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By Knasmillner

During blasting body wave interaction with geometrical surfaces induces Rayleigh-waves which propagate along free surfaces, e.g. crack faces or delaminated rock layers. These Rayleigh-waves carry most of their energy within a very shallow surface layer and propagate with very little attenuation in real rock materials. Upon interaction with a crack front a very strong mixed mode stress intensity factor may result and lead to fracture initiation. On the basis of experimental photomechanical results the history of dynamic stress intensity factors Kt and K2 will be studied in Detail.

Jan 1, 1990

By Hustwick I

New Zealand Steel Mining Limited operates two independent sand mining operations on the West Coast of the North Island of New Zealand. (Fig. 1)Waikato North Head 30km south of Auckland supplies ironsand concentrate as the raw feed for New Zealand Steel's works at Glenbrook, and Taharoa 70km further south, exports ironsand concentrate to Japan. Taharoa uses two sets of six low pressure Warman centrifugal pumps in series to load bulk ore carriers 3km off shore through two underwater pipelines.Waikato North Head delivers the ironsand to Glenbrook l8kms through a 200mm ID buried pipeline using two stages of high pressure positive displacement (HPPD) pumping.A high level of operating and maintenance expertise has been developed since commissioning the two systems which are proving to be reliable, efficient and of minimal impact environmentally.

Jan 1, 1990

By Lowell J. D

This paper is an outgrowth of a continuing compilation of the geology of Chilean ore deposits by Carlos Ruiz who was the author in 1965 of Geologia y Yacimientos Metaliferos de Chile which was the definitive compilation of the ore deposits of Chile. A new version was written by him in 1988, with the co-operation of Federico Peebles L, published in Geologia, Distribucion y Genesis de los Yacimientos Metaliferos Chilenos. Over the past eight years J David Lowell studied the geology of the Chilean mineral belts in connection with planning mineral exploration for copper and gold.

Jan 1, 1990

The overall systems approach to blast furnace aerodynamics is explored including the time and spatial inter-relationships that exist between the furnace lines, tuyeres, burden characteristics, distributor capabilities and furnace operating practice. Attention is called to the time dependent, three dimensional aspects of blast furnace aerodynamics and to the existence of several zones within a furnace where the flow characteristics are different. Changes in furnace operating practice to take further advantage of fully beneficiated burdens including formed coke are discussed from a practical viewpoint. Lessons learned in a variety of shaft furnaces used for other purposes are discussed insofar as they have a bearing on aerodynamics in an iron blast furnace. Questions are raised about the penetration of hot blast in large furnaces. Operating practices and.proposed solutions are evaluated where tuyeres over iron and slag notches are restricted or plugged. Opportunities are presented for using on-line hierarchical computer systems with adaptive tuning algorithms to provide non-linear control of changing process conditions in real time. This will make it possible for the blast furnace operator to optimise a variety of interrelated paramaters, each with different response times. Potential increases in productivity, fuel savings and improved quality control are believed to be within reach.

Jan 1, 1975

The Devonian Mount Morgan gold-copper deposit was situated on the western margin of the Calliope Volcanic Are assemblage, in the northern New England Orogen. Recorded production from commencement of mining in 1882 to mine closure in 1989 stand

Jan 1, 1994

It is a privilege for me to participate in this vitally important discussion of The Role of Governments in the Management of Resources. The distinction of my fellow participants is evidence that this event is a matter of extreme importance and attracts international attention. In the management of natural resources, government and private enterprise share awesome responsibilities for the economic well-being of nations. Mining and its relation to the prosperity of nations is almost as old as recorded history. Copper was being mined and extractive metal- lurgy practised at Timna in Israel's southern desert as far back as 4000 B.C., and the rich mines of Laurium not only saved the Greeks from Persian domination 2500 years ago, but also provided Athens with a monopoly of silver in the Mediterranean world. This bolstered the economic power of Athens and led to the golden age of Greek commerce and culture.

Jan 1, 1978

Structural Controls Interpretation of regional aeromagnetics, radiometrics and satellite image data has identified three structural domains (fig 2): The Fairyland Domain: a general N - S structural trend. The Cracow Domain: a general NW - SE structural trend. The Bald Mountain Domain: a general N- S structural trend. Known mineralisation is confined to the Cracow Domain in which there occurs two major NW - SE trending fault zones. The Cracow Fault Zone (CFZ) and the Immy Creek Fault Zone (ICFZ). Enhanced detail of the CFZ (fig 3) shows three main structural trends within it: NW-SE structures which include the mineralised White Hope South fault zone and the Golden Mile fault zone. NE-SW structures which have an influence on mineralisation in the Orange Creek, Fernyside and Golden Plateau areas. N-S structures comprising several major structural zones.

Jan 1, 1990

By Jensen B, Ofori P, He Y, White E, Stanmore B, Brien M, O&apos

As part of a large AMIRA project, an on-line moisture meter was installed at two mine sites in Central Queensland. This project investigated the factors which control the moisture content of coarse (>0.5 mm) coal from the centrifuges used in conventional coal preparation plants. It was placed immediately after the first centrifuge to isolate the factors pertaining to one machine and its feed.The meter was found to be accurate and precise when compared with manual and mechanical sampling methods. The Grubbs estimator technique indicated that its precision is better than 0.3 per cent at the 95 per cent confidence limit.It has been identified that:1. the variability of the measured moisture contents of coarse coal can be described by normal distributions. Standard deviations of about 0.6 per cent are common; and2. the treatment of the coarse coal on the drain and rinse screens immediately prior to the centrifuge can affect the final moisture content.

Jan 1, 1995

The mechanisms of fragmentation in homogeneous materials and structured rock mass are reviewed. A method previously used to predict vibration damage to the remaining rock is extended and shown to be valid for the prediction of fragmentation in the rock mass removed by blasting. The effectiveness of different explosives in different types of rock blasting is discussed.

Jan 1, 1990

By Boyd G

This paper describes the planning, analysis, design and operational experience of highwall mining based on auger drilling techniques applied to thick coal seams exposed in an opencut highwall. Being the first time such technology has been used in Australia, a large commitment to technical design and logistics planning was given by Callide Coalfields Pty Ltd. This commitment included technical and operations management and supervision, mine services, and the retention of consultants to undertake geotechnical analysis, instrument preparation and instrument installation.

Jan 1, 1991

Since early 1968 the Bureau of Mineral Resources (B.M.R.) has carried out VLF-EM test surveys in various parts of Australia and Papua. The aim of the work, primarily, was to examine the effect- iveness of the method as an exploration tool under a variety of Australian conditions. Selection of test areas was determined by the availability of geological, geophysical and drilling information and by the desirability to include a variety of physical variables such as depth of weathering and topography. The aim of the present account is to review the results of this work and to make an assessment of the method available to the mining industry. The author wishes to acknowledge considerable assistance both by way of data and discussion provided by Messrs. Paul Gillespie (B.M.R.). and John Haigh (formerly B.M.R., now Senior Geophysicist, McPhar Geophysics Australia.) The article is presented with permission from the Director, B.M.R.

Jan 1, 1971

The Highlands Region of Papua New Guinea has 3 major national highways. The locations of these national highways are shown in Figure 1. The Highlands Highway begins at Lae City on the coast and passes through the Highlands towns of Goroka, Kundiawa and Mt Hagen. It terminates at Togoba approximately 10km out of Mt Hagen town. The Enga Highway begins at Togoba and passes through the towns of Wapenamanda, Wabag and Laiagam. It terminates at the giant Porgera Gold Mine. The Southern Highlands Highway also begins at Togoba and passes through the major towns of Mendi, and Tari. It terminates at Koroba station, near the Hides Gas Field. Two separate Feeder roads intersecting the main highway service both the Kutubu Oil Project and the Hides Gas Field. These national Highways play a very important role in the development of Papua New Guinea. Goods and services are delivered to the bulk of the population of the Highlands Region using these highways. Heavy machinery and equipment for the mining and petroleum projects of Porgera, Hides and Kutubu are transported using these roads.

Jan 1, 1997

By Kavetsky A, Scott A

As well as breaking and moving rock, blast energy sets up a seismic wave in the ground which can cause significant damage to rock structures and buildings and disturbance to human occupants. This seismic ground vibration is potentially most damaging when its dominant frequency coincides with the resonant frequency of a structure, leading to high amplification factors between the input ground vibration and the resulting structural response. This paper outlines methods of identifying the resonant frequency of structures. It also describes a practical numerical method for the modification of blast designs to reduce the ground vibration energy in critical frequency ranges. The method is illustrated with two recent case studies.

Jan 1, 1990

Establishing the link between the solid, cold rock of dikes, sills, plutons, and lavas and hot, active magma chambers is the quest of igneous petrology. Differentiation of Earth, the diversity of the igneous rocks, and the spectacle of volcanism are ample evidence that magmatic processes are fundamental to our understanding of planet formation and evolution. Single gabbroic plutons, on the other hand, often show intricate and abundant evidence of the effects of crystal growth and sorting. It has not proven simple, however, to establish the basic principles of magmatic behavior leading to this crucial evidence. Because of their abundance, exposure, simple geometry, large range in size, and often straight-forward petrology, sills are excellent examples of the magma chambers. Physical and chemical processes operating in sills can be recognized that also routinely operate in many other bodies. Understanding the dynamics of sill solidification is essential to understanding the genetic links between lavas and plutons.

Jan 1, 1990

Over the longer term, the adoption of new technology is an essential component in the endless tasks of reducing mining costs, improving safety and improving environmental standards. However the choice of which of the many available new technologies to adopt and which not to adopt is not easy and the price of mistakes can be very high. The most important issue for mine developers faced with making such choices is knowing whether or not a new technology has been developed to the stage where the timing is right for its adoption. A system for categorising new mining technologies is provided. It provides a basis for more easily reaching common understandings about various new technologies and the background information supplied provides an understanding of what it takes to get new technologies to the proven stage and the risks of never getting there. Wherever possible, new full-scale mine developments should not rely on unproven technologies. Approaches to handling situations where a proposed new mine development is not feasible on the basis of proven technologies are also provided. If any commitment to the use of unproven technologies is made, a guarantee of high quality development support from the supplier of that technology is essential. Several case studies of successful and unsuccessful new technology development programs at BHP are Provided.

Jan 1, 1997

The objective in design of an excavation in a jointed rock mass is to achieve a prescribed degree of control of rock mass displacement around the excavation. Any excavation in jointed rock usually involves slip and separation along discontinuities as well as translation and ro- tation of constituent rock blocks. Thus, any acceptable model of behavior around an excava- tion must be capable of simulating the force displacement paths followed by the constituent elements, including rigid body translation and rotation. The distinct element method models such behavior by simulating the rock mass as an assemblage of rock blocks which interact through corner and edge contacts. Discontinuities are regarded as boundary interactions between blocks with joint behavior prescribed for these inter- actions. Introduction of structural element logic allows a variety of installed support sys- tems to be modeled. The response of the support to axial, transverse, and flexural loads is based on explicit algorithms similar to those used in the distinct element formulation. This allows large displacements and rotations and general non-linear constitutive behavior for both the support elements and the interface with the rock. This paper describes both the distinct element and structural element formulations and demonstrates several applications involving sup- port interaction with jointed rock.

Jan 1, 1987

By Patridge A. C

Observations of coal stockpiles subject to unusual levels of instability showed that the particular coals exhibited 'gap grading', a relative lack of intermediate size particles. This led to a suggestion that fine coal particles within the pile might have been induced to migrate under the influence of water flow and to concentrate in relatively impervious layers, resulting in local water saturation and reduction of shear strength. To investigate this suggestion, a large test column has been constructed and washed coals with various levels of fines content have been subjected to a downward flow of water. Subsequent examination of the bed of coal within the column confirmed the percolation of fines and their concentration into horizontal layers, and showed the development of zones of saturation above those layers. Shear box tests showed differences in cohesion and internal friction angle between coals with different percentages of fines, supporting the hypothesis that fines percolation may lead to decreased stability.

Jan 1, 1995

By Rigby D, Gould K. W, Hart G. H

The variation in chemical and isotopic composition of hydrocarbon gases generated from humic source rocks in the Cooper Basin, the orth West Shelf, the agoorin oil shale deposit. ollinsville and the southern Sydney Basin is reviewed, discussed and interpreted.The primary composition of gases generated in and released from such source rocks appears to be very largely controlled by the degree of dispersion of the organic material. For example in eoaly shales, where the degree of dispersion may be high, products as generated may escape into surrounding inorganic structures where further maturational reactions may proceed. On the other hand, when the organic materials occur in massive form, as in coal seams, the hydrocarbons generated tend to be retained within the coal. Further cracking to the stage of methane generation is usually required before release of hydrocarbon products is significant.Secondary factors of importance in determining seam gas composition in the Bowen (Collinsville) and southern Sydney Basins are the invasion of coal measures by carbon dioxide from external magmatic sources and/or the vertical diffusion and loss from the surface ofgases generated at depth.Isotopic measurements of gas composition have been particularly valuable in determining the origins and histories of the gases examined, in demonstrating when gases are of mixed origins and in the prediction of gas quality in exploration.

Jan 1, 1985

A novel fracture-plane control blasting technique with particular application in wall-control blasts in mines employing medium to large diameter boreholes is described. It consists of a string of nested holes, each nest consisting of a large diameter charge-hole flanked on either side by a small diameter satellite hole. Each nest is shown to be an analog of a pressurized hole with diametral notches along its length. This 'equivalent-notched' hole concept for generating controlled fractures along preferred directions has been successfully investigated in the laboratory and in the field. The technique has been used to generate controlled fractures on a quarry bench in highly jointed limestone. The resulting blasts with a 250 mm diameter central charge-hole and 50-75 mm satellite holes show that two nests of such holes almost 5 m apart could be joined by a single co-linear fracture. The design range of diameter ratio between charge-hole and satellite hole is 3 to 6 and spacing is 3 to 5 charge-hole radii. With careful matching of explosives and decoupling, and combination of diameter ratio and spacing, it would be possible to connect two nests of such holes more than 20 charge diameters apart by a single controlled fracture plane. The relative merits of the technique against existing wall-control blasts are discussed, and guidelines for practical fracture-plane control blast designs are discussed.

Jan 1, 1990

The investigations described in this paper aim at the development of a new impact mill. The objective is to produce particle size distributions below 10 .tm without using an air classifier. Circumferential rotor speeds of up to 200 m/s are strived for.

Jan 1, 1993