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By B Mohanty, M P. Roy, P K. Singh

"The measured response of residential structures is a critical indicator of troublesomeor potentially damaging ground vibrations. A study was conducted to evaluate theresponse of structures situated in the periphery of four open-pit coal mines in India. Although, most of the structures were at far-off distances from the present blasting sites, an attempt was made to document the response of structures to blast vibration for future applications to optimize the blast designs for the safety of the structures. The study involved a total 215 blasts, employing one-, two- and three-hole calibration study, and production blasts. The bench height varied from 7.5 m to 42 m, and boreholes loaded with emulsion and slurry explosives were 250, 260, 270 and 310 mm in diameter. The explosive detonated in a blast were between 300-198400 kg whereas in a delay it was 33-24800 kg. Up to 12 tri-axial vibration sensors were located in overburden along a linear array from 25 m to 6.5 km distance from the blasts. Altogether, 1512 blast vibration signatures were recorded. Production and specially fi red single-charge blasts allowed the determination of natural ground frequency. The fundamental frequency of the structures ranged between 3.13 to 10.6 Hz, the same as those of the ground vibrations. The amplifi cation of vibration in the structures was in the range of 1.6 to 5.6. The study details the interaction between ground vibrations and selected structures, and the means to reduce amplifi cation of vibrations in the structures and persistence of vibrations through improved blast design."

Jan 1, 2008

Developments in the technology of explosive production and deliveryallow a greater amount of flexibility in rock fragmentation by blasting. The rock fragmentation efficiency of an explosive is currently given by a rating which is determined by the explosive manufacturers using proprietary formulae and methodology. Hence, comparison of explosives from different manufacturers may be misleading. Modeling of explosive energy, using a thermochemical code such as CHEETAH provides an objective standard by which the likely performance of different explosive formulations can be determined. Such modeling can be used for optimisation of explosive composition to match specific rockfragmentation objectives.

Jan 1, 2001

By D. M. Muir

The mineralogy of residues formed during the pressure acid leaching of arid region nickel laterite ore varies according to the salinity of the process water, alkali cation additives and the overall acid loading. In fresh water, hematite is the main iron-bearing leach residue component, together with amorphous silica and hydronium or sodium alunite/jarosite [(H3O,Na)(Fe,Al)3(SO4)2(OH)6]. As the process water salinity increases, or as NH4+ or K salts are added, alunite/jarosite is the kinetically favoured iron-bearing phase accompanied by an increase in acid consumption. The alunite/jarosite appears as two XRD distinct phases with different Fe:Al molar ratios. In weakly saline water, iron-rich alunite/jarosite slowly transforms to hematite and an aluminium-rich alunite/jarosite together with the release of acid. The addition of potassium salts forms a more stable alunite/jarosite whilst the addition of ammonium salts leads to greater transformation of alunite/jarosite at 250°C. Weakly saline process water gives enhanced nickel recoveries, whilst strongly saline process water gives lower nickel recoveries but higher soluble iron because of chloro-complexation. SEM and microprobe analysis shows very little nickel is associated with the alunite/jarosite and hematite phases. Nickel losses to the residues are attributed to adsorption on amorphous silica and to a lesser extent on alunite/jarosite.

Jan 1, 2006

By A S. Derrington

There are several long-standing rules of thumb that are often quoted in mine ventilation studies. They include airway ‘carrying velocities’ and the critical upcast air velocity range that must be avoided to prevent a water blanket forming. Quoting these rules of thumb may lend an air of legitimacy to a ventilation design, and allow the design engineer to avoid having to study a problem from first principles. But how valid are these shortcuts in today’s rapidly changing world? This paper summarises research into the genesis of several commonly quoted rules of thumb. It finds that they were very specific to the local conditions, practices and economics at the time they were developed. It also presents examples where applying these rules of thumb outside of their original context can lead to unexpected and erroneous results.CITATION:Derrington, A S, 2017. Ventilation rules of thumb – friend or foe? Focusing on design upcast air velocities for shafts and raise bores, in Proceedings Australian Mine Vent Conference 2017, pp 253–260 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By E. Fried

Cemented paste backfill (CPB) is an innovative tailings management method that consists in returning considerable amounts of mine tailings into the underground mine openings. The filled stopes thus participate to the ground support that allows maximizing orebody extraction and a safer environment for the mine workers. There are also significant environmental advantages of using CPB. Indeed, up to 50% of the concentrator tailings can be backfilled, leading to a smaller volume of problematic waste materials to be managed at the surface. Once the CPB is placed, or when the mine is flooded at its end-life, the backfill is subjected to underground water flows that may leach and spread the pollutants (mainly metals, sulphates, and acidity) which can contaminate the underground waters. The aim of this study is to characterize the leaching properties of CPB material and to identify the cement phases that ensure the metal fixation. A laboratory procedure was implemented consisting in the preparation of various paste backfill mixtures using sulphide-rich and sulphide-free materials, different types of binder, and mixing waters having various sulphates, copper and zinc concentrations. After 90-days curing time, the samples were submitted to column leaching tests. The CPB materials were flushed each day with 100 ml of deionised water during 100 days. The collected leachates were then analyzed for pH, Eh, electric conductivity and chemical composition. For some samples, a differential acid neutralisation test was carried out. The objective of this experiment is to dissolve selectively the hydrated phases by adding incremental acid concentrations. By analyzing punctually the equilibrated solutions, the composition of the dissolved phases and their metal content can be estimated. The leaching test results showed that the pH of the leachates remains alkaline during the test period. When the pH decreases under 10 (after 30 days), different behaviours in terms of chemical element release (especially for zinc) were observed. During the test, the oxidation of pyrite seems to slow down, probably due to passivating phenomena. Moreover, the differential acid neutralisation test results allowed a better understanding of the CPB mineralogy and the Zn-bearing cement phases. Zinc and the other metals seem to be fixed within a calcium-magnesium silicate.

May 1, 2007

By Mark R. Svinkin

Regulations are needed to keep construction vibrations in tolerable limits. The existing regulations were developed for low-rise residential structures, but they are incorrectly used for different super and underground structures. The existing regulations cannot prevent most of harmful vibration effects on sensitive devices, people and structures from construction and industrial vibration sources. It is important to determine the areas of application of the existing regulations and bring attention to the necessity of measurement of the structural responses for assessment of vibration effects on structures. For multi-story residential, commercial and industrial buildings, the frequency-independent safe limit of 51 mm/s (2 in./s) can be chosen for the peak particle velocity of structural, not ground, vibrations. Specifications for construction operations with dynamic sources have to consider specifics of each construction site. Preventive measures can be used to mitigate harmful vibration effects on various structures and settlements in sand and clay soils.

Jan 1, 2006

The need for the hydraulic transportation of coal in the New South Wales coal industry, both from the coal face to the surface and from the coal mine to the consumer or the port for export, is explained. Details of research projects currently in progress and involving the hydraulic transportation of New South Wales coals are given together with information on the hydraulic transportation of coal in the United States of America. The potential of hydraulic transportation as a viable alternative to the proposed expansion and upgrading of the New South Wales railway system to meet the projected New South Wales coal production to the year 2000 is described.

Jan 1, 1980

By Fabiano Mendes

Processos industriais de carbonização são tecnologias maduras e operam há mais de 7 décadas. Contudo, o sistema integrado de produção de ferro primário e aços a base de biomassa como fonte de energia e termorredutor, mesmo sendo a alternativa ambiental de menor impacto existente, chega a seus limites tecnológicos, ambiental e econômico, ameaçando a sua sustentabilidade. O grupo Vallourec buscou o processo Lambiotte como base tecnológica para desenvolver seu ambicioso projeto de carbonização contínua, em substituição ao processo artesanal de fornos retangulares de batelada, utilizados atualmente. O esforço experimental de mais de meia década, com a adaptação e profunda reengenharia do processo Lambiotte, que é o que melhor representa esta classe de reatores, para que ele atendesse as condições brasileiras e o uso das espécies de madeira da família dos Eucaliptos culminou no desenvolvimento do processo de carbonização continua Carboval, que demonstrou sua plena capacidade, para atender aspectos econômicos, sustentáveis e de qualidade siderúrgica do carvão vegetal produzido.

Aug 17, 2017

By J Merrells

Fluor, together with our clients, has yielded significant reductions in the total cost of mining projects by employing a systematic and methodical process of cost reduction. This paper outlines this structured approach to reducing the total cost of projects through the gathering of information, the evaluation of the zero base design, and the development of the execution strategy for the project in the study phase.Over the recent iron ore boom the cost of growth projects escalated rapidly due to a variety of factors including the engineering cost of re-designing facilities, construction in remote areas and an increase in the ‘perceived’ capital requirements for maintainable and operable facilities.Fluor has made strategic steps towards safely reducing the capital intensity of projects, by working with clients to develop zero base designs which utilise the minimum technical requirements in order to meet the function of the plant and then add cost for safety, maintenance and operability only where clearly justified.This paper has set forth a structured three phased approach to focus the team on reducing capital cost while maintaining a low increase in engineering effort.The initial ‘gather’ phase focuses the team on acquiring information and identifying decisions that will need to be made so that the team can prioritise and focus the attention on areas that will provide the greatest benefit. Within this phase the identification of zero base design requirements, review of lessons learnt and analysis of capital cost levers, allows the team to identify the key decisions on the project that will affect the capital cost.In the subsequent ‘evaluation’ phase the team established the zero base design, using the hierarchy of cost reduction as a guide to focusing the team’s attention on high yielding cost saving opportunities.In the final phase the team develops the execution strategy which will yield the least cost using strategies and tools such as modularisation, standardisation, replication, strategic sourcing and 3D design.CITATION:Merrells, J, 2017. Reducing total project cost in the study phase using zero base design, in Proceedings Iron Ore 2017, pp 621–626 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By F. Dai

Granitic rocks usually exhibit strongly anisotropy due to pre-existing microcracks induced by geologic loadings. The understanding of the rock anisotropy in mechanical properties such as tensile strength is critical to quarrying and stabilization of underground structures. In this paper, Brazilian tests are conducted in combination with MTS material testing machine and split Hopkinson pressure bar (SHPB) system to measure both static and dynamic tensile strength of anisotropic Barre granite. Samples are cored and labeled using the three principle anisotropic directions of Barre granite (BG). These directions are also chosen as the loading directions for the Brazilian discs. For dynamic tests, pulse shaping technique is used to achieve dynamic equilibrium in the samples during the test. Finite Element Method is implemented to formulate equations that relate the failure load to the material tensile strength employing a orthotropic model for Barre granite. For samples in the same orientation group, the tensile strength shows clear loading rate sensitivity. The tensile strengths exhibit clear anisotropy under static loading; while less anisotropy under dynamic loading. The tensile strength anisotropy of Barre granite is interpreted as interactions of the pre-existing microcracks.

May 1, 2009

By B K. Hebblewhite, F T. Suorineni, J D. Tibbett

Block caving is an underground mining method that can provide high production capacities at low operating costs. This enables the profitable extraction of massive, low-grade orebodies and attracts industry towards the method. Block caving operations require significant initial capital investment and predictable cave propagation is crucial to safety and economic success. Lack of access to observe the caving process hinders our ability to learn how the rock mass and geological structures are reacting to mining. Virtual reality scientific visualisation (VRSV) enables the integration and investigation of multiple, large caving data sets and provides a viable alternative to visualise rock mass response without physical access to the cave. Point instrumentation is incapable of providing an overview of cave performance and seismic monitoring, while providing an overview of the rock mass and the response of structures to caving, is only useful when linked to the caving activities. The integration of point instrumentation data with seismic monitoring information, coupled with scientific visualisation of the mining system in a virtual reality environment, provides a powerful means for understanding caving performance.This paper describes the use of a VRSV module at UNSW Australia, designed for investigating the block cave mining system from a case study operation. This module has been used to investigate the location and chronological evolution of seismicity to understand sources of damage resulting in seismic space-time sequences (SSTS) in the caving system. The events within an SSTS represent damage that is spatially and temporally related. An SSTS group represents a collection of microseismic events from a reasonably competent region of the rock mass that has experienced a stress change significant enough to cause sequential damage. SSTS group locations have been seen to be the path of subsequent cave propagation. Thus, SSTS analysis enables insight to further our understanding of rock mass damage in caving geomechanics through analysis of historic data. Such insight has operational potential to learn from recent rock mass activity for optimising the management of undercut advance, draw front advance and cave draw patterns.CITATION:Tibbett, J D, Suorineni, F T and Hebblewhite, B K, 2016. Understanding damage source mechanisms in a caving system using virtual reality scientific visualisation, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 439–452 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Roberto J. Guardia, Ted Lewtas, Peter Rasmussen, Klaus Winkler

As part of the Lake Fort Smith Water Supply Dam Enlargement project, located in northwest Arkansas, microtunneling methods were used to install two side-by-side,1.53m (60-in) inside-diameter steel pipes between the intake structure shaft and the lake. The 46.6 m- (153 ft-) and 41.7 m- (137 ft-) long tunnels were excavated in Pennsylvanian sedimentary bedrock ranging from coarse sandstone to siltstone and shale-like claystone. The intake tunnels were constructed 18.3 m (60 ft) below lake level from the dry shaft. Special installation methods and procedures described herein were used to complete the lake taps. Installation difficulties that caused minor delays are also reviewed. After the excavation of the Intake shaft was completed, the two lake taps were installed in approximately ten weeks with the same microtunneling machine.

Jan 1, 2005

By G. Balletto, C. Furcas

"The mineral raw materials industry is a key-component of the Gross Domestic Product of industrialised economies, closely related to both the building and the industrial sectors. Despite this, at local level mining and quarrying are associated with both irreversible environmental damage and several visual alterations affecting the natural landscape. In this sense, SIA (Social Impact Assessment) has become a strategic tool that can not only improve the prediction but also the assessment of the social impact by involving the local communities in a participatory process. Taking into account the SIA experience, together with the examination of some relevant international case studies, it is possible to draw up a list of good practices for mining project management, from exploration through to closure and beyond, with quarry restoration. Such good practices will complement the existing studies, focusing on environmental issues, with the social issues arisen considered in SIA application."

Jan 1, 2011

By Nick Rose, Robert Sharon, Mark Rantapaa

Development of the Northeast Layback of Barrick’s Betze-Post open pit commenced in June 2000 and was successfully completed to a height of 400m (1,300 ft) in January 2003. Following a brief exploration drilling campaign at the toe of the final slope, in-pit waste rock backfilling commenced, which will ultimately buttress the final wall. Instability initially occurred in late 2000, above the 5040 Level, as the slope height approached 120m (400 ft). As mining reached the 4680 Level, significant deformation was experienced over a slope height of 230m (760 ft). Slope stability was managed and targeted reserve recovery was achieved by executing complicated modifications of the mine plan, including splitting layback development, well placed offloading cuts, step-outs and mid-slope waste rock buttresses. Decision on timing of these modifying events was often dictated by review of deformation magnitudes and rates determined from continuous slope monitoring records. Design modifications were developed through continuing interpretive refinement of structural geology controls and groundwater distribution, and through stability re-assessments. This document presents an overview of the geological setting and material and strength conditions of the northeast sector of the Betze-Post open pit, followed by development experience leading to design and development of the Northeast Layback. Rock mechanics modeling, design details and geotechnical performance monitoring are then presented. Development experience, stabilizing adjustments to the original design and safety procedures for development and exploration activities are described. The document is finalized with conclusions and acknowledgements.

Jan 1, 2005

By D Craw

At Reefton, mesothermal gold deposits occur in the Ordovician Greenland Group basement and bituminous coal deposits occur in overlying Eocene Brunner Coal Measures. These different resource types occur in close proximity to one another in the same topography, vegetation and climate. Both types of resources have been mined for many years and as a result historic mining areas discharge water with chemistry reflecting the mineralogy of the deposits. Coal measures release natural acid rock drainage throughout the region due to oxidation of pyrite in coal and associated sediments. Levels of acidity are increased in mining areas, and pH near three is common. Gold mines contain pyrite, arsenopyrite and stibnite. Discharge waters from these sites have pH near seven because of the high acid neutralising capacity of the basement rocks. Both coal and gold mining sites have iron oxyhydroxide precipitates in drainage waters. These precipitates are more abundant at gold mining sites, and one deposit is up to 5 m thick. Iron oxyhydroxide at coal mine sites contain Zn (up to 89 ppm), Ni (up to 10 ppm), As (up to 163 ppm), Cr (up to 23 ppm), Pb (up to 16), and Cu (up to 11 ppm). Jarosite group minerals have been identified in the coalmine iron oxyhydroxide, although most of the material is amorphous. Gold mine iron oxyhydroxide contains Zn (up to 353 ppm), Ni (up to 592 ppm), Cr (up to 17 ppm), Cu (up to 72 ppm), Pb (up to 29 ppm), Sb (up to 230 ppm), and this material is particularly high in As (up to 20 wt per cent). Most of the material is amorphous but distinctive zones (mm scale) are As rich (up to 30 wt per cent As oxide). Pharmacosiderite, K2Fe4(As04)3 (OH)5.6.3H20, is a secondary mineral in one deposit. These iron oxyhydroxide deposits are useful indicators for the metals mobilised into the environment by oxidation in the historic workings.

Jan 1, 2003

By H. A. Davies

DURING a current program of research on the structure and properties of liquid sodium alloys, the need arose for information on the solubilities as a function of temperature of several B subgroup metals in liquid sodium. In the absence of reliable information in the literature for several of these systems, par- ticularly at temperatures in the range 100° to 300°C, an apparatus was constructed to determine solubilities by a direct melt-sampling technique, followed by wet-chemical analysis for both sodium and the solute metal. The details of the technique have been described previously.' The solubility of indium in liquid sodium was determined at eight temperatures in the range 100° to 270°C. The solubility as a function of temperature is shown on Fig. 1; this represents the liquidus line over this composition range. A cooling curve was plotted after the completion of the sampling and an arrest was observed at 94.9°C which must be interpreted as being the result of a eutectic reaction. By extrapolation of the liquidus to this temperature, the eutectic composition was estimated to be about 0.25 at. pct In. The present estimate of the eutectic temperature and composition are in good agreement with the values of 96.0° to 96.2°C and between 0.28 and 0.45 at. pct In, respectively, which were reported by Heycock and Neville.2 However, no further information on the liquidus of this system at the sodium-rich end could be found in the literature for comparison. One compound: NaIn, has been reported in this sys-

Jan 1, 1968

By Johnny Lyons-Baral, John Kemeny, Don Kraemer

Ground vibrations from blasting can result in the degradation and failure of rock and soil exposures, as well as damaging neighboring houses and buildings. At the same time, vibration provides an opportunity to regularly monitor the rock and soil exposures. If a geophone or accelerometer is attached to a rock block or wedge on a mine slope, for example, then blast vibrations will regularly “sound” the rock block and the resulting vibrations can be used to assess the stability of the rock mass in the neighborhood of the accelerometer, as well as monitoring the properties of the blast. This paper describes the development of a wireless sensor network based on inexpensive MEMS accelerometers for blast monitoring and rock and soil structural health monitoring. The wireless sensors are placed at various locations in and around an open pit mine or quarry, and transmit data to a central source after ground vibration events occur. As described in the paper, a variety of wireless and non-wireless accelerometers were tested in actual field conditions. This includes the monitoring of over 30 blasts at an open pit mine in Arizona with as many as nine simultaneous accelerometers. Matlab was used to process all the data and develop innovative methods to view and interpret the data. This includes the use of the wavelet transform to determine resonance frequencies, and the use of both ground resonance frequencies and scaled-distance peak particle velocity (ppv) relationships to assess slope stability. As part of this research, a three-dimensional point cloud environment for viewing and analyzing the vibration data from the sensors has also been developed.

Jan 1, 2014

By Adriana Amaro Diacenco

Neste trabalho, os procedimentos para modelagem de estruturas de compósitos do tipo sanduíche que incorporam materiais viscoelásticos são apresentados. A análise numérica foi desenvolvida utilizando a Teoria de Deformação Cisalhante de Primeira Ordem (FSDT), que é implementada em um elemento Serendipity retangular contendo oito nós e cinco graus de liberdade. A incorporação do amortecimento para os modelos de elementos finitos em compósitos de placas laminadas é feita usando a abordagem de módulo complexo e a resolução numérica das equações resultantes do movimento são aspectos particularmente relevantes dos procedimentos de modelagem. Após as discussões de vários aspectos teóricos, as funções de resposta em frequências (FRF's) são calculadas para placas laminadas de compósitos com camada viscoelástica.

Aug 17, 2017

Gold mineralisation at the Macraes Gold Project is hosted in the Hyde-Macraes shear zone and can be traced for ~30 km along strike, although economic resources are confined to a seven kilometre section in the vicinity of the Macraes  township. The shear zone, which typically dips at a low angle (~20¦) to the NE, is bounded by an upper hanging wall shear and a lower footwall fault. Mineralisation occurs along the hangingwall of the shear zone as well as in low angle concordant shears and stockworks. Ore types include graphitic cataclasites with variable amounts of quartz veining, 'lode schists' and quartz-vein stockworks. Mine geology and grade control activities are designed to ensure accurate definition of ore and waste as well as the accurate prediction of ore grade. Grade control involves an integrated process of blast hole sampling, geological mapping and geostatistical modelling. Geological mapping is carried out post blasting by means of excavating trenches across are zones defined by assay data. Conditional Simulation is used to model raw assay data to define ore-waste contacts and estimate ore block grade, although, geologically defined contacts have precedence. Low angle ore zones impart a wedge shaped geometry to many ore blocks. These ore blocks are bounded by contacts that can be selectively mined to, thereby reducing misallocation of ore and minimising grade dilution.

Jan 1, 2001

By Takashi Sasaoka

Chain Conveyor Cutter (CCC) is a chainsaw-type machine and originally developed for the construction of underground walls and/or ground improvements. CCC was developed from the accumulated technology of coal mining, combining the cutting technology of a shearer and the fuctions of chain conveyor. The CCC can cut harder soils and soft rocks, and vertically mixes the cut soils/rocks with cementing material selected through the discharging port installed at the bottom of the machine. In Indonesia, highwall mining trials have already been conducted in several coal mines. However, full-scale and regular operations have not been done yet due to the ground and machine control issues from their geological conditions. In order to overcome these problems, the application of CCC to highwall mining systems was proposed, and its applicability and technical issues to be solved were investigated in this research. This paper discribes the characteristics of CCC system and discusses the application of CCC to highwall mining systems.

Jan 1, 2012