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By Daniel W. H. Su

The importance of incorporating fundamental principles of rock material response and failure mechanics into a pillar strength design model has been demonstrated. To accurately assess pillar strength, a model should account not only for the characteristics of the coal, but also for those of the surrounding strata. The interactions between the pillar and the surrounding roof and floor dictate ultimate pillar strength. Confinement, or the lack thereof, provided by roof and floor frictional end-constraint is one of the most significant factors in the strength of very wide pillars. The best conditions for end-constraint occur with ideally strong roof and floor. In this paper, it will be shown that weak roof and floor may decrease the ultimate pillar strength by as much as 30% compared to ideal conditions. Field observations confirm this pillar strength reduction in the presence of weak roof and floor. Furthermore, rock partings within the coal have a variable effect on pillar strength, depending on the parting strength. A competent shale parting within the coal reduces the effective pillar height, thus increasing the ultimate pillar strength; a weak claystone parting slightly decreases the strength. Imposed load distribution also has a significant effect on pillar strength, such that asymmetric pillar loading, similar to that observed in pillars adjacent to high extraction mining, reduces the ultimate pillar strength below that of equivalent pillars subject to uniform load distributions.

Jan 1, 1997

By P Grieve, J L. Mauk

The Central Maratoto Valley in the Coromandel Peninsula contains a sequence of veins in pervasively altered dacite + andesites of the Waipupu Formation. We recognise at least eight different vein types: (1) pyrite stringers, (2) quartz + carbonate veins, (3) crystalline quartz veins, (4) carbonate veins, (5) chlorite + carbonate veins, (6) siderite veinlets, (7) siderite + carbonate veins and (8) carbonate + pyrite veins. The overall temporal trend of the veins is from early pyrite to quartz and then to late carbonate veins. Carbonate veins and pyrite stringers both form planar and irregular veins, whereas some carbonate veins have diffuse contacts with the wall rock. Gold and base metal sulphides are associated with some of the quartz + carbonate veins. Textures within the veins reflect open space filling and multi-phase reopening. A partial record of hydrothermal activity has been preserved by vein crosscutting relationships, hydrothermal alteration minerals and fluid inclusions. Hydrothermal alteration minerals display zonation from south to north. The alteration increases from unaltered to weak propylitic alteration of andesite in the south (MVRCDC1), to sericitic alteration of andesite and dacite in the north (MVRCDC3). The alteration assemblage is dominantly sericitic, with no adularia present, drawing parallels to the Thames region where there is no adularia.

Jan 1, 1999

By L. B. Hales

Image analysis for feed belts and flotation has been used for over 20 years. It has been shown to aid in the modelling and optimization of Sag Mill circuits, and any improvements in the image analysis result in improvements in the model for control. Using a laser to measure the height-profile of rocks on the conveyor has been shown to increase the accuracy of the size classification. We have developed a system using two cameras in a stereoscopic configuration to provide height-profile measurement without the added expense and safety concerns of using a laser. Additionally, we have developed a novel technique for calibration of the system, using artificial intelligence techniques to optimize the model fit by adjusting the image analysis tuning parameters to values resulting in the best classification.

Feb 27, 2013

By Z. Xiao, A. R. Laplante

"The recovery of gold by gravity from grinding circuits differs from virtually all other gravity recovery approaches in that stage (or unit) recoveries are low, typically 1 to 5%, but overall recoveries are generally in the 25 to 60% range, because individual gold particles are presented many times to the primary recovery unit. Full-scale recovery is difficult to predict from benchscale tests. Further, maximizing metallurgical recovery is generally not the primary objective, because of the more efficient downstream recovery circuit (flotation or cyanidation). In this paper, a new concept, the gravity recovery effort, is presented to assist in the design and optimization of gold gravity circuits. It is defined as the product of the circulating load treated by the primary gravity unit, the recovery of this unit, and the gold room recovery. Predicted gold recovery is linked to the recovery effort, the size distribution of gravity recoverable gold (GRG), the dimensionless retention time in the mill and the partition curve of GRG. A case study of economic optimization of the gravity recovery effort is presented. INTRODUCTIONPredicting gold gravity recovery from grinding circuits has always been a hit-and-miss exercise. The problem can be traced to the highly variable gravity recoverable gold (GRG) content of ores, high GRG circulating load, fraction of the circulating load treated, and performance of primary gravity recovery and gold room. Typical values, highs and lows are shown in Table 1."

Jan 1, 2001

By Gary Eck, Kevin Tallent

Over the past decades, the science of energetic materials has advanced dramatically in both the fields of military munitions, as well as industrial explosives. Out of necessity, test methods to measure the explosive performance properties of these materials were developed. As would be expected, these test methods have evolved and become more sophisticated with the recent advancements in electronics and computerized technologies.

Jan 1, 1998

Overexposure to noise is a widespread, serious health hazard in the mining industry, and causes hearing losses to a large percentage of the mining population. Recognizing this fact, the Bureau has a major on-going research effort to address this problem area. These proceedings include an overview of the Bureau noise control program and summarize nine selected noise control research programs.

Jan 1, 1984

By E. P. Carman

1. DAVENPORT, S. J. Bibliography of Bureau of Mines Publications Dealing With Health and Safety in the Mineral and Allied Industries, 1910--46. Tech. Paper 705, 1948, 154 pp. 30 cents. 2. FJELDNER, A. C., FISHER, P. L., AND POLLOCK, M. B. Bibliography of Bureau of Mines Investigations of Coal and Its Products, 1940 to 1945. Tech. Paper 698, 1947, 53 pp. 15 cents. 3. GOOD, J. E., ABREU, ALVARO, AND FRASER, THOMAS. The Coal Industry of Brazil. Part 1. General Economy, Production, and Marketing. Tech. Paper 713, 1949, 38 pp. 20 cents.

Jan 1, 1954

By K Palmer, G J. Artmont

Alluvial gold is an ideal exploration tracer to bedrock source and indicator of bedrock mineralisation style because: (i) gold occurs in a wide range of deposit types, (ii) primary composition is sensitive to style of mineralisation, and (iii) it is a heavy resistate mineral that is readily preserved and easily sampled. In regional exploration of the Central Ranges of Irian Jaya, alluvial gold mineralogy has been applied to maximise the information return from panned concentrate sampling and to focus exploration effort. Primary gold is a solid solution of Au+Ag¦Cu¦Hg, ¦ trace Pd, Te, and Sb. In general Ag¦Hg increase and Cu decreases with inferred decreasing temperature of formation, and gold from particular mineralisation styles has signature compositions that can be used as indicators of bedrock mineralisation type. Furthermore, the abundance of alluvial gold is an indicator of the economic potential of a catchment. The convergent continental-oceanic plate geology of the Central Ranges is conducive to a wide range of mineralisation styles. Mineralogy of gold in ophiolite, skarn, porphyry, mesothermal vein and possible VHMS environments is characterised from alluvial and bedrock samples, and the use of gold mineralogy in prospecting at regional scale through prospect definition to drilling is demonstrated.

Jan 1, 1995

By C. Daly

The Faculty of Engineering at the University of New South Wales (UNSW) offers a core first-year engineering design and innovation course, ENGG1000, undertaken during the first and second semesters. This course is highly regarded in the sense that it provides an introduction to many concepts and activities that students will experience over the four-year minimum for which they are undergraduates at UNSW. Approximately 1400 students enrol in the semester 1 course across the Faculty, typically 80 of which undertake the Mining Engineering stream. Students in teams of between six and eight design and construct a physical model to represent an aspect of their chosen discipline. For example, in 2013 the mining engineers designed and built a model dragline. This paper concentrates a major aspect of the course ? the involvement of team members in group activities and the development of the associated skills of peer assessment and peer review as the course progresses over a period of 12 weeks. The term ?peer assessment? in this paper refers to the requirement for students to assess the design components of their peers. This course has a structured requirement in terms of how a successful design is a result of a sound design process rather than a ?try and see? approach. Each student must describe in detail the process they undertook to achieve their final design ? hence the approach is independent of the discipline and/or project selected. Peer review is a process whereby students review the contribution of their team members to the overall design. This activity encourages team involvement and interaction. The final assessment mark can be moderated by the outcome of this peer review, although it is run twice during the semester. The first ?run? is for feedback only during week six and hence no moderation is undertaken. It was found through consultation with students and from questionnaires that both processes are well accepted and highly regarded by students, as they give them a degree of ownership of the assessment process. In addition, the processes provide rapid and relevant feedback on the progress of individual students. Peer review and peer assessment are also considered to be very valuable tools for use in courses in succeeding years. For instance, many of the courses in mining engineering rely heavily on group assessment tasks.

Jan 1, 2014

By C. Daly

"The Faculty of Engineering at the University of New South Wales (UNSW) offers a core first-year engineering design and innovation course,ENGG1000, undertaken during the first and second semesters. This course is highly regarded in the sense that it provides an introduction to many concepts and activities that students will experience over the four-year minimum for which they are undergraduates at UNSW. Approximately 1400 students enrol in the semester 1 course across the Faculty, typically 80 of which undertake the Mining Engineering stream. Students in teams of between six and eight design and construct a physical model to represent an aspect of their chosen discipline. For example, in 2013 the mining engineers designed and built a model dragline. This paper concentrates a major aspect of the course - the involvement of team members in group activities and the development of the associated skills of peer assessment and peer review as the course progresses over a period of 12 weeks.The term ‘peer assessment’ in this paper refers to the requirement for students to assess the design components of their peers. This course has a structured requirement in terms of how a successful design is a result of a sound design process rather than a ‘try and see’ approach. Each student must describe in detail the process they undertook to achieve their final design - hence the approach is independent of the discipline and/or project selected.Peer review is a process whereby students review the contribution of their team members to the overall design. This activity encourages team involvement and interaction. The final assessment mark can be moderated by the outcome of this peer review, although it is run twice during the semester. The first ‘run’ is for feedback only during week six and hence no moderation is undertaken.It was found through consultation with students and from questionnaires that both processes are well accepted and highly regarded by students, as they give them a degree of ownership of the assessment process. In addition, the processes provide rapid and relevant feedback on the progress of individual students.Peer review and peer assessment are also considered to be very valuable tools for use in courses in succeeding years. For instance, many of the courses in mining engineering rely heavily on group assessment tasks."

Jan 1, 2014

By Robert A. Clifton

It seems probable that more and more minerals will be used in plastics as time goes on. This must occur because the minerals will; aid in processability, enhance the engineering properties, reduce the cost, and above all conserve large amounts of petroleum based chemicals. This paper examines the advantages and disadvantages of using the minerals and the ability of the domestic minerals industry to support this possibly very large undertaking. In the author's opinion, it can. This talk is excerpted from a forthcoming Bureau of Mines Information Circular.

Jan 1, 1985

By Peter Riba

Up until ten years ago the industry had arrived at a relatively conventional, and consistent design of coke ovens. Through the years the designers and builders were not being heavily taxed to come up with revolutionary new designs. However, the stimulus for design change was ever present. These stimuli for change are quite important and they are the driving force which produce improvements. The most obvious stimulus to change a design is commercial. To "build a better mouse trap and the world will beat a path to your door" is the well used cliche which best befits this philosophy. As in all businesses, coke oven designs require that all of the considerations, which affect the cost or the desirability of the design, be optimized. One way to increase the desirability of the particular design, 1s to make the design in- expensive to operate. Or, put another way, to increase production for the same operating cost

Jan 1, 1980

Size Separation Pretreatment and Alumina Recovery from Bayer Red Mud

Sep 13, 2010

The proposed classification scheme is based on two primary parameters, one for petrographic composition and the other for rank, both being determined with microscopic techniques. The scheme has been applied to a wide range of Australian coals and found to provide a useful means of relating their inherent properties to properties such as volatile-matter yield, crucible swelling number, and calorific value, which will determine how these coals might be used commercially.

Jan 1, 1970

By James W. Martin

This user?s manual analyzes the application, selection and performance of hopper/crusher/conveyor systems used with front-end loaders in surface mining operations. It is designed to be used in conjunction with its companion manual: "Guideline Manual for Front-End Loader Load-and-Carry Applications" Aspects of the application are covered as well as design considerations of the hopper/crusher/conveyor units. Lists of equipment manufacturers, crusher specifications, together with a series of checklists, are included for preliminary analysis.

Jan 1, 1982

By J. R. G. Williamson

The Mining Division of Iscor, an integrated minerals and metals company, has recently completed a feasibility study for the establishment of a new heavy minerals mine and smelter in the Richards Bay area of KwaZulu-Natal, South Africa. The mine will produce a heavy mineral concentrate containing ilmenite, zircon, rutile and leucoxene which will be beneficiated at a central processing complex close to Empangeni. The ilmenite will be smelted to produce high-grade titania slag and pig iron for export. The ancient dune containing the mineral deposit is located some distance inland of the coastal dunes, and the sands contain a high proportion of extremely fine material which must be extracted ahead of the gravity separation process. Of the 56 million tonnes to be mined annually over the ten-year life of the mine approximately 23,4%?a total of 13,1 million tonnes of minus 45 micron residue fines?will have to be disposed of in a containment facility. The origin of the fine material is from the weathering of amphibole minerals. The remaining coarse sands will be returned to the mined area to re-create the original dune configuration. A number of options for the disposal of the residue fines have been examined and specialised laboratory tests undertaken to determine the deposition behaviour of the fines. The final solution involved the use of a ?sub-aerial? technique for deposition of fine material in a disposal facility. The resulting arrangement will adequately meet technical and environmental criteria. Upon closure after 10 years of operation, the surface of the disposal facility will be returned to sugar cane cultivation The paper refers to the various options considered and describes the problems associated with competent disposal of the residue fines and the development details of the final disposal facility.

Jan 1, 1997

This paper describes the excavation of No. 1 Power Station Lift Shaft at the Kiewa Hydro-Electric Project. The advantages and limitations of the borehole method are outlined, and general principles of plant design are discussed.INTRODUCTIONFor many years, attempts have been made to reduce mine development costs by various methods. Some of the, techniques of tunnelling have been adopted in horizontal headings, and in main vertical shafts, mechanical plant has displaced hand labour with notable success. However, in the field of small rises and winzes, improvements have largely been effected by attention to details of procedure. The most promising avenues for' substantial reductions in cost relate to:(a) Long-hole drilling(b) The borehole method(c) Calyx drilling.Whilst each of these methods has its peculiar advantages, the borehole rising method is probably most useful, and capable of wide application.In brief, the borehole method of rising requires a, drill hole parallel to the axis of the rise. A hoisting rope is passed through the borehole, and is attached to a platform on which the rising crew are raised with their equipment to the drilling position in the rise.When properly planned, the method is particularly safe, and has generally received the approval of mine inspectors and safety authorities. Rising work is generally hazardous, even when special timbering methods are used. In...

Jan 1, 1959

The U.S. Bureau of Mines conducted a laboratory study to determine what effect use of water-jet-assisted cutting has on frictional-ignition suppression. A single bit with a steel tip, installed on a rotating drum, repeatedly made 22-in-long cuts in a block of Berea sandstone. The drum was operated in an enclosure that contained an explosive methane-air mixture. High-pressure front-mounted water jets operating at 2,000 to 5,000 psig and low-pressure rear-mounted sprays operating at 80 psig were used; the number of ignitions that occurred with each type of spray was compared. The rear-mounted spray was more effective for preventing frictional ignitions than the front-mounted water jet.

Jan 1, 1989

By G Boyd

The Nokomai Gold Mining Project commenced production in January 1992. The Project continues a history of mining in theNokomai Valley which extended from 1863 to 1942. L & M Mining Limited have held interests in the valley since 1980. In 1990 the Nokomai Joint Venture was formed with the Hore family, the owners of Nokomai Station, to mine a large alluvial gold resource in the valley. The mine is located adjacent to the Mataura Brown Trout fishery and required extensive environmental studies prior to granting of permits. The mine is budgeted to work for 20 months, processing 460 000 m3 of wash material. During this period, contract miners, Downer Mining Limited, will move in excess of seven million cubic metres of overburden from the deposit.

Jan 1, 1992

By R. E. Head

[This paper embodies the data obtained by a detailed statistical, microscopic analysis of the composite mill feed concentrate, and tailing from the Magne and Arthur mills of the Utah Conger Co. for 1 month in 1929. It is one of a series of papers by the same authors5 dealing with the mineralogical characteristics of the ore and concentration products from various well-known plants. The work was done in the cooperateive microscopic service laboratory at Salt Lake and represents the results of cooperation between the United States Bureau u of Mines, the Utah Copper Co. and the University of Utah.]

Jan 1, 1935