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By R. N. Chakravorty

Spontaneous combustion presents a very serious hazard to both safety and economics of mining operations. Notwithstanding considerable research that has been done over the years to present and control spontaneous combustion the risk still exists. Consequently, this problem poses a major challenge to mine safety researchers; new and improved techniques are constantly being developed to deal with this major hazard. This paper reviews the current practices to prevent and control spontaneous combustion in coal mine operations highlighting new developments in this area. Research and development work presently being carried out in Canada to' deal with this problem is also discussed which includes monitoring, inertization and application of biotechnology.

Jan 1, 1988

By Kuzmitch O, Morozov A

The main direction in the mechanisation in the mines of the Donbas and the USSR is long-face technology with complexes on the base of hydraulic supports. On the base of the 30 year old experience of exploitation of the coal clearing systems the serious data about the behaviour of the contained rock, display of underground pressure 'on longwalls and preparatory workings have been accumulated. Exploitation works in mines of the USSR are carried out at different depths: from 1000m to 1200m. There are 26 mines in Donbas, which exceed the depth of 1000m. It is the mines of Donbas, where is a rich experience of the exploitation of coal seams in various conditions. Besides, there are wide variations on the factors of the extraction thickness, depth of seam, angle of dip, occurrence of gas dynamics and others. In many scientific establishments, and in Donetsk Polytechnical Institute also, there are scientific research/results, which can be of interest for the coal mining countries.The volume of coal mining from longwall system-mechanised walls in Donbas became stable at the end of the 70s at level of 70 percent. All the efforts to increase this level have not given any notable results, not saying about the technical-economical data, which gradually deteriorate. It shows that positive progress in using the technology for the long walls is over and it is necessary to find new ways of mechanisation of coal winning.

Jan 1, 1991

By J. Pang

The mechanisms of chalcopyrite oxidation in alkaline solutions have been studied using cyclic voltammetry and AC impedance spectroscopy techniques. Analysis of the impedance spectra using equivalent circuit models has made it possible to suggest layerwise growth of surface films. From the value of equivalent circuit parameters, properties of the surface layers are inferred. These properties change substantially with the change in oxygen and/or collector concentration in solution and give rise to changes In contact angle and flotation response. In agreement with prior investigations, the present study shows that flotation recoveries alone cannot be used to determine the effect of collector on flotation of chalcopyrite. The rate of flotation is a more sensitive parameter to determine the role of collector on floatability of chalcopyrite.

Jan 1, 1989

In the western Woodlark Basin, propagation of seafloor spreading is occurring directly into the continental crust of Papua new Guinea. The spreading is not strictly in a back-arc tectonic setting, rather it appears associated with microplate rotations related to the complex convergence of the Indo-Australian and Pacific plates in the southeastern Pacific region. Volcanic rocks along the western Woodlark spreading axis range from normal mid- ocean ridge basalts to basaltic andesites with back-arc geochemical affinities. Rare peralkaline rhyolites also occur. Hydrothermal deposits occur at a basaltic andesite volcano located on the neovolcanic zone near its westernmost propagating tip. Franklin Seamount is a 250m-high cone constructed largely of pillow lavas and talus which sits astride a 450m-high ridge of similar lavas oriented subnormal to the spreading direction. At its crest, 2150m below sea level, there is a 100m-deep caldera.

Jan 1, 1993

By D. A. Stanley

The Bureau of Mines has developed an equation which describes the dewatering of clay slurries with polyethylene oxide. This dewatering equation is An _ kC + b where n, k. and b are empirical constants and C is the concentration of polymer solution used for dewatering. The minimum amount of polymer required for dewatering. A is determined by titration of the clay slurry with a polymer solution. In this report, the dewatering equation is applied to data obtained for a polyacrylamide dewatering sequence. Fundamental similarities between the dewatering properties of clays and the viscosity of polymer solutions were observed. These similarities were explained by correlating an equation describing polymer configuration in solution with the dewatering equation. This correlation showed that amount of polymer required for dewatering and polymer solution viscosity are both consequences of the frictional interaction of entangled polymer coils.

Jan 1, 1989

Effective ground control in the gate entries, particularly in the tailgate travelways, is essential for safe longwall mining. Longwall pillars maintain gate entry stability and carry abutment loads. To answer the need for effective longwall pillar design, an empirical method called Analysis of Longwall Pillar Stability (ALPS) was proposed several years ago. Some recent research at the Bureau of Mines has focused on the refinement and verification of the ALPS method. ALPS was originally developed from field studies in which multiple stressmeters were installed in longwall pillars and monitored during mining. Several new field studies have now been incorporated into the ALPS data base. The field measurements have' been used to verify formulas for predicting abutment strength and pillar loads, and to develop an expression for the distribution of the abutment load.

Jan 1, 1989

By William Reisz

The explosives and blasting industry has a commendable safety and security record, especially over the last several decades. This is due in large part to our newer technologies, better training and education, engineering practices, corporate initiatives, our professional organizations, and whether we like to admit it or not - our regulatory agencies.

Jan 1, 2012

By W. de Bruijn

Differential reduction and expansion or shrinkage of hematite under the influence of intimately associated foreign oxides may be a source of stress formation and sinter degradation during blast furnace reduction. To study specific effects, synthetically pre-pared hematite powder evenly doped with 1% by weight of several elements present as oxides, was pressed into tablets and sintered at high temperature prior to reduction. Continuous thermo-gravimetric and dilatometric analyses were per-formed on the sintered tablets as these were being subjected to reduction under simulated blast furnace time/temperature/gas composition conditions up to 1183 K. These findings were coupled with observations on the microstructure of tablets removed from various stages of the reduction process.

Jan 1, 1988

By E. M. Frizzell

This paper addresses the use of the microcomputer programs BACKONE and BACKWEDG for an estimation of rock mass strength characteristics by back analysis of plane and wedge failures. The artificial support requirements are also determined by the programs PLANE2, BOLTPAT, and BOLTWEDG in terms of rock anchor installation angles, tensions, and installation patterns. These programs have been combined into a package called BACKPACK, which can be applied in open pit mines where some failures have already occurred.

Jan 1, 1988

By R. W. Barbaro

The limitation of sulfur dioxide in power plant emissions dictates that sulfur in coal be reduced to the lowest possible level before combustion so as not to aggravate the emission control problem at the stack. For coal fired power plants, the methods in practice to achieve low sulfur coal include mining areas with relatively low sulfur. reducing sulfur in the mined coal through preparation techniques and blending high and low sulfur coals. A prerequisite to the successful implementation of any of these practices is the knowledge of the spatial distribution and the capability to predict sulfur values in a coal seam.

Jan 1, 1988

By R. J. Roman

During the refining of primary magnesium metal: a spent flux (sludge) is produced which is considered a dangerous waste by the Washington State Department of Ecology. Four years of research, testing and marketing has identified two beneficial markets for the spent flux: 1) as a fertilizer and soil admendment as a result of the material's high potash and nitrogen content and its high lime equivalence and 2), as a roadway deicing agent to clear roads of ice and snow as a result of both the salt content and the flux containing chemical compounds which exothermically react with water.

Jan 1, 1988

By D. A. Rice

As part of a cooperative effort between the U.S. Bureau of Mines and the Florida Institute of Phosphate Research (FIPR), with input-from the phosphate industry, the conversion of phosphor-gypsum to sulfur is being investigated. The proposed process incorporates a thermal reduction of phosphogypsum to calcium sulfide (CaS) and a hydrometallurgical treatment to convert calcium sulfide to ammonium bisulfide (NH4SH), which is then oxidized using a catalyst to produce elemental sulfur. The paper summarizes the results of continuing laboratory studies using an activated carbon catalyst which was loaded with sulfur through oxidation of ammonium bisulfide solution. The extraction of the sulfur that forms in situ on the catalyst is a key area in the development of the sulfur recovery process. Two approaches for removing the sulfur are being investigated: 1) thermal treatment to volatilize sulfur, and 2) leaching the sulfur using liquid anhydrous ammonia. The research has shown that it is technically feasible to recover over 90% of the sulfur from the carbon by either volatilization or ammonia leaching. Locked-cycle testing has demonstrated that the carbon has the potential to be recycled after ammonia leaching.

Jan 1, 1988

By Abdulhadi H. M, Soliman S. A

The Western Desert of Egypt is a part of the arid Great Sahara of Africa which extends from the Nile Valley in the east to the Atlantic Ocean in the west. It is covered by a sedimentary sequence of Mezozoic and Teriary rocks. Recently this part of the country (about 65% of its surface area) has attracted an increasing attention in the plan of finding new agricultural and industrial communities outside the crowded Nile Valley. The plan aims to reduce the high population density in the narrow Nile Valley and to cover a considerable part of the increasing food demands in the country of Egypt. Accordingly, the groundwater exploration work in the Western Desert has been remarkably increased in the last decade, however it is still limited compared with the vast area of the Desert. The present work is a part of the groundwater exploration in the 6th October City, a new community located at 40kms west of Cairo. The rock exposures belong to a sedimentary stratigraphic section starting from the Cretaceous in the east to the Pliocene in the west. The Cretaceous outcrops due east are attributed to an almost N-S uplift and forms a thick massive limestone plateau which separates the present area from the Nile Valley. The Teriary section in the west have alternations of different porous formations such as the sands and sandstones which may acquire a good potentiality of groundwater resources. The previous groundwater exploration work included combined geological and geophysical investigations followed by exploration drilling. Although the area lies directly to the west of the Nile Valley, the discovered groundwater is saline and located at deeper reserviores compared with the groundwater in the Nile Valley. This groundwater was described as marine fossile water by the oil companies working in the Western Desert. From the geological point of view, it is believed that the Cretacious massive limestone plateau, in the east, roots to a depth which far exceeds the groundwater levels in the Nile Valley and acts as an impervious barrier between the aquifers in the Nile Valley and the area under investigations.

Jan 1, 1988

By J. D. Lowell

The gold content of prophyry copper deposits ranges from less than .05 gmt (ppm) to more than 1.0 got, and most deposits contain on the order of 0.05 gmt Au. Perhaps the highest grade mineralization which has been found in close proximity to a porphyry copper is the Ok Tedi Gold Cap orebody whose grade falls in the 2-3 gmt Au range.

Jan 1, 1988

By A. Wright

Gold Fields Mining Corporation is presently evaluating gold mineralization beneath thick, wet alluvium at the Chimney Creek Project, Nevada. Contamination of reverse circulation samples has been visually apparent since drilling began in the area. Tests have shown that, while contamination can affect assays, reverse circulation holes appear to define mineralized zones almost as well as the diamond drill holes. To improve reverse circulation sample integrity several techniques were tried including a stiff-mud injection system but with limited success. Diamond core drilling continues to be used in conjunction with reverse circulation drilling to further delineate the mineralization.

Jan 1, 1991

By G. J. Schneider

The higher stress zone adjacent to an underground opening causes a velocity anomaly that can be mapped in favorable conditions with an acoustic cross-borehole logging system. Bureau personnel used a specialized system at the Colorado School of Mines test site near Idaho Springs, Colorado, to locate the Edgar Mine tunnel and its associated stress anomaly. Data from the logging system' were processed with a tomographic image reconstruction algorithm to map the opening and the location of the high velocity zone around the opening. The velocity imagery from tomographic analysis compared favorably with predictions from numerical modelling of the location of the stress anomaly.

Jan 1, 1988

It is my role at this juncture to report to you on behalf of the Council of Mining and Metallurgical Institutions itself. In essence, the Council is an orbital body - a little like Halley's Comet - it returns to earth, in spectacular style, once in every four years. We must acknowledge, however, that the spectacle is provided by the constituent member body organising the particular event and, on this occasion, it is The Australasian Institute of Mining and Metallurgy. On behalf of the Council and its other constituent bodies may I thank the Australasian Institute most sincerely. Our thanks go to Sir James Foots, the President of the 13th Congress, and to all the members of the organising committee and to the five sub- committees. Over 40 people are involved as full members and I am certain there will have been many more involved in very meaningful ways. None of this great- team would ask me to mention them individually, I'm sure, but to fail to acknowledge the role of John Funnell, the Honorary Secretary, would be an unforgivable omission. We must also thank the kindred institutions in Japan, Korea, Thailand, Malaysia, and Indonesia who all helped with the tours themselves or with the initial preparations. Qantas, Jetabout Australia, and Jetabout Singapore have all also made very important contributions and, in our different ways, we each owe our thanks to them. At the two most recent meetings of the Congress - in Hong Kong and Johannesburg - Professor Marston Fleming made this report on behalf of the Council and was supported on both occasions by Robert MacWilliam as vice- chairman. Marston died in 1983 and Robert died in 1984; both men contributed a great deal to CMMI and we will miss their counsel for a long time. As you know, Sir Alistair Frame succeeded Marston Fleming as chairman in 1984 and I succeeded Robert MacWilliam as Vice-chairman.

Jan 1, 1986

By Jr. Neudecker

Rock melting technology can provide in-situ glass liners in nuclear waste package emplacement holes to reduce permeability and increase borehole stability. Reduction of permeability would reduce the time and probability of groundwater contacting the waste packages. In-creasing the stability of the storage boreholes would enhance the retrievability of the nuclear waste packages. The rock melting hole forming technology has already been tested in volcanic tuff similar to the geology at the proposed nuclear waste repository at Yucca Mountain, Nevada.

Jan 1, 1989

Research has determined that ground control interaction problems in mining over a previously mined seam occur primarily in the tension zone created at the edge of the subsidence trough, and in areas above lower seam remnant pillars. Based on empirical and analytical studies, planning options for improving conditions on the upper seam have been developed to optimize extraction while minimizing the negative effects of seam interactions. These options include prediction of potential upper seam damage, guidelines for minimizing inevitable negative interaction effects, and recommended opening and pillar sizes, shape, and orientations, as well as design and planning procedures.

Jan 1, 1988

By John MacDonald

An unstable economy has shown businesses what the mining industry has known for decades ? a successful business location today may not succeed in the future. Unexpected expenses, natural events and workforce changes have a big impact on the costs of production. To help focus production and maintenance budgets, mining executives are increasingly turning to production metrics to make key decisions. Role of mine and mill data Companies employ a variety of information systems to allow employees to accomplish their operational tasks, and each worker is focused on the metrics, or key performance indicators (KPI), for his or her individual function. For example, machine operators monitor throughput and cycle time to keep the machines running continuously and to meet daily production quotas. Meanwhile, the maintenance teams monitor machine performance, overall equipment effectiveness (OEE) and meantime between failure to predict and help prevent downtime.

Jan 1, 2013