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By M Schaffer, T Kewe, N Moffatt

Porgera mine is 95 per cent owned by Barrick Gold Corporation. It is located at an altitude of 2200–2700 m above sea level in the Enga province of Papua New Guinea and produces approximately 460 000 oz per annum with a proven and probable reserve of 6.2 Moz. The refractory ore is ground in a conventional semi-autogenous grinding and ball mill circuit. After the gravity gold is recovered, the slurry is floated, oxidised in the autoclaves and then leached. This paper will focus on the flotation circuit and the recent upgrade of the control system. The five interdependent flotation circuits were challenging for operations to control as they dealt with variable grade, throughput and circulating loads, as well as the physical limitations of the equipment. With the installation of 18 Portage Froth Characterization® (PFC) cameras, the plant’s operation has been converted from a level-control based strategy that was focused on individual cells to one that targets grade and recovery control across the entire circuit. Variability in feed and the corresponding launder issues were addressed with a unique site initiative of deflector plates to indicate filling level. Non-linear closed loop control was implemented directly in the DeltaV Distributed Control System (DCS) using Portage Advantage Regulatory Control (PARC) algorithms and optimised with AwaRE advanced controllers. The most noticeable benefits achieved with the upgrade include improved flotation gold recovery, consistent flotation sulfur grade and autoclave performance. Correspondingly, there was a significant drop in boiler diesel fuel usage and launder overflow conditions.CITATION:Kewe, T, Moffatt, N and Schaffer, M, 2014. Porgera flotation circuit upgrade and expert system installation, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 345–356 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

Effect of Anionic Surfactant on Silica Particle Attachment at the Oil-Water Interface Controlling particle attachment is crucial where powdered solids come into contact with oil and water. Particles are trapped in a deep energy well at the oil-water interface, stabilising emulsions. Here it is shown that adding anionic surfactant causes dramatic changes to the bulk and interfacial structure of silica particle-stabilised oil-in-water emulsions. Exposing particle-stabilised drops to surfactant concentrations above the critical micelle concentration enhances the rate and extent of creaming and flocculation. Mixing particle-stabilised emulsions with surfactant solutions causes drop fragmentation. As the surfactant concentration increases, the average drop size decreases and particles are displaced from the interface during the mixing process.

Sep 13, 2010

By C E. J de Ronde

Most of the world's economically significant volcanogenic massive sulphide (VSM) deposits are considered to have formed in submarine arc and backarc settings. While the Kermadec-Tonga arc is an excellent example of an intra-oceanic arc setting, it remains largely unexplored in terms of submarine mineral resources. More than half of this arc (~1400 km of the >2500-km-long feature) lies within the EEZ of New Zealand, where it is defined by at least one sub-aerial and 33 submarine volcanoes. The NZAPLUME (New Zealand American PLUme Mapping Expedition) cruise of March 1999 provided a systematic assessment ofhydrothermal activity on the southernmost 13 submarine volcanoes along the southern Kermadec arc. Using prospecting techniques based on the physical and chemical detection of hydrothermal plumes, we discovered that more than half (7 of 13) of the southern Kermadec volcanoes host one or more active hydrothermal systems at depths ranging between <200 to 1800 m. Chemical results show that the fluids discharged are compositionally diverse among volcanoes and between sites at a single volcano. Plumes over more than half of the volcanoes are gas-rich (He, CO2, H2S) relative to mid-ocean-ridge (MOR) plumes. In addition, most sites are highly enriched in Fe, yielding Fe/Mn values that far exceed those for MORs. One interpretation consistent with these observations is compositional overprinting by addition of magmatic fluids, which are typically highly enriched in gaseous and ionic components. Regardless of the source, it is clear that the ligands (HS-, Cl-) required to efficiently transport base (e.g. Cu, Zn, Pb) and precious (e.g. Au, Ag) metals to the seafloor are abundant in Kermadec arc fluids. We conclude that modem analogs of VMS deposits are likely forming at multiple sites along the Kermadec arc and within the EEZ of New Zealand.

Jan 1, 2000

Computation is believed to be a powerful tool in scaling-up chemical processes and in designing materials, however, is being challenged by low predictability and limited scalability. This presentation will discuss the promising future of multi-scale computation in solving these two problems to realise the real-time simulation of industrial processes. Multi-scale structures are a common nature of most chemical systems and the meso-scale phenomena are believed to be the road blocks not only in improving the predictability of physical modeling but also in extending the scalability of computation. Focusing on the meso-scale phenomena, a series of research has been carried out at the Institute of Process Engineering, Chinese Academy of Sciences, for the past three decades. Starting with a simple idea of modeling the meso-scale clusters in gas-solid two phase flows, the so-called EMMS (Energy-Minimisation Multi-Scale) model was established. In verifying the stability condition of the model, the pseudo-particle approach was proposed to explore the micro-mechanisms in particle-fluid systems, and the strategy of the EMMS model was extended to other six different multi-phase systems, resulting in a unified conceptual formulation of multi-phase complex systems expressed by a multi-objective variational problem. In applying this model to different multi-phase systems and to industrial problems, it was recognised that the EMMS model defined a new paradigm of multi-scale computation by realising the structural similarity between software, hardware and the problems to be computed. This paradigm of computation was implemented on a multi-scale supercomputer with a capacity of 1.0 petaflops by integrating CPUs and GPUs (Graphic Processing Units), showing high efficiency and low cost. Running the EMMS model on this computer, the simulation of hydrodynamics of multi-phase systems can be speeded up very much, indicating a promising future of virtual reality of process engineering. The presentation will review this series of work, introduce successful applications in industries, and will be concluded by emphasising the critical importance of the meso-scale phenomena as the bridge between macro-dominants and micro-mechanisms. This is an ABSTRACT ONLY. No full paper was prepared for this presentation.

Sep 13, 2010

Old Copper Flotation Tailings Waste Reprocessing

Sep 13, 2010

Commercialisation of Ni Heap Leaching at Murrin Murrin Operations

Sep 13, 2010

Generation and Attachment of Submicron Size Bubbles to Colloidal Solids

Sep 13, 2010

By M P. Cipold, J F. Bachmann, C C. Bachmann, J Ha

Knowledge of fuel qualities is of ultimate importance for the efficiency of chemical plants or power stations. Although most blending yards are equipped with automatic samplers and the derived samples are processed in the laboratory, the quality variation of the blended product may still be strong. This is caused by several reasons. First of all the process of sampling, crushing, dividing and analysis is time consuming. Results are available only with a delay of two to 24 hours. During this time blending is operated without knowledge of the main parameters. Conveyors with high throughput require expensive sampling systems capable of handling samples which are representative. The frequency of sampling needs also to be high in order to be representative. This results in high maintenance costs and also downtime of the sampling system.Online analysis of bulk materials has matured over time and today it can supplement but not replace laboratory analysis. As an example, J&C Bachmann has realised a coal quality monitoring system on the coal supply of a South African coal processing plant. The plant consumes ~42 Mt of coal per annum. The blending yard consists of two sets of three heaps where coal of six different mines is blended according to the factory’s requirement. From there, the blended coal is fed to the factory on two different belts.In 2010 the plant installed a TEXAS X-ray fluorescence analyser as a trial. It was tested under different conditions on several belts before the customer decided to install six TEXAS analysers on the feed belts to the stackers and two more analysers on the reclaimer belts. All analysers are installed directly on the belt and not on a substream.During the test period blending strategies were developed in close cooperation between the customer and J&C Bachmann. The use of the analysers in conjunction with the blending model has proven that the variation of the reclaimed coal quality was decreased significantly, which results in increased process performance and significant cost savings.CITATION:Bachmann, C C, Bachmann, J F, Cipold, M P and Ha, J, 2017. Online quality control of a coal blending yard, in Proceedings Eighth World Conference on Sampling and Blending , pp 125–128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

During an eight month period, January to August 1978, nine bore holes were drilled in the Mikonui River gravels. On account of two rebores required from near bottom, the number of bores is in effect 11. Just on 1300 feet were drilled with an average depth of 120 feet. Depth varied from 102 feet to 133 feet. Penetration on average per hole value, varied from 7.4 to 16.4 feet per day. Gold values were even more erratic. Drill rig used was the Keystone churn drill manufactured locally by the Dispatch Foundary. It is skid mounted and requires a crew of two persons.

Jan 1, 1979

By K G. van den Boogaart, M Lehmann, U Mueller

Geometallurgical parameters are descriptions of the mineralogy and microstructure of the ore determining its mineralogical and microstructural characteristics. From a conditional geostatistical simulation of such properties, a processing model can compute recovery, equipment usage, processing costs, and thus the monetary value for mining and processing a block with certain processing parameters. The output can be used for optimising mining sequences or finding optimal processing parameters by solving the corresponding stochastic optimisation problem.The approach requires two properties of the simulation not provided by established geostatistical techniques:Many relevant geometallurgical parameters are from non-Euclidean statistical scales such as (mineral) compositions, (grain size) distribution, (grain) geometry, and (stratigraphic type) categorical, which might produce nonsensical values (for example, negative proportions, negative facies probablities, planar grains) when simulated with standard geostatistical techniques.Due to the nonlinearity of processing, the entire conditional distribution of the geometallurgical parameters is relevant, not only its mean and variance. The geostatistical simulation needs to reproduce the joint conditional distributions of all the geometallurgical parameters.The multipoint conditional geostatistical simulation technique discussed here allows for jointly simulating dependent spatial variables from various sample spaces. The technique combines an infill simulation, similar to the one used in multipoint geostatistics, with a new form of distributional regression to estimate conditional distributions of arbitrary scales from different information sources, including training images, training models and observed data. The distributional regression is based on a generalisation of logistic regression and is related to both Bayesian Maximum Entropy geostatistics and high order cumulants.The method ensures that simulated data reside in the set of possible values and honour the characteristics of the joint distribution to be reproduced. The computational effort is substantial, but affordable for a useful application with standard problems: from processing-aware block value prediction and block processing optimisation as shown in the test application to a mathematically completely defined simulated model situation with a complex processing model.CITATION:van den Boogaart, K G, Tolosana-Delgado, R, Lehmann, M and Mueller, U, 2014. On the joint multipoint simulation of discrete and continuous geometallurgical parameters, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014, pp 379–388 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

Gold was first discovered in the Shotover by Thomas Arthur in 1862. He left his job as a shearer and soon there were up to 3000 miners working over the length of the river. Some parts were extremely rich and a few early miners recovered as much as 300 ounces in a day. From these early days of hand working the operations progressed through to hydraulic elevating once water races and pipes were installed after the Skippers road was completed about 1890. The riverbed was worked in paddocks with .the gravel being sluiced to a central suction which elevated the material over a sluice box. Use of this system continued intermittently through until 1977 when Joe Schieb retired û the last of the hydraulic miners. Many bucket ladder dredges worked on the lower Shotover near Big Beach where the Sew Hoy family recovered a lot of gold. Just after 1900, at least three worked further upstream, one on the beach where Shotover Jet now operates and one further up below the Moonlight. All the sections for this were transported in over the Moonlight Track and the boiler, steam engine and bucket ladder are still sitting at the edge of the river. up near Maori Point a dredge operated from Dredge Slip upstream. Records are poor on these dredges but they all suffered from the frequent floods and large boulders which damaged the bucket line. The last dredging attempt was about 1930 when a suction dredge was constructed on Maori Beach. This failed as seems to be normal for most suction dredging ventures. The river can drop to very low levels in the middle of a dry summer, and in winter when the water is tied up in the mountains as ice and snow. During 1863 when heavy rain melted snow in the high country, the river rose 35 feet overnight and drowned many miners camped on the banks. The ever present risk of flooding dominates the method of working and plant design.

Jan 1, 1987

By R M. Briggs

Kapowai Caldera Complex (KCC), located 10 km west of Tairua (eastern Coromandel Peninsula), is a late Miocene composite collapse caldera, formed during eruption of several small and large volume andesitic rhyolitic ignimbrites. Numerous epithermal Au-Ag mineral deposits and associated alteration zones at the KCC are related to caldera (rhyolite lava domes, intracaldera faults) or regional structures (faults). The main epithermal deposit exposed in the central KCC is associated with an E-W striking structural boundary fault that cuts the Welcome Jack rhyolite dome. Propylitic (calcite - chlorite) and sericitic (quartz - sericite) alteration haloes surround this deposit. Sporadic zones of sericitic alteration are also exposed within and on the margins of the Bulls Run rhyolite dome complex. Epithermal systems post-dated emplacement of these rhyolite domes, but were controlled by them. Propylitic alteration of ignimbrite in the floor of the Kapowai and Kauaeranga valleys is related to the major NE-trending Kapowai Fault which extends SW to south of Thames. Alteration along this fault pre-dates alteration associated with the rhyolite lava domes. Numerous sericitic and propylitic altered welded ignimbrite, rhyolite and andesite lava lithic fragments have been sampled from intracaldera ignimbrites, and although no direct source is known, they infer the presence of buried epithermal systems. Repeated epithermal activity at the KCC is inferred by the exposed epithermal deposits/alteration zones and the older buried geothermal systems. Silicic caldera volcanoes are considered to be critical volcanic environments for epithermal Au-Ag mineralisation in Coromandel, but are highly variable and need detailed stratigraphic, structural, petrologic, and geophysical studies to characterise them.

Jan 1, 1999

Solid Energy New Zealand Limited owns and operates the Ohai coal field (Wairaki Coal Mining Licence, CML) in western Southland. The Morley Stream passes directly through the middle of the CML and has required diversion in the past to enable open cast mining to proceed. Solid Energy is evaluating two new open cast pits at Ohai. Commissioning these new pits would necessitate further diversion of the Morley Stream. One of these potential new mines is adjacent to an abandoned State Coal Mines (State Coal) pit and there is an opportunity to substantially rehabilitate this old pit as a corollary to the new mine and the stream diversion project.   Past Morley Stream diversions were undertaken by State Coal and so they predated the Resource Management Act 1991 and the degree of community environmental awareness and involvement that has become the norm these days. Not surprisingly the design and construction of the historic stream diversions was based purely upon mining (operational) and engineering considerations. This led to the stream being diverted in a manner that achieved the clinical conveyance of design volumes of water from points A and B.   Solid Energy realised that the proposed new diversions need to adopt more holistic and environmentally sustainable design principles while also including appropriate mining and engineering constraints. This project involved the design of a 1.7 km diversion of the Morley Stream (median flow of about 1000 litres/second) that would enable progressive prestripping and development of the new mines and would also address final rehabilitation (of the stream), geotechnical risks, hydrological and ecological issues. To address all of these factors the project required a multidisciplinary approach. Moreover, it required a clear understanding of how the mining operational constraints could be integrated with the environmental considerations. A significant aspect of the project was how to take account of fishery instream habitat needs, the resource consent requirements and most of all, the involvement of key stakeholders such as the Fish & Game Council, Department of Conservation, the Iwi and local community in the design process. This was achieved through coordinated consultation and stakeholder involvement in a technical design workshop.

Jan 1, 2005

Gold was first discovered on the Shotover by Thomas Arthur in 1862, and soon there were over 3000 miners working on the river. It has often been called the richest river in the world. Most countries probably have one of these, but it was certainly the richest in New Zealand. In the early days some miners collected as much as 200 oz/d from a sluice box, and the early river gravels must have been extremely rich before the gold bearing terrace gravels were sluiced into the river. Otago produced about 10 Moz out of the NZ total of over 30 Moz. Most of this was alluvial and possibly one third or more came from the Shotover. The extremely cold winter and danger of flooding made it a dangerous river to work. During 1863 when heavy rain melted snow in the high country, the river rose 35 ft overnight and drowned many miners camped on the banks. These hazards still exist and dominate the method of working. The early hand miners cleaned out much of the riverbed, and the advent of the hydraulic elevator enabled deeper parts of the river to be worked over. Extensive sluicing of high terraces also took place particularly around Skippers. Several companies have attempted operations on the Shotover. Many of these were distinctly unsuccessful, such as the suction dredge at Maori Point about 1930 and the Skippers Limited fluming in about 1934. At least two attempts were made to divert the river with the Sandhills cut above Skippers and the Oxenbridge Tunnel down near Arthur's Point.

Jan 1, 1983

By Hillis R

As part of BHP Iron Ore's policy and goal of achieving a high standard of environmental management within its operations, a protocol for mine closure has evolved. The need to demonstrate sound environmental management with respect to site decommissioning meant that a comprehensive, environmentally sensitive closure protocol was required. Within this framework, a four-phase protocol was developed, the first phase was the determination of objectives in relation to site rehabilitation and end land use. The second phase was the determination of the process required to achieve these objectives. The third phase was the application of this process in a site specific manner. The fourth and final phase was monitoring of the site with regard to the achievement of determined objectives. The protocol was originally developed to direct the closure and decommissioning of the Goldsworthy site in 1992. This being the first total site decommissioning for BHP Iron Ore. Since that time the protocol has been successfully utilised for the closure of the Yampi (Koolan Island) operations (in 1993/94) and the Shay Gap/Nimingarra Operations (in 1994/95).

Jan 1, 1996

By A R. Proudman, A H. Purvis

The Granites Gold Mine Callie gold deposit is located 550 km northwest of Alice Springs in the Tanami Desert. Gold mineralisation occurs due to a complex interplay of geological factors which include but are not limited to favourable lithology, structure, alteration and quartz veining. High-grade mineralisation, while pervasive under favourable conditions, is highly variable over short distances and is very nuggetty. In contrast, the lithology and geological structures that host the mineralisation are very continuous. Orebody modelling techniques have evolved over time because of a growing understanding of the mineralisation controls. Modelling issues such as sampling and assaying accuracy, modelling method, data density, gold population statistics, geological interpretation and domaining, grade boundary and calculation conditions, and model block size are constantly being reassessed in an effort to increase understanding of the mineralisation controls and modelling accuracy. The evolution of the modelling process in response to increasing data levels and a growing understanding of the mineralisation controls has resulted in changes to the perception of the orebody size and style. This has caused the choice of underground mining method to be revised several times and the process to final mining method selection to take longer than usual. In order to achieve the planned production start-up date of July 1998 the process has been allowed to progress in parallel with development of the underground mine. This paper describes the resource modelling and mining method selection process applied to the Callie underground mine and some of the issues which have contributed to its evolution. Some conclusions that are relevant to the efficient planning and development of new mining projects in general are presented.

Jan 1, 1998

By J Sibbel, K Goh

A key issue facing mine managers in remote locations in Australia and overseas is that of managing a fly-in, fly-out (FIFO) workforce. Current Australian research (Sibbel, in prep) indicates that FIFO employees and their families do not differ from the general population in terms of their overall mental health and the well-being of their family relationships. However, they do face unique issues/pressures associated with the lifestyle, the impacts of which are dependent on the policies and practices of the company as well as individual coping and support mechanisms. Successful management of a FIFO site and its employees therefore requires specialist knowledge and skills beyond those of a solely residential operation. The well-being of the FIFO workforce depends on both site and individual employee characteristics, and has implications for productivity and turnover, as well as safety and health. In addition, although FIFO separates individuals and their families in time and space, the interaction between work and home must be acknowledged and taken into account. Drawing on findings from recent Australian and international FIFO research (eg Annear, Poot and Kingston, 2006; Beach, Brereton and Cliff, 2003; Brereton et al, 2006; Gallegos, 2006; Keown, 2005; Parkes, Carnell and Farmer, 2005; Sibbel, 2001, 2004, in prep; Shrimpton and Storey, 1996; Storey, 2001; Watts, 2004) this paper discusses key understandings of both the positive and negative impacts of FIFO employment on employees and their families, and provides practical management strategies as an aid to the development of best practice. Individual impacts including fatigue and loneliness, as well as family issues such as communication, continually changing roles and responsibilities and the impacts of regular parent absence are key areas which can be ameliorated by appropriate management understanding and action. A flexible framework approach is presented that is suitable for a diversity of operations, including principal and contractor workforces of different sized operations.

Jan 1, 2006

In this paper a quantitative deterministic risk modelling approach (Quadrim) is introduced. The mathematical framework and equations for quantifying uncertainty within and aggregating across value chain nodes from error propagation techniques is proposed and discussed. A case study and worked examples, based on a hypothetical mine are then presented. This illustrates how uncertainty from the mining and economic value chains can be handled in a typical net cash flow calculation, and how this can be translated to a risk model. It is then illustrated that current valuation techniques do not just result in an information gap for decision makers. Traditional approaches such as discounted cash flow (DCF) analysis and truck and shovel productivity analysis, which do not take into account uncertainty in input values, can result in potential bias in estimates such as net present value (NPV) or equipment hours

Sep 26, 2011

The construction of mine headframes of reinforced concrete is not a new departure as many structures have been built of this, material particularly in Canada and South Africa. This type of construction has been satisfactorily tested in service and is now accepted by the mining fraternity.The two headframes at New Broken Hill Consolidated Limited are the first structures of this type to be built in Australia, and provide an interesting application of reinforced concrete design and construction.Reasons for Adoption of ConcreteDuring 1947 the writer visited D.S.A. and Canada and inspected three headframes, of reinforced concrete construction.Leading details are as follows:(i) Hollinger Gold Mines. (Timmins, Ontario) : Height of sheaves 110 ft. Shaft has provision for 4 skips each of 12,000 lb. capacity. Structure incorporates surface crushing plant.(ii) International Nickel Corporation-Murray Shaft (Sudbury): Height to sheaves 153 ft. 6 in. Shaft provides for 2-12 ton skips and 2 cages. Surface crushing plant built integrally with frame.(iii) Asbestos-Johns Manviae (Quebec): Height of sheaves 116 ft. Shaft provides for 2 skips 200 cu. ft.

Jan 1, 1956

Acid soluble calcium is depleted in drainage sediments from hydrothermal alteration centres in the Coromandel Peninsula. The routine analysis of acid-soluble calcium on drainage samples is an economical and effective technique for outlining hydrothermal alteration centres in volcanic terrains.

Jan 1, 1979