Search Documents

By R C. Morris

The channel iron deposits (CID) (Ramanaidou, Horwitz and Morris, 1991; Morris, Ramanaidou and Horwitz, 1993; Ramanaidou, Morris and Horwitz, 2003; Morris and Ramanaidou, 2007) are one of the two major iron ore types mined in the Hamersley Province. The CID provided around 41 per cent of the total of 268 Mt of iron ore mined from the Hamersley Province in 2006. The current CID resource is around seven billion tonnes. The CID deposits occupy numerous meandering palaeochannels in a mature surface that includes Precambrian rocks and ferruginous palaeogene valley fill. These palaeochannels are generally less than a kilometre but can range to several kilometres in width and from one metre to more than 100 m thick. The two currently mined CID areas are located:in the western Hamersley Province in the Robe palaeochannel, and in the east in the Yandi palaeochannel. These two major CID channels extend over 100 km to 150 km, with the Robe system up to 5 km wide. The granular ore facies typically contains ooids and lesser pisoids with haematite nuclei and goethite cortices, with abundant goethitised wood/charcoal fragments and goethitic peloids, minor clay and generally minimal porous goethitic matrix. Post deposition weathering is common and produced secondary facies.Ooids and pisoids were mostly derived from the stripping of a well- vegetated deep ferruginous surface. The peloids were derived both intraformationally from fragmentation and reworking of desiccated goethite-rich mud. Minute wood/charcoal fragments in the soil that were initially replaced by goethite and then dehydrated to haematite, formed nuclei for many ooids and pisoids. In addition, abundant, generally small (in situ by goethite within the consolidating CID. This profusion of fossil wood, both as ooids and pisoids nuclei and as discrete fragments as well as the local presence of kenomagnetite suggests major episodic wild fires in heavily vegetated catchments. The goethitic matrix was the result of chemically precipitated iron hydroxyoxides, resulting from leaching of iron-rich soils in an organic environment.

Jan 1, 2007

By J Hadjigeorgiou

The stability of open stopes in underground hard rock mines is influenced by several factors including the shape and size of the excavation, surrounding stresses as well as the degree of jointing. This paper presents a design methodology for stope analysis in jointed rock masses. The proposed approach relies on geological structural data to construct realistic three-dimensional joint network models. The stability of an open stope is determined based on a limit equilibrium analysis.

Jan 1, 2000

By J M. Parr, C J. Yeats

Discovered in 1991 by combined plume detection and bottom-tow photography (Binns and Scott, 1993) and for some years thereafter the highest tenor mineral occurrence known on the ocean floor, the PACMANUS hydrothermal field has since been surveyed and sampled in great detail by CSIRO and international research agencies (Binns et al, 1995; Auzende, Urabe and Scientific Party, 1996; Binns et al, 2002; Tivey et al, 2006). Since 2005 commercial surveys employing deep-tow geophysical packages and remotely-operated vehicles (ROVs) have been conducted by Nautilus Minerals Inc and partners within Papua New Guinea-granted offshore exploration licenses (Nautilus Minerals Inc, 2008). Two academic drilling programs have been conducted, one under the international Ocean Drilling Program (ODP) directed at deep structure (Shipboard Scientific Party, 2002; Binns, Barriga and Miller, 2007), and one using a 5 m capable seafloor diamond drill to investigate the immediate subsurface at one site (Petersen et al, 2005). An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By A Domanti, C Jewkes

This paper describes the design and constructability issues investigated in the selection of a trenchless solution in comparison to trenched construction options as part of a scoping study for the augmentation of the existing Bulimba Creek Trunk Sewer in Brisbane. Initial work involved the planning of alignment options vis-a-vis ground geology, geotechnical conditions, location and depth of shafts considering potential construction technology, flotation and stability of the tunnel, availability of construction sites and the influence of construction works on neighbourhood properties and the immediate environment. Two design pipe sizes, DN1200 and DN1500, were considered, and factors including jacking forces, specification of product pipes, pipe joints, pipe jacking methods and the associated impacts of ground settlement were carried out. Of particular interest was research on suitable lubricating fluids with the potential to minimise jacking forces and maximise the length of pipeline between launch and reception shafts.

Jan 1, 2008

By S Miller, A Neale

As part of a long-term acid rock drainage (ARD) mitigation study, PT Freeport Indonesia has completed the construction of a highly instrumented, full-scale, experimental, overburden stockpile to further evaluate the behaviour of the waste rock system at Grasberg mine. A total of 24 lysimeters, 30 sets of thermistor strings and 48 oxygen-sampling ports were installed at select locations during stockpile construction. ARD flow rates and chemistry have been recorded since the start of overburden rock placement in April 2000. Measurements of in situ temperatures and oxygen concentrations quantify reaction rates and the oxygen pathways that control oxidation kinetics deep within the waste rock profile. Direct field observations show the significance of advective oxygen flow with respect to the onset of oxidation kinetics. Oxygen measurements show that the rubble zone that forms at the base of a waste rock bench provides a critical pathway for oxygen entry to the waste rock profile. Furthermore, rapid oxidation as evidenced by measured temperature increases deep within the panels of waste rock is observed to occur. The observations presented in this paper provide critical insight for understanding the mechanisms and behaviour of full-scale waste rock stockpiles with respect to ARD generation. The results of this program will assist in the future selection, testing and evaluation of appropriate mitigation measures with respect to surface and face treatments to reduce long-term ARD generation. This project is a work in progress, and at least another two-years will be required to fully understand site-specific ARD generation and ARD mitigation mechanisms. This paper will discuss various design and construction considerations, provide an overview of results achieved to date, and some preliminary interpretation of what is happening within the overburden stockpiles.

Jan 1, 2003

By Coxhead B. A, Brandt B. A

The geological exploration and evaluation of coal reserves involves the appraisal of very large amounts of data. Computers afford an ideal means of handling and manipulating the data, thereby avoiding the laborious and expensive method of manually compiling the logs in full descriptive language. The Minad system of computer storage and retrieval of geological and analytical data is particularly suited to the description of cores and cuttings from exploration drill-holes. The encoded data is arranged in a 120-column computer output sheet format; descriptive geological information in a 54-column geolog and analytical information in a 64-column assaylog. The acquired data is quantitative, uniform and relatively complete and can be selectively retrieved for processing by a wide range of specialized computer programs developed for the coal mining industry. Visual retrieval of data for manual processing is facilitated by the use of simple codes and logical word abbreviations.

Jan 1, 1977

By Muir D

A review of the various methods of degrad- ing cyanide either from gold processing liquors or electroplating baths is presented with some discussion on their relative merits or problems. Whilst alkaline chlorination is common practice in many U.S. and Canadian plants it poses particular problems for certain plants. Alter- native methods include electrolysis, hydrolysis and air oxidation with activated carbon as catalyst which are also integral steps in the carbon-in-pulp process. A basic study of the degradation of cyanide ion has been carried out therefore to determine the effect of temperature, oxygen and carbon. It is shown that carbon is an excellent catalyst for degradation by air and likely to lead to higher losses of cyanide in a C.I.L. circuit. Degradation by hydrolysis is important at high temperatures and high pH such as employed in the Pressure Zadra or Anglo elution processes. Carbon catalysed degradation of cyanide by oxygen in effluent streams may be an environmentally acceptable alternative to conventional chlorine degradation.

Jan 1, 1987

By Ramsay WRH, Morand V

Structural, mineralogical, and textural data from the Tarnagulla Goldfield demonstrate that the area has undergone three significant phases of deformation. The first phase of deformation (Dl) predates the intrusion of the Tarnagulla pluton, which has been dated using K/Ar as 391 ¦ 5MY. We regard this pre-granite deformational event as the major regional deformation. Gold-bearing quartz veins have been deposited in dilational sites on west-dipping reverse faults. These sites demonstrate a geometry related both to faulting associated with Dl and the plunge of the Fl fold axes. This evidence, together with chronology of unmineralised ? D2 and D3 faults, the absence of quartz veining associated with D3 events, and the deformation of carbonate-quartz-biotite-sulphide aggregates within Sl by later S2, lead us to conclude that the bulk of the mineralisation was essentially syn- or late Dl. S'80 values for fluids in equilibrium with vein quartz from Central Victoria have indicated equivocal support for either a magmatic or metamorphic origin. Our evidence supports a pre-magmatic origin for mineralisation at Tarnagulla and hence tends to favour a metamorphic fluid source.

Jan 1, 1995

By Quast K. B

Laboratory batch rod and ball milling tests were conducted on samples of Heavy Medium Separator (HMS) sinks from Renison Tin Limited. The product size distributions for this heterogeneous material were very different to similarly sized homogenous material previously reported by the authors. The effects of pulp density on product size distributions were only evident at pulp densities greater than 80 per cent solids. At high solids density, the major weight distribution product peak fell and broadened indicating less efficient breakage, particularly for rod milling. Tin distribution in the ground products was also affected by pUlp density, and there was always less cumulative per cent tin than cumulative per cent weight, ie there was no tendency for cassiterite to slime down to 10/lm.

Jan 1, 1995

By Chapman J, Kanchibolta S. S Poetschka N L

A field study was undertaken at Marandoo iron ore operations to investigate the effect of blasting on the lump/fines ratio. Three blasts, each in a different ore domain were monitored and the blasted ore was subsequently audited through the tr

Jan 1, 1998

By A. W. CAMERON

Over a 4 hr period of steady plant operation samples were taken at regular intervals from points within the grinding and flotation circuits. Size fractions of each composite sample were analysed for lead and zinc values and a comparison made of the behaviour of the lead, zinc, and gangue minerals, size by size throughout the whole circuit.Analysis of the breakage behaviour using dynamic mathematical models gave the rates of breakage of each size fraction of each main component. Simulated grinding experiments showed that the main grinding circuit had some reserve capacity.In the lead flotation circuit all lead values between 150 mesh (Tyler) and 5 microns had excellent flotation characteristics, and a major proportion had a high rate of flotation which was practically the same for all sizes. Increase in overall lead recovery would require improvement of the flotation behaviour of ultra-fine lead minerals. These were slow floating and were responsible for approximately half the lead losses in the final zinc concentrate and one-third of the lead losses in the final tails.All sizes of zinc values between 100 mesh and 7 microns floated well and the performance of the zinc flotation circuit was mainly limited by the relatively poor flotation of the very fine zinc values. Approximately 60 per cent of the zinc lost to the final tails lay within the minus 7 micron fraction.The overall flotation conditions were conducive to very good selective flotation of the major proportion of the values and limitations in metallurgical performance were mainly due to the properties of the ultra-fines.

Jan 1, 1971

By A D. Paktunc

The surface reactivity of underwater deposited, high-sulfide copper mine tailings was evaluated under fresh and saline water cover conditions by measuring the surface and pore water quality as a function of time. The experiments were conducted in aquarium type lysimeters having a shallow, well-aerated water cover up to approximately 0.25 m over the tailings. Natural lake water was used for the fresh water cover and seawater for the saline water cover scenarios. The tailings showed significant surface reactivity and oxidation under both fresh and saline water cover conditions. The surface water quickly became moderately to highly acidic, and surface oxidation of the tailings resulted in increased dissolution and release of sulfates, iron (total), calcium, magnesium, aluminium, manganese, copper, nickel, zinc, lead, cobalt and silicon to the water covers. A moderate to slightly increased loss of total sulfides, including pyrite, chalcopyrite and sphalerite, occurred in the tailings surface layer to a very shallow depth. In comparison to the fresh water cover, the complete acidification of the saline water cover was delayed by approximately 30 - 40 days because of its additional available alkalinity. Whereas the rate of surface water acidification and release of aluminium and silicon were moderately reduced under saline water cover conditions in comparison to those for the fresh water cover, the release of calcium, magnesium, iron (total), copper, nickel, lead, zinc, sodium and potassium were enhanced. The mass transfer fluxes for dissolved copper, nickel lead, zinc and iron (total) from the tailings substrate to the surface water cover following surface water acidification were higher by 50 per cent or more in the saline water cover than those in the fresh water cover. This release was also reflected in moderate loss of pyrite, chalcopyrite and sphalerite in the very shallow upper surface layer of the tailings at the tailings-water interface, although the loss of pyrite in the surface layer was less pronounced. In both cases, the dissolution of aluminosilicate minerals moderated, to a certain extent, pH and acidity in the water cover.

Jan 1, 2003

By Hainsworth D, Winstanley G, Gurgenci H, Corke P

Past experience has shown that the automation of the dragline swing motion requires real time monitoring of the bucket position. A current project at the Centre for Mining Technology and Equipment (CMTE) is aiming to achieve this using machine vision. The hardware platform is a Datacube MaxVideo 200 system. The images are obtained by a fixed camera installed on the dragline boom. The field of view is large enough to include the bucket in all possible configurations. Standard chain coding and run-length coding algorithms are used to process the video image. The three-dimensional bucket position is calculated by combining the output of the machine vision system with the rope length data obtained from transducers installed on drag and hoist drums. This information is then fed into a control computer which takes corrective action to suppress bucket oscillations before they reach dangerous levels.

Jan 1, 1995

By Chowdhury P. J R, Biswas S. K

Recovery of metallic values from lean-grade raw materials as well as from secondary/intermediate industrial products is of immense importance to a country like India which is not endowed with extensive sources of copper and nickel. The results of a few studies carried out in this area are described in Part-I and Part-II in this article. A novel anode casting system, specially designed for a small copper refinery which had been set up to produce copper wire bars/rods is described briefly in Part-III.

Jan 1, 1992

By Hatcher MI

Exploration undertaken at Copley diapir has located several occurrences of oxidized supergene and primary sulphide copper mineralization at the margin of the diapir or in adjacent country rocks. The mineraliza- tion is related to carbonate-rich epigenetic solutions which moved along major structural features closely associated with the intru sive diapir.

Jan 1, 1975

A major problem in the continuous casting of aluminium killed strip steel is the incidence of black and grey lines in the strip surface caused by the alumina inclusions. One place for limiting the number of alumina inclusions is by providing favourable fluid flow conditions in the ladle so that the inclusions float out to the surface or adhere to the ladle wall. In laboratory equipment 20 kg of steel was melted in an alumina crucible of 14 cm diameter in an induction furnace. Deoxidation was carried out while the melt was constantly stirred by argon bubbling. Bubble frequencies were measured at the lance tip using a microphone technique. High speed cine photo- graphy was incorporated to measure melt top surface velocities. Experimental results indicate that the rate of removal of inclusions is a function of both the gas input and the power input. However due to unfavourable surface area to volume ratio, reoxidation of the melt took place. Some other experimental difficulties in working at high temperatures are also discussed such as lance design, melting arrangement and sampling techniques.

Jan 1, 1984

By Meunier G, Davis J, Koperski G

The dry processing of mineral sands concentrates can result in the generation of significant amounts of airborne dust. The radioactive component of this dust has implications within the context of work environment health codes. The last four years have seen considerable investment in dry plant equipment enclosure and dust extraction systems, with resultant reductions in plant ambient dust levels. Simultaneously, an industry wide program was started to examine the origin, nature, mineralogy and radioactivity of the airborne dust. The major findings of this study have been: ò confirmation that monazite was the only significant source of dust radioactivity. ò recognition of two sources of dust: - agglomerates of finely divided ilmenite-rutile alteration products, which are formed by the removal of surface coatings and particles. - abraded mineral fragments, which reflect the mineralogy of the parent particles.

Jan 1, 1991

This paper reviews the role of fill in mining including consolidated fill both histor- ically and currently as determined by a recent survey of the Fill Subcommittee of the Canadian Advisory Committee on Rock Mechanics (CACRM). It covers the application of fill in modern min- ing methods including mechanized cut and fill, undercut and fill, post pillar cut and fill and longhole pillar recovery between stabilized fill. An automated fill preparation plant and recent developments in rotary drilling of hydraulic fill conducting holes are described briefly. The paper also summarizes the findings of some of the important laboratory and field work carried out on the behaviour of fill in Canada, the United States and Australia and again draws on current information obtained from the Fill Subcommittee of the CACRM. Space limitations and unavailability of suitable material prohi- bit the summary of similar information from other countries.

Jan 1, 1973

By Moon N. T, Torrance A. C

This study has considered the effect of mechanical shock on the resilience of the glass microspheres commonly used to sensitize an explosive emulsion. The damage to the glass microspheres caused by detonating cord, emulsion manufacture and the manufacture of the glass microspheres were considered along with the effect of sensitizer concentration on explosive performance. Reductions of up to 50% in the glass microsphere concentration of an emulsion explosive can result from poor initiation practice, such as the use of high strength detonating cord as downlines during initiation. Laboratory results suggest that detonating cords of strength greater than 3.5 g/metre should not be used as this can seriously affect explosive performance, particularly in small diameter charges. This reduced performance results from damage to the sensitizer elements and recrystallization of part of the emulsion phase.

Jan 1, 1990

By Bell LC

Overburden removal, mining and reclamation are now accepted as the basic operational steps involved in the winning of coal by open cut methods. To attain the lowest operational cost, the recontouring and revegetation of spoilpiles must be planned concurrently with the planning of overburden removal and mining. The earthworks associated with reclamation work on spoilpiles often account for 75 - 90 per cent of total reclamation costs. Experience at Callide Mine has shown that the way that spoilpiles are contoured does influence water retention and can reduce erosion from rainfall run-off. However, provided the recontoured slopes meet'Mines Department specifications, the quality of reclamation work is judged not by the quality of the earthworks but by the plant regrowth on the reshaped surface. Thus it is the quality of the revegetation which is of prime importance. For vegetation to be successful, time must be spent on planned research into methods of overcoming plant nutrient deficiencies and selection of suitable grass and tree species. The research programme undertaken at Callide Mine consists of three stages :- laboratory studies glasshouse trials field trials

Jan 1, 1978