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By Chander S

Properties of surface films on chalcopyrite and pyrite differ due to variations in the mechanism of oxidation of the two minerals. In the case of chalcopyrite the first step in the oxidation is the release of iron as ferric ions, which hydrolyse depending upon conditions prevalent in solution. The iron oxide/hydroxide layer formed by hydrolysis of ferric ions is quite porous and easily detachable from the surface of chalcopyrite. When the surface oxide layer is detached a sulphur-rich layer is exposed making chalcopyrite hydrophobic. The thickness and properties of the sulphur-rich layer determine its flotation response, both in the absence and presence of collectors. In the case of pyrite, on the other hand, iron is released as ferrous ions which require much higher pHs to hydrolyse. These ions remain adsorbed on the surface of pyrite making the surface hydrophilic. When the iron species are complexed with chelating agents such as ethylene diamine tetra acetic acid, pyrite was hydrophobic. Siderite forms in the presence of carbonate ions, which might be present in several flotation systems. Siderite nucleated on isolated sites at the surface. The presence of such a precipitate is likely to influence the interaction of pyrite with various reagents thereby altering its flotation behavior. To determine the mechanism of oxidation, kinetics of oxidation of chalcopyrite and pyrite was studied using several electrochemical techniques, namely, cyclic voltammetry, polarisation and impedance spectroscopy. Floatability of the minerals was investigated by measurement of contact angles on mineral electrodes and by Halimond tube flotation. Impedance spectroscopy was especially useful for estimating various properties of surface film for both the minerals. Properties such as charge transfer resistance, porosity, and capacitances of the surface films on the two minerals are compared under several conditions of oxidation. These properties were found to be a strong function of the rate and the extent of oxidation.

Jan 1, 1993

By Armstrong M, Kleingeld W. J

Current low prices for many metals mean that deposits have to be mined at high cut-offs (relative to their mean grade), which means that only a small percentage of mining blocks are above cut-off. Worse, at such high cut-offs, the blocks above cut-off are usually not grouped into convenient clumps for mining; they tend to be split into small isolated patches that are difficult to reach and hence expensive to extract. Companies wishing to acquire mineral properties have to be able to work out quickly what percentage of blocks are above cut-off and what can effectively be mined given the mining method envisaged. Moreover they need this information within a relatively short-time. The work presented here relates to typical South African gold mines (ie tabular orebodies) but the long-term objective is to develop tools for quantifying the impact of reserve breakup at high cut-offs for a wide range of underground mines including those that are not tabular. The mining method and the sampling procedure determine whether ore blocks can effectively be located and extracted economically. This project studied the impact of these two factors on the recoverable reserves for Witwatersrand gold mines. In order to be repeatable, the tests were done on numerical models of the deposit obtained by geostatistical simulations. To ensure realism, the orebody model and the mining scenarios were based on a specific mine. The recoverable reserves (ore tonnage above cut-off, the corresponding metal quantity and the average grade) were calculated for a wide range of cut-offs for four mining scenarios, as well as for the base case of free selection: ò Scenario 1: Blocks are taken if their true grade is above cut-off and if they are accessible from a raiseline (no information effect, no marginal blocks). ò Scenario 2: In addition to the accessible pay blocks, adjoining marginal blocks are taken (no information effect, + marginal blocks). ò Scenario 3: Blocks are taken if their estimated grade is above cut-off and if they are accessible from a raiseline. Here the estimator is the average of the face samples (information effect, no marginal blocks): ò Scenario 4: Accessible pay blocks are taken if their estimated grade is above cut-off. Adjoining marginal blocksare also taken (information effect, + marginal blocks). ò Free selection: All blocks whose true grade is above cut-off are taken irrespective of their accessibility. The results can be presented in different ways, for example by plotting ore tonnage above cut-off versus cut-off grade, or metal tonnage above cut-off versus cut-off grade etc. As expected, this shows the hierarchy between the five scenarios from the free selection base case to scenario No 2 (true accumulations, pay +

Jan 1, 1995

When lying over 200-250m depth, many seams and surrounding strata are gassy enough to create mining difficulties , particularly in highly productive longwalls as well as in their development headings. In addition to the gassiness of seams or stra- ta in the outgassing volume around working, the shape expansion and limits of this one influences much the intensity of gas emission. These charac- teristics of outgassing volume differ very much ac- cording to the permeabilities of the seams and strata encountered by their fracturation due to mi- ning. Moreover, the shape of the outgassing volume is very much modified by the rate of advance of the face. In nearly impermeable deposits, gas flows from a limited outgassing volume. When the rates of advance of a face are medium or low, the shape and dimensions of this volume do not change very much and outgassing volume is translated progressi- vely with the face advance. This explains why, in the past, it was observed that there was for each seam an average steady specific emission of gas, round which the volume of gas evolved per mined ton or per mined unit area, calculated over a cer- tain time, was oscillating. Combined with a statisti- cal irregularity coefficient, this allowed prediction gas of emission and thus to take decisions for air ventilation, drainage, and eventually production.

Jan 1, 1988

By A Woodley, G Keir

The mining industry faces concurrent pressures of reducing water use, energy consumption and greenhouse gas (GHG) emissions in coming years. However, the interactions between water and energy use, as well as GHG emissions have largely been neglected in modelling studies to date. In addition, investigations tend to focus on the unit operation scale, with little consideration of whole-of-site or regional scale effects.This paper presents an application of a hierarchical systems model (HSM) developed to represent water, energy and GHG emissions fluxes at scales ranging from the unit operation, to the site level, to the regional level. The model allows for the linkages between water use, energy use and GHG emissions to be examined in a flexible and intuitive way, so that mine sites can predict energy and emissions impacts of water use reduction schemes and vice versa. This paper examines whether this approach can also be applied to the regional scale with multiple mine sites.The model is used to conduct a case study of several coal mines in the Bowen Basin, Australia, to compare the utility of centralised and decentralised mine water treatment schemes. The case study takes into account geographical factors (such as water pumping distances and elevations), economic factors (such as capital and operating cost curves for desalination treatment plants) and regional factors (such as regionally varying climates and associated variance in mine water volumes and quality).The case study results indicate that treatment of saline mine water incurs a trade-off between water and energy use in all cases. However, significant cost differences between centralised and decentralised schemes can be observed in a simple economic analysis. Further research will examine the possibility for deriving model up-scaling algorithms to reduce computational requirements.CITATION:Keir, G and Woodley, A, 2013. Regional trade-offs between mine water and energy use - a water treatment case study, in Proceedings Water in Mining 2013 , pp 21-28 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By Cudmore JF, Rowlands D

Incidents associated with spontaneous combustion of coal have resulted in the loss of many lives and considerable capital and equip- ment. Nevertheless, the factors controlling the propensity of coal to spontaneous combustion are not clearly understood and there is a need for research to study the effects of rank, petrog- raphy, moisture contents, etc. This has been attempted in a study of the propensities of selected Queensland coals to spontaneous combustion. An adiabatic calori- meter was constructed to study the self-heating of a large number of coals. Chemical and petro- graphic analyses of the coals were determined and an attempt was made to relate these propert- ies to the self-heating characteristics of the coal. The results show a strong relationship between rank and self-heating characteristics and that petrographic composition of coal may also be of importance. Some observations on the application of the laboratory results to the practical situation are made as are recommendations for future research.

Jan 1, 1981

By McNabb KE, Ward B, Dyer G

Roof conditions at Southern Colliery, the second longwall mine to be established at German Creek, were found to be much stronger and more massive than at the earlier longwall mine on the lease. Investigations were made to ascertain the level of face support required for longwall extraction under the changed geological conditions. Geotechnical information was provided from drillholes and highwall exposures. Downhole geophysical logs, notably the sonic velocity log, were used to obtain a distribution of the major lithological units over the mine area. A representative type section of the strata and geomechanical properties was compiled to form the basis for numerical modelling. Two-dimensional finite element methods were used to predict strata movements and chock loads under cantilevered roof conditions. The model incorporated a 6.3 in thick roof beam either bonded or detached, with either a 2 in or 5 in overhang. The solid rib, immediate roof, chock support and goaf were modelled as distinct parts, in addition a front abutment stress profile, derived from three-dimensional displacement-discontinuity analysis, was superimposed on the model.

Jan 1, 1992

There is no other effective way for study ing firedamp and coaldust explosions than to produce controlled explosions in a pre-monitor- ed environment - either mine openings kept for the purpose, or special surface galleries. Such explosion testing facilities have been employed historically at Buxton in U.K., with lesser known installations at Bruceton, U.S.A., Tremonia, West Germany, Katowice-Mikolow, Poland and elsewhere. Both firedamp and coal dust explosions are studied. Normally coal dust explosions are initiated by somewhat standardised methane air mixtures, by explosives, or purely by coal dust. Various structures and suppression installations are installed in roadways and galleries prior to explosion to simulate destruction and suppression, and the results of such tests form the basis of suppression installations, especially stone dust barriers and water barriers. Other data collected from these experiments include rev- ersals of explosion waves, pressures and temperatures and duration of explosion waves, analyses of aftergases etc. Other uses of explosion testing galleries include testing of explosives, electrical equipment and frictional . sparking.

Jan 1, 1981

By M Battersby, F Parra, S Sanchez-Pino

Pneumatic flotation, as developed by Dr Rainer Imhof, has been applied in commercial beneficiation operations since 1987. Over 85 flotation cells have been installed in more than 30 operations, successfully beneficiating a wide range of minerals. Pneumatic flotation is however still considered as a non-conventional flotation process. Due to its highly selective nature in operation it has generally found its market in difficult applications where conventional flotation equipment has struggled. Compa±fa Minera Huasco (CMH) operates an iron ore pellet plant in central Chile. CMH desired to produce a low silica pellet for the export market where the SiO2 grade should not exceed 1.5 per cent. It is common practice in other countries to float quartz from hematite with relative ease. However, the silicates contained in the magnetite ore of CMH are only present as quartz in small quantities and the major undesirable silicates are difficult to float. CMH spent considerable time on developing a reverse flotation process and a reagent suite to try and reduce the silica content to acceptable levels. However, extensive laboratory and pilot plant tests with conventional mechanical tank type cells and with column cells failed to produce the required reduction in impurities. A series of tests with pneumatic flotation cells indicated that this type of flotation technology could achieve the required silica target. A 500 tph Imhoflot pneumatic flotation plant was subsequently constructed and successfully commissioned by CMH, making it one of the largest iron ore flotation plants in the world. This paper details the background and testing that was undertaken by CMH which led them to choose pneumatic flotation as the preferred process and compares the test results with that achieved in the industrial plant.

Jan 1, 2005

By J Brisebois

The derelict Lake George Mine is located at Captains Flat in NSW, acommunity of approximately 450, which lies some 43 km southeast ofQueanbeyan. It straddles the Molonglo River, which flows toQueanbeyan and thence the nationÆs capital, Canberra. Catastrophictailings dam failures in 1939 and again in 1943 resulted in the transportand dispersion of thousands of tonnes of sulfidic wastes downstream,with terminal settling in Lake Burley Griffin, in Canberra. The mine wasclosed in 1962, and major rehabilitation in 1996 - 1997 addressed the riskof further collapses, and reduced water flow into the underground mine.Nevertheless, acid mine drainage from the mine, and seepages ofcontaminated water from the capped tailings dumps continue to pollutethe Molonglo River for some 30 km downstream.Environmentally, the highest contributor to the total contaminant loadof the river is the Main Adit Spring. This was shown to be a constantgroundwater-driven acidic flow, with contaminant generation resultingalmost entirely from the ingress of gaseous oxygen into the undergroundworkings. Long term remediation may be possible at source, by pumpingreducing gases into the sealed mine, but the probability of thistechnology succeeding to the required degree is yet to be demonstrated. For at least the medium term, treatment of contaminated water flow(s)will be required to achieve any of the water quality targets that may beapplicable to the river. Three methodologies were short listed, but anumber of strategic uncertainties remain, which the NSW Derelict MinesProgram will address. Future risk arising from long-term contaminantrelease by the treatment wastes must be considered. Appropriate data,and realistic long-term performance parameters regarding the relativestabilities of water treatment sludges are scarce, and make properevaluation of competing technologies problematic.

Jan 1, 2003

By G W. Scott, H M. Lukey

The Lake Superior Region has been a producer of iron ore for over 150 years. Early mining operations concentrated on direct shipping ores, which are the result of post-depositional upgrading principally by deep weathering. As direct shipping ore reserves became depleted, the focus changed to the production of iron ore pellets from taconite. The post-depositional processes responsible for upgrading taconite are regional metamorphism, contact metamorphism and hydrothermal processes (Clout and Simonson, 2005). While these processes are important in iron ore genesis they can also contribute to liberation problems and in some instances reduced pellet quality (Han, 2004). Low-grade metamorphic mineral assemblages can negatively impact liberation and pellet quality. Low-grade iron formation may contain a suite of carbonate minerals including ankerite, dolomite, kutnohorite, siderite and magnesiosiderite. Variation in the distribution and composition of siderite and magnesiosiderite makes controlling the MgO content of pellets difficult. Carbonate minerals also require calcination in the pellet induration process, which requires additional heat to be added to the system, slowing down the induration process and reducing throughput. Prediction of carbonate mineralogy and carbonate mineral chemistry is an important goal of ore characterisation for pelletising properties. Contact metamorphism causes changes in mineralogy and grain size (Klein, 1973; Gunderson and Schwartz, 1962). Increasing the grain size of magnetite should improve its liberation characteristics. However, plant grinding targets may not allow the coarse-grained, more easily liberating magnetite ores to increase throughput and can actually result in decreased throughput due to recirculation. While magnetite and martite ores are well understood (Lukey, Johnson and Scott, 2007) late open-space filling microplaty haematite ores are not. These ores, while composed of similar minerals, have a unique genesis that results in fine grain size and complex textures that present liberation challenges and often make interpreting laboratory metallurgical test results more difficult.

Jan 1, 2007

By T A. Helms, P Gottlieb, S E, R Bateman

In response to the ever-increasing challenges facing the modern gold mining industry and the need for improved gold recoveries within all processing streams, CSIRO has upgraded its latest automated mineralogical analysis system, QemSCAN (formerly QEM*SEM), with special purpose hardware that speeds up the location and measurement of precious metal-bearing phases. By rapidly scanning the surface of polished blocks, and accepting only fields that contain the minerals of interest, QemSCAN is able to find, map, and quantify target minerals in extreme detail. Phase identification and quantification is achieved by placing a grid of points over the target particle and collecting X-ray information at each analysis point. The resulting mineral maps provide the metallurgist with a complete textural description of all gold-bearing phases within the product measured, together with quantification of the gold phases in terms of their modal abundance, particle size, mineral associations, relative contributions to gold deportment and liberation characteristics. Examples are presented which illustrate how QemSCAN is able to find and quantify gold-bearing phases within low-grade ores from the Super Pit, Kalgoorlie. This work is the result of a collaborative project between Kalgoorlie Consolidated Gold Mines (KCGM), CSIRO Minerals, and the University of Queensland, and is on-going.

Jan 1, 2000

By Wright R, Stock E. C

The Windarra nickel deposits known to date comprise two sulphide orebodies located at Mount Windarra and South Windarra. These orebodies, which are 15 km apart, lie within an ultramafic complex at or near its footwall contact with a banded iron formation. The Windarra deposits are 270 km north-northeast of Kalgoorlie in West- ern Australia which was the centre of a major nickel exploration programme fol- lowing the discovery of nickel deposits at Kambalda in 1966. Surface indications of the Mount Windarra orebody were discovered in 1969 by Mr. Ken Shirley while prospect- ing the Laverton area for Poseidon Ltd. (then NL). The mineralisation was loc- ated by systematic prospecting for goss- anous material associated with aero-mag- netic anomalies and ultramafic rocks. The South Windarra deposit was dis- covered in 1971 by the Union-Hanna- Homestake Joint Venture, by exploring along the strike extension of the mount Windarra ultramafic-banded iron format- ion contact. A detailed ground magnet 1. Acting Operations Superintendent, Windarra Nickel Project, Windarra, W.A. 2. Senior Geologist, Windarra Nickel Project, Windarra, W.A. 3. Mine Geologist, Windarra Nickel Project, Windarra, W.A.

Jan 1, 1973

By S Robson, T G. Blenkinsop, S C. Dominy

Golden Pig mine is in the central part of the Southern Cross greenstone belt within the Archaean Yilgarn craton. The mine has produced approximately 2.5 Mt of ore at 5.7 g/t Au to yield approximately 450 000 oz. The majority of gold mineralisation is hosted within extensively deformed and quartz-veined BIFÆs. In addition to the BIF-hosted mineralisation, an increasingly important part of the resource lies in the Taurus Lode, which is a N-NNW-trending amphibolite facies shear zone. The Taurus Lode lies within a continuous shear-zone that has a moderate to steeply WSW dipping foliation, and a mineral lineation of biotite, amphibole and pyrrhotite plunging consistently 10¦ S. Drive faces, subperpendicular to the foliation and lineation, consistently show evidence for syn-mineralisation reverse shear. Exposures parallel to the mineral lineation and perpendicular to the foliation reveal both sinistral and dextral asymmetries. These characteristics suggest that the vorticity axis of the Taurus Shear Zone is parallel to the mineral lineation, and that the simple shear sense is reverse. This geometry can arise when there is a major component of flattening across the shear zone, which may be due to interference between two adjacent granite domes. The BIF-hosted lodes plunge consistently 15¦ NNW coincident with the intersection of the axial planar cleavage of the regional folds and the Taurus Shear Zone. However, where the penetrative shear characteristics control the orientation and geometry of the mineralisation, oreshoots plunge SSW, parallel to the stretching and mineral lineations within the shear. The SSW plunge of strike extensive and laterally confined high-grade, economic ore shoots within the Taurus shear is fundamental to defining the economic mineralisation within this lode. Identifying the zones of maximum continuity and establishing the optimal position for future development will maximise ore extraction.

Jan 1, 2003

By Fiedler VA, Threadingham GM, Leckenby DF, Clarkson CJ

The Utah Development Company Research and Development Laboratory has embarked upon a programme of optimisation of the company's coal preparation plants. This goal is being accomplished in a three-fold manner - use of pilot plant equipment for optimisation and modelling of the various unit operations, evaluation or development of on-stream ash analysis for process control, and evaluation or development of alternative processes. In each of these areas, digital data acquisition- and at a later stage, process control feedback, is being extensively utilised, based largely upon the use of the HP85 and HP9915 desktop computers. A variety of input/output configurations such as HPIB, BCD, GPIO are used, and at times supplemented by microprocessors such as the Intel 80/05 to assist in data transfer. This paper will discuss a number of specific projects, especially in relation to the manner in which the variables are monitored, and the data later retrieved and analysed.

Jan 1, 1983

Degussa's PAL-system (peroxide assisted leach) has been proven to be more economical than the conventional cyanidation technique. Significant in- creases in the gold recovery have been reported, accompanied by savings in cyanide. Accelerated extraction kinetics and modified reagent demands necessitate a redesign of the conventional cyanidation plant. The South African Osprey Mine is presented as an example of a successful PAL-application. Based on the plant and laboratory data it is shown that the redesign of the flowsheet can be an important factor for the effectiveness of a metallurgical plant. In the case of the Osprey Mine, the PAL-technology all ows a modification of the current preoxidation-ClPcircuit to two separate CIL-plants to treat run-of-mine ore and old tailings dumps. A doubling of the throughput is possible without enlargement of the plant. This innovation in the field of gold extraction, the combination of the PAL-process with a redesign of the metallurgical plant, can be considered as a basis for a more profitable gold mine.

Jan 1, 1991

In the late 1970's Western Mining Corporation, Exploration Division considered the purchase of a major multi-element spectrometer as an adjunct to our existing atomic absorption spectrophotometers. The analytical work proposed for the unit included barium, uranium and rare earth elements from Olympic Dam, uranium, sulphur, vanadium and strontium on Yeelirrie type deposits, major element and whole rock analysis, multi-element analysis of samples from the laterite, chromium and manganese exploration programmes and tin and arsenic analysis. These were all analyses that were not readily or easily performed by flame atomic absorption or were where we expected that a simultaneous multi-element instrument would be an advantage. Also the turnaround times for the commercial laboratories was considered unacceptably long for some determinations. Other factors, important when considering the spectrometer were the ability to ensure confidentiality of results and the ability to assign our own priorities and not to have to rely on commercial laboratories. The two techniques considered were X-ray Fluorescence Spectrometry and Inductively Coupled Plasma Optical Emission Spectrometry. The decision was made in favour of the ICP unit for several reasons. The ICP fitted in with our existing methodology, ie samples digested for atomic absorption or colorimetric techniques would also be suitable for ICP analysis and vice versa. The technique was suitable for water samples and for major element analyses and for rare earth elements. X-ray fluorescence spectrometers were installed at the Kambalda and Belmont laboratories and would be available to us for routine checking and for elements not suitable for ICP analysis. The final consideration was price. ICP was considerably cheaper than XRF.

Jan 1, 1987

By Arit I, Adisoma G

General Limit Equilibrium Method (GLE) and Janbu's Generalised Procedure of Slices (GPS) are two limit equilibrium methods in slope stability analysis which satisfy all equilibrium conditions. Numerical difficulties associated with these metho

Jan 1, 1998

The Iron Prince orebody occurs within the Lower Middleback Jaspilite Horizon of the Middleback Group and consists of hematite within host rocks of jaspilites and schists. The ore was probably the product of leaching of silica from jaspilites and replacement by iron, concentrations occurring in suitable structural traps. The narrowness and the presence of extensive dolerite amphibolite dykes within the orebody make it essential to operate a grade control programme in advance of the faces. Information from drilling is drawn up on bench plans, step plans and impurity overlays, and these serve both in day to day production planning and in long term planning. Mining is done selectively by open-pit methods and blending conducted by keeping at least three faces of different grades of ore open at any one time. No stock piles of ore are kept for blending, but contact ore, contaminated ore and enriched material are dumped for later beneficiation.

Jan 1, 1971

By Motyka J, Adamczyk AF, Witczak S

A case study of migration of a paper factory fluid wastes, on the distance of 5 km from an underground disposal site to an ore mine is presented. The ore mine in question, situated in SW Poland is pumping 3.5 m3/s (ca 300 000 m3/day) of groundwater, producing a cone of depression about 150 m deep and several kilometers wide. The migration of wastes (pollutant) occurs within the carbonate karstic aquifer of Triassic age. The aquifer is about 100m thick and is characterized by the coefficient of hydraulic conductivity equal to 8 m/day on the average. The results of systematic measurements carried out for 13 years enabled to estimate the mean breakthrough curve of the pollutant. On this basis and taking into account the coefficient of hydraulic conductivity as well as the mean hydraulic gradient between the disposal site and the ore mine, the migration parameters of the polluting material, i.e. the real flow velocity, the effective porosity and the longitudinal disper- sivity have been calculated. As the measurements considered a long migration distance of the pollutant, the obtained hydrodynamic dispersion constant (dispersivity), in the authors opinion, is reliable enough to be applied for regional groundwater calculations, regardless of the "scale effect".

Jan 1, 1988

By Mack JF

A metallurgical evaluation of the Argyle Kimberlite No. 1 (AKl) orebody has been carried out using a 40 tonnes per hour pilot plant. Pilot plant results, together with laboratory investigations provided a basis for the determination of process design criteria for a major treatment plant. Various sampling programmes were carried out to determine specific aspects in the evaluation of diamond liberation. Treatment parameters such as the top crush size, recrush size and the bottom cut-off size were investigated. A description of the pilot plant is given together with the design criteria for a 3 million tonne per annum treatment plant

Jan 1, 1984