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Answers to the questions "which rocks contain diamonds?" and "which indicator minerals should diamond explorers look for?" are no longer so easily obtained, now that diamonds are known to occur in lamproites and various types of lamprophyres, as well as their traditional source of kimberlites. One way of isolating those factors (host-rock"geochemistry, geographical or tectonic location, xenolith minerals, etc.) which are most critical in determining the diamond potential of a given pipe, is a detailed and critical re-examination of the huge volumes of accumulated data on kimberlites, lamproites and related rocks. A large analytical database to this end has been set up on an Apple Macintosh II microcomputer using the quasi-relational database management system 4th Dimension. Currently, it contains data for up to 90 major and trace elements, isotopic ratios and contained mineral compositions for some 4,000 rock specimens from all over the world. Many experiences in setting up this database are probably relevant to other geologists setting up their own systems: they include determining the relationships between data items; the advantages of codes over free text in representing categorical variables such as rock types; the need for rigorous error trapping and data validation; and the problem of missing data values and ambiguities thereof. The working system is now being used in a rigorous statistical assessment of the criteria which distinguish diamondiferous from non-diamondiferous rocks.

Jan 1, 1989

By Black LP, Law SR, Oversby BS, Mackenzie DE, Wyborn D

Three volcanic sequences of different ages occur close together in the Burdekin Falls area, southeast of Charters Towers in northeastern Queensland. The oldest is equated with the Cambro-Ordovician Mt Windsor Volcanics, and consists mostly of strongly deformed, regionally metamorphosed rhyolitic lava and minor feldspathic to quartzose sandstone. This unit is overlain by folded but unmetamorphosed Upper Devonian-Lower Carboniferous volcanics (DCv) of the lowermost Drummond Basin sequence. The primary volcanic facies of (DCv) principally comprises andesitic and rhyolitic lavas, and dacitic ignimbrites. Similar volcanics are widespread in the lowest formations of the Drummond Basin sequence elsewhere, and dominate that sequence east of the Anakie Inlier. The youngest volcanic sequence is Late Carboniferous and composed of lower, more deformed, compositionally diverse ignimbrites, lavas and conglomerates, overlain by generally less deformed rhyolitic ignimbrite sheets. The upper part is equated with the Bulgonunna Volcanics which extend 90km south to the Mt Coolon area. The Burdekin Falls area contains an ignimbrite stratigraphy different from that in the south. However, one of the most voluminous ignimbrites (Locharwood Rhyolite) in the southern stratigraphy is also present in the north, enabling the two to be correlated.Each of the three volcanic sequences reflects proximity to eruptive sources. Both the volcanics at the base of the Drummond Basin sequence and the Late Carboniferous volcanics are largely the products of subaerial eruptions. The former were erupted from several intermediate-composition volcanoes, and the latter from multiple-vent silicic calderas. All three sequences are considered to be prospective for precious and/or base metal mineralisation. Polymetallic massive sulphide deposits occur in the Mt Windsor Volcanics farther west, and many epithermal gold prospects and mines are hosted by the volcanics at the base of the Drummond Basin, especially east of the Anakie Inlier. The Late Carboniferous volcanic sequence is deeply eroded, and co-magmatic high-level plutons are widely exposed; this sequence may therefore be more prospective for deeper-than-epithermal mineral deposits.

Jan 1, 1990

By Moxon N. T, Berndt J. R

BHP-Utah Coal Limited's Peak Downs Mine is located in Cen- tral Queensland, approximately 200 km south west of Mackay. The annual raw coal production of the mine is over 8 million tpa, requiring the removal of about 40 million cubic metres of prime overburden. This is achieved through the use of five large draglines. The large depths of overburden (up to 55 metres) encountered over half the strike length of the mine enables cast blasting to be carried out in conjunction with draglines employ- ing the chopping method of digging. The objective of cast blast- ing is to use explosive energy to move as much material directly into spoil as possible. The additional costs of drilling and blast- ing are offset by reducing dragline rehandle. Two factors which are of primary importance to the design of cast blasts are initiation control and material velocity. High speed motion picture photography is a powerful diagnostic tool to quantify these aspects of blasting (Winzer, Montenyohl and Ritter, 1979; Chiappetta et al., 1983; Anon., 1983). The objec- tives of such analysis are to: 1. Determine the burden velocity, 2. Determine the time to initial movement (that is, the inter- val between a face hole firing and the initial movement of the burden), 3. Check the accuracy of the initiation sequence. BHP Central Research Laboratories (CRL) and Peak Downs Mine monitored a cast blast in the mine's Winchester Pit on 18 August, 1988. The objectives of this exercise were to: 1. Quantify current cast blast performance, providing a base case for comparison with modified blast design. 2. Compare two orientations of angled holes within the blast. 3. Assess the effectiveness of cast blasting utilising an air-deck. 4. Check blast timing with respect to burden movement times.

Jan 1, 1989

The paper describes the geology, structure, stress, gas and strata geomechanical properties for Leichhardt Colliery and their reactions to mining.

Jan 1, 1986

By L Cooper, J Sharma, M J. Hendry

Thick clay tills below potash mine tailings and brine ponds are important natural barriers protecting fresh water aquifers in Saskatchewan. Centrifuge modelling was applied to assess geochemical processes and impacts of dilute brine (0.1 M NaCl) migration through clay till core samples obtained from non saline, unoxidised clay till at a mine site. At accelerated gravity of 876 + g, during each day of centrifuge modelling, flow driven through a 52 mm length core simulated transport through a 45 m thick clay over ~2100 years. Hydraulic conductivity, monitored continuously before and during brine permeation, was low and relatively constant (8.5 + 10-12 m/s), confirming that confining stresses prevent permeability increase. Core density and porosity measurements confirmed that reactive transport occurred under realistic in situ conditions. Breakthrough (defined by C/C0 = 0.5) of non-reactive Cl- occurred at 25 days. The slight delay for Na+ breakthrough, associated with small increases in Ca2+ and Mg2+ concentrations in the effluent were attributed to ion exchange, but carbonate reactions were relatively unimportant. Cation exchange analysis of core samples was inconclusive without corrections for porewater Na+ and carbonate dissolution. Geochemical processes that were observed during centrifuge modelling were successfully simulated using the 1D geochemical transport code PHREEQC. Solute transport was dominated by diffusion with limited ion exchange to delay Na+ migration. Brine would not break through a 45 m thick clay for tens of thousands of years. Based on these findings, the thick clay till at this site, if laterally extensive and undisturbed by drilling activity, is likely to act as an effective natural barrier to vertical brine migration over the long term.

Jan 1, 2003

By H Yuan, H Tian, Y Zhang, Z Wang, C Wang

Submerged arc welding (SAW) is one of the significant metal-joining processes for manufacturing marine vessels, steel pipes, and offshore structures with high deposition rate and engineering reliability. Welding flux serves several essential functions, including atmospheric shielding, arc stabilisation, bead morphology control and weld metal (WM) refinement. Therefore, from a thermodynamic point of view, the focus for flux design and WM compositional/microstructural modification has been placed to elucidating the transfer pathways and mechanisms of major alloying elements, such as Si, Mn, Ti and O during welding. To this end, a thermodynamic model has been established to predict alloying element contents in the WM. Such functions are enabled by the physicochemical properties of the fluxes, which are inherently rooted in the nature of the fluxes. A unique yet systematical investigation, including physicochemical property changes and structural evolution behaviours, has been conducted over the wide range of fluxes applied to actual welding of EH36 shipbuilding steels. Combined with spectroscopic methods, structural behaviours of network formers such as SiO2, Al2O3 and TiO2 and network modifiers such as MgO, MnO and CaO have been illustrated. Viscosity and ionic conductivity have been found to be positively associated with the degree of polymerisation.

Aug 21, 2024

By Denby B, Hollands R. Schofield D

Surface mines are in operation worldwide, the vast majority employ large haul trucks for the transfer of material both to the outside world and around the site. The sheer size of these trucks and the operating conditions means there is a high

Jan 1, 1998

By Johnson N. W, Ralston J, Lauder D. W, Smart St C R

The flotation behaviour of the Hilton ore of Mount Isa Mines has been examined in the presence of two collectors (sodium ethyl xanthate (Ex) and sodium diisobutyldithiophosphinate (3418A)) over a range of flotation Eh values and collector additions. Tests were also conducted in the absence of collector to determine the relative contributions of natural and self-induced floatability of the major minerals in the feed. In these tests the influence of metabisulphite on the self-induced floatability of the minerals was also determined. Attention focussed on optimising the selectivity of galena flotation. It is shown that the Hilton ore sample contained lower levels of naturally hydrophobic iron sulphide minerals than are generally contained in the Mount Isa lead-zinc ore. Furthermore, the self-induced floatability of galena was less than that exhibited by the galena in the Mount Isa lead-zinc ore. Sodium metabisulphite (MBS) reduced the self-induced flotation of galena but had no effect on the natural floatability of the iron sulphide minerals.

Jan 1, 1991

By Coppock BW

Sintering of lead and zinc concentrates is practised by Sulphide Corporation Pty. Limited to provide both desuiphurised lump sinter feed, for simultaneous reduction to zinc and lead in the Imperial Smelting Process blast furnace, and sulphur dioxide gas for sulphuric acid manufacture. From November, 1969 a 20 percent increase in production rate has been obtained through improvements in operating technique. A gradual increase in bed permeability was achieved by modifications to the feed mix conditioning equipment and by improving moisture control. However advantage could not be taken of the higher permeability to increase sulphur elimination because the hardness of the lump sinter decreased. Higher throughput, better quality sinter and more stable sintering conditions were however made possible by simultaneously: 1. reducing segregation and compaction in the sinter bed, by narrowing the discharge opening of the main layer feed hopper, 2. reducing the sizing of sinter returns to give a closer size spectrum of particles in the feed mix, and 3. increasing the sulphide sulphur content of the feed mix to give higher bed Temperatures.

Jan 1, 1972

By Chander S

Properties of surface films on chalcopyrite and pyrite differ due to variations in the mechanism of oxidation of the two minerals. In the case of chalcopyrite the first step in the oxidation is the release of iron as ferric ions, which hydrolyse depending upon conditions prevalent in solution. The iron oxide/hydroxide layer formed by hydrolysis of ferric ions is quite porous and easily detachable from the surface of chalcopyrite. When the surface oxide layer is detached a sulphur-rich layer is exposed making chalcopyrite hydrophobic. The thickness and properties of the sulphur-rich layer determine its flotation response, both in the absence and presence of collectors. In the case of pyrite, on the other hand, iron is released as ferrous ions which require much higher pHs to hydrolyse. These ions remain adsorbed on the surface of pyrite making the surface hydrophilic. When the iron species are complexed with chelating agents such as ethylene diamine tetra acetic acid, pyrite was hydrophobic. Siderite forms in the presence of carbonate ions, which might be present in several flotation systems. Siderite nucleated on isolated sites at the surface. The presence of such a precipitate is likely to influence the interaction of pyrite with various reagents thereby altering its flotation behavior. To determine the mechanism of oxidation, kinetics of oxidation of chalcopyrite and pyrite was studied using several electrochemical techniques, namely, cyclic voltammetry, polarisation and impedance spectroscopy. Floatability of the minerals was investigated by measurement of contact angles on mineral electrodes and by Halimond tube flotation. Impedance spectroscopy was especially useful for estimating various properties of surface film for both the minerals. Properties such as charge transfer resistance, porosity, and capacitances of the surface films on the two minerals are compared under several conditions of oxidation. These properties were found to be a strong function of the rate and the extent of oxidation.

Jan 1, 1993

By Kametani H

Since pyrite is a semiconductor, the relationship between the leaching rate and the semiconducting properties is of interest. In order to investigate this relationship, a pyrite concentrate (95% FeS2) was oxidized at 90¦C (363 K) in an acid solution containing 100 g/dm3 H2SO4 and 1.0 to 25.1 g/dm3 total Fe. The suspension potential (Pt vs. SCE) was maintained at the desired values, within the range 0.40 to 0.70 V, by controlled additions of a KMn04 solution during leaching. The results were analyzed using a simplified kinetic expression. The rate constant was independent of the Fe concentration, while it increased with suspension potential. Partly oxidized samples were then prepared at varying fractions of reaction. After removing the elemental sulphur formed, they underwent thermoelectric power measurements using a packed bed lying in a temperature gradient. The value of thermo- electric power increased from about 0 to 30 pV/K in the early stages of oxidation. The results obtained are compared with those for chalco- pyrite reported in a previous paper.

Jan 1, 1987

By Coombes J, Richards W. L

The objective of this paper is to illustrate, in a practical way, how both geologists and mining engineers can use conditional simulation to add value to their decisions. Inherent assumptions, requirements and essential components of condition

Jan 1, 1998

By Else D

While the underground mining work environment may have processes and equipment considered unique, most of the broad issues likely to affect the occupational health and safety of employees are not. One such occupational health and safety issue that is common to the mining sector and most other industries is noise. Noise as an occupational health and safety issue is of national significance. Presently noise induced hearing loss costs Australia around $35 million per year on compensation claims experience alone. Noisy equipment and work environments are still being tolerated in parts of the mining industry as `part of the job'. Where work has been undertaken in noise management, considerable emphasis has been placed on either industrial hygiene monitoring programs or the provision of hearing protectors to miners working on or around noisy equipment.Opportunities for more cost-effective and long term methods for controlling noise exist. Ready to apply solutions to noise problems in the mining industry are available, but for many mining operators this information is often difficult to obtain. To overcome this problem, the SHARE program collects and distributes solutions to occupational health and safety problems. The program aims to help organisations to close the gap between what is known about solving health and safety problems and what is actually being applied at the shop floor level: Recent developments have incorporated the SHARE program concept into worksite hazard management projects that involve the participation of employee representatives, front line supervisors and engineering personnel. Besides providing workforce members with an increased understanding of hazard management skills, the SHARE in-house program results in the implementation and sharing of solutions to health and safety problems by the program participants.

Jan 1, 1992

Methane is present in varying degrees in nearly all underground coal mining operations. At mixtures with air near 5-15% it is explosive and consequently since it is not usual for these levels of contamination to be reached in the general body of a mine ventilation system it is not unusual to experience it in specific places. On longwall faces the most used power loader is the shearer machine and because of its general shape, situation and operation it is likely that all the factors which are required to cause a frictional ignition can be present. This paper makes a general appreciation of the causes of these ignitions and methods which are and have been used to control these situations on and around these machines.

Jan 1, 1981

Despite the research interest on non-cyanide gold lixiviants over the past three decades all the non-cyanide gold processes are still at the developmental stages with limited understanding on solution and pulp chemistry in some cases. This is partly associated with:the difficulties in measuring reliable equilibrium data for various gold(I/III) complexes with non-cyanide ligands; the lack of knowledge on mixed-ligand complexes; and different kinetic stabilities of gold(I) complexes with respect to disproportionation. This paper presents reliable equilibrium data for complex formation, dissolution, precipitation, hydrolysis and disproportionation reactions of gold(I/III) compounds with a range of non-cyanide ligands: S2-, HS-, S2O32-, SO32-, SCN-, SC(NH2)2, OH-, NH3, Cl-. Solubility of gold(III) compounds with non-cyanide ligands follows the order: Cl- > NH3 > OH-. In the case of gold metal the solubility order at a given temperature is MgS > Fe(III) or Cu(II) / Cl- > Cu(II)/NH3 > NaOH, but the solubility increases with increasing temperature. Rate of gold oxidation with different non-cyanide lixiviants depends on the oxidant, ligand and temperature and follows the general order of oxidants: Fe(III) or Cu(II) > X2 or OX- > O2 (X = halogen). In the case of metal ion oxidants oxygen is required to reoxidise Cu(I) or Fe(II). Some of the reported data on chloride and thiosulfate leaching of gold are presented to highlight the effect of additives and the copper, silver and sulfur contents of the starting material on the success of non-cyanide leaching processes.

Jan 1, 2004

By A Roseman, T Gruber

Traditional methods for installing gaskets for segmented bored tunnels have relied upon different bonding procedures with adhesives that carry a series of disadvantages to segment producers. Fixation of the gaskets into the concrete segment as part of the casting procedure has been developed over the last 20 years and has emerged as an economical solution to produce high-quality tunnel segments for various technical tunnel applications. This paper investigates the advantages of using anchored gaskets, the different tunnel systems that employ anchor gaskets and reviews the first anchor gasket project; the Lee Tunnel and analyses how segment production efficiencies are gained.CITATION:Gruber, T and Roseman, A, 2014. Use of anchored gaskets in segmented bored tunnels, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 253–256 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By M Battersby, F Parra, S Sanchez-Pino

Pneumatic flotation, as developed by Dr Rainer Imhof, has been applied in commercial beneficiation operations since 1987. Over 85 flotation cells have been installed in more than 30 operations, successfully beneficiating a wide range of minerals. Pneumatic flotation is however still considered as a non-conventional flotation process. Due to its highly selective nature in operation it has generally found its market in difficult applications where conventional flotation equipment has struggled. Compa±fa Minera Huasco (CMH) operates an iron ore pellet plant in central Chile. CMH desired to produce a low silica pellet for the export market where the SiO2 grade should not exceed 1.5 per cent. It is common practice in other countries to float quartz from hematite with relative ease. However, the silicates contained in the magnetite ore of CMH are only present as quartz in small quantities and the major undesirable silicates are difficult to float. CMH spent considerable time on developing a reverse flotation process and a reagent suite to try and reduce the silica content to acceptable levels. However, extensive laboratory and pilot plant tests with conventional mechanical tank type cells and with column cells failed to produce the required reduction in impurities. A series of tests with pneumatic flotation cells indicated that this type of flotation technology could achieve the required silica target. A 500 tph Imhoflot pneumatic flotation plant was subsequently constructed and successfully commissioned by CMH, making it one of the largest iron ore flotation plants in the world. This paper details the background and testing that was undertaken by CMH which led them to choose pneumatic flotation as the preferred process and compares the test results with that achieved in the industrial plant.

Jan 1, 2005

By J Krawcz, S Wasilewski, W Mironowicz

Barometric pressure and its variation in deep underground workings have a considerable effect on ventilation conditions. Pressure changes which create transient states of air flow and air parameters in workings are especially significant. Experiments have shown that pressure changes have a remarkable effect on air parameters at mine workings and hence, attempts to evaluate the scale of this phenomenon are of value. Continuous monitoring of the barometric pressure on the surface of mines allows for the detection of changes in pressure which undoubtedly influence alternations of pressure in the underground areas of mines. Very important factors are the internal disturbances of pressure within a mine ventilation system due to variable conditions of fan operation and the operation of a winding machine where a mine cage moving in a shaft causes piston like disturbances. Local transient disturbances caused by temporary opening/closing of air stoppings due to personnel or underground transport traffic are of importance. The results of over two years of observations of barometric pressure and its influence on pressure variation in underground mine workings are presented in this paper. The observations were possible through the installation of pressure sensors at selected points of the downcast shaft in a mine. Of interest are the observations of the transient states of pressure and other air parameters caused by emergency fan stoppage, movement of a mine cage and changes due to the opening of air stoppings. Data acquired during experiments of opening and closing air stoppings were used for the validation of a flow model in a long working.

Jan 1, 2005

By Brimblecombe P

Morwell Open Cut is a continuous mining operation employing 5 buck- etwheel excavators, I bucket chain excavator and 54 conveyors. The combined bunkering capacity at both client Power Stations represents less than 12 hours maximum coal demand. This creates an extremely dynamic operating environment, which is further complicated with significant variations in both excavating and transportation plant capabilities. To achieve set objectives, including- I adequate reserves, 2 coal supply reliability, 3 cyclic plant maintenance, 4 minimal cost of coal, scheduling of the operation requires constant monitoring and reappraisal. Investigations are in progress to develop a computer based scheduling tool capable of simulating the complex operating environment. A review of computer scheduling packages currently available within the State Electricity Commission of Victoria has found limitations making most unsuitable for the task. The type of package found to be most suited is a knowledge based system ('Expert System')capable of operating within a set of rules defined by the user. Work is proceeding on the development of a knowledge base to test the effectiveness of Personal Computer based `Expert Systems'.

Jan 1, 1989

In response to requests from the iron ore mining industry, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Division of Mineral Physics has developed a number of bulk analysis techniques in which analyses are obtained directly from ore samples weighing many kilograms or from ore located on conveyor belts.Because penetrating neutron and gamma radiation is used, measurements are obtained from a large volume of ore, which ensures thal the analyses are represelllative of the bulk.Two different gamma-ray techniques have been developed to measure iron ore grade. The first is based on backscallering of 60CO gamma rays, while the second involves measurement of the annihilation radiation which arises when the ore is irradiated wilh 226Ra gamma rays. Both techniques measure the iron concentration with an accuracy (1 s) of better than 0.4% Fe.A thermal-neutron irradiation technique using a 252Cf neutron source has been developed for the simultaneous determination of iron and the aluminium impurity (expressed as AI2O3) in iron ore fines on a conveyor bell. Because the conveyor speed must not exceed about 0.05 m/s, if good accuracy for AI2O3 is required, an auxiliary analysis bell is required Lo avoid inLerference with normal ore processing. Dynamic trials have demonstrated that accuracies of 0.6% Fe and 0.1% AI2O3 can be obtained.

Jan 1, 1985