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By Theophili CN, Kapenis AP

Seismic tomographic imaging has been applied to determine the blast induced damage zones in bauxite pillars in underground mining. At the retreating stage, when pillar dimensions are reduced from 8 x 8 m to approximately 5 x 5 m, the' seismic tomographies reveal, through measurements of the P-wave velocities which is a measure of the degree of fracturation of the pillar rock mass, the presence of three zones within each pillar. In the external zone, where velocities recorded are below 750 m/s. extensive pillar damage occurs which is attributed to both the growth and coalescence of pre-existing cracks and even the creation of new cracks in the rock mass. This effect is in agreement with literature, when considering the peak particle velocity as a criterion for rock failure in tunnels. In the intermediate zone, where velocities range between 7S0-1000 m/s, damage to a much lesser extent occurs which is due mostly to growth of pre-existing cracks and widening of their apertures. The inner zone, where velocities exceed 1000 m/s, is considered to be unaffected by blasting. Simple remedial measures of low cost, which are based on blasting mechanics are proposed to minimise the blast induced damage zone and consequently the transition zone.

Jan 1, 1995

By Dinuzzo P, Wychie J, Desoe C

The Selwyn Gold-Copper Mine is located 150 km southeast of Mount Isa within Proterozoic units of the Mount Isa inlier (Figure 1). Mineralization in the mine area is associated with strongly sheared ironstones and iron rich schists at the base of the mid- Proterozoic Staveley Formation. The ironstone horizons outcrop as a series of dominant ridges over a 10 km strike. Economic gold-copper mineralization has been defined in 4 separate zones within a 3.5 km length of the outcropping ridges. A current combined geological resource for the deposits is 5.3 million tonnes of 5.0 g/t Au and 2.02 Cu. Weathering of the deposits has resulted in a pronounced vertical zonation of mineralogy, especially copper, within the ore zones. This has produced 3 separate ore types which require different treatment techniques. The categorization is based on copper content and zones are termed leached (surface), oxide and sulfide. Ore removed from the pits will be mainly leached and oxidized with minor sulfide near the pits final depths, while the underground ore will be from the sulfide zone with minor oxide in some areas.

Jan 1, 1989

By Maloszewski J, Kidybinski A, Sawka B

A forecast of mining conditions in Upper Silesia collieries for the beginning of the 21st century has special focus on average depth of mining, energy of seismic tremors induced by mining and energy of dynamic loads on roadway supports. A method of dynamic loads calculation is based on volume of failed rock surrounding an opening and the seismic energy of tremors anticipated. New types of yielding steel arch supports have been designed to resist massive static and dynamic loads and a system of supports has been tested both on 1 : 10 scale models and in natural size. The support sections used are 29, 36 and 44 kg/m.

Jan 1, 1988

By Aspinall T. O, Just G. D

Computer software systems have been developed to assist in a wide range of specific mine planning and scheduling applications. In selecting appropriate systems for any mining operation it is apparent that certain features have particular advantages for each mine site. The ideal solution to this problem is to select a range of systems which best relate to sections of each mining operation. This approach raises potential data linking difficulties where output from one system is incompatible with input requirements for other systems. A study at the University of Queensland investigated the problems related to the integration of a number of mine planning and scheduling software systems. The project used data from large scale coal strip mining operations in Central Queensland. Two major computer packages used extensively in the study were the SURPAC mine planning and XPAC mine scheduling systems. Dragline and truck and shovel operations were analysed in the project. Results of the work have been directly applied at the mine site to assist current strip design by effectively automating the design procedure. This enabled sensitivity studies to determine the effects of changing dragline working levels and varying pit dimensions. Coal blending studies and procedures to optimise operations have been investigated using linear programming within a spreadsheet software application. Output from the SURPAC and XPAC programs was directly linked to the linear program for this analysis. The simulation program GPSS/PC was also used in a similar manner to assess optimisation parameters.

Jan 1, 1992

By Doyle P, Mulroney D

The Cassidy Shaft was sunk to access the Mount Charlotte and Reward Orebodies below the Flanagan Fault. The 1,184m deep shaft is concrete lined to 6.5m diameter for its full depth. The initial 590m was excavated by stripping into a 1.8m diameter borehole and hoisting the broken material through the existing mine. The remaining 594m was excavated by conventional shaft sinking methods. The shaft was sunk through 3 existing plats and an additional 8 plats cut. 1,800 tonnes of steel and 8 cables were installed during the furnishing of the 4 compartments.

Jan 1, 1985

The Kennedy Siltstone Open Cut provides graded rock for stope filling. Rotary drilling of 310 mm blastholes with a Gardner Denver GD120 is used, and the successful application of an equilateral triangular drilling pattern is described. Charging practices and the development of bulk slurry handling are outlined. Blast monitoring plays an important role in K.S.O.C. drilling and blasting operations. The proximity of nearby residential areas (1300 m) and the Mount Isa Airport (4500 m) necessitates special attention with regard to the minimisation of both air blast and ground vibration levels. The application and control of drilling and blasting parameters has had a direct bear- ing on success of the mining operations and also played an important role in reducing the disturbance to the community.

Jan 1, 1978

Results of investigations on adsorption and desorption of CO M CH and a mixture of the two gases are described.4 Results showed that even when the equilibrium conditions contains 50% Co and 50% CH4, the gas emission in the initia' stages will contain as much as 80% CH . 4 The temperature has a small effect and so also particle size for 1.4-11.2mm. The ratio of CO2/CH gases adsorbed in coal samples depends upon t4he equilibrium pressure and this ratio decreases with pressure. Results of field tests support laboratory studies.

Jan 1, 1988

By T J. Orr

The changing demographics of the mining industry make successful passing of knowledge and skills to the next generation critical. Training methods and technologies are being developed to meet this need. Twenty years ago classroom training was largely a one-way transfer of knowledge through instructor lectures. In contrast, instructors today can use virtual reality technologies to guide trainees as they fully participate in learning experiences. Trainees can interact with the virtual work environment, co-workers, and equipment without being exposed to workplace hazards. The speed of advancement in mine safety, health, and production training shows no sign of slowing in the next 20 years. Researchers at the National Institute for Occupational Safety and Health have studied and participated in the evolution of miner training. A look at training materials they have created in the past and those they are currently developing reveals changes in methods and technologies over time and also key characteristics which have remained constant. Possibilities for the future can be discussed in the framework of an implementation of virtual reality in new miner training sessions. The example computer-based training package teaches new miners to read mine maps and provides opportunity to practice navigation skills in a virtual mine. With this æserious gameÆ, trainees experience the look and feel of moving through an underground coal mine while in the safety of their classroom. During field-testing in 2007, trainees and instructors responded very favourably to this new way of learning. The software was usable by mine trainers with even limited computer expertise and could be installed on the affordable computers they were using for their more traditional slide presentations. The Underground Coal Mine Map Reading TrainingÆs foundation on past successful development strategies and its acceptance by todayÆs instructors and trainees provide valuable lessons for developing training materials, strategies, and technologies for miningÆs future.

Jan 1, 2008

Five Hypotheses are given for factors influencing long-run metals price forecasts. 1 . Geologists succeed when given the money. 2. Better understanding of a metals market depresses its price. 3 . Statistical techniques get forecasts wrong. 4. Long-run metals prices are related to crustal abundance. 5 . Economic cycles affect metals prices more than is realised. These are then framed within the transition between eras as influenced by apparent long waves in economic activity. Innovation surges during the transition between eras. The transition to the 5th Wave since the Indus- trial Revolution 200 years ago is now underway. Finally, price projec- tions are given both for the 5th Wave and 200 years from now on the assumption that a similar monetary measure to today will be then extant.

Jan 1, 1988

By J Boland

Polycrystalline diamond compacts (PDC) have been widely used as cutting elements in the drilling tools for the oil, gas, civil and mining industries because of their faster penetration rates and longer bit life. US Department of Energy reports that PDC bits account for more than one-third of the total footage drilled worldwide (US Department of Energy, 2004). However, non-thermally-stable diamond composites (NTSDC) have seldom been applied to geothermal drilling, since premature failures of such PDC cutters have been observed in hard rock formations. Several factors need to be considered to prevent premature failure of cutters and improve cutting performance when using PDC-based bits and other rock cutting tools. The first set of factors consists of the strength, density, stiffness, toughness and thermal resistance of the PDC and the rock. A second set relates to the complex behaviour of the bonding between the PDC cutter and the bit matrix, or the pick and the pick holder, which is vital in maintaining stable, reliable and durable adhesion of the cutters to their hubs. Finally, based on a better understanding of the cutting processes, the formulation of a predictive model would assist in further development of cutter design.

Jan 1, 2004

By McCarthy P. L

A distinctive feature of the goldfields of Victoria was the extrac- tion of gold from deep leads, that is the buried river beds of Vic- toria's ancient rivers and streams. It is estimated that about 265,000 kg of gold was produced from Victoria's deep lead mines which comprises about 11.5% of Victoria's total production of gold (Bowen, 1974). The significance of deep lead mining for Victoria, however, went far beyond its economic contribution to Victoria. If Profes- sor Blainey is correct it was the frustrations of mining gold from deep alluvial leads in Ballarat during 1854 which precipitated the Eureka Stockade (Blainey, 1963, 46-52). This event resulted in the implementation of a fair mining administration and was an emphatic statement of the rise of democratic movements in Australia. Much of the technology and skill for mining deep leads had to be developed locally because at that time no other major gold- field elsewhere in Australia or the world had gold deposits with comparable problems. Deep lead mining in Victoria was there- fore largely a home grown industry and the equipment for that industry was often designed and produced in Victoria.

Jan 1, 1988

The mining of mineral sands in coastal aquifers is often constrained by other land use conflicts and inappropriate controls imposed through a lack of understanding of environmental interactions and processes. The recent experience with the Tea Gardens mining operation illustrates how increasing our knowledge and understanding leads to more effective management of environmental problems. As well as a source of heavy minerals, the Tea Gardens sand bed serves as a town water supply source. From past experience it was believed that mining could cause undesirable increases in dissolved iron concentrations in the aquifer, but the reasons and mechanisms for this phenomenon were not clear. A water monitoring program was therefore designed for the mining operation which was aimed at protecting the water supply borefield from any detremental effects. After one year the results of the monitoring program were assessed in the light of new knowledge and understanding of iron hydrochemistry. It was found that the existing program was not achieving some of its major aims, and was therefore modified to a more effective and cost efficient program.

Jan 1, 1988

By Young DJ

Gold mineralisation at the Hamata prospect is related to a series of stacked pyrite and quartz-pyrite veins associated with a number of shears which strike N to NE and dip E. Mineralisation is contained entirely within the Morobe Granodiorite close to the intersection of the Upper Watut Fault and some younger NE to SW striking faults. The prospect was originally detected in 1987 by a regional stream sediment sampling programme. Subsequent mapping and sampling outlined an anomalous zone approximately 900m long by 300m wide. Drill testing has indicated a resource of 46Mt at 0.9 g/t Au.

Jan 1, 1991

By Cotton R. E, Cox R

Digger Rocks is one of several nickel-bearing sulphide deposits localised within komaLiitic volcanics of the Forrestania Greenstone Bell within the Archaean YiIgam Block of Western Australia. Exploration and evaluation to April 1990 have delineated a resource, at a nominal cut-off grade of 0.5 per cent Ni, of 1.9 Mt at 1.1 per cent Ni within a lensoid sulphide body which strikes NW, dips 50°SW, and occurs at a depth of 30 - 110 m below surface. There has been no production from any of the Forrestania nickel deposits to-date. The deposit, comprising both disseminated and massive sulphides, has maximum dimensions of 400 m strike, 115 m vertically and 90 m true width. Generally the massive sulphides occur at the base of the disseminated sulphides, on or close to the base of the Digger Rocks dunite. The two main massive sulphide lenses have maximum dimensions of 120 m strike, 75 m vertically and 16 m true width (northern lens) and 60 m strike, 25 m vertically and 4 m true width (southern lens). The average grades of the massive and disseminated sulphides are 5.9 per cent i and 1.2 per cent i respectively. The massive sulphides generally have sharp hangingwall and fOOlwall contacts and display strong internal grade anisolropy.The massive sulphides are mainly within the supergene zone and consist of violarite, pyrite and marcasite. The disseminated sulphides are mainly within the primary zone and consist of pentlandite, pyrrholite, pyrite and minor chalcopyrite. Alteration zones, up to six in number, are complex in detail. The sulphides are capped by an average of 30 m of sub-economic, leached, siliceous, oxidised material.A genetic model for the deposit is described which places Digger Rocks in Category 2 (sulphides in large layered dunite bodies) of the latest classification of komatiitic nickel sulphide deposits in the Yilgam Block of Western Australia by Hill and Gole (1990).

Jan 1, 1992

By Bromley JC

Eimco Great Britain, a division of Baker Mining Equipment Company, was contracted to develop a hardrock tunnelling machine in conjunction with British Coal. The objective: a machine to cut rock up to 170 MPa compressive strength yet retaining the flexibility of roadheader type machines. This flexibility to encompass mobility, wide range of excavation shapes and sizes, simplicity of design and use, compact size, and efficient cutting operation. Current roadheaders operating in hard material are characterized by: 1. Severe machine vibration 2. Bouncing of the boom away from the rock 3. Very high pick wear 4. Inability to sump head in bad floor conditions The reasons for this poor performance can be attributed in part to: 1. High speed of cutting head rotation 2. Inability to hold boom against rock while cutting variable hardness strata. To overcome the problems described, a new articulation method was developed utilizing four hydraulic rams to "lock" the boom in position on one axis and four hydraulic motors to rotate the boom for cutting via a turret arrangement. The slide mounted turret is hydraulically advanced for sumping into the face, independent of the machine base. To transfer cutting forces back to the rock, the machine base is held rigidly in the excavation by floor to roof or side to side rams. A cutting head mounted on the boom rotates at very low speed, but with very high torque.

Jan 1, 1987

The paper describes the design of the dilute medium and medium recovery circuits installed at the coal preparation plants at the Cornwall Coal Company's Fingal Mine, and the BP Coal Australia's Howick Mine. These circuits maximize the use of clarified water for rinsing to improve the mass transfer of adhering medium from the coal surface into the carrying liquid, and have been combined with the use of a two stage magnetic separator. The separator utilizes a conventional concurrent first stage and a counter-rotation second stage. This combination results in high medium recoveries during both normal operation, and start up and shut down phases when large quantities of medium can be lost from a conventional circuit. Overall losses using this circuit have been estimated to be, 200g/t, over a twelve month period. Further advantages in plant operation are also obtained, especially steady operating conditions in the centre-tube pump tank, lower slimes contamination of the product, and lower quantities of non magnetics trapped in the separator concentrates. The techniques are particularly suited to incorporation in circuits treating coals containing high percentages of sticky and difficult clays, as are found in the Walloon coal measures.

Jan 1, 1987

Gold at Renco occurs in association with pyrite, pyrrhotite, chalcopyrite and quartz and is confined to a series of brittle fractures and fault breccias (reefs) preferentially developed within an anastomosing ductile shear zone. During late Archaean crustal movements both the orebody and the enclosing host rocks were deformed within a series of east-north-east striking, southerly dipping, shear zones. The reefs within these shear zones are now texturally different to those away from the shear zones, and this difference is reflected by differences in the way the gold is distributed in the two reef types. These differences are not taken irto account by the software package currently being used to generate kriged plans of gold grade and reef thickness and this may explain some of the inaccuracies found in these plans.

Jan 1, 1990

The first mining in Western Australia probably commenced some 40 000 years ago when Aborigines arrived and began quarrying stone for tools and weapons, and ochre for decoration. The earliest documented mining by European settlers took place in 1850 on a small lead vein in the bed of the Murchison River, reported by the explorer A C Gregory. However, it was the discovery of gold in the Kimberley region in 1885 that first drew wider attention to the State's mineral potential.

Jan 1, 1992

By Palmer C. G, Rowe P. G

Ore handling improvements at Mount Isa Mines Limited were necessary to keep abreast of technological advances in all phases of sublevel stoping practice.In the early 1930s an efficient ore handling system was in operation.However in 1936 excessive water encountered in deepening the hoisting shaft necessitated the sinking of a second hoisting shaft. Financial difficulties prevented abandoning the original shaft and surface ore handling and crushing facilities, so ore was transferred underground and underground crushing deferred. It was not until 1951 Jhat multilevel crushing permitted increased efficiency in the handling of ore from stopes. Ore was then hoisted in one shaft and transferred on the surface by conveyor belt to a new crushing plant.In 1956 a planned production increase from 5,000 to 11,000 tons per mining day made possible further improvements in ore handling. Larger equipment was installed and existing equipment modified to capacitate the handling of larger sized ore at increased daily tonnages.INTRODUCTIONThe intensive exploratory programme commenced in 1954 disclosed large reserves of both lead and copper ores and in 1956 an expansion programme was initiated to increase production from 5,000 to 11,000 tons per mining day. The increased tonnage would result in decreased costs per ton and further cost reductions would result from increased mechanisation underground. The combined effect would permit larger tonnages of lower grade ores to be included in ore reserves. To achieve both cost reduction and the scheduled production increase, improvement in ore handling was of vital importance.For efficient and low cost sublevel stoping it is necessary to maintain an economic balance between...

Jan 1, 1961

By Ward B

Central Colliery was developed to exploit large underground reserves in the German Creek lease. It was planned from the outset as a retreating longwall operation and is the first longwall mine in Queensland. Longwall mining is not new to Australia but all previous experience has been confined to the coalfields of New South Wales. There was no precedent for longwall extraction in the markedly different geological setting of the Bowen Basin in Central Queensland. Various investigations were thus carried out during the initial development of Central Colliery, prior to the installation of the longwall, to ascertain the geotechnical characteristics of the coal seam and the adjacent strata and to predict the performance of the heading and pillar design as mining proceeds to depth. Laboratory tests showed the coal to be weak with an unconfined compressive strength of 9.6 MN/m2. Site inspection and geophysical correlation revealed a shear zone and extensive intraformational shear planes in the seam. The latter were found to exert a controlling influence on rib reaction in the headings. This behaviour was predicted by finite element modelling of the development headings which indicated that mining induced stresses in the coal would be relieved by block movement of the ribs. A chain pillar width versus depth curve was established for yielding pillar design based on empirical and computational methods. This gave pillar widths from 25m to 48m over the proposed depth range of 150m to 300m. Finite element modelling of the 25m pillars chosen for the first gateroads confirmed the overall stability of the design but suggested that rib spall could be significant in the adjacent tailgate. (1) Chief Mining Engineer, Capricorn Coal Management Pty. Ltd., German Creek Mine, Queensland (2) Senior Engineering Geologist, Coal Division, The Shell Company of Australia Limited, Melbourne

Jan 1, 1986