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The discussion which followed the publication of my paper by the formert has, I think, enhanced its value. It may therefore be of interest to members of our Australasian Institute, who are not members of the Institution of Mining and Metallurgy, if I give a synopsis of the discussion.My attention was drawn to the fact that my paper did not make clear the extent of the improvement in furnace operations, which followed the use of coke of high quality; this comment applied more particularly to the lead content of slag. My failure to supply comparative figures in regard to the lead content of slag was governed by a condition which, I think, is of interest to metallurgists. As a result of industrial...

Jan 1, 1932

By K Shannon, A Shaw

The Hilton and George Fisher deposits occur 22 and 24 km north of Mount Isa, NW Qld, Australia respectively. Both deposits occur as deformed Proterozoic, sediment hosted, stratiform orebodies hosting Pb-Zn-Ag (Hilton) and Zn-Pb-Ag (George Fisher) mineralisation. The two deposits are separated by approximately 2 km of strongly faulted barren shales, mudstones and siltstones along strike. Despite this, correlations between the Hilton and George Fisher deposits have previously been assumed on the basis of textural, lithological and geochemical similarities, but previously lacked specific details to prove exact stratigraphic matches.Feasibility drilling allowed broad correlations based on the position of siltstone pillars separating individual orebodies. However the position of continuous potassium-rich, siliceous and cross-fractured tuffaceous marker beds (TMBs) often used as stratigraphic markers within the Hilton Mine were initially unrecognised within the George Fisher stratigraphy where they are erratically silicified and often not cross-fractured resulting in correlations being difficult to prove. As a more detailed knowledge of TMB locations at George Fisher was gained it was possible to look for corresponding TMBs within the Hilton orebodies. Recent underground stope definition drilling at the two locations enabled specific TMBs, stratigraphic units and even individual sedimentary beds to be matched between the two locations, despite the large separation between mines.The correlation between the two deposits has implications for future exploration drilling north of George Fisher. If a specific stratigraphic horizon can be determined within one hole, positioning of further drillholes can be more accurately planned. The significance of having stratigraphic matches between Hilton and George Fisher also has implications for correlations with other Isa Valley deposits. Convincing preliminary TM and stratigraphic correlations have already been made between George Fisher and the Isa Lead Mine 24 km to the south.

Jan 1, 2002

By J Ramezani, K Faure, N Mortimer

Western New Zealand can be regarded as a rifted continuation of eastern Australia. Detailed studies of units previously considered to have trans-Tasman correlations are being undertaken within the FRST Programme Mineral Wealth of NZ and its EEZ to test specific connections, and thus add to the exploration framework of NZ. Correlation of two major episodes of granitic magmatism are currently being investigated. These represent the oldest (mid Paleozoic) and youngest (Early Cretaceous) magmatic events that conjoined Australia and New Zealand are believed to have in common.

Jan 1, 2007

Support design in jointed or blocky rock masses is often approached by the use of either 'rules of thumb', rock mass classification systems such as the Q-system (Barton, Lien and Lunde, 1974) or RMR (Bieniawski, 1973) or conventional wedge analysis. Generally, this requires that a number of key simplifying assumptions are made and the support system is designed to cater for either a mean, most likely, or worst case scenario depending on the risk tolerance. The design block size is often a major uncertainty and often a worst case block size based on excavation span is used. Thompson and Windsor (2007) state that it is inappropriate to base support designs on the excavation size as these size blocks rarely occur if discontinuity trace lengths are considered. Probabilistic keyblock methods can be used to determine the most likely design block sizes. A methodology is presented whereby JBlock software (Estherhuizen, 1996) is used to estimate potential block sizes as part of the support design process. Using information such as the spacing, orientation and length of discontinuities, it is possible to simulate blocks in the walls of an excavation (Esterhuizen and Streuders, 1998). Keyblock analysis methods (Goodman and Shi, 1985) are used to evaluate whether blocks are removable and whether the chosen support will be sufficient to ensure stability. Data from two mines is used to demonstrate how probabilistic keyblock analyses can be used in support design. Discontinuity data was used to generate 10 000 removable blocks and the design block size statistics were determined. For one mine this information was used to scale blocks in a conventional. Unwedge analysis whilst for the other mine, the point estimate method (Harr, 1987) was applied. The choice of appropriate design acceptance criteria in terms of factor of safety and probability of failure is also considered.

Nov 25, 2010

By J F. Seale

The design of the settling pond for the Malvern Hills opencast coal project was based on a primary requirement to control runoff and sediment generated from the immediate 6 ha mine catchment, which included two seepages from old underground workings. The pond has been particularly effective in controlling turbidity in the outflow water, with the consent limit of 50 NTU being met on all but one occasion and normal levels of discharge less than 10 NTU. Water quality testing carried out at the time of consenting indicated that there were no acid-generation issues with the proposed mine site in dominant mudstone strata of the Broken River Formation, and that water from the old mine workings was near-neutral in terms of pH and well-buffered. However, it became apparent over the very dry summer of 2003 - 2004 that slaking of the exposed mudrocks in the mine batters was resulting in significant acidity generation, and outflow pH levels were well below the consent limit of 6.5 during and following periods of rainfall. Although these acidity problems have been remediated in the short-term by the use of lime products, it is clear that a programme of lithotype characterisation for AMD should have been undertaken and this has now been implemented. Design of long-term acid drainage control measures is being carried out, and will probably be based around the use of hydrated lime for pH control with enhancement of natural wetlands.

Jan 1, 2004

Of the world's total production of gold the largest proportion comes from the more regularly consistent ore bodies, but in the aggregate an important part comes from those which are often irregular, uncertain and small. These smaller ore bodies are often high in grade and, as the capital required to work them is not large, they appeal to people seeking a quick and profitable return for a small outlay.These small mining concerns cannot afford detailed geological and petrological investigations and mapping, so they are very often dependent on local knowledge and experience which admittedly may be of really great value.Nevertheless the absence of skilled guidance may not only cause good opportunities for intelligent exploration to be lost, but discourage the seach for other ore bodies.lVIining engineers in the course of their travels in the examination of mines often come across such cases and also others where problems of finding lost ore bodies have been solved by the man on the spot. As records of cases are valuable and useful additions to the knowledge of ore occurrences, the writer now proposes to describe one such case coming under his observation in recent years.It is that of a small mine, known as the Idaho, at the southern end of the famous "Golden Mile" at Kalgoorlie (see Fig. 1). This mine has been a small and very erratic producer ever since it was abandoned by an English company which owned it forty years ago. Except for one period of four years it has always been owned and worked by parties of co-operative miners and during its time has gone through a tortuous career. Although it has often...

Jan 1, 1938

By W E. Vance, B H. Ashton

The emission of seam gases into underground workings in coal mines is acknowledged as a major hazard, particularly methane due to its possible ignition. Acknowledge of seam gas parameters is important for the prediction of gas emission rates into the ventilating air current. They are also important as the basis for the evaluation of the likely contained gas as a possible energy source.   Gas content determinations for the Kupakupa seam have been made at the Huntly West Mine.  Applying the method of Creedy (1986) to face samples, gas contents of 1.80 and 1.66 have been determined. Using desorbed and residual gas content data a content of 1.92 m3/t has been derived. These are on an ash included basis. Calculations using the adsorption equation of Kim (1977) and coal quality have given a gas content of 2.19 m3 t. Long-hole exploration drilling at Huntly West Mine has provided information on gas pressure. A pressure rise test has given a reading of 500 kPa (absolute); this is low compared with the pressure given for the determined gas content from theoretical adsorption isotherms.

Jan 1, 1991

By Cocquio D. S, Bauchau C

In the course of an integrated airborne survey in 1975, a uranium-molybdenum deposit was discovered by Minatome Australia Pty Limited in North Queensland, Australia, approximately 70 km by road west of Townsville.The mineralization occurs in a welded tuff unit within the Carboniferous St James Vokanics. It is structurally controlled by a complex of subvertical east-west fractures and is exposed over a strike length of 350 m. Drilling has traced a further 150 m extension underneath a barren capping consisting of a thick pile of vokano-sediments. The maximum width of the orebody is 150 m, and its vertical thickness is approximately 100 m.The primary ore minerals are coffinite, pitchblende and molybdenite, accompanied by various alteration products (particularly uranium molybdates).The vein-type mineralization is considered epigenetic.A comprehensive program of surface drilling and underground exploration is in progress to establish the uranium and molybdenum reserves.

Jan 1, 1980

By M A. Mongillo

Most geophysical and geochemical data collected during regional exploration programmes are in vector form (location, value), and have traditionally been presented and interpreted in a profile or contour map format. However, the human vision system can interpret data presented in image format much more easily and new information is often revealed by the judicious application of powerful interactive computer image enhancement techniques. This paper describes a practical demonstration of the application of such tools to gravity and resistivity datasets from the Central Volcanic Region of theNorth Island.   Filtering, contrast enhancement, relief shading, pseudo-colouring and then overlaying of the gridded datasets in image format has helped identify inter-relationships such as the association between many low resistivity anomalies (epithermal deposits or geothermal resources) and the edges of large gravity anomalies (calderas or grabens). Similar revelations should result from the application of these tools to the integration of other mapped datasets from geophysical, geochemical and geological disciplines.

Jan 1, 1992

By R J. Merchant

The Hauraki goldfield is located east of Auckland in the North Island of New Zealand. It includes Great Barrier Island, the Coromandel Peninsula and the Coromandel and Kaimai Ranges as far south as the town of Te Aroha and south east to Te Puke. It has a total north-south extent of about 180 km and an area of 3000 km2. The goldfield is the most productive in New Zealand, and while production at present is negligible, the area has undergone continuous exploration over the last seven years.

Jan 1, 1984

Holla has given a good background to the various methods of subsidence control in the coalfields around Sydney.The present writer notes that in many cases, especially with wide longwall panels, there is not the flexibility to alter the mine layout as there is to some degree with the various pillar extraction methods. For this reason it may not be possible to plan the workings to minimise subsidence and some damage to structures may occur. The cost of repair or the cost of subsidence provisions to minimise damage may be small in relation to the tonnages of coal which would otherwise have to be sterilised. One method of subsidence control which has been in use in the Newcastle area since 1970 is the panel and pillar layout (partial extraction layouts with stable pillars). An extracted panel width of 0.6 times the depth of cover resulted in a maximum subsidence of 115 mm for an extracted seam thickness of 2.2 m.As Holla points out, the extracted panel widths in relation to th depth of cover depend on the particular geological setting. His Fig. 3 shows that the subsidence over a panel width of 0.3 times the cover depth in the Southern Coalfield is the same as over a panel width of 0.55 to 0.6 times the cover depth in the Northern Coalfield.Selective pillar extraction and longwall mining can both be used in the panel and pillar layout. Holla's Figs 2 and 3 are used to estimate the maximum subsidence over an extracted panel of known geometry. Maximum subsidence is related to seam thickness. What provision is made for a reduction in subsidence due to the coal which remains behind in a pillar extraction panel if the pillar recovery is poor? The writer suggests that an effective seam height could be used, based on the actual mining height reduced by a factor to account for the percentage recovery of coal from an extracted panel.

Jan 1, 1986

The early records of hydraulic elevator and bucket ladder dredging in the Clutha River system indicate the success of that era of alluvial gold mining in Otago. This paper briefly reviews parameters of depth and gold grade for alluvial operations. The application of dragline technology is proposed for the economic removal of overburden to target the deeper alluvial gold areas which remain in the Otago region.

Jan 1, 1992

By Madgwick J. C

Microaerobic biodegradation oflow-grade manganese dioxide slurry tailings was demonstrated in enrichment cultures treated with dilute molasses at 30°C and pH 5·8. Supplementary nitrogenous nutrients, yeast extract addition and pH adjustment were not required.Continuously stirred, air-limited reactors were superior to still intermittently agitated cultures, in that, at 5 per cent (w/v) MnOz tailings and 5 per cent (w/v) molasses, the yield of 0.12 g Mn++/g molasses, the rate ofleaching of 1·06 g Mn++/l/d and a recovery of Mn++ of 58 percent from MnOz were 2·8 times, 1·7 times and 1·9 times greater, respectively. The best compromise in yield (0·45 g Mn++/g molasses) and rate ofdissolution (0·73 gMn++/l/d) was at 1 per cent (w/v) molasses in a stirred reactor.Where leaching organisms were separated from sterile ore by a bacteria impermeable membrane leaching was shown to be some 20 per cent due to diffusible metabolites and 80 per cent due to a direct contact between the bacteria and the ore particle's surfaces.

Jan 1, 1986

By M E. Dunphy, P Silversmith

The Reefton Goldfield, both historically and potentially, represents a significant gold producing camp in the Westland province of New Zealand. Some two million ounces of gold have been produced from the Greenland Group host rocks between 1870 and 1951 with the most significant producers being the Blackwater and Globe Progress mines.   Steep terrain, high rainfall, poor outcrop, widespread fluvio-glacial deposits, tertiary cover and sometimes onerous environmental access conditions have proved a challenge to conventional exploration techniques. In addition classic exploration techniques have come up against a desire to reduce exploration cycle time and exploration costs while increasing both quality and quantity of geological information.   The trial, and subsequent implementation, of Wacker sampling has proved a highly successful and effective geochemical tool currently being utilised to target, discover, and define potential economic gold mineralisation in the Reefton Goldfield.

Jan 1, 1997

By Hemingway P, Boag J

Major operating aspects of the Mary Kathleen Uranium Ltd. treatment plant are discussed with partkular reference to those which are peculiar to this operation.Problems associated with the production of a penalty free uranium oxide product are examined and the methods developed to overcome them are described in detail.INTRODUCTIONMary K,athleen Uranium Ltd. is the largest of the Australian uranium producers. The flow-sheet is based on fine grinding, standard sulphuric acid leach, ion exchange concentration, and magnesia precipitation of the final product, with certain modifications introduced as the result of pilot plant investigations at the South Australian Department of Mines Research Laboratories in Adelaide.The plant commenced operations in June, 1958, attained design tonnlige of 1,120 tons per day in September of that year and has since operated continuously with a throughput in excess of 1,000 tons per day. Pilot plant recommendations generally have been followed, and predicted results have been attained. The only exception has been the silica and rare earth content of the product produced during the early months of operation. Considerable modification of the early resin regeneration techniques resulted in the reduction of the silica content of the product to within specification limits. Research work in the ion exchange section has also resulted in the reduction of the rare earth content of the product to below specification levels. All product now being produced is completely within the agreed specification limits of impurities.

Jan 1, 1961

By F Linares, B De Waele, K Bischoff, M Lacorde, G Loveday

Recent exploration has identified the presence of detrital iron deposits (DIDs) associated with banded iron formation (BIF) units in the north-west of the Congo Craton, Gabon. The regional geology comprises a complex of granitoids and gneisses assigned to the Archaean Chaillu Complex, within which older slivers of lower amphibolite-grade greenstones are preserved including muscovite-biotite-garnet-bearing felsic schist, amphibolite and BIF. These units are typically overlain by several metres of residuum comprising colluvium, eluvium and duricrust. The residuum is overlain by a regionally extensive loess cover from 2 m to 10 m thick.The DIDs occur within the weathered residuum as mostly unconsolidated gravels with lesser canga (CAN) duricrust draped over deeply weathered hematite. Head grades are in the range of 45 to 52 per cent Fe. Fresh BIF, located from 30 to 50 m below surface, is comprised of magnetite-quartz±amphibole. The detrital iron gravels are comprised of rod- and plate-shaped clasts of hematite (martite)-maghemite-goethite composition, in a ferruginous sand to clay-sized matrix. The DID form ridges and plateaus that coincide with magnetic highs defined using high-resolution ground magnetic surveys.The field relations and petrography indicate that the detrital iron accumulations are the result of weathering (including enrichment) and erosion of primary BIF. This includes removal of quartz, further oxidation and re-cementation of BIF to form ferruginous caprock. This cap and the in situ oxidised BIF were subsequently disaggregated and liberated, and further weathered to form the detrital iron accumulations.Metallurgical test work on bulk detrital iron samples has shown this material can be upgraded to lump and fines iron ore products with grades of 62 to 65 per cent Fe using simple scrubbing and wet screening, followed by dense media separation of the -1 mm fraction, with overall mass yields from 75 to 85 per cent. The test work indicates a high ratio of lump to fines products, sometimes exceeding 50:50.CITATION:De Waele, B, Lacorde, M, Bischoff, K, Loveday, G and Linares, F, 2017. Geological and metallurgical characteristics of banded iron formation associated detrital iron mineralisation in Central West Africa, in Proceedings Iron Ore 2017, pp 259–268 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

Few, if any, reliable thermodynamic data are available for the activity of tin oxide in slags. In this work, the activity of the oxide in silica saturated iron silicate slags has been measured at 1573 K using the equilibrium Sn (alloy) + Y2O2-SnO (slag).Slag and a Ag-Sn alloy were sealed in a zirconium oxide crucible to prevent the escape of volatile tin oxide, and the oxygen pressure at equilibrium measured in situ using the zirconium oxide as a solid electrolyte. Activity of tin was calculated from known data for the Ag-Sn system and activity of tin oxide calculated from free energy data. The results have been extrapolated to predict the industrially important distribution of tin and iron between Fe-Sn alloy and iron silicate based slags.

Jan 1, 1983

For the purposes of this discussion it is assumed that contributors should express the thoughts that arise from their personal experience. So wide is the range of mineral deposits, and so varied the methods employed in their discovery and development, that no two geologists are likely to have been impressed with the same applications of their science. The author's own personal experience has been, during recent years at least, very largely concerned with the broader aspects of the employment of scientific method and geological knowledge to the problems of exploration and exploitation, for the guidance of the general public and governmental authority rather than of mine executives and directors. The view-point thus reached is likely to differ in many respects from that of men who are much more intimately concerned with the mining problems of a single metal or a single mining field, and for this reason a statement may perhaps supplement those from others whose experience has been markedly different.It may well happen that, at some not distant date in the future, when systematic and comprehensive instruction in economic geology is embodied in the courses- prescribed for mining engineers during their years of training, the author's comments will be quitesuperfluous; but at the present time they appear to him to call for expression.The Need for Training of Mining Men in Economic Geology.Contact over a period of many years with mining men who have had different kinds of training and experience has been convincing that there is a general reluctance to acquire a full rational understanding of the geological factors involved in exploratory and developmental problems. The correction of this attitude is regarded as vital to the industry and it is necessary to insist that the outstanding requirement of the present day is the utilization of all branches of geological, investigation in the field and the laboratoryby men who have had systematic and specialized training in these matters. The science of geology is many-sided, but is, nevertheless, whole and essentially indivisible. No one can afford to disregard any fraction of its content 'or any of its methods of investigation.The greatest advances have been made in the understarnding of the occurrence of mineral deposits by those whose knowledge Qfbasal principles, has been soundest, whose endeavour has been to ascertain all their relationships in space and time, whose attention to detail of all kinds has been keenest, and at the same time, whose capability to distinguish between major and minor features has been most marked.With the passage of the years and the accumulation of data from many lands, it has been possible to build up a great body of information regarding the primary deposition and secondary alteration of mineral occurrences, which is of the utmost value in guiding thesearch for new deposits to take the place of those that become exhausted. This heritage is due not only to the efforts of gifted in...

Jan 1, 1950

By Healy T. W, Dixon D. R

The present study 'of pure ZnS and NiS and ZnS (marmatite) by detailed electrokinetic methods has shown that by careful control of experimental parameters much new' information on sulphide-water interfaces can be obtained. Time-dependent processes of alteration of sulphide surfaces are foHowed by electrokinetic methods and indicate that the isoelectric point of the surface depends on elemental sulphur coverage, oxidation product coverage, and the conditions which promote or minimize such reaotions in the presence and absence of activator.

Jan 1, 1977

By C Moorhead

The classification of Mineral Resource estimates for reporting in accordance with the JORC Code is a statement of the Competent PersonÆs confidence in the estimate and an attempt to convey that confidence to the various users of the resource estimate. In general the classification process is either largely subjective, relying on the Competent PersonÆs experience, or relies on statistical measures derived from the estimation process. These statistical measures may not necessarily relate to the overall confidence in the resource which must also take account of the confidence in the geological inputs to the estimation. Several authors, including Jackson et al (2003) and Dominy, Noppe and Annels (2004), have addressed methods of including consideration of geological data and its reliability into the classification process. Henry and Parker (2005) have discussed a quantitative measure for classification of Measured and Indicated Resources related to mine production parcels. These methods rely on the availability of sufficient information for the application of geostatistics, data evaluation techniques or repeated interpretation of data to provide an indication of confidence. They are suitable for very advanced projects. In 2005, using a modification of the financial audit æcontrol and quality criteriaÆ principles, then widely accepted within Newcrest Mining Limited (Newcrest), the principal author developed a scheme which categorised the classified resources into æcontrolÆ and æqualityÆ (or risk) categories. Control covers all aspects of the data collection, the geological interpretation, the data analysis and the modelling of tonnage and grade; it is also influenced by the documentation of the estimate. The quality criteria are a subjective measure of risk associated with the estimation of the resource and refer to the risk that the tonnage and grade are not realised and the consequences if decisions are made on the basis of these estimates. By evaluating the generally accepted level of risk attributed to these quality ratings by Competent Persons within Newcrest, a graphical representation of the confidence in the resource ounces was prepared for communication of the expected confidence in the resource statement.

Jan 1, 2009