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By Z. G. Song

As a kind of complex physicochemical process, grinding would affect the subsequent mineral processing such as flotation considerably. In this study, the effect of wet grinding on malachite and calcite flotation using sodium oleate as collector was studied. And the mechanism of the effect of grinding was investigated. Laboratory scale grinding and flotation testing of malachite and calcite samples were performed. Different grinding media were used, including steel balls and zirconia balls. It was the aim of this work to study the effect of grinding on the pulp chemistry paying particular attention to flotation recovery. The effect of grinding media and different addition location of sodium oleate on malachite and calcite flotation was studied. The methodology used in this project involved grinding the ore with and without the addition of sodium oleate in mill, measuring the pH and metal ions produced by minerals after grinding, adding various quantities of sodium oleate and determining the copper recovery. The presence of species of products on the minerals after grinding was probed using X-ray photoelectron spectroscopy (XPS), and the metal ions produced by minerals after grinding were measured by atomic absorption spectrometry (AAS). It is showed that the mil-ling environments evaluated significantly affected the flotation of malachite and calcite. This study also discusses the effecting mechanism of grinding environment on floatability of malachite and calcite.

Jan 1, 2014

"The most common agglomeration technique in iron and steelmaking is sintering, which requires the use of iron ore/concentrate mixtures, limestone and dolomite as fluxes and coke as fuel in order to produce the required melt at high temperature to cause agglomeration of the particles. Sinter feed blends containing high proportions of magnetite concentrate are difficult to granulate and to produce granules of high permeability, and sufficiently robust quasi-particles for successful sintering operations. Since the granulation of iron ore sinter feed requires no use of a binder, the added fluxes play a vital role in holding the granule particles together until they sinter. The fluxes also help to improve the granule quality and control slag composition in the blast furnace. It is well-known that the particle size distribution of the fluxes affects the granulation effectiveness and green bed permeability which determine the productivity, physical and metallurgical properties of the granules and sinter. Hence it is necessary to understand the role of flux particle size on granule properties so as to improve the granulation of iron ore sinter feed blends containing high magnetite concentrate. In this study, laboratory granulation experiments have been carried out on iron ore sinter feed blends containing high proportions of magnetite concentrate at different addition levels of limestone and dolomite mean particle sizes, to understand the influence of limestone and dolomite particle sizes on granulation rate processes and granule properties.INTRODUCTION Increases in iron ore production to meet the global demand for iron and steel products has led to the depletion of high grade iron ores and thus the current utilisation of low grade iron ore fines and concentrates. However, sinter, pellets and the lump are the required feed types used in the blast furnace. The high basicity sinter is the main iron bearing feed accounting for 70-85% in the blast furnace due to its good metallurgical and mechanical properties that allow high productivity, efficient processes and low production cost (Adam et al., 2017)."

Jan 1, 2018

By A. I. Urvanzev, N. V. Shikhov

"In this paper, we present the study’s results of electrical separation processes on the basis of new separator designs, new technological solutions, and newly discovered effects. We considered the options of enrichment by magnet separation of magnetite and titanomagnetite ores, ores and products containing chromium and manganese, ores of non-ferrous and precious metals. During pneumo-electric separation of mixed iron ore of SMPC, 43.3% of the output of the concentrate with an iron content of 61.7% was obtained in one step, with extraction of 70.5%. The paper also presents the results of the finalization on the air-electric separator of the magnetic fraction when separating oxidized ores of MPPOO (mining and processing plant of oxidized ores) on the Jans polygrade magnetic separator. A concentrate was obtained with an iron content of 65.1% with the extraction of 95.0% and tails with an iron content of 13.0%. The possibility of obtaining low-silica concentrates from these ores with an iron content of 67.15 and a quartz of 2.88% is shown. Also, the results of tests on the enrichment of chromite ores on the firing-magnetic scheme with corona-electrostatic separation are considered. On the initial ore of the Don MPP (mining and processing plant), a concentrate with a content of 61.8% Cr2O3 was obtained with a quartz content of ~ 1.0%. The results of pneumo-electric separation with triboelectric charge of the separated particles are presented. The results of the tests indicate a principal possibility of enriching chromite ores without costly high-temperature roasting. Dry technology of enrichment of manganese ores with the use of electrical separation increases the quality of the oxidized concentrate to the first grade and raises the total extraction by 2 times. For the Chineya deposit of titanomagnetite ores with copper impurities, electroseparation operations were carried out on two samples with a Cu content of 1.93 and 3.75%, respectively. For a sample with a Cu content of 6.02%, a copper concentrate output of 24.42% was obtained with a Cu content of 23.82% and the extraction of 94.88%. The results of enrichment by electroseparation of gold-containing sulfide ores can have the practical importance. For ores of the Berezovskoye deposit, a pyritic concentrate containing 100 g / t of gold was obtained after two or three operations of IES (integrated energy systems)."

Jan 1, 2018

By L. Gao, X. Gui

Fine coal obtained from Kailuan mine served as the processing object of this study. This material was difficult to separate. A flotation rate experiment was designed to investigate the process distribution characteristics of size and density during fine coal flotation. Size and density analyses of five clean were studied. The mineral morphology of flotation rate experiment cleaning was observed through scanning electron microscopy. The fractions -0.074+0.045 mm and -0.045 mm exhibited the best practical floatability and presented the highest combustible body recovery rates, but the selectivity and natural floatability of these two fractions were the worst. The - 0.074 mm fraction has contaminated the clean coal from the early stage of flotation, and the cumulative clean coal ash of -0.074 mm reached up to 17.20%. The low and middle-density classes displayed varying flotation behavior, but the flotation yield difference was only nearly 3%. The middle-density class caused the clean coal to have high ash content. The poor selectivity of fine coals, middle-density fraction, and fine mud resulted in high-ash clean coals during flotation. Thus, improving the selectivity of fine coal, restraining the flotation of fine mud, and grinding the coal to decrease the middle density mass fraction to liberate clean coals can yield high-quality clean coals through flotation.

Jan 1, 2014

By Nina Panteleeva, Elena Afonina, Stanislav Titkov, Jury Buksha

"Flotation processing of water-soluble minerals (potassium ores, sedimentary salts of salt lakes) is currently the main method for production of potassium fertilizers and concentrated carnallite which is the initial product for production of metallic magnesium. Flotation of sylvite (KCl) and halite (NaCl) is carried out in the electrolyte solutions: KCl-NaCl-H2O and KCl-NaCl-MgCl2-H2O. The report presents the results of studies of the effect of concentration and the electrolyte type on the size of air bubbles in a flotation cell in comparison with the floatability of mineral constituents of potash ores. The floatability in electrolytes of various compositions has been studied: - of sylvite (KCl) by alkylamines, - of halite (NaCl) by alkylmorpholines, - of silicate-carbonate slimes contained in the ore by ethoxylated surfactants. The reagent modes (regimes) activating the flotation desliming of potash ores have been developed."

Jan 1, 2014

By Ingvar Ymén, Alexandra Lundmark

"The depressive effect of dichromate on galena was evaluated with chemical experiments and small-scale depression experiments at a pH of around 12. The depressive effect was measured with Dynamic Vapor Sorption (DVS), which measures the water uptake of a sample as a function of the % relative humidity. The depression is due to PbCrO4PbO, which in the presence of Ca2+ and SO4 2- forms a more or less amorphous solid solution (Pb,Ca)(CrO4,SO4)PbO, which clogs to the surfaces of the ore. Free Pb2+- ions are needed for depression to occur and at high pH Pb2+ - hydroxide complexes, supply enough Pb2+ - ions to precipitate (Pb,Ca)(CrO4,SO4)PbO. In air CO2, precipitates CaCO3 which slowly lowers pH, precipitating more (Pb,Ca)(CrO4,SO4)PbO and CaCO3 on galena. Similar experiments where performed with five alternative depressors whereof phosphate, which forms an amorphous precipitate of approximate composition Pb3Ca13(PO4)10SO4, gave the best results. Phosphate was tested in laboratory scale flotation experiments giving encouraging results.INTRODUCTIONWithin Boliden Mines, concentrating of copper and lead from complex sulfide ores is performed by bulk flotation, meaning that copper and lead are concentrated in the same product. Downstream, copper and lead are separated by flotation of chalcopyrite, and depression of galena. Boliden has for many decades used sodium dichromate to depress galena (reference 1). Dichromate is both toxic and carcinogenic and Boliden has for many years investigated several alternatives. So far, however, the best results have been obtained with dichromate. Since Boliden has tried to substitute dichromate for a long time without finding a process as effective, Boliden decided to clarify the function of dichromate in the depression of galena and on the basis of the outcome find alternative depressors with similar function. This study was given to RISE Bioscience and Materials / Surface, Process and Formulation as a consultancy assignment. This paper presents the outcome of the combined efforts of Boliden and RISE."

Jan 1, 2018

By Z. G. Song, C. Y. Sun, X. R. Zhang, Y. Yu

In skarn type scheelite deposit, there are calcium minerals with floatability similar to scheelite, such as calcite, fluorite, etc., which are difficult to separate. Heating cleaning method developed by Petrov has been widely applied in processing rough concentrate of scheelite for nearly half a century, but there exists a general lack of full understanding of the interaction between floatation reagent and mineral particles surfaces. The mechanism on separation of scheelite and calcium minerals in heating cleaning process was investigated by mineral flotation experiments, XPS analysis, as well as solution chemistry and crystal chemistry calculations. The results showed that the sequence of minerals floatability using sodium oleate as collector and a large amount of sodium silicate as modifier in heating flotation test was scheelite > calcite > fluorite, which was the same as solution chemistry calculations based on Gibbs free energy vs. pH and also the same as Ca-X intensity order by crystal chemistry analysis. There are two sides about the mechanism of heating cleaning method: one is that the adsorbed collector on calcium minerals surface is desorbed more easily than scheelite, and the other is selective dissolution of calcium ions from the mineral surface because of Ca-X intensity difference in heating and stirring process.

Jan 1, 2014

By Magnus Evertsson, Rebecka Stomvall, Josefine Berntsson

"Understanding the effect of particle shape on dry rheology is considered to be an important aspect in order to replace natural sand used in concrete with manufactured sand. Crushed particles from solid rock are normally less rounded and have less equally shaped dimensions compared to natural sand. Thus, the flowability and workability of the concrete will be different. In previous research, it has been demonstrated how different crushing techniques affects the shape of the particles. In many cases it is believed that Vertical Shaft Impact (VSI) technology is a way forward to replace natural sand. To be able to study the effect of VSI at the smaller fractions (63-2000 µm) sufficient measurements methods to determine particle shape are required. Optical tools to analyze the aggregates would make it possible to study a large amount of particles at small fractions. The determination of particle shape of aggregates is challenging since the shape is highly irregular and the size span of particles are very large. This study aim to evaluate one of the available optical tools, the Camsizer, for digital imaging determination of shape and size distribution. The available default shape parameters of the Camsizer are studied to understand the meaning of the parameters and their suitability for determining the quality of manufactured sand. To evaluate the capacity to determine particle shape, tests are made with 35 different materials. The results are compared with the dry rheology measured with the standardized "flow cone" test. Dependence has been previously proven between particle shape and the mass flow rate in the cone. Three different shape parameters, aspect ratio, sphericity and symmetry, are studied with the Camsizer and the results are compared with the mass flow rates in the cone. The results indicate a strong linear relationship between the optical parameters and the flow cone test."

Jan 1, 2014

By Venkataramana Runkana, Aditya Pareek, Vishnu Masampally, Nagaravi Kumar Varma Nadimpalli

"Recovery and grade of the ore produced are two important metrics, which define the profitability of a mineral processing plant. Achieving high grade and high recovery at the same time in a mineral processing plant is difficult due to conflicting nature of the two objectives. To explore the operability limits of the plant operations and find the set of operating conditions that can help achieve the best possible recovery and grade, there is a need to solve a multi-objective optimization (MOO) problem. Past research focused on building a plant-wide simulation model or on optimization of individual units or a part of a mineral processing plant like grinding circuit, crushing circuit, etc. However, it is necessary to consider optimization of the complete plant in order to optimize the plant performance. Here, we have formulated the mineral processing plant performance optimization as a MOO problem. We have applied machine-learning algorithms such as random forest to build models to predict the recovery and grade of the ore. A non-dominated sorting-based multi-objective evolutionary algorithm called NSGA-II (Non-dominated Sorting Genetic Algorithm II) was employed to solve the MOO problem. Since the number of parameters that influence recovery and grade are quite large, we have applied machine-learning algorithms for feature selection or identification of key process variables. Pareto optimal conditions were determined for manipulated variables like grinding mill throughput, speed ratio at SAG mill, speed of centrifugal pump, water addition at different locations etc. The results obtained are useful in identifying the operability of a mineral processing plant to achieve the optimum grade and recovery for a given feed grade and the processing circuit. INTRODUCTION Copper is majorly mined or extracted as copper sulfides from large open pit mines in porphyry copper deposits. Among all the available ores, sulfides are the most commercial ores, especially chalcopyrite (Greenwood and Alan, 1997). Copper grade in these ores generally lies between 0.4 to 1.0%. In order to perform smelting operation, the grade of copper has to be improved to around 30% (Biswas et al. 2013). This targeted copper grade is achieved through two stages of mineral processing. Firstly, the copper in the ore has to be liberated by crushing the mineral rock. Secondly, the liberated copper in the crushed ore is then physically separated from other minerals like nickel by froth flotation techniques."

Jan 1, 2018

By S. H. Morar

Froth flotation is a physico-chemical separation process that takes place in two phases; pulp and froth phase. It is widely recognised as a complex process, due to the range of interactions present within the system. Of critical importance is the role of the froth phase within the system. The pulp kinetics governs the maximum potential recovery within a flotation cell, while the froth phase governs the selectivity via the froth?s stability. Higher froth stability improves recovery at the expense of grade, and lower froth stability improves selectivity. It is well known that the two major factors affecting froth stability are attached particles and solution chemistry. This paper looks at a flotation bank at different froth depth and frother concentrations. The air recovery to the concentrate is determined at each condition and relates the effect of the operating conditions on froth stability and transport to the amount of solids that are recovered to the froth and concentrate by true flotation. The results presented show that, for a given process objective, which in this case was a consistent mass pull profile, depending on the operating conditions, solids recovery in the pulp is affected by the air rate required to maintain the target mass pull. To a smaller extent, the changes in the pulp composition affect down-stream pulp recovery. The variation in solids recovered into the froth drives the froth stability at the start of the flotation bank, while the frother drives the froth stability at the end of the bank. The performance in between these two extreme conditions arises from an interaction of these two effects. The consequences of these interactions can give rise to counter-intuitive responses that can confound efforts to optimise the performance of the bank.

Jan 1, 2014

By L. Y. Wang

In order to produce the iron and steel products with high quality and decrease the output of steel tailings, the quality of molten iron is a critical factor for iron and steel companies, especially the content of sulfidic in molten iron. Hot metal pre-treatment, an important and effective method to desulphur, is widely used in steel production. Millions of tons of slag from desulphurization and slag skimming are produced each year in China, and many more times this amount is stored in slag dams because of the lack of effective means to deal with it. In order to achieve the goal of sustain-able development, recycling these slag becomes necessary. The main objective of this paper is to study the composition characteristics of slag that from desulphurization and slag skimming. The sample was obtained from Anshan Iron and Steel Group Corporation, processed by hot metal pre-treatment. In this study, the chemical components and the mineral compositions of sample were tested. The results of chemical components and iron chemistry phase analysis showed that the iron and sulphide content in this sample were high, and the iron products existed mainly in the form of magnetite, metallic iron, ferrosilite. X-ray diffraction (XRD) and scanning electron microscope (SEM) results indicated that the sample included metallic iron, ferrate, wustite, metasilicate, aluminate, aluminosilicate, white lime and soon. Grading magnetic separation test work showed that magnetic separation was an effective method to recovery iron products and decrease the sulphide content in concentrate, and the tailing could be used as the raw material or padding in cement production.

Jan 1, 2014

By W. G. Liu

Phenyl malonic acid (PMA), a new chelating collector, which contains a phenyl structure and a malonic acid chelating group, has been synthesized and its collecting capabilities to calamine, hematite, quartz and hemimorphite are also studied in laboratory. From the experimental results, it can be seen that the PMA has somewhat flotation ability to calamine, hematite and quartz, while it nearly has no collecting ability to hemimorphite. With the increase of PMA concentration, the flotation recovery of calamine increases. When the dosage of PMA was 560g/t and at pH=7~9, the flotation recovery of calamine gets its maximum of 45.94%. The test results about the influence of pH on the flotation recovery of quartz show that the flotation recovery increases with the increase of pH, and the maximal flotation recovery can be gained in alkaline media. On the other hand, PMA has stronger flotation capability to hematite than to other minerals. The flotation recovery of minerals increases with increase of PMA concentration. When the dosage of PMA is 560g/t and at pH=5~7, the flotation recovery of hematite is 82.96%. Mean-while, the influence of pH on the flotation recovery of hematite was studied and test results showed that, as pH increases, the flotation recovery sharply rises until pH=4, then the increasing rate de-creases outstandingly, at pH=6 the flotation recovery reaches its maximum of 82.96% and it de-creases speedily in alkaline media. Finally, through the measurement of infrared spectroscopy and in terms of solution chemistry of collector, the flotation mechanism has been discussed. It was concluded that the adsorption of PMA on minerals surface is chemical adsorption in nature through two oxygen atoms in the polar group of phenyl malonic acid chelating with the metal ions of minerals surface to form a hexagon-cycle chelate complex: C(=O)-O-M-O-(O=)C.

Jan 1, 2014

By V. E. Dementiev, V. I. Kulikov, G. I. Voiloshnikov, Yu. O. Fedorov

"The report presents the summary of the JSC Irgiredmet’s activities in the field of preconcentration of ores. As of 2018, the Institute has almost 40-years’ experience in this area. Over the years, Irgiredmet has done a lot of work – from development to implementation of new technologies of ore piece sorting and concentration based on X-ray radiometric separation (XRRS). INTRODUCTION Preconcentration has been a challenging issue of the mining industry over the last decades. The implementation of this technology can significantly increase mining efficiency. The main application of preconcentration is improvement of mined ores quality, however new and more complex issues have arisen with the evolution of the technology. Irgiredmet has started to develop an efficient preconcentration technology for gold-bearing and rare-metal ores 40 years ago. The X-ray radiometric method widely used at that date as a method of elements determination in geology and geophysics become the ground for this work (1). Since that time, the Irgiredmet Institute has developed and significantly improved the technology of piece ore sorting, or XRRS (2-5), that is currently also known as the X-ray fluorescence method. The progress of the XRRS development achieved by Irgiredmet in cooperation with Rados LLC, Tekhnoros LLC (Krasnoyarsk), Rados-Service LLC and CJSC Tekhnogen (Ekaterinburg) has proved efficiency and applicability of the XRRS technology for processing a wide range of minerals and solving of various technological problems (7-9) compared to other radiometric methods (6). Furthermore, obtained results are supported by numerous studies, trials and implementations. The significance of ore preconcentration for greenfield and brownfield projects determined the establishing a new subdivision of Irgiredmet, the XRRS Technology Center (XRRS TC), that has provided the Institute with a completed range of processing technologies, from preconcentration to producing final products. Over the past few years, the XRRS Technology Center has carried out studies and testing of a numerous (more than 100) projects, mines and deposits of gold-bearing ores, rare metal ores (Be, Ta, Nb, W, Mo), base metal ores (Cu, Sb, Zn, Pb), ferrous metal ores (Fe, Ti, Cr), rough diamonds and coal. The XRRS Technology Center performs various specific studies and testing not only in Russia, but as well as in Kazakhstan, Georgia and Mongolia. Mines and companies from Chile, India, China, Iran and other countries also take an active interest in the XRRS technology."

Jan 1, 2018

By Luo Chuansheng, Rao Jinshan, He Xiaojuan, Qiu Xianyang

The dissemination grain size of chalcopyrite is really fine and refractory grains of -10µm take up 25%. Dissemination relationships among chalcopyrite with pyrrhotite, pyrite, marcasite and gangue minerals are complex. Content of Fe-bearing sulphides and Fe-bearing silicates associated with chalcopyrite reaches to about 60%. It’s hard to liberate and separate chalcopyrite from pyrrhotite. The above four are the main mineral processing difficulties of a copper ore in China. Because of the similar floatability and poor separation effect between chalcopyrite and pyrrhotite, enhanced depressing and collecting method was adopted in Cu-S separation before 2009. Due to the different magnetism among chalcopyrite, pyrrhotite and Fe-bearing silicates, magnetic separation is creatively induced in Cu floatation circuit based on the in-depth study of process mineralogy. High efficiency and new Cu-S separation technology of "Rough concentrate regrinding-pyrrhotite rejecting from middling by magnetic separation" and a highly selective copper minerals collector YL-1 had been developed to solve the difficult problems of refractory Cu-S separation, which are heavy load of middling recirculation,difficulty in upgrading Cu concentrate, unstable locked cycle and low separation indexes. And grade of Cu concentrate has been increased by 3.33%, recovery of Cu and Ag has been increased by 19.32% and 10% respectively.

Jan 1, 2014

By Thomas Mütze, Michael Klichowicz, Mathis Reichert, Holger Lieberwirth

"Self-similarity is proofed to be a common feature when brittle material is comminuted, either in particle bed or single particle mode. Appropriate test work is well documented for particle sizes less than 7 mm in several publications. In contrast, almost no research has been done for coarser particles. The aim of this paper is to show that the fracture pattern of coarser material also tends to be self-similar. Hence, single particles of quartzite, granodiorite and dolomite were comminuted under compressive load. The focus was set on three different size fractions -3.15 +2.5 mm, -31.5 +25 mm and lumps -300 mm. According to the wide range of particle sizes, three different piston-die presses were used with a maximum compressive force ranging from 5 kN to 4000 kN. The force-displacement curves were recorded in order to calculate the specific comminution energy. Additionally, the -31.5 +25 mm size fraction was crushed in a laboratory scale jaw crusher and a roll crusher. Some authors report that the energy-size-reduction relationship of self-similar materials can be approximated by a linear function, which is independent of the comminution equipment. In their charts the slope can be seen as a product-size-independent grindability measure. Our tests show a self-similar breakage behavior when particles in a range of -300 +3 mm are comminuted in single particle mode. Furthermore, the products of the piston-die-presses and the roll crusher are similar to each other in a self-similar representation of the particle size distribution. The jaw crusher product, however, is not self-similar compared to the piston-die-press products. Finally, the linear energy-size-reduction relationships are confirmed for each fraction, but show size dependent slopes."

Jan 1, 2014

By J. Lindström, J. Hamuyuni, M. Lundström, J. Aromaa

"The rising demand for metals today, coupled with the scarcity of primary sources for raw materials threatens both technological advancements and industrial manufacturing. In order to meet the demand, metals and other resources trapped in waste streams, have to be harnessed. This philosophy supports circular economy, where metals and other resources are kept in a closed loop. The pickling acid recovery system of most stainless steel production is one such example where the dissolved metals such as iron, nickel and chromium are currently not completely recovered due to the limitations of the current technologies. The aim of this study was to assess the available metals recovery methods from extremely concentrated acids. The main aim is to simultaneously recover metals and keep sulphuric acid reusable in acid circulation process. From the available literature, the most promising methods were chosen for laboratory experiments. Based on experimental work, the results and observations of electrodeposition, solvent extraction, and freeze crystallization are provided. KEYWORDS Pickling acid, metal recovery, solvent extraction, cathodic polarization, Freeze crystallization. INTRODUCTION Pickling in stainless steel production is an essential surface treatment process (Regel-Rosocka, M. (2010); Agrawal and Sahu, 2009). It is applied for removing surface films such as oxides and chromium-depleted layers to improve the corrosion resistance and surface finish of steel (Regel-Rosocka, 2010). Whilst the process greatly improves the surface finish of the stainless steel, it generates large amount of used acid, containing dissolved metals including chromium, iron, and nickel (Agrawal and Sahu, 2009). Recovery of acid is common practice for most steel producing industries (Nyman and Koivunen, 1986). In this work, acid regeneration process is investigated so as to simultaneously reusing sulfuric acid and recovering the dissolved metals. Recovery of valuable metals even in very small amounts would also bring additional revenue to the steel production industry. At a time when metal production has also been challenged by lack of natural resources for raw materials, secondary sources for metals such as the acid pickling process therefore, have greater potential as supplements. From earlier studies, electrodeposition (Giovanardi and Orlando, 2011; Kuznetsov et al., 200; Rögener et al., 2012; Surviliene et al., 2006), solvent extraction (Alguacil and López 1996; Haghshenas et al., 2009; Kesieme et al., 2013) and freeze crystallization (Beyer et al.,2003; Hasan et al.,2017; Van der Ham et al., 1999) are some of the most established potential methods. Earlier studies have also shown that simultaneous recovery of acid and metals would require combination of different methods. This is primarily due to the nature of very stable metal containing complex compounds formed during pickling. These complexes must be broken down to free the metals for further recovery processes."

Jan 1, 2018

By S. Z. Shafaei

An experimental investigation has been carried out using a laboratory scale Denver flotation cell. For evaluation of cokeable coal of Alborze Sharghi coal washing plant, the full factorial method was used to statistically design and analyse the experiments. The 2 factorial interaction model were developed for combustible recovery and ash content as response and diesel dosage, conditioning time, feed percent solids and rotor speed as factors. Model validation and residual analysis were con-ducted and results indicated that the fitness, predictability power and residual distributions of models were good. The effect of parameters and interactions were examined and it has been demonstrated that rotor speed, solid percent and interaction between diesel dosage and solid percent were more important terms of all responses. A product with approximately 78% combustible recovery and 10% ash content was obtained at 4000gr/ton diesel fuel oil (high level), 30 sec conditioning time (low level), feed percent solids of 15% (low level) and 800 rpm rotor speed in appropriate condition.

Jan 1, 2014

By Y. Foucaud, C. Eswaraiah, L. Filippov

Enhanced gravity separators such as Falcon concentrator which uses additional centrifugal force, are the most common gravity concentration techniques used for fine particles processing. Hence, understanding the kinetics and separation mechanisms within these separators is of paramount interest. Recent research yielded a predictive physical model for the Falcon Ultra Fine (UF) which however does not explain some results obtained with industrial ores. This study aims to identify the mechanisms involved in Falcon UF separation with the objective of confirming or rejecting the hypotheses on which the current model is built and suggesting potential points of improvement. The Falcon UF kinetics is investigated through the processing of complex low-grade and fine-grained ores from the Altenberg tin deposit (Germany), the Tabuaço tungsten deposit (Portugal) as well as a synthetic iron ore. Saturation tests are performed on the Falcon UF by controlling the separation efficiency in terms of recovery and enrichment ratio with time or feed mass. Results show an evolution of Falcon UF performance with time in contradiction with the stationary separation hypothesis on which the physical model is based. Observation of the concentrate bed suggests the presence of erosion figures in furrows which may play locally an active role in the separation. In terms of Falcon UF separation timing, three phases can be distinguished. First, upon initial feeding of the bowl, a bed quickly grows unselectively and ultra-fine particles are ejected from the bowl until the bed reaches its final profile. Next, actual separation occurs with selective concentration of dense particles. Finally, capture sites saturate and recovery drops. The evolution of partition curves over time confirms the existence of two separation mechanisms. First, differential particles settling within the flowing film responsible for the ejection of small size particles during the whole separation cycle which is already accounted for in the physical model. The second mechanism involved may be explained by the action of lift force, neglected in the physical model, which acts preferentially on coarse particles deposited at the surface of the bed resulting in coarser particles being rejected in the tailings. Hence, the addition of a lift force component to the existing model is suggested to account for this second separation mechanism.

Jan 1, 2018

By H. X. Yan, J. X. Zhang, F. S. Niu

"The analysis on influencing factors of hydraulic conditions in fine hematite flocculation, such as stirring speed, stirring time and axial distance of particle size and fractal dimension of floc was investigated. Furthermore, response surface methodology(RSM) has been applied according to the Box-Benhnken center-united experimental design principle to optimize parameters of hydraulic conditions as a response index to indicate the fractal dimension of floc. The results show that when the agitation speed is 900r/min, the axial distance is 2.0cm, and the stirring time is 3.0min, the particle size reaches the maximum value of 35.44µm and the fractal dimension is 1.6594. The interaction between the axial distance and the stirring speed is highly significant, but the interaction with the stirring time is not obvious. The experimental data and model predications match well, which indicates that the established model has high accuracy and practicability. INTRODUCTION With the exhaustion of iron ore resources that are easy to be mined and the vigorous demand for iron and steel, the exploitation and utilization of fine-grained embedded iron ore resources have drawn attention from the industry and the government [1~2]. Flocculation flotation is one of the effective methods for separation and recovery of fine granular minerals. In 1975, the method was first applied and succeeded in Tilden Concentrator, USA. Flocculation and desliming became the key technology of the Tilden to raise its annual treatment capacity from 4 million tons to 8 million tons at that time [3 ~ 4]. In 2008, the selective flocculation and desliming-reverse flotation technology was successfully used to treat 2.8 million tons of Qidong iron ore. Under the conditions of 28.36% raw iron grade and 98% grinding fineness -0.038 mm, the ideal index of 62.5% iron concentrate grade and 68% recovery was obtained [5]. Dr Kitchenner of the Royal College of Mining and the Ore Processing Research Group of Wallenstein Laboratory first proposed the use of flocculation to separate minerals. After that, many scholars conducted a great deal of theoretical and practical researches, but mostly they focused on chemical theories, mathematical models and selectivity differences in the flocculation process, while the research on the influence of the pulp flow state on the separation effect in the flocculation process started later [6~9]. The results show that the motion of the agitated flow field has a significant influence on the formation of flocs. The fluid morphology will change with the change of hydraulic conditions. The change of fluid morphology will not only affect the movement behavior of particles, but also change the action of chemical agents on the surface of mineral particles[10~12]."

Jan 1, 2018

By G. N. Jadhav

In India, bauxite deposits are concentrated in Central India, Western Ghats and Eastern Ghats. Bauxites from various regions in Gujarat were identified during the present investigations of geochemical mapping. Different types of Bauxites samples were collected from Kachchh, Jamnagar, Porbunder, Junagarh, Bhavnagar and Amreli areas of Gujarat state and were studied in detail for their geochemical signatures to plot the data on Geochemical map. Raw bauxites were characterized by using powder XRD, XRF, ICP and optical microscopy techniques (with the help of Model microscope having both transmitted and reflected light setups) and were later examined to grade their quality. Most of the bauxites from Kachchh region were of high-grade (gibbsitic) type; while those of Sourashtra region were of low-grade (lateritic / calcitic) types. Most of these bauxites were either of ferruginous/lateritic or of calcareous/calcitic types. Based on the mineralogical composition, such as gibbsite, hematite and/or goethite, Kaolinite and calcite minerals present in particular bauxites, the deposits were graded. Finally, the Geochemical mapping of Bauxites for Gujarat region was prepared and discussed.

Sep 1, 2012