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Autocompression and virgin rock tempera ture have a marked influence on the ventilation of the lower levels at North Broken Hill Limited N.S.W. To maintain comfortable working temp- eratures without penalty to working hours, increase in airflow or the cooling of the work area is necessary. The use of refrigerated air cooling is discussed. Ventilation of underground mining opera tions at North Broken Hill Limited is accomplished by downcasting air through No.3 shaft, the main operating shaft, 1581 m deep, with additional air through No.1 shaft (542 m) 2 and No.2 shaft (978 m), both no longer opera- tional shafts. Air is upcasted through No.3 ventilation shaft which is 4.9 m diameter and concrete lined, from the No.28 level (1140 m) to the surface. On the surface level of this shaft is a horizontally mounted Richardson 4800 mm diameter single stage axial flow fan with adjustable pitch rotor blades.

Jan 1, 1977

By A G. Greenwood

Research into cemented rock fill at Mount Isa Mines Limited since 1992 is described. The key mechanisms controlling segregation during stope filling with cemented rock fill are described and include the gravity flow mechanism which is described in detail. Examples are provided to demonstrate these mechanisms. Comparisons are made between Mount Isa MinesÆ cemented rock fill and slurry-based cemented rock fills. Recent backfill stability modelling using a three-dimensional finite element program is described.

Jan 1, 1998

By Brant BA, Lewandowski R, Trendle M, Haughton D

There is a vast amount of geotechnical data, which can be obtained during exploration programs at new and existing mine sites. Additional information on the performance of the in-situ rock mass can be obtained from bore cores, which are usually only geologically logged and then stored. A computer based data management system for storage and retrieval of geotechnical data has been developed to access and manipulate such data.

Jan 1, 1983

WMC Resources Ltd has been involved the development and trialling of an automated load haul dump vehicle system since 1997. This paper describes the introduction of the system into the Olympic Dam Operation and its performance compared with existing manual loaders. In certain situations the autotram loader will outperform the manual operation, particularly on the longer distances. There were no personnel injuries associated with the operation of the system during the testing period.

Jan 1, 2005

The most frequently applied project evaluation criteria are the Net Present Value, the Internal Rate of Return, and the Pay Back Period. Unfortunately, the Internal Rate of Return and the Pay Back Period, if interpreted according to their traditional definitions, easily produce results which contradict the Net Present Value. The reasons for the Net Present Value incompatibility of the two criteria are that these criteria have not been adequately defined and so new, complete definitions are recommended. The concept of the True Rate of Return is proposed as a substitute for the interest rate that the Internal Rate of Return has been believed to represent. The redefined Internal Rate of Return and Pay Back Period criteria, as well as the True Rate of Return are all Net Present Value compatible and can, therefore, serve as independent project evaluation criteria. Also, the correct approach to the evaluation of mutually exclusive alternatives and the status of the often neglected borrowing projects in project evaluation are found to be quite important.

Jan 1, 1991

By G Wood, B Lumsden

A statistical ærandomised block designÆ full plant trial of magnetic conditioning of flotation feed was undertaken at Rio TintoÆs Northparkes Mine in New South Wales. Magnetic conditioning of flotation feed has been shown to improve the flotation of 20 38 ¦m fraction for either metal. Approximately half the copper and gold losses at Northparkes are in the

Jan 1, 2007

The Curragh coal mining operation was designed and constructed to produce two coals initially at a rate of 4.3Mtpa. These are a high thermal energy steam coal primarily for domestic electricity generation and a low ash high quality coking product for the export market. Treatment of coals from four seams to achieve this requires a large and complex preparation plant and blending facilities incorporating state of the art technology. This facility was constructed during 1982/83. It has been designed for expansion to 6.8Mtpa capacity. The preparation and handling facilities were built at a cost of approximately A$80 million. Equipment includes 500 plus electric drives with a total capacity of 20 000kw. Commissioning was carried out in three phases : Staging - of the control system Coal Handling Facilities - conveyors, stackers and reclaimers for raw and product coals The Coal Preparation Plant - heavy media cyclones and froth flotation. A period of three months was devoted to the commissioning of the plant before requiring product coal to contract specification. This paper will describe the planning, implementation and results achieved.

Jan 1, 1986

The Taupo Volcanic Zone (TVZ) is the largest active volcanic belt in New Zealand. It is

Jan 1, 1987

Jan 1, 2004

The relationship between the permeability of coal to a mixture of methane and carbon dioxide, and the permeability to methane and carbon dioxide separately is described in this paper, along with the analysis of the differences in permeabilities of coal to methane and carbon dioxide.

Jan 1, 1989

As world demand for various minerals increases the mining industry in its endeavour to satisfy this demand will, eventually,look to the extraction of orebodies which previously may have been uneconomical to mine. These orebodies may be of two types. Firstly, new low grade orebodies and secondly, remnant sections of previously mined orebodies. Some of the factors relative to remnant mining operations are discussed and the potent- ial of remnant mining in providing an important contribution to future world metal production is considered.

Jan 1, 1975

The philosophy of computer control of grinding and flotation at ZC/NBHC is presented. The performance and reliability of the in- stalled systems are discussed.

Jan 1, 1978

By Adranyl W. W

Sub-level caving with bottom ore drawing has gained wide acceptance in rich, soft, low magnetic iron ores because it provides moderate ore dilution and ore losses. The main problem here is the high rock pressure exerted on sub-level drives situated in the sub-level sill pillars. To reduce this effect, the ore block is divided into panels. This paper illustraes the method of determining the maximum panel width providing low maintenance cost of sub-level drives.

Jan 1, 1995

Supergene enrichment of ilmenite occurs through a complex series of reactions with initial oxidation and hydration followed by leaching and dehydration. Lateritization appears to be associated with the early phase of the supergene process and if ilmenite grains are encased in iron oxides no further alteration proceeds.

Jan 1, 1986

By I Ross

The ground handling system needed for the second lift of the underground block caving operation at Northparkes Mines had to link into the existing infrastructure. Production requirements indicated that an annual output of 5 Mtpa was necessary from a depth of approximately 850 m. The shaft that serviced the first lift stopped at a depth of 520 m. This paper covers the selection of the design for the system and the factors that were taken into consideration in making the decision. It will describe the installation program and methodology and highlight areas of significance and then detail some of the issues concerning commissioning of the ground handling system.

Jan 1, 2005

This paper examines the methods and people required for the evaluation of project or corporate acquisitions. Experience over the past five years has shown that some growth can be achieved by carefully evaluated acquisition of gold projects within regions where the acquiring company has gold processing facilities. Many Western Australian companies have participated in this process and the trend seems likely to continue with a diminishing number of larger producing companies controlling through joint venture or direct purchase of widely spaced ore deposits. In some cases the acquisition may include ore processing facilities, however an increasing number of smaller project acquisitions, involving small open pit gold deposits, which are within trucking distance of the acquiring company's mill. Whilst gold prices remain at the current depressed level we can expect to see this trend continue.

Jan 1, 1989

By E Villaescusa

This paper describes a methodology for the design of mine pillars at the McArthur River Mine. The pillar strength is calculated using a method that accounts for confinement, pillar geometry and intact rock properties. The average pillar stress was calculated using in situ measurements of vertical stresses at shallow depth and the tributary area method in conjunction with numerical modelling. Observations of pillar behaviour indicate that an existing pillar stability graph may be slightly conservative and further adjustments for the local rockmass conditions are needed. The results to-date indicate that all mine pillars are stable for a range of mining geometries at McArthur River Mine.

Jan 1, 1998

By Taylor R. K A, Berglin C. I K

The manganese ore deposits at Groote Eylandt are quite variable both in regard to grade and physical cond- ition. In order to treat a wider range of these ores and to increase production a new primary-crusher and' concentrator complex costing $8 million has been installed and commissioned to treat ore at the rate of 12,000 tonnes per day. The initial testwork carried out to determine the method of the ore treatment required, and on which the design of the concentrator was based, is detailed. The flowsheet and equipment used is discussed together with the operation of the plant. The production achieved and product qualities obtained are given.

Jan 1, 1973

By Van Rensburg C S J

The options that are open to engineers for cooling mines are limited and are primarily dependent upon the thermophysical properties of coolants. These properties are carefully analysed in the context of cooling mines and a comparison is drawn among Ammonia (R717), Monochlorodifluoromethane' (R22), Dichlorodifluoromethane (R12) and Water (R718). From this comparison the extent of Ammonia's superiority as refrigerant is Evident.

Jan 1, 1988

The on-going technical developments to enhance the productivity and cost effectiveness of large blasthole drills incorporate many of the blasthole drilling operating experiences garnered over the past half century.Those experiences have shown in part that on a drill unit with good quality structural elements the higher the percentage of the electrical and electronic components designed into the product, the higher its productivity and the lower its operating cost.

Jan 1, 1992