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By M Lak, R Amiri, A Haratian, M Asghari, S Haji

In recent years, due to advances in designing of various magnet assemblies, a wide range of magnetic materials with different properties can be concentrated. Jalal Abad iron ore beneficiation plant, which is located in Iran, Kerman province, is currently producing iron ore concentrate with the capacity of 0.8 Mt/a by having medium intensity magnetic separators (MIMS) with rougher and cleaner stages that finally leads to the production of an iron concentrate with the Fe grade of about 65 per cent. In this plant, the rougher tailings directly goes to the thickener as the final tailings and cleaner tailings feeds to the ball mill for regrinding. Since some hematite particles with weak magnetic properties cannot be recovered from only these two stages of magnetic separation, the obtained tailings from this concentration plant has approximately an iron grade of 25 per cent to 27 per cent. Accordingly, laboratory processing tests were conducted on the obtained representative sample of the final tailings. Based on the experimental results performed on final tailings, a new magnetic drum separator with a specific magnetic assembly was designed that could finally lead to product with iron grade range of 58 per cent to 60 per cent with relative and total weight per cent of 8.6 per cent and 3.86 per cent. Finally, it could be concluded that feeding of magnetite particles to the existing drum separators, due to their high magnetic field intensity, cannot efficiently lead to improvement of the grade of concentrate. Therefore, pilot magnetic separation tests were done on the final concentrate for evaluation of product upgrading probability. Consequently, by increasing another stage of cleaning and by decreasing the magnetic field intensity, the final product grade could be enhanced from 65 per cent to 67 per cent.

Nov 8, 2021

Nine case studies are presented to illustrate how risks can be, minimised or quantified during pit optimisation, utilising Whittle Four-D software. Each case study covers a specific problem that has been encountered from a wide variety of pit optimisations. Case A: Maximising profits when the tenement owner is paid a royalty on tonnes processed. Case B: Allocating product prices, rather than a single commodity price during optimisation. Case C: Quantifying processing costs that are affected by penalty elements in the ore. Case D: Exploration expenditures below current pits can be quantified through the use of simulation techniques. Case E: Alternative strategies can be quantified when pits are restricted by tenement boundaries. Case F: Relocation of mine infrastructure that requires large capital expenditures, can be simulated by allocating costs to an area during optimisation. Case G: Evaluating alternative corporate strategies during pit optimisation. Case H: Sensitivity analysis for price, processing cost and mining cost. Case I: Quantifying the advantages of using additional mining capacity during the early periods of mining.

Jan 1, 1994

By A Giyose, V Malysiak, K Davey

Batch flotation tests were conducted on a haematite-bearing Sishen iron ore slimes sample from South Africa using reverse cationic flotation. The effect of grinding on flotation performance, the flotation response of various key impurities in the sample, and the feasibility of increasing metal recovery by refloating tailings in a scavenger flotation step were investigated. The test results indicate that reverse cationic flotation is effective in rejecting impurities from the iron ore sample tested. From a head grade assaying 6.4 per cent SiO2, 2.14 per cent Al2O3, 0.402 per cent K2O, 0.082 per cent P and 0.194 per cent TiO2, the levels of impurities were reduced to 1.83 per cent SiO2, 0.88 per cent Al2O3, 0.095 per cent K2O, 0.066 per cent P and 0.174 per cent TiO2 in the final concentrate at a Fe recovery of 74 per cent. The flotation response of SiO2, Al2O3 and K2O were found to be better than that of P and TiO2. The testwork demonstrated that grinding to 80 per cent passing about 49 microns is essential for upgrading the Sishen iron ore to produce >67 per cent Fe concentrate grade. This grind size corresponds to about 80 per cent liberation of haematite from the gangue minerals. Fe recoveries up to 76 per cent were obtained by refloating the rougher tailings in a scavenger stage, with little effect on the final concentrate grade. Size-by-size Fe recovery data obtained indicated that particles below ten microns were mostly lost in the desliming stage conducted prior to flotation whilst some reported to the froth by entrainment. Some of the coarser haematite-gangue composite particles reported to the froth product by genuine flotation.

Jan 1, 2009

By Gray E, Banks J

In mine site revegetation, exotic grasses are more commonly used than native grasses. This is due to unavailability of native grass seed on a commerical scale and lack of information on agronomical aspects of native grasses. This paper lists a number of native grass species that have the potential to grow well on mine sites, and provides some information on their seed collection, processing and germination. Further, it demonstrates via results of a field trial conducted at Ranger Mine spoil the relative performance of ten native grasses and Rhodes grass. It is concluded that (i) some native grasses have similar ability to grow on mine spoils compared to Rhodes grass and (ii) the use of native grasses have added advantages in ecosystem restoration.

Jan 1, 1994

By S Robinson, A Turner, R Dale, C Butler

"Sandfire Resources NL- (‘Sandfire’) DeGrussa definitive feasibility study (DFS) identified geometallurgy as a major factor in achieving optimum plant performance at the DeGrussa mine. A geometallurgical initiative was created to proactively investigate this issue, and a key initial achievement was the 2013 paper by Condon et al (2013) on developing a working geometallurgical model from first principles. Significant advancements in Sandfire’s geometallurgical understanding since that publication now shape how information is presented and communicated.The main geometallurgical parameters so far identified as critical factors affecting plant performance are Cu:S ratio, iron sulfide mineralogy, talc carbonate content and sphalerite content. Apart from specific mill strategies, geometallurgical issues have been managed through communication between departments and strategic run-of-mine (ROM) pad management.This paper uses the current theories of geological evolution of the volcanogenic massive sulfide (VMS) deposit at DeGrussa, to discuss the variability between the orebodies C1, DeGrussa (sea floor mounds) and C4, C5 (sub-sea floor replacement) to highlight the different issues each orebody is expected to encounter when processing.A zone of altered low-grade mineralisation surrounds the main orebodies at DeGrussa, referred to as a halo. Talc minerals are often patchy within this halo and often cause significant recovery issues during processing. This halo has been successfully modelled using MgO as a proxy. The ability to model the talc material assists with both identifying potentially problematic zones for processing and geological interpretation of the ore deposits evolution.Early in geometallurgy studies at DeGrussa it became apparent that it would be useful to identify processing performance prior to mining. This necessitated the incorporation of specific sulfide species into the mining block model. These attributes are interpolated from the logged sulfide estimates allowing a clear picture of the abundance of each mineral type within a defined area.In conjunction with the block model a geometallurgical factor (GMF) graph was developed, identifying sulfide mineralogy based upon mineral assays. These two recent additions to the model provide a clear picture of the nature of the ore sources that will be presented to the processing plant.The future of geometallurgy at DeGrussa will see these tools used to aid mine scheduling with a view to further improve processing recoveries.CITATION:Butler, C, Dale, R, Robinson, S and Turner, A, 2016. Geometallurgy – Bridging the Gap between Mine and Mill: a Case Study of the DeGrussa Geometallurgy Program, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 77–88 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By K Ionkov

The oolitic iron ore reserves in Lisakovsky, North Kazakhstan represent quite a challenging deposit both from a technological and from a resource point of view. The difficulties in processing such types of ore are connected with the extremely fine dissemination of phosphorus and gangue minerals inside the oolitic formations. The goethite crystals are cemented in their structure by aluminosilicates with quartz and other gangue minerals and dissemination is so fine that they are not separable by physical methods. The laboratory tests performed for dephosphorisation show that the combination of alkaline roasting followed by low intensity magnetic separation and acid leaching enables the obtaining of high grade iron concentrate. The magnetic separation performed ahead of leaching is effi cient as a means of buffering the high pH by washing out the soluble salts and the excess of base and after leaching facilitates the removal of secondary liberated gangue minerals in the non-magnetic fraction. As a consequence, phosphorous content is dropped to a more acceptable level for the ferrous metallurgy and iron grade and recovery reach 61.6 and 80.8 per cent respectively.

Jul 11, 2011

By Marshall GA, Dickerson AW

The efficient operation of large haul trucks in large open pit mines requires an economic trade off between the haul route quality, the haul truck payloads and the level of haul truck reliability. This paper describes an investigation into the relation- ship between haul route surface quality and the level of structural reliability of a haul truck main frame. An instrumentation system for unattended recording of data on a haul truck operating normally in a mine and com- puter based analytical procedures were developed and used to identify which road segments contribute significantly to fatigue cracking at various sections of a haul truck main frame. INTRODUCTION In many open pit mines there is exten- sive use of large haul trucks to move over- burden and minerals. In most open pit hard rock mines, both the overburden and mineral ore are moved by large rear dump type haul trucks. Similar haul trucks are also widely used for coal overburden and mine site coal haulage operations in New South Wales, South Australia and Western Australia. Large bottom

Jan 1, 1982

Atlas Copco is one of the worldÆs leading providers of industrial productivity solutions (Atlas Copco, 2009). Furthermore, the company spans 160 markets and held 34 000 employees at the end of 2008. The company is organised under three ætechniquesÆ whereby the Construction and Mining TechniqueÆs business division is located within +rebro, Sweden. This paper is aimed at briefly facilitating information on how the company and more specifically, the Construction and Mining Technique is run. Also, by sharing my experiences, this paper is intended to encourage and motivate students currently studying for a degree relevant to the minerals industry, to apply for this extremely beneficial scholarship. Through a number of presentations relating to the various divisions, products and aftermarket services of the company, I came to realise that Atlas Copco extends beyond simply selling equipment suitable for the mining and civil industries. This tour through Sweden also contained highlights of visiting the Underground Rock Excavation factory, Surface Drilling Equipment factory and Secoroc divisions. I was also fortunate enough to participate in a tour of the LKAB mine in Kiruna. In addition, time was allocated to less industry related activities, and I was able to go dog sledging, sip vodka cocktails out of ice glasses at the Ice Hotel and enjoy traditional Swedish foods of moose and reindeer. Most important and memorable to me; however, was the ability for employees of Atlas Copco to speak of the company and their products with such passion and enthusiasm, which truly made this a motivational and unforgettable experience.

Jan 1, 2009

By Chaturvedula V. K

Pillar extraction carried out using various methods (split and lift, Wongawilli and Old Ben) involves the formation of narrow fenders (commonly 7 m of coal) formed by driving "splits" for lifting off with a continuous miner. The strata above a split and fender adjacent to the goaf consists of a cantilever beam (usually >3 m thick) that extends from the solid coal and bridges across the fender. Lifting off the fender from the split in safe conditions depends upon the bridging capability of the cantilever and the fender strength. The nature and competence of the immediate and near roof, the support capability of the coal fender and the presence of faults and or joints can adversely affect the bridging behaviour of the cantilever. Insufficient knowledge of these parameters can lead to extraction under dangerous conditions. Remnants of fenders ("stooks") also support the cantilever and their dimensions are critical to obtain regular caving and goaf falls. Stook area, goaf roof span and roof stand-up time after lifting can be related and only a relatively small increase in stook area of 10-15 m2 can lead to a significantly increased stand-up time, especially under a massive roof. Such conditions strongly influence the re- distribution of abutment stresses and can create increased outbye pillar loading. Based on detailed underground geotechnical investigations, it is concluded that strata caveability, roof cantilever behaviour, fender H:W ratio and remnant stook size are all critical parameters for successful and safe pillar extraction.

Jan 1, 1992

By J J. Hanhiniemi, M S. Powell

A ‘Variable Blend and Rates’ model is developed for SAG mills which extends upon the JKSimMet® Variable Rates Model. Similarly, a ‘Variable Blend Residence Constrained Perfect Mixing’ Ball Mill model is also introduced, also extending upon the existing JKSimMet® model. These models are used in conjunction with JKSimMet® while employing external technical programs. The technical model is then used to inform an economic model described elsewhere in Hanhiniemi and Powell (2022), which calculate operating and unit costs based on operating conditions, design, and ore characterisation. The SAG and ball mill models include constraints beyond those in the JKSimMet® models. The SAG model constraints include Size Specific Energy (SSE) verification, charge weight limit, and assessment of the impact of media to ore composition in the charge using the SAG Charge SSE Model developed in this paper. The ball mill model includes residence time, volumetric capacity, and SSE verification constraints. These models are applied to Cortez Gold Mine in the processing of two very different ore types and their blends; ‘Horse Canyon’ which is softer in coarser sizes and competent is fine sizes, and ‘Wenban’ which is competent at coarser sizes but softer in fine sizes than Horse Canyon. Horse Canyon also has a finer run-of-mine size distribution then Wenban. The application of the model at this site included undertaking five surveys at varying blends. The behaviours of the blends and individual components is then studied in the SABC circuit. A nonlinearity is observed with throughputs increasing with blending. The newly developed modelling approach captures these responses. Controlled blending based on ore competence-by-size and size distribution was implemented by the site, which then realised significant improvements in throughput without any capital cost (Ntiamoah et al, 2020). The modelling developed in this paper is then compared to existing practice, and the new method was found to provide improved fidelity and utility. A three-dimensional surface is then developed using the model describing the SAG mill throughput capacity at varying conditions (speed-filling) versus varying blend. The change in throughput as a function of only the changing charge composition is presented. The result is nonlinear, and explanations are provided to describe this behaviour.

Aug 24, 2022

By Lemberg D. W, Friday R. G

Potential means of lowering overall costs to permit deeper stripping include : 1. the use of larger diameter blastholes in highly-fissured strata (to reduce drilling costs); 2. dewatering from semi-permanent bores to reduce blasting costs (by maximising the use of bulk ANFO) and promote highwall stability; and 3. the use of inclined blastholes, bulk AN, staggered V1 patterns, adequate backfill and more cost-effective stemming columns. Each of these is covered. The pumping of bulk watergels continuously raises the blasthole water column, thereby perpetuating the demand for these blasting agents. This must be a principal consideration when choosing between a bulk and a packaged watergel. Any packaged product should exhibit dimensional permanence and an energy yield per metre length equal to that of bulk ANFO. Possible ways in which controlled trajectory blasting (CTB) could benefit deeper stripping operations are outlined. By allowing the maximum use of bulk ANFO, de- watering may be a prerequisite of a viable CTB Operation.

Jan 1, 1981

By K Hortin

Kidd Creek mine in north western Ontario is developing phase 1 of the deep mine project for mining between 2100 m and 3100 m below surface. Heat problems were experienced during the 2003 summer in working places about 2300 m below surface. At the time the mine had a æcold stopeÆ for cooling the air supplied to the mine below 1500 m from surface. The æcold stopeÆ is where during winter, ice is created in both the open pit and its connecting airways to the mine and used to cool air in summer. The operation and limitations of the existing cold stope were evaluated and led to the requirement for additional mechanical cooling to be available for the summer of 2004. The first stage of a surface refrigeration plant providing 7.5 MWR of cooling was approved, the compressor set was ordered in early January 2004 and the plant commissioned six months later in early July 2004. Based on the current modifications to the mining plan, further plant expansions are required in 2006 and 2009 leading to a total of 19 MWR of mechanical refrigeration and 8.5 MWR equivalent from the extended cold stope. The refrigeration system is described with emphasis on the specific adaptations necessary to suit Canadian conditions. Additional investigations were; using the refrigeration compressors in winter for heating and, extending the performance of either cold stopes or alternative ice storage systems. The winter use of refrigeration involve removing heat from the mine exhaust air to provide a cooling load and to use the hot water in the condensing circuit to heat the intake air and reduce reliance on mine air heating with natural gas. This paper follows on from an earlier one presented at the Seventh International Mine Ventilation Congress where the background and planning of the mine ventilation and cooling requirements were described for extending the mine at depth to 3100 m.

Jan 1, 2005

By S Jahanshahi

In an earlier LCA study, the authors showed that the electricity consumption of the electric furnaces used in the production of the ferronickel and ferrochrome feedstocks made significant contributions towards the Gross Energy Requirement (GER) of stainless steel production, on a æcradle-to-gateÆ basis. Given the relatively low efficiencies associated with electrical power generation, substantial reductions in the GER for stainless steel production could be anticipated if more direct use of thermal energy was made in the ferronickel and ferrochromium smelting stages.In view of these findings, a follow-up study was undertaken to investigate the likely environmental benefits of using bath smelting processes for the production of ferronickel and ferrochromium compared to the traditional rotary kiln-electric furnace processes, but still utilising the electric furnace process for stainless steel production. The METSIM process simulation software package was used to set up models of the two bath smelting processes and provide process energy requirements that were incorporated into the LCA. The environmental impacts considered in the LCA were greenhouse (Global Warming Potential, GWP) and acid rain gas (Acidification Potential, AP) emissions and solid waste emissions.The results of the study showed that the bath smelting route reduced the GER for ferronickel production by about 37 per cent over the traditional route, which translated to about a 21 per cent reduction in the GER for stainless steel. The corresponding reduction for ferrochromium was about half that for ferronickel, and when combined with the ferronickel result gave a 25 per cent reduction in the GER for stainless steel production. Similar reductions were also observed for the GWP and to a lesser extent the AP for both feedstocks, as all primary energy inputs were essentially fossil fuel based. Substantial reductions in solid waste emissions were also indicated for the direct use of ores in smelting. By utilising bath smelting processes for the production of the ferronickel and ferrochromium feedstocks, stainless steelÆs suitability for meeting many of the goals necessary for sustainable development, already recognised because of its particular properties, would be even further enhanced.

Jan 1, 2004

By M I. Pownceby, S Bhargava, F Charalambous, S McMaster, R Ram, J Tardio

"A key component of any geometallurgical investigation involves being able to predict element or mineral recoveries from simplified input data such as bulk chemistry and/or mineralogy. This relies on the metallurgist having access to accurate information regarding the chemistry of the ore and gangue minerals as well as the likely impact on processing/extraction caused by the impurities (present either as gangue or as substitutional impurities). In this study the chemical properties of two commercially important uranium minerals, brannerite (U4+Ti2O6), and uraninite (U4+O2), were characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Significant levels of impurities were present in both samples with the uranium minerals deviating significantly from their ideal chemical formulae. Differences in chemistry were due to: cationic substitution decay of the uranium isotopes into radiogenic lead and other daughter products mixed uranium oxidation states post-depositional alteration.As well, the brannerite sample showed evidence of significant radiation-induced metamictisation. Leach tests to measure the ease of extraction of uranium from both samples were conducted over a wide range of conditions (temperature, acid concentration and oxidant concentration). For uraninite, the lower U dissolution rates observed in the natural sample compared to a synthetic UO2 sample were directly attributed to the presence of impurities. For brannerite, significant metamictisation of the natural sample led to enhanced U extraction rates compared to a heat treated fully crystalline sample. This study highlights the importance of detailed mineralogical characterisation studies in any uranium process mineralogy investigation as the compositional, textural and microstructural aspects of the main uranium phases present will likely play an important role in any process to extract uranium.CITATION:Ram, R, Charalambous, F, McMaster, S, Pownceby, M I, Tardio, J and Bhargava, S, 2013. Chemical and microstructural characterisation studies on naturally occurring uranium minerals - implications for processing, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013, pp 325-334 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 29, 2013

By M Pernechele, U König

Most of the operating steelmaking capacity currently relies on conventional, coal-based steelmaking processes. Currently, direct reduced iron (DRI) is only produced in regions where energy is available at low cost. To align with net-zero emissions goals, steelmaking capacity must transition to loweremissions steelmaking technology. Direct reduction of iron ore will get one of the preferred methods in the future due to its high technology readiness. New reduction technologies include hydrogenbased direct reduction processes. To ensure optimal efficiency during DRI production and to cope with newly developed technologies, processes need to be monitored more frequently and accurate. Traditionally quality control of raw materials and DRI has relied on time consuming physical testing, wet chemistry or the analysis of the elemental composition. The mineralogy of DRI that defines its properties is not frequently monitored. Process monitoring and quality control of DRI is possible by using modern X-ray diffraction (XRD) methods. In addition to the metallic iron content (Femet), metallisation (Metn) and the total carbon content (Ctot), XRD analysis also identifies the overall mineralogical phase composition. This allows additional information about the reduction process and enables fast counteractions on changing raw material mixtures. The benefits of the quantitative determination of the phase composition and the calculation of process critical parameters to produce DRI will be demonstrated with a case study

Sep 18, 2023

By S Hapugoda, J R. Manuel, X Cao, B D. McDonald, N A. Ware, L Lu

Roy Hill is a large iron ore mining, processing, railing and port operation in the Pilbara region of Western Australia. Since delivering its first shipments to customers in December 2015, Roy Hill has quickly achieved a 60 Mtpa production rate of lump and fines products. The process plant, principally consisting of wet scrubbing, screening and de-sanding unit processes, was expanded from early 2020 to include operation of a Wet High Intensity Magnetic Separation (WHIMS) Plant. The WHIMS Plant treats tailings to recover approximately 4 Mtpa of ultra-fine (nominally -150 μm) high-grade hematitic concentrate which, after dewatering, is blended into the fines product. Unlike typical hematite concentrates, which consist largely of dense particles with smooth surfaces, the WHIMS concentrate is characterised by very finely microporous hematitic/goethitic particles, reflecting the overall characteristics of the Roy Hill deposit. Detailed test work has been conducted in collaboration with CSIRO to characterise the WHIMS concentrate in terms of its physical and mineralogical properties, and to determine its influence on the granulation and sintering performance of Roy Hill fines – from fundamental/lab-scale and sinterpot perspectives. The results demonstrate that blending of the high-grade hematitic Roy Hill WHIMS concentrate into the fines product can maintain overall sinter quality and positively influence granulation and sinter melt formation, as well as Fe grade.

Nov 8, 2021

By L Klemettinen, A Jokilaakso, D Attah-Kyei, P Taskinen, M Tiljander, D Sukhomlinov, D Lindberg

In this study, the use of carbon neutral biochars as reducing agents in the pyrometallurgical treatment of nickel slag was investigated at 1400°C in order to recover valuable elements such as copper and nickel from the slag. A large amount of slag is generated during the nickel matte smelting. Nickel slag contains valuable elements such as copper, nickel and cobalt, which can be recovered. Disposal of this slag results in loss of resources and may cause pollution of the environment. It is important to retrieve these metals for environmental and economic reasons. In this study, the slag was reacted with non-fossil reducing agents (biochar) which were produced from hydrolysis lignin and black pellet biomass pyrolyzed at 600 and 1200°C and with metallurgical coke for comparison. The reduction experiments were done at 1400°C for 15, 30 and 60 mins under inert gas atmosphere. The samples were quickly quenched and analysed with Electron Probe X-ray Microanalysis (EPMA). The results showed that the use of biochar resulted in faster reaction kinetics in the reduction process compared to coke. The fast reaction kinetics is attributed to the relatively high content of volatiles in this biochar, leading to gas formation and thus mixing of the sample material. Moreover, thermodynamic modelling was also performed using FactSage™ to simulate equilibria with different amounts of biochar. The metal to slag distribution coefficient calculated from the results of thermodynamic modelling were consistent with experimental results. In addition, thermodynamic calculations confirmed that nickel is reduced rapidly and it deports to the metal alloy phase. As the reduction progresses or extra reductant is available for reactions, more iron is deported to the metal phase. The calculations also revealed that Zn vaporises into the gas phase.

Jun 19, 2024

By E S. Weiss, S P. Harteis

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) has conducted full-scale explosion experiments, to evaluate the strength characteristics of various seal designs, used for safely isolating worked-out areas in underground coal mines. Large-scale explosion tests conducted within the multiple entry section of PRLÆs Lake Lynn Experimental Mine (LLEM) is currently the only accepted test method used by the Mine Safety and Health Administration (MSHA), for deeming a seal design suitable for use in American mines. These explosion tests are labour intensive, expensive to conduct, and can interfere with other critical underground safety and health research programs conducted by NIOSH. The PRL has developed an alternative seal evaluation method, based on a hydrostatic pressure loading concept, that can facilitate the in situ testing of seals in an operating mine. Two chambers within LLEM and one within PRLÆs Safety Research Coal Mine (SRCM) were used for hydrostatic pressure loading various seal designs. The results from these chamber tests compare favourably with those from the large-scale explosion tests in the multiple entries. In addition to testing seal designs at the required 20 psi static pressure level, the chamber test approach also allows for the determination of the sealÆs ultimate design strength. Size-scaling relationships for predicting the strength of seal designs as a function of entry size are also presented.

Jan 1, 2005

By S McKnight, L Koroznikova, S Hall

Mineral sands represent an important new resource being developed in the Murray Basin, including parts of western Victoria. This paper will outline a simple methodology for mineral sands characterisation, developed as part of the AMIRA-managed project P777 æThe Development of Heavy Suspension Techniques for High Density Separations (Replacement of ClericiÆs Solution)Æ. This project is currently sponsored by three multinational mining companies (De Beers Consolidated Mines, Iluka Resources Limited and Rio Tinto Limited) and is developing an innovative laboratory mineral characterisation procedure that will allow the replacement of the currently employed highly-toxic chemicals.Mineral sand resources almost always contain more than one valuable (and relatively heavy) mineral. Titanium minerals are found with a large range of titanium contents, giving rise to density variation and often subjective mineralogical descriptions. Companies tend to rely on laboratory heavy liquid separation in the evaluation of samples arising from exploration, mining or metallurgical processes. Unfortunately, there are only a limited number of high density (æheavyÆ) liquids and these tend to be more toxic as their density increases. Low-toxicity inorganic solutions, based on tungsten compounds, have been developed that can be utilised at relative densities (RD) up to 3.0. However, beyond this value currently only organic liquids can be used. Diiodomethane (methylene iodide) having a relative density of 3.31 is commonly used; however, this presents significant health and safety hazards. Mixtures of thallium formate and thallium malonate were found in the early 1900s by Clerici to provide liquids having specific gravities between 4.0 and 5.0, hence æClericiÆs solutionÆ. For the characterisation of the heavy components of mineral sand deposits (eg anatase sg 3.9, rutile sg 4.2, ilmenite sg 4.4 û 4.7 and zircon sg 4.6 û 4.8) there is currently no heavy liquid alternative to ClericiÆs solution. ClericiÆs solution is highly toxic and testing is now conducted by very few laboratories worldwide with costs reflecting the chemical costs (though extensive efforts are made to recover and reuse the liquid, plus the requirement of its removal from the mineral samples), the infrastructure costs and health and safety regimes (eg blood testing of exposed staff, inventory management). A simple laboratory technique of density fractionation is being developed, employing suspensions of fine tungsten carbide particles in lithium heteropolytungstate (LST) solutions, that can replace ClericiÆs solution in the evaluation of fine mineral sands samples (eg -250+150 microns). The developing methodology that can achieve low-cost, low-toxic separations at relative densities above 5.0 will be outlined and the comparison of results with ClericiÆs solution presented.

Jan 1, 2006

The continuous casting of zinc alloys has been of fundamental importance for many years in the production of a number of products, including sheet for architectural applications, battery cans for dry cells and wire for metallising. The intrinsic benefits of continuous casting, including efficiency and high tonnage capability, uniformity of metallurgical structure and properties, and absence of voids and other defects, have contributed to the success of these products. Less well known, but of growing importance, is the more recent application of continuous casting technology to the production of zinc alloy bar stock products, including bearing stock, machining bar stock, forging stock and cathodic protection anodes. A wide range of zinc alloys are now continuously cast in a variety of cross sectional shapes and sizes to suit the diverse characteristics of these products. Of particular significance are the introduction of hollow zinc-aluminum bearing stock, and the availability of zinc alloy machining bar stock for hydraulic applications and for producing prototypes of zinc alloy pressure die castings. In addition to the traditional benefits, continuous casting provides special properties which are important in the application of these bar stock products. The list of successful applications of continuously cast zinc alloy bar stock is growing rapidly, and the market potential for resultant new zinc applications appears to be significant.

Jan 1, 1993