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By Yamamoto Y, Ohyama H

In case of NATM, mechanical cutting is desirable in view of the original purpose of not spoiling natural ground. As typical tunnelling machines, there are two (2) kinds available: one is "Full Face Excavator" known as TBM (tunnel boring machine), and the other is "Roadheader" known as Part Face Excavator. By the use of the former, accurate profile cut is made possible, but there is a limit in the shape of a cutting section. By the use of the latter, cutting of various sections is made possible, but in order to cut a section economically and accurately, operators are required to have a high level of skill. In this text, we introduce Automatic Controlled Profile Cutting System (hereafter "ACPC" System) developed as a roadheader.

Jan 1, 1987

That gold will dissolve in sodium hyposlphite solutions is known from the lixiviation of silver and gold ores.The gold will dissolve only in small quantities. According to Stetefeldt, if gold leaf is treated for a time with sodium hyposlllphite solutions of varying strengths solution takes place in every instance, the deviation in quantity being very slight.In order to form hyposulphite double-salts, the gold must become oxidised, the oxygen being derived from the air absorbed by the solution. Consequently, it is the quantity of free oxygen in the solution by, which the reaction is determined, as for one equivalent of gold dissolved one equivalent of caustic soda is set free.

Jan 1, 1901

In order to maintain an accurate survey underground, it is first necessary to connect all shafts used for the transferring of the survey to the levels below by a precise surface survey.This has been achieved at Mount Isa by a careful triangulation survey with stations adjacent to those shafts most suitably located for transferring the survey below.The precedure used is described herein.The Weisbach triangle commonly used is obtained by reading to swingirig wires, the theodolite being placed in line with them as nearly as is possible. The surveyor at the surface places the wires in the shaft as far apart as the size of the shaft will permit, with sufficient space between the wires and walls to ensure their swinging freely. The far wire is fixed in position, while the near one is movable by means of fine adjusting screws to facilitate its being brought into line with the fixed wire and the theodolite. When this is done the surveyor at the lower level is advised by pre-arranged signals and the survey can then commence.The surface portion of the survey is simple; all that is necessary being to read the angle from the backsight to the wires, measure their distance from the theodolite, and keep a check on them throughout the survey to make sure that no movement takes place.The lower portion of the survey is more difficult, the surveyor first qf all having to place his theodolite as nearly as possible in line with the wires.

Jan 1, 1953

India is on fast economic growth. Even in the turbulent years of global crisis, it could achieve a growth of over eight per cent. In recent past, Indian Government has been contemplating a faster growth in all the sectors of economy so as to make the nation an economic power in the world.Steel is a versatile material. It has its role in most of the major industrial activities, such as infrastructure, automobiles, urbanisation, consumer durables and other. In other words, steel is a part and parcel of industrial expansion, urban and rural development. It is rightly admitted that steel acts as pillar of any development model. Volume of steel consumption is the barometer which measures economic progress and/or industrial status of any country.India and China are the two countries in Asia which have the significant impact on the global steel industry. Of course, China is much ahead of India in consumption level of steel.

Dec 6, 2010

An empirical method of estimating dense rock (D.R.E.) equivalent volumes erupted as airfall tephra, described in a companion paper in this volume, is elaborated, and its accuracy discussed. Estimates obtained from a single eruption can be classified as to whether they show positive, negative, or constant relative dispersion. For positively dispersed tephras (estimated volumes increasing with distance), this procedure improves the accuracy of the method. The technique is applied to selected andesitic tephras erupted from Egmont Volcano, New Zealand, during the last 28 000 years, which are found to range in volume from about 1.5 x 107 m3 up to about 2.4 x 108 m3 D.R.E. With a factor of about 16 between the smallest and largest volumes, this contrasts sharply with the rhyolite volcanoes in New Zealand, where the difference factor is usually of the order of 100. The largest tephra eruptions at Egmont are small compared to the largest debris avalanches, which have exceeded 1010 m3 (10 km3) in volume.The magnitude versus frequency relationship, calculated using a maximum likelihood method, establishes the limits of eruption magnitude at Mt Egmont as 107 to 109 m3 D.R.E. For some volcanoes, the magnitude-frequency relationship changes with time, owing to clustering of eruptions, separated by long dormant intervals. Ngauruhoe Volcano, New Zealand, is an example. Within eruptive episodes, the mean interval between eruptions of >_ 105 m3 is about 0.9 ¦ 0.65 years. The mean interval between eruptive episodes in which >_ 106 m3 is erupted, including episodes in which this volume is erupted gradually, is about 25.8 ¦ 6.6 years, and the mean dormant interval between all episodes is about 5.2 ¦ 3.0 years. At present Ngauruhoe is in an unusually prolonged dormant period, 50% longer than any in the historical record, since 1839.

Jan 1, 1990

The development of computers is examined in the context of the mining industry. The risk element is given as a reason for the slow introduction of the computer into mining. Dealing with mining's uncertainty is seen as a major role for computers. The use of computers is traced from early accounting applications to current involvement with all aspects of mining. The problems associated with increasing use of computers and their impact on management is discussed in depth. Disenchantment of management is thought to arise from unfulfilled expectations. Contributory causes are given as overselling of computers, reaction against change, speed and growth of computer technology. The solution is seen to lie in a more dominant role for user management in the development of computer systems and greater emphasis on education. The computer of the future will then become integral to the mining process as an extension of management's planning and control function.

Jan 1, 1974

By Wagland D. G, Guo H

The Mt Whaleback orebody is in a complex geological regime. A good understanding of geological structure is essential during the design and implementation stages. The amount of information on the rock-mass condition available at the design stage is considerably limited. It is essential to validate the rock-mass properties used in the design during implementation. It is important to achieve integrity of the final pit wall during development and to maintain the integrity until the end of its designed life for safe and economical extraction of ore. The original geological model is updated by way of on-going detailed geological face mapping. Original design is reassessed and is modified based on any significant variations to the previously evaluated geotechnical conditions. Information gathered during design implementation provide tools for effective management of the pit walls. Controlled blasting techniques are employed in the final limits blasting. Presplit blasting is used in most limits blasts. Presplit helps to maintain the integrity of the wall by venting excessive gases from the limits blast. This helps to reduce bedding dilation by gas penetration. Also, it helps to define the design batter for the operators for final batter trimming. Pyritic shale needs special attention during blasting due to its reacting nature. Cablebolting is applied in selective areas to secure small-scale potential instabilities. During the development phase, pit wall monitoring instruments are installed. These instruments are used to monitor the performance of the wall during and after excavation of the slope.

Jan 1, 1995

By Jancar T, de Guzman M M, Matthews B, Tu J. Y

The use of computational simulation to predict the performance of existing equipment or for the design of improved mineral processing equipment will be referred to as Computational Mineral Processing (CMP) in this paper. The emphasis will be on solving the governing equations for liquid solid flows in complex geometric domains to obtain, typically, the three-dimensional distributions of velocity and pressure for the liquid phase and the velocity and concentration for the solid phase. The underlying technology, computational fluid dynamics (CFD), is very well-developed in other industries (aircraft, car and chemical) and forms a vital part of product design and analysis. The subsequent design of improved mineral processing equipment may also involve finite element structural analysis (FESA). Computational fluid dynamics (CFD) and finite element structural analysis (FESA) are part of the generic discipline of Computational Engineering and Science (CES). Ciment and Scherlis (1993) define CES as `The systematic application of computing systems and computational solution techniques to mathematical models formulated to describe and simulate phenomena of scientific and engineering interest'. Increasing computer power (Kaufmann and Smarr, 1993), is a dominant factor determining the rapid growth of industrial utilisation of CES. This increase is happening at both the supercomputer and the workstation level. Indeed, today's typical workstation, a Hewlett-Packard 735, is as powerful as a CDC 7600, the leading supercomputer in 1970. Future computer architectures are expected to become increasingly parallel (Gartner Group, 1990) allowing a sustained performance of a teraflop (a million megaflops) to be achieved well before the Sydney Olympics in the year 2000. It is recognised that the modem development of most disciplines in the physical sciences rests on the three complementary strategies of experimentation, analysis and computational simulation. As the 21st century is approached the volume of computational simulation, both fundamental and applied, is growing dramatically and the role of experimentation is diminishing. In the area of equipment design, CES provides the following advantages over experimental testing and measurement: 1. lead time in design and development is significantly reduced; 2. CES can simulate conditions not reproducible in experimental tests; 3. CES provides detailed and comprehensive information; and 4. CES is more cost-effective and time-efficient. The ultimate benefit for industry is greater productivity and hence greater profitability. The broader issues in relation to CFD are discussed by Fletcher (1993b). In the five- to ten-year time frame, growth in computer power will make it practical to combine CFD and FESA with optimisation procedures to produce a design process that is almost fully computerised. It is expected that fully automatic

Jan 1, 1995

The treatment of mixed lead carbonate and lead sulphide concentrates at Mount Isa presents a problem which is unique ,in the lead smelting world; a problem whose solution is far from simple, and is not yet complete. Two years of study under plant conditions have definitely proved, however, that a most satisfactory sinter can be made in a single-pass roast.The object of this paper is to present a brief record of the development of the single-pass roast and a resume of current practice in the smelting plant. The sintering operation is discussed in greater detail, as it is upon this phase of the work that every item in the smelter operating programme depends.The smelter, to-day, presents a very much simplified layout, equipped for economical, straightforward operation, requiring, however, very careful and constant supervision, due to the extreme delicacy of the sintering operation and to the rapid and wide variati9n in the nature of the concentrates which are to be handled.

Jan 1, 1933

This paper reviews the issues of mining machinery automation with special emphasis on underground applications. Automation is desirable because it offers the following advantages: ò increased safety by reducing human exposure to hazards of underground mining; ò higher productivity; and ò reduced wear of equipment. In spite of these advantages and in spite of numerous attempts over the past several decades, mining automation has been a difficult proposition, partly because no two mining operations are exactly alike and these operations are carried out in an unpredictable environment. This is the main difference between automation in factories and in mines and that is why mining automation has been lagging so far behind factory automation. Automation is possible only when the machine 'knows' its workspace. In a factory, this workspace can be 'described' to the machine because it is sufficiently controlled. In a mine, the environment undergoes continuous change and the only way the machine can 'know' its workspace is through real-time sensing.

Jan 1, 1995

The intention of this paper is to examine the practical and technical aspects associated with the measurement of blasting related phenomena. The emphasis is directed towards the acquisition of quantitative data rather than its theoretical interpretation. The application of advanced technologies will require that many more people involved with blasting become familiar with this topic. Against the many other disciplines where measurement may be beneficial, blasting is peculiar on several counts. 1) It must almost always be carried out in the field, and very often in a production environment. 2) Much consideration must be given for the safety of personnel and equipment. 3) The process is dynamic and seldom repeatable. Because the blast process is so dynamic there is little opportunity for direct examination. For this reason measurements are almost universally made using electronic techniques. In this way the event can be captured faithfully as it occurs and later examined in detail, after the fact. It is obvious that some familiarity with these electronic techniques is a necessary ingredient for successful blast monitoring.

Jan 1, 1990

Winzes are usually sunk 9 ft. 6 in. long by 6 ft. 0 in. wide and are divided into two compartments, 4 ft. 0 in. by 5 ft. 0 in. inside the timbers. The general practice is to sink the winze to a depth of from 9 to 12 ft., put in bearers and three or four rings of timber, and then erect a sinking headframe before continuing sinking operations.GENERALThe main feature governing the design of the headframe was that all parts could be transported on timber trolleys in No. 2 Shaft. Except for some minor details the structural members consist of steam pipe. Joints are sections of steam pipe welded to one member and into which the other member fits and is held in place by a 1-in. bolt. The headframe consists essentially of two bedpieces to carry the winch and to form a seat for the four legs. The legs support the sheave bearers, the tipping door and the brace.Except during tipping operations the door is in a nearly vertical position. For tipping it is lowered to an inclined position and a hook suspended from one of the bracing members of the headframe is attached to a "D" welded to the bottom of the kibble. This causes the kibble to tip when it is lowered on to the tipping door. The capacity of the kibble is 4 cubic feet.THE HEADFRAMEThe dimensions of the headframe are:Height to top of sheave .. .. 14 ft. 10 in.Distance centre to centre of legs 4 ft. 4 in.Length of bedpieces .. .. .. .. 8 ft. 9 in.The weight is approximately 2,000 lb., the tipping door and bedpieces being the heaviest members. They weigh 240 lb. and 170 lb. respectively.One compartment of the winze is decked over, and the bedpieces, which are 8 ft. 9 in. lengths of 6 in. pipe with three short lengths of plate welded to the underside, are placed over the sinking compartment, either transversely or parallel to the winze. Three 3 inch pipes act as spreaders between them.Welded to the top of each bedpiece is a 6-in. by iHn. plate 3 ft. 0 in. long with four 4-in. by 1.5-in. slots cut longitudinally at 10 in. centres. Two 10 in. by 4-in. timbers are bolted to these plates, the distance between them being adjusted to suit the holes in the winch bedplate, which is bolted to the 10-in. by 4-in. timbers.Two short lengths of 3 in. pipe are welded to each bedpiece at 4 ft. 4 in. centres. These form the seats for the legs of the headframe, which are...

Jan 1, 1941

By P Lilly

Blasting is the primary comminution process in most mining operations. This process involves the highly complex and dynamic interaction between two main components. The first is the detonating explosive and the second is the rock mass into which the explosive is loaded. The mechanical properties of the rock material (such as dynamic strength, tensile strength, dynamic modulus and fracture toughness) are important considerations in understanding the blasting process. However, it is the characteristics of the geological defects (joints, foliation planes, bedding planes) within the rock mass that ultimately determine how effectively a blast performs in terms of fragmentation, all else being equal. The defect characteristics include, but are not limited to, their orientation, spacing, and mechanical properties. During the blasting process, some of the geotechnical characteristics of the rock mass are substantially changed. From the blasting outcome point of view, the most notable and important is the change in fragment size distribution that the rock mass undergoes. The pre-blast in situ defect-bounded block size distribution is transformed into the post-blast muckpile fragment size distribution. Consequently, it is fundamental to our understanding of and ability to predict the blasting process that both the blastability of a rock mass and its transformation into the fragment size distribution can be appropriately quantified.

Jan 1, 2001

The theory of declining optimimum cut-off grades is more than 25 years old, but for a number of reasons it is still not widely used in industry. A lack of faith in the veracity of estimated grades is not in itself a reason to abandon any attempt to optimise cut-off grades. The use of declining cut-off grades has been thought to cause high-grading, but in fact this is only true if an artificially high discount rate is used in the calculations. Perfect application of an optimum cut-off grade should ensure that only ore generating more than a minimum net return is mined, and that as much as possible of the ore capable of generating that return is mined. Therefore differing mining costs in different parts of some underground mines necessitate local modifications to cut-off grade. Optimisation of cut-off grade is of necessity an iterative process. Integration of that process into a feasibility study need not be excessively time-consuming. A number of approximations can be made to speed the optimisation (any attempt to achieve a high level of accuracy is probably doomed to failure by a lack of precise cost and price projections). A procedure is outlined for optimising cut-off grade during planning of a typical underground mine.

Jan 1, 1991

By Turco E, Pelizza S, Castellani F, Stanganelli V

Excavation are in progress for the building of tunnels of the waterworks in West Campania (Naples). The works afferent to part II envisage tunnelling through a miocenic clay formation over consolidated by two tunnels whose sections are respectively 50 and 10m2. Tunnel blasting is carried out by mechanical means. An excavator is used in the big tunnel, whereas in the small tunnel a roadheader machine is used for a short tract and a mechanized shield is used over a long stretch. The tunnel feature complex problems regarding stability. This is particularly so for the big tunnel whose face appears unstable. For this reason the clay on the face is sistematically bolted by means of 3-metre and 12-metre bolts. This prevent the use of a TBM for tunnel Excavation.

Jan 1, 1987

This paper summarises some observations regarding the way SAG and AG mills work based on the last ten years of pilot plant operation, grinding circuit design and operational reviews for various projects in Australia and overseas. The main purpose is to promote discussion on key factors influencing breakage in a SAG mill. The focus of the paper is on two questions: How do mill lifters and liners really work and have an effect on grinding? How does the mill charge composition impact on grinding performance? The focus of the paper is on observations of mill behaviour in both pilot plant trials and plant operation, particularly on Cadia ore. DEM, by others, and JKSimMet modelling of SAG mill performance have greatly assisted in forming the ideas expressed in the paper and both are valuable tools in developing our understanding of the comminution process. Put in the æextremeÆ form the major observations and conclusions expressed in this paper are that: the main purpose of mill lifters is to reduce mill liner wear and not to promote rock breakage; the often promoted theory that balls impacting the ætoe of the chargeÆ is a dominant form of breakage is incorrect; and fines production in a SAG mill is primarily a function of the rock load mass, with a secondary dependence on ball load for any given circuit configuration.

Jan 1, 2007

By Kandemir H, Stafford G

The Croydon Gold Mine is located in northwest Queensland and is a joint venture between Central Coast Exploration N.L. and Pancontinental Mining Ltd. The mining operation commenced in 1987 and consists of satellite open pit mines feeding a central Carbon-In-Pulp gold Treatment Plant. The gold mineralisation is hosted by quartz veins within the Croydon Volcanic Group and the Esmeralda Granite, a cogenetic igneous suite of Middle Proterozoic age. The mineralisation comprises gold and silver with associated basemetals. The gold and silver electrum occurs as extremely fine free grains. The gold distribution is heterogenous occuring across the full vein width, or restricted to the footwall or hangingwall. The average mineral resource grade is 3.5 g/t. The deposits are all hard rock and mining is carried out by drill and blast technique. All mining activity is carried out by a mining contractor. Mining is by a selective mining method which entails the drilling, blasting and extraction of the hangingwall waste prior to orebody extraction.

Jan 1, 1989

By Hyde L. J

Blasting is one of the available technologies to be employed in underground excavation systems. In many instances it can be the only technology which is suitable. The recent moves towards more mechanised working systems is resulting in a reduced awareness of new blasting practices and technologies on the part of many excavation engineers. Recent developments in blasting systems can be utilised to significantly improve operating efficiency, reduce total cycle times, better comply with regional environmental constraints and reduce the total cost of underground excavation. Blasting is and will remain, a very adaptable and exciting alternative which is far from boring.

Jan 1, 1987

By B OÆNeil

The Trent-Severn Waterway is a 386 km long navigation route through central Ontario between Lake Ontario and Georgian Bay, and is operated by the Parks Canada Agency. Its primary focus is to pass recreational boats through a system of 44 locks. The Big Chute Marine Railway (BCMR) is one site in the system that provides transportation for boats. The BCMR carriage is used to transport boats and their passengers on the inclined railway a distance of 230 m over a natural barrier from one body of water to another, with an elevation difference of 18 m. The unique feature of the haulage system used in this application is the variable angle of the incline from about 20 per cent rise changing to horizontal and followed by 20 per cent decline. In such conditions, unlike as in standard incline haulage, special configuration of hoists and drives is required. On the uphill part of the track, there is a need to have a motoring mode, on the downhill part a regenerating mode and on the horizontal part a combination of motoring and regeneration is required. The original system was built in 1978 and employed four 100 hp dc drive mine hoists to haul the 100 tonne conveyance loaded with 90 tonnes of boats. Due to failures and operational problems with the original system, in 1999 Parks Canada awarded a turnkey contract to ABB for a new, modern system of four single drum hoists. The new system was put into operation in 2000, only six months after receiving the order. The hoists are controlled by digital drives and a digital control system. Due to dramatic changes in the load conditions for individual hoists involved, the new system features many interesting solutions like changing drive modes from speed to torque control and a multiple, regulated braking system. It is a unique hoisting system, which could be also used in mining applications.

Jan 1, 2005

Strategic planning in mining is an important value accretive process. One of the most important aspects during the planning phase is determining the correct mine and plant design. The traditional mine site design (mine, plant, stockpiles, dumps) develops a fixed system for one set of conditions or expected values. A robust design is a fixed system that is designed to deal with a large range of conditions without changing the system design. A flexible design changes the system dynamically in response to changes in uncertainties. It is hypothesised that a robust design generates less value than a flexible design as it fails to realise the value of actively managing the operation. One of the most critical aspects in creating strategic value from a project is embedded in the design of the system. A flexible design has components that allow the design of the system to change over time. An operational plan is proposed as a hybrid of a robust and flexible design. This paper seeks to compare these different design methodologies. An analysis of the same case study is undertaken to compare these approaches, showing an a traditional net present value (NPV) of $1678 M, robust design NPV of $1787 M and an operational plan NPV of $1867 M - an increase of $170 M.

Dec 6, 2010