Search Documents

By Marquez W

Trace fossils have been found in Bolivian Silurian sediments in "La Iumhre" area close to La Paz-Bolivia.Tracks, are good indicators of depth and environment. A detailed study of the ichnogenus is made.The depth and environmental deposits are analyzed to determine the facies. It was shown that the trace fossils of Silurian sediments in La Paz belong to the Zoophvcos and Nereites facies.

Jan 1, 1990

By Woodcock J. T, Millett R. N

It was shown that manganese dioxide could be used as an oxidant in acid thiourea leaching of a gold ore. Manganese dioxide could generate high redox potentials and was as effective as hydrogen peroxide in the leaching process. Results obtained under closely controlled leaching conditions confirmed that high redox potentials enabled faster dissolution of gold to be obtained but led to extremely high reagent consumptions (thiourea, acid, and manganese dioxide). Additions of sodium sulphite solution in an attempt to lower thiourea consumption by reducing formamidine disulphide back to thiourea were only marginally successful. Although thio- urea consumption was slightly decreased, the consumption of acid and manganese dioxide was substantially increased and there was no net benefit in using sulphite. Tests in which a single addition of mangan- ese dioxide was made before addition of thiourea minimized overall reagent consumption and gave only a slightly lower dissolution rate of gold. This is a promising technique for further Investigation.

Jan 1, 1987

A major tool in the search for petroleum is reflection seismic mapping. The period which has seen most of the exploration in Victoria is also one which has seen major advances in this technology, from 1963 try present day. Seismic mapping can be divided into three interlinked areas - acquisition, processing, and interpretation. In acquisition the major changes have been from an explosive energy source in 1963 to gas exploders in 1968 and airguns in 1970. The number of recording channels has increased from 24 to 192, with digital recording introduced in 1966, and floating point recording in 1976.

Jan 1, 1982

By Thompson IR, Solomons SS

Underground mining with the cut and fill method has been declining during the past decade or so, being replaced mostly by sublevel open stoping methods. During 1983 the Australian Mineral Industries Research Association Ltd. (AMIRA) commissioned a review of the method, with the aim of compiling the state-of-the-art, indicating future trends and recommending topics for research that would be needed to support this future mining. Mines using the cut and fill method in Australia and three other countries were visited to compile current practices and expected developments.Cut and fill is mostly used where geological and ground conditions are unsuitable for open or caving methods. These range from narrow, irregular orebodies to wide, massive orebodies where pillars are retained in ore. There is significant potential for improvement and further development of the method. It may then be used in a broader range of conditions and for orebodies that may not otherwise be viable to mine.

Jan 1, 1985

An ongoing research program into surface subsidence over Room and Pillar coal mining is described. A subsidence monitoring network has been established for one Room and Pillar mine in the West Moreton Coal Field of South East Queensland, at which pillar extraction is being conducted. The maximum measured subsidence to 28 January 1986 was 638 mm, with movement continuing. Analysis of the monitoring data with view to application of the subsidence pre- diction theory developed by Kowalczyk (1972) is discussed. The Kowalczyk theory provides predictions of subsidence depression, slope of surface, horizontal displacement, surface curvature and horizontal strain, for both the Partial and Total Settlement cases. The development of subsidence with time is also investigated and a preliminary analysis conducted.

Jan 1, 1986

By Recepoglu O, Tolun R, Yavasoglu N, Bulutcu AN

Scheelite was floated from a low-grade (0.28 per cent W03) calcitic (96.30 per cent CaCO3) scheelite ore using oleoyl sarcosine as collector and alkylated 8-hydroxyquinoline as modifier. Compared to oleoyl sarcosine alone, the grade and the recovery of scheelite concentrate were increased from 8.07 per cent to 33.54 per cent and from 55.1 per cent to 73.4 per cent, respectively. Infrared studies with pure calcite and scheelite minerals showed that while alkyl oxine is adsorbed on the scheelite surface, it is not adsorbed on the calcite.

Jan 1, 1993

By J Robinson, L D’Uva

"The Gold Fields group and Gekko Systems have successfully worked together on multiple projects, including at the St Ives, Agnew and Granny Smith operations in Western Australia, and the Damang operations in Ghana, with gravity recovery design, technology installation and optimisation the key driver on each occasion.In 2014, Gold Fields Australia identified an opportunity to challenge the historical thinking at Granny Smith and reassessed the benefit of upfront gravity gold recovery. The historical approach had been to employ gravity on the tailings stream of the carbon-in-pulp (CIP) circuit, recovering sulfide minerals into a concentrate from spiral concentrators for further liberation of gold via a regrind circuit.Gekko was engaged to assess the implementation of a gravity circuit within the grinding area, and to perform a comprehensive gravity recoverable gold test program. Test data was fed into the AMIRA P420 BCC Gravity Model to confirm the gravity recovery potential of the ore, and for process design basis generation. Height, space and capital limitations proved to be a design challenge. However, collaborative learnings throughout the project ensured the design and operation of a reliable and economic gravity gold circuit. Ultimately, the Granny Smith gravity circuit was a success, satisfying all the project objectives and yielding consistent, measurable benefits. On average, the gravity circuit recovers 33 per cent of total gold, resulting in an increase to overall gold recovery by 0.7 per cent.This paper highlights the key project drivers for Gold Fields, and the development of the Granny Smith free gold gravity circuit. It details application of test work and modelling, and the challenges and learnings encountered during the design, installation and commissioning stages. This paper seeks to demonstrate that continuous improvement in a long standing operation can be beneficial to overall circuit flexibility and increased ounce production.Citation:D'Uva, L, Robinson, J and Bell, T, 2016. Defying Gravity - Brownfield Continuous Improvement, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 135–144 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By Webster SS

This paper uses computer modelling tech- niques to compare and contrast anomaly patterns obtained with fluxgate (vertical field) and proton precession (total field) magnetometers at typical latitudes in northern and southern Australia. The use of these modelling tech- niques is suggested as an aid to magnetic interpretation and field examples are included from Tasmania and the Northern Territory.

Jan 1, 1975

By Johns A. L

The concept of the Melbourne Underground Rail Loop and the organ- isation to achieve its construction are covered in the companion papers (Reference 1, 2) and will not be repeated here. The Victorian Railways, as well as being the eventual operator of the Loop when it is completed by MURLA, have also been responsible as "Contractors" to MURLA for the construction of the "cut and cover" or "box" tunnels and related approach works located on existing Railway property. These tunnel connections link the existing suburban system to the new underground works. The following tabulation indicates the significant work volume involved in this cut and cover tunnelling exercise and which is covered in some detail by this paper.

Jan 1, 1981

By A L. Wills

Cliffs Natural Resources Pty Ltd (Cliffs) operates iron ore mines in the Koolyanobbing region of Western Australia. Ore is mined from three separate hubs and trucked to Koolyanobbing. There it is crushed and screened to lump and fines finished products and railed to Esperance port for export to Asian customers. Cliffs is renowned in the marketplace for its consistent product quality. In 2010, 9 Mt of ore was exported to Asia.Over the last three years, Cliffs has systematically refurbished its product quality system (PQS), to improve efficiency of production while maintaining its high standard of product quality. Particular attention has been given to reducing inventory, which has required significant modifications to the production process design.In redesigning the production process, emphasis was placed on maximising the application of the inherent blending in each of the production process steps and dedicated blending was only introduced where essential. Simulation modelling and statistical analysis of process capabilities were utilised to develop a system that optimises inventory, minimises rehandle, eliminates several decision-making steps and maintains a pull focus throughout the value chain.The new planning functions are now fully integrated and effectively control long-term grade variability rather than relying on long-term stockpiling. The production process design and the daily crusher blend plan are used to control short-term grade variability. With the upgrading of the planning processes the accuracy and consistency of algorithms for lump per cent and lump and fi nes grades became more important and an increased geometallurgical function has been added to the company.The continuous stockpile management system was upgraded to increase the effectiveness of the daily crusher blend planning process and is now the sole intervention point in the production process for grade-based decisions. Grade control systems were modified to utilise advances in software and geostatistics to deliver accurate short range planning models. The reconciliation and sampling systems have also been refurbished with an emphasis on practical application and feedback loops.Accountability and transparency are provided by management reports that are generated from a centralised data warehouse and the introduction of a corrective action system. Standardised reports are available to all stakeholders and a quarterly KPI scorecard assists the management review process.The successful rejuvenation of the PQS has culminated in operational efficiency through the implementation of an integrated end-to-end process flow. Shareholder value is maximised through maximising recovery of the resource and minimising costs. Customer focus is maintained by reliably delivering product with acceptable and low grade variability.

Jul 11, 2011

This brief overview of the history of Brown Coal mining in Victoria is a luncheon presentation -I do not intend to make it indigestible with extensive listings of resources or production. There is a vast pantry of collated historical records and of vari- ous predictive studies available for the enquired with a hearty digestion. A gourmet collation is provided in The Aus IMM Monograph No 11 published in 1984 entitled "Victoria's Brown Coal-A HUGE FORTUNE IN CHANCERY", currently still on offer by the Institute and available at a bargain price in the foyer at this conference. Monograph No 11 also provides a feast of excellent references on the theme of Victorian Brown Coal assembled by the several contributors. In contrast, my presentation paper is a fast-food service, extracts from the printed paper only-you have no choice-you "get what you get" and in small quantity. I hope it will tantalise your appetite -like Oliver Twist you will ask for more. -Buy the Monograph!

Jan 1, 1989

From the viewpoint of mechanical efficiency, charges should be fully coupled and, upon detonation, should just fail to break the rock in compression. But because mining thrives on its cost-effectiveness rather than its mechan- ical efficiency, the explosive which generates maximum energy per $ should generally be used, even though the mechanical efficiency of this explosive's detonation products may be sub- optimum. Wherever possible, each charge should have a length:diameter ratio of about 20 or more and should shoot to a concavely biplanar free face that is both parallel and reasonably close to the blasthole. Success in obtaining parallel effective faces often demands the drilling of angled blastholes and, hence, will require intensified research and development efforts by drilling manufacturers, especially where hard strong rocks are encountered. Blastholes should be drilled on equilateral triangular grids and fired in a Vl or shallower V-type sequence using inter-row delays which ensure that good pro- gressive relief of burden is achieved. The conventional method of calculating Se/Be values (on the basis of planar effective faces) is often invalid.

Jan 1, 1986

By Chugh Y. P

A generalized void diffusion model for subsidence prediction has been developed based on theoretical concepts and physical principles. The general form of the model is a three-dimensional differential equation. With a few assumptions on the characteristics of overburden strata overlying typical room-and-pillar mining or longwall mining systems, specific solutions for the differential equation were obtained. A brief description of these solutions and their applications in the United States and China are presented in this paper.

Jan 1, 1992

By Marshall GA, Dickerson AW

The efficient operation of large haul trucks in large open pit mines requires an economic trade off between the haul route quality, the haul truck payloads and the level of haul truck reliability. This paper describes an investigation into the relation- ship between haul route surface quality and the level of structural reliability of a haul truck main frame. An instrumentation system for unattended recording of data on a haul truck operating normally in a mine and com- puter based analytical procedures were developed and used to identify which road segments contribute significantly to fatigue cracking at various sections of a haul truck main frame. INTRODUCTION In many open pit mines there is exten- sive use of large haul trucks to move over- burden and minerals. In most open pit hard rock mines, both the overburden and mineral ore are moved by large rear dump type haul trucks. Similar haul trucks are also widely used for coal overburden and mine site coal haulage operations in New South Wales, South Australia and Western Australia. Large bottom

Jan 1, 1982

Daily geological mapping of the Panguna porphyry copper/gold system since mining began in 1971 has provided a good basis for resource estimation and mine planning as the mine and estimation methods have advanced. Geology defined during evaluation and early mining has been substantiated and many smaller features have been better defined or identified. Breccias, pebble dykes, major structures and location of lithology contacts important to short term planning and long term pit slope stability have been defined. Correlation of copper and gold with breccia zones is quite striking and was not fully appre- ciated at the end of evaluation. Pit mapping geology, and diamond drill geology and assays, are now routinely added to a Geological Data base on computer, which forms the major geological data base for modelling the deposit. Geology from diamond drill logging, updated by pit mapping, and assays from diamond drilling updated by blast hole assays have been incorporated in a 45 bench deep 486 000 block computer based block model which forms the basis for long and short term planning. The introduction of pre-concentration scre- ening, based on the distribution of mineralisat- ion and fracturing, puts more emphasis on the definition of grade distribution at low concent- ration and on structures in the rock. Geostatistics is now used for resource estimation and has produced acceptable estim- ates. but these need to be refined, particularly in peripheral, low grade areas of the deposit.

Jan 1, 1987

By Reeves I. And Farquhar J, Pearce S

The irregular shape of the Rosebery orebody, coupled with the inconsistencies in grade over short strike lengths, has meant stoping blocks have had to be small to combat dilution and stability problems. In the past, each lens was divided into regular block sizes and developed up to five years before production commenced. There were two major drawbacks to this practice; firstly, existing development deteriorated over time therefore requiring rehabilitation prior to production. Secondly, the pre-determined blocks could not be easily changed to incorporate changes in mining technology or economic circumstances. Bearing these problems in mind, it was evident that any new lens development had to be designed to allow maximum flexibility. The lens being currently developed is J lens. It represents approximately 50 per cent of the current reserves tonnes, and 65 per cent of the zinc metal. Its importance to the mine's future cannot be over emphasised. At its core the lens is up to 25 m thick at grades of over 30 per cent zinc. The practice of dividing the orebody into levels and sublevels, with consequent crowns was no longer acceptable because of restrictions in stope design and potential loss of ore. To assist in the development planning of J lens, a geostatistical block model was applied in long section to graphically represent the lens. Areas of high zinc concentration, as well as zones of uneconomic material were identified by using the model. This has meant that the development could he targeted, enabling stope delineation to occur in the lens without significant ore loss. Because of limited development resources, and the need to bring J lens on-line in the near future, the development strategy has had to focus on 'just-in-time' principles, rather than accessing the whole lens from bottom, and progressing upwards. Tight development schedules have required individual stoping block to be developed on such factors as grade and available tonnes rather than as a vertical sequence.

Jan 1, 1993

By Seymour K. M, Sampson D. B, Walker I. W

Ashton Mining Limited is the operator of two wholly-owned gold mine/mill complexes at Laverton and Leonora. In addition, Ashton owns 43% of the Bardoc Joint Venture mine/mill complex, which is operated by Aberfoyle Pty Limited. All three of these operations are located in the Eastern Goldfields region of Western Australia (Figure 1). At Laverton, milling capacity is in the order of 1 million tonnes per year in 3 mills (Duketon 200,000 tpa, Cork Tree Well 650,000 tpa and Craiggiemore 150,000 tpa). These mills service a distance of 80 km, from Baneygo in the north to Craiggiemore in the south. Mineral tenements cover a 150 km long stretch of a series of sub-parallel mineralised structures. At Leonora, the Harbour Lights mill is designed to treat 750,000 tpa of sulphide ore, and has treated oxide ores at an annualised rate of over 1 million tonnes/year. The mill is supported by several tenement blocks that lie within a 50 km trucking radius of the mill. The most important of these is the Mertondale tenement block, which covers approximately 25km of the Mertondale Shear Zone.

Jan 1, 1991

Supercritical fluids are gases compressed to near liquid densities and, as such, have unique properties compared to liquids: low viscosity; zero latent heat; high diffusivity and pressure-dependent, solvation characteristics. These properties are being utilised in new processes and current research is delineating areas where such processes may be applicable to extractive metallurgy. The processes and areas of interest are as follows: Supercritical Fluid Extraction in which substrates are dissolved at high pressure and fractionated at successively lower pressures. Areas of interest include extraction of organic materials for regeneration of activated carbon for the CIP process and for upgrading alumina industry products and, separation of transition metal chlorides. ò Supercritical Water Oxidation in which high pressure gaseous water acts as a medium in which substrates are oxidised while suspended or dissolved. This process may be of use for oxidation of organics in Bayer liquor and oxidation of mine waters etc. ò Supercritical Fluid Reactions where reactions occur in a supercritical fluid medium, particularly when the medium itself is a reactant. This may be of use in treating refractory or carbon-aqueous auriferous ores and in lower-temperature chlorination of transition metal oxides. Research is described which is aimed at chlorination and separation of transition metal oxides by two supercritical operations.

Jan 1, 1991

The O.K. deposit occurs within a belt of cherts and spilitised basic volcanics near the western margin of the Hodgkinson Province. The tabular to lenticular shape and gross conformability of the ore bodies; the common occurrence of colloform, framboidal and banded textures in the ores; the lack of significant alteration adjacent to the massive ore horizons and the apparent restriction of stockwork mineralization to the foot-wall side of the massive ore zone at the O.K. mine, all favour a syngenetic origin for the massive sulfide bodies. Furthermore, the micro- structural evidence suggests that the ores have undergone the same deformational history as the country rocks. The invariable association of the ores with spilites; the S isotope values and Co-Ni contents of the pyrites, together with the primitive metal assemblage (Fe, Cu, minor Zn) strongly favour a basic magmatic source for the sulfides. It is suggested-that the sulfides were probably precipitated sub aqueous- ly during a hiatus in volcanic activity. The O.K. deposit is of the cupreous pyrite variety, but unlike other well known occurrences of this type, it does not con- stitute part of an ophiolite complex. While the host volcanics exhibit strong ocean floor tholeiitic affinities, no associated ultra

Jan 1, 1978

The Prospect to Pipehead Tunnel is a component of the Sydney Water Board's multi-million dollar Drinking Water Quality Program to improve the quality of Sydney's potable water supply to meet revised national health guidelines. The tunnel project involves the construction of seven kilometres of 3.9 metre diameter machine bored tunnel which is to be lined with a three-metre diameter steel liner. The paper describes the fully integrated planning and design approach and management technique used to enable this major project to proceed to meet the requirements of a tight construction program.

Jan 1, 1993