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By Lj. D. Andric

By the micronization-milling of the material, the size and the structure of its particles are changed and it comes to the increasing of the potential energy of the system as well as to the chem-ical activity of the material what is the result of an increased free surface and of the concentration of the grate defects, that is of the internal energy of the system. All these changes that are reached, show that new characteristics of treated materials are got by micronization process. Controlling the process of the micronization and by purpose directing of the new characteristics of the activated materials, we can have the positive effects and use them in more technologies. Talc is important nonmetallic mineral raw material that is widely used as either the basic raw material, or as filler. This has stimulated its technological investigation, as well as the investigation of its physical-chemical characteristics. In this paper are shown experimentally reached results of the physical-chemical characteristics of the talc during the process of the micronization in high energetic mill. In this paper, the optimum conditions of miconization of talc in high-energy-speed rotary mill and its influence micronization on a degree of Fe2O3recovery by hydrometallurgical methodes, are presented. The X-ray analysis of the obtained products showed that high quality talc with low content of can be obtained by these physical-chemical processes In this paper, the principles and application or fine and ultra-fine grinding high-energy attriton mill with small balls, enabling fast, efficient grinding, low energy consumption, short grinding time and easy handling will be described.

Jan 1, 2014

By G. Pahomova

"It developed an alternative to traditional flotation enrichment refractory of complex lead-zinc ores to obtain conditional lead and zinc products. The scheme involves the use of the processing method of gravitational enrichment of the primary cycle and the combined gravity-flotation-hydrometallurgical in finishing. The method has a high level of comprehensive utilization of mineral raw materials in relation to the elements that are extracted in the process of enrichment in lead concentrate, and the increase in recoverable value of processed ores. INTRODUCTION The primary source of lead are complex sulphide lead-zinc ore, lead ore actually rarer. The value of lead and zinc ores (except lead and zinc) is determined by the presence in them of a wide range of associated components: silver, contained mainly in galena; gold; bismuth in the form of its own minerals, but is associated with galena; cadmium contained mainly in the sphalerite; indium, thallium and gallium contained in sphalerite and galena; selenium and tellurium are present as impurities in the sulfide, tellurium is also found in the form of its own minerals. Of note harmful impurities antimony, which is often associated with lead sulphosalts and arsenic, having a substantially own minerals. By quality (content of lead, or the total content of lead and zinc) lead-zinc ores are divided into rich, ordinary and poor; by oxidation - to sulfide (with a lead oxides content less than 15% and zinc oxide content less than 10%), mixed and oxidized (50% oxide); the latter have a subordinate importance as a source of zinc and lead. Traditionally, the most contrasting technological properties of sulfide ores of nonferrous metals considered flotation properties, which determines the priority in the selection of flotation technology of their enrichment. Other methods of enrichment - gravity (jigging and enrichment in heavy suspensions), radiometric sorting (separation) are used as preliminary operations whose main purpose is to increase the content of lead and zinc in the ore sent to flotation, as well as the removing of part of empty rock in dumping tails prior to flotation. Effective implementation of these methods is possible at large size emphasizing in the ore of lead and zinc minerals, which is typical of the rich ores and which so far mainly worked. At the same time, non-ferrous metal ores (polymetallic, lead-zinc, copper-zinc, etc.) have a sufficiently high contrast to gravitational properties since ore minerals have a higher density compared with a rock minerals. But the gravity of the practice of non-ferrous ores enrichment is not widely used, despite its high degree of environmental safety and lower cost expensive."

Jan 1, 2018

By A. N. Lazaridi, S. I. Afanasenko, S. A. Safonov

"This scientific work presents the results of comparative tests of centrifugal concentrators with a vertical and horizontal axis of rotor spinning. The article also describes a qualitative analysis of the behavior of mineral particles in a centrifugal field with fluidization for concentrators with a horizontal axis. The analysis was aimed at studying the effect of the quantity of fluidization holes in the basket on the degree of magnetite recovery and the effect of the basket rotation speed. The experiment demonstrated that concentrators with a horizontal axis are not inferior in terms of the qualitative recovery indicators to concentrators with a vertical axis. The researches also provided facts about the wide practical application of concentrators with a horizontal rotor arrangement. INTRODUCTION Methods of gravity concentration, attractive for their ecological purity, see their revival. First of all, this is due to the invention of centrifugal concentrators with the fluidization of the layer of mineral particles. The creation of a new generation of gravitational centrifugal concentrators made it possible to achieve a tangible breakthrough toward the direction of reducing the grain size of mineral particles effectively divided by density, up to 10 µm at a high production capacity of the vessels reaching 500-600 tons per hour. Such separators enable dressing a crushed ore of flotation grade and in some cases replace the flotation process, especially in primary operations, in joint cycles. In the long term, this method of concentration should significantly expand the scope of application, replace partial flotation processing, ensure the introduction of environmentally friendly energy-saving technologies at ore-processing plants. Summarizing the international experience for the last 30 years, it can be confidently asserted that centrifugal methods of concentration have become widely used in processing schemes for the separation of finely dispersed products in the mining industry. An interest in the creation of installations using centrifugal acceleration for the separation of mineral particles by density has particularly grown. Dozens of centrifugal concentrator designs have been created and continue to be improved. Centrifugal concentrators have a number of obvious advantages, which are especially relevant today. Losses of fine gold during the process of mining are well known. Gold washers screw, spiral separators, jigging machines and sluices traditionally used in the production processes do not solve the problem of fine gold recovery. Table 1 shows the results of comparative tests of a centrifugal concentrator (ITOMAK) and other concentration equipment. According to the research conducted by the company GMRS, Krugersdorp, South Africa (2000), the initial material was gold ore crushed to 150 micrometers (90%)."

Jan 1, 2018

By L. Ya Agapova

Emissions from pyrometallurgical processing of copper concentrates are usually subjected to wet scrubbing. The washing sulphuric acid so produced contains up to 0.2 g/L of rhenium, which is recovered by solvent extraction in the form of crude ammonia permeate (NH4ReO4). The mother liquor, obtained from the sulfuric acid wash, contains up to 35 g/L of rhenium and significant amounts of impurities. Crude rhenium salt is commonly processed by double recrystallization to produce marketable salt. A ton of high grade NH4ReO4 can be produced using 3.0-3.5 m3 of mother liquor. We propose an efficient technology of mother liquor pre-treatment aimed at removal of water-soluble organics with subsequent electrodialysis. Electrodialysis of mother liquor in a multichamber electrodialyzer resulted in the production of pure rhenium acid, from which a marketable NH4ReO4 is precipitated using ammonia solution. Multiple steps of recycling consisting of dissolution of NH4ReO4 salt, rhenium acid production from NH4ReO4 salt by electrodialysis and precipitation of NH4ReO4 from rhenium acid made it possible to upgrade the purity of obtained rhenium compounds by 1-2 orders of magnitude. A rhenium metal powder of 99.997% purity was produced by high-temperature reduction of high-purity NH4ReO4 with gaseous hydrogen. Rhenium metal powder of high purity can be produced from sulfate solutions of NH4ReO4 by non-platinum anode-based membrane electrolysis processes also. Keywords: rhenium, mother liquors, membranes, electrodialysis, rhenium acid, ammonia perrhenate, reduction, powder, electrolysis

Sep 1, 2012

By Kauko T. Ingerttilä, Jouko O. Kallioinen, Jaakko O. Leppinen, Alexander V. Lashkul, Vladimir E. Nenno

The Separation in Froth (SIF) technique is based on the idea that the pulp is fed directly onto the froth layer prepared on the surface of liquid medium providing an effective method for separation of coarse particles up to a few millimeters size. Thus the SIF process can result in substantial savings in grinding energy and flotation chemicals. In this work flotation of apatite, calcite and silicate minerals from various industrial sources was investigated using laboratory and pilot plant-scale SIF machines. Flotation of diamonds was also investigated on laboratory scale. It was observed that all the minerals mentioned above can be successfully floated up to about 3 mm particle size. Beneficiation tests with the coarse fractions of classification circuits indicated that final grade calcite concentrate can be obtained with over 90% recovery in one SIF step in this grain size (typically 0,1 to 1,5 mm). Similarly, substantial upgrading of coarse apatite was achieved without grinding it to the fineness required by conventional flotation. SIF could also be applied to the recovery of coarse apatite from the tailings of a conventional flotation process. The capacity measured in the pilot plant test runs for a 1 m2 cell was typically 30 t/m2h. Presently, a full-scale process using the SIF technology is being installed for coarse apatite recovery.

Jan 1, 2003

By Harri J. Lehto, Marja I. Oja

Empirical models used for predicting the performance of screens on the basis of capacity, cut size, water split and grade efficiency curves were evaluated. This paper reports experimental results obtained with single-deck Derrick screens. The performance of the screen was tested with limestone in a separate screen set-up, in a pilot plant and in industrial scale test runs. The results of pilot plant experiments showed that the measured water split was higher than the measured bypass. This is an indication to that water flow does not entrain the same proportion of all fine particles present in the feed which is advantageous for screening. The experimental design for the industrial test runs was made on the basis of the pilot plant tests. Suitability of the existing models has been checked and accuracy compared. The tests showed that best grade efficiency model was the Rosin-Rammler model. An empirical model for the evaluation of the model parameters as a function of pulp density of the feed and the load of the screen is suggested.

Jan 1, 2003

By A. Boulton

Low molecular weight synthetic polymers substituted with hydroxyl, carboxyl or sulfonate functional groups were used to improve the flotation separation of zinc or copper sulfide minerals from iron sulfide gangue minerals in three massive sulfide ores of different mineral composition. These polymers produced significant improvements in zinc or copper grades as a result of a selective depression of iron sulfide minerals. It was shown that this selectivity was the result of preferential adsorption of the polymer on the surface of the iron sulfide minerals. The different types of interaction between the functional group on the polymers and the sulfide mineral surfaces could explain the trends observed in the flotation results.

Jan 1, 2003

By Matthew Thurley

Optimisation and control of comminution, pelletization, and agglomeration processes is a complex task with large potential for gains in productivity, energy efficiency, and particle size distribution quality. One factor in realising these gains is the requirement for fully-automated online particle size distribution measurement. Moreover, online particle size distribution measurement that is based on the particles on the visible surface and can avoid or mitigate substantial errors that result from under-sizing overlapped particles and over-sizing areas of fines particles. Literature review indicates a body of substantially 2D photographic based particle size measurement systems that suffer from a large number of significant errors except in the simplest case of a monolayer of particles under good illumination with limited color variation in the material. In order to measure the visible particles on a pile there are a number of requirements including; avoiding particle delineation errors due to variation in material color and shadows, detect overlapping versus non-overlapping particles, and identify areas of fine particles as fines and not large rocks. Results are presented using a fully-automated online measurement system of crushed rock on conveyor belt using a 3D surface laser profile. The system provides continuous online measurement and results are shown on over four hours of production after the primary crusher. Size distribution results are calculated using volumetric estimation of the particles on the surface of the pile. The results show a strong capability to discriminate size variation especially in the 10% and 20% passing values. Furthermore results show that if areas of fines are misclassified as large rocks, and overlapped particles misclassified as small rocks, then a near complete loss of discrimination occurs for the P10 and P20 values which become largely constant values.

Jan 1, 2014

By Behzad Vaziri Hassas, Firat Karakas, Mehmet Celik, Onur Guven

Since dewatering is a costly process, removal of moisture from relatively fine size lignites is an important industrial problem. As the lignite gets finer, the presence of micropores and relatively low hydrophobic nature of lignite lead to trapping of large quantities of water in the coal matrix. Lignites used in power stations need to be dried to a certain degree of humidity before it is transferred to the combustion chamber. It is generally wise to dewater coal as much as possible by physical means before it is dried. However, dewatering cost in some cases may be prohibitive. Thus, sometimes removal of even little percent moisture may be of great help in such operations. Surfactants have been used to increase the efficiency of coal dewatering. It is crucial to select appropriate type and amount of surfactants in order to get higher efficiency. Since the hydrophobic characteristic of coals increases with increasing the coal rank, dewatering of bituminous and anthracite can be accomplished using low HLB surfactants (Oily), however, these surfactants are not efficient in the case of low rank coals like lignites and brown coals. It is suggested that adsorption of low HLB surfactants on high rank coals is governed by Acid-Base interactions rather than electrostatic and van der Waals forces. Since this characteristic in lignites is not strong enough, low HLB surfactants could not be effectively adsorbed on low rank coals to make surface more hydrophobic. In this paper, a special set-up has been designed to study the effect of high HLB surfactants on dewatering of fine lignite particles. It is shown that high HLB surfactants function more efficiently on low rank coals than low HLB ones.

Jan 1, 2014

"The first 90 years of the last century generated a considerable volume of technical literature on the subject of grinding mill power and its prediction. It is therefore surprising that during this time there were no published models for predicting grinding mill power draw which were validated using a wide range of comprehensive industrial scale data.Notwithstanding this lack of data, the majority of models placed limited emphasis on the internal dynamics of mills and relied on simple assumptions which considered the charge to take up a fixed position and shape.Laboratory based studies (Liddell, 1986), and industrial data (Morrell, 1993), showed that these assumptions did not hold over a wide range of operating conditions, and brought into doubt the ability of the (then) existing models to accurately predict grinding mill power draw. Furthermore no model treated AG,SAG and ball mills as a single class of devices whose power draw could be predicted with the same equations.Through a detailed investigation of the charge dynamics, coupled with a large data base of industrial mill power draws, this situation was rectified by the end of the century, by which time a model had been developed and validated, which accurately predicted the power draw of all wet tumbling mills. This paper describes this model and reviews some of the earlier attempts at mill power modelling."

Jan 1, 2003

By S. A. Kondratyev

"The present research work aims at disclosing the dependence of flotation concentrate recovery and its grade on the physically adsorbed collecting reagent properties, viz., surface pressure in the reagent film at gas-liquid interface, velocity of reagent species spreading over the said interface, relation between interaction energies of collector molecules within a film and with water dipoles.When using a single collecting reagent it is possible to improve the flotation concentrate grade in two ways, namely, by reducing collector consumption rate or using a weaker reagent. According to the proposed mechanism, a decrease in the physically sorbed species of the collector leads to a decrease in the rate of removal of the kinetic restriction of a flotation contact formation. As a result, the recovery of the useful component is reduced and the content of valuable components in the flotation concentrate is increased. The relationship between the spreading velocity of physically sorbed species at the gas-liquid interface and the recovery and quality of the flotation concentrate has been experimentally proved. Reduction in collector consumption lowered the valuable component recovery at a higher grade of the concentrate.The reasons were established for a rise of valuable content in the flotation concentrate if a weaker collector was used. It is justified that the use of a weaker collecting reagent with a shorter hydrocarbon fragment declines physically sorbed species of collector. The spreading velocity of collector derivatives at gas-liquid interface tends to lower along with less participation physically sorbed species of collector in formation of a flotation aggregate. The spreading velocity is determined for products of interaction between butyl-and ethyl-xanthates and lead nitrate at gas-liquid interface. It is found that the spreading velocity of butyl-xanthate derivatives is higher than that of ethylxanthate derivatives.The research work gets insight into the nature of relation between useful component content in the flotation concentrate and the useful component recovery. It is pointed out that adjusting the collecting activity of a collector makes it possible to influence a useful component content in the froth product thus gaining a compromise between wanted grade and recovery parameters."

Jan 1, 2018

By P. Huang, D. W. Fuerstenau

Various factors that control the natural flotability of talc, including differences due to crystal face and edge effects, were delineated. For study of talc depression phenomena, dextrin was used as a model depressant. For the enhancement of talc flotation, dodecylammonium acetate (DDAA) was used as the collector. The interaction of DDAA with talc was assessed by flotation experiments and electrokinetic (zeta potential) measurements, from which the role of hydrophobic bonding can be demonstrated. The results presented in this paper provide useful information on how the crystal chemistry and surface chemistry control the electrical double layer, adsorption phenomena, wettability, and flotation behavior of talc in aqueous media.

Jan 1, 2003

"Wet low intensity magnetic separation has been used for the recovery of magnetite for decades. As high-grade reserves continue to decline, low grade magnetite ores are being targeted for iron production. Low grade magnetite mineralisation is typically fine grained and requires fine to ultrafine grinding (P80 40 - 30 µm) to liberate it from, predominantly, silica/silicate gangue matrices. Grinding to such particle sizes requires high power consumption and produces excessive fines which impact negatively on wet magnetic separation and tailings dewatering. In addition, the dearth of fresh water for mineral processing in arid areas impacts negatively on the economic viability of low grade magnetite projects. These challenges have motivated innovation in dry magnetic separation technologies for the beneficiation of magnetite that can be economically applied on a large-scale. Such technology has been developed in the Cyclomag Planar magnetic separator (PMS) invented by South Australia-based Christopher Kelsey of IMPTEC P/L. The significant gangue mineralisation associated with magnetite ores in South Australia is quartz. In this study, the performance of the Cyclomag PMS on the recovery of magnetite mineral from magnetite-quartz blends was investigated. Magnetite-quartz blend were subjected to the PMS at varying control parameters - magnet discs rotation speed, inlet airflow and feeder speed. The study showed a successful dry separation of magnetic mineral from non-magnetics using the Cyclomag PMS. The PMS has potential to effectively recover magnetite mineral."

Jan 1, 2018

By D. J. Borrow, K. van Netten

"A fine coal tailings feed was selectively agglomerated using a concentrated water in oil emulsion binder consisting of 95% aqueous phase and 5% organic phase. The purpose of the study was to investigate a continuous system in plug flow, providing a rapid beneficiation technique with high selectivity and recovery. The development of the novel binder was undertaken in previous work in a batch system consisting of a high-speed blender. In this previous work, it was found that agglomeration could be achieved in 3 s, providing the binder was pre-dispersed. Furthermore, it was found that, depending on the feed, only ~1 wt% of oil was required to achieve agglomeration, some 10 times less than required in traditional oil agglomeration. In a more recent study, the technique was adapted into a continuous process. Due to the rapid speed of the process using the emulsion binder it was found that a simple flow constriction within a 1 inch pipe was sufficient to achieve the selective agglomeration observed in the batch system. In this previous study, a coal feed consisting of a flotation product was agglomerated at a superficial slurry velocity of 1.3 m/s using a partially closed ball valve as the flow constriction. In the current study, a feed consisting of fine coal tailings with an ash content of 50.1% was used to establish the influence of superficial slurry velocity on the agglomeration process. The superficial slurry velocity was varied between 1.3- 4.2 m/s, while maintaining a constant pressure drop of 100 kPa across the flow constriction. The flow constriction consisted of a partially closed ball valve. It was found that increasing the superficial slurry velocity across the flow constriction reduced the amount of organic liquid required to achieve agglomeration. Under the optimum conditions, a combustible recovery of 80.4% was achieved at a product ash content of 9.6%. This work demonstrates a valuable product can be rapidly produced from tailings material using the novel emulsion binder. INTRODUCTION A significant opportunity exists to recover fine coal from material that is currently classified as waste. This waste material, also called tailings, is currently considered not economic to process due to its high ash content, low solids concentration, and the fine size of the particles. Thus, for this opportunity to be realised, a process is required that is highly selective and has the ability to economically recover fine particles at high throughputs. The technique of oil agglomeration has previously been considered as a candidate for the recovery of fine coal, as it is highly selective and has no lower limit on the size of particle that can be recovered (Capes and Jonasson, 1989). However, the cost of the oil required as the binding agent in the process has proven to be a significant barrier to any long-term applications (Swanson, Nicol, and Bensley, 1977). Recently, however, Yoon and co-workers have developed an ultrafine coal separation process that utilizes an oil phase for the recovery of the hydrophobic coal particles and have implemented an oil recycle to greatly reduce the consumption and thus cost of the oil (Yoon et al., 2016)."

Jan 1, 2018

By V. A. Ivanova

Modification of hydrophobic part of carboxylic collector molecule is an upcoming trend for producing new reagents and changing its flotation properties such as activity, selectivity, sensitivity to hardness salts that inevitably present in the pulp liquid phase in the processing of ores containing calcium minerals. A wide range of apatite collectors ? monoalkyl ethers and monoalkylamides of dicarboxylic acids ? succinic, o-phthalic and maleinic acids have been synthesized by the addition of aliphatic alcohols and amines with various hydrocarbon radical value (from ?11 to ?16) to anhydride of the corresponding acid. Using computer modeling based on ChemBio 3D program of specialized complex Chem?ffice the calculation was carried out of charge distribution on atoms, energy parameters of molecules for investigated compounds. Calculated values of absolute hardness (?=6.75 ? 12.36) and absolute electronegativity (?= 5.67 ? 8.90) of the reagents showed that monoderivatives of dicarboxylic acids refer to the ?hard? type of bases. The degree of a charge transfer during calcium compounds formation of considered collecting agents (?N=0.009 ? 0.143) has been computed. Dissociations, micelle formation in solutions of these reagents and its hydrophobic and collecting properties were investigated in respect to apatite. Dependence of bulk, surface and collector properties on collector molecule architecture (double bond or benzene ring and non-ionogenic functional group in the structure of hydrocarbon radical) has been established. It is shown that experimentally determined dissociation constants (??a=5.16 ? 5.60 for succinic acid derivatives and ??a=3.32-3.78 for maleinic and o-phthalic acid derivatives) perfectly correspond to acidic properties predicted by computer calculations. Compounds of monoalkylderivative dicarboxilic acid have been determined optimum in composition and structure. The results of apatite flotation from apatite-nepheline ores of the Khibiny deposit (the Kola Peninsula) are presented here and show benefits of selected reagents. Keywords: monoalkylderivatives, dicarboxylic acids, reagents, microflotation

Sep 1, 2012

By Wei Zhang, Jinhong Zhang

"In froth flotation, the adsorption of collector on mineral surface is critical for a successful flotation process. In present work, an atomic force microscopy (AFM) has been applied to study the adsorption of potassium amyl xanthate (PAX) on copper sulfides, i.e., chalcopyrite, chalcocite and bornite. The in-situ collected AFM images show that PAX adsorbs on chalcopyrite mainly in the form of oily dixanthogen; while it strongly adsorbs on chalcocite and bornite in the form of insoluble metal xanthate, which binds strongly with the mineral surface. The information obtained from the AFM study shed lights on the collectivity and therefore the selection of specific collector for different copper sulfide minerals in industrial practice.INTRODUCTIONFroth flotation, which treats the highest throughput in mining industry and produces the maximum economic outcome of any surface chemistry process, has been widely applied for the concentration of copper sulfide minerals, i.e., chalcopyrite, chalcocite and bornite. In flotation, collectors are added into the pulp (mixture of water and fine-grained minerals) to selectively adsorb onto the target mineral and render its surface with high hydrophobicity, which is generally beneficial for a strong mineral-bubble attachment and thus a high flotation recovery. Therefore, the adsorption of collector on mineral surface is vital for a successful flotation process and it has been studied by applying various surface analysis techniques, such as IR (Infrared Spectroscopy), CV (Cyclic Voltammetry) and XPS (X-ray Photoelectron Spectroscopy). (Poling, 1963; Allison et al., 1972; Mielczarski et al., 1984; Leppinen et al., 1989; Kartio et al., 1996) These studies have revealed a lot of information, such as the reaction, product and mechanism, of the adsorption of chemicals on mineral surface. It is also of great interest to directly get the image of adsorbed collectors on mineral surface changing with pulp chemistry, such as pH, redox potential, ionic strength and chemical’s dosage."

Jan 1, 2018

By Leopoldo Gutierrez

Eight oil sand ores with the bitumen content ranging between 3.6 and 15 wt.% and the fines content (-44 micrometers size fraction) between 9 and 69 vol.% were subjected to the standard alkali extraction test used to measure the degree of oxidation of metallurgical coals. The results showed that there is a strong correlation between the absorbance of extracted solutions at a wavelength of 520 nm and the ratio of the fines content to the bitumen content. The latter factor is directly relevant to assessing the extractability of bitumen from oil sand ores. Bitumen extraction tests showed that the bitumen recovery decreased from 90 % to 30 % when the absorbance at 520 nm increased from 0.23 to 0.64. A comparison of the UV/visible spectra of solutions obtained from the alkali extraction tests with solutions of Aldrich Humic Acids suggest that low bitumen/high fines oil sand ores release substantial amounts of organic matter very similar, if not identical, to humic acids. In contrast, high-bitumen and low-fines ores do not release as much of the organic matter, and UV spectra of these leached substances are quite different from those of humic acids. Overall, the results show that chemical composition of bitumen in the tested ores varies greatly with ore type and oxidation, and that the alkali extraction test is a promising technique to quickly assess the extractability of bitumen from a given ore type.

Sep 1, 2012

By S. Castro

Molybdenite flotation is strongly depressed at pH higher than 9.5 in the flotation of Cu-Mo ores in sea water. Chemically sea water contains mainly Na+ and Cl- ions, but also some secondary ions, such as SO42-, Mg2+; Ca2+, HCO3-; etc., which are not necessarily indifferent for the flotation of molybdenite. The natural floatability of molybdenite in sea water and in NaCl solutions containing different secondary ions is investigated by micro-flotation tests. The tests indicate that the floatability of molybdenite in alkaline media in 0.6 M NaCl solutions is not affected by the presence of anions, such as, SO42- and HCO3-, at concentrations similar to those occurring in sea water. However, a strong depression of molybdenite at pH ranging from 9.5-10.0, is produced by the alkaline earth metal cations (Ca2+ and Mg2+ ions), dissolved in distilled water or in 0.6M NaCl solutions. It was found that effect of Mg2+ions is significantly stronger than Ca2+ ions. Effect of both ions is attributed to hydrolysis and adsorption of MOH+ hydroxy-complexes. This is followed by subsequent precipitation of hydrophilic colloidal hydroxides at the molybdenite/solution interface, and in bulk solution.

Sep 1, 2012

By G. P. Karmakar, K. K. Chandan

"The drilling mud is an essential part of the drilling process, which plays a major role in keeping safe and efficient oil and gas well drilling. In the oil industry, bentonite clay dissolved in water produces the simplest type of drilling muds. Bentonite clay contains montmorillonite particles. These particles are dispersed uniformly in water and such dispersions are used in various industrial products like paints, ceramics, pesticides and drilling muds. The bentonite clay easily dissolves in water and increases the viscosity of the water, which is one of the most important properties of a drilling mud. Bentonite has the highest swelling capacity, which is responsible for building up of the viscosity of the clay-water system. The flocculation behavior of bentonite is one of the major concerns for the performance of the water-based drilling mud in the oil and gas well drilling process. The behavior of drilling mud greatly depends upon the quality and quantity of bentonite clay, as well as the additives that are used in their formulations. In this work, a comprehensive study has been carried out to find out the effect of added polyacrylamide (PAM) polymer, surfactant, pH and salt concentrations on the dispersion/ flocculation characteristics of bentonite clay-water system. It has been observed that the increase in PAM dosage reduces the residual turbidity and improves the settling rate of the bentonite particles. The flocculation rate has also been found to be better under higher pH conditions. The combined effect of salt concentration and PAM dosage improved the overall flocculation efficiency of the system.INTRODUCTIONIn the oil industry, bentonite clay dissolved in water produces simplest type of drilling muds. Bentonite clay containes montmorillonite particles. These particles are dispersed uniformly in water. Such dispersions are used in various industrial products like paints, ceramics, pesticides and drilling muds (Akther et al., 2007). The bentonite clay easily hydrates in water and increases the viscosity of the mud system (Razi et al., 2013; Meng et al., 2012). Bentonite clay in the drilling mud increases the viscosity which is one of the most important prop erties of a drilling mud. Bentonite has the highest swelling capacity, which is responsible for the building up viscosity of the clay-water system (Sonmez et al., 2013). The drilling mud is an essential part of the drilling process, which plays a major role in keeping a safe and efficient oil or gas well drilling (ASME, S. S. C., 2005). The flocculation behavior of bentonite is one of the major concerns for the performance of the water-based drilling mud in the oil or gas well drilling process. This behavior of drilling muds greatly depend upon the quality and quantity of bentonite clay, as well as the additives that are used in their formulations (Yu and Amanullah, 2005; Akther et al., 2007). Bentonite particles form aggregate under certain conditions including high temperature, and high concentration (Luckham and Rossi, 1999). If the quality of bentonite is not sufficient to accomplish intended viscosity of the muds, it is essential to add certain additives to increase the viscosity and prevent aggregation of the system (Razi et al., 2013). The anionic polymer bearing sample can build up inter-particle bonds between the polymer and clay particles. The addition of various additives like, polymers control the dispersion and enhance the viscosity of the mud by controlling the flocculation of montmorillonite particles in bentonite dispersion (Heller and Keren, 2002; Mahto and Sharma, 2004)."

Jan 1, 2018

By M. Kanuchová, J. Briancin, M. Achimovicová

"Faculty of Mining, Ecology, Process Control and Geotechnology, Technical University, Košice, Slovakia An industrial eccentric vibratory mill was used for direct and short-time mechanochemical reduction of ilmenite concentrate (FeTiO3) and anatase (TiO2) with magnesium metal powder in order to reduce Fe and Ti resp. and hereby to convert them to the more soluble phases suitable for further hydrometallurgical processing. X-ray diffraction analysis of FeTiO3 after 60 min of milling with Mg confirmed the presence of Fe0 and Mg2TiO4 phases and for TiO2 after 180 min of milling the new TiO and MgO phases have appeared. X-ray photoelectron spectroscopy has detected Fe0 (metal) and Mg2+ species which are corresponding to the product of FeTiO3 mechanochemical reduction. The product of TiO2 mechanochemical reduction has revealed XPS spectral lines corresponding to Ti2+, Ti4+ and Mg2+ species on its surface. Morphology of mechanochemically reduced samples was studied by scanning electron microscopy analysis. Subsequent leaching of mechanochemically reduced FeTiO3 and TiO2 was performed in dilute HCl and H2SO4 at 80oC and compared with mechanically activated samples. The recovery of Ti has reached 100% for FeTiO3 and 79% for TiO2 after 60 min of leaching. Based on this study the flowsheet for possible processing of natural refractory titanium ores patented by author was adapted and documented. INTRODUCTION Ilmenite (FeTiO3), along with rutile (TiO2) represents the most important titanium resource necessary for titanium industry, for production of titanium metal, alloys and pigment grade TiO2 which are becoming more important and versatile for various industries such as an aircraft and aerospace, navy, chemical, automotive, medical and offshore wind industries, for machine and plant engineering and architecture as well, mainly due to high corrosion resistance. Pigment grade TiO2 is utilizing in pigment, plastic, glass, paper and rubber industries (Zhang, 2011). There are obvious research efforts for development of the potential alternatives to the expensive thermo-chemical commercial processes of titanium raw materials processing. Zhang (2011) has summarized conventional thermo- a electrochemical processes which involved a combination of pyrometallurgical, hydrometallurgical and electrometallurgical technologies and highlighted the improved hydrometallurgical routes promising for commercial application in the future. Such improvement could also be mechanical activation of FeTiO3, TiO2 by high-energy milling which causes their structural disordering, the changes of physical and chemical properties, consequently and has a positive effect on the dissolution kinetics (Achimovicová et al., 2014a, 2017, Baláž, 2008). The various types of mills such as a planetary ball mill, a vertical ball mill, a drum mill, an attritor were used for mechanical activation of FeTiO3 as a pretreatment process for subsequent leaching (Achimovicová et al., 2014)."

Jan 1, 2018