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The behavior of a curved wall under earth pressures for a horseshoe shaped tunnel lining is considered to be closely related to the beha vior of a vertical beam with variable flexural sti-"ness on an elastic foundation. In stress analysis an approximate method which divides the axis of the tunnel lining into small finite lengths and replaces the integrals by summation is usually adopted. this method is extremely complicated and tedious. However the variations of the moment of inertia from point to point along the wall axis can be expressed by a power function inversely .eith the distance from the ll )ottom and the analytical method can still used. The equations for the calculation of deflection, rotation, bending moment, shearing urce, and soil reaction of the curved wall are derived in nondimensional forms in this paper.

Jan 1, 1987

By McKee D. J

Much research is aimed at providing a revolutionary advance in technology that has the potential to render current mining and beneficiation problems obsolete. Such revolutionary advancements have been significant but few in number. Recent history shows that most improvement has been derived from a series of incremental improvements to the many processes that make up mining and beneficiation systems. Management approaches are changing to encourage this 'continuous improvement' and to support its implementation through the formal management of quality. This paper reviews some of the industry's priority R&D project areas and demonstrates that very significant opportunities are available to broaden the focus for improvement from individual processes to include the interaction between mining and mineral beneficiation systems.

Jan 1, 1994

The Kunwarara magnesite deposit is the largest known magnesite (MgCO3) deposit in Australia. It is located under black soil plains to the north of Rockhampton in Queensland. The deposit consists of magnesite nodules set in a fine-grained sandstone, siltstone and mudstone matrix. The magnesite is derived from weathering of serpentinite in adjacent hills and transport of magnesium in solution to a Tertiary/Quaternary river system. The magnesium has come out of solution in the active river system, and combined with atmospheric and biogenic CO2 to form magnesite nodules. The magnesite can be very pure with certain varieties up to 98 per cent MgO (LOI free). The deposit has been mined since 1991 and processed into magnesia (MgO) which is sold into refractory, agricultural and other markets. The geologist is an integral part of the small mine technical team. The role of the geologist includes characterisation of the ore through drilling and bulk sampling, supervision of geological aspects of mining and assistance in the optimisation of ore processing.

Jan 1, 2000

By E Jamieson

For a number of years, Alcoa World Alumina Australia (Alcoa) has been investigating opportunities to produce economically viable products from bauxite residues. Three of these potential products are described here, being Red Sand, ALKALOAM« and REDLIMETM.Red Sand has a nominal particle size of +100 micron and is physically little different to crushed bauxite from which it is derived. In AlcoaÆs Western Australian refineries, Red Sand constitutes up to half of the residue going to impoundment areas. Initial testing indicates that this sand could be processed to provide an acceptable general landfill material, a construction back fill or a material suitable for road base construction. ALKALOAM« is the fine-grained residue often referred to as red mud. A great deal of work has been done to show the benefits of adding this material to sandy soils, which are common in coastal regions of WA. ALKALOAM« has properties that can elevate the pH of the acidic soils and also retain phosphorous, reducing overall fertiliser use and protecting sensitive waterways. REDLIMETM is a by-product of the refining process. This material has a high acid neutralising value. REDLIMETM could be more effective at pH control than most available products because of the fine particle size and sodium carbonate that remains with the product.

Jan 1, 2004

By K B. Quast

During the prefeasibility stage of the mining cycle for a gold deposit, an evaluation of the ore leaching characteristics from various defined areas is essential prior to plant design. There are a number of simple laboratory tests which have proven successful in establishing gold and silver leaching kinetics, carbon adsorption and fouling, as well as elution characteristics. A number of case studies of carbon-in-pulp (CIP) simulation are presented which show excellent agreement between calculated and assayed gold and silver grades in feed and adsorbed on carbon which validate the methods used.

Jan 1, 1998

By J Cortinez, P Vallejos, J Yianatos, M Rodriguez

Nowadays, one of the main problems in current flotation plants and new projects is the significant decrease in feed grades and changes in the mineral composition, which has an important effect on the mineral liberation and associations. Additionally, flotation plants usually operate with feed throughput higher than the original design, which has a significant impact on the feed particle size. All these conditions affect metallurgical performance, and must be evaluated and addressed, by improving control strategies for banks optimisation. For this purpose, the flotation of valuable minerals along the circuits requires better understanding, considering the compromise between performance and selectivity in flotation circuits. This paper presents a characterisation of the different minerals recovered along industrial flotation circuits. Plant sampling campaigns, performed in a copper industrial concentrator in Chile, provided the data for the study. Two rougher flotation banks consisting of cells of 130 m3 and 300 m3 were analysed. All the samples from the industrial surveys were analysed by screening and mineralogy, and the mineral recovery along the circuits was evaluated per particle size class, liberation class, type of associations, and others. Additionally, operating data on froth depth profiles complemented the evaluation of the mineral composition of concentrate streams, along the circuit. The results allowed for identifying and quantifying the main factors that affect the copper recovery and concentrate grade along the flotation banks. It was found that minerals with liberation lower than 50 per cent have a significant impact on the recovery. On the other hand, the decrease in the Cu grade in concentrates along the flotation circuits is mainly due to the relative increase of middling minerals (less liberated), non-valuable floatable minerals, such as free pyrite, and gangue entrainment. The characterisation of the gangue entrainment flow rate along the flotation banks showed a strong relationship with froth depth, which becomes more critical towards the last cells of the banks.

Aug 24, 2022

By J A. Cowburn

The high intensity zone within the Jameson Cell is the downcomer. It is largely external and separated from the flotation tank. This, together with operation of the downcomer under vacuum, rather than at elevated pressure and the absence of moving parts, allows ready access to the high intensity zone for measurement and analysis. Experimentation was conducted allowing measurements of recovery for residence times of between 20 milliseconds and ten seconds within the downcomer of a Jameson Cell. The affect of aeration rate on the recovery of different particle sizes was also studied.

Jan 1, 2005

By C J. Moran

All mines face water management challenges. Adopting leading practice water management strategies can help reduce both operational and strategic risks. While many of the water issues faced by underground mines are the same as other operations, underground mining presents some unique water management challenges. In this paper we review trends in underground mining, water use and associated water issues. We then compile a structured set of strategic and operational risks that are pertinent to underground operations. The causes, threats, opportunities and measures for controlling or mitigating the risks are summarised. The risk compilation could provide an addendum for underground operations to the Australian governments leading practice water management handbook.

Mar 21, 2011

Coal washery wastes comprise tailings, finer than 0.5 to 0.1 mm depending on the sophistication of the washery, and coarse reject, typically finer than 50 mm. Subaerial disposal of coal tailings slurry at about 30 per cent solids by mass results in the formation of a delta with an average slope of about 1 in 100, representing one extreme. The ravelling of coarse reject on loose-dumping, results in an angle of repose slope with an angle of about 37o (1 in 1.3), representing the other extreme. The pumped co-disposal of coal tailings and coarse reject results in the formation of an upper delta with an average slope of about to one in ten, between the two extremes. The depositional behaviour of these three waste streams is discussed and compared in this paper. The important depositional and material parameters, and a theoretical description of the processes involved, are also presented. Comparisons are made between the depositional behaviour of the various coal washery waste streams, and natural depositional systems, such as rivers, alluvial fans, and scree slopes.

Jan 1, 1998

By Torrance AC

A joint research programme conducted by BHP Central Research Laboratories and Du Pont Wesfarmers Pty Ltd examined the effect of the size of cast primers on the run up and steady state detonation veloci- ties of ammonium nitrate based explosives as a function of blasthole diameter. Both continuous and point to point velocity of detonation meas- urement techniques were used. The field trials examined a number of the Du Pont HDP series of primers in conjunction with ANFO, emulsion and watergel explosives. Results indicate that the run up velocity of 187mm diameter ANFO charges is negligible using cast primers as small as 150g. owever, emulsion and watergel explosives did exhibit run up in both 187 and 311mm diameter blastholes, independent of the size of primer. This could last from 7 to 10 blasthole diameters.

Jan 1, 1988

By F Sahlström, E M. Jolis, V R Troll, E Jonsson, K Högdahl, C Harris

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Bastnäs-type magnetite-skarn-hosted rare earth element (REE) mineralisations are located in the Palaeoproterozoic Bergslagen ore province, central Sweden, and occur along a ca 100 km long belt of 1.90–1.87 Ga metavolcanosedimentary rocks. Ten different Bastnäs-type deposits have been sampled in order to assess the origin of ore-forming fluids in these systems. Magnetite and quartz have d18O values ranging from -2.3 to +1.1‰ and +7.2 to +8.3‰ respectively. Mineralised carbonates have d18O values between +5.8 and +7.2‰ and d13C values between -5.4 and -3.3‰. Temperature calculations based on the O-isotope composition of mineral pairs, combined with available fluid inclusion data, suggest primary mineralisation at ca 650–400°C. For these temperatures, calculated equilibrium fluids have d18O values that range from those typical of magmatic fluids (+6 to +8‰) to lower values (down to +3‰). Variation in carbonate O and C isotope data are consistent with interaction between local Palaeoproterozoic carbonate rocks (d18O = +12.5 to +19.6‰ and d13C = -1.8 to +1.7‰) and fluids of a magmatic origin. It is suggested that the Bastnäs-type REE-magnetite mineralisations formed as a result of reactions between local carbonate units and high-temperature, magmatic-dominated hydrothermal fluids during 1.90–1.87 Ga (Svecofennian) syn-volcanic activity.CITATION:Sahlström, F, Jonsson, E, Högdahl, K, Harris, C, Troll, V R and Jolis, E M, 2015. O and C isotope study of Bastnäs-type rare earth element mineralisation, Bergslagen, Sweden, in Proceedings PACRIM 2015 Congress, pp 439–444 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By B Clements, R Dunne, J Dioses, S Hart

In April 2003 plant upgrades in the æLow GradeÆ Cadia Hill circuit were undertaken in order to improve concentrate quality and metal recoveries from the flotation circuit. The major changes involved: circuit reconfiguration to allow all concentrates to be reground to less than 38 ¦m prior to final cleaning; increasing ball charge in the regrind mill to fully utilise all of the installed power; desliming of the cleaner scavenger concentrate to improve the circuit water balance; and the inclusion of a gravity concentrator in the regrind circuit to recover more free gold to bullion.Once the flotation circuit had stabilised under the new operating conditions concentrate launder modifications and increased froth crowding on the scavenger flotation cells permitted the introduction of stronger collectors without compromising concentrate quality or circuit stability.Twelve months on, the copper concentrate grade has increased by two per cent and metal recoveries increased by three per cent and seven per cent for copper and gold respectively. The project capital outlay of approximately $2.0 million has been repaid in less than three months. This paper will review the project from the design, construction and commissioning perspective as well as the subsequent debottlenecking exercise that was required to eventually yield the full benefits of this upgrade.

Jan 1, 2005

By D J Williams

Coal washery wastes comprise tailings, finer than 0.5 to 0.1 inn depending on the sophistication of the washery, and coarse reject, typically finer than 50 mm. Subaerial disposal of coal tailings slurry at about 30 per cent solids by mass results in the formation of a delta with an average slope of about 1 in 100, representing one extreme. The ravelling of coarse reject on loose-dumping, results in an angle of repose slope with an angle of about 37" (1 in 1.3), representing the other extreme. The pumped co-disposal of coal tailings and coarse reject results in the formation of an upper delta with an average slope of about to one in ten, between the two extremes. The depositional behaviour of these three waste streams is discussed and compared in this paper. The important depositional and material parameters, and a theoretical description of the processes involved, are also presented. Comparisons are made between the depositional behaviour of the various coal washery waste streams, and natural depositional systems, such as rivers, alluvial fans, and scree slopes.

Jan 1, 1998

By S Jahn, M Noel, E M. Rykaart, M Pau

Three soil cover test areas were constructed on waste rock backfilled into the Lichtenberg Pit, near Ronneburg Germany. A fourth, uncovered area was included as a control. Each test area measures 50 m by 65 m, and was constructed using full-scale equipment and construction practices. Extensive material sampling and testing was included as part of the construction. Devices were installed in each plot to monitor meteorology, infiltration, run-off, interflow, soil moisture, soil temperature, and soil pore gases. Boreholes were completed in each area and instrumented for temperature, pressure and pore gas sampling to a depth of approximately 60 m. Data from the monitoring instruments have been collected since July 2000, and have been comprehensively analysed and modelled on two occasions. The paper presents an overview of the test area design and instrumentation and the results of the two comprehensive data reviews. The reliability of the various monitoring methods is discussed and experience with several innovative methods is reviewed. The difficulties encountered in modelling the data set using common soil physical models are discussed.

Jan 1, 2003

By I M. Platten, Y Xie

Sampling protocols that are designed to suit the mineralisation style will result in a reduction of the nugget effect and hence resource risk. The a priori need for all sampling programs is the effective characterisation of the mineralisation type(s) to support optimisation. This requires a program of sampling for sampling followed by holistic characterisation. At each end of the coarse-gold to fine-gold spectrum, the samplability of a deposit ranges from relatively simple for fine-grained disseminated gold particles, through to extremely difficult for coarse nuggety mineralisation. Many deposits contain a proportion of both particle size types. The proportion and size of coarse gold particles has a direct impact on the effectiveness of sampling, where coarser particles will require larger samples and more specialised protocols. The nature of mineralisation geology/mineralogy and associated gold particle sizing can only be determined by sampling to facilitate optimised protocols. Mineralogical studies, focusing on particle size, particle clustering and distribution in host minerals, are required as part of wider paragenetic and metallurgical investigations. This paper discusses the role of mineralogical studies in the characterisation of gold ores for sampling optimisation through a series of case studies.

Jan 1, 2008

By D Adhikary, M Khanal, B Poulsen, H Guo

During longwall mining, the ability to reliably estimate the height of longwall mining-induced fractures is critically important in order to effectively manage mining-induced water inflows and aquifer interference. The extent of mining-induced subsurface deformation, fracture, surface subsidence and aquifer interference is largely controlled by local lithological conditions, mining methods and mine layouts. Therefore for the purpose of quantifying mining impacts it is imperative to incorporate the local geology and mine plan parameters in a mine scale model. Two different numerical models based on 3D continuum (Finite Element Method) and 2D discrete (Discrete element method) domains, respectively, are developed to incorporate the mine site parameters of a study site in Australia. Both the models are calibrated and validated with measured mine data. The continuum numerical modelling method is used to investigate the change in permeability of the overburden strata due to underground extraction considering the full 3D nature of geology and mine layout. The discrete element modelling method is used to simulate the initiation and propagation of fractures, allowing the caving of overburden strata to be represented in a realistic manner, and the permeability enhancement of the strata overlying the goaf to be calculated from first principles. Permeability enhancement in the discrete element model is a direct function of the fractures induced in the deformation/caving process; fracture location, extent, aperture and connectedness. From the numerical modelling under the simulated condition for the mine studied here, it is predicted that the permeability of the caving zone from the goaf to five times the mining height increases by almost six orders of magnitude. In the fracture zone to approximately ten times the mining height, the change in permeability is predicted to be around two to three orders of magnitude. At the height of more than ten times the mining height the magnitude of permeability increased is predicted to be one to two orders of magnitude. CITATION:Khanal, M, Poulsen, B, Adhikary, D and Guo, H, 2018. Modelling of height of connective fractures during longwall mining, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 254–265 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By Y Peng, D Wannas

In the fine particle flotation technologies being developed today the fine hydrophilic (gangue) particles are usually well dispersed. These highly dispersed fine particles can be recovered into the flotation froth product by mechanical entrainment. Flocculation of hydrophilic particles caused by polymer depressants could potentially reduce the mechanical entrainment of these particles. This paper reports testwork completed on fine particles of several solids, iron oxide, hydroxylapatite, galena and sphalerite, as well as on a relatively coarse quartz sample (-75+38 ¦m). Dodecylamine was used as a collector for the quartz, and several dispersants and polymer depressants, including sodium silicate, sodium metaphosphate, zinc sulfate, potassium dichromate, corn starch, corn dextrin and carboxymethyl celluloses (with molecular weights of both 700 000 and 80 000) were used as flotation modifiers. The major part of the testwork involved flotation tests in a 200 ml flotation column. Both water and solid recoveries were recorded. The degree of flocculation and dispersion was determined by settling tests in 250 ml graduated cylinders. It was observed that flocculation of the fine hydrophilic particles significantly reduced their mechanical entrainment, while dispersion severely aggravated it. Thus, in the flotation separation of artificial mixtures of the -75+38 ¦m quartz and fine iron oxide or hydroxylapatite, polymer depressants that caused flocculation were found to perform better than the ones that did not cause flocculation.

Jan 1, 2005

By Moorrees C

Tests show how that temperature and rate of sparging to remove carbon dioxide determine the rate of precipitation and the chemical and physical properties of hydrated magnesium carbonates precipitated from clarified magnesium bicarbonate liquors derived from crude magnesia. At temperatures above 55°C the product is largely in the form ofhydromagnesite, Mg5(C03)4(OH)2.4H2O Between I5°C and 55°C the major product is nesquehonite, MgCO3·3H2O, although partial hydromagnesite precipitation can be induced by a high rate of aeration.As a result of the reduced time required to bring about greater than 95 per cent magnesium precipitation, the higher MgO content of the product, the ease of product recovery from the precipitation vessel, and the lower energy requirement for thermal decomposition of the precipitate to magnesia, it is preferable to precipitate hydromagnesite rather than nesquehonite. Moreover, the magnesia produced from hydromagnesite is somewhat more reactive than that formed from nesquehonite.Using precipitate calcination temperatures less than 1000°C, the chemical reactivities of the magnesias formed from both precipitates are greater than those of the crude magnesias derived from Savage River magnesite itself. The magnesias would be suitable for most uses developed for caustic-calcined magnesia. However, for refractory brick manufacture, it would be necessary to briquelle the caustic-calcined magnesia. adjust the CaO and SiO2 contents and sinter at temperatures in excess of 1600°C. This would bring about an increase in the bulk density and induce the appropriate chemical bonding reactions.Dead-burned magnesia produced from Savage River magnesite by the calcination/carbon dioxide route would have very low B2O3 contents, typically less than 0.0001 per cent.

Jan 1, 1985

By P Cameron

The Julius Kruttschnitt Mineral Research Centre (JKMRC) has recently commercialised a variety of new products for the mining industry through its commercial division (JKTech). Although the products cover a wide variety of niche applications, a common thread runs through the Research, Development and Commercialisation (RD and C) process: they have emerged from industry sponsored projects. The development history of JigScan (a control system for the mineral-processing jig) is a good example of how this RD and C process works in practice. It involves building mutually beneficial partnerships between the JKMRC and the mining industry through several incremental projects with one or more industry sponsors. All research projects have objectives to demonstrate but these projects also feature a degree of product development to actively encourage and support the longer-term vision for the mature commercial technology. The process to develop JigScan as a commercial product worked because each incremental project recovered costs, provided an immediate benefit for the sponsor and contributed to the longer-term development objectives of the JKMRC. Integrating development with research need not greatly increase the cost of research objectives generally provides a more robust research outcome for the sponsor and greatly reduces the overall development risk. Successful projects often feature industry mentors actively participating in the RD and C process. Additional funding from government appears to be easier to obtain when such close partnerships with industry are apparent. Finally, the business structure of the JKMRC within the University of Queensland ensures that commercial outcomes, developed within the contractual arrangements of the underlying RD and C projects, are used to benefit and support further RD and C with the mining industry. This paper tells the story of the development and commercialisation of JigScan, and draws conclusions about this kind of RD and C model.

Jan 1, 2000

By B Upton, J Mitchell

The use of hydro scaling and in-cycle shotcrete to replace conventional jumbo scaling, mesh and bolting as the primary method of ground control for run of mine development has been investigated through extensive trials at the Waroonga mine, Agnew Gold Mining Company.These trials have progressed from investigating the productivity aspects of the method through to a three month mine-wide trial, which may yet lead to the adoption of this potentially best practice ground control technique at Agnew.Ov erseas trials and research have shown that hydro scaling results in a significant improvement in the shotcrete-rock bond strength. Good adhesive bond strength ensures that the shear strength of the shotcrete layer rather than itÆs flexural or tensile strength is fully mobilised as rock mass reinforcement.This maximises shotcretes ground reinforcement capability and it is suggested that a bolt-less fibrecrete support design is feasible using the hydro scaling technique.

Jan 1, 2005