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Increasing demands on quality of metallurgical grade alumina and for lower production costs led to the development of a new fluid bed calcining process. The process, jointly developed in Germany by Vereinigte Aluminium Werke A.G. and Lurgi Gesellschaften m.b.H., takes advantage of modern chemical engineering methods such as counter-current flow of combustion air and solids, direct heat-exchange between combustion air and fine solids and near stoichiometric combustion of oil in a fluid bed. Using a two-stage Venturi-type suspension preheater for heat-recovery from combustion flue- gases, the circulating fluid bed technique with internal oil combustion at 2.2000 F for the calcining step and 'a five-stage fluidized bed cooler for heat recovery from calcines, the process gives an outstanding heat- efficiency. In a first industrial plant for 560 sh. t. alumina per day heat consumption figures of less than 1.400 BTU/lb A12O3 were achieved.

Jan 1, 1971

Orebodies in the Mt. Charlotte-Hannan's North area N. and E. of the town of Kalgoorlie provide a marked contrast to the pyritetelluride lodes of the Golden Mile, although both groups of orebodies appear to be fundamentally related.These highly siliceous telluride-free orebodies N. of the Golden Mile are closely related to strong oblique faulting. The Golden Mile lodes, while possessing an apparent overall relationship to the oblique faults also have a close relationship to E. dipping strike faults.INTRODUCTIONThe Mt. Charlotte-Hannan's North area lies N. and E. of the town of Kalgoorlie and is separated from the Golden Mile by the Golden Pike fault. The orebodies discussed lie in an area approximately 3 miles long by 1 mile wide (Fig. 1).The area includes the site of the original discovery of gold in the Kalgoorlie district in 1893. There have been numerous mining operations over the years, the bulk of the production coming from two orebodies, Mt. Charlotte and Hannan's North. These have provided approximately 900,000 tons of the 1,100,000 tons of ore mined in the area.Production to date from the principal orebodies in the area has been as follows.1. Hannan's North orebody, 582,000 tons of ore for 275,000 oz of gold2. Mt. Charlotte orebody, approximately 230,000 tons for 75,000 oz3. Pharlap and Golden Goose orebodies, each orebody approximately 8,000 tons for 2,700 oz4. Maritana Hill orebodies, approximately 170,000 tons for 70,000 oz...

Jan 1, 1965

By K W. Mills, N R. P Baczynski, J Mylvaganam, D A. Prado, M F. Lee, I A. de Bruyn

"This paper presents the second part of a study of the assessment of rock stress inputs on the performance of various new mining designs at the Ok Tedi large open pit mine in Papua New Guinea. Over the years, four programs of rock stress measurement have been completed at Ok Tedi, each providing different interpretations of the in situ field stresses. Details of three of these programs and interpretations are provided in the precursor to this paper, entitled ‘Rock Stresses at Ok Tedi, Papua New Guinea’ (Lee et al, 2014).This paper explains how the various stress interpretations were utilised in the modelling of the proposed new open pit and underground mining excavations, comparing where possible their expected effects on stability. The modelled performance of three specific mine components have been discussed here as case studies, including: the below-pit drainage tunnel, as the floor of the open pit workings is mined down from 350?m above, to within just 75?m above the crown of the tunnel the stability of the 1000?m high slope of the proposed West Wall cutback the proposed sublevel open stoping extraction sequence in the Gold Coast orebody beneath the East Wall, for which only the likely ‘worst-case’ stress regime was used to assess sequencing and stability issues.The benefits of scheduling the collection of detailed rock stress measurements and other input data from a range of different sources at various stages of the projects are discussed.Alternative in situ stress models have less stability impact on open pit slopes than on underground mine excavations.CITATION:de Bruyn, I A, Baczynski, N R P, Lee, M F, Mills, K W, Mylvaganam, J, and Prado, D A, 2014. The application of rock stress inputs to stability assessments at Ok Tedi Mine, Papua New Guinea, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference, pp 43–54 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 5, 2014

The metals titanium and zirconium and their alloys occupy individually unique positions in the catalogue of metallic materials available for engineering applications. Because of the uniqueness of their usage in the aerospace industry, in the case of titanium, and in the nuclear industry, in the case of zirconium, the except- ional resistance of both the metals to the majority of corrosive media is often overlooked. The cost factor in the application of these more exotic metals has, in the past, been a major considerat- ion in the rejection of titanium and zirconium as constructional materials in areas of usage where their superior corrosion resistance strongly favoured them over more conventional metals and alloys. The cost differential, vis-a-vis austenitic stainless steels, for example, is not a trifling matter, being of the order of 6 : 1, when compared on a weight basis. However, if one considers the cost, for, say, sheet product on an area basis, the ratio is redgced to approximately 3.4:1. If one also takes into account the enhanced performance of the more expensive material and the sub- sequent increase in service life and decrease in plant down-time, the economics of the usage of materials such as titanium becomes much more attractive and, indeed, highly competitive,

Jan 1, 1969

Newmont Australia Limited has for some 15 years mined a number of large open cuts associated with the Telfer Gold Dome deposits. The principal ore body exploited has been the East Flank of the Main Dome where a very high grade gold reef deposit of mixed metal sulphides, grades in excess of 20gA Au, has been mined in conjunction with dissemi- nated mineralisation contained in the overburden material. The main ore body has been under review for some years as an under- ground mine, however due to the ore body widths of less than 1 metre and a dip generally less than 35 degrees and a very weak host rocks earlier studies all resulted in a continuation of open pit mining activities. In early 1988 it was recognised that open cast mining would not be able to mine all of this valuable resource and a feasibility study was commenced to come up with a practical and economic approach to underground mining.

Jan 1, 1991

By Whiten WJ, Narayanan S

Data from ball mills of a wide range of sizes are analysed using detailed mathematical models and non-linear least squares fitting techniques. This analysis reveals that the relative power inefficiency of large ball mills is due to inefficient grinding of coarse (plus 4 mm) particles in these mills. A qualitative physical hypothesis is proposed to explain this behaviour. The results of the analysis can be used to scale up ball mill behaviour, using the mathematical models and techniques developed. A simpler ball mill scale-up procedure is also proposed, and its limitations stated. Laboratory experiments are being conducted to determine the average size distributions of single particles of different ores after breaKage. These experiments can distinguish between the different ores, and it is hoped to use their results to model and predict the grinding of different ores in ball Mills.

Jan 1, 1978

By D P. Blair

The theme of this conference is blasting productivity. This article only considers the technology aspect of this theme, and in particular, the collection and analysis of experimental data. In many cases, field trials are set up to collect data on variables such as fragmentation and vibration with the aim of comparing different explosive products and/or blast designs. An important aspect of such trials is the collection of sufficient data to draw sound conclusions. In this regard, there is no doubt that the scatter in real data is the root cause of all problems of obtaining misleading results due to an insufficient number of trials. This article shows that the typical one-off trial has a high probability of producing misleading information, which could be considered to be worse than having no information at all. Assuming that sufficient data has been collected, this article also highlights the methods that can be used to make the most of that data. These methods include the application of appropriate statistics that are dependent on the nature of the scatter in the data, and the use of some of the more recent filtering and spectral approaches that can be used to reduce the noise in measured blast signals and increase the resolution of their spectral characteristics.

Nov 8, 2011

By B Taylor, S Evans

Bulk explosive technology for underground mining has not seen any significant technological advances since the widespread transition from ammonium nitrate fuel oil (ANFO) to ammonium nitrate emulsions (ANE) commencing in the 1980s. The in-hole energy profile that conventional ANE systems deliver is limited by the physics of chemical gassing and simple control systems. This compromises the range, precision, and accuracy of energy delivery into the blasthole, and in some cases limits the length of charge that can be delivered. Orica’s 4D™ bulk system removes many of these constraints, enabling better blasting performance across all underground mining methods. This paper reviews work completed at three mining operations across Australia, the United States, and Chile with a focus on how this system can improve mining operations and deliver sustained commercial and productivity benefits into the future. These benefits include improved ore recovery, reduced dilution from waste rock, and reduced overall explosives consumption. This paper also reviews how this new technology can be applied for planning future mining operations.

Sep 1, 2024

By H Zhang, Y Wang, S Sukenaga, H W. Ni, H Shibata, W Z. Mu

The crystallisation behaviour of low melting point CaO-SiO2-Al2O3-MgO inclusions greatly affect the deformability of inclusions during the rolling process. The crystallisation characteristics of CaO-SiO2- Al2O3-MgO melts representing the oxide inclusions in Si-Mn killed steel were systematically investigated. The effect of Al2O3 and MgO contents on the crystallisation change were analysed under a fixed CaO/SiO2 in the complex inclusions. The continuous-cooling-transformation (CCT) and time-temperature-transformation (TTT) experiments were conducted. The results showed that the increase of MgO content increases the crystallisation ability of CaO-SiO2-Al2O3-MgO inclusions, while the increase of Al2O3 content has the opposite effect. The viscosity, liquidus temperature of oxide melt and also the initial crystallisation potential might be the reasons for the change in crystallisation behaviour. Also, the crystallisation activation energy could semi-quantitatively characterise the crystal growth during the crystallisation of inclusions. To obtain low melting point plasticized CaO-SiO2-Al2O3-MgO (CaO/SiO2=1) system inclusions, the Al2O3 content of the system needs to be controlled larger than 15 wt per cent and the MgO content should be kept at a small amount.

Aug 21, 2024

By M Pyle, R Ch, T Vizcarra, ramohan, G Lane, G Ballantyne

Preconcentration, through gravity separation (Wallace et al, 2015), magnetic separation and particle size (Clout, 2013), has been used in many historical projects to convert low grade material into ore. More recently, pre-concentration technologies such as bulk sorting (Kurth, 2017), screening (Bearman, 2014) and coarse particle flotation (Vollert et al, 2019) have also demonstrated their ability to progressively reject waste through the value chain. These technologies can not only deliver stepchange improvements to the economics of mining operations, but can transform the environmental and social aspects by minimising water and energy consumption and significantly reduce the quantity of fine tailings produced. However, implementing progressive waste rejection requires technologies and approaches to be combined and applied in the right way to capture the value. From a technical perspective, progressive waste rejection introduces challenges related to the orebody, equipment performance, engineering and understanding the value chain from the resource through to final product. From a management perspective, the key issues are related to people and processes, in particular; motivating the business, challenging the paradigms, and introducing new ways of operating within the constraint of existing management structures to manage risks and minimise lost opportunity costs. This combination of technical and management issues means that progressive waste rejection is a complex undertaking for mining companies, yet the reward for the business and other stakeholders is potentially high and should not be ignored. This paper presents how progressive waste rejection can offer step-change improvements to the business case for high and low grade greenfield and brownfield projects based on case studies completed by Ausenco. The paper then outlines different implementation approaches from concept studies to execution to address the various technical and management challenges outlined above.

Nov 10, 2020

By G Davison, C Rossimel, M Bouazza

Expanding rock bolts anchor within a rock mass more efficiently than non-expanding varieties. This is of great importance in weak ground conditions, where grouted friction bolts perform less efficiently than in good ground conditions. Filling a Split Set with demolition concrete has been shown to double the load-carrying capacity when compared to conventional use of Split Sets. This report details verification of these results by installing and pull-testing 14 Split Sets of varying grout conditions within in a fault zone. These Expanding Split Sets achieved loads double and triple that of ungrouted and normally grouted conventional Split Sets. A literature review and chemical analysis were conducted to understand the expansion process better. It was found that 20 per cent more calcium is included in expanding cement, which is responsible for its growth. Factors most affecting the expansion process were identified. Furthermore, the expansion rate of a bolt outside a borehole was measured and 6 mm of expansion across its diameter was found. The compressive properties of the cement were compared with other types, due to expanding cement becoming uncohesive after the expansion process is complete. When confined within a Split Set, compression testing demonstrated that this grout is just as strong and rigid as normal grout. Finally, the bolts were tested by shear and it was found that the Expanding Split Set (ESS) has a similar shear capacity to grouted Split Sets, which is 70 per cent higher than that of ungrouted Split Sets. These results enabled the mechanism for improved performance in weak ground conditions to be verified. Expanding grout will expand the Split Set into its borehole of varying diameter and lock it into place, creating increased friction and resistance to pull-out. This paper shows that ESSs can be a useful reinforcement technique in weak ground conditions.CITATION:Rossimel, C, Davison, G and Bouazza, M, 2014. An investigation of expanding split sets in weak ground, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 159–170 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By R R. Lovel, G J. Sparrow

Currently there are large reserves of good quality iron ore near to existing infrastructure that are not being developed because the phosphorous levels are above acceptable market specifications. Since the high phosphorous content is considered to be mainly associated with the goethite fractions of the ore, attempts were made to leach the phosphorous from the ore after a heat treatment to dehydroxylate the goethite. Heating the ore and leaching with 40 g/L NaOH lowered the phosphorous levels from 0.145 wt per cent P to 0.075 wt per cent P or lower, but a heating temperature over 800¦C was required to achieve this reduction in phosphorous levels. However, when sodium hydroxide was added to the iron ore before the heat treatment, similar phosphorous removal was achieved with a heating temperature of 300 - 350¦C. It was considered that dehydroxylation of the goethite in the presence of the hydroxide makes the phosphorous available for removal with a water leach. As well, 50 per cent of the silica and 60 per cent of the alumina in the ore were also removed in the leach, but some sodium remained in the leach product. Further work is required to remove the residual sodium to produce a marketable product.

Jan 1, 2009

By Y Xie, L O’Connor, S C. Dominy

"Sheeted vein gold deposits are characterised by multiple subparallel veins and free milling gold. In situ heterogeneity of mineralisation results in grade and process parameter variability, which will increase project risk. Measured variability is often enhanced by poorly designed sampling and test work protocols. Protocols that are optimised within the framework of the theory of sampling to suit the ore type, together with quality assurance/quality control systems, will reduce variability and provide fit-for-purpose results. The geometallurgical approach requires spatially distributed samples within a deposit to support variability modelling. Diverse attributes from core logging, mineralogical/textural determination and small-scale tests are used to measure variability. This contribution emphasises early stage geometallurgical intervention during project development. It presents a discussion of representative sampling in the context of the theory of sampling. A case study presents a protocol that exemplifies how data can be gained from a well-designed and planned program to support a resource estimate and prefeasibility study.CITATION:Dominy, S C, O’Connor, L and Xie, Y, 2016. Sampling and Test Work Protocol Development for Geometallurgical Characterisation of a Sheeted Vein Gold Deposit, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 97–112 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By J Coombes, R Sterk

The efficiency of the Australian and New Zealand stock exchanges relies on a fully informed market: shareholders and investors are fully and transparently informed of all material information relating to the shares. These principles of transparency and materiality are similarly core to the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves (the JORC Code). The JORC (Joint Ore Reserves Committee) Code also includes a principle of competency to ensure that the person providing the material information for public disclosure is suitably qualified and experienced.Since its inclusion into the ASX (Australian Securities Exchange) Listing rules in 1989, the JORC Code has continually improved and evolved in attempts to meet the market’s need for competent, transparent and informed disclosure. The quality and effectiveness of Public Reporting in accordance with the JORC Code is under constant challenge: some practitioners argue there is insufficient regulation, while others argue the need for greater self-regulation.This paper contributes to that discourse by exploring how well the Reporting expectations are met, and, whether Public Reporting in accordance with the JORC Code has a material impact on share-price movement.CITATION:Sterk, R and Coombes, J, 2017. Public reporting – new standards or no standards?, in Proceedings Tenth International Mining Geology Conference 2017, pp 423–432 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By V Rasouli, G Cavanough, A Mokaramian

The sampling time, the costs and its quality are the three factors that determine the best method of drilling in mineral exploration. The two principal methods of reverse circulation (RC) and diamond core drilling are often used in combination by mine operators. RC is used for drilling shallow holes and in-pit grade control, and core drilling for deeper holes to identify future resources. The RC method is faster and more flexible than coring and provides virtually uncontaminated cuttings (ranges from dust to 25 mm chips) to the surface cyclone suitable for geochemical anomalies. The diamond coring produces core samples to increase the level of geological knowledge and the 3D extension and distribution of the orebody. However, both of these methods are subjected to certain limitations and inefficiencies in reaching deeper depths and drilling complex hole geometries. Examples of such shortcomings include the inability to provide enough air pressure for RC drilling and high friction between drill pipe and the hole wall in diamond core drilling.Considering that delivering large volume of reliable samples from deep zones to the surface in shortest possible time is of paramount importance in mineral exploration, and assuming that obtaining core samples over whole overburden is not always essential, then drilling small size holes as fast as possible and delivering the small chip samples to the surface would be a good alternative with several advantages over conventional drilling methods for deep hard rocks mineral exploration. As a result, the use of coiled tube (CT) drilling technology has been proposed recently for such applications. CT is a continuous length of ductile steel or composite tube stored and transported on a large reel; and allows fast drilling by eliminating the connection time and providing continuous circulation during drilling. This enables quick access to the zone of interest to collect the cuttings or obtain core samples. CT is advantageous particularly in drilling directional boreholes and multi-laterals. In this paper, feasibility of using CT delivering reliable samples is discussed for deep mineral exploration. In addition, recent developments and practices are presented that make CT a reliable drilling technology to drill cheaper, faster and deeper and to deliver more continuous and reliable data and samples from deep formations.CITATION:Mokaramian, A, Rasouli, V and Cavanough, G, 2012. Quality sampling using coiled tubing drilling in deep mineral exploration, in Proceedings Sampling 2012 , pp 73-80 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By N Haque, S Northey

Water in mining, mineral processing and metal production on a life cycle basis has been at the top of agendas for various industries, government agencies, research organisations, academic institutions and communities. As a result, a number of water footprint assessment methodologies have been developed. However, their practical applications in mining and mineral processing industries with specific case studies are still rare.A key objective of the Minerals Down Under Flagship is to contribute to the long-term sustainability of the Australian mining and mineral industries. Researchers in the Mineral Futures theme have developed robust assessment methods to evaluate the impact of mining and minerals technology development on the environment. The future of mining and the mineral industry is strongly linked with its sustainability - better water management strategies will need to be implemented.Life cycle assessment (LCA) has been a recognised method for measuring the environmental impacts of products, processes and services. It provides a scientifically sound method of comparing products and processes using a common basis and identifies so called æhot spotsÆ and opportunities for reducing environmental impacts. The water footprint of mining, mineral processing and metal production using an LCA basis is still scarce in the literature. Research methodology is now being applied in detail for copper, gold and nickel. A primary focus has been the relationship between ore grade and water use for which mathematical models are being developed. These types of models provide inputs for LCA of mining and mineral processing plants and can identify water saving opportunities through scenarios and process route analysis.CITATION:Northey, S and Haque, N, 2013. Life cycle based water footprints of selected mineral and metal processing routes, in Proceedings Water in Mining 2013 , pp 35-50 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By Falbo A, Barbaro M, Esposito MA, Passariello B

Acidic reductive leaching is one of the best known and most widely employed chemical processes for beneficiating minerals of industrial interest. Conventional acidic leaching with sodium dithionite (Na2S2O4), employed to bleach industrial minerals used in the production of ceramics, glassware, paper etc, does not always allow products of high quality to be obtained. In the work reported here two reducing agents, ascorbic acid and oxalic acid, have been employed in a medium acidified by means of sulphuric acid. Continuous systematic tests have been performed on a kaolin sample containing 0.8 per cent Fe2O3, adopting various operating parameters such as, leaching time, temperature and reagent concentration. In each case the total quantity of bi- and trivalent iron dissolved was ascertained. Removal of 80 per cent and 100 per cent of iron with ascorbic and oxalic acid respectively was obtained, while less than one per cent of iron was dissolved in the presence of sulphuric acid only. Products having a very good degree of whiteness (92 - 94 per cent) were obtained, whereas with sodium dithionite the degree of whiteness was in the 85 to 88 per cent range. The best conditions identified were applied to a sample of quartz for the removal of ferric impurities.

Jan 1, 1993

By S Kost, R Nievergelt, F Cortes

In recent years, the use of steel fibre-reinforced concrete (SFRC) for segmental tunnel linings has become increasingly popular due to numerous advantages including durability, resistance to spalling, reduced cracking at corners and edges and significant cost-saving potential. One of the key parameters for measuring the performance of SFRC is the residual (post crack) flexural strength. A problem often faced in design and quality control of SFRC is the high variability of results obtained by standard beam test methods, with reported coefficients of variability (CoV) in the order of 25 per cent. The high test variability results in a relatively low permissible design strength relative to the average flexural strength of the material and commonly leads to non-conformances with respect to residual flexural strength during production testing.This paper presents the implementation of an alternative testing method using large round determinate panels (RDPs) for quality control testing of the SFRC used in the segmental lining of the City East Cable Tunnel (CECT) in Sydney. The alternative RDP test method was found to correlate well with standard beam tests and significantly reduce the variability of test results, minimising the risk of outlying residual flexural strength results, with zero non-compliant test results reported during the production period.This successful implementation of an alternative test for post-crack flexural strength with lower variability in results constitutes a relevant precedent to demonstrate the feasibility of this approach which contributes to the development of more cost-effective concrete mixes and minimises the risk for non-compliant results and the contractual disputes that commonly arise from these.CITATION:Cortes, F, Nievergelt, R and Kost, S, 2014. Development of a segmental lining specification for steel fibre reinforced concrete flexural strength testing using round panel tests, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 461–468 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By T A. J Hopper, S Mukkisa, M L. Johns, K T. O’Neill

Technological advances the sensor design and performance for logging while drilling (LWD) instrumentation offer considerable opportunities in iron ore exploration. Here we focus on the development of a nuclear magnetic resonance (NMR) LWD tool. NMR is an advanced geotechnical logging technology capable of providing in situ measurements of the porosity, pore size and permeability of the formation of interest. The ability to provide real-time characterisation of iron-ore systems is beneficial to both drilling operations as well as real-time formation evaluation. The development of an NMR LWD tool for mineral exploration drilling has previously not been achieved due to the significant technical and environmental challenges associated with the design and operation of such a tool. The tool outlined in this work is designed to work in reverse-circulation (RC) drilling systems. As such, the tool needs to be compatible with the RC drill-string, as well as being highly robust to survive the shocks and vibrations experienced during RC drilling operations. The magnetic physics of the probe must be capable of measuring at the appropriate depth into formation whilst being subject to the array of motions experienced during drilling operations. Furthermore, conducting accurate NMR measurements in an iron ore formation is challenging and the measurement methodology must be tailored to characterise the magnetic environment. The tool also requires high-powered electronics capable of operating the necessary pulse sequences for excitation and acquisition. The resultant tool design must therefore optimise the inherent trade-offs which exist between the physical components (ie mechanical structure, magnetic components and electronic hardware) in order to operate appropriately whilst not hindering RC drilling operations. Current experimental analysis of the prototype indicates that the current probe design exhibits the required measurement specifications and is nearing field testing. Future work will look towards commercialisation of the instrument.

Nov 8, 2021

By R Castedo, P Segarra, I del Castillo, L M. López, J A. Sanchidrián

This work investigates some suggested methods for blast vibration monitoring on a hard surface based on 53 tests on a vibration exciter. Errors in the measurement attributable to coupling have been described as function of frequency by the rock-to-mount (or coupling) transmissibility, ie ratio of the velocity of the vibration sensor mount to the velocity of the rock motion. Transmissibility has been measured from 2 to 200 Hz, at two vibration levels (5 and 20 mm/s), in four seismographs. Attachment methods with an anchor, thermal adhesive and gypsum plaster allow stiff rock-to-mount coupling. They ensure accurate measurements (errors below 0.3 dB) for frequencies commonly found in blasting (below 100 Hz) irrespective of the mount characteristics and the vibration level. Free laid mounts and sandbagged vibration sensors lead generally to a poor, weak coupling. Errors are non-linear errors with the input velocity, ie the operating frequency window narrows as the velocity of the ground increases. Free mounts follow ground motion acceptably well (error up to 0.4 dB) at both vibration levels and frequencies below 15 Hz. At higher frequencies, free mounts lead to the largest distortions with expected errors ranging from 0.8 to 6.6 dB. Sandbagging limits the expected errors below 1.3 dB, but it does not prevent large errors that can be up to 4.5 dB. Both frequency and velocity should be considered together to assess the measurement errors instead of the expected accelerations, as it is currently made.CITATION:Segarra, P, Sanchidrián, J A, Castedo, R, López, L M and del Castillo, I, 2015. Effect of vibration sensor mounting method on the quality of vibration measurements, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 545–552 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015