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Tried, Tested and Proven - 300 m3 Flotation Cells in Operation

Sep 13, 2010

The Hyde-Macraes Shear Zone (HMSZ) is low angle, duplex thrust system that has developed in a graphitic pelite schist within the Otago schist belt, New Zealand . At Round Hill lateral ramps have developed parallel to the movement direction between+ the footwall and hangingwall shears. These structures exhibit normal oblique-slip displacement which has been an important mechanism for creating space in an otherwise compressional system. Gold-bearing quartz veins were emplaced along the boundary shears and lateral ramps during thrusting. Gold within the lateral ramps is coarse (up to 300 microns) however hanging wall cataclasite development in the boundary shears after the gold was deposited has reduced the grainzise of most of the gold to less than one micron. This bimodal gold distribution has metallurgical implications with respect to the maximisation of gold recovery at Macraes.

Jan 1, 1993

By S Reid, W Chen, T J. Donohue, A Katterfeld

The use of discrete element modelling (DEM) is widespread in the materials handling field, and is used for many applications. One of the important limitations in using DEM is the number of particles that can be modelled, with this limitation often resulting in increasing the minimum particle size in the simulation. This restriction on minimum particle size is usually accommodated in the calibration process where the parameters in the simulation are chosen in such a way as to reflect the presence of smaller sized particles, and in typical applications such as transfer chutes this is standard practice. However, in the application of vibrating screens the inclusion of the ‘fines’ is critically important due to their influence on the screening efficiency. In reality, the presence of fines reduces the screening efficiency for a number of reasons; however, the main mechanism that will be addressed in this study is the effect of adhering fines. This is where the fines adhere to the larger particles and are carried over into the lump stream. The approach for this study will be to firstly consider the relatively simple mechanical sieving process used in the determination of particle size distribution, and then this will be expanded to consider the application of vibrating screens.CITATION:Donohue, T J, Chen, W, Katterfeld, A and Reid, S, 2017. Addressing the challenges associated with the modelling of iron ore in vibrating screens, in Proceedings Iron Ore 2017, pp 155–160 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By P Lotz

With the recent increase in environmental awareness, gold mining companies are fast becoming signatories of the International Cyanide Management Code (ICMI, 2007). The objective of the Code is to improve the management of cyanide used in gold mining and to assist in the protection of human health and the reduction of environmental impacts associated with the use of cyanide. In particular the code specifies the following cyanide concentration limits: 50 ppm WAD cyanide in a tailings storage facility, 0.5 ppm WAD cyanide for effluents, and 0.022 ppm free cyanide or 0.022 ppm WAD cyanide as surrogate in the post mixing zone of river discharge. Weak acid dissociable (WAD) cyanide refers to those cyanide species liberated at a moderate pH of 4.5, such as HCN(aq) and CN-, and the majority of Zn, Cd, Cu, Ni and Ag complexes with low dissociation constants. It is potentially toxic to humans and animals. Gold plants using cyanide should ideally measure WAD cyanide online and destroy WAD cyanide in excess of the applicable limits to ensure compliance with the Code. Mintek has recently developed an online WAD cyanide analyser (WAD Cynoprobe). The WAD cyanide analysis technique is based on the use of a ligand exchange reagent that liberates WAD cyanide bound to metals such as Zn, Cd, Cu, Ni and Ag. The ligand exchange reaction is represented by the following chemical equation: Metal(CN)X + yLigand ↔ Metal(Ligand)y + xCN- The plant filtrate is treated with a ligand exchange reagent, to liberate WAD cyanide, before measuring the free cyanide concentration via amperometry. The WAD Cynoprobe measures both free and WAD cyanide concentration. Its fast analysis time, approximately five minutes, makes it suitable for use in the control and optimisation of the cyanide destruction and recovery process. The instrument has proven accurate and reliable in the analysis of synthetic copper, nickel and zinc cyanide solutions made up in the laboratory as well as under industrial gold plant conditions during various trials. The WAD Cynoprobe has gained widespread commercial acceptance and is currently implemented on nine gold plants around the world.

Jan 1, 2007

The Influence of Particle Shape in Rock Fracture

Sep 13, 2010

By S Jokanovic

At New Zealand Steel MiningÆs Waikato North Head operation a Bucket Wheel Excavator û shiftable conveyor mining system is used to excavate titanomagnetite bearing sand and clay. The system utilises two Bucket Wheel Excavators and two Beltwagons with a two shiftable bench conveyors and two common trunk conveyors to deliver material to a processing plant. The original system was commissioned in 1984 as a high capacity, low cost method of excavating. In 1996 a second Beltwagon was purchased, increasing the flexibility of the mining system.

Jan 1, 2002

The early development patterns of both Australia and New Zealand were substantially in parallel and both were heavily indebted to gold mining for, providing the stimulus to growth. However, since the mining boom, of 1895 - 1899, the mining sector in New Zealand has progressively declined, while in Australia it has assumed an increasing importance in the economy. The continued dominance of minerals in Australian trade, and the fact that eight out of the top ten companies in Australia are directly involved in mineral exploration and production, has strongly influenced government and public attitude's to the minerals sector. Although the legal framework of mining and exploration Acts and Regulations are similar it is in, the method of administration, particularly in regard to exploration and prospecting licences, that the gulf across, the Tasman is apparent. Despite the relative ease of application and granting of licences in Australia, in the more settled south eastern part of the continent we are finding more and more land is being zoned unavailable for exploration. In the remote areas, the Aboriginals now control nearly ten per cent of the land area of Australia, virtually with drawing that portion from exploration. The concept of 'Australianisation' has softened a hardening attitude against foreign investment in mining on the part of the bureaucracy. This anti-mining attitude is fortunately, not shared by the public, and we can but hope that the will of the Australian people can filter through to our masters in Canberra, and ease the rapid increase in the number of regulatory bodies which does so much to inhibit the normal conduct of business. The delays caused by interminable hearings and committee investigations all cost money. This cost can only rebound back on the end consumer, who after all is a voter.

Jan 1, 1982

By H J. Stedman

A Transient Electromagnetic (TEM) geophysical survey was trialled in Bowen Basin Permian coal measures overprinted by Cretaceous intrusion. The trial’s intention was to compare whether TEM could assess residual coal more accurately and economically than drilling.TEM results were promising but had limitations. TEM did not compare to drilling for defining coal thickness or relative level definition. However, TEM resolved conductive anomalies laterally; providing a qualitative picture of remnant coal.Three material types and associated conductivities occur within the trial area: overburden (sandstone/siltstone), intrusive sills and heat affected coal.Ground conductivity was analysed by measuring decay of residual current within the TEM loop. Fast decay related to resistive overburden and intrusion, attenuated decay related to conductive coal.Generally speaking, carbon content governs coal resistivity where good quality, low ash, bright coal is more resistive relative to dull, high ash coal. Though in the trial area, relative to intrusion and overburden, coal was found to be the most conductive of the three materials.By modelling conductive anomalies, a general picture emerged of remnant coal regions. Subsequent highwall exposure reconciled with conductive TEM anomalies.CITATION:Stedman, H J, 2017. Findings from a transient electromagnetic trial for heat-affected coal, in Proceedings Tenth International Mining Geology Conference 2017, pp 233–238 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

Comparing Energy Efficiency of Multi-Pass High Pressure Grinding Roll (HPGR) Circuits With increased emphasis on reducing costs and carbon emissions in mineral processing, it is becoming essential to employ the most efficient comminution devices and to use them to maximum effect. High pressure grinding rolls (HPGR) are considered highly efficient compared with other devices, however their relative efficiency in multi-HPGR circuits is less well understood. A series of comminution tests was carried out to evaluate three multi-pass HPGR circuits and a jaw crusher-ball mill circuit. Combinations of HPGR units (1.0 m and 0.25 m diameter), jaw crushers and Bond ball mills were used to grind a 32 mm top size porphyry copper feed (BBWI = 12.1) to a product P80 size of about 150 ¦m. Up to three passes of HPGR were used in each circuit, with energy measurement and size analysis at each point in the comminution process. The energy efficiencies of individual comminution stages and of the overall circuits were quantified and evaluated using three different approaches. The operating work index method for comparing comminution energy efficiency underestimated HPGR performance due to the large amount of fines generated. The -75 ¦m efficiency factor and F50/P50 reduction ratio interpolation methods both give a fairer measure because they better take into account the amount of fines generated by HPGR. The results show that the relative comminution efficiencies of the three multi-pass HPGR circuits tested differ by as much as 22%, providing insights as how to best employ HPGR in a comminution circuit. The most energy efficient of the circuits tested was a three-pass HPGR circuit with a 1.0 m diameter roll on the first pass in closed circuit with an 8 mm screen followed by a second and third pass in a 0.25 m roll.

Sep 13, 2010

The sedimentary basins of this region developed in the collision zone of thePacific Ocean plate and the continent. Stresses were transmitted thorough wedge-like lithospheric blocks, such as the Okotsk Sea, East Kamchatka, Aleutian and other smaller blocks. Compression and inversion were more active at the boundaries: ***INSERT EQ*** and ***INSERT EQ*** in places. Tension, rifting and the increase in the rate of sedimentation were marked in P1-2, P3, N12, and also in N2 û Q in places. Structural plan changes of the sedimentary basins and possible oil, gas and fluid migration occurred more actively at the boundaries: ***INSERT EQ***.

Jan 1, 1995

At a regional scale, the Otago Schist has been divided into textural zones, metamorphic zones, structural transposition zones, and terranes and lithologic associations. Each of these subdivisions reveals aspects of the internal structure of the lithologically monotonous Otago Schist but, to date, a map of the schist derived directly from structural data has not been made. In the present study, digitised structural data from the QMAP GIS were used to make a form line map of Schist foliation which, in turn (and using certain non-unique guiding assumptions), was used to construct a provisional foliation thickness map of the Otago Schist. Contours of dominant foliation (Sp) thickness have been drawn from 4 kIn above to 16 km below the reference level of the Caples-Torlesse terrane boundary in the schist structural pile. A recent revision of the Otago Schist textural zone classification has shown that the grain size of metamorphic white micas increases progressively with textural grade. There also appears to be a correlation between schist mica grain size and foliation thickness. Using mica grain size, it may eventually be feasible to establish the vertical structural position of samples in greenschist facies parts of the schist pile to a precision of ¦ 1 km or better, even if they are in inliers or fault-bounded blocks. Foliation thickness and mica grain size are thus potentially useful tools for research and exploration in the Otago Schist in that they assist with structural interpolation and extrapolation. Even at this early stage of application they can be used to provide hitherto unobtainable, semi-quantitative estimates of displacement on Mesozoic and Cenozoic faults and folds.  

Jan 1, 2001

Dynamics of Three Phase Contact Line Motion in Liquid-Liquid-Solid Systems - Impact of Surface Roughness

Sep 13, 2010

By C A. Feebrey, R A. Duncan

The Ebor Volcano in north eastern New South Wales is an eroded example of a central-type intraplate volcanic-intrusive complex. It is of Miocene age (19 - 20 Ma) and has similarities to other central-type volcanoes in eastern Australia which may represent manifestations of sub-lithospheric hotspot activity. Thick lava flows are exposed around the Great Escarpment and are dominated by a tholeiitic basaltic suite, ranging from ol-tholeiite to qz-tholeiite to icelandite with ages of 19.2 - 19.6 Ma. On its western edge, the tholeiitic lava suite probably overlies remnants of basanite flows belonging to the Eocene (~48 Ma) Doughboy province, but elsewhere, minor alkaline basaltic lavas may be coeval with the tholeiitic suite. Several felsic bodies were emplaced into the volcano at ~19.0 - 19.2 Ma and include subalkaline and peralkaline types. The Crescent Complex is a Miocene-age, strongly differentiated mafic to felsic intrusion in basement rocks and centrally located in pre-erosion reconstructions of the Ebor Volcano. It is interpreted to be a major feeder for the tholeiitic lavas based on age and composition. Evolution of the dominant tholeiitic suite proceeded from a parental ol-tholeiite magma, through qz-tholeiite, icelandite and small volumes of felsic rocks by fractionation of plagioclase, olivine, clinopyroxene and titanomagnetite, accompanied by enrichmentof SiO2, SFeOlMgO, alkalies and HFSE.

Jan 1, 1995

Comparison of Discretised Population Balance (DPB) and Finite Element Method (FEM) Methodologies for Modelling Batch Gibbsite Precipitation

Sep 13, 2010

The New Zealand Steel Ironsand Slurry Pipeline was successfully commissioned in February 1986. The project includes 18 km of high pressure, polyurethane lined buried pipe. McConnell Dowell Constructors Limited has developed a coupling which has allowed this pipeline to be fully welded. The design and development of the coupling and its application on this project is discussed.

Jan 1, 1986

By J J. Culberson

The past 10 years has seen use of computers become widespread in the mining/exploration industry (including coal, precious and base metals, oil/gas and industrial minerals). This paper will concentrate on the use of computers as a tool to provide technical solutions (including data management, mine planning and operational support) to this industry rather than the use of computers to aid accounting, maintenance and inventory (æcommercialÆ) applications. This paper will review the processes and benefits of the use of computers in mining. We then review the use of technical computing locally here in New Zealand and see what business benefits local users have found from using computers in mining. We have, in research for this paper, spoken with mining software vendors from around the world to find out what is currently the æbest practiceÆ in the industry. The paper will then list what those vendors see as the ultimate improvement on the cards for the future of mining software.

Jan 1, 2000

By M Bourke

Modern computers and software provide powerful tools for the geologist to construct reliable models of geological resources, and the mining engineer to produce accurate and workable mine plans. Over the years many people have developed a phobia of computers, especially for geological analysis, modelling and mine planning. This phobia is often caused by a lack of knowledge, poor training or a bad experience. The adoption however of computers for geological modelling and mine planning is now becoming mainstream. With the correct training, a good understanding of input data, and detailed knowledge of the required results, the phobia can safely be overcome to provide mining operations with increased productivity.

Jan 1, 1999

Triboelectrostatic Producing Ultra-Clean Coal

Sep 13, 2010

By K Faure

At Sams Creek a gold-bearing, peralkaline granite pophyry dike intrudes Ordovician-Silurian metapelite and quartzite. These metasedimentary rocks have undergone three phases of folding: a first phase of recumbent folds (F1), a second phase (F2) of northerly-trending inclined folds with a prominent crenulation cleavage, and a third phase (F3) of steeply plunging folds. The granite porphyry dike has a thickness of up to 40 m and intrudes thin lamprophyre dikes along its contacts. Deflection of the crenulation cleavage around the granite dike, shearing within the dike and its sinuous outcrop pattern indicate that the granite dike has been deformed during F2 and F3. The granite has been hydrothermally altered, with a first stage of magnetite-ankerite alteration. This first stage is cut by a second stage of quartz-pyrite veins and a third stage of sulphide, quartz and ankerite veins, accompanied by pervasive silicification represented by quartz-perthite-albite-rutile¦pyrite-ankerite-sericite assemblages. Lamprophyre is altered to an ankerite-chlorite-sericite assemblage. The sulphide veins are composed of arsenopyrite + pyrite ¦ gold ¦ galena ¦ sphalerite ¦ chalcopyrite ¦ pyrrhotite. The altered granite and the veins have been deformed and recrystallised. The competent sulphide minerals pyrite and arsenopyrite are fractured and brecciated, with fractures locally filled by galena, a ductile sulphide mineral. Vein quartz shows local cataclastic and mortar textures and develops pressure shadows around arsenopyrite. Alteration and mineralisation are confined to the granite porphyry and adjacent lamprophyre. These features together with the style of veining and the sulphide mineralogy indicate that the mineralisation was formed from a magmatichydrothermal fluid that was sourced from the granite. Oxygen, carbon and sulphur isotope values of the vein minerals (quartz, ankerite and sulphides) are also consistent with a magmatic source.

Jan 1, 2003

By A S. Derrington

There are several long-standing rules of thumb that are often quoted in mine ventilation studies. They include airway ‘carrying velocities’ and the critical upcast air velocity range that must be avoided to prevent a water blanket forming. Quoting these rules of thumb may lend an air of legitimacy to a ventilation design, and allow the design engineer to avoid having to study a problem from first principles. But how valid are these shortcuts in today’s rapidly changing world? This paper summarises research into the genesis of several commonly quoted rules of thumb. It finds that they were very specific to the local conditions, practices and economics at the time they were developed. It also presents examples where applying these rules of thumb outside of their original context can lead to unexpected and erroneous results.CITATION:Derrington, A S, 2017. Ventilation rules of thumb – friend or foe? Focusing on design upcast air velocities for shafts and raise bores, in Proceedings Australian Mine Vent Conference 2017, pp 253–260 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017