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By Manchao He, Xiaoding Xu, Yubing Gao

Based on the geological conditions of the 15,600 working face in Pingba Mine, this paper establishes the mechanical model of the stress distribution in the pre-working face under the influence of mining pressure based on a hemispherical stress distribution theory. The analytical formula for the stress distribution is determined. A numerical model for the mining pressure under the influence of key layer is also constructed, and dynamic stress interruptions under various roof-cutting relief schemes in different horizontal positions are simulated. The stress distribution of the stope under different pressure relief schemes is analyzed and compared with the theoretical results. Results show that blasting roof cutting blocks the transmission of the abutment pressure to the working surface to the coal and rock mass in front of the working face, reducing the significant working face mining pressure influence range, which decreases as blasting pressure relief position moves toward the working face. Stress accumulation in the coal in front of the working face also increases as the blasting pressure relief position moves toward the working surface. Engineering practice results show that blasting cutting can effectively block the propagation of mining pressure, and the stress impact range is shortened by approximately 1/3.

Jul 31, 2021

By B. M. Eiter, J. Hrica, D. R. Willmer

"Mineworkers are routinely tasked with making critically important decisions about whether or not a hazard presents an imminent danger. Researchers from the National Institute for Occupational Safety and Health (NIOSH) collected formative data to investigate mine safety professional perspectives on workplace examinations, which revealed a potential gap in how mineworkers are assessing risk. During interviews, participants indicated having processes in place for what should be done once an imminent danger situation is identified. Critically, however, they report having no systematic methodology for mineworkers to use to determine if a hazard is considered imminent danger. While this is important for all imminent danger situations (e.g., failure to lockout/tagout), it is especially important for those situations that are not immediately recognizable as imminent danger. In this paper, we identify and describe, three distinct categories of imminent danger complexity and discuss potential steps that could lead to improved identification of imminent danger situations. Finally, we identify potential practices to incorporate into risk management efforts, including feedback, communication, and specialized training to increase awareness of imminent danger situations. INTRODUCTION In recent years, the metal and nonmetal (M/NM) mining sector, as categorized by MSHA, experienced an increase in the number of fatalities occurring at mine sites. From 2013 to 2015, 69 mineworkers were fatally injured; that is twice the number of fatalities that occurred in each of the previous two years (MSHA, 2015a). As a way to address this increase, the Mine Safety and Health Administration (MSHA) issued a program policy letter (P15-IV-01) suggesting that “miners would benefit from rigorous workplace examinations conducted by experienced and trained examiners (MSHA 2015b).” The goal of workplace examinations is to find hazards in the field and mitigate them before they cause injury or death to mineworkers. While it is important to identify all hazards in the workplace, it is critically important to identify those hazards that are considered imminent danger because they require an immediate response to avoid a severe or even fatal injury."

Jan 1, 2018

By R. G. Hite, R. G. Rowe

The Crandon deposit, located in northern Wisconsin, is a 65.8 million ton Precambrian volcanogenic massive sulfide deposit which averages 1.4% copper and 5.8% zinc. The deposit is classic in origin, mineralogy and shape. Comprehensive understanding of the geology of both the deposit and the project site has been fundamental to the credibility and success of project feasibility studies and regulatory permit preparation. Mine development in the current investment and regulatory climate requires thorough and timely application of geologic tools. From 1977-1980 geologic activities were focused on the typical objectives of orebody delineation, reserve estimation, depositional geology, and general site investigation. Results from these programs formed the basis for the project's preliminary feasibility studies. Since 1981 further geologic investigations have provided criteria for project design, site management, and operational permitting. Activities have included mine entry position definition drilling, devel reserve modeling, large diameter (150 mm) core drilling for mill pilot samples, rock mechanics testing, and evaluation of the glacial overburden/deposit geohydrology for computer simulation.

Jan 1, 1992

By R. J. Zagrocki

Rekindled public concern about lead toxicity has intensified the awareness of lead-bearing materials in contact with the environment and the human population. Lead's common association with other metals makes the increasingly restrictive lead standards a primary concern for a large number of metal and metal-related industries. In commercial scale demonstration tests with lead-bearing wastes, the HRD Flame Reactor process has a demonstrated ability to separate and recover over 95% of the lead as a recyclable oxide, while rendering the remainder of the material as vitrified, non-leaching, and nonhazardous co-product. Recent Flame Reactor process tests and preliminary cost data for secondary lead soda slag are highlighted.

Jan 1, 1992

By P. C. Miller

The paper reports laboratory results from the bioleaching of chalcopyrite ores and concentrates using a mixed moderate thermophile culture. Copper dissolution in excess of 95% was achieved in all cases with the majority of tests indicating copper dissolution in excess of 98%. Aspects of downstream processing are discussed in relation to iron rejection by precipitation. The laboratory results indicate the need for careful control of the pH value to prevent co-precipitation of the copper with iron. A comparison of capital and operating costs is given indicating potential differences between the use of toll smelting and bacterial leaching on site. A discussion is given highlighting the sensitive cost areas of these two process routes.

Jan 1, 1997

By P. Crouse, J. Obermeyer

"INTRODUCTION Site location and history The Holden Mine is a former underground copper mine that was developed and operated by the Howe Sound Mining Company (Howe Sound) from 1938 to 1957. The mine is located in north-central Washington State, U.S., near Lake Chelan in the area shown as Holden Village in Figure 1. Although Rio Tinto never owned or operated the mine, they are managing and funding a several hundred million dollar clean-up to prevent future water and soil contamination and to reclaim the former mine site under the United States Environmental Protection Agency (USEPA) Superfund process. The former mine included an onsite mill and a nearby housing complex for the miners. Howe Sound developed the mine as a series of near-horizontal drifts and tunnels, interspersed with stopes and shafts that connect different mine levels underground. The tunnels that were excavated to develop the mine total nearly 100 km in length.During development of the underground workings, Howe Sound removed more than 230,000 cubic meters (m3) of waste rock from the tunnels and deposited this material in two waste rock piles. Ore was processed from the mine in the onsite mill to produce a copper concentrate that was shipped off site for smelting. Roughly 10 million tonnes of tailings were produced as a by-product of the milling operation, most of which were deposited in three large impoundments (Tailings Piles 1, 2 and 3) directly south of and adjacent to Railroad Creek. Howe Sound closed the mine in 1957. In 1961, the property was transferred to Holden Village, Inc. (Holden Village), a not-for-profit corporation that maintains a year-round community and operates an interdenominational religious retreat in the former miners’ town. With the exception of the patented private land, the remainder of the Site is on National Forest lands and is administered by the U.S. Forest Service. The mine is remote. It is only accessible by boat or float plane from Chelan, Washington, up Lake Chelan to Lucerne, nearly 40 km. Vehicle access from Lucerne to the mine is provided through a 17.5-km-long winding gravel road that climbs 640 meters in elevation. The general site features are shown in Figure 2. Physical setting The Holden Mine is located on the eastern slopes of the Cascade Mountain Range at an elevation between 975 and 1,050 m above mean sea level. Holden Mine was developed adjacent to Railroad Creek, which lies in a glacial U-shaped valley carved into the igneous and metamorphic bedrock with steep-sided slopes (Figure 2)."

Jan 1, 2017

By Karan S. Keith, Haydn H. Murray

The sorptive and impervious nature of clay materials was recognized long before modem technology allowed us to understand the physiochemistry of clays. In Cyprus, around 5000 BC, sorbent clays were used for fulling woolen cloth. One of the earliest recorded uses of clays as an impervious liner was more than 3200 years ago in the construction of a bitumen-sand-gravel-clay liner built along the embankment of the Tigris River at Assur. Today one of the most common applications for clay minerals in the environmental industry is for use as impermeable barriers to fluid transport. Clay minerals are fine in particle size and thus have large surface areas, which, as a result of intermolecular forces and ionic substitutions, make them excellent materials for both ion exchange and ion sorption. Therefore it was logical to consider certain clay materials for applications in the environmental industry, where they can act as physical and chemical traps for potential contaminants. Certain bentonites have historically been used as sealants for fluids (Grim, 1962), and other clays have been used as sorbents for both water and oil (Haden, Jr., 1972). Prior to the 1980s, disposal of the nation's municipal, commercial, chemical, and nuclear wastes was largely indiscriminate and poorly regulated. This created environmental pollution problems, especially with respect to groundwater contamination. Promulgation of federal regulations like the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA - commonly known as Superfund) have forced a more careful and costly approach to waste disposal. The US Environmental Protection Agency (EPA) is the government body charged with enforcing and ensuring compliance with federal regulations governing toxic waste production, storage, and disposal. Widespread application of geotechnology to the design and construction of waste containment systems and to pollution remediation has become necessary due to such laws and because of increasing use of the subsurface environment for the disposal of hazardous wastes. In the United States nearly 1.8 kg of trash is disposed of per person per day, which amounts to nearly 181 Mt per year. This amount is more than double the waste produced in 1960, and these numbers are expected to continue to increase. Canada produces approximately 1.68 kg of waste per person per day. The EPA estimates that in the United States 64% of our garbage is landfilled, 18% recycled, and 18% incinerated. Even with continued increases in recycling and incineration efforts, the EPA projects that the United States will still need 82% of today's landfill capacity in the year 2000. Data on the exact number of landfills in the United States and Canada is conflicting in part because of changing definitions of what constitutes a landfill and because of inadequate record- keeping by some states and provinces. An estimate of the number of municipal solid waste (MSW) landfills in the United States in 1990 to 1991 ranged from 4 462 to 10 467 with an average estimate of 6 600. In Canada the number of MSW landfills reported varied from 5 493 in a 1982 survey to 1 766 reported in a 1991 National Solid Wastes Management Association (NSWMA) survey (Repa and Sheets, 1992b). A properly operated MSW landfill on average requires 1 hectare of land per year per 25 000 people (Coates, 198 1). In addition to MSW facilities, there are also waste disposal facilities needed for hazardous waste and low level and high level radioactive waste. In 1983, approximately 266 Mt of hazardous waste was generated in the United States, almost 50% of this by industrial production. About 68% of the hazardous waste generated in the United States and Canada and almost 50% generated in Europe are still landfilled (Egger, 1987). In 1985, approximately 51 000 m3 of commercially produced low level radioactive waste was disposed of in radioactive waste disposal sites across the United States (Jungling and Greeves, 1989). By 1987, the US defense program had produced approximately 10 000 t of high level nuclear waste. In addition, there were approximately 14 000 t of spent fuel assemblies from commercial nuclear power plants in temporary storage; the amount is expected to nearly triple by the year 2000. Presently most commercial spent fuel assemblies are stored in water-filled pools at nuclear power plants. Defense waste is stored on federal reservations in surface and underground steel tanks (Anon., 1987). Under federal law nearly all waste disposal and containment sites are required to have a liner or barrier and a cover system design that meets federal- or state-approved hydraulic conductivity requirements for the type of waste that the site will receive. When approved materials, necessary for constructing the waste containment structure, are not available on site, one of the most economical ways to meet these requirements is through the use of clay, soil/clay, or clay/geotextile materials. In a 1991 survey by NSWMA of its members and other select private sector facilities, 81% of the surveyed landfills had some type of liner system. About 75% of these liners were clay materials (either recompacted or natural). The remaining 30% were using flexible membrane liners as part of a liner system. Clay liner materials are most commonly used in the South, Midwest, West-central, and South-central regions of the United States. About 93% of the landfill facilities had closure plans, and of these 91 % were using clay materials in some way for the final cover material (Repa and Sheets, 1992a). Waste barriers and containment structures take several basic forms, and they are used in a variety of different applications: 1) cutoff walls, 2) soil or soil/clay-admix liners, 3) geosynthetic bentonite-clay/geotextile membranes, 4) radioactive waste containment barriers, and 5) synthetic geomembranes. This chapter will discuss the first four of these categories. The field of synthetic geomembranes, although a related topic, is beyond the scope of

Jan 1, 1994

By S. D. Thompson

Several discrete-event simulation models have been developed for designing the conveying system capacities of underground coal mines. Most of these models require the use of a step-function approach to mimic the loading process at each conveyor loading point. Over the years, practitioners have generally employed one of three versions of the step-function approach. An important issue is how these three versions compare to each other in terms of simulated capacity requirements for belt conveyors. Another is-sue is how they compare to peak capacity design. This paper addresses these issues by statistically and quantitatively comparing their simulation results. The consequences and problems associated with using each version are also discussed and summarized.

Jan 1, 1997

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 R. A. Matuszak

In recent years, a new concept in the control of electrically powered excavators has come into existence. The new type of control system has come to be known as "static" control. The use of the name "static" to describe this system is somewhat misleading since this term refers only to one of the many advantages of this very important advance in excavator control systems. In 1959, the first truly "static" control for Ward-Leonard equipped electric excavators was designed, developed and placed in service. The control system, originally intended only as a more modern electronic type of alternate to the tried and proven rotating amplifier control system then in use, has since proven to be much more.

Jan 1, 1964

By R. Mensah-Biney

The loading characteristics of gold-tetrabromide species onto activated carbon have been evaluated using a completely mixed batch reactor system. The overall loading of gold onto carbon was rapid for the first hour but continued slowly without cessation as a result of reduction of gold. Conventional equilibrium considerations were therefore not applicable. Although loading continued slowly after several days, abnormally high loading capacity values of 10-12 meq/g carbon (650-800 kgAu/tonne) could be attained within 72 hours. The loading of gold-bromo species by activated carbon was by the mass transfer of [AuBr4l-onto the carbon surface where reduction to metallic gold took place. Elution of gold from the loaded carbon was feasible provided the carbon had not been loaded to too high capacity values. If loading is carried to high levels, complete elution becomes impractical and the gold may be recovered by ashing the carbon. For the high loading capacities observed, this option would appear to be cost effective. The effect of several variables on the loading capacity of the activated carbon is discussed.

Jan 1, 1992

By Barry Hunsaker

I cannot help but be reminded, as I stand here today, of my boyhood years and heritage, both of which are inextricably tied to this very valley and are, in a: bay, apropos of the theme of this Keynote Session. I remember the scarcity of people. For example, 48, 000 in Phoenix and 436, 000 in the State in 1930 and 65,000 in Phoenix and 499, 000 in the State in 1940. Today Phoenix boasts a population of over 500, 000 and the State a population of 1, 500,000. I remember the' lack of facilities, goods and services, including gas and electric power. I recall stories of my grandfather who had the freighting or teaming contract to haul all the supplies and generating equipment, by wagon mind you, up the old Apache Trail to Roosevelt Dam. . .a three day trip from the nearest railhead which, by the way, was not Phoenix, for it did not merit a railhead on those days, but the village of Maricopa approximately 25 miles south of Phoenix. I remember chopping firewood, heating wash water on an open fire in a No. 3 wash tub at the rear of the house and doing my school homework by the light of a kerosene lamp just 25 to 35 years ago within what is now a large metropolitan area

Jan 1, 1965

By R. R. Sacrison

The Barrick Mercur Gold Mine lies in the Oquirrh Mountains of northern Utah. Limestone, sandstone, shale, and chert are the predominant rock types being mined. Recent expansion has encountered rhyolite. Lithology and structural attitudes control most mechanical behavior. Slope steepening, mine planning, and site selection are presented as means by which geological engineering has contributed to the economics of the operation. Geomechanics investments of approximately $700,000 have resulted in cost savings or additional production worth over $16,000,000.

Jan 1, 1990

By T. Good

Twin roll sizers are neither compactly designed machines nor are they configured to accommodate underground mobility; in fact, twin roll sizers leave room for improvement in many aspects of the design. The DRC1200 capitalizes on the weaknesses of these machines to make a more productive, easily maintained, and compact twin roll sizer than current market offerings. These strides were made through the inception of the Hard Rock Extraction System (HRXS), which requires a mobile sizer as part of the system. After use of a third party sizer on the HRXS, potential improvements were evident. These improvements include improved structural design to reduce overall footprint and an optimized design to reduce operating cost.

Feb 23, 2014

By J. M. Dean

The MANpower SUPport Program (MANSUPP), a part of the Mine Management Support System (MMSS), allows an underground coal mine site user to determine manpower requirements for production support work by considering ongoing operations and current mine conditions. The objective of MANSUPP is to plan a detailed manpower structure for a mine by incorporating a production schedule, condition-modified work standards and management preferences to predict required manhours for various activities, for example, belt moves. The program is written in Quattro Pro version 3.0 (Lotus 1-2-3 compatible) utilizing the command language, macro and formula capabilities.

Jan 1, 1992

By Éder Domingos Oliveira, Carlos Antonio Morais, Ruberlan Gomes Silva

The objective of this study is to assess the impact of different reagents, such as limestone, lime, magnesium oxide, and sodium hydroxide, in experiments carried out in the single purification step and in two consecutive purification steps by raising the pH of a rare earth sulfuric liquor with the aim to remove or reduce the impurity concentrations in the rare earth sulfuric liquor. The choice for the best purification condition was made based on the minimum loss of rare earth elements (REEs), reagent consumption, and residue generation. The exploratory experiments show that it takes place in the two consecutive purification steps, the first one consists in dosing the limestone pulp until it reaches a pH of 3.5 followed by an addition of a lime pulp reaching a pH of 5.0. Under this condition, the results were a total removal of Fe3+, PO4 3− , and Th4+ ions and a reduction of 99%, 87%, and 37% w/w in the Al3+, UO2 2+, and SO4 2− concentrations, respectively, in the purified rare earth liquor. Furthermore, the lowest REE losses (8.3% w/w) and reagent consumption (4.3 kg/m3 ) and also a low residue generation (7.5 kg/m3 ) were observed in this condition. Despite reaching similar results regarding impurity removal, the experiments done with the addition of limestone, lime, magnesium oxide pulps, and sodium hydroxide solution in the single purification step, where the pH was raised to 5.0, presented higher REE losses (64.9%, 42.5%, 44.8%, and 60.9% w/w, respectively) and a higher residue generation (43.2, 25.1, 11.1, and 13.6 kg/m3 , respectively). This occurred due to the co-precipitation of salts containing rare earth elements in their composition. The experiments conducted with limestone, lime, and MgO resulted in a higher consumption of reagents, while the same result was observed when NaOH was used (4.3 kg/m3 ). In the experiments carried out with the addition of magnesium oxide and sodium hydroxide, the respective purified rare earth liquors presented a high concentration of magnesium, sulfate, or sodium, which could impact the quality of the marketable rare earth salts, whereas the salts obtained under the best condition observed in this study seem to be amenable for use as raw material in an attempt to obtain rare earth products with an acceptable chemical quality.

By David P. Kimball, Dalva L. Moellenberg

On May 21, 1990, EPA released its Strawman II draft program for mining wastes. It proposes to expand RCRA regulation of mining operations to include materials other than wastes. Strawman I1 would establish strict standards for the states to follow, rather than technical guidance. It proposes to establish performance standards; design criteria; monitoring requirements; and corrective action, closure, post-closure, and financial assurance requirements. It suggests "pollution prevention" concepts for mining operations. This paper explores the Strawman II proposals, particularly the technical criteria, and addresses several of the important concerns raised by industry.

Jan 1, 1991

By Ralph C. Kirby

The U.S. produces about 34 percent of the world's aluminum yet must import 90 percent of the raw materials needed. There are abundant resources of aluminum-bearing minerals such as clay, anorthosite, alunite, shale, and dawsonite, but none of the numerous processes proposed for recovering alumina from them has yet proved economically competitive with the Bayer process using imported bauxite. To help develop an economically viable process for utilizing these resources, the Bureau of Mines is testing on a common basis several proudsing processing techniques. New improvements and approaches developed by industry and the Government are being evaluated on a mall scale to obtain enough information on which to form a judgment regarding the best processes for commercial adoption. A continuous miniplant having a feed rate of about 70 pounds per hour is being operated now to investigate the nitric acid process for recovering alumina from clay. Parts of this plant will be used subsequently for work on other processes for recovering alumina from clay, anorthosite, alunite, and dawsonite. Initial results of the operation and plans for the overall project will be discussed.

Jan 1, 1974

By F. A. Renninger

The terms environment and environmental control, when used in today's context, generally imply to the average individual, something to do with pollution and pollution control. These latter terms, likewise, impart visions of fouled air and dirty water attributable largely to the industrial segment of American society. We have been conditioned, by various means, over the past ten years to equate environ¬mental control with pollution control. We have been trained to think of industrial environmental control programs as efforts conceived only to comply with one or more of the recently imposed pollution control regulations. Almost automatically we; approach consideration of environmental control with a degree of pessimism that is we assume that pollution prompted the control program. It is the purpose of this discussion to demonstrate that environmental control. at least as it exists and has existed within the crushed stone industry, involves far more than simply control or reduction of air and water pollution. It involves a dedication to the enhancement of each of the several "mini-environments" which together comprise the total world surrounding any given crushed stone operation. Environmental control, exercised properly, is an optimistic, constructive, forward-looking, enhancing type of activity. It is a function which has been, and should continue to be, willingly and expectantly undertaken by informed management personnel. In short, environmental control. is an activity from which both industry and society can and should benefit.

Jan 1, 1972

By William F. Riggs

Inspiration Consolidated Copper Company, located in a semi-arid climate in Arizona, continually struggles with a water problem. This applies to quality as well as quantity. When the EPA considered installing a new centralized sewage plant to handle the combined waste from the municipalities of Globe and Miami, Arizona, they automatically assumed that He could use the sewage effluent for process water in flotation. The treatment plant was to be a tertiary system producing 1600 gpm of sewage effluent. Inspiration decided that this could possibly be a source of additional process water. It was decided to test sewage effluent from Miami Treatment Plant at the rate of 400 gpm since it was only a primary treatment plant. The 400 gpm was combined with the 5000 gpm of process water going to the Concentrator. After one week the results were disastrous. The recovery and final grade had each dropped approximately 5%. With the results from this brief run, it was concluded that sewage effluent from a primary treatment plant could not be used. Research was then brought into the problem to begin an evaluation of sewage effluent in flotation.

Jan 1, 1977