Flotation Separation Process Research Articles

Comparative evaluation of particle separation efficiency based on carbon dioxide and air bubble sizes in flotation separation processes

Micro-sized carbon dioxide gas bubbles can be applied as alternatives to air bubbles in flotation separation processes, which can reduce CO2 emissions as well as decrease energy consumption. CO2 and air bubbles were used as particle collectors in the flotation process to investigate and compare the collision efficiency and particle separation characteristics. This study measured bubble size distributions and simulated the single-collector collision (SCC) model that has been applied extensively to flotation processes. The diameter of the air bubbles was found to decrease as the saturator pressure increased, but the size of the CO2 bubbles increased when the pressure exceeded 151.99–202.65kPa. When using CO2 bubbles as collectors to separate particles in water, the simulation results from the SCC model expressed in terms of bubble volume concentration (BVC) was related to the lower collision efficiency of CO2 bubbles, and the bubble number concentration (BNC) rather than the BVC to the effects of macrobubbles. The findings of this study suggest that the advantages of CO2 bubbles used as collectors in particle separations would be lower operating costs and reduced greenhouse gas emissions from water and wastewater treatment plants.

Visualized study on the interaction between single bubbles and curved solid surface in flotation separation process.

The present study has been devoted to bubble-curved solid surface interaction in water, which is critical to the separation of suspended particles by air flotation. For this purpose, two particular stages of the interaction (collision and attachment) have been examined visually using high-speed photography in a laboratory-scale flotation column. The effects of the surface material and surfactant concentration on these two stages have been also studied quantitatively. The considered solid materials are the cleaned glass as hydrophilic surface and Teflon as hydrophobic surface. The experimental results show that the presence of surfactant significantly affects the collision and rebound process of a gas bubble, while there is no obvious effect of the surface material on the rebound process. An increase in surfactant concentration has been observed to suppress the rebound number and maximal distance of the bubble from the surface. Moreover, the three-phase contact time of the bubble is a strong function of the surfactant concentration and surface hydrophobicity as well as of the bubble diameter. Another important finding is that the bubble attachment is only observed at the hydrophobic Teflon surface below the surfactant CMC (critical micelle concentration). Results of this study are relevant for deep understanding of the attachment mechanism and to determine the proper conditions for a selective flotation process.

Research on Flotation of Copper Sulfide Ore in Yunnan Province

Floatation experimental research is carried out on a certain complicated ore containing mixed sulphides in Yannan province. For the characteristics of the mine and the scene of the test requirements, the use of mixed flotation-separation process has achieved a successful recovery of useful elements. Combination inhibitors can effectively achieve the separation of copper and sulfur .Under the proper process conditions ,the good technical indexes were obtained.

폐금속 광산지역 농경지 납, 아연 오염 토양의 중금속 고도선별

The study is to propose the optimal separation technique of heavy metals (Pb and Zn) contaminated in soil for improving the removal efficiency by various applicable techniques. The heavy metal contaminated soil samples near abandoned mine X-1 and X-2 were used for the study. Firstly, the wet classification process was shown more than 80% of removal efficiency for lead and zinc. Meanwhile, the magnetic separation process was shown low removal efficiency for lead and zincs because those heavy metals were non-magnetic materials. For the next step, the flotation separation process was shown approximately 24.4% of removal efficiency for zinc, while the gravity concentration process was shown approximately 57% of removal efficiency for lead, and 19.9% of removal efficiency for zinc, respectively. Therefore, zinc contaminated in soil would be effectively treated by the combination technique of the wet classification and the flotation technique. Meanwhile, lead contaminated in soil would be effectively treated by the combination technique of the wet classification process and the flotation process. Furthermore, the extraction of organic matter was shown more effective with aeration, 3% of hydrogen peroxide and 3% of lime such as calcium hydroxide.

Present Status of China's Hematite Processing Technology Study

This paper describes the hematite beneficiation technology progress and equipment,the current research has through biological flotation, flotation and selective aggregation separation process for separating iron minerals.Can reach a maximum of iron grade of 67.50%, metal recovery rate of 75% of the final concentrate of current hematite beneficiation process for gravity separation magnetic separation reverse flotation process.

Theoretical study of 2-mercaptobenzimidazole derivatives as chelating collectors in flotation separation of galena and pyrite

Three 2-mercaptobenzimidazole derivatives, 1-ethyl-2-mercapto-benzimidazole (EMBI), 1-propyl-2-mercapto-benzimidazole (PMBI) and 1-benze-2-mercapto-benzimidazole (BMBI), were designed and synthesized in the paper, and their collecting behavior in flotation separation process of galena over pyrite was investigated by flotation tests on lab scale. Apart from this, density functional theory (DFT) calculation and molecular dynamics (MD) simulation were also used to elucidate their collecting mechanism. Results of flotation tests indicate that separation of galena over pyrite is feasible at pH 10, and BMBI has the best floatability among three collectors. DFT calculations show that BMBI has the highest occupied molecular orbital (HOMO) energy and strongest collecting efficiency. The adsorption mode of three collectors on mineral surface by MD method indicates that the combination processes of collectors with mineral are exothermic, and the higher the binding energy, the firmer the collector adsorbs on the mineral surface and the higher collecting capacity. The calculation results demonstrate that the floatability of three collectors follows the order: BMBI>PMBI>EMBI, which is highly consistent with the flotation tests.

Novel Condensed Ring Carboxylic Hydroxamic Acid Studied in the Flotation Behavior of Diaspore and Aluminosilicates

Flotation reagents are the critical technique in the flotation separation process for desilication. Aimed at the highly selective reagent for direct flotation of diasporic bauxite, a novel compound, dibenzo-1-(7-carboxyl-4-hydroxyl bicycle [2.2.2] octan-7,8-diyl) carboxamic acid (DBCA) with two functional groups carboxyl and hydroxamate in the same molecule, was synthesized through Diels-Alder reaction followed by oximation reaction. Subsequently, the floatability of diaspore, kaolinite, and illite was measured by using DBCA as a collector, the interaction mechanism between minerals and DBCA was investigated through zeta potential measurements and FT-IR spectrum, and the structure and property relationship of the collector were also discussed. The flotation experimental results showed that DBCA had a very strong collecting ability for diaspore, while poor activity was observed for kaolinite and illite. The interaction of DBCA on diaspore surfaces may be mainly dominated by chemical bonding as the formation of three chelation rings; however, those on the surfaces of kaolinite and illite are mainly hydrogen bonding or physical adsorption. Consequently, it is possible to separate diaspore from such aluminosilicates as kaolinte and illite employing DBCA as a collector.

Flotation techniques for separation of diaspore from bauxite using Gemini collector and starch depressant

The floatability of diaspore and three kinds of silicate minerals, including kaolinite, illite and pyrophyllite, by a cationic Gemini surfactant as collector and starch as depressant was investigated as function of reagents concentration and pulp pH. Further studies of artificially mixed minerals and bauxite ore were also detailedly conducted. At last, the pre-desliming reverse flotation separation process was adopted. It can be concluded that the combinational use of a Gemini cationic collector and the starch depressant is effective. The concentrates with Al 2O 3 to SiO 2 mass ratio of 9.66 and the recovery of Al 2O 3 of 71.73% are obtained from natural bauxite ore (A/S=5.70) at pH value of around 10.

Improved epoxidation process

In this work, a new technique process for processing Cu-Zn mixed ores containing chalcopyrite and marmatite was proposed to avoid the complex Cu-Zn flotation and extraction separation processes, as well as for the comprehensive utilization of abandoned silver-containing zinc leaching residue (ZLR). In the first step, stepwise bioleaching of Cu-Zn mixed ores in the presence of mixed moderately thermophilic microorganisms and Fe3 + was conducted for recovering Zn from marmatite. Copper was then efficiently extracted from the copper-containing bioleaching residues through catalytic bioleaching by using ZLR as catalyst. The final bioleaching residues were subsequently leached by thiourea for recovering Ag efficiently. The provided technique process accomplished the stepwise dissolution of Cu-Zn mixed ores and the comprehensive utilization of silver-bearing ZLR. The intermediate species, the electrochemical dissolution process and the electrochemical interactions between chalcopyrite and marmatite were also discussed to interpret the detailed mechanisms of stepwise bioleaching.

Radionuclides, heavy metals and fluorine incidence at Tapira phosphate rocks, Brazil, and their industrial (by) products

Inorganic phosphate fertilizers may contain radionuclides, heavy metals and fluorine. This paper presents the possible environmental hazards from Tapira phosphate rocks and their (by) products (Brazil) utilized as phosphate fertilizers. The activity concentration of 238U, 234U, 226Ra and 40K in Tapira phosphate rocks is within the world range for these rock types. The 232Th activity concentration is higher than the mean reported in phosphate rocks. A value of 2184 nGy h −1 was obtained for the exposure dose rate in Tapira phosphate deposit area, which is indicative of a high background radiation area. The flotation-separation process causes the incorporation of no more than 9%, 11% and 24% of radionuclides, heavy metals and fluorine, respectively, into the phosphate concentrate. The radionuclides and heavy metals existing in phosphate fertilizers applied in Brazilian crops according to the recommended rates, do not raise their concentration in soils to harmful levels.

Dynamic adsorption of sodium dodecylbenzene sulphonate and dowfroth 250 onto the air–water interface

Surface active agents (surfactants) are widely used to control the interfacial properties of the gas–liquid and liquid–1 interfaces in the froth flotation separation process. The dynamic adsorption of the surfactants is critical to flotation which is a kinetics-controlled process. This paper examines the dynamic adsorption of sodium dodecylbenzene sulphonate and Dowfroth 250, which is a commercial mixture of polyglycols used to control the dispersion of air in flotation. The dynamic adsorption process was modelled based on either the diffusion-controlled or kinetics-controlled theories. The numerical computation was applied to solve the non-linear governing equations. The dynamic adsorption of the surfactants was measured in terms of the dynamic surface tension using the pendant drop method. Comparison between the theoretical results and experimental data shows that the kinetics-controlled model for the surfactant adsorption describes the experimental data better for both surfactant systems.

Bubble-Particle Interaction Measured by Atomic Force Microscopy

Interaction forces between solid particles and air bubbles during flotation are of significant academic and practical importance. An atomic force microscope (AFM) probe technique was used to measure the interaction forces between an air bubble and a hydrophobic/hydrophilic spherical particle. In the case of hydrophobic spheres, strong attraction between the surfaces, leading to the rupture of the intervening water film and the attachment of the particle to the air bubble was observed. In the case of hydrophilic spheres, the rupture of the intervening water film and the attachment of the particle to the air bubble did not take place. In each case, however, the repulsive interaction force during approach prior to attachment was dependent on the speed of the bubble (the piezoelectric translator) indicating that the hydrodynamic interaction between the bubble and the particle at short separation distances is significant. The force analysis together with the deformation of the gas-liquid interface during the interaction is described, which gives a more detailed description of the bubble-particle interaction. The outcome of this research increases our understanding of the flotation separation process.

Quasistatic detachment of a sphere from a liquid interface

In this paper the problem of removing a spherical particle initially attached to a liquid–gas interface is analytically treated. In particular, the Derjaguin equation for small radii is used to derive a closed-form approximate expression for the work of detachment of the sphere from the interface. Expressions corresponding to the prescribed displacement condition and the applied force condition, which seems to be the relevant condition for the flotation separation process, are presented. A special effort has been made to closely compare analytical results with data obtained through the exact numerical treatment of the detachment process. Results show that proposed expressions are sufficiently accurate to calculate the energy required to detach the sphere from the interface as soon as the sphere radius is small compared to the capillary length. Validity limits are specified.

Biodesulphurization as a complement to the physical cleaning of coal ☆

Physical and biological processes have been combined with a view to reduce the sulphur and ash content of finely ground coal. The coal used was a semianthracite from the North Spain Coal Field. A sample of several kg in a coal/water suspension with a w/w concentration of 15% was subjected to a physical treatment combining cyclone and flotation separation processes. Representative samples were taken from each of five size fractions: original feed and the physical separation products, which were screened through water into sub-samples classified by particle size. Each fraction from the physical separation and the screening was analysed for ash and sulphur. The elimination yield of the hydrocyclone was 22% of ash and 21% of sulphur. The figure for ash raised to 41% when the hydrocyclone and flotation equipment were both used, with no change in sulphur elimination. In turn, the biodesulphurization treatment applied in addition to the two processes raised the respective yields to 59 and 42%. The change in the calorific value of the coal was hardly significant, while sulphur emissions, expressed as g S/GJ were reduced by 51%. Additionally, an assessment was made of the thermal behaviour of the various samples from the physical and biological treatment by means of programmed temperature combustion analysis carried out by a thermogravimetric equipment.

Modeling flotation separation in a semi-batch process

A model for a semi-batch flotation separation process has been developed, based on available microprocess probabilities, and compared to experimental data obtained using a WEMCO laboratory flotation cell. In general, the model predicts the correct experimental trends. In many cases, the model also predicts removal efficiency very well. Parametric studies reveal that the model predictions are sensitive to a stability parameter, the turbulent energy density in the flotation cell, the contact angle between the solid particle and fluid, and the ratio of initial-to-critical film thickness.

Empirical Equations for Meniscus Depression by Particle Attachment

In this paper the problem of calculating the depression of the gas–liquid meniscus by the particle attachment was solved. The analytical approximate equations obtained for small and large radii, r tpc, of the three-phase contact were analyzed and compared to the available numerical results. The Derjaguin equation for small r tpc and the analytical results for large r tpc are accurate for r tpc/ L≤0.2 and r tpc/ L≥2, respectively, where L is the capillary length. For the meniscus depression with r tpc/ L from 0.2 to 2, the empirical equations were obtained based on the asymptotic analysis of the analytical approximate solutions. The empirical numerical constants were obtained by fitting to the exact numerical results. The empirical equations together with the analytical approximate equations provide the accurate predictions for the meniscus depression for the whole range of the radius of the three-phase contact and are expected to be useful for modeling the detachment interaction in the flotation separation processes.

Research and Development of Novel Surfactants

Surfactants are widely used in numerous applications, including detergents, emulsification, flotation, foaming control, surface-wetting modification and surfactant-based separation processes. The fields of surfactant chemistry and application are now so vast, there have been so many interesting recent development in its. Chemically, surfactant molecules usually are classified according to the nature of the hyrophilic group, in anionic, cationic, amphoteric and nonionic type. While, the nature of the hyrophobic groups are usually less pronounced than in the nature of the hydrophilic group. Generally, they are long-chain hydrocarbon residues. Polysiloxane and perfluoroalkyl group have also been used as the hydrophobic group in the surfactant. Recently, hybrid type surfactants having both hydrocarbon and fluorocarbon group were developed. Furthermore, many other functional surfactants have been newly developed by sophisticated organic synthesis and enzymatic reactions. Here, we report the overview of surfactants, especially recent research and development of novel surfactants.

A Study of Kinetics on Induced-Air Flotation for Oil-Water Separation

Abstract Induced-air flotation makes use of the centrifugal force of a high-speed backspin impeller through which gas is introduced at the top and liquid at the bottom. The gas and liquid become fully intermingled and, after passing through a disperser outside the impeller, form a multitude of gas bubbles, thus completing the flotation separation process of a liquid-solid or liquid-liquid heterogeneous separation process of a liquid-solid or liquid-liquid heterogeneous system. The flotation machine used for treating oily sewage generally belongs to the four-cell series. Its good points are that the machine has a high removal efficiency for oil separation, shortens retention time, and has great treatment capacity. The device has been widely used in treating oily sewage in recent years (1, 2). In order to provide a basis for establishing a method of design computation and for screening appropriate chemicals, this study was initiated to gain an understanding of the variables controlling the induced-air flota...