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By I Govender, T L. Moodley

Tumbling mills are grossly inefficient, using only 5 per cent of the total energy supplied for actual breakage. A significant proportion of this inefficiency is unavoidable owing to geometric limitations; rotating drum systems are prone to exhibiting certain regions (energy barriers) that resist particle entry thereby restricting the transfer of energy. Though such systems are inherently inefficient, improved modelling schemes may lead to slightly enhanced efficiency through better microscale predictions of key breakage drivers (stress, force). Central to achieving such incremental advances is the development of a universally accepted rheology for dense granular flows. Armed with a better understanding of these macro-scale ingredients, classical process modelling offers an efficient, spreadsheet friendly framework for recovering the spatial distributions of the comminution drivers. At this real-time level of process control, it should be possible to tune comminution operations towards more energy efficient configurations – the ultimate goal of this research. The present work employs validated DEM data to recover the full continuum field which will ultimately serve as a basis for calibrating process model outputs based on different rheological hypotheses. Such a continuumbased approach captures tensor properties like the shear stress and strain rate – both of which are necessary to developing a dense granular rheology. Moreover, DEM captures this data at the momentum transfer timescale of 10-6 s – no other measurement technique is capable of this level of spatial and temporal resolution. Importantly, the confidence in this DEM data is strengthened because it has been validated at the continuum scale using Positron Emission Particle Tracking (PEPT) kinematic measurements. Validated DEM data is derived from batch experiments conducted within a 300 mm ID laboratory drum using three and five millimetre glass beads at 60 and 75 percent critical speed; such mill speeds are typically encountered in the tumbling mill industry. Dimensional analysis is conducted using critical rheological parameters (shear rate, shear stress, granular temperature etc), which are key to not only developing a granular rheology but ultimately will be used to tune our mechanistic models.

Aug 24, 2022

By Hoberg H, Schneider FU

The stability of suspensions can frequently be controlled only by the use of supplementary polymeric agents. Such methods date back to the time of the ancient Egyptians, who used natural rubber as a deflocculant for carbon black in the manufacture of ink (Anon, EncyclopediaBritannica, 1968). Since the development of synthetic polymers in the 1950s they have been deployed in all manner of applications. Indeed the mining and paper industries as well as industrial or communal waste water treatment plants are largely dependent on flocculants which make a major contribution to the relief of the environment. As some of the polymers used are carried out from the process via purified water, problems can emanate from the application itself as long as no reliable data is available as to the exact whereabouts of the polymers and their impact on the biosphere. In order not to invade other systems, they would have to be biologically degradable which has not, until now, been confirmed (Blockhaus, Sequaris and Schwuger, 1991; Schumann, 1991). It has, however, previously been demonstrated (Hoberg et al, 1990) that when process water circulates in mineral processing operations, residual amounts of polymeric flocculants can have extremely adverse effects on the selectivity of flotation processes. The adsorption behaviour is consequently one of the most important considerations in the development of new polymers, the aim being to minimise the amount of non-absorbent matter. The objective of the investigations carried out on ampholitic synthetic polymers of high molecular weight to be reported on here was to permit the connection between settling index and adsorptivity to be characterised in greater detail. As the level of knowledge concerning flocculation and polymer adsorption in real systems is still limited in spite of numerous practical and theoretical studies in this field, the experiment was designed to be relatively broadly-based. As well as investigating various raw materials, an attempt was made to compile results on the influence exerted by different surface charges.

Jan 1, 1993

By Munro DL

The Mary Kathleen uranium deposit is in north-west Queensland, approximately halfway between the townships of Mount Isa and Cloncurry, at long. 1400 009 E and lat. 200 44' S. The deposit Iwas discovered by prospectors of the Walton McConachy Syndicate early in July, 1954, and climaxed a very intensive ground search by hundreds of part-time prospectors. during the uranium boom from March to July 1954ò Numerous small deposits, mostly in the vicinity of Mount Isa, were discovered in various rock environments, but Mary Kathleen is the only large deposit and, apart from a few tons of hand sorted material from the Milo lease, is the only deposit that has been worked. Exploration of the surrounding area, and proving of the economic worth of the deposit, were conducted from the time of discovery until February 1956 by a geological team camped near the deposit. Proving was carried out by drilling a pattern of vertical and inclined diamond drillholes at fifty-foot centres over the outcrop. An adit was driven eastwards through the deposit. Metallurgical research and design work in the South Australian Department of Mines Adelaide Laboratories were based on core samples and bulk samples from the deposit. The signing of a contract in March 1956 with the British Atomic Energy Authority to supply 4500 short tons of uranium oxide allowed mining to commence, and enabled the planned construction of water supply, township and treatment plant to proceed. The open out mine and plant are now serviced by a modern township, four miles away, which is connected to Cloncurry and Mount Isa by road. Although little field work has been done since the exploration phase, this paper differs in interpretation from a previous paper (Matheson and Searl, 1956) in that it is based on a revised structural inter- pretation (Compana, 1958), detailed mapping of progressive exposures in the open out, and a re-examination of diamond drill cores.\

Jan 1, 1968

By B Banerjee, H Masoumi, X Shen, S Raval, D Tannant

Structural mapping of pit walls can be performed using digital images and photogrammetry software, but the performance is limited by weather and environmental conditions including dust, rain and light. On the other hand, active sensors such as terrestrial laser scanners (TLS) and total stations (TS) suffer from vertical orientation bias and occlusions when persistent discontinuities dip at the same angle as the scanner line-ofsight. The recent development of the compact light detection and ranging (LiDAR) systems has made it possible to mount these sensors on unmanned aerial vehicles (UAVs) or drones which offer the potential to overcome limitations that are inherent in existing mapping systems. This study details the research involving integration and application of an advanced UAV-LiDAR system for structural mapping of a highwall. A state-of-the art laser scanner with an inertial measurement unit (IMU) and real-time kinematic global positioning system (GPS) was integrated on to a UAV. The system was first tested in a laboratory condition. Then the UAV-LiDAR system was employed to map a highwall of a coal mine. The planned flight trajectories tested the system at variable distances from the highwall face and at various speeds. The raw data collected from individual sensors were fused, filtered to remove noise, and segmented to produce a surface scan model. Finally, the point density and surface coverage were measured using the surface scan model of the highwall. The parameters were compared with equivalent measurements computed from a reference TLS data. The study demonstrates the capabilities of a UAV-LiDAR system to generate accurate and occlusion free data for mapping highwall geological structure with very quick and efficient flights in the field. CITATION:Raval, S, Banerjee, B, Shen, X, Masoumi, H and Tannant, D, 2018. Evaluation of a UAV-LiDAR system for mapping geological structures in an open pit highwall, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 496–503 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By D Van Doorselaere

The purpose of blasting during mining is to produce a muck pile that can be efficiently loaded and transported. There is an increasing awareness of the variation in muck pile characteristics and its economic implications. It is well known that good fragmentation by itself is not sufficient to optimise the muck loading efficiency. The swelling and configuration of the muck pile also significantly affect the productivity of the loading equipment. The characteristics of a muck pile depend upon the blast design parameters, explosive properties and rock mass geology. This study has focused on the dependence of muck pile configuration on blast design parameters, explosive properties and size distribution of the muck.The field work was done in two phases. In the first phase 12 blasts were monitored, while in the second, three blasts were monitored. The blast design parameters and explosive properties for each blast were documented and the following muck pile characteristics were measured:muck pile height and its distance from the facedistance of throwwidth of the power troughsize distribution by image analysis technique.The effects of burden, bench height, heave energy of explosive, row-to-row delay, powder factor and the mean particle size of the fragments on muck pile configuration were examined. It was observed that muck pile height and distance of throw are strongly influenced by the burden, bench height, heave energy of the explosive and the size distribution of the muck. The width of the power trough depends upon the row-to-row delay, powder factor and total burden. In addition, the effect of the fragment size distribution on the muck pile parameters has also been discussed.CITATION:Singh, S P and Van Doorselaere, D, 2015. The relationship between blasting parameters and muck pile configuration, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 369–374 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By N S. Rauert

The Barrick Gold Granny Smith underground operation located at the Wallaby deposit is currently in a transition period from a near surface operation in ramp up mode to a fully operational deep mining operation with annual production exceeding 1 Mt/a. A key element in this process has been the project execution of the Wallaby Deeps project from initial scoping study in 2007 to the major production component of the Wallaby operation by 2013.The Wallaby Deeps project serves as an example of how an ongoing detailed study program can be integrated into a day to day mining operation assessing risk and mining application in a perceived challenging narrow vein geotechnical environment prior to mining. A detailed study phase to feasibility level is carried out prior to the mining each zone of Wallaby with mining approval only granted on study completion with full justification.A central element in this process is an optimisation study that utilising the Mineable Shape Optimiser (MSO) and Schedule Optimisation Tool (SOT) software tools developed by AMIRA Ltd PRIMO research project is used to carry out an NPV value based option study. This optimisation process being then tempered to reality by a predefined practicality assessment process utilising extensive peer review by operational and study team members as well as industry experts.Other challenges facing the Wallaby Deeps project include the requirement to maintain the ramp up production profile to full production by 2012 without disruption but with pressures of an ongoing geological resource to reserve conversion program essential for the study process and mining approvals and also development rate achievement.To date these challenges are being met with integrated planning and the value of the study program itself. Production in 2012 year to date is well on the way to annual production rate exceeding 1 Mt/a.CITATION:Rauert, N S, 2012. Wallaby Deeps - from the optimal opportunity to reality, in Proceedings Narrow Vein Mining 2012 , pp 207-214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

It was Harold McMillan, Prime Minister of England 30 years ago, who used the phrase "The Wind of Change" to describe political events in Africa in his day. So well did this phrase capture the spirit of the time that it echoed around the world, and the echo has never stopped. Change is the constant factor in the society in which we live and everyone of us has had experience of the effect which it has had on our professional and personal lives.Change will not stop, it will continue at an increasing rate and the questions we must answer are how do we prepare ourselves to meet the challenge of future change and how do we take advantage of the opportunities which it will bring?It is these questions which I wish to discuss in this address.There is nothing new about change in the mineral industry, it has been happening for thousands of years and it will continue as long as civilisation exists on earth. One type of change is economic and we are all aware of the rises and falls which occur in the prices of metals and minerals (Figure 1). When these have happened in an orderly manner, and could be predicted and planned for, it has been possible to take advantage of the benefits and minimise ill-effects, but when they were sudden and precipitate, and could not be predicted, the consequences were serious. The extreme example, of course, was the oil price shock of the 1970s which had such disastrous effects on industry and society.Other types of change are social, cultural and political. They have all been important in recent years and will continue to be so in the future.But it is technological change which may well be the most important because its effects are profound and irreversible, and alter irrevocably the way in which we live. So in discussing the mineral industry in a changing world I will talk specifically about technological change.

Jan 1, 1989

By P M. Downes

Porphyry-related skarns are common around thePacific Rim. Examples include Cadia and Goonumbla (Australia) Ok Tedi (PNG) and Ertsberg and Grasberg (Indonesia). Although usually treated as separate to the adjacent porphyry copper-gold (Cu-Au) deposit, skarns near porphyry deposits are commonly inextricably part of the larger Cu-Au system(s). Using Cadia as the primary example, we demonstrate that large, zoned, calc-silicate skarns necessitate very large porphyry systems. The Big Cadia and Little Cadia Fe-Cu-Au skarns are associated with the Late Ordovician to Early Silurian high-K calc-alkaline to shoshonitic Cadia Intrusive Complex (CIC). Together, these skarns total ~40 Mt of Cu-Au ore but are much smaller than the adjacent Cadia EastûFar East, Cadia Hill, and Ridgeway porphyry-related Cu-Au deposits. Historically these skarns were large, economically significant and highly controversial deposits. Porphyry-related skarns typically have well-developed calc-silicate and ore zonation. At Cadia, classic skarn zonation has been mapped between Cadia Quarry (proximal) and Big Cadia (distal). Over this 800 minterval, mineralogy trends from: proximal garnet > pyroxene, grading to; fe-oxide-rich skarn; and distal haematite-epidote-rich skarn. At Little Cadia, analogous but symmetrical alteration zonation is present. Big Cadia formed from fluids that migrated laterally within calcareous units and were sourced from strongly altered quartz monzonite phases of the CIC at Cadia Quarry. Isotope studies and mass-balance calculations suggest that prograde and retrograde skarn alteration was caused by magmatic dominated fluids. They also indicate that the mapped alteration system at Cadia Quarry is insufficient to account for the total volume of Fe present at Big Cadia. Despite the typically oxidised nature of many porphyry systems, not all skarns in the porphyry environment are oxidised. Assimilation of carbonaceous sediment by hydrous, alkaline intrusions could lead to reduced Au skarns rather than porphyry deposits. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By D I. Cliff, K Johnstone, N LaBranche

The resurgence of silicosis and coal worker’s pneumoconiosis (CWP) in mining and the recent ban of engineered stone products underscore the need to comprehensively address mineral dust exposures and the associated health hazards. Worker exposure to particulate matter, remains a pressing concern demanding nuanced exploration as all dusts are not created equal. The established link between silica and respiratory diseases necessitates a more detailed understanding of the characterisation of particulates and their health impacts. While current monitoring relies on total mass, it is increasingly evident that the size, shape, mineralogy and agglomeration of particles play a crucial role in determining health impacts. This has been evident in the engineered stone industry with workers not only facing a greater risk of silicosis, but also seeing a faster progression of the disease and a higher likelihood of dying from it. Simultaneously, the surging demand for critical minerals, integral to low-carbon economies, has seen government and industry fast tracking the exploration, mining and processing of these commodities. Critical minerals, crucial in technologies like lithium-ion batteries and high-performance alloys, are central to achieving global environmental goals. Significant funding is currently being allocated to advance the development and processing of these materials, however there remains a considerable gap in understanding potential health risks, urging comprehensive health risk assessments. To tackle these challenges, the University of Queensland has developed innovative dust characterisation methodologies, including the use of the Mineral Liberation Analyser (MLA), a scanning electron microscope, to characterise respirable and inhalable dust samples. This advanced technique, initially applied in coal and metals mining, is expanding to critical minerals mining, unravelling diverse mineralogical components and particle size distributions. This conference presentation will showcase the latest research, emphasising the use of advanced analytical techniques to deepen our understanding of the size, shape and mineralogical composition of particulate matter. By synergising insights from coalmines, metals mines, smelters, engineered stone and critical minerals assessments, we aim to proactively manage health risks, contributing to safer workplaces and responsible production practices in the mining sector.

Apr 16, 2024

By P D. Munro

The spatial distribution of ore with similar processing properties or domains within an orebody may be identified early in the assessment of an orebody to provide a sound basis for later development of the orebody. The assignment of domains in the primary sulfide portion of an orebody is often more difficult than recognition of the oxidised, supergene and related domains usually located towards the top of the mineralised volume. This paper will discuss some approaches to assigning domains within the primary sulfide portion of an orebody. The processing properties of each mining block will be known if the contained domain(s) and their proportions are known. The use of both physical and chemical ore properties to assign the domains is discussed. The domains based on similar processing properties do not necessarily coincide with geological zones assigned by geoscientists. As part of assessing the physical properties of ore, the modal analysis of the ore with respect to the valuable sulfide minerals and the sulfide and non sulfide gangue minerals has to be known, along with the traditionally used elemental assays for valuable and penalty elements. Two scales for determining other physical ore properties will be considered: the mesoscopic scale (examined by human eye) and the microscopic scale (examined via a microscope under high magnification). The strengths and weaknesses of the data obtained at the two scales are discussed in the paper. Broadly, data collected at the mesoscopic scale are much less expensive but the types of data available are more limited. Methods for evaluation of chemical ore properties are also discussed. After establishing a basis for establishing the spatial distribution of domains, variability testing is required to verify the integrity of the designated domains. In contrast, each block of ore in some orebodies has been assessed principally via the results of a laboratory separation on a number of drill core samples or composites from throughout the block, with minimal or no attention to the concept of domains.

Jan 1, 2008

Australia is a highly significant hub in the global minerals business. This paper will present the results of global and national studies looking at the potential 20 to 30 year future evolution of the mining and metals industry.   Globally, the World Economic Forum launched a Mining and Metals Scenarios project in January 2009 to explore the question: 'How will the environment for the global mining and metals industry look in 2030?'. As part of a structured strategic foresight process, eight workshops were held across the world over the course of a year which brought together over 200 leaders from the private sector, government, academia and non-governmental organisations. The workshops were supplemented by personal interviews and guided by an international advisory board.   Critical uncertainties for the future of the industry were identified and compare extremely well with the outcomes of a national survey of AusIMM members identifying the key issues and drivers shaping the future of their operations. Global context was one of the most significant issues identified by The AusIMM membership, which is expanded in the World Economic Forum study in terms of: geopolitics; global governance; action on climate change; and economic outlook. More specifically, this global study developed three divergent yet plausible scenarios describing potential environments for the global metals and mining industry in 2030. These scenarios are compared with ground-breaking global foresight work coordinated by the Stockholm Environment Institute in the 1990s. The scenarios will help decision makers rehearse alternative futures, anticipate potential hazards and identify business opportunities - new solutions, new markets and new connections. The presentation will present these scenarios as a way of challenging thinking, testing established wisdom, and stimulating imagination about the business case for the mine of the future. As Marcel Proust put it, 'The real voyage of discovery consists not in seeking new landscapes but in having new eyes'. This is an ABSTRACT ONLY no paper was prepared for this presentation.

Jun 1, 2010

By D T. Feinstein, M B. Gotkowitz

In Wisconsin, state laws and regulations governing metallic mine permitting stipulate that protection of groundwater quality be assured indefinitely through all phases of the mining project, including development, active mining, reclamation, and long-term closure. By rule, the Wisconsin Department of Natural Resources (WDNR) requires that permit applicants use a numerical model to assist in the assessment of compliance with this requirement for all proposed mine-waste facilities. As a part of the compliance assessment, model calculations are used to predict groundwater solute concentrations through time at designated boundaries for comparison to current groundwater quality standards. In practice, this modelling requirement has involved the application of numerical solute-transport models. Our review of a solute-transport model submitted by the developers of a proposed mine near Crandon, Wisconsin, provides us with an opportunity to assess the usefulness of transport modelling as a permitting requirement. Recent evaluations of solute-transport models by other workers suggest limitations in predictive accuracy. Our review of the model submitted for this project also identified important limitations due primarily to uncertainty in calibration of model parameters at the undeveloped site. The utility of any model to predict project compliance or non-compliance with numerical standards is limited by the range of uncertainty of key model parameters, such as dispersivity and porosity. Uncertainty in the future behaviour of the solute source(s) also reduces the predictive power. Moreover, the site characterisation provided by the model may have limited power to describe the site condition post-development. Although these inherent shortcomings accompany the use of solute transport models at undeveloped sites, the requirement for model development and the ensuing technical review has substantially assisted in our evaluation of site conditions and project design. Through this process we have identified elements of the waste facility design that are crucial to the environmental viability of the project, resulting in modifications to original project proposals. While results from this model review will be used to evaluate compliance, additional benefits come from the identification of critical design features that enhance groundwater protection.

Jan 1, 2003

By P Cameron

Many products and technologies have been developed from outcomes of research projects carried out by the Julius Kruttschnitt Mineral Research Centre (JKMRC). When these products and technologies are applied to the design and optimisation of blasting, comminution and separation, improvements in profitability can be realised. In 1970 Alban Lynch promoted two practical ideas to improve plant operations: Ore and equipment properties can be separated allowing experience with one type of ore or equipment to be transferred to other types of ore and equipment. If this experience was encapsulated in a mathematical model, then these properties could be combined and used to simulate (ie to design and to optimise) complete mineral processing circuits. Many problems associated with scale-up from laboratory to industrial equipment could be eliminated by experimental work on full-scale equipment in the plant. Many JKMRC research projects have focussed on the development of models of unit operations in mineral processing and their application to process simulation. Models of comminution and classification developed at the JKMRC have been used since the early-1980s. Ore characterisation techniques developed to support these models are licensed world wide through JKTech. The application of comminution modelling techniques to blasting, which optimises the process feed size distribution is used in Mine-to-Mill? projects. The advances in the understanding and modelling of froth flotation over recent years have provided the opportunity for integrated ore characterisation and process optimisation from resource to product. JKMRC project outcomes often provide proven opportunities for the mineral industry to improve performance and productivity. JKTech was established in 1986 to commercialise and market the most promising outcomes and thus ensure their continuing availability to the mineral industry. These include: commercial software (JKSimMet, JKSimBlast and JKMetAccount); monographs (Comminution and Blasting); technologies (Mine-to-Mill? and flotation optimisation); and hardware products (JKFrothCam, JKJetLift? and the Mineral Liberation Analyser). This paper summarises these technologies and their benefits.

Jan 1, 2002

By S E. Wallah, D Hardjito, B V. Ran

The manufacture of Ordinary Portland Cement (OPC) is not only energy-intensive but also releases a significant volume of carbon dioxide (CO2) to the atmosphere. In addition, OPC in concrete often causes premature deterioration that affects the durability of concrete structures. This paper explores an alternative to OPC concrete called geopolymer concrete.The present research utilises low calcium (class F) fly ash as the source material to produce geopolymer concrete. Several factors that affect the mix design process such as mix proportion, curing time, and curing temperature have been studied. In addition, the long-term properties such as drying shrinkage, creep, and exposure to sulfate attack are also being investigated.The test data presented in this paper reveal that geopolymer concrete possesses high compressive strength, undergoes very little drying shrinkage and moderately low creep, and shows excellent resistance to sulfate attack. The result is extremely promising and demonstrates the sustainability of geopolymer concrete as a construction material for a sustainable future.

Jan 1, 2004

By J Mauk, J Rowland

The Karangahake epithermal Au-Ag mine consists of two main lodes, the Maria and the Welcome/Crown hosted in Miocene andesites. Mineralisation is strongly constrained to major structures and is genetically linked to dynamic tectonic processes. Two main periods of faulting are represented in the deposit: 1. NE striking right-lateral/normal oblique linked spatially and temporally with the mineralising system, and 2. ESE striking right-lateral/normal oblique post-mineral faulting that displaces the lodes. Paleostress analyses performed on a limited kinematic data set indicate NW-SE extension during the formation of the vein system. Veins and lodes strike NNNE and accordingly contain a strike-slip component. The kinematics of vein formation at Karangahake is broadly consistent with that of other deposits within a NNE-trending belt of deposits. Oblique shear on deflecting structures will create zones of compression and dilation. Dilatant zones created on steep structures create fluid pathways potentially focussing large volumes of fluid from deep parts of the system into dynamic structures.

Jan 1, 2003

One of the responsibilities of the Melbourne and Metropolitan Board of Works is to provide a sewerage system for the metropolis of Melbourne which now contains over 2.5 million people. In providing this sewerage system it was necessary for the Board to embark on a large tunnelling programme some 20 years ago. As a result of this extensive tunnel construction programme, tunnel boring machines and shaft sinking methods have been developed to cope with the soft ground and soft to medium rock found in the southern and eastern areas of Melbourne where the majority of the recent tunnelling has been carried out. While in the last few years radical changes in construction methods have not been made, development has continued and improvements have been made, which have enabled the Board to extend the limits of the ground conditions in which it can efficiently construct shafts and also tunnels with boring Machines.

Jan 1, 1976

By Demin SS

Slow seismotectonic movements along the in-clined deep fault zone under the compressional horizontal stresses are supposed to be the prin-cipal mechanism controlling the structure and processes in the active ocean margins. Within the scope of the plane strain problem a simple 2-D geomechanical model for the evolution of an island arc system is investigated. We consider a homogeneous elastic half-plane with a shea-ring surface crack. The key element of the model is viscous interaction between the crack sides, the viscisity varying with depth. The model dif-fers from the classical steady-state mode of subduction by nonstationary creep processes on deep faults and by possibly cyclical development of the transition zone.A numerical modeling of the stress-strain state within the island arc system through time was carried out using a semianalytical approach. The results of simulation are in good agreement with geological, geophysical, and seismological data.

Jan 1, 1990

By D E. Thorp

The mining and concentration operations of New Zealand Steel have been carried out initially from the Waikato North Head (WNH) deposit since 1969 and subsequently from the Taharoa deposit since 1972. Over the years the WNH operation has produced about 1.2 million tonnes of concentrate which has been converted into steel, while total exports to the Japanese Steel Industry from Taharoa reached five million tonnes in February of this year. Recent expansion plans both in domestic steel production and in the ironsand concentrate export market have made it necessary for the company to look closely at, among other areas, the mineral processing of the titaniferous ironsands in both deposits. This paper deals with the recent test work carried out at WNH and Taharoa on the use of the cone concentrator unit as a primary gravity concentrating unit ahead of the magnetic separation stages and as a cleaner concentrator following the primary magnetic separation.

Jan 1, 1977

By Linge HG, Klauber C

The key element in the carbon-in-pulp process for gold processing is the loading of dissolved Au(CN)2 from solution onto activated carbon. The mechanism and kinetics of this step have been examined by solution adsorption-desorption and X-ray photoelectron spectroscopy for both coconut derived activated carbon and peat-based activated carbon. The results show that these carbon types have the same mechanism and kinetics of adsorption. There is no contribution to the bonding from carbon-oxygen functionalities on the carbon surface, as has been invariably supposed in all previous theories for the mechanism of the reaction. It is shown that Au(CN)Z is reversibly adsorbed intact on and parallel to the graphitic planes of the carbon with the formation of a weak carbon-gold n-donor bond. The kinetic measurement of carbon gold loading reactivity is discussed and use of the Murdoch equation for this test is critically assessed.

Jan 1, 1989

The initiation of cast Pentolite primers by detonating cord has been examined by the combination of two different experimental techniques with computer simulation by the finite element hydrodynamic code DYNA2D. In the first type of experiment, the cord/primer system was placed in a water aquarium, and photographed using a high-speed image converter camera. This highlighted the emergence of the detonation front through the primer surface and the generation of shock waves in the surround- ings. Numerical simulation was used to interpret the experimental record, establishing where the cord had induced buildup to detonation inside the primer. The second experiment used the plate dent test, where the primer was placed in contact with a block of metal (here aluminium), with the resul- tant dent in the metal surface being a measure of primer output. Detailed numerical simulation of this test confirmed that the observed dent was caused by the development of a complex series of shock waves inside the Primer.

Jan 1, 1988