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By D J. Brake

Most mine ventilation engineers are involved in ventilation planning and design in some capacity. Ventilation modelling software used by a competent experienced ventilation engineer is extremely useful in developing good ventilation designs by allowing assessment of a wide range of potential options. Unfortunately, ventilation modelling undertaken by persons who do not have sufficient experience or knowledge usually results in a façade that covers up a fundamentally unsatisfactory design. Ventilation models are produced for a wide variety of purposes including: fault-finding of a problem area in a mine and options analysis for resolution of such problems; a complete review or optimisation exercise of an entire mine’s ventilation system; or a much longer life-of-mine type of study. Models can be intended as the basis for studies with diverse purposes such as primary shaft or airway sizing, primary fan specification, examining re-entry times after blasting, resolving leakage or recirculation, or investigating the impact of fires or underground climate or cooling requirements. The concepts of ‘materiality’ and ‘fitness for purpose’ are essential to developing or using a ventilation model and serious mistakes have been made in wrongly using a ventilation model for purposes for which it was never intended, often because it is simply the most recent model on the mine site. Mistakes at this level often translate into faulty ventilation strategies and inefficient or ineffective use of scarce capital for ventilation projects. Validating a ventilation model is a time-consuming and expensive process and not every model must (or even should) be fully validated to meet the objectives at that time. This paper discusses the application of quality assurance in ventilation planning with particular respect to the ‘basis of design’ (BOD) as well as the standards for validating a ventilation model. It also provides a recommended way of dealing with non-conformances in measured versus modelled values of critical parameters in the model.CITATION:Brake, D J, 2015. Quality assurance standards for mine ventilation models and ventilation planning, in Proceedings The Australian Mine Ventilation Conference, pp 221–228 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By E Kunz

Decreasing the gas content in the worked seam by degassing before the start of winning has proven its worth in some areas of German hard coal mines. On the one hand, it removes the risk of gas/coal outbursts and on the other hand it reduces the gas inflow into the longwall. The underground experiences of the last 30 years have led to a æhit listÆ of coal seams with respect to their suitability to predegassing. Trials in the DMT laboratory and also results gained in the deposit show that the suitability of a seam for predegassing depends on its rank. In seams with volatile matter of 20 - 30 per cent, high efficiency ratings are achieved as a rule, with lower ratings both in seams with lower and with higher content of volatile matter.If the rock pressure is unusually high, the efficiency rating of the predegassing is lower, even in seams which would normally be suitable for this process. Under unfavourable conditions, for example below or above residual pillars, in-seam boreholes cannot be drilled successfully and the method is not practical. But if the worked seam was already stress relieved, the predegassing has an optimal efficiency. Latest investigations show that the distance between the in-seam boreholes can be extended. But in that case, the time necessary to reach the same reduction of the gas content increases considerably.

Jan 1, 2005

By I Swane, R Rait, A Robertson

Geochemical assessment of mine waste materials prior to commencement of a proposed mining operation is a fundamental component of mine feasibility studies and the regulatory approvals process. Static and kinetic geochemical test methodologies are widely used to predict the geochemical nature of mine waste materials and to develop strategies for managing potentially æhostileÆ materials. These data can also be integrated with data from other fundamental studies such as hydrogeology to predict specific environmental outcomes and potential impacts at mine closure and post-closure.A case study is presented for a proposed open pit gold mine in Mongolia, which illustrates how geochemical, hydrogeological and groundwater quality data can be used as part of a geochemical modelling process to predict the final pit lake water quality over time. A series of static and kinetic test geochemical test programs were completed and acquired data integrated with hydrogeological and groundwater quality data provided by the proponent. A widely used geochemical modelling program (PHREEQC) was used to develop the geochemical model and predict water chemistry in the pit void after mine closure. Sensitivity analyses were completed to explore the effects on the model output of groundwater to leachate water ratio, pit wall rock type and climate.Modelling has indicated that pit void water should be pH circum-neutral at mine closure and should remain within Mongolian and World Bank water quality guideline limits under the modelled simulation most likely to occur in the field. Final void water salinity is expected to increase eight fold over 14 years after end of mine life due to a continuous flux of salts (particularly sulfate salts) into the pit lake whilst the pit lake volume will remain relatively constant due to evaporation and a slow recharge rate. Dissolved metal and sulfate salt concentrations in pit water are also predicted to increase over time and could be moderately elevated compared to applied water quality guideline values. Some of the metal concentrations, however, may be lower as these would be expected to precipitate at circum-neutral pH and greater. Recommended additional assessment work on the project when mining commences includes determining the magnitude of adsorption and co-precipitation of metals occurring in the pit void water/sludge system.CITATION:Robertson, A, Rait, R and Swane, I, 2013. Geochemical assessment of mine waste materials and prediction of final pit lake water quality at a proposed gold mine in Mongolia, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 165-170 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By T Roberts, S Talu

Steel wire weld mesh is a common industry standard surface support used in underground mining, traditionally installed with mining drills during the bolting cycle. As underground mining depth and stress increase, mining methods and their sequences at these depths place challenges on conventional surface support options. These challenges have provided a need for high capacity surface support options that improve development efficiency, reduce the need for secondary ground support installation and is easily installed with current mining equipment. A 5m2 mesh testing machine was built, suspending a 9500kg concrete slab, designed with multiple hold down points to test varying bolting patterns. Mesh load and displacement is accurately measured using a data acquisition system which pushes against the restrained mesh module with an available 200kN load and 1200mm displacement capacity. A testing program comparing conventional surface support, straps and combinations of both were tested for baseline results. New module designs incorporating existing mesh types and new design concepts were manufactured to allow for single pass installation during a bolting cycle. Nine mesh types, mesh/strap combinations and new mesh module designs were compared using the same test method. Based on these results, two high capacity mesh module types are produced. This paper will detail the test program, load and displacement results and underground mesh module performance, describing the two high capacity mesh modules function within the development cycle and manual handling. CITATION:Roberts, T, Talu, S and Wang, Y, 2018. Design and testing of high capacity surface support, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 303–322 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By A Poliakov, E Donskoi, K Vining

The automated optical image analysis software Mineral4/Recognition4 (M4/R4) is capable of performing comprehensive characterisation of different materials throughout the iron ore value chain, including ore fines, lump, sinter, pellets and coke. It has been successfully used by CSIRO for industrial and research projects and has been independently licensed to several world leaders in iron ore production and ironmaking. The M4/R4 software was strongly integrated with a Zeiss microscope to make use of the company’s powerful AxioVision software. This required users to own both Zeiss microscope hardware and AxioVision software in order to be able to use M4/R4 to its full image acquisition and analysis capacity. Therefore, it was not available to the users of equipment produced by other major microscope manufacturers. In recent times however, Zeiss has indicated that the AxioVision software will no longer be supported. To overcome this limitation, CSIRO has proceeded with the next generation of this software, Mineral5/Recognition5 (M5/R5). Importantly, the M5/R5 system has been developed without any dependence on a specific microscope hardware/software platform. Furthermore, the image analysis functionality is now based on openCV open access software and has been fully rewritten using stateof- the-art software development tools to allow reading and processing of all major image formats. Although past applications have been specific to iron ore and ironmaking applications, other improvements, such as an increased number of minerals allowing better gangue segmentation, flexible mineral definitions, improved software modules behaviour and refined analysis routines enables the platform independent M5/R5 image analysis system to be used by researchers in any area of mineralogical or materials research.

Nov 8, 2021

By A Dennis, T Hunter, R Coleman

For metallurgical plant design, it is necessary to progress through successive phases of test work, piloting and process development before involving all the other engineering disciplines and “freezing” the process design criteria and flow sheet. This process usually relies upon the experience, skills and personal preferences of various technology providers, study and engineering entities, test work and metallurgical laboratories and, most importantly, the owner’s team and its operators. Current industry trends include lower grades, more complex orebodies, geometallurgy in defining orebody variation and design envelopes, more common “hybrid” plant processes and the market demands for more reliable, timely and predictable early plant performance.This paper will discuss interaction of these trends and provide guidelines for the level of detail and technical complexity required for a number of different “typical” examples. The paper will pay particular attention to the study definition level translated into the required detail and certainty needed by the overall process “owner” and original equipment manufacturer (OEM) equipment suppliers to ensure the best real plant performance. Some recent case studies will be discussed. In many projects, at a late stage of project definition, it has become common practice to undertake a “value engineering” phase. Although it could be argued that this should be undertaken earlier, it is largely driven by an overall need to reduce capex and “optimise” the perceived “fat” built into the project during the detailed design process. This value engineering can be very counterproductive to project timing and operational performance and warrants discussion.The paper is intended to promote discussion on a topic of wide interest. The authors’ diverse backgrounds and experiences are integral to the views in this paper.CITATION:Dennis, A, Coleman, R and Hunter, T, 2017. Critical process design considerations from test work to operations, in Proceedings MetPlant 2017, pp 12–30 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By A B. Jahed, Ö Aydan, T Ito

In this study, the authors compiled some case history data and present some typical examples of rock slope stability issues in Afghanistan with a special emphasis on Kandahar region and categorise rock slope failures according to the principles of modern rock slope engineering. The slopes considered involve rock-cut, natural rock slopes mainly. The effect of structural geology and discontinuous nature of rock mass on both slope-cuts and natural rock slopes is taken into account and some preliminary assessments on the stable and unstable rock slopes are presented. Furthermore, the seismic effect on their stability is also considered. It is also pointed out that similar issues could be observed in open pit mines, which may be exploited in years to come.

Nov 29, 2022

By S Maryati

Surface mining activities disturb large areas, produce great sediment loads and tend to be a source of water pollution if they are not managed properly. Coal mining in Indonesia has a very high risk of soil erosion because the coal mining areas are generally located in tropical areas with a high average of rainfall (4000 - 6000 mm/year) and use surface mining methods. The main factors affecting erosion risk are climate, soil type, topography, vegetation cover and management factors. Thus, the monitoring of erosion risk in mining areas is very important due to the characteristics of coal mining in Indonesia. The objective of this research is to determine the ability of satellite images (remote sensing data) and geographic information systems (GIS) to provide an accurate and up to date spatial database for the monitoring of erosion risk in surface coal mining areas using the Universal Soil Loss Equation (USLE) method.The erosion risk analysis and spatial data processing are generated by the ArcGIS 9.3 software and need several data, namely: an erosivity map, erodibility map, a slope map, vegetation index map and land management or land cover map. The erosivity map is derived from the rainfall data, whereas the erodibility map is derived from the soil map. The slope map is derived from the SRTM-DEM (Shuttle Radar Topography Mission-Digital Elevation Model) and processed using 3D analyst tools. Furthermore, the vegetation index map and land cover map are derived from a satellite image using digital image processing techniques.This preliminary study produced results that show soil erosion monitoring, which is integrated with remote sensing and GIS technologies, has great potential for producing accurate, advance, and low cost erosion risk maps in coal mining areas. This map is very important for getting spatial distributions of the erosion and useful for developing erosion management plans.

Nov 22, 2011

By S N SHEARD

The use of geophysics in mineral exploration in Australia, and overseas, has increased dramatically over this century. This paper shows that using simple equipment with clever interpretation that the foundations of modem geophysics were laid, using all the same principles. The plethora and diversity of mineral exploration geophysical techniques does not allow a full description of their evolution to be given in such a paper. To convey this evolution, however, the progress of two different geophysical methods, magnetics - a potential field (passive) method, and electromagnetics - an electrical (active) method, are described. Examples of magnetic survey data from the 1920s and more recent vehicle home and airborne surveys are given to show the increase in data quality through technological improvement. A set of four airborne electromagnetic data sets spanning three decades is used to indicate the improvement in electromagnetic techniques. It is argued, that considerable progress is still required in the electromagnetic field to increase its interpretability.

Jan 1, 1992

By S C. Dominy, R C. A Minnitt

Determination of the sampling constant and liberation diameter are of importance when applying the Fundamental Sampling Error (FSE) equation to optimise sampling protocols. The method for the direct determination of the sampling constant is based on the æGy 50-pieceÆ experiment and variants thereof, which is generally known as the heterogeneity test. In the coarse gold environment, the heterogeneity test is prone to poor repeatability and bias due to the very heterogeneity that it aims to quantify. A key issue is the large sample mass that can be required in the coarse gold environment, which may reach 1 t or more. The heterogeneity test often provides an evaluation of the background gold grade heterogeneity, but understates that of the high-grade coarse-gold component. This is because the total mass of fragments is usually too small to represent the mineralisation. Despite this relatively well-known problem, heterogeneity tests are often undertaken on deposits where the presence of coarse gold is ignored, not fully realised or vastly understated. Sampling types and protocol designs are frequently based on poor quality data that do not match the characteristics of the orebody. For this style of mineralisation, an empirical approach to define ore characteristics is recommended.CITATION:Dominy, S C and Minnitt, R C A, 2012. Application of heterogeneity testing to coarse gold ores, in Proceedings Sampling 2012 , pp 143-160 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By Kissell F. N, Volkwein J. C

The U.S. Department of Interior's Bureau of Mines has the opportunity to visit many U.S. mines, including some that claim 2 to 5 times the national average of 334 raw tonnes/unit shift (tps) from a continuous miner section. In a project to assess the reasons for this high production, the Bureau conducted two studies. The first study focused on the 25 highest producing continuous miner sections. What stood out during the visits-was the quality of the labor-management relations. In each of the mines there was a positive labor/management relationship based on mutual trust and a sense that the employees were the company's most valuable resource. Discussions with labor revealed a universally positive attitude toward the company. Interviews with the mine superintendents invariably ranked the quality and attitude of workers as more important than anything else. Also during the mine visits of the 25- mine study, no engineering factors obviously stood out. Time at the face was greater than average, most were in coal over 1.52 m and the roof was generally good. Also, none of the 25 mines had to contend with high methane levels. Because this study found that a high percentage of mines were in seams less than 1.52 m thick, the second study examined thin seam mines only.

Jan 1, 1988

The gossan developed from the Whim Creek Cu-Zn-Pb-Ag sulphide deposit, in the Pilbara region of Western Australia, occurs near the top of a ridge in a dissected plateau 01 moderate relief. The gossan is characterized by the abundance of secondary ore minerals which indicates that it is relatively immature, due to climatic conditions and erosional stripping.The abundant presence of secondary carbonates indicates that the low pH generally resulting from sulphide oxidation has been neutralized, probably by the buffering effect of carbonatcs and silicates. Fe, Cu, Pb, 'Ag and Sn have been enriched in the gossan relative to the primary ore, and Mn, Ti, Co and Ni have been strongly depleted; other elements have remained substantially unchanged. The gossan has a strong gcochemical signature characterized by high Cu, Zn, Pb, As, Sb, Sn, Ag and Mo coutents. Boxwork textures are poorly developed, bu't the gossan has other diagnostic mineralogical features including sulphide inclusions in quartz and the presence of residual cassiterite.

Jan 1, 1982

By K Edwards, A J. J Mouton

Hematite represents the vast majority of iron ore exported from Australia as the development and processing cost of magnetite is generally seen as a barrier to the development of vast magnetite resources. However, a number of magnetite projects have attracted a significant amount of interest and investment from large Chinese steelmakers.This paper compares the relative merits of the development of Australian magnetite and hematite ore from the point of view of the steelmaker, taking into account the factors that influence the capital costs of the development of the ore types and the relative costs of operating the process plants to treat these ores. By modelling the relative operating cost for the production of hot rolled coil in China for the two ore categories, the paper demonstrates the economic drivers behind the Chinese steelmakers’ large investments in the magnetite resources of Western Australia. It does this by estimating the potential value of magnetite concentrate to the steelmaker in the event that the maximum potential is realised by operating the blast furnace with a 100 per cent pellet burden.Under the conditions described, it was found that direct reduction (DR)-grade magnetite concentrate could command a price premium over 62 per cent Fe fines of up to 46 per cent (December 2014 on a cost and freight (CFR) basis). The corresponding premium for blast furnace (BF)-grade magnetite concentrate is 17 per cent, which demonstrates the dependency on grade.The capital expenses for a 14 Mt/a concentrate plant is estimated at US$3.1 B for BF-grade magnetite and US$3.35 B for DR-grade, with operating expenses at US$45 and US$50 respectively. The corresponding free on board price for a break-even net present value is calculated at US$82/t for BF-grade magnetite and US$90/t for DR-grade. The minimum long-term iron ore price (62 per cent Fe) that would be required to underpin such a project is estimated at US$78/t CFR for BF-grade magnetite and US$68/t CFR for DR-grade concentrate.Apart from the financial benefits, it is demonstrated that the use of magnetite concentrate in ironmaking has the potential to reduce CO2 emissions by approximately 400 kg per tonne of hot rolled coil.CITATION:Mouton, A J J and Edwards, K, 2015. Magnetite – a higher-grade blast furnace feed and its potential benefits for the ironmaker, in Proceedings Iron Ore 2015, pp 613–620 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By S Zummar, A Van den Bulck, T De Staercke, T Van Rompaey

An increase of 22 per cent in lead usage is expected in the European Union by 2050. During lead refining, the Harris process is a critical step in which a salt melt is used to remove arsenic, tin and antimony. During this process, the caustic salt melt absorbs these impurities, requiring regular evacuation before saturation. Current metallurgical practices for: 1) determining the end point of the lead alloy involve time-consuming sampling and offline analysis, and 2) determining the end point of the caustic salt melt are based on subjective visual observations by the operator. In the context of Industry 4.0 concept, automating these processes becomes desirable, as smart sensors systematically collect real-time data in an unbiased manner. This research focuses on monitoring the Harris refining process using objective methodologies. Two different methodologies are investigated. The first methodology focuses on electrical conductivity changes of the caustic salt melt as function of Sb content. For this study, synthetic and industrial samples are used. A lab-scale electrical conductivity set-up was built to accommodate the aggressiveness of the salt melt. Initial findings suggest a promising relationship between electrical conductivity and Sb content in the caustic salt melt. Although the results are preliminary, the study provides valuable insights by enabling real-time measurements. The second methodology focuses on measuring the electromotive force (EMF) in lead doped with Sb at pilot-scale. Multiple probes are reevaluated for their effectiveness in Sb measurement. Ultimately, a partially stabilised MgO probe with Ni as a reference, without cardboard and copper protection caps, yields promising results. A correlation between EMF and Sb content is observed. However, repeatability issues arise due to possible wire interference at low temperatures. The results underscore the potential of advanced measurement techniques in optimising lead alloy production within the context of Industry 4.0.

Aug 21, 2024

Hard rock TBMs are very often open machine layouts, with just a part roof shield over the front of the machine. The whole system is designed for fast face advance and the economy of the project often depends entirely on the rate of advance. Typically, hard rock conditions will demonstrate stable and good ground for a major part of the tunnel. However, short sections of crushed shear zones with clay and gouge material may cause serious time delays. Spiling rock bolting has been proven to be very efficient under such circumstances, provided the fully grouted rebar bolts can be placed in a controlled and practical manner.Environmental restrictions are becoming more and more a part of tunnel excavation projects. Even hard rock TBM tunnelling may require a strict ground water control, because of consequences on the ground surface from lowering the ground water level. Such consequences may be surface settlement, negative influence on ground water resources or damage to vegetation.Pressure injection ahead of the advancing tunnel face (in this paper named pre-injection), using microfine cement and chemical grouts, is today a proven technology. As examples can be mentioned (Garshol, 1997) about 100 km of pre-injected tunnels below Oslo City and about the same length of subsea tunnelling elsewhere in Norway. Examples from other parts of the world are also available, like below Stockholm, Sweden, the Inland Feeder project and Hollywood Metro both in Southern California.To take advantage of spiling rockbolts and pre-injection, it is an obvious prerequisite to be able to drill the necessary boreholes in the right positions and at the correct angle. In drill and blast excavation this is simple, but in TBM projects it has repeatedly turned out to be difficult. More than once owners have accepted bids containing reassurance from the contractor that the drilling method will be sorted out later. Experience shows that if ælaterÆ means after start of the TBM operation, it is often too late.

Jan 1, 1999

By A H. Bagherieh, S Mesroghli, H Jorjani, S Chehreh Chelgani

The rare earth elements (REEs) assay and recovery in leaching processes is being determined using expensive analytical methods, ICP-AES, and ICP-MS. This paper presents a neural network model to predict the effects of operational variables on the lanthanum, cerium, yttrium, neodymium recovery in the leaching of apatite concentrate. The effects of leaching times: ten to 40 min, pulp densities: 30 to 50 per cent, acid concentrations: 20 to 60 per cent and agitation rates: 100 to 200 rpm were investigated and optimised on REEs recovery in laboratory at a leaching temperature of 60¦C. The obtained data, on the laboratory optimisation process were used for training and testing of a neural network. A feed-forward artificial neural network with 4-5-5-1 arrangement, was capable of estimating the REEs leaching recovery. Neural network predicted values were in good agreement with the experimental results. The correlations of R = 1 in training stages, and R =  0.971, 0.952, 0.985 and 0.98 in testing stages were results for Ce, Nd, La and Y recovery predictions respectively and that theses values are considerably acceptable. It was shown that the proposed neural network model accurately reproduces all the effects of operation variables, and can be used in the simulation of a REEs leaching plant.

Jan 1, 2008

By D J. Thobaven

Project financing challenges caused by declining commodity prices have heightened the need to improve project metrics such as minimising capital payback and maximising net present value (NPV). Khnaiguiyah Mining Company (KMC) recognised the need to improve early cash flows at their Khnaiguiyah zinc-copper project after initial studies showed the project could not provide the desired financial outcomes necessary to compete for investment dollars in the current market.A significant improvement to the project cash flow in early years was realised through simultaneous optimisation of cut-off grade, mining sequence and strategic stockpiling. This improvement was achieved by accelerating mining in the pits, stockpiling lower value material and feeding higher value material directly to the plant. The schedule required higher mining and stockpile capacities than the sequential mine plan although minimal change occurred in the definition of ore and waste as measured by tonnes and grade. The practicality of the strategic schedule was demonstrated by implementation in the production plan with excellent conformance.CITATION:Thobaven, D J, 2014. An application of simultaneous optimisation – improving the payback period of a zinc-copper open cut project, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 137–144 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By Y Gu, R Fandrich

Traditionally, characterisation of the mineralogy and textures of ore and rock samples were based on observations of hand specimens and thin sections using an optical microscope. The extent of the data collection was limited by the available tools and thus variations in mineralogy and texture were generally not described by quantitative data. These qualitative to semi-quantitative approaches, even though well established over the years, resulted in variable observations and data sets. The data were unlikely to be representative of a sample and limited statistical validity meant the results could not be reliably used in modern digital mining design and planning. With recently developed SEM based quantitative mineralogy tools and the corresponding methodologies, ore textures can be quantified and compared numerically. The numerical data can not only enhance the understanding of an orebody in geological terms, but can also be used in the creation of metallurgical models for mine and mineral processing design and simulation. These capabilities provide valuable inputs to risk assessment studies and the evaluation of mineral projects.

Jan 1, 2007

Two key elements in the design of a pastefill or high density backfill system are the preparation of the backfill material and its distribution underground. This paper examines these two areas. Owing to the essentially impervious nature of total mill tailings, preparation of pastefill and high density fill from current tailings involves a physical dewatering process. There are currently three methods available for this process: Vacuum or pressure filters. These represent the ætraditionalÆ approach to the preparation of pastefill. Paste production storage mechanism. This is a thickening/storage mechanism developed with the specific objective of producingpaste/high density backfills. Fluidization. This system utilises silos fitted with simple dewatering devices and nozzles. Recently developed by CANMET, it provides the simplest and most economical approach.This paper describes and compares the three preparation methods, from a practical and an economic point of view. Once the pastefill/high density fill has been prepared and binder added, the backfill must be distributed underground into the stopes. A fundamental factor in the design of a distribution system is the rheology of the material. No two materials will exhibit the same properties, and a sequence of rheological and related testing is required prior to the completion of the design of the underground distribution system. This paper covers the testwork normally required and discusses the fundamental design parameters of pastefill distribution systems. The final section of this paper summarises the use of pastefill at three mines in Canada.

Jan 1, 1998

By J Jardine

An improved ground support method for development intersections, wide spans and stope brows was implemented at Kanmantoo mine. The method uses a jumbo to simultaneously drill and install self-drilling anchors (SDAs) to depths from 4.5 m to 7.0 m. Resin is subsequently pumped into each SDA using a specially designed integrated tool carrier basket, with plating occurring within 10 mins due to rapid resin cure. This methodology means that SDAs can be installed rapidly due to reduced process steps and wait times with reduced hazards to personnel. Cablebolts are used extensively in underground mines to reinforce the ground in wide spans, such as at intersections and stope brows. The flexible cablebolt tendon allows for a long, continuous and high-capacity reinforcing element to be inserted into the rock. A common cablebolt installation practice at Australian underground mines that do not utilise a mechanised cable bolter, is for cablebolt holes to be drilled by a jumbo or longhole rig, hand installation and grouting by a service crew, then plate tensioning following a grout curing wait time of typically 12 to 24 hours. This process involves multiple separate labour-intensive work processes and results in reduced availability of priority headings. This paper discusses the development history of vertical SDA use in wide spans at Kanmantoo mine. The installation process is fully described, including aspects such as reliable in-hole coupling of SDAs, resin selection and pumping aspects. A cost benefit assessment, and a case for ground stability are presented to compare cablebolt use to SDAs in development intersections.

Mar 29, 2023