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By A Richmond

"In some lode-style gold deposits the geological (lithological) uncertainty may have similar economic significance as the grade uncertainty. In the absence of precise knowledge of the deposit geology, geological models of these types of deposits that are used to constrain spatially the estimated (or simulated) grade values may influence significantly the contained metal. Methods for assessing geological uncertainty quantitatively are rarely considered due to their perceived inability to consider exhaustive geological interpretations, and resulting models that often appear geologically unrealistic. Furthermore, should the lodes have been subjected to folding, or where the mineralisation continuity does not follow a planar orientation along strike or down dip, standard methods of variography and interpolation using linear vectors in space often do not provide a good representation of continuity. An alternative approach is to relate spatial samples from adjacent drill holes using an unfolding plane.The paper demonstrates conditional simulation of the geometry and gold grades of a folded lode-style deposit where:simulation of lode geometry considers explicitly the geologistÆs interpretation, andsimulation of gold grade values that consider explicitly the folded nature of the lodes.The results are contrasted to the traditional approach of linear vectors in real space for a single lode interpretation.CITATION:Richmond, A, 2012. Conditional simulation of a folded lode-style gold deposit, in Proceedings Narrow Vein Mining 2012 , pp 149-154 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 26, 2012

By I D. Hair

A numerical groundwater model was used to predict the nature of interactions between heavy mineral sands mining operations and the groundwater regime at North Stradbroke Island, Southeast Queensland. North Stradbroke Island is formed mainly of massive vegetated Cainozoic aged dune sands. Since the 1950s, a number of operations have mined rutile, zircon and ilmenite on North Stradbroke Island. In such mining operations, a dredge and an associated processing plant are floated in a pond either above or below the prime groundwater table The numerical model was based on the North Stradbroke Island Groundwater Management Model, developed in 2001 by the Department of Natural Resources and Mines (NR&M). This model was constructed using the modular, cell-centred, finite-difference groundwater flow model, MODFLOW, developed by the United States Geological Survey (USGS). The NR&M model was refined to improve model resolution and detail for simulating dredge mine paths. Of particular interest were: water table fluctuations induced by mining for the identification of slope stability risk; the optimisation of sand spear arrays supplying mine make-up water requirements; inflow and outflow rates to the dredge pond for overall mine water balance; and interactions with Eighteen Mile Swamp and water supply bores controlled by the Redland Shire Council (RSC). Depending on the water level in the dredge pond compared with the surrounding groundwater table, water either flows out of the dredge pond into the groundwater regime or from the groundwater system into the dredge pond. The MODFLOW river package (RIV) was utilised for the modelling study. Dredge pond movement was simulated using specialised software developed by Watermark Numerical Computing (WNC) to interpolate pond positions and map the dredge path to the model grid both spatially and temporally. As tailings placement affects the groundwater system through increased recharge, the MODFLOW recharge package (RCH) was utilised to simulate different recharge efficiencies. Long-term model predictions were made for the period from July 2002 to May 2021. Results of the modelling showed that exchanges of flow between mining operations and the groundwater regime could be effectively managed. The study provided valuable information which was used to develop an appropriate mine water management plan.

Jan 1, 2003

By S Vink, V Nanjappa, C J. Moran

Poor quality water resulting from interaction of surface run-off with saline mine spoil and soils can cause significant problems for water reuse on mine sites. Not only can this saline water lead to machine corrosion and increased maintenance costs, but may cause detrimental effects on the environment. Determining the geochemistry of mine spoil, and the likelihood of salt dissolution during rainfall events, may aid in more effective mine site management of water. Spoil samples were taken from three areas of the German Creek mine site, situated in the Bowen Basin coalfield, Queensland. Samples from two undisturbed areas on the lease were also collected for comparison. Analyses were performed using a variety of laboratory techniques: leaching tests, effective cation exchange capacity determination, X-ray diffraction, clay quantification, and total organic content determination. Results show that dissolution of surface (top 2 cm) salt minerals from spoil areas is an important contributor to surface run-off salinity during rainfall events. Equally, ion exchange with clay minerals appears to be a significant source of elevated ion concentrations in run-off waters. Findings from the undisturbed areas show undetectable quantities of salt mineral species, resulting in waters with low ion concentrations. More generally, monovalent cations (sodium, and to a lesser extent potassium) appear to be derived from dissolution of salt precipitated whereas divalent cations (calcium, magnesium) are more likely to be sourced from exchange reactions with clay minerals. Incorporating knowledge about the mechanism of cation mobilisation from spoil with the spatial distribution of spoil properties and understanding of the dynamics of water quality variations on the site will aid in development of integrated water quantity and quality management strategies.

Jan 1, 2009

By S Brochot

In cases where coarse gold is present in a deposit, it is usual to use the screen fire assay (SFA) method to analyse the samples. There is no doubt that this method is more accurate than the standard fire assay (FA) and reduces the risk to have a systematic bias. Nevertheless, the difference between the analytical errors of both methods can be glossed over when the overall sampling error is added to obtain the measurement error. In that case, the advantage of the SFA cannot justify its higher cost.The current paper attempts to address this question in the case of a gold ore deposit with visible coarse gold in various sampling situations (drill core sampling in exploration, blasthole or chip sampling in mining exploitation). The overall measurement error is estimated taking into account the analytical error and all the sampling error components following the Pierre GyÆs theory of sampling.Firstly, only the last sampling stage is considered when the pulverised sample is processed either to obtain one analysis sample for a FA or to be screened and subsampled for a SFA. The calculated measurement error clearly shows the advantage of the SFA specifically in presence of coarse gold. Secondly, the half core sampling is studied to explain the observed discrepancies when controlling the second half core. Finally, the blasthole sampling is treated using in situ heterogeneity models to show that the relative advantage of the SFA is hidden by the large overall sampling error.In conclusion, the choice of the assaying method is discussed at the light of the overall measurement error and in accordance to the analysis objective.CITATION:Brochot, S, 2012. Standard fire assay or screen fire assay? Application of the overall measurement error approach to choose the most appropriate method, in Proceedings Sampling 2012 , pp 135-142 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By Derham DW, Newcombe LA

The operations of the Mount Morgan gold tailings retreatment plant were significantly improved in 1984 by the desliming of the CIP plant feed, which reduced cyanide consumption and increased percent gold dissolution. Subsequently, the development of slimes treatment, incorporating gold leaching from slimes solids by copper cyanide complexes in the process water, and gold adsorption on to carbon in an environment lacking free cyanide was successfully implemented. Mount Morgan was initially mined for gold commencing in 1882 on the auriferous ironstone cap to the sulphide ore body. During the history of mining and processing at Mount Morgan the operations have developed through numerous phases of gold and copper production, operating almost continuously through until the final closure in late 1990. The final phase of processing was the retreatment of tailings, predominantly flotation tailings accumulated since the 1930s, for the recovery of gold and minor silver. Tailings retreatment commenced in 1982 with the commissioning of a 10 000 tonnes per day CIP plant to treat some 40 million tonnes of tailings at an average grade of 1.08 g/t Au. The initial operations were hampered by high cyanide consumption and poor gold dissolution on the mixed siliceous/pyritic tailings. The successful development and implementation of the desliming of the CIP plant feed in 1984 (as described by Parsons and Hampshire, 1986) reduced cyanide consumption by 40 per cent, and raised gold extraction by 13 per cent points by virtue of significantly higher dissolved oxygen levels. The finer portion of the reclaimed tailings were deslimed by eighty 100 mm diameter AKW cyclones, with the desliming cyclone overflow thickened in a Warman 30 in diameter thickener for water recovery and slimes disposal. Operation of the desliming plant involved the discarding of a slime fraction representing about 15 per cent of the reclaimed feed. Although gold-bearing, the high content of cyanicides and oxygen consumers within the slime negated any conventional treatment of this stream with free cyanide for gold recovery. The natural lixiviant behaviour of the soluble copper cyanide complexes for gold, which was extremely evident at Mount Morgan, directed efforts in this area. Enhancement of gold leaching with a deficiency or near absence of detectable free cyanide, but with significant levels of copper cyanide complex from recycled process water were examined. Adsorption of this solubilised gold onto carbon in a similarly difficult environment required close examination.

Jan 1, 1993

By J Lane, D J. Barker, B Pei

Queensland Alumina Limited (QAL) is the worldÆs largest producer of smelter grade alumina, located in Gladstone, Queensland, Australia. The plant employs evaporative cooling towers for waste heat rejection. Process water requirements include red mud residue disposal, steam venting to the atmosphere and Calcination feed moisture. Raw (untreated) water consumption in 2001 was 37 700 m3/d or 3.8 m3 per tonne of production. The Gladstone region experienced a water shortage in the period 2001 to 2003, resulting in progressive water restrictions. Industry operated under a ten per cent restriction from April 2002 and in November 2002 a 25 per cent restriction came in force. The maximum restriction level of 50 per cent was anticipated for the middle of 2003. Water restrictions of these magnitudes have the potential to result in significant production limitations, which would have major economic consequences for QALÆs owners, customers, suppliers and employees. Therefore it was imperative that measures be found to mitigate the impact of these restrictions. Furthermore, as one of the largest water users in the Gladstone region, QAL had an obligation to the community to minimise water usage as much as possible. A thorough analysis of water usage on site was conducted, focussing on all water streams leaving the plant. The philosophy used was that by minimising water outputs, the inputs would follow suit. Where possible, preference was given to solutions that provided lasting water savings. This occurs when the value of the water saving justifies the project cost, irrespective of water restrictions. By June 2002 an average water saving of 19 per cent was achieved, almost double the required saving. By end November 2002 further projects had increased the total water saving to 29 per cent, mainly through the re-use of GladstoneÆs municipal treated effluent as wash water. Further measures to reach the target of 50 per cent reduction were investigated. The evaporative cooling system was to be replaced with seawater cooling, using cooling towers to minimise the seawater pumping cost. Another benefit of this concept was the ability to dispose of the cooling tower bleed stream with the existing system for neutralised red mud disposal. This would avoid the need for an additional environmental outfall from the plant. In February 2003 the Gladstone region received over 500 mm of rain, which boosted water reserves to five years supply at forecast usage rates. This led to the lifting of all water restriction. As most of the implemented water savings measures are economically viable in the absence of water restrictions, raw water usage at QAL is still less than 75 per cent of pre-2002 levels.

Jan 1, 2003

Graded macadam slag base has been used successfully by the Department of Main Roads, N.S.W., in the construction of Expressways. However, the use of graded macadam in urban conditions introduces problems which can be avoided by the use of material meeting the specification outlined in M.R. Form 744. This paper outlines the rationale behind the technical requirements of the specification for the "Supply of natural gravel or crushed rock for road pavement (bitumen surfaced) M.R. Form 744". A blend of materials produced from slag is proposed as a potential solution for the production of slag base which would be suitable for use in urban construction or maintenance of roads.

Jan 1, 1979

The West Fork project is located in Reynolds County, Missouri, in the mineralized zone referred to as the Viburnum Trend. The West Fork orebody has a calculated ore re- serve of 13 600 000 tonne (15 000 000 st) con- taining 5.5 per cent lead, 1.2 per cent zinc, and recoverable values of copper and silver. A total of 64 600 tonne (71 200 st) of lead concentrate and 11 300 tonne (12 500 st) of zinc concentrate will be produced annually. The mill was designed to operate at an average capacity of 3450 tonne/day (3800 st/day), based on a 95 per cent availability factor. The mill will operate 24 hours a day, 5 days a week, with maintenance performed, as needed, on weekends. The mine will operate on an identical schedule; but the underground, pri- mary crushing will operate on a six hour/shift, three shift/day schedule. The 1.07m x 1.22m (42in x 48in) jaw crusher will produce a minus 20cm (8 in) material at an average rate of 191 tonne/h (211 st/h). The jaw crusher has almost twice the throughput capacity required, but the decision to install that size of crusher was based on the need to handle over sized rock in the ore.The coarse crushed ore will discharge into a 180 tonne (200 st) skip pocket, which will allow up to a one hour surge capacity prior to hoisting. Hoisted ore will discharge into a 900 tonne (1000 st) storage bin located adjacent to the headframe. The skip pocket and coarse ore silo comprise the total ore storage capacity. The concept of having no intermediate fine ore storage between the secondary crushing and grinding sections was borrowed from the Brushy Creek Mill of St. Joe Minerals, which operates adjacent to the West Fork property. Integration of the secondary crushing and grinding circuits has worked ' successfully for years at the Brushy Creek Mill. The most obvious advantage to eliminating the intermediate fine ore storage is'capital expen- diture savings. The capital expenditure savings include the cost of silos, feeders, and the cost of additional conveyor length and eleva- tion. Savings in operating costs will also be gained, particularly in reduced maintenance costs. Other factors which influenced the decision to eliminate fine ore storage were the simplicity of the secondary crushing sec- tion and the limited area available for con struction of the facility

Jan 1, 1978

The term "joint venture" lacks any precise legal definition but is typically used to denote a form of legal relationship which is neither a partnership nor a corporation. Nbst joint ventures are contractual relationships which provide for the sharing of mining leases and production facilities and for the sharing of costs, but which enable each joint venturer to carry on his own separate business. The rationale for such relationships is that each participant: retains independent taxation status may independently grant direct security over his interest in the project assets for financing purposes Bankers prefer to lend to incorporated joint ventures (i.e. corporations in which all of the joint venturers are shareholders) but will lend to individual joint venturers provided the joint venture agreement does not imperil their security; i.e. provided there is a "bankable" joint venture. The carpeting objectives of joint venturers and their bankers may be reconciled and unnecessary conflict avoided by the timely inclusion of appropriate provisions in the joint venture agreement before financing negotiations commence.

Jan 1, 1983

The medical evaluation of the health effects of dust exposure in the mining industry should be based on the premise that the results of the medical examinations will be considered in relation to the previous history of exposure to dust.(l) To this end the Mines Regulation Act and the Regulations under that Act in West- ern Australia provide for: the prime responsibility for dust sampling to rest with the mining companies; the appointment of a Ventilation officer by each mine and the sampling and record- ing by him of dust and toxic gases in work places at three monthly intervals, or more frequently as required; the appointment of a Mines Medical Officer who shall make provision for the medical examination of persons and the prevention of occupational diseases; the appointment of a Ventilation Board, consisting of the State Mining Engineer, the Senior Inspector of Mines for the State, an Inspector of Mines having specialised training in ventilation tech- nology, a medical practitioner having specialised experience in occupational health problems relevant to the mining industry, and a Scientific Officer having duties under the provisions of the Clean Air Act, 1964;

Jan 1, 1979

By C Chen, W J. Bruckard, F R. A Jorge

The base metal industry mines and processes hundreds of million tonnes of ore per annum to produce saleable products and large tonnages of waste by-products such as tailings. These ores usually contain less than 1 wt per cent of toxic elements (As, Sb, Bi, Cd, Se, Te, Hg, etc), which are subsequently treated with the other components in the ore during the production of concentrate through to saleable metal products. The deportments of minor elements across the various unit operations of a process flow sheet do not normally receive the attention that the major elements receive. However, these minor elements can have a major influence on the quality of the products as well as an economic and environmental impact. Therefore, a high degree of control over their deportments is a key step in reducing their dispersion in the biosphere. Ongoing work at CSIRO has been examining minor element deportments across unit processes used for smelting and refining and the options for early removal of minor elements, as well as methods for safe disposal of some toxic elements. This paper provides an overview of the R&D activities undertaken at CSIRO to develop tools and methodologies for improved management of minor elements during the processing of sulfide ores.

Jan 1, 2006

The Tregoora Gold Project is centred around the old Mitchell River Antimony Field located 100 kilometres west-northwest of Cairns, North Queensland. The project is currently the subject of a joint venture between Strategic Minerals Corporation N.L. and Hawk Investments Limited.Historical BackgroundThe Tregoora area was first prospected for antimony and gold around 1890. During the periods 1905 to 1914 and 1937 and 1944 approximately 100 tonnes of antimony and an unknown quantity of gold were won from a number of small mines the principal one being the "Retina". A strong increase in the demand for antimony in the early 1970's resulted in renewed exploration activity in the region and the re-development of the Retina Mine. Despite the intermittent interest in the region for antimony it was not until 1984 that the potential of the area for hosting gold resources was realised with the delineation by Strategic Minerals Corporation N.L. of a significant gold deposit now referred to as the Black Knight.

Jan 1, 1986

The Committee for Mineral Reserves International Reporting Standards (CRIRSCO) was formed in 1994 to promote development and adoption of international standards for estimation and reporting of exploration results, mineral resources and mineral reserves. The CRIRSCO standards have been accepted by most mining companies and professional societies worldwide. Market regulators from Australia, South Africa and Canada require that these standards be followed when releasing public information. Among these requirements is the use of specific definitions for what constitutes exploration results, mineral resources and mineral reserves. If such information is publicly disclosed in must be estimated by a Competent or Qualified Person. In the United States of America, public disclosures are regulated by the US Securities and Exchange Commission. The SEC does not recognise the CRIRSCO guidelines, and some of the SEC requirements for public release of information are materially different from those applicable in other countries. The CRIRSCO definitions and the Competent Person requirements are reviewed and compared with those of the SEC. The organisation of the SEC and its rule making process are briefly discussed. Ongoing efforts to bring the US regulatory requirements closer to those applicable in other countries are presented, as well as other activities that CRIRSCO is entertaining with the United Nations, the International Accounting Standard Board and other international organisations to reach the objective of worldwide standardisation of reporting procedures.

Jan 1, 2006

A key premise to this paper is that most people involved in the design and implementation of drilling and blasting operations could benefit from a greater understanding of the geological materials, deposits and landforms they are dealing with. The second key ingredient for successful blasting is the concept of blasting objective. Mine operators and blasting contractors must be clear on what drives their costs (blasting leverage) and should formulate blasting objectives and operational targets which help in this regard. Many operators ignore geology descriptors and features apart from the name of the rock and start crudely quantifying the rock mass properties in terms of uniaxial compressive strength, or even worse still as hard or soft. This occurs too early in the design process and not much attention is paid to the geological materials, geological structures and the characteristics of the deposit they intend to excavate. In effect the rock type name and the strength descriptor become the site geology. Furthermore many blasting operators do not formalise their blasting objective, do not set operational targets and do not measure results to the degree required for continuous improvement. In this paper a number of civil, surface mine and underground mine blasting applications are tabulated in terms of typical blasting objectives and common geological materials. A good description of geological materials can convey a lot of useful information for blasting operators if they are able to accommodate this knowledge. In addition a clear statement of the blasting objective and associated operational targets will maximise the likelihood of achieving blast-driven downstream productivity improvements. The æStarting at Both EndsÆ combination is deemed extremely useful for any continuous improvement blasting program.

Jan 1, 1999

By C Li

Removal of gangue minerals from ilmenite concentrates can beaccomplished by relatively low temperature roasting in controlled gasatmospheres to selectively enhance the magnetic separationcharacteristics of the ilmenite. At roasting temperatures below 800¦C the magnetising reactions are often not consistent with phase equilibria considerations. Metastable phases can nucleate and control the roasting products. In weathered ilmenites the phase assemblages and microstructures in the altered ilmenite grains can influence the roasting reactions. In this paper we give an overview of the phase chemistry of chemically weathered ilmenites and of metastable phases formed by low temperature roasting. We also report the results of roast experiments conducted in a neutral gas atmosphere. Major increases in magnetic properties after short roasting times at low temperatures were obtained for a range of ilmenite concentrates. For example heating a secondary ilmenite concentrate from Western Australia for 15 minutes in nitrogen at 600¦C gave an increase in the three kilogauss magnetic fraction from three to 92 wt per cent. The solid state phase changes accompanying the inert atmosphereroasts were characterised by combining elemental analyses withquantitative phase analyses of the ilmenite concentrates and their roast products. It was found that the phase reaction that is principally responsible for the increase in the magnetic properties of weathered ilmenites involves a transformation of disordered ferrous-containing pseudorutile to an ordered ilmenite-hematite solid solution containing typically ten to 35 mole per cent of the hematite component. Examples are given of the application of the inert atmosphere roast to effect separations of ilmenite from gangue minerals.

Jan 1, 2001

As a basis for my address to you tonight I thought it might be opportune if we considered the great history of the mineral industry in Australia, and the contribution it has made to the development of the country. While it is perhaps interesting to review the achievements of the past there is also the opportunity to examine the developments of the future.The names generally given to the three periods of man's life on the earth-the Stone, the Bronze, and the Iron Ageand to which should perhaps now be added the Atomic Age, imply the vast importance of the progressive steps in 'man's discovery of minerals and the means of working them. They tell the story of his advance from the flint knife to the bronze celt, and then to the keen-edged iron weapon, and now to the possibilities of the peaceful application of atomic energy. Not only have the stories of gold, iron, copper and tin told a great deal of the history of the progress of mankind, but they have also traced the commercial and industrial growth of Australia over the last century.Gold in the 1850's was responsible for the most significant period of immigration Australia has ever had-when the population almost tripled in the ten years to 1860. Minerals were also responsible for opening up Australia and determining the pattern of settlement. As mineral finds were made, railways were constructed to these fields, then agricultural development followed.Then, as the industrial era started, minerals provided the raw material for Australia's rapid industrial expansion, and they have all contributed to the extent that they have made...

Jan 1, 1960

IT is generally accepted that for transport of coal underground from different collecting stations, the system of endless rope haulage with remote control is not only one of the safest and most economIcal, but is also one of the most'efficlent in dealing with output.When the coal measures lie in regular planes, the work of laying down such a haulage presents no difficulties. When, however, the dip of the measures is Irregular, or dislocated by faulting, the management is faced with the problem of constructing vertical curves of such a radius that the sag of the rope will correspond with the road bed, and thus obviate the danger of the rope rising and throwing the skips off the track.The direction of the main roads for haulage purposes being ascertained from the plan of the royalty to be worked, the faults or dislocations in the seam are determined for these roads with the greatest possible accuracy by means of bore holes from the surface.From the data thus obtained the haulage road can generally be so graded that the rope will keep on the floor during haulage operations, although the grades may in places be synclinal.The writer confesses that he knows of no accurate formula for calculating the sag of the rope under varying tensions and so determining the safe radius of the curve, and he had to depend upon past experiences under somewhat sImilar conditions.The accompanying sections illustrate a case where the writer has recently installed an endless rope underground approximately 5000 ft. in length, from the foot of a tunnel in which an endless rope delivers the output to the screening plant, and having to negotiate, first a 400-ft. downthrow fault, and later a 32 ft. upthrow.

Jan 1, 1927

By J R. Kyle

The Deep Mill Level Zone (DMLZ) skarn Cu-Au deposit is the deepest explored part of the Ertsberg East Skarn System extending from the surface at 4200 m elevation to the DMLZ at 2900 to 2600 m. The DMLZ is hosted in an upper Cretaceous to lower Tertiary siliciclastic and carbonate succession adjacent to the 3 Ma Ertsberg pluton. Much of the DMLZ ore is hosted by mixed assemblages of siliciclastic and dolomitised carbonate strata that have been altered to Mg-rich skarn assemblages. Unaltered equivalent strata from a 300 m cored interval in the Yellow Valley Syncline were characterised petrographically and representative samples were analysed for major element compositions. These stratigraphic and chemical units are interpreted to be responsible for the varying skarn lithologies within the DMLZ. The dominant prograde skarn assemblages are controlled by protolith composition, notably the relative abundance of quartz, dolomite, and calcite within the protolith. Models based on isochemical metamorphism of mixed assemblages of quartz and dolomite suggest that the formation of the forsterite-diopside dominant skarn assemblages resulted in the greatest amount of pore space increase. DMLZ Cu-Au concentrations were locally controlled by host lithology, with structural features providing fluid pathways that focused the mineralising fluids. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Eggleton T, Taylor G

The lateral and vertical distributions of gold and a wide range of other elements in the regolith, close to Au and Cu mineralisation have been investigated at Goonumbla, NSW. Open cut mining has exposed deeply weathered profiles which have been used for this investigation. Determination of secondary mineralogy and micromorphology of profiles have facilitated the broad interpretation of processes that determine element mobility and dispersion from primary mineralisation as a result of weathering. This in turn has led to better interpretation of geochemical data and enhanced understanding and knowledge of regolith geochemical processes which are invaluable in the formulation of improved exploration Procedures.

Jan 1, 1997

Although I have, for most of my working life, been associated with research into problems of water pollution, this has been exclusively in a country where problems arise from having too many people rather than too little water, a country furthermore, where for the past few decades, mining, except for coal, could hardly be called a major Industry.

Jan 1, 1971