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By Mousset-Jones P, McPherson M. J

Underground airways are characterized by irregular shape and uneven surfaces including large-scale natural roughness, fractures, and a super-imposed sand roughness. Swirls in the grooves of the wall and separation because of the periodic variation of the open cross sec- tion, due to the blasting patterns, make it almost impossible to calculate average con- vective heat transfer computationally on the bases of the geometrical description of the surface. However, dimensionless friction factors can be used to characterize the surface effect of an airway and an analogy between heat and momentum transfer can be applied to calcu- late an average convective heat transfer Coefficient.

Jan 1, 1988

By Hang G, Hongtian X

In this paper, it is briefly introduced that China's Ordovician limestone confined-water menaces coal mining and Ordovician water is prevented and cured to secure the safety of coal mining. The theory of "Down-Three-Zones" is presented on the basis of research and practice in recent ten years. The concept of "Down-Three-Zones" of floor water-eruption is described clearly. Finally, the principle and method of applying the theory of "Down-Three-Zones" are discussed. 1. An Introduction of Damage: China is rich in coal resources. The conditions of coal field geology are quite complicated. There is an area of two million square kilometre of Karst limestone in nine million six thousand square kilometres of territory. The resources of underground water are rather plentiful, but this menaces coal exploration. Sixty percent of coal mines in China are damaged by limestone confined-water in different scales, particularly coal mines located the Carboniferous-Permian coal fields of the Ordovician limestone distribution area of Northern China. Because there is the 500-800 metre thickness of Ordovocian limestone and the well developed Karst containsl plentiful water, Karst water can have more than 100 Kg/cm pressure. Limestone aquifers have only distances of several metres or several decade metres to coal seam, Karst water can enter the aquituge and even the coal seam, large eruptions often occur. For example, a mine of 3 million ton production capacity had an eruption of 2053 cubic metres per minute. This is the largest confined-water eruption which has brought enormous economic damage and threatened the safe production of coal mining. Therefore, the prevention and cure of Ordovician water has immense advantage to the development of the coal industry. There are several decades experience in the prevention of Ordovician water-eruption in China. The prevention of Ordovician water-eruption has two kinds of plans. 1) dewatering and depression: it refers to dewatering of aquifers as roofs of seam and depression of aquifers as floors of seam in mining areas. 2) comprehensive prevention under the condition of having water pressure in aquiters. Due to enormous water, electricity, equipment and lots of other factors, the former isn't used extensively, the latter tits to China's actual conditions and is used widely. So-called comprehensive prevention under the condition of

Jan 1, 1988

By Yaroshenko YuG, Bokovikov BA, Gordon YaM

Problems of the effect of the number of tuyeres and their parameters on the uni- formity of gas distribution are invest- igated with the use of the authors' devel- oped mathematical model of the movement of gases and materials in the blast furnace. It is shown that the improvement of uni- formity of gas distribution with an increase in the number of tuyeres has a damping character. An analysis of the errors of the specified assumptions of the hypothesis concerning the potentiality of the gas movement in the bed is carried out. It is established that the potential approach model gives good results with the determination of the discharge of gas and its stress field, but is not useful for the calculation of local velocities of gas in the raceway. The results of trials of calculation investigations of the dynamics of form- ation of the raceway and the voidageòfield in beds of burden materials are presented in the concluding part of the paper.

Jan 1, 1981

By Finlayson E, Hilyard D

1:100 000 geological mapping of Bougainville Island has resulted in refinement of stratigraphic subdivisions and relationships. We subdivide the sequence into basement Atamo Volcanics (Late Eocene-Early Oligocene), consisting of spilitised pillow basalts, which are overlain unconformably by Late Oligocene-Early Miocene Keriaka Limestone. The latter is unconformably overlain by fine-medium grained volcaniclastics and minor lavas of the Middle-Late Miocene Toniva Formation which coarsens upward and passes gradationally and conformably into the coarsely volcanolithic latest Miocene-Pliocene Arawa Conglomerate. The Kupei Complex, host to the Panguna.porphyry Cu-Au deposit, consists of medium - K20 microdiorites, granodiorites, and andesites intruding Arawa Conglomerate and Toniva Formation. K/Ar isotopic dates on the Kupei Complex range from 4.8-1.3 Ma, and hence overlap the age of the Arawa Conglomerate. We believe that the Arawa Conglomerate consists of mass flow deposits on a volcani- clastic apron surrounding a volcanic edifice above the intruding Kupei Complex.

Jan 1, 1990

The Hunter Valley Rail Project (HVRP) represents most of the coal producers using the Hunter Valley Rail System in NSW to haul coal to the port of Newcastle. This system carries over 70 per cent of NSW's coal exports, comprising over 30 per cent of total Australian coal exports. Hunter Valley coal is the largest export industry in NSW, and one of its largest export growth opportunities. However, the industry is under intense pressure in international markets from existing and new coal producers and from other energy sources. Whilst potential growth in demand is substantial, particularly for thermal coal in Asia, excess world supply has pushed prices down, and this underlying trend may well continue. The industry has lost international competitiveness and as a result, investment has dropped 44 per cent over the last two years. The industry must be rapidly structured to compete and attract investment on the basis that these pressures will continue. Substantial productivity improvement and cost reductions must be made for the industry to regain competitiveness, otherwise growth will not occur and the industry will decline, with serious implications for the Australian and NSW communities. The introduction of internationally competitive rail freight rates is an urgent and essential part of this process. It is the key objective of the HVRP.

Jan 1, 1995

Proposals for engineering works in the River Dement in recent years have been made in the context of very little geological informat- ion. Breakage of the Tasman Bridge, forced a complete re-appraisal and collection of inform- ation in order to select a new site and predict problems. Seismic, magnetic and gravity methods foll- owed by drilling have allowed an assessment of the nature, thickness and distribution of mater- ials underlying the river bed. Key discoveries included recognition of low seismic velocity silts (1100 m/s) and a separate channel for the river since the Late Tertiary.

Jan 1, 1977

Recent work on computerised mineral resource databases at the Institute of Geological and Nuclear Sciences Limited has concentrated on the development of the GERM, REGCHEM, and MINLIT databases, and their integration in a Geographic Information System using MapInfo software on an IBM-compatible microcomputer local area network. GERM (GEological Resource Map) is a mineral deposit inventory with national coverage and more than 10 300 entries. REGCHEM (REGional Exploration GeoCHEMistry) is a database of stream sediment analyses from open-file mining company reports, containing more than 14 000 sample sites from the Coromandel and west Nelson regions. MINLIT (MINeral LITerature bibliography) is an annotated bibliography of literature on topics relating to the exploration and geology of mineral deposits in New Zealand, and includes more than 5000 entries for published books and papers, and unpublished mining company reports, university theses, and government reports. Master sets of GERM and MINLIT continue to be maintained on a VAX mainframe network but REGCHEM is operated only in the PC environment using the Microsoft ACCESS database management system software.

Jan 1, 1993

By Cotton P. L

Although the terms "pipe" and "tube" are normally considered synonymous, a distinction is often drawn, the former term being applied to the hot finished product and the latter to cold finished material. It is, considered that the title of this paper includes hot finished seamless, and continuous-weld pipe, cold drawn seamless tubing, and electrically welded tubing.The continuous-weld process will be reviewed first, passing to the various methods of seamless manufacturing, which, in addition to meeting the demand for hot finished seamless pipe, also supply the raw material for cold drawn tubing, the manufacture of which will then be described. Finally the electric resistance-weld process will be Considered, and the paper will conclude with a brief review of the processes described and trends in present-day manufacture.CONTINUOUS-WELD PIPEThe raw material for this process is delivered in the form of coiled, hot finished, strip steel, generally referred to as "skelp". The end of one coil is electrically buttwelded to that of'the next, so forming an unbroken strip. This continuous ribbon of 'steel is fed into a skelp heating furnace, and brought to the correct temperature for the forming and welding operations which follow. This temperature is usually about 1,350°C.The heated skelp issues from the furnace into 'a multistand mill, in which the first pair of rolls is designed to form the skelp into tubular shape, the edges being in close proximity to, but not touching each' other. These edges...

Jan 1, 1951

By Xaykhamphoune, Ward B

Draglines have been used exclusively for primary overburden stripping at the German Creek Mine complex in central Queensland, where coal has been extracted from a series of ten open cut pits working seams of the German Creek Coal Measures. Due to the dip of the seams, most of the pits have now reached the limit of current economic viability and the emphasis has switched to underground extraction using longwall methods and to a new area of open cut reserves in the nearby Rangal Coal Measures at German Creek East. This area is characterised by weak Tertiary overburden, relatively steep dips and low strength intraformational shear planes at the top and bottom of the coal.The first pit, with a maximum depth to coal of 15 m at the low wall, avoided any major slope failure through use of scrapers to excavate the boxcut and dump the spoil away from the low wall. However, this method was not considered economically viable for the second pit where low wall depths reached 44 m. Following geotechnical investigations the boxcut was divided into a number of zones depending on depth of cover, dip and thickness of Tertiary clay. Slope stability was assessed for each zone using several analytical techniques to ensure that dragline mining would be acceptable. Slope design parameters incorporating various stabilisation techniques, notably an updip trench backfilled with competent spoil to form a low wall buttress prior to excavation of the boxcut panel, were successfully integrated into the mine plan after careful consideration of the complex scheduling to minimise rehandle.

Jan 1, 1992

By Freeman N

A microcomputer based control system has been developed and implemented at ZC Mines (now Pasminco Mining). The control system maximises throughput at a product size set point while maintaining a "safe" cyclone underflow and mill operating pulp density.To characterise mill and cyclone operation over a range of ore types, 60 circuit surveys were carried out by ZC Mines personnel over a period of four months. The data for each test were model fitted to check for data consistency and to accurately estimate circulating loads.The model fitted results were combined with instrument readings (including in-stream analysis probe assays) and the data checked for ability to predict key variables such as product size and underflow density from measurable inputs.In the resulting control scheme, panicle size and underflow density are not monitored directly, but are predicted by regression equation models based on directly measured variables. The tonnage control loop uses a dynamic model to maximise responsiveness.The system provides a data log output to an mM compatible personal computer at programmable intervals. Comparative data logging over a period demonstrates substantially smoothed circuit performance.The grinding control system was originally implemented using Fischer and Porter micro-DCI controllers. The program has also been implemented on a distributed control system using a sequence oriented programming language.

Jan 1, 1990

By Morris B. J

Soil air samples taken from the top one metre of the soil profile, were measured for C02 and 02 using portable field analysers at a number of sites of known sulphide mineralisation in South Australia. Carbon dioxide anomalies were detected over actively oxidising sulphides during autumn and winter following recent rainfall. Anomalies were not detected where no oxidation was occurring, where seasonal conditions had been very dry, or where the sulphur content of the ore was low (

Jan 1, 1993

Selection of mining methods, stope dimensions and stoping sequences is usually based on comparisons with other similar orebodies or rocktypes. Rock mechanics principles assist the process, which can be further improved by application of rock mechanics' models - in particular, computer based stress analysis techniques. These models vary in capabilities and potential application but, basically, can be subdivided into techniques which only model the surface of excavations, and those which model the total volume to be analysed. To address the wide range of geometries, stoping methods and sequences, and geomechanical environments at Mount Isa Mines, a number of models have been developed. By presenting examples of their actual and potential application it is demonstrated that appropriate use of these techniques will assist in the determination of mining parameters and improve ore recovery. Examples presented cover sequencing in tabular and massive orebodies, location of shafts and shaft pillars, and backfill and hanging-wall stability. It is concluded that surface techniques are more appropriate for regional analyses and volume techniques are more suited to analyses of detailed, local geometry. Colour computer graphics should be an integral part of data preparation, and results interpretation and Presentation.

Jan 1, 1986

By Marquez W

Trace fossils have been found in Bolivian Silurian sediments in "La Iumhre" area close to La Paz-Bolivia.Tracks, are good indicators of depth and environment. A detailed study of the ichnogenus is made.The depth and environmental deposits are analyzed to determine the facies. It was shown that the trace fossils of Silurian sediments in La Paz belong to the Zoophvcos and Nereites facies.

Jan 1, 1990

By Rospigliosi RT, Krouse HR

The San Vicente stratabound zinc-lead rhythmite deposit, Peru, is hosted in carbonates of the Late Triassic - Early Jurassic Pucara Group. These strata were deposited in a large, shallow water, carbonate platform which extended nearly continuously for 150 kilometers (north-south) in the eastern part of the Pucara basin.The distinctive sulfide-bearing rhythmites occur in three dolomite units which, from bottom to top, include the San Judas horizon with one sulfide-bearing manto; the San Vicente horizon with seven sulfide-bearing mantos including the main ore horizon; and the Alfonso horizon with three sulfide-bearing mantos. The dark gray sulfide-bearing dolostone layers range in thickness from a few millimeters to a few centimeters and contain variable amounts of carbonaceous material, pyrite, quartz, fine-grained sphalerite and galena. They are bordered on each side by selvages of yellow to red-brown coarse-grained sphalerite containing minor amounts of galena. Coarsely crystalline white or gray sparry dolomite is found between the coarse-grained sphalerite layers. Although commonly stratiform and uniform in thickness, the dark layers curve, "pinch out," coalesce, and form "islands" and "peninsulas."Mineral replacement textures, the paragenetic sequence, and presence of sparry dolomite, bitumen, intraformational breccias and isotope data support a hydrothermal replacement origin by metal-bearing solutions that deposited the ore and related minerals in space previously occupied by dolomite and evaporite minerals. The alignment of the Zn -Pb deposits, and at San Vicente the orientation of the mantos, the spatially and temporally associated igneous sills and the tourmaline-bearing sandstone support hydrothermal mineralization driven by a magmatic heat source in a tensional regime.

Jan 1, 1990

By Schonert K

The throughput of a HP-roller mill is determined by the acceleration of the feed material within acceleration zone and introduction into the compression zone. Both processes depend on the internal friction and the friction of the material on the roller surface which is influenced by the surface structure and adhering of material. The particle motion in the acceleration zone has been investigated with high speed videos showing the effect of the centrifugal force and the slip on the roller surface. The throughput is discussed in the term of the specific throughput which can be approximated by a linear function characterised by the throughput number and the throughput elasticity. The throughput number is a helpful measure for investigating the influence of the feed material and the surface structure. The experimental results give some guidance for chosing an optimum corrugation profile.

Jan 1, 1993

By Kubik K

The objective of this paper was to determine if recent advances in numerical electromagnetic wave propagation modelling techniques could be used to study the propagation of GPS signals over arbitrary terrain. Specifically the effects of diffraction and multipath were to be modelled accurately for propagation over arbitrary terrain surfaces defined by a digital terrain model. Ideally the model was to be in three dimensions and cover an area of a few square kilometres with a simulation height of a few hundred metres. Simulations were to run on current technology PC's with run times less than a few hours. A relatively new technique that involves a numerical solution to the Parabolic Equations can be used to solve for two-dimensional propagation over any type of terrain. The PE provides a direct solution of Maxwell's wave equations by approximating the Helmholtz scalar wave equation. This technique does not rely on the study of individual ray paths as used in the Geometrical Theory of Diffraction (GTD). It was decided to develop a two dimensional Parabolic Equation code, using the Fourier Split/Step method that allowed propagation over arbitrary terrain (; ; ). The model boundary conditions assumed that the satellite transmission was a plane wave, and that the lower boundary was a perfect reflector. Propagation simulations from the model accurately provide the amplitude and phase of the propagated plane wave at all points within the model domain. The PE model was used to study the effects of diffraction and multipath caused by various types of terrain commonly found in an open cut mining environment. The study of diffraction errors was relatively simple, because we are simply concerned with amplitude of the signal as it diffracts about an obstacle. If the amplitude is above the level receivable by a GPS receiver then the diffraction error can be obtained from the geometry of the terrain obstacle. The study of multipath is more complex, as the computed phase from the PE model is ambiguous and the presence of multipath can only be inferred. Thus the absolute magnitude of the nmltipath error is not currently determinable, though the results of some new work is shown here. This paper shows that diffraction effects can cause significant errors in range. It also shows the effects that multipath has on the received amplitude of the signal and the received phase of the signal. A discussion is made of further work that is presently underway that will allow the direct determination of the multipath error by comparing the ambiguous phase with a reference phase.

Jan 1, 1997

By Lama R. D

The Australian underground coal mining industry is undergoing major changes. This paper analyses the technologies presently being researched in mines, and discusses their utilisation as major contributors in the underground mining of coal in Australia over the next 20 years. It describes the problems that underground mining of the year 2000 will face and the possible solutions to those problems based upon results of present day research. Methods, equipment and organisational requirements are outlined. Developments in micro-electronics, computerisation and monitoring will require a new look into human resource development, education and training, and organisation to meet the challenges of the 21st century. The mining system's philosophies of the future are Outlined.

Jan 1, 1986

The nickel operations at Kambalda consist of mining thin massive to disseminated Ni sulphide orebodies from 10 individual mines of variable grade.Daily sampling involves visual estimation of the grade of working faces based on geological parameters. This system of grade estimation is used as a guide for daily grade control only.Nickel metal allocation is based on an external sampling system. As all ore sources are blended at the primary crusher, only one calculated mill head grade is available. Therefore all sources are sampled prior to crushing. This system historically consisted of mechanically grab sampling ore from trucks as they passed over a weighbridge on arrival at the concentrator. Currently the system involves diverting one out of every ten trucks to its mine sample stockpile, which is crushed through the primary, secondary and tertiary crushing system fortnightly. The individual mine grades are re-combined to create a total sample grade. This is reconciled against the calculated mill head grade. The reconciliation factor is applied uniformly to all individual mine sample grades to calculate mill reconciled mine grades.

Jan 1, 1990

By Wilson R. G

Mining conditions imposed by a coal seam roof can be analysed according to natural causes, before consideration of strata control. All types of roof behaviour can be explained by considering only three independent variables. They are roof rock types, rock stresses and discontinuities. Roof rock types encountered in the Sc.ithern Coalfield of New South Wales (NSW) are sandstone, shale, mudstone, laminite and coal. Each rock has its own mode of failure. Lithological stability of the sediments varies from one type to another. Regional stresses upon a coal seam roof will vary in magnitude according to the proportion of gravitational stress, which is related to depth of cover, and residual stress, which is related to the maximum depth of burial and may be gauged by coal rank. Local stresses will vary according to tectonic deformation, related to irregularities in seam structure.

Jan 1, 1976

By Cutmore NG

The moisture content of iron ore is important in handling, stockpiling, transport and further processing operations. Typically these ores contain both `free' and `bound' moisture, the latter being moisture that is not removed in a conventional laboratory determination of moisture by air drying at 105¦C, and it is the free moisture that is important in dust control and ore handling. The CSIRO Division of Mineral and Process Engineering has previously developed and commercialised gauges, based on capacitance and microwave techniques, for the on-belt determination of moisture in coal and minerals. However, these gauges determine total moisture, and have a different sensitivity to free and bound moisture in the material analysed. Consequently, the accuracy of determining total or free moisture alone may be significantly affected by variations in the bound moisture content. An investigation has been carried out on the simultaneous determination of free and bound moisture in iron ore fines (

Jan 1, 1993