Search Documents

The commonly used Stopes-Heerlen coal petrographic classification and nomenclature has over the years been subject to variable interpretations. This paper discusses the problem with specific reference to the inertinite maceral group. The effect of various interpretations of the Stopes-Heerlen system on maceral analysis is discussed and illustrated by means of comparative analyses conducted by a number of laboratories in Australia.An attempt is made to define the reflectance thresholds used by the authors to subdivide the inertinite group; the genetic and technological significance of these thresholds are compared.The difficulties of distinguishing structured and nonstructured macerals of the inertinite group are discussed in terms of possible improvements to the present StopesHeerlen system by extending the classification to include transitional maceral types.

Jan 1, 1970

By R Pozo, F Reyes

Codelco Chile is currently developing the El Teniente û New Mine Level Project (NMLP) in order to increase ore production by seeking to mine the ore deposit located under the current operational orebody. Reserves of 2000 million tonnes (Mt) have been quantified, which will be extracted as from the year 2017 by using the panel caving and progressive sinking method. Codelco and SKM Minmetal (SKM) jointly developed the project prefeasibility stage (PFS), closing these studies in March 2008. The first part of the project approach is to replace mine production currently feeding the Colon concentrator facilities with 137 000 tonnes per day (t/d), focusing attention on a production increase from the year 2026 up to 180 000 t/d. Project efforts have also been centred on maximising the contribution of new technologies for both construction and operational phases of the New Mine Level, together with selecting the best mine infrastructure to keep El Teniente operations going on for the next 50 years. Implicit in this is the inherent improvement of a variety of current Mina El Teniente process and management practices. The plan is to reduce actual mine operational risks and take advantage of new opportunities afforded by the project, which is in effect a greenfield project with respect to the implementation of fundamental changes in the labour and business environment. In addition, issues related to human resources, maintenance and management, materials handling, establishing centralised operations and accesses, automation and remote operations control and power efficiency could also be addressed. The project, beyond the New Mine Level exploitation, considers the mineÆs future potential, with a second deeper exploration in prospect named Deep Level. Finally, the project identifies features that would add value to the mine operations, in an initiative named æSpace for Future TechnologiesÆ. This will allow the eventual implementation of new electrical equipment and the application of mechanised technologies and other process improvements for the mine development.

Jan 1, 2008

Xstrata CopperÆs Mount Isa Copper Operations is located in mineral rich north-west Queensland and is one of the largest sources of copper in the world. This world-class underground operation is planned to produce over 6.6 million tonnes of copper ore in 2007 from the X41 and Enterprise Mines. With an underground mining history of over 50 years and underground reserves of over 83 million tonnes at 2.6 per cent copper, mine planning for the future becomes an exciting challenge for the technical team due to the older nature of certain areas. The 1100 Orebody of the X41 mine was one of the first places that copper mining occurred, with its discovery in 1953 - 1954 and mining commencing in the 1960s. Sublevel open stoping mining methods have been employed since that time as the means of extraction, using a primary-secondary sequence to maximise stope turnaround time. Large Transverse Pillars within the 1100 orebody were not mined out in order to provide access for ventilation, power, orepasses and other services. The Panel Pillar, 4180XC and 4010XC pillars are three such Transverse Pillars in the 1100 orebody that will be mined as a final retreat. This paper discusses the technical challenges and issues associated with the extraction of Q390 stope, one of the stopes located in the Panel Pillar, and the design solutions to overcome these issues. Managing the exposure of backfilled stopes of variable fill strength, ensuring the stability of the crown, stope walls and drawpoints, managing vertical openings, re-establishing service networks, and stope filling are the critical issues given consideration for the final design of Q390 stope and other such stopes within a Transverse Pillar. Communication and coordination between the different departments in the mine are essential for the necessary work to be completed in a timely manner to bring pillar stopes into production.

Jan 1, 2007

As the title indicates the central themes discussed in this contribution are sustainable development, information systems, and extractive industry. More specifically, the objective is to present a prototype for the systematic generation of extractive industry (henceforth: EI) û specific sustainability information. The paper begins with the authorÆs viewpoints on the core notions of sustainability, and development, as well as their relationship to information. These set the stage for the introduction of the information system (IS), as well as the follow-up sustainability information system (SIS) extractive industry sustainability information system (EISIS) concepts and related discussions. The paper continues with a second part, in which, efforts to research and develop an EISIS prototype are described. First, the team is presented. Second, the systemÆs aim and target groups are briefly discussed. After, an articulated overarching EISIS conceptual model emphasising capital accumulation, and service flow concepts û is presented. This is followed by a detailed description of the assembled prototype with a focus on data and information generation. The formulation of data generation, storage and transmission processes, as well as its use in sustainability interpretation rules and their embedment in the conceptual model is made with respect to monetised stock and flow parameters, measured in the appropriate dimensions. In the third part, the author presents and discusses the results of a first round of prototype experimental development in three major EI firms. First, the system observation, and data analysis protocols are described. Second, a review of protocol implementation, and respective results, is made. Finally, the overall performance of the proposed prototype, and development process issues are discussed, before suggesting areas for improvement and future research. The paper ends with a conclusion in which the author provides a retrospective balance of the æknowledge creation projectÆ, as well as a prospective outlook for research in this field; before acknowledgements are made and references provided.

Jan 1, 2009

By N Taylor, P Hewitt

The Northern Beaches Storage Project (NBSP) is part of Sydney Water’s SewerFix™ Program to improve the wastewater system and protect public health and the environment. It was built by the SewerFix Wet Weather Alliance (the Alliance), a partnership between Sydney Water, RPS, MWH, Parsons Brinckerhoff and United Group Infrastructure.The project temporarily stores excess wastewater diverted from the Narrabeen Submain during wet weather. The project considered a below-ground storage facility, which involved constructing a deep tunnel from Brookvale to Fairlight, connecting into the Northside Storage Tunnel and a storage tank, which was subsequently adopted and constructed.The storage tank scheme included a pumping station and inlet and outlet pipes installed by microtunnelling. The storage tank site is in the Brookvale industrial area situated in an area of deep marine sediments overlying Hawkesbury Sandstone at about 30?m below ground. Microtunnelling for the inlet pipe was conducted from a 12?m deep jacking shaft. The jacking shaft and 14?m deep pumping station excavations were carried out from within secant pile earth retaining structures adjacent to existing buildings.Construction activities had the potential to cause settlement of the adjacent buildings. During excavation and microtunnelling the water ingress, adjacent groundwater level and settlement of the adjacent buildings were monitored. The monitoring data was assessed against an action plan, which modified construction activities as required to minimise the risk of damage to buildings from settlements caused by lowering of the groundwater table outside the excavations. The secant pile construction, excavation, microtunnelling and pumping station construction proceeded without incident or damage to adjacent buildings.This paper highlights that tunnel/underground options should be considered during options development, describes the original storage tunnel scheme and presents details of the successful microtunnelling and deep shaft construction adopted on the NBSP.CITATION:Taylor, N and Hewitt, P, 2014. Tunnelling on Northern Beaches Storage Project, Sydney, to improve water quality, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 451–458 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By M Gill, A Mathias

The mining industry has always been cost-focussed but in recent times mining companies have moved towards obtaining a competitive advantage through the implementation and sustainability of best practice in the areas of improved safety, operating costs, quality and productivity. This is the concept of Value In Use û that mining companies see value generated all the way to the bottom line through improved change, and those changes become an established mine practice. Many mining companies do not have the resources or the knowledge to sustainably achieve such an outcome. This has led to companies looking to their suppliers to deliver measured value to their business through partnership arrangements. Suppliers have been able to leverage their knowledge of products, product applications and services to offer alternative supply agreements that bring greater returns to their businesses while improving supplier/client relationships. Orica has developed such a partnership with Coal & Allied in the form of a Continuous Improvement Program. Coal & Allied is based in the Hunter Valley region of NSW and is the largest coal producer in that region. Both parties are contractually bound to jointly deliver Value In Use projects to Coal & AlliedÆs Hunter Valley Operations and Bengalla mine sites. It is the request of the Orica and Coal & Allied Steering Committees that this paper does not include the details of actual projects or the costs or key performance indicators associated with the program. This is to maintain the competitive advantage to both Orica and Coal & Allied through the implementation of such a program. It is in the writersÆ opinion that this paper does not lose any significance through this restriction as the most important component of the Continuous Improvement Program is not the projects themselves but the methodology behind them. With this in mind the paper will discuss the development of Value In Use offerings, the key aspects of the Coal & Allied and Orica joint program, what is a Value In Use project, how to measure its value, finally why and even more importantly what makes this program is a success.

Jan 1, 2004

A study was conducted to evaluate the effectiveness of the three types of sample grinders routinely used in the mining industry for the sample preparation of gold ores with particular emphasis placed on testing their capacity to produce a representative assay sample of coarse gold ores. The grinders used in this study are the Labtechnics LM5, the Mixermill 4010 ringmill and the Keegor vertical spindle pulveriser, commonly called a Keegormill. The study was based on the preparation of samples from two sources of known coarse gold ore, the Union Reefs Gold Mine and the Brocks Creek Gold Mine in the Pine Creek region of the Northern Territory of Australia, and a fine gold ore which was from the Macraes Gold Mine in New Zealand. The Union Reefs Mine contains visible coarse gold with 30 per cent to 40 per cent of the gold in the plus 75 μm fraction of milled ore. Discreet particles up to 5 mm have been recorded, Hellsten (1994). Union Reefs Gold Mine recovers 40 per cent of its bullion production through a gravity circuit, Riches (1997). Brocks Creek ore contains visible coarse gold with gravity bullion production fluctuating between 50 per cent and 65 per cent, depending on the mill feed. Average gravity bullion production from the Brocks Creek Mine is 55 per cent, Wilke (1997). The average gold grain size of Macraes Mine ore is 20 μm with 40 per cent of the gold in sub 10 μm particles. No gravity bullion is produced from the Macraes Mine, O'Keefe (1997). The testwork demonstrated conclusively that it is possible to prepare a representative sample for assay, of a coarse gold ore, when a Keegormill is used to pulverise the sample to a nominal 100 μm particle size (90 per cent passing a 100 μm screen by wet sieving). Both the Mixermill and the Labtechnics LM5 failed to prepare a representative sample, even when ground to a nominal 75 μm particle size.

Jan 1, 1998

By C A. Cooper, G A. Suter

The sizing of a starter dam for a Tailings Storage Facility (TSF) involves balancing many competing demands. It should cost as little as possible, be high enough to store tailings until the first raise can be constructed, it must be able to contain water safely, and it must be designed in such a way that the long-term integrity of the higher raises are not compromised, among other things. In addition to these demands there is the complication of the behaviour of the process plant, and the tailings during commissioning. Variations in slurry density, excess water in the TSF, initial settled density of the tailings, reliability issues, and beach slopes above and below water can all impact the way the tailings beaches are developed and ultimately impact the ability of the starter dyke to contain the required volume of tailings and water.The conventional approach to the design of a TSF starter dyke is to begin looking at the elevation required for a set of deterministic design parameters, find ways to reduce the size or volume of it as much as possible to reduce cost, and then possibly look at the sensitivity of some of the input parameters. This paper discusses a stochastic modelling approach for starter dykes that allows a wide range of design inputs to be simulated quickly, with an envelope of possible results produced. The sensitivity to different parameters can also be examined to understand which design inputs have the biggest impact on the required dyke sizing. By integrating the 3D TSF modelling tool Muk3D with GoldSim, it will be demonstrated how a wide range of scenarios can be evaluated and how that information can be used to make better decisions about the selection of design options.CITATION:Cooper, C A and Suter, G A, 2018. Starter dyke optimisation with Muk3D and GoldSim, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 466–475 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By J A. Sanchidrián

The general ranges of validity of some distribution functions are assessed from their behaviour with 119 sets of fragmentation data from bench blasting obtained by sieving. The emphasis is on determining the lower size/passing limit that the size-scaled Rosin-Rammler, Grady and Swebrec functions, and their bi-component versions, can represent with reasonable precision. By fitting these functions to the data using different weights, the accuracy of the fit varies in the different size/passing zones, so that an overall knowledge of the capacity of the function is obtained across the whole size range, from the coarse zone to the fines. Reasonable ranges of use of bimodal Rosin-Rammler and extended Swebrec (all of them five-parameter, bi-component distributions) are, in terms of percentage passing p, 99 > p > 2 per cent (up to 100 per cent for the extended Swebrec), or 90 > p > 0.5 per cent, in which the expected error of the calculated size is below 15 per cent in the extremes of the range, and less than five per cent in most of the central range; maximum errors (ie errors that will only rarely be exceeded) are typically less than 50 per cent in the central range, and up to about 100 per cent in the extremes. Ranges of use for the Swebrec and the size-scaled Rosin-Rammler (three-parameter distributions), with only slightly larger errors than the bi-components, are 100 > p > 5 per cent or 80 > p > 2 per cent. The classical two-parameter Rosin-Rammler can be used in the range 95 > p > 20 per cent or 90 > p > 10 per cent, with expected and maximum errors less than about 15 per cent and 100 per cent respectively.CITATION:Sanchidrián, J A, 2015. Ranges of validity of some distribution functions for blast-fragmented rock, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 741–748 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By F

Ore reserve estimation has been described as the most individualistic, the most prickly and even the most controversial of all the technical aspects of the mining profession. This symposium is a great opportunity to look at the present state of the art and full marks must go to the Sydney Branch for organi- sing it at this time. The first essential of good ore esti- mation is probably an awareness of the uncertainties involved, and the possible impli- cations of these uncertainties.

Jan 1, 1979

By Mackenzie W. R, Harding C. G

The Islamic Republic of Mauritania is a large country of over 1 000 000 square kilometres situated on the Atlantic coast of north-west Africa. It is bounded to the north by Western Sahara and Algeria, to the east by Mali, and to the south by Mali and Senegal. With the exception of a narrow strip in the south along the Senegal River valley, the country lies entirely within the Sahara. The north of the country is largely devoid of vegetation, and it is estimated that 90 per cent of the population of 2.1 million people live in the southern quarter of the country. From about the turn of the century, Mauritania was ruled by the French from Dakar in Senegal and, until 1960 when it obtained independence from the French, Mauritania did not have a capital. Today, the capital is Nouakchott, home to an estimated 600 000 Moors of mixed Arab, Berber and African descent. After independence in 1960, disputes over Spanish Sahara to the north led to a military coup in 1978 and it was not until 1991 that a democratic constitution was adopted. The new constitution declares Mauritania to be an `Islamic, African, and Arab Republic.' It provides for an executive president, elected for a six-year term, and for a bicameral legislature, consisting of a national assembly and a senate. The first presidential and legislative elections were held in 1992 under United Nations' supervision. Mauritania's economy is predominantly pastoral, and the country depends heavily on foreign aid. Its principal export industries are iron ore mining (about ten million tonnes per annum from mines near Fderik in the north) and fishing. Mines d'Or d'Akjoujt SA (MORAK), a company in which General Gold Resources NL (GGR) has 42.5 per cent equity, produces over 50 000 ounces of gold per annum, which represents the third largest export industry in the country.

Jan 1, 1996

Segregation of granular material is a very common phenomenon. Realised in a forced manner it is a basis of all separation processes in mineral processing, mainly classification and beneficiation. Spontaneous segregation, occurring under dynamic conditions and making possible mutual translocations of grains, is however an undesired phenomenon as a rule. It decreases the degree of blending of the material which in many cases is an important technological feature of the material. It should be noted that the segregation can be treated as the reverse phenomenon to blending. The importance and frequency of spontaneous segregation has caused many rules and technical solutions to be developed aimed at decreasing the possibility of the spontaneous segregation. However, not enough attention has been focused on an quantitative description of the phenomenon of segregation, either to ways of quantitatively evaluating segregation effects or to explanation of the influence of conditions under which the grained material exists on the occurrence of segregation and its degree. The paper presents the following topics: 1. new numerical indicator for evaluation of the segregation degree (and blending) of material contained in an arbitrary determined region is proposed; it is determined relative to the maximum possible degree of segregation of the given material when taking into account its individual properties; values of the indicator can be calculated effectively for an arbitrary material, also for ulticomponent material. 2. there is proposed a way of evaluating the state of segregation (or blending) of material in an arbitrary part of the region mentioned above, based on investigation of the gradient of distribution of the material features; algorithms of analytical procedures and calculations are presented for typical cases met in mineral processing; 3. results of initial experimental studies, both laboratory and industrial, concerning the effect of the chosen factors occurring in transport and storage of the material on its degree of segregation are presented; and 4. conclusions referring to the fundamental and practical significance of the results are also presented.

Jan 1, 1993

By E Widzyk-Capehart

The conventional ammonium nitrate fuel oil (ANFO) loader utilises a pneumatic system to control the flow of ANFO (via rotary actuator/ball valve) and air (via an auxiliary air valve). This system, though relatively simple and reliable, has several drawbacks with respect to ease of control and level of automation. In this paper, a radio frequency (RF) remote control for explosives charging is discussed. The system design incorporates electric solenoid valves to control the rotary actuator and the auxiliary air valve. All operations associated with explosives charging are selectable at the remote and are completed according to a modifiable time sequence. This allows the following charging sequence to be reduced to a single momentary application of the remote:removal of water from the hole prior to charging with ANFO; charging of the hole for a preset but adjustable period of time; and removal of the remaining ANFO from the ANFO hose. A specially developed remote switch allows the operator to maintain two-handed control of the ANFO hose whilst achieving full control of the charge-up process. Failsafe electronic architecture is incorporated into the systemÆs design to increase safety to the highest level. Should the RF remote control fail, a wired remote is included in the system to allow for the charging process to continue, albeit at a reduced level of control. The application of the RF remote control system in an underground explosives charging operation minimises and/or eliminates many problems associated with the use of the conventional charging system. These include: the wet-hole problem, trip and entanglement hazards, air embolism and the two-man loader control requirement. The developed remote control unit proved to be effective at removing water from wet holes leading to increased face advance per drilling operation. It proved to be economically feasible, allowed for an increase in systemÆs dependability and safety factor and for a truly one-man operation which resulted in reduced manpower.

Jan 1, 1999

By Mozley R

Contaminated sediments are a multinational problem. A crucial factor in solving an environmental problem is knowledge of, not only the amounts of polluted soil, the contaminants involved and their concentration, but also the historical background of the problem. Processing polluted soil is a tailor made activity based on rational decisions resulting from a detailed treatability study. Lack of information about characteristic properties of a specific sludge/pollution combination is the main obstacle in the route from first ascertaining that a particular harbour subsoil is polluted, to final identification of the full scale treatment plant. In the first instance, information must be generated regarding the distribution of pollutants in relation to the distribution of the original geophysical components. Based on this information rational decisions can be made on separation at a particular cutpoint and what sequential techniques should be involved for a certain fraction. For this purpose a `fingerprint method' is presented especially developed for investigation of polluted soil and sediments. The heart of the fingerprint method is a series of sequential hydrocyclone separations, by which a series of products is generated. The objective of the fingerprint method is to select an optimised treatment procedure in which the pollutants are concentrated in as small a volume of material as possible, leaving the bulk of the material clean. The pollutants can then readily be destroyed or isolated from the environment. The philosophy and advantages of the fingerprint method are demonstrated for a harbour sludge containing heavy metals as main pollutants. Hydrocyclone separation combined with flotation of both the coarse and fine fraction resulted in reusable and dischargeable products. Flotation of the fraction of fines was carried out by means of an experimental flotation cyclone enabling the selective recovery of mineral particles with diameters less than 10 microns. The overall conclusion is that design and engineering of treatment flow schemes for polluted dredged materials is a tailor made activity based on rational decisions resulting from the fingerprint information.

Jan 1, 1993

By D Clarke, R Simpson

The Main lode in the Anwia Gold deposit is difficult to interpret due partly to the fact that three separate grid and drill hole orientations exist over the area and partly due to a lack of understanding of the controls on the high-grade mineralisation. Scattered high gold grades and multiple veining orientations add to the confusion. Sectional interpretations of the lode are often misleading due to the multiple orientations of drilling. Initial attempts to define a high-grade constrained geological model were not successful due to the inability to establish any geological continuity that would hold together in three dimensions. As a consequence the initial geostatistical domaining for the Main lode at Anwia comprised a simple broad mineralised envelope split by the weathering profiles. Subsequently an analysis correlating subjective qualitative logging information with grade plus utilisation of LeapfrogTM software, together with extensive geological re-interpretation resulted in the definition of a coherent high-grade shoot within the Main lode. The resource was re-estimated including this new domain as a high-grade hard boundary. Estimations on both models were carried out using uniform conditioning, which is a recoverable resource estimation methodology that estimates tonnages and metal above a series of cut-offs for SMU (selective mining unit) sized blocks. This paper compares the tonnages and metal contents that are calculated from the two estimation runs, both at a zero cut-off and a series of higher cut-offs. The results confirm that the estimation methodology has been implemented correctly as the tonnage and metal content at zero cut-off is the same for both models. The resource tabulations and grade tonnage curves predicted by the two models highlight the differences that can occur at higher cut-offs when realistic high-grade domaining is implemented. The results also reinforce the point that recoverable resource models are intended to address selectivity issues and are not substitutes for good geological modelling. Recoverable resource techniques, such as uniform conditioning, will not correctly estimate high-grade zones that have not been explicitly modelled.

Jan 1, 2006

Over the past seven years, a combination of New Zealand-, Australian- and German-led research voyages using the research vessels Tangaroa, Southern Surveyor, and Sonne respectively, have revolutionised our understanding of the Kermadec-Tonga arc-backarc systems. This convergent margin is the most seismically-active subduction zone system on Earth with convergence rates steadily increasing northwards from the Hikurangi Trench to ~250 mm/year at northern Tonga. In combination with the intra-oceanic setting, factors potentially producing magmatic, tectonic, and hydrothermal variability in this system include an increase in potentially subductable sediment northwards along-strike, intersection of the Louisville Ridge (hot-spot chain) and Osbourn Trough (paleo-spreading centre) with the arc at ~25¦S, and the possibility of Samoan (hot-spot) plume ingression in the northern Lau Basin. The bulk of the magmatism is submarine; whereas only a few emergent (some transient) volcanic islands exist, about 80 submarine volcanic centres of significant size (>1000 m above surrounding sea floor) are present between White Island in the south to north of Tafahi in Tonga. About 35 per cent of these centres are hydrothermally active. Important petrogenetic features of the volcanic rocks along this arc system are the abundance of rhyolite (some quartz-amphibole-bearing), and the outcrop of primitive olivine-clinopyroxene-phyric basalts in satellite cones of the major edifices. Many of the edifices consist of complex caldera systems. Eruptions from and degradation of these edifices were probably tsunamigenic. Many of the hydrothermal systems developed within the edifices are likely destroyed during the sector collapses which are the characteristic edifice degradation mode. There are three backarc spreading systems along this margin: the Havre Trough, Valu Fa-Eastern Lau Spreading Centre, and the nascent Fonualei Rifts. The latter are particularly notable in having captured the entire suprasubduction zone magmatic flux for a distance of about 150 km, shutting down the adjacent volcanic front arc volcanoes.

Jan 1, 2005

By Buisman C. J N, Koch R. O

Soil and groundwater beneath the Budelco zinc production plant at Budel-Dorplein (The Netherlands) are contaminated with metals and sulphate. To avoid contamination of nearby drinking water aquifers in the very distant future, a geohydrological containment system (GCS) and a microbial treatment plant for extracted contaminated groundwater have been developed. As a first step in the design of the system groundwater data from over 150 wells and geological profiles were used to model geohydrological conditions beneath the site. Several configurations of water-extraction wells were deduced from the model. Data gathered during additional fieldwork were then used to improve the model. Finally results that were calculated for the various configurations were used to select an optimal groundwater containment system. Currently some 5000 m3/day groundwater are extracted from a combination of 12 shallow and deep wells. Heavy metals and sulphate have to be removed from the extracted water before it can be discharged into the river system or used as process water. Several water treatment methods have been studied and pilot-tested at the site. The preferred and selected process is based on the activity of sulphate reducing bacteria (SRB) and combines sulphate removal and heavy metal removal in one single step. The anaerobic bacteria reduce the sulphate to sulphide resulting in the precipitation of metal sulphides. A pilot plant gave promising results and a commercial-scale plant has been designed. The proposed design has been tested in a demonstration plant which included all main process units. Test results for all process units are presented. The collected information was then used to optimise the design of the commercial-scale plant. Special attention was paid to automation and safety items. Construction of the plant was finished in May 1992. Start-up, commissioning and operational experience are reported. The concentrations of metals and sulphate in the effluent of the SRB water treatment plant are well within the limits set by the authorities for discharge to public waters.

Jan 1, 1993

By V M. Silva, P A. A Martins, V O. Matthew, A L. S Fonseca, E B. Cunha, A J. D Ferrari, E M. S Silva, A C. Silva, D R. T Vilela

The Anglo American phosphate mine is located in the Brazilian state of Goiás and possesses one of Brazil’s most important phosphate rock deposits, with the site being the country’s second largest producer of phosphate rock concentrate. Despite the site having been in operation since 1979, the mining team only started using explosives in 2004 when rocks with greater hardness started to appear in the mine’s geological profile. Rock excavation was previously performed mechanically. Until 2013, only rocks with high hardness were blasted, this following the standard drilling grid that was defined in 2004 without any changes in the blast parameters. The aim of this paper is to show how fragmentation optimisation has yielded positive results at all stages of the production chain, from the mine to the mill passing through an impact hammer crusher, a rod mill and ball mill, operating in close circuit with hydrocyclones.While incorporating the mine to mill holistic approach during the operational integration, the focus was on defining the blasting domains and respective optimal fragmentation and measuring the benefits of blasting in terms of reduction in energy and grinding media consumed in the comminution processes. In the first stage, the blasting team made changes to the blasting parameters and assessed the effects of these changes on fragmentation using computer software and on-site measurements. This generated a database that made it possible to divide the mine into blasting domains. For the second stage, teams from the plant, geology, mine planning and operation departments jointly made comparisons between the performance when processing stockpiles, which only included high hardness blasted ore (20–30 per cent of blasted ore). Changing the drilling grid’s size from 3.0 m × 3.8 m to 2.0 m × 2.6 m for high hardness rock with the presence of silicates resulted in a 40 per cent reduction in the P80 for the blasted material (from 459 to 278 mm), while changing the grid from 3.0 m × 3.8 m to 2.6 m × 3.2 m for high hardness rock without the presence of silicates generated a reduction of 25 per cent (from 270 to 204 mm). There were gains observed from the measurements at the mineral processing plant in terms of specific energy spent on comminution and on the consumption of grinding bodies in the rod mill. There was a measured reduction of circulating load during secondary grinding and a reduction in slime generation.CITATION:Silva, A C, Martins, P A A, Silva, E M S, Fonseca, A L S, Ferrari, A J D, Cunha, E B, Silva, V M, Matthew, V O and Vilela, D R T, 2015. Fragmentation optimisation – adopting mine to mill for reducing costs and increasing productivity, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 363–368 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By C T. Dunbar, P A. Walker, G E. LeJuge

A programme of blast improvement was initiated at the Mt Whaleback iron ore mine by BHPIO management in early-1998. One component of that work was the need to improve wall control blasting practices to better achieve the designed pit slope elements. This paper describes the geological conditions in which pit walls are developed, the mine operating equipment, the blast design concepts applied to minimise blast damage, the techniques applied in an assessment of the blast performance and the operational procedures developed to ensure that the blast concepts are effectively implemented in the production environment. Substantial changes have been implemented in both technical and operational aspects of the mining operation in order to achieve the improvements in pit wall condition, in particular recognising the need for a more flexible approach to limits blasting in response to highly variable and complex geology. The benefits to the mine are not only an improved wall condition, but increased confidence on the part of mine management that mine plans may be implemented on design and on schedule.

Jan 1, 2001

By L Drowley

The Adelaide Desalination Plant (ADP) draws raw sea water into the facility and returns saline concentrate to the Gulf St Vincent via subsea conduits. This paper describes the detailed design and construction methodologies developed for the cross connection tunnel excavation. The paper concentrates on key design elements which include:· lateral breakout support of the segmental tunnel lining,· ground improvement grouting in the zone of the cross connection tunnels due to extremely variable and weak ground conditions, and· excavation methodologies and proposed support types of the riser to tunnel cross connections.The design process consisted of developing concepts, detailed risk assessment, three-dimensional (3D) finite element modelling and structural analysis for temporary support of tunnel lining; functional design of the ground improvement grouting and the temporary support; and permanent lining design of tunnel to ocean riser connections in a mixed soft ground/hard rock environment.The paper also presents conclusions of the design based on construction data available, and highlights the close collaboration between the design team and construction team.

Mar 8, 2011