Search Documents

By T Baumgartl, B Richards

Covers on waste rock and tailings remain the primary choice for closure planning where the purpose is to create an environment where water ingress into reactive material can be controlled and/or prevented. In semi-arid and arid environments, dry cover systems are the preferred option with the design intention to absorb rainfall and to prevent deep drainage. Although the average amount of rain typical for semi-arid environments is relatively low and evaporative demand is high, the seasonal and annual distribution may vary greatly. Rocky substrates are often the only choice for the construction of covers due to economic constraints or availability of suitable materials. While the water holding capacity may be suitable for the application of a dry cover design in arid and semi-arid climates, some of these covers bear the risk of preferential water flow when rain events are intensive or occurring at high frequency. The objective of this presentation is to demonstrate the occurrence of preferential flow through rock containing dry cover systems. A regional classification for the applicability of dry covers is attempted to delineate those regions of Australia where the characteristic of the rainfall pattern increases the risk of failure for dry cover designs. CITATION:Baumgartl, T and Richards, B, 2016. Rainfall patterns rather than climate classification control cover design for closure, in Proceedings Life-of-Mine 2016 Conference, pp 89–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

The New South Wales coal industry is a highly mechanised well organised industry which has developed from an annual production of slightly less than 13 million tons in 1950 to over 33 million tons in 1969. Although continuous miners were not introduced into the mines until 1950, by June 1969 the percentage of coal won by these units was 87.3. The paper describes mining conditions in the various coalfields of the State, their complexities and problems and how these have been dealt with. The introduction of fully mechanised longwall faces has presented a challenge which has been accepted and descriptions of systems in use are discussed. Major expansion of the industry is anticipated to meet the requirements of the growing Australian steel industry, for local power generation and to meet the increasing demands of overseas markets.

Jan 1, 1980

The selection of an appropriate mining method should take into account the geometry of the deposit and its physical properties. Other factors which assist in the determination are the requirements for flexibility in the mining process, minimisation of risk factors and maximising the financial return. Several established mining methods exist which can encompass the requirements to deliver the optimum mining method, this can be in both an underground or open cut environment. The objective is to outline these methods and where they can be applied in a mining project.

Jan 1, 1997

By Fukuichi K, Matsukawa H, Nakagawa M

The Myojin Tunnel, located on the Shikoku Expressway being constructed by the Japan Highway Public Corporation, is 3,770 m long with a cross sectional area of 80 m2. Kajima Corporation, the contractor for the northern construction section of this tunnel, adopted here its newly developed "mini-bench" method of excavation. The objectives of this method were 1. to be able to perform all tunnelling operations using the whole cross sectional area of the tunnel under any ground conditions, and 2. to be able to vary the length of the mini-bench within the range of 0 to 7 m according to ground conditions. In order to achieve these objectives, original, sophisticated equipment was developed and employed in the work. One of the newly developed machines is a special jumbo, a hydraulic crawler jumbo with five rotary type booms. This machine is capable of accommodating variation in the length of the mini-bench accompanying changes in ground conditions and is equipped with a special mechanism by which the positions of the booms can be controlled by means of hydraulic cylinders. Also developed was a shotcrete robot for use with the mini-bench method which has the control board near the shotcrete nozzle for close control of application.

Jan 1, 1987

By Crosby N. R

The design of mine openings and the assessment of their reserve are processes ihicl, require the routine manipulation of considerable amounts of data. A number of computer programs have been assembled to operate in a mini computer in order to provide some mechanical assistance for these processes. The system responds to plain language commands. which allows mining engineers to compute the reserves for a number of possible mining outlines, on an interactive basis. Methods of numerical analysis were used in preference to statistical or qeostatistical techniques.

Jan 1, 1977

By Yan D. S

The removal of antimony from a refractory gold-bearing stibnite ore by roasting and selective chlorinating roasting was investigated. The influence of roasting temperature, roasting time, roasting atmosphere and type and amount of chlorinating agents on antimony removal were studied. The laboratory studies carried out included roasting tests of 4 g samples in a laboratory rotary kiln, followed by 400 g samples roasted in a fluidised bed. The test results revealed that antimony was efficiently removed by roasting at temperatures over 800¦C in a nitrogen atmosphere. The most efficient volatilisation of antimony was achieved with the addition of ferric chloride at temperatures between 350-600¦C.

Jan 1, 1995

By Artmont G. J, Palmer K

Alluvial gold is an ideal exploration tracer to bedrock source and indicator of bedrock mineralisation style because (i) gold occurs in a wide range of deposit types, (ii) primary composition is sensitive to style of mineralisation, and (iii) it is a heavy resistate mineral that is readily preserved and easily sampled. In regional exploration of the Central Ranges of Irian Jaya, alluvial gold mineralogy has been applied to maximise the information return from panned concentrate sampling and to focus exploration effort. Primary gold is a solid solution of Au+Ag¦Cu¦Hg, ¦ trace Pd, Te, and Sb. In general Ag¦Hg increase and Cu decreases with inferred decreasing temperature of formation, and gold from particular mineralisation styles has signature compositions that can be used as indicators of bedrock mineralisation type. Furthermore, the abundance of alluvial gold is an indicator of the economic potential of a catchment. The convergent continental-oceanic plate geology of the Central Ranges is conducive to a wide range of mineralisation styles. Mineralogy of gold in ophiolite, skarn, porphyry, mesothermal vein and possible VHMS environments is characterised from alluvial and bedrock samples, and the use of gold mineralogy in prospecting at regional scale through prospect definition to drilling is demonstrated.

Jan 1, 1995

By Ho D, Yang J

The ready availability of powerful desktop workstations, which combine 3D real-time graphics and processing speed better than that of supercomputers of a few years ago, now allows the cost-effective solution of real world geomechanics and underground mining strength simulations. The inclusion of geotechnical factors such as rock joints and porous flow on strength and stability are discussed together with the range of available deformation and failure models for soil, rock and concrete. This paper describes the capabilities provided by finite element graphics and analysis software for modelling and sequential investigation of both excavation and lining, or rock bolting, construction sequences. Examples of the use of finite element models in mining are also included in the paper, together with a discussion of the required people, software and computer hardware resources required to achieve timely and productive results.

Jan 1, 1995

Knowledge of the hydrogeological setting of a mine forms an integral part of a mining operation. Groundwater impacts, initially, on mine feasibility. Then, on commencement of mining, it interacts on the operational components of dewatering, water supply, tailings leachates, mine wall stability, stormwater run-off, water disposal, impact on regional environment and mine closure planning. The recording of hydrogeological information is frequently overlooked during resource and reserve definition as well as during the course of mining when prime opportunity exists for the collection and collation of this data. In recent times, the exclusion of hydrogeological data has been exacerbated by use of high air pressure drill rigs that exclude water inflow. The recording of water data has been further inhibited by the use of computer coded drill logs that do not include the site geologistÆs or drillerÆs comments on drilling problems and observations associated with groundwater intersections. Geologists now infrequently directly supervise drill rigs, but visit the rig only intermittently to evaluate drilling progress. They do not see first hand drill performance characteristics at water make zones. Drill cuttings, as drill chips and cores, are now mostly logged away from the drill site so that wet sample locations, visual water flow evidence and verbal comments from the driller are not recorded. As a result, mine geologists now do not direct adequate attention to the delineation of lithologies and structures that store and transmit water. This paper provides examples of water sighting and recording techniques applicable to a mining operation. Examples are also provided where hydrogeological conditions have been disregarded with serious impact on the progress of mining. The recording of hydrogeological data should be maintained and formatted by the site geologists into a useful database for review as and when required by specialists in hydrogeology, geotechnical and mining engineering and the environment. The information can be coded by the site geologist for inclusion into the mine database. A groundwater dataset, compiled during the progress of field investigations, will save the considerable cost of re-drilling and hole re-entry testing which would otherwise be required to provide base level hydrogeological information required for progress of mining. Apart from working mine use, a hydrogeological dataset is a necessary component for planning mining closure and mine legacy conditions.

Jan 1, 2003

By Cox LT

A short term tyre study of trucks operating in a multiple pit surface coal mine showed significant potential for cost savings. The tyre study, conducted on-site over a three months period covered a mixed fleet of 18 trucks ranging from 27 tonne to 77 tonne capacity operating on overburden removal, coal haulage and watering duties. Some existing plant history records and a variety of tyre related measurements during the course of the study allowed the current state of tyre operations to be quantified. Specific attention was given to determining ger>ral trends from historical records and conducting detailed studies of individual lug damage, pressure monitoring and rectification, as well as tyre maintenance procedures. Important haul road parameters including camber, gradient, curve radii and superelevation, constructional materials and surface clean-up were appraised for their influence on tyre wear. Recommendations for achieving long term cost effective tyre utilisation included increased tyre maintenance, personnel development, compliance with haul road design parameters and more stringent clean-up Procedures.

Jan 1, 1982

LESLIE BRADFORD GOLDEN JUBILEE ORATION "Not only a metallurgist but a scientist of the highest order" Leslie Bradford and the Australian Metallurgical Industry

Jan 1, 1987

By Blight P

There is today widespread concern about the future of the mining industry. In attempting to understand the underlying causes the paper probes in some detail, the long term structural changes affecting growth of metal demand and the development of excess mineral supply capacity. This examination reveals an industry characterised by an unfavourable combination of high barriers to exit and low entry barriers. While rising entry barriers are expected to herald some improvement in the profitability of mining over the next decade, this adjustment is likely to be slow and will require a more economically rational assessment of the industry by corporations and governments Alike.

Jan 1, 1986

Coal is a very versatile resource, having variable characteristics and having potential for a wide variety of mar- kets. Australia has extensive deposits of black coal, although they are concentrated mainly in Eastern Australia. Assessments of the currently known reserves are related to the qualities of these reserves. Markets available to black coal fall into the broad groupings of metallurgical, fuel, conversion and miscellaneous markets and the requirements of these markets are related to coal characteristics. Market trends in Australia and on the export market are discussed and projected forward. By the end of this century Australian consumption of black coal could well be 100 million tonnes per annum, and, in the absence of any export restriction, a similar amount is likely to be exported. Currently defined black coal resources in Australia will last at least 600 years at these projected rates of consumption. Although the position appears satisfactory in considering the projected life of the black coal resources, there is a serious lack of detailed information on reserves, mining and preparation yields, quality and possible environmental restrictions. Action is required on three parallel courses: (1) a consistent, systematic and extensive survey of current coal resources in Australia, (2) accelerated exploration activity to define poorly prospected and potential areas, and (3) regular updating and extension of the knowledge of Australia's coal resources. This information would be of tremendous assistance for the formulation of a national energy policy on coal.

Jan 1, 1975

Coal seam methane (CSM) is an æunconventionalÆ gas resource that is becoming an important energy resource for Australia, especially along the eastern seaboard. It has been conventionally believed that methane in high rank coals was exclusively derived from thermocatalytic processes during decomposition of coal at elevated temperatures. However, recent re-interpretations of gas composition and isotope data have indicated that microbial methane generation may be one of the main processes responsible for the accumulation of commercially producible methane in some coals. In low rank (æbrownÆ and sub-bituminous) coals, methane (CH4) is mainly generated by microbial activity at low temperatures. The amount of this biogenic gas generated and accumulated in low rank coals depends largely on the rate of burial and depth. Most low rank coals are æunder-saturatedÆ with respect to their maximum gas sorption capacity. In contrast, high rank coals may be highly saturated due to extensive gas generation from both thermogenic and secondary biogenic processes. However, in basins where secondary biogenic gases have not replenished the thermogenic gas lost during basin uplift, the coals will be æunder-saturatedÆ. In many basins around the world, high CSM producing zones appear to contain secondary biogenic CH4 generated by microbes transported in meteoric water recharge through permeable coal seams. Biogenic CH4 generation requires the activity of a consortium of anaerobic respiring microorganisms, fermentative bacteria and acetogenic bacteria to break down complex organic molecules to simpler molecules having one or two carbon atoms, which enables methanogenic archaea to generate CH4. The two main methanogenic pathways in the generation of secondary biogenic gas from coal are aceticlastic reaction and carbon dioxide (CO2) reduction. In eastern Australian coals CO2 reduction appears to be the main process. The types of microbes that are directly involved in these processes are unknown because they have not yet been isolated from the coal seams. The CSIRO is currently investigating the processes of biogenic gas generation in Australian coals. Potential may exist to introduce appropriate microbes into deep coal seams to enhance methane saturation levels, gas sorption capacities and permeabilities.

Jan 1, 2004

By Loo C. E

Thirty two polyacrylamide flocculant samples were selected from the wide range offered to the Australian coal industry. An extensive test program was conducted to consider the properties of the flocculants, the substrates, the process conditions and the water chemistry encountered in coal preparation plants. The study indicated that flocculants with molecular weights of 12 to 14 million and degree of hydrolysis around 40% gave the best "average" performance over a wide range of process conditions. The pick-up and filtration of fine coal was demonstrated on a pilot scale to be a critical function of flocculant properties. This study also showed that the agitation intensity during flocculation was a critical parameter in determining the settling rate of the slurry and the clarity of the resulting supernatant. An electronic meter to measure agitation intensity was designed, constructed and tested to demonstrate how, for the first time, laboratory results can be implemented in operating plants.

Jan 1, 1989

By Johnson N. W, Munro P. D, Pease J. D

The Lead/Zinc Concentrator of Mount Isa Mines Limited processes complex fine grained ore from the Isa and Hilton silver-lead-zinc orebodies, producing lead concentrate, zinc concentrate and (until 1996) a low-grade middlings (LGM or bulk) conc

Jan 1, 1997

The Teutonic Bore deposit lies in a major greenstone belt within the Archaean Yilgarn craton of Western Australia. It occurs towards the base of a suite of tholeiitic basalts, some 100 m above a felsic volcanic pile of rhyolitic composition. Sediments comprise a minor, albeit important, percentage of the mine stratigraphy.The deposit consists of a single, steeply dipping lens of massive sulphides totalling 1.4 million tonnes grading 4.16 per cent Cu, 16.4 per cent Zn, 1.22 per cent Pb and 203 g/t Ag. In addition, cross cutting "stringer" mineralisation in the footwall contributes a further 0.75 million tonnes at 2.38 per cent Cu, 1.92 per cent Zn and 52 g/t Ag to the mining reserves. Principal primary sulphides in massive and disseminated mineralisation are sphalerite, pyrite, chalcopyrite and galena, while minor amounts of arsenopyrite and argentiferous tetrahedrite are also present. Weathering has affected the primary mineralogy down to at least 90 m, resulting in a strongly leached oxide profile to about 85 m, overlying a thin, erratic zone of chalcocite supergene enrichment.Lateral metal zoning is marked both in massive sulphide and stringer mineralisation, with Cu/Zn ratios decreasing away from the centre of the orebody. Alteration is well developed in association with footwall stringer mineralisation, changing from a central Fe-Mg carbonate, chlorite and silica alteration zone below the massive sulphides to an outer halo of sericitisation. The spatial distribution of these minerals is patchy. Geochemically, the footwall alteration zone is characterised by central Cao, Na20 and Sr depletion (with less regular enrichment of SiO2 , Fe and MgO), surrounded by a peripheral zone of K20 enrichment.Evidence supports a classic volcanic-exhalative origin, involving submarine discharge on the flanks of a rhyolitic dome and accumulation of the massive sulphides in a local palaeotopographic depression. The sulphides overlie their feeder zone as shown by alteration and stringer mineralisation. Tholeiitic wallrocks are thought to be genetically unrelated to the mineralising solutions, although their presence as a cap over the felsic volcanics may have permitted the build up of a circulating metalliferous brine system prior to sulphide deposition.

Jan 1, 1984

By Taylor R. N

Flow simulations have been performed on the flash-smelting burners currently used at KNS. This paper presents studies of the heat transfer between gas and particles at the burner exit. Gas and particle temperatures, velocity and concentration profiles of the two-phase flow are calculated by the mathematical model. The predicted gas temperatures have been favourably compared against values measured by thermocouples placed near the burners in the flash furnace. The predicted particle temperatures are also reasonable when compared with the measured temperatures.

Jan 1, 1992

By Tagawa H

In Japan, geological condition do not only vary in a wide range of strata but are also extremely complex with the existence of faults and aquifers. With respect to rocks, in particular, it is very rare that homogeneous rocks are distributed uniformly. In general, geological conditions are distributed in a wide variety, ranging from earth, sand, soft and medium rocks to hard rocks. Under these geological conditions, when planning of the tunnel construction is to be made out, either blasting method or tunnel boring machines must be selected taking into consideration the geological structures along with the designed tunnel route,' possibility of encountering aquifers, hardness of rocks anticipated and also, the adjacent environ- mental conditions. In the process of select- ing an excavation method,, it is important to make a comparative investigation between the above two methods considering the advantages and disadvantages with regard to the respective operating efficiency, economical efficiency and the conditions and scope of application as well. Furthermore, in addition to these considerations, the recent environmental restriction, which does not allow the blasting in the surroundings of residential areas, must also be taken into account. Because of this, in some cases there is no alternative but to use a static excavation method or a tunneling machine even when these are less efficient than blasting.

Jan 1, 1987

Alternative processes for converting coal to liquid products and their stage of development are outlined. The merits of hydrogenationprocesses in general, and the solvent refined coal process in particular, are stressed. Bench scale experimental hydrogenation procedures used by the Australian Coal Industry Research Laboratories Ltd. (ACIRL) to study the liquefaction of Australian coals and correlations between properties of such coals and their conversion to liquid products are described. Factors involved in assessing investment and operating costs for modern hydrogenation based coal refineries of different capacities are described with reference to a recent study undertaken in N.S.W. The significance of coal properties such as yield and yield structure of total liquid products and how they and other factors can influence the economics of the coal refining operations are discussed.

Jan 1, 1977