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By A Garg

Squeezing can occur both in hard rock and in jointed rock mass as a result of over stressing. It is related to time dependent shearing, ie shear creep and is associated with the volumetric expansion (dilation) and radial inward displacement of the tunnel surface. While planning a tunnel in hard rock under a high cover of the order of 2 km it is desirable to identify the potential squeezing ground conditions and to select appropriate excavation technique and the support measures. There are several solutions to counter balance the squeezing ground viz over excavation of tunnel profile, assessing appropriate excavation technique, provision of a ductile primary support and time for providing tunnel lining. Low drivage rates and high cost due to support failures requiring rectification arising out of poor anticipation of tunnel closures and support pressures are major problems associated with tunnelling under squeezing ground conditions. Under squeezing ground conditions, the deformation will be gradual, therefore, in order to absorb deformations yielding supports are quite useful as primary support which provide a reliable low initial support pressure and permit uniform stress relief of the surrounding rock along with preventing rock from ravelling. The paper discusses the various factors which influence the selection of appropriate excavation technique and support measures in hard rock under squeezing ground conditions.

Jan 1, 1999

By M Dorricott

This paper describes the design, construction and performance of sill pillars using cemented development mullock at the Crusader Gold Mine. The orebody is some 35 m - 60 m in length, 5 m - 8 m wide, dipping at 60¦ - 85¦ and plunging at about 40¦ to the north. It is accessed via a footwall decline. The ore occurs at the contact between basalt and ultramafic. This contact is characterised by shearing and alteration; and is prone to unraveling failure. The cut and fill mining method at Crusader extracts 25 m high ore blocks in four flat back lifts and one 8 m thick crown pillar. To enable full recovery of these high-grade crown pillars with minimal dilution, a 5 m thick sill pillar is constructed using cemented rock fill (CRF), after mining of the bottom two lifts in each block. Uncemented development mullock is used as rock fill (RF) for subsequent lifts. Development mullock and cement/water slurry is mixed underground to produce CRF. The fill is transported to the stope in LHDs and dumped on the floor. The sill pillar is advanced progressively, with compaction provided by the loader driving over the previously placed fill. Old jumbo rods are installed as shear pins along the flat dipping hangingwall to reduce the risk of rotational failure of the pillar. A fan of cable bolts is installed into the hangingwall to prevent unraveling failure in the sheared ground. Buffer blasting is used to minimise damage to the CRF sill pillar when the crown pillar below is extracted. At the time of writing, extraction of the crown pillar underneath the CRF has taken place at the 930 stope. The crown pillar was extracted successfully with dilution from the backfill and hangingwall minimised and 98 per cent of the gold recovered. This compares with pillars that were mined beneath uncemented backfill where only 70 per cent of the gold was recovered and where there was significant dilution from the backfill and from hangingwall failures. Where no CRF was placed, there were also numerous production delays caused by large rocks from the hangingwall blocking the stope brow.

Jan 1, 2002

By J Gutzmer

The Kalahari Manganese Deposit in South Africa accounts for 80 per cent of the worldÆs land-based mineable Mn reserves. Although the ores are primarily mined for export, South Africa is the worldÆs third largest producer of ferromanganese and ferrosilicomanganese alloy, both of which are derived from the smelting of these ores. Mineralogical analysis has traditionally been forsaken for bulk chemical assaying in quality control of smelter feeds, principally because quantitative data could not be easily produced. Yet, mineralogy plays a vital role in determining smelting behaviour, which in turn has economic implications when aspects such as energy and reductant consumption are considered. Smelting is an endothermic process, and the amount of energy input required is dependent on the minerals present in the ore, as well as their relative proportions. Further, knowing the bulk Mn oxidation state in the ores allows for calculation of the amount of oxygen that must be driven off to produce alloy, and hence the amount of reductant required. Additionally, certain minerals can be correlated with potentially deleterious elements, so that ore mineralogy can indicate penalty element distribution. Mineral abundance analysis was conducted on ores from the Kalahari Manganese Deposit using quantitative X-ray powder diffraction. Rietveld refinement using a fundamental parameters approach was applied to micronised ore samples. The mineral percentages obtained were validated using mineral chemical data together with bulk major element data derived from ICP-OES. Bulk oxidation state partitioning was then carried out knowing the Mn valence in the minerals. The results show potential for implementation of the proposed method on a smelting plant, where ore blending could be then implemented to achieve consistent feed compositions to smelters. Selective mining could also be undertaken to obtain desirable ore compositions for domestic or international markets.

Jan 1, 2008

By R K. Dayal

Many transport tunnels show distress after few decades of construction. Owing to exorbitant cost of replacement, rehabilitation of tunnels has become inevitable and rapidly gaining attention/significance worldwide. This paper discusses the detailed planning and design of remedial measures for repairs and rehabilitation of the twin tube highway tunnel in India, at an elevation of 2200 m constructed approximately 38 years ago. The tunnel length is 2547 m having 30 m2 cross-sectional area of each tube. The tunnel is lined in stretches, totalling 60 per cent lined and the remaining portions are unlined. The tunnel has developed acute problems of rock falls, water leakage, distressed pavement and icicle formation resulting in slow movement of vehicular traffic which has also increased. Suffocation inside the tunnel caused deaths due to inadequate natural ventilation, hence artificial ventilation was deemed necessary and was provided in the restricted 28.5 m2 cross-sectional area of tunnel. The paper would be useful for planners, designers and construction engineers for setting future trends.

Jan 1, 1999

By M I. Pownceby, A Torpy, C Johnson, N C. Wilson

To extract uranium from low-grade, calcrete-hosted uranium (CHU) ore is challenging owing to the presence of carbonate and swelling clay gangue minerals that require an alkaline lixiviant to be used. Western Australia possesses ~75 000 U3O8 t in CHU resources. Improvements to alkaline leach extraction practices would improve the economic potential of these deposits.A column leach study of CHU ore was run for 105 days using an alkaline carbonate-bicarbonate lixiviant. The uranium content of the liquor plateaued after 75 days at ~275 mg U/L; the calculated maximum solution capacity was 800 mg U/L. Spiked peaks and troughs were seen in the data set beyond the 60th day, where concentrations ranged from 220 - 290 mg U/L, indicating possible cyclic uptake and loss of uranium from the solution.Pristine and leached ore samples were geochemically analysed and mineralogically characterised at high resolution using a field emission gun-electron probe micro-analyser (FEG-EPMA). Results showed that leached ore samples from the top of the column contained less carnotite than pristine ore. In contrast, leached ore samples from the column base contained regions with more carnotite than pristine ore, indicating precipitation. Three carnotite grain micro-structures were identified in the leached ore; fan-spherulite, granular and core-shell cubes, with evidence for multiple growth phases.Evidence of carnotite precipitation was seen at the edge of and in pore spaces within montmorillonite and dolomite grains. The point of zero charge of both minerals is lower than the pH of the lixiviant (pH 10.8), thus the mineral surfaces are negatively charged and would not attract UO2(CO3)34- ions out of solution. Similarly, the decrease in the uranium content of the lixiviant is not attributed to super-saturation, as this was unlikely to have been achieved. Work is ongoing to understand the reason for carnotite precipitation and the fluctuations in the lixiviant uranium concentration that are seen.CITATION:Johnson, C, Pownceby, M I, Wilson, N C and Torpy, A, 2013. Microscale characterisation of pristine and processed ore - implications for leaching calcrete-hosted uranium ore, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 303-316 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By Soldenhoff K, Levins D, Collier D, Day A, Secomb R, Brown S, Tapsell G, Bellingham A, Quan C

Bench and pilot plant studies were carried out at ANSTO to develop a process for rare earth recovery from the Mt Weld deposit near Laverton, Western Australia. This paper describes the development of the flowsheet, which is similar to conventional monazite processing, but with the introduction of several innovative steps to account for the complex rare earth mineralisation and the presence of specific gangue minerals. A unique feature of the flowsheet is the recovery of cerium by solvent extraction from a sulphate leach liquor. The process was tested continuously by the operation of a pilot plant at ANSTO's Lucas Heights Research Laboratories, Sydney in the first half of 1992. The plant, designed to treat 100 kg per day of beneficiated ore, confirmed the viability of the process, with rare earth products from the operation satisfying stringent buyer specifications.

Jan 1, 1993

By S C. Dominy

Current and proposed methods of resource classification relate to the geological, economic and technical confidence in the estimated resource. Geological confidence is, however, only vaguely defined. It is largely related to the level of drilling and sampling, to the geologistÆs perceived level of confidence in his/her work and on the continuity of the mineralisation. Rarely has any real attempt been made to assess how well a deposit has been explored, sampled and evaluated and how accurate or realistic the geological model is for the deposit. This contribution reviews the impact of two of the potential sources of error, ie sample recovery and quality. The first of these parameters is measured during logging and assaying, but is often forgotten during grade and tonnage estimation, and resource classification. Preliminary studies have shown that modelling of this parameter is a valid exercise, which should accompany the evaluation of grade and other economic parameters. The sample recovery factor for an ore block can then be used to reassess the confidence in the block. It could, for example, downgrade the status of a Measured Resource to an Indicated Resource even though standard methods might indicate that the higher classification is applicable. A method is proposed by which this recovery factor could be incorporated into current resource classifications producing a more sophisticated and comprehensive measure of sample quality. A review of the sources of error naturally leads to the assignment of scores to each stage of the evaluation process, depending on the methods used and assumptions made. Sample recovery is one important factor, which is likely to appear at several stages. These scores can then be weighted and combined in a manner resembling that used in the CSIR Rock Mass Classification. This score will then allow the resource estimate to be rated on a scale from 0 to 100 per cent to produce a Quality Control Index (QCI). However, this index must then be modified using an Evaluation Difficulty Index (EDI), which reflects the difficulty of a particular style of mineralisation to accurate resource estimation. This results in the production of a Resource Reliability Rating (RRR), which can then be linked to international classifications, such as the 1999 JORC; 2000 CIM; and 2001 EURO codes. This will permit a more precise definition of geological confidence levels or, combined with estimation error, produce a classification system in its own right. This same rating can also be used as the basis for technical audits of mineral projects.

Jan 1, 2002

By M Rankin, F Medina, R Verburg

We conducted a preliminary assessment of an extensive deposit of historic tailings discharged over a period of 40 years to the shoreline along a Southern Peruvian coastline. The tailings formed an extensive beach approximately 2.4 km long and 300 m wide. The tailings consist principally of pyrite (37 to 59 per cent), hematite (nine to 20 per cent), magnetite (three to 13 per cent) and quartz (11 to 36 per cent). The present operating company was required to evaluate the feasibility of capping the ocean side tailings deposit, however, given the size of the undertaking and the potential to reclaim residual minerals from the tailings, it was prudent to first evaluate whether capping would in fact reduce the impacts to the marine environment. Therefore this preliminary assessment examined: 1. metals contamination in tailings, shoreline porewater and marine sediments; 2. reactivity of tailings and acid generation potential; and 3. the potential for biological effects from metal contamination in the uplands tailings (solid phase) and beach porewater. Based on mineralogy, column leach studies and chemical results, the upland tailings have a high geochemical potential to acidify and release metals, especially copper, nickel and zinc, should they be subject to oxygenated and aqueous conditions. But, the extreme arid climate results in very low potential for precipitation and virtually precludes the transport of acid drainage reaction products from the upland tailings towards ocean. Wind erosion caused by offshore winds is likely a small source of tailing transport to the ocean. Since some potential exists to reprocess the tailings in the future, capping does not seem justified at present.

Jan 1, 2003

The paper explains the genesis of the Ballarat College of Advanced Education to its unique position in mining engineering education. A description follows of the development of the Graduate Diploma in Occupational Hazard Management which commenced in 1979 in the cooperative mode of four groups of three weeks full- time study followed by twenty-three weeks in industry. In particular an analysis will be given of the state of origin of students, ages and employing industries. Given the experience from the evolution of this course a similar process is described for the Graduate Diploma in Mining which has been accredited to commence early in 1987.

Jan 1, 1986

By Paine G. G

The measurement of the fragmentation size distribution of a blast muckpile can be achieved directly by screening the entire muckpile. Screening of muckpiles in a production operation is generally not practical due to the logistics and time involved moving large volumes of rock through a screening plant. An indirect technique to assess blast fragmentation size distributions has been developed. This technique uses photographs of the blast muckpile taken at intervals during the excavation cycle. The images from the photographs are input to desktop computer software via a digitiser tablet. The software compilates the rock fragment sizes and calculates a size distribution. This paper discusses the technique and subsequent data analysis. Examples of the application of this technique for the assessment of comparative blast performance are given.

Jan 1, 1990

The source and origins of the hydrothermal fluid of orogenic, or quartz-vein lode-gold deposits remain uncertain and disputed: Resolution would likely have a significant affect on exploration strategy. The gold-carrying fluid is interpreted to be a low-salinity mixed aqueous-carbonic fluid of near ambient pH and redox state, that may be derived either magmatically through crystallisation of granites at depth in the crust or through metamorphic reactions in a range of rock types. Classic isotope and geochemical tracers of fluid source have not differentiated these possibilities and have produced conflicting conclusions. Mass balance calculations show that fluid composition will be modified by wallrock reaction between source and deposit, and tracers should not be expected to give clear indications of fluid source. Fluid oxidation state can also be modified along flow paths. Tracers should be interpreted with care and with view to possible modification. Modelling of full flow paths and examination of the hydrothermal histories of proposed source rocks may be alternative approaches to determining fluid source.

Jan 1, 2002

By Olden WH

A scheme is presented whereby the complexities of design and operation of a hydraulically powered coalmine support are modelled using the finite element method. This enables predictions to be made of the interaction of the support with its environment in a variety of operating conditions. The model is a two dimensional representation. The modelling scheme was applied in two case studies. In the first, the performance of a four leg support was uprated by increasing the front leg force. The finite element model enabled changes in overall support performance to be verified. In the second case study, the change in lateral force developed by a two leg support was assessed with changes in support operating height and floor foundation stiffness. The modelling scheme is capable of further development with the possibility of extending the model into three dimensions and the addition of control elements that would enable an actual mining sequence to be Represented.

Jan 1, 1992

By Skinner J, Brackenbury K

The AuPlus" Systems have been applied in the gold mining industry to achieve improved gold recoveries, faster leach kinetics and reduced cyanide consumptions. Calcium or hydrogen peroxide, collectively known as peroxygens, can be used. The choice depending on plant design and the nature of the ore. Laboratory test work and plant trials are included in this paper to illustrate the benefits of peroxygen usage in extractive gold metal- lurgy.

Jan 1, 1991

The Australian mining industry has suffered from a decline in its public image during the past decade. This has occurred partly as a result of increased questioning of accepted social and economic values since the mid-1960s and the greater restrictions placed on industry since then, and partly ò from the industry's inability to effectively answer its critics. Public opinion surveys have shown the depth of the decline in the industry's community acceptability and highlighted those issues which people regard as disadvantages of mining. The industry's poor public image has contributed to the difficulties of attracting young people to take up professional careers in mining. All those involved in the industry have a responsibility to assist in activities designed to improve the industry community Acceptability.

Jan 1, 1981

This paper reviews the use of MTU diesel engines in uses such as Off-Highway Vehicles, Rail traction, Generating Sets, Marine Propulsion and Defence Applications, and focuses on a central theme of maximum power in the minimum of space.

Jan 1, 1986

There was a time, in the memory of some here tonight, when the annual meeting of The Institute was a nostalgic occasion. Often, in the 1920s, there was comment on the decline of Australian mining and on the lack of new mineral discoveries. When some of our Presidents prayed then for a new Bendigo, and instead were given a Mount Isa, they were justifiably disappointed because of the vastly different capital requirements.In 1967 the mining picture is very different. The recent mining developments in Australia are certainly as important as several Bendigos and several Kalgoorlies. The mining industry in Australia has never been more dynamic than today (Table 1). And if we ask why it is so dynamic, the answer lies in the role which overseas capital is playing in the industry. The contribution of overseas capital should concern us not only because we are members of the mining and metallurgical profession, but also because we have a duty to make our profession contribute as much as possible to the well-being of Australians. It is not sufficient to argue that overseas capital is good for the mining industry; we must also examine whether it is good for the economy and the nation. In this context the current criticism of the inflow of overseas capital into Australian mining is useful, for it gives us an opportunity to see what has resulted from the inflow.In discussing this question I do not suggest that we emulate Captain Hancock, that legendary Moonta mine manager who, according to Oswald Pryor's cartoon, used to say to his miners: "When I say a thing is, it is, even if it isn't". The question can only be discussed on a factual basis; and I would submit that many of the important facts relating to overseas capital in our mining industry are often overlooked or ignored. I would further submit, on the basis of these facts, that Australia's present day mining industry has been largely built on overseas capital and that the overall benefits of that capital to Australia have been enormous.

Jan 1, 1967

A new least-squares method for inversion of d.c. resistivity soundings from horizontally layered earth is proposed. Powers are used as measured data. Apparent resistivity is generalized and apparent parameters curves are defined. Estimates for parameter errors are often possible even when data errors are unknown or large. Acceptance or rejection of a model is made an easier decision. Total computational effort is often reduced when compared to global least-squares methods, because although several optimizations are needed, few data points are involved in each, and initial guesses are requested only once and not all at the same time. Correlations between parameters may be used to improve solutions. Precise indications for extra needed data points can be conveyed. A test example is worked out and a field sounding, taken by Rijo (1973, personal communication) in an alluvium-filled river valley in north-eastern Brazil, is studied.

Jan 1, 1987

A new experimental procedure for determining the solids flux curve is detailed. The procedure is based on measuring the concentration at various heights of a bed of settled solids formed during a semi-continuous sedimentation test. Unlike conventional thickener area calculations, the test procedure demonstrates the dependence of the flux curve on the system feed flux. At a given feed flux, there was good agreement between the solids flux curve determined by the method and continuous sedimentation results. The widely used method of Kynch was found to be restricted to relatively high effective feed fluxes and consequently there was poor agreement with continuous tests at low feed fluxes. The flux curve determined by the method of Coe and Clevenger was invalid for all feed fluxes. A case study shows how the required thickener area would vary for a number of fine coal processing options.

Jan 1, 1989

By Brook W. H

The history of the reduction of iron from its ores is lost in antiquity. Archreologists state that man has practised it for over four thousand years. Until comparatively recent times charcoal was the principal reducing agent for making metallic iron from its various oxidised ores. Coke was first used by iron founders in England in 1619, and its use spread gradually throughout the civilised world from then onwards. Indeed, the destruction of forests to obtain the requisite charcoal made the iron founders, both in England and America, extremely unpopular, and this hampered the iron industry to a considerable extent, until coal provided the metallurgist with a new and better fuel--coke which is used by most pyro-metallurgists today. The transition from wood to coal products for iron smelting had a profound effect on the location of iron works. Particularly was this the case in America where, in the infancy of the industry, practically each of the early States had its own iron producers, but as coal and coke replaced charcoal, there came about a concentration of the iron and steel industry around the coking coal deposits, and so today there are huge steel plants clustered around the soft coal basins in Pennsylvania and Illinois.The development of the iron and steel industry in Australia, which is comparatively recent by world standards, has been cradled in the coal basins of New South Wales. The first steel works of any consequence in this country were built near Lithgow, close by the mines which produced the coal for coking.Incidentally, these works were rather unique in that the three essential materials for iron and steel manufacture-ore, coal, and limestone-were found virtually at the works' back door.When, in 1912, the location of the proposed steel works for The Broken Hill Pty. Co. Ltd. for smelting ore from Iron Knob in South Australia was considered, the site ultimately chosen was at Newcastle, almost on top of seams of satisfactory coking coal. One of the major factors which had determined the site of the steel works was the fact that, about 1912, three tons of coal were required to produce one ton of finished steel product, and the relative economics of ore and coal haulage were much in favour of bringing ore to the coal.

Jan 1, 1947

By D Reid, A Fourie, J Ayala

This paper discusses cone penetration test correlations for loose gold tailings that were developed within a critical state soil mechanics framework. The development of a new calibration chamber for cone penetration testing that consists of a modified triaxial cell is described. Some of the early development and commissioning issues that were encountered, as well as the solutions adopted are outlined, including the system to prepare the samples and to acquire high-quality data from the testing. Also, the triaxial laboratory testing required to achieve the critical state line is described, including some of the basic precautions considered necessary as good practice. Additionally, the system adopted for volume tracking of the calibration chamber sample is described, which is essential for ensuring a reliable state parameter comparison against the acquired cone penetration test data. Finally, some laboratory test data from the calibration chamber is plotted against the soil behaviour type charts currently available from various authors.

Jul 1, 2021