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By R M. Yanamandra, S K. Tripathy, N Mangadoddy, P Sudikondala, P Ankireddy

Spiral concentrator is one of the most commonly used gravity concentration devices in mineral processing. The particles are classified based on their specific gravity and size. The present work analyses the experimental and numerical investigations of the water flow field, such as fluid depth and free surface primary velocity of two high gravity spiral concentrators at different flow rates. The measurement techniques use a flow depth gauge and flow visualisation technique adapting lycopodium powder as the tracer. Flow features in terms of liquid depth and primary velocity at the free surface of the flow are captured across the trough in two different high gravity spirals. A highspeed motion camera with an imaging frequency of 5400 frames per second and 768 × 768 pixel resolution is utilised to track the tracer particles in the liquid flow on the dark surface background. Further, the two-phase flow is studied numerically on high gravity spirals based on the volume of fluid (VOF) approach utilising the RNG k-ε model and Reynolds Stress Model (RSM) for predicting the fluid flow on trough surfaces such as water depth and free surface primary velocity. The CFD predictions of the flow field for the two spirals are attempted to validate against experimental data. The high gravity spiral concentrators show lower flow depths and free surface primary velocities but steep velocities on the outer trough zone compared to that of low gravity spiral concentrators (conventional coal spirals). Among the computationally tested high gravity spirals, higher pitch and higher secondary slope design shows greater flow characteristics.

Aug 24, 2022

By X Y. Ma, X G. Tian, P F. Zhang, T B. Zhao, Z H. Li, Z Y. Fu

This study analysed the fracture characteristics and movement process of goaf roofs under the condition of gangue backfilled mining, based on the engineering conditions of Tangshan Mine F5001 gangue backfilled working face. The inclined borehole detection method is adopted to conduct long-term and fixed-point detection of the roof stability. The distribution characteristics of mining-induced cracks in the roof are described quantitatively based on the crack density, and a similar model test method is used to assist the analysis of the roof movement under the control of gangue backfilled mining using stress sensors and digital speckle deformation field monitoring. The results show that under the condition of gangue backfilled mining, structural cracks in the roof typically appear at the boundary of rock strata. The appearance of cracks is related to the rock strata where they are located. Structural cracks appear in the form of single cracks ahead of the working face and develop into structural cracks in the goaf. The roof movement of the coal seam develops in five stages: fracture incubation, crack extension in advance, dense fracture development, steady fracture expansion, and roof stability. Separation forms the primary component of the roof subsidence, accounting for more than half of the subsidence value. The separation generally extends over a long distance along the strike, and vertical crack-intensive areas appear in the roof above the cut-off and stop line. The findings of this study provide a theoretical basis to support designs of backfilled mining and upgrading of hydraulic supports in working faces.

Nov 29, 2022

Iron Concentrate Synthesised from Waste Ferrous Sulfate Produced in Titanium White Preparation

Sep 13, 2010

By S Jahanshahi, D R. Swinbourne

The classical metal-slag-gas equilibrium technique was used to study the thermodynamic activity of cobalt, iron and their oxides in iron silicate based slags containing under controlled oxygen potential (3.70 x 10-8 to 2.95 x 10-7 atm) at 1573 K. The measured activity of cobalt oxide in FeOx-25 wt per cent SiO2 slags showed positive deviation from ideal behaviour for melts with up to ten wt per cent CoO. At higher silica contents, the behaviour became closer to ideal and in accord with previous studies on silica saturated slags. The activity coefficient of FeO in these slags had virtually no dependence on the CoO content. Partial substitution of silica by lime resulted in an increase of the activities and activity coefficients of CoO, FeO, Fe2O3 and Fe3O4. The results indicate that saturation of the slag with a magnetite phase occurs at CaO contents of five wt per cent and higher. Phase equilibria studies SiO2-FeO-Fe2O3-CaO slags containing cobalt were also carried out using the drop-quench technique. Results from these experiments confirmed the formation of a magnetite solid solution containing about three wt per cent CoO at lime contents of five wt per cent and higher at 1573 K and 2.9 x 10-7 atm of oxygen.

Jan 1, 2000

Recovery of Vanadium from Stone Coal Through an Environmentally Friendly Acid Leaching Technology

Sep 13, 2010

By R M. Stephenson

Large diameter raise boring is a common raise excavation method in the Australian mining industry. Geotechnical investigations were conducted on several large diameter raise bore projects at Gwalia Mine to assess the potential for instability and potential back-reaming problems. A thorough geotechnical analysis and subsequent back-analysis was conducted on a vent raise excavated at 5.5 m diameter and 810 m length.The geotechnical investigation for the vent raise included collection of data from an acoustic televiewer survey that was conducted on the pilot hole. The survey results provided structural data and an insight into the effects of stress on the pilot hole. Structural analysis was conducted using a combination of information obtained from the acoustic televiewer survey and geotechnical logs of the diamond drill core drilled close to the site.Further information was collected from drillers’ plods from pilot hole drilling and back-reaming to conduct a back-analysis of the completed shaft, and this was compared with the structural analysis.The key finding from this review was that the acoustic televiewer survey of the pilot hole accurately identified locations with blocky conditions. This is an important supplement to the information available from the main geotechnical investigation hole, as this was offset from the shaft location over most of its path.CITATION:Stephenson, R M and Sandy, M P, 2014. Structural analysis of acoustic televiewer logs for large diameter raise bored shafts, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 89–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

Principles of management in ore preparation before process of enrichment of chrysotile ores are discussed. The formulas, which were tested in industrial conditions, are offered, which may be used for averaging of chrysotile-asbestos fibres by content in ore and grade.

Dec 6, 2010

Bubble Load Measurements in Flotation - A Critical Review of Current Practice

Sep 13, 2010

Underground excavations are subjected to complex stress changes caused by nearby mining, but may also be affected by repeated dynamic loading from blasting and seismic events. In some cases, the combined, cumulative effects can lead to unforeseen damage, displacement and instability. Simulating dynamic loading of an underground excavation is a very complex task. The state of rock mass stress, damage and deformation must first be simulated sufficiently requiring small-scale structures to be explicitly modelled. Supporting elements must be represented with high similitude and then the dynamic event must be applied to the system in the case of blasts, or evolve as a consequence of rock mass instability for seismic events. A special case is for the effect of pit blasting on underground excavations - discontinuous rock phenomena at scales from mine, to bench, to pillar, to tunnel need to be captured and this represents one of the most computationally intensive tasks in mine simulation. Recent advances in computer power allow these tasks to be completed at a mine scale, incorporating discontinuities and geological detail matching the best practice for static Finite Element analyses. The results are a worthwhile contribution to mine decision-making, but require careful interpretation and thoughtful inputs - even more so than quasi-static analysis - as the cumulative effects of unfavourable modeling practices are greater. Some learnings from experiences with mine scale, discontinuum dynamic simulation are summarised, including a discussion of considerations of scale and similitude for this type of analysis.

Nov 25, 2010

The gold salting fraud at Busang on the island of Kalimantan, Indonesia was exposed in early 1997 and resulted from the independent drilling, sampling and assaying of PT Freeport Indonesia which reported assays from the South East Zone with negligible concentrations of gold. Since then, a number of legal actions directed at former Bre-X directors, consulting firms and financial or broking institutions are at various stages and are based on numerous allegations surrounding the supposed existence of obvious and numerous warning signs or æred flagsÆ. These include: the absence of references to visible gold in the drill logs; the alluvial nature of the gold grains; the high gravity recoveries; the invalid comparison with Kelian; the absence of outside scrutiny and the lack of external review/audit and surface depletion of gold. The focus on the red flags has been at the expense of the numerous positive indications or ægreen flagsÆ. These include the morphology and chemistry of the gold grains, the gravity testwork, the amalgamation results, the role of external consultants, the results of a review by one of North AmericaÆs leading minerals auditing groups, the behaviour of the gold at surface and the presence of references to visible gold in the drill logs. The flawed nature of the discussion of the technical facts surrounding Busang has prevented a meaningful and informed discussion about what actually happened and has, therefore, prevented the formulation of meaningful remedies for the future.

Jan 1, 2002

Triboelectrostatic Producing Ultra-Clean Coal

Sep 13, 2010

By V S. Vutukuri, K Shariar

This paper present a modification of selected strength criteria for coal and rocks containing weakness planes. The three strength criteria, namely, Murrell (1965), Bieniawski (1974a, 1983) and Hoek and Brown (1980) have been assessed for coal (containing weakness planes) by using triaxial strength tests. Triaxial test results indicated that the strength of coal specimens depends on the weakness plane inclination with respect to the principal stress direction. However it is shown that with increasing confining pressure, the effect of weakness planes inclination on the strength of coal specimens is reduced. The constant parameters in the three failure criteria for coal are determined for each weakness plane inclination by using the Datafit computer program (nonlinear regression analysis) and the results are compared with other rock types.

Jan 1, 1999

The 115-year history of the Hall-Heroult process for production of aluminium has been characterised by a sustained technology-driven improvement in costs and productivity. In the past decade the industry has effectively transferred best practice into older technology with improvements through computer control of the process, and redesign of cell linings using computer modelling . Incremental development is now at the point where diminishing returns will apply for further technical improvement effort however, until the gap between technical limits and current best practice is addressed through major process redesign. The process remains a long way short of its technical limits in energy consumption, carbon anode consumption, cell life and product purity. Investment cost in new capacity is very high, supporting the retention of older and less efficient technology and hence limiting the application of best practice in environmental performance and occupational health exposure. The industry is a major emitter of greenhouse gases yet the process has the potential to release oxygen as the primary waste. All of the above issues will be addressed in the new century, but only through commitment to the necessary long-term research and development that is required to achieve a redesign of the process.

Jan 1, 2000

By J Carswell, K McTyer

The Pajingo gold operation in Queensland is approximately 50 kilometres south of Charters Towers and 134km south-west of Townsville. The resource was discovered in 1983 and first open pit gold production began in 1986. The mine traditionally employed a bottom-up sequence – a combination of modified and traditional Avoca methods with run-of-mine waste backfill. This practice caused many high-grade crown pillars to be left in place, yet accessible. In recent years, these crown pillars have been extracted by injection grouting of rockfill. This process facilitated blind up-hole open stoping. To date, thirteen separate injection campaigns have been completed, of which ten were deemed successful. In general, the two key technical difficulties in this mining technique are: maintaining a consistent high-quality ground consolidation of the rock fill material; and controlling the drill and blast practices during stoping. Here, effective drill-and-blast control was found to be essential to achieve the dual aims of 100% extraction, and maximum sill pillar stability to minimise dilution. During stoping, the technical performance of the consolidated rock-fill was recorded; both to verify the design, and to identify operational improvements. The results showed that Pajingo has realised both reduced production down-time through use of early strength gain grout, and more rapid and thorough grout consolidation through changes to the emplacement method. The optimisation of consolidated rock fill has led to several quantifiable benefits to the mine, including: profitable extraction of previously sterilised crown pillars resulting in both increased ore reserves and production profile; improvements to the stability of grouted stope crowns, thereby reducing safety and production related; risks associated with open up-hole stopes; reduction in cost and time constraints, with respect to the grouting of loose fill; and reduction in grout curing time – from 14 days to 8 days – thereby minimising production down-time. This paper is a case study of the evolution and optimisation of the up-hole open stoping mining method at Pajingo. The challenges and successes are discussed in terms of their key mining outcomes. CITATION:McTyer, K and Carswell, J, 2018. Evolution of rock fill consolidation at Pajingo Gold Mine, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 66–77 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By E Holloway

The optimisation of an open pit mine can be broadly split into two stages, the first being the ultimate pit optimisation (and subsequent stage designs), and the second being schedule optimisation. Macroeconomic uncertainty clearly impacts on both however interrelationships do also exist. Generally, the opportunity exists for the ultimate pit to be revised during each planning cycle, however when this reprieve is removed the uncertainty for the underlying business increases. As one example, the introduction of an in-pit waste dump can be seen to significantly limit the option to revise the ultimate pit. When in this situation there are two potential risks that present: (i) the long-term price used for the ultimate pit selection is optimistic, and too large of a pit is selected resulting in waste being mined which uncovers material not of a significant value to deliver a profit; (ii) the long-term price used for the ultimate pit selection is pessimistic, too small of an ultimate pit is selected, and ore of realisable economic value left behind. Both of these outcomes are risks and as such can be assessed and quantified. CITATION: Holloway, E, 2018. Incorporating economic variability into a strategic planning framework, in Proceedings Complex Orebodies Conference 2018, pp 88–90 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

Combined Flow Sheet for Treatment and Recycling of Municipal Solid Waste (MSW) with Complex Morphological Composition

Sep 13, 2010

By Nixon J. C, Reynolds C

Three principal features of the ore at Captain's Flat, New South Wales, tend to complicate concentration of the valuable minerals, these being:1. The ore occurs in three more or less separate bodies which vary in texture and mineral ratios. Mining of constant proportions of the three sections, or adequate blending of the ore, is not fully effective, and consequently the flotation section is subjected to feedof varying texture.2. The mineral association in the heavily pyritic ore is extremely intimate. Composite particles exist even at 20 micron sizeI, and probably finer.3. The copper content of the ore averages_about 0,6%, which is high enough to justify recovery of the chalcopyrite in a separate concentrate. A review of the metallurgical history of the mine shows that this feature has been the cause of the several major changes in flowsheet of the flotation section since the commencement of milling.METALLURGICAL HISTORYThe mine started production in January 1939, at the rate of 250 tons per day of sulphide ore, assaying 0·68% Cu, 6·52% Pb, 10·8% Zn, and about 1 dwt. Au and 2 oz. Ag per ton.

Jan 1, 1952

Study on Beneficiation Technology of a Refractory Fluorite Ore in North China

Sep 13, 2010

The Dynamics and Thermodynamics of Absorbing Lithium of Ion Sieve Preparing Pollymetallic Nodules

Sep 13, 2010

With the continued implementation of stricter limitations on the discharge of excess process water from all existing and future mining and metallurgical operations, the design and operation of the entire process water circuit must form an integral part of any total operational package. It is far better to æanticipate and circumvent the problemÆ rather than be forced into an expensive remediation program after the event. By far the greatest problem relates to the treatment and disposal of what is generically known as acid drainage. In simple terms, an acidic metal sulfate solution is generated by a series of chemical and biological reactions as soon as most sulfide minerals are exposed to air and water. Treatment of this solution by one or more of a wide range of chemical and physical options can involve substantial capital and operating costs, although there are recent processing options that yield saleable by-products, thereby reducing the financial liability of what is effectively a waste stream. This presentation provides an overview of the Australian situation compared with the rest of the world and outlines the basic features of a number of the more advanced passive and active acid drainage options.

Jan 1, 2004