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By P Nichols, C te Kloot, A Harrison

Ernest Henry mine (EHM) is a sub-level caving operation located in north-west Queensland, Australia. Located below a previously mined open pit, the underground operation ramped up production to 6.8Mt/a in 2017. The EHM ore body dips at 45 degrees to the South and therefore requires each level to “step out” from the level above as seen in Figure 1. Within this step out zone it is important to both maximise recovery and allow for efficient operation of the underground workings production to bring the level up to full production as quickly as possible. Throughout the step out design process, a combination of further defining the ore boundary, using lessons learnt from production performance on upper levels and the introduction of design improvements, has reduced the production ramp-up time, decreased costs and increased recovery for a single level at EHM. CITATION: Nichols, P, te Kloot, C and Harrison, A, 2018. Case study – Ernest Henry Mine: designing step out zones in an inclined sub-level cave, in Proceedings Complex Orebodies Conference 2018, pp 53–54 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By S. F. Walsh

The San Manuel Oxide Pit is located within the subsidence boundaries of Magma Copper Company's block caving operation. Ground conditions offer a constant blasting challenge and vary from hard, competent crystalline rock to widely spaced fracturing in a sedimentary conglomerate. A successful drilling and blasting program has undergone several changes since mining commenced in 1985 and continues to be developed. This paper discusses the site specific progress made with the drilling and blasting program from selection of feasibility parameters to current practice. Topics discussed include controlled blasting, use Of high energy blasting agents, charge decking, blast casting, as well as standard drill and blast techniques.

Jan 1, 1988

By W. Hu

Gravity concentration has been the main method for tin ore beneficiation, based on the significant difference of density between cassiterite and gangue in the tin ore. However, with the exhaustion of rich and coarse reserves, the proportion of tin distribution in slime be-comes as high as 50 to 70% and has a size range of -19 urn. In some sulfide tin ore, most of the tin is of the minus 10-urn size fraction, and thus slime processing has gained importance in tin ore processing. Some innovations are being developed, such as the centrifugal cone separator, belt concentrator, slime table, B-M separator, and slime flotation. Direct flotation with tolyl arsonic acid has been practiced with success.

Jan 1, 1989

By R. Spring

Artificial intelligence, and especially expert systems, are currently receiving considerable attention. Of interest to the control engineer is the utilization of these tools for real-time process control applications. To evaluate this technology, a real-time expert control system was implemented in one of the grinding circuits at Brenda Mines Ltd. The performance of this micro computer based expert system compared satisfactorily to the proven supervisory control system currently in use. The study confirmed the expectations that expert systems have potential for real-time, supervisory control of mineral processing operations.

Jan 1, 1989

By T. I. Martinovic

A major investigative' program was conducted on the development of an acceptable substitute organic binder for bentonite for the pelletizing of the Iron Ore Company of Canada's Carol concentrate. The first phase of the program covered an evaluation of several organic binders in laboratory tire balling in order to identify the most promising potential organic binders. Based on the green ball quality obtained, Peridur C-10, Alchem 8C26 and peat moss were selected for full scale pot-grate testwork. The selected binders were tested with various pelletizing mixes (acid, dolomite, limestone and fully fluxed). The pot-grate test results showed that an acceptable pellet quality can be produced with the use of Peridur C-10.

Jan 1, 1989

By B. L. Seegmiller

Regular entry trusses are used in headgates, tailgates, roadways and intensely-faulted areas. These trusses have proven to give the required support and maintain roof stability even under major abutment loading conditions for both the re-treating and advancing longwalls. Areas previously requiring steel arches have been eliminated. A special Continuous Entry Truss? provides permanent support to adjacent tunnel/crosscut zone for more than 300 feet in each tunnel. The continuous nature of the tensioned truss allows sup-port forces to be placed on the roof in not just the two-dimensions of regular trusses, but in a full three-dimensions. A newly developed Roktruss? provides support in an arched 30-foot high rock zone. The Roktruss? allows truss support concepts to be used in an opening with a curved roof.

Jan 1, 1989

By S. C. Sethi

The paper presents an analysis and discussion of the underground ventilation system at the waste Isolation Pilot Plant (WIPP), with particular emphasis on specific repository-related requirements and the gradual evolution of engineering designs relative to the WIPP Project scope. The underground facility has been constructed with three shafts. Additional studies, coupled with actual site-specific experience, have established? the need for construction of a fourth ventilation shaft to double the under-ground airflow. As a research pilot project, and the first of its type in combining mining and nuclear technologies, the WIPP Project is accumulating data and experience that may be fruitfully applied in the future designs of ventilation systems for planned commercial nuclear waste repositories.

Jan 1, 1988

By D. Baker

Alternative material handling methods are allowing material handling operations to be performed with increased cost savings. This allows for higher production levels with better returns. RAHCO International Inc.'s Continuous Mining Excavator (CME) has recently received a lot of attention due in part to its operating efficiency, flexibility, and associated low operating costs. The CME is designed to perform three primary functions. These include material excavation, sizing and loading operations. In many applications, a drilling and blasting process can be eliminated. The CME was developed originally in 1985 for open pit coal mining. See figure I. Since this time, it has been proven an effective system for excavating many other types of materials including friable and sticky materials. It has also been shown to suitably handle hard rock in certain site conditions.

Jan 1, 1998

By A. MacG. Robertson

Where weak rock zones are encountered in the slopes of an open pit, they may control pit wall stability. Back analysis of slopes involving failure through weak rock enables an estimate to be made of the weak rock strength. A system of consistent rock mass classification is described which enables the weak rock mass material to be described and classified from drill hole core. Correlation with back analysis determined strength allows strength estimates to be assigned to each rock mass classification.

Jan 1, 1988

By W. E. Bron, E. S. Machlin

GRAIN boundary migration in V-shaped thin specimens of high purity silver was studied. Each specimen contained two crystals having the relative orientation: (111)A/(111)B; (ll0)A/(101)B. The boundary between these two crystals varied between a continuous curved and an alternating two plane interface. The plane interfaces were oriented parallel to (101)A/(011B) and (121)A/(211)B. Traces of these planes are shown in Fig. 1. Evidently the two plane interface, although of higher area, comprises lower total interface energy than the average curved boundary it replaced. The plane boundaries were found to move at 650 °C to consume the broad segment of the V opposite to the direction of interface area and energy decrease. On investigation, using the thermal etching technique of Hendrickson and Machlin,1 it was found that the outer grain contained 8.3x108 more dislocations per cm" than the grain at the apex of the V. Consequently, the boundary moved to decrease the strain energy associated with the difference in dislocation density across the boundary. The rates of motion of specific {110} and {112} boundaries were measured during interrupted anneals at 650°C by referring the position of the boundaries to each other and a fiducial line on the specimen surface. The measured rates of motion are 0.075 and 0.025 mm per hr for the {110} and {112} boundaries, respectively. Plots of grain boundary motion vs time of annealing show straight lines with little deviation of data points from these lines.

Jan 1, 1957

By A. Ghalambor

The objective of this investigation was to determine the sensitivity of three selected input parameters in the operational control of continuous bottom-fed thickeners used for the treatment of coal refuse slurries. The three variable parameters were "Feed Flow Rate," "Feed pH," and "Feed Solids Concentration." These three input parameters were studied under three polymeric conditions which were cationic polymer, anionic polymer, and a combination of cationic-anionic polymer. For each polymeric condition, two mathematical models were developed: one for overflow response, the other for underflow response. The combination polymers produced the best desired quality of overflow and underflow. For this polymeric condition, changes in the feed solids concentration was the most sensitive factor in the maintenance of the overflow quality, and the feed pH was the most sensitive factor for the maintenance of the underflow quality. The mathematical models generated a set of plots which would allow an operator to control and/or adjust any of the three variables to achieve optimum conditions.

Jan 1, 1989

By J. B. Austin

Jan 1, 1945

By Jorgensen D. K.

The Bullfrog and Montgomery-Shoshone deposits, outside Beatty, Nevada, have a combined drill-indicated reserve of 17.4 M tons of ore with an average grade of 0.103 oz/t Au and 0.240 oz/t Ag. The deposits occur in Miocene volcanic rocks which underwent large-scale movement within a detachment-faulted terrane. The principal host to gold mineralization is a strongly welded rhyolitic tuff which experienced brittle deformation during plate movement. Open-space fractures and breccia were filled with quartz, calcite, and adularia accompanied by lesser pyrite, gold, and acanthite. Gold occurs as micron-sized particles within and adjacent to the low-angle fault and along associated listric-normal and tear faults.

Jan 1, 1989

By R. O. Burt

The Tanco pegmatite is located in the Bird River greenstone belt of south-eastern Manitoba approximately 160 km northeast of Winnipeg (Figure 1). The orebody was discovered in 1929 and subsequently attempts were made to exploit it for tin by Jack Nutt Mines Ltd. and later in the middle 1950's by Montgary Oil Ltd., who extensively developed but did not produce from its lithium deposits. In 1966 systematic investigation of the pegmatite as a potential source of tantalum led to the founding of Tantalum Mining Corporation of Canada Ltd. (TANCO), and production of tantalum concentrates from the Bernie Lake mine commenced in 1969. Tanco's currently jointly owned by Hudson Bay Mining and Smelting Co., Cabot Corporation, and the Province of Manitoba.

Jan 1, 1988

By D. H. Warren

This presentation we hope will provide you with an orderly approach co mine and surface plant closure taken from our experience over the past several years on six different projects within the intermountain states. There is no magic to the approach. It is basic common sense and yet it is interesting how many of the specific details are overlooked due to the individual complexity of each site. Our attempt here is to share some of the issues that have confronted us on these six sites. Please recognize that it is impossible to be all inclusive. Of the six sites we have drawn from; two are mine, mill and smelter sites dating back to pre-1900, one is an industrial site dating back to the early 1900s, two are mill and concentrator sites dating from the late 1940s and one is a mining district site dating from the late 1800s.

Jan 1, 1989

By M Bettison, R Marton, R Wright, M Lowry

Depending on the geological setting, waste rock from mining can present risks to achieving acceptable closure outcomes. In the Pilbara iron ore mines, the majority of waste rock is geochemically inert. However, small percentages of pyritic material with the potential to generate acid and metalliferous drainage (AMD) require considered management within mine waste stockpiles designed to minimise AMD release to the environment. A larger percentage of waste rock has physical characteristics (e.g. erodibility) that may impact upon long-term landform stability. CITATION:Marton, R, Wright, R, Lowry, M and Bettison, M, 2018. The golden thread of waste characterisation from exploration drilling to waste rock placement, in Proceedings Life-of-Mine 2018, pp 90–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By D. C. McIntire

The Homer City Station, jointly owned by New York State Electric and Gas Corporation and Pennsylvania Electric Company is a three unit coal fired station. The first two units were put into commercial operation in 1969; the third unit became commercial in 1977. Units 1 and 2 are subject to the Pennsylvania State Implementation Plan (SIP) emission limit of 3.7 pounds of S02 per million BTU. Unit 3, having started construction later, is subject to the Clean Air Act, New Source Performance Standards emission levels of 1.2 pounds of 50-2 per million BTU.

Jan 1, 1988

By J. A. Hren, C. M. Wayman

RECENT investigators have noted anomalous behavior in the electrical resistivity of vanadium below room temperature. Rostoker and Yamamoto1 in studying the vanadium-oxygen system hypothesized that the body-centered-tetragonal phase existing from 15 to 34 at. pet O at approximately 800°K was really a low-temperature allotrope of vanadium that was stabilized by oxygen. In measuring the electrical resistance of cold-swaged vanadium rod over a range of temperatures, a small discontinuity was observed at approximately 240°K, supporting their notion of allotropy. However, the magnitude of the observed discontinuity was extremely small. Loomis and Carlson2 in studying the ductile-brittle transition in vanadium also made resistance measurements and reported a discontinuity near 200°K. More recently, White and Woods3 showed that the electrical resistivity from room temperature to approximately 100 °K was not linear and at variance with the Bloch-Griineisen law. Instead of finding a discontinuity, they observed a deviation from linearity below 200°K. In discussing their results they pointed

Jan 1, 1961

By T. B. Jarboe

The 150 MWe circulating fluidized bed (CFB) power plant described in this paper is the product of recent Bechtel experience in the industrial power and steam market, where the economic feasibility of fluidized bed projects has been proven. The inherent ability of CFB boilers to burn low grade fuels makes it possible to also burn low ranking coals or coal wastes, including anthracite culm, coal mine rejects, and coal wash plant waste slurry. The impact of fuel characteristics on plant design is addressed. This includes solids handling, steam generation, sulfur capture, and auxiliary load requirements.

Jan 1, 1988

By C. I. Huang

The mining industry is an easy target for criticism from an environmentally sensitive society. Recent researches discovered that human activities, including mining. cannot be blamed for all of the pollution observed on earth. Interdisciplinary research is providing diagnostic and remedial solutions to problems such as acid mine drainage and cyanide-polluted streams. Researchers have also found that mercury-bearing hot springs and volcanic eruptions are partly responsible for some pollution. Geochemists, mining geologists, engineers, and environmental scientists can pool their efforts to make the environment cleaner and safer. Remote sensing of the environment and the use of microbes may become much more popular in the near future in the mining-environment arena.

Jan 1, 1988