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By H. J. Wu

The optimum performance in mineral processing plants usually demands the optimum size reduction, which is frequently achieved by a closed grinding circuit. Due to the difficulty associated with fine size classification, the size separation efficiency in closed grinding circuit is usually very low, which leads to huge circulating load and significant overgrinding. Recent development of Der-rick Stack Sizer has made an efficient fine size separation down to 200 mesh with a satisfactory screening capacity. With the efficient fine size separation with Derrick Stack sizer, the problems commonly associated with typical closed grinding circuit, including high circulating load and over-grinding, have been eliminated. Feedback from numerous Stack Sizer applications in iron ore industry indicated that, compared with conventional fine size classification equipment, the circulating load achieved by Derrick screen was usually decreased from approximate 300% down to 60% or so, while the iron recovery has been increased by 6% to 8% only by more efficient size separation in the closed grinding circuit. To study this phenomenon, this paper discusses the relationship between size classification, circulating load and mineral recovery in the closed grinding circuit. A simulation model to predict the improvement in the grinding circuit from more efficient screening is also introduced with this paper.

Jan 1, 2014

With shortage of sulfide nickel ores, laterite ore was paid more attention by scientists. Because its grade is commonly lower than sulfide nickel ores, laterite ore can not be utilized effectively be-coming the bottleneck of study. Leaching laterite ores from Yuanjing, Yunnan province, organic ac-ids show better selective than sulfide acid in nickel and cobalt recovery. Organic acid has low de-pendent on pH, keeping leaching capability even higher than 3. On the other side, when pH up to 2, sulfide acid can not leach laterite ores any more. After four kinds of organic acid leaching laterite ores, besides citrate, malate and succinate have good leaching and effectively selective capability. Especially, succinate has the best selective leaching capability of nickel and cobalt in four kinds of organic acids for latter anion purification and separation. Isolated from waste water with sugar, Aspergillus niger (zs1) has great capability to produce organic acids and vigorous growth. Laterite ores have been respectively processed by direct-leaching and indirect-leaching. Indirect-leaching gives a better result than direct-leaching. Extraction of nick-el by indirect-leaching reaches 44.3%, far more than that of direct-leaching. Moreover extraction of nickel at pulp density of 5% is higher than that at pulp density of 10%, reaching 63% in 11 days and extraction of cobalt also is 48.1% in the same period. Compared with nickel and cobalt, iron gives low extraction in solution, containing organic acids produced by Aspergillus niger .

Jan 1, 2014

By Yuexin Han

The wet preconcentration of haematite, comminuted by high-pressure grinding roller was studied, using the cylindrical ferromagnetic medium. The effects of various factors including rod diameter, rod gap and background magnetic field intensity (BMFI) on the performances of preconcentration for different size fractions and the force analysis of single mineral particles with different diameter in the separation zone were emphatically investigated. The results showed that as the rod diameter increased, the rod gap decreased, and the BMFI increased the tailings grade and the tailings yield reduced while the concentrates recovery raised that was regardless of variations in feed size distribution. For the -3.2+0.18mm size fraction preconcentration, the magnetic medium with a rod diameter of 4 mm and a rod gap of 7 mm at BMFI of 454kA/m is used to get a higher performance. For -0.18mm size fraction preconcentration, the magnetic medium with a rod diameter of 4 mm and a rod gap of 4 mm at BMFI of 263kA/m is used to get a higher performance. After the classifying preconcentration, at the optimum condition, the overall concentrate grade increases by 9.56 percentage points and the concentrate recovery is up to the 82.67% with a tailing grade of 10.68% and a tailing yield of 40.31%. The magnetic force, exerted on weekly magnetic minerals was proportional, to the specific susceptibility and square of BMFI. For the same BMFI, the magnetic capturing force on coarse particles increased, and that on fine particles decreased with the increasing of rod diameter. For the lean locked-particles, considering the gravity and viscous resistance of particles, rods with a big diameter were beneficial to the capture of coarse particles and had no influence on the capture of fine particles, while rods with a small diameter were good for the capture of fine particles and not suitable for the capture of coarse particles of lean locked-particles. Keywords: low grade haematite, high-pressure grinding roller, high intensity magnetic separation, pre-concentration

Sep 1, 2012

By Y. B. Zhang

China is rich in iron ore resources, but most of these ores are low-grade, polymetallic and refrac-tory ones. Furthermore, with the rapid development of chinese iron & steel industry, the comprehen-sive recovery of these ores is becoming more and more important. The tin, zinc-containing complex iron ores are typical polymetallic and intractable ones, and great reserves of them are found in China. At present, they have not been efficiently utilized. In this paper, based on the investigation of basic physicochemical properties of the tin, zinc-bearing iron concentrates, taken from a mineral processing plant, the mineralogy reason that these concentrates are so intractable and refractory is found out, using advanced microscopic testing methods, such as optical microscope (OM), Scanning Electronic Microscope (SEM), X-ray diffrac-tion (XRD), etc. It is found that the symbiotic relationship of iron, tin and zinc metallic minerals are very complicated, and magnetite in the concentrate is closely symbiotic or enwrapped by fine cassi-terite and sphalerite. So it is difficult to separate tin and zinc completely from the iron concentrates by simple regrinding and physical separation method. This investigation provides theoretical guid-ance for developing new approaches for utilizing these concentrates.

Jan 1, 2014

By Xing Yang, Zhen Peng, Guangwen Zhang, Haifeng Wang, Yaqun He

"Triboelectric separation of ilmenite ore based on the tribocharge differences between ilmenite and gangue minerals was conducted in this study. Triboelectric characteristics of ilmenite and its associated minerals were studied using polyvinyl chloride (PVC), pentatricopeptide repeats (PPR), copper, polymethyl methacrylate (PMMA), stainless steel (SS), teflon and quartz glass (QG) tribochargers in lab triboelectric unit. Results demonstrated that the ilmenite particles tribocharged positively while gangue minerals tribocharged negatively using PVC as tribocharger. The particle size also has a significant effect on tribocharge, and the -0.125+0.074 mm is the optimal size fraction of triboelectric separation. Charge-mass ratios of minerals increase with the increases of tribocharging length, but the increasing rate gradually reduce. At 1.5 m tribocharging length, charge-mass ratios of ilmenite, quartz, feldspar and mica are up to 6.07 nC/g, -6.05 nC/g, -4.30 nC/g and -4.56 nC/g, respectively. Based on the triboelectric characteristics of each mineral, triboelectric separation of ilmenite was conducted, and the grade of ilmenite ore increased from 15.47% to 28.40%. INTRODUCTION As a transition metal titanium plays an irreplaceable role in medical, aerospace and materials due to its light weight, high strength and corrosion resistance. Pure titanium dioxide is an excellent white pigment and is widely applied in industries of paint and textile. Ilmenite is the main raw material for titanium industry. For the beneficiation of ilmenite, series methods have been proposed, such as the application of dry magnetic and wet gravity separations to separate the ilmenite from the zircon and rutile. Electrostatic separation is extensively used in the beneficiation of heavy mineral sands for the recovery of rutile, zircon and ilmenite while flotation is used to separate fine ilmenite (Mehdilo et al., 2014; Fan et al., 2014). Compared with flotation and gravity separation, electrostatic separation does not consume water, and native properties of materials will not be changed and energy consumption will be reduced (Wang et al., 2014). Thus, the wide application of electrostatic separation and other dry separation methods is a trend in separation and purification industry, especially in water-scarce areas."

Jan 1, 2018

By R. C. Dunne

A review of the current ?state of the art? of refractory gold treatment will be provided. This will include a global perspective of refractory processes past and present and the location of currently operating plants. Some discussion on the challenges that face the refractory gold industry will also be provided. Keywords: refractory gold treatment, flotation, roasting, pressure oxidation, bacterial oxidation, preg-robbing gold ores, fine grinding.

Sep 1, 2012

By Y. X. Yang

Bottom ash is a solid waste stream in a Waste-to-Energy (WTE) processing plant during the combustion of the municipal solid waste (MSW). In the Netherlands, bottom ash contains typically about 18% metals originated from the MSW, and current industrial practice could recover about 10% metals through magnetic and eddy current separators. The remaining 8% as the finer particles is difficult to recover through current physical separation technology. Among various alternatives, vitrification is one of the promising options to immobilize the ash and recover the remaining metals. During vitrification a homogeneous glassy slag and a Fe-Cu based alloy were obtained. In the cur-rent study, the metal alloy recovered from the bottom ash originated from a Dutch Waste-to-Energy plant contains about 82 wt% Fe, 12 wt% Cu and 6 wt% other alloying elements and impurities such as C, S, P, Ni etc. The generated alloy does not have direct commercial applications, and separation of copper from iron-based alloy is critical to obtain the market value of both copper and ferrous constituents. To find a suitable processing route of this metal alloy, various alternative approaches have been considered for an efficient removal of copper from the alloy, and the focus in the present study was on the sulphide treatment at elevated temperatures of 1400 ~ 1500oC. The tested sulphide systems include pure FeS, FeS containing sulphide mixture (such as Na2S and Al2S3), pyrite (FeS2) mineral, ZnS containing sludge as an industrial waste. It was found that the carbon saturation of the alloy is proved to be an essential condition for a proper phase separation. The results showed that FeS mixed with Na2S, ZnS containing sludge and pyrite are effective sulphide systems for copper removal with a removal efficiency of 92% by using pyrite and 95% by zinc sludge at a S/Cu ratio of around 7 times of the stoichiometry. The copper content drops from 12 wt% to about 2 wt%. However, it is still difficult to remove copper completely from the alloy in a single step, and a multi-step operation is needed. The present research is expected to contribute both to the utilization of the metal recovered from bottom ash, and to the general recycling of steel scrap where copper removal from the steel scrap is a critical issue.

Jan 1, 2014

By C. R. Mambote

One of the processes developed for vanadium recovery from the fly ash of crude oil is through acid leaching. In the process, iron is one of the impurities that should be removed before vanadium precipitation, due to the fact that iron tends to co-precipitate with vanadium. The mechanism of iron precipitation is understood in terms of ferric hydrolysis, followed by the dimerization and subsequent polymerization of the crystalline iron compound. In order to develop a new approach for the fly ash processing, in the present paper the precipitation of iron from the liquor after the leaching process was studied with addition of NaOH or NH4OH in the presence of H2O2 or Na2C2O4 at 80°C. The objective was to investigate the feasibility of the selective precipitation which could be applied to vanadium and nickel recovery from the fly ash. The experimental results show the difficulties of removing iron by precipitation without co-precipitating nickel and vanadium.

Jan 1, 2014

By E. A. Brocchi

This work is dedicated to the chemical treatment of a typical EAF dust by chlorine content agents. The residue contains 48% Fe2O3 and 28% ZnO mainly in the franklinite structural form. The others less compounds are: 4.00% CaO, 2.60% MnO, 2.20% MgO, 1.08% PbO, 0.36% Cr2O3, 0.21% B2O3, 0.03% CdO and 0.01% NiO. The experiments purpose is selectively to remove zinc from the residue leaving the iron behind. Thermodynamics studies have indicated some roasting possibilities. The experimental results have shown that both HCl leaching and carbochlorination will remove iron and zinc without any selectivity. However, either the chlorine or the calcium chloride roasting seems to form, preferentially, the zinc chloride. So, it will be presented how the EAF Dust can be treated by the using of chlorine roastings process such as carbochlorination in order to separate the zinc and iron present in the frankilinite, main EAF dust content.

Jan 1, 2014

By M. Wierink

The lifecycle of a resource, specifically a metal, is often depicted as circle from primary production from mining to minerals processing and via manufacturing and use to disposal and recycling. When a material is recycled, it is considered as saved energy compared to producing the material from primary source. This is, however, a simplified representation. At each step of the life cycle, there are changes in the quality of the material due to different materials chemical and physical interaction, phase transformations due to diffusion, radiation etc. Due to these physical and chemical phenomena there are losses of material, which as determined by thermodynamics are not recoverable within the life cycle. This can be considered as an increase embodied energy per mass unit of substance and loss exergy from the material cycle. With low cyclic loss, the material will remain in the recycling loop for a long time, while with high cyclic loss it will disappear fast. Where you put the material determines how fast it disappears from the resource cycle. In this research paper the phenomena of quality degradation of material and idea of increase of embodied energy and exergy loss within a resource cycles is portrayed. The cyclic nature of material states and transitions and energy consequences of material quality degradation as well as the parameters affecting the length of the time scales of the material cycles are described. Currently the cyclic embedded energy and the history of material is not taken under consideration in generic life cycle assessment. This easily results into a conclusion that lifetime of product is optimized only in terms of how much energy an appliance uses during its lifetime, while ignoring the loss of embedded energy due to the effects caused by the environs the material is subjected to during the cycle. Better description of the time properties of material give us a possibility to design toward optimum lifetime of products in terms of resource efficiency. Keywords: product lifetime, material lifetime, recycling, cyclic resource efficiency, material state, material quality, exergy, embodied energy

Sep 1, 2012

By Chris A. Fleming

"The ability to recover cyanide from gold plant tailings has been known almost as long as the cyanidation process has been practiced, but there has been little incentive to process tailings in this way in the past. With the development of technologies that make it possible to recover and recycle free or complexed cyanide directly from gold plant slurry tailings, which indicates, on paper at least, significant cost savings compared to cyanide destruction, coupled with the introduction of legislation to seriously limit the discharge of cyanide to the environment in most gold-producing regions of the world, many companies are evaluating the cyanide-recovery alternative.There is arguably an even more compelling reason for mining companies to consider cyanide recycling. With the growing storm of negative public opinion that the use of cyanide in the mining industry is attracting - following several highly publicized spills over the last couple of years - the time has come for the gold industry to demonstrate environmental diligence and stewardship in the use of this commodity that is so vital for their industry. There is no doubt that the widespread implementation of cyanide recycling will reduce the impact of the cyanidation process on the environment, both by reducing the risk of spills (with less cyanide being transported from manufacturing plants to gold mines), and by reducing the loading of toxic and nontoxic metals and ions in the tailings.This paper briefly discusses the pros and cons of the different processes that are available for the treatment of gold plant tailings to regenerate and recovery cyanide for recycling, and presents a techno-economic argument for the incorporation of this technology into many gold plant flowsheets today."

Jan 1, 2003

By L. A. Vaisberg

"Mining processing plants are the most high-performing industrial enterprises in the world economy system. Even at an average-scale mining enterprise, the grain-size separation equipment continuously processes 105 to 106 dissimilar mineral particles per hour. In separation by physical properties, their number increases by at least 10 to 50 times. Mathematical modeling of such a high flow of discrete particles is carried out using two different approaches: the discrete-particle and the phenomenological methods. The calculations demonstrate the possibility of handling big data when describing the processes of separation of granular material. INTRODUCTION The interest to the screening process and the process of formation of new screen designs in Mekhanobr is traditional since the moment of its foundation. It is symbolical that the first publication of the Mekhanobr proceedings in 1924 was the monograph dedicated to screens and screening products as such, which was the first one in the world at that moment. It was a book of Prof. L. B. Levenson, one of the founders of Mekhanobr, who headed the Technical Bureau of the Institute. Vibratory screening is the most mass process in the technologies of solid minerals processing, which determines significantly the energy demands of crushing and grinding cycles, and at some enterprises determines the quality of the final product, for example in case of crushed stone, coal or abrasive materials production. The general understanding and simulation of the process of poly-dispersed granular materials vibratory screening was developed at several conceptual levels taking into account the features of classification of materials with different size and density.Considering the real industrial processes of vibration screening, it shall be noted that at the sieve surface of the screen in the initial part of the deck the classification in a thick material layer (in natural conditions) occurs, which further transfers to a thin layer (free movement). In the process of screening of light minerals, for example coal or metallurgic feedstock, screening is mainly performed in the thick layer."

Jan 1, 2018

By Ashish Agarwal

For a correct evaluation of the performance of any process, it is important to reconcile the data gathered in the plant from the material balance point of view for all the streams flowing in and flowing out of the process unit. There are two main approaches to reconciliation of data, which involve minimization of the sum of the squares of: (i) the closure residuals and (ii) the component adjustments; both weighed with the estimated variances of the components. Though, these approaches have served us well, it has not been possible to ascertain if the reconciled values for various components and the split factors obtained using these approaches are truly the best estimates. In this paper, this aspect has been investigated by analyzing pseudo-experimental data of known error structure on size classification of particles in a hydrocyclone. Three types of basic error structures were considered for the measured component values: absolute error, relative error and chi-square error. The error structure was modified by adding a random component of error using normally distributed random numbers corresponding to zero mean and different levels of variance. By carrying out a large number of simulation experiments, it has been shown that in the presence of random errors, irrespective of the basic error structure of data, which is usually unknown, the chi-square error minimization criterion can be used to obtain most reliable results. Keywords: data reconciliation methods, chi-square error minimization

Sep 1, 2012

By C. Y. Wang

Based on Slurry Electrolysis, and combined with the problems of extraction antimony, lead and their separation from complicated antimony-lead concentrate, a series of tests have been done in this paper. Using Slurry Electrolysis to treat complicated antimony-lead concentrate, antimony and lead can be separated in one step. And 2# metal antimony can be achieved in cathode directly at the same time. Lead in concentrate is restrained still in the residue at the form of PbCl2. After converting the residue with ammonium carbonate and removing sulfur with kerosene, the high quality of lead concentrate (Pb is above 45%, S is below 15%) and pure sulfur can be achieved, respectively. The recovery of all in Slurry Electrolysis process is as: Sb 95%, Pb 95%, Ag 80%, S 60%.

Jan 1, 2014

By N. ??dyanik, Z. Kugukaldinova, O. Mishurina, Y. Glazkova, E. Mullina

"This paper describes the process flow of a selective processing method for acidic mine waters formed in the copper sulfide industry and characterized by a high content of copper, iron, and manganese ions. The proposed method comprises a series of sequential processes: the 1st stage is the recovery of Cu2+ ions by precipitation, the 2nd stage is the recovery of Fe2+ and Fe3+ ions as a dispersed phase by acid-base precipitation, followed by recovery in the 3rd stage of Mn2+ ions by converting Mn2+ with an oxidizing agent into insoluble forms of manganese and subsequent recovery of the dispersed phase by electroflotation. The developed method was tested on the acidic tailing storage facility (TSF) water of a mining project in the Urals region. The practical results of the implementation of the developed method have shown that its implementation will allow to recover copper, iron, and manganese in the form of salable products with a simultaneous decrease in their concentrations in adjacent water bodies down to the applicable MPCs. The process is a simple one, does not require any sophisticated expensive equipment and can be implemented either as a standalone solution or as part of existing treatment facilities. INTRODUCTION As a result of unsustainable utilization of natural resources in Russia, only a small fraction is processed into commodity products, while the rest is systematically dumped as emissions, effluents, and other wastes, polluting the environment. By amount of waste and concentration of valuable components, those wastes can be classified as aqueous technogenic resources [1, 2]. Therefore, the development of processing methods for this mineral resource category is an urgent and priority task that will significantly improve the industry’s profitability and the environmental conditions in the respective regions. MATERIALS AND METHODS Following research methods were mainly applied in this study: lab-scale and pilot-scale tests in a diaphragmless two-chamber electric flotation cell; for solutions and recoverable process products — chemical analysis using photometric determination techniques for metal cations and atomic adsorption determination techniques for the processing products. The phase composition of the precipitates formed in the process was investigated by X-ray phase analysis in the general-purpose diffractometer with a copper anode DRON-1."

Jan 1, 2018

By Graeme Heyes, Warren J. Bruckard, Michael A. Somerville

"Over the past few years CSIRO Minerals has been conducting research aimed at developing a continuous copper converting process to replace the traditional two-stage batch process that is currently used to produce blister copper. Sirosmelt type reactors and calcium-ferrite (lime-based) slags have been used rather than the conventional iron silicate slags. The research work has now been extended to focus on the development of a single-stage continuous copper making process (so-called direct copper converting) in which copper concentrates are converted to low-sulfur blister copper in a single step, that is the smelting and converting steps occur in one continuous stage.One feature of the direct copper converting process is that copper losses to the slag phase can be high, meaning the slag produced needs to be treated to recover the copper value. The feasibility of the whole copper making process will most likely depend on the efficiency and cost effectiveness of the copper recovery stage. Flotation has been identified as the most economical option to recover the copper from direct copper converting slags where it has been estimated that a copper recovery from the slag of above 90% is required to make the overall single stage copper making process economically feasible.A limited series of laboratory batch flotation tests was conducted on a suite of calcium-ferrite-based slags made in laboratory smelting trials. Copper sulfide concentrates from MIM were used as feed-stocks. The objectives of this work were to develop a robust flotation process to maximise the copper recovery and iron rejection from slags made in the process, and to establish operating conditions for future continuous flotation pilot plant trials.The slags treated included a reduced low copper slag, an oxidised high copper slag composite, and a very reduced low copper self-pulverising slag. The copper content of the slags varied from 2.9% to 14% Cu and the CaO/Fe ratio varied between 0.30 and 0.54. In general, the higher the copper content the more oxidised the slag. The copper was present as metallic copper, oxide copper and copper-calcium ferrite phases with the phase mix related to smelting conditions. The slags were crushed, ground, wet-screened at 355 or 210 µm to remove coarse metallic particles of copper, and floated at natural pH (about pH 11) using reagents and conditions appropriate for the selective recovery of the copper phases. Reagent additions were typically 200 g/t KEX and 500 g/t Na2S.9H2O and the grind size was generally a P80 of about 40 µm."

Jan 1, 2003

By T. S. Reddy

Research and Development Centre for Iron and Steel (RDCIS) a unit of Steel Authority of India Limited (SAIL) is continuously engaged in reduction of energy consumption at SAIL plants by implementing innovative and new concepts. In this regard, continuous efforts are being made to recover waste heat in Sinter Plants. This paper discusses existing waste heat recovery measures taken and proposed measures planned in Sinter Plants. One such effort is on waste heat recovery from sinter coolers. Hot sinter is discharged to the crusher at the end of the sinter machine at a temperature of 500 to 800°C. Temperature of hot sinter is brought down to nearly 100°C in the sinter cooler with air-cooling. The air after cooling the sinter is generally discharged to the atmosphere at about 225 to 300°C. It is planned to recover heat from the hot air that is being released to atmosphere and heat the process water, which is being added at ambient temperature in mixing drum at Bhilai Steel Plant. The temperature of raw sinter mix will be raised by addition of this hot water, which will help in improving the productivity of sinter machine. It is estimated that Waste heat recovery to the tune of 1.5 to 2.0 Gcal/h is possible with reduction in CO2 emissions in the range of 4000 to 5000 ton/year. The novel approach that is being adopted is addition of hot water in mixing drum for higher sinter productivity for the first time in India. Keywords: waste heat recovery, sinter plant, hot water generation, emission reduction, CDM

Sep 1, 2012

By Aidan Giblett, Karen McCaffery, Robert Dunne

"A worldwide decline in competency levels of practicing metallurgists over recent decades has become clearly evident and is a common topic of discussion among senior practitioners and professional associations. The associated impacts on the industry are material and include operational inefficiencies, missed optimisation opportunities and suboptimal new plant designs. There are many contributing factors to this condition. Decrease in competency is particularly evident both in regions where imbalance between supply and demand has led to a general reduction in experience levels for comparable roles over time and in emerging regions where a rapid rise in demand for practitioners has occurred in conjunction with rapid economic development and industrialization. The context, depth and breadth of education curricula and levels vary with location such that solutions to the technical competency dilemma may need to be developed specifically for each region with these influences in mind. Delivering, demonstrating and maintaining competencies are a critical requirement of undergraduate training and ongoing professional development. Other factors such as generational and cultural characteristics and expectations, political influences, role requirements and employment reward and recognition systems all play a critical role in determining if core competencies can be effectively developed, applied and subsequently maintained. This paper reviews factors impacting and some common approaches to competency development. The authors’ experiences in the management of professional development efforts within the global industry are reviewed and a blueprint proposed to address industry requirements in this area."

Jan 1, 2014

By P. Somasundaran

Gangue minerals can often have severe adverse effects on selective value mineral separation. Such effects can be mediated through a variety of pathways or mechanisms. One popular mechanism is that of ?slime coating? or heterocoagulation, wherein the gangue mineral fines are believed to coat the value mineral surfaces and thereby reduce selectivity and floatability. Another pathway that has received relatively little attention is that mediated through the effect of gangue minerals on pulp rheology, and consequently selective separation. Our recent work in developing a scientific understanding of these effects has highlighted the prevalence and importance of this pathway. In this study, the impact of shape and morphology of serpentine gangue minerals on suspension rheology and selective Ni flotation from ultramafic ores was investigated. We found strong evidence for micro- and macro-network formation in the presence of acicular (needle-shaped) or fibrous minerals, which impacted pulp rheological properties. Results also supported the hypothesis that morphology has a greater role to play than mere shape. The size of the network ranged from 5 microns to 2 cm depending upon the amount and aspect ratio of fibrous minerals. These networks impede many flotation sub-processes, such as gas dispersion and bubble-particle interactions. Additionally, the small pore size of the networks prevents bubble penetration leading to a large transport of the gangue minerals to the concentrate via lifting of the entire network by bubble flux, which resulted in a significant grade dilution. Based on the scientific insights generated in this study various techniques have been developed to improve selective value mineral separation. Keywords: fibers, aspect ratio, microstructures, networks, pulp viscosity, gangue transport

Sep 1, 2012

By André Mans, Frans B. Waanders

"Ferrosilicon (Fe-Si) is an important commercial material and it forms the basis of the powder used in dense medium separation (DMS) of various minerals in a minerals beneficiation process. Current losses of Ferrosilicon (Fe-Si), which is used in the dense medium separation (DMS) of iron ore at Kumba Resources, Sishen, South Africa occur due to adhesion to the separation products and also by being present in the effluent stream, due to abrasion. The losses contribute greatly to the running cost of the plant and the purpose of this project was to determine the characteristics of the unused Fe-Si and then to characterise the changes that occur during storage and the use thereof.A Scanning Electron Microscope (SEM) and Mössbauer Spectroscopy (MS) were used to investigate the characteristics of the fresh and used Fe-Si. The SEM analyses of the Fe-Si yielded a composition of 15 wt.% Si and 85 wt.% Fe with minor impurities of Mn and Cr (<1 wt. %), resulting in an ordered phase with a calculated composition of Fe2Si. The average density of the Fe-Si was found to be 7.177 g.cm-3 whilst the size distribution was determined with the d50 of the particles being approximately 30 µm. A slurry, containing 10% solids was prepared, which had a density of about 1.1 g.cm-3 and this slurry was used to conduct the various experiments under laboratory conditions at the university. Samples were taken at regular intervals from a storage container containing a lime solution as well as from a closed circulation circuit system, kept at a constant temperature of about 60°C. Mössbauer Spectroscopy yielded, for the new fresh Fe-Si-samples, a two-sextet spectrum with hyperfine magnetic field strengths of 19.9T and 30.7T respectively, and the yellow-brown froth was found to be akaganeite or ß-FeOOH.It was found that the biggest loss of Fe-Si was due to the abrasion of the particles during the DMS process. A possible change in magnetic properties was also observed, leading to further losses that could occur during prolonged use of the medium. No clear changes to the Fe-Si occurred during correct storage methods, as was initially thought."

Jan 1, 2003