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By Linying W

Entropy is an important concept both in natural and social sciences.Considering the preparatory process of the earthquakes as an open system, in view of basic ideas of the Theory of the Dissipative Structure, the seis-mological Entropy is introduced as an order parame-ter, describing the scale of order associated with the earthquake distribution in time, space and mag-nitude. The features of evolution of seismic acti-vities before and after the large earthquakes have been studied by using the seismological entropy.The preliminary results show that the seismological entropy in certain region decreases as the large earthquake is approaching, it means that the distri-bution of earthquakes has turned gradually in order from disorder.It is expectation that the application of the Principle of Entropy in seismological research will deepen the understanding of the physical process of earthquake preparation. Meanwhile, it will also offer some enlightements in studying mitigation of seismic hazard as well as earthquake prediction.

Jan 1, 1990

By Bogar D. V

Often dewatering of coal tailings is inhibited by the presence of clays, making it difficult to obtain a high concentration, handleable coal tailings. The net result can be a low concentration, chocolate mousse-like tailings which poses significant sedimentation problems in a tailings dam and represents a significant environmental problem. This paper examines the coal tailings from a Hunter Valley colliery where the tailings properties are influenced significantly by the presence of montmorillonite clay. The influence of the calcium ion on the rheology and sedimentation/compression behaviour of coal tailings . containing montmorillonite already dispersed in water was investigated and revealed that very little improvement in the properties is achieved through the coagulation. The preliminary investigations also indicated that the properties of the tailings were dominated by the presence of the montmorillonite clay. Thus investigations were carried out on the clay alone in water. Investigations into the effect of dispersing samples of the clay alone in water and then coagulating with calcium compared with dispersing the clay directly into calcium ion solutions at the same calcium concentration showed huge improvements in the rheology, compressibility, sedimentation rates and sediment solids concentrations for the second dispersion method, which can be called controlled dispersion. The sediment volume fraction solids improved by more than a factor of two by controlling the dispersion of the clay. The reason for the improved properties lies in the suppression of the initial swelling of the clay, which is initially in the sodium form, thus maintaining the parallel orientation of the platelets that is present before wetting. While swelling is being suppressed, ion exchange occurs with the calcium which results in permanent swelling suppression. In the uncontrolled dispersion case where swelling is uninhibited, the clay is allowed to break up and despite the powerful coagulating nature of the calcium ion, the random orientation of the high aspect ratio clay platelets inhibits effective coagulation. Results indicate that the initial electrolyte concentration of the washwater in a coal washery is the critical factor controlling the dewaterability of clay tailings and the handleability of the dewatered product rather than the actual act of coagulating with the calcium ion. The results presented are of clear practical significance and indicate how coal tailings problems where clay dominates the rheology can be improved considerably by knowledge of the surface chemistry.

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

The Coal Corporation of New Zealand Ltd (CoalCorp) is the largest coal producer in New Zealand, with extensive properties in both the North and South Islands. CoalCorp's North Island operations are kilcmetres to the south of Auckland. opencasts, are located in the catchment wildlife, historical and scenic values. in this catchment is the single most mining operations. centred on Huntly, a town some 80 Five coal mines, four of which are of Lake Waahi, a lake with significant The discharges of mine lodgement water important environmental constraint on Throughout New Zealand the use of water is controlled by a statute called the Water and Soil Conservation Act 1967. All industrial water users are required to hold Water Rights, which are in effect licences to take, use, dam, divert or discharge water. Water Rights are obtained through a legally defined process and any potentially affected party has the per to object to their granting. A special tribunal hears the evidence for and against an application, and issues its decision, which is reviewable in a higher court on Appeal. Rights, if granted, are issued subject to conditions and, in the case of mining discharges, limits would be set on flaw rate, suspended solids concentrations, turbidity, pH and the concentrations of any potential toxicants. This paper presents a case study of an integrated, catchment wide water management plan for Lake Waahi, that was prepared by the author, and others while the author was in the employ of CoalCorp, and its predecessor, State Coal Mines. The author is grateful to CoalCorp for their permission to submit this paper.

Jan 1, 1988

By Propser M, Szekely J

Flow maldistribution in the iron blast furnace has been studied analytically by the use of the vectorial form of the Ergun equation and experimentally via packed columns and a cold model of a blast furnace. Experimental results are presented showing the effect on fluid flow patterns of the following types of nonuniformities in a packed bed: the increased voidage at the wall ("wall effect"), the decreased voidage at the interface between layers of materials with different sizes and shapes, and the differences in resistance to flow of bulk regions of a column with different sizes and shapes. The proposed theory is applied to the calculation of fluid flow patterns for these nonuniformities. Velocity profiles, as calculated from these flow patterns, were found to agree reasonably well with experimental measurements obtained via hot wire anemometry techniques for laboratory scale packed columns. Calculated fluid flow patterns are presented for blast furnace burdens which show how flow patterns are affected by (a) coke segregation and (b) the relative differences in resistance to flow between coke and oxide pellet layers. For the cold model study, calculated flow patterns are presented based on photographs of a given burden distribution. The velocity profiles calculated from these flow patterns were found to agree reasonably well with the velocity profiles measured from the cold Model.

Jan 1, 1975

The organization of this department is as shown in the following chart:Chief Mechanical EngineerPowerGenerationWorkshopsNew ConstructionMaintenanceTransportCommunity ServicesMineMillSmelterDesign and OfficeOrganizationThe functions of each section will be described separately.MAINTENANCE UNDERGROUND DEPARTMENTThis section covers all mechanical equipment underground as well as fans and winders on the surface, the headframes, and conveyors from the shaft to the crude ore bins. As has been descrIbed, No. 2 Ore shaft was opened up to the surface and a new headframe and receiving bins were erected, and when the new lead crushing and screening plant was constructed and ready for operation, the rope sheaves...

Jan 1, 1953

The process and control technologies incorporated into the coal preparation plant at Newlands were to be used for the first time in Australia. The commissioning organisation and procedures were set up on the basis that commissioning personnel, while being competent, would be unfamiliar with the equipment. In addition the commissioning process would have to be completed quickly. The organisation coped with all of these problems and more.

Jan 1, 1986

By Howell IJ, Kirsopp R

In June/July 1981 Mount Isa Mines Limited was confronted with a crisis situation in the crushing operation of the Lead/Zinc and Copper Concentrators. Three crusher mainframes developed serious cracks in the upper rim area. The type of cracking indicated that major failure of these mainframes could be imminent. Operational crushers could not be sensibly inspected and it was therefore assumed that more than three mainframes were seriously cracked. The crisis was averted as described in the following text.

Jan 1, 1978

Key incompatible element ratios for metabasalts from the Early Permian Croisilles and Patuki Volcanics, South Island, New Zealand, provide constraints on the tectonic environment in which their precursor ophiolitic protolith formed. Two geochemically distinct metabasalt suites are recognised among both the Croisilles and Patuki rocks. Metabasalts from one suite exhibit the geochemical signatures of depleted tholeiites from oceanic spreading ridges (N-type MORB) or spreading centres in evolved back-arc basins. These N-type tholeiites show high Zr/Nb ratios (Zr/Nb = 37-62) and are depleted in light rare earth elements (LREE)((La/Y)N

Jan 1, 1987

By Armstrong M

Two methods of Monte-Carlo simulations, one suggested by Matheron (1972) and the other by Rudenno (1983), have been tested for simulating coal deposits. To do this 2160 values of ash percentages were simulated using 60 known data points in a two dimensional grid, 20 m x 40 m. 1L is found that while both methods conserve the mean of the known distribution in the results of the simulations, only the first method reproduces the spatial covariance (i.e. the variogram), of the experimental data. The results show that for simulation of regionalized variables only the first method tested yields the desired results.

Jan 1, 1985

Reconnaissance geochemical exploration in the vicinity of low angle detachment faults which bound the core of the Paparoa metamorphic core complex yielded Au up to 14 ppm, with 35% of greywacke, granitoid and quartz vein samples in the northern range exceeding the 0.01 ppm detection limit. Au is associated with Ag, As, Sb and Cu anomalies consistent with epithermal-type mineralisation. The Ag and Cu anomalies also distinguish this mineralisation from older, mesothermal Au deposits widespread in the Ordovician 'slate belt' greywackes, which comprise much of the upper plate of the core complex. Baryte, molybdenite, fluorite and stratiform U mineralisation in the northern Paparoa Range may also be related to hydrothermal activity along the detachment fault zones.

Jan 1, 1995

By Yang RL, Bailey ML

During overburden blasting operations in dragline pits, coal edge losses along the lowwall edge of the new pit are often experienced. In tonnage terms, losses can be significant. With the thick seams at Callide Mine, 20,000 tonnes of coal can be lost along a 600 metre pit. In addition to the immediate dollar value of the coal, replacement of this coal (from which overburden has been removed) will be from higher ratio and higher cost pits in the future. Unit costs of production for the remainder of the coal uncovered in the current pit increase. Experiments involving variation of blasthole inclination and/or amount of standoff on the front row of blastholes have given no significant improvement in the coal edge loss control.

Jan 1, 1988

Hydraulic backfill is generally retained in stopes using permeable barricades. Mitchell et al (1975), Mitchell (1992) and Grice (1989) have shown that under normal drainage conditions, barricades experience low levels of loading. Cowling et al (1988) have also shown that barricades are susceptible to piping failures if excess water has ponded on the upper backfill surface and if leakage of backfill from the barricades has occurred. During 1997, six hydraulic backfill barricades failed in four different Australian mines. Fortunately, in each case, the quantity of backfill slurry released was small, and no injuries to personnel nor damage occurred. Detailed investigation of two of the incidents showed that the primary cause of failure could be attributed to the delivery of excess quantities of transport water from the low-density slurry. For each of the incidents investigated there was evidence of the development of piping failures, which resulted in hydrostatic loading conditions on the barricades from the ponded water on the upper backfill surface. The circular failure surfaces in the barricades were characteristic of the application of point loading conditions. This paper discusses the circumstances that led to these incidents and analyses the modes of failure. The standards for the safe operating of hydraulic backfill systems are reviewed along with requirements for ongoing management and control. The design requirements of barricade construction are analysed and some appropriate guidelines introduced.

Jan 1, 1998

With the recent wider introduction of friction hoists of the Koepe type. for winding from depths of more than 3000 feet it has been found that failure by fatigue is the most common form of rope deterioration. Large numbers of wire breaks occur near the centre of the rope cross-section and it is difficult to detect these with certainty using the preferred d.c. magnetic test. For best results with conventional search coils their dimen- sions should be related to the typical wire break field pattern surrounding the longitudionally magnetised rope. The field of a broken wire was experimentally determined, using a Polish type MD6 Defectograph wire rope testing magnet and a short prepared length of rope with a movable simulated broken wire. The external field distortion perpendicular to the rope was measured by means of a gaussmeter and Hall probe. The advantages of this method are that terrestial magnetism and inherent rope "noise" have no effect on the results.

Jan 1, 1971

By S Planeta

The use of explosives in underground mining has its drawbacks, particularly in the case of thin or narrow vein type deposits. Due to that, there is a need to develop more discriminative and safe rock-breaking technologies. Mechanical rock splitting seems to be one of the most promising avenues in this respect. This paper describes briefly principles and features of radial-axial splitters. It reviews a feasibility study done to evaluate a potential of this technology in selective mining. It was intended to compare productivity and cost of ædrill-splitÆ mining with conventional cut-and-fill method. Hypotheses and assumptions adopted, methodology used and the obtained results are presented and discussed. The study has confirmed an interesting potential of radial-axial splitters in mining thin and narrow vein deposits. In conclusion, it is stressed however, that it will take more R&D work to corroborate the results obtained. Some suggestions concerning future research in this field are also given.

Jan 1, 2003

The smelting operation associated with the production of aluminium has a voracious appetite for high grade carbon materials. Within the technical parameters of the Hall-Heroult process, the reduction of alumina to one tonne of aluminium results in the consumption of nearly 0.5 tonne of carbon at the anode of an electrolytic cell. This paper reviews the role of carbon and the basic quality requirements of carbon products in the production of aluminium, discusses the effects of certain physical and chemical specifications on smelting and related operations, and examines recent trends in the quality of these raw materials.

Jan 1, 1977

By Montagnon P, Dagois G

The use of activated carbon for gold recovery has been known for years, but came industrially on stream since the years seventies.Despite several years of experience, the criteria for selecting a carbon have not been clearly determined so far.This paper will try to highlight the user through his experience, on the most important factors which should affect his decision.We will develop:- Physical characteristics - Adsorption characteristicsand try to show that slight variations on these characteristics may have important consequences on the plant design and profitability.

Jan 1, 1984

By Durucan S

The southern Attiki peninsula is a very interesting area from an environmental point of view. The port and the city of Lavrio is situated at the east coast of the peninsula with about 10 000 inhabitants and there are also a few villages in the vicinity. The south-eastern part of the peninsula hosts the famous Lavrio mines which exploited the silver bearing orebodies of the area for more than 25 centuries. As a result, soils around the city of Lavrio are polluted with high heavy metal loads. The area is also of archaeological interest, as there are well preserved remnants of ancient mining and processing plants and archaeological sites. Soil samples collected from an area of approximately 120 km2 around Lavrio were analysed for their metal contents and the spatial distribution of the concentrations of ten selected elements were estimated from these data sets. The spatial data analysis and transformation capabilities of Geographic Information Systems, combined with extensive mining and geological data, helped the authors to identify the extent and causes of metal pollution around Lavrio.

Jan 1, 1995

By R Lastra

Applied mineralogy involves conducting investigations on ores, minerals and materials to solve problems encountered in mining, metallurgy, processing, industrial minerals, environment, health and other fields. The investigations are performed to determine the mineral behaviours during processing by using every mineral and ore characterisation technique and appropriate instruments. As the field is young, new techniques and instruments are still being developed. This paper attempts to convey the scope of the field by:describing the capabilities of the respective research instruments for determining mineral characteristics, summarising investigations of gold as an example of applied mineralogy studies of precious metals, andpresenting a case history where applied mineralogists worked closely with mineral processing engineers on a base metal ore and mill products to help the engineers optimise their processes for maximum recoveries.

Jan 1, 2008

By Muchi I

To clarify the characteristics of non-uniform flow of gas through layered burdens of ore and coke, flow equations of continuity and motion were solved numerically taking account of the geometrical effect of a bed. The results are compared with that predicted by an approximate solution. A mathematical-kinetic model for determining the distributions of process variables over the region from the top to the melting level of blast furnace with the horizontal or the inclined layers of burdens is developed in consideration of the uneven gas flow. By the use of this model, the longitudinal and the radial distributions of process variables in an existing blast furnace in Japan were calculated with the aid of a digital computer. Computed results show that the process variables and the melting level change remarkably over the cross-section of the furnace and that the patterns of these distributions are similar to the results observed by other investigators.

Jan 1, 1975