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By Falbo A, Barbaro M, Esposito MA, Passariello B

Acidic reductive leaching is one of the best known and most widely employed chemical processes for beneficiating minerals of industrial interest. Conventional acidic leaching with sodium dithionite (Na2S2O4), employed to bleach industrial minerals used in the production of ceramics, glassware, paper etc, does not always allow products of high quality to be obtained. In the work reported here two reducing agents, ascorbic acid and oxalic acid, have been employed in a medium acidified by means of sulphuric acid. Continuous systematic tests have been performed on a kaolin sample containing 0.8 per cent Fe2O3, adopting various operating parameters such as, leaching time, temperature and reagent concentration. In each case the total quantity of bi- and trivalent iron dissolved was ascertained. Removal of 80 per cent and 100 per cent of iron with ascorbic and oxalic acid respectively was obtained, while less than one per cent of iron was dissolved in the presence of sulphuric acid only. Products having a very good degree of whiteness (92 - 94 per cent) were obtained, whereas with sodium dithionite the degree of whiteness was in the 85 to 88 per cent range. The best conditions identified were applied to a sample of quartz for the removal of ferric impurities.

Jan 1, 1993

By Martin R. E

L44 Shaft is a major upcast ventilation shalt in the hanging wall of the 1100 Orebody. Various techniques for stripping a raisebored pilot hole were combined to produce L44 shaft. From the surface to 198 m depth, the shaft was concrete lined 7.3 m internal diameter. Below this the shaft was developed to 7.6 m diameter unlined. 11 level, 540 m below the surface, was the first readily accessible level connection. The section to 198 m depth was benched and concrete lined through weak oxidised ground. When more competent ground was encountered the operation was converted to horadiam stripping. This application of the raiseborer has led to a safer, more efficient method of shaft development.

Jan 1, 1977

During the life of a mining project in Papua New Guinea (PNG), the greatest impact is on the people of the project area and the most intense, day-to-day contact is between these people and the project's field staff. Yet formal structures at present emphasise contact between much higher levels of national government and company personnel. Whilst understandable, this is unfortunate particularly since, given the nature of PNG politics, villagers do have a powerful influence on project success, as recent dramatic events on Bougainville have indicated. A greater role for local views and greater attention to such views by other parties is clearly required. But to achieve a successful marriage between informal village politics and the formal structures of investment procedures will require considerable patience and adjustment. This should be reflected in the cost of project development and be regarded as being as of a significance equal to that currently accorded to the technical aspects of project development.

Jan 1, 1990

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 A Annor, L J. Chen

The production of paste backfill has typically been accomplished through the adaptation of existing technology. Thickeners and disc filters have several drawbacks when applied to production of tailings paste backfill. Personnel at CANMETÆs backfill research laboratory in Sudbury, Ontario, Canada have been carrying out research into and development of methods to produce paste backfill using total mill tailings since 1991. Using a silo for production of paste is not a new concept but has been refined to a marketable level. This technology is based on a fluidization principle that assists in settling the tailings to an homogenous state in a silo. Other developments include patented de-watering technology for use in the silo to speed the settling of the solids to a suitable solids content, optimisation of silo geometry, and instrumentation related to paste backfill production and transportation. The advantages to fluidisation technology are in reduced capital cost, reduced operating costs and in the environmental benefits of using full plant tailings over classified tailings or alluvial aggregates. Another major advantage is in the ability of this technology to be retrofitted to existing hydraulic backfill plants to further reduce capital cost. This paper details the development of the new technology as well as the associated cost savings over other technologies. It will also look at the research and development of unique components that make this technology work.

Jan 1, 1998

Gravity concentration of tin at Renison Limited uses tables and spirals to treat the various coarser fractions produced from sulphide flotation tailing. An acceptable final tailing cannot be made from one pass over the tables and spirals and therefore the tailing from these separators is reground and combined with the sulphide flotation tailing as the feed to the classification section. The gravity section became increasingly overloaded in the years preceding 1976 due to efforts to maximize tin recovery to the gravity concentrate. In April, 1976, two 2DSV Reichert cone concentrators in series were installed to treat the table and spiral tail- ing stream, prior to regrind, to scavenge a small tonnage of hard, coarse low tin grade material for rejection to final tailing. Gravity section loadings were decreased markedly, allowing operator attention to be directed more to table performance than to spillage collection. An increase in mill throughput of approximately 15% was possible following the commissioning of the Reichert cones. The cones are currently operated to make the minimum tonnage of tailing consistent with reasonable- gravity section loadings.

Jan 1, 1978

By O Bøckman, E Thisted, K H. Esbensen, U Thisted

Process industry measurement systems, once installed, are often interpreted as static black boxes delivering correct values as long as not proven otherwise. After first implementation and set-up with a distinct sampling frequency, they often run ‘forever’ without checking if this frequency is still appropriate with respect to changed raw materials characteristics, different process conditions or changed customer specifications. Failure detection is based on operator experience and skills (often close to an art form) and/or from control measurements of reference samples. This may well be too late for many industrial process contexts. An appropriate sampling frequency is a critical success factor for valid monitoring and control.Based on the methodology of variographic analysis we here illustrate how to design/re-design/optimise an industrial measurement system in terms of sampling frequency, discretisation and accuracy based on customer specifications. We also show how variographics can be used to monitor for deviations. We use experience from process industry to show how these methods can be used not only for product characterisation, but also for monitoring input factors, process indicators and measurement of these. The information hidden in the vast amounts of data that is continuously created in modern process industries can be utilised to cut costs in the measurement activities and at the same time contribute to early error detection. We illustrate by case examples from production processes at a nickel refinery, supporting the Lean and Six Sigma methodology. This will provide a standard operating procedure for monitoring the stability of measurement systems, and provide a basis with which to discuss how a variographic approach can be integrated with the Lean and Six Sigma approach as an online tool to map, characterise and validate measurement systems and thus avoid more cumbersome measurement system analysis in full detail.CITATION:Thisted, E, Thisted, U, Bøckman, O and Esbensen, K H, 2017. Variographic case study for designing, monitoring and optimising industrial measurement systems – the missing link in Lean and Six Sigma, in Proceedings Eighth World Conference on Sampling and Blending , pp 359–366 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By Guoqing Cao, Xinghong Wang, Fuqiang Liu, Rong Shen, Xiaoping Yuan

In this paper, an approach is proposed to monitor the rate of lump coal based on image processing. Using this method, we effectively improve rate of lump coal on comprehensive mechanised coal face.

Jan 1, 1998

By J D. Lubben

Hibbing Taconite is a Lake Superior-type granular magnetite taconite deposit occurring within the Biwabik Iron Formation along Minnesota’s central Mesabi Iron Range. The deposit is situated on the northern margin of the Proterozoic Animikie Basin. The deposit strikes northeast, dips gently southeast, and occupies 10 km of strike length. Mining focuses on 50 m of granular cherty and laminated slaty taconite within the Lower Cherty member.Ores generally consist of a quartz, magnetite, siderite, ankerite, minnesotaite, stilpnomelane, and haematite mineral assemblage. Processing is optimised by exploiting the physical and chemical variations that exist between three major ore types. Taconite ore averages 20 per cent magnetic iron (MagFe), 27 per cent weight recovery (WtRec) and produces a final concentrate with 4.5 per cent silica (SiO2). Since 1976, production has totalled approximately 237 million long tons (Mlt) of pellets (8 Mlt per year rated capacity).Ore processing uses a simple fl ow sheet of autogenous grinding (<0.044 mm) followed by two phases of wet magnetic separation, fi ltering, limestone/bentonite addition, balling, and firing to create pellets averaging 66 per cent total iron. A Liberation Index (LIS) is used as a primary guide for ore grading and metallurgical control. Grind requirements, magnetite liberation and silica grade are closely monitored to ensure plant optimisation and product quality.A recent program of benefi ciation of low-grade ores by in-pit crushing and dry magnetic cobbing has demonstrated that low-grade ores (<17 per cent MagFe, <25 per cent WtRec) can achieve a signifi cant metallurgical upgrade (up to 25 per cent MagFe and 40 per cent WtRec). This operation recovers 60 per cent of the total crushed volume, and has a calculated effi ciency factor (magnetic iron recovery) of 79 per cent. This paper discusses the benefi ts of this upgrading and its effects on ore blending and processing.

Jul 11, 2011

By A Bagis

Road tunnels are an accepted and effective transportation solution in urban areas to mitigate increasing traffic congestion and facilitate improved urban connectivity in a cost effective manner while meeting societal goals to reduce the impact of construction. In designing a tunnel system, there is a requirement to achieve an acceptable level of in-tunnel air quality, as well as meeting ambient air quality goals. In Australia, there is also a requirement for zero portal emissions which means that all pollutants must be emitted to the atmosphere via a ventilation stack.Traditionally, effective pollutant dispersion has been achieved by constructing tall ventilation stacks which disperse pollutants into the atmosphere at a high level. The dominant variable parameters in the effectiveness of the dispersion under the ventilation engineers control are the efflux velocity, the height of the ventilation outlet and the concentration of pollutants at the point of discharge. During off-peak operations the required ventilation exhaust rate can be reduced due to the decrease in traffic. This can lead to a drop in the efflux velocity from the stack and therefore the effectiveness of the dispersion. This potentially drives the need for a higher outlet, or an increased exhaust rate to achieve a higher efflux velocity with consequent effects on energy consumption.The paper proposes a method of varying the cross-sectional area of the ventilation stack with the use of motorised control dampers, thereby maintaining a sufficiently high efflux velocity throughout the 24 hour period independent of traffic conditions. This allows the use of a potentially shorter ventilation stack.

Mar 8, 2011

By E Gabriel, J C. Koppe, A Gomes and P Crispim, R Schaarsdmit, I Pablos

Drill and blast (D&B) is one of the most important production operations in open pit mining. The resulting fragmentation of the D&B reflects in the downstream unit operation. Good fragmentation of the ore will minimise the cost of loading, hauling and crushing. The understanding of the geological model integrated with a software system for bench face surveying and planning of blast layouts based on three-dimensional images can help to achieve the fragmentation goals of the mine operation. A case study integrating these tools was carried out in a large iron mine in Brazil. The iron ore in the study area consists of hard and friable itabirites. More than three different ore types may occur on the same bench. Under these conditions, data integration becomes necessary to improve the results of blasting. A blasting plan was based on the generated geological model. The methodology helps understanding the factors that can interfere in the fragmentation process, allowing defining actions that can improve the blast design in those places that fragmentation wasn’t achieved. This condition is important for a continuous improvement of the drilling and blasting operation. In comparison with the previous blasting carried out at Itabira mine, which did not take into account the geological model, substantial improvements in fragmentation were observed, eliminating the need for secondary blasting.CITATION:Schaarsdmit, R, Pablos, I, Koppe, J C, Gabriel, E, Gomes, A and Crispim, P, 2015. Geological modelling and bench face survey to improve blasting fragmentation, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 401–406 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By García B., Wolff E.

The pellet qualities primarily depend upon the thermal profile and gaseous environment during induration. During the induration of the pellet, it undergoes physical as well as chemical changes. Physical changes are mostly due to sintering and chemical changes are due to carbon burning inside the pellet. The effect of carbon on sintering is investigated on a single pellet scale using an optical dilatometer. Sintering is a complex process that involves transportation through various mechanisms. Sintering is quantified in terms of sintering ratio and the kinetic parameter, exponent ‘n’, under isothermal conditions is deduced using the power law equation. The value of n can be used to estimate the sintering mechanism at different isothermal temperatures. Also, the activation energy is calculated using the empirical Arrhenius equation. The activation energy of 0 per cent coke and 1 per cent coke-containing pellets are 531.0 kJ/mole and 552.6 kJ/mole respectively. The order of magnitude of activation energy suggests the same mechanism in both cases. Although the mechanism of sintering is the same, 1 per cent coke-containing pellet sinters more at any isothermal temperature.

Jun 17, 2024

By I R. F MacCulloch

Bacterial oxidation of sulfide minerals is a familiar and commercially available process to enhance gold recovery with problem ores. Pintail Systems, a Colorado, USA based company had developed bio-processes for gold recovery based on natural mineral formation and transformation in a global mineral cycle. The biological recovery of precious metals from ore involves a number of mechanisms that are dependent on the metal-mineralogical association. These processes include: partial bio-oxidation of sulfide ores; oxidation of gangue minerals exposing gold to leaching; surfactant properties of bacteria/nutrient solutions that improve wettability of ores and solution contact with leachable gold and silver; and microbial production and excretion of trace amounts of gold lixiviants, and bio-fracturing or biological alteration of ore minerals. Pintail has demonstrated enhanced recovery of precious metals during cyanide detoxification of spent heaps at the end of mine life. Biological recovery processes also have the potential to be applied to in situ mining technologies. The in situ process application could recover gold from subgrade deposits, small deposits or those ore bodies with uneconomic stripping ratios for conventional mining. In situ biomining can be accomplished at a fraction of the cost of conventional mining and leaching and does not have the environmental liabilities associated with many conventional gold lixiviants.

Jan 1, 2004

Many stress measuring instruments use overcoring stress-relief principles but adopt different sensing techniques. Every technique is subject to certain limitations of rock types and conditions. To investigate the performance and reliability of the instruments in field measurement, a simple and practical approach has been developed to allow comparable laboratory results to be obtained which simulate in-situ rock and stress conditions. Four commonly used devices, the USBM deformation gauge, the CSIRO HI cell,the CSIR triaxial cell and the UNSW SI cell were thoroughly tested in the laboratory. Some conclusions have been drawn as to their suitability and reliability in different field conditions. Recommendations are provided for the choice of an appropriate technique for a given rock type and condition. A new thin-wall cell that overcomes the disadvantages of earlier devices has been developed and tested. Its laboratory performance shows that it has good prospects.

Jan 1, 1990

By M I. Pownceby, N A. S Webster, A J. Studer, I C. Madsen, J A. Kimpton, M J. Fisher-White, L Lu

In situ synchrotron X-ray and in situ neutron diffraction-based experimentation have been implemented to characterise the formation of the complex calcium ferrite iron ore sinter bonding phases silico-ferrite of calcium and aluminium (SFCA) and SFCA-I. Experiments were carried out using fine-grained (<20 ¦m) sinter mixtures containing ~77 wt per cent Fe2O3, 14 wt per cent CaO, 3.5 wt per cent SiO2 and 5 wt per cent Al2O3, with diffraction data collected during heating until 1300 - 1350¦C, which was enough to ensure complete melting of the SFCA phases. In the case of the in situ synchrotron experimentation, results showed that altering the nature of the starting sinter mixture (ie substitution of goethite for hematite; substitution of an amorphous Al2O3-based mineral for gibbsite) did not have a significant effect on the thermal stability range of the SFCA phases. It did, however, have a profound effect on the formation and rate of consumption of the calcium-rich ferrite phases C2F and CF, and on the formation mechanisms of SFCA and SFCA-I. The in situ neutron diffraction experimentation is the first described in the context of iron ore sintering, and the observation of both SFCA-I and SFCA formation in the in situ diffraction data represents the first step in achieving the goal of charactering iron ore sinter phase formation in large volumes of industrial sinter starting materials with a wide range of particle sizes (up to 6.3 mm).CITATION:Webster, N A S, Pownceby, M I, Madsen, I C, Studer, A J, Lu, L, Manuel, J R, Kimpton, J A and Fisher-White, M J, 2013. In situ x-ray and neutron diffraction studies of silico-ferrite of calcium and aluminium iron ore sinter phase formation, in Proceedings Iron Ore 2013 , pp 487-494 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By B J. Beven, A Vatandoost, J Young, S Campbell-Hardwick

The intrinsic value of iron ore depends on its physical and chemical characteristics. For example, silica and alumina are unwanted elements, downgrading iron grade and adversely affecting high temperature processing, attracting penalties in smelter contracts. For this reason, an informed knowledge of processing characteristics and product quality of the ore is valuable and cost effective during mine planning and processing.Ore variability is a significant factor that affects metallurgical behaviour and efficiency of ore processing equipment. Ore of sufficient chemical and physical quality needs to be modelled, mined, processed and usually blended. Feed and product assays are commonly used to assess potential ore upgradability. However, assays alone cannot be all informative of actual processing response given the variability of the physical properties of the ore.This study investigates the potential benefit of implementing a geometallurgical approach during the commissioning stage of the Kings deposit, part of the Solomon Iron Ore project in Western Australia. Kings drill hole database information, ie geological, textural and geochemical data, together with the results of metallurgical test work were used for geometallurgical analysis and modelling. Three main ore types were identified at Kings, namely channel iron deposit (CID), bedded iron deposits (BID) and Detrital Iron Deposit (DID). Additional classifications were utilised to better characterise these units in terms of their physical properties.Bulk sampling for each ore type was carried out across the deposit for metallurgical testing. Multivariate statistical models were developed for prediction of product quality for each geometallurgical unit. A new approach for modelling yield based on ore upgrade factors is introduced. These models were then applied to the Kings regularised mining model to assess product quality across the mining blocks and to plan product stockpiling and blending strategies.CITATION:Vatandoost, A, Beven, B J, Campbell-Hardwick, S and Young, J, 2013. A geometallurgical approach for iron ore product evaluation, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 259-266 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By Rabie A. S, Fouad K. M, Ammar A. A

The existence of Gabal El Kahfa ring complex, located in the Eastern Desert of Egypt, has been ascertained from aeromagnetic and aeroradiometric survey data as well as by aerial photography. Two maps for -the net aerial radiometric measurements reduced to ground level and aerial magnetic data corrected for the regional normal gradient of the earth's magnetic field have been constructed. The aeroradioactivity data have been interpreted geologically and analyzed statistically to outline various radiometric units and compute their charac- teristic statistics. The ring complex showed a circular radiometric feature and yielded a radiometric mean background and a standard deviation of 6.48 and 0.89 pR/h respectively. Besides, the observations showed a normal distribution. The aeromagnetic data have been reduced to the north magnetic pole, then filtered to produce the regional-and residual-component maps. Statistical trend analysis was conducted for the tectonic linea- ments resulting from the three magnetic maps, to define the structural framework of the area under study. This statistical study proved the exis- tence of trends in the east-west, northwest-south- east, northeast-southwest and north-south directions. The ring complex is characterized by a circular magnetic feature, whose average relief is 2150 nT. It is included within a high east-west trending magnetic zone. The latter represents a deep-seated uplift or anticline which is bordered from all sides by some faults of different trends.

Jan 1, 1988

By C Zschiesche, alam, A Abadias Llamas, A K

Lead has the ability to collect and carry valuable metals such as copper, bismuth, antimony, tin and precious metals for their downstream recovery. Therefore, lead metallurgy is key for the raw material supply that our society demands. Lead smelters, excluding lead-acid battery recyclers, tend to process more complex primary and secondary raw materials, which are mostly processed via the pyrometallurgy route. Accordingly, understanding the slag system of these metallurgical processes is key for the efficient industrial operation and recovery of minor elements. Glencore Nordenham is an integrated lead and zinc smelter in northern Germany with a production of 92 000 t of lead and 164 700 t of zinc in 2022. The lead production line processes complex leadbearing raw materials through the direct smelting process. Firstly, the feed mix is smelted in a Top Submerged Lance (TSL – Ausmelt®) furnace, where a lead bullion containing minor metals and a lead-rich slag are produced. Then, the lead-rich slag from the TSL is tapped (via launder) into a Side- Blown Furnace (SBF), where lead oxide is reduced to produce lead bullion (with minor elements) and discard slag. The lead bullion from both stages is refined to produce lead (>99.9 per cent) and recover the minor elements (Cu, Ag, Au, Sb, Te, Bi etc). This paper reflects the experience of operating the SBF after the first five years of operation and describes its ‘PbO-SiO2-FeOx-CaO-ZnO’ slag system. Firstly, the slag system, the furnace operating region and the potential solid phases present are discussed from a theoretical point of view. This theoretical study has been performed using FactSage™ 8.2 and the database developed by the Pyrosearch group at the University of Queensland, Australia (UQPY). Then, the FactSage™ simulations are compared with industrial slag measurements. Finally, some examples on how the slag knowledge gained at Glencore Nordenham can help the industrial operation of the SBF are discussed.

Jun 17, 2024

By F Saloojee, F K. Crundwell

Refractory ores need to be pretreated prior to cyanide leaching for acceptable gold recovery. Pressure oxidation is one method of rendering the ores more suitable for cyanidation. The focus of this work is optimisation of autoclave configuration for pressure oxidation. An autoclave for the pressure oxidation of a feed containing pyrite and arsenopyrite was modelled, using the population balance framework. The autoclave model takes into account feed particle size, reaction kinetics and retention time. Mass balance calculations were incorporated into Cycad Process« software. This allowed for the investigation of different circuit configurations. The base case model consists of a single autoclave. The feed was then doubled and additional autoclaves were added to provide the same residence time as the base case. Four different configurations for the additional equipment were simulated. These were parallel, series, series with inter-stage thickening and parallel-series circuits. The options are compared in terms of extraction and productivity. The parallel circuit behaves similarly to the base case. The series and series-parallel circuits have higher recoveries and productivities than the base case. The series circuit with inter-stage thickening provides the highest extraction and productivity. This is because the thickening reduces the slurry volume and increases the residence time of the solids in the downstream autoclave.CITATION:Saloojee, F and Crundwell, F K, 2013. Optimisation of circuits for gold pressure oxidation, in Proceedings World Gold 2013 , pp 181-188 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By G H. Park, Y J. Jun, J H. Park

The carbon solubility of the CaO-Al2O3-FeO-SiO2-MgO slag, the main system formed in the Ruhrstahl-Heraeus (RH) vacuum degasser, was measured at 1873 K to understand the effect of slag compositions on the carbon contamination in the ultra-low carbon (ULC) steels. The stable form of carbon was demonstrated to be carbonate by plotting the log [(wt%C)/aC] ratio against the log p(O2) which ranged -11 < log p(O2,atm) < -9. The carbon solubility of the CaO-Al2O3-FeO-SiO2-MgO slag can be estimated using thermodynamic model. The distribution ratio of carbon increased with increasing concentration of FeO due to the FeO reduction reaction and increased basicity of slag. The carbonate capacity of the CaO-Al2O3-FeO-SiO2-MgO slag can be expressed as a linear function of the activity of lime and the optical basicity.

Jun 19, 2024