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By D La Rosa, K Caron, H Mamani, W Valery, R Diaz

The Gold Fields Cerro Corona copper-gold deposit in Peru has heterogeneous rock characteristics in terms of its mineralogical, geological and geotechnical properties. Blast design variations in these conditions directly impact the run-of-mine (ROM) fragmentation, which in turn influences downstream process efficiencies. In particular, when harder ore is processed, throughput and circuit performance may be limited.To evaluate the potential to increase throughput and improve overall plant performance by optimising blasting practices and comminution circuit operation, Gold Fields La Cima engaged Metso Process Technology and Innovation (PTI) to conduct a full process integration and optimisation project at Cerro Corona. Blasting, crushing and grinding processes were reviewed to identify the potential to achieve substantial improvements in productivity when treating the most competent ore types.Site-specific models of the blasting, crushing and milling processes were developed using SmartTagTM ore tracking technology for calibration and validation. Ore tracking permitted locations in the blast volume to be queried against the geotechnical block model to determine the hardness and structural parameters of the feed to the comminution circuit. They also ensured surveys were conducted when ore from the audit blast was flowing through the crushing and grinding circuits.The predictive models developed enabled PTI to demonstrate how changes in blast design influenced both ROM fragmentation and the performance of downstream comminution processes. Outcomes of the project suggested changes to blast designs and comminution practices, and these were partially implemented for a validation trial. The trial demonstrated a 14.8 per cent increase in mill throughput for the specific ore selected for the study, and an average increase of 5.7 per cent for all ore types. There is potential to further increase throughput and process performance if all recommendations are implemented. This paper describes the methodology used and benefits to the operation from the mine to plant.CITATION:La Rosa, D, Caron, K, Valery, W, Diaz, R and Mamani, H, 2015. Blast fragmentation impacts on downstream processing at Goldfields Cerro Corona, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 333–342 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By M J. Sale

The Epithermal and Mesothermal Gold Prospectivity Modelling Projects recently completed by Crown Minerals provided explorers in New Zealand with a new compilation of historical exploration data combined with new geological information from the GNS QMap 1:250 000 scale mapping project. These data were used to produce predictive mineral potential maps for gold mineralisation in New Zealand. The aim of these projects, which was to stimulate mineral exploration and investment in exploration, has been successful with new companies acquiring new tenements and committing significant exploration expenditure to exploring in New Zealand in the coming years. The projects were undertaken at a national scale and consequently not all exploration data were compiled into the prospectivity models. HPD New Zealand Ltd recognised the value of the prospectivity modeling work and committed exploration funds to continue the modelling process started by the projects. They recognised the need to compile the remaining data and run the models again to allow detailed exploration targeting.

Jan 1, 2004

Many of the large refrigeration plants used in, the cooling systems on deep South African gold mines are situated on surface where they are exposed to seasonally and diurnally varying climatic conditions, and to a diurnally varying demand for cooling made by the mine. It has been traditional to accommodate the seasonal variation in climate by manual control applied to the plants at appropriate times of the year, and the plants have normally been specified to conform passively to the diurnal variations. This paper introduces new strategies for the active automatic control of the plants on a diurnal cycle, and shows that attractive benefits in energy and chilled water resource management can be accrued through the use of these strategies. The results have been derived through the modelling and simulation of a representative refrigeration plant.

Jan 1, 1985

By G K. Robinson

Variations in many aspects of physical and chemical grade are often of concern to mining operations and mineral processing plants. In most circumstances these amounts of variation are predictable. At the time of planning new operations, we should be able to predict the amount of sampling and testing variation which our sampling devices, laboratory procedures and on-stream analysis devices will achieve. We should know how well our stockpiles, reclaimers and bins will homogenise material (or whether segregation will actually increase the amount of variation). We should be able to predict the amounts of variation that will occur on the important time or tonnage scales at the crucial p oints in our proposed operation. And once these amounts of variation are reliably known, mine planning will seem a little bit more like dealing with known knowns rather than like dealing with unknown unknowns.The first step towards quantifying amounts of variation for planned operations is to assess amounts of variation for existing operations. How many operations have estimates of amounts of variation in their databases? How often are people able to partition amounts of variation into amounts due to sampling error, amounts due to sample preparation, amounts due to assaying, and the amount of real variation in the stream of material?CITATION:Robinson, G K, 2012. Making sure that the amount of grade variation is a known known, in Proceedings Project Evaluation 2012 , pp 159-162 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

The discovery of nickel sulphide deposits at Kambalda in 1966 heralded the development of ò an industry with a capital value of over $1.5 billion producing about 10% of the western world's nickel. ò an unprecedented exploration boom in which over $200 mil- lion was expended in 10 years in the search for nickel deposits. ò a major new class of nickel deposits stimulating exploration for similar deposits overseas. and rapidly propelled a struggling small mining and exploration company to become one of Australia's corporate giants, provid- ing a much-needed stimulus to economic activity in a region suffering from a severe downturn in its principal industry, gold mining. Production of nickel in Western Australia commenced at Kam- balda in 1967 and grew rapidly to a rate of over 30,000 t of con- tained nickel per annum in 1970, 40,000 t in 1973 and 50,000 t in 1975. Early production was aided by a shortage of nickel on the world market due to disruption of supply from the major Canadian producers, resulting in high free market prices for the metal. Since these early years, the industry has experienced a number of cycles of indifferent health due principally to market developments overseas, although the level of production of nickel in Western Australia remained fairly consistent. The two most serious of these, in 1977-8 and 1985-6, forced the closure of a number of mines. Current nickel prices are allowing remaining producers to enjoy a measure of relative prosperity, although there is little general speculation that this will be long-lived. Nickel deposits discovered in the exploration boom were almost exclusively related to ultramafic rocks. Volcanic peridotite (komatiite)-associated deposits, exemplified by the Kambalda ore- bodies, were the targets of initial exploration which was concen- trated on ultramafic sequences near lower stratigraphic contacts with underlying mafic rocks. Subsequently, discoveries made in coarse-grained dunites in interpreted intrusive settings broadened the search parameters.

Jan 1, 1988

By J J. Cilliers, K Hadler

Air is fundamental to flotation; not only is it required to collect the valuable particles, but it also controls the froth stability and consequently the separation performance for a given feed. Froth stability can be described and quantified in numerous ways, which are subtly different. Air recovery is one such measure of froth stability which accounts for both the stability of the bubbles and the mobility of the froth. The benefit of using air recovery as a measure of froth stability is that it exhibits a peak as air flow rate is increased, and this corresponds to the air rate at which the optimal separation performance is obtained. As such, it provides a single target value for optimising air flowrate for a given set of feed conditions. Use of air recovery, however, has one potential drawback: accurate measurement of the inlet air flow rate to a flotation cell is required. This can be problematic for operations, particularly where calibration of air flow rate is carried out infrequently or where there is no air flow rate measurement, such as for many self-aerated flotation cells. To this end, we present an alternative method for determining the peak in air recovery (PAR) air rate.We introduce a simplified method for determining the PAR air rate using trends in froth velocity and overflowing froth height, both of which are readily measured using existing froth image analysis systems. We will show, using industrial data, the application of this simple technique to find the optimal air flowrate for flotation cells. We will also discuss other alternative techniques for air rate optimisation that have the potential to improve separation performance using existing technology.CITATION:Hadler, K and Cilliers, J J, 2018. How to find the optimum air rate for flotation cells, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 377–384 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By R N. Humphries, R J. K Thompson

Large-scale coal mining in South Wales dates back to the late 18th and early 19th centuries with the birth of ironmaking on an industrial scale. This rapidly gave rise to new and large communities with immigration from far and wide across the United Kingdom (UK). These new communities were largely dependent on coal mining and served as the main form of employment and social cohesion until the industry’s demise in the 1990s. With wholesale mine closure and the concomitant loss of employment, the extensive environmental degradation and chronic mine-related illness left a deep scar on the psyche on many still living in the South Wales mining communities. This coupled with memories of strife in the 1980s has resulted in ongoing hostility toward the surface coal mining of the remaining accessible coal reserves in the proximity of these communities.The purpose of this paper is to set out the historical basis of the concerns of these legacy mining communities in South Wales and explain how they are being positively addressed by both the recently evolved planning and regulation system and by today’s surface mining industry. Reference is made to experience gained from two recent applications for surface coal mining adjacent to former mining communities. Ways are suggested in the approval process that surface mining can work in more harmony with the local communities through working partnerships between the mining company, the authorities and regulators and the affected communities. It is concluded that partnership is key to creating a more responsive mine-operating culture and a means to securing approval for future surface coal-mining prospects in South Wales, and probably elsewhere too.CITATION:Humphries, R N and Thompson, R J K, 2014. Surface mining and legacy mining communities in South Wales, UK, in Proceedings Life-of-Mine 2014 , pp 399–412 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

Quantitative probabilistic ecological risk assessment has been used to evaluate the likely effect on fish diversity and abundance of filtered and bioavailable metals in streamwater affected by acid drainage from the abandoned and remediated Rum Jungle U/Cu mine in the Northern Territory of Australia. The water quality was determined using monitoring data from a gauging station on the East Branch of the Finniss River, downstream of the mine site, and modelled assuming a number of potential water quality management options. The management options ranged from no action, through some flushing options to full catch and treatment of contaminated seepage from the waste rock heaps. The computer code AQUARISK was used to undertake the analyses. Critical criteria for contaminant water concentrations at the site, derived from probability density functions of available fish ecotoxicology data, were found to closely approximate the regulatory trigger values for the contaminants of concern. Modelled predictions of reduced diversity and abundance were also in good agreement with in situ biodiversity measures. Based on a reasonable target of 67 per cent species tolerance for this heavy impacted site, it was found that none of the low cost options for wastewater management was acceptable. Combinations of two of the options approached acceptability. Both of the catch and treat options exceeded the arbitrary acceptability target well. This implied that the more expensive option of liming to pH 10 might be unnecessary at this site. Thus, the use of ecological risk assessment modelling has proven useful in undertaking cost-benefit analyses for this site. The approach provides a management decision-making tool that can be economically used to link expensive on-site environmental engineering options with site-specific ecological goals rather than the previous nebulous aims of æreduced contaminant loadÆ or æimproved biodiversityÆ that often resulted in excessive expenditure without achieving successful environmental benefit.

Jan 1, 2003

By R W. Henley, L Knuefing, M Turner, Y Zhang, M Saadatfar, A Limaye, R Cruikshank, M A. Knackstedt, A Kingston, L Beeching, N Francois

A better understanding of ore fragmentation and the textural features of ore is a key to the energy efficient extraction of targeted minerals from low-grade ore deposits. In this study, X-ray microcomputed tomography (micro-CT) is employed to study mineral liberation during the tensile failure and onset of fragmentation of a copper ore. Our results show that X-ray micro-CT could inform new studies of ore micromechanics and fragmentation at the laboratory scale and may offer new avenues to address current challenges in the design of efficient comminution processes. We present the results of experiments based on a high-pressure apparatus enabling micromechanical studies to be carried out in situ (inside a micro-CT scanner). This platform produces high-quality 3D images of the evolution of a sample of porphyry copper ore during an in situ fragmentation test. A sequence of tomographic images enables mapping in 3D of both the deformation of mineral phases and the fragmentation process. The fragmentation occurs quasistatically through multiple stages starting with an initial tensile fracture splitting the ore diametrically, followed by tensile-activated nucleation and growth of multiple fractures producing a complex fracture network. Coupling breakage with microstructural information enables quantitative determination of the impact of ore texture heterogeneity on fracture patterns and mineral liberation. This microstructural information can be compared to key measurements of the ore mechanical behaviour such as the global deformation energy, strain deformation field and the stress relaxation response. The latter allows one to identify interesting precursor signals of the tensile failure. The copper liberation, fragment size distribution and breakage patterns are statistically characterised and related to comminution mechanisms which are clearly identified in the sequence of tomographic images. The two dominant mechanisms are rock-rock friction/compression induced by fracture closing and compression-driven fragmentation at rock-crusher contact points.

Aug 24, 2022

By A Annor, L J. Chen

The production of paste backfill has typically been accomplished through the adaptation of existing technology. Thickeners and disc filters have several drawbacks when applied to production of tailings paste backfill. Personnel at CANMETÆs backfill research laboratory in Sudbury, Ontario, Canada have been carrying out research into and development of methods to produce paste backfill using total mill tailings since 1991. Using a silo for production of paste is not a new concept but has been refined to a marketable level. This technology is based on a fluidization principle that assists in settling the tailings to an homogenous state in a silo. Other developments include patented de-watering technology for use in the silo to speed the settling of the solids to a suitable solids content, optimisation of silo geometry, and instrumentation related to paste backfill production and transportation. The advantages to fluidisation technology are in reduced capital cost, reduced operating costs and in the environmental benefits of using full plant tailings over classified tailings or alluvial aggregates. Another major advantage is in the ability of this technology to be retrofitted to existing hydraulic backfill plants to further reduce capital cost. This paper details the development of the new technology as well as the associated cost savings over other technologies. It will also look at the research and development of unique components that make this technology work.

Jan 1, 1998

The Research Centres Program initiated by the Federal Government and supported by the mining industry has had a major impact on geoscience research and education during the past five years. Eight major university based-Geoscience Research Centres are currently supported by the Government, including four Key Centres of Teaching and Research and a further four Cooperative Research Centres (CRCs). The Research Centres Program has led to a concentration of high quality research and teaching in areas of demand and strategic importance creating strong university - industry linkages and a source of well trained and motivated graduates. Over the last decade Australia's reputation as a leader in mineral exploration and ore deposit research has grown substantially, in part because of the development of the Research Centres Program, and to increased collaboration and interaction between research groups and exploration geoscientists across the industry. During a period when ore deposit research activity has been decreasing in other countries (eg USA, Canada, Japan and most European countries), equivalent research activities in Australia have been increasing, within a well co-ordinated national framework. The future challenge for universities and the mining industry will be to maintain the momentum of the successful research centres in order for the centres to become self-funding over a six- to nine-year period.

Jan 1, 1996

By Y M. Wang, W Z. Liu, L F. Li, X L. Zhang

Based on the blasting crater theory, the equation between k under typical cases and burden line, charge height was obtained by open pit bench blasting analysis model. The model was calculated with mine production blasting. The blastability coefficient k and the best range of blasting burden line were specially emphasised on determination of lateral crater tests.CITATION:Wang, Y M, Liu, W Z, Zhang, X L and Li, L F, 2015. Application of lateral crater test in open pit blasting parameters optimisation, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 463–468 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By H Hy÷tyniemi

In this paper multivariate data analysis performed on a new multi-camera system implemented to zinc flotation circuit of PyhSsalmi mine is presented. Image-analysis-based system was developed to take advantage of the commonly known fact that the changes in the flotation process are reflected to the visual appearance of the froth surface. Most often the changes are seen first in the froth and later in other process measurements. The image variables are already utilised in closed loop control and considerable savings are achieved with the current setting, but the results coming from the separate cells are used individually. This is clearly not the optimal way to take advantage of the many measurements coming from different locations of the process. A better approach would be for example to use the measurements coming from the early stages of the process to predict the behaviour (or improve the quality of measurements) in the later stages. The methods described in this paper are aimed to improving the situation in this sense.

Jan 1, 2005

New Caledonia is a major metallogenic unit of the south-western Pacific Rim. Its mineral production is of world significance and it has an unusually well diversified mining history. New Caledonia's main metallogenetic potential is, however, associated with its unique ophiolitic complex and its important mineral- izations of nickel, chrome, cobalt and iron. Gold has been found in all the four basic tectonic elements of New Caledonia: the Central Massif, the West Coast basalts, the ophiolitic complex and the Caledonian North. Some analogies are attempted. Only the Caledonian North has supported mining operations (213 kg Au). More recently tenuous gold indications have been found within the ophiolitic complex, possibly associated with Oligocene plutonism.

Jan 1, 1987

Cores of pre-Tertiary basement from ten oil exploration wells are related petrologically to the "axial", "marginal" and "shelf" facies of the New Zealand Geosyncline.A NW. Nelson-type basement is inferred beneath peninsular Taranaki and the western continental shelf. The terms Taranaki Basin and Wanganui Basin are re-defined and the terms North Wanganui Basin, South Wanganui Basin, Pipiriki High, Taranaki Fault, and Turakina Fault are proposed. Major faults are interpreted as of mainly transcurrent type and appear to form the western part of a splay at the northern end of the Alpine Fault. Evidence for a major Cook Strait Fault is reviewed.

Jan 1, 1967

By K J. McDonald

All commercially available zircon sands contain radioactivity sourcing from the decay of trace amounts of contained uranium (U) and thorium (Th). The fine particle size zircons of the Horsham area in the Murray Basin region of Victoria, Australia, contain significantly more (about twice) Th+U than those commercial zircon sands. The marketability of these fine-grained zircon sands is likely to rely on the removal of these radioactive impurities. CSIRO Minerals have been working for some time to develop processes for the removal of the radioactive impurities from zircon. It is generally agreed that it is quite impossible to leach U and Th from zircon, however, the Heat and Leach (HL) process, described in detail in Aral and McDonald (1999), reduces the radionuclide levels significantly. The identified (HL) process aims to leach uranium and thorium selectively from a decomposed zircon. The novelty of the process is that a large part of the leached product can be reconstituted to a low radiation zircon by a subsequent heat treatment. The HL process uses a flux mixture of sodium carbonate and calcium borate to decompose the zircon at relatively low temperatures (900 to 1150¦C) and a weak acid (0.5M HNO3; 80¦C/0.5 h; pulp density ten per cent) to leach the radionuclides selectively. The process leaves the major components (ZrO2 and SiO2) behind with little loss. The HL process for example lowers the U+Th content of a Murray Basin zircon from 1000 ppm to 400 ppm U+Th. Among the radionuclides more U progeny is removed than the Th series radionuclides. This is very significant as the radioactivity of U series is 2.5 times more that from the Th series. Therefore the reduction in the radioactivity level of zircon is more than the reduction in Th+U indicated by XRF analysis. A schematic flow sheet of the HL process is shown in Figure 1. Although the HL process successfully lowers the radionuclide levels in zircon sands, the final product contains significant amounts of sodium (up to 14 per cent Na2O) and small amounts of CaO. By comparison, the sodium content of the commercial zircon sands is in general 2O. Zircon is used mainly as an opacifier in tile glazing where the addition of ten to 15 per cent zircon to a translucent base glaze gives the sanitary white colour to the tile surface. Opacification is the result of the refractoriness of zircon particles at the glaze firing temperatures that is generally around 1050¦C.

Jan 1, 2001

By G York

South African gold reserves extend to great depths. However, strategies for the mining of such deposits have changed only slightly over the past number of years. Regional support at depth is currently provided by rock pillars and backfill. Many problems have been experienced with these regional support practices at deeper levels. In this paper several alternative forms of regional support are described which include the use of concrete, the use of back area caving and confinement to strengthen pillars. These new concepts are supported by numerical and laboratory modelling and in situ results.

Jan 1, 1998

The history of potential large scale development at Stawell in northwestern Victoria dates back to 1914, when Great Boulder Mines Limited, of Kalgoorlie, Western Australia, took up options on some of the major mines in the Stawell Goldfield. Despite this and other attempts by various groups over the next thirty years, mining activity on the field gradually dwindled to the retreatment of old mill tailings.A static price for gold and indifferent drilling results prevented a major effort towards reopening the field until the late 1970's. A renewed exploration effort led to the discovery of sufficient reserves to justify installation of a carbon-in-leach gold treatment plant.

Jan 1, 1984

By D R. Andrew, K T. Morrison, J F. Tiedgen

Waste blasting in iron ore operations can pose a number of technical challenges, including blasting through variable geology and blasting soft ground in wet conditions. Blast patterns are designed to be loaded with a specific range of explosives with unique characteristics and properties. Each explosive product will produce an optimal blast outcome for a given set of blast parameters and ground conditions. Sites characterised by softer rock typically require low-density, low-energy explosives. Historically, these products have contained a high ratio of porous ammonium nitrate prill and are only suitable for dry blastholes. When blastholes within a pattern are found to be unsuitable for such explosives due to wet, damp or muddy blasthole conditions, a new product is selected. While it is easy to switch products to match blasthole conditions, the different properties of the new non-ideal product can impact blast performance and increase loading times and costs.Flexigel™ is a solids-sensitised emulsion blend suitable for loading at variable densities and energies in dry, damp, muddy or wet blastholes. It is a universal product that can be loaded to match ground and blasthole conditions or complement other explosive products.At Fortescue Metals Group’s Cloudbreak site, Flexigel™ was trialled through a series of matched pair blasts in order to optimise blast outcomes in conditions that were non-ideal for existing explosive products and to reduce the overall cost of drill and blast operations. Flexigel™ yielded improved instantaneous dig rates and improved loading efficiency when compared to a traditional emulsion blend. The results also indicated that variable-density and variable-energy products afford greater flexibility for optimising blast outcomes across all ground and blasthole conditions trialled.Trials of Flexigel™ at Cloudbreak have shown that a variable-density solution is available for conditions where traditional explosive products are non-ideal. As such, Flexigel™ is able to fill a major void at any operation where the desired low-density, low-energy explosive product must be substituted for a more expensive traditional emulsion blend or heavy ammonium nitrate/fuel oil.CITATION:Andrew, D R, Morrison, K T and Tiedgen, J F, 2015. Flexigel™ – a variable-density solution, in Proceedings Iron Ore 2015, pp 413–418 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

The old Trekelano mining area is situated in the Cloncurry Gold and Mineral Field 14 km east-south-east of Duchess. It connected with the main Cloncurry-Dajarra railway line by a private line from Juenburra, a distance of 10 km. The distance by rail from Townsville is 561 km. The area was first mentioned circa 1902 - 1903 when a very short report said, that a Tony Allis had taken a parcel of copper ore out of a mine which, he called æThe InheritedÆ. After that report, nothing further was printed until about 1906, when traces of copper were noticed on a wagon track going to Kiama Well. The Trekelano deposit did not outcrop, with the cap covered by about two metres of soil. The deposit was named after an early pastoral holding. The early prospectors were however disappointed by TrekelanoÆs low copper grades, approximately five per cent Cu. This is understandable when, in those days, about 25 per cent was the cut-off grade for mines in the district. Meanwhile, The Hampden Mining and Smelting Company were constructing a smelter to treat their sulphide ores at Kuradala that was replacing their high grade oxides ore. By about 1910, the Hampden Mining and Smelting Company was experiencing smelting problems, and needed suitable oxidised copper ore to blend with the Kuradala pyritic ore. Someone must have remembered the Trekelano low-grade oxides, resulting in agreement to mine and cart the ore to Duchess, from where it was railed to Hampden, as Kuradala was known at that time.

Jan 1, 1998