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The Channel Tunnel is an outstanding example of an undersea tunnel and its design illustrates most of the unique features of this type of tunnel. The marine site investigation was partic- ularly vulnerable to adverse weather conditions. To minimise this interference the time the drilling vessel was required to remain on station was kept to a minimum by expediting the drilling and the insitu tests as far as was practicable. To avoid additional unforeseen costs the contract documents were framed to take particular account of marine practice. The limited access at the coast line meant that for economy, maximum tunnel advance rates had to be attained. Ground excavation, handling and disposal methods and the provision of the lining were optimised and equipment specified in detail to ensure that no one com- ponent was delayed by a lack of capacity or mechanical failure in any other.

Jan 1, 1976

By Bell I. F

In 1985, ZC Mines (now Pasminco South) had been unprofitable for some years due to a combination of high operating costs, low metal prices, low head grade and an aging and inadequate mining infrastructure. However, the resource of metal in the ground was still of world class, even after some 80 years of mining. A major study, which was to be of two years duration, was therefore commenced to establish a practical and profitable long term mining strategy and to cost the infrastructure options needed for its support and thus form the justification for a capital expenditure program to take the mine profitably into the 21st century and its second century of operation. This paper discusses the rationale behind the methodology adopted and the nature of the results achieved in one aspect of the study - the determination of the mineable resource and the relationship between the head grade/quantity of the economically mineable resource and the variables of cut-off grade, cost structure, annual production rate and metal prices/exchange rates. The basis of the study was the designing of some 5000 scopes to mine out the entire resource for a range of cut- off grades and the assembly of the detailed physical data thus obtained in a stope-by-stope data base for financial and other analysis. Those scopes which were shown to be economically mineable were then scheduled for two optimum annual production/cut-off grade/metal price combinations to provide life-of-mine cost and value of production cash flows.

Jan 1, 1992

The non-renewable energy resources of Queensland comprise coal, petroleum (oil and gas), oil shale and uranium. Coal is widely distributed., and has been developed extensively both for export and for use within the State. Proven reserves total 5 390 million tonnes recoverable of coking coal and 5 580 million tonnes recoverable of non-coking; very large resources particularly of non-coking coal are still to be quantified by further drilling. Annual production is of the order of 20 million tonnes of coking coal, principally for export, and 6 million tonnes of non-coking, mainly for power generation within the State. Petroleum resources are meagre in com- parison with those of coal. Initial recover- able reserves of liquids (mainly in the now substantially depleted Moonie Oil Field) totalled only 4.2 million m3. Initial recover- able reserves of gas (mainly in the western Surat and Bowen Basins) totalled 7 800 million m3. Annual production is of the order of 64 thousand m3 of liquids for refining in Bris- bane, and 268 million m3 of gas mainly for production of fertiliser and for industrial and domestic heating, in Brisbane. Prospects are fair for the discovery of additional reserves. Two deposits of oil shale are potentially of economic significance. The Rundle deposit at The Narrows in central Queensland has the

Jan 1, 1979

Brief summary of results obtained by a French-Japanese cooperative study on the bottom of trenches around Japan. The geophysical prospection, multi beam echo sounding and direct observation with submersible dives of the trench bottom clarified the details of the subduction of oceanic plates. It may be noted, among many new facts found: 1. The subduction and geologic structure resulted from the process is different according to the nature of subducting oceanic plate, and the geology of the land behind the trench. Thus the Nankai trough characterized by the developpement of accretionary prisms is contrasted to that of the Japan Trench where the basement rocks are exposed on the land side cliff of the trench wall. 2. The compressional tectonic situation prevailing in the trench bottom provokes the venting, along the fissures on the bottom, of water contained in sediments. Hydrocarbons contained in the sediments are comming out with water and give nutrients for bacteria. Clams, tube warms, sea slugs and shrimps are taking these bacteria as their food and biological communities with exceptionally dense population for the deep sea of more than 3000 meters in depth are formed on the field of accretionary prism and wall of the land side cliff. 3. An intense compressional tectonic field resulted from the subduction is inducing the transition from the subduction of oceanic plate to the collision of a part of the plate to the continental plate.

Jan 1, 1987

By Grossi M, Baiden G

This paper describes a new mine backfill method based on a newly invented binder with several years of test results from laboratory and on- site applications. The new binder has several advantages over traditional Portland and slag cement binders. One tonne of the new binder can replace two to three tonne of Portland cement when used to consolidate backfill and can result in the same compressive strength within seven days. When comparing backfill slurries of the same pulp density, the new binder attains more volume of in-place backfill mass than Portland cement because of the high crystallisation of water, resulting in tightly filled stopes. The crystallisation of the water provides for less or no de- watering in the backfill stope and easier transportation of the backfill slurry. Pastefill performance can be achieved by using pulp densities typical of a hydraulic backfill and the new binder, all the while transporting with the same ease of hydraulic fill.

Jan 1, 1998

By P Breuer, A Simons

The sulfidisation, acidification, recycle and thickening (SART) process is currently being used at NewcrestÆs Telfer Gold Mine to recover cyanide and copper from the cyanidation tails of the pyrite concentrate carbon-in-leach (CIL) process. While the process has been effective at attaining high recoveries of cyanide and copper, the Telfer SART plant has experienced higher than expected sulfide additions to achieve these recoveries. This paper details the results of surveys on the Telfer SART plant, which show that residence time appears to be causing the high sulfide consumptions. The paper also details the results of laboratory scale experiments which confirm the observed residence time impact during the acidified stage of SART.CITATION:Simons, A and Breuer, P, 2013. The impact of residence time on copper recovery in Telfer Gold MineÆs cyanide recycling process, in Proceedings World Gold 2013 , pp 189-196 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By Waghorne E. P

The State Electricity Commission of Victoria is Australia's largest single coal producer. Approximately 19 Mt of coal will be produced in 1989 from the SEC V's newest mine, Loy Yang Open Cut (LYOC), which com- menced overburden stripping operation in October 1982. When the adja- cent Loy Yang Power Station is completed in the late 1990's, LYOC will supply between 35 to 45 Mt/a, depending on power station performance and demand of coal for non-power generation uses. LYOC has been a major challenge for the SECV. It is the biggest single open pit coal mining development undertaken in Australia, with a whole of life capital cost approaching A$1 billion. The mine has supplied a very rapidly growing demand for coal from the expanding power station while developing in breadth, length and depth. Coal demand has consistently been above the figures anticipated during the initial planning because of the substantially improved performance of the 500 MW units of the Loy Yang A Power Station. The superior performance of the LYOC and power station has generated additional electrical energy during the first 5 years of power station operation compared with the initial planning targets- at almost no additional capital cost. This has been a major benefit to the SECV. LYOC will continue to present major challenges for the SECV, particularly in achieving overburden removal and coal reserve targets as development of the open cut continues to full depth over the next 15 years.

Jan 1, 1989

By J Chan, T Baumgartl, A Plante, C Peltre, P D. Erskine

Mine soils are often organic matter and carbon poor due to disturbance, topsoil stockpiling and mixing with spoil. They present an opportunity to observe the accumulation of soil carbon arising from rehabilitation or ‘green carbon’ through organic matter inputs and may be considered for carbon credits. Soil carbon is known to improve multiple soil characteristics and is viewed as an indicator of soil health.When attempting to estimate soil carbon levels in the Australian coal mining regions, both coal and black carbon (BC) need to be quantified. Coalmine soils contain coal particles that are difficult to distinguish from organic matter using standard carbon analyses. BC, a material arising from the incomplete combustion of organic matter and fossil fuels, displays some similar characteristics to coal and is ubiquitous in Australian soils due to bushfires. The presence of coal and BC complicate the determination of green carbon levels in mine soils.A method to quantify coal and BC in mine soils from the Bowen Basin using thermal analysis and multivariate curve resolution is presented. By determining BC and coal contributions it is then possible to calculate green carbon levels in rehabilitated mine soils. Calculated green carbon levels are compared with bulk density as soil quality indicators.CITATION:Chan, J, Baumgartl, T, Erskine, P D, Peltre, C and Plante, A, 2014. Distinguishing carbon fractions in coalmine rehabilitated soils, in Proceedings Life-of-Mine 2014 , pp 491–498 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

The segment of the Upper Cenozoic volcanic chain (CVZ) located on the western border of South America (16-28¦S lat.) is constituted by an association of strato- volcanoes and ignimbrite sheets, with high K calco-alkaline affinities. Strata-bound volcanoes, mainly of andesitic and dacitic composition, present along the whole chain, and various hydrothermal alteration zones, on the slopes and in the cores of eroded volcanic structures. Some of these altera- tion zones bear epithermal precious metal ores and sulphur deposits, which at present are being exploited. The studied Salar de Gorbea area, located in the Andes of northern Chile (25-26¦S lat.) contains a numer- ous group of Miocene to Quaternary stratovolcanoes, with advanced argillic and extreme silicification hydrothermal alteration in their cores and on their slopes, favoring the formation of great volumes of alunite within altered zones and sulphur deposits in the higher parts of the volcanic edifices. Simultaneously, siliceous hydrothermal breccia of the phreato-magmatic type, with evidences of hydromag- matic explosions are recognizable, allowing, in some cases, the ascent towards the surface of rock fragments belonging to the Paleozoic pre volcanic basement. Radiometric ages obtained in some of the hydro- thermal alteration zones (K-Ar in alunite) are slighty young- er than the unaltered rocks which constitute the strato- volcano. Trace element (Hg, As, Sb, S, Au, Ag, Cu, Pb, Zn, Mo) patterns in orientative rock samplings show that the studied alterations zones correspond to high sectors of the cpithermal system, without evidences of metallic minerali- zation on surface. The weak erosive action due to the ex- tremely and climatic conditions in this segment of the Andes, has not allowed the cropping out of deeper areas of the hydrothermal alteration zones, in contrast to other Miocene more eroded volcanic edifices and Miocene vol- canic terranes of the Andean Range.

Jan 1, 1987

By J Shillabeer

Paste backfill has been adopted by many underground mines in North America and a growing number elsewhere. Paste offers a number of advantages. This paper suggests wider applications of paste technology to surface tailings disposal and water management. Advantages include improved overall stability, potentially easier permitting, smaller water inventory and earlier reclamation. It may be feasible to use the same plant to prepare backfill and to dispose of surplus tailings. Example cost models are given to illustrate potential applications.

Jan 1, 1998

By J Millard, K Sexsmith

BHP Billiton Diamonds Inc (BHPB) has been mining kimberlite from several pipes at the Ekati Diamond MineTM located 300 km north of Yellowknife since 1997. Processing of kimberlite produces coarse kimberlite rejects (CKR, 0.5 to 8 mm) and fine tailings (less than 0.5 mm). The CKR are trucked to the Coarse Kimberlite Reject Storage Area (CKRSA) located within the drainage area of the tailings impoundment (Long Lake Containment Facility û LLCF). The coarse rejects are wet when dumped and are expected to freeze as a result of annual average site temperatures of about -10¦C. Seasonal thawing occurs along the exposed edges of the pile. Monitoring of the CKR indicates they have consistently low sulfur concentrations (0.4 per cent) accompanied by high acid neutralisation potentials (78 to 337 kg CaCO3/t). Carbonate concentrations vary from 0.9 per cent to 3.4 per cent. The CKR are therefore not potentially acid generating based on conventional laboratory testing. Monitoring of stagnant pools on the tundra downgradient of the CKRSA has shown that water originating from the pile resembles acid rock drainage (ARD). Water pHs can be less than 4, and sulfate concentrations are typically in the thousands of milligrams per litre. Conventional flowing toe seeps are pH neutral but also have elevated sulfate concentrations. Investigations conducted in the summer of 2002 revealed no evidence of in situ acid generation. Pore water chemistry is probably controlled by oxidation of fine-grained pyrite, neutralisation of acidity by calcium and magnesium carbonates and silicates, and freeze concentration of pore water. The acidity observed in tundra pools downgradient of the CKRSA appears to be a result of leaching and mobilisation of iron under reducing conditions at the CKR-soil contact. Downstream of the CKRSA, reduced iron oxidises and is hydrolysed on contact with the atmosphere causing pH depression. BHPB is applying the findings of this study by constructing facilities containing kimberlite on granite pads. These in turn are placed on frozen ground so that the foundations remain frozen and limits contact of wastes with the acidic soils.

Jan 1, 2003

By Brosnan J. G

Simcoa Operations is the only silicon smelter in the region and since the plant was commissioned in late-1989, has progressed from supplying silicon metal to the secondary aluminium market to the current position of supplying in excess of 90 per cent of its production to the high quality chemical and primary aluminium markets. This position has been achieved through the unique advantage which Simcoa has developed within the industry, namely raw materials, people and Simcoa's ability to adopt and use modern technology. A quality culture was instilled into the workforce prior to commissioning which ultimately led to AS3902 qualification in 1992. Simcoa has continued its quality drive through the formation of 'Simcoa's Quality Leadership Process' which is planned to make Simcoa the best silicon producer in the world.

Jan 1, 1995

By S Vink, A Wolhuter

Increasingly the community and government regulators are calling for æzero dischargeÆ mines. Some mining companies are beginning to explore ways in which they can transition to zero discharge. When striving to attain zero discharge, mines must consider multiple variables in addition to water quantity. These include climate regime, water quality and regional water budgets. This paper explores the drivers behind the concept of zero discharge mines and will use examples to illustrate the feasibility of attaining this goal.CITATION:Wolhuter, A and Vink, S, 2013. Is zero discharge a viable or useful concept in mine water management?, in Proceedings Water in Mining 2013 , pp 329-334 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By G W. Wilson

Net solar radiation is one of the key factors affecting evaporation from soil covers on waste rock dumps. While net solar radiation is normally taken as a uniform parameter over a site for modelling purposes, there can be significant variation in the radiation actually received on various portions of the dump. These variations are a function of the difference in the cover slope and direction of exposure. A predictive model has been developed to calculate the actual radiation received on the dump surfaces, based on the net radiation data measured at a weather station on a horizontal surface. The model has been designed for application at any mine site in the world, and can be used in conjunction with evaporative flux models to help estimate the effect of three-dimensional variations in the cover surface exposure. The waste rock dump at Equity Silver site (located in British Columbia, Canada) has a barrier-type soil cover system to limit oxygen entry and water infiltration. This cover has been monitored for the past nine years. The new net solar radiation model has been applied to this site and the predicted net radiation was compared to the values of actual net radiation measured on the site. The predicted variations in net radiation over the three-dimensional surface of the waste rock dump have been applied to calculate spatial variations in potential and actual evaporation (or evapotranspiration) from the site. Preliminary analyses indicate actual evaporation from a site at this latitude could vary by a factor of two for exposed versus shaded slopes. The implications of these variations for the site are considered.

Jan 1, 2003

Most compact bucket wheel excavators in use are in the small to medium range. Large compact bucket wheel excavators compete directly with con- ventional longer boom excavators which have operational advantages over the large compact. There are, however, situations where the large com- pact excavator is viable. In the development of these large compacts there are a number of technical features to be addressed. In addition the SECV now propose to expand the concept to a large compact bucket wheel excavator with a bridge and loading unit for their Loy Yang Open Cut.

Jan 1, 1989

By L Abrahamsson

This paper describes results from a gender study for a new mine in Pajala, a small community in northern Sweden. Using a gender perspective, the study examines migration, education, local culture, the labour market, and work organisation as problems and opportunities in the regional context for the planned mine. The most obvious ‘gender issue’ for the Swedish mining industry is the very low percentage of employed women, which is even lower among mining workers. To recruit the best people, a company actively needs to attract both women and men; however, the mining companies find it difficult to recruit women as cultural, labour market and educational traditions as well as the mining companies’ own cultures often make it difficult for women to find work in the mining industry.The Torneå river valley, the region surrounding Pajala, has a gender-segregated labour market and gender-stereotyped culture and few young women live in this traditional and oldish region. Many young people leave the region and this is especially true for women. Compared to the rest of Sweden, there is a low educational level, especially among the men. In the mining companies, as in many other male homosocial workplaces, the workplace culture has strong connections to a certain type of traditional masculinity (laddishness, a kind of ‘macho-style’) and for a long time this has excluded women. ‘Gender’, however, is not only a question of recruiting women to a male-dominated industry. An organisation that discriminates according to gender can become inflexible, hindering communication, learning, innovations and change processes. In mining companies, this can manifest itself in hesitant attitudes among the miners about safety as well as organisational and technological development.This study found that companies establishing a presence in this region should develop a strategy for how to deal with and manage the risks and opportunities in the surrounding society (the regional culture) as well as inside the company (the mining culture). This need to be strategic will also be required of future mining companies as they will face higher demands on safety, gender equality, and technology to become modern, efficient and lean organisations.

Nov 22, 2011

By Robinson T

The paper describes a spreadsheet system that enables selection of projects and companies that meet the user's corporate exploration and/or acquisition philosophy. A regularly maintained commercially available database has been used as the basis for this system. It provides an easily accessible efficient com- prehensive search method. The technique enables ranking by various criteria, both technical and financial, to provide groups of projects/companies that are of interest. Initially, target size parameters such as reserves, production and mine life are applied together with geological criteria such as age and deposit type; the significance of the targets in the context of the Australian gold industry is addressed.

Jan 1, 1988

By Massacci P

A review has been made of the studies focusing on methods for the description of grain -size distribution after breakage and, separa- tely, of the degree of liberation of the miner- al species making up the various grain-size classes of comminution products. The purpose of the study has been to de- velop an overall model of the phenomenon which, owing to the very effect of comminution, leads to the formation of grains that are generally of mixed composition. A calculation procedure has thus been de- veloped for the liberation function taken as the assessment of the distribution of mix com- ponents in the products obtained after a commi- nution process. The aim is to identify a func- tion which may, to a certain extent, simulate the variation of the grade-recovery function of an ore in relation to its degree of comminu- tion. The numerical model thus obtained has been tested out on results obtained experimentally.

Jan 1, 1986

By Thomson I. R R, Friday R. G, Palmer W. T

The paper introduces the problems encountered in designing open stopes and briefly examines the factors that determine the final stope dimensions achieved after mining is completed. A case study is presented where monitoring of a stope was considered necessary due to the expected formation of a highly stressed crown pillar above the stope. The influence, on the mining approach adopted, of a yielding crown pillar is discussed. Monitoring and numerical modelling were used to develop an understanding of the behaviour of the particular stope as mining progressed. A comparison between the measured displacements and the numerical predictions at an interim stage of mining was carried out to assist in choosing the final sequences involved in completing the stope.

Jan 1, 1981

By A R. Bye

The mining industry is facing some key challenges that provide a compelling case for geometallurgy initiatives. Over the last 30 years, the average grade of Australian orebodies being mined has halved while the waste removed to access the minerals has more than doubled. In the last eight years, the industry’s energy consumption has increased 70 per cent while multi-factored productivity has fallen 24 per cent. The paper documents a broad range of industry case studies which demonstrate strategies for gaining value from geometallurgy.The mining industry constantly faces the key questions of how significant ore variability is on mine valuation and how would knowledge of the variability change the mining schedule, mine to mill design and operation. Using case studies the paper describes the methods used for incorporating mineral extraction attributes into orebody models and their technical integration into daily operation as well as mine planning optimisation. While pit optimisation from a fully attributed geometallurgical model highlights areas of opportunity and risk it is shown that during the scheduling phase of mine planning that significant value can be added. The benefits from these projects included reducing geotechnical and environmental risk, improving mine to mill performance, option analysis and quantified cash flow risk. There is growing acceptance within the minerals industry that ‘realistically assumed modifying factors’ defined by a competent person/s are not sufficient to mitigate the risk of funding mining ventures. Geometallurgy is moving away from factored ore reserves to data-rich block models providing reliable information for mining, metallurgical and environmental considerations.

Sep 5, 2011