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By J Howard

Following discovery in October 2004, commencement of development in February 2007 and first ore production in mid 2007, the Trident gold deposit, located in the Eastern Goldfields of Western Australia, has now been successfully mined for over three years. Three years of operational history has enabled the performance of the Trident underground mine to be reconciled against the mine plan and strategy proposed for the original feasibility study.The Trident deposit, initially based on two lode systems known as the Eastern Zone and Western Zone, has been continuously drilled, interpreted and re-interpreted over the period and as a result the addition of the Athena, Apollo and Artemis lode systems as well as numerous smaller scale lodes has been realised. The first three years has seen the Trident underground mine quickly move up to its 1 Mtpa design production rate. The mine plan and strategy used in the initial feasibility study and subsequently implemented, required sufficient flexibility to enable modification and optimisation to mine plans as ore zones were further defined. The ability to modify the mining plans has enabled Avoca to achieve its mining targets at Trident. With over 250 000 ounces gold produced to January 2010, the company is well positioned to achieve its ten year vision associated with the Higginsville Gold Project.This paper offers an account of operational experiences whilst providing comparison to assumptions and methodologies used in the original feasibility study. The paper is a sequel to a paper presented at the Tenth Underground Operators’ Conference held in Launceston, Tasmania titled Development Strategy of the Trident Underground Gold Mine.

Mar 21, 2011

By A N. Parry, G van Wyk

"Sensor based automatic ore sorting technologies are used in the minerals industries to efficiently remove waste and submarginal grade material from crushed and screened run-of-mine (ROM) ore, producing a coarse (typically >10 mm) upgraded preconcentrate at an early stage in the mineral processing circuit. This avoids additional energy intensive downstream processing of this rejected component of the ROM feed, leading to lower unit operating costs and reduced tailings disposal volumes.Test work on bulk low-grade gold ore stockpile samples from Central Norseman Gold Proprietary Limited has been conducted, indicating high gold recoveries as well as high material rejection rates. A financial model, based on these results, evaluates grade sensitivity and identifies a minimum stockpile grade for adequate financial returns. The base case modelling estimates that the ex-stockpile grade (including the fines bypassed fraction) can be more than doubled through ore sorting and that the project will be highly viable with strong cash flow generation at stockpile grades as low as 0.7 g/t gold. The modelling will enable the company to benchmark ore sorting options against stockpile reclaim and screening operations currently employed. Citation:Parry, A N and van Wyk, G, 2016. Upgrading Low-grade Gold Ore Stockpiles by Preconcentration Using Ore Sorting - an Assessment of the Economic Impact and Viability, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 179–190 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By G S. C Murray

Major mining projects are developed with the assistance of lending institutions who provide hundreds of millions of dollars in funding over several years, and of course expect those funds to be returned with interest. Two Australian banks have adopted the Equator Principles, an emerging financial industry benchmark for assessing and managing environmental and social risk in project financing. Project financiers have encountered environmental and social issues that are both complex and challenging, particularly with respect to projects in the emerging markets of Asia-Pacific and elsewhere. There are many recent and historical examples of failures by resource companies to effectively manage their environmental, social, safety and security risks, some of which have caused the project to fail completely, and some of which have caused the temporary cessation of production. These events put the financial institutionsÆ funds at risk through inadequate management capacity and non-compliance adversely affecting the ability of the borrowers to repay the loans. They can also reflect adversely on the reputation of the lending institutions. In assessing these risks, lenders are increasingly looking at the track record of the borrower in its country of origin and in other countries where it operates. Lenders are wary of companies that have one standard for operations in a developed country, where the regulatory environment may tightly control what they do, and another standard for operations in countries where the regulatory regime is perhaps less stringent. Lenders may require environmental and social reviews or audits to be conducted on their behalf by competent third parties prior to a loan being approved, and annually over the life of the relationship. The mining industryÆs concept of the unwritten æsocial licence to operateÆ is highly relevant in relation to the delivery of community benefits that are sustainable post-mine closure. This paper provides examples of recent practices that support financial viability and sustainable development, as well as examples of some failures that have put lenders at risk.

Jan 1, 2007

By N Murthy

Alumina is a major impurity in Australian iron ores and as the higher grade ores become depleted there will be a stronger focus on treating lower grade haematite/goethite ores and developing suitable beneficiation techniques to reduce the alumina content. High alumina in iron ore is deleterious in that it can:• produce slags with lower desulfurising capacity,• reduce sinter/pellet strength and quality, and• produce higher slag volume and increase slag viscosity.Meeting iron ore quality specifications for alumina by blending ore from different sources will eventually be insufficient. Hence, innovative flow sheets based on new and commercially available technologies will be required. Their advantages and disadvantages, the testing methodologies and the challenges and diffi culties involved in reducing the alumina content of iron ores are presented and discussed.

Jul 11, 2011

By S Farrokhpay, C Akop

Copper-gold-pyrite ore types with an elevated pyrite head grade utilise a sequential flotation circuit to recover initially a copper-gold concentrate with a pyrite-gold concentrate being produced from the tailing of the initial circuit.A simpler flotation circuit with lower operating and capital costs for treatment of such copper-gold-pyrite ores with an elevated pyrite head assay was sought in the described work. After characterising the ore, the objective was to apply bulk rougher flotation of both the copper minerals and pyrite for the copper-gold-pyrite ore at natural pH. Hence, no lime or other pyrite depressants were required in bulk roughing. The bulk rougher concentrate was upgraded in a cleaner circuit to reject non-sulfide gangue and then the resulting sulfide concentrate was separated by depressing the pyrite to produce two products (copper and pyrite concentrates, both having significant gold assays). A standard test with a sequential circuit was applied to the same ore for comparison.The chalcopyrite and pyrite losses in the tailing from the rougher circuit were the same for both bulk and sequential roughing (less than six per cent). In cleaning (bulk circuit), the effective pH for pyrite depression was 11.8–11.9; copper recovery was 70–75 per cent (grade of 15–20 per cent copper) and the sulfur recovery (pyrite product) was 80–85 per cent (grade of 34–36 per cent sulfur).These results approached those for the sequential circuit where copper recovery was 80–85 per cent (grade of 15–20 per cent copper) and the sulfur recovery (pyrite product) was 83 per cent (grade of 38 per cent sulfur).The observed effects of feed sizing on the liberation of minerals in the rougher feed are discussed. Options for improving the bulk circuit results are also considered. Importantly, the implications of various aspects of these findings for the bulk circuit are discussed with an industrial focus.CITATION:Akop, C, Farrokhpay, S and Johnson, N W, 2014. An alternative circuit for chalcopyrite-pyrite ores with elevated pyrite content in Cu-Au ore treatment, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 407–416 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By S Novak

A world-class example of sustainable development in practice, the Local Resource Development Initiative (LRDI) grew from agreements between the Ambatovy nickel mine developers and the Government of Madagascar. A program of training and community development, the LRDI aims to maximise local benefits by optimising the integration of local resources during the construction period of the mine. By local resources, we mean the local labour force as well as local goods and services. Begun in 2007, the foundation of the LRDI is to integrate local resources into the mining project and where gaps are identified, design and implement training, mentoring and other programs to fill those gaps. The principal accomplishments are: the establishment of training centres that trained over 4000 people in little over one year, 96 per cent of whom hired to work at the mine; a support program for local micro, small and medium enterprises that has led to the award of 65 contracts for goods and services with training and mentoring of over 100 local businesses; and a number of special projects that have, among other results, strengthened local agricultural development and created employment for young people. The LRDI provides unique insights into key indicators and lessons learned to strengthen the social and economic sustainability of mining projects in developing countries. The paper will discuss these in terms, among others, of: the importance to project success of upstream planning to address socio-economic issues; the role of civil society and other local partners to strengthen and expand sustainability outcomes, and to spur governments to demand that major projects promote economic and social sustainability; and the integration of mine sustainability with sustained regional social and economic development.

Jan 1, 2009

Sampling protocols and metallurgical flow sheets should be designed to suit the style of mineralisation in question. In support, the a priori need for evaluation programs is the characterisation of the mineralisation type(s) and domain definition. The proportion and size of gold particles has a direct impact on the effectiveness of sampling protocols and metallurgical processes employed. Within the coarse- to-fi ne gold spectrum, the samplability of a deposit ranges from relatively simple for fine-grained disseminated particles, through to difficult for coarse gold mineralisation. Conversely, metallurgical processing may be relatively simple for coarse gold ore and more difficult for very fi ne gold ores. Most deposits contain a proportion of both particle size types. The nature of mineralisation, mineralogy and associated gold particle sizing can only be determined by preliminary sampling to facilitate testing. Mineralogical studies, focussing on ore mineralogy and gold particle deportment, size and distribution are required as part of wider paragenetic and geometallurgical investigations. This paper discusses key issues and presents a methodology for the determination of gold particle size in coarse gravity-gold ores to support sampling optimisation and which also contributes to metallurgical characterisation.

Aug 1, 2010

By F Burns, G Peachey

The Hidden Valley process plant has recently undertaken a program to relieve process flow bottlenecks and improve process automation. An environment of cost reduction and restrained capital necessitated solutions that primarily utilised existing equipment and internal resources. Removing bottlenecks relieved pressure from a strained circuit that was unable to maintain consistent performance. Improved process automation firstly stabilised the process, then allowed the circuit to sustainably operate at the expanded capacity limits. These allowed implementation of an operating approach that focused process operators towards identifying and resolving process disturbances in advance. Plant recovery and throughput have markedly improved as a result.CITATION:Burns, F and Peachey, G, 2014. Recent process improvements at Hidden Valley gold mine, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 43–54 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By N Lewis

Recent major urban trunk sewer infrastructure projects in Melbourne have involved construction of nearly 10 km of tunnel boring machine (TBM) driven tunnels in a range of geological conditions varying from soft alluvial soils to hard volcanic rock. To provide both construction and permanent access to the new trunk sewer network, a total of 17 shafts between 5 m and 13 m in diameter, and up to 64 m in depth have been constructed. This paper describes the design and construction of the temporary shaft support systems for the shafts.The range and variability of geological conditions at each shaft site required the adoption of the following shaft support systems across the projects – jet grouting, sheet piles, diaphragm wall, secant pile, contiguous pile, reinforced shotcrete rings and rock bolts.Groundwater control, settlement, TBM launch and reception chambers at the shaft base, chambers and TBM launches at mid-depth of shafts, connection shafts between new and existing sewers and bypass pumping shafts are among the challenges that have been met.This paper reports on the some of the challenges involved and experience gained in developing design and construction solutions for large diameter shafts that are excavated within varying geology in Melbourne over the past three years.

Mar 8, 2011

This paper presents the descriptions of a final year geological engineering project at the Royal Melbourne Institute of Technology involving the correlation of borehole and mapped ground conditions and their statistical Analysis.

Jan 1, 1994

This paper will provide an overview of the coal mining industry operating in the Wollongong area, covering: the history and heritage of mining in the Illawarra region;unique features affecting mining in the region û opportunities and threats;current mining operations in the area;challenges facing coal mining in the region, including managing environmental impacts and seeking community support for mining approvals; andthe future for coal mining in the region. The paper aims to showcase the size and history of the coal mining industry around Wollongong and to emphasise the specific benefits and challenges that are faced by companies operating coal mines in such close proximity to urban and environmentally sensitive areas.

Jan 1, 2008

By Sofoulis I

Recent studies in the Archaean of the Kalgoorlie-Norseman area show that the layered rocks can be subdivided into two main units, both containing basic igneous rocks and sediments. The lower unit is distinguished by the presence of acid volcanic flows and sills. In some areas, clastic sediments become coarser and,pas-s into conglomerates. This passage is accompanied by thinning of the beds. These features and their distribution suggest a basin of subsidence flanked-by areas of shallow-water deposition. -.

Jan 1, 1964

By Fuerstenau MC

Zinc cementation and carbon adsorption are both presently used for precious metals recovery from cyanide leach solutions. Each of these techniques exhibits unique processing features which renders them suitable to treat solutions with different properties and in different applications. In this study, the two processes are reviewed and compared. Operating data from a number of Merrill-Crowe precipitation and carbon adsorption plants in North America have been obtained and used in this analysis. The relative capital and operating costs for the two processes have also been considered.

Jan 1, 1993

With the introduction of the Health and Safety in Employment (HSE) Act 1992 and the subsequent repeal of regulations pertaining to mining, there has been an upheaval of the management of health and safety in mines.  More than ever, employers know that they must ensure that their workers are competent to carry out their assigned tasks.

Jan 1, 1997

Stress Mapping Technology is aproprietary technique developed to target epigenetic mineralisation located in dilatant (low stress) sites. It is a computer based technique, based on rock mechanics principles and stress-strain relationships, which seeks to transform strain data, in the form of a solid geology map, to stress data.The main assumptions in the conceptual model are that:The strain pattern of faults and lithological contacts have not been changed since mineralisation i.e. that ore formation is late in the structural history.Stress orientations and magnitudes are known.Rheological properties of faults and rock units can be deduced.The 2D geometric and rheological data is then treated by a mathematical technique which permits the geometry of the elements to be defined by the spacing and orientation of the discontinuities in the rock mass.

Jan 1, 1990

By Whiteley M, Robinson T, Vernon B

The Western Australian gold industry has approximately 100 operating plants, mainly CIP/CIL. The nature of the State's rapidly expanding gold industry gave rise to concerns over management of the cyanide hazard, in that most plants are remote from major population centres, have a workforce with a high turn over and use highly saline process water. Approximately 4,500 workers in the industry have the potential to be exposed to cyanide in the course of their normal work.This paper outlines the risk management strategy developed by Government and industry to monitor atmospheric HCN gas in the work environment and the role of continuing education and training along with regular site inspections by Department of Mines Inspectors.

Jan 1, 1990

The Granites Gold Mine has far exceeded the design capacity of 300,000 tonne per annum during its first sixteen months of operation. The presence of considerable free coarse gold has made it imperative that the gravity section operate at maximum efficiency. The inadequacy of acid digest- ing facilities and trying climatic conditions prompted management to initi- ate investigations into the use of Intensive Cyanidation as an alternative method for upgrading gravity concentrates prior to smelting.

Jan 1, 1988

Modern off-highway trucks have evolved over 30 years from small 20 ton units to vehic- les with capacities of up to 170 tons. Diesel engines are used by all manufacturers while transmissions are either mechanical or electri- cal. Development over the years has kept pace with component availability from engine, trans- mission and tyre manufacturers.Computer simula- tion studies are recognised for purposes of vehicle evaluation and costing under various op- erating conditions. Several manufacturers are currently manufacturing or evaluating vehicles with capacities of up to 260 tons. This paper describes the essential facts associated with the operation of off-highway trucks of the rear dump type in the mining industry.

Jan 1, 1973

By Mason P, Waller C

The Phase I electrowinning system at KCGM's Fimiston Operation utilised the well proven technology of electrowinning precious metal values onto steel wool followed by calcining and direct smelting to bullion. The above process, while reliable and successful, was to some extent labour intensive. The Williams Mine in Ontario, Canada had published conditions under which precious metal values are electrowon onto woven stainless steel and directly removed using high pressure sprays. The current paper describes the testwork which was carried out to check the applicability of the Williams criteria to KCGM eluates arising from the elution of highly loaded carbon from the calcine circuit and lowly loaded carbon from the float tails circuit. Information is also given on the commissioning and operational experience which occurred.

Jan 1, 1996

Field investigation of surface subsidence events associated with both active and abandoned underground coal mines in the United States has established criteria that enable the prediction and classification of mine-related subsidence. The key was establishing the role of geology in all types of subsidence and the recognition of beam subsidence in specific geologic settings. The classification is based on overburden thickness, variations in stratigraphy, topography and mine plan. Types of subsidence are Pit, Room, Sag, and Beam. Pit subsidence is associated with three geologic settings: shale overburden, seasonally wet unconsolidated overburden, and perched water table in unconsolidated overburden. Room subsidence occurs where the roof across the width of the room fails to the surface and a shallow depression develops.

Jan 1, 1992