Modeling of the Concentration Field of Solid Phase in a Hydrocyclone in Suspension Separation by Pressure Flotation

A mathematical model of suspension separation by pressure flotation in a hydrocyclone was developed. The continuity equation was solved numerically for a flux of particles of the solid phase in a flow of a non-Newtonian suspension in a hydrocyclone. The concentration field of solid particles was determined. The effect of the defining similarity criteria on the distribution of concentrations was studied.     

Simulation of suspension separation by two-stage pressure-head flotation in a cylindrical direct-flow hydrocyclone

A mathematical model of separation of suspensions with a non-Newtonian dispersion medium by two-stage pressure-head flotation in a cylindrical direct-flow hydrocyclone was developed. A system of differential equations describing convective diffusion and motion of a particle-bubble complex was solved numerically. The concentration field was modeled and integral separation parameters were determined.     

Analysis of droplet behavior in a de-oiling hydrocyclone

A mechanical separation process in a de-oiling hydrocyclone is described in which disperse oil droplets are separated from a continuous water phase. This separation process is influenced by droplet breakage and coalescence. Based on experimental data and simulation results in a stirred tank, a modified breakage model, which can be applied to droplet breakage in the de-oiling hydrocyclone, is developed. Then, a simulation model is developed coupling the numerical solution of the flow field in the hydrocyclone based on computational fluid dynamics (CFD) with population balances. The homogenous discrete method and the inhomogeneous discrete method are applied for solving the population balance model (PBM). The investigations show that the numerical results obtained by the simulation model coupled with the modified PBM using the inhomogeneous discrete method are in good accordance with experimental data under a high flow rate. According to this simulation model, the effect of three different inlet designs on the separation efficiency of the de-oiling hydrocyclone has been discussed. The results indicate that the separation efficiency of the de-oiling hydrocyclone can be improved with an appropriate inlet design.     

Selective recovery of polyhydroxyalkanoate inclusion bodies from fermentation broth by dissolved-air flotation

Selective dissolved-air flotation for the separation of medium-chain-length polyhydroxyalkanoate (PHA) inclusion bodies (IBs) from Pseudomonas putida cell debris is investigated. Measurements show that both P. putida cell debris and PHA IBs have an iso-electric point of approximately pH 3.5. Selective aggregation and as a result selective flotation of PHA IBs was observed near this pH. Qualitative prediction of the aggregation behaviour was possible on the basis of the Van der Waals, hydrophobic and electrostatic interactions. In some cases however, the stability of the suspension could not be explained with these forces alone. It was therefore suggested that additional interactions, such as steric/brush effects, play an important role in the aggregation process.     

Optimizing Geometric Parameters in Hydrocyclones for Enhanced Separations: A Review and Perspective

Hydrocyclones have been extensively applied for solid–liquid or liquid–liquid separations in various industries. However, the exact mechanisms underlying the enhanced separation technologies based on the optimization of geometric parameters of hydrocyclones remain unclear, and a number of research teams have performed numerous studies to enlarge the application scope of hydrocyclones by optimizing geometric parameters. This review provides a comprehensive state-of-the-art review of hydrocyclone enhanced-separation technologies. The enhanced-separation technologies are categorized into ten groups: cylindrical section, inlet, vortex finder, underflow pipe, conical section, hydrocyclone inclination angle, hydrocyclone insertion, conical-section/apex water injection, reflux device, and multi-hydrocyclone arrangement. These enhanced-separation technologies were analyzed and summarized according to the key separation-performance parameters of hydrocyclones, such as separation efficiency, cut size, split ratio, energy consumption, and capacity. It is expected that both the reviewed contents and the proposed challenges and future methodologies and technologies may provide research fellows working in this field with an improved understanding of enhanced separation technologies of hydrocyclones.     

Entrapment efficiencies of hydrodynamic boundary layers on rising bubbles

Flotation and separation practice shows that fine hydrophilic solids are often drawn into the froth product. The occurrence of this unwanted event in the classical froth flotation has led to the idea of using it for the separation by size of ground materials. Thus, a method for the extraction of hydrophilic fines by foaming of a suspension was proposed. The aim of the present study is to relate this phenomenon to the residence time of the particles in the vicinities of the rising bubbles. Dynamic interactions of fine solids with rising bubbles cause perturbations in the background flow field. A procedure for the mathematical modeling of these disturbance effects is proposed. The initial idea is that the particles lag behind the background bubble-driven flows. A key point is the possibility of classifying fine entities according to a general criterion, containing only parameters of the outer flow. The basic result is that there exists a range of particle and bubble dimensions for which this entrapment is optimal. The proposed model investigation gives a concise explanation for the observed capture of fine solids in many flotation and separation processes.     

Synthesis of Monodisperse Poly(chloromethylstyrene divinylbenzene)Particle and Its Applications

Poly(styrene-divinylbenzene)(PS-DVB)particlesarethemostcommonlyusedpolymericchromatographicstationaryphase.However,theirhydrophobicnaturelimitstheirusageinbiochemicalseparations.ChemicalmodificationofPS-DVBmaybeusedtoincreasetheirpolarityfortheseparationofbiomacromolecules.Becausepoly(chloromethylstyrenedivinylbenzene)(PS-CH2Cl)containsreactivechloromethylgroups,ithasmanyadvantagesoverPS-DVBinchemicalmodification.However,untilnow,theyhavebeenpreparedbysuspensionpolymerization.Thismeth…     

Effect of Rheological Properties of the Dispersion Medium on Separation of Suspensions in Hydrocyclones with Various Working Space Configurations

The model of separation of suspensions with a non-Newtonian dispersion medium in a cylindroconical hydrocyclone, which takes into account the effect of the Coriolis force on solid particles, was constructed and applied to analysis of the rheological properties of the dispersion medium on separation of suspensions in hydrocyclones with various working space configurations.     

Optimization of partitioning process parameters of chloramphenicol in ionic liquid aqueous two-phase flotation using response surface methodology

Ionic liquid aqueous two-phase flotation (ILATPF) is a green and effective separation and purification method, which combines solvent sublation and ionic liquid aqueous two-phase extraction system. This investigation attempts to study and optimize the partitioning conditions of chloramphenicol (CAP) in ILATPF. An experimental design of response surface methodology (RSM) was used to evaluate the influence of the variables, including the type of ionic liquid (IL), K₂HPO₄ concentration, flotation time and gas flow rate on CAP flotation. Quadratic polynomial models were adjusted to the data to predict the behavior of two responses, namely the partition coefficient (K) and sublation efficiency (E) of CAP. The optimal flotation conditions were found using [C₆mim]Cl, 0.74 g/mL K₂HPO₄, 50 min flotation time and 50 mL/min gas flow rate, which ensured K = 405.71 and E = 93.16 %. It was observed that the effect of the four factors on K and E of CAP was flotation time > gas flow rate > the type of IL > K₂HPO₄ concentration. The ILATPF was proved effective for CAP separation in aqueous phase, and RSM was revealed to be an appropriate and powerful tool for experimental design of CAP separation by ILATPF.     

Separation and determination of the sulph-hydryl flotation collectors using ion-interaction chromatography

Summary This paper discusses simple and practical methods for the separation and determination of various sulph-hydryl flotation reagents by ion-interaction chromatography. Physical and chemical parameters such as column length, the support, and the constituents of the mobile phase and their respective concentrations were considered. A set of capacity factors, determined for a given set of conditions, is used to assist in the design of separation methods. The developed methodology enables the determination of various sulph-hydryl compounds in a given mixture of flotation reagents, distinction between compounds with the same functionality, and the separation of structural isomers of a particular compound. The applicability of the methods was demonstrated by the analysis of some commercial flotation reagents, as well as samples generated in an investigation of synergism of the sulp-hydryl collectors.     

A mathematical model for predicting oil-water separation efficiency in a de-oiling hydrocyclone

The de-oiling hydrocyclone is among the most effective devices to recover oil from oily wastewater. In this work, a new model is theoretically developed to predict the separation efficiency of oil droplets in hydrocyclones. According to the analysis of the flow pattern, the droplet dynamics, and oil concentration distribution in the de-oiling hydrocyclone, the differential equation for the new model is established based on the principle of the mass balance of oil droplet. The proposed model can be finally expressed as a simple explicit function including the main geometrical dimensions and operating parameters. The availability of this model is validated by comparison of the calculated grade efficiency with experimental data and other theoretical separation model.     

Optimization of separation and determination of chloramphenicol in food using aqueous two-phase flotation coupled with HPLC

An aqueous two-phase flotation (ATPF) based on short-chain alcohol and salt was a preconcentration, separation and analysis method of chloramphenicol (CAP) coupled with high-performance liquid chromatography with ultraviolet–visible detector. The influences of salt concentration, flotation time, flow rate and the volume of n-propanol on the flotation efficiency of CAP were discussed. Response surface methodology was employed to optimize the experimental conditions. Under the optimal conditions, this method has been applied to quantitative determination of CAP in food with detection limit of 0.12 ng g^?1 and quantification limit of 0.4 ng g^?1 and the recoveries were in the range of 91.53–103.95 %. This ATPF used low cost of organic solvents, had high concentration coefficient and supplied a moderate and biocompatible environment, which is suitable for biomolecules.     

Surface chemical studies on selective separation of pyrite and galena in the presence of bacterial cells and metabolic products of Paenibacillus polymyxa

Selective separation of pyrite and galena from mixture of the two minerals was achieved through interaction with cells and metabolic products from a culture of Paenibacillus polymyxa. Adsorption of cells and metabolic products onto minerals and electrokinetic studies of minerals after interaction with cells and metabolic products were carried out to examine the resulting surface modification on the mineral surfaces. Flocculation and flotation techniques were successfully applied in the selective separation of minerals after bacterial interaction. The effect of varying conditions for production of extracellular polysaccharides and protein provided an insight into the possible mechanism involved in microbially induced flocculation and flotation of pyrite and galena.     

Adsorption of ionic surfactants in particulate systems: flotation,stability, and interaction forces

The flotation efficiency of silica particles using the ionic surfactants, sodium dodecylbenzenesulfonate (SDbS) and cetyltrimethylammonium bromide (CPB), have been investigated. Results from adsorption, electrophoretic mobility, dispersion stability and direct interaction force measurements are used to develop an understanding of the role of ionic surfactants in particulate flotation. Adsorption and mobility data indicate that SDbS adsorbs at the silica/solution interface, though without improving the flotation efficiency. CPB was found to adsorb on the silica particles as a result of electrostatic interaction; initially to neutralize the surface charge and destabilize the suspension, and at higher surfactant concentrations, to reverse the particle charge and re-stabilize the suspension. Direct force measurements in the presence of CPB confirm that the electrostatic interactions between approaching surfaces are neutralized at low CPB concentrations. Additionally, evidence for a strong adhesive interaction after contact is seen. At higher concentrations, the surfaces begin to recharge, and the adhesive interaction decreases in magnitude. The flotation efficiency was found to correlate well with the measured particle interactions, and to be a function of the particulate electrophoretic mobility.     

Removal of Safranine from Aqueous Solution by Using Adsorptive Bubble Separation Techniques

Safranine, a cationic dye, was removed from synthetic wastewater by ion flotation. Over 98% of safranine was removed from the solution in 10 min. A stoichiometric amount of surfactant (1 mol of surfactant to 1 mol of dye) was found to be most effective for safranine removal. The separation efficiency of safranine decreased with increasing concentration of NaNO3. Safranine was also removed by adsorbing colloid flotation technique using Fe(OH)3 as the coagulant. Sodium lauryl sulfate was used as the collector, and over 97% of safranine was removed in 5 min. The separation efficiency decreased with increasing ionic strength of the solution. The deleterious effect of neutral salt was compensated somewhat with the aid of Al^3 as the activator. Both ion flotation and adsorbing colloid flotation may be applicable in the removal of safranine from wastewater.     

The liquid flow force on a particle in the bubble-particle interaction in flotation

In this paper the problem of calculating the liquid flow force on a particle in interaction with an air bubble with a mobile surface in flotation as a function of the separation distance was solved. The force equation was obtained by first deriving the disturbed flow confined between the surfaces. The model for the force includes the separation distance between the bubble and the particle, the particle size, the bubble's Reynolds number, the bubble rise velocity, and the polar position of the particle on the bubble surface. The proposed equations provide an exact solution to the situation where the particle and the bubble are very close together. The attractive flow force and the surface forces are of similar orders of magnitude. Consequently, the models presented in this paper should provide a better estimate for calculating the forces on particles interacting with air bubbles in mineral flotation and other separation operations involving colloidal interactions.     

Ion and Adsorbing Colloid Flotation of Auramine

Auramine, a cationic dye, was removed from synthetic wastewater by ion flotation of auramine‐sodium lauryl sulfate complex. Over 98% of auramine was removed from the solution in 15 min. A stoichiometric amount of surfactant (1 mol of surfactant to 1 mol of dye) was found to be most effective for auramine removal. The rate of separation and ultimate removal of auramine increased with increasing the rate of air flow and decreased with increasing concentration of NaNO₃. Auramine was also removed by adsorbing colloid flotation technique using ferric hydroxide as the coagulant. Sodium lauryl sulfate was used as the collector, and over 95% of auramine was removed in 10 min. The separation efficiency decreased with increasing ionic strength of the solution. The deleterious effect of neutral salt was compensated somewhat with the aid of aluminum ions as the activator. Both ion flotation and adsorbing colloid flotation are promising approaches for the removal of cationic dye from wastewater.     

氯化钠存在下应用氯化亚锡-罗丹明B-水体系浮选分离钯

研究了氯化钠存在下氯化亚锡-罗丹明B-水体系浮选分离钯的方法及条件，在盐酸介质中，钯（Ⅱ）浮选率为100%，并与常见贱金属分离，对方法在分光光度法中的应用进行了研究，并对浮选模型进行了探讨。     

The application of ultrafiltration for treatment of ships generated oily wastewater

The wastewaters collected from ships were preliminary separated in harbour installation into an oil fraction (slop oil) and the aqueous phase. The oil phase was then separated from slop oil, and the resulting water phase was subjected to the treatment in a coagulation/flotation process. The effluent (oil content 7–13 ppm) from these processes was further purified in biological wastewater treatment plant. A composition of bilge water is variable what affects the efficiency of coagulation/flotation process and the effluents may contain a significant amount of oil residues. The purification of effluents from coagulation/flotation process was performed in this work with ultrafiltration (UF), using FP100 membranes. The turbidity of obtained UF permeate was varied in the range of 0.08–0.26 NTU and the oil content was at a level of 0.9–1.1 ppm. Such purified water can be utilized for rinsing the oil–water separation devices located in the wastewater treatment plant, instead of tap water used so far. The obtained UF retentate contained 30 ppm of oil can be recycled to the coagulation/flotation process. Fouling of UF membranes was observed during the separation process, however, the FP100 membranes were effective cleaned with alkaline cleaning agents P3 Ultrasil 11.     

Zinc Recovery from Wulagen Sulfide Flotation Plant Tail by Applying Ether Amine Organic Collectors

Separating oxidized zinc minerals from flotation tailings is always a challenge. In this study, a flotation tailing from Wulagen zinc mine in China (Zn grade < 1%) was processed using froth flotation with combinations of amines (OPA 10, OPA 1214, OPA 13, DDA) and Na₂S to study the effects of these amines on the zinc recovery as well as their interactions with other reagents, aiming to screen out a proper reagent scheme to improve zinc separation from extremely low-grade zinc flotation tailings. The results show that different amines led to different flotation performance, and the collectors were ranked as OPA 1214, OPA 13, OPA 10 and DDA in a decreasing order based on flotation collectivity and selectivity. An increase in the concentration of each collector increased the zinc recovery but reduced the concentrate zinc grade. Interactions were also observed between different amines and Na₂S and Na₂SiO₃, and OPA 1214 outdid the others in saving the usage of both the Na₂S and Na₂SiO₃. The measured adsorption of collector onto smithsonite was found to correlate well with flotation test results. It was concluded that hydrocarbon chains can be held accountable for the difference in the flotation performance with different amines. The longer the hydrocarbon chain, the stronger the hydrophobic association ability of amine, which is conducive to the selective amine adsorption onto sulfurized smithsonite particles and hence the smithsonite flotation.