Search Documents

Ore textures in Australian BIF-derived ores are quite complex and have formed the basis for ore genesis models, which includes hypogene upgrading or supergene upgrading then regional metamorphism for the microplaty hematite ores and supergene upgrading for the martite-goethite ores. Despite a high level of ore texture knowledge, little is known about the spatial distribution of ore textures within deposits or their relationship to downstream processing. This paper describes a new iron ore texture classification system to better understand the vertical textural zonation characteristics of Australian BIF-derived deposits, the interpreted role of recent supergene upgrading processes on modifying primary ore textures and their implications for downstream mineral processing. The iron ore textural classification scheme presented uses textural groupings defined on the basis of similarities in mineralogy, ore texture, porosity, mineral associations and hardness. The scheme is non-genetic and has been successfully applied to deposits in the Pilbara, Yilgarn and Gawler cratons. The main ore texture groups include dense martite/hematite, microplaty hematite, microplaty hematite-goethite, martite-goethite, goethite-martite and goethite-rich. Each group can be further subdivided into physically hard to softer subcategories. The ore textural groups can be divided into those interpreted to be associated with primary replacement of BIF and secondary textures resulting from more recent modification by near-surface hydration or dehydration processes. A schematic vertical section through BIF-derived deposits consists (from surface) of detritals underlain by a carapace, both of which may have been eroded, followed by a hydrated zone with replacement of primary ore martite and microplaty hematite by vitreous goethite. The hydrated zone is underlain by 0.2 - 6 m thick zones of intense dehydration and textural infilling of porosity with hematite and hydrohematite. Immediately below the dehydration zone is a strong zone of leaching, where more porous and friable ore textures occur, followed underneath by a gradational contact with primary ore. Secondary supergene processes can impact on beneficiation with hydration and leaching resulting in more difficult density separations at the concentrator stage due to reductions in density differences between ore and gangue and loss of heavy media into pores. Supergene modification of primary BIF-derived ore textures can substantially change lump metallurgical properties, with hydration and dehydration favourably increasing lump yield but reducing resistance to thermal shock whilst leaching will give the opposing outcome. The lump properties of ore textural groups appear to be relatively consistent within and between the iron ore deposits examined.

Jan 1, 2002

By Gonzalez-Dominguez J. A, Dreisinger D. B

At Cominco's Zinc Refinery at Trail, British Columbia impurities are removed from zinc sulphate electrolyte by a two-stage purification process using zinc dust. Copper, cadmium and thallium are removed in the first stage whereas cobalt is removed in the second stage. Cobalt removal kinetics are affected by soluble antimony and copper additions to the electrolyte. This study was focused on the kinetics of cobalt removal by zinc powder cementation. Experimental variables included copper and antimony concentrations, pH and temperature. Common organic additives employed in zinc plants were studied to determine potential interactions with the cobalt removal process. Cementation products obtained from laboratory experiments and plant practice were studied using SEM. A number of significant results were obtained: 1. Copper and antimony ions were sustantially removed from solution during the early stages of the cementation reaction (within the first 15 minutes). Cobalt cementation kinetics are slow and follow a first order kinetic regime. 2. A drop in the cobalt removal rates can be correlated with a rise in the Eh of the slurry. 3. Ligninsulphonate, Percol 351 and animal glue at levels of 2 mg/L significantly impede cobalt cementation.

Jan 1, 1993

By J E. Wheeler, S B. Valine, L G. Albuquerque

It has long been known that closed circuit grinding with a classifier improves grinding efficiency, reduces unit specific power consumption, and reduces over grinding. The classification device removes material from the circuit that has reached the desired size and returns coarse material back to the mill for further grinding. The efficiency of the classifier is an important factor in the overall performance of a grinding circuit. The classifier affects the capacity of the grinding circuit and the metallurgical performance of downstream operations. A review of historical research and modern case studies is used to demonstrate the benefits of high frequency screens for classification in grinding circuits.CITATION:Valine, S B, Wheeler, J E and Albuquerque, L G, 2012. Applications of fine screens in grinding circuits, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 389-394 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By D Kentwell

A resource model serves two main purposes depending on the stage of a project. The first is to provide an early indication of likely tonnages and grades at certain cut-offs so that decisions can be made on whether continued spending on the project is justified. The second is to provide a basis for mine planning, feasibility studies and reserves. Resource models are not designed for selection of actual blocks in the ground for processing. This is the purpose of a grade control model, which is created at a stage beyond both resources and reserves.Inferred, Indicated and Measured Resources contain different levels of uncertainty with respect to the accuracy of the resulting grade and tonnage curves. These uncertainties arise from three broad areas: quality of information, geological assumptions and estimation technique. This paper focuses on known problems with the ordinary kriging (OK) estimation technique. Resource estimates often produce smoothed block grade distributions with much lower block grade variability than true selective mining unit (SMU) block grade distributions. There are two main factors that are involved in this smoothing. Firstly, where the block size used for estimation is larger than the SMU block size, this will smooth the block grade distribution and move the grade and tonnage curves away from the true SMU block grade and tonnage curves. Secondly, and less well recognised, is that smoothing is inherent in the OK estimator. This also moves the grade and tonnage curves away from the true SMU grade and tonnage curves, even when the estimate is done at the SMU block size. There are a number of techniques, such as simulation, uniform conditioning and degraded search neighbourhoods that can provide a better approximation of the true SMU block grade and tonnage curves at the expense of individual block accuracy.This paper aims to explore the extent to which OK resource estimates designed to maximise individual block accuracy can differ from (an estimate of) the true resource at SMU block size in terms of grade and tonnage curves. The differences at economic cut-offs and above are examined. In some cases these differences are significant. Both the OK estimation technique and block size play a part in the differences observed. To do this we will examine a number of commodities and deposit types using real project data.The conclusion is that the current industry standard default practice of targeting maximum individual block accuracy (conditional unbiasedness) using OK at resource stage, without consideration or evaluation of the extent of associated smoothing at SMU scale, can lead to significant errors in fundamental mine planning decisions. This then has implications for resource classification if the classifications are based heavily on the OK quality without consideration of the true SMU distribution.CITATION:Kentwell, D, 2014. Aligning resource estimates with mine planning, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 185–192 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

The purpose, basic data requirements and various analysis/modelling tools employed for geomechanical evaluation of mine-site conditions are overviewed. The impact and application of computer technology are dis- cussed. Broad guidelines and criteria are presented for establishment of a practical geomechanics data-base system to yield infor- mation suitable for mine design purposes. Future needs of the Australian mining in- dustry are examined.

Jan 1, 1983

By Lawson F

Chrome chemicals are commercially produced by the alkali roasting of chromite ores with sodium carbonate. Results of tests conducted in a laboratory furnace indicated that the sodium carbonate reacted rapidly with part of the gangue material to form a metastable intermediate that later reacted further with the chromite. For the conditions used, the recovery of water-soluble sodium chromate was able to be described empirically as yield % = a tn with a = 0.24 T - 241.3; n = 3.90 - 3.12 × 10-3 T and t is the reaction time in hours.The major rate limiting step in the overall reaction sequence appears to be the rate at which oxygen can get to the reaction sites across the liquid film coating the solid reactants.Sodium sulfate alone was found to be an unsatisfactory source of alkali for reaction with chromite. However when limestone also was added in quantities sufficient to allow the reaction CaCO3 + Na2SO4 + H20 ? Ca SO4 + 2NaOH + CO2 to take place, the results obtained were comparable to those found when sodium car-bonate was used.For chromite particles in the size range -124 + 105 µm, the use of stoichiometric excess of sodium carbonate did not appear to increase the yield or the reaction rate significantly. However, with smaller sized particles, - 53 µm, increased yields of water-soluble chromate were obtained when roasted with more than the theoretical quantity of sodium carbonate.

Jan 1, 1984

By R Bunduwongse

The oil crisis had repercussions throughout the world and most importantly on mining, where the drive to reduce the use of liquid fossil fuel led directly to the appearance and subsequent growth in the design of mobile crushers in late 1970s early 1980s, which heralded a new era in both quarrying and mining. Even though mobile crushing has now become common, even preferred in the quarrying industry, this has not been the case in mining. This paper looks at why, in spite of the initial optimism, this technology has yet to gain full acceptance in the mining industry. The paper examines some of the problems that have been encountered in the past and offers suggestions as to how they can be avoided by applying the appropriate technology. It then takes a look at the successful application of the semi-mobile in-pit crushing system used by Italian Thai Development Company (ITD), on the Mae Moh Phase 5 contract and examines how the techniques used successfully there could be applied to the industry at large.

Jan 1, 2007

By B A. Webler, P Su, P C. Pistorius

Advanced high-strength steels (AHSS) typically have much higher aluminium concentrations (by an order of magnitude or more) than conventional low-carbon aluminium-killed steels. The resulting lower oxygen activity at the steel-slag interface changes the kinetics and thermodynamics of steelslag reactions. Previous work showed that the rapid transformation of alumina inclusions to spinel inclusions, and spinel to periclase, occurs because of the relatively high concentration of dissolved magnesium. In this paper, experimental results on nitrogen removal by ladle slag are compared with predictions based on the available thermodynamic databases. As in previous work, the kinetics was modelled by assuming mass transfer control, with steel or slag mass transfer limiting. The results show that significant removal of nitrogen by steel-slag reaction is possible.

Aug 21, 2024

Folklore suggests that oxidation is detrimental to sulfide mineral flotation, and in many instances is the reason given for values reporting in the tailing. However, while a considerable body of work examining galena oxidation is available in the literature there are very few studies that investigate the consequences of galena oxidation on its subsequent flotation in base metal sulfide ores. This work clearly demonstrates that pyrite forms a galvanic couple with galena, due to the large difference in their rest potentials, and results in accelerated oxidation of galena, particularly as the pyrite content of the ore is increased. The most obvious effect of the galvanic oxidation of galena by pyrite is the release into the system of galena oxidation products, providing an ample supply of lead ions available to activate gangue minerals, most notably of which in lead/zinc ores is sphalerite. The inadvertent activation of sphalerite by lead ions inevitably leads to the recovery of liberated sphalerite into the lead concentrate, and as a consequence a reduction in the lead concentrate grade. That is, a loss of selectivity for galena against sphalerite. If galena oxidation is excessive not only is there a considerable loss in lead concentrate grade, but also a marked decreased in lead recovery as the flotation rates of the gangue minerals increase, until they rival that of galena.

Jan 1, 2005

By R A. Anand, N N. Viswanathan, M M. Pande

Slags are the most voluminous solid by-products generated in pyrometallurgical operations, and, as such, finding an application for these oxidic materials is pertinent to maintaining resource efficiency. In particular, pyrometallurgical copper production is associated with high slag rates, typically ranging from 2.2 to 3.0 tons of slag per ton produced copper, which necessitates slag valourisation. A possible application for these iron silicate slags is as supplementary cementitious materials (SCMs), which effectively lowers the CO2 emissions per ton of cementitious material. Although utilising iron silicate slags as SCMs has been studied in previous work, the scientific literature has limited data on the effect of composition on the inherent reactivity in cementitious systems. More specifically, no reports on the impact of FeO/SiO2 ratio have been presented in previous publications. Therefore, the present study aimed to isolate this parameter in a synthetic FeO-SiO2-Al2O3-CaO-MgO-Cr2O3 system. Since the amorphous content is a pertinent parameter for SCMs, a high-temperature confocal laser scanning microscope (HT-CLSM) was utilised to assess the crystallisation behaviour at continuous cooling conditions. Furthermore, high-temperature rheological experiments were conducted to measure the viscosities of the slags in relation to the crystallisation behaviour. The experiments showed that depolymerising the slag by increasing the FeO/SiO2 ratio generated a less viscous slag, which showed higher tendencies for crystallisation. Furthermore, experiments assessing the inherent reactivity as an SCM showed that depolymerising the slag by increasing the FeO/SiO2 ratio as the sole independent parameter generated an initially more reactive slag. However, replacing SiO2 with FeO was found to negatively affect the reactivity as measured over seven days within the tested compositional range.

Jun 19, 2024

By Kato Y

As a direct result of the Mining Industries need to improve efficiency and production in Open Pit type operations, the size of haulage units have increased dramatically. This trend has continued such, that the majority of dump trucks operating in Open Pit operations are in the 170 ton class. Continued mining in existing locations has meant that the increase in vertical lift and resultant grades, and increases in hauling distances are making electric drive systems unsuitable. This is largely due to the electric drive systems heat limitations on major propulsion components. With these mining requirements in view and the present limitations on electric drive systems in mind, Komatsu have been developing the Komatsu HD1600M. A diesel powered mechanical drive dump truck capable of operating in deep pit operations. This presentation introduces: Komatsu HD1600M Dump Truck

Jan 1, 1982

By J E. Powalisz

Obtaining a representative sample of bulk materials in process industries is critical to providing valid data for process control and custody transfer (valuation). The accuracy of a sample, that is to say how well the sample represents the material in the process, is directly related to how well the process can be controlled and to how much a product may be worth. Sampling accuracy then is in fact related to bottom line profitability.Sampling theory offers information and equations on how to take a representative sample from a process, however, the actual practice of extracting a sample from the process can be more of an art.Key sampling variables include product specifications such as bulk density, particle distribution, material conveyance, practical sampler location, sampler type and sample frequency and volume/mass.This paper discusses basic sampling theory, sampling methods, types of samplers, how to develop a ‘real world’ sampling system and current manual and automated samplers.Key points include ‘practical precision and variance’, material properties, flow properties, direct sampling versus indirect sampling, sampler types and applications.CITATION:Powalisz, J E, 2014. Bulk solids sampling, in Proceedings Sampling 2014 , pp 179–188 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

The sixth international symposium on mining with fill nearly coincides with the 25th anniversary of the Jubilee Symposium on Mine Filling. That symposium, held in August 1973 in Mount Isa, in part to commemorate the 80th anniversary of The Australasian Institute of Mining and Metallurgy, was the first in what has turned out to be a very successful series of symposia. Subsequent symposia were held in Sudbury, Canada (1978), Lulea, Sweden (1983), Montreal, Canada (1989) and Johannesburg, South Africa (1993). The series of symposia has now become an established part of the mining industry calendar, and it will be interesting to see which country is given the honour, and accepts the challenge, to organise the next symposium.One way of predicting the future, or some small part of it, is to revisit where we have already been with a view to determining the existence of any trends that may impact on the future. An historical review of filling practice and research, with special emphasis on Australian experience in particular and worldwide in general over the previous 25 years, will enable me to address the historical and predictive objectives. Controversy can always be achieved by producing a best of list; it can be guaranteed that everyone will disagree with at least one of the nominations. On this occasion, the best contributions by individuals or groups in a number of areas of mine fill technology, over the last 25 years, will be the basis for the nominal awards. The controversy can be increased by posing a number of questions that, hopefully, some of the authors will address during their presentations. I imagine the social functions will be busy enough, but the questions may just add to the cut and thrust of the debate.

Jan 1, 1998

By D Goel

India, the second-largest steel manufacturer globally, achieved crude steel production of around 126 million tonnes (Mt) in the last financial year of April 2022 to March 2023 (FY23), against an installed capacity of 162 Mt. In its National Steel Policy, 2017, India has undertaken targets to take the crude steel production capacity to 300 Mt by 2030–2031 and production and demand to around 255 Mtpa, also by this deadline. The blast furnace-basic oxygen furnace (BF-BoF):electric arc furnace-induction furnace (EAF-IF) ratio in 2022 was at 44:56.

Sep 18, 2023

A review is given of progress made to- wards the development of personal gravimetric dust sampling for risk assessment on South African gold mines. The present strategy is critically examined on the basis of principles for assessing health hazard from dust exposure. Reasons are advanced for replacing the konimeter with a gravimetric system based on full shift personal sampling. Constraints imposed by local characteristics of gold mines are used to illustrate the difficulty in finding suitable instrumentation for measuring personal exposure to respirable silica.

Jan 1, 1988

By A V. Ozsever

The selectivity in flotation columns involving the separation of particles of varying degrees of floatability is based on differential flotation rates in the collection zone, reflux action between the froth and collection zones, and differential detachment rates in the froth zone. Using well known theoretical models describing the separation process and experimental data, froth zone and overall flotation recovery values were quantified for particles in an anthracite coal that have a wide range of floatability potential. For highly floatable particles, froth recovery had a very minimal impact on overall recovery while the recovery of weakly floatable material was decreased substantially by reductions in froth recovery values. In addition, under carrying-capacity limiting conditions, selectivity was enhanced by the preferential detachment of the weakly floatable material. Based on this concept, highly floatable material was added directly into the froth zone when treating the anthracite coal. The enriched froth phase reduced the product ash content of the anthracite product by five absolute percentage points while maintaining a constant recovery value.

Jan 1, 2005

The economic significance of a fundamental understanding of the mineral pyrrhotite is dis- cussed. Particular emphasis is placed on the relationship of other sulphide minerals to the pyrrhotite when it is the major sulphide mineral present in an ore body. Studies of the Kambalda nickel deposit are used to give a better under- standing of (a) the genesis and other character- istics of a particular ore body (b) the textural relationships between pyrrhotite and other sul- phide minerals (c) magnetic properties of natural pyrrhotite, and (e) the oxidation and supergene processes that take place in a sulphide ore body.

Jan 1, 1972

By Merry N, Cocks T

The mineral exploration industry is increasingly aware of the importance of the relationship between mineralogical data and geochemical assay results. However, until recently, the cost and time constraints of most techniques for analysing alteration mineralogy have precluded detailed alteration studies. These impediments have been reduced by the development of the Portable Infrared Mineral Analyser (PIMA), a field portable infrared spectrometer that allows rapid (in field) and cost effective analysis of alteration minerals including subtle variations in mineral crystallinity and Composition.

Jan 1, 1995

By Weller KR

A study of high pressure rolls grinding of a number of Australian ores and minerals has been carried out using a pilot-scale machine with rolls 300 mm diameter and 70 mm wide. The results from this study have been used in conjunction with plant survey data to construct computer simulation models of various comminution circuits and these have been used to investigate options for incorporating high pressure grinding rolls into these comminution circuits. Possible rolls options for three of these circuits are presented, and likely energy savings over the existing circuits are discussed together with potential improvements in plant throughput and/or product sizing. A scale-up procedure for predicting full-scale machine performance from small-scale testing is described, and the effects of rolls operating conditions are also discussed.

Jan 1, 1991

The Kennedy Siltstone Open Cut provides graded rock for stope filling. Rotary drilling of 310 mm blastholes with a Gardner Denver GD120 is used, and the successful application of an equilateral triangular drilling pattern is described. Charging practices and the development of bulk slurry handling are outlined. Blast monitoring plays an important role in K.S.O.C. drilling and blasting operations. The proximity of nearby residential areas (1300 m) and the Mount Isa Airport (4500 m) necessitates special attention with regard to the minimisation of both air blast and ground vibration levels. The application and control of drilling and blasting parameters has had a direct bear- ing on success of the mining operations and also played an important role in reducing the disturbance to the community.

Jan 1, 1978