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By S Prakash, P S. R Reddy, S K. Biswal, V N

The beneficiation potentials of two Indian iron ore slime samples by flotation technique using both cationic and anionic collectors are investigated. The direct and reverse flotation of slimes using oleic acid and dodecylamine as the collector have been studied using both conventional cell and flotation column to upgrade the iron content. The characterisation studies of iron ore slimes indicated that the samples are extremely fine in nature and contain substantial amounts of martite, magnetite, goethite, limonite, kaolinite and quartz beside hematite as the dominant iron mineral phase. The samples on average contain around 52 - 58 per cent Fe, four to seven per cent SiO2 and five to six per cent Al2O3. Taking into account the physico-chemical properties of the slimes, it is attributed that both the samples need to be deslimed by hydrocyclone before flotation. The results of both cell and column studies on sample I showed that a feed containing 57.5 per cent Fe could be upgraded to 65.5 per cent Fe at 50 per cent overall recovery with simultaneous decrease in SiO2 and Al2O3 content to 2.3 per cent and 1.8 per cent respectively by using oleic acid as the collector. In the case of sample II, it has been established that reverse flotation of silica is the better technique to improve both the grade and recovery of iron. Batch flotation studies in cell indicated that a product with 63.1 per cent Fe could be obtained at 40.0 per cent yield with 63.6 per cent iron recovery by the combination of reagents such as gum acacia, sodium hexa meta phosphate and dodecylamine. The performance of column flotation techniques is far superior to that of the cell with respect to both grade and recovery. The concentrates are found to be quite suitable for commercial exploitation as pellet feed.

Jan 1, 2005

By Ulvelin K, Antila K

Large scale cut and fill mining in narrow silver-lead-zinc orebodies began at Mount Isa in 1964. Initially each orebody was one stope and access was via raises from the level above. Upholing was the principal mining method, although flatbacking was employed where ground conditions were more difficult. Developments since have included access via footwall inclines and connection of all stopes with major crosscuts. Flatbacking is the principal method. The most recent cut and fill operation is now fully mechanised using drilling jumbos, rockbolting jumbos and load-haul-dump units. Improved ground support and drilling and blasting practices have enhanced safety, recovery and productivity in all cut and fill operations.

Jan 1, 1988

By Moort van J C

A new low-intensity magnetic separator which operates by spinning particles in a continuously rotating magnetic field is able to reduce particle entrapment of non-magnetics to an almost insignificant level. In such separators the removal of ma

Jan 1, 1997

By Kim YC

An alternative development drilling strategy to the one currently in use at an open pit mine was investigated using geostatistics for a portion of the pit. The massive orebody, the 3-D nature of the problem, and the location of ultimate pit limit in the study area all created some unique problems in devising the development drilling strategy. Rather than using confidence interval of the global reserve estimate as the main criterion for development drilling, the confidence interval of short and medium range mine planning blocks was used as the objective. Based on somewhat arbitrarily selected level of confidence, the results from the study showed that a total of 50 diamond drillholes (DDHs) rather than the planned 62 DDHs is sufficient in the study area, if the selected confidence levels are acceptable to the management. The paper also emphasizes the importance of particular objectives being used in development drilling and how they influence the "optimal" placement of the development drillholes.

Jan 1, 1986

By Yamamoto Y, Ohyama H

In case of NATM, mechanical cutting is desirable in view of the original purpose of not spoiling natural ground. As typical tunnelling machines, there are two (2) kinds available: one is "Full Face Excavator" known as TBM (tunnel boring machine), and the other is "Roadheader" known as Part Face Excavator. By the use of the former, accurate profile cut is made possible, but there is a limit in the shape of a cutting section. By the use of the latter, cutting of various sections is made possible, but in order to cut a section economically and accurately, operators are required to have a high level of skill. In this text, we introduce Automatic Controlled Profile Cutting System (hereafter "ACPC" System) developed as a roadheader.

Jan 1, 1987

By M Ben, P de Donato, M Kongolo

The extensive literature on sulfide flotation indicates that pyrite poorly floats under alkaline condition. Xanthate concentration has a positive effect on pyrite flotation, but above a pH of 11, pyrite seems to be strongly depressed, independently of the concentration in xanthate. In this investigation, aeration and xanthate concentration effects were studied for pyrite flotation conditioned at pH 11 with lime. Results presented in this paper include surface infrared analyses and pulp chemistry measurements which have showed that aeration had a dual effect on pyrite flotation. It induced pyrite surface activation by oxygen, and oxidation of ferrous iron to ferric hydroxides or oxyhydroxides species. It also favoured dissolution of CO2, leading to calcium carbonate precipitation and adsorption onto pyrite surface. Both CO2 dissolution and ferrous oxidation generated protons and decreased pulp pH. Pyrite flotation was observed to be effective with a statistical monolayer of xanthate that could be adsorbed as mixture of dixanthogen and metal-xanthate complex. Non-floated fractions showed high amounts of carbonate, and presence of hydroxyl iron sulfate (Fen(OH)m(SO4)p, xH2O) which have inhibited the hydrophobicity effect of adsorbed xanthate. Environmental desulfurisation could be improved by aeration control causing pyrite oxidation and pH decrease to reach optimal flotation condition with a relatively low xanthate concentration.

Jan 1, 2005

By Schofield N. A

The cross-sectional method of stope grade estimation at Cobar Mines has consistently had several shoneomings, me most imponant of which being mat stope grade is significantly overestimated in the high grade lenses.The use of mree-dimensional ore lens modelling improved the grade estimation and ore waste definition but significant overestimation still occurred in me high grade stopes, particularly those wim extremely variable grade distribution. The implementation of an indicalor kriging based method for mapping of me high grade copper mineralization has significantly improved the quality of copper grade estimates and provides a mineralisation geometry similar to that generated manually by me mine geologists. This paper presents the results of a test case study in the application of indicator kriging to the mapping of the copper grade in two stopes in the QTS North mineralisation. The results are encouraging in that they prov ide coofi rmation of the geometrical model developed by the geologists and much improved estimates of the grades of me stopes whencompared to me grade reponed from mining these stopes.

Jan 1, 1993

By Forsythe DJ, Sun S-S Andrew AS

Paragenetic, fluid inclusion, stable isotope, and 87Sr/86Sr and 143Nd/144Nd isotope studies of the Mt Carbine tungsten deposit in North Queensland provide information on the sources of the mineralising components and record the history of fluid-rock interaction during the hydrothermal process. The ore minerals , wolframite and scheelite , are contained in quartz veins which post-date the major deformations in the Siluro-Devonian Hodgkinson Formation . Mineralisation was immediately preceded by the emplacement of the Mossman Batholith (280 ¦ 7 Ma). Two major stages of mineralisation are present and separated by a brittle fracturing episode . The stable isotope and Sr and Nd isotope data suggest that the ore fluids during stage I and most of stage II mineralisation were a mixture of magmatic water and non-magmatic water (connate or metamorphic) which had experienced a long residence time and had extensively exchanged with the sediments at high temperature. Subsequent mineralisation events were dominated by fluids of meteoric derivation with a short residence time. The data imply that other solutes, such as W, were probably derived in minor part from local country rock sources with the major contribution coming from a magmatic source related to the granite batholith.

Jan 1, 1987

By Pyrih R, House A, Shangraw J, Silva AJ

Sunbeam Mining -Corporation has the inten mine with heap leach gold recovery, near spent ore indicated a relatively high ar topographical configuration, the spent across a small drainage and a lake. Du permit for spent ore disposal from th agencies, concerns about the potential contamination by the arsenic were expres conducted extensive studies to addre contamination. These studies consiste( geochemical and geotechnical parameters underlying the proposed disposal si geotechnical investigations were also hydrologic characteristics were include with the use of an IBM PC computer. :ion of opening an open pit gold Stanley, Idaho. Testing of the ?enic content. Due to the local ore was planned to be disposed :ing the process of obtaining a federal and state regulatory for surface and ground water .ed. Sunbeam Mining Corporation is the potential for arsenic of laboratory testing of both of the spent ore, and the soils te. Field hydrogeologic and -onducted. Local climatic and 1 in the analysis of these data Conclusions of studies indicated that although the seepage through the spent ore disposal would contain an elevated dissolved arsenic content, the hydrologic and geochemical characteristics of the site would prevent arsenic migration into the local ground water system. The attenuation of arsenic on soils with high clay content, and dilution after reaching the ground water table would lower the arsenic content to acceptable Concentrations.

Jan 1, 1988

By Quast K. B

The ore used in this test program was a composite sample from Waihi, New Zealand containing 2.7 g/t gold and 36 g/t silver. From the testwork it was found that a high concentration of sodium cyanide (0.1 per cent) was necessary to ensure a high recovery of both gold and silver. There appeared little chance for either differential leaching or adsorption of gold and silver. The addition of bentonite clay decreased the rates of gold and silver dissolution. The addition of 50 g/1 NaCI had little influence on the rate of silver extraction. The addition of 5 g/l carbon gave adsorptions of 70 per cent of the gold and 35 per cent of the silver, indicating the possible presence of base metal cyanides in solution. The addition of excess sodium sulphide only precipitated 70 per cent of the silver in solution, adding further evidence to the presence of base metal sulphides. The production of separate silver and gold products was not possible by either preferential leaching, preferential adsorption of gold on carbon or preferential precipitation of silver.

Jan 1, 1991

The twin iron ore islands of Cockatoo and Koolan are located in the spectacular setting of Buccaneer Archipelago off the Kimberley coastline of WA.Cessation of ore shipments from Koolan in 1993 ended 42 years of continuous mining activity which began with the first shipment of ore from Cockatoo in 1951.

Jan 1, 1993

The initially cautious approach taken towards ground support and reinforcement at the Porgera Underground Gold Mine in the Highlands of Papua New Guinea has evolved rapidly in the two years since stoping commenced. The confidence to continue the evolution process has grown from an increasing knowledge of mining conditions as stoping has progressed, to the extent that reinforcement requirements have decreased by 50 to 75 per cent depending on local circumstances. Changes to mining practices have significantly assisted and influenced this process.Empirical observations of ground behaviour, assisted by a deliberately selective extensometer monitoring program, provided the stimulus for early changes to ground support and reinforcement practices. Further optimisation of the ground support and reinforcement effort is being pursued through an active monitoring, measuring and analysis program. Ultimately, situation rather than site specific design will ensure continuing high quality ground support and reinforcement installations. However, local structural and lithological factors will continue to become more critical as the optimum position is reached.

Jan 1, 1993

Before the arrival of the first Europeans, Aborigines living in the northern Flinders Ranges mined ochre - an earthy form of haematite used for pigment.The discovery of copper ore at Kapunda and Burra in the 1840s stimulated the early settlers to prospect further north along the ranges. Many of the new discoveries were not properly evaluated and companies were floated on the most tenuous evidence.

Jan 1, 1993

By Vernon PN

The Eossing Uranium Mine is a high tonnage low grade open pit operation using acid leaching for uranium extraction and ion exchange and solvent extraction for solution purification. Advanced technology, much of it computer based, has led to major economies that have contained operating unit costs over the last four years in the face of double figure inflation. An improved ore reserve block model and mine planning system have achieved a considerable reduction in the stripping ratio. Drilling and blasting costs have decreased some 25%, mainly by the introduction of heavy ANFO explosive. A centralised computer control centre for the metallurgical plant has increased labour productivity resulting in improved process control. The all-staff workforce is united with management in the objectives of creating a safe, healthy, working and living environment and a prosperous company, capable of contributing to the wellbeing of the nation and the shareholders. This situation has been brought into being by an equal opportunity policy coupled with a management system emphasising open two-way communication through all levels in the organisation. The success of this policy is highly apparent in the morale and productivity of the workforce.

Jan 1, 1986

The necessity for good management and economic working in our mines and ore-dressing sheds is impressed upon us by the present low prices of all our metals. Silver, lead, copper, and tin have all suffered a heavy decline during the last six or twelve months, and many mines have been shut down simply on account of the low market value of the ore produced. After fully considering the position of the mining industry. I am convinced that considerable improvements will have to be made to make it as prosperous as it ought to be. The most obvious of these improvements are good management, good machinery, and as little interference by directors as possible. If these conditions are insisted upon and carried out efficielltly a poor mine may have a chance to weather the storm.There is no doubt that the present depression is the refilult of over-speculation and general loss of confidence by which the whole commercial system has been affected, and every branch has suffered more or less, mining not excepted. It has suffered heavy losses in the past, and the future is not over bright we are, therefore, compelled to be careful in everything by which mining is affected and savings can be secured.

Historical exploration of the Ballarat East goldfield defined two primary quartz vein lode types. Tracking the intersection of these lodes with vertical lines of enrichment (or so-called æindicatorsÆ) was the basic practice for historical mining. This strategy proved highly successful in terms of identifying quartz veins associated with mineralisation. However, it provides little understanding of the timing or processes involved in the formation of these veins, or the associated emplacement of gold. Current underground mapping shows the Ballarat East gold deposit can be subdivided into four stages of vein formation. The earliest veins (V1 and V2) strike north-south and formed during bedding flexural slip and limb thrust fault propagation in parasitic chevron folds. V3 veins are subhorizontal and relate to further fold tightening involving a transition from east-west compression to north-south extension that initiated re-shear of bedded slip surfaces and additional strike-slip faults. Sporadic V4 veins overprint the shallow-dipping sections of V2 and V3 veins and are associated with weak north-south compression. The V4 veins mineralogy is distinguished by a high carbonate content and sphalerite-galena sulfide assemblage. Vein sampling indicates a significant increase in gold mineralisation where overprinting by the later deformation/veining has occurred. As a result of these observations, a new model is emerging that identifies the chronology, structural control and spatial distribution of respective quartz vein types. This is a major advance in terms of exploration targeting, resource modelling and mine planning.

Jan 1, 2008

Silver-lead mineralization at Indooroopilly, Queensland, extends upwards from Upper Triassic rhyolite which intrudes phyllite-containing Palaeozoic mineralization.Sulphides and magma were emplaced in a special structural site which underwent dilational fracturing while surrounding rocks were block-faulted and compressed. This site lies at tbe intersection of dykes, faults, and a lineament adjacent to a Middle Triassic granitic stock.Structural controls at Indooroopilly are attributed to the effects of piston faulting. Exploration for similarly controlled deposits should be directed towards structural intersections near stocks or batholiths which have intruded mineralized belts. Priority should be given to structural intersections which were sites of block-faulting and igneous activity under compressional tectonic conditions.Favourable sites lacking surface mineralization may contain ore at depth as piston faulting produces 'blind' ore deposits.

Jan 1, 1976

Present knowledge of the Pacific floor in- dicates: Postulated subduction zones and/or moving basements overlain by undisturbed sediments. Contiguous mantle convections of conflict ing directions and variable rates. Disharmony between transform faults and mantle convections. =hese features are shown to be difficult to reconcile with conventional hypotheses of sea f 1mr spreading and cast the model into serious doubt.

Jan 1, 1987

By Heidecker A

Several types of drainage structure providecost-effective environmental controls for water supply to Charters Towers and its mining industry. Drainage groves maintain bank-levee, channel, pool, and spring structures. Failure of drainage structures leads to anoxic fermentation of channel fill releasing residues, such as arsenic, which would otherwise pass harmlesly by fixed on sedimentary particles.Experiments along drainage structures indicate that productive agroforestry could be integrated with expeditious development of groves to cope with environmental change.

Jan 1, 1990

By Bolton G. C

Experiments were conducted to access the feasibility of removing zinc from lead slag by sulfation or chlorination or both. Gaseous sulfation with sulfur dioxide and oxygen released only 50 per cent of zinc even under the most severe conditions. Sulfation with concentrated sulfuric acid by a fast-leach process released 95 per cent of zinc while pug-roasting released a maximum of 78 per cent of zinc. Chloridization with NaCi in the presence of sulfating gas released 50 per cent of zinc, while direct chlorination with chlorine gas and oxygen released 85 per cent of zinc and 100 per cent of lead in a chloride condensate containing little impurities.

Jan 1, 1980