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By Sakai S, Suga S, Bisque RE

Soil gases were collected on activated charcoal, analyzed by computerized mass spectrometry and treated with multivariate statistical pattern recognition to determine the diagnostic geochemical signature associated with the Okuaizu Geothermal Field in Japan. From this a geothermal model was developed and compare to 175 "unknown" samples in a 250 m spaced grid over 30 1Qn2 mapping the areas with a matching geochemical character. Faults and fractures were generally located by the presence of high molecular weight components. Following the initial survey, the faults in two specific areas were precisely located by a second survey with samples at 10-30m spacing. Where earlier geochemical surveys had placed anomalies 1-2 Km northeast of the geothermal center, the fingerprint survey accurately mapped the system and detected several faulted zones. It was not misled by hot springs located away from the geothermal System.

Jan 1, 1987

By Swain H. D, Kay R. L

Assessment of mineral reserves in any ore- body hinges on both mineralisation characteris- tics and the economics of extraction. The mineral reserves statement depends on interpre- tation of diamond drill information by geolo- gists, determination of the production plan and operating costs by mining and metallurgical engineers and prediction of future income by economists. The techniques used to generate the mineral reserves statement for Bougainville Copper Limited in 1969 are described and the accuracy of predictions discussed. Preliminary results from a geostatistical reassessment are comp- ared with the ore zone model, blast hole data and concentrator reconciled production results.

Jan 1, 1979

By Vynne J. F

Drill monitors for blasthole and exploration drills have been available to the mining industry since the 1970s. The early monitors were pen strip chart recorders which were developed for the oil drilling industry and adapted to mining. They recorded drilling parameters such as depth, pull-down pressure, torque, RPM, and bailing air pressure. While these recorders could generate a large volume of paper, the amount of useful data was minimal. The data was not summarised and required an engineer to interrupt the chart traces. Being a mechanical recorder, the devices were also susceptible to frequent failures.

Jan 1, 1993

By F Sinaga, E Widijanto

PT Freeport IndonesiaÆs Deep Ore Zone (DOZ) mine is the new underground block caving mine within the East Ertsberg Skarn System (EESS) which started production in mid-2000. The DOZ will produce 25 000 tpd using mechanised block cave mining method and will be the fourth underground mine opened within the EESS deposit. A review of the DOZ extraction bolting design was conducted in November 2000. The aim of this review was to re-evaluate the effectiveness of the current design in relation to bolt length and spacing and to challenge some questions about the technical background of the design. For instance, the influence of the rock condition on the design. To review this bolting design, several books and papers are reviewed and several experienced people have been contacted to give their opinion. The methodology used for this review is:reviewing the technical background of current design; collecting ideas and alternatives; collecting data from books and personal communication and conducting analysis; and conclusion and proposed design.

Jan 1, 2002

Open pit mines in the Yilgam Craton have unique hydrogeological characteristics resulting from a combination of geology, mineralisation and the complex and extended development of the regolith. The principal features of this geological relationship are:ò deep and complex multi-stage development of the weathering profile; ò steeply dipping rock layering;ò supergene enrichment; andò mining across the regolith/rock interface.These features result in large changes in permeability horizontally across rock layers; vertically through the weathering profile and along-strike in association with mineralisation and the mineralised Structure.

Jan 1, 1993

By Dunn P. G

The copper ore reserves at the Chuquicamata mine were re-estimated during March to June 1994, as part of a comprehensive audit of the mine's overall short- and long-term planning. The basic principles essential to all ore reserve estimates were implemented viz: 1. A detailed study of the geology, in this case particularly of the orientations of structural features of copper mineralisation and the subdivision of the orebody into geologically homogeneous sections, 2. the use of both drillhole and blasthole data sets, 3. statistical and geostatistical analyses of both data sets to model anisotropic spatial structures for all the geologically homogeneous sections, 4. block kriging using both data sets individually; and 5. a comprehensive validation of the block valuations to confirm the absence of global and conditional biases and to quantify the actual improvement achieved in the overall quality of the estimates compared to those executed on earlier techniques.

Jan 1, 1995

By N McIntyre, M Edraki, K R. Jain

From the very early stages of a mining project, there is a requirement to predict the chemistry of potential drainages from various waste storage facilities. However, using relative masses to scale chemical loads measured by laboratory kinetic tests, such as humidity cells, to a full-scale mine waste facility will lead to concentration predictions that are unrealistically high for many dissolved constituents. Scaling factors developed by various procedures indicate that laboratory rates may range anywhere from two to eight times (Drever and Clow, 1995) to 100 to 1000 times faster than field rates (Malmstrom et al, 2000; Smith and Beckie, 2003; Ritchie, 1994). This contribution will use previous works and secondary data to discuss the significance of scale in water quality predictions. It will also present primary experimental geochemical and numerical data from a column leaching study on coal spoils to discuss potential applications of mesoscale leaching tests in bridging the gap between bench-top tests and field scale trials.

Aug 2, 2023

By R Wolff

One critical factor in open pit mining projects is the estimation of the recoverable reserves. The reason for this is that at the valuation stage there is a lack of information about future metal prices and production costs. Consequently, the estimation of the recoverable reserves needs to be done based on a fixed break-even cut-off grade (BECG), in which fixed expected metal prices and production costs are assumed throughout the operating life of the mine (OLM). In this paper, an alternative technique for estimating the recoverable reserves of an open pit mining project is presented and explained in detail. The main characteristic of this technique is that it estimates the recoverable reserves of the project using mining costs as reference: this is done due to the fact that mining costs are easier to model than metal prices. Another important characteristic of this technique is that it uses the uncertainty of the geology of the orebody, given by simulations of the deposit, to make final strategic decisions, such as the selection of the operating life of the mine and the optimal production rate, which minimise the risk of not achieving future production targets while maximising the upside potential of future rewards. As it will be shown, the final outcome of the proposed technique is the generation of a robust open pit design, that include cutbacks and ultimate pit limits, called the marginal open pit mine design (MOPMD). One characteristic of the MOPMD is that, at each production period, it will be characterised by their respective geological uncertainty, given as probability distributions of ore, waste and metal quantities, and by marginal economical project indicators, such as cut-off grades and metal prices, among others. The details follow in the paper.

Jan 1, 2006

By A D. Pradana, D R. Pradana, Y H. Putra, Z Zulhan, T Hidayat

The high temperature processing of nickel laterite ore is currently dominated by the Rotary Kiln- Electric Furnace (RKEF) technology. The ratio of SiO2/MgO (S/M) in the ore is one of the critical parameters that determines the success of the RKEF process. Incompatible S/M ratios in the ore can cause aggressive chemical interaction between the slag and MgO refractory. The slag-refractory interaction at conditions relevant to nickel laterite ore smelting was investigated in the present study. Synthetic mixtures representing the slag compositions of nickel laterite ore smelting were prepared by mixing MgO, SiO2, Al2O3, CaO, Fe2O3, and Fe and heating the mixtures in steel containers at 1300°C under an argon atmosphere for 3 hrs. Pure MgO crucible were used as containment material in the melting process of the mixtures to represent the MgO refractory. The kinetics of the slagrefractory reaction were investigated using samples with selected initial S/M ratios of 2.0 and 3.0 (wt/wt) (with constant CaO = 3 wt per cent, Al2O3 = 5 wt per cent, FeO = 10 wt per cent) by performing melting at 1500°C in MgO crucibles for 5, 30, and 120 mins under an argon atmosphere. The effect of the S/M ratio in slag on the slag-refractory interaction was also investigated by performing melting of mixtures with different initial S/M ratios of 1.75, 2.0, 2.5, and 3.0 (wt/wt) in MgO crucibles at 1500°C for 120 mins under an argon atmosphere. After the melting process, each sample was quenched in water, mounted in resin, ground, polished, and coated. The interaction between the slags and MgO refractory was then evaluated by analysing the polished samples using a scanning electron microscope equipped with an energy dispersive spectroscopy (SEM-EDS). Thermodynamic simulations using FactSage™ 8.0 thermochemical software were performed based on the experimental slag compositions, refractory, and conditions to support the evaluation process. The results show that a higher S/M ratio in slag leads to a higher tendency for the refractory component to dissolve into the slag. A higher S/M ratio in slag also leads to an increasing extent of solid-state diffusion of iron oxide into the remaining refractory grains. The dissolution of MgO into the slag is rapid; the MgO concentration in the final slag increased by 2.4 wt per cent and 5.7 wt per cent at initial S/M ratios of 2.0 and 3.0 wt/wt, respectively, within 5 and 30 mins of the melting process.

Aug 21, 2024

By Takasaki Y, Ohzeki S, Hotta H

TO measure high temperature properties of blast furnace burdens ( the change of gas permeability accompanied by contraction, soft- ening and melting ) which govern the gas flow and its distribution, a series of experiments were carried out under simulated blast furnace conditions, using sinter, acid pellets and self -fluxing pellets. 1) The high temperature properties are affected by the ore's reducibility ( up to 1000 -1200¦C ), and the composition, and volume of gangue before reduction. Generally, the burde- ns with high basicity ( Ca0/Si02 ), high reduc- ibility and low volume of gangue have good high temperature properties. Good high temperature properties are : a high temperature at which the gas permeability rapidly decreases, a high melting point and a low maximum pressure drop. 2) Using acid pellets, slow-down of red- uction rate occurs around 1000¦C because the pellet forms a dense metallic shell, while its slag core, resulting from a FeO, Si02 and A1203 reaction, has a lower melting point. 3) The addition of MgO sources improves high temperature properties both of sinter and Pellets.

Jan 1, 1980

By Bishop I, Toon S

To determine whether 130 felt earth tremors around Edwinstowe, Nottinghamshire U.M, which also experienced severe surface fissuring, were caused by coal extraction, a surface seismometer array was established around Thoresby Colliery. Over the next year, 785 microseismic events were detected. The spatio- temporal seismicity patterns are clearly associated with the commencement, continuing extraction and closure of faces. Of particular note are events which locate at the surface and appear to be related to the active fissuring. Events occur within days of commencement of production and cease when production finishes, with good correlation between face advance and hypocentral position. Naturally occurring microseismic events have also been detected up to 1 km ahead of active longwall faces in the Midlands using triaxial geophone packages grouted into the seam together with a surface seismometer in the top of the borehole. The quality of these data were very high and guided waves can clearly be seen with the dispersive characteristics associated with seam waves. In one experiment more than 2000 events were detected in only two days of monitoring even in a relatively noisy surface environment. This paper demonstrates how very accurate locations (5 10 metres) can be generated using three-component digital data from only one borehole. The surface seismometer and the borehole P-wave onset can give extra precision for the height of the event relative to the seam. The event distributions give a dynamic, three-dimensional image of the developing patterns of fracturing above, below and ahead of the longwall face with important implications for roof control, subsidence prediction and gas Migration.

Jan 1, 1992

By Saghafi A, Kelly M, Williams R. J

A two year program of research into the feasibility of long-hole drilling for improved gas emission control has been undertaken at Appin Colliery. State of the art equipment was employed involving cableless electronic surveying and down-hole motor drilling. The project involved the drilling of 1000 m long, in-seam boreholes in the Bulli seam and boreholes of similar length drilled cross measure and then in-seam along the underlying Balgownie seam. A new concept for gas drainage was defined, employing long-holes for both predrainage and post drainage.

Jan 1, 1988

By Kurita K, Tanaka T

In order to clarify the gas flow and motion of coke and reaction in the raceway, the mathematical raceway model was developed. This model consists of the equations of momentum and continuity of gas and coke. The simulated results were compared with the results of the cold and hot experimental model. The relationship between the blast volume and the raceway size, the pressure distribution and the velocity distribution of coke are in good agreement with the experimental results. Moreover the equations of reaction and heat conservation were simultaneously calculated with the dynamic equations. Distributions of gas composi- itions and temperature were simulated and found to be in good agreement with the distributions of gas compositions of CO, CO2 on the tuyere level measur- ed in the hot experimental model.

Jan 1, 1981

After extensive testing and a period of plant trials to establish the benefits of Caro's acid (H2S05) as an alternative oxidant, Queensland Mines Limited (QML) decided to replace pyrolusite with Caro's acid in its acid leach uranium treatment plant at Nabarlek. The decision was based on the reagent savings and environmental gains associated with the removal of manganese from the process liquors, as well as the labour savings and improved oxidation reduction potential control possible in leaching using the Caro's acid system. The permanent Caro's acid generating plant was designed by Interox Chemicals Pty Ltd of Australia (IC) to suit QML's require- ments and differed from the unit used during the plant trials. Commissioning of the plant was completed in April 1983 and it has been continuously used since that date.

Jan 1, 1984

Faced with low prices and weak demand in an oversupplied market, the Australian coal industry must seek to further reduce its costs. The paper examines minesite competitiveness of the open cut coal industry in Australia with some references to the coal operations of M.I.M. Holdings Limited. The make-up of F.O.R. mine costs is analysed in order to identify where efforts should be directed to maintain competitiveness. The scope for mine site improvements through changes to working practices, the application of new technology and cost management is examined.

Jan 1, 1987

By Peck W

The tunnel alignments investigated for the Gosford Regional Sewerage Scheme are located in the Terrigal Formation and are covered for most of their length by a thick blanket of soil and weathered rock. The following techniques were found to be most effective in geotechnical investigations for tunnelling in this area: air-photo interpretation, seismic surveys to pinpoint drilling targets, in-situ measurements of strength,deformation modulus and permeability in cored holes, and the construction of rock- mass models. Cross-hole seismic modulus measurements, surface resistivity soundings and electric well-logging techniques were found to have limited applicability due to adverse local conditions.

Jan 1, 1976

By Xu C

This paper describes the structure and operation of an interacth.. computer program for mineral industry financial analysis and production planning. It includes comprehensive risk analysis with correlated variables and optimal production scheduling using Lane's balancing cut-off grades and the general dynamic programming approach.

Jan 1, 1995

Sublevel open stoping (S.L.O.S.) was introduced at Rosebery in 1972 in the wider ore blocks below 14 level, largely replacing cut and fill methods which had been in use up till that time. During 1973/74 the method produced 10% of primary stoping tonnes, and by 1981/82 it increased to 65%. Because of the increasing reliance placed on sublevel open stoping for primary stoping production, every effort was made in both planning and operating to: - maximise ore recovery and reduce dilution - increase productivity - reduce costs.

Jan 1, 1982

By Merwin RA

The recent development of rare earth permanent magnets has revolutionised the field of magnetic separation. The advent of rare earth permanent magnets in the 1980s provided a magnetic energy product an order of magnitude greater than that of conventional ferrite magnets. This has allowed the design of high-intensity magnetic circuits operating energy free and surpassing the strength and effectiveness of electromagnets. New applications and design concepts focusing on the mineral and metal processing industries have evolved. This technology also led to the development of various magnetic separators specifically designed for mineral processing applications. Applications which were not previously considered are now being applied to primary mineral upgrading and recycling and secondary recovery.

Jan 1, 1993

The first mining in Western Australia probably commenced some 40 000 years ago when Aborigines arrived and began quarrying stone for tools and weapons, and ochre for decoration. The earliest documented mining by European settlers took place in 1850 on a small lead vein in the bed of the Murchison River, reported by the explorer A C Gregory. However, it was the discovery of gold in the Kimberley region in 1885 that first drew wider attention to the State's mineral potential.

Jan 1, 1992