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By A. An. Mushketov, A. Al. Mushketov, N. A. Sopina

"INTRIDUCTION At present, more and more metallized raw materials with a metallization degree of not less than 80% are used in the smelting of steel. The main quantity of this raw material is produced in furnaces of mine type. Advantages of this type of raw materials for metallurgical processing are low levels of harmful and slag-forming impurities and a high content of metallic iron. At the same time, the cost of smelting raw materials and obtaining high-quality steels are reduced. In addition to the undoubted merits of metallized raw materials, there are high requirements for the quality of iron concentrates, which are the starting material for metallization: the mass fraction of acidic oxides should not exceed 3%; The mass fraction of iron should not be less than 69%, mass fractions of harmful impurities (phosphorus, arsenic, sulfur, copper, etc.) should not exceed 0.02%. These requirements are dictated by the fact that the recovery of burned pellets is carried out by gas in a solid phase. In this case, the empty rock and harmful impurities from the metal are not separated and sent to the steelmaking unit, increasing the heat consumption for heating and worsening the quality of the steel. The combined production of high-quality concentrate and metallized raw materials requires a large capital outlay from the enterprise, which in the future can be compensated for by increased profit from the sale of more expensive marketable products. At present, in the territory of Russia and the CIS countries Lebedinsky mining-and-processing integrated works is the only enterprise that carries out the entire chain of operations for the production of metallized raw materials, starting with the production of high-quality magnetite concentrate with a mass fraction of iron of 69.5% and ending with the production of a metallized product in the form of hot briquetted gland. JSC «SSGPO» is the largest iron-processing enterprise in Kazakhstan, which processes about 40 million tons of ore per year and receives 16 million tons of concentrate per year with a mass fraction of iron 66.0-66.5%. The technological scheme existing at the concentrator of JSC ""SSGPO"" includes the crushing of the feed ore to the size of 20-0 mm; dry magnetic separation operation; three reduction stages to a fineness of 90-95% kl-0.071 mm; operation of desliming, wet magnetic separation and filtration of the concentrate. Dry magnetic separation of the feed ore makes it possible to remove from the process of 19.6% of the tailings with a mass fraction of the total iron 12.5%, of magnetite 2.2%. The first reduction stage is carried out in rod mills with the volume of 40 m3 to a size of -1.6 + 0.0 mm. The first stage of wet magnetic separation is carried out in counterflow magnetic separators PBM-P-150/200L. The magnetic product of the first stage of WMS is classified in hydrocyclones; sands enter the second reduction stage into central discharge ball mill 3600 × 5000. Runoff of mills enter on the second enrichment stage in counterflow magnetic separators PBM-P-150/200L. The magnetic product enters the classification of the second stage, forming a closed cycle. Mass fraction of the class -0.071 + 0 mm in classifications runoff of the second stage is 70-75%. The second stage classifications runoff is transported toWMS-III operation in semi-counter separators PBM-PP-120/300. The magnetic product of the third stage enters the classification of the third stage. Granular residue are transported to the reduction of the third stage into central discharge ball mill 3600 × 5000. The mill runoff enters the third stage of classification, forming a closed cycle. Classifications runoff of the third stage enters on deslimation. Deslimed product is sent for fine screening to the crasher «Derrick» 2SG48-60W-5STK with a cell size of 0.1 mm. Top size of crasher is sent to regrinding. Undersize with a mass fraction of the class -0.071 + 0 mm 90-95% is fed to the wet magnetic separation of WMS-"

Jan 1, 2018

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 E. R. Bobicki

"Low-grade ultramafic nickel ores, while representing a large potential nickel resource, are difficult to process due to their serpentine content. Microwave treatment is proposed as a technique to improve the beneficiation of ultramafic nickel ores by converting the constituent serpentine to olivine. The present paper reviews the microwave heating response of ultramafic nickel ores and resultant changes in mineralogy, as well as effects on grinding and slurry rheology. Beyond nickel extraction, microwave treatment improves the mineral carbon storage capacity of ultramafic ore tailings, providing a potential source of additional revenue via the sale of carbon credits. The combined positive effects, considered in the context of the whole operation, suggest an economically viable process is possible.INTRODUCTIONAs high-grade deposits become depleted, the processing of low-grade ores has become increasingly important. One such resource is low-grade ultramafic nickel ores. While representing a large source of nickel, these ores are difficult to process due to their serpentine content. Serpentine is a phyllosilicate mineral consisting of 1:1 stacked sheets of silica tetrahedra and magnesium hydroxide octahedra. There are three primary polymorphs: lizardite (platy), antigorite (corrugated) and chrysotile (coiled, fibrous). The anisotropic nature and non-spherical morphology of serpentine particles leads to complex rheology. Suspensions of serpentine minerals, especially those of chrysotile, exhibit high viscosity and yield stress, which can have a negative effect on comminution, flotation and dewatering operations. In flotation, serpentine is known to slime-coat pentlandite, a valuable nickel mineral, and form bubble-fibre aggregates that report to the froth, reducing nickel concentrate grade and recovery. Methods used to counteract the effects of serpentine in processing include desliming, the addition of chemical dispersants, salts or acid, and dilution (Bobicki et al., 2014a). Microwave pre-treatment has been proposed as an alternative way to eliminate the deleterious effects of serpentine in ultramafic nickel ore processing by converting the serpentine to olivine via dehydroxylation, which occurs at 600-700oC (Reaction 1). Olivine is isotropic, consisting of isolated silica tetrahedra linked by octahedrally coordinated magnesium ions, and has the same surface potential as pentlandite at the pH of flotation (~pH 9). Furthermore, since olivine is more reactive to CO2 than serpentine, microwave pre-treatment creates an opportunity to store more CO2 in tailings, an attractive option for mining operations looking to increase their bottom line where carbon pricing exists."

Jan 1, 2018

By A. V. Rasskazova

"The oxidized and mixed ores are processed by heap leaching. Primary ores with high gold content are floated. In recent years mining of primary ores with the low gold content (up to 4 ppm) has increased. Extraction of gold from these ores by floatation is technologically ineffective. Gravity concentration is ineffective for fine gold particles because of their floatability. The research objective was assessment of the viability of processing gold-bearing ore with combined gravitational and hydrometallurgical methods and testing of recovery of metals from a gold-copper oxidized ore chloride-hypochlorite leaching solution. The advantage of chloride-hypochlorite lixiviant is the low cost of reagents which is produced by the electrochemical synthesis of NaCl solution with the addition of HCl. The adsorption of chlorine compounds by a mineral matrix and its ability to oxidize the refractory ore components and allows for the application of chloride-hypochlorite systems for gold recovery for both oxidized and primary ores. The complexity and problem in using a gold–chloride system is the strong adsorption of gold–chloride complexes onto mineral surfaces, such as goethite, quartz, and alumina. In preliminary testing, gold recovery from gravity circuit gold bearing concentrates processed by agitation leaching in chloride-hypochlorite solution, gold recovery has reached up 82% after 4 hours of leaching. Chloride-hypochlorite leaching of copper-gold oxidized ore with preliminary processing by sulfuric acid provided for 94 % gold recovery to solution. Understanding of ecological hazard of cyanides is the motive power of researches in the field of search non-cyanic chemistries to provide for technologically and economically effective solvents of gold. Soluble compounds of chlorine with a suitable oxidizer are one of the alternatives to cyanides. Basic researches of gold extraction by chloride-hypochlorite solution have shown high rates of gold recovery.INTRODUCTION Because of the continued and growing environmental concern for the use of cyanide for gold processing, interest for the use of non-cyanide lixiviants, especially with halides has renewed recently (Tran et al., 2001; Ferron et al., 2003; Bhaghalha, 2007). Leaching solutions based on halides (chloride, bromide and iodide) are viable alternative to cyanide (Kwang et al., 2008). The major disadvantage of the chlorine–chloride system is the high reactivity of chlorine in reaction with sulfide and gangue carbonate minerals. It is believed that only high grade materials may be treated by chlorine–chloride systems economically (Baghalha, 2007). Another important problem of the application of gold–chloride complex is that it tends to be rather unstable and may re-precipitate upon contact with a reductant, such as sulfidic minerals of ore. It is well known that Au(III)–chloride hydrolysis species are strongly adsorbed by goethite, quartz, and alumina (Machfsky et al., 1991). To minimize adsorption of gold–chloro complexes, it works best to minimize the adsorption time."

Jan 1, 2018

By M. Saghaeian, R. Hejazi, H. Abedini, M. Zare

Water recovery in mineral processing plants is one of the most important subjects because water supply is a critical matter economically and environmentally, especially in desert areas. In this paper, the filtration behaviour of two iron ore tailing sample has been investigated using laboratory scale vacuum and pressure filtration units. These samples including tailing from Sirjan and Zarand concentrate production plants with the d80 of 94 and 41 micron, respectively. The results show that by using vacuum filtration the cake moisture content of Sirjan sample would be about 24%. But the filtration time is too long and vacuum belt filter cannot be used in industrial scale. Adding about 40 g/ton of flocculant would decrease the filtration time by about 30% and make the vacuum belt filter appropriate for dewatering of this sample. For Zarand tailing sample, the vacuum filtration would produce a wet cake by about 31% moisture content. Filtration time is too long and adding flocculant would not improve the results very much. So pressure filtration must be used for dewatering of this sample. The results of laboratory tests show that using pressure filter would reduce the cake moisture content to 21%. The filtration time is logical, so this process can be used for Zarand tailing dewatering.

Jan 1, 2014

By Teemu Väyrynen, Matti Vilkko, Antti Jaatinen, Pekka Itävuo

"This paper shows that smooth and accurate feed-hopper level control is essential for consistent cone crusher operation. The objective of the paper is to define the best practices for tight control of cone crusher feed-hopper level. The paper discusses the challenges involved in a delay-dominant level control problem (specifically, dead-time-induced performance and stability issues, mass flow disturbances, process and actuator non-linearity) and proposes five corresponding control structures. The performance of the proposed control structure candidates is evaluated in a simulation study and, finally, a full-scale experiment is conducted for the best-performing candidate. The results of this study emphasize the importance of control structure selection. While the most obvious control structures failed to deliver the desired performance, the best result was achieved by using control structures that eliminate the conveyor transport delay (dead-time) from the control loop. In practice, the control loop dead-time can be eliminated by either using an actuator (variable-speed feed conveyor) that is connected directly to the feed-hopper, or by redefining the process boundaries closer to the used actuator (regulate the circuit mass balance instead of feed-hopper level). The presented control structures provide means to achieve a consistent cone crusher performance and size reduction. This facilitates efforts to improve the plant’s performance and increases the plant’s overall stability."

Jan 1, 2014

By A. G. Bulaev

Biohydrometallurgical technologies based on activity of acidophilic microorganisms oxidizing ferrous iron, sulfur, and sulfide minerals are widely used to extract base and noble metals from sulfide ores and concentrates. As sulfide minerals oxidation is exothermic, industrial processes are usually preformed at 40–50°C. Moderate thermophiles predominate under these conditions. Most of moderately thermophilic acidophilic microorganisms that oxidize metal sulfide are mixotrophic, i.e., they use both organic nutrients and CO2 as carbon sources. Carbon availability is crucial for microbial activity and affects efficiency of biohydrometallurgical processes. Aeration with CO2-enriched air is often used to increase microbial activity in biooxidation reactors. Organic nutrients can be used as alternative carbon source for moderately thermophiles performing biooxidation of sulfide concentrates. We performed several experiments with different sulfide concentrates to study effects of organic carbon sources on biooxidation efficiency and demonstrated that application of such organic nutrients as yeast extract (YE) and molasses made it possible to increase biooxidation efficiency. For example, addition of 0.02% YE in the nutrient medium increased biooxidation rate of pyrite–arsenopyrite gold bearing and chalcopyrite concentrates in batch mode at 45°C. YE addition increased oxidation rate of sulfide sulfur and gold recovery level from 65 to 87% and from 73 to 81%, respectively. Similarly, YE addition increased copper extraction from 47 to 54%. At the same time, YE addition increased efficiency of biooxidation of pyrite–arsenopyrite gold bearing concentrate in continuous mode. Without YE addition, oxidation rates of pyrite and arsenopyrite were 65.7% and 94%, while gold extraction was 71%. YE addition (0.02%) made it possible to oxidize 74% and 95 % of pyrite and arsenopyrite and extract 78% of gold. Addition of molasses (0.02%) similarly affected biooxidation efficiency. Thus, addition of organic nutrients in nutrient media is a promising strategy for improvement of biohydrometallurgical processes.

Jan 1, 2018

By O. Guven, I. Karaagaçlioglu, O. Ozdemir, M. Çelik

In this study, the effect of morphological properties such as shape factors and roughness of the glass beads on their flotation efficiency were determined using image analysis and profilometer methods. There is a considerable correlation between the shape factors, surface roughness and flotation behavior of the glass sample. These results indicate that as the particle shape is away from roundness and smoothness, it acquires more hydrophobicity.

Jan 1, 2014

By R. D. van der Weijden, W. F. C. van Wageningen

"Copper(II) can be recovered or removed from acidic copper sulfate solutions as cuprite or metallic copper powder by reduction with carbohydrates (van der Weijden et al., 2001, 2002). In order to make this process suitable for a commercial scale pipe reactor, process conditions and reactor configuration need to guarantee proper throughput of the dilute suspension. This is where crystal engineering also comes into view. Copper powder characteristics, such as size and shape of particles, influence the tendency to adhere to reactor walls and to agglomerate, which in turn influence the throughput. Furthermore, separation, drying, packaging and product quality, are dependent on the powder characteristics.In this paper the effect of both chemical and physical parameters on the shape and size of particles were systematically studied in a number of autoclave experiments. These parameters include mixing, Cu(II) concentration, pH, temperature, seeding, use of additives and reactor materials. Additionally, Monte Carlo simulations of copper growth inside a Kenics static mixer were made. Results show that the use of additives, and the use of static mixers influence particle characteristics the most."

Jan 1, 2003

By Massimiliano Zanin, William Skinner, Keith Quast

With the scarcity of fresh potable water on mining sites, particularly those in arid and remote regions, the use of sea water is being contemplated and actually used at a number of mineral concentrators worldwide. The use of sea water, with its associated high dissolved solids content and ionic strength will affect all aspects of processing (e.g. frothing and froth stability, buffering capacity for pH control, solubility of minerals and corrosion of media and equipment). Selective depression of pyrite is more difficult in sea water due to the increased lime addition to achieve a high pH. This results in a reduction in molybdenite recovery. The use of grinding media with various chromium contents and its effect on subsequent Cu and Mo flotation has been investigated in the current study, with both grinding and flotation testing conducted in artificial sea water. Pulp chemistry (pH, Eh and DO) have been logged during grinding, and flotation testing was conducted on subsequent slurries. The flotation results show that the system is remarkably robust and able to cope with wide ranges of pulp chemistry parameters. The effects of artificial sea water on the surfaces of minerals during grinding have been examined using X-Ray Photoelectron Spectroscopy

Jan 1, 2014

By Seungwoo Park, Gaurav Soni, Roe-Hoan Yoon, Hyunsun Do, Kaiwu Huang

In a flotation froth (and foam), air bubbles become larger due to coalescence, causing bubble size to increase, bubble surface area to decrease, and hence casing less hydrophobic particles to drop off to the pulp phase below. Thus, bubble coarsening provides an important mechanism by which product grades are increased. On the other hand, excessive bubble coarsening results in low recoveries. In the present work, a model describing the process of bubbles becoming coarser in a foam as they rise to the top by deriving a mathematical relation between the Plateau border area, which controls film drainage rate, and the lamella film thickness, which controls bubble-coalescence rate. The model has been derived by assuming that liquid drainage rate increases due to slip at the air/water interface, and that the critical rupture thickness is determined by the capillary waves created by thermal motion. The model developed in the present work can predict the bubble size ratio between the top and bottom of a foam as functions of aeration rate, foam height, and surface tension (frother dosage). The model predictions are in good agreement with the changes in bubble sizes measured using a high-speed camera.

Jan 1, 2014

By Diego Mesa, Willy Kracht

Frothers may be classified as weak or strong depending on their ability to produce stable froths, which is related to the amount of water that they transfer from the pulp to the froth. They can also have an effect on the non-selective mechanism of recovery by entrainment, implying that both selectivity and froth stability are, at least to some extent, frother dependent. Solids, on the other hand, also have an effect on froth behaviour. Clays, which are characterized by their small particle size, laminar shape, and high specific surface, tend to report to the froth phase and have an enormous impact on both froth stability and the overall performance of the flotation process. The purpose of this work is to shed light on the effect that different frothers have on the froth behaviour when clays are present. In order to do that, two sets of experiments were conducted using frothers from the families of alcohols and polyglycols. For each test, the equilibrium froth height was measured at different frother concentrations in an agitated machine with an acrylic square-base cell that was 11 cm wide and 25 cm high. The cell was designed in such a way that froth was able to grow without concentrate discharge. In the first set of tests, pure clays such as kaolinite and montmorillonite were used. In the second set, an actual copper sulphide ore with a high content of clays was used as solid phase. The results, expressed as curves of equilibrium froth height against frother dosage, showed a coupled effect of frother-clay on froth behaviour for both sets of experiments. In some cases, the froth grew up until the border of the cell with only a few parts per million of frother. In other cases, the equilibrium froth height varied smoothly with frother dosage. The results suggest that choosing the right frother can be of use for controlling the froth behaviour when dealing with clay-rich froths, using frother dosage as the control variable. The application of these findings at industrial scale are discussed and some recommendations are given.

Jan 1, 2018

By M. E. Holuszko

This paper reports the results of induction time measurements carried out on the products of film flotation of galena and sphalerite particles from three different size fractions (38~75µm; 75~150µm; 150~212µm). As expected, the tailings (sinking fraction) from film flotation at any particular surface tension, had always longer induction times than the concentrates (floating fraction), for both minerals. The difference between the induction times of film flotation concentrate and tailings could be as little as 2.5 ms and 5 ms, and as large as 6 ms and 10 ms. These differences can be related to the different hydrophobic characteristics of these fractions, as expressed by (?c) and composition of the particular film flotation product. In addition, the induction times of the larger particle size fraction were shown to be longer than for the corresponding smaller particle size fraction, even though the average ?c(degree of hydro-phobicity) of these fractions appears to be very similar. Desliming, Cu activation and collector addition to the sphalerite samples was shown to decrease the induction time values significantly.

Jan 1, 2014

By Jan J. Cilliers, Nicolas Barbian, Esther Ventura-Medina

"Froth structure and stability are known to play an important role in determining flotation recovery and selectivity. An industrial sampling campaign was performed to develop a clearer understanding of the effect of flotation variables on froth stability and the role played by the resulting stability on flotation performance.Froth stability was estimated as the fraction of bubbles bursting on the surface of the froth through image analysis and the solids loading on the bubbles at the top surface. It was generally found that high air flowrates resulted in a drop of froth stability showed by a drop in the fraction of air overflowing and a decrease in the solids loading and simultaneously produced low copper recoveries and low concentrate grades. Deep froths only allowed a small fraction of air to overflow and consequently produced low recoveries. An increase from a standard to high frother dosage did not result in a larger fraction of air overflowing, hence producing low recoveries. Likewise, low frother addition only allows low recoveries because the resulting unstable froth cannot support itself. Low aeration was found to be preferential as it allowed high particle loading, therefore high bubble stabilisation, and low gangue entrainment, resulting in the highest flotation performance.Additional laboratory tests were performed to introduce a new stability parameter and to give a clearer understanding of the effect of flotation variables on froth stability. The results confirmed some of the observations made on the plant."

Jan 1, 2003

By Sergio Castro, Janusz Laskowski

In the flotation in highly concentrated electrolyte solutions not only ionic strength but also chemical composition, flotation pH and mineral properties play an important role. As a result an improvement or depression may be observed. A strong improvement in the floatability of hydrophobic bituminous coals and other inherently hydrophobic minerals is characteristic for the "salt flotation process", which is carried out in concentrated electrolyte solutions at natural pH and without addition of any flotation reagents. However, pH is a key factor when saline and hipersaline waters with hydrolyzing metallic ions are used as process water. In the case of flotation of Cu-Mo sulfide ores in seawater, molybdenite is strongly depressed by the Mg2+ hydrolysis products when pH is raised to depress pyrite. Process water with a high content of Mg2+ and Ca2+ ions, and this also includes seawater, have deleterious effect on the anionic flotation of industrial minerals with fatty acids. The flotation of potash ores is carried out in NaCl-KCl saturated brine (6-7 mole/L of NaCl and KCl) with the use of long-chain amines. Such a high electrolyte concentration changes dramatically the amine Krafft point making the collector insoluble in brine; its mode of action entirely differs from that in conventional flotation processes.

Jan 1, 2014

By M. Pelser, C Aldrich

"The presence of calcium and magnesium in the hydrometallurgical processing of base metals, results in a number of process difficulties. These problems range from the contamination of the final product (where the final product is a precipitate) to high energy consumptions and large bleed streams during electrowinning. Calcium poses an additional problem in sulphate solutions owing to the low solubility of its sulphate salts. This can easily lead to a process stream that is supersaturated with calcium sulphate, resulting in unwanted solids formation within the process equipment.Several processes are reviewed for the control of calcium and magnesium. Of these, fluoride precipitation was selected for experimental investigation. This method involves the addition of a soluble fluoride to precipitate CaF2 and MgF2. The experiments showed high selectivity for calcium and magnesium over the base metals. The experiments also showed magnesium precipitation to dominate for calcium to magnesium molar ratios greater than 1:3.To avoid the domination of magnesium precipitation, a flow sheet is proposed whereby only a portion of the base metal stream is subjected to fluoride precipitation. For the precipitation, a 10% excess of ammonium fluoride is used to remove the maximum amount of calcium and magnesium. After precipitation and solid-liquid separation the split-stream is returned to reduce the overall calcium and magnesium concentration of the base metal stream."

Jan 1, 2003

By Seher Ata

This paper is concerned with the coalescence behaviour of two bubbles in dilute solutions of cetyltrimethylammonium bromide, methyl isobutyl carbonil and triton x-100. Two bubbles were produced at the tips of adjacent capillaries and the time elapsed between the first contact of the bubbles and film rupture was determined by means of a high speed camera. It was found that the amount of surfactant required to stabilise the bubbles increased in order of CTAB>TX-100>MIBC. The probability of coalescence decreased sharply with increasing surfactant concentration in CTAB and TX-100 solutions while with MIBC each bubble pairs resulted in coalescence, giving hundred per-cent coalescence probability.

Jan 1, 2014

By Irena Grigorova

"Vermiculite is a naturally occurring mineral compound composed of shiny flakes, resembling mica. Worldwide, vermiculite has been used in various industries since 1920. When heated to a high temperature, flakes of vermiculite expand several times their original size. The expanded vermiculite is a lightweight, fire-resistant, absorbent, and odorless material. These properties allow vermiculite to be used to make numerous products, as an additive, for example to potting soil, in agricultural, construction, horticultural and industrial applications, including pesticides, insulation, potting mixes, brake pads, sound deadening materials, fire protection, paints, sealants, insulating concrete and etc. Over recent years researchers have been looking for effective economic and environmental methods and solutions for fine technological waste utilization. As a result of vermiculite ore processing large quantities of fine waste dust are formed. Until now there has been no application for this waste product. Currently this waste product is stockpiled using valuable land space, and is a potential contaminant. The paper presents the results of a study on the possibility to obtain briquettes from fine vermiculite by-product. The particle size distributions, chemical and mineralogical compositions of vermiculite were determined. It was established that consolidation of vermiculite dust by methods of briquetting and its consequent application in agriculture as meliorants for physico-chemical treatment, improves soils aeration structure and properties."

Jan 1, 2014

By K. C. Corin, M. S. Manono, J. G. Wiese

"It has been suggested that hydroxo species, particularly those of calcium, selectively adsorb onto gangue minerals. Such species enhance the depressive action of carboxymethyl cellulose (CMC) onto gangue via an acid-base interaction between the positively charged mineral surface and the negatively charged CMC molecule. Thus, the hydrophilicity of gangue minerals is enhanced, preventing the dilution of the concentrate. However, as there is little evidence to support these claims it is important to investigate. Adsorption data and mineral surface charge analyses will allow a fundamental understanding into how electrolytes and their ionic strengths affect gangue-depressant adsorption. It is strongly anticipated that decoupling these effects will allow process operators to tailor their process water quality needs towards best flotation operating regimes and in the long run effect closed water circuits. Thus, using talc and pyrrhotite as proxies, this work investigates the influence of the ionic strength of process water on the adsorption of CMC onto minerals in sulphide flotation.INTRODUCTIONThe phenomenon of gangue depression in mineral flotation is of critical importance as regards the attainment of a required concentrate grade. This thus suggests that the depressant of choice has to have a highly selective affinity for the targeted gangue minerals. This would ensure the necessary prevention of gangue from reporting to the concentrate without inadvertently depressing the value bearing mineral. The chemistry of the environment regulates the manner in which gangue depression occurs. In sulphide flotation, polysaccharides are used as depressants of choice to depress naturally floatable gangue which may in the case of Merensky ores exist as talc. The two widely used polysaccharides in the South African context are carboxymethyl cellulose (CMC) and modified guar gum. It is suggested that polysaccharides depress gangue by rendering the surface of gangue hydrophilic or by preventing the formation of hydrophobic layers on gangue mineral surface, forming large gangue aggregates and thereby increasing their heterocoagulative nature (Shortridge et al., 1999)."

Jan 1, 2018

By Masanori Mori, Hajime Miki, Osamu Ichikawa, Tsuyoshi Hirajima, Mitsuru Sawada, Keiko Sasaki

For pretreatment of selective flotation, surface oxidation of chalcopyrite and molybdenite was applied by oxygen plasma then the minerals were washed by solution at pH 9 with oxygen bubbling. Surface characteristics of these minerals were investigated with AFM, XPS, zeta potential and contact angle measurements. Contact angle of chalcopyrite and molybdenite decreased a lot by plasma treatment. When they were washed with pH 9 solution with oxygen bubbling, contact angle of molybdenite increased whereas chalcopyrite one kept low. Adhesion force measurements indicated similar behavior. Result of flotation experiments indicated low recovery of both chalcopyrite and molybdenite after plasma treatment and only molybdenite recovery became higher after washing. Selective flotation of chalcopyrite and molybdenite could be achieved with this process. Possible mechanism of selective flotation was proposed from the results of XPS, AFM, etc.

Jan 1, 2014