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By C J. Ptacek, J G. Bain, D W. Blowes

The passive interception and in situ treatment of groundwater using permeable reactive barriers (PRBs) has, within the past decade, become an accepted remedial approach to the control of plumes containing dissolved organic and inorganic contaminants. Since the first applications of the technology in the early-1990s, there have been several field-scale PRBs that have provided excellent treatment of dissolved metals in groundwater. Additional commercial applications and demonstration projects continue to be developed. Three field-scale applications and supporting laboratory columns have shown that several thousands of milligrams per litre of sulfate, more than 1000 mg/L iron, and several tens of milligrams per litre of other metals can be removed from groundwater by PRBs that promote sulfate reduction. The reactive materials, which incorporate various forms of organic carbon, promote microbially mediated sulfate reduction, the generation of hydrogen sulfide, and the subsequent precipitation of sparingly soluble iron and other metal sulfide minerals. Effective performance has been achieved by PRBs installed at a mine-tailings impoundment in 1995 (Sudbury, Ontario) and at an industrial facility (Vancouver, British Columbia). These PRBs have removed iron and other metals from groundwater. Similar materials were also used to create reactive layers within test cells directly in a tailings impoundment in 1999 (Timmins, Ontario) with the objective of removing iron and sulfate from the pore water before it migrates from the tailings impoundment. Zero-valent iron (ZVI) has been shown to provide excellent removal of chromium (VI) in a PRB, which was installed at the US Coast Guard facility in Elizabeth City in 1996, by reduction and precipitation reactions. Laboratory tests have also shown that ZVI reduces As(V) to As(III), which is subsequently removed from solution by co-precipitation with iron oxyhydroxides. In groundwater containing sulfate, ZVI and mixtures containing organic carbon can promote sulfate reduction and the subsequent precipitation of sparingly soluble arsenic and other metal sulfides. A trial PRB system was installed in 2001 and was shown to attenuate arsenic and other electroactive metals in groundwater at an industrial facility in northwestern Ontario. Basic oxygen furnace (BOF) slag, a waste material generated by the steel industry, has shown excellent potential for the removal of phosphate, elements such as arsenic and water-borne pathogens from groundwater in field and laboratory tests.

Jan 1, 2003

For several years, the Geology Department of the University of Canterbury has hosted a series of postgraduate projects in the field of coal studies, supported principally by the Ministry of Energy and to a lesser extent by private companies. These projects have involved mainly West Coast Coalfields, and my own studies have focussed on inorganic geochemical aspects of West Coast coals. Because of the large number of potentially important analyte elements in coal, and the wide diversity of coals occurring in the West Coast region, this project has required a substantial amount of work to be spent on sample collection, sample preparation, development of analytical methods, and actual analysis. Considerable problems must be faced at the sampling stage: Can sufficient information be obtained from whole-seam composites, or should seams be sampled in plies. Ply analysis is preferable, but results of proximate analyses are usually available for composites only. Where multi-seam drillhole samples become available (eg Greymouth Coalfield, where some holes yielded more than six sampled seams), the ply option involves a dramatic increase in the number of samples. I have attempted to strike a workable compromise between geographical coverage of coalfields, and detailed sampling of individual seams at each locality. In many cases, sample material has been used jointly with Jane Newman who has carried out petrographic studies.

Jan 1, 1985

By Goto T, Sato K, Mori N

A field investigation by making use of the seismic method has been carried out in order to comprehend the mechanism of rockburst and gas outburst and their predictive measures. The seismometers were so arranged both on the surface and underground as to enclose a mining panel. Seismic signals detected by the array were recorded and processed by the 32-kwords computer system. At present the system is available for analysing the source location and Richter's scale of each event and for visualizing the distribution of seismic foci and released energy at any mining stage. The magnitude distribution of events can be regarded as a comparable index of the seismic activities among mining panels. An analysis of the spatial density distribution of seismic energy in the mining panel can be useful to distinguish a highly stressed zone from stress released areas. The energy released curve or the rate of energy release determined from seismic data is also a good indication of the seismicity.

Jan 1, 1980

How many of you have felt tired and light-headed after standing or working in the sun or by the oppressive, hot, muggy conditions of an Australian summer? For those of you who have, you've experienced the minor effects of heat stress. Heat

Jan 1, 1994

By Young D. R, Webb I. D

The hydro-chlorination of Fe2O3 and Fe304 has been investigated in the range 850-950¦C in order to elucidate the role of iron in the segregation process for nickeliferous laterites. The kinetics of Fe203 chlorination using 20% HC1 - 80% N2 gas mixtures is consistent with a single-stage structure control model, whereas Fe3O 4 exhibits a two-stage reaction mechanism. Oxygen potential measurements using a CSZ probe located above the bed and X-ray powder diffraction results confirm the proposed reaction scheme. When a serpentine nickeliferous laterite (1.03% Ni - 11.7% Fe) was chlorinated at 900¦C with a 20% HCl - 80% N2 gas mixture it was found that the iron oxide in the ore was extracted in a similar manner to the synthetic iron oxides. Also, it was found that the nickel extraction from the ore paralleled that of the iron and the tests indicated that for the major part of the extraction, the solid nickel species were in equilibrium with the gas phase. The recovery of nickel from laterite ores by the segregation process has been investigated by a number of workers and several extensive reviews of the literature associated with this field have been published (Iwasaki, 1972; Canterford, 1975; Wright, 1973).

Jan 1, 1987

By Sivell W

We discuss the origin of the Patuki ophiolite complex and the Dun Mountain ultramafics of Middle Permian age in Nelson, New Zealand. It is shown that the Patuki volcanics have strong affinities with tholeiites of mid ocean spreading ridges transitional to alkaline basalts similar to those from fracture zones and ocean islands. At D'Urville Island, typically pillowed alkaline basalts enriched in rare light rare earth elements (LREE) - ophitic spilites - are associated with LREE-depleted (N-MORB-like) tholeiitic spilites with intergranular textures. The metabasalts are associated with a wide variety of sediments, and with sediments are intruded by conformable sheets of serpentinite. Coarsely crystalline mafic and plagiogranitic rocks signify vents and magma chambers, and we propose that the group developed as ocean crust from a slowly spreading mid-ocean ridge, transform association, overwhelmed at intervals by volcaniclastic sediment. Detailed mapping at a scale of 1:5000, and stratigraphic and geochemical development and structural coherence, show that the group is not melange in the Franciscan sense. The Dun Mountain Group, of serpentinites, peridotites, dunites, gabbros and other rocks, intruded the upper Patuki Group as a linear series of aligned pods and sheets. They carried up with them tectonic inclusions of older rock, which were metasomatised, and altered wall-rock, and one low angle dike passed several hundred metres into overl~ing sediment, at moderate temperatures (500 C). The rocks did not act as a floor (and alleged source) for the Patuki, but partly post-dated and were emplaced into Patuki.

Jan 1, 1987

This case study describes various aspects of establishing a laboratory facility for testing chemically-cemented fill materials. The applicability of data obtained from such a facility related to mine conditions depends on many factors: kind of data, type of testing facility, sample parameters (composition, geometry, size, etc.). The equipment employed must be adaptable, to accommodate variations in sample size and properties. The design, construction and operation of the testing facility is described, and its application to fill samples prepared from sulphides and oxides both chemically and naturally cemented. The present system was selected following an extensive study of equipment available for testing materials in the fields of rock mechanics and construction materials. The strength testing' facility incorporates Linear Variable Differential Transformers for monitoring both lateral and axial displacements during sample compression. The output from these and from other related instrumentation can be recorded or fed direct to a computer, enabling stress-strain data to be printed out while the test is in progress. Also described are controlled environment curing facilities which allow samples to be cured or weathered under different temperature or humidity conditions to simulate long-term ageing and in place conditions.

Jan 1, 1973

By E Werner, J J. Donovan, A J. Morris

Coal mining in the Pittsburgh coal seam, in the eastern United States, began in the late-1700s. Since that time numerous mining technologies have been used throughout the basin. Environmental concerns, particularly mine discharge quality, have only been considered since the early-1970s. During the last 20 years, many of the larger underground mines have closed and are now either flooding or already flooded. In order to understand the consequences and potential future effects of this flooding, mine mapping of the basin has been compiled utilising a geographic information system (GIS) with an emphasis on locating barrier pillars between mines. Mine flooding has been monitored at numerous sites utilising pressure transducers and data loggers. These data have been combined with historical data from mining companies and structure contour maps to yield chronological flooding maps of the basin from 1980 to present. Utilising these maps and the indicated flooding rates, future discharge locations have been identified along with estimates of when these discharges are likely to occur. Related work has identified barrier pillar hydraulic conductivities and vertical infiltration rates as a function of overburden thickness. All of this information has been integrated into a groundwater flow model that simulates mine flooding. This model is useful in defining mine to mine interactions as the various mines fill with water, and the testing of various flooding scenarios. The model will be used in evaluating mine discharge rates and evaluating the options for regional mine drainage treatment.

Jan 1, 2003

By Grace B, Cunningham D

The poor quality of bore waters available to the Australian mineral processing industry creates a climate for crystallization of calcium based scales. If ignored, calcite and/or gypsum buildup can cause loss of production and costly unscheduled maintenance. This paper discusses the factors which contribute to scale forma- tion, methods used to monitor buildup and preventative measures (mechanical and chemical) that can be used. A case history il- lustrates the value of using chemical antiscalants.

Jan 1, 1991

Cannington is a Broken Hill type deposit discovered by BHP Minerals, now BHP Billiton, in 1990. The deposit is located south east of Cloncurry, Queensland, Australia. The deposit occurs in the Eastern succession of the Mount Isa Inlier within the Soldiers Cap Group. The mineralisation is interpreted to be confined to two limbs of a synform wrapped around a core amphibolite. The silver, lead and zinc mineralisation is zoned within silicic and mafic units. There is a strong association between silver and lead. The combination of mafic and silicic zoning, differing relative grades of silver, lead, zinc and iron, the relative position of the mineralisation on the synform limbs and differing metallurgical performances have resulted in the identification of ten different ore types, four of which are currently extracted. Ordinary Kriging (OK) is used as the resource estimation methodology for the silver, lead and zinc mineralisation. This modelling approach has performed quite well for resource reporting and long term mine planning. However the limitations of this modelling technique to adequately provide information on a local stope scale has lead to the geological staff to consider alternatives to this approach. Limitations of the current modelling method apply to both the geometry of the orebodies and the grade variability. Since early-2000 the Cannington geologists have been experimenting with modelling both the distribution of the mineralisation types using Probability Field conditional simulation (PF) and the distribution of grade using Sequential Gaussian Simulation (SGS). This approach to local modelling of mineralisation type and metal grades using conditional simulation (CS) has undergone a full evaluation by comparing grades estimated for stopes using both the (OK) resource model and conditional simulation (CS) models. The mine planning staff have used the CS derived models, and have found improvements in grade predictions over the currently utilised Ordinary Kriging û derived resource model.

Jan 1, 2003

By Sobek S, Lotzien RM

Although the conventional procedures for designing agitator flotation plants are well-known and reliable, little experience for designing modem pneumatic flotation plants has been gained up to now. A reliable procedure originating from graphic methods for the design of distillation columns is presented. Examples demonstrate on laboratory and semi-technical scale the application of this extremely practical method for designing a fly ash and a magnesite flotation plant.

Jan 1, 1993

By Giedl JG

Technical applications of computers within the coal industry are expanding rapidly with an increase in the number of users and user locations. Collinsville Coal Company Pty Ltd is an example of a remote and growing user company which has a Telecom link to MIM's ICL mainframe computer in Brisbane. The Planning Department is one of the technical user departments at Collinsville, with a variety of VDU, plotting and screen graphics hardware supported by the MIM Computing network. Current applications involve the storage, retrieval and manipulation of borehole information, plan and map production, volume calculations from survey data and mine ventilation modelling for underground Operations.

Jan 1, 1983

By Abraham B. K, Jensen B, Gillies A. D S

The aim of the research was to investigate the feasibility of using an impedance cell and ratio-transformer bridge to measure solids content in coal slurry pipelines. It appeared that this technique could be developed to measure variations in conductance which correlate with solids content. Successful implementation of the measurement technique would have a variety of applications in existing coal wash plants and the potential for automatic process control. A small pilot plant was designed for a feasibility study. This was a closed loop system in which the coal was uniformly dispersed in a tank with a variable speed agitator and then circulated through an external pipe returning to the top of the tank. The impedance cell was located near the end of the external pipe. Slurry concentrations were varied from clean tap water to 50 per cent solids by weight with the addition of weighed quantities of dry coal dust. Ratio-transformer bridge measurements showed that variations in individual observations were equivalent to measurement errors of about two per cent. These probably reflect variations in concentration of the mixture in the pipe. Data for increments in concentration of one per cent indicate that this is about the limit of resolution of the current system. The paper discusses the principles of operation of the impedance cell and measurement system. Results from the pilot study and proposed improvements in the impedance cell design are examined.

Jan 1, 1995

The working of alluvial deposits has from all times been a popular form of mining, not only from the simplieity of its operations, but also, in its more primitive stages, from the possibility of carrying it on without large capital, without skilled lahour, expensive plant, long terms of preparatory work, or, in fact, any other requisite than a shovel, a dish, and a stout pair of arms. It is possibly one of the oldest industries, and probably, also, it has been one of the most profitable.In tbe Australian States the happy days of rid alluvial deposits, when gold was to be hltd for the shovelling, are now almost over. The lust for gold has caused almost every corner of the world to be ransacked, and the more easily earned wealth to he exhausted: for the most part there remain now those deposits only which are too poor to be profitably worked by means of the implements and methods of old times. But, though the deposits have become poorer, the keen inventiveness of man has devised means whereby such large quantIties can be treated at a cost so low that he can still make a profit out of them. In this article, out of the many means devised, three only will be referred to-viz., hydraulic sluicing, bucket dredging, and hydraulic dredging. All mining may be divided into three principal operations-1st, the breaking down and conveying of the ground to where it is to be treated for the recovery of the metallic values, 2nd, the treatment of the material for the recovery of those values; and, 3rd) the removal of the worthless material or tailings. In all mining the object is to effect these three processes for the least expenditure of money commensurate with the highest degree of efficiency.

Jan 1, 1907

Current problems in predicting sub-surface strata movement and fracture development due to longwall mining have highlighted the need for more accurate, dependable methods of physical modelling of rock mechanics problems which are beyond the capabilities of current mathematical techniques. Physical model studies of the caved zone above the working faces up to the base of a water source are of importance in attempting to understand changes in mass permeability due to induced fracture zones and the resulting ground water conditions. Turkey's most important supplies of coking coals are to be found within the hard coal resources of the Black Sea coast. Coal seams up to 9 metres thick, dipping at angles as steep as 90 degrees are being successfully mined at the Kozlu Mine. Since 1956, mining operations have been carried out under the sea in dry conditions. The undersea mining conditions of the Kozlu Mine have been investigated using scaled physical models constructed from artificial materials which satisfied necessary scaling requirements. Models representing the in-situ conditions were tested and the following extraction sequence was employed: 1. The Sulu Seam extraction 2. The Acilik Seam extraction (as two slices) 3. The Piric Seam extraction. The displacement of the fixed reference points were subsequently measured using a high precision photogrammetric technique and induced horizontal and vertical strains were calculated.

Jan 1, 1988

By Parfitt RL

A quarter of the North Island, New Zealand is covered by weathered volcanic tephras of mainly andesitic and rhyolitic compositions. Rapid weathering of basic volcanic glass and slower weathering of acidic glass have produced short-range order alumino-silicate clays such as allophane. Although amorphous to x-rays they have a high degree of local structure. Allophane comprises hollo spheres of approximately 40 diameter and 7 X wall thickness. This small particle size and morphology gives a very high surface area (up to 800 m2/g). Ferrihydrite is another short-range order clay of similar small size and high surface area; it has ò formed from the rapid oxidation of water containing ferrous iron derived from volcanic rocks. The quantity of allophane present in tephra depends upon the climate, the nature of the volcanic glass and the time it has weathered. In New Zealand highest amounts (-50%) occur in beds of andesitic ash deposited on old ignimbrite surfaces with mean annual rainfalls >1600 mm. Both allophane and ferrihydrite will react with oxyanions, such as phosphate, arsenate or borate, and remove them from solution. Other anions such as fluoride also react with aluminium sites on the mineral surface. At NZ Soil Bureau, Department of Scientific and Industrial Research (DSIR), New Zealand, techniques have been developed for granulating allophane to enable it to be used to remove pollutants from solution without dispersion into the liquid phase. This granulated allophane can be used to remove phosphate from sewage effluent or fluoride from tap water without having a sedimentation stage to remove the clay.

Jan 1, 1987

By R Skirrow, E Bastrakov, A Mauger, P

A new rapid spectroscopic core and chip logging and imaging system developed by CSIRO was evaluated by PIRSA and GA on a wide variety of mineralised properties in South Australia, including the Emmie Bluff, iron oxide copper-gold-style prospect on the Stuart Shelf. During a three-month campaign in South Australia in 2003 the system logged over 50 000 metres of core from the State Core Library, company prospects and mines. The new system uses automated core tray handling, continuous visible and infrared spectroscopy, and digital imaging, to characterise and identify dominant mineral species on core, chips and pulps, at spatial resolutions of ~1 cm (spectral data) and ~0.1 mm (image data). The system can log up to 1000 m of core per day and several thousand metres of drill chips. Mineralogy is pre-interpreted using specialised identification software trained on a selected suite of minerals showing characteristic absorption features within the measured spectral range. On core from the Emmie Bluff iron oxide copper-gold prospect, 470 km NW of Adelaide and 80 km SSE of the Olympic Dam Cu-U-Au deposit, the spectral mapping system was able to characterise a number of alteration zones enveloping the sub-economic Cu-Au mineralisation. These consist of distal white mica phases showing decreasing Al content towards mineralisation, a zone of increased iron oxide content in the hangingwall to mineralisation, and a zone proximal and coincident to Cu-Au mineralisation that is enriched in chlorite with variable Mg/Fe chemistry. Additionally the results show background spectral characteristics that mimic the magnetite distribution.

Jan 1, 2004

The Hall-Heroult process is likely to be the dominant method of aluminium production for the remainder of the century. The characteristics of the operation of a modern smelter are described and attention drawn to their disabilities which are due chiefly to the small production capacity of individual cells.The principal components of the Hall-Heroult cell- the electrolyte, the anode and the cathodes are discussed in order to identify the problems of scale-up. The factors influencing current efficiency and energy consumption are analysed and lead to the conclusion that the greatest potential for energy saving lies in reducing the anode to cathode distance (ACD).The most promising direction for major change is in the application of a new titanium diboride-carbon composite for coating of the surface of the cathode carbon. It improves the wetting of the carbon by aluminium and should permit the use of sloping cathodes and anodes. The deep metal pad would thereby be eliminated and, in the absence of magnetic perturbations, the ACD could be substantially decreased.

Jan 1, 1987

Precious metal mineralization at the North Arm goldfield in SE Queensland occurs in the Triassic North Arm Volcanics, a sequence of andesite to rhyolite, pyroclastic and epi- clastic rocks deposited in a continental envir- onment. This unit displays a well-defined fracture system on Landsat imagery, including several arcuate structures which may represent former calderas. Two of the latter are associ- ated with zones of hydrothermal alteration, breccias and anomalous precious and volatile metal values. At the North Arm prospect, alter- ation is zoned from outer propylitic into exten- sive sericitic, although K-feldspar alteration is prevalent in the rhyolite. A zone of advanced argillic alteration is also present at Mt. Ninderry, SSE of North Arm. Alteration involves depletion of Na, Ca and Sr, and vari- able enrichment of S, As, Au, Ag, Hg and Mo. K and Rb are strongly enriched in K-feldspar altered zones. Precious metal mineralization occurs in veins, stockworks and hydrothermal breccia zones, and pervasive low grade Au-Ag dispersion is found throughout the sericitic and K-feldspar altered rocks. Veins and brec- cia interstices contain abundant quartz (common- ly banded), minor pyrite, calcite and sericite, with traces of silver grading to electrum, frei- bergite, naumannite, allargentum, marcasite, chalcopyrite and sphalerite. Mineralogical and geochemical characteristics are consistent with that found at volcanic-hosted epithermal precious metal deposits, particularly with the low-sulphur/adularia-sericite type.

Jan 1, 1987

By McKew M, OÆRegan

Rapid access longwall mining' or 'longwail punch mining' is a proposed extraction method whereby longwall gate roads are driven into a seam directly from an opencut highwall. The longwall panel thus formed is retreated back to within 40 m of the highwall providing an extremely simple, reliable and therefore highly productive longwall mining system. The concept is of particular benefit for the recovery of isolated pockets of coal (adjacent to a highwall) not easily accessible from a conventional underground mine. As panel gate roads are driven directly from the open strip, minimal delays are incurred between the end of open cut and start of underground production, allowing the method to bridge the gap between open cut mining and a total underground commitment. The study was specific to the Bowen Basin, and given the likely conditions, no significant operational or geotechnical hinderances to the concept could be identified. It was therefore concluded that longwall punch mining would not expose the operator to any additional risks above that normally associated with the introduction of longwall mining. Thus, longwall punch mining is an attractive option, both operationally and financially, for open cut mines reaching their maximum economic Death.

Jan 1, 1988