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By Wilson Blake

The occurrence of rock bursts in some deep mines throughout the world constitutes a severe operational hazard. In addition to endangering the safety of the miners, the rock-burst problem is a major factor in mining economically in deep mines because of the loss of production and expense owing to cleanup and repairs following a burst. Developing means of controlling or eliminating rock bursts has been the subject of intensive research for over 50 years. While much has been learned about the effects of rock bursts, little is known about their basic causes; hence, control measures have been at best only partially effective--attested to by the number and severity of bursts that continue to occur throughout the world each year. In the Coeur d'Alene mining district of north Idaho, the rock-burst problem continues as the silver and lead veins persist at depth. These veins are presently being mined at greater than 7,000 feet below the surface and will be mined to some 10,000 feet in the future. The majority of rock bursts in this district occur in pillars. While pillar bursting has been essentially eliminated in some deep-mining districts by longwall techniques, modification or application of this technique to the thin, irregular, and near vertically dipping veins of the Coeur d'Alene district has not been found to be practical. The creation of pillars is a consequence of the horizontal cut and fill mining method used. Figure 1 shows a vertical longitudinal projection of the silver vein at the Galena mine, illustrating the mining method. Stoping progresses between raises and is carried upward between levels. A horizontal pillar is created as a stope approaches a mined-out level. Recent broad-band micro seismic monitoring of rock-burst-prone stopes by the Bureau of Mines has shown that potential burst zones could be delineated weeks in advance of a burst and that a definite sequence of events took place prior to the occurrence of a pillar burst (1). Hence, time was available for control measures to be effected when a stope pillar reached a critical burst geometry.

Jan 1, 1971

By P. Verhoeven, G. Hefter, P. M. May

The dissociation (ionisation) constant of hydrogen cyanide, pKa(HCN), has been measured by high precision glass electrode potentiometric titrations in saline solutions containing up to 5 mol/L sodium chloride. The dissociation constant of water that is necessary for the calculation of pKa(HCN) has also been measured. In saline solution, and in contrast to literature values, pKa(HCN) changes considerably at both high and low ionic strengths as a result of changes in activity coefficients. In addition an equation is presented, using literature data, that describes the variation of pKa(HCN) with temperature up to 150°C. The significance of the changes in pKa(HCN) for optimising the pH of alkaline cyanide gold recovery streams is briefly discussed.

Jan 1, 1991

By Mustafa Yalçin, Ali Ihsan Arol

Coconut shells are the most widely used raw material for the production of activated carbon used in the gold production by cynanide leaching. There have been efforts to find alternatives to coconut shells. Shells and stones of certain fruits, have been tested. Although promising results to some extent were obtained, coconut shells remain the main source of activated carbon. Türkiye has become a country of interest in terms of gold deposits of epithermal origin. Four deposits have already been discovered and, mining and milling operations are expected to start in the near future. Explorations are underway in many other areas of high expectations. Türkiye is also rich in fruits which can be a valuable source of raw material for activated carbon production. In this study, hazelnut shells, peach and apricot stones, abundantly available locally, have been tested to determine whether they are suitable for the gold metalurgy. Parameters of carbonization and activation have been optimized. Gold loading capacity and adsorption kinetics have been studied.

Jan 1, 1995

By Daniel Maine

Swelling clay soils have been problematic to many types of infrastructure in the United States. However, their impact on underground construction is often misunderstood. The use of swell pressures in design of initial tunnel and shaft support lacks proper guidance and is often mis-interpreted. This paper provides insight and guidance on how to implement a geotechnical investigation program to determine if swelling soil exists at a site and how it impacts the design of temporary support systems for underground projects. An example is provided for how swell pressures were incorporated into the design of an initial support system for a rib and lagging tunnel system and problems that occurred.

Jun 23, 2024

By R. C. Woodhead

During past years the most difficult problem presented to the coal preparation engineer has been the cleaning of fine coal, The problem of handling fine coals is more involved than the coarser sizes, because the higher surface moisture contents complicate screening, and the larger percentages of fine near size material complicate separating problems. Low gravity high capacity specific gravity separations were not possible with equipment available at that time. Coal preparation engineers did develop machines that would effect a separation of the fines, however, to maintain a high efficiency, the point of separation had to be a relatively easy one. The more difficult separations were made in the coarse coal sections of the washeries, and the fines were generally cleaned at higher specific gravities in equipment such as tables, feldspar jigs, rheolaveurs, etc. Clean products from both processes were mixed, resulting in overall lower ash contents, During the last several years, however, we have been confronted with increasing demands ZGP more precise separations of finer coals to still further reduce ash contents. A study was begun and a program instigated to improve the cleaning of fine coal, The result of this endeavor was the development of the new cycloidal heavy medium cyclone.

Jan 1, 1964

By J. Seiter

Mining has always been among the most hazardous of occupations, and with the increasing demand for coal and minerals, safety in mines assumes even greater importance. Worldwide, underground miners are being exposed to noise and respirable dust hazards associated with roof bolt drilling. These hazards are now being understood to cause irreparable damage to the health of miners. The objective of this research was to discover if a Polycrystalline Diamond Cutter (PDC) drill bit generates less respirable dust and hazardous noise than a competing Tungsten Carbide (WC) bit, in dry vacuum drilling. In order to control the drill parameters the drilling tests have been conducted in a laboratory setting. The results were met by determining the quantities of dust and noise generated using each drill bit and analyzing those levels by using monitoring devices and software to collect the data. This paper includes information on experiment setup, equipment used, drilling parameters, and data collected. The test results suggest that there are noticeable trends that the PDC bits produce less dust than WC bits but more testing is needed to substantiate these trends.

Feb 23, 2014

By Michael J. Martinson

A powerful methane explosion in the mid-shaft pump station of a main service and ventilation shaft killed several persons on the station; more workers were killed when a mancage travelling down the shaft fell to the shaft bottom under a pile of broken concrete slabs from a brattice wall destroyed by the explosion venting into the shaft and a tangled mass of twisted steelwork from the equipped compartment. The newly-commissioned shaft serves a recent extension of an established mine on the Orange Free State (OFS) goldfield in South Africa. After outlining the circumstances in which the paper was written, and reviewing the nature and extent of the methane hazard in OFS mines, the paper describes the physical layout of the shaft and summarises evidence given by witnesses at the official inquiry concerning events prior to the explosion. No attempt is made to apportion blame for the incident.

Jan 1, 1989

By L. Sandbak

"CURRENT BASIS OF GROUND SUPPORT DESIGN ANALYSIS The current strategy used in determining what kinds of support are needed is based on empirical design charts (Grimstad and Barton, 1993). Figure 1 is an example of the topcut analysis used for a 14 foot wide (4.3 meter) drift, which is the current design width used for topcuts at TRJV mine. The majority of our topcuts are situated in ore of the Type IV and Type III weak rock class categories that necessitate the use of bolts, mesh and 2”-4” of shotcrete. This type of empirical chart gives excellent guidelines for the kinds of support, and it is based on case histories of civil tunneling and mining properties. It is a good starting point for determining the kinds of support needed, but not to the detail needed to optimize the number of bolts, type of mesh, or combination of types or strengths of shotcrete. This report is an attempt to help quantify the safety factor and optimum design parameters to include mesh and shotcrete as part of the design criteria and subsequent safety factor.SAFETY FACTOR ANALYSIS: BOLTS ONLY One type of safety factor analysis used at TRJV for the past 7 years is described as the “dead weight” method, developed by Pakalnis (2008). It involves the support of a conservative “dead weight” of rock held in place by bolts in which the depth of failure is approximated as a wedge whose height is one-half of the span. The failure or dead weight wedge resembles a triangular wedge that must be supported by the remainder of the bolts going through the wedge (see Figure 2).The support capacity of the system is determined by the bond strength of the bolts holding up the wedge, which is in turn based on the RMR. The method assumes the total support capacity is the sum of the individual bolt values defined by either the breaking strength or the bond strength of the bolts (whichever is lower) passing through the failure surface."

Jan 1, 2017

By W. M. Lewis

Product losses to tailings ponds have long been a source of frustration for the mining and utilities industries. The utilization -of the Lewis Econosizer to recover lost products has proven to be very cost effective through reduced acreage requirements, cleaning costs and increased production. The unit is successfully operating in coal, aggregates, industrial minerals, clay, fly ash, heavy minerals and many other ores. Utilizing an upward flow of slurry in a free settling environment, particles stratify within the unit according to settling velocities and are removed as sized products. Ultra fines or clarified water is removed off the top of the unit. The Econosizer requires no power and only minimal maintenance.

Jan 1, 1998

By John E. Kinnison

The Mission mine, located in southern Arizona near Tucson, is a recently developed open pit which produces 15,000 tons per day of copper ore. The mine lies on a wide and gently sloping bajada sweeping northeasterly from the Sierrita mountains. It derives its name from the nearby Mission San Xavier del Bac, built circa 1700. The ore body is everywhere covered by about 200 feet of alluvium, as are the adjacent Pima and Palo Verde mines. The geology of the Mission deposit is known principally through the study of diamond drill holes spaced 150 to 300 feet apart. The open pit is in an infant stage and has not yet revealed much of the deposit, although information obtained there by the operating staff, and from a few thousand feet of exploratory underground workings, has added significantly to the general fund of knowledge. Permission to publish was granted by the American Smelting and Refining Company. I am indebted to Kenyon Richard and J. H. Courtright for criticism of this paper and for their direction during the several years in which I studied the Mission deposit. Acknowledgment is given to consultant in petrography, Robert L. DuBois of the University of Arizona. The only previous publication pertaining directly to the geology of file Mission deposit appeared in 1959 (Richard and Courtright), and may not be everywhere readily available. Cooper (1960) has published a short paper on the district

Jan 1, 1963

By J. Leonard Frame

A coal-fired fluidized bed combustion (FBC) system will be installed at the Owatonna Tool Company, Owatonna, Minnesota. Two FBC combustors will burn solid fuels: coal, petroleum coke, and wood and paper wastes. Crushed dolomitic limestone will be used to control sulfur emissions to EPA limits. The combustors will supply indirectly heated hot air and hot water for paint drying operations, washing processes, and space heating. The program is sponsored by the United States Department of Energy and the Owatonna Tool Company, and is one of five programs designed to demonstrate industrial applications of coal-fired fluidized bed equipment. The paper will describe the combustion system and the results of development tests with dolomitic limestone for sulfur emission control.

Jan 1, 1978

By Kenneth R. Hancock

The importance of "Mineral Pigments" can best be shown by noting that the world production is estimated to be in excess of 47 billion kilograms (52 million st). This quantity if pack- aged in the common 22.6 Kg (50 Lb.) bag and placed end to end would circle the world over 500 times. This world production figure is based on a broad concept that pigments, extenders, and fillers have essentially similar functions. In this paper mineral pigments are products produced synthetically or from selected minerals and through pulverization have characteristics of pigments.

Jan 1, 1985

By S. Dixon

The use of warm (40-50°C) solution for the selective elution (pre-strip) of copper cyanide from gold and silver cyanides adsorbed on activated carbon was found to elute +90% of the adsorbed copper compared to the use of ambient (20°C) solution eluting 50-70% of the adsorbed copper. The warm solution pre-strip elution did have higher co-elution of gold (1-4%) and silver (10-18%) with the copper. The use of ambient solution pre-strip elution co-eluted less gold (0.2%) and silver (2%).

Mar 2, 2022

By Jozef S. Stachulak, Bruce R. Conard

INTRODUCTION The concern of occupational exposure to diesel exhaust pollutants is an important workplace issue for the mining industry. During the last three decades of diesel operations at Inco, a significant amount of research and improvement has been made in the area of work environment, and effective diesel operation. This paper will review the experience gained by Inco's Ontario Division from the implementation and the use of modern engines, improved fuel quality, and the exhaust control technology, coupled with adherence to proper maintenance and ventilation design and practices. Past monitoring practices and the current occupational monitoring program at lnco are outlined. A major new research initiative involving multi-stake holders in diesel performance is described. MINING IN THE SUDBURY AREA The discovery of nickel-copper ore in the Sudbury area dates back to the year 1856. The existence of this orebody was noticed when a strong compass deflection was observed by a provincial surveyor. This discovery, even though documented in official re- ports, failed to arouse any public attention at that time. In 1884, a rock-cut was blasted through a small hill near the village of Sudbury to permit laying track for the Canadian Pacific Railway (Boldt 1967). The rock-cut uncovered a body of massive sulfides with a copper content of over nine percent. The mineralization is concentrated along the outer margin of the Sudbury Basin, an oval-shaped structure having a dimension of 55 x 95 kilometres. The ore extends down-dip to to at least 3000 metres below the surface. The mining methods at lnco can be divided into two categories: "filled-stope" and 'bulk" mining. This division, in the broad sense, may also reflect the environmental conditions of the mine. In the past, the selection of a mining method was based on the size, shape, grade and the strength of the ore and its surroundings. The recent development of improved technology and mining equipment permitted wider application of low cost bulk mining methods. UNDERGROUND DIESEL EQUIPMENT The first diesel-powered machine, a 145-horsepower scooptram, was put into operation in March 1966, in a cut-and-fill stoping complex at Frood Mine. The number of diesel machines underground in the Inco, Ontario Division, mines was increased to 360 units by 1971,550 in 1977 (Rutherford 1978), and over 830 diesel-powered units in 1995. The following list indicates current mobile diesel equipment. LHD 194 Loaders 81 Trucks 28 Jumbo Drills 78 Personnel Carrier 101 Service Equipment 155 Locomotives 50 Bolters 30 Scissor Lift 113 About 20 percent of the LHD and truck units are equipped with electronic fuel controlled engines. COMPOSITION OF DIESEL EXHAUST Diesel exhaust contains hundreds of pollutants (Watts 19921, including components of unburned fuel and lubricating oil and products of incomplete combustion of the fuel and oil. These pollutants are emitted either as gases or as particles. Gaseous pollutants include carbon monoxide, nitrogen oxides, and sulfur ox- ides, as well as a variety of organic compounds, such as hydro- carbons, aldehydes, and polynuclear aromatic hydrocarbons. The particle phase, also known as diesel particulate matter (DPM), is the filterable portion of diesel exhaust. Figure 1 depicts the trimodal particle size distribution that arises from different mechanisms of aerosol generation (Cantrell and Rubow 1992). Primary combustion aerosols, including diesel exhaust aerosol, are formed as very small particles (in the 0.001 to 0.08 micrometre range), but physical mechanisms such as condensation and coagulation quickly transfer the aerosol mass from the nuclei mode to the accumulation mode. These processes result in a mass median diameter of approximately 0.2 micrometres for diesel particulate matter, and 90% of the particles are less than 1.0 micrometre in size. These particles have a high surface area, permitting the adsorption of different substances produced during combustion. Mechanically generated aerosols, on the other hand, typically contain particles greater than 1 micrometre in diameter. The particle phases of diesel exhaust contain three components (Bagley, et al, 1996) shown by Figure 2, namely: a carbon- aceous fraction composed mainly of solid-carbon particles, a sulfate fraction containing small hydrated sulfate particles, and a soluble fraction that contains compounds that are soluble in organic solvents and are adsorbed or condensed onto carbon core particles. These compounds consist primarily of higher molecular weight hydrocarbons and PAH's and may contribute 15% to 45% of the weight of the total particulate matter (Schuetzle, 1983). The control of these pollutants is necessary to ensure a healthy work environment. Proper engine maintenance, engine design modifications, improved fuel quality, and use of exhaust control technology, coupled with good ventilation practices, all

Jan 1, 1997

By I. Meliadis

This study presents the methodology and proposals for the restoration of an abandoned quarry in the Greek island of Milos. The local data (soil, vegetation etc.) of the island were collected, analysed and compiled into thematic maps using Geographical Information Systems. The restoration plan was based on the G.I.S. database and suggested the revegetation of the disturbed lands with herbaceous (grasses and legumes) or woody (shrubs and trees) plants. Plants should be indigenous or from other areas with the same vegetation type. Herbaceous plants establish and grow easily protecting the soil from surface erosion. The revegetation success depends on the seed quality, planting season and methods as well as local environmental conditions. Our proposals aim to restore the abandoned quarry with methods that follow the natural succession of vegetation, have minimal environmental impact, low cost and the expected result will be similar to the surrounding undisturbed land.

Jan 1, 2002

By C. McKinnon

Climate change is the central challenge facing the mining industry, wherein producers must simultaneously ramp up production to provide the raw materials for clean technologies while transitioning to carbon neutrality. While transitioning to renewables will take time, mines can start improving energy efficiency while improving productivity today. This paper proposes a novel technology ecosystem that can help. By monitoring mine shovels, loaders, haul truck paths, and conveyor belts, the proposed technology enables particle size measurements throughout the operation, truck and belt volume monitoring, ground engaging tools monitoring, and boulder detection.

Mar 2, 2022

By C. Menidiatis

The first cement plant of TITAN Cement Co was founded in Elefsis in 1902. It was the first cement industrial facility to operate in the Balkans and in the Eastern Mediterranean region. Currently have four cement plants in Greece producing 5.4 million tons per annum, and 25 ready-mixed concrete sites producing 1.4 million m3 annually. It has a total of 20 quarries, 14 of which are producing materials used in the making of cement while the remaining six produce aggregates used in the production of ready-mixed concrete. All plants in Greece are accredited for ISO 14001. The restoration of quarries began in 1976 at the company?s limestone quarry of the Patras plant, and was soon extended to all quarries. At that time, a department responsible for all environmental issues was established. To date, over 700.000 shrubs and trees have been planted and maintained at quarries, plants and ready-mixed concrete facilities, while over 100,000 trees have been donated to municipalities, communities, customers and to the Greek state.

Jan 1, 2002

By Hung-Kei H. Lam

Rubidium and cesium were discovered by Bunsen and Kirchhoff about 100 years ago. These two elements are by no means as abundant as sodium or potassium. Their occurrence in minerals is widespread, but usually as minor constituents. There is no known specific ore containing rubidium, but rubidium is found replacing the. other alkali metals in .some minerals.. Perhaps the highest concentration of rubidium found in one mineral is in lepidolite, KLi(OH,F)2A12Si3010, which contains from 0 to 3.5%*Rb20. 0n the average, lepidolite contains about 0.5% Rb20. Other sources of rubidium are carnallite, KMgCl3?6H20; pollucite, H20.2Cs20.2AI203.9SiO2; rhodizite, R20.2A1203-3B203; biotite, H2K(Mg,Fe)3A1(Si04)3; sea water, rivers, marine and fresh water organisms, soils, and plants. Cesium, even though it is the least abundant. of the stable alkalies, has a specific ore. Pollucites a hydrous cesium aluminum silicate, may con¬tain as high as 42.5% Cs20, although again, the average Cs20 content is about 25% among the handful of known deposits. Other cesium-containing minerals are lepidolite and carnallite. Rubidium and cesium are very much like potassium in chemical properties, consequently, they are hard to separate. Because of the difficulty in obtaining pure cesium and rubidium compounds coupled with the scarcity-of supply, prices were high and the two elements enjoyed little industrial use. Just before the Second World War, the world. supply of rubidium and cesium, from Germany, was a matter of tens of kilograms per year and prices were about

Jan 1, 1959

By J. A. Holtkamp

Environmental regulation in Mexico has matured dramatically and effectively in the last decade. The gap between environmental regulation in the United States and Mexico is rapidly narrowing, so much so that it is no longer necessarily less burdensome to operate in Mexico from a regulatory perspective. This paper is intended to give a general overview of the system of environmental regulation in Mexico. The actual application of Mexican laws and regulations governing the environment to a specific operation will require a much more detailed review of the applicable environmental standards.

Jan 1, 1994

By James A. Nunn

Location Xiaolangdi is located in the Henan province of the People’s Republic of China. The distance between Xiaolangdi and the capital of Henan, Zhengzhou, is about200 km. Xiaolangdi is located on the Yellow River at the end of its big characteristic knee. It can be easily found on the map by locating Luoyang. The closest big city to Xiaolangdi is Luoyang (about 45 km). This city has about1 million inhabitants and is well known also to foreigners for its famous historical past. It has been the capital of China through 10 dynasties in former times. Overview The Xiaolangdi Multipurpose Dam Project is located at the last gorge of the middle reach of the Yellow River. The main purposes of the project are: -flood control, - ice jam control, - sediment control, - irrigation, - water supply, - hydroelectric power generation. The project consists of many structures, these are 10 intake towers, 9 flood &sediment tunnels, 6 power tunnels, 1 underground powerhouse, and 1 zone dearth and rockfill dam with a sloping impervious core, 154m high, with a crest length of 1317m. The powerhouse mainly features 6 turbine and generator units of 300 MW, totalling installed capacity of 1800 MW and annual energy output of5.1 GWH. The total storage capacity of the reservoir is 12.65 billion m³ of which 5.1billion m³ is live storage. Of the Yellow River drainage basin, 694,000 km2 or 92,3percent is located upstream of Xiaolangdi Dam Site. Xiaolangdi is located in a key position for flood and sediment control of the Yellow River. Upon completion, Xiaolangdi Dam and Reservoir will effectively mitigate catastrophic floods, the control level will be increased from the present less than 100-year return period up to 10,000 years. Also, it will reduce severe flooding of the river bed of the lower

Jan 1, 1999