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China's coal energy development, characteristics and relationships with atmospheric pollution are reported. Atmospheric pollution sources from coal combustion are analyzed. Some of the projects for clean coal combustion in the Shanghai area include use of industrial briquettes, investigation of coal combustion additives, and blending combustion of coal with industrial wastes. Coal is China's main energy source, and 80 percent of China's annual coal production is used in combustion devices. Coal-flue gases from the domestic stoves and industrial furnaces are the main atmospheric pollution source. China's atmospheric pollution is, in fact, the pollution of coal-flue gases. To 2000, in view of China's energy needs as a developing nation, the atmospheric pollution from coal combustion must receive our utmost attention.

Jan 1, 1994

By James J. Meadows, Jason D. Pampena, Emanuele G. Cauda, Lauren G. Chubb

Exposure to respirable crystalline silica (RCS) can cause serious and irreparable negative health effects, including silicosis and lung cancer. Workers in coal mines have the potential of being exposed to RCS found in dust generated by various mining processes. The silica content of respirable dust in one single mine can vary substantially over both time and location. The current monitoring approach for RCS relies on the use of traditional air sampling followed by laboratory analysis. Results generated using this approach are generally not available for several days to several weeks after sampling, and this delay prevents timely and effective intervention if needed. An alternate analytical method is needed to reduce the time required to quantify the RCS exposure of mine workers. The National Institute for Occupational Safety and Health (NIOSH) has developed a new method using commercially available portable infrared spectrometers for measuring RCS at the end of the sampling shift. This paper will describe the application of the new field-based RCS analytical process for coal mines, including the use of the new method with the existing Coal Mine Dust Personal Sampler Unit. In a case study conducted by NIOSH with a coal mine operator in West Virginia, field-based RCS analysis was completed at a mine site to evaluate the new technique. The RCS analysis results obtained by the field-based method in this case study showed sufficiently strong correlation with results obtained by the MSHA standard laboratory analysis method to allow the mine operator to use the field-based method for evaluating process improvements.

By K. W. Harris, K. A. Perry

Reserve depletion in Central Appalachia is continuously creating unique ground conditions for underground coal mines with many of these difficult environments directly attributable to multiple seam mining and/or deeper overburdens. While many empirical studies have been performed in an effort to improve understanding of these problems along with potentially improving safety and extraction, many of the difficulties encountered lie outside of the normal realm of expected behavior. This is often the case when mining in bump prone ground, where additional concerns are introduced and design buffers are warranted. The boundary element software LaModel was used to study three bump events in a deep-cover, multiple-seam reserve located in Harlan county in the Kentucky region of Central Appalachia. This region is notoriously bump prone due to significant areas of deep cover, the presence of strong to massive lithology (such as sandstone), and an extensive history of underground mining that increases the probability of multiple seam interactions. Multiple seam interactions are best understood with respect to site-specific parameters, including both the geological and geometrical components of interburden, overburden and mine workings. Initially, empirical-based approaches (ARMPS/AMSS) were used when attempting to back-analyze the bump events. However, it was recognized that a more detailed investigation was necessary to understand the fundamental causes/conditions associated with the bump events. Consequently, the LaModel study resulted in a mine-specific calibration method for the reserve. With this method in place, enhanced bump prediction throughout the reserve is expected, such that the stability, recovery and safety of future mining may be improved.

Jan 1, 2014

By J. R. R. Bowling, A. McFadden, M. Francoeur

The abstract discusses the increasing use of extensive duct-fan systems in underground hard-rock mine development. It highlights the challenges of designing these systems, particularly the risk of partial vacuum and the need for careful booster fan positioning. The paper explores factors influencing the design of these systems, including component limitations, operational wear margins, and power constraints. It also defines the concept of partial vacuum and its impact on ventilation ducts. The authors propose an algorithmic approach for specifying the location and blade pitch of in-line booster fans to prevent system failure.

Mar 17, 2022

By James Corcoran, Richard McLane, Joseph DeMello, Eric Carlson, Hans van de Vrugt

The Los Angeles County Transportation Authority’s Purple Line Extension Phase 1 is a $3.12 billion (USD) design-build, underground heavy rail project, connecting an existing station at Wilshire Boulevard and Western Avenue and extending west 3.92 miles under Wilshire Boulevard and terminating approximately 550 feet west of Wilshire/La Cienega Station. The project alignment runs through the heart of the world famous La Brea Tar Pits and one of the world’s largest urban oil elds. This paper presents a case history of the planning, design, and construction efforts to achieve successful construction of the bored tunnels through Reach 3 of the alignment. Further, this paper outlines the proactive partnership between the owner, Los Angeles County Metro (Metro), the Design Builder, Skanska-Traylor-Shea oint enture (STS), and Southwest Geophysics who provided the geophysical services. Specically, the project included background review of historic site data (e.g., oil eld maps, building foundation plans, historic aerial photographs, etc.), geophysical demonstration testing to ascertain the capability of borehole magnetics to detect oil wells, directional drilling of thousands of feet of horizontal and vertical boreholes, collection of high resolution magnetic gradiometer data along vertically and horizontally cased boreholes as well as the collection of surface magnetometer data, discovery (“ground truthing”) of detected geophysical anomalies, and abatement of potential obstructions within the tunnel alignment.

Jun 23, 2024

By Ihsan Berk Tulu, Ted Klemetti, Deniz Tuncay

Accurately estimating load distributions and ground responses around underground openings plays a significant role in the safety of the operations in underground mines. Adequately designing pillars and other support measures relies highly on the accurate assessment of the mining-induced loads, as well as the load-bearing capacities of the supports. There are various methods that can be used to approximate mining-induced loads in stratified rock masses, both empirical and numerical. In this study, the numerical modeling approach recently developed at West Virginia University, which is based on the modeling approach developed by the National Institute for Occupational Safety and Health (NIOSH), is investigated using the finite difference software FLAC3D. The model includes the longwall panels, the adjacent chain pillar systems, and the different stratigraphic layers of the overburden. Using the 3D model, changes in loading conditions and deformations on the areas of interest, induced by an approaching longwall face, can be examined. This paper details the 3D modeling of a longwall panel utilizing this approach, and the verification of the results against field observations. The studied panel was 360 m wide with a 3-entry chain pillar system and about a 160-m average overburden depth around the studied area. The overburden strata consist of alternating layers of shale, sandstone, and limestone. The FLAC3D results were compared against field measurements from the mine site. The stress change values measured in the chain pillars were comparable with the modeling results. The model also replicated the surface subsidence profile obtained from field measurements fairly well. Overall, the 3D modeling approach was found to be successful for the case study longwall panel.

Sep 23, 2020

By MAURICE SUNKPAL, Taghi Sherizadeh, ELAHEH TALEBI, PEDRAM ROGHANCHI

Excessive heat exposure is among the health and safety hazards for mine workers. The nature of the underground climate makes it a convenient avenue for heat generation and accumulation from several heat sources, including autocompression, equipment and heat from strata. This study investigates the effects of clothing insulation and acclimation on the thermal comfort of mine workers exposed to heat in underground working environments. Several clothing ensembles were considered to analyze the effect of the thermal resistance of clothing on the workers’ thermal comfort. To investigate the impact of clothing insulation, the thermal comfort limit of an underground miner was calculated in the form of maximum allowable exposure time for an eight-hour shift.

By P. Zhang

Previous studies have shown that separation of clay minerals from non-clay minerals is the key to economic recovery of the phosphate from the waste phosphatic clays (slime) which represent about 20- 300/0 of the phosphate mined. Small hydrocyclones of different sizes (4" and 6") were tested for sizing the slime at +10 microns in order to remove most of the clay minerals. The effect of design variables and operating parameters were evaluated. Multi-stage cycloning and the effect of dispersant were also investigated. Chemical and mineralogical analyses of different size fractions of both the underflow and overflow samples indicated satisfactorily separation efficiency.

Jan 1, 1998

By F. Varley, J. Whyatt

A variety of dynamic failure cases with regional impact were described at a bump symposium held in 1958. These types of events, while rare, are of particular interest because their ability to impact a large area has disaster potential. These cases can be grouped into two broad classes of events by mechanism. These are (1) a slip along steeply dipping faults and (2) the fracturing of strong strata above or below the coal seam. Both failure modes produce dynamic or “shock” loads on the perimeter (roof, rib and floor) of mine openings. Special consideration should be given to these failure modes in the planning of deep coal mines, since their occurrence is not within the professional experience of many contemporary workers. In addition, their potential is not evaluated by many of the analysis tools commonly used to evaluate hazards in coal mine plans.

Jan 1, 2009

By D. E. Walsh

The behaviour of gold particles on a spiral was studied using radioactive gold tracers. The method allowed the effect of particle size, particle shape, pulp density, feed rate, and splitter settings to be studied. Although the method has been successfully applied to other gravity concentrators, it was found that reliable results were more difficult to obtain on the spiral. However, these preliminary results show that provided suitable precautions are taken, the technique is capable of providing valuable information that cannot be obtained by conventional studies, and could be used to better optimize spiral performance.

Jan 1, 1992

By Bryan Morris

Quebrada Blanca (QB) is a copper project located in the semi-arid Andean highlands of northern Chile. The operation is situated 170 km ( 105 miles) southeast of the port of Iquique and 30 km (18 miles) west of the border with Bolivia, at an altitude of about 4300 m (14,000 ft) (Fig. 1). The QB ore body is a secondarily enriched porphyry copper deposit containing reserves of 85 Mt (93 million st) grading 1.3% copper. Underlying the enriched zone is a significant primary ore zone containing several hundred million tons grading about 0.5% copper. In the late 1970s and early 1980s Falconbridge and its affiliates spent $20- $30 million exploring the deposit and conducting feasibility studies. Falconbridge, however, decided not to develop the property. It was returned to its owners, Empresa National de Mineria (ENAMI), a Chilean state mining corporation. In 1988, ENAMI announced its intention to privatize the property through public bidding. Cominco Resources, then 61% owned by Cominco Ltd., examined the property and the extensive data base developed by Falconbridge. In conjunction with its parent company, Cominco Resources submitted a proposal to ENAMI to construct an open- pit mine, with heap leaching and solvent extraction/electrowinning (SX-EW) processing facilities. The plan would use patented heap leaching technology developed by Sociedad MineraPudahuel (SMP), a privately owned Chilean mining company. At that time, a $150-million project that would produce about 45 kt/a (50,000 stpy) of cathode copper was envisaged.

Jan 1, 1993

This United States Bureau of Mines study is based on a review of U.S. mine fire accidents that occurred from 1970 through 1989. Information on these accidents was obtained through investigative reports written by Mine Safety and Health Administration personnel. For this study, 260 mine fire accident reports were examined. A previous Bureau research effort established that fires causing fatalities were more likely to occur in haulage entries than at any other underground location. This study has found that the most prolific source of haulage entry fires was the inadvertent grounding of trolley wires. The largest segment (15 out of 40 trolley wire fires) resulted from not maintaining adequate clearance between the trolley wire and the vehicle. Several novel fire prevention and control ideas have evolved in response to frequently occurring fire-related problems. These included; discriminating power isolation devices, wire cutting devices, more accessible fire extinguishers, vehicle overcurrent protection, and vehicle fire suppression.

Jan 1, 1994

By Edward S. Hsia

Pluor Utah has been closely associated with the engineering and construction of earth bottom thickeners for porphyry copper operations, for the counter-current decantation circuit of a gold cyanide plant and similar applications in mineral processing. During the past 13 years, some 18 of these thickeners have entered service and the bottoms have proved to be watertight structures with no particular problems encountered. In the course of this work, technological advances have been realized in the procedures for engineering and construction of these units to assure watertight basins and achieve all possible economies in construction. This paper describes the successful application of engineering and construction techniques for a number of these thickeners.

Jan 1, 1977

By Cleophus Short

[Of the many occupations in and about the coal mines, those of the haulage crews are among the most hazardous. Statistics ship that the second greatest number of fatalities about the coal mines occur during haulage ion and through the use or misuse of haulage equipment. During the five year period between January 1, 1957 and January 1, 1962, the m stone mine had a. Sack haulage frequency of 4098 and mined 3, 541,939 toads per haulage fatality. Coal mire haulage is similar in respects to railroading. We gee very serious consideration to the instillation of tack and to the selection of the haulage crews. In doing this, we are attempting to have our coal mine haulage as. Safe as that of the railroads.]

Jan 1, 1963

By Charles E. Dandois

New is a relative term, and, when used with reference to a concept as old as shaft kilns can be applied to a number of designs. In this case the design that is the subject of this paper, is known as the ring or annular shaft kiln as developed by Mr. Karl Beckenbach of West Germany. The first&apos; operating unit was rated 185 tons per day and was installed in 1962. Today, there are approximately 84 units in operation in Western Europe and Japan. Twenty-one additional units are in the process of erection or on order. Developed sizes range from approximately 100 to 330 tons per day. Units of over 500 tons are in the design stage, however, the largest units presently operating are rated 330 tons per day, <the first: of this size having been installed in 1966. "Figure" 1 is an elevation view of the unit. It is a single vertical cylinder to which are attached the required service platforms, combustion chambers, injectors and distribution piping. Auxiliaries such as recuperator, exhaust fan and dust collector are mounted on the appropriate service platform. The charging pan, feed conveyor, etc. are mounted at the kiln top. At the bottom of the kiln is the silo with a vibrator type discharger, and mounted separately is the required blower for injector air and fan for internal cooling.

Jan 1, 1973

By D. W. Dew, D. M. Miller, P. C. van Aswegen

The bacterial oxidation (BIOX®) process for pre-treatment of refractory ores for gold recovery is marketed by BIOMIN Technologies S.A. The process was originally developed by GENMIN who are still providing testwork, design and commissioning assistance to BIOMIN. This process offers an alternative to the more conventional roasting or pressure oxidation techniques with the following advantages: • Greatly reduced capital costs for small to medium size plants. • A relatively flexible and easily controllable process requiring relatively unskilled labour for operation. • Improved gold recovery. • A process that is environmentally friendly. The principal disadvantage of bacterial oxidation is the relatively slow kinetics compared to pressure oxidation and roasting, a plant residence time of 4 to 5 days typically being required to obtain complete liberation of gold from refractory sulphide minerals. Bacterial activity is also slow to recover from disruptions such as air supply failure or contamination by toxic species such as cyanide. Optimum plant performance depends on judicious management and sound training of operators.

Jan 1, 1993

By J. Kuti

In room and pillar mining a large number of working points are arranged to follow a mining pattern. Geological and roof control problems can be overcome or their effect minimized by varying this pattern. Longwall mining on the other hand, fixes the mining pattern for anyone panel. This aspect of longwall mining leads to constancy, so that a well-conceived organization, ventilation, dust and roof control systems lead to daily repetition and subsequent simplicity of control. All the same, a fixed mining pattern calls for a very careful consideration and selection of design parameters. (Ref. 1.)

Jan 1, 1971

By Donald Whittaker

Severe climatic conditions in mines are normally associated with working at depth. More precisely, it is a matter of working in regions of high strata temperature, since, for example, some coal mines in the Ruhr have strata temperatures at 1000 m which are matched only at 3 times that depth in the South African gold mines. In Britain we are perhaps fortunate in encountering strata temperatures in our deeper coal mines some 10-15 K lower than at the same depth in the hot mines of the Ruhr. Nevertheless the problems of high temperatures and humidities in UK mining operations, which in the past have been confined to a few specific sites, have in recent years become more widespread, and there is every reason to suppose that the trend will continue. Clearly strata temperature is not the only .causative factor. Long ventilation circuits serving districts remote from the shaft must also play a part, while the heavy use of machinery and the rapid, rates of excavation of modern mining methods are obviously important. It is necessary to understand the mechanisms of all such factors, and to measure their magnitudes and fluctuations, if remedial measures are to be properly designed or predictions made which are accurate enough to be of use in ventilation planning. This paper presents the results of a long-term (and continuing) investigation carried out in several mines to measure the major sources of heat and moisture on longwall districts and trunk conveyor roadways. The variation with time of these sources is reported, and the resultant effect on the climate is considered. In their investigations of the heat exchanges occurring in a whole mine Oakes and Hinsley (1955-56)1 listed and estimated the magnitudes of a large number of heat sources. Some of these, namely autocompression of the air in the shaft, diesel engines and compressed air mains, do not apply to the present investigations, which refer to longwall districts with conveyor transport and no compressed air supply. Others, such as oxidation of coal and, desorption of methane, have not been taken into account in the measurements, but are discussed later. One other source, the importance of which was pointed out by Gracie and Matthews (1975)2, is the coal on the conveyor, a form of strata heat emission, but one which is strongly dependent on the rate of coal production. The heat emissions measured in the present investigations were the energy consumed by electrical machinery, the heat conducted from the strata and the heat lost by the conveyed coal. Most of the emitted heat was removed from the district by the ventilation air, and was measured by continuously recording the enthalpy of the air at fixed stations. The heat removed by service water, supplied for machine cooling and dust suppression, was also measured. Account was of course taken of the relatively minor changes in level around the districts, in terms of the potential energy gained or lost by the coal and by the ventilation air (autocompression).

Jan 1, 1980

By David R. Delling

Introduction In 1967, Tenneco acquired Kern County Land Co. The primary reason for the acquisition was to obtain Kern&apos;s agricultural, manufacturing, and oil interests. Included in the Kern portfolio were the core of Tenneco&apos;s present sodium leases in Sweetwater County, WY. This lease base has been ex¬panded and now consists of 62 km2 (24 sq miles). Beneath this property lies more than 500 Mt (550 million st) of economic trona ore. Following the Kern acquisition, Tenneco continued exploration and feasibility studies concerning the trona leases. The effort was accelerated in 1976. Tenneco was attracted to trona because of the favorable lease position it held, the growth rate of the Wyoming industry during the 1960s and 1970s, and the prospects for a long-term, stable business enterprise. The reserve picture was certainly attractive to a company long accustomed to the never-ending struggle to replace oil and gas reserves. In 1978, Wyoming was a boom area that had experienced rapid growth for a number of years. Unemployment was very low and vacant housing nonexistent. The prospects for soda ash were somewhat different in the 1970s than now. But it was recognized even then that a new producer would have a challenging task to compete in this business. Tenneco knew the capital burden required to build a grassroots facility during inflationary time, would have to be offset elsewhere Since labor and energy are the dominant direct costs in mining trona and producing soda ash these factors have always received a great deal of attention. Contracting and permits Environmental monitoring on the site began in late 1977. With the already mentioned considerations in mind, engineering began by mid-1978. Brown & Root Inc. was selected as the general contractor for the project. S. A. Scott & Co. was the engineering subcontractor for the mine shafts, hoists, ventilation system, and miscellaneous mine facilities. Frontier-Kemper was awarded the contract for sinking the two mine shafts. Acquisition of numerous federal, state, and local permits occupied all of 1978 and 1979. The Wyoming Industrial Siting Permit, which addresses socioeconomic issues, drew the most public interest. Siting issues were all satisfactorily resolved by negotiating reasonable stipulations with various local governmental units, school districts, and the like. Site location The Green River project location is not truly remote. It is located within 5 km (3 miles) of Interstate 80 and only about 32 km (20 miles) west of the city of Green River. Nevertheless, a substantial investment had to be made in communication and utility links to the site. These included: • A 14-km (8.5-mile) rail spur connecting with the Union Pacific Railroad at Bryan, WY. This spur has four bridge structures including one crossing Interstate 80. Most soda ash is shipped by rail, and coal is received over this line as well. • A paved 5-km (3-mile) roadway connecting to Interstate 80. • A powerline extension of about 27 km (16.5 miles), along with two new substations. • A 24-km (15-mile) waterline connecting the plant to a pump station on the Green River. The site is located on gently sloping terrain at an elevation of about 2.1 km (6800 ft). Ground conditions are good for construction. Weathered bedrock lies near the surface in most places. Geology The general geology of the Green River Basin has been well described previously. Tenneco&apos;s ore is in several superimposed evaporate beds. But the bulk of it is present in Bed 17, located about 457 m

Jan 10, 1985

By G. W. Poling

Chemical and physical properties of thiol collectors are reexamined to compare the prospects of heavy metal-thiolate or disulphide surface reaction products acting as actual collector species. Recent evidences for the existence and importance of each of these types of adsorbed species on sulphide minerals are also discussed. A conclusion is reached that partial coverage by chemisorbed heavy metal thiolate is often sufficient to confer practical levels of hydrophobicity and floatability. Only on a few highly conducting and "noble" sulphides does adsorbed disulphide-type collector oxidation product appear to be significant.

Jan 1, 1976