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Predicting Water Recovery from Flotation Cells

Sep 13, 2010

By Warren L. J

The effectiveness of shear-flocculation as a method for upgrading simple mixtures of ultrafine (1-11 \lm) scheelite and garnet was evaluated. Statistical methods were used in the design and analysis of the main test program.The stirrer speed, stirring time, and initial weight ratio were all found to have significant effects on both the recovery and grade of the floes produced. The particle sizes also had an effect on the final grade. There were several important interactions between factors which also affected the results. Optimum conditions for shear-flocculation were established, and under these conditions about 80 per cent of the scheelite could be recovered at a grade which depended on the composition of the starting mixture. Starting with mixtures containing 10 and 50 per cent scheelite, the best final grades were between 20 and 50 per cent and between 70 and 90 per cent respectively, the actual value depending on the particular combination of particle sizes.

Jan 1, 1977

The Fosterville Goldfield has a modest past production (0.3 Moz), but is now emerging as a significant goldfield (2.6 Moz resources, including 1.1 Moz reserves) with implications for exploration within the orogenic gold provinces of the Lachlan Fold Belt in Australia and the Buller Terrane on the West Coast of New Zealand. Fosterville is located 20 km east of the 22 Moz Bendigo Goldfield and is geologically similar to other Victorian goldfields, however the nature of the gold mineralisation differs significantly. Unlike other Victorian goldfields there is no primary free gold at Fosterville. The gold occurs in as sub-SEM resolution particles, in fine grained arsenopyrite and pyrite crystals disseminated through the wall rocks in fault controlled quartz-carbonate vein stockworks. The Fosterville Goldfield comprises several subparallel fault systems striking 340¦ over an exposed strike length of 28 km. The Fosterville Fault system comprises the west dipping (~75¦), reverse Fosterville Fault and several less steeply west dipping splay faults formed in the footwall. The splay faults extend through east dipping beds from the Fosterville Fault across a syncline hinge into stratigraphically controlled positions on the west dipping limb of the syncline. The predominant control on gold mineralisation is the intersection of the bedding on the east dipping limb of the syncline and faulting which, is in turn controlled by the orientation of bedding in the west dipping limb of the syncline. The mineralised shoots are thus subparallel to the plunge of the syncline and show a plunge reversal about a culmination in the footwall syncline. This provides a very powerful exploration tool with bedding û cleavage intersection lineations measured in outcrop and oriented core indicating the plunge of mineralisation. Mineralisation is also, albeit less commonly, controlled by local variations in strike and dip of the host fault and at metre scale by host lithology. As the faults and mineralisation are stratigraphically controlled, detailed stratigraphic interpretations are essential to provide control on structural interpretations for resource modelling. Compared to other Victorian goldfields, the Fosterville Goldfield formed later (385 Ma to 360 Ma cf 440 Ma), at lower temperatures and at shallower depths (fluid inclusion studies of Au associated veins suggest vein formation at ~270¦C (range 140¦C to 385¦C) and at depths of 2.6 - 5.7 km).

Jan 1, 2005

The C.S.A. copper-lead-zinc mine, located 7 miles north of Cobar in central-western New South Wales, is the largest known mineral ocurrence in the Cobar mining field. The generally discordant orebodies occur within a strike width of 600 ft and an overall strike length of 1200 ft. They are enclosed by the steeply westdipping, west-facing sediments of the Cobar Group, and comprise lenticular steeply north-pitching and eastdipping zones of sulphide mineralization which range in composition from massive pyrite-sphalerite-pyrrhotitegalena to less massive pyrite-pyrrhotite-chalcopyrite varieties.The thinly bedded siltstones, shales, and greywackes enclosing the mineralization appear to have derived some of their constituents from volcanic sources. They have been metamorphosed to the greenschist facies of regional metamorphism. At least two stages of deformation and folding have occurred. The first stage folded the rocks on a south pitching fold axis into their present configuration, and superimposed a strong axial plane cleavage which subsequently guided the emplacement of the mineralization. The second stage of deformation is considered to have controlled the zonal distribution of the orebodies.

Jan 1, 1970

Who Macraes Mining Company Limited is can be summed up by the following statements: +         We have been New Zealand's largest gold producer for seven years +         We have one of the lowest market capitalisation per reserve ounce of the gold producers in the  Australian Gold Index +         We have a resource finding cost of less than NZ$l0 per ounce +         We have a large land bank with proven reserves +         We have an Operating Cash Margin of approximately NZ$200 per ounce +         We have reduced our Dry Milled Tonne Cost by 34% since 1992   Our Mission is to continually grow our gold business, through maximising cashflow and focusing on our value drivers being: +         Increasing reserves +         Increasing cash operating margins +         Increasing production   The real challenge is the reduction of operating costs and the optimisation of revenue, particularly in the current gold price environment.   The Company has as at 31 December 1996 total mineral resources of 6.1 million ounces and reserves of 3.4 million ounces. This together with our current cash position of approximately NZ$15 million and strong hedging book of approximately 800,000 ounces places the Company on a sound financial footing whilst positioning itself to aggressively pursue its growth strategy when gold price and market conditions improve.

Jan 1, 1997

Increasing demands on quality of metallurgical grade alumina and for lower production costs led to the development of a new fluid bed calcining process. The process, jointly developed in Germany by Vereinigte Aluminium Werke A. G. and Lurgi Gesellschaften m.b.H., takes advantage of modern chemical engineering methods such as counter-current flow of combustion air and solids, direct heat-exchange between combustion air and fine solids, and near stoichiometric combustion of oil in a fluid bed. Using a two-stage Venturi-type suspension preheater for heat-recovery from combustion flue-gases, the circulating fluid bed technique with internal oil combustion at 220°F for the calcining step and a five-stage fluidized bed cooler for heat-recovery from calcines, the process gives an outstanding heat-efficiency. In a first industrial plant for 560 sh. tons/day of alumina heat consumption figures of less than 1·400 B.T.U./lb Al203 g were achieved.

Jan 1, 1972

By C M. Hall

We report 40Ar/39Ar ages for adularia and illite from veins and wall rocks at the Waihi and Favona deposits, in the Waihi district. One sample of vein adularia from the Favona deposit yielded a plateau age of 6.04 ¦ 0.06 (la) Ma, and two samples of vein adularia from the Waihi deposit yielded plateau ages of 6.17 ¦ 0.03 and 6.17 ¦ 0.09 Ma. Two samples of wall rock adularia from the Waihi deposit yielded plateau ages of 6.07 ¦ 0.06 and 6.08 ¦ 0.03 Ma. Adularia ages overlap at the 2s level, and we do not consider them to be significantly different. Two samples of illite from wall rocks at Favona have total gas ages of 5.66 ¦ 0.04 and 5.65 ¦ 0.04 Ma, and retention ages of 6.57 ¦ 0.04 and 6.61 ¦ 0.04 Ma, whereas one sample of vein illite yielded a total gas age of 5.29 ¦ 0.17 Ma, and a retention age of 6.26 ¦ 0.19 Ma. The total gas ages of illite are minimum ages that are equivalent to conventional K/Ar analyses, whereas retention ages of illite are maximum ages. Although interpretation of the illite data is complicated, the adularia results strongly suggest that the Waihi and Favona deposits formed contemporaneously in the same fossil geothermal system at 6.0 to 6.1 Ma.

Jan 1, 2003

By Moinpour M

The kinetics of reduction of copper (cuprous) sulphide with CO-CO2-He gas mixtures, using an excess of CaO(s) as a sulphur-scavenging substance were investigated in the temperature range 855° - 950°C by a thermogravimetric method. Several gas compositions were employed at each temperature. Potential carbon deposition was overcome by preheating the reducing gas mixture. The phase-composition and the morphology of partially reactedsamples were analysed by a SEMlEDAX unit. The reduction rates showed strong dependence on the bulk gas compositions (CO, CO2) and, in most cases, the rate declined with rising temperature. The rate-controlling step appears to be the diffusion of CO2 gaseous species through the micropores of the CaS(s) - product layer which builds up around the CaOcore.

Jan 1, 1989

By Dunlop GA

Pilot Plant confirmatory testing of the treatment route developed in the Metallurgical Laboratory is an essential factor in the development of complex ore bodies. Objectives should be well defined to permit the efficient planning and cost effective operation of the pilot plant project. The primary objective for the pilot plant should be to confirm the viability of the developed flowsheet on a continuous basis, examining only major variables such as ore types, quantum changes in grind, comparison between bulk and sequential flotation circuits, use of flotation columns, evaluation of autogenous grinding and production of samples of concentrates for market evaluation. Secondary objectives may include the collection of engineering design data and the production of a comprehensive report to Bankable Document standards to provide technical support for capital financing. The complexity of the ore body and the scale of the final operating project together with the pilot plant objectives will determine the extent of the pilot plant operations. The level of expenditure associated with a pilot plant can vary, in total cost and as a percentage of the total development capital investment required to take the prospect from exploration to a producing mine. Factors contributing to expenditure are discussed. Associated with cost considerations is the level of confidence mining company investors can have that their capital investment will return dividends.

Jan 1, 1990

By Carras S, Kelsey P, Caccetta L

An important problem in open pit mine planning is that of detennining the optimum ultimate pit limits of the mine. These limits are that contour which is the result of extracting the volume of material which provides the total maximum profit while satisfying certain practical operational requirements such as safe wall slopes. The determination of the optimum pit contour provides information that is essential in the evaluation of the economic potential of the mineral deposit. A number of optimisation techniques are available for determining this contour with the Lerchs-Grossman and the Network Flow methods being the most favoured. Unfortunately, direct application of these techniques to large ore-bodies may cause considerable difficulties because of the computational time and storage requirements. In this paper, we present a strategy for resolving these problems, and the associated pit design software PITOPTIM (incorporating a fast network flow technique) and a data reducer, BOUND. The results presented highlight the speed and power of the software package rivalling the popular Lerchs-Grossman technique. An application of the software for a sensitivity analysis is also presented and discussed.

Jan 1, 1991

From March to May of 1963, the Bureau of Mineral Resources carried out an experimental aeromagnetic survey at Cobar, New South Wales, to field test a proton-precession magnetometer installation in the Cessna aircraft VH-GEO. The Cobar area was chosen as considerable information was already held on the Earth's magnetic field there, which was known to provide a range of anomalous areas that are not excessively disturbed.A procedure for survey flying and methods for processing data were developed during the survey. Contour maps of the aeromagnetic results were produced in the field. The experimental survey was successful in outlining magnetic anomalies in detail.INTRODUCTIONSince 1951 the Bureau of Mineral Resources, Geology and Geophysics (B.M.R.) has carried out an airborne magnetometer exploration programme with DC.3 aircraft carrying fluxgate magnetometer equipment. Recently a proton-precession magnetometer was developed by the Design and Development Group of the B.M.R. for observatory use. One unit modified for airborne use was installed in the Cessna light aircraft, VH-GEO. The Cessna was modified structurally to take the magnetometer, associated bird, and winch gear.The proton-precession magnetometer has many good features.1. It utilises the transistor and associated solid-state devices in its electronics, and hence is light and small.This is the basic feature allowing its installation in a light aircraft. The transistor circuits have a high reliability factor and owing to the card sub-unit...

Jan 1, 1964

Rheological Behaviour of Clay-Rich Gangue Mineral Dispersions During Hydrometallurgical Treatment Alumino-silicate minerals invariable may present an intractable challenge in hydrometallurgical operations employed in low grade nickel, copper and gold ore leaching or high level nuclear waste (HLNW) processing. The interactions and reactivity of alumino-silicate clay gangue minerals such as muscovite/sericite, chlorite, kaolinite and smectite under acidic (eg pH <3) or alkaline (pH >13) conditions can have a striking impact on the particle interactions. These may manifest in undesirable pulp rheology, poor extraction rates and challenges in the subsequent "handleability" and solid-liquid separation processes (eg dewatering). In the present work, a review of investigations involving the interfacial chemistry, interactions and rheological behaviour of aqueous dispersions of mica-group, layered alumino-silicate clay (muscovite / sericite) and chalcocite minerals as a function of pH in the range 2 - 9 and time at 25¦C, is presented. Particle zeta potential, reflecting interfacial chemistry, indicated a strong pH-history and particle volume fraction dependency. Pristine particles' zeta potentials measured from high to low pH indicated mineral-specific isoelectric point (iep) at pH range 2 - 5. Subsequent measurements from low to high pH showed pH-history dependency with iep shift to higher pH values, the extent of which also depended upon particle volume fraction and aging time. Pulp pH-mediated particle interactions revealed by shear yield stress analysis displayed a bifurcation behaviour and good compliance with DLVO theory. The maximum pulp yield values occurred at the iep whilst weak rheology was observed where the magnitude of the particle zeta potential was greatest. The pivotal role played by both pulp chemistry and suspension conditions in regulating the particle interactions and concomitant rheological behaviour is highlighted. The implications of the findings with regards to clay-base pulps' handleability and its control during aqueous processing are discussed.  

Sep 13, 2010

The use of mining by-products for beneficial use may face approval, and acceptance barriers. This paper described the use of a sustainability framework to assess the safety, effectiveness and economic value of modified bauxite residue (Alkaloam«) for use on agricultural land in the Peel-Harvey region of Western Australia. The results indicate the merit associated with using this by-product from a safety and, private, community and environmental value perspective. They may be used to indicate the worth of pursuing any future community acceptance and agency approval process.   The use of Alkaloam« for beneficial use on agricultural land in Western Australia was first investigated over 25 years ago. Efforts to gain regulatory approval and community acceptance of Alkaloam« have had a complicated and enduring history. Understanding and assessing the value of a by-product using social and economic considerations, in conjunction with an environmental assessment, provided a more complete evaluation to that previously used.

Jun 1, 2010

In the Ngakuru area, zeolite deposits occur in late Quaternary lake sediments and ignimbrites. The deposits are associated with sinters, hydrothermal eruption breccias, and quartz-adularia altered fault breccias: all indicators of a shallow epithermal environment. Several of the deposits are adjacent to epithermal gold prospects. Zeolites are most abundant in lacustrine tuffs of the Ngakuru Formation, a 100-300 m thick sequence of siltstone, tuff, diatomite, sandstone and conglomerate. The formation overlies the Ohakuri Ignimbrite dated at c. 270 Ka, and is unconformably overlain by alluvial sands and gravels which are younger than 20 Ka. Individual zeolite deposits contain 30-80 per cent zeolite over a thickness of up to 45 m in thinly stratified tuff beds. The tuff beds are locally overlain by diatomite. The tuffs are composed mainly of glass shards and pumice clasts, with minor volcanic plagioclase, quartz and biotite crystals. Glass shards in the tuffs are replaced by the silica-rich zeolites mordenite and clinoptilolite. Amorphous silica (opal A), opal-CT, K-feldspar and smectite are also present. The distribution of the Ngakuru Formation is controlled by northeast trending normal faults, which separate it into the Ngakuru and Guthrie grabens. A silicified (quartz-adularia altered) hydrothermal breccia along one of the fault zones suggests that the faults acted as feeders for heated water that caused the deposition of the zeolite minerals. Some of the zeolite deposits are adjacent to sinters and hydrothermal eruption breccias. The location of the sinter about 20 m above one deposit indicates that the zeolites were formed at a depth of 20 to 70 m below the paleosurface. The hydrothermal eruption breccias contain clasts of altered ignimbrite, which contain geochemically anomalous gold and silver values. By analogy with their occurrence in active geothermal systems in the Taupo Volcanic Zone, mordenite and clinoptilolite in the Ngakuru deposits probably formed at temperatures of 60-150oC from near-neutral pH waters as a result of interaction with glass-rich tuff beds. The Ngakuru zeolite deposits are therefore interpreted as shallow hydrothermal alteration zones within larger epithermal gold-bearing systems.

Jan 1, 2002

By R Dunne, W McCallum

Continuous improvement might be defined as seeking incremental improvement over time through improved equipment, processes, technology and the efforts of people. Most people working in ore processing facilities embrace the general principles of continuous improvement. However, given the industry-wide issues with skilled personnel and the constantly changing environment in ore processing facilities, it is often difficult to identify improvements in a facility over a given time period. The driver for these outcomes is the use of basic principles and technology to achieve best practice targets. The process involves four stages: develop standards of practice to define best practice in specific areas; write procedures to guide the organisation towards these best practices; implement the procedures and develop a review process to provide a method of measuring performance against best practice.By reviewing performance against best practice on a regular basis, the organisation measures progress towards the best practice targets and the incremental improvement between these regular reviews is a measure of continuous improvement.This paper provides the background for developing standards of practice for metal accounting, metallurgy and metallurgical management. The paper also describes how standards of practice can be used to develop continuous improvement and the skills set of the departmentÆs leadership team.CITATION:McCallum, W and Dunne, R, 2012. Metallurgical management tools for continuous improvement, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 225-230 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By B Lance, D O’Brien

The Hidden Secret ore body is located within the Mt Charlotte underground mining system in Kalgoorlie, Western Australia. Mineralisation of the Hidden Secret ore body is lode style and therefore differs from the typical economical mineralisation mined at Mt Charlotte and consequently demanded a novel approach to the mining methodology. The ore body is lens like in shape, extending 200m along strike, 210m vertically, and dipping at 55 degrees. The lode width varies from 1.5m at the extremities to over 22m in the central zone of the ore body. Average grade is 3.4 Au grams per tonne. The initial mining methodology was Modified Avoca utilising Longhole Open Stoping with pillars, in a bottom up stoping sequence. However, as Hidden Secret became better defined and wider than initially modelled, it was identified that a high portion of gold would remain in the pillars and other mining concerns emerged such as remote backfilling large open voids and potentially unsafe vertical standoff distances between levels and wide open stopes. A re-evaluation of this method was undertaken and a new approach adapting a variation of Avoca methodology was identified to remove the rib pillars and replace them with a sill pillar separating the 4 levels into 2 distinct blocks. This new approach provided an immediate advantage by removing the bogger backfilling activity from the same level of the active stope front, enabling stope drilling and prepping to occur during the backfilling cycle. Bogging productivity has also improved as the fired ore is funnelled to the draw point by the backfill rill, significantly reducing the requirement for remote bogging thus improving bogging productivity. This mining method is currently in progress in the first of the two mining blocks and is on track to realise the targeted recovery of 7,700 ounces from the rib pillars.

Mar 15, 2021

By D Reid, A Fourie

The in-pipe treatment of slurries with polymer addition shortly prior to deposition is a noteworthy emerging technology of increasing popularity. Although polymer treatment has been shown to substantially modify and improve depositional and dewatering behaviour in a significant number of cases, the impacts of polymer treatment on geotechnical performance of tailings are less well understood. For example, certain combinations of polymer and slurry type have been shown to result in lower final densities at a given vertical effective stress. Despite these lower densities, polymer-treated tailings often exhibit peak undrained shear strengths consistent with untreated material. However, the sensitivity and/or brittleness of the material may be negatively influenced by the looser state created. Although these changes have been studied, most testing available in the literature was undertaken on relatively ‘fresh’ samples of polymer-treated material. However, significant shear may occur following treatment and prior to the commencement of settling and self-weight consolidation as the material moves down the beach.To study the effects of shearing on the subsequent performance of polymer-treated tailings, a test program consisting of consolidation, triaxial and direct simple shear tests was undertaken on presheared polymer-treated material. Materials used were identical to those used in previously published studies on the impacts of polymer treatment in a ‘fresh’ condition. Shearing of the polymer-treated material generally appeared to lessen the impacts of the polymer treatment process. However, the behaviour of the material when sheared indicated that the polymer was still impacting the behaviour of the material in some respects. The results indicate the importance of the consideration of shearing on material behaviour when planning and designing a tailings deposit where polymer treatment is to be implemented.CITATION:Reid, D and Fourie, A, 2015. Effects of shear on the behaviour of polymer-treated slurries, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 215–224 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By D J. Brake

There has been a strong trend over the past decade in hard rock mines towards the use of very high powered auxiliary (or secondary) fans; in many mines, the installed power for the secondary ventilation system now exceeds that of the primary ventilation system. This also reflects the trend to use two-stage auxiliary fans pushing air into a single ‘trunk’ duct that in turn splits into multiple branches with multiple outlets feeding multiple workplaces. This often produces a poor result in terms of face flows due to the high resistance, high leakage and badly managed duct outlets, as well as high fan capital and operating (power) costs, which in turn also results in a higher cost for the underground power reticulation/distribution systems. This paper explores the reasons why this trend exists and what ventilation practitioners can do to utilise less expensive systems that simultaneously deliver better workplace conditions. It includes a case study.CITATION:Brake, D J, 2017. Auxiliary ventilation design – why and how mines waste so much power on inferior systems, in Proceedings Australian Mine Vent Conference 2017, pp 27–34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By A Hatt

This paper presents a case study of characterisation work undertaken at a greenfield exploration project to provide engineering and OH&S inputs for the design of a ventilation system. The paper discusses how comprehensive early characterisation of the ambient surface and underground environment including aspects related to heat, dusts, strata gas, and geologic/mineralogical factors enables incorporation of the right ventilation and non-ventilation controls at a study level to mitigate the risks identified.

Oct 12, 2022

Andesites are a major source of aggregate for much of the North Island of New Zealand. There are regional differences with respect to some important properties of the andesites. Some are reactive with cement and are designated as potentially deleterious or deleterious by the concrete industry. Other andesites, particularly those that are slightly altered or weathered, have rather high Plasticity or Clay Indices and perform poorly in road construction.   The performance of the andesites has been investigated and can be shown to be determined by: +        the chemistry of the rock which in turn determines the chemistry of the glass in the rock; +        the presence of large amounts of groundmass glass in the rock; and +        the nature of the superimposed alteration processes. Environment of extrusion and how rapidly the rock has been cooled or chilled are also important as they determine the fabric of the rock and how much glass will be present in the rock.   There are three main types of alteration that affect the quality of the aggregate: 1.   hydrothermal alteration, 2.   late magmatic alteration associated with the devitrification of glass, and 3.   weathering.   Each of these alteration types produces different alteration minerals. In fresh andesites the devitrification of glass has an important affect on the rockÆs properties. The Taranaki andesites are shown to have unusually (in comparison with other North Island andesites) high Na2O contents, held in the groundmass glass, which is the fundamental reason for the high alkali û silica reactivity of these andesites.

Jan 1, 2005