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By C S. Kelsey, J R. Kelly

Australia is presently enjoying the fruits of a booming iron ore market. Expectations are that market strength will be supported in the short to medium term by increasing feedstock demands from steel mills, as world economies rebuild post-Covid-19. However, as cost and environmental pressures increase the longer-term market outlook will be dominated by product quality. The ‘flight to quality’ will place increasing demands on direct shipping ore miners as they compete to maintain their standing in the iron ore marketplace. China will progressively disengage from its dependence on Australian imports, leaving miners under increasing pressure to boost product quality and diversify outlets globally. Australia has vast deposits of low-grade magnetite ores located mainly in remote and arid regions of the continent. This paper proposes a dry grinding and magnetic separation process to produce premium concentrate grades from the low-grade ores, to assist in meeting future product quality demands. The premium grade concentrates could be either blended with lower quality direct shipping ores or marketed separately. The proposed dry concentration process involves the pairing of Vertical Roller Milling (VRM), a mature technology widely used in the cement industry, and Planar Magnetic Separation (PMS), a new methodology, which has been developed to the threshold of commercialisation by the private Australian company Cyclomag P/L. Two laboratory prototype planar magnetic separators with field strengths of 1800 gauss and 6000 gauss have been built and tested on a range of magnetite ore types over the past three years. In each case, following grinding to liberation sizes, a combination of roughing and cleaning operations has produced pellet grade concentrates. Vertical roller milling has competed successfully with conventional media milling in grinding cement clinker, limestone and blast furnace slags. A key advantage of dry VRM/PMS processing is its potential adaptability to stepwise modular development, which can minimise initial capital investment, while generating early revenue streams to cope with unpredictable market volatility.

Nov 8, 2021

Flotation of Composite Synthetic Particles

Sep 13, 2010

Improving Pentlandite Selectivity Over Pyrrhotite Using Reagents

Sep 13, 2010

The Johnny Mercer lyrics 'You've got to accentuate the positive, Eliminate the negative, Latch on to the affirmative à' would best sum up the traditional approach to community relations in the mining industry. This '90s 'Public Relations spin' approach, usually backed up by scientific data, technical reports and graphs outlining risk probability and the impact potential on people and communities, is being challenged. Challenged by communities who have greater access to information, demand greater levels of transparency and corporate responsibility of large corporate operations and possess greater awareness of the communities they live in.   The growth of the environmental movement, of anti-globalisation, anti corporatism, apprehension of a large corporate's ability to deal with community issues, and a lack of faith in the abilities of regulators to regulate corporate activities, means our industry faces challenges on multiple fronts. It must now be able to address these from a personal/community perspective if it is to remain relevant within communities.   One of the keys to this is linking the internal activities and responsibilities to the externals concerns and demands for higher levels of operation and care.   This presentation draws on Corporate Public Affairs trends, functions and approaches and the application to External Affairs activities within Newmont Waihi Gold's operations in Waihi and regional exploration activities throughout the Hauraki Goldfields.   The approach presented works on the philosophy that communities don't necessarily have to like what we do, but should be able to identify and recognise the way in which we involve them in decision making, communicate our intentions and respond to issues.

Jun 1, 2010

By D N. Castendyk, J L. Mauk

The world-class Waihi (>6.6 Moz Au, >41.8 Moz Ag) and adjacent Favona (>0.5 Moz Au) deposits are within a single volcanic-hosted epithermal Au-Ag district located in the southern Coromandel Peninsula, New Zealand. Gold and silver mineralised quartz veins at both deposits are hosted in porphyritic andesite flows of the Waipupu Formation. Both deposits have veins surrounded by intense widespread hydrothermal alteration that is characterised by the assemblage of quartz, pyrite, adularia, illite or interstratified illite-smectite, plus less common chlorite and albite, which is locally overprinted by minor calcite or rare kaolinite. Quantitative mass transfer calculations using Gresen's general metasomatic equation indicate that hydrothermally altered andesite at both deposits is enriched in silicon, potassium, rubidium, barium, sulphur, gold, arsenic and antimony, whereas sodium, strontium and calcium are mostly lost. Iron and magnesium show mixed gain and loss. Element gain or loss can be directly related to the prevailing alteration mineralogy. Addition of potassium, rubidium and barium coupled with the concomitant loss of sodium, strontium and calcium in intensely altered wall rocks corresponds to the replacement of plagioclase by adularia or illite. Partial retention of sodium and calcium reflects the presence of hydrothermal albite and calcite, respectively. Mass balance calculations show distinct element gain and loss that can be related to the intensity and type of alteration mineralogy. However, because most rocks are intensely altered and the progression into less altered peripheral rocks is not observed in this study, the lateral extent of elements gain or loss is unconstrained with anomalies extending at least 200 to 300 m away from major veins.

Jan 1, 2003

By L Soebari, W Sunyoto

The Wabu Ridge Gold Skarn deposit is located at elevations of up to 3100 metres above sea level, in the Central Highlands of Irian Jaya, Indonesia, 35 km NNW of the Grasberg porphyry deposit. Wabu is a grass-roots discovery in an area with no previous gold mining history or record of gold mineralisation. A geological resource of 117.26 million tonnes at an average grade of 2.16 g/t Au (1.0 g/t Au cut-off) has been defined to-date. Mineralisation is hosted within a skarn occurring along the southern boundaries of the Late-Miocene age monzonite-diorite Pagane intrusive complex. The intrusive complex occurs in the footwall of a major EW structure, the Derewo fault, which displays sinistral strike-slip and reverse fault movement. The Derewo fault separates Derewo metamorphic units to the north from platform sediments of the Australian craton to the south. The skarn has a strike length of 6 km and is up to 1.5 km wide. It is developed within calcareous shelf sediments of the Tertiary New Guinea limestone group and is dominated by prograde garnet development. Gold mineralisation was deposited during retrograde alteration and is directly associated with arsenophyrite and bismuth minerals. Retrograde alteration is distinguished by a sequence of clinopyroxene , magnetite, epidote and hornblende, biotite and chlorite and lastly carbonate. Gold is associated with the biotite/ chlorite phase together with sulphides and precipitated as the result of fluid mixing. The Wabu Ridge Gold Skarn deposit was identified in April 1990 during a regional program of helicopter assisted stream sediment sampling of -80 mesh (180 microns) fraction and panned concentrate sampling. The initial discovery sample site was situated 15 km down stream from the deposit and returned 1.49 ppm Au for the stream sediment sample and 138 ppm Au for the panned concentrate sample. A regional airborne helicopter magnetics survey, conducted in early-1992, helped defined the main magnetite associated skarn zone and the extent of associated igneous rocks. Detailed follow-up commenced in May 1992 and consisted of detailed mapping, soil sampling and ground magnetics prior to drilling the first hole in October 1992. Drilling to-date has delineated a contained geologic resource of 8.1 million ounces of gold and potential exists for a larger resource.

Jan 1, 1999

Recovery Process of Carbon Dioxide with Metal Oxides and Metal Hydroxides

Sep 13, 2010

Comparison of Industrial Cyanide Destruction Processes

Sep 13, 2010

By C Chen, T Kan

The distribution ratio of Pb (LPb s/m) between three types of slags (FeOx–SiO2, CaO–FeOx and FeOx– CaO–SiO2) and molten copper after equilibrium was measured at 1300°C and oxygen partial pressure (pO2) of 10-10–10-6 atm. Results showed that for FeOx–SiO2 slag, the LPb s/m increased from 0.024 to 2.57 with pO2 increased from 10-10 to 10-6 atm. The LPb s/m with CaO–FeOx slag was lower than the FeOx–SiO2 slag at the same pO2, ranging between 0.015 and 0.53. Using the FeOx–CaO– SiO2 slag generated LPb s/m values (0.02–1.6) in between. The oxygen partial pressure in the investigated range had no obvious effect on the activity coefficient of PbO (γPbO) which was averagely 0.44, 1.70 and 0.71 for FeOx–SiO2, CaO–FeOx and FeOx–CaO–SiO2 slags, respectively. The increases in the (CaO+MgO)/SiO2 mass ratio of the FeOx–CaO–SiO2 slag induced the decrease in the LPb s/m and the increase in the γPbO value. However, the variation in the Fe/SiO2 mass ratio didn’t exert obvious effects.

Jun 19, 2024

By M D. Melville, B C. T Macdonald, J Dixon

The acidic and metal rich waters that are generated from acid sulfate soil (ASS) drainage can have damaging impacts upon ecosystems. The most obvious impact has been the discolouration of water and occasional fish kills. ASSÆs produce these acidic and metal rich waters when pyrite in soil is oxidised. Land management techniques are an essential long-term requirement to minimise the amount of pyrite oxidation. Acidic water that cannot be prevented through land management can be neutralised by other techniques. Powdered lime is the most common material in agriculture that is applied directly to soils and waters. Powdered lime can be expensive and if applied dry it may aggregate. Since the aggregated particles of lime are larger they could sink rapidly in the water column and not react. In waters with high concentrations of dissolved iron and aluminium the lime particles may become coated with a metal oxy-hydroxide precipitate, which will decrease its reactivity. A unique lime-dispensing machine, the Waterways Lime Spreader, has been developed to neutralise acidic waterways. The Waterways Lime Spreader can produce a solution rich in fine lime from larger limestone fragments. The current size of the machine means only 3.5 grams per second of limestone can be emitted. This output will neutralise low acidity waters, however, for high acidity waters the time for neutralisation can be long. More reactive chemicals such as hydrated lime or increasing the size of the machine will reduce this neutralisation time. The Waterways Lime Spreader is also capable of producing slurry mixtures if powdered materials are required. Trials with the Waterways Lime Spreader were undertaken in part of the Clothiers Creek catchment located in northeast NSW, Australia. A small drain with a water volume of 4 m3 was neutralised with crushed limestone to pH 6.9 from an initial pH of 2.6 and an acidity of 902 mg/L CaCO3 in 160 minutes. In comparison a drain with a slightly larger volume of 6 m3 that had an initial pH of 3.2 and an acidity of 753 mg/L CaCO3 was neutralised with hydrated lime to pH 11.8 in five minutes. The Waterways Lime Spreader has been used successfully to neutralise water from acid sulfate soils. It is expected that future applications of the machine may be for the neutralisation of acid rock drainage or acidified lakes.

Jan 1, 2003

By A Asadov, D Nair

This paper discusses the determination of the percentage of crystalline material in a natural silica deposit which would be considered harmful to health (<10 ¦m). A sample of the natural silica material was recovered and split into a number of subsamples. Samples were sieved using a conventional dry sieve to remove material >300 ¦m before testing. Particle size analyses of the fine fraction showed 75 per cent of the material was below 10 ¦m. Initially XRD and XPS were run on the samples to determine the minerals and composition of the sample. The XRD revealed strong quartz peaks and smaller tridymite peaks with a high amorphous background. The XPS indicated traces of iron, titanium and carbon with dominant silicon and oxygen peaks. The structure of the sample was investigated using the SEM. It was apparent that there were a number of larger quartz crystals (>30 ¦m) with a mix of amorphous and crystalline in the finer fraction. It was also observed that amorphous material was attached to the surface of the crystals. In order to determine the percentage of crystalline quartz a known amount of quartz was added to the sample incrementally. On each addition an XRD scan was performed and the area under the peaks recorded. Back analysis of these peaks with an assumed percentage of crystalline material in the original sample gave a crystalline content of 30 per cent. The quantity at the respirable fraction was estimated to be 18.7 per cent.

Jan 1, 2003

Processing of Hard-to-Treat Copper Ore and Flotation Middlings Using Chemical Treatment

Sep 13, 2010

Is your company paying taxation on profits which are partly illusory?ò Are unions making wage demands based on erroneous notions of the real level of value added to your companyÆs production?ò Do you receive historic data on profit contributions by different products, or for different market areas, which you feel may be misstated?ò Do you find that cash is not always readily available to pay dividends out of reported earnings because, it is required to finance additional working capital without a real increase in the level of activity?ò Are your planning and budgeting routines hampered by the need to rely on historic financial data which bear little resemblance to what the future may hold for your company?ò Are you able to maintain your business at its optimum operating capability or do you feel each year that it becomes more and more difficult to achieve the same volumes of prdduction at the same level of return on assets employed without having to raise more capital?If your answer to any of these questions is "yes", then it is very likely that Current Cost Accounting (CCA) has something to offer you!characteristics of the mining industry and for single venture mining operations.

Jan 1, 1984

In the past two and a half years, over 40 000 metalliferous mining and related services personnel have been trained through an Australian Generic Safety Induction system. This is almost half of AustraliaÆs metalliferous mining related workforce. This remarkable industry acceptance and delivery of safety courses is supported by Acacia Resources, Great Central Mines, Homestake, Newcrest Mining and WMC Resources, amongst hundreds of other mining, exploration and major contracting and services companies. MARCSTA; the Mining and Resources Contractors Safety Training Association (a pro-active not-for-profit self-help group of 24 major contracting companies) developed this generic safety induction. MARCSTA set out to find the æcommon groundÆ necessary to help address the evident safety problems and cost of re-training that were plaguing development of an internationally competitive and productive export industry. The incredible expansion of Australian mining during the decade fuelled a need for out-sourcing, resulting in much larger numbers of contractors on-site. At the same time, changes within Australian legislation, community expectations and the development of huge fly-in/fly-out operations and widespread skills shortages led to a rapid labour turnover and a higher paid workforce. Many Australian mining houses also ran international operations, particularly in South East Asia and head hunted people across the world. The skill levels fluctuated and fell at some local operations. Employers could no longer rely on systematic in-house training of permanent employees to improve safety and productivity as workers could and often did move on. Serious discrepancies in both quality and quantity of safety induction training and work practices occurred. Repetitive, boring and ineffective safety training became an embarrassing and costly burden for companies and workers alike. Then a spate of mining deaths sparked highly publicity, workforce concern and a demand for improvement from government, unions and corporate stakeholders. MARCSTA recognised it had to develop a high-quality safety-training program to satisfy the needs of all employers and be acceptable to others within the industry. This induction system had to be flexible enough to meet differences in legislation between states and industry sectors and be portable to enable cost and time savings for the new transient workforce. Changes in the last two years as a result of evaluating and incorporating various Taskforce inquiries into underground mining fatalities later led to the development of the MARCSTA Underground Safety Induction. This logical development added to the run away success of MARCSTAÆs General Safety Induction and was seen to be essential for many surface mines that were planning to develop underground operations. There are many lessons that MARCSTA learnt during its development that Pacific and South East Asian mining operations can benefit from. The most important of these are the support of stakeholders within industry and the recognition of higher safety and health expectations from workers and government. This goes hand-in-hand with the productivity and return on investment expectations of companies and their shareholders.

Jan 1, 1999

Investigation on Multicomponent Semi-Autogenous Grinding

Sep 13, 2010

Some crystal chemical properties of several apatites from Brazilian deposits and occurrences were determined; the samples had different origins (igneous, metamorphic and sedimentary). The aim was to establish relationships to their froth flotabilities behaviour. Detailed X-ray diffraction studies were carried out, to determine precisely the unit cell parameters and the degrees of crystallinity of the apatite samples. A thorough chemical analysis of these minerals was also conducted. Microflotation studies were carried out, using sodium oleate and dodecylammonium chloride as collectors. The crystallinity levels were determined for all samples studied, with the establishment of a crystallinity index, which varied from 10.0 to 4.5, on a normalised scale. A marked dependence was observed between this crystallinity sequence and flotability; for both collectors, flotability dropped drastically for crystallinity indices lower than 8.0. Also, the low crystallinity apatites showed a decrease in floatability, for longer conditioning times.

Jan 1, 1993

By A Bird

Gravity gold circuits have an important part in reducing operating costs and maximising recovery in modern gold plants where coarse gold is present in the ore body. The design and selection of equipment has a vital part in the overall effectiveness of the gravity gold circuit. There are a number of associated factors that need to be taken into consideration when selecting the most suitable equipment for gravity gold circuits including occupational health and safety, security and labour requirements. This paper is a case study that outlines the validation behind the design, selection of equipment and subsequent benefits of the recent upgrade of the gravity circuit at the Marvel Loch gold mine with the main component to the upgrade being the installation of a Consep Acacia Reactor. Since the upgrade there has been a significant increase in gravity recovery, which has reduced the amount of gold reporting to the leaching circuit therefore reducing reagent consumption and overall operating costs. There has been an increase in overall gold recovery and therefore increased gold production. The benefits to occupational health and safety include the removal of toxic gases being released in the gold room during the previous practice of gold concentrate calcination and the removal of the arsenic and nickel from the gold doré, which poses a risk during refining. Manual handling and security has improved as there is no physical contact with gold concentrates during the automated process using the Acacia reactor. The total time for gold room personnel working in the gold room has also reduced from around six hours per day to less than one hour per day.With the continuing development of low grade gold deposits, there will be an increase in demand for low capital, high recovery gravity gold circuits that can significantly increase overall production while reducing operating costs.

Aug 8, 2011

By Gerasimenko MP

The authors consider the features and advantages of a new promising trend in mineral processing - column flotation. Design aerohydrodynamic and process characteristics of pilot-scale columns are studied. Optimum process parameters for various ores and operations are studied. Flow patterns in cells of various cross-sections are investigated and the relationship between Peclet criterion and specific capacity of cell is determined. On this basis options were developed for optimisation of hydrodynamic characteristics of large capacity cells, including longitudinal sectionalising of the collection zone. It is shown that advantages of high column cells (10 - 13 m) produced in the West can be implemented in a sectionalised machine of smaller height (5 - 6 m). Investigations on the influence of slurry and air bubbles flow patterns indicated that to increase flotation rate of particles of various flotabilities it is expedient to combine co- and counter-current flows of phases in a single column. The proposed designs allow tailings to repeatedly return tailings to the collection zone and alternate co- and counter-current slurry and air flows. For the first time columns with alternating slurry flows (combination of co- and counter-current flows) are developed and commercialised. Unique multi-sectional cells having a number of essential advantages compared to monocells are developed. Design features of the cell allow: implementation of different flotation process flowsheets in a single unit, improved beneficiation process results, reduced specific power requirement, and elimination of sludging of the aerator and cell bottom part. Operational problems restricting introduction of column cells are connected with the aeration unit. The new cells are supplied with pneumohydraulic and stepped airlift spargers, allowing control of bubble size distribution with a service life of not less than three years. Successful operation of the new generation of columns with cell volumes of 15, 25, 40, and 80 cu m and the height of 5 - 6 m in copper, molybdenum, antimony, tungsten and nickel ores and coal slurry processing at different plants in this country illustrated their considerable process and operational advantages and verified the proposed options and relationships. A simulation technique of the flotation process and models for the solution of various problems are developed. A modular model of column flotation is constructed taking into account the kinetic relationship of the process and the hydrodynamic regime in the cell. Based on this, a technique of calculating the column parameters based on laboratory tests is developed (scaling-up), and applied for calculating the design of commercial-scale columns is developed.

Jan 1, 1993

By D Craw

The Rise and Shine Shear Zone is a mineralised low angle deformation zone traceable for at least 7 km through biotite zone schist of the Dunstan Range, central Otago. Rocks from the shear zone obtained from recent drillholes are unweathered and facilitate paragenetic studies. There is a progression of mineral deposition from semiductile foliation-parallel shearing, to subsequent folding, and brittle fracturing. Sheared rocks are dominated by microshears containing fine grained hydrothermal muscovite and rutile that has recrystallised from metamorphic muscovite and titanite respectively. Euhedral pyrite occurs within segregations in the schist and is locally brecciated by the shears.   Arsenopyrite occurs within microshears and is intergrown with hyrothermal muscovite. Fractures within relatively undeformed schist are filled with ankerite, siderite, chalcopyrite, sphalerite and galena and these veinlets also crosscut the microshears. Locally the schist is folded and zones of brecciation, silicification and vein deposition overprint the rock. Vein quartz and albite predominate and arsenopyrite and gold infill breccia matrix and crosscutting veinlets. Sulphide deposition began in the later stages of metamorphism with pyrite deposited in quartz-albite segregations. Subsequent shearing caused brecciation of some grains and accompanied deposition of arsenopyrite ¦ gold and rare sulphides along foliation-parallel microshears. Minor amounts of chalcopyrite, sphalerite and galena were then remobilised in ankerite veins that crosscut the shears. In areas of high strain, arsenopyrite was then deposited as euhedral grains in veins and breccias. Synmineralisation deformation caused the brecciation of some grains and gold was deposited infilling fractures in the arsenopyrite. The paragenetic sequence shows gold mineralisation occurred in two distinct sets of structures (semiductile and brittle) that formed at different times in the formation of the shear zone.

Jan 1, 2006

An Integrated Solid Waste Management Method for Western Macedonia, Greece

Sep 13, 2010