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By Molloy GR, Eaton RA

The crusher development programme for 7ft Super Extra Heavy Duty (SXHD) Symons cone crushers commenced in 1984. The main objective of the programme was to run the crushers at maxi- mum power for the full life of the liners. This would give a finer product sizing enabling grinding and flotation plant throughput to be maximised. The study was conducted along two basic lines of attack, the first main- taining an effective profile through the life of the liners, the second improv- ing the properties of the liners. It has been found that crusher liner life can be extended and crushing efficiency improved by modification of liner composition and profile.

Jan 1, 1988

In Australian collieries, solutions to the outburst problem must be implemented in a highly competitive environment which has a low tolerance on negative productivity effects. Solutions are only applicable if the overall viability of the operation remains sound. Minimum time must be spent on alleviation and control measures. This is favoured by simple geology, advanced warning and efficient alleviation and control procedures. Research requirements in support of this include 1. an improved means of predicting the nature and location of outburst zones ahead of the face and, 2. an improved means of measuring the effectiveness of gas drainage. For additional safety at the face, a means of continuously monitoring outburst proneness is required. In general, greater emphasis is required on improved instrumentation.

Jan 1, 1987

By Harris RW

Acoustic Emission structural integrity evaluation tests rely on the validity of the detected acoustic emission data and the ability of the practitioner to both analyse and interpret the data to make a correct decision on the future use of the structure tested. Unfortunately with acoustic emission surveillance testing, it is not possible to know that all the available data has been assessed property. The equipment sensitivity, threshold settings, and event capture capacity, when combined with the decision making ability of the operator in real time, make it very difficult to achieve reliable integrity evaluation. The main problem is to interpret the data and so any monitoring system should involve expert systems in conjunction with both acoustic emission and other operational monitoring data to maximise the utilisation of the large amounts of information now available from operating plants, mines and structures.

Jan 1, 1991

The overall mineral assemblage of the Broken Hill orebody is similar to that of a skarn. However unlike the classical skarns it does not represent contact metamorphism of pre-existing limestone beds. It is a stratiform accumulation of exhalative-sedimentary silica, sulphides, (Ca, Fe, Mn) silicates and carbonates, fluoride and phosphate that has later undergone regional metamorphism. The resulting development of coarse-grained quartz, sphalerite, galena, rhodonite, bustamite, mixed carbonates, fluorite, apatite and many minor phases has produced a sulphide-rich skarn- like mass that like many others of its kind, might best be referred to as a stratiform skarn. Recent investigations of occurrences of this type are showing that the incidence of concentrations of particular metamorphic minerals in and adjacent to such orebodies are closely related to bedding and to former sedimentary facies patterns. From this it appears that the mineral assemblages may be used to deduce not only the nature of the materials laid down in the beds, but also the physico-chemical conditions under which sedimentation took place. Several stratiform deposits, including Broken Hill, are used as examples to show that variations in these conditions may have a profound influence on the subsequent response of the rock to regional metamorphism and hence on the mineral assemblages that finally develop.

Jan 1, 1983

The design and construction of a 2.5 million tonne per annum ship unloading system at the PWCS export coal terminal in Newcastle, NSW, has further increased the flexibility and sophistication of Australia's largest coal export facility. The system comprises a new unloading wharf serviced by a self unloading vessel, conveyor stream and multi compartment ground level storage shed. Coal is reclaimed from this shed by the largest portal scraper ever installed under cover. The system also provides additional flexibility by receiving coal from the existing PWCS road receival to improve scheduling. The PWCS can now simultaneously handle 11 coal types and receive from rail, road and sea at almost 15000 tonnes per hour.

Jan 1, 1987

The patented "Epytensic" pump of Minnovation Ltd, a multiple piston pump, is used widely on shearer loaders and by partial high pressure watcr jet cutting strategically in relation to cutter picks not only improves cutting rates, but saves power and increases the life of gearboxes and picks, as well as improving dust suppression. The "Face Side Pump", also a piston pump, located on the ranging arm gearhead has advantages over gateroad pumps and shearer body pumps. The "Extraction Drum", hydraulic air mover system, linked with the above innovations and high pressure water, have further advantages in methane and dust removal. Some modifications providing these systems need workshop applications but most are possible underground with minimal changes to shearer profiles and advantages of minimising hosing, along with the other advantages stated.

Jan 1, 1991

By Thompson D, Burgess G. C

Subsequent to large scale trials in 1987, the installation of a submerged lance Sirosmelt furnace system was approved in late-1988 for the cupellation of retort bullion to dore silver. Commissioning work commenced in June 1990. During the process air is lanced into a molten slag bath contained in a cylindrical vessel to rapidly oxidise the granulated feed bullion from 15 - 25 per cent silver to rough dore grade. The process is now an integral part of the Precious Metals operation replacing the first stage reverberatory cupellation furnaces to achieve productivity improvements, lower silver inventory and increased silver Recovery.

Jan 1, 1992

By Walraven F, Knott G. G

Using a typical small logging instrument (Neltronic KPD), a natural gamma reference section for part of the Brockman Iron Formation and part of the Mt. McRae Shale has been established in the Newman area. This is compared with the stratigraphic type section of Trendall and Blockley (1968). Folding and faulting are recognised using natural gamma logs. Because of the confidence with which stratigraphic horizons can be identified, less expenditure on diamond and percussion drilling is required to confirm stratigraphic position. Using natural gamma logs as stratigraphic control the apparent thinning of the Banded Iron Formation during iron enrichment is Demonstrated.

Jan 1, 1973

The growth in the nickel market and the price increases predicted in 1970 have not mat-erialized. Several plants have been construct-ed, particularly to treat lateritic ores. A spectacular increase in cost of energy and the escalation of capital costs have led to severe economic difficulties on the part of many nickel producers. Several of the nickel prod-ucers joined together to form a Nickel Develop-ment Institute in 1984 with the prime objective of improving nickel markets. Most producers have taken exceptional action to cut overall costs as well as unit costs. Another organiz-ation made up of nickel producers, NiPERA, was established in 1980, to study and take action on problems of nickel in the environment and especially in the workplace.Ion exchange, and particularly continuous ion exchange, has been developed into a reli-able commercial unit operation in the last dec-ade. An example of how ion exchange combined with hydrogen reduction can be integrated into a Caron type reduction roast ammonium carbonate leach process for the recovery of nickel from laterites is discussed.

Jan 1, 1985

By Donchak P. J, Champion D. C, Fordham B. G, Domagala J

The Hodgkinson Province forms the northern part of the Tasman Orogen and contains the most extensive outcrops of Silurian - Devonian rocks in Queensland. Deep-water, marine siliciclastic sequences (mainly turbidites) dominate most of the province except near the western margin where mafic volcanics and fossiliferous limestones characterise much of the succession. It is difficult to apply normal stratigraphic mapping techniques to the Hodgkinson Province because of extensive stratal disruption by numerous thrust faults, the general lack of stratigraphic and structural markers, and the unfossiliferous nature of much of the succession. Nevertheless, several distinct units have been delineated although their internal stratigraphy or boundary or superpositional relationships are uncertain. Ordovician strata, as well as two major unconformities have been recognised in the western part of the province. Several models have been proposed to explain the evolution of the Hodgkinson Province. Although there is no general agreement most recent researchers favour an extensional tectonic regime.

Jan 1, 1990

The Burragorang Valley lies approx. 95 km by road south west of Sydney and some 35 km west of Camden. It is over 80 km in length and varies in width from 3 km to over 16 km. Geologically, the history of the Burragorang Valley is of interest. It was referred to by early geographers and N.R.M.A. booklets as the largest sunken valley in Australia. This description is incorrect as it is a water worn valley formed by the dissection of an uplift in the south western portion of the large Sydney Sedimentary Basin. Ages2 ago there extended right across the Blue Mountains, a continuous tableland into which the Nattai, Wollondilly and Cox's Rivers have carved out the formation of the Burragorang. This dissection together with other valleys such as the Megalong, Jamieson and Grose, formed part of the eastward drainage pattern of the uplifting tableland into the Pacific ocean. The lapse of time since the streams in the Burragorang began their work of erosion can

Jan 1, 1976

By Denisov GA

Conventional processes for disintegration of ores are characterised by low selectivity and cause damage to the components of their structure. It affects their liberation and recovery which are connected also with the inevitable formation of extreme fines. In the world practice recently came into view 4 trend to grinding of materials within a thick layer (in a bed layer), which provides a substantial selectivity of liberation, for example, of kimberlite. The degree of diamond preservation in the final product is highly increased. However, this method causes a considerable overgrinding of material. A new method of intralayer vibro-impulse breaking of materials providing an easily adjusted force acting at the layer and timely removal of product size grains from the grinding chamber has been developed in Russia.

Jan 1, 1993

By Quast K. B

Laboratory batch rod and ball milling tests were conducted on samples of Heavy Medium Separator (HMS) sinks from Renison Tin Limited. The product size distributions for this heterogeneous material were very different to similarly sized homogenous material previously reported by the authors. The effects of pulp density on product size distributions were only evident at pulp densities greater than 80 per cent solids. At high solids density, the major weight distribution product peak fell and broadened indicating less efficient breakage, particularly for rod milling. Tin distribution in the ground products was also affected by pUlp density, and there was always less cumulative per cent tin than cumulative per cent weight, ie there was no tendency for cassiterite to slime down to 10/lm.

Jan 1, 1995

By Kuruppu M

Geotechnical design plays a key role in mine design. A proper geotechnical design provides a safe working environment and facilitates efficient mining operation. There are mainly three design approaches: (i) judgmental, based on observational and experiential facts, (ii) empirical, based on empirical design formulae; and (iii) analytical, incorporating numerical analysis. Most design applications are based on the design methods one and two as mentioned earlier. However, complexities arise in deep underground mining operations and deep open pit mines. These complexities and difficult geological environment introduce more uncertainties and simple empirical formulae would not be adequate as a design tool. These situations require numerical modelling and analysis of the design problems including interpretation of the results obtained from the analysis. There are several tools available for performing the numerical modelling and analysis. A brief review of the available tools is provided. The authors selected ANSYS (a general purpose finite element analysis tool) for use in mining geomechanics and geotechnical design. This paper includes several examples demonstrating the applicability of this software in designing mining structures. The authors hope that the design examples will demonstrate the use of the numerical modelling and analysis applications in excavation design.

Jan 1, 1995

By Williams P. A

Tailings dams constructed by the upstream method have traditionally been built using the sand fraction of the tailings, which has automatically provided a relatively permeable embankment material, and helped provide the necessary drainage conditions which are a pre-requisite for safe and stable dam construction using this method. This paper discusses some recent trends which have resulted in proposals to use impermeable material in place of the sand fraction as the embankment material, both for the starter dam, and subsequent lifts. The consequences of these types of decisions on the overall stability of the dam are illustrated, and the need for continued monitoring of pore pressures in the tailings as the dam is raised is emphasised.

Jan 1, 1992

Tyre cost at Mount Morgan Limited had been 24% of the truck operating cost. Comprehensive tyre testing resulted in a reduction in tyre costs of about one third. A record of the evaluation techniques may enable the selection of tyres that are most suited to particular conditions. Rubber characteristics, rubber quantity, tyre design, road conditions, dump conditions and inflation pressure were found to be sig- nificant variables. Measurements of tyre temperatures at the breaker strip were used to select the tyre design and inflation pressure required for Mount Morgan Limited's conditions. Relugging of tyres was discontinued as a result of tyre testing.

Jan 1, 1974

By C Yates, S Jobling, Z Y. Yang

The current trend in the UK towards the adoption of retreat longwall mining methods and the associated rapid development of the access drivages have exacerbated the environmental conditions experienced within these workings. There is a recognised need to improve the efficiency of the design and operation of mine ventilation systems in order to maintain an adequate environment and climate within these workings. Any improvement achieved in the quality, quantity and control of the delivered ventilation will assist in the provision of improved gas and dust dilution and climatic control. The paper presents an analysis of the psychrometric data recorded during the execution of a series of comprehensive climatic surveys conducted within two representative deep underground UK coal workings. The surveys were performed across two high production retreat longwall districts within UK Coal Ltd collieries. The surveys employed intrinsically safe psychrometric transducers and digital data-loggers to collect a continuous record of the mine climate over designated weekday production and weekend non-production periods. The transducers and data-logging units are capable of simultaneously measuring and digitally recording changes in the dry bulb temperature and the relative humidity at regular time intervals for extended periods of time.

Jan 1, 2005

By Hughson B

A multi-wire borehole instrumentation system was used to monitor strata movement caused by a retreating longwall face at the Ellalong Colliery, situated in the Lower Hunter Valley in New South Wales, Mechanical anchors were placed at various horizons in the borehole which extended from the surface to the extracted coal seam. The vertical movement of the anchors was monitored during mining. The zone of major disturbance was confined to 13 times the extracted seam thickness above the seam. The average dilation of strata in this zone was 6 per cent. Above the caving zone, the tensile strain was under 2mn/m except at one location, where it was `xmi/m. The subsidence trough under dynamic conditions was flatter than that under stationary conditions. The subsidence also depended upon the extent of strata fragmentation prior to undermining.

Jan 1, 1987

By Wilson PH

A research programme sponsored through the Australian Mineral Industries Research Association investigated two aspects of mine aerodynamics on model scale. These were aero- dynamic losses in (a) shaft/airway intersections and (b) losses created by mine cages moving in a combined haulage/ventilation shaft. The shaft/airway intersections studied included base and intermediate levels for both upcast and downcast. shafts, with one to four rectangular airways intersecting a circular shaft. Changes in intersection geometry were limited to the installation of 45¦ conical brow cutoffs of varying size and the addition of simple flow control devices. The relative air- flows between the airways and the downstream shaft were varied over a range employed in Australian mining practice. In general, experiments revealed that a small brow cutoff was significantly better than none at all, and a simple device such as a cone can reduce losses and improve flow stability at an intersection. The mine cage studies determined the effect on aerodynamic loss of cage area blockage, height/length ratio, openings in cage walls and surface roughness due to external structural members. The results show that in a combined haul- age/ventilation shaft, when the relative air

Jan 1, 1978

Efforts to stabilize international markets in commodities have gradually intensified during the course of this century in keeping with the grow- ing complexity and interdependence of the world economy and the increasing involvement of government in economic activity. Successive Australian Governments have con- sistently supported the concept of commodity agreements and arrangements in an effort to lessen short term fluctuations in price and to moderate the boom/bust conditions which tend to charac- terize production and trade in many commodities. The objective is to stabilize price at a level which equates supply and demand over the life of the arrangement. Such action involves a degree of market inter- vention and government involvement in the inter- national trade in the commodity concerned; the acceptability and desire to foster such arrange- ments varies from country to country depending upon attitudes to market intervention and man- agement. However attitudes, even among those opposing commodity agreements, have under- gone a major reversal in this century. Before the first world war, such intervention as existed almost entirely involved the physical producers. There was almost no government involvement and at that level most regarded commodity agree- ments as neither desirable nor practical. However government regulation of such activities as pro- duction and marketing of food during World War I, coupled with post-war shortages, followed by overproduction and the crash in prices during the Great Depression, stimulated producer gov- ernment interest in commodity market regulation. Consumer governments took a little longer and with a few exceptions, it was not until the post World War II period, that the fear of shortages of basic commodities brought some consumer countries to accept the concept.

Jan 1, 1978