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By K Uchino, M Inoue

Self-potential anomalies are generated by fluid pressure gradient, by temperature gradient or by chemical gradient. On the basis of this principle, a new technique is proposed to locate the fire source of spontaneous combustion of coal by the self-potential method. In order to investigate whether this method can be applied to locate the spontaneous combustion of coal in practice, surveys of self-potential distributions were undertaken in a coal waste pile undergoing spontaneous combustion. The results showed that there is a negative centre of the electrical potential distribution in the measurement area. The potential in this centre is about 140 mV lower than that in the surrounding area. Moreover, the negative centre of electrical potential distribution almost overlaps with the high temperature zone. Therefore, it is concluded that it is possible to locate the heat source by the measurement of self-potential distribution.

Jan 1, 2005

By A L. Hemphill

Conventional models, based on pulp kinetics, were regressed directly to steady-state data from a nine-stage platinum flotation plant, to provide a basis for optimisation studies. æFroth factorsÆ were used to characterise the froth in each stage and a ædepressant factorÆ was used for gangue minerals, to account for addition of depressant to the cleaners. These factors improved the fit, but differences between plant and model of up to 50 per cent were still present in a number of streams in the cleaning circuit. A new model was developed, which incorporated two rate constants for the recycle of particles from the froth. These parameters provided a workable approximation of the distribution of probabilities of particles being recycled in plant cells, depending upon where particles appeared at the surface. The feed streams were characterised by two pulp kinetic parameters and the above recycle parameters, for all minerals and all stages. The fit to the data was improved very significantly, when compared to the use of conventional pulp-based models with several pulp rate parameters. This relatively simple model did not require additional data from batch tests and it was suitable for plant simulations.Simulations of various strategies for plant operation were tested, allowing the simulator to vary the concentrate flows from all or some of the stages, in order to maximise platinum recovery. The simulator was imbedded in an automatic optimiser and constraints on chrome content or mass flow of final concentrate were used. The simulations of the existing circuits demonstrated that an improvement in recovery, (for a constant concentrate mass) of about 0.5 per cent was possible, by optimising all concentrate flows. A significant reduction in the flow of scavenger concentrate and an increase in the recycle flows in the cleaners were noted. The results of simulations of various changes to the circuit configuration are also discussed. An increase in recovery of 1.4 per cent (for constant concentrate mass) has been achieved in recent simulations, through circuit changes. However, it was necessary to keep the mass pull of concentrate, per unit area, within typical limits.

Jan 1, 2005

By S Lehane, S Pearce

The characterisation and assessment of waste rock has been the subject of considerable research, and many guidance documents have been published both internationally and within Australia. While these documents provide detailed information on how to characterise waste rock, there is not a great amount of detail on how to determine the optimal waste management options from an operational viewpoint. For example, typical questions that a mine operator would seek answers to include: What placement method should be used (eg end tipping versus paddock dumping)? What is an optimal tip head height for waste placement in a storage facility? How should sulfide grade control be carried out?Defining the contributing factors to waste management and waste material placement and assessing the contribution of each variable directs these assessments towards a semi-qualitative and quantitative methodology. Quantitative methodologies show an increase in the confidence of these assessments by providing logical, measureable assessments.As part of a strategic assessment for waste management at an active mine site, a detailed risk-based investigation of the influence of variables common to waste placement was completed. These variables included placement method, placement height, sulfur grade and material conditioning (eg compaction) on the associated risks of waste material storage. The assessed risks include temperature assessments (potential for thermal take-off as a result of spontaneous combustion), toxic gas production and flow and acid production potential. Applying a numerical modelling approach to the assessment of the different waste material placement strategies allows for the variation in risk to be graphically presented and communicated through risk matrices and histograms.CITATION:Pearce, S and Lehane, S, 2015. Quantitative risk assessment tools to assist with waste management and placement guidelines, in Proceedings Tailings and Mine Waste Management for the 21st Century, pp 353–364 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By Y Li, B Shen, S Zhang

Jointed rock mass is often encountered in rock engineering and its stability has always been a major concern in underground engineering. To analyze the stress characteristics and their variations in jointed rocks, in this study, a new concept of sub-instability stage before rock failure is defined, and a new experimental method is used to investigate interaction between defects and intact rock of the jointed rock mass during the subinstability stage., Firstly, external characteristics of stress and failure mode of the whole jointed rock are investigated systematically by conducting uniaxial compression tests on red sandstone samples with a set of preexisting open flaws of different sizes, and the interactive damage of intact parts and defects in the subinstability stage was further studied. Secondly, rock-like material samples made of bonded plaster blocks were tested and internal data from stress sensor between the strong and weak segments were collected. The transforming processes from independent activity of the individual segment to overall interactive movement of jointed rock before the unstable failure were analysed. The test results indicated that the subinstability stage marked the beginning of interactive failure between the intact rock and defects. In the early subinstability stage, the relatively intact parts bore most of the load in a jointed rock mass, and the defects were damaged firstly which caused high strain around it. The areas of high strain increase rapidly, extending and migrating, causing damage to the intact parts. In the later sub-instability stage, the interaction effect reached its maximum, and a large number of cracks appeared in the intact rock and they propagated and coalesced. Intact parts experienced rapid failure and then the jointed rock failed. The experimental method used in this paper to identify the sub-instability stage could be used to identify failure precursors of jointed rock masses and to develop technology for disaster prevention in rock engineering. CITATION:Zhang, S, Shen, B and Li, Y, 2018. Experimental studies on interactive failure characteristics of jointed rock, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 453–461 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

THIS paper is not intended to be more than a mere outline of the economic geology of Tasmania. It is desired to present in a condensed form the present state of our knowledge in regard to the distribution of the ore, coal, and oil-shale deposits of Tasmania in time and space.Tasmania is exceptionally well endowed with mineral wealth, particularly in the north-western and western districts. In the enthusiasm resulting from the first discoveries of mineral deposits at a great number of localities in those districts, it became a generally accepted belief that the whole of that portion of Tasmania constituted a continuous metalliferous province. As geological research in these, areas has progressed, however, it has become increasingly clear that ore-deposition has been confined on an economic scale to definite well-defined areas or belts which have a genetic relationship to certain tectonic and petrologic phases of the general geology. These areas or belts have recently been defined by the writer, and...

Jan 1, 1923

Mining in Guyana dates back into antiquity and a brief history of gold and diamond mining and of the small-scale miner, the pork-knocker, is given. The gold and diamond deposits found on the beds and in the flats of old and present rivers and the current methods of investiga- ting these deposits are briefly described. Methods of mining these deposits including the small-scale hand methods of pitting and diving with or without helmets are also briefly described. 'The small-scale method of dredging using a suction dredge in conjunction with a diver is described in more detail, from its develop- ment to current practice, without giving too much mechanical and technical details. The organisation of the industry and the mining titles, laws and policy relating thereto are reviewed. A brief account is given of the socio- economic role of the industry. Conclusions are made regarding the need for improvements in existing equipment and financing and for incentives to stimulate production. The future outlook of the industry is con- sidered.

Jan 1, 1986

By I Canbulat, J Emery, L Yao and C Zhang

This paper documents a process of data analytics and machine learning applied to coalmine roof convergence data. It follows a publication documenting the formation of the database. For each set of analyses Python scripts were utilised to extract data from an SQL database, with subsequent analyses also executed in Python, utilising open-source tools such as scikit-learn. Preliminary analyses with classic machine learning algorithms included multiple logistic regression, K-nearest neighbours, decision tree, random forest, support vector machine, kernel support vector machine, artificial neural network (ANN), naïve Bayes and multiple linear regression. Results indicated that relationships were complex and non-linear, with the artificial neural network most suitable. An ANN model was then refined through a standard process of hyperparameter optimisation and data augmentation to arrive at a final model. Due to the black box nature of the ANN further insight into how the parameters interacted was sought and found with Shapley additive explanations (SHAP values). SHAP values utilise Game Theory, where each input parameter or feature is a ‘player’ while the data set is the ‘team’. The SHAP value is the impact of each player on the target value, essentially establishing the contribution of each input parameter. The results from all analyses are delivered in the paper, together with insights, applications, strengths, and limitations of the methodology.

Nov 29, 2022

By S Li, Y Lei, X Wu, C Ma, W Q. Zhang

The failure of roof of thin bedrock working face under loose aquifer in a coalmine can lead to water-sand inrush disaster. Based on the accident of water-sand inrush in 30108 working face of a mine in Shaanxi province, China, the mechanism of water-sand inrush is theoretically analysed. The process and critical conditions of water-sand inrush in working face are reproduced by numerical simulation where the bedrock thickness is 20 m, the clay layer thickness is 40 m and the mining height is 6.5 m. The study found that under the condition of thin bedrock and thick clay layer, the characteristics of the clay layer have a significant inhibitory effect on the development of the fractured zone, and the development of the water-conducting fractured zone is incomplete and insufficient. However, in the process of continuous mining of multiple adjacent working faces, the strength of the clay is gradually reduced by the influence of mining and the erosion of water, and the height of the fractured zone is gradually increased. In the subsequent mining process of the working face, the roof is more likely to be cut-off and lead to water-sand inrush. From the initial failure of the clay to the final crack directly through the surface, the shear strength of the clay is reduced by about 52 per cent. Further simulation found that in addition to the characteristics of the clay layer itself, the main factors affecting the water-sand inrush in the working face caused by overburden failure also include the difference in bedrock thickness and strength, and the difference in coal seam mining height. With the increase of bedrock thickness, the development height of the fractured zone increases gradually with increases of bedrock thickness when the cutting failure of overburden rock no longer occurs. With the increase of mining height, the height of water flowing fractured zone also increases, but the cracking ratio gradually decreases. Therefore, it’s of great practical significance to systematically study the mechanism and critical conditions of water and sand inrush in mines and the main influencing factors for preventing similar accidents in mines with similar conditions.

Nov 29, 2022

By S Coward, J Vann, R Wolff, S Jackson, S Moayer, A Bye

Uncertainty about the future and orebody should significantly impact evaluation of mining projects. Scenario planning, widely used in other industries, for example in the petroleum industry, can provide organisations with an opportunity to explore the consequences of uncertainty on their future plans. By developing plausible scenarios, scenario planning assists decision makers by allowing them to make systematic and possibly effective decisions for the future. This paper reviews existing mine project evaluation in the context of a new framework called scenario-based project evaluation (SBPE) (Vann et al , 2012) that addresses many shortcomings of existing approaches. SBPE uses conditional simulations (CS) models as inputs which are evaluated against future alternative project pathways (æalternativesÆ). These alternatives are evaluated using multiple plausible images of the deposit (CS realisations) which capture realistic variability and as an ensemble, map uncertainty of various orebody attributes at fine scale. The alternatives can involve different mining, stockpiling, blending and processing strategies. The ultimate output is a (stochastic) set of cash flows for each alternative from which financial measures, such as NPV, can be derived. Alternatives can then be explored in the presence of against external scenarios such as changes in prices, costs, and taxation. The obvious problem with such data rich results is knowing which scenarios or group of scenarios are optimal.An innovative approach to robust stochastic optimisation (RSO) suited to the SBPE framework is presented here for the first time. This approach to RSO aims to deal with the large number of alternatives generated from SPBE. The goal of applying the RSO approach to SBPE is to identify robust strategic alternatives (project configurations) which have the flexibility to deal with variability and uncertainty of geological and processing inputs such as density, grade and process performance. By applying the proposed RSO method, it is possible to deal with uncertainty and identify the best project configuration in the face of a large number of envisaged scenarios. A case study is provided, in which we have tested the application of the proposed method and compared the result with conventional methods. An important conclusion from this research is that selecting the value of the penalty coefficients in the RSO approach proposed is (as is all optimisation) an exercise of trade-offs; a higher net present value (NPV) is generally associated with a higher risk and a lower risk is associated with a lower NPV. Indeed, this is a strong argument for considering the RSO approach outlined here over more conventional approaches.CITATION:Moayer, S, Vann, J, Coward, S, Jackson, S, Bye, A and Wolff, R, 2012. An innovative approach to robust optimisation for scenario-based mineral project evaluation, in Proceedings Project Evaluation 2012 , pp 141-148 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

Stereological transformation relies on knowledge of the textural characteristic that governs the relationship between the one-, two- and three-dimensional liberation spectrum. Transformation functions can be built from fractionation of real mineralogical particles. Alternatively, transformation functions can be built from simulated textures, geometrical textures or artificial textures. These transformation functions can be useful when the texture of an ore has not yet been characterised for the preliminary assessment of liberation. Recently, Lin et al (1995) developed a methodology for generating such an artificial texture. The artificial texture can be used to produce broken particles of known volumetric composition. Data from image analysis on several artificially generated samples is readily available, and can be used to build the associated stereological transformation function. In this work, the methodology for calculating the transformation function from LinÆs artificial texture is presented. The new texture is implemented for stereological transformation applications.

Jan 1, 2008

Porphyry type mineralization of Lower Cretaceous age in eastern Queensland has been recognized only from the easternmost part of the northern New England Orogen (Day, Murray and Whitaker, 1978), within the northern Yarrol Province (Horton,1982). Recent work about the Mt. Suthers (Pb, Zn, Ag, Cu, Au), Lug-e-nor (Cu, Pb, Zn, Ag, Au, Mo), and German Tully (Cu, Au, Bi) prospects suggest that there has been a phase of porphyry type mineralization within the Gympie Province, of Lower Cretaceous age, overprinting earlier Permo-Triassic phases. About the Mt. Suthers Prospect surface samples of shallow, medium to heavy textured soils derived from marine sedimentary rocks of Permian age, and extrusive and intrusive igneous rocks of intermediate composition and Triassic age, were analysed for Cu, Zn, Pb, Co, Cr, Ni, Fe, V, Mn and Ag. Whereas strong iithological control determined the distribu- tion of Cu (diorite) and of Cr, Ni, Fe and V ,sedimentary rocks), the distribution of Pb, Zn, Ag and of Cu, were determined by mineralization of faults by a cavity fill hydrothermal process. Gold is associated with the Pb, Zn, Ag mineralization. Co and Mn showed distributions independent of lithology and structure. The fault controlled style of mineraliz- ation at Mt. Suthers is repeated at other localities to the south; Calgoa, Marodian, and German Gully. Relative dating of structural features and isotopic dating of nornblende porphyrites (134-135 m.y.) near and related to those mineralized at German c;ully suggest a previously unrecognized phase of porphyry copper style mineralization in south-east Queensland of Lower Cretaceous age (Fig. 1).

Jan 1, 1987

The constructionhunnelling industry in Hong Kong has taken an upturn during the last few years due to the commencement of works to relocate the International Airport to Chek Lap Kok Island. The Airport Core Program consists of ten individual projects including roads, landfill, bridges and tunnels to build the airport and link it to the mainland of Hong Kong. Part of one of these projects is Cheung Ching Tunnel located on Tsing Yi Island. The proposed tunnel consists of a 1.6 km twin tube road tunnel through the island's central ridge, taking three lanes of traffic each way. Each tunnel is 16 m wide - (the widest road tunnel in Hong Kong) and are 10 m high. ICI Explosives (China) saw an opportunity to supply bulk explosives to the Cheung Ching tunnel and contacted ICI Australia to determine availability of a bulk system for tunnel blasting, and assist in its introduction. This paper discusses the methodology behind developing that bulk system to suit a large tunnel drill and blast operation. It also looks at the problems encountered along the way, from the development of the product to the application of the system in the tunnel and the eventual success of introducing a bulk system into a large tunnelling project.

Jan 1, 1994

Rajasthan of western India blessed with rich base metal and phosphorite deposits. The biogeochemical and geobotanical methods of mineral exploration are greatly used in parts of Rajasthan Zawar, Khetri and Ambaj multi-metal project Gujarat and Jhamarkotra phosphorite deposit. These principles are exclusively based on certain assumptions about the anomalous chemical composition in plants and distribution and migration of indicator elements. Biogeochemical studies for lead zinc deposit of Zawar group of mines were carried out to locate the probable accumulators which could help in prospecting for these metals. The important roots of Impatiens balsamia plants contain 735 mg. of cadmium and crotolaria linifolia 603 mg., melhania futteyporensis 626 mg. lindenbergia muraria 443, celosiu argentia 360 mg. In the Khetri copper belt the vegetation is scanty and the species includes Acacia arabica, zyzypus jujuba and cactus euphorbia.

Jan 1, 1988

DuPont is a chemical and energy multi-national of approximately 90,000 employees. Often regarded as the world leader in injury reduction and process safety management, DuPont operate 140 manufacturing sites around the globe. Conoco is a wholly owed subsidiary of DuPont which is involved in oil, gas and coal exploration.   Throughout this paper I will discuss DuPont statistics, developing a safety culture and training process as well as discussing possible short comings in the New Zealand safety focus. I will conclude with my recommended improvements and issues for New Zealand companies to focus on.   It is very difficult to compare DuPont and New Zealand statistics through lack of compatibility in recording methods and my ability to interpret ACC's Injury Statistics. However through considering DuPont's statistics, and comparing them to your own companies or departments, you will agree they are indeed impressive. I hope that by discussing DuPont's safety philosophy, and possible shortfalls within New Zealand Legislation many of you will find ideas and inspiration which will help you to further reduce your own injury rates.

Jan 1, 1997

By Hainsworth D, Winstanley G, Gurgenci H, Corke P

Past experience has shown that the automation of the dragline swing motion requires real time monitoring of the bucket position. A current project at the Centre for Mining Technology and Equipment (CMTE) is aiming to achieve this using machine vision. The hardware platform is a Datacube MaxVideo 200 system. The images are obtained by a fixed camera installed on the dragline boom. The field of view is large enough to include the bucket in all possible configurations. Standard chain coding and run-length coding algorithms are used to process the video image. The three-dimensional bucket position is calculated by combining the output of the machine vision system with the rope length data obtained from transducers installed on drag and hoist drums. This information is then fed into a control computer which takes corrective action to suppress bucket oscillations before they reach dangerous levels.

Jan 1, 1995

New Zealand Steel Limited is nearing completion of the environmental reporting and planning procedures for its proposed fivefold expansion to steelmaking at Glenbrook, and supporting mining operations at Waikato North Head. A report on the proposal to transport concentrate from the mining operations to Glenbrook has also been prepared and is awaiting release. This paper draws from these events, and by discussing some of the problems encountered, gives some guidelines for the preparation of an Environmental Impact Report.

Jan 1, 1981

By F Minz, P Lamberg, A Mwanga, C Lund, C Wanhainen, M Amiri Parian, J Rosenkranz

A geometallurgical model is currently built in two different ways. The first and the most common way relies on geometallurgical testing, where a large number of samples are analysed for metallurgical response using small-scale laboratory tests, eg Davis tube testing. The second, mineralogical approach focuses on collecting mineralogical information over the orebody and building the metallurgical model based on mineralogy. At Lules University of Technology, Sweden, the latter method has been adopted and taken further in four ongoing PhD studies. The geological model gives modal composition by the help of element-to-mineral conversion and Rietveld X-ray diffraction. Texturally, the orebody is divided into different archetypes, and liberation measurements for each of them are carried out in processing fineness using IncaMineral, a SEM-based technique. The grindability and liberation spectrum of any given geological unit (sample, ore block, domain) are extrapolated from the archetypes. The process model is taken into a liberation level by mass balancing selected metallurgical tests using the particle tracking technique. The approach is general and can be applied to any type of ores. Examples of ongoing studies on iron and massive sulfide ores are given.CITATION:Lamberg, P, Rosenkranz, J, Wanhainen, C, Lund, C, Minz, F, Mwanga, A and Amiri Parian, M, 2013. Building a geometallurgical model in iron ores using a mineralogical approach with liberation data, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 317-324 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

Underground mechanized excavation in New Zealand has become more commonplace in civil and mining applications during the last three years. At one stage up to seven Dosco Road- header machines were being used on different projects around the country. The Huntly West Mine Drifts inclined at one in four were by far the most severe grade conditions that the machines were subjected to; however, other operations posed their own particular problems for the machines. Two major interrelated factors became evident as soon as the machines commenced at Huntly. These were traction problems on the grade and control of water, particularly on the invert.

Jan 1, 1978

By J MacDiarmid

Atlas Copco is a leading provider of industrial productivity solutions (Atlas Copco, 2007) and one of the worldÆs largest suppliers of rock drilling equipment. The business division of Atlas Copco Construction and Mining Technique is based in +rebro, Sweden with the majority of their equipment produced in a number of facilities within the area. As part of the 2006 AusIMM/Atlas Copco Scholarship I was fortunate enough to visit these facilities to experience first hand this truly unique global company. Through numerous presentations on the various divisions and products manufactured by the company, I saw the broad range of products and services offered by the company and came to realise it is much more than just selling drills. Other highlights included a brief love affair, a tour of EuropeÆs largest underground mine (or factory depending who you ask), a drink at the ice bar at the ice hotel in JukkasjSrvi, and a number of dinners of reindeer. Overall this it was a truly amazing experience with all involved with the program going out of their way to ensure I got the most out of the trip. More importantly, through no effort at all, everyone naturally conveyed their passion for the industry and the company which is a great credit to the æAtlas Copco WayÆ thereby creating a company æcommitted to your superior productivity through interaction and innovationÆ.

Jan 1, 2007

By P M. Hetherington, M P. Murphy, K E. Crook, F Pym

Resource characterisation is critical for informed decisions in both strategic and operational space. The sources of information for resource characterisation are limited by: direct measurement of resource attributes, such as grades, rock-types, mineralogy, and are available only from sparse locations, ie drill holes; or indirect geophysical measurements such as seismic, gravity or electro[1]magnetic survey. Data collection tools, methods, and processing technologies are constantly improving providing a broad spectrum of options for data collection strategies. The cost of each data survey varies from thousands to millions of dollars with the value of each additional data having diminishing return for a particular business decision. The value of information analysis provides the optimal decision on data collection strategy within a limited available budget. This work presents an example of value of information analysis for new Blast Hole Assay Tool (BHAT) and Reverse Circulation Grade Control (RCGC) data used in addition to the wider spaced exploration data. The value of information is quantified in terms of reduction of grade uncertainty, ore loss and dilution by comparing different combinations of data collection methods. Four different strategies were considered: exploration samples in addition to 50 per cent of blastholes surveyed with BHAT, exploration samples in addition to 33 per cent of blastholes surveyed with BHAT, exploration with wide-spaced RCGC data, and exploration without additional grade control. For each strategy the observed values have been simulated using advanced multivariate geostatistical simulations and compared with simulated ground truth models. The calculated uncertainty, ore loss and dilution informed the optimal data collection strategy. Opportunity to reduce sample density from the nominal 50 per cent of drill holes was evaluated.

Mar 22, 2022