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By Toivanen R-M, Leinonen O, Pekkarinen H

This paper presents developments in designing an integrated mine control system at Kemi mine. The aim of this paper is to present the general structure of the system and to outline some features of the process control strategies. The results o

Jan 1, 1998

By Cullen JF

Australia has a large resource of manganese at BHP's Groote Eylandt mine which has been progressively developed over the last two decades. While much of the product is marketed internationally to the iron and steel industry, substantial quantities are processed in Australia at the Company's ferro alloy works in Tasmania. In addition, small but increasing quantities of ore are being consumed by the non-metallurgical industry. Fluctuating fortunes in the steel industry produce similar trends in the marketing of manganese. The increasing cost of freight and power together with strict environmental control is further affecting the market balance. Mine operators are expanding into the alloy making field. Reduction in usage in less developed countries is occurring.

Jan 1, 1982

By Van Hoorn PD

For the development of BHP's Gregory open cut coal mine in Central Queensland a mini computer was successfully used to assist staff in the evaluation of the deposit and the planning of the mine. The Gregory deposit is essentially a single mineable seam deposit, however the systems developed may be applied to other coal deposits including multi seam occurences. The first phase of the Gregory computer evaluation and planning project involved the establishment of a borehole data base for the storage, retrieval and analysis of both strata and quality data. During the second phase a numeric block model of the coal deposit was created. Using this model reserve calculations were carried out by specifying the area with the aid of a digitizing tablet. The third phase involved the develop- ment of systems to simulate the dragline stripping operations including the rehandle percentage calculation, a dragline production schedule showing coal quantity and quality exposed, and a combined multi dragline operation schedule that can produce figures and graphs for up to 20 variables. A derivative of the operating plan was a programme that gave productioh cost estimates

Jan 1, 1978

By Yinxiang W, Chunlai Y

In older to improve efficiency of surface pre--grouting in sealing off water in heavily water-bearing strata, such as sandstone,siltstone and limestone, several methods have been used in China, they are ; intermittent pre-grouting, adjusting pre-grouting parameters and stepwise repeated pre-grouting methods. The paper describes effect of deviation on water sealing in pre-grouting. Deviation correction measures, like mechanical, technological and changing hole position methods have been introduced with satisfactory results in practical engineering projects without increasing the volume of engineering project and without causing delay.

Jan 1, 1988

Shear strength testing of rock discontinuity surfaces has been undertaken at a considerable number of open pit gold mining operations in Western Australia, as part of geotechnical studies of pit wall stability. These mining operations are located in geological settings that are typified by highly weathered and/or chemically altered rocks that contain significant structural fabric in which accurate and representative measurement of shear strength is essential.Little of the published rock discontinuity shear test work and back-analysis of failures has been conducted on weathered discontinuity surfaces, at low normal stress levels which are comparable to Western Australian conditions. Available shear strength data are reviewed and the following aspects of shear strength testing are considered:ò the need for shear strength test work and the amount of testing required;ò review of laboratory testing methods and the quality of the results; ò presentation of the test results;ò discussion of the shear strength failure criteria; ò interpretation of the test results;ò summary of test results for a variety of rock types, degree of weathering and discontinuity surface conditions;ò a review of laboratory and field shear strength data to illustrate the amount of variability that can occur; andò a monitoring strategy is proposed to manage the uncertainty associated with discontinuity shear strength.

Jan 1, 1992

By Matthew SP, Hayes PC

The product morphologies formed on the reduction of dense wustite crystals are classified into three types,A) porous iron, B) porous wustite covered with dense iron and C) dense wustite covered with dense iron. The mechanisms of formation of these structures and the effects of impurity elements on the product morphologies are discussed

Jan 1, 1984

By Enever JR

In-situ rock stress measurements conducted in the Phillipines and on Bougainville have revealed stress fields significantly different from expectations based on intraplate experience. The results have potential significance in regard to both engineering practice in the Pacific Rim region as well as in helping to understand the geological processes occuring near subduction Zones.

Jan 1, 1987

The great variety of geological conditions in French coal deposits has obliged the industry to develop different thick seam mining methods. In very steep seams in a dense deposit where stowing is necessary to avoid spontaneous combustion, surface subsidence and water problems, a rising horizontal slice method is used, the coal being hard enough and the seams regular (Lorraine). In very thick and irregular steep seams where the stowing is not necessary, a sub-level horizontal slicing is used; a third method has to be used in Dauphine.

Jan 1, 1976

By Szwedzicki T, Jiang J

The acoustic emission (AE) technique has found wide application in rock engineering. Generally, acoustic emission, which is produced by a rapid microcrack growth, is an ubiquitous phenomenon associated with brittle fractures and can provide information on the failure process in rocks. The sudden release of stored energy in the form of an elastic stress wave that travels from the point of origin within the material to a boundary is called an AE signal or a discrete AE event. Based on a number of experiments and analysis, the correlations among the rock type, the complete stress-strain behaviour, mode of failure and AE properties are investigated and the AE pattern has been classified as four types: single-peak AE, double-peak AE, continuous AE and absent AE. Each type of AE pattern corresponds to a certain type of rock and is largely related to the internal structure and imperfection of a rock. Applications of the AE technique in stability monitoring, in situ stress assessment and seismic source location are also discussed.

Jan 1, 1995

By T Weldon

In the last 15 years, it has become increasingly popular to win gold and silver from carbon strip solutions with electrolytic æsludgeÆ cells. The precious metal sludges produced in the cells are washed to the cell bottom and pumped into filters. Most new operations are specifying sludging cells, and many older operations are being retrofitted with up-to-date electrolytic sludge cells and filters. The new sludging cells are generally more energy efficient than older cells, but more importantly, the cell operations to remove product are much less labour intensive, cleaner, and the operator need not have physical contact with the electrolytically produced metal. A case study of a major North American gold producer (50 000 kg/yr) that removed old style stainless steel wool cathode cells and installed new sludging cells and sludge filters is presented. The effect of various impurities is discussed.

Jan 1, 2005

By Cornell J. B

Scaling in Bayer Refineries is a natural consequence of the super-saturated liquors used in the process. The caustic liquor is supersaturated not only with alumina but also silica and calcia at various stages of the process. The basic scaling mechanisms are reviewed and examples of the two basic types, growth and settled scales, are given. Examples include gibbsite scales formed in the precipitators and silica scales formed in heat exchangers. The main factors affecting the rate of growth of growth scales are temperature and supersaturation and are highlighted using a silica scale example. For growth scales chemical cleaning rates can readily be predicted from kinetics and an example for a gibbsite scale is given. For settled scales the growth rate cannot be predicted and the hydrodynamics within the system have most effect. There is no simple method to predict the potential for chemical cleaning of settled scales; some of the relevant issues are discussed, in particular methods to identify the cementing phase in the scale. An example of design considerations for a scaling system, transport of slaked lime, is Given.

Jan 1, 1996

Initial coal production at Ulan was solely from underground mines. A significant increase in demand for steaming coal in the late 1970's emphasised the need to further expand production and led to the development of the open cut mine which commenced commercial production in June, 1982.During the initial stages of mine planning, feasibility and cost studies were undertaken to determine the most suitable method for coal haulage from the pit. The comparison between a conventional truck haulage system and an in-pit crushing system using a mobile crusher and moveable belt conveyor haulage confirmed that the mobile crusher and conveyor system was superior in every respect for the Ulan mining operations.Technical features and design parameters for the major items of equipment are outlined as well as operating, manning and performance assessments. Minor equipment problems were encountered during initial operation but these have since beenrectified and the plant is now capable of exceeding the design production. Maintenance and energy costs are considerably lower than originally estimated and production efficiencies are continually improving as operators develop new techniques and procedures in the handling of the equipment.

Jan 1, 1985

By Keele R. A

The Cambrian structure in the Mt Read Volcanics was produced by four deformational events: obduction of forearc-derived mafic/ultramalic complexes in the early Middle Cambrian, a middle Middle Cambrian extensional phase related to the post-collisional Mt Read volcanism and VHMS mineralisation, Middle Cambrian E-W folding, and Late Cambrian N-S folding and basin inversion. The major phase of VHMS mineralisation in western Tasmania is restricted to the very brief period of extensional tectonics within the middle Middle Cambrian. Within this period a N-S graben was produced with a complex series of transfer zones, largely striking E-W. Most VHMS mineralisation is restricted to the top of massive volcanic successions, with several mines close to Cambrian transfer structures. Many of the transfer structures continued to be active until the Devonian. The later compressional Cambrian events are not significant in localising orc formation. Within the Rosebery mine a complex pattern of minor Cambrian normal faults has a second order control on the distribution of the mineralisation.

Jan 1, 1997

Ore sorting is a high capacity, low cost method of preconcentrating ores and in some cases of producing a marketable concentrate. In most cases it is applied to run of mine material, immediately after primary crushing and screening in sizes ranging from 10 mm to 150 mm. Recent developments in bulk sorting of friable uranium deposits have resulted in machines capable of handling fine materials with sensing and separation being achieved on a zone by zone basis. Modern ore sorting machines rely on the synchronous operation of four internal sub systems, feed presentation, sensing, data processing and separation. A variety of different sub systems is available which can be combined in various forms to produce sorters capable of handling a wide variety of mineral types. The benefits in using ore sorting cover a wide range of situations and are applicable to both established mines as well as new mining ventures. Reduced operating costs, increased productivity, capital savings, energy and resource conservation and environmental issues are all part of the reason why ore sorting is finding rapid acceptance in today's mining industry.

Jan 1, 1980

By Yu A. B

An experimental study of the packing of a coal heap has been carried out. The bulk density of a coal heap is considered as a function of a number of variables, viz flow rate, conveyor belt speed, the height of the disengagement point of the conveyor belt, coal particle density, moisture content, the size of the heap and coal particle size distribution. The effects of the dimensionless numbers resulting from dimensional analysis on the packing density of a coal heap have been experimentally examined and analysed. Based on the experimental results, equations have been formulated for the estimation of the bulk density of a coal stockpile. The validity of these equations are checked by comparing the predictions with measurements of real industrial Stockpiles.

Jan 1, 1991

By Stone I

Tahmoor Mine is located in the southern Sydney Basin 80km south-west of Sydney and produces 1.2 MT of Bulli Coal annually. Bord and pillar methods used to date will be supplemented by a longwall system. Difficult roof conditions have been experienced since mining began in 1979. A dominantly horizontal stressfield promotes shear failure in the thinly interbedded roof sequence of shales, laminites, siltstones and fine sandstones. General roof conditions and failure characteristics are related to the angle between the roadway direction and the principal horizontal stress direction. The apparent stressfield changes direction, magnitude and the ratio of principal horizontal components across the mine workings in response to both in situ and mining induced causes. Initial roof support of 5 x 2.1 m bolts per W-strap at in intervals, with mesh, was upgraded to include RSJ's in order to support areas of failed roof. This support system was inefficient and costly. A third system of support emphasizes roof reinforcement with full resin encapsulation of 2.1 m bolts in W-straps. The number of bolts per strap (6-8), extra butterfly straps and bolts, and W-strap spacing is determined for each area by expected roof and stress conditions. Intersections are pre-bolted and ribs are supported in some areas. Pillar dimensions, order of drivage and roadway width have each been altered to improve roof control. The intensity of roof deformation at the face varies from panel to panel and causes development rates to decrease to 30% of the maximum. 1. Manager, Tahmoor Mine, Tahmoor, N.S.W. 2. Senior Geologist, BP Coal, Picton, N.S.W. Roof conditions in each area of the mine are characterised and then projected to future development areas based on the relationship between stressfield orientation, relative roadway direction and face conditions. Planning information available includes expected development rates, roof support requirements and areas of changing conditions. Future improvements of strata control involve defining support design parameters for the range of mine conditions already seen at Tahmoor.

Jan 1, 1986

By Weller KR, Restarick CJ, Stewart PSB

Following a detailed assessment of concen trator performance at Broken Hill South Limited which was reported in a previous paper, the fine grinding section was changed from a parallel arrangement of the two grinding circuits to a series arrangement, and the concentrator per- formance re-assessed. The change to series grinding had virtually no effect on the actual or potential capacity of the circuit to make a final product with 80% passing 100 mesh. However, the fresh flotation feed contained significantly less +150 mesh lead and +65 mesh zinc (material which was shown to float poorly), without an increase in the quantity of poor-floating ultra-fine lead and zinc. From the size-by-size flotation recovery data, it was shown that overall recoveries of both lead and zinc were approximately 1% higher than they would have been without this change in size distribution and it was concluded that this was a direct result of the change in grind- ing procedure.

Jan 1, 1972

By I Arburthnot, N Lawler, C Loan

The function of a thickener is to optimise and accelerate the process of gravity sedimentation. The desired end product (be that maximised concentrated solids or clarified liquid) determines how the thickener is designed and operated.Significant internal research, together with extensive on-site piloting, by Outotec has resulted in the determination that the application of the appropriate amount and type of shear to hindered settling aggregates can result in a substantial change to the sedimentation process. A new patented technology, called shear enhanced thickening (SET), has been developed. SET results in considerable design implications for full-scale thickeners, including a substantial reduction in required footprint and/or significant increases in underflow density.The development of SET, combined with laboratory and pilot scale verification, will be discussed along with the introduction of this technology to a number of full-scale thickeners. The associated implications and benefits for industrial thickeners are outlined.CITATION:Loan, C, Lawler, N and Arburthnot, I, 2012. Industrial scale results from shear enhanced thickening technology, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 341-346 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By I Gipps

The mining industry has come through a period of major change in community expectations regarding safety and environmental impact and these changes can be expected to continue in the future. These changes are ultimately reflected in Government regulations and industry safety standards and form the basis of the ælicense to operateÆ. Equally, advances in technology have made possible new equipment and processes either available now, or close to completion, that will allow mines to meet these more stringent expectations if properly introduced. Changes in technology provide opportunities for mine management to introduce new systems that will remove people from hazardous areas and lead to improvements in the ætriple bottom lineÆ. In a longer time frame of five to ten years, novel and advanced technologies that are currently being developed will deliver new mining methods and conversion of presently uneconomic resources to ore. This is consistent with the time frame required to develop a new mine from discovery. Strategic decisions can be taken now by mine designers to enable the introduction of these major technology changes. Examples of both practical and strategic opportunities are drawn from the integration of rock cutting/blasting, automation, electronic communications and new mining methods. This paper discusses emerging industry trends, changes to legislative framework and some practical choices for existing and imminent technology.

Jan 1, 2003

The paper focuses on how rock bolts are loaded in different rock masses, as well as in pullout tests. Three analytical models for rock bolts are presented in brief, one for bolts in continuously deformed rock masses, one for bolts in blocky rock masses, and one for bolts in pullout tests. The bolt models are used to interpret measurement data for rock bolts from three sources and to help specify the modes of axial load in the rock bolts. It is found that in continuously deformed rock formations fully coupled rock bolts have only one axial stress peak. The position of the axial stress peak moves towards the far end of the bolts with increasing rock deformation. In blocky rock masses several axial stress peaks may appear in the rock bolt. The position of this kind of axial stress peak does not change during the entire loading process. For rock bolts in pullout tests, decoupling of the interface always occurs first at the loading point. The decoupling front moves towards the far end of the bolt with an increase in the applied pull load.

Jan 1, 2000