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By S K. Ray

Open fire in a mine gallery causes large-scale damage to property and sometimes precious lives. Such fires produce two distinct effects, the throttle effect and the buoyancy effect. These effects disturb the ventilation system of the mine. To understand the complex dynamic phenomenon of open fire and its effect on ventilation systems, a mine fire model gallery has been designed and constructed at Central Mining Research Institute, Dhanbad. Two sets of experiments at air velocities of 1 and 1.5 m/s were conducted in the gallery using coal samples from the Dobrana seam of the Raniganj coalfields. After about an hour of development of fully-fledged fire, heavy backlash, with smoke and fumes, was observed. At the time of backlash occurring the gallery was divided into two zones. In the region of the gallery from the base up to 1.4 m the airflow was normal, in the remaining upper portion the airflow was the reverse. Air quantity reduced substantially, while pressure dropped across the fire zone, the products of combustion (POC) and temperature increased during the period of the throttle effect. It has been revealed from these studies that with an increase in airflow, pressure drops across the fire zone, POC, temperature and reduction in airflow increases. This paper addresses the important design features of the gallery, the instrumentation system, the experimental procedure and assesses the effect of open fires on mine ventilation systems.

Jan 1, 2005

By Davies H, Pigram C, Sunata W, Falvey D, Loxton C, Giddings J, Rogerson R

PALAEOMAGNETIC CONSTRAINTS ON TERRANE TECTONICS IN NEW GUINEA Chris Klootwijkl), John Giddingsl), Wahyu Sunata2), Chris Pigraml), Charles Loxton3), Hugh Daviesl), Rick Rogerson3) and David Falveyl) 1) Bureau of Mineral Resources, Canberra, Australia 2) Geological Research and Development Centre, Bandung, Indonesia 3) Geological Survey of Papua New Guinea, Port Moresby, Papua New Guinea

Jan 1, 1987

This paper describes the new iron and steelmaking process recently commissioned at NZ Steel. Ironsand mined and concentrated at Waikato North head is slurry pumped 18 km to the company's Glenbrook works. Ironmaking includes the direct reduction process pioneered at Glenbrook in the 1970s and a new continuous electric melter. The molten, high carbon pig iron produced is then fed to a vanadium recovery unit and on to the KOBM oxygen steelmaking vessel. Steel is cast into billets or slabs. The new plant, which is the first stage of a fully integrated works at Glenbrook, raises New Zealand Steel's production capacity from 150 000 t/y to 750 000 t/y.

Jan 1, 1986

By M J. Davies, R S. Davies

Despite increased expenditure, the global discovery rate of world-class ore deposits has been in decline for over a decade (Schodde, 2017). Mineral exploration has traditionally followed an empirical approach, searching for evidence of mineralisation upon the surface of the planet, then drilling to define the extent of an ore body beneath the surface. As outcropping deposits in well-defined areas are depleted, there is a need for exploration to extend to less well-explored search spaces. One popular new frontier is exploration at greater depths beneath the Earth's surface. However, exploring for deep deposits with limited surficial evidence requires the implementation of predictive targeting methodologies (Hronsky, 2011; McCuaig & Hronsky, 2014). The Mineral Systems Concept (Hronsky & Groves, 2008; McCuaig et al., 2010) provides a framework for predictive exploration targeting. Ore deposit formation is recognised to be a focused mineralising event. These events represent self-organising critical systems and are underpinned by the interaction of complex, non-linear processes. Through the collection and analysis of datasets that map mineralising processes, it may be possible to predict the size and location of resultant ore bodies. CITATION: Davies, M J and Davies, R S, 2018. Beyond below-ground geological complexity: Developing adaptive expertise in exploration decision-making, in Proceedings Complex Orebodies Conference 2018, pp 95–98 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By M Jahani, M Taji

For suitable production planning in an open pit mine, and also to carry out the optimisation process during the mining production cycle, prediction of fragment size distribution is required prior to carrying out the blasting operation. For this purpose, many prediction models, such as empirical models, were presented. The proficiency of these models differs in various conditions and mines. Therefore, in this paper the most important models, including SveDeFo, Kuz-Ram, CZM, Modified Kuz-Ram in 2005, Kuznestsov-Cunningham-Ouchterlony (KCO) and also Gheibie et al, were examined by the information of 20 blasts in Gol-Gohar iron ore mine. Fourteen images were taken on average for each blast. For image processing analysis Split-Desktop software was used. After examination, it was understood that none of the available empirical fragmentation models had presented acceptable performance, except the Kuz-Ram model for magnetite ore, which had somewhat acceptable results. However, this model for blasting patterns in hematite presented unsuitable results. Examination and comparison of two important distribution functions, Rosin-Rammler and Swebrec, were carried out and it was observed that the performance of Swebrec for fines was far better than Rosin-Rammler. This result for the upper part of fragment size distribution curve, coarse, is the reverse.CITATION:Jahani, M and Taji, M, 2015. Comparison of empirical fragmentation models at the Gol-Gohar iron ore mine, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 707–714 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By G Harbort, D Zoetbrood

"The Phu Kham copper-gold operation in the Laos People’s Democratic Republic (PDR) is owned and operated by Phu Bia Mining Limited. PanAust Limited holds a 90 per cent interest in Phu Bia Mining Limited, with the remaining ten per cent held by the Laos PDR Government.The original 12 Mt/a copper-gold concentrator at Phu Kham commenced production in April 2008. An incremental improvement program resulted in a number of circuit changes being incorporated by 2011, including conversion of conditioning tanks to flotation cells and the installation of a Jameson Cell cleaner scalper. In 2012 the Phu Kham Upgrade Project was commissioned to increase throughput to 18 Mt/a. In April, 2013 the Phu Kham Increased Recovery Project was commissioned to maximise performance by debottlenecking the plant IsaMill™ regrind and cleaning capacity.With the variable mineralogy of Phu Kham ore, control of the c concentrate regrind circuit is essential in terms of achieving effective liberation to maintain concentrator performance. On a routine basis laboratory regrind signature plot data is compared with daily surveys of the operational IsaMills™. More extensive surveys are also conducted to determine size distribution on a mineralogical basis and the effect of fine regrinding on pulp electrochemistry and flotation performance. This paper provides a review of the operating performance of the Phu Kham IsaMills™ with regard to power draw, feed and product size distribution, feed per cent solids, mineralogy and pulp electrochemistry. Operating performance is compared with the IsaMill™ signature plot test for predicting performance.Citation:Harbort, G, Zoetbrood, D and McNab, B, 2016. Operating Performance of the Phu Kham IsaMill™, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 39–50 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By T W. C Stambolie

Coalmines, like any other mine, generally involve the classic three-staged approach to mining studies; namely concept, pre-feasibility study (PFS) and feasibility studies (Cusworth, 2012). Subsequent to these studies, and in instances parallel to these studies, the commitment to an environmental impact statement (EIS) is made in order to secure both state and federal development consent. In recent times, the sentiment to both mining and coal is changing whereby the traditional approaches to mine planning and economic evaluation is complicated by evolving environmental legislation, expectations and time frames. It is all too common to take shortcuts in the development of projects in order to create the perception of cost savings and expediting the delivery timeline. Atkins (2016) points out that: boards of so many small to mid-tier mining companies, and a few majors, focus on relentless project delivery too early in the project process, with so little time and effort applied to risk analysis and option development. Unforeseen risks can cost any timeline or budget far more than the effort required assessing and mitigating these. The ultimate risk to any feasible coal project is that of environmental approval and achieving development consent.CITATION:Stambolie, T W C, 2016. A black canvas – planning a greenfield coalmine in New South Wales, in Proceedings Life-of-Mine 2016 Conference , pp 31–35 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

In a ætypicalÆ gold deposit each tonne of ore will contain tens of millions of very fine gold particles, whereas; at Bendigo the majority of gold in each tonne of ore is present in just five to 15 very coarse gold particles, a distribution more akin to diamond deposits. At Bendigo the minimum sample size required for good assay repeatability is estimated at 4.5 t for each assay. Drill core samples are several orders of magnitude too small to generate representative assays.The drilling data are characterised by a nugget effect approaching 90 per cent, a very skewed distribution and, on average, under-report in situ grade by 50 per cent to 75 per cent. Since 2002 Bendigo Mining NL has completed 47 000 m of diamond drilling, 1200 m of on reef development, collected and processed 100 bulk samples (150 t each), 800 mini bulk samples (50 kg each) and processed in excess of 25 000 t of ore through a pilot plant. The results of this work have provided the information required to develop and verify a robust grade estimation procedure. No standard geostatistical manipulation of the drilling assay data can generate an accurate grade estimate as the samples and associated assays are not representative of the ore being sampled. The recognition of this fact was critical as a radical transformation of the raw drill assay data was required to develop a workable methodology for grade estimation in such a high nugget environment. The aim of the transformation was to reduce the nugget effect and high variance and so approach a lognormal assay distribution. Ideally the average drill grade would approximate actual in situ grade and the assay distribution would reflect actual grade distribution within the reefs. Following the data transformation simple block modeling within the defined resources allows grade estimates to be made that can be used in the estimation of Indicated Resources and hence Probable Reserves. The grade estimates have been checked by extensive bulk sampling and processing of 25 000 t of ore (three per cent of total resource) through a pilot plant with planned full scale mining to provide the ultimate verification.

Jan 1, 2004

By I Gipps

The mining industry has come through a period of major change in community expectations regarding safety and environmental impact and these changes can be expected to continue in the future. These changes are ultimately reflected in Government regulations and industry safety standards and form the basis of the ælicense to operateÆ. Equally, advances in technology have made possible new equipment and processes either available now, or close to completion, that will allow mines to meet these more stringent expectations if properly introduced. Changes in technology provide opportunities for mine management to introduce new systems that will remove people from hazardous areas and lead to improvements in the ætriple bottom lineÆ. In a longer time frame of five to ten years, novel and advanced technologies that are currently being developed will deliver new mining methods and conversion of presently uneconomic resources to ore. This is consistent with the time frame required to develop a new mine from discovery. Strategic decisions can be taken now by mine designers to enable the introduction of these major technology changes. Examples of both practical and strategic opportunities are drawn from the integration of rock cutting/blasting, automation, electronic communications and new mining methods. This paper discusses emerging industry trends, changes to legislative framework and some practical choices for existing and imminent technology.

Jan 1, 2003

An automatic control system of a longwall roof support is dis-cussed. Hydraulic automatic control systems for longwall roof support have not met all requirements for such systems. Utilization of standard hydraulic elements to form a system that would-comply with all demands leads to a very complicated structure with a large number of hydraulic hoses within and between adjacent supports. So, only simplified systems have been made. This paper describes the multifunctional valve that per-mits realization of any desired logic functions, while maintaining a com-pact form, and analyses its application as a fully hydraulic automatic control system of a roof support.

Jan 1, 1985

By V Sanmartfn, J Torracchi

The broad biodiversity of our country is manifested through several different biological forms. From the villages of Portovelo and San Gerardo in the southern part of Ecuador, some samples of water and rocks were taken in order to identify the native micro-organisms which take part in the natural processes of leaching of sulfurous minerals. The presence of Spp Thiobacillus ferrooxidans was determined together with a fungi sample which has not yet been characterised by the current workers. These have been isolated, grown, experimented and conserved in appropriate cryogenic environments. The present research intends to study the individual and group adaptation of the bacteria and the fungi upon suitable systems of agitation and ventilation, in combination with several different concentrations of refractory auriferous samples. These refractory samples were derived from old mine workings and the experiments were performed to test the effectiveness of the isolated species in bioleaching as pre-treatments upon the cyaniding processes. The capability of these bacteria to develop in environments with high concentrations of cyanide has also been studied, to investigate the possible use of bacteria in the biodegradation of cyanide. The presence of Thiobacillus ferrooxidans in acid conditions has already been tested in advance, however, the presence of fungi species in these conditions are studied to prove their efficiency as another alternative for the bioleaching of refractory auriferous minerals and Baptista, 1998).

Jan 1, 2004

By S Hayton

While coal seam gas is considered to be an unconventional gas, the proliferation of areas under exploration and development mean that it is rapidly becoming main stream. The potential of New Zealand's coals to produce coal seam gas has been recognised for some time. However, key market drivers have not been suitable for the progression of this potential into reality. Kenham Holdings Ltd and CRL Energy Ltd, recognising the potential for the gas in New Zealand have initiated what is the largest ever assessment of New Zealand's coal seam gas potential. The premature demise of the giant Maui field has raised the focus of new gas developments and has increased interest in what we are doing. Over the past couple of years Kenham Holdings Ltd and CRL Energy Ltd have approached the assessment of the coal seam gas potential in a staged programme. Preliminary assessment of the data on the permit areas indicates that the potential resource may be up to 500 PJ. To date, preliminary appraisals have been completed or are underway on a significant number of fields. Exploratory drilling has been completed or initiated on several of those fields, with results from this work being fed into the preliminary modelling as it has become available. Given that in many of these areas there is no pre-existing information concerning their gas potential and world wide experience with lignite is practically nonexistent, it has been a steep learning curve with many surprises. However, initial gas content results and preliminary gas flow models have been on the whole, rather pleasing, with the commerciality of some developments already apparent.

Jan 1, 2003

The Newcrest Mining Limited Telfer Gold Mine consists of an underground sublevel cave (SLC) operation located 734 m directly below active open pit operations. Open pit and underground current production rates are 50 million and 5.7 million tonnes per anum (Mt/a) respectively. The SLC was initiated in late 2006 with breakthrough planned to occur on the 5484 bench of the west wall in late 2009. Risk to the south ramp was identified during this time, resulting in the construction of the north ramp. The SLC was continually tracked from initiation with a suite of monitoring systems and managed with a Major Hazard Management Plan (MHMP) and associated Trigger Action and Response Plans (TARP). At breakthrough the eastern limb of the cave was located within a 70 m horizontal distance from the south ramp. The south ramp was closed in October 2009 due to significant slope deformation, extensive cracking in the berms and batters between the ramp and breakthrough bench and a major failure 250 m to the north of the cave breakthrough. Wall response was first identified from slope deformation measurements taken by the wall monitoring radar in May 2009, at which point the SLC was 160 m from breakthrough. The impact of the SLC on the slope is a unique case with the monitoring systems in place able to provide data on the slope reaction to the SLC progression. This paper will discuss the management of the south ramp such as the early interpretation of risk associated with cave breakthrough, monitoring systems implemented to track the cave progression and wall deformation, data integration and interpretation and risk management. Following the closure of the south ramp further instrumentation programs and risk assessments were conducted to determine the risk of re-opening this haulage route. The outcomes of this program will also be presented.

Nov 25, 2010

By Moritz P

Thiourea has been recognised for a long time as an acid-stable complexant for gold. Generally, the use of thiourea has been shown to exhibit enhanced leaching kinetics compared to cyanide but suffers the disadvantage of excessive reagent consumption. Thiourea leaching is particularly com- patible with the extraction of gold from refractory ores. This is due to the need for an oxidative pretreatment to liberate the gold. Such pretreatments typically result in the production of an acidic residue. The application of novel thiourea leaching technologies to the extraction of gold from a bioleached pyrite concentrate was investigated. The interac- tion of leach variables with thiourea consumption and gold extraction was established. An economic assessment of thiourea leaching was compared with conventional cyanidation. The results indicated that gold leaching of the bioleached residue using thiourea compared very favourably with cyanidation.

Jan 1, 1991

By S Fityus, K Koosmen, J Simmons

The purpose of this paper is to therefore investigate the hydrogeological characteristics of tailings, coarse and mixed rejects from coal processing to enable better understanding of the potential for undrained behaviours in coal mine spoil piles. This is achieved by analysing the results from permeability and oedometer testing of tailings, coarse rejects and mixtures thereof. Focus is given to the effect that tailings content has on the behaviour of mixed rejects, the transition point between drained and undrained material behaviours, and the evolution of properties with increasing stress that would occur with increased depth of burial in a mine spoil pile. The implications of the findings are discussed with respect to spoil pile stability.

Jul 1, 2021

By A Melkumyan, F Ramos

This paper addresses the problem of prediction of grade variables over volumes (block estimation) for an autonomous mine. Resource estimation is usually concerned with the prediction of the quality of material over volumes (blocks in resource models). This problem is tackled by developing Bayesian block estimation with the Gaussian processes (GPs) framework. GPs are commonly used for nonparametric regression and classification and offer an elegant solution to deal with incomplete knowledge and information. A GP is defined by its mean and covariance function. The parameters of the covariance function can be learnt by maximising the marginal likelihood of the data. This offers a way of automating the covariance fitting process, while at the same time allowing for an assessment of how well the covariance function fits the data. Within the GP framework the calculation of the average grade over a volume can be performed using Bayesian quadrature, which treats an integral as a random variable. First, it is demonstrated that the block kriging equations in geostatistics are the same as Bayesian quadrature. Then, it is determined when closed form analytical solutions for the integrals are possible and quadrature approaches for approximations are briefly discussed.

Sep 26, 2011

By T McConachy

New opportunities for miners are beginning to appear through new discoveries, improved knowledge and access to vast unexplored areas of the deep sea and continental shelf. Recent discoveries of undersea hydrothermal deposits show evidence of high-grade mineralisation, although in many instances the extent of the resource is still unknown. The promise and the difficulties of undersea mining have been evident since attempts were first made to mine manganese nodules in the 1960s. The physical nature of the undersea resource is a key influence on its mining potential; and environmental issues will also become increasingly important. This paper explores these issues and concludes with a description of the immediate to medium term applied research required to develop this industry and the spin off that such research can provide.

Jan 1, 2000

This paper gives the background to the development of solvent extraction processes for the recovery of metals from aqueous solutions. Its growing importance in Australia for the recovery of both uranium and copper is dis- cussed, as well as the developments in mixer-settler design as applied to recent plants. The economic significance of solvent extraction as an alterna- tive to cementation is discussed and important features of each process are highlighted by comparison of costs for each process in a hypothetical situa- Tion.

Jan 1, 1971

By Minchinton A

CPeX is a non-ideal explosive performance prediction model. The model takes into account the rate of energy release, the extent of chemical reac- tion and the effect of confinement on energy release. The model resolves the explosive energy into `shock' and `heave' com- ponents as a function of explosive type, hole diameter and rock type. The predictions of the model are compared for a bulk emulsion, and a prill-doped bulk emulsion in soft rock. The predictions, based on calibra- tion of the model with simple unconfined detonation velocity measure- ments, show the significant effect of non-ideality on explosive Performance.

Jan 1, 1988

By F Ramos

Conventional techniques for resource estimation generally involve the laborious analysis of variograms and the specification of parameters for covariance functions. In large deposits, construction of resource models and their update require significant amount of manual work, expert knowledge and time. In this paper we take a machine learning view to the problem of resource estimation. This is a non-parametric Bayesian method, leading to automatic parameter estimation (learning). Through Bayesian learning, the parameters of the model can be obtained by optimising a quantity known as the marginal likelihood. The main advantage of this approach over conventional maximum likelihood estimators is that the objective function incorporates the OccamÆs razor principle. This allows the comparison of different statistical models û for example, models designed with different covariance functions û and naturally penalises complexity, thus avoiding overfitting. Our technique presents significant flexibility for the definition of mean and covariance functions and permits the usage of more sophisticated models.The second contribution of this work is the formulation of a data fusion mechanism that continuously updates the resource model. As mining progresses, more information becomes available. For example, the hardness of the rocks can be measured while drilling blast holes, grades of ore and contaminants are obtained from cone logging. This information is in general available at a finer spatial resolution but can be more uncertain. The data fusion mechanism can seamlessly estimate the uncertainties of the different types of information and fuse them as new measurements are acquired. This procedure can significantly improve the quality of the resource model, defining new grounds for stochastic mine planning. We demonstrate the effectiveness of our approach in estimating iron ore deposits by integrating information about different grades.

Sep 26, 2011