction at present. Seven out of these eleven plants have adopted primary autogenous grinding. Four of them have coarse grinding mills (8 to 14 mesh) and three have fine grinding primary circuits (48 to 65 mesh). Their nominal capacity totals 26. 2 million ltpy of concentrates or pellets, representing very nearly 75% of the aggregate capacity 135. 3 million ltpy) of the eleven concentrators listed. For a long time there was a tendency to consider that primary autogenous grinding was only applicable to suitable coarse grained ores, However, extensive testing of a very wide variety of ores, and actual operating performance in several commercial plants, seem to have established beyond reasonable doubt, that the majority of mineral ores which the beneficiation engineer may be called upon to process can be ground autogenously. The basis for the selection of autogenous or conventional grinding mills, becomes principally economic and depends on the liberation characteristics of the ores under consideration and their relative hardness and grindability.

Jan 1, 1965

By J. V. Belke

There are many aspects of a grinding mill supply and installation that can result in the mill not operating as intended, resulting in unplanned shutdowns, poor reliability and headaches for all concerned. One of the largest aspects, both in criticality and physical mass, is the mill foundation; if not properly specified, designed and constructed the mill operation will be compromised. The mill foundation starts with the design specification and loading diagram supplied by the mill builder. The importance of understanding these documents and how to apply them is critical for the start of any mill project. When designing mills with a GMD the foundation must be properly modeled to ensure that all interactions of the mill and motor structures, foundation and subsurface strata behave in the intended fashion. All of the previous efforts can be laid to waste if the construction of the mill foundation is poorly handled. Mill foundations are typically the most massive concrete structure at a processing plant and can easily cause nightmares for inexperienced contactors. This paper explores some of the more important facets along the lifecycle of the grinding mill foundation.

Feb 23, 2014

By Jerry M. Riggsbee, John H. Weber

INTRODUCTION The Washington Metro is a 98 mile rapid transit system that will serve the District of Columbia, southern Maryland, and northern Virginia. The construction work herein described relates to Section B-1 of this system. The contract for this work was awarded by the Owner, The Washington Metropolitan Area Transit Authority, to a joint venture doing business under the name of Ball-Shea-Norair. The partners in this venture were Gordon H. Ball, Inc., Danville, California; J. F. Shea Company, Inc., Walnut Creek, California; and Norair Engineering Corporation, Washington, D. C. The bid price for the project was $33,741,524 with a contract duration of 910 calendar days. Notice to proceed was issued January 5, 1970. The present modified price for the work is $36,866,000 with completion anticipated in July 1974. (About 1,638 days elapsed time.) The work to be done consisted essentially of construction of 3,490 linear feet of cut-and-cover track with side platform, and 600 ft cut-and-cover arch shaped subway stations. Stations are located in Judiciary Square and Eighth & G Street, N. W., areas. Decking of excavation in street areas, maintenance of traffic and utilities, vent and fan shafts, underpinning of court buildings in Judiciary Square and the Smithsonian National Portrait Building, and an electrical substation were included in the contract. Stations were constructed of cast-in-place concrete.

Jan 1, 1974

By Paul H. Johnson

Heap leaching is a simple means of recovering copper from oxide and oxide-sulfide ores. Although this method requires relatively low capital investment, it suffers from low copper recoveries and relatively high acid consumption. The objectives of this study were (1) to determine what factors influence these shortcomings, and (2) to establish a basis of correlation. between laboratory and field testing. The principal methods of leaching copper ores at the present time are heap, dump, in-place, and vat. A number of references are presented in the bibliography on the theoretical and practical aspects of these methods. In the heap-leaching method, crushed or uncrushed oxidized copper ore is placed on a prepared drainage pad. Acid leach solutions are dis¬tributed over the top of the heap, caused to percolate downward through the ore bed by gravity, and are drained from its base. The leach duration is generally a matter of a few months. Dump leaching is used to recover copper from very low-grade oxide-sulfide pit-waste materials. Here again, leach solutions are, percolated downward through a heap. However, in this method, little or no acid is added to the leach liquors, prepared drainage pads are not used and the leaching cycle is generally measured in terms of several years. Leaching agents are usually autogenously generated by the breakdown of sulfide minerals within the dump.

Jan 1, 1970

By Kent Phillips, Meredith Scaggs-Witte, Emily Sarver, Cigden Keles

"After nearly four decades of decline, the prevalence of coal workers’ pneumoconiosis (CWP, or black lung) in the United States has been on the rise since the mid-1990s (Laney et al., 2014; Laney et al., 2010; Suarthana et al., 2011; Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2016). Particularly alarming is the number of cases of rapidly progressive disease such as progressive massive fibrosis (PMF) (Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2016; Laney et al., 2017). A recent study by Laney et al. (2017) observed 192 U.S. coal miners participating in the Coal Workers’ Health Surveillance Program (CWHSP) who had been diagnosed with PMF since 2000. Of the 163 (85 percent) that had a normal radiograph on file to use as a baseline, 27 (17 percent) of these individuals had progressed from a normal radiograph to PMF diagnosis in less than 10 years. Moreover, 162 (84 percent) of the individuals in that study worked in Kentucky, West Virginia or Virginia, and 169 (88 percent) had only ever mined underground. Blackley et al. (2016) also reported on a group of 60 PMF cases that were discovered by a single black lung clinic in eastern Kentucky. Since seeking care at such clinics and participation in the CWHSP are voluntary, and could be influenced by a number of factors, there has been some concern that these reports may overestimate the degree of resurgence in severe disease (i.e., versus disease that was previously under-reported). Even so, they highlight a critical need to better understand the cause(s) of disease development and progression — such that effective interventions can be devised.The notable uptick in CWP and PMF rates among miners in central Appalachia has led to this region being called a hot spot for disease (Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2014; Laney et al., 2017). While the geographic clustering has been well documented (Pollock et al., 2010; Antao et al., 2005; Wade et al., 2011; Wang et al., 2013), the root cause is still unknown. Leading hypotheses have focused on the relative amount of rock being cut along with coal in many central Appalachian mines, as there has been a tendency to mine increasingly thinner coal seams over the past couple of decades (Laney et al., 2010; Schatzel, 2009). This shift has likely been accompanied by changes in specific dust exposure factors, such as increased abundance of particularly harmful dust constituents (e.g., silica or silicates) or increased frequency of harmful exposures (e.g., due to work in more risky environments) (Pollock et al., 2010; Blackley et al., 2016; Cohen et al., 2016; Douglas et al., 1986)."

Jan 5, 2018

By J. D. Miller

"It is now possible to use 3D X-ray tomography analysis for plant-site characterization of coarse particles at a sampling rate of about 3 kg/min for particles which range in size from 150 mm to 1 mm at a voxel resolution of about 150 microns. This is quite a significant advance in X-ray tomography technology and should be useful for plant-site coarse particle characterization (size, shape, composition, density, texture, grain exposure, mineral liberation) with a response time of minutes after receiving the sample. Applications in the mineral industries are discussed including the coal industry, aggregate industry, metal mining and the processing of industrial minerals. INTRODUCTION Plant-site characterization of coarse particles at coal preparation plants, crushed stone/aggregate plants, and mineral processing plants is needed to improve plant capacity, product quality, and/or process efficiency. Not much on-line coarse particle characterization is done at these plants. Some limited information regarding particle size is obtained on-line from reflected light images using systems such as the OPSA, Split, and WipFrag analyzers. Even laboratory analysis of coarse particles has been difficult because of the large amount of sample required to insure statistical significance of the results. During the past decades laboratory 3D characterization of particles from energy and mineral resources by X-ray tomography has been demonstrated and used to good advantage [1, 2]. 3D X-ray tomographic analysis had its origin in the medical services industry; it is used to provide internal images of the human body and now has also been developed for non-medical applications [3]. Figure 1 shows a schematic diagram for the cone-beam geometry micro-CT system. In our case X-rays from a microfocus X-ray generator are partially attenuated by the sample (a packed bed of particles) that is made to rotate in equal steps in a full circle about a single axis of the particle sample. At each rotational position, the surviving X-ray photons are detected by a planar two-dimensional array (image intensifier) large enough to contain the shadow of the specimen. These two dimensional projection images are collected using conventional video technology. The video signal for each projection is then converted to a two-dimensional digital array by an image processing system. Finally, a three-dimensional image is reconstructed from the collected set of projection images. With the availability of automated high speed X-ray tomography [4] it now seems possible to do plant-site particle characterization at a sampling rate of about 3 kg/min for particles which range in size from 150 mm to 1 mm at a voxel resolution of about 150 microns. This is quite a significant advance in X-ray tomography technology and should be useful for plant-site particle characterization (size, shape, composition, density, texture, grain exposure, mineral liberation) with a response time of minutes after receiving the sample. Applications in the mineral industries are discussed including the coal industry, aggregate industry, metal mining, and the processing of industrial minerals"

Jan 1, 2016

By R. V. Stewart

This chrysotile asbestos orebody is located near the northern tip of the Province of Quebec, Canada. It is some 1818 km (1130 mi) north of Montreal; 480 km (300 mi) north of the tree line and is situated within the zone of continuous permafrost. The open pit ore zone is approximately 0.4 km (1/4 mi) in length some 61 m (200 ft) in width and plunges at 25-30 below surface to a vertical depth of at least 610 m (2000 ft). The orebody was originally evaluated by programs of surface mapping, diamond drilling and bulk sampling. The fibre is semi-crude, possesses excellent strength, and good fibre length distribution.

Jan 1, 1978

By Richard M. Winar

In September of 1988, the United States Environmental Protection Agency (US EPA) published final regulations that effect owners and operators of underground storage tanks (USTs). These regulation include stringent technical requirements for owners and operators of USTs containing petroleum and certain hazardous substances. The technical requirements effect both new (those installed after December 1988) and existing USTs and include notification; performance and operating standards; release detection, reporting, investigation; release response and corrective action; and closure requirements for out-of-service USTs. The USEPA also published final regulations regarding financial responsibility requirements for owners or operators of petroleum USTs in October of 1988. These regulations require owners or operators of petroleum USTs to demonstrate financial responsibility for the costs of corrective action and compensating third parties for bodily injury or property damage caused by releases from petroleum USTs. Like thousands of other industries, the mining industry must become thoroughly familiar with these new regulations in order to properly manage their UST systems, ensure compliance, and understand other ramifications imposed by these regulations.

Jan 1, 1990

By D. S. Flett

Abstract. The commercial importance of hydroxyoximes as extractants for copper has given impetus to basic studies on the chemistry of metal extraction by these compounds. The discovery of accelerator compounds which produce catalytic effects on hydroxyoxime extraction rates has led to mechanistic studies of these rate processes. While these studies have highlighted the importance of interfacial chemical reactions in the extraction process, it is not yet possible to unambiguously describe the mechanisms of metal extraction in these systems or the associated catalytic effects. This paper reviews progress in understanding the mechanism of metal extraction by hydroxyoximes.

Jan 1, 1979

By C. S. Compton, T. E. Marshall, D. R. Dolinar, R. Grau, L. J. Prosser, A. T. Iannacchione, D. C. Oyler

Unrecognized roof beam failures resulted in 69% of the falls of ground injuries occurring in underground U.S. stone mines from 1990 to 1996. Field investigations at 45 underground stone mines suggest that excessive beam sag or deflection is the principal unstable roof behavior characteristics associated with miner injuries. Laminated roof structures, common in most underground stone mines, allow the immediate roof to separate into distinct beams. The timely determination of roof beam deflection could provide stone miners with advanced knowledge of potentially hazardous roof. Existing methods to assess roof conditions consist of observational and monitoring techniques. Observational techniques include open drillholes, sounding, wedging, and borescopes. Monitoring techniques include scratch tools, extensometers, telltales, Miners Helpers, and Guardian Angels1. Miners have difficulty utilizing these techniques because roof beams are located an average of 8 m(26.5 ft) above the miner’s head in environments that are dark, dusty and noisy and these deflections are measured in millimeters of movement. To help mitigate the potential for falls of ground injuries to underground stone miners, the National Institute for Occupational Safety and Health (NIOSH) has developed the Roof Monitoring Safety System (RMSS) to aid in monitoring dangerous levels of roof beam deflection. If enough site-specific information is collected and placed on highly visible maps, individual mining operations could establish general guidelines for responding to specific roofbeam deflection occurrences. This would help in implementing a pro-active, comprehensive roof control plan for reducing falls of ground injuries.

Jan 1, 1999

By P. B. Queneau

An operating problem encountered at the Moa Bay operation in Cuba, where nickeliferous laterite ore is processed by sulfuric acid pressure leaching, is the formation of alunite and hematite deposits on the autoclave walls. The AMPX Extractive Research & Development, Inc., metallurgical laboratory (Golden, Colorado) has made substantial improvements in the Moa Bay process in the areas of metal recovery, energy consumption, and feed versatility. One of the advantages of AMAX's process is its ability to treat substantial portions of nickel- and magnesium-rich serpentine while maintaining acid utilization efficiency. The process minimizes scale formation by combining staged acid addition with vigorous agitation and 270°C operation, but does not eliminate scaling. This paper describes how advantage can be taken of MgSO4?XH20 precipitation both to inhibit alunite scaling and to disperse hematite scale within the MgSO4?XH20 matrix. Cooling the autoclave from its 270°C operating temperature down to 180°C takes advantage of the reverse solubility of magnesium sulfate. The magnesium dissolves, liberating entrained hematite, thus providing a means for control of autoclave scale with minimum process disruption.

Jan 1, 1984

By Ben L. Seegmiller

How to obtain optimum slope angles for future open pit mines using the rock mechanics approach is the subject of this paper. In the past ten years significant developments in open pit rock mechanics have come about. This has been due to the mining industry's need for the steepest, yet safe, pit slope angles attainable. Requirements for economically achieving slope stability and the actual payoff that may be achieved through stability studies have been previously discussed', by stability engineers. While the emphasis has generally been placed on the concept of "stable slopes" in the past, it is suggested that emphasis now be placed on "optimum slopes" or "optimum slope angles". A definition of an optimum slope angle is one which (1) is as steep as possible and practical from orebody and mining constraint standpoints and yet, (2) maintains the accepted standard of safety defined by a safety factor against failure and/or a probability of failure. In other words, the emphasis is placed on achieving practical stability results as defined by safety and economic considerations, as opposed to simply achieving stability. The essential purposes of this paper are to (1) outline the need for optimum slope angles, (2) discuss the procedures for using the rock mechanics approach in slope angle design for a future open pit and (3) specify the end results that may be achieved by using such an approach. While the basic concepts and recommendations outlined in this paper may be equally applicable to soil as well as rock slopes, the emphasis and procedures have been directed at rock slope angle design.

Jan 1, 1976

By G. A. Kordosky

LIX® 34 liquid ion exchange reagent, one of a totally new class of metal extractants, is discussed in terms of its properties. Specifically, these properties include improved selectivity for copper and greater recovery. Some comparisons to the well known General Mills' LIX® 64N have been made. Particular emphasis is given to treating solutions containing very low copper values and high impurity levels.

Jan 1, 1976

By Brian H. Kaye

Efficient design of grinding circuits for efficient production of ultrafine material requires rapid feedback of information concerning the fineness of material leaving the grinding device. Generating this information requires efficient sampling and adequate rapid characterization of the material leaving the grinding machinery. Recent developments-in electrooptic inspection of dry end wet material leaving a grinding device are critically reviewed. New methods for characterizing ultrafines are discussed. A rapid operating automated cybernetic (intelligent) permeability device for automatic control of grinding circuits using Blaine index and other fineness indices is described.

Jan 1, 1983

By K. K. Kohli

Since the adoption of the Surface Mining Reclamation and Control Act of 1977, which mandates that surface subsidence be an intergral part of the underground coal mine design, there has been a sudden rise of demand on guidelines for minimizing surface subsidence and its associated structural damages. Unfortunately there is no sufficient amount of systematic subsidence data to fill such a gap, although considerable research has been devoted to the subsidence-induced damages of surface structures in the past. However, it was said that many surface subsidence surveys have been performed and monitored by coal companies during the past twenty years, and that it will be a great source of information for subsidence engineering design if they can be collected and assembled together. An effort was therefore initiated in the Department of Mining Engineering, West Virginia University, under contract with the U. S. Bureau of Mines in December 1978 to contact each individual coal company in the Northern Appalachian Coal Field for any surface subsidence survey data. After 10 months' survey, the data collected include 17 longwall panels and 2 room and pillar sections. The data in-each panel and section cover the complete set of subsidence survey raw data, underground mine layout maps, surface topo maps, geological loggings showing the stratigraphic sequences and thickness of the overburden, and if available, locations and types of surface structures. On-site visits were followed to study the surface terraines and structures. Interviews were conducted with the owners of the surface structures in most cases about, if any, the history and characteristics of damages.

Jan 1, 1980