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By Y Li, B Shen, S Zhang

Jointed rock mass is often encountered in rock engineering and its stability has always been a major concern in underground engineering. To analyze the stress characteristics and their variations in jointed rocks, in this study, a new concept of sub-instability stage before rock failure is defined, and a new experimental method is used to investigate interaction between defects and intact rock of the jointed rock mass during the subinstability stage., Firstly, external characteristics of stress and failure mode of the whole jointed rock are investigated systematically by conducting uniaxial compression tests on red sandstone samples with a set of preexisting open flaws of different sizes, and the interactive damage of intact parts and defects in the subinstability stage was further studied. Secondly, rock-like material samples made of bonded plaster blocks were tested and internal data from stress sensor between the strong and weak segments were collected. The transforming processes from independent activity of the individual segment to overall interactive movement of jointed rock before the unstable failure were analysed. The test results indicated that the subinstability stage marked the beginning of interactive failure between the intact rock and defects. In the early subinstability stage, the relatively intact parts bore most of the load in a jointed rock mass, and the defects were damaged firstly which caused high strain around it. The areas of high strain increase rapidly, extending and migrating, causing damage to the intact parts. In the later sub-instability stage, the interaction effect reached its maximum, and a large number of cracks appeared in the intact rock and they propagated and coalesced. Intact parts experienced rapid failure and then the jointed rock failed. The experimental method used in this paper to identify the sub-instability stage could be used to identify failure precursors of jointed rock masses and to develop technology for disaster prevention in rock engineering. CITATION:Zhang, S, Shen, B and Li, Y, 2018. Experimental studies on interactive failure characteristics of jointed rock, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 453–461 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By S Jeon, K Aikawa, M Ito, A Kusano, I Park, N Hiroyoshi

In mineral processing of complex sulfide ores containing copper (Cu), lead (Pb), and zinc (Zn), flotation has been commonly used. Typical Pb mineral in the ores is galena (PbS), while some types of the ores contain anglesite (PbSO4). This article reviews our recent studies on the effects of coexisting PbSO4 on the flotation of complex sulfide ores, and a method to suppress the floatability of sphalerite (ZnS) in the presence of PbSO4 was proposed. Comparison of flotation experiments for different types of model samples showed that PbSO4 makes the separation of Zn from Cu difficult; that is, for the model sample containing PbS without PbSO4, Zn could be separated from Cu, while when the model sample containing PbSO4, Zn was recovered together with Cu as froth. Solution analysis and thermodynamic calculation suggested that Pb2+ was released from PbSO4 and reacted with ZnS to form PbS, acting as an adsorption site for the flotation collector, xanthate. This would be the main reason for high floatability of ZnS in the presence of PbSO4. As a method to suppress ZnS floatability for the ores containing PbSO4, a pre-treatment of the ores to remove PbSO4 prior to flotation was proposed. The results of model experiments using mixture of ZnS and PbSO4 showed that ~97 per cent of PbSO4 was dissolved within 30 minutes of pretreatment using ethylenediaminetetraacetic acid (EDTA) as extractant, and thus ZnS floatability was markedly suppressed. Moreover, Pb2+ extracted from PbSO4 during the pre-treatment could be recovered as zero-valent Pb by the cementation using zero-valent Fe as a reductant. The details of ZnS flotation in the presence of PbSO4 and the effects of the pre-treatment are discussed based on the results of surface analysis like XPS.

Aug 24, 2022

By D Craw, C Smith, C Martin

The Wangaloa coal mine closed in 1989, and an attempt to grow Pinus radiata on quartz-rich overburden dumps was not successful. The site is currently being rehabilitated with re-profiling and native plant establishment. Plants are being established in a range of substrates that consist of variably disaggregated Tertiary coal measure sediments derived from the mine sequence. This material has low organic matter content (typically <10 %), originating from coal fines or carbonaceous sediment. Substrate samples were collected during December 2003 from a range of sites varying in age, slope, and parent material. Nutrient analysis includes nitrate, ammonia, total N, total P, available P and readily exchangeable base cations. Total nitrogen and phosphorus are low on areas of recently disturbed, quartz-rich overburden, with total N =1200 mg/kg, and total P =200 mg/kg. Background forested areas have total N ranging between 2800 - 3300 mg/kg and total P of 420 - 500 mg/kg. Quartz-rich overburden sites contain available nitrogen levels of less than 6 mg/kg, while background forested areas are generally >20 mg/kg. The soils and water runoff are generally acid, with pH down to three. Water samples have been collected from both ground and surface resources on a monthly basis since December 2003. The main lake on the site had pH of 4.6 in 1999, and this remained relatively unchanged when 850 tonnes of lime were added in 2002. However, the lake pH changed to 6.4 within a one month period in 2004, and has fluctuated since that time.

Jan 1, 2004

Since the earliest recorded prospecting of the 1860's mineral exploration and mining in Fiordland has been discouraged by the formidable physical difficulties presented by its isolation, extremely rugged relief, treacherous coastal waters and generally unfavourable weather conditions. Government assistance was often sought by the miners and prospectors but little, if any, support or encouragement was received after the initial period. During the 1840's decorative marble was quarried at Caswell and Dusky Sounds. A prospector discovered and attempted to mine copper sulphides to the north of Dusky Sound (Parks Mineral Beds) and near Mt Solitary. A small Pb, Zn, Cu, Ag, Au bearing quartz reef was discovered and driven on in the granite coast line of Preservation Inlet (Bradshaws Reef) and the ore roasted on site. Alluvial and quartz lode gold was discovered at Preservation Inlet in the 1890's and led to the recorded recovery of 11 000 oz of mainly lode gold. Falloff in grades with depth, thinning and splitting of the reefs and the high mining costs at this location led to a virtual abandonment of the field by 1906. In the late 1950's and early 1960's the geology of Fiordland was mapped by the Geological Survey at 1:250 000 scale, but field work was largely confined to the shore lines of the coast and fiords. In view of the physical difficulties it is not surprising that mineral exploration and mining up to 1970 was limited to the scant attention outlined above.

Jan 1, 1977

By A Datar, D Mulligan

The extractive phase of broad-scale mining can have major impacts on landscapes and associated ecosystems. Post-mining ecological rehabilitation typically starts with reconstructing topography. A fairly common industry practice has been to use landform elements such as plateaus, terraces, and gentle slopes for stabilisation purposes. However, this approach can lead to the generation of fairly uniform landforms that do not necessarily reflect natural ecosystems. Previous research in undisturbed and agricultural landscapes shows that ecological attributes and diversity in microclimates is positively correlated with landform heterogeneity. An objective of this study was to investigate if those findings are still valid in post-mining rehabilitating landscapes on North Stradbroke Island, Queensland, Australia. We investigated the relationship between landform heterogeneity and status of ecological recovery. The landform heterogeneity is measured through variance in three landform characteristics (relief, slope, aspect) using remote-sensing data and the status of ecological recovery is represented by ecological indicators measured through field surveys. The results indicate strong correlations between landform heterogeneity indices and native vegetation species richness with sensitivity to the spatial scale of investigation. It is recognised that climate, substrate and rehabilitation practices act as primary drivers of rehabilitation success. However, the results indicate that, in some examples, landform heterogeneity (heterogeneity in relief and slope angles) contributes up to 30 to 50?per?cent of the variance in native vegetation species richness. While the primary drivers of ecological recovery are difficult to control over extensive areas and extended time periods, landform heterogeneity provides a tool to indirectly control the micro-environmental parameters to improve ecological recovery. Reducing the uncertainties in the choice of ecological and landform indices and the degree of landform heterogeneity suitable for particular rehabilitating landscapes would be site specific. The introduction of desired landform heterogeneity may provide a very effective tool for significant improvement in ecological rehabilitation across broad-scale post-mine landscapes, an outcome of benefit to industry, government and local communities.CITATION:Datar, A and Mulligan,?D,?2014. Do we need to change the way we set up the stage?, in Proceedings Life-of-Mine 2014 , pp 29–46 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By West RF, Pooley RH

An underground mine, a treatment plant and supporting facilities have been constructed at Lebong Tandai in Sumatra, Indonesia by PT Lusang Mining. Throughput is initially 50,000 tonnes per annum of ore with an inbuilt capability to expand to 100,000 tonnes per annum. Construction proceeded in parallel with design work on a tightly controlled critical path schedule. The very remote location of the mine, the difficult access and the fact that equipment was imported from many parts of the world presented a challenging project management problem. The transport system, which involves road, river and rail and support facilities on site had to be brought into full operation prior to the arrival of major equipment. Mine development involved the reopening of the old access drives and workings, refurbishing two shafts and the haulage system together with redevelopment of old stoping areas and the opening of new stoping areas. Ore production is now from three main areas using shrink and underhand stoping methods. Ore breaking and drive development is with conventional airleg mounted rockdrills and ANFO explosives. Exploration to locate and develop new reserves to replace ore mined is an ongoing activity.

Jan 1, 1986

Sampling and analysis of mineral deposits need to be executed without fear or favour of financial or personal impacts. Examples are given to illustrate the effects of departures, witting and unwitting, from correct use of appropriate techniques and/or equipment with emphasis on exploration and mining of porphyry copper deposits of the Pacific Rim. Some of the results of errors on the low and high sides of true value in exploration, resource or reserve estimations and in production caused by sampling and/or sample preparation mistakes, faulty practices, equipment and/or analysis are considered.

Jan 1, 2004

As near surface deposits are increasingly mined out and pit widths beginto exceed the reach of practical direct-casting stripping machines, high haulage costs can make truck-shovel pre-stripping operations uneconomic. This is compounded because the rate of inflation for diesel fuel oil, lubricants, tyres, etc. exceeds the general rate of inflation. The use of conveyor transport systems, long established in terracemining operations in weak materials, e.g. engineering soils, can provide a viable haulage alternative in pre-strip operations and in some open pit settings. The paper describes the engineering requirements and basic economics of such systems.

Jan 1, 1985

By Dionne S, Goodwin F. E

Zinc-aluminium alloy cast matrix composites have been made by squeeze casting, pressure infiltration, spraying forming and stir casting. The overview describes composites made . with these processes. Improvements in properties compared to the conventional alloys are most significant at elevated temperatures. Since stir casting is the most economical viable route of producing composites, progress made in this area is particularly emphasised.

Jan 1, 1993

By H E. S Moorcroft, D Scott

The increasing mining depths of South African gold mine deposits are resulting in ever-increasing heat loads associated with depth and the geothermal gradient. Together with changes in the mining horizons brought about by the depletion of older, shallower, high-grade reserves, this leads to the need for the continuous review and redesign of cooling requirements. Traditionally, cooling requirements were met by using a combination of cooling strategies, including bulk air cooling on surface and underground. If this proved to be insufficient, chilled service water and secondary remote air-cooling systems were introduced. This paper reviews these practices in order to provide a cost-effective means of catering for the introduction of hydropower at the Gold Fields Ltd South African operations. Some of the equipment that has been developed to meet the requirements of both hydropower and refrigeration includes hydropower fans, cooling coils and in-stope venturis. These are individually described and discussed, together with their roles within the greater strategy. The planned change in the cooling strategy and the employment of these technologies have effectively doubled the cooling available, from 10 MW to more than 20 MW, extracted from the hydropower water used to drive the mining equipment. In conclusion, the cooling strategy described allows a total heat load of approximately 52 MW to be successfully ventilated and cooled through the use of combined surface and underground refrigeration installations, and through the use of hydropower-chilled water.

Jan 1, 2005

The underground storage of LPG and other hydrocarbons is in current commercial use in Northern Hemisphere countries in Europe, Asia and the USA.Elgas Pty Ltd, a 50 per cent joint venture between AGL and BOC, embarked on a worldwide feasibility investigation in 1989 to establish the viability of constructing an underground LPG storage facility in Sydney, Australia, the first of its kind in the country. Elgas recognised that with the limited 19 000 tonnes of storage capacity at Port Botany and the limitations imposed by use of small coastal ships (up to 10 000 tonnes capacity), a larger storage facility was required to utilise higher capacity ships from more remote sources such as the North West shelf and overseas. This would achieve security of supply in high demand periods and economies of scale. The underground option also provides improvements to safety and environmental standards.

Jan 1, 1999

By Cloutier JY, Quinn P, LeClerc A, Dube G, Agar GE

Gold dissolution by cyanide requires the presence of oxygen which is usually supplied by sparging compressed air into the gold containing slurry. For those ores that contain certain obnoxious substances that consume oxygen, maintaining the required minimum level of dissolved oxygen can be troublesome. One of the most economical solutions to the problem of low dissolved oxygen, especially in plants that have air compressors installed, is to enhance the rate of oxygen mass transfer. The oxygen mass transfer rate was measured in a two phase system using two different sparger arrangements, and with addition of a frother that is known to reduce the bubble size produced by the sparger. The common sparger system was shown to be inefficient compared with a readily available but under utilised method of gas dispersion which introduces air directly below the reactor turbine. Transfer of this technology to an operating plant confirmed the beneficial effect of the improved sparger system. The addition of the frother did decrease the bubble size, but it also reduced the oxygen mass transfer rate.

Jan 1, 1993

By Xizhen J

Point load testing for irregular rock specimens was studied to determine the relationship between tensile and compressive strengths, drill penetration rate and other rotary drilling parameters. The DH-l type point load tester was developed and more than 2 000 irregular specimens of over 60 kinds of rock from 16 mines and quarries were tested. The effects of size, shape and number of samples on the point load strength index were investigated, using regression analysis. Experiments were carried out to investigate the relationship between point load strength index and uniaxial compressive strength on 29 kinds of rock. The relationship between these values and the drill penetration rate for rotary and percussion drills is discussed.

Jan 1, 1986

By Eren H

For a hydrocyclone of fIXed geometry, DC, Di, DO and ? are constants, the variable parameters affecting the performance are Qi, Fi, Du and H. (See Appendix 2 for definition of symbols).The relationship between d50c, Qi, Fi, Du and H gives models which can effectively be used for performance predictions. Such models have already been established by Lynch et al and by Plitt.These models have been tried in a limited manner under continuous operating conditions for on-line cowol. For on-line control effective and accurate instrumentation is required for which a new set up is proposed. Using this set up, a new model was established. A feature in this model is that deviations from the norm of operational parameters affecting d50c were considered. It is shown that these deviations generated by the disturbance of one or more of variations in the parameters, can be monitored by a computer and suitable signals generated to control servo mechanisms for restoring the required d50c value.The logic followed in developing the computer software is described and the application of the model is indicated.

Jan 1, 1990

By P Moser, P Schimek, F Ouchterlony

This paper summarises the findings of 27 model-scale bench blasts in magnetic mortar, which were conducted from 2011 to 2014 at the blasting site of the Montanuniversitaet Leoben.The aim of the study was the investigation of the influence of blasthole delay times in small-scale bench blasts on the face characteristics and cracking damage created in the surrounding rock, which affects the fragmentation in subsequent rows.The test specimens or blocks, which were produced out of magnetite concrete, were roughly 1:100 in scale to normal bench blasts. The confinement of the testing blocks at the sides and back ensured the similarity to normal bench blasts with regard to the wave transmission into the surrounding rock. The specimen contained three or four rows with five blastholes each and were shot row by row, with virgin (undamaged) material in row 1 and increasingly damaged or preconditioned material in the following rows.The tested delay times varied between 0, 28, 73 and 140 µs, which corresponds to 0, 0.4, 1.0 and 2.0 ms/m of burden.The evaluation of the material properties showed that the use of magnetite concrete eliminated the inhomogeneous behaviour of rock, but some unexpected differences of the individual production cycles were still detected.The characteristics of the bench after each blast was evaluated along three horizontal lines out of a 3D model of the bench face. The tested delay time sequences of the virgin (first row) and single preconditioned blasts (second row) produced more overbreak for longer delays, while the third-row shots resulted in a smoothened surface independent of the chosen delay.The introduced damage after every blast was evaluated by an observation of irregularities on the newly blasted bench face. The visible cracks at the top of the testing blocks were documented and divided into several crack families according to their angle, length and origin. The remaining block was broken out of the blasting site after blasting, cut into several horizontal and vertical slices and dye penetrant spray was used to visualise the cracks created. Some of the detected crack families showed an influence of the delay time. The calculated mean crack density and mean crack intersection density showed that longer delays resulted in a higher degree of damage.The fragmentation results were well reproduced by the basic three-parameter Swebrec function. The observed improvement of fragmentation in the second- and third-row blasts was linked to the preconditioning of the burden for the following row while blasting the actual row. With the exception of the simultaneously initiated blastholes, the blasts showed coarser fragmentation for the shortest delays, while the longest delays generated the finest fragmentation.CITATION:Schimek, P, Ouchterlony, F and Moser, P, 2015. Influence of blasthole delay times on fragmentation as well as characteristics of and blast damage behind a remaining bench face through model-scale blasting, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 257–266 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

Rifting and transfer faulting in the Late Cretaceous to Early Tertiary resulted in the formation of the Bundaberg Trough and Wallaville Basin and deflected the margin of the Maryborough Basin southwestward between the Kolan and Burnett Rivers. During the Cainozoic, three periods of volcanic activity occurred in the Bundaberg-Gin Gin area. The oldest of these periods, Paleocene to Early Eocene, resulted in the outpouring of tholeiitic lavas. During the Late Miocene to Pliocene, undersaturated alkali basalts generated at depths of from ca. 35 to 55 km were emplaced. These lavas were followed in the Pleistocene by the alkaline Hummock and Berrembea Basalts. The loci of eruption of all of these lavas were controlled by the intersection of the transfer fault system and pre-existing north to northwesterly trending faults in the Bundaberg-Gin Gin area.

Jan 1, 1990

A new gold cyanidation assay technique has been proven for a range of ores, where it has demonstrated benefits of being: ò Accurate (reduces the typical range of assay scatter almost three-fold, and avoids common fire assay interferences). ò Fast (under one hour, providing a quantum shift in space requirement and equipment utilisation each bottle roll can provide over 15 determinations per day). ò Simple (suitable for field application, no high skill or experience requirements). ò Profitable (reduced drilling, drilling time, ore misclassification and/or double handling after mining). ò Cheap (far lower cost than Fire or Aqua Regia Assays, ie LeachWELLTM costs around 10ó for a 20 g sample at 50 per cent solids, proportionately greater for larger samples eg $1 for 200 g samples which address most nugget effect problems). ò Relevant (distinguishes economic. ie cyanide-extractable gold, the only unequivocal value to use for true resource definition, mine planning and grade control). ò Robust (rough bucket chemistry of samplers does not seriously affect results). A new development is the provision of LeachWELLTM CAS, a solution, which also contains optimum cyanide and stabiliser concentrations; and offers greater: ò Safety (the dilute cyanide solutions are stabilised to avoid generating toxic HCN vapours; and present no cyanide dust or flying chips to deal with). ò Ease (a single squirt dispenses precise quantities of the entire reagent suite, avoiding multiple weighings). ò Reduction in total reagent costs. An inter-laboratory comparison on nine ore types, using two assay techniques (Fire Assay and Aqua Regia) involving 45 laboratories, has demonstrated that LeachWELLTM 60X assays for the samples tested, were equally or more reliable than typical Fire or Aqua Regia Assays. There is particularly great benefit in applying LeachWELLTM 60X assays to richer ores in comparison to Aqua Regia assays, which appear to be prone to very significant underassaying depending on individual analyst skills, and which often suffer greater nugget effects. The major impacts for heap leaching are that: ò Using the LeachWELLTM assay technique for grade control, ore of marginal grade is not accidentally discarded to waste or visa versa due to the scatter of assay data inherent in typical small charge (25 g) fire assays. ò LeachWELLTM assays very importantly report only that gold which will be recoverable in the heap, viz that which is liberated - an important factor where the coarse crush often leaves ten per cent of gold unliberated. These impacts are of particular importance for many ores (ie most of those recovered from open pit operations and at the margins of rich ore subject to slurry processing) subjected to heap leaching as the oxide zones often present major problems of nugget effects as well as mineralisation that cannot be accurately assigned through interpretation of clear structural controls.

Jan 1, 1994

A practical approach has been developed for the design of both grates and pulp lifters. It is based on: an appreciation of the process interaction between grates and pulp lifters, an interpretation of mill charge structure as it relates to discharge through grates, and an analysis of pulp and solids flow in pulp lifter channels. This approach can be used to improve the overall discharge effectiveness of AG and SAG mills.

Jan 1, 2000

The major greenhouse gas emissions from coal combustion are leading certain people to argue for uranium mining and nuclear power to meet these challenges. Although there is considerable rhetoric around promoting nuclear power as 'green' due to its relatively lower greenhouse intensity, a careful study of the data is required to properly underst and the sustainability of uranium mining and nuclear power and whether it can or should have a role in future energy supply scenarios. This paper presents detailed research and analysis on uranium mining, focusing on known economic resources, production, solid waste and water management, pollution issues as well as energy and greenhouse aspects. A particular focus will be on Australia and its operating and prospective uranium mines. Overall, the paper raises fundamental issues concerning the long-term sustainability of uranium mining and nuclear power and documents the greenhouse intensity of uranium production and the nuclear fuel chain.

Jun 1, 2010

Statistics show that despite a low lost-time accident rate there is a high fatality rate from falls of ground in pillar extraction work. Investigation of accidents indicates that in many cases the planned ex- traction cycle has been ignored. Better training, supervision, and personnel protection and where possible changed systems are suggested as a means of improving safety and achieving better Results.

Jan 1, 1974