Search Documents

By Warren L. J

The recovery of phosphate minerals from the Mt Weld deposit by froth flotation has been studied by many researchers. Most of the flotation experiments were carried out with a tall oil fatty acid as collector and sodium silicate as dispersant and gangue depressant at pH about 10. Several rougher stages and cleaner stages and, sometimes, a desliming stage were included. The major difficulty was to reduce the Fe2O3 impurities in the concentrate to the required level. We used QEM*SEM (Quantitative Evaluation of Materials by Scanning Electron Microscopy) to provide a comprehensive and accurate mineralogical analysis of the flotation products. The analysis indicated that the Fe2O3 impurities were mainly recovered in the second concentrate, owing partly to the incomplete depression of the liberated iron oxides by the sodium silicate and partly to composite particles containing iron oxides. The selective depressing action of sodium silicate was improved by adjusting the variables such as the modulus (SiO2/Na2O), pH and time of standing of the stock sodium silicate solutions or by adding some polyvalent metal salts into sodium silicate solution. The flotation process was optimised to produce a phosphate concentrate with the required grade and recovery (38.6 per cent P2O5, 2.67 per cent Fe2O3, 13.7 for P2O5/(Fe2O3 + A1203), at P2O5 recovery of 81.5 per cent). The possibility of recovering the rare-earth phosphate, monazite, from the Mt Weld deposit by flotation was also studied.

Jan 1, 1991

By Neill T. J, Howarth D. F, Malcolm J. McPhersqn

For many years Isa Mine has seen the need for a continuous mining machine which will economically cut hard rock. Tunnel borers are unsuitable due to the size and inflexibility of the machine and the shape of excavation mined. The design of roadheader type machines will not permit the use of the necessary cutting technology. in 1983 a joint project was undertaken by The Robbins Company and Mount Isa Mines Limited to develop and to trial a machine suitable for cutting hard rock in an operating mine. The project was based on the proven technology of raiseboring applied to horizontal development. The Mobile Miner was fabricated and trialled in a disused quarry in the U.S.A. during early 1984. Following these trials, the machine was transported to Mount Isa and commenced mining in September that year. The initial duty was to continue the development of a decline commenced by conventional mining for a conveyor system to serve the deeper southern areas of the 1100 copper orebody. This system will permit direct tipping of copper ore to a new crusher complex and conveying of the - crushed ore approximately 2 kilometres to the central hoisting shaft facilities. The Robbins Mobile Miner MM120-3001 uses a vertical rotating cutting wheel mounted on a horizontal swinging boom to excavate a nominally rectangular shaped heading. The cuttings are collected on an apron and conveyed back through the machine. The resulting excavation is smooth-walled with no blasting damage to the surrounding rock. This provides a safer working environment than does conventional drill and blast development mining. Ground support requirements are considerably reduced.

Jan 1, 1986

By R O. Laidlaw, J L. Mauk

The Coeur d'Alene mining district in northern Idaho, USA is the second largest producer of silver in the world. Mesothermal silver-lead-zinc veins occur in the metasedimentary rocks of the Belt Supergroup with five main types of associated hydrothermal alteration: 1) feldspar destruction, 2) hydrothermal bleaching, 3) carbonatisation, 4) sulfidation, and 5) silicification. Hydrothermal bleaching is characterised by hematite destruction with associated siderite and quartz veins and veinlets, coarse euhedral pyrite and magnetite. Bleached zones envelop both mineralised and barren veins and extend for metres to tens of metres into the wall rocks. Carbonatisation consists of addition of siderite, which occurs as veins, veinlets, stockwork, irregular blebs or spots, and coarsely disseminated grains, depending on the relative distance from the main vein structure. Siderite envelops nearly all mineralised veins, relates to all other alteration types and extends from several metres to tens of metres into the wall rocks. Pyrite and galena alteration dominate sulfidation and are associated with some mineralised veins. Pyrite alteration strongly correlates with siderite alteration and exists in three main forms: a) very fine-grained pyrite flooding, which can extend for metres to tens of metres into wall rocks; b) coarse-grained, euhedral pyrite, which is sporadic and associated with the redox boundary in hydrothermally bleached zones; and c) small isolated zones (6 - 15 cm) of medium-grained, subhedral to euhedral pyrite associated with pervasive siderite alteration. Where present, disseminated galena extends for metres to tens of metres into the wall rocks. Silicification is characterised by veins, veinlets, stringers, irregular patches and variable hardness in siltites and commonly appears in association with hydrothermal bleaching and siderite alteration. Although related to mineralisation, silicification is sporadic and in most places a clear envelope around mineralised veins cannot be identified.

Jan 1, 2001

By K Verbeken, D Seveno, A Maslov, I Bellemans

Recycling and decarbonisation current metallurgical processes is key for our planet’s future and in both cases, digital twinning will play an important role. However, the various modelling techniques being used for digital twinning require a lot of input values on variables such as viscosities, diffusion coefficients and surface energies that need to be known as a function of temperature, atmosphere and composition, but which are not widely available, such as in databases, for molten slag phases. The need for more accurate data on physical slag properties is clear and will be extremely relevant for making more realistic and quantitative simulations. Some of these properties are difficult to determine, which is inherent to the very high pyrometallurgical temperatures. Therefore, this work focuses on some aspects related to determining electrical conductivities, viscosities and surface tensions of slags via a combined experimental-modelling method. Besides experimental work, molecular dynamics (MD) simulations can be used to investigate oxidic slag physical properties. With MD simulations, one can follow the time evolution of a system (consisting of atoms or molecules) by integrating Newton’s equation of motion. The input for an MD simulation mainly consists of a force field as well as initial positions, velocities and mass of each atom. The determination of the transport properties in existing literature of MD simulations in oxidic systems, is typically based on incorrect assumptions. For example, to determine the ionic conductivity, the frequently-used Einstein-Stokes equation fails to take into account all ionic types and neglects correlated motion. Furthermore, the viscosity determination via the Einstein-Stokes formula also assumes independent motion of the different ions. This paper gives a brief overview of the opportunities and challenges related to the use of MD simulations for oxidic slag systems.

Jun 19, 2024

By J-P Franzidis

A technique for determining the recovery of attached particles across the froth phase in flotation that relies on measuring the rate at which bubble-particle aggregates enter the froth is used to investigate the selectivity of attached particles across the froth phase. Combining these measurements with those of other techniques for determining the froth recovery of attached particles provides an insight into the different subprocesses of particle rejection in the froth phase. The results of experiments conducted in a 3 m3 Outokumpu tank cell show that the detachment of particles from aggregates in the froth phase occurs largely at the pulp-froth interface. In particular it is shown that the pulp-froth interface selectively detaches particles from aggregates according to their physical attributes.

Jan 1, 2005

In response to requests from the iron ore mining industry, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Division of Mineral Physics has developed a number of bulk analysis techniques in which analyses are obtained directly from ore samples weighing many kilograms or from ore located on conveyor belts.Because penetrating neutron and gamma radiation is used, measurements are obtained from a large volume of ore, which ensures thal the analyses are represelllative of the bulk.Two different gamma-ray techniques have been developed to measure iron ore grade. The first is based on backscallering of 60CO gamma rays, while the second involves measurement of the annihilation radiation which arises when the ore is irradiated wilh 226Ra gamma rays. Both techniques measure the iron concentration with an accuracy (1 s) of better than 0.4% Fe.A thermal-neutron irradiation technique using a 252Cf neutron source has been developed for the simultaneous determination of iron and the aluminium impurity (expressed as AI2O3) in iron ore fines on a conveyor bell. Because the conveyor speed must not exceed about 0.05 m/s, if good accuracy for AI2O3 is required, an auxiliary analysis bell is required Lo avoid inLerference with normal ore processing. Dynamic trials have demonstrated that accuracies of 0.6% Fe and 0.1% AI2O3 can be obtained.

Jan 1, 1985

By Rokot M

In a little over three years, Chevron Niugini has built up a team of relatively young, hard working men and women, mostly Papua New Guineans, who spend most of their working days out among people in the Southern Highlands and Gulf Provinces who are directly affected by the Kutubu Petroleum Development Project. These are Land and Community Relations officers, or LACROs. They take on a huge responsibility, not only representing Chevron but also being friend, advisor and negotiator, frequently dispensers of medicines, and agricultural advice and more. When things go well, others get the praise, when things go wrong, LACROs are the martyrs. Just as the geologists who locate the oil, the drillers who find it, the engineers who design the facilities, the construction gangs who build them, the landowners who claim it, and the Government who monitor it, so are the LACROs part of a team.

Jan 1, 1991

By M Hilden, K Barbosa, M Yahyaei, C Ndimande, K Runge, V Jokovic

Classification devices provide a link between comminution and flotation. Basically, it determines which particles are diverted back for additional grinding and which ones pass to downstream flotation. Therefore, the classifiers play an important role in the performance of a mineral processing circuit. Hydrocyclones are the most common classifiers used in wet grinding, despite being associated with poor classification efficiency. Hydrocyclones are widely used due to advantages related to low maintenance as well as reduced capital and operating cost. Other classifiers, such as fine screens, have much better classification efficiency compared to hydrocyclones. The major challenge of using screens in an operation, however, is their large footprint and increased maintenance requirements relative to hydrocyclones. Some researchers have demonstrated that switching from hydrocyclones to screens, as the classifier device in a ball milling circuit, resulted in a 20 per cent increase in plant throughput and significant improvements in coarse particle recovery, resulting in a 6 per cent increase in overall flotation recovery. However, it is known that these benefits of improved classification are very much ore specific, ie depending on the ore response. Therefore, there is a need to estimate the benefits of improved classification in pilot scale testing before the plant could consider the potential classifier upgrade. This paper presents the results of two pilot-scale grinding tests where the ore sample was processed using different classifiers: a traditional hydrocyclone and hybrid classification involving the use of a semi-inverted hydrocyclone followed by a screen. The size specific energy and circulating load were used to compare the performance of the grinding circuit. The grinding product was subject to mineral liberation analysis and the impact of classification efficiency on the mineral liberation is discussed in the paper.

Aug 24, 2022

During induration of iron ore pellets produced from magnetite concentrates, there are many reactions occurring simultaneously. While the magnetite is being oxidised to hematite, carbonate fluxes are being calcined, leading to the formation of complex oxides. Calcination of fluxes and the formation of calcium and magnesium ferrites and silicates during the preheat stage can influence the magnetite oxidation process. As the calcination reaction proceeds quicker than oxidation at temperatures experienced during the preheat stage (700 - 1200¦C), the bulk flow of CO2 emanating from within the pellet should disrupt the diffusion of O2 to the magnetite reaction as the gas fluxes are similar in magnitude. This increases the time required for the oxidation of the pellet. Using an infrared rapid heating furnace, experiments were performed on heating individual magnetite green balls in an air atmosphere. These experiments showed that time played an important role in the extent of oxidation and calcination and temperature significantly influenced the initial evolution of high temperature phases such as magnesioferrite, calcium ferrites and calcium silicates. Understanding the kinetics of all these reactions for a particular pellet feed, and their interaction, is important for optimising the design of the induration furnace.

Jan 1, 2005

During the past three years Lurgi's Circulating Fluid Bed (CFB) technology has been successfully applied to roasting of refractory gold ores and con- centrates. In comparison with the so-called Stationary Fluid Bed roasting systems, a considerable improvement of gold recovery, to around 95 per cent, has been demonstrated and achieved on many occasions in pilot CFB units and in commercial CFB roasting plants as well. The major reason for such improved gold recoveries is the excellent controllability of the roasting process in the CFB reactor system. Here, temperature, gas atmosphere and solids residence time are more precisely controllable at optimal values during roasting operation in order to achieve the highest possible gold recovery in the subsequent leaching process step. Further dominant benefits of CFB roasting systems are their flexibility with regard to feed material, throughput capacity, dry or slurry feed, almost unlimited oxygen enrichment, direct fuel addition and in situ capture of SO2 in the presence of limestone and dolomite. The system will accept 50 per cent turndown ratio, large variations in feed composition and particle size, as well as a variety of different fuel types. The commercial applications of CFB roasting systems for gold con- centrates have been realized so far at Fimiston, Kalgoorlie/Westem Australia and for whole ores at Cortez, Nevada/USA.

Jan 1, 1991

By Ovchinnikov YN, Novikov VS, Spirin NA, Babushkin NM, Mysik AF, Shcherbatskii VB, Kukarkin AS

Laboratory investigations were carried out to determine the resistance coefficient of the flow through beds irrigated with wetting and non-wetting liquids. A formula was obtained which may be used to evaluate the resistance of the irrigated packing. Quantitative investigations were also carried out on operating furnaces at Magnitogorsk. Continuous measurements of the lower pressure drops were made under different furnace conditions. Pressures were measured in the tuyere space and the bosh region. A significant transient behaviour of the pressure drop was observed in the irrigated zone as a function of the accumulation of the liquid phase in the bosh region as smelting progressed. Additionally, transient processes were also investigated in the upper furnace zones. The basic cause of the transient behaviour was shown to be the irregularity of burden descent caused by the casting cycle. It was shown that the rate of burden descent between consecutive casts reflects fairly accurately the accumulation and drainage of the liquid products as a result of which heat transfer, reduction and aerodynamic processes assume transient character. In practically all cases of casting a decrease in blast pressure and that over the furnace height of 0.2 kg/cm2 was observed. The analyses of radial gas composition at the stock line showed that compositional variations connected with the casting cycle are most pronounced in the central and peripheral regions, whilst in the intermediate regions the conditions are relatively stable. Calculations show that as casting progresses there is a decrease in the gas flow rate at the periphery and an increase in the centre of the furnace. The transient nature of the aerodynamic processes in packings revealed the existence of an appreciable reserve capacity. Elimination of transience was tested on the furnace at Magnitogorsk and improved operating and economical furnace parameters obtained.

Jan 1, 1975

Recovery of tin and copper from concen trates containing cassiterite, stannite and chalcopyrite was studied in laboratory-scale tests designed to simulate continuous operation of the matte fuming process in which tin is recovered as SnS fume while copper accumulates in the matte. Charges made up of 300g of mixtures of the concentrate and siliceous flux were added at a uniform rate in pelletized form to crucibles containing 300g of matte and 50g of slag (both of which were recovered from previous tests), while blowing through the matte with air or oxygen-nitrogen mixtures at a rate of 3 to 5 1/min. Accurate material balances enabled the effects of process operating conditions on tin recovery and sulfur utilization to be deter- mined. When operated correctly, the matte fuming process gave tin recoveries exceeding 90 percent in spite of wide variations in the copper content of the matte and in the operat- ing conditions. Deterioration of tin recovery was associated with undersaturation of the slag with respect to silica, and with high partial pressure of sulfur dioxide (greater than approx- imately 0.2) brought about by oxygen enrichment of the blowing air. The utilization of sulfur varied widely in low grade mattes. Copper in excess of approx- imately 10% promoted formation of SO2 by the commonly accepted reaction: FeS + 1-120 2= FeO + S02 while in copper-free and lower grade mattes a substantial fraction of the oxygen was consumed in the alternative reaction FeS + i 02 = FeO + z S2.

Jan 1, 1980

By Lee H. G, El-Rahaiby S. K

The literature relating to reduction of sulphides by carbon using lime as sulphur-absorbent is reviewed. A stage-wise thermodynamic model is employed to evaluate the practical feasibility of the direct reduction smelting of galena (PbS) concentrates with a carbon reductant in the presence of lime; a coke-rate of 65 kg/ton Pb is predicted by the model. The experimental data on the reduction of PbS:4CaO:4C mixtures under nitrogen were correlated by means of a finite difference numerical method and the values of the intrinsic rate constant I1 were derived. The results for the uncatalysed reduction are represented satisfactorily with log I1 = 1.247(±0.522) - 5540(±610)T-1.The catalysed PbS:4CaO:4C mixtures contained 2.5 wt% of ternary (K, Li, Na)2CO3 catalyst. For the catalysed reduction it was found that log I1 = 3.981 (±0.301) -7790(±353)T-1, where I1 (in both relations) is expressed in moles.(g.C.)-1.atm-1.s -I. The catalytic enhancement faclor was found to be quite large in the 1068 to 1262°K temperature range investigated here.

Jan 1, 1991

By R Valenta

Most developing projects face a range of technical and non-technical challenges, and examination of development histories can potentially provide insights into improved approaches to project development. The Kestanelik project in the Canakkale region of Western Turkey was acquired by Chesser Resources Ltd in 2008. Turkey is a significant and growing source of gold production, with sector participation by both domestic and international companies. While the broad ranges of challenges faced by developing projects is well known, there are relatively few case studies in which the range of technical, environmental, social and governance challenges are presented in a single contribution. Recent studies of undeveloped complex orebodies have particularly shown the extent to which environment, social and governance (ESG) complexities contribute to project delays and failures. The Kestanelik project faced a full range of technical and ESG complexities, and provides an illustrative example of the associated challenges. CITATION: Valenta, R, 2018. A case study of technical, social and environmental challenges for a gold project development in Western Turkey, in Proceedings Complex Orebodies Conference 2018, pp 73–74 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By C M. Sennitt, M J. Spadafora

Systematic field evaluation of known gold and clay occurrences in South Korea has led to the recognition and discovery of both high and low sulphidation gold-silver epithermal systems. These are associated with Cretaceous acid-intermediate volcanic centres in the southern parts of the peninsula. The high sulphidation deposits such as Seongsan and Kohung are characterised by pervasive silica-alunite-dickite-pyrophyllite alteration with anomalous arsenic geochemical signatures. Gold mineralisation is associated with fine grained marcasite and pyrite. A low sulphidation quartz vein system observed at the Tongyoung mine comprises multistage colloform banded quartz-carbonate assemblages, with minor manganese and base metals. Gold and silver occur as electrum and tellurium minerals. Some deposits such as Gasado and Dogcheon display both high and low sulphidation alteration assemblages. Early pervasive silica-alunite-pyrophyllite alteration caps formed by acid fluids with a significant magmatic component, occur above cryptocrystalline colloform banded vein systems. The quartz vein stage hosts the precious metal mineralisation and appears to have been deposited by later neutral fluids generated in part through mixing with meteroric water.

Jan 1, 1999

By I Basson, J A. Miller, M Becker, F C. de Beer, L C. Bam

"Geometallurgy brings together geologists, mine planners and process engineers to extract meaningful mineralogical and textural information from an orebody, with a view to predicting its metallurgical response. Preferably, automated analytical techniques, which provide mineralogical and textural information, should process a large number of samples quickly, relatively inexpensively and reliably. Microfocus X-ray computed tomography (µXCT) is capable of producing 3D volumetric information on texture and mineralogy that satisfies some of these criteria. µXCT has been used extensively to study the porosity and internal pore structure of iron ore pellets as part of downstream processing. It has not been widely applied to earlier mineralogical and textural analysis of unprocessed ore, due to the limited ability of X-rays to penetrate high-density samples. In this contribution, we propose scanning methods to overcome this limitation, thereby facilitating a broader application of µXCT to iron ore resource management.CITATION:Bam, L C, Miller, J A, Becker, M, De Beer, F C and Basson, I, 2016. X-ray Computed Tomography – Determination of Rapid Scanning Parameters for Geometallurgical Analysis of Iron Ore, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 209–220 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By S Porter, R Woodall, N Weeks

Nelsen, Porter and Wilson (1996) provided some preliminary concepts for the design of the Melbourne City Link tunnels. At that time, the City Link project was in the early design phase whereas now it is nearing completion. This paper provides details of the actual design adopted for the various sections of the tunnels as well as some commentary on the design process. The tunnels form a critical element of the project and the design of both driven and cut and cover tunnel sections is a significant factor contributing to successful project execution. Geology, hydrogeology, site constraints, traffic management and program were important design inputs. Design for the cut and cover sections in particular varied significantly in response to these differing inputs.

Jan 1, 1999

By Singh RN

Monolithic packing systems have gained in popularity as a gate side packing method. However, there has been no detailed investigation to assess their underground strength behaviour. This work includes the laboratory and in situ investigation for strength behaviour determined on various monolithic packing materials namely Tekpak-XX, Hydropak-20, Hydropak-30, Astrapak-3R, Flashpak, Thyssen pack and Aquablends. A simple technique for assessing the pack strength was developed at the laboratory by using a penetrometer, of which penetration resistance can be directly correlated with the uniaxial strength of the pack. The in situ strength investigations were made on core samples obtained from three pipes inserted inside the pack, while the penetration test were made on the pack surface. The in situ results indicated that the packing material develops an inconsistent strength on various part of the pack which was mainly related to an inadequate mixing of grouts inside the pack.

Jan 1, 1992

By M Araos, I Onederra

A novel explosive formulation that substitutes the use of ammonium nitrate (AN) with hydrogen peroxide (HP) as the main oxidising agent has been developed and tested as part of an Australian Coal Industry Research Program (ACARP) project. The main objective was to provide a step-change solution that has the potential to completely eliminate NOx fumes in blasting. The development of this HP/fuel-based explosive started with a comprehensive detonation characterisation program, consisting of unconfined velocity of detonation (VOD) measurements of samples at different diameters, densities and void sensitisation techniques. VOD results showed that the HP/fuel-based explosive mixtures behaved similarly to non-ideal commercial explosives; in that way mixtures could be tailored to achieve specific detonation performance targets. The next stage of testing in this development involved preliminary confined tests to evaluate the rock breakage potential of the HP/fuel-based explosive mixtures. Fully instrumented single-hole tests were conducted in a limestone quarry. Results from these preliminary trials confirmed the rock breakage performance of HP/fuel-based explosive mixtures. The confined VOD measured in one of the tests was 5100 m/s in a 102 mm diameter blasthole at a density of 0.96 g/ml. The corresponding borehole pressure measurement of this HP charge was 2.61 GPa with a detonation temperature of 2921°C. Based on near-field accelerations, both HP and ANFO charges displayed similar attenuation characteristics in the test conditions. Post-blast observations indicated that the breakage performance of the HP mixtures clearly reflected the in-hole detonation performance measurements obtained, confirming the ability of these explosive mixtures to both fragment and effectively displace the rock mass under evaluation. Further research work continues with the future commissioning of a prototype mixing and delivery unit, the successful completion and analysis of data from multiple-hole trials, and further characterisation work associated with product stability, reliability and performance under different geotechnical conditions.CITATION:Onederra, I and Araos, M, 2015. Detonation and breakage performance of a hydrogen peroxide-based explosive formulation, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 565–574 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By N Takamatsu

The environments surrounding the iron and steel industry have changed greatly in recent years. Reported in this paper are the technologies adopted by the Japanese iron and steel industry to fititself to change in global steel demands, degradation of iron ore and coal, prolonging service life of the facilities and requirements of energy saving. In addition, innovative technologies for CO2 emission control in iron making processes are also discussed.

Jul 11, 2011