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By J Knecht, R Klymowsky, E Burchardt

The wide spread introduction of SAG mills into grinding circuits 20 years ago was the last development which had a major impact on the design and economics of comminution circuits. Single SAG mills were able to replace batteries of high maintenance and cost intensive crushers in order to achieve high throughput operations. Today, where the head grades of gold and copper ores are falling, there is again a strong need for a significant breakthrough to reduce investment and operating costs as well as improve metal recoveries. High-pressure grinding rolls is the new technology available to meet this challenge. HPGRÆs are state-of-the-art in several mining and minerals applications such as the grinding of iron ores and concentrates, and diamond bearing ores. Reasons for their success in these industries are overall cost reductions and improved product properties achieved by the application of high compressive forces. But these ores are relatively soft, with unconfined compressive strengths up to 150 Mpa.

Jan 1, 2000

Until early-1997, Mount Isa Mines Limited (MIM) generated electrical power for most of north-west Queensland. The discoveries of many new orebodies in the region meant the inevitable increase in power generation requirements for the new mines. In addition, the expansion at Mount Isa itself meant that MIM had to invest in new generating capacity or utilise the existing generating plant more effectively. Using its generating plant more effectively required MIM to undertake rigorous energy management within its own operations. A personal computer based system with a wide area network was installed as the basis for energy management. The result was that energy consumption was reduced, the need for additional generating plant was curtailed, and capital outlay for the generating plant that was required was delayed. As a direct result of energy management, carbon dioxide emissions were reduced substantially.

Jan 1, 1998

By D W. Airey

Frictional rock bolts are widely used because of their low cost. However, they have a thin wall section that makes them prone to corrosion, and they cannot be relied on to provide long-term ground support. It is difficult to assess the capacity after the bolts have been installed as they can only be pulled out if this has been allowed for during insertion. The questions of how long can the rock bolts function effectively and the effectiveness of various surface coatings, which can have significant cost implications are, investigated in this study.A series of accelerated corrosion tests have been performed on frictional rock bolts. The rock bolts, typically 900 mm long, have been inserted into concrete cylinders produced using a styrofoam insert to create the hole for the bolt insertion. Strata rock bolts with four surface coatings have been tested: uncoated black steel, galvanised, enduro (plastic coated) and coated with a proprietary aluminium/zinc alloy. Tests have been performed on two diameters of bolts. Following insertion of the bolts, the concrete cylinders were placed in a large drum filled with saltwater and current was applied to accelerate the corrosion process. The rock bolts were then extracted at various times after the commencement of corrosion. Comparison of the insertion and extraction resistances shows that corrosion initially increases the bolt resistance and that substantial section loss is required for the bolt resistance to drop significantly.CITATION:Airey, D W, 2014. Laboratory corrosion tests of frictional rock bolts, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 257–262 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

Remote sensing techniques can be used to map joint sets in a rock mass for the estimation of in situ block size distribution and improved optimisation of blasting. This paper reviews remote sensing using photogrammetry and laser mapping for mapping rock masses and presents elements of the analyses applied to data acquired with these mapping technologies. These techniques enable a user to map areas of hundreds of square metres rapidly with high precision. Using this data computer programs such as Sirojoint can provide estimates of joint position and orientation with orientation measurement accuracies better than one degree. The paper describes the use of remote mapping and provides potential users with a description of some of the advantages and limitations of the mapping techniques and the data they produce. Mapping of lithology and structure of rock masses is an important task required in many areas of mining and construction. It is a complex task routinely performed using established techniques developed to provide consistent results under a wide range of conditions. The techniques for data acquisition and analysis described in this paper enable more accurate mapping to be performed rapidly and enable mapping of inaccessible sections of a rock mass. These techniques will provide geologists and geotechnical engineers with more detailed, accurate data than previously available.

Jan 1, 2001

By B Muller

The disposal of tailings has become a greater issue due to the changing economics of mineral extraction. The processing of lower grade deposits and tougher environmental regulations has led to the selection process for tailings disposal options becoming more complicated. Current selection methods are too time consuming or too easily manipulated for inexperienced users to use successfully. This paper examines a different method for the initial selection of a tailings disposal system, using a numerical system that was introduced into the mining method selection field. The numerical method system was compiled by reviewing previous work done on the positive and negative aspects of the tailings disposal methods used by the coal and metallurgical mining industries. Assessing the common trends and design aspects of each of the methods was undertaken and a ranking was designed to explain how well suited the tailings disposal methods are to a situation. The tool successfully analysed sites using common data to indicate methods for disposal that would have provided minimal technical problems, low environmental risk and been practically possible. The tool also proved successful in identifying critical areas that would need further investigation. This new system was tested on some disaster case studies from around the world in order to show that it could have successfully selected a different method for tailings disposal that would have prevented the disaster.

Sep 26, 2011

By G Neely

COPING WITH COMPLEXITY In every industry, and mining is no exception, plant and processes increase in complexity over time and managers and operators need correspondingly more knowledge. The mine manager has to delegate details to operators, engineers, metallurgists, accountants, safety specialists, personnel officers and the rest. Is it reasonable then, to expect the Mines Inspector to be competent to judge the conduct of all these operations against the criterion of the regulations? Obviously not, but what are the alternatives? One is a superficial inspection where the inspector goes on a hazard hunt for broken steps and missing handrails. Another is one in which an army of specialist inspectors marches on a mine, sometimes outnumbering the staff. Each is competent to assess some part of the operation and if he or she can find an opposite number among the mine staff, they can discuss details. But what good does it achieve? The system acts to remedy present defects and to make recommendations which, if only they were followed, would prevent the same things happening again. Given that this process has been going on since the first Factory Act of about 1840, how is it that there are any more defects left to put right? The answer of course is that defects keep appearing, and new defects arise as fast as the old ones are found and corrected. Further progress can only be made by preventing defects at their source.

Jan 1, 1994

By L Gladysiewicz

This paper deals with the current situation in the mining industry in Poland. An overview of typical transport systems working in the different branches of mining is provided. The transport systems currently used in lignite mining, particularly in the Belchat=w mine û the largest brown coal mine in Poland, and those operating in copper mines are described in detail. New designs of belt conveyors used in underground hard coal and copper mining are presented.

Jan 1, 2003

By Henderson J, Ward RG

Dissolved oxygen has been measured directly using a rugged, reliable, accurate electrochemical probe system developed for steelworks application by B.H.P. Central Research Laboratories. Furnace measurements show that the steel is generally supersaturated with oxygen and that oxygen contents vary considerably from heat. to heat. Ladle measurements also show considerable heat-to-heat variations. Analysis in terms of ladle deoxidation chemistry differentiates between carbon monoxide controlled and manganese silicate controlled oxygen levels. Deviations from these levels are sometimes due to aluminium present in other added ladle alloys but in some cases the plant applicability of laboratory derived equilibria is questionable.

Jan 1, 1972

Carbonatites - igneous carbonate-silicate rocks - host the world's major resources for niobium, phosphorous and REE (rare earth elements).Carbonatites represent the least common products of mantle and igneous processes and their emplacement is principally controlled by lithospheric domes and rift structures. Intrusive carbonatites frequently comprise carbonate-amphibole-apatite-pyrocWore assemblages, occur as plugs, cores, dykes, sills sheets, veins, pipes and irregular bodies, are gecichemically anomalous (Ba, Ca, Cl, F, Hf, Mg, Nb, P, REE, S, Sc, SO4, Sri Tb, Ti, D, V, Zr), are associated with alkaline silica-undersaturated igneous rocks forming carbonatite complexes, and display large, intensive alteration haloes. Also carbonatites are similar to limestones, prone to weathering, and may form thick laterite profiles.Magmatic ores (pyrocWore, apatite, bastnaesite, monazite, magnetite, baddeleyite, phlogopite, fluorite, calcite) and weathering related residual and supergene ores (pyrochlore, apatite, magnetite, anatase, vermiculite) are currently being mined on all continents except Australia. Australia is underexplored for carbonatite associated primary magmatic and especially residual-supergene ore deposits. Chances are very high for the finding of new carbonatite, occurrences and associated ores.

Jan 1, 1994

The mining industry views with the utmost concern, legislative or administrative action that inherently reduces the scope for exploration activity. Is there any basis for this concern in relation to Victoria? This paper will outline the role of the Department of Minerals and Energy and the main features of legislative provisions affecting exploration effort. The practical difficulties that confront the Department and explorers alike will be examined. The importance of industry representation to influence the direction that policy and legislative review might take, will be highlighted. Above all, the paper will establish that one essential duty of government is to ensure the provision of appropriate mining titles and security of tenure.

Jan 1, 1982

By M Mee, R L. Gwyther

Accurate measurement of rock mass response during the mining of massive underground orebodies is essential, as mines become larger and deeper. These measurements enable: provision of quantitative data for optimal pit slope design and engineering; monitoring of the stability of deep pit slopes, the long-term integrity of shafts and large-scale underground infrastructure, and long-term measurements of deformation or rock mass creep following the mining process for environmental management. Strainmeters traditionally used for deformation measurement have neither the long-term stability nor the high sensitivity to perform measurements in these applications. This paper describes a new precision borehole strain monitoring system (GTS) currently deployed by CSIRO Exploration and Mining, which has the potential to solve these new issues in rock mass deformation monitoring. This technology was originally developed for use in hard rock mines (Gladwin, 1977) and refined considerably for earthquake research (Gladwin et al, 1994; Gwyther et al, 1992). A case study of the use of the GTS in monitoring longwall coal mining over the period 1993 - 1998 is presented.

Jan 1, 2000

By R B. Wanty

Historically, most investigations of biogeochemical cycling in acid rock drainage systems involved synoptic sampling over longer time periods (one sample per week or month) or intensive time series studies over a few hours or days. However, many important episodic loading events, such as seasonal meltwater and storm events occur on timescales that are rarely observed by these traditional sampling approaches. Monitoring these transient processes, which may contribute the bulk of the annual metal loading, is essential for accurate assessment in acid rock drainage areas. Recent work also has demonstrated dramatic diel (24 hour cycle) variations in trace metal concentrations in response to diel changes in temperature, pH, oxygen, and photochemical cycling (Brick and Moore, 1996; Nimick et al, in prep). To characterise a system that may respond to diel, seasonal, and episodic events, a monitoring program must sample at a frequency that captures the details of these major forcing events. We developed two novel instruments, the Zn-DigiScan and the DigiSampler to examine low and high frequency temporal changes in acid rock drainage areas. The Zn-DigiScan is a battery powered real time in situ chemical analyser designed for long-term deployments with hourly analyses of Zn. Stream physical parameters (temperature, conductivity, dissolved oxygen, pH, turbidity, etc) were measured every 15 minutes with a water quality sonde. The DigiSampler was developed for the long-term daily sampling of biogeochemically active elements and can take either discrete samples or samples integrated over 24 hours. The DigiSampler collects 2 ml samples in a Teflon coil which are separated by 0.2 ml nitrogen bubbles. The sample coil is returned to lab and the 2 ml samples are diluted 1:10 and analysed for trace metals by ICP-MS. Initial results from a three-day deployment at Fisher Creek, MT, USA have successfully demonstrated the ability of the Zn-DigiScan to record Zn concentrations at levels below 100 ¦g/L. Zinc concentrations measured at 30 minute intervals in Fisher Creek showed a diel cycle with low values of ~25 ¦g/L in the late afternoon and increasing to ~60 ¦g/L by early morning. Zn concentrations were inversely related to temperature and pH, suggesting that temperature and pH dependent adsorption was the main factor controlling diel Zn fluctuations. Initial deployment of the DigiSampler also was successful, revealing diel cycles in Zn, Cu, and Mn. Comparison of trace metal samples collected by the DigiSampler showed good agreement with samples collected by an Isco automated water sampler, demonstrating that the DigiSampler can collect clean samples for trace metal analysis at the low ¦g/L range.

Jan 1, 2003

The major technological advances of the last 30 years have profoundly reshaped mining practices. Machines keep getting bigger while productivity continues to increase and manning levels drop. These trends will continue and the introduction of breakthrough technologies will continue to accelerate, driven by a continued focus on lowering the cost of production, improving the productivity of workers and machines, and ensuring safer working environments. At the same time, global consolidation of mining companies has impacted on technology development in a range of ways. There are many potential technologies being proposed, some already operating in Australian mines. The automation of underground load-haul-dump (LHD) trucks for example, continues the process of removing workers from the most dangerous operating environments. Global positioning systems fitted to draglines, fibre optic communication channels, and 400 tonne trucks are only some examples of what lies ahead. However, where we need to return focus is to the technology of management û which is also one of the two key interrelated themes of this keynote address. Have we, as an industry, adequately been able to keep up with technological advances? Are our management systems as competent as the machinery we employ? The other key theme is the processes of globalisation and consolidation. What are the impacts on our industry? What are the implications of these processes, particularly for the ways in which we manage our people? My paper is divided into several components:some comments on the coal industry and the dramatic restructuring we have seen in recent years; in the context of this restructuring, an overview of my company and its evolution; my views on the role of contractors; some comments on the consolidation also occurring in the mining machinery and equipment, technology and services sectors; some observations on two major areas of technology û drill and blast; and trucks, shovels and excavators; the implications of consolidation and new technology for our employees and management; and finally some comments on research programs.

Jan 1, 2001

The three main types of iron ore deposits in Australia are bedded, massive and residual. Some character- istics of iron ore, important in its process behaviour, are related to its mineralogy which is a result of its geological history. World iron ore resources are extremely large but there are problems in quantifying re- serves, defined as that part of re- sources from which a useable commodity can be extracted economically. The relationship between the discovery and exploitation of iron ore resources and the process of industrialization is examined in historical and present day contexts.

Jan 1, 1976

By A Flatten, F Reusch

Recent advances in the disciplines involved in simulating large mining operations provide increasingly precise and accurate methods for the study of cave mechanics; however, in large regional-scale models, hydrological aspects are often neglected or studied independently from the mechanical problem. There exists a great demand for a unified approach to study and simulate both the mechanical and hydrological phenomena that allows for a more detailed understanding of the effects of groundwater flow, dewatering and the impact on block cave mining operations.This paper presents a numerical framework that combines three-dimensional regional-scale hydrological simulation techniques for groundwater flow, together with non-linear continuum–discontinuum rock mechanics models, provides such a unified modelling approach. The underlying simulation technique is based on a coupled parallel solution formulation adopting single-phase fluid flow formulations into a discontinuous, strain softening and dilatant finite element model. This approach is adopted for the presented case study of a realistic block caving example in a simplified unidirectional coupling formulation, to investigate the effects of the mechanical analysis on the hydrological response. Here, particular emphasis is on the non-linear coupling of the deformable and strain-softening solid skeleton and fluid phase; eg the change of hydraulic properties with evolution of damage in the rock mass and large-to-intermediate scale structures due to ongoing caving operations. The importance of discontinuum structures is discussed, as mining-induced fault reactivation significantly influences the hydrological response.CITATION:Flatten, A, Reusch, F and Beck, D, 2016. The application of hydromechanical mine-scale modelling for large block caving operations, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 341–348 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By P K. M Mazzoni, D Frantois-Bong

This paper aims to show alternatives to the estimation methods used for finding the parameters in GyÆs well known model for sampling variance in the case of particulate materials. Many experiments designed for gathering data on the sampling variance for specific mineral deposits allow the experimenter to use approximations in the calculation of the parameters of the mathematical model involved, which sometimes can be very useful. However, there are some instances where approximations lead to biased estimates of the parameters, and consequently, lead to errors in the establishment of the sampling protocol and treatment of quality control data. In the present work, an alternative is presented for computing the parameter values based in any experimental set up, without the need for any simplification. The method was derived using the method of least squares and evaluations are made using the usual tools in this kind of methodology: residual analysis and evaluation of the fit by means of a plot of calculated versus experimental variances. With the aid of these tools, one can better evaluate the structure of the experimental errors in such applications, and the adherence to the proposed model. In addition, it is possible to perform hypothesis testing for the equality of different sampling procedures in terms of sampling variance. The full mathematical details are given, together with an algorithm for applying the method, which can be implemented easily using any computer language. An illustration of the method is shown, considering the international work done in ISO/TC 102. This example is a determination of the minimum sample mass to be collected in iron ore shipments, in order to achieve a specified sampling precision.

Jan 1, 2005

By R A. Pax

Electrostatic separation is a core requirement for the beneficiation of mineral sands suites to provide valuable product. Although the basis of electrostatic separation has been understood for some time, the details required to be able to calculate the metallurgical performance of a separator has not previously been achieved from a mechanistic perspective. Empirical models have had some success but require extensive test work. Traditionally, performance of an electrostatic separator is determined by careful experimental work using the target mineral suite. Although electrostatic separation was invented at the end of the 19th century, very little modification of the basic equipment occurred until relatively recently, with the addition of a plate electrode to aid separation. Previously, the author has presented results, calculated using finite element modelling (FEM), of the electric fields present in an electrostatic separator in various configurations. This paper will present some new mathematical modelling work, which uses the FEM determined electric field configurations but also incorporates some fundamental physical processes that provide insight as to the limitations and opportunities for this important separation technique.

Oct 5, 2011

By K J ROSENGREN

Underground rock mechanics was initiated as a formal discipline in Australia by early studies for underground structures for the Snowy Mountains Scheme in the 1950s. These techniques were quickly embraced by underground mining and there has been steady development to the present time. The paper reviews the status of current techniques for rock mechanics studies and discusses some important issues such as ground support, mine filling and caving. It concludes that a considerable degree of engineering judgement is still required for the practical application of rock mechanics to underground mine design.

Jan 1, 1992

By L Alem

In the field of mineral extraction, complex technologies are being introduced in mines, operators/technicians rely on assistance from an expert (or more) in order to keep their machines functioning. Personnel with such expertise, however, are not always physically on-site. There is a growing need for innovative technological solutions to support effective delivery, just in time, of remote guidance between an offsite expert and an on-site maintenance operator. To meet this need, we have, as part of our Human System Integration project within the CSIRO’s Minerals Down Under (MDU), Transforming the Future Mine theme, explored the usefulness of a number of emerging technologies including: augmented reality, wearable systems and touch table interfaces. This paper presents ReMoTe, an augmented realty system for remote guiding using a touch table interface for the expert station and a combination of augmented reality and a wearable system at the operator end. In designing this system we were interested in exploring the extent to which it can increase the productivity and safety of maintenance personnel. This paper also presents Mobile ReMote, our recent development of a fully mobile remote guiding system. In Mobile ReMote, both the expert and the operator are using a near eye display and wearing a light computer in a back pack. The expert is able to guide the operator using his/her hands on the virtual display, while the operator is able to see the instructions on the rear eye display. Workers in the mining industry are highly mobile, a mobile expert and operator station will meet this need.

Nov 22, 2011

By Xizhen J

Point load testing for irregular rock specimens was studied to determine the relationship between tensile and compressive strengths, drill penetration rate and other rotary drilling parameters. The DH-l type point load tester was developed and more than 2 000 irregular specimens of over 60 kinds of rock from 16 mines and quarries were tested. The effects of size, shape and number of samples on the point load strength index were investigated, using regression analysis. Experiments were carried out to investigate the relationship between point load strength index and uniaxial compressive strength on 29 kinds of rock. The relationship between these values and the drill penetration rate for rotary and percussion drills is discussed.

Jan 1, 1986