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By Maria I. De Rosa

The major fire and fire injury findings for all coal mining categories for 1990-1999 are reported in tables 37-38. Table 39 and figure 13 show the number of fires. fire injuries, risk rates, employees' working hours, and coal production (under- ground and surface coal mines only) by time period for all coal mining categories. Table 40 shows major findings (for under- ground coal mines only) for 1978-1992. For all coal mining categories, 458 fires occurred during 1990- 1999; 157 of those fires caused 164 injuries and 2 fatalities (Ewhr = 2,070 x l0%r, Irr = 0.016: C'P (for underground and surface coal mimes only) - 10,363 x l0\t, Frr = 0.044, LWD = 14,753). Twenty-nine fires and 17 injuries involved contractors. Sixty-six fires required firefighting interventions by mine rescue teams (25 times in underground mines) and fire brigades and fire departments (at least 41 times at surface coal operations). In all, 51 fires destroyed or heavily damaged equipment (including 16 pieces of mobile equipment) because of failure of other firefighting methods, late fire detection, undetected fires, or fire size. A total of 114 fires were detected late, and 42 fires were undetected. The greatest number of fires and fire injuries occurred at surface coal mines; the highest risk rate values were also calculated for this category. For all coal operations, the ignition sources that caused the greatest number of fires were flame cutting/welding spark/slag/flames (1 03 fires or 23% with 69 injuries), hydraulic fluid/fuel sprayed onto equipment hot surfaces (98 fires or 2 1 % with 29 injuries), spontaneous combustion/hot coal (62 fires or 14%), electrical short/arcing (49 fires or 11% with 18 injuries), and conveyor belt friction (3 1 fires or 7% with 6 injuries).

Jan 1, 2004

By Maria I. De Rosa

The major fire and fire injury findings for all metal/nonmetal mining categories for 1990-2001 are shown in tables 64-65. Table 66, partly illustrated in figure 22, shows the number of fires, fire injuries, fire fatalities, risk rates, employees' working hours, and lost workdays for all metal/nonmetal mining categories by time period. For all metal/nonmetal operations (including stone and sand and gravel), a total of 518 fires occurred during 1990-2001; 296 of those fires caused 308 injuries and 4 fatalities (Ewhr = 4,012 x 106 hr, In = 0.015, LWD = 36,204). Thirty fires and 26 injuries involved contractors. The greatest number of fires and fire injuries occurred at surface operations; the highest risk rate values were also calculated for surface operations. The number of fires increased during the first four 2-year time periods (1990-1991, 1992-1993, 1994-1995, and 1996-1997), then decreased during the last two periods (1998-1999 and 2000-2001). The number of injuries showed a decrease throughout the periods, accompanied by an increase in employees' working hours. Twenty-five firefighting interventions by mine rescue teams in underground mines and at least 30 interventions at surface operations were required to combat these fires. However, 45 fires destroyed or heavily damaged facilities and equipment (including 19 pieces of mobile equipment) because of failure of firefighting methods, late fire detection, undetected fires, or fire size. Ninety-seven fires were detected late, and 30 fires were undetected. The ignition sources that caused the greatest number of fires were flame cutting/welding spark/slag/flame (169 fires or 33% with 137 injuries), hydraulic fluid/fuel sprayed onto equipment hot surfaces (89 fires or 17% with 46 injuries and 3 fatalities), heat source/explosion and flammable liquids/ gas/refueling fuel on hot surfaces (98 fires or 19% with 73 injuries), electrical short/arcing (51 fires or 10% with 16 injuries), and spontaneous combustion/hot material (46 fires or 9% with 17 injuries). The flame cutting/welding spark/slag/flame source caused fires usually involving welders' clothing or oxyfuel/grease and other materials (including chute and dust collector liners, flammable liquids, belt material, crusher, hopper and shaker deck materials, washer plants, equipment mechanical components, stampler breaker, hydraulic fluid, rubber tires and hoses, gear boxes, bin feeder, dump rope cables, screen liner and screen panel, kiln and shaft material, pipelines, liquor pumps, wood pallets, electrical junction boxes, handrails, grease, refuse, shop and wood). The spontaneous combustion/hot material and electrical fires were usually detected late due to lack of combustion gas/smoke detection systems. At least 55 of the 89 mobile equipment hydraulic fluid/fuel fires became large fires (requiring 12 mine rescue team interventions in underground

Jan 1, 2004

By Michael D. Fenton

Bauxite resources were primarily in Africa, Asia, Oceania, and South America. Only five countries combined, Australia, Brazil, Guinea, India, and Jamaica, contained most of the total world reserves available for extraction under current economic conditions and accounted for nearly 80 % of world production of bauxite. World bauxite and alumina production declined and prices for smelter-grade alumina remained below the $200/mt level during 1993 because of growing aluminum inventories on international markets and declining worldwide demand. The United States imported bauxite primarily from Australia, Brazil, Guinea, and Jamaica. U.S. alumina plant capacity remained essentially unchanged throughout 1993, but apparent capacity utilization decreased by the close of 1993. Chromium Most of the world's known resources and reserves of chromite are located in India, Kazakhstan, South Africa, and Zimbabwe. India, Kazakhstan, and South Africa accounted for 73 % of world production of chromite. The two largest producers of chromite, Kazakhstan and South Africa, were in the process of major economic and political change during 1993. South Africa's production and exports of chromite continued to fall during 1993, because of weak international demand and a flood of cheap metal from the former U.S.S.R. and China into world markets. Despite a significant increase in production, South Africa's ferrochrome producers continued to operate below capacity in 1993. Prior o the dissolution of the U.S.S.R., Kazakhstan was a major internal supplier of chromite ore to the U.S.S.R. consumer, but subsequent decline in demand led to a downward trend of chromite production in Kazakhstan and increasing exports to Europe during 1992 and 1993. The United States consumed, about 10% of world chromite ore production in various forms of imported materials. The United States imported nearly one-half of its required chromium contained in chromite ore and chromium ferroalloys and metal from South Africa; the remainder was from the minor producers Turkey, Yugoslavia, Zimbabwe, and others.

Jan 1, 1995

The West Coast region of the South Island is situated astride the Pacific û Australian plate boundary zone. The most significant component of this zone is the Alpine Fault. A variety of reconstructions of the pre-Alpine Fault plate tectonic configuration of the New Zealand continental area have been attempted over the past 25 years or so. Most of these have not been closely constrained by a regional compilation of field data related to the age and horizontal displacement history of the Alpine Fault. A model in which the Alpine Fault was initiated no earlier than the interval 18 - 16.5 Ma (B.P.) is proposed, a significantly younger age of inception than has been widely accepted as the onset of dextral displacement along the plate boundary through the South Island. A subsequent history of displacement is presented consistent with the West Coast basin stratigraphy. The alluvial gold content of some parts of the Miocene to Pleistocene conglomerate sequences is also discussed.

Jan 1, 1996

By W. R. Reed

NIOSH continues to conduct respirable dust control research for surface mine blasthole drilling operations. Research areas have included testing variables (shroud leakage area, drill deck cross-sectional area, shroud height, collector-to-bailing airflow ratio, etc.) that have the most impact on respirable dust control, development of a dust collector inlet hood, development of a dust collector dump point shroud, and testing of a small diameter water separating sub. This paper summarizes the results of the aforementioned research that has been completed. Additionally, past dust control research for drilling operations of both underground and surface mines completed by the U.S. Bureau of Mines, created in 1910 and incorporated into NIOSH in 1997, is reviewed.

Jan 1, 2008

By S. J. Page, W. R. Reed, J. A. Organiscak

NIOSH continues to conduct respirable dust control research for surface mine blasthole drilling operations. Research areas have included testing variables (shroud leakage area, drill deck cross-sectional area, shroud height, collector-to-bailing airflow ratio, etc.) that have the most impact on respirable dust control, development of a dust collector inlet hood, development of a dust collector dump point shroud, and testing of a small diameter water separating sub. This paper summarizes the results of the aforementioned research that has been completed. Additionally, past dust control research for drilling operations of both underground and surface mines completed by the U.S. Bureau of Mines, created in 1910 and incorporated into NIOSH in 1997, is reviewed.

By Walter von der Linden

On April 14, 1975, Consolidation Coal Company began to operate a longwall face in their Shoemaker Mine using shield supports. This was the first time that shield supports were used in the United States (1) 1/. Shortly thereafter, Kaiser Steel Corporation started a shield longwall face at their York Canyon Mine (2). From October 1975 through May 1976, three more longwall faces were commissioned in mines located in south-western Pennsylvania and northern West Virginia. In June 1976, four installations had completed their first panel and two installations had completed the subsequent move to the second panel where coal production is now well under way. During this time (April 75 to June 76) the total number of shield support face operating months, including moving time, was 40 and the combined face advance was approx. 17, 000 feet (5200 m) with face lengths varying from 450 - 550 feet (137 - 168 m). While the shield support experience in the U.S. is still limited on the basis of time and mining parameters, the operating results of all faces have been very satisfactory. New record 24 hr production figures were set and - far more important - long term production figures could be sustained on an impressively high level even when taking face moving time into account. The purpose of this paper is to review the performance of shield type supports in the U.S. and to assess their value as longwall supports for U.S. underground mining conditions with regard to roof control, maintenance, operator convenience, safety and productivity.

Jan 1, 1976

By Walter von der Linden

A description is presented of the mining conditions of four longwall shield type support installations in the Pittsburgh seam in northern West Virginia and southwestern Pennsylvania. Details of roof control and operating procedures, production and performance data, and equipment description and basic engineering specifications are given for these four longwall installations. The range of mining heights was between 150 and 250 cm (60 and 95 in.). The major accomplishment of the shield supports in all four faces was the provision of an almost 100% availability for coal cutting; i.e., the face-down time due to roof control problems and support maintenance requirements was minimal.

Jan 1, 1978

By Francis D. Leathers

Four friction pile load test programs, including 23 tension tests and 9 compression tests, have been performed as part of the Central Artery/Tunnel Project in Boston, Massachusetts. The tests, performed on both precast, prestressed concrete (PPC) piles and steel piles, yielded the following adhesion values: [Soil Type Clay Clay Glacial Till Interbedded Sand and Clay Interbedded Sand and Clay Pile Type PPC Steel Steel Steel PPC Adhesion (psf) 610 to 1,200 230 to 900 220 to 550 680 1,280 ] The adhesion appears to be affected by differences in pile material type, with PPC piles having higher adhesion than steel piles. However, part of the apparent difference for the clay may be due to differences in time between driving and testing. The significant range of test data means that the need for site specific testing to determine or verify design values of adhesion should be considered during design. Creep rates at loads near failure ranged from about 0.02 to 0.18 inches per log cycle of time, with most values in the range of about 0.04 to 0.08 inches per log cycle of time.

Jan 1, 1994

The paper discusses some theoretical aspects of Gy's sampling theory and provides reasons as to why it has found limited use in the mining industry, particularly for ores with low concentrations of values such as gold. These types of ores are referred to as low grade ores in the paper. It is shown that the misuse of the a priori liberation factor proposed by Gy is the main reason for the implementation limitation of Gy's model for low-grade ores. In addition, results of a case study done at the Gencor Geostatistics Department based On the new implementation of Gy's theory are provided.

Jan 1, 1996

Problems discussed and research opportunities identified during the workshop in the major areas of 1) flocculation, 2) flotation, 3) leaching and magnetic separation are summarized below. I. FLOCCULATION Problems Practical problems caused by unintentional flocculation or dispersion were described in the papers that dealt with iron ore processing, selective flocculation, fine coal processing, phosphate processing and potash processing. Ideas generated during the discussions ranged from the very practical suggestion that a conscious effort be made to transfer knowhow from the experienced clay industry to the metals and fuels-from-slimes industry. . . , to the familiar appeals for omnipotent theoretical developments. There was surprising recurrence of some questions in many contexts. Recurring questions are emphasized here rather than commodity-specific problems because their answers would serve a wider clientele usage. There is indeed no objection and some advantage to commodity-specific research, however, provided the proposed project is planned with full cognizance of transferable knowledge in other commodities, and of the possible usefulness of these results in other areas. Research Needs Most of the questions or research opportunities can be classified into three groups: a) water chemistry, b) dewatering, and c) flocculation theory. Other classifications are possible and probably useful. In each group there is a clear need for outwardly esoteric theoretical research a clear application of that work to current practical problems. Higher priority should be given to proposals for theoretical research which explicitly show the expected ultimate usefulness of the result. Likewise, proposals for applied research should demonstrate cognizance of applicable theory. Both of these types of projects could profit from collaboration among industrial, university and government personnel.

Jan 1, 1979

MONDAY, FEB. 17 9.00 A.M. to 9.00 P.M. Registration at Institute Headquarters. 9.00 A.M. Meeting of Committee on Development of the Activities of the Institute, Room 905, 9th Floor. 10.00 A.M. Simultaneous Sessions of Institute of Metals Division, Room 2, 5th floor. Industrial Organization, Room 1, 5th Floor. 12.30 P.M. Luncheon at Headquarters, 5th Floor. 2.00 P.M. to 4.25 P.M. Simultaneous Sessions of Institute of Metals Division, Room 2, 5th Floor. Industrial Organization, Room 1, 5th Floor. Petroleum and Gas, Room 905, .9th Floor. 2.30 P.M. Sightseeing trip by automobile for the ladies. Among the points visited will be: The American Museum of Natural History. The Episcopal Cathedral of St. John the Devine. The Spanish Museum. The American Geographical Society. The American Numismatic Society. The visits will be followed by Tea. 4.30 P.M. Memorial Service to Dr. Rossiter W. Raymond, Auditorium. 8.30 P.M. Smoker, 5th.floor.

Jan 2, 1919

By E. G. Joe

"This paper summarizes the main conclusions derived from twenty-two technical presentations made at the 1973 meeting of the Canadian Mineral Processors. Results of two surveys with response from over seventy mines were reported on Canadian milling practice for water re-use and on elimination of cyanide from mill effluents. Water and solution recycle in Canadian mills were detailed for copper, copper-zinc, lead-zinc-copper, nickel-copper, iron and gold mines. Cyanide elimination from mill effluents was reported under current practice and under requirements for further treatment by various other processes. Three recent process equipment entries into Canadian mills have been the on-stream particle analyzer, the new gravity concentration tables for recovery of fine tin and other heavy minerals, and solution-jet slurry equipment for reclaiming ground ore from storage. The principles of operation of this equipment were described along with the practical limitations that were found in their application to mineral processing. Capital costs and milling cost reductions were shown in some operations. Computer control of flotation mill processing was a major item on the program. Four major mining companies outlined their mill process control strategy, computer programs and on-stream analysis equipment. Some capital costs and personnel changes were presented, together with gains in concentrate grade and mill recovery. Recent development work has shown the effect of the type of grinding and of aeration on the recovery of sulphide minerals in flotation. One mining company reported a significant depressing effect on copper sulphide flotation while floating ore ground with mild-steel balls; also, pyrite appeared to be activated in the subsequent zinc flotation step. One company with extensive experience in the application of aeration to copper sulphide flotation showed significant improvement to copper recovery by pre-aeration. Both the effects of grinding and aeration were subject to the constraints of the chemical condition of the ore pulp. The metallurgy of silver recovery by combination grinding - gravity treatment and of gold recovery from a complex gold-sulphide ore were reviewed in two papers on precious metals. The latter paper further described the recovery of gold from the Cottrell collectors and the final disposal of arsenic from the dust collectors."

Jan 1, 1973

A project was funded by the Australian coal industry to investigate the mechanisms that might lead to sample bias when using cross-belt cutters, in order to help coal industry personnel to make better decisions about the purchase, maintenance and operation. It concentrated on DEM modelling of skew cutters. These are set at an angle to the belt with the intention of minimizing disturbance to the non-sampled material. Two bias mechanisms are likely to cause bias for cross-belt cutters. Waves of material are bulldozed off the belt by the upstream side of the body of square cutters and material is thrown by the leading edges of cutter blades for all types of cross-belt cutters. These mechanisms cause some parts of the load of material on a belt to be over-represented. The effects of these mechanisms cannot be made to be negligible, so cross-belt samplers cannot be trusted to produce unbiased samples, especially for segregated streams of material. However, it is possible to give a bound on the maximum likely bias. The grades of two portions of the stream can be estimated by stopping the belt and shovelling off 1/3 of the cross-section of the load on the belt into a container, concentrating on the final side of the belt and the top of the load. The remaining material should be put into another container and the difference in grade determined. The maximum likely bias is typically about 10% of this difference. For a cross-belt cutter, having an extraction ratio near to 100% is not a reliable indication that the cutter has little or no bias. Some bias mechanisms affecting cross-belt sample cutters make sample mass too high and some make it too low, so an extraction ratio near 100% can occur if two bias mechanisms are both active. Keywords: sampling, DEM simulation, sample bias, accuracy, precision

Jan 1, 2009

By S L. Birch, M D. Raven

X-ray diffraction (XRD) is a well-recognised, invaluable tool to provide detailed mineralogical analysis on a wide range of applications. However, despite the wide use of XRD in many industries, there are currently few recognised standard methods for quantitative XRD analysis and none for the analysis of iron ore materials. An initial step towards preparing a standard method for XRD analysis of iron ores was to assess the current level of precision achievable by practitioners of the technique by organising an international round robin. Six Australian chemically certified iron ore reference materials were distributed to over 100 international participants. A summary of over 120 data sets from more than 80 participants is presented. Results show that a bewildering array of techniques for sample preparation, data collection, phase identification and quantification were used. The reported values for the main components (ie hematite, goethite, quartz and amorphous content) show not only extensive variability between participants but also within participants’ results for those who submitted multiple data sets. The disappointing low level of precision exhibited for a relatively simple mineral phase system indicates a strong requirement for development of a standardised procedure.CITATION:Raven, M D and Birch, S L, 2017. Summary of results of an international X-ray diffraction round robin for mineralogical analysis of iron ores, in Proceedings Iron Ore 2017, pp 599–604 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Leonard Obert

Before 1957 a number of investigators reported stress determinations made on or near the surface of underground excavations. The usual procedure was to measure surface strains and to calculate the stresses using laboratory-determined values of the elastic constants of the rock. In some instances strain gages were stress-relieved so that the measured stress was absolute. Also, several investigators reported near-surface absolute stress determinations made by the flat-jack procedure. In 1958, Hast1 described a procedure for making absolute stress determinations within a body of rock. In this procedure a diametral deformation gage was placed in a borehole and then the borehole was overcored to produce stress relief. The secondary principal stresses in the plane normal to the axis of the borehole were calculated from measured deformations and the elastic constants of the rock. During the past nine years a number of investigations have been reported1-20 in which this technique, or modifications of it, have been reported. Both the stress distribution in the walls of underground openings and the stress field at points as great as 200 ft from these openings have been determined. Considered collectively, these reports shed some light on the nature of the stress distributions in the proximity of underground openings and on the stress field, that is, the state of stress outside of the zone of influence created by openings. To summarize these findings first consider the stress distribution in the wall and structural components of openings. Fig. 1 (a) shows a typical theoretical stress distribution curve in a linear-elastic, isotropic, homogeneous material. Fig. 1 (b) is an idealized measured stress distribution curve for the same opening in a relatively unfractured uniform, but brittle,

Jan 1, 1967

By E. A. Anderson

In 1918 the American Society for Testing Materials held a symposium2 on what was then known as season cracking. The sessions included six papers, all on brass. During the ensuing 26 yr., many new workers have come into the field and several other metals have been found subject to failure by stress-corrosion cracking when the right combination of stress and environment is achieved. It is not surprising, therefore, that the present symposium has brought forth 29 papers covering alloys of seven important metals. The phenomenon of stress-corrosion cracking is not necessarily confined to these seven metals. Dix3 has stated, "Indeed, it is probable that ingenious investigators can find solutions which will stress-corrosion crack any known metal or alloy." Mears, Brown, and Dix4 have indicated that stress- corrosion cracking failures are not necessarily limited to metals but may include the plastics. It is to be expected that the increase in the number of metals known to crack in service and the general emphasis on such failures at a symposium such as this will alarm many to whom the subject is un- familiar. Such alarm is not justified by the record. It is true that stress-corrosion

Jan 1, 1945

Many of the difficulties faced by the U.S. mineral industry in 1982 and 1983 emanated from the worldwide recession, from the high value of the U.S. exchange rate, and, in part, from actions taken by foreign governments to protect selected industries. While some problems will be minimized with continued worldwide economic recovery, others remain and may require special attention by U.S. policymakers. These problems include declining U.S. production capacity in selected mining and mineral processing industries, the impact of the high value of the U.S. exchange rate, and protectionist trade practices by competitor nations. Illustrative of the last is the International Trade Commission (ITC) determination in June 1984 that both the domestic steel and copper industries have been substantially injured by foreign imports. In its July 1984 recommendations to the President, the ITC suggested higher tariffs and quotas for 5 years on 70 percent of steel imports but conditioned the aid on cost-cutting and modernization steps by the domestic industry. In the copper decision, two commissioners recommended increased duties, two recommended that quotas be imposed, and one recommended that no relief be provided. The President decided in September to seek voluntary restraint agreements with nations that export steel to the United States and rejected both quotas and higher tariffs on copper imports. General Economic Setting This decade opened with the U.S. mineral industries struggling to deal with double-digit inflation, record high peacetime interest rates, and almost 7 years of oil-cartel-induced energy price increases that seriously affected the profitability of energy-intensive industries such as mineral production and processing.

Jan 1, 1985

By J. Michael Howard

Holes cored through the Prairie Creek lamproite volcanic complex at the Crater of Diamonds State Park by companies interested in the site's commercial diamond potential give an opportunity to redefine the size and shape of the Prairie Creek pipe. Relationships of cored rock sequences and the discovery of a previously unrecognized major rock type allow a reinterpretation of the sequence and type of intrusive activity. Trench sampling of diamondiferous rock units yielded a diamond content far below what was anticipated based on an estimate from historical records. Inadequacies of shallow bulk-testing methods for a diamondiferous pipe are examined.

Jan 1, 1999

By K. Delbeke

Within the framework of the EU Existing Substance (93/793/EEC) and REACH regulations EC/1907/2006), the copper industry initiated in 2000 a comprehensive Voluntary Risk Assessment of copper and several copper compounds. The Italian Government's Istituto Superiore di Sanità, reviewed the process and reports on behalf of the European Commission. Copper exposure levels to man and the environment from production of copper anodes and cathodes, copper powders and copper chemicals as well as fabrication and use of semi-fabrication products and down stream user products were collected across Europe. Environmental and human health effects data were obtained from literature as well as novel research programs and used to deduct safe threshold

Jan 1, 2007