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During mapping in the Bijerkerno area (Fig. 1), well-preserved sedimentary structures were found at three separate localities. The structures are of four varieties, which are 1. small-scale cross-bedding (Fig. 2),2. convolute bedding (Fig. 3),3. minor scour and fill (Fig. 4), and4. flame structures.Ripple-marking is also doubtfully present.These structures are best preserved in what was...

Jan 1, 1971

Warrego copper ore characteristically contains 0.05-0.2% bismuth, which on upgrading produces a concentrate of approximately 1.3% bismuth. Early smelting of this concentrate (1973) was accomplished in a flash furnace (eliminating 92% of the bismuth in the con- centrate) and Top Blown Rotary Convertors (eliminating 85% of the bismuth in the matte). However 1.3% bismuth was considered the max- imLun bismuth level that could be treated. Geological evidence indicated that the bismuth level in~the copper ore would increase and that the bismuth level in the Warrego ore would be 0.3-0.7% bismuth. Treating these ores would produce a copper concentrate with bismuth levels far in excess of those accept- able to the smelter and still produce low bismuth content blister (limit 0.03% bismuth).

Jan 1, 1984

By Forrester P. I, Richardson W

Methane in coal mines is an ever present hazard resulting in loss of lives and serious economic consequences. For effective control of methane, ventilation alone may not be totally adequate in some situations. In order to deal with such cases, new methods for the control of methane are being researched. One such method based on biotechnology has been investigated in Canada in the past several years. This method involves bringing methane oxidizing micro- organisms into contact with coal to oxidize the methane released to non-flammable products.

Jan 1, 1988

By Giles D, Wegmann D

The Mt Todd Gold Project is located 42 km northwest of the township of Katherine within the Northern Territory of Australia. It is situated in the southeastern portion of the Pine Creek Geosyncline. The Batman gold deposit, the largest of several deposits at Mt Todd, hosts an identified mineral resource of 92.9 million tonnes (Mt) grading 1.4 grams/tonne (g/t) as at 31 December 1993. Host rocks at Batman are assigned to the Early Proterozoic Burrell Creek Formation, comprising greywacke and siltstone interbedded with shale. Gold mineralisation is associated with a very broad zone of sheeted and stockwork quartz-sulphide veins that occupy a corridor of intense brittle fracture and faulting. A conceptual model of formation involves the dilation of joints and micro-faults within overlying sediments during sinistral movement along a basement shear zone. Synchronous granite intrusion generated convective circulation of crustal fluids through the sedimentary pile resulting in the formation of auriferous quartz veins within favourable structures. The Batman zone of mineralisation is not directly related to fold structures which typify several other major gold deposits within the Pine Creek Geosyncline.

Jan 1, 1994

By Noller B. N, McGill R. A

The Alligator Rivers Region has been the scene of one of Australia's most intensive environmental monitoring efforts since the current generation of uranium mining was mooted in the 1970s. Prior to mining, the local environment and the nature of potential impacts were not well known. The initial monitoring programs therefore included large baseline characterisation and research components. After some 15 years, water, soil and sediment monitoring programs have been reduced to a fraction of their early size, as the mining and natural systems became better known and characterised, and the actual nature of the environmental impacts were established. Modem techniques allow much more rapid and thorough identification of chemical species and elements of concern, allowing much more focused monitoring programs to be designed. In the 1980s data collection was emphasised at the expense of interpretation, and monitoring programs were maintained at much higher levels than were in fact required. It is now clear that investigations are important and should be distinguished from monitoring programs, and that the timely interpretation of investigations and implementation of recommendations can greatly reduce the effort and expense that can be involved in a monitoring program. Monitoring programs based on a sound understanding of potential environmental impact may then be efficient and cost-effective, yet provide sufficient information to assess the environmental impact of mining, guide further environmental protection measures when problems are detected, and demonstrate compliance with regulatory requirements.

Jan 1, 1994

By M I. Pownceby, A Guiraud, S Purohit

Sticking and breakage of iron ore pellets during high temperature reduction can result in several operational challenges during shaft furnace ironmaking. With the shift to H2-based DRI processes and decreasing iron ore quality, this issue becomes more prominent. It is therefore important to understand how the iron ore chemistry and mineralogy affects the sticking and breakage of pellets inside the shaft furnace. This study provides a review of the mechanisms that lead to sticking and breakage of pellets inside the shaft furnace. The sticking index of pellets is related to the rate of metallic iron production as well as the precipitation morphology of product iron. Sticking of pellets is also enhanced by the formation of low-melting slag phases. The breakage of pellets inside the shaft furnace is often associated with the mechanical load of burden and pellet swelling, which is caused due to iron whisker or protruded iron formation. This paper investigates how the composition of iron ore, particularly the presence of different impurity oxides such as SiO2, Al2O3, MgO, CaO and alkali oxides in the pellets, influences the sticking and swelling indices. The effect of ore mineralogy on these adverse behaviours is also discussed.

Sep 18, 2023

By E A. G Marques, P M. Dight, T A. V Costa, K Mercer

Brazilian banded iron formation (BIF), known as ‘itabirite’, is the main host rock for iron ore in the Iron Quadrangle mines, Brazil. Their geneses are controversial and it is agreed that diagenetic, metamorphic and tectonic events, as well as weathering processes, were responsible for the iron concentration. In addition, it is understood that weathering processes are mainly responsible for reducing the original high intact rock strength, and for generating deep weathered profiles with low strength rocks commonly observed in Vale’s mines.A considerable amount of work has been done to correlate the macro and micro aspects of the itabirites as physical, chemical and geotechnical characteristics that directly or indirectly affect the intact rock strength; however, it is not yet clearly understood what effects the weathering processes have on the strength reduction of these rocks and its associated impact on pit slope stability. This forms a key focus of the lead author’s current research work.This paper presents a review of the geological, geotechnical and weathering characteristics of the itabirites, and early results for the evaluations of fresh itabirites from the PhD thesis research being undertaken by the authors at the Australian Centre for Geomechanics, School of Civil, Environmental and Mining Engineering, The University of Western Australia, sponsored by Vale SA.The results showed that to evaluate the density and unconfined compressive strength (UCS) correlation, not only the porosity but also the geological features should be considered, as they are responsible for data dispersion; however, the presented data suggested a trend that provides the confidence to develop advanced studies and a data population increment to establish proper correlations to support a reliable UCS method.CITATION:Costa, T A V, Dight, P M, Mercer, K and Marques, E A G, 2015. An overview of the weathering process, preliminary density and unconfined compressive strength correlations for fresh itabirites in vale mines on the western side of the Iron Quadrangle, Brazil, in Proceedings Iron Ore 2015, pp 241–254 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By J Miedecke

A metalliferous mine has operated at Storys Creek from the 1890s to 1979. Storys Creek drains from a pristine catchment and National Park and remains as the most degraded stream from historic mining in north-eastern Tasmania. It has been the subject of public concern since the closure, particularly at times of high rainfall such as existed in 1985 and 1986. The mine is located on the banks of the creek, which flows into a major river, the South Esk River, which is one of TasmaniaÆs largest rivers and important for recreational fishing and water supplies. For much of the life of the of the operations tailings were directly discharged into the creek, and in latter years stockpiled or very close to it. Little rehabilitation was carried out at mine closure. The result was erosion and subsequent deposition on the banks of the creek downstream. Direct emissions of adit water and the consequential emission of contaminated ground water to the creek continue to affect water quality. Contaminant loads discharging from the mine and tailings comprise 70% of the metal load in the catchment and are by far the largest single source. Acidity data suggested that the introduction of systems to introduce alkalinity could be effective in ameliorating the residual acid drainage impacts in the Storys Creek catchment. After a period of investigations and trials which proved their effectiveness, treatments adopted have included the following: relocation of tailings to a constructed and clay capped disposal area and rehabilitation of tailings area; crushed limestone addition to stream flows; crushed limestone addition to creek banks and exposed tailings; sealing of a drainage Adit; and construction of an anoxic drain to generate alkalinity to surface waters draining to old mine workings. These innovative treatments have resulted in a marked improvement in water quality draining from the area. The anoxic drain is believed to be one of the few, if any, which has been constructed to have generated high levels of alkalinity from clean waters and offers a solution to the clogging problems experienced in such drains in the past. Similarly, the use of crushed limestone in an active stream has proved effective in buffering acid drainage and removing metals from solution.

Jan 1, 2003

By A McGann, P J. Coghill, D Miljak

"It is widely accepted that bulk ore sorting could provide a step change in processing of low-grade ores. For this to be achieved a rapid, accurate bulk sensor of grade is required as well as sufficient natural variation of grade in the ore stream. CSIRO trialled a magnetic resonance (MR) sensor capable of measuring chalcopyrite, and by inference total copper grade, on the 1300 t/h Ridgeway portal conveyor. The gauge produced an unprecedented set of data down to a 1 t scale for months at a time. This paper analyses the measured variation and compares it to a simple model derived from the bore core data and mixing within the block cave mine.The model of the small-scale (<1000 t) variation is developed using fractal methods which have successfully been used in the past for copper porphyry deposits showing a power law or near power law distribution of copper grade and vein sizes. These fractal distributions have two features highly favourable for segregating ore, a large proportion of low-grade pods and the large-scale spatial clustering of grade. We show the presence of fractal ordering in bore core data at short range in the Cadia Ridgeway porphyry deposit and measure its persistence in the crushed rock produced by the Ridgeway block cave mine over one month. The model is then extended to demonstrate the effect of varying head grade, mixing and pod (or diversion) weight on bulk sorting efficiency.CITATION:Coghill, P J, Miljak, D, McGann, A, 2016. Modelling Grade Variation in Crushed Ore at Cadia Ridgeway and Its Potential Consequences for Bulk Ore Sorting, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 77–88 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By C R. Fountain, R J. Sinclair

The zinc industry is dominated by the electrolytic zinc (EZ) process. The EZ process has a low tolerance for impurities, resulting in tight concentrate specifications. Many mining companies sacrifice zinc recovery in order to meet smelter specifications. Some have ore-bodies that cannot be economically developed because too much metal has to be sacrificed, or it is just not possible to meet the specification. The BUKA Zinc Process (BZP) has been developed as a method of producing high-quality zinc from a wide range of concentrates. It can have lower capital and operating costs than the conventional zinc and lead production routes. Advantages accrue from increases in metal recovery during concentrating, smelting and refining; the elimination of most of the capital and operating costs associated with lead smelting; reduced transport costs; lower zinc refining costs; reduced refinery residue disposal costs; and reduced future environmental liabilities. This paper describes results of testwork that has been undertaken to demonstrate the viability of the BZP on both test rig and laboratory-bench scale.

Jan 1, 1998

By Y K. Leong

Occasionally additives are used in the wet processing of iron ore tailings and slurries, for examples, in the thickening of tailings with flocculant to recover process water, and in the smooth pumping of concentrated slurries. They can mitigate slurry behavioural issues that could significantly affect the plant operation and production. The nature of iron ore business requiring the plant to have a high throughput to be economical, large amounts of slurries are therefore processed every day. The quantity of additives needed will correspondingly be large and so are the associated costs. This could have a significant impact on the plant profitability. If additives are used they must be very costeffective. NaOH is among the lowest cost chemicals available, at ~US$400 per ton. In this paper we will look at use of composite additives involving phosphate compounds with NaOH added to reduce the cost, for the control of iron ore slurries rheology. The NaOH worked synergistically with the phosphate compounds. The effectiveness of these composite additives in viscosity reduction can be neutralised by another cheap additive such as lime or a Ca(II)-based salt turning the slurries back to being a paste. Tailings paste is an ideal material for safe storage in the dam. These composite additives can also be used to facilitate the recovery of iron ore at commercial grade from tailings (Leong, 2020a, 2021a).

Sep 18, 2023

By J Shillabeer

Paste backfill has been adopted by many underground mines in North America and a growing number elsewhere. Paste offers a number of advantages. This paper suggests wider applications of paste technology to surface tailings disposal and water management. Advantages include improved overall stability, potentially easier permitting, smaller water inventory and earlier reclamation. It may be feasible to use the same plant to prepare backfill and to dispose of surplus tailings. Example cost models are given to illustrate potential applications.

Jan 1, 1998

By Hopkins G. M F

Intensive exploration of the Archaean ultra mafic sequence bordering the Kambalda dome has resulted in the discovery of at least ten dis- tinct areas of nickel sulphide mineralisation subsequent to the initial drill intersection in January, 1966. Sulphide ore reserves to June 30, 1972 were 19.36 million tonnes at 3.3% nickel after mining of 3.0 million tonnes at 3:7%,nickel since production commenced in March, 1967. About 75% of contained nickel metal reserves occur in sulphide concentrations located at the base of the-ultramafic sequence, in contact with underlying meta-tholeiitic basalt. The remaining reserve occurs in concentrations of sulphides within the ultramafic sequence, usually within 100 metres of the underlying contact and typically in proximity to contact mineralisation. These hanging wall orebodies are smaller, contain significantly lower con- centrations of sulphide, and generally exhibit higher Ni:S ratios than underlying contact ore- bodies. The majority of contact sulphides concentr- ations form narrow, elongate, north north-west trending bodies, closely coincident with fault bounded depressions in the contact. Detailed study of the Lunnon Shoot ore environment in- dicates that it was a locus of crustal failure during, and subsequent to, emplacement of ultra- mafic rocks. Resultant structures parallel and

Jan 1, 1973

By H S. Mitri, A Sainoki

Destress blasting techniques have been widely employed in underground mines for the purpose of preconditioning highly stressed rock mass. Appropriate applications of the technique successfully contribute to increasing mine safety (eg mitigating the risks for rock bursts). This paper presents a simulation technique to estimate the extent of damage zones induced by destress blasting. A 3D numerical model with a single blasthole is constructed with FLAC3D code, whereby static analysis is carried out in which horizontal and vertical stresses are applied to the model in order to simulate stress conditions in a deep underground mine. Afterwards, dynamic analysis is performed whilst applying time-varying blast pressure along the blasthole. The blast pressure profile takes into consideration an instantaneous increase and gradual decrease in blast pressure as well as the propagation of detonation along the blasthole. In this paper, constitutive models allowing for shear and tensile strengths of rock mass that are dependent upon strain rate are newly implemented into FLAC3D code with C++ programming language, whereby blast-induced damage is assessed by the extent of tensile and shear failure zones. The results obtained from the dynamic analysis show significant decrease in the extent of yielding zones induced by destress blasting with increasing the magnitude of in situ stress. They indicate that considering in situ stress state is indispensable in order to propose proper blast design for each level in underground mines. Based on these results, the relationship between the extent of the damage zone and depth at which destress blasting is performed is established. Furthermore, stress dissipation induced by destress blasting is examined with static analyses, in which the modulus of elasticity is decreased according to a rock fragmentation factor, a, only for the area where tensile and shear failures takes place during the dynamic analyses. A model parametrical study with respect to a is undertaken. The relationship between the rock fragmentation factor and the stress dissipation in the yielding zones is developed from the parametrical study. The developed relationship can be useful when destress blasting is designed for massive rock masses.CITATION:Sainoki, A and Mitri, H S, 2015. Simulation of damage zones induced by destress blasting, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 245–256 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Vanderberg B

A 3D, PC based computer program is currently under development by Blasting Analysis International, Inc., to analyze the kinetics of full scale blasts with two or more high-speed motion picture cameras. Todays common approach of utilizing only a single camera system can, in some cases, lead to great errors and erroneous conclusions when motion is assumed to be in a predefined plane of motion. CMe phrase, "What you see is what you get, it no longer true in 3D."). This is especially true in blasting environments which exhibit complex and/or predominant structural geology. The 3D system eliminates this problem, and includes automatic corrections for vertical and horizontal camera optic axis orientation, dimensional controls, lens distortion, field set-ups, projection imaging and digitized inputs. The only information required is the surveyed or known coordinates of at least six non coplanar points in the field of view. Motitn from each camera view is then digitized, transformed through a direct linear transformation, and processed with the 3D software, which also automatically time matches the data, even when the high-speed cameras are operated at different speeds. Eleven calibration constants are generated using an overdetermined system of linear equations to output the true 3D coordinates of motion in the time domain. Applications for this 3D approach are not restricted to just analyzing the kinetics of a blast. The system is sufficiently flexible to allow an accurate, quick and economical method of bench face profile analysis, generate muck pile profiles and estimate volumetric calculations. The recording systems for these applications can be common 35mm still photography and/or video equipment. It is envisioned that this system will soon replace expensive laser surveying systems at a fraction of the cost in the near future. It is also an excellent system to accurately quantify drill pattern layouts and the spatial locations of each blasthole. This information is required for generating single hole based synthetic seismograms to accurately predict the vibrational outputs of full scale blasts. In terms of litigation concerning claims resulting from blast induced ground vibrations to structures, the system is proving to be an excellent and economical method of performing pre-blast surveys where differential settlement is suspect.

Jan 1, 1990

By R Shrimali, P Rajmeny, L Shekhawat, A Joshi

Rampura Agucha open pit mine has successfully been excavated to a depth of 320 m, incorporating multistage working. The key to success is the implementation of presplitting as control blast measures at every stage of mining, including intermediate cut backs, in addition to the final wall. The major challenges encountered in establishing presplitting in the hang wall as compared to the footwall of the mine are:reversely dipping foliation, ie dipping into the hang wall itselfstriking obliquely at an angle of 20–30° with regards to the general strike of the pit wallthe presence of numerous geological planes of weaknesses like major faults, slips, etc.Control blast parameters like hole inclination, spacing and stand-off with buffer row were chosen initially from the literature survey and were subsequently fine-tuned by field trials to the mine geo-mining conditions of the hang wall. Electronic initiation used for trim blasts along with double presplitting in fault-affected zones helped in getting better presplit performance and resultant stability of the hang wall.CITATION:Rajmeny, P, Shrimali, R, Shekhawat, L and Joshi, A, 2015. Establishing the design parameters of a control blast for long-term stability of the hang wall at Rampura Agucha Mine, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 437–446 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

Mining of the Martha Hill epithermal gold deposit via open pit methods will excavate a pit to 15 m below sea level. Regular geotechnical evaluations of pit slopes have taken place. Details of the various components of these evaluations, including geological structure, material strength, and groundwater, are covered. Pitwall geological structures are represented clearly on pit floor grade control maps with the dominant sets being steeply dipping strike fractures. Cross cutting shears are common. Material strength is reflected by the oxidation status of the hydrothermally altered host rocks, with weaker material occurring in partially oxidised ground. Regional groundwater is generally high, particularly on the north-eastern side of the pit, where it has been little affected by de-watering. Geological structures appear to control the flow of groundwater in the proximity of pitwalls and require draining by the introduction of horizontal drains. An overview of pit slope design is given. Slopes are designed for overall slope stability, allowing for the occurrence of minor interbench failures.

Jan 1, 1991

By C Li, K McDonald an, T Nicholson, C Brown

The relative reactivities of chars prepared from different coal samples at temperatures in the range 500 to 1150¦C were determined by measuring the rates of metallisation of a standard ilmenite concentrate. The results have been interpreted in relation to different measured physical and chemical properties of the chars. Char reactivities were found to correlate with the maximum specific surface area (SSA) of the chars, obtained from plots of SSA versus temperature. Weathering of coal samples gave higher reactivities which correlated with higher SSAs. Experiments using recycled chars showed that the high internal SSAs developed during earlier reduction reactions provide no benefit in terms of increased metallisations. The important role of char hydrogen contents in controlling low temperature metallisation rates was demonstrated. Chars prepared from different rank coals had the same hydrogen content when prepared at the same temperature. Ilmenite metallisation rates had a linear dependence on the hydrogen content of the chars. Large differences in the slopes of the metallisation versus H2 content curves for different chars were interpreted in terms of SSA variations and catalysis of the gas reactions by dispersed metallic iron particles in the chars. A simple test based on magnetic separation of the char was shown to give an indication of enhanced reactivity due to contained metallic iron.

Jan 1, 2001

By J Mukhopadhyay, J Gutzmer

Most world-class high-grade (60 - 67 wt per cent Fe) hematite iron ore deposits are the product of enrichment of Precambrian iron-formations but processes responsible for enrichment are still unclear. Different models, ranging from syngenetic and diagenetic (King, 1989), deep-seated hydrothermal (Powell et al, 1999; Barley et al, 1999; Taylor et al, 2001; Gutzmer et al, 2002) and ancient supergene (Morris, 1980; 1985; Van Schalkwyk and Beukes, 1986) to modern supergene (MacLeod, 1966) have been suggested. The high-grade hematite deposits stand in contrast to martiteûgoethite ores which are generally accepted to be the result of supergene enrichment of iron-formation because they are found along Cretaceous to Tertiary lateritic weathering profiles (Morris, 1980; Harmsworth et al, 1990). Uncertainties about the origin of the high-grade hematite ores appear largely due to the monomineralic composition of the ores. They are almost exclusively composed of hematite (as microcrystalline hematite and martite), a mineral with wide stability field and very simple chemical composition that reveals little about its origin. Second, many of the deposits have been overprinted by later deformation and chemical weathering obscuring primary ore characteristics and zonation (Taylor et al, 2001). Third, surprisingly few detailed geological studies have been undertaken on the deposits with the aim of unraveling ore genesis. Most studies focus on the present-day structure of orebodies and their general physical-chemical composition for mining and beneficiation purposes. A more thorough understanding of the origin of high-grade hematite iron ore deposits may be gained by combining available mining-orientated data with systematic petrographic-geochemical analyses of different ore generations and hematite phases. This paper presents a first summary of results of an ongoing study, started some two years ago, of high-grade iron ore deposits in South Africa, India and Brazil, including a comparison with the rather well studied deposits of the Hamersley Province in Australia.

Jan 1, 2002

By L M. Zhang, X Y. Li

Surface displacements are routinely monitored at multiple points during slope excavation. The monitoring data reveals the safety status of the slope under current loading conditions. They can be used to enhance the prediction of the future performance of the slope by reducing the uncertainties of the prediction model and its model parameters. In a multistage excavation, the observed displacements in the current stage can be used to update the prediction of the displacements in subsequent stages. Besides, due to the spatial correlation of the slope parameters, the prediction of the displacement at one location can also be updated using the monitored displacements at adjacent locations. This study aims to develop a multistep updating method to enhance the prediction of the future performance of the slope using time-series monitoring data at multiple points. This method integrates the theoretical computational model with observational evidence. It considers the inherent uncertainty of the slope, model uncertainty and measurement uncertainty. With more monitoring information being incorporated, the prediction becomes closer to the actual performance of the slope. A case study of a multistage excavation of an extremely high rock slope in south-west China is presented for illustration.CITATION:Li, X Y and Zhang, L M, 2014. Better prediction of performance of a slope using time-series monitoring data at multiple points in a multistep excavation, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 183–188 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014