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By Reeve JS

Heap leaching is a low capital cost alternative to conventional processing techniques for gold recovery from areas that contain small gold particles in a porous host rock.For successful heap leaching the ores to be leached must maintain good permeability after being stacked into heaps so that the leach solutions can percolate evenly through them.The presence of clays, slimes or excessive amounts of fines can hamper the flow of leach solutions causing channelling and producing dormant or unleached areas within the heaps. This results in unreasonably long leach periods and poor extractions. In extreme cases the clays or fines completely seal ore heaps, causing leach solutions to run off the sides of t'he heaps rather than penetrate the ore.The Northern Queensland Company uses the Agglomeration Heap Leach technique (AHL) to overcome the difficulties associated with clays or fines. This technique involves cementing the fines, by using readily available binders, into a rigid, porous network that greatly enhances uniform flow of cyanide leach solutions through the ore heaps.

Jan 1, 1986

In the consideration of coal resources in this country one of the most neglected aspects and perhaps one of the most important is that of the geologic controls on coal formation. The composition, properties, thickness and distribution of the coal are all determined by geological factors. The extent and amounts of coal to be found in the South Auckland area have great economic significance, and are in the main considered here. Upheaval of the New Zealand geosyncline during the Rangitata Orogeny produced a system of parallel, north-south trending basement ridges and basins in the South Auckland area. A subtropical climate and relative tectonic stability allowed deep weathering of these mesozoic greywackes in the late Cretaceous and early Tertiary. Such weathering, markedly reduced the landscape relief, and provided vast supplied of very fine detritus for later sedimentation as the Waikato Coal Measures. This coal measure phase marked the beginnings of Tertiary  sedimentation in this region and represented a change from a sub-aerial weathering regime to a fresh water swamp environment.

Jan 1, 1976

By K Ellis, K Quast, R Newell

The use of ammonia as a leaching agent in the recovery of copper from ores and concentrates has a number of potential benefits. These include the ability to treat ores with an acid consuming gangue, non-corrosivity, the insolubility of iron in the solution and increased selectivity. This paper reviews the previous and current use of ammonia based leaching systems for copper recovery and presents the results of a laboratory investigation that involved leaching of a copper concentrate and a low-grade ore. The effects of the operating variables (particle size, oxygen addition, agitation and temperature) are discussed. Of these, the particle size had the greatest effect, with decreasing size giving improved leaching rates and recoveries. The possibility of using ammonium salts in heap leaching is also discussed, and the results of some small-scale column leach tests presented. Possible methods for recovering the copper from the leach solution are outlined, and the types of ores and concentrates for which ammonia leaching may prove to be a viable alternative processing route are discussed.

Jan 1, 2000

By Ward S. D

When using grinding time for a batch grinding operation as a measure of the energy usefully employed for comminution; the assumptions made are often not valid. A kinetic approach, based on a study of the rate constant, or k, value for the material is more acceptable. The Rosin-Rammler distribution equation has been theoretically derived from the general equation for first-order batch grinding. This relationship, incorporating a term for k, was used in a study of the rod milling of a binary mixture of quartz and limestone.The presence and degree of interaction between the components was considered by comparing the size distribution of the mill product with that predicted by assuming the overall distribution equal to the sum ofthe distributions given by the Rosin-Rammler equations for each component weighted according to its volume fraction in the mixture. The interaction was found to be complex and particularly sensitive to particle size.A simple graphical procedure was devised to predict the size distribution of the mill. Product components and this gave a fairly good approximation to experimental data.

Jan 1, 1976

By Liu H, Chen S

Natroalunite is one of colouring minerals in kaolin. In this investigation, natroalunite, on which Ca(II) was adsorbed, was flocculated by HPAM and kaolin was depressed in suspension. The adsorption of Ca(II) on the natroalunite surface was studied by zeta-potential measurement and Auger Electron Spectroscopy analysis. Ca(II) was adsorbed more on the natroalunite surface than on the kaolin surface. The mechanism of Ca(II) adsorption was considered to be chemical adsorption on natroalunite and to be physical adsorption on kaolin. It has been found that Na6P6O18 and Na2Si04 can strongly affect Ca(II) adsorption on the surface of kaolin, but weakly on the surface of natroalunite. The effects of degree of hydrolysis and the molecular weight of HPAM, the effect of pH and the effect of Ca(II) have been studied. The kaolin ore, containing SO3 1.05 per cent has been processed with this method. The products only containing S03 0.36 per cent and the weight ratio of concentrate 52.27 per cent were Obtained.

Jan 1, 1993

Gold bearing sediments at Scotland Point occur within the Quaternary Gibbston Fonnation, which underlies Cromwell Flat in Central Otago. Gibbston Fonnation unconformably overlies Teniary Manuherikia Group clays, sands and quartzose gravels. Gibbston Formation sediments are composed of a texturally diverse, multistoried lithostratigraphic succession of sandy/gravelly/bouldery lithofacies, deposited within a multiple channel (braided) depositional environment. Lithostatigraphic analysis indicate an upward overall decrease in average grain size, reflecting a concomitant reduction in stream competence. This trend results from progressive channel abandonment as major distributaries avulse across the outwash plain. Grade distribution of alluvial gold is controlled by aggradational and to a lesser extent degradational lithofacies deposited as distinctive braid bar forms near the base of the sequence. These lithofacies were deposited at different topographical levels on the outwash apron, under variable hydraulic conditions. Recognition of large-scale auriferous bedforms within the braid bar depositional system coupled with an understanding of lateral facies relationships, allows headgrade control on run of mine ore and quick determination of overburden to ore ratios.

Jan 1, 1988

For decades strip mining with discon tinuously operating 'draglines and shovels has been the most economical operation method in the shallow hard coal opencast mines of Aust- ralia, North-America and some other countries. Continuously operating equipment such as bucket chain excavators and bucket wheel excavators in combination with conveyor belt systems, conveyor bridges and stackers had been deve- loped in Germany; during the last 25 years this type of equipment has been further developed in order to allow a high degree of rationaliza= tion as to opencast mines in unconsolidated overburden in Germany, in many European couh- tries, in India and in Victoria. The differing compactness of the layers to be mined, the increasing mining depth, the adverse over- burden to coal ratio and geotechnical con- ditions account for the combined use of con- tinuously and discontinuously operating equip- ment and systems. This paper is to demonstrate some projects showing the combination of continuously and discontinuously operating equipment which aims at optimizing opencast mine operations. It will be reported on the following combinations: - combined use of bucket wheel excavator/

Jan 1, 1981

Australia has historically been a world leader in mining innovations. This trend is reflected in the international patent records, which show that in recent years there has been some recovery in the number of patent filings arising from Australian research. These innovations occur across a wide cross-section of mining technologies and derive from both public and private sector research. Australian mining innovations are largely dominated by new processes and equipment, principally in the areas of rock drilling and coring, strata stabilisation, cutting tools, blasting, mine design and oil field exploitation. They include improvements in drill bits, rock bolts and accessories and wellbore systems. Another area that has received significant research attention has been the in situ thermal processing of coal deposits. High profile examples of Australian mining innovations include the æSORDMinerÆ, a remote-controlled mining machine for use in mining collapsing wet environments, and CSIROÆs SMART*CUT rock cutting pick that dramatically increases the rate of cutting hard rock. This paper will provide an overview of recent innovations in Australian mining, as reflected in the international patent records, including the organisations and individuals active in the field, and the technological nature of specific innovations.

Jan 1, 2008

By M A. Mular, T Akroyd

A fundamental model, which considers the subprocesses of particle collection by bubbles in flotation, is applied to two comprehensive flotation surveys in the rougher stages of C3 concentrator, PT Freeport Indonesia. The flotation surveys focused on the collection of: cell-by-cell and size-by-size metallurgical, cell hydrodynamic, and pulp and surface chemistry information.The two surveys were conducted at significantly different feed tonnages, giving rise to significantly different feed particle size distributions, pulp densities and mean pulp residence times. A series of model simulations are performed with the aim of quantifying changes in copper recovery, on both a size-by-size and unsized basis, with changes in values of the hydrodynamic parameters and hydrophobicity of the copper sulfide mineral. This was carried out in an effort to identify the most promising route to increase overall copper recovery in roughing. It was found that by increasing the hydrophobicity of the copper sulfide mineral surfaces it became possible to optimise cell hydrodynamics, which targeted increased fine (-12 ¦m) copper sulfide mineral recovery but without adversely affecting coarse (+150 ¦m) copper sulfide mineral recovery.

Jan 1, 2007

Near Kangiara in south eastern New South Wales, Australia, a number of polymetallic (copper, lead and zinc, with minor silver and gold) mineral deposits occur within a relatively broad volcanic rock belt, intercalated with limestones, sandstones and shales, of Silurian age. The Kangiara deposit was the most significant for the region.Adjacent to the Kangiara deposit, the unaltered country rocks are more rhyolitic than elsewhere in the volcanic rock belt, and the mineralization is accompanied by silicification, chloritization, sericitization and argillization. The host rocks typically contain a higher K20:Na2O ratio than the volcanic rocks not associated with mineralization.In the Kangiara deposit the mineralization consist of massive (in part banded), fragmental, disseminated and vein-type copper-lead-zinc ores, with the massive and fragmental types divisible into pyrite-rich, chalcopyrite-rich and sphalerite-galena-rich varieties. With respect to this mineralogy, the ore textures and sulphur isotope compositions the deposit can be compared to the stratiform mineralization associated with Silurian acid volcanic rocks at Woodlawn, Captains Flat and elsewhere in the Lachlan Fold Belt, as well as the Tertiary Kuroko deposits of Japan.

Jan 1, 1990

By G Huggins

Excavation in underground jointed rock masses creates cavities into which the surrounding rock mass deforms. Deformations, besides intact rock deformation, include mechanistic deformations such as slip and rotation. In this paper deformational moduli were measured for prototype and blocky (jointed) models using elastic analogue methods for stopes from MIM LimitedÆs Lead Mine. The blocks for the models were defined in terms of the prototypeÆs joint sets, their spatial separations, orientations and average friction characteristics. From dimensional analyses, a relationship between prototype and model deformations was used to predict stope mid-span deformations. The results of this physical modelling work, conducted in the 1970s, motivated an investigation into the electro-treatment of tailings backfill to achieve improved strength and stiffness characteristics. Tailings backfill containing fines and having a high clay content can be electrically dewatered, and at times grouted, cemented, ion exchanged or agglutinated, to achieve relatively high magnitudes of strength and stiffness. These treated tailings stiffnesses can reduce the deformation magnitudes within a rock mass and, in doing so, reduce problems encountered in mine pillar extraction. The application of these tailings modification techniques is examined in relation to the elastic analogue methods.

Jan 1, 1998

By E U. Petersen, D R. Cooke

Hydrogen and oxygen isotopic constraints on hydrothermal fluid composition from the Pliocene Boyongan and Bayugo porphyry copper-gold deposits (southern Philippines ) reveal mixing of magmatic and sea water reservoirs as the hydrothermal system evolved. Magmatic-equilibrated fluids (d18O: +8.3ë to +9.1ë; dD: -61ë to -51ë) are represented by hypersaline brines implicated in copper-gold transport and deposition. These dominate the fluid inclusion assemblage in early comb-quartz (unidirectional solidification textures), miarolitic quartz, and in K-silicate-stage quartz-K-feldspar ¦ biotite veins. Fluids responsible for post-K-silicate alteration assemblages of pyrite-clay (illite, pyrophyllite and kaolinite), alunite and smectite are represented by low-moderate salinity two-phase inclusions in co-existing quartz. These are interpreted as mixtures of evolved magmatic fluids (d18O dD: -42ë to -20ë) with evolved Pliocene sea water (d18O: + 4.0ë; dD: +4ë). The isotopic evidence for sea water involvement in the hydrothermal system suggests that porphyry emplacement and associated diatreme formation could have occurred in a submarine setting. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Duke J. H

Advanced computer aided geological modelling techniques are now available to the geologist to allow the rapid evaluation of a gold orebody at various stages of its development. The types of grade estimation techniques used change during the various stages as the density of drilling and knowledge of the deposit increases. At the prospect evaluation stage drillhole intercept selection techniques are coupled with preliminary 2D (vein or layer) modelling or 3D block modelling techniques to arrive at a geological resource estimate. At the prefeasibility and feasibility stages more sophisticated 2D and 3D modelling techniques, such as domain controlled grade interpolation with anisotropy, are used along with interactive open pit and underground mine design, to calculate recoverable reserves. At the production stage closely spaced blasthole sample data is modelled quickly and coupled with interactive grade control facilities. Shot volumes, tonnages and grade estimates can be databased to provide reconciliation figures. These modelling techniques are embodied in MINEX-3D, an Australian software system which, with the emergence of the 386-based PC and high resolution (VGA or better) graphics, makes a whole range of advanced geological modelling techniques available to most exploration and mine geologists.

Jan 1, 1989

By J Palaci, M MelTndez, F Parra, I Rojas

At the Huasco Pellet Plant of Compa±fa de Aceros del Pacffico, Chile, the production of iron concentrate suitable for pellet feed from a low-grade iron ore was technically evaluated. In this study, three treating schemes including comminution, magnetic concentration and flotation in pneumatic cells were tested. The best results were obtained at the laboratory scale by flotation technique using Lilaflot D 817 M as the collector without using any depressant. The operational parameters were determined including pneumatic flotation, and three circuits, two including magnetic pre-concentration, with the low-grade iron ore. The best results were obtained by size reduction at 80 per cent under 325 Tyler mesh, three steps of magnetic concentration and three steps of flotation in pneumatic cells. The magnetic concentrate contained 63.02 per cent of iron and 6.6 per cent of silica, and after the pneumatic flotation the iron content increased up to 70.18 per cent and silica decreases to 1.07 per cent with 78.78 per cent of iron recovery at a weight recovery of 31.89 per cent. Therefore, it is possible to use low-grade iron ore to produce pellet feed from magnetic concentrates by using reverse iron flotation in pneumatic cells.

Jan 1, 2005

By C Chen, W J. Bruckard, F R. A Jorge

The base metal industry mines and processes hundreds of million tonnes of ore per annum to produce saleable products and large tonnages of waste by-products such as tailings. These ores usually contain less than 1 wt per cent of toxic elements (As, Sb, Bi, Cd, Se, Te, Hg, etc), which are subsequently treated with the other components in the ore during the production of concentrate through to saleable metal products. The deportments of minor elements across the various unit operations of a process flow sheet do not normally receive the attention that the major elements receive. However, these minor elements can have a major influence on the quality of the products as well as an economic and environmental impact. Therefore, a high degree of control over their deportments is a key step in reducing their dispersion in the biosphere. Ongoing work at CSIRO has been examining minor element deportments across unit processes used for smelting and refining and the options for early removal of minor elements, as well as methods for safe disposal of some toxic elements. This paper provides an overview of the R&D activities undertaken at CSIRO to develop tools and methodologies for improved management of minor elements during the processing of sulfide ores.

Jan 1, 2006

By R P. Langford, T A. Moore

Over the last 15 years Indonesia has experienced a surge in coalexploration, which has led to the development of a major export industry. This coal exploration has improved the understanding of the geology of the Indonesian coal deposits. The main economic coal deposits are of Eocene and Miocene to Pliocene age, which mainly occur in Kalimantan and Sumatra and were formed from peat deposits in an equatorial paleoclimate similar to that prevailing today. Some of these peats were domed peats, which grew above the normal water tables, under a climate of year-round rainfall; these peats grew above the level at which waterborne mineral matter can enter the system, resulting in low ash and sulphur, and locally very thick coal. It is believed that such peats have formed the unusually thick, low ash, and low sulphur Miocene coals of Indonesia. Coal deposits of Eocene age are typically characterised by thinner seams, with relatively higher contents of ash and sulphur. The Miocene coals and Eocene coals both appear to have formed in lacustrine, coastal plain or deltaic depositional environments, similar to the modern peat-forming environments of eastern Sumatra and parts of Kalimantan. The Eocene coals formed mainly in extensional tectonic settings. Miocene - Pliocene coal deposits formed in a range of tectonic settings.

Jan 1, 1999

By Gadd D. E

Since October 1972, New Zealand Steel Mining Ltd has loaded around 10 million tonnes of ironsand concentrate from single-point mooring buoys located off-shore at Taharoa on the west coast of the North Island of New Zealand. Before the first off-shore loading system was installed a considerable research effort was applied to proving the slurry loading technique. Subsequently the system has been expanded and a new buoy, pipelines and pumping system were installed in early 1978. Since then 110,000 DWT class ore carriers have been loaded at rates of around 2600 tonnes per hour through twin submarine pipelines. This paper reviews the operation of the shiploading system and attempts to answer the question: "If the Taharoa operation were to be planned in 1980, would the same research spending be necessary or have published research results since, made such practical tests unnecessary?".

Jan 1, 1980

By Cusack BL

The addition of cement to underground backfill at The Zinc Corporation, Limited and New Broken Hill Consolidated Limited, Broken Hill commenced in 1967. This resulted in a deterioration in metallurgical performance with increased loss of lead and zinc to residues at each concentrator. Investigations to determine the cause of the problem and methods to counteract it have been undertaken. This paper outlines the effects of cement on lead-zinc beneficiation at Broken Hill and presents an interim report on attempts to overcome the metallurgical Deterioration.

Jan 1, 1970

By R van Berkel

Regional synergies concern the capture, recovery and reuse of by-products, water and energy between industrial operations in close proximity. The Centre for Sustainable Resource Processing (CSRP) undertakes applied research to further advance regional synergies in the Kwinana Industrial Area in Western Australia in order to achieve greater efficiencies in water, energy and materials consumption and reduction in waste and emission generation. The Kwinana Industries Council (KIC) and its member organisations recognise water consumption and disposal as key environmental issues. Some 30 companies in Kwinana consume a total of more than 35 000 ML/yr of fresh water. Over the past years significant progress has been made towards the reduction of water consumption and improvements in effluent disposal. As part of the CSRP Kwinana Synergies Project, water balances for the ten major water consuming companies have been completed, including workshop sessions with company staff on water synergy opportunities. This work resulted in a set of synergy opportunities which are currently being pursued. In parallel to the Kwinana project, the CSRP has commissioned a supporting project that delivers a toolkit to guide a more targeted and less resource intensive way to identify feasible water synergy opportunities. One of these tools focuses specifically on water, and takes count of input and output water flows within a given industrial area to deliver listings of prioritised water synergy opportunities. This paper discusses the water mapping and workshop approach taken in Kwinana and its outcomes, which are to identify and evaluate water synergy opportunities. The results from the trial application of the developed Regional Eco-Efficiency Opportunity Assessment Toolkit are also presented.

Jan 1, 2006

The Department of Conservation (DOC) manages public conservation land throughout New Zealand in terms of section 6 of the Conservation Act 1987. In brief, this requires DOC to manage the natural and historic resources of the land; promote the benefits of conservation to present and future generations; provide information about conservation; to foster recreation on the land; and allow for its use for tourism.   Locally the department's Tauranga Area Office manages approximately 60 000 hectares of Conservation Park (known as the Kaimai-Mamaku Forest Park) which includes early gold mining relics and former bush tramways associated with the logging and the mining industries. The Department has recently developed the Kaimai Heritage Plan which seeks to restore some of the relics and encourage involvement by the local communities in the restoration and interpretation of their history in the hills. It provides a unique opportunity for the Department to help bring alive for New Zealanders an important, and often overlooked, part of our history as a nation in a stunning natural setting.   The purpose of this presentation is to: +        display the endeavour and ingenuity of the early miners and loggers, the relics of those industries and the dramatic environment in which they worked; +        identify the linkages between those early industries and gold mining today; and +        promote a co-operative approach to heritage and recreation management involving all facets of the community.

Jan 1, 2006