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By D David

The majority of SAG and ball mill design methodologies are applied using a single design value for mill selection, such as the 80th percentile ball mill work index or SMC value. Inherent in the selection of this design value is a desire for the mill to accommodate unfavourable, but not absolute worst case, feed conditions. It has been observed in numerous “post-mortems” of unsuccessful designs and also in many optimisation studies, that the selection of the design value has been poor. Statistical analysis of testwork data sets shows that inherent variability in the data can, by itself, lead to design errors. Metallurgical testing is an attempt to measure the characteristics of millions of tonnes of ore using only a few kilograms of sample. In this paper some realistic but synthetic test work data sets are used to explore old and new methods of defining the design envelope and subsequently selecting a reliable point. The aim of the paper is to provide practitioners with tools that reveal the adequacy (or otherwise) of metallurgical test programs intended to support various levels of project design. It also provide guidance as to how it is possible to statistically justify a comparatively high design point in the absence of adequate test data.CITATION:David, D, 2015. Measuring and taking notice of orebody variability – an essential ingredient for reliable plant design, in Proceedings MetPlant 2015, pp 10–26 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By J Ward, B Rohrlach, B Rosero, J Silva, O Poma

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Alpala copper-gold deposit is a recent, high-grade porphyry Cu-Au discovery located in the Imbabura Province of north-western Ecuador. The deposit lies along the crustal-scale Chimbo-Toachi Fault Zone within the Dagua-Piñon terrane, which is an oceanic plateau accreted to the South American convergent margin in the Late Cretaceous. The deposit is hosted by quartz diorite stocks that intrude andesitic volcanic breccias of the Oligocene to mid-Miocene San Juan de Lachas Formation. Miocene-age calc-alkaline plutonism is associated with porphyry Cu, Cu-Mo and Cu-Au deposits in southern and northern Ecuador. The Alpala deposit lies along a sector of the Miocene arc that has recently been underplated by the Carnegie Ridge seamount chain that induced shoaling of the subducted Nazca plate beneath northern Ecuador.Surface expressions of the deposit were recognised in May 2012 during follow-up of stream sediment anomalies, when outcropping sheeted and stockwork porphyry-related veins were discovered in Quebrada Alpala. The roots of a NW-trending, structurally-controlled lithocap were recognised over an area of 4.5 × 0.9 km. The remnant lithocap exhibits well-defined mineral zonation mapped by TerraSpecTM analyses on grid soil samples. Soil sampling, heliborne magnetic surveying and channel sampling defined initial drill targets.Seven diamond drill holes were completed in the year from September 2013. Drill hole CSD-13-005 intersected 672 m grading 0.93 per cent Cu and 0.91 g/t Au in high-temperature, inner propylitic and locally potassic-altered quartz diorite intrusions. Overlying hydrothermal clay alteration assemblages define the base of the lithocap. A NW–SE trending footwall structure defines the south-west margin of the deposit. Drill hole 5 intersected high-grade sheeted ‘B-type’ and ‘C-type’ veins (Gustafson and Hunt, 1975) that lie along the south-west margin of an 1100 × 500 m magnetic anomaly that is the focus of ongoing exploration.CITATION:Rohrlach, B, Poma, O, Rosero, B, Silva, J and Ward, J, 2015. High-grade porphyry copper-gold mineralisation in north-west Ecuador – The Alpala Cu-Au porphyry discovery , in Proceedings PACRIM 2015 Congress, pp 369–376 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

Biosorption of Cr(VI), Pb(II) and Zn(II) from Aqueous Solutions by Immobilised Phanerochaete chrysosporium Biomass in a Fixed-Bed Column The continuous-flow adsorption of Cr(VI), Pb(II) and Zn(II) from aqueous solution by immobilised Phanerochaete chrysosporium biomass in a fixed-bed column was studied. The effects of flow rate, influent concentration of Cr(VI), Pb(II) and Zn(II) and bed depth on breakthrough curves and biosorption capacity were investigated. The experimental results showed that the breakthrough time decreased with increasing flow rate, increasing influent concentration and decreasing bed depth. The data also indicated that the equilibrium uptake of Cr(VI), Pb(II) and Zn(II) increased with decreasing flow rate and increasing influent concentration of Cr(VI), Pb(II) and Zn(II). Two models were employed to predict the breakthrough curves and to determine the characteristic parameters of the column useful for column design. The Thomas model was able to predict the breakthrough curve in the range of relative concentration(Co/Ci) higher than0.3, Cr(VI), Pb(II) and Zn(II) whereas the validity of the Bohart-Admas model was limited to the initial part of breakthrough curve at all flow rates and influent concentrations of Cr(VI), Pb(II) and Zn(II). The feasibility of reusing the immobilised fungal beads through five adsorption/desorption cycles in fixed-bed column was investigated.

Sep 13, 2010

By R P. Callaghan

Underground production from the low grade copper orebodies at Mount Lyell in recent years has involved surface subsidence of open cut areas. Relevant structural and lithological features of the geological environment are described. The highly mechanised underground mining system involves sublevel caving and sublevel open stoping with associated hanging wall cave. Monitoring of subsidence and caving has been made by regular visual inspection and measurement of crack development, and by surface profile surveys. These simple techniques have proved adequate in assuring management that ground movement is proceeding normally and safely.

Jan 1, 1980

By Mukhopadhaya K. K, Cory A. H

The concept of using travelling magnetic fields created by linear motors was stimulated by Laithwaite who advanced ideas on motors with shaded poles (Laithwaite, 1968), rack and pinion motors (Laithwaite, 1970) as well as low speed, brushless motors and three dimensional motors (Laithwaite, 1973a and 1973b).Sudan (1963) and Sundberg (1969) had applied the concept to metallurgical processes. However, the use of travelling magnetic fields has not been used widely to produce conditions for the separation of magnetic from non-magnetic minera1s or even magnetic materials from non-magnetic materials, although some attempts were made by McCarthy (1922), Davis (1934), Dean, Gottschalk and Davis (1934) and Gottschalk (1934).Laithwaite (1973, a) while working with linear motors made suggestions for designing separators and in the work described here, the observations of Laithwaite and others are extended to determine the characteristics of the motor with a view to using it as a magnetic separator.

Jan 1, 1980

By A Giblett, K Afewu

This paper uses a case study to demonstrate best practices techniques for predicting the contribution of gravity concentration in a gold recovery process flowsheet. The case study was selected as an example of an ore with a marginal gravity gold content, which makes the value of a gravity circuit difficult to quantify. In this instance the value of leveraging a significant knowledgebase of operating gravity circuit performance to support the decision making process was demonstrated. This case study analysis serves as a useful demonstration of best practice methodologies supporting decisions to include or exclude gravity recovery in a gold recovery process flowsheet.CITATION:Giblett, A and Afewu, K, 2015. Do we need a gravity circuit or not? A case study in applying best practice, in Proceedings MetPlant 2015, pp 288–295 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By G Tripp, G Lorusso

The Velvet gold orebody (153 Koz Au) is located near the Kanowna Belle gold deposit in the Boorara Domain of the Kalgoorlie Terrane, a subdivision of the Archaean Eastern Goldfields Superterrane (Swager et al, 1990). Gold mineralisation at Velvet is hosted within an intrusion of intermediate composition that broadly follows a sub vertical hanging wall splay of the Fitzroy Shear Zone.Velvet was discovered in 2003 during an underground exploration drilling program targeting potential strike extensions to the Kanowna Belle deposit. Diamond drill hole KDU1595 returned a downhole intercept of 36 m grading 4.6 ppm Au approximately 500 m west of the deposit and at a vertical depth of 700 m below surface in the immediate hanging wall of the primary Kanowna Belle host structure, the Fitzroy Shear Zone. Subsequent drilling completed following the initial discovery, from both surface and underground collar positions, failed to replicate this result.In 2014, KDU1595 was resurveyed gyroscopically and the mineralised intercept correctly located. Additional drilling was undertaken to follow-up the repositioned discovery hole. Challenges included poor drilling angles through the Fitzroy Shear Zone, excessive deviation during drilling and the unknown geometry of the target. Navigational drilling helped to successfully penetrate the Fitzroy Shear Zone and in April 2015, drill hole KDU3234 returned a significant downhole intercept of 45 m grading 5.6 ppm Au.Additional drilling success resulted in a decision to develop a 600 m drive to serve as a dual-purpose access for further exploration and mining. This was a potential risk considering that the orebody geometry was unknown and all significant drilling results were clustered within a 50 m × 50 m panel. Development commenced in June 2015 and the first ore cut taken in April 2016. Geological mapping and structural interpretation, together with multi-element and spectral analysis of drill samples has enabled several other target areas to be identified for exploration. The Velvet mining area is critical to continued production at Kanowna Belle. Geological understanding must advance as mining progresses to ensure continued resource growth and optimal extraction of reserves.CITATION:Lorusso, G, Rogers, J and Tripp, G, 2017. Velvet underground exhumed – discovery and development of a new mining front at the Kanowna Belle gold mine, in Proceedings Tenth International Mining Geology Conference 2017, pp 169–174 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By P Landeros, D Benado, J Cornejo, A Pinochet, C Caviedes

In 2005, El Teniente mine began preconditioning the primary rock mass by hydraulic fracturing (HF). The major perceived benefits of this process are a decrease in the magnitude of the expected maximum seismic event and improved cave propagation. In addition, HF has resulted in new information on the propagation pressures of each fracture. Previous studies have attempted to relate propagation pressure to minor principal stress or confining stress.Considering the spatial continuity of propagation pressure and the significant quantity of collected data since the incorporation of the HF technique, minimum requirements for geostatistical modelling have been reached, permitting robust estimates inside the representative volume with acceptable errors (Cornejo, Muñoz and Rojas, 2012; Cornejo and Landeros, 2013). These results are then used to identify zones with higher magnitudes, which are mostly related to more complex geotechnical zones (intrusive and major faults) and caving singularities, making it possible to estimate the spatial extension of these zones.Finally, these results are integrated with other geomechanics aspects to support risk analysis of the mining plan.CITATION:Cornejo, J, Landeros, P, Benado, D, Caviedes, C and Pinochet, A, 2016. Geostatistical modelling of hydraulic fracturing pressures at El Teniente Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 183–190 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

Wetting Characteristics of Mineral Surfaces - Contact Angle Measurements through Molecular Dynamics Simulations

Sep 13, 2010

By K Niyomjinda, B Etschmann

Chatree Gold Mine is currently the only modern day gold mine operating in Thailand, and is situated approximately equidistant from Chiang Mai in the north and Bangkok in the south. Environmental guidelines set by the Thai authorities require Chatree Gold Mine to achieve a Total Cyanide level of 20 ppm or less in the process plant discharge slurry stream prior to release into the tailings storage facility. This paper describes both the initial difficulties faced in achieving compliance on this limit utilising the conventional INCO SO2/Air cyanide destruction system and the subsequent process improvements initiated to both the leaching process and the standard INCO process to achieve the current compliance levels of approximately 99/100 shifts. Improvements were focussed on the dual aspects of reducing the formation of WAD cyanide and ferrocyanide species in the leaching circuit coupled with process changes to improve removal of the ferrocyanide species from solution during the cyanide reduction stage.

Jan 1, 2004

By Moorrees C, Everson P

A detailed examination of carbonic acid leaching of crude iron-containing magnesia derived from Savage River magnesite shows that the rate and extent of magnesium and iron dissolution are affected by the slake time, leaching temperature, carbon dioxide pressure, pulp density and rate of agitation. In order to produce high-purity magnesia from the leachate by precipitation and calcination, the optimum leaching conditions, which are those that yield maximum magnesium and minimum iron dissolution, have to be a compromise in terms of the above parameters. For example, iron dissolution can be limited by leaching at an elevated temperature (-45°C), but because the maximum concentration of magnesium biearbonate decreases rapidly with an increase in temperature, it is necessary to use a low pulp density (-2 per cent solids) in order to achieve an acceptable degree of magnesium dissolution.Evidence is obtained that iron dissolution involves the formation of a soluble ferric bicarbonate complex that decomposes at elevated temperatures. The extent of iron dissolution is much higher than might be expected and it is probably because the original magnesite contains siderite in solid solution with the magnesite; on calcination, the hematite whieh is formed is in a very finely divided condition and hence more reactive.

Jan 1, 1983

By A M. Purba and A Sjadat, A D. Wilson

Ongoing mining of the East Ertsberg Skarn System orebody below the Gunung Bijih Timur and Intermediate Ore Zone caves has been relatively successful and a ramp up to 80 000 t/d was achieved in the Deep Ore Zone Mine. However, the distribution of production, the overall drawpoint availability as well as the rate of change of the cave back profile has not followed the anticipated path. Several key factors influencing cave growth and progress, grade variation, fragmentation, wet muck and surface subsidence have been recognised over the life-of-mine that now have to be taken into account for planning the later stages of mining.The paper will discuss the influence of geological controls of lithology and structure – how this as well as other contributing aspects have impacted ore flow, contributing to some of the widespread panel damage, and been a key factor in compacted draw columns and caused an accelerated appearance of water ingress. This in turn has rapidly changed the distribution of wet drawpoints requiring remote mucking and special controls that also affect the call from the remaining dry drawpoints. Comment is also made on the potential final cave profile if it continues along the current trend and some discussion is offered about possible mitigation measures if this were to come about.CITATION:Wilson, A D, Purba, A M and Sjadat, A, 2016. Progressing cave performance into the later stages of the Deep Ore Zone mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 285–292 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

Conservation and environmental issues are raising their profile with respect to both demand restraint and electricity supply options. In New Zealand, conservation pressures and energy efficiency need to be seen in relation to the supply system currently in place which has capacity for economic supply of electricity in quantities substantially in excess of the current market. Consequently, energy efficiency and conservation need to be interpreted in relation to the supply system as well as in relation to end use. The relationship between the environment and conservation is strongest when new generation is required. New Zealand's electricity supply system consists of a large proportion of hydro production and this has significant environmental benefits when considered in relation to concerns of global wanning and the greenhouse effect. However, environmental trade-offs in supply options need to take account of both the efficiency of electricity end use, the trade-off between hydro and thermal generation and the inter-regional effects of shifting development options from one region to another. The Electricity Corporation has a high level of consciousness with respect to environmental and conservation issues and this paper demonstrates its own moves to maximise energy efficiency and illustrate the environmental trade-offs for supply.

Jan 1, 1990

By B Murphy, A Uliana, P STrgio de Oliveira, G Ara·jo de Souza Franco, T Miettinen

Outotec has performed numerous research and development projects and various surveys in the study of reverse iron ore flotation. Over the past four years their TankCell-70 and TankCell-160 flotation cells at the Germano concentrator of Samarco in Brazil were extensively surveyed. These surveys have revealed some extreme operating conditions in reverse iron ore flotation and are the subject of this paper. Some of the findings include large variations in the content of solids in the various flotation stages. At the bottom of the cleaner cells, the content of solids by weight reached over 60 per cent, whereas at the bottom of the scavenger cell this was less than 50 per cent. Froth carry rates were also significantly different in the various flotation stages. In the case of coarse material, the scavenger cells operated at a froth carry rate of over 40 t/h.m2. With fine material, however, froth carry rates of less than 10 t/h.m2 were measured. High froth carry rates caused significant changes in the residence times at Samarco. In the rougher cells, the fifth cell had more than double the residence time of the first cell. This was even more pronounced with the scavenger cells, where the second cell had more than triple the residence time of the first cell. High froth carry rates also caused losses in iron recovery. As a consequence of such findings, it appears that different rules apply in the sizing of reverse flotation circuits compared to direct flotation circuits. Different operating parameters (mixing intensities and air flow rates) must also be used in the rougher, cleaner and scavenger cells in order to optimise the metallurgical performance. Outotec has also been working on a number of new technologies aimed at improving the metallurgical performance of iron ore reverse flotation circuits by increasing froth carry rate and decreasing fine iron entrainment.CITATION:Miettinen, T, Uliana, A, Ara·jo de Souza Franco, G, STrgio de Oliveira, P and Murphy, B, 2013. TankCell flotation at SamarcoÆs Germano concentrators, in Proceedings Iron Ore 2013 , pp 441-444 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

The Ekati Diamond Mine is located on permafrost terrain in CanadaÆs Northwest Territories. The mine rock consists of: diamond-bearing and barren kimberlite; and surrounding waste rock such as granite. The kimberlite occurs in several vertical æpipesÆ that are, or will be, mined using open pits. Early predictions of drainage chemistry at Ekati identified the potential for ARD due to sulfide oxidation from both waste rock and kimberlite. This was surprising for the kimberlite, because neutralisation potentials (NP) are typically hundreds of kg CaCO3 equivalent/t. However, subsequent testwork showed that substantial portions of the NP ædisappearedÆ quickly, apparently due to the unusual non-carbonate mineralogy. In any case, additional predictive work concluded much of the rock was benign and there would be no ARD. Shortly after mining started, ARD appeared from both the waste rock and kimberlite, although a few years passed before the company and its consultants recognised that at least some of the acidic water was ARD. Numerous other processes have been put forward as possible explanations for the remaining acidic drainage, although none have been either confirmed or eliminated. Because: the causes of the ARD and acidity are not known; no causes have been eliminated and more have been added; drainage chemistry was not predicted accurately; and future mining will encounter similar rock. I believe the Ekati Diamond Mine needs high-level assistance to understand current chemistry and to avoid problems with future drainage. Organisations like INAP, MEND3, and universities could provide this assistance.

Jan 1, 2003

By S Jackson, I Arbuthnot

The use of High Rate Thickeners has gained wide acceptance in the mineral treatment industries. The design of these units is characterized by an efficient deaeration and flocculation chamber, and introduction of the flocculated feed solids into a preformed floc bed zone. By these means the settling process is accelerated and consequently High Rate Thickeners achieve a significantly higher throughput per unit area than conventional thickeners.   The object of a control system on a High Rate Thickener (HRT), as on a conventional thickener, is to obtain the required underflow density and overflow clarity at all feed conditions. The feed conditions which may vary include volumetric and mass feed rate, pulp density, particle size and particle type. A conventional thickener has a large volume and cross sectional area, and changes in performance occur slowly û the operator has time to observe and react to these changes to maintain control. On a HRT, there is a much reduced residence time and therefore control parameters need to be reset more frequently. Although manual control is possible, the use of automatic control systems is therefore desirable to avoid excessive operator attention, while optimizing control of density and clarity. Automatic control of a conventional thickener is usually achieved by an underflow density loop which regulates the rate of withdrawal of underflow. A turbidity meter is sometimes used to measure overflow clarity and regulate the addition of a coagulant or polymer flocculant. These measures are not adequate on a HRT, because they would not give optimum control and could lead to excessive flocculant use. To achieve optimum operation in a HRT, the floc bed level should be maintained above the feed inlet point in the thickener. This bed level has become the key variable around which most control systems have been designed. However, a number of problems have occurred which has resulted in poor control, or only partial control of thickener performance. We will describe some of these problems, and a solution which is simple and effective.

Jan 1, 1990

By A P. Brown

Comparison of legal permits required for mining (as opposed to prospecting or exploration) inNew Zealand, under the Mining Act 1971 and the Resource Management Act/Crown Minerals Act 1991. Mining generally receives the same treatment as any other industrial or commercial activity.

Jan 1, 1995

Sulfidisation Promotion Effect of Ammonium Sulfate on the Flotation of Copper Oxide Ores

Sep 13, 2010

By Innes J. A

The structural variations occurring in pellets of finely divided mixtures of iron ore and coke breeze, metallized by firing at elevated temperatures, have been examined microscopically. For any given pellet composition, time and temperature are the two most important factors in determining the development of the bonding processes.INTRODUCTIONThe success of sintering and pelletizing processes in the agglomeration of fine iron ores for blast furnace use has brought about rapid changes in thinking relative to methods of preparing furnace burdens. Increases in productivity with the use of sinter emphasize the advantages of a stable, uniformly sized furnace feed. Current practice is to produce a self-fluxing sinter containing most of the lime requirements of the furnace incorporated as a stable medium (Figgis and Charker, 1962). The elimination of fine material from the burden allows greater stack permeability and smoother operation.Sintering and pelletizing of iron ores with or without the incorporation of fluxing compounds has conditioned operators to the extent that it is now considered possible that all components of the burden may eventually be beneficiated in one form or another. Investigations are in hand to improve the quality and sizing of coke, which occupies the major part of the burden volume (Callcott, Innes and Brown, 1961; Innes, Gregory and Worner, 1963). Interest is also being revived in methods of pre-reducing iron ores prior to charging to the furnace (Hansen, Melcher and Fine, 1961). Recent experiments in a small experimental blast furnace (Melcher, 1963) show that charging of semi-metallized pellets can give rise to a production increase of 55 per cent...

Jan 1, 1963

By B Chi, A Mahanta, R A. M Maddever, O Dominguez

BHP Billiton, in collaboration with Sodern and CSIRO, has developed a downhole logging tool for measuring geochemistry in situ. The FastGradeTM 100 (alternatively, FG100), exploits pulsed fast and thermal neutron analysis (PFTNA) to analyse the rock. This method is based on the detection and measurement of characteristic gamma rays emitted from isotopes in the material that become briefly radioactive when they are bombarded with neutrons. The tool outputs raw spectra arising from three types of neutron interaction, namely, inelastic scattering, neutron capture and neutron activation, which occur in successive time-windows (Smith et al, 2015). The spectra contain peaks at specific energies that are characteristic of the different elements interacting with the neutrons, the gamma count of which is related to elemental concentration. BHP Billiton uses in-house data processing software to convert the measured spectra to elemental concentrations.Much work has been done to understand the tool response under a wide variety of environmental and operating conditions, including logging speed, borehole rugosity, the presence of cavities, water etc. Effort has also been directed at understanding and quantifying the current sources of error in our conventional assays due to sample collection, preparation, and laboratory instrumentation in order to use this information as a baseline to compare against the FastGradeTM 100 results.To date, the FastGradeTM 100 primary use has been as a verification tool (JORC, 2012). However, beyond this, it has considerable potential to improve productivity in both exploration and production environments due to its ability to provide geologists with assay results soon after a hole is drilled.This paper presents initial test work and tool performance, including accuracy and precision under various conditions. Results are illustrated by comparing tool measurements to assays from laboratory samples collected from both reverse circulation and diamond-drilled holes.CITATION:Chi, B, Maddever, R A M, Mahanta, A and Dominguez, O, 2017. Near real-time assay with downhole assay tool (FastGrade™ 100), in Proceedings Eighth World Conference on Sampling and Blending , pp 137–144 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017