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By M Donatelli, E Grazio, A Heissenberger

The distribution of a contaminant in a bulk mass greatly influences the effectiveness of sampling procedures. Most currently used sampling guidelines for genetically modified organisms (GMO) testing have stringent distribution requirements. Specifically, all these protocols are based upon the assumption that GM material, if present, is randomly distributed. Yet, assuming randomness is risky because the applied sampling plan may not provide an accurate estimate of the content of the contaminant. Despite the general consensus that an evaluation of the possibility of non-random distribution of GM materials within lots is a pre-requisite for the definition of effective sampling protocols, no experimental data on the distribution of GMOs in kernel lots are available anywhere in the world. Additionally, to date there is no distribution-free statistical model to estimate sampling errors, thus making the theoretical definition of optimal sampling technique impossible when randomness cannot be assumed. Here we present preliminary results of the KeLDA project, which is the first study investigating the distribution of GM materials in large soybean lots imported within the European Union. The extensive variability of GM content, observable both within and among soybean lots, indicates that heterogeneity issues cannot be overlooked when defining sampling strategies for large lots of particulate material and that randomness cannot be assumed a priori. A new statistical model free from any distribution assumptions, developed in order to estimate the sampling error associated with different sampling protocols together with the risk of false-negative results, is also presented. The new model, which is applicable to any consignment of particulate material with respect to any kind of contamination, presents two novelties: first, freedom from any distribution assumption; second, the possibility of estimating the magnitude of the sampling error associated with different sampling protocols as a function of specific distributional properties.

Jan 1, 2005

By Boyle L. A

A positive displacement pump is being dev eloped for pipeline transportation of coking coal to a -50 mm export specification, at a con- centration and velocity which will allow trans- portation in the plug flow region, minimising degradation of the particle structure, and pipe= line friction losses which will be lower than with turbulent or laminar flow. Pump operation is by hydraulic powered free pistons in a rota- ting cylinder block, with cylinders overlapped by stationary inlet and discharge ports in a water lubricated and sealed rotary valve. Before this development coking coal was not considered suitable for transportation in slurry form, for the valves in the double act- ing duplex piston pumps used for slurry pipe- lines, cannot be divorced from the slurry and require that the solid material must be reduced to a fines'consistency before introduction into the pump suction. The hydraulic transportation of 10 million tonnes of -50 mm coking coal, 50 km from the Bargo area west of the escarpment to an offshore shiploader at Port Kembla is feasible. Study shows that economic factors alone would dictate that the development of a pumping system for long distance transportation of coking coal is necessary. The greatest impact from the slurry transportation of coking coal would be the

Jan 1, 1976

The comminution process indicates that the most energy-efficient comminution system would be one where the particles leave the breakage field as soon as they reach product size. Contrary to the free falling gravitational (vertical) flow in crushers, the grinding millÆs energy efficiency essentially depends on ore characteristics and the discharge rate of broken particles, which in turn depends on how efficiently the discharge pump (grate and pulp lifters) operates. The essential function of a pulp lifter is to transport the broken material and slurry from the discharge grate out of the mill. Hence, the design optimisation of pulp lifters affects not only the energy efficiency and throughput of autogenous grinding/semi-autogenous (AG/SAG) grinding mills, but also contributes other process benefits such as improved wear life and operator-friendly steady and smooth mill operation. Following its introduction in 2006, OutotecÆs patented Turbo Pulp Lifter (TPLÖ) design has been retrofitted at existing sites and also installed in some new ones around the world. This paper will provide operational experience and data on how the TPLÖ design has allowed AG and SAG mills to operate efficiently.

Jan 1, 2009

By S H. Algie, D P. Taplin, S G. Doig

"Suboptimal performance of clusters of hydrocyclones (cyclones), relative to the performance of the individual cyclones that comprise the cluster, is a common phenomenon. The primary cause is well known: uneven distribution of the slurry feed into the individual cyclones. The direct result of uneven distribution is that each cyclone in a cluster performs somewhat differently. Hence, some, if not all, of them do not work at their intended operating points, and the classification is not as sharp as intended. The impact on grade, recovery and milling efficiency will vary depending on the duty of the processing circuit, but the most immediately apparent consequence of uneven distribution is a difference in wear rates in the individual cyclones; this exacerbates the problems of unequal performance of the individual cyclones. In severe cases, and as differential wear proceeds, flows from the individual cyclones may become visibly different. Uneven distribution, once the phenomenon was identified, was seen to be a significant issue in the high-solids hydrocyclone cluster in the ball mill recycle section of Evolution Mining’s Edna May Operation (EMO, Westonia, Western Australia) gold processing plant. In 2012, a FloCEP® hydrocyclone feed distributor system was installed to alleviate the problem. Over the next four years of operation, this innovation has proven its value in the metallurgical and maintenance areas. Individual cyclones now wear at the same rate, greatly reducing the need for operator intervention, as well as increasing overall plant availability through minimising unplanned maintenance. The costs of the installation can be justified by savings in maintenance alone, though the greatest value, as is described in this paper, is in allowing the plant to produce consistently closer to its operational design limits. The FloCEP® system is a low maintenance, readily installed retrofit, based on two patented devices that are combined with complementary proprietary design methodology allowing customisation for specific flow rates and slurry particle properties. Together, these devices produce and distribute a pseudo-homogenous slurry flow without moving parts.Citation:Taplin, D P, Doig, S G and Algie, S H, 2016. Experience with FloCEP® Slurry Flow Conditioning at Evolution Mining's Edna May Operation, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 251–260 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By Ramsay WRH, Morand V

Structural, mineralogical, and textural data from the Tarnagulla Goldfield demonstrate that the area has undergone three significant phases of deformation. The first phase of deformation (Dl) predates the intrusion of the Tarnagulla pluton, which has been dated using K/Ar as 391 ¦ 5MY. We regard this pre-granite deformational event as the major regional deformation. Gold-bearing quartz veins have been deposited in dilational sites on west-dipping reverse faults. These sites demonstrate a geometry related both to faulting associated with Dl and the plunge of the Fl fold axes. This evidence, together with chronology of unmineralised ? D2 and D3 faults, the absence of quartz veining associated with D3 events, and the deformation of carbonate-quartz-biotite-sulphide aggregates within Sl by later S2, lead us to conclude that the bulk of the mineralisation was essentially syn- or late Dl. S'80 values for fluids in equilibrium with vein quartz from Central Victoria have indicated equivocal support for either a magmatic or metamorphic origin. Our evidence supports a pre-magmatic origin for mineralisation at Tarnagulla and hence tends to favour a metamorphic fluid source.

Jan 1, 1995

By Y Yang

Despite the importance and usefulness of basicity in metallurgical slags, the optimum quantitative expression of it has remained elusive, partly due to the fact that the precise concept of basicity has not been properly clarified. The two basic approaches to the concept of basicity are the Lux-Flood, which perceives basicity in terms of the activity of the free oxide ion, aO2-, and the Lewis, which perceives basicity in terms of the ability to donate negative charge. The former has been almost universally adopted in the area of metallurgical slags, while the latter has been increasingly accepted in the field of glass chemistry. In this paper, some difficulties of the Lux-Flood approach are pointed out, including the need for indirect measures of aO2-, which have proliferated in recent years. Accordingly, it is suggested that the Lewis approach has a good deal to commend it, and that the quantification of it in terms of optical basicity is the best measure of basicity available, which should therefore be more widely applied in metallurgical slags than it currently is. The fact that there are intrinsic problems in evaluating the optical basicities for the transition metal oxides is acknowledged, and a new scale is recommended. The patterns of iso-optical basicity lines in ternary systems are shown to agree well with the pattern of iso-activity and iso-capacity lines under appropriate conditions.

Jan 1, 2000

By O Aydan, R Ulusay

Blasting is the most commonly used excavation technique in mining and civil engineering applications. Blasting induces strong ground motions and fracturing of rock mass in rock excavations. Particularly, high ground motions may also induce some instability problems of rock mass and structures nearby. Furthermore, it may cause some environmental problems due to noise as well as vibrations of structures near the populated areas. Furthermore, flyrocks is another major issue for the safety of people and damage to machinery and equipments when blasting is employed. In this study, the authors explore the ways how to estimate the ground motions as a function of distance, amount of explosive, number of holes. The ground motions were measured by stand-alone accelerometers developed by the first author and some empirical relations are developed. The effect of ground motions on the instability issues of benches such as sliding, toppling and rockfalls were investigated. Furthermore, the flyrock issue is investigated and some empirical relations to estimate the maximum distance of flyrocks from the blasting relations are compared and discussed. CITATION:Aydan, O and Ulusay, R, 2018. The ground motions induced by blasting in open pit lignite mines and its environmental effects, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 142–151 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

Prefeasibility planning and cost estimation of conveyor systems has historically been undertaken by comparing fi xed plant transport requirements to that of similar systems in service. This paper describes the development of a prefeasibility conveyor technical design and cost estimation application using Microsoft Excel Visual Basic for Applications (VBA) platform. The application tool known as D-Convey (Dachshund Convey) was developed with the goal enabling the end user: to develop a technical model for conceptualised conveyor systems, to perform economic analysis on the developed technical model, and to conduct a comparative and risk analysis. An Excel VBA based platform was utilised to draw upon both the analytical and graphical capabilities of a spreadsheet. Some of the features of D-Convey system include a revolutionary dynamic graphical help system, known as the 'information pane' in lieu of traditional help fi les as well as the use of familiar graphical user interface elements such as the MS Offi ce 2007 task ribbon. The D-Convey system incorporates material database allowing for mass handling prefeasibility estimation in other industries; it has been validated at a local quarry.

Dec 6, 2010

By Matthew I. G, Hall P. G

The Selective Precipitation (Basics) Process is a means of controlling impurities such as the ions of Mn, Mg, and Cl as well as sulphate and water, in an electrolytic zinc plant circuit. This is achieved by precipita- ting zinc selectively as a basic zinc sulphate from a portion of impure circuit solution. The impurities remain in the solution, which can be discarded, while the zinc, substantially free of impurities, is returned to the main circuit by using the precipitate as a neutral- ising reagent. A description of the process and its development to a full scale operating plant at the Risdon Works of the Electrolytic Zinc Company of Australasia Limited is Presented.

Jan 1, 1977

By Bhaskara Sarma P V R

Solvent extraction of cobalt from an ammoniacal ammonium sulphate medium was carried out using Di(2-Ethyl Hexyl) phosphoric acid in kerosene as diluent. The effect of ammonium chloride and ammonium sulphate on the extraction efficiency was studied. The extracted species in the ammonium chloride and sulphate systems were CoAz2HA.NH4CI and CoA3.HA.2(NH4)2SO4, respectively. Ammonia scrubbing and cobalt stripping studies were carried out from loaded and ammonia free organic Respectively.

Jan 1, 1992

Stawell Gold Mines Pty Ltd operates two underground decline mines within the township of Stawell. An active exploration program and commitment by owners to improving the ore reserves has led to an improved mine life and reduced operating costs since the purchase of the operation by Mining Project Investors and Pittston Mineral Ventures in late-1992. Over the past six years of operation a cumulative 1 150 000 ounces of gold have been added to the mineral inventory. An improved geological understanding of the orebody has evolved over time increasing the ore reserves and allowing the development of long-term plans for the mines future. This has enabled important capital decisions to be made providing the impetus for improved productivity and thereby reduced operating costs. Co-operative mine planning and mine geology utilising best practice geological systems have enabled the effective extraction of a structurally complex and mineralogically varied deposit within a rural Victorian township. Detailed metallurgical research has improved the function of an aged and poorly designed circuit to boost the mill capacity whilst also improving the metallurgical recovery. The combination of metallurgical expertise and an understanding of the geological setting enable an effective control of metallurgical recovery.

Jan 1, 2000

By Rowe J

The case study is based on the largest ore deposit at Mt. Lyell; the Prince Lyell deposit, comprising a regular lensoid mass of dissemina- ted and vein pyrite-chalcopyrite mineralisation. Reserve estimation employs conventional techniques, based on diamond drill hole and relevant development sampling data. Probable ore reserves are estimated using the contouring (isoline) method an longitudinal projections for ore thickness and accumulation (m %Cu) at a '0.8% Cu' cutoff. Final stope and pillar res- erve estimates (proved ore) are derived from designed ring tonnages and contoured accumula- tion for individual mining units, following more intensive sampling. Systematic grade control procedures have been adopted and individual stopes and pillars reconciled against mill production. The proved ore estimates have been found to com- pare favourably with the reconciled production.

Jan 1, 1979

By N Udugampola, d A. Seneviratne, X Ai, B Li

With the evolution of mining technology, wireless mesh networks using low-power, long-range technologies such as LoRa are increasingly utilised in underground mining operations. Efficient deployment of wireless nodes in such mesh networks necessitates understanding radio wave propagation behaviour in underground mines. While existing propagation models either remain theoretical or apply only to basic geometric shapes, we propose a practical approach to analyse radio wave propagation behaviour in underground mines using ray tracing simulations with reconstructed 3D models of targeted environments. Our method validated using a set of corridors as a substitute for underground mine environments, involves constructing a 3D model using SolidWorks from LiDAR scans of the environment and performing wireless transmission simulations using the MATLAB ray tracing toolkit. Our simulation model is also fine-tuned by calibrating the raytracing parameters based on real-world LoRa transmission experiments in the actual environment corresponding to the 3D model. This method offers a practical solution for optimising wireless node placement in underground mines, facilitating efficient network deployment while reducing the need for extensive physical testing of radio wave transmissions.

Sep 1, 2024

This paper discusses the recently com- pleted TBM-driven pressure tunnel at the Sand Bar Hydroelectric Power Project. The Sand Bar Project is a diversion scheme situated on the middle fork of the Stanislaus River in the Western Sierra Nevada, California, U.S.A. As part of the project, a 5.6 km long and 3.71 m diameter unlined pressure tunnel was bored by a Jarva TBM at the average rate of .37.5 m/ day. This report deals with construction aspects of the tunnel, including TBM performance, lining design, and remedial support measures. Correlations between TBM performance, geologic conditions, and rock properities are made, and the Contractor's mode of operations are discussed. Advance rate prediction, and the impact of these excellent advance rates attainable in hard rock using the new machines are discussed.

Jan 1, 1987

By Amer S, Novais A. Q, Limpo Gil J

A proprietary hydrometallurgical ammonium chloride process for the recovery of not only zinc, but also copper, lead and silver from sulphidic zinc-rich concentrates has been developed at bench scale by CENIM and INETI (ex-LNET) as part of a research project supported by the Commission of the European Community (DGXII). This paper deals with the innovative chemical aspects applied to this chloride process and also with the more relevant data relating to mass balance, heat balance and process economics. Under mild temperature and oxygen pressure leaching conditions it is possible to extract practically all the zinc together with the other metals of interest and to precipitate simultaneously the solubilised iron fraction as goethite. The pH is kept close to neutrality in spite of the ammonia released in the leaching of the non-ferrous sulphides. A buffer effect is observed mostly due to the formation of zinc ammines which are very soluble in this medium. The zinc is further extracted by D2EHPA, the acidity being neutralised by the ammonia. Most of the ammonium chloride is naturally regenerated in this step. The zinc is recovered as zinc cathodes in a conventional sulphate electrowinning circuit. All the main raw material consumptions excluding the concentrate, such as oxygen, lime and ammonium chloride are linked to the sulphate formation in the leaching step which must be kept as low as possible by decreasing the reaction time under neutral conditions. The process analysis is complemented by the economic evaluation of a reference case. Difficulties encountered in finding a more convenient method of assessing the economics of the process in the absence of a reference price for a complex sulphide concentrate are examined and discussed. The reason why this analysis was performed with a much more optimistic metal prices scenario is also highlighted. The process economics are primarily dependent on the zinc market quotations and of course on the concentrate cost. Around 70 per cent of the total revenue is due to zinc sales. Assuming an internal rate of return of 17 per cent, the price of the concentrate can be as high as 255 $US/t for a plant capacity of 320 000 t/y (90 000 t/y of zinc).

Jan 1, 1993

By Manca PP, Lassandro R, Caranassios A, Massacci G, Ciccu R

The paper discusses the state of the progress reached in the development of the diamond wire tool for cutting hard rocks. To the advances of this relatively new technology a substantial contribution has been provided by the research being carried out at the University of Cagliari on samples of granite rocks from different Sardinian stone quarries. On the basis of field experiments and laboratory test data, the mechanism of diamond wire cutting has been assessed. In particular the influence of the rock features and operational variables on tool performance (cutting rate and bead wear) has been Elucidated.

Jan 1, 1992

By X Yang, T Zhang, Z Li, Z Yan, M A. Williams, S Qin, P Wilson

Continuous development of complex new steel grades to meet the ever-increasing demand of high performance causes recurrent issues in steel continuous casting such as surface quality defects (eg cracks, depressions, deep oscillation marks) and productivity challenges (eg faster casting, near-net shape casting). Continuous casting of steel is a highly successful metallurgical process. Much of this success can be attributed to the performance of the casting powder that is added to the top of the mould, creates a liquid slag pool as it is heated, and forms a slag film between the watercooled copper mould and steel shell during its passage down the mould. Mould powder selection is a compromise between the conflicting requirements of heat transfer and lubrication. In an EU RFCS (Research Fund for Coal and Steel)-funded project, various techniques are developed to offer the opportunity to adapt the slag film to meet the conflicting needs in different parts of the mould such that mild cooling can be generated in the meniscus, mid-broad face or corner areas whilst maintaining lubrication and offering higher cooling rates in other areas of mould. This has significant potential to address the industrial issues in product quality and productivity of continuous casting. This paper reports, as part of the EU RFCS project, the determination of crystallinity and porosity in slag films for casting challenging and innovative steel grades using new methods. In comparison with the methods such as X-ray powder diffraction (XRD) analysis and optical microscopy / scanning electron microscopy (OM/SEM) analysis that are currently adopted by the industries, EBSD (electron backscatter diffraction) has been employed to determine the crystallinity of the slag films taken from industry casters. X-ray computed tomography (XCT) plus 3D image reconstruction has been used to determine the slag film % porosity with pore volume, pore size distribution, and pore location, which can be linked with the performance of the slag films during casting different steel grades.

Jun 19, 2024

Depletion of shallow ore reserves is forcing the South African gold mining industry to exploit reefs at ever-increasing depths. By 2010 around 30 per cent of South African gold production probably will come from depths greater than 3 km (Johnson and Schweitzer, 1996). At such depths, virgin stresses will rise significantly, producing complex rock engineering problems (Malan and Basson, 1998). Concern over structural instability at depth has led planners to seek a technology capable of ædetection of geological structures with a displacement of 2 m or greater (or as appropriate to the mining technique) 200 m ahead of mining at an acceptable costÆ. Borehole radar probably is such a technology. Cover holes are drilled routinely ahead of development. The evaluation of its candidacy for a tactical role in ultra-deep gold mining dependsùamong other thingsùupon establishing the electromagnetic characteristics of the environment hosting significant gold reefs. The Ventersdorp Contact Reef (VCR) is one such reef. Recent borehole radar field trials, presented here, suggest that the VCRÆs overburden is a remarkably translucent, clutter-free dielectric with a Q of ~35 and that the VCR itself is the dominant radar reflector.

Jan 1, 2002

By G N. Musafer, M H. Thompson, R C. Wolff, E Kozan

The most important aspect of modelling a geological variable, such as metal grade, is the spatial correlation. Spatial correlation describes the relationship between realisations of a geological variable sampled at different locations. Any method for spatially modelling such a variable should be capable of accurately estimating the true spatial correlation. Conventional kriged models are the most commonly used in mining for estimating grade or other variables at unsampled locations, and these models use the variogram or covariance function to model the spatial correlations in the process of estimation. However, this usage assumes the relationships of the observations of the variable of interest at nearby locations are only influenced by the vector distance between the locations. This means that these models assume linear spatial correlation of grade. In reality, the relationship with an observation of grade at a nearby location may be influenced by both distance between the locations and the value of the observations (ie non-linear spatial correlation, such as may exist for variables of interest in geometallurgy). Hence this may lead to inaccurate estimation of the ore reserve if a kriged model is used for estimating grade of unsampled locations when non-linear spatial correlation is present. Copula-based methods, which are widely used in financial and actuarial modelling to quantify the non-linear dependence structures, may offer a solution. This method was introduced by Bßrdossy and Li (2008) to geostatistical modelling to quantify the non-linear spatial dependence structure in a groundwater quality measurement network. Their copula-based spatial modelling is applied in this research paper to estimate the grade of 3D blocks. Furthermore, real-world mining data is used to validate this model. These copula-based grade estimates are compared with the results of conventional ordinary and lognormal kriging to present the reliability of this method.CITATION:Musafer, G N, Thompson, M H, Kozan, E and Wolff, R C, 2013. Copula-based spatial modelling of geometallurgical variables, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 239-246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

A viable flow sheet of the sorption-flotation technology for gold recovery from low-grade ores and concentrates using powdered activated carbon modified by organic compounds as the sorbent-bearer has been developed. The powdered activated carbon, with high kinetic ability and sufficient specific area, was selected as the all-purpose gold cyanide complex-bearing sorbent which is active during flotation. To improve carbon adsorption capacity and to provide the required floatability its porous structure was filled with a quaternary ammonium compound which can extract gold cyanide complexes and render additional flotation properties to the carbon. To optimise the process and to simplify the layout, adsorption and flotation processes were carried out simultaneously in a mechanical flotation cell. The proposed technology was used for extended and pilot-plant tests of sorption-flotation gold recovery from 0.6 g/t Au final tailings and 2.0 g/t Au gravity tailings. The extended tests were carried out on Taseevskaya (Chita Region) flotation tailings, whereas pilot-plant tests were conducted on Kommunarovskaya (Krasnoyarsk Region) gravity tailings passing to cyanidation, followed by processing with filtration technology. Additional gold recovery from Taseevskaya final flotation tailings was 50.8 per cent. Gold recovery from Kommunarovskaya final gravity tailings was 92.5 per cent. Compared to the complete sludge process conventionally used at the plant, gold recovery was increased by 7.5 per cent due to lower gold losses in the liquid phase and conversion of the refractory non-cyanided metal into a carbon concentrate. This paper presents the experimental results of gold adsorption onto powdered activated carbon modified with quaternary ammonium compounds (sorbent-bearer) as well as sorbent-bearer flotation with various collectors from cyanide solutions and pulps.

Jan 1, 2005