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By S Hapugoda

Iron ore oxide and oxyhydroxide minerals such as haematite (eg various types of martite and microplaty haematite), different forms of goethite, magnetite, hydrohaematite and kenomagnetite were analysed using optical microscopy, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) techniques, to determine the type and proportion of deleterious elements present and the chemistry of associated gangue minerals. The aim was to characterise elements potentially deleterious for agglomeration and steelmaking, eg sulfur, phosphorus, aluminium and silicon and correlate their distribution with mineral texture and association, to provide feedback on downstream processing performance and product quality.Examples of characteristic mineral associations are shown from various genetic styles of iron ores, including magnetite banded iron formation (BIF), BIF-derived martite-goethite and skarn-type magnetite ores.A number of examples are presented demonstrating the benefits of the use of combined techniques of reflected optical microscopy, SEM and EPMA data to reliably identify ore and gangue minerals and their associations in different types of iron ores.

Jul 11, 2011

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

Validation and Application of Filtration Theory to Plate and Frame Pressure Filtration - From Laboratory to Full Scale

Sep 13, 2010

By B R. Castley

Consumable materials used in mines are often transported to the working areas down shallow angle decline shafts, typically at anywhere between 10¦ and 30¦ to the horizontal. The winding equipment is usually a relatively small single-drum winder and the material is transported in one or more cars, running on rails in the decline. The winding rope is attached directly to the cars, which are mechanically coupled together. For small rock hoisting declines, the cars are replaced with hoppers or skips. The winder is normally of basic design, fitted with only the minimum required safety devices and very elementary brake control. Since these winders are not ælicensedÆ and are usually located in remote areas, the standard of maintenance on the installations is often poor, leading to frequent accidents, resulting in runaways, derailments and broken ropes. These problems can be overcome easily with the application of the rope haulage principle. When large volumes of ore have to be transported to surface, belt conveyors are used on shallow angle inclines, or high-capacity friction winders are used in vertical shafts. Conveyors are limited to inclines no steeper than 14¦ and vertical shafts with large friction or drum type winders are extremely capital-intensive. Rope haulage systems can be used on decline shafts where the inclination is too steep for belt conveyors and too shallow for conventional drum winders. Rope haulage systems also offer a variety of safety, technical and cost advantages over other winding and transport systems. This paper describes the adaptation of the rope haulage principle to modern requirements and, combined with 21st century electronic technology, explains how the principle can be used as an efficient, safe and practical solution to some problems associated with the transport of materials, personnel and ore in mines. The authors describe the designs, methods of operation, safety aspects, automated control, loading and unloading facilities of modern rope haulage systems used for transporting personnel, material and ore. This paper considers a variety of systems already designed for different applications, from small material-only installations to multi-purpose and large rock-hoisting systems with payloads as much as 180 t. It also describes in more detail, a material transporting system recently commissioned in South Africa.

Jan 1, 2005

By E Gabriel, J C. Koppe, A Gomes and P Crispim, R Schaarsdmit, I Pablos

Drill and blast (D&B) is one of the most important production operations in open pit mining. The resulting fragmentation of the D&B reflects in the downstream unit operation. Good fragmentation of the ore will minimise the cost of loading, hauling and crushing. The understanding of the geological model integrated with a software system for bench face surveying and planning of blast layouts based on three-dimensional images can help to achieve the fragmentation goals of the mine operation. A case study integrating these tools was carried out in a large iron mine in Brazil. The iron ore in the study area consists of hard and friable itabirites. More than three different ore types may occur on the same bench. Under these conditions, data integration becomes necessary to improve the results of blasting. A blasting plan was based on the generated geological model. The methodology helps understanding the factors that can interfere in the fragmentation process, allowing defining actions that can improve the blast design in those places that fragmentation wasn’t achieved. This condition is important for a continuous improvement of the drilling and blasting operation. In comparison with the previous blasting carried out at Itabira mine, which did not take into account the geological model, substantial improvements in fragmentation were observed, eliminating the need for secondary blasting.CITATION:Schaarsdmit, R, Pablos, I, Koppe, J C, Gabriel, E, Gomes, A and Crispim, P, 2015. Geological modelling and bench face survey to improve blasting fragmentation, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 401–406 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By A Späth

Active explosion barriers are used to contain and suppress a methane gas and/or coal dust explosion propagation, including localised mine fires. Early research indicated that these active explosion barriers could be used on a mechanised cutting machine, making it the only technology that could suppress an explosion during its propagation phase at the cutting face. Thereby not only adding protection during mining operations but also reducing the development of toxic gases, fatal temperature increase and fatal overpressure build-up. During their evolution over the last two decades, further advantages of Active explosion barriers were proven in mine operations in countries such as South Africa and China. Characteristics such as effectivity, efficiency, mobility and space restrictions allow these systems to be used in various locations within a mine operation, including highwall operations. This improved technology contribution to safer coal mining was recognised by mine operators, workers and regulators. The Queensland’s Recognised Standard 21 (Resources Safety and Health Queensland (RSHQ), 2021) stipulated active explosion barriers as a technology to ensure the safety within their underground coalmines. The mobility and flexible implementation of the active explosion barriers allow a feasible and practical solution for all critical locations for explosion and fire management in an underground coalmine. The conformance to the Recognised Standard can be achieved all underground coal mining operations such as Bord and Pillar, and Longwall mining. This paper describes the conformance, implementation and use of Active explosion barriers for Longwall mining and development as well as Bord and Pillar mining in Queensland’s underground coalmines.

Oct 12, 2022

A Simulation Study on Two-Stage Grinding with High-Pressure Roller Mills By the application of high-pressure roller mill (HPRM) in the field of mineral processing, computer simulation can be used to predict overall performance of a grinding circuit based on data obtained from HPRM comminution test in pilot scale or industrial scale. Using the model developed by Klymowsky and Liu for HPRM comminution and an extended Plitt's model for classification, steady-state of a closed circuit grinding can be calculated by means of a virtual locked-cycle-test conducted on computer. This paper presents the result of a simulation study on two-stage grinding with HPRM as the comminution device. The emphasis is put on the influences of circuit-configuration and way of recirculating classifier's coarse-product on the overall circuit performance. The results show that two-stage grinding with HPRM has its merit and flexibility in meeting demands of various grinding tasks in mineral processing.

Sep 13, 2010

By S Januszewski and, G Dirom, D Christensen

Four field test plots were constructed in 1998 on a sloped waste rock surface at the Myra Falls Operations of Boliden Westmin (Canada) Limited to evaluate hydraulic performance of alternate cover system designs. The field test plot cover systems were designed to control oxygen ingress and water infiltration to the underlying waste rock while providing a medium for a grass and legume vegetation cover. The test plots consisted of a bare waste rock surface (control plot), and three additional plots consisting of native compacted till placed directly on the waste rock surface, overlain by non-compacted till. Two of the test plots included a compacted till layer ameliorated with flyash and bentonite, respectively, to improve moisture retention and reduce permeability. The third test plot consisted of a compacted layer of native till overlain by non-compacted till. A performance monitoring system was installed in each test plot to evaluate net percolation and oxygen ingress to the underlying waste rock. In addition, each test plot has profiles of matric suction, water content, and temperature sensors installed at up-slope and down slope locations. A review of four years of monitoring data shows that the compacted till/bentonite cover system has been most successful in limiting the infiltration of meteoric waters and oxygen ingress to the underlying waste rock material. The compacted till/flyash and compacted till cover systems have produced similar net percolation results and neither have functioned well in maintaining an oxygen ingress layer throughout the year. The amelioration of bentonite with till to produce a compacted barrier layer shows promise in reducing water and oxygen ingress at the MFO site, while the incorporation of flyash with the till did not result in a significant increase in performance. The field performance data clearly demonstrates the need for developing field trials prior to full-scale construction, as opposed to relying solely on an un-calibrated numerical modelling to design the full-scale cover system.

Jan 1, 2003

By A Parbhakar-Fox, B G. Lottermoser, N Fox

"Determining the deportment of economic and environmentally significant elements in sulfidic mine materials (eg ore, gangue and waste) requires the use of advanced microanalytical techniques, including electron microprobe analysis (EMPA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Sulfidic boulders were sampled from an acid rock drainage impacted ephemeral stream adjacent to historical copper-silver workings at Baal Gammon, northern Queensland. The abundance and deportment of a range of trace elements and precious metals were analysed in these samples. Whilst many of these elements represent a potential environmental risk if leached from sulfidic rocks into streams in the surficial environment, significantly some of these elements (eg In, Sb and Co) represent specialised metals that are currently considered to be in critical supply.Sulfidic waste rock material at Baal Gammon is dominated by chalcopyrite, arsenopyrite, pyrrhotite and pyrite. Microanalytical investigations revealed that chalcopyrite contains significant quantities of In, Sn, Ag and Zn either substituted directly into the crystal lattice or occurring as discrete sphalerite and stannite inclusions. Arsenopyrite, which may comprise more than 50 per cent of some boulders, is notably enriched in Sb, Co and Ni but also contains inclusions of sphalerite, chalcopyrite and stannite. In contrast, pyrrhotite contains no trace elements of economic significance, but instead represents a likely contributor to acid generation during oxidation in the surficial environment. Trace metals (eg In, Sb, Co, Ni, Zn) are liberated during sulfide oxidation of these boulders in the surficial environment, generating a metal-rich, low-pH leachate.Fe-oxides precipitated as rinds on the surface of these boulders under low pH conditions also contain abundant As, Bi, Sn, Cu and Zn. Abandoned or historical mines represent potential sources of metalliferous drainage that poses potential environmental risks to water and habitats. However, sulfide-rich historical waste rock, stockpiles and processed waste (eg tailings) at abandoned mines may also represent significant sources of critical (eg indium) or other significant metals (eg Sn) that if liberated economically could improve environmental conditions in and around abandoned and historical mines.CITATION:Fox, N, Parbhakar-Fox, A and Lottermoser, B G, 2016. Critical and Deleterious Metal Deportment in Sulfidic Waste Rocks, Baal Gammon, North Queensland, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 173–182 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By M Scoble

This paper is based upon the experiences of collaborating academics in two mining schools and their personal view of attempts to integrate the principles of sustainable development into mining education and research. In this quest, the concept of sustainable mining practices is proposed, not only relating to environmental, social and economic performance but also stressing mine safety and efficiency. These practices need to support strategies that enable flexibility and resilience within mine operations to counter recessionary cycles. Also, these counter-cyclical strategies are now imperative for sustaining mining education and research itself. There is a critical interdependence between these two different perspectives on æsustainabilityÆ. The paper concludes by demonstrating models of strategies that promote inter-disciplinarity, collaboration and networking for sustaining mining schools.

Jan 1, 2009

By R J. Mills, B S. Sinclair, D A. Fergusson, A G. Goldstone

In 2005, Solid Energy New Zealand Limited obtained non-notified consent for the disposal of 1Mt of coal ash at the Rotowaro minesite, forming part of a coal supply agreement with the Huntly Power Station. The consenting of major mine site activities has historically required wide consultation and involves notification of the application.   The risk and cost associated with consultation can be significantly reduced via a non-notified process. A non-notified consenting process necessitates environmental effects to be shown to be æless than minorÆ, which requires the combination of robust science and a pragmatic approach to design, assessment of environmental effects, and consenting issues.   Key issues examined included consideration of how to practically operate a significant disposal project within the confines of an operating mine, minimising the costs, civil and geotechnical design and practical issues associated with traditional disposal. Environmental issues specifically related to the coal ash, led to a site specific performance driven approach to management rather than relying on conventional prescriptive approaches. Environmental issues of concern include the leaching of boron and aluminium from ash into groundwater and mine water management systems where both boron and aluminium can occur at elevated levels.   Coal ash exhibits unusual geochemical characteristics reflecting the primary coal composition and the combustion process. The dominant coal type combusted at the Huntly Power Station is derived from Rotowaro and the resulting ash is cementitious and has a high alkalinity. As a result the disposal design is based on the characteristics of the ash itself rather than the material into, or onto which the ash is disposed. Non-notified status was able to be achieved through consideration of these key characteristics of the ash, ensuring that the dimensions of the disposal site and each location was designed to minimise the flow of groundwater through the ash and demonstrating that the physical ash disposal effects are less than minor compared to the consented mining operation.

Jan 1, 2006

By N Clarke, J Hunt, A Barros, N Guerrero, L Keeney

Grade Engineering® (GE) involves a range of integrated technologies and operating protocols for improving effective feed grade through early rejection of low value material prior to costly processing activities and has the potential to transform the economics of large, low grade, mining operations. Extensive GE test work by AngloGold Ashanti (AGA) and the Cooperative Resource Centre for Optimising Resource Extraction (CRCORE) determined that the Gramalote gold deposit in Colombia is highly amenable to implementation of grade-by-size screening to upgrade the ore at a production scale. To understand the relationships between geology and the upgrade response drill core and bulk samples were analysed at the Centre for Ore Deposit and Earth Sciences (CODES) as part of a larger CRCORE project to understand geological controls on grade-by-size deportment, i.e., the tendency for specific mineral phases to preferentially fractionate during breakage into different size fractions. This work is focussed on understanding the role of mineralogy and texture in influencing rock breakage and natural fractionation at a range of scales. Detailed logging of Gramalote drill core and mineralogical analyses including hyperspectral logging, portable and bench-scale X-ray fluorescence (XRF), plus low resolution Laser Ablation of intact drill core pieces, combined with data from site (drill logs, geochemistry, petrophysics) were used to evaluate the ore and alteration mineralogy, vein paragenesis and textural variability. This provided information on gold deportment and allowed the identification of favourable host veins. Bulk sample material from different ore grade zones was also analysed. A comparison with the results of GE testing shows that positive upgrade results are produced by rocks with abundant veins, particularly those associated with potassic and/or white mica alteration. This work indicates upgrade response can be predicted from drill core using data collected by a combination of automated systems including hyperspectral data, XRF, and detailed drill core logging.

Nov 10, 2020

By J Planner

As Australia’s coal and iron ore export volumes increase to meet international market growth, port terminals, mining operations and rail transport systems can be the source of increased dust emission. Current and future sustainable expansion must minimise dust emission from bulk handling and transport operations located in close proximity to residential areas. Lower level dust emissions can be controlled by operational measures such as water addition to products, and use of water spray on stockpile surfaces. Recent research has shown that higher levels of dust emission can be more effectively controlled by understanding and treating the dust characteristics of each individual bulk product. Application of this research, progressively being applied at Australia’s coal and iron ore port terminals and rail transport systems, is achieving compliance with health standards and minimising dust nuisance effects to an acceptable level.

Nov 22, 2011

By P Hofmeyr, D Pretorius

Iron ore, which is transported by rail from the iron ore mines at Sishen in the Northern Cape, to the Saldanha Iron Ore Terminal in the Western Cape, needs to be analysed while loading to be exported. Every shipment will be sampled and an average analysis of the ore will be produced which is required by the purchaser at the receiving port. On arrival at the iron ore terminal at Saldanha, the ore is tipped from the rail trucks onto conveyor belts to be either stockpiled or direct-loaded. The conveyor belts run under the sampling plant and the ore is sampled periodically by means of an automated cross-belt sampler. This is the first iron ore port sampling facility in which the automated sampler is situated above the conveyor belts and not adjacent to them. A portion of the primary sample taken off the belt is moved to the dedicated sampling laboratory situated behind the cross-belt sampler and over the conveyor belt lines. The sample is split in the laboratory, one split being used for moisture and particle size determination and the other part is dried and then analysed by means of X-ray fluorescence spectrometry (XRFS) on fusion beads for major and minor elements. Particular care is taken to obtain high quality data for penalty elements.This sampling plant is completely automated and from the primary cross-belt sampler to final analysis by XRFS no manual steps are involved. This has meant that some processes are used which are suitable for automation and are ISO compliant but not necessarily ISO-certificated. The ISO manuals were developed with manual laboratory processes in mind. Precautions are also taken to maintain the integrity and representativity of the samples. This paper is a case study?describing?the automated sampling systems used at the Saldanha Iron Ore Terminal sampling facility and laboratory from conveyor belt to analysis.CITATION:Hofmeyr, P and Pretorius, D, 2012. Automated sampling of iron ore for analysis at the Saldanha Iron Ore Terminal in South Africa, in Proceedings Sampling 2012 , pp 25-32 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

Whether you are an employee, contractor or consultant working in the mineral industry, there are pressures to deliver the best possible performance. Technical professionals are usually driven by an internal desire to perform to a high standard because of personal pride in their profession, but there are an increasing number of external requirements to demonstrate that the actions taken were based upon reasonable grounds and that the work conformed to current best practice. People expect these best practice procedures to be followed and governments are now requiring those tendering for contracts to be registered in some way and to be participants in quality assurance schemes. One is not immune to these pressures just because you are working in a less legislatively sophisticated developing country in the circum-Pacific rim (pacrim) region.   Among the external pressures are the general ethical requirements of the professional body to which the person usually belongs, e.g. The Australasian Institute of Mining and Metallurgy (AusIMM), which are further elaborated upon in various Codes and Guidelines on specific matters, e.g. JORC (ore reserves reports) and VALMIN (assessment and valuation reports). These are outlined and discussed. Also, AusIMM's Chartered Practicing Status (CPS) Proposal is outlined in the context of other Pacrim countries approach to registering of technical professionals, which is a way of ensuring that minimum standards of qualifications, experience, competence and repute are demonstrable to ones employer (or client), peers and the wider community, including government.   Today, in the external working scene, there are many laws (particularly those applicable to the corporate and environmental spheres), with which contractors/consultants and even employees must fully comply, or else face criminal sanctions involving huge fines and imprisonment. These, too, are outlined and discussed. One must be able to mount a due diligence defence to avoid or mitigate these consequences.   Personal liability in the context of the day-to-day performance of one's duties has thus become a major concern to the technical professional and the ways in which it can be ameliorated, or insured against, are described. However, for some mineral industry practitioners, the problem is exacerbated because. of their general ignorance of the extent of their personal liability exposure. This paper intends to address this ignorance and to heighten general awareness of personal liability issues, as well as proposing some simple ways to limit this liability.

Jan 1, 1995

Remote sensing, in general, is the recording of light and heat from a planet's surface within a certain range of the electromagnetic spectrum. For the Earth, systems capable of this recording are the MultiSpectral Scanner (MSS) and SLAR. The former is the recording system used in satellite and will be discussed in the next section. SLAR stands for Side Looking Airborne Radar. This device sends invisible radar waves which illuminate the Earth's surface. The reflected waves are subsequently recorded as images. The system can operate through darkness and dense cloud cover, and is particularly suited for the study of geological structures at both large and small scale (Wayland 1976). Remote sensing techniques are now widely being made use of in mineral exploration, especially for those last remote 'sanctuaries' where geological data are meagre or non-existent. For places like Borneo, West Irian, the Amazon Basin etc. remote sensing, in the form of both satellite imagery and SLAR, is of considerable help, in fact more often than not the only help, to delineate geological provinces, geotectonic domains and meaningful lineaments. In the case of New Zealand, well made geological maps at scale 1:250 000 by the Geological Survey are available to the public and these provide useful preliminary grounds for the selection of target areas. However, even in this case LANDSAT imagery can be of aid as will be shown later.

Jan 1, 1977

By B Mohanty, D Zwaan

Systematic near-field vibration monitoring of stope blasts was carried out in a large, deep underground mine. A total of 31 production blasts were studied in order to investigate the effectiveness of existing blast designs. This involved the vertical retreat mining method, which requires drilling a raise bore or blasting a slot raise (typically 1.22 m in diameter) using large diameter boreholes (165 mm). The diagnostic technique employed multistation near-field monitoring of blasts with high-g (100 g) and high-frequency (>10 kHz) triaxial accelerometers. The amplitude of the vibrations is correlated with the strain energy transmitted from each explosive deck. The results showed that more than 30 per cent of the explosive decks contributed little energy to the rock breakage process in these blasts, and an equal number contributed only inadequately. These findings are indicative of serious blast malfunctions. The problems can be traced to inadequate deck blast design and possibly to drill hole deviation. The various causes for such malfunctions are discussed and remedial measures suggested.CITATION:Mohanty, B and Zwaan, D, 2015. Assessment of underground production blast designs and blasting performance, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 607–616 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By N Elith

Coal is a valuable energy source in New Zealand and has been mined from the West Coast for over 100 years. Stockton Mine is New Zealand's largest opencast coal producer supplying around 1.5 Mt of hard coking and thermal coal to international markets annually. The Stockton Plateau forms an extensive, gently inclined dip slope on erosion resistant Lower Eocene Brunner Coal Measures unconformably overlying basement rocks. The dip slope rises 600 - 1000 masl, locally dissected by fault scarps and present-day fluvial systems, some of which are deeply incised. Within the Mt Augustus Mining Block overburden comprises of a 30 - 40 m thick sequence of fluviatile, coarse to granular coal measure sandstones. High quality coking coal is preserved as a gently dipping, 10 - 12 m thick seam. High and sometimes very steep cliffs of jointed overburden shape the skyline escarpment, above steep forested slopes and gullies. As mining has progressed at Mt Augustus individual coal blocks are progressively becoming more technically challenging. This paper outlines the scientific approach taken by Solid Energy International and mining contractors to carefully unlock many thousands of tons of coal whilst protecting nearby flora and fauna from the impacts of dislodged rock and other blasting side-effects. The strategy involved: an expert-driven onsite risk assessment,formulation of a management plan to manage impacts,conducting an in situ vibration research program, andanalysis of results and operational designs to eliminate potential environmental problems.

Jan 1, 2003

By P Lindsay, J B. Hughes

Underground and opencast coal mining has been ongoing since 1896 on the Stockton Plateau, West Coast, New Zealand. Acid Rock Drainage (ARD) from historic and current mine workings has had an adverse environmental impact on the surrounding aquatic environment. The two main catchments affected by ARD are those of the Mangatini and St Patrick streams. These catchments flow into the Lower Ngakawau River, which holds high amenity value for the local community. Water quality targets set by Solid Energy for 2010 in the Ngakawau River include increased pH and clarity and a decrease in certain dissolved metals.   At-source ARD minimisation options are the first stage in mitigating the effects of mining acid forming rocks and reducing acid loads in the Mangatini and St Patrick stream catchments. ARD minimisation techniques reduce the quantity of acidity generated and thus reduces the treatment required. Treatment will be required for many years at Stockton due to current and historical acid formation. This paper looks at the treatment options that Solid Energy has been investigating including limestone leach beds, engineered wetlands, oxic limestone drains, and limestone dosing of catchment drainage. Particular focus is given to fine limestone dosing of the Mangatini stream and subsequent water quality improvements.

Jan 1, 2007

Extraction under very mild conditions - a few minutes at room temperature with poor solvents - yields results characteristic of surface properties for a variety of coals. Such superficial extractions preferentially remove long-chain aliphatic compounds. As coal becomes more oxidized, less of these yellow- colored compounds is extracted, forming the basis for a simple colorimetric test for coal surface quality. The fact that these aliphatic compounds are responsible for surface hydrophobicity is supported by good correlation between extraction results and floatability, which decreases with decreasing extractability. This extraction test is very sensitive to oxi dationb even the effect of heating for an hour at 100 C can be detected. A second extraction test using mild alkali conditions has shown good correlation with plant dewatering Operations.

Jan 1, 1986