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By G W. Croft, L E. Krause

The current copper ore handling systems in use at Xstrata CopperÆs Mount Isa Copper Operations are up to 33 years old and have hoisted over 160 Mt at a rate of around 6 Mtpa. The mineÆs production profile is increasing in line with the optimum life of mine plan to over 6.6 Mtpa, which requires a system utilisation and reliability above that previously achieved. Copper ore is hoisted up the U62 shaft, which forms the central part of the U62 ore handling system. In theory this system can cope with the duty planned if the bottleneck is only the U62 winder. To achieve the planned production rate will require increased focus on reliability of each component in the ore handling system so that ore is available at the shaft for hoisting whenever the shaft is available, and the shaft is available for the maximum practical time. Increased availability will be achieved through the outcomes of the study of each component in the U62 system, and the internal ore handling systems that deliver ore from as far as 2 km laterally and 700 m vertically from the U62 shaft. The true capacity of each component is being determined and current performance is being measured with the aim of improving performance through root cause analysis and engineering out the causes of delays. The program began in March 2004 and this paper describes the progress achieved as of April 2005.

Jan 1, 2005

The Australian mining industry is at an interesting stage in its development. Of the large number of mining companies in Australia, some are still solely domestic in their focus. others have made their first tentative forays offshore, and others are global players of significance in the world industry. It is not long ago that the entire industry was almost exclusively domestic in its focus. Very few companies before the early 1980s had ventured offshore, and those that did so were considered quite risque. The initial moves were made mainly by large companies who could afford to lose the funds expended in getting started in a range of offshore locations.

Jan 1, 1995

By Kurihara M

In Japan, shield tunneling method is generally used to drive a tunnel in sand layers around the urban area. In this report, appli- cability of NATM (New Austrian Tunnelling Method), which uses rock bolts and shotcrete as support, to water-bearing sand layers is studied aiming at establishing more economical tunnel driving technique. After the geological exploration, the conditions (i.e. pitch of steel supports, water content, cohesion, and fine content of ground,)necessary to ensure the face stability were investigated by using centrifuge loading tests. Concerning measures to manage ground water, an air permiability test was carried out to investigate the effect of the compressed air to cut-off inflow, and pumping test to study the applicability of dewatering. Furthermore, two dimensional elastic FEM analysis consider- ing progress of the excavation face was perform- ed to analyze stresses in the support system and deformation of the ground, and to investi- gate safety of the support and the ground. From these prior investigations, possibility of the applicability of NATM to the present pro- ject was predicted. Finally, based on these results, a real scale field application test was put into practice to confirm the prediction, and to pursue construction efficiency and phenomena which could not have been predicted Beforehand.

Jan 1, 1987

By B Veera Reddy

For thick seam extraction, the Blasting Gallery (BG) method is ideal for obtaining the maximum percentage of extraction at fast rates. The continued use of this mining method is threatened by strata control and spontaneous heating problems. The strata control problems are managed, to some extent, by supporting the roof with cable bolting and roof bolts of 2.5 m length and with regular induced blasting. However, a number of BG panels were sealed off prematurely due to spontaneous heating problems, losing 1.12 million tonne of coal. The use of compressed CO2 for controlling mine fires is not uncommon in the coal mining industry, but its use is something new for controlling active spontaneous heating in a BG working panel goaf. This method was attempted at the BG I/8 panel of the Godavarikhani (GDK) 8 Incline, Singareni Collieries Company Limited (SCCL). The spontaneous heating was effectively controlled and the remaining coal in the panel was completely extracted by continuous flushing of carbon dioxide (CO2) into the goaf for 40 days. One thousand and twenty four CO2 cylinders, each of 45 kg at 80 bar pressure were flushed into the goaf at the rate of 25 to 30 cylinders (350 m3 of CO2) per day. A quantity of 35 510 tonne of coal was extracted during the period from 30 July 2002 to 7 September 2002. The main objective of this paper is to present the complete process of controlling the spontaneous heating by CO2 flushing and to report on the study of the behaviour of gases and their analysis. The unique experience of controlling the active spontaneous heating in the working Blasting Gallery I/8 panel goaf at GDK 8 Incline with CO2 flushing (till the completion of the panel) will go a long way in establishing a working procedure for handling fire/spontaneous heating problems in BG panels.

Jan 1, 2005

Ridgeway Gold Mine (Ridgeway) has a clear mission to maximise its cash flows in order to deliver shareholder value and is developing strategies to achieve this. Business process management using leading measures is core to this approach. Leading measures indicate potential outcomes ahead of time, allowing time to adapt and improve. Ridgeway is making strategy a central organisational agenda, creating a focus to æput first things firstÆ by controlling æleadingÆ activities and mobilising employees to act. Feedback using specific, leading measures gives employees the opportunity to proactively adapt their behaviour in order to deliver internal business outcomes that generate cash flows and shareholder value. This paper will outline RidgewayÆs business approach to track and control processes from resource to revenue, with a focus on delivering cash flows and shareholder value. Ridgeway is implementing a Balanced Scorecard approach (Kaplan and Norton, 1996). A total business focus is taken and leading measures are identified. Specific measures are used to score our success from the perspectives of learning and growth, internal business processes, customer and stakeholders, and finance. These measures and improvement plans are targeted at strategies to maintain our ælicence to operateÆ with our community stakeholders, produce accurate plans and forecasts, improve our operational effectiveness and grow our business.

Jan 1, 2002

The present geology of the northwest quadrant of the Circum-Pacific is the product of the interact-ions between plates or paleo-plates which have oc-curred since the earliest part of the earth's hist-ory. Almost every possible geologic structures are observable there; stable continents, collision belts, and subduction arcs as well as extensional basins. This suggests that almost all the possible tectonic processes occurred through geologic time and the present overall structure of the Quadrant is no more than a time section of the long lasting tectonic history which the region experienced.

Jan 1, 1990

Zinc-bearing materials containing chlorides and fluorides of alkali metals, such as electric arc furnace dusts, Waelz oxides, galvanising ashes, brass foundry and converter fumes are marginally attractive, both technically and economically, for processing by the Imperial Smelting Process or in a conventional zinc sulphate electrolytic plant. The EZINEX« Process allows the recovery of high purity zinc in cathode form from these materials, together with regeneration of the leach liquor. The process is based on a new electrochemical system which depolarises the anode reaction with reduction of the cell voltage, compared with the traditional sulphate electrolysis method. The electrolyte, based on a chloroammino complex, permits the recovery of other valuable metals present in the zinc bearing materials such as lead, copper and silver. These are recovered as a metallic cement, consequently improving the economics of the process.

Jan 1, 1993

Magmatism and mineralization are features of the New England Orogen in late Palaeozoic- Mesozoic time. Voluminous silicic and mafic magmatism, both orogenic and post-orogenic in association, was accompanied by abundant mineralization in the earlier phases. Later activity passed transitionally into less vol- uminous felsic to mafic intraplate basaltic volcanism, with possible migratory hot spot activity through the flanking Oxley and Sydney Basins. Only minor mineralization took place at this stage. A new inerpretation links these magmatic and mineralizing events to a major thermal cycle. A New England hot spot(?) complex evolved in latest Carboniferous/early Permian time. Its activity was partly obscured by orogenic magmatism as Australia moved slowly over magma sources in the deep lithosphere. In Triassic time Australia's movement changed direction and faster drift over the waning hot spot complex produced multiple migratory intraplateòactivity. The volume of magma and hence abundance of ancillary mineralization was related to age of the hot spot, speed of the continental movement over thermal sources and extent of accompanying orogenic activity. The New Eng- land Orogen hot spot(?) possibly existed for 165 Ma, with mineralization changing over this Period.

Jan 1, 1987

By Dickerson A. W

The most important mining problem facing many of the established surface coal mines in the Bowen Basin area of Queensland is the rising cost of overburden stripping associated with increasing depths to coal. The Dragline-Hopper-Truck Project is one of a number of responses to this problem, and involves the design and construction of an experimental hopper followed by field evaluation of a dragline-hopper-truck mining system.Such systems, if proven feasible, could be used for a range of applications, eg prestripping, extension of depths for single pass dragline operations and solution of geotechnical problems.

Jan 1, 1992

By Neto J. A N

Usually there are organisational interfaces between each stage - companies or departments. Each organisation will have different ideas about "optimum" operation. These ideas will be driven by how the performance of each is measured ' and rewarded. Therefore it is important to set up data acquisition processes with respect to maximisation of overall profitability and resource utilisation. In the simplest case - if the miners are paid on tonnes and the concentrator has severe grade penalties on concentrates, then there is the possibility of a conflict of interest over metal Balance.

Jan 1, 1991

With the recent wider introduction of friction hoists of the Koepe type. for winding from depths of more than 3000 feet it has been found that failure by fatigue is the most common form of rope deterioration. Large numbers of wire breaks occur near the centre of the rope cross-section and it is difficult to detect these with certainty using the preferred d.c. magnetic test. For best results with conventional search coils their dimen- sions should be related to the typical wire break field pattern surrounding the longitudionally magnetised rope. The field of a broken wire was experimentally determined, using a Polish type MD6 Defectograph wire rope testing magnet and a short prepared length of rope with a movable simulated broken wire. The external field distortion perpendicular to the rope was measured by means of a gaussmeter and Hall probe. The advantages of this method are that terrestial magnetism and inherent rope "noise" have no effect on the results.

Jan 1, 1971

By Ellicott C, Webb N

In November 1996 the NSW Minister for Mineral Resources, Hon Bob Martin MP, commissioned ACiL Economics and Policy Pty Ltd to conduct a wide ranging review of safety within the New South Wales mining industry.The review was a response to a disturbing number of fatalities which had occurred in the industry during the Minister's term of office together with a number of alarming near misses where serious failures in mining systems had occurred. Shortly after the review was commissioned, four mine workers died at Gretley Colliery near Newcastle. An inquiry is currently being conducted into the incident.

Jan 1, 1998

By Grady PO

The longwall panels at Clarence Colliery have experienced intermittent sudden weightings on the face that have caused some production delays. These weightings have typically been more severe on the wider faces. A program of surface subsidence and extensometer monitoring was undertaken above Longwalls 4 and 5 to investigate the behaviour of the overburden strata during longwall extraction on two faces of different widths.The monitoring indicated that a dome shaped zone of large downward movement extends up into the overburden strata to a height equal to about the panel width.

Jan 1, 1998

By Mckenzie CK

Delay scatter, although widely recognised, has rarely been studied with the aim of critically reviewing blast designs. With current trends towards increased deck charging, and the effect on the number of separate delays in blast designs, delay scatter is shown to have a rather profound influence on the control of initiation sequence and the ability to successfully con- duct pre-splitting and smooth blasting. Determination of realistic delay scatter distributions is the first step towards application to blast design. Delay scatter must be evaluated in terms of deviation from the nominal time, not in terms of deviation from the batch mean, since the latter is not usually known without specific testing, requiring accurate timing instrumentation. Computer programs using Monte Carlo simulation can then be developed to investigate the probabilities of out-of-sequence initi- ation or near-simultaneous initiation within any specified interval. The procedures have been applied to both production and development blast designs in Australia and Chile to improve initiation sequence control and to rationalise and simplify blast designs.

Jan 1, 1988

By B Wiggins, M Russell

Off-gas handling systems are a critical component of modern metallurgical furnaces and typically represent as much as 50 per cent of the total installed smelter capital cost. Inadequate off-gas system performance, due to insufficient exhaust flow or excess maintenance downtime, can present a serious process bottleneck and limit smelter production rate. Therefore, it is essential that the relevant performance issues are fully understood and considered in the design of these systems, particularly when combustibles produced within the furnace must be combusted or handled in the off-gas system. This paper examines the requirements, design issues, and conceptual design process for state-of-the-art postcombustion off-gas systems. The relevant design considerations of safety, environment, energy consumption, and maintenance are presented, and the relative importance of these key issues are compared and discussed. The benefits of using computational fluid dynamic (CFD) modeling in the design process at the conceptual design stage are also demonstrated. Finally, the design basis and performance of a recent Hatch-engineered system currently in operation is evaluated.

Jan 1, 2002

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

Adsorption isotherms, zeta potential and coagulation techniques have been used to exa- mine the mechanism of metal activation on SiO2 and ZnS surfaces. The importance of surface nucleation or precipitation of metal hydroxide coatings is'established and identified-by characteristic charge reversal patterns. The significance of surface coatings in sulphide and non-sulphide flotation is discussed.

Jan 1, 1973

By Kaji S

The Tsugaru Tunnel, located on the Honshu island approach to the Seikan Tunnel, is 5,880 m long and has a "Shinkansen" cross section of 90 m2 area. The geological formation through which the tunnel passes consists of very soft rock most of which is unsolidified sandstone belonging to the Neogen. The permeability coefficient is in the range of 10-2 to 10-4 cm/s and being water bearing with a high ground water level, the ground is unstable and subject to soil outflow phenomenon. Kajima Corporation, undertaking the Futamata Construction Section (1,420 m long), excavated the tunnel by the upper half heading method with side pilots employing the following countermeasures to cope with these severe conditions.

Jan 1, 1987

Gold Fields Ghana Ltd (GF Ghana) currently operates an underground mine at Tarkwa, in south--west Ghana. The mine was operated by Tarkwa Goldfields Limited, a wholly owned subsidiary of the State Gold Mining Corporation of Ghana (SGMC). The mine was making operating losses and in a poor state of repair. Tarkwa Goldfields retrenched all the staff and GF Ghana assumed management responsibility for its own account on I July 1993.

Jan 1, 1997

By Weyer J

Many existing computer planning programs for the mining industry focus either on big mining enterprises with a high production rate or on smaller operations for high value minerals. Big mining enterprises, like the hardcoal company `Ruhrkohle AG' in Germany have their own R&D departments which develop powerful computer programs for planning purposes, partly in co-operation with mining universities. However, there is a remarkable number of small- scale mining operations which are either not able to buy expensive hard- and software or don't have the skills for the operation of extensive software programs. Partly there is also a trend in using rule of thumb calculations rather than computer programs which need a lot of - partly unavailable - data. For this reason a computer program was developed which does not need expensive hardware and software and which can help the planning engineer in the selection of a limited number of possibilities. Until this time the planning engineer established two or three different cases and calculated the results with a pocket calculator. This could last some hours or even some days. Now he or she can use the computer program with a normal PC to compare the cases. All activities are menu-driven. The basis for all, calculations are fixed and variable costs as well as average performance for special activities. The paper gives an example for a possible planning situation in fluorspar mining (originally this program was developed for the fluorspar enterprise Lengenfeld in Germany). It shows the initial situation, the main structure of the program, the input logic and the results. Benefits, limits and possible extensions of the program are discussed.

Jan 1, 1995