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By G Jones

The Singapore Land Transport Authority (LTA) has been procuring the expansion of their underground mass rapid transit rail network at a prodigious rate since the first line opened in 1987. Four lines (149 km) are currently operating and several more lines are at various stages of planning/construction; one of these is the Downtown line stage 2 (DTL 2).DTL 2 contract C917 was awarded in September 2009 for S$320 M. On 18 June 2013 the original contractor became insolvent, leaving the works incomplete. Following a fast-tracked tender process, McConnell Dowell was awarded the S$254 M contract on 29 August 2013 to complete the works. This contract includes two underground stations constructed by cut-and-cover methods and twin bored tunnels between the stations. Each tunnel is 1400 m long, excavated by earth pressure balanced (EPB) tunnel boring machines (TBM) at an average depth of 20 m and segment lined to 5.8 m inner diameter. The tunnel alignment is located under a busy five-lane road lined with prime residential real estate and congested with utilities.To compound the difficulty the tunnels are located within the notorious Bukit Timah Granite formation. This has a very wide range of strength, from below 1 MPa to over 300 MPa. This strength range is a consequence of six weathering grades, from soil to fresh rock, with the fresh granite causing severe abrasion problems. The various grades can occur within a very short distance of each other. Consequently, the problem of supporting a mixed face exists, particularly in the intermediate weathering grades where intact rock is encountered in the invert and corestones within a loose soil matrix in the crown, which can increase the instability by allowing the ground to flow into the TBM.The focus of this paper will be the excavation of the bored tunnels by EPB TBM used by McConnell Dowell to complete these challenging works.CITATION:Jones, G and Shepherd, J, 2014. Earth pressure balanced tunnelling in a dense urban environment, C917A, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 41–50 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By S Harris, A Bossilkov

The Kwinana (Western Australia) and Gladstone (Queensland) industrial areas are among the few dozens of heavy industrial areas globally that demonstrate significant levels of regional resource synergies. Such synergies are also referred to as æindustrial ecologyÆ or æindustrial symbiosisÆ. Fundamentally they involve the exchange of by-products or sharing of utilities between companies in close geographic proximity to achieve competitive advantage and environmental benefit. A concerted research effort is currently underway to foster greater realisation of regional resource synergies in minerals processing intensive regions, in Australia and internationally. This paper summarises current insights from the foundation research into engineering tools and technologies and enabling mechanisms for regional resource synergy developments. Regional resource synergy developments were reviewed for 16 international and two Australian regions. It was found that Kwinana and Gladstone compare favourably with the well-regarded international examples of regional synergy development. Given the fairly strong evidence that self-organisation is critical for regional synergy developments, an implementation model has been proposed that captures entry points for synergy developments at the level of platform (industry collaboration), process (developing synergy opportunities) and project (assessing and implementing specific synergies). It was also found that regional synergies have so far developed in the absence of specific methods for identification and screening of synergy opportunities. Moreover, very limited attention has been paid to the associated technological and engineering challenges. The current technical research effort therefore targets: the development of a toolset for the identification and development of potential synergy opportunities; and assessment of technology needs and opportunities for regional synergies involving water, energy and materials recovery and reuse.

Jan 1, 2006

By Shrivastava P

The iron orebodies of the Pilbara region are formed by supergene enrichment of banded iron formation and rarely do such processes produce orebodies with uniform grade distrib- utions. The orebodies being mined or developed have to be worked to grade/quality constraints imposed by contractual agreement rather than natural characteristics. Hence it is imperative to use a non-biased ore reserve calculation method. The geostatistical study of a typical iron orebody is presented. Emphasised are the geological characteristics of the orebody manifested as a variable grade distribution of iron and impurities; the determination of variogram model; subsequent uses of the model for computation of ore reserves and kriged lock estimates; computation of dispersion variance and conditional simulation of orebody.

Jan 1, 1977

By J Moncrieff, P Bellairs

The Black Star Open Cut is located immediately adjacent to the township of Mt Isa and is situated in the middle of extensive pre-existing infrastructure including two concentrators, two smelters, a wet fill plant and two shafts. At any one time there are in excess of 500 people working on the surface within an industry-accepted 600 m exclusion zone from Black Star blasts. Apart from the surface operations there are also the underground operations including the lead mine (closed in December 2005) and the Enterprise and X-41 mines that must clear for all Black Star blasts. The application of industry standard blasting exclusion zones (600 m) was risk assessed as imposing operationally prohibitive constraints which could cause significant business interruption due to the logistical challenges required to ensure that all personnel from surface plants were evacuated for each blast and potential for lost production whilst these personnel were not operating the plant. In was therefore an imperative for the blast exclusion zone to be reduced. This was achieved by the: use of a QA/QC team to ensure that relevant drill and blast implementation is within an acceptable tolerance (KPIs) from design; use of high-quality stemming material called HMR, which is a by- product of the concentrating process and is generally sized at -14 mm with very little fines; implementation of appropriate training and support to Black StarÆs own blast crews, reinforcing the need to achieve the designed amount of stemming in every hole; and provision of appropriate support from Black StarÆs management for additional resources to ensure that every blast achieves design within the KPIs but especially in high-risk areas. The blast exclusion zone was successfully reduced after monitoring the flyrock results from more than 176 blasts. Black Star Open Cut now maintains a minimum blast exclusion of 200 m in critical areas; however, general blasting currently uses a 250 m exclusion as this provides additional risk management whilst still minimising the logistics associated with clearing and securing the slightly increased area.

Jan 1, 2007

Claiming the Green Revolution - Protecting Investment in Green Mineral Processing

Sep 13, 2010

Filter aids are currently used in many industries to increase filtrate clarity and filtration rates. In other industries filtration could be improved if accept- able filter aids could be obtained cheaply. The present paper describes a simple thermal process for making filter aids from coal, outlines the effects of coal properties and major operating variables, and discusses the properties of satisfactory products. Several possible variations in reactor design have been used experimentally, involving fluidized beds of carbon or inert material, reaction of the particles while entrained in air, and a combination of entrainment and fluidization. The limits imposed on product yields by the composition of the parent coal are considered in relation to a range of Australian coals and one New Zealand coal; and the effects of temperature, residence time, and reactant flow rates have been studied in relation to product yields and characteristics.

Jan 1, 1969

The Ladolam gold deposit, located on Lihir Island in PNG, is one of the largest known epithermal gold deposits, with a resource of over 37 million ounces. The deposit is characterised by a telescoped porphyry-epithermal system 2-rich sulphidic hydrothermal fluids capable of transporting significant quantities of gold, and the sudden change from porphyry to pithermal conditions caused by removal of the volcanic edifice. As magmatic ore fluids breached the surface, cool surface waters (seawater and/or meteoric) acted as a diluent. Although no other deposit is known with comparable geological characteristics and size, positive features that may be looked for in exploration for other like-deposits elsewhere include magnetite-rich alkalic volcanic rocks, large carbonate haloes, and presence of phreatomagmatic breccias. New discoveries may be recessive or undercover, due to the quartz-poor nature of the alteration.

Jan 1, 2002

By Bhattacharyya A. K

A strata parameter is introduced to include the deformation characteristics of the undermined strata in the prediction of subsidence movement. By using the strata parameter and mining factors as parameters, a nomogram for predicting the maximu

Jan 1, 1994

Territory Iron has seen fit to revive the old Frances Creek iron ore mine some 30 years after it ceased operations in AustraliaÆs Northern Territory. The key to this revival has been the changes that have happened since market forces, infrastructure limitations and a cyclone combined to force its closure. As it breathes life into this old mine, the Company is serious about its responsibilities to its shareholders, to its workers, to local and regional communities and to the environment. This paper addresses how Territory Iron has approached technical, operational and regulatory issues that apply in Australia. Some insight may be gained into the myriad of tasks that mining companies face to revitalise an old mine. These tasks vary from employing the latest exploration tools, best practice drilling, sampling and modelling of orebodies, optimisation of pit designs and schedules, maximising product value by blending, optimising infrastructure usage and minimising capital and operating costs. All of this has to take cognisance of commercial, environmental and other issues including Native Title.

Jan 1, 2007

By Ehlers HK

Mount Isa Mines Limited has 25 rod and ball mills of various sizes installed in two Concentrators at Mount Isa. A continuing investigation into installation, design and materials of liners for these mills has been in progress since the early sixties. Both manual and mechanical methods of liner installation are used and described. Materials for the various applications have been evaluated, mainly by field trials. Design of liners has also been evaluated by field trials and the history of trials in No.4 Concentrator is given. The purpose of the investigation has been to reduce the cost of mill lining and the life of many linings has been greatly increased as a result of this work.

Jan 1, 1978

By Channon W, Dube M, Makwana M, Kerfoot D. G

In early-1995, the Bindura Nickel Corporation commissioned a pressure leach plant at its Smelter and Refinery complex located in Bindura, Zimbabwe. The novel pressure leach process was developed by Sherritt to treat the nickel-copper sulphide residue produced from the original atmospheric leach circuit. The process extracts essentially all the nickel from the nickel-copper sulphide residue under non-oxidising acid pressure leach conditions, thereby producing an upgraded copper sulphide residue suitable for smelting and refining to electrolytic copper. The commissioning of the pressure leach plant was relatively smooth and design conditions were achieved within six weeks of operation. This paper presents a brief description of the process development and the plant design, followed by highlights of the plant start-up activities and summary of the plant performance.

Jan 1, 1996

Relationships between lead blast furnace performance and the composition and size distribution of sinter were determined from analysis of lead blast furnace operating data. Sintering plant practice was subsequently modified and substantially improved furnace performance resulted.

Jan 1, 1971

A geostatistical study is made of the drilling results available one stage prior to the present for a tabular deposit. The results show that the blocks required by the mining engineers could have been assessed by the earlier drilling grid with an accuracy significantly better than that obtained by applying conventional methods at the present stage.

Jan 1, 1976

By Sheer T. J

The increasing demand for underground cooling in South African gold mines has resulted in various cooling methods being con- sidered, including the use of ice. Two main areas in connection with ice cooling systems are being investigated. The first concerns the efficient and cost effective production of ice on a larger scale than previously required for any other application. The second con- cerns the transportation of ice in pipes from surface ice-making machines to underground melting sites.

Jan 1, 1988

The Tailings Leach Plant at Chingola employs a Leach/Solvent Extraction/Electro- winning process and contains the largest solvent extraction plant in the world, with design liquor flow rates of 55 m3/min. A pilot plant constructed to provide design data also indi- cated areas of uncertain operating and control performance and led to a decision to model the whole circuit to determine the overall dynamic behaviour and basic operating characteristics. Details of the plant flowsheet are given and the basic physical and chemical' equations required for the simulation defined. Each unit operation is considered separately and details of the mathematical models used for their simulation presented.

Jan 1, 1977

A Devonian metallogenic province is extended northwards from central Queen- -sland to the Burdekin Basin in the Charters Towers Gold and Mineral Field. Devonian sediments of the Burdekin Basin are intruded by mineralised quartz felspar porphyry which occurs as pebbles in Upper Devonian conglomerate. A mineralised volcanic complex lies on the crest of an anticline in Devonian sediments.Red siltstone is slurried and reduced to pyritic hornfels over folded limestone.A thick wedge of volcanogenic conglomerate overlain by marine shale lies on the mineralised rim of an ocean which suffered cataclysmic changes during Late Devonian times.

Jan 1, 1987

By Penney B. K, Baghdadi A. A

An electron probe micro-analyser, controlled by a dedicated mini-computer,has been operating at Imperial College since 1970. The data assessment capability of the computer was limited and, in order to make better use of the information produced by the analyser, extra computing facilities were needed. Following the initiation of a Laboratory Automation Project at Imperial College involving the use of a central computer linked to laboratory type computers and to further more powerful systems,it became possible to carry out much more detailed and extensive mineralogical analyses by connecting the mini -computer to the Laboratory Automation Network. The paper describes the techniques employed including hardware, software, inter- connection, analysis and operating methods.

Jan 1, 1977

By Scaife PH, Cripps Clark J, Cameron DB

Tuyere coke samples have been taken through the tuyere openings of B.H.P. International Blast Furnaces since 1978 with Whyalla No. 2 Blast Furnace taking samples on a regular basis since 1982. The degradation of coke during it's passage through the Blast Furnace can be measured and the relationships between these data, feed coke data and blast furnace operating data demonstrated. Tuyere coke sampling has been useful in revealing misleading external coke testing results and is still the method to monitor directly the performance of coke within the Blast Furnace.

Jan 1, 1987

The truly scientific method in the study of such questions at the present day is the reverse of that which was followed in the early days of geology, when after the observation of a few isolated facts, some great geological mind was led to a general theory, and humbler followers were only too apt to do mild violence to nature in order to make her facts conform to it tt accumulates year after year a multitude of facts of patient observation, supported by studies with the microscope, and in the laboratory, avoiding general theories, and only making such deductions in regard to locftl conditions as are supported by the overwhelming evidence of facts. S. F. Emmons, on the geological distribution of minerals in the United States, at the "world's congress" of mining engineers, Chicago. Fig. l.-This exhibits the general stratigraphical characters of the southern lodes. The" Indicator" veins, the great barren lode masses, a later fissure than all of these (" B "), and the auriferous lodes of last series cleaving the wrinkled terraces and the older lodes also are" Indicator" veins. B is a later formed vein that leaves no " depositions" behind. ooe are fragments of the" most ancient'' lode wreckage. Db are the auriferous lodes and correspond with those lodes, also whose auriferous characters are not result of secondary impregnations.

The Directional Drill Monitor (DDM) is an advanced instrument for real time in hole surveying. It was developed by Du Pont (Australia) to suit Australian gassy coal mining conditions. The instrument consists of three units: i. Down hole transmitter ii. Acoustic transducer iii. Data receiver processor unit (i.e. up hole unit). This paper describes the function of each unit in detail and highlights the importance of the DDM in long hole drilling efficiency. Surveying is carried out independent of hole depth. Each survey takes 2-3 minutes to complete, the frequency of surveying to control borehole trajectory is determined by the accuracy required for a particular hole.

Jan 1, 1992