Search Documents

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 Stewart R, Manson RA, Haig DW, Perembo RCB, Kruman B

Since the advent of plate tectonic modelling, the Ramu-Markham valley has been thought the site of a classical island-arc/conti- nent collision zone. In this interpretation the units south of the Markham Valley are held to be island are / micrcontinental mate- rial accreted to Australia and those north of the valley are thought to represent a separate Finisterre island-arc terrane. Recent remapping by the Geological Survey of Papua New Guinea shows: (1) there is no terrane boundary along the Ramu-Markham valley (2) the Finisterre Volcanics are probably part of either a fore-arc sequence or oceanic plateau obducted onto a microcontinent/ volcanic-arc composite terrane, accreted to the continental Australian plate. A new tectonic model is proposed for northern PNG and involves: (I) Eocene to Late Oligocene subduction below a microcontinent remote from Australia to produce the Sepik are and related intrusives, the Finisterre Volcanics (fore-arc or possible oce- anic plateau), together with the Alife blueschist. (2) obduction of the Sepik arc in Late Oligocene-Early Miocene times over the advancing Australian plate. This resulted in crustal melting, some of the products of which are the Mid- dle to Late Miocene Akuna and Bismarck intrusive complexes of the Maramuni arc. (3) obduction of the Finisterre Volcanics began in Early Pliocene times and continues today. (4) post-Middle Miocene mineralisation is the result of melting after obduction of the Sepik microcontinent.

Jan 1, 1997

INDEX OF CONTENTS.1. Historical.2. Manufacture.3. Heat Treatment.4. Fatigue, Failures.5. Consideration of the Establishment o£ a Central Testing or Proving Station.HISTORICAL.Since the introduction of improved high air pressure drilling machines in the early part of the century, efforts have been made to develop the quality of the rock drill bit, in order to take advantage of the greater increase of power output per unit weight of the machines (1). This resulted in the change from solid to hollow steel in the second decade of the present century (2).As the greatest sufferers from the dread disease of silicosis (3), it seemed appropriate that the South African gold mines should be the first to use hollow drill steel. Since then solid drills have become practically obsolete for mining purposes.Water is used with hollow steel drills not only to keep the cutting end cool, but also to assist in preventing the formation of undue dust during drilling. It is of interest to note, however, that water fed through hollow steel or sprayed into the air is only partially effective in removing fine dust particles a few microns in diameter, which particles are said to be the most potent in producing silicosis (3a).So far as the composition of "straight" carbon steel drills is concerned, a commission appointed by the Johannesburg mines carried out a very exhaustive series of tests on drill steels.These drills were manufactured from steel made by all the standard methods, including Swedish, Bessemer, crucible, openhearth, and, to a limited extent, electric furnace steel. It should be remembered that the commissioners' report was issued in 1913, when hollow drill steel had not yet been introduced. Only solid steel drills were then in use.

Jan 1, 1947

By Murray C. G

A database of over 1300 earthquakes has been used to investigate the relationship between seismicity and tectonics in two areas of eastern Queensland and NE New South Wales. These areas have been monitored by several networks that were installed primarily to monitor seismicity associated with the impounding of large reservoirs. Events that occurred prior to the installation of these networks have been excluded from the analysis because they have large uncertainties in location.Seismicity in SE Queensland and NE New South Wales is concentrated in the coastal regions. Activity also extends off the coast of Queensland and beyond the continental shelf. The coastal activity is mainly within the New England Fold Belt. An area of the fold belt overlain by the Clarence-Moreton Basin is also active. There is an area of activity near St. George that correlates to the Wunger Ridge. Fraser Island and the adjacent onshore area, near Maryborough, are notably aseismic.Within the New England Fold Belt there is a NNW trending zone of concentrated activity that includes the South D'Aguilar Block and the Esk Trough as far as Gayndah. The Nambour Basin, the Gympie Province, and the southern portion of the Yarrol Block are significantly less active.Composite focal mechanisms of several groups of accurately located earthquakes in SE Queensland indicate predominantly reverse faulting. This faulting is the result of the crust being compressed horizontally in a NE-SW direction.Activity in the Burdekin Falls Dam area of central eastern Queensland is confined to the Drummond and Bowen Basins. There is also significant activity offshore from Townsville and Bowen.

Jan 1, 1990

Most types of nuclear power reactors use uranium dioxide fuel. Power reactors using natural uranium dioxide'fuel are of special interest to countries such as Australia that have their own uranium supplies. A wide range of uranium dioxide powders can be fabricated and the ideal one flows readily, presses without the need for binders or lubricants, sinters to the required density and gives low reject rates at all fabrication stages. Sinterable uranium dioxide is usually produced via the ammonium diuranate route. The A.A.E.C. is aiming to demonstrate production of nuclear grade uranium dioxide from Australian concentrates, improving technology where possible. Details are given of the dissolution, solvent extraction, precipitation, filtration, drying, and calcination-reduction steps. Solvent extraction from sulphate media is also under study with a view to developing a process to produce a nuclear grade product at the mine treatment plant site,

Jan 1, 1969

A shift in the present day oil exploration scenario from West Coast can be foreseen keeping in mind peak of exploration in Cambay Basin and fast pace of development in Bombay High and its associated fields by the end of this century. Shifts in exploration from structural traps to stratigraphic traps, techno- logical development to drill in deep waters, improving economic situation for oil ventures and proven oil and gas potential of East Coast basins suggest that Indian oil explorat- ion scene will be at its peak along east coast during early 21st century. Hydrocarbon shows in Poonch and Jawalamukhi in Punjab Basin, improvements in drilling to greater depths, better seismic data aquisition, good source rock potential of Subathus and its equivalents and large geologi- cally mapped structures will reopen new avenues for explorationists. Not much exploration effort has been put up so far in Ganga Basin. Keeping in mind size of the basin, sedimentary thickness involved, presence of algal matter deposited in shallow marine environment & higher hydrocarbon indications warrant active exploration. Gondwanas in India having such a large sedimentary area can not be ignored keeping in view generation and production from the non marine sediments of Kenya, Chad, Sudan, Gadon and China. Gondwanas become all the more important in view of gas production from their equivalents-Karoos in Ethiopia and South Africa. In all, above mentioned changes can be predicted in Indian oil exploration scenario during 21st century.

Jan 1, 1986

Direct smelting of copper in a single vessel has long been the extractive metallurgist's dream. Such a process offers the important alvantage. of (i) maximum use of the energy available from oxidizing the sulphur and iron of the concentrate: (ii) restriction of SO2 emissions to a single constant-strength source; (iii) minimum materials handling and (iv) elim-ination of at least one process step. Extensive developmental work was carried out in the 1960's and 1970's to implement such single-step processes. Some of the processes reached the prototype stage and it appeared that copper smelting technology was on the thresthold of a new, efficient, minimum-pollution era. Since that time, however, the forward thrust has slowed and single-step copper smelting is still a process of the future.The paper describes the potential advan-tages of single-step smelting; its history and current status; and the reasons why it has not been adopted industrially. It concludes that the potential benefits of single-step smelting are powerful and that many of the difficulties encountered in the 1970's will be overcome in the 1980's.

Jan 1, 1985

By D Feng, G C. Lukey, J S. J, R R. Dagastine

An ongoing challenge in the coal industry is pyrite removal using the flotation method for fine particles. The use of a æseparation in frothÆ (SIF) technique to recover coarse particles of up to a few millimetres in size has presented a potential solution. However the commercial success of SIF is still limited due to the poor understanding of the separation mechanism. The particle floatability in SIF is determined by the constructive or destructive stresses resulting from the forces exerted by the particle on the bubble films. Hence, the surfactant properties and the mineral characteristics (eg hydrophobicity, shape, etc) are the key factors that control the interaction between the particle and froth. In the present work, the interaction forces between different particles (ie crushed glass, pyrite and coal) and a single air bubble are measured in a non-ionic surfactant solution (pentaethylene glycol mono n-dodecyl ether, C12E5) using an atomic force microscope (AFM). Experimental results show that the interaction is primarily dependent on the contact angle (ie the degree of hydrophobicity of the minerals). For crushed glass, the transition from repulsion to attraction was observed as the contact angle increased. As the concentration of C12E5 increased, the adhesion force was suppressed due to wrapping effect. For coal and pyrite with much higher hydrophobicity, long-range attraction was observed. The effect of shape factor was only visible at high surfactant coverage where sign of destabilisation became noticeable on the retracting force curve. These results provide a fundamental understanding of the direct interaction forces of a complex real system between an irregular particle of either crushed glass, pyrite or coal and a single air bubble. Theories developed for interpretation and modelling are thus far based upon the study of ideal systems of glass or polystyrene spheres and an air bubble and were incapable of explaining the interactions in complex real systems. The presented measurements were a first approach to the problem of real mineral-bubble interaction in flotation systems. Thus, the results can only best be interpreted semi-quantitatively.

Jan 1, 2005

By Thomas G. A

THE irregularity of the Mount Morgan (Queensland) ore body presents problems other than those only of mining. For irregularity of outline is coupled with irregularity of grade, and the ore varies so rapidly from profitable to non-profitable, and fromhighly siliceous to highly pyritic, that the task of estimating quantities and values of ore reserves is manifestly rendered a difficult one, while the actual disposal of the broken ore demands constant supervision.Four classes of ore are handled. The oxidized ore, cheaply mined and cheaply treated, is obtained by quarrying from the top of the mountain. Below the 315-ft. mine level (measured from the original summit) sulphide ore comes in, and this is divided into siliceous sulphide ore (too siliceous for economic smelting), sulphide ore suitable for smelting, and ore too poor either to be smelted or to be treated by wet process with the siliceous ore. It is with these three latter descriptions of ore that this paper principally deals.Although the output from many stopes in the mine may usually be presumed beforehand to be either smelting or wet-treatment ore, yet it is never safe to take this for granted, and constant assaying is necessary. At the same time the ore merges from one class into...

Jan 1, 1911

The paper presents an overview of the mining industry of Papua New Guinea. Although the Bougainville problem is still unresolved, new mines like Ok Tedi, Misima and Porgera, which have come on stream during recent past, have raised hopes of sustained growth period in the industry. Kutubu Oilfield is also being developed in the Southern Highlands and the oil production has commenced from July 1992. Government revenue from these mega projects will increase five-fold during 1993 and 1994. A new mine which is being planned is the fabulous Lihir Deposit, on an island renowned to be full of gold. Gold occurs within a volcano which still contains high temperature ground water because the system which created the deposit is still geothermally active.In Papua New Guinea, problems of environmental management are far easier to tackle than those of a socio-political and economic nature involving compensation payments to the landowners and the distribution of royalties and taxes between the national and provincial governments. At the socio-political level, the country has not been able to resolve the problems of land rights versus mining rights. Whenever mining starts in a big way, it raises people's expectations to a very high level, which then becomes the focal point of dispute between landowners, provincial governments, national government and mining companies. A new system called 'Forum' has been tried to bring all parties together and son out the issues. The system appears to be working well in new mines like Ok Icdi, Porgera, Misima and Kutubu Oilfields.

Jan 1, 1993

By Wright S

Single pellets of mixed lead-zinc concentrate containing up to 20 % lead were roasted in the temperature range of 800-1100¦C. Variables studied included pellet size (from 9-8 to 3-2 mm diameter), gas flowrate past the pellet (from 0.05 to 5 ms t), composition of the atmosphere and the effect of additives such as zinc oxide and silica. After defined periods of time, the pellets were removed from the furnace, quenched and submitted for chemical, XRD, SEM and microprobe analysis. The oxidation of the zinc sulphide followed a shrinking core model. Temperature measurements showed that very high pellet temperatures were experienced at the start of an experiment but after 5-10 minutes these approached a constant temperature. The lead loss from the pellets was then constant with time. Thermodynamics predicted the presence of two bands of lead material in the reacted layer of the pellet. These were found in practice. The lead loss from the pellet occurred from the outer oxysulphate layer via the vaporization of lead oxide polymers. The vapour pressure of PbO, and the loss of lead, was dependent on temperature and bulk gas concentrations of SO2 and 02. At 1100¦C the addition of silica greatly reduced the loss of lead from the pellet. Physical factors such as pellet diameter and gas flowrate past the pellet affected the particle dynamics. These results were found to vary in accordance with the predictions of the Froessling equation.

Jan 1, 1989

The Mesozoic intrusive rocks in southeastern coastal China can be divided into three intrusive suites, and they can be brought into corresponding with four cycles of volcanic activity. This paper describes their time-space relation with volcanic rocks, and their geochemical characteristics. Data from the Mesozoic volcanic-intrusive. complex rocks in Eastern Zheijiang, Eastern Fujiang and Eastern Guangdong show distinct regional differences, both within and tectonomagmatic activity regions. The southeastern coast of China involves four tectonomagmatic activity regions. They have many differences on the nature of magma source regions, activity patterns of magma, time-space distribution, petrography and petrographic facies association of volcanic and intrusive rock and mineralization.

Jan 1, 1990

By Selischop F, Tredoux M

The distribution of platinum-group elements (pGEs) has been investigated in matte and slag samples from Waterval Smelter (Rustenburg Platinum Mines). The study showed that a strong preference of PGEs for alloy phases in matte represents a concentration mechanism that commenced in the furnace but can be considered a continuum from natural processes. Metal losses to fayalite (converter) slag occur by matte entrainment due to the mechanical capture of liquid sulphide droplets from the matte layer, and the exsolution of dissolved metal sulphide resulting from changes in the oxidation state of the slag. The latter is comparable to immiscible sulphide in basic magmas. However, the observed distribution of PGEs shows enrichment in metal phases of the matte. A mechanism is proposed whereby naked PGEs in silicate melts coalesce to form clusters which are stabilised by surface attachment of sulphur atoms. This envelope acts to 'draw the cluster into sulphide melts. Small particle melting effects permit PGE clusters to remain as liquids at magmatic and smelter temperatures.

Jan 1, 1994

By Mostyn G

In the last three decades various theories have been presented to allow the estimation of the force required to cut rock. These have generally relied on an hypothesised mechanism of chip formation.The paper presents results of an experimental program completed on an unjointed artificial rock in which the force and chip geometry were measured during deep cutting with a quarter scale bulldozer tyne. The program included various depths of cut and artificial rock of varying strength. The experimental results are compared with predictions based on three expressions for cutting force. Generally the measured forces are within the range of those predicted but none of the methods predicts the cutting force with any accuracy. It is considered that the discrepancies are due, in part, to the fact the that actual shape of the chip formed in deep cutting is quite different to that assumed in developing the theories and thus the theories cannot be expected to predict the cutting forces. It is concluded that Evans and Nishimatsu's theories predict lower bound estimates of the horizontal cutting forces. Deliac and Fairhurst's approach appears to over estimate the forces required to cut rock. New methods of prediction are required based on the observed mechanisms of failure.

Jan 1, 1993

By Kobayashi M

Particulate chalcopyrite samples (78 ~ 98 mole per cent chalcopyrite, screen size fraction from 710 to 250 µm) were prepared by crushing and sieving lump ore samples from 12 locations in the Mt Isa Mine. Measurements of thennoelectric power (which does not involve the passage of a current) were made using a packed bed that was compressed by loading with a weight and placed in a temperature gradienL Details of the apparatus are described.The effect of particle size was investigated by preparing 12 fractions, with mean particle sizes ranging from 605 to 2.2 µm, from one of the ore samples. Values of thennoelectric power decreased with both increasing particle size and loading pressure; however it remained fairly constant for particle sizes above 80 µm, when loading pressure exceeded 3.3 MPa.Measurements of the chalcopyrite samples gave an average value of -260 JlV/K (-248 ~ -268 µV/K) for nine samples and about -290 µV/K for three samples, showing that these samples were all n-type semi-eonductors.

Jan 1, 1990

Blasting is an essential component of most mining operations, and is used to reduce the rock mass to a workable size distribution, as well as to create stable openings and pit walls. Frequently, there is little difference between the designs of blasts to achieve these two functions, though more advanced operations have developed different designs for these very different functions. To assist in the appreciation of how blasting practices can impact on the stability of rock openings and pit excavations, this paper reviews the role of high pressure explosion gases on final block stability. It is assumed that the stability of all surface and underground excavations are, to a greater or lesser extent, controlled by the interaction between discrete rock blocks. Typically, these blocks will be defined by either natural, or excavation induced, jointing.

Jan 1, 1999

By Amelunxen R, Finch JA

Flotation columns represent an important addition to flotation practice. Columns have largely replaced. conventional machines in molybdenum cleaning in Canada. Columns have been successfully tested on bulk copper/molybdenum cleaning at Gibraltar Mines Ltd. A rougher cleaner/scavenger cleanercombination was shown to be capable of giving higher grades and recoveries compared with three stages of conventional cleaning. A control strategy for the columns has been developed. An interaction between gas hgldup and wash water rate has been exploited to control performance.

Jan 1, 1985

Unprecedented political, economic, and social change throughout the world will have an increasingly profound effect on the dynamics of the world's mining industry. Analysis of the early financial trends in this development (statistics on exploration expenditure, and investment flows) gives some insight into the magnitude of structural change and its implications for established mining economics and companies.Increasing confidence in the stability of many third world and developing countries is attracting exploration and investment capital that had previously been largely directed to established mining economies in North America, Australia, Europe and Southern Africa. Some of the projects requiring capital and technology in the CIS, Africa and Latin America are technically very attractive. The end of the 'cold war' and the influence of the IMF is gradually changing their risk profile for mining investment.

Jan 1, 1993

The Auscoke project has reached-a stage where a pilot plant nominally able to produce 100 t.p.d. of coked briquettes is being brought on stream during Nov. 1971 . The targets for this stage of the project are to establish the technological and economic value of Auscoke for the iron blast furnace, and to verify the commercial feasibility of large scale plants. The project originated at the B.H.P. Central Research Laboratories (C.R.L.) and work to date has shown that using a two stage contin- uous process, strong large coke can be produced at good productivities from medium or low volatile poorly caking coals. General features of the pilot plant and processing are discussed.

Jan 1, 1972

By J Chßvez, J Rosa del Castillo, J Rui

Environmental Impact Assessment (EIA) and Feasibility Studies (FS) were carried out to evaluate the potential use of treated acid mine drainage (AMD) occurring at the Kingsmill Tunnel in the Central Andes of Peru. The 11 km long tunnel drains the underground works of the Morococha Mining District and discharges about 1.25 m3/sec of AMD directly into the Yauli River in the Amazon Basin. The communities living downstream cannot use the Yauli River water due to its low pH and elevated concentrations of metals (eg Cu, Zn, Fe, Mn, As, Cd) and sulfate. Studies carried out for this project included technical feasibility, EIA, economic viability and social impact assessment phases. During the æTechnical FeasibilityÆ phase, the treated AMD was produced by simulating a high density sludge (HDS) lime neutralisation/ precipitation process and was evaluated for various potential uses. Mining companies located in Morococha, in particular Centromin Peru SA, and the Water Works Company of the City of Lima (Sedapal) collaborated with Golder Associates during the studies. The Canadian International Development Agency (CIDA) provided the financial assistance. The results of the physical, chemical, biological and toxicological analyses demonstrated that the AMD could be sufficiently treated to be potentially used to supplement the drinking water supply of Lima, and for agricultural (eg irrigation and livestock) and recreational purposes. Process design and scale-up parameters were also determined for implementation of the full-scale treatment facility at the site. The use of the treated AMD as a drinking water supplement would be economically feasible.

Jan 1, 2003