Continuous Precipitate Flotation of CuS/ZnS

Abstract

The precipitate flotation of copper and zinc as sulfides in dilute aqueous solutions (50-250 ppm metal ion concentration) was investigated in the laboratory in continuous flow. The dispersed-air flotation technique was followed, leading to a selective recovery of copper sulfide of the order of 95% in a high acidic pH region (of 1.7) by a laurylamine ethanolic solution as collector and with the addition of cetyl-pyridinium chloride as frother. The precipitate flotation of zinc sulfide was then accomplished with the same method at pH 5.0 as a second separation stage (in the presence of minor amounts of copper).     

红柱石与绢云母、高岭石反浮选分离的研究

对比研究了在捕收剂十二胺和XM-1体系下红柱石与绢云母、高岭石的浮选行为.结果表明:红柱石和绢云母、高岭石在pH=5～6的弱酸性条件下,用XM-1作捕收剂比用十二胺反浮选更具有选择性.采用自制的新型捕收剂XM-1对新疆哈密某红柱石矿进行原浆浮选验证试验,获得了良好的分选指标.     

Removal of Direct Red from Aqueous Solution by Foam Separation Techniques of Ion and Adsorbing Colloid Flotation

Abstract

Experimental investigations on the removal of Direct Red from an aqueous solution were carried out through two foam separation techniques: ion flotation and adsorbing colloid flotation with Fe(III). The residual concentration of Direct Red can be lowered to below 0.5 ppm in 3 minutes by ion flotation and below 0.1 ppm in 2 minutes by adsorbing colloid flotation. The optimum pH for the removal of Direct Red was found to be 4 for ion flotation and 3–5 for adsorbing colloid flotation. The effects of surfactant, foreign ions, and Al(III) addition on the removal of Direct Red are discussed.     

Biosorptive Flotation in Metal Ions Recovery

Abstract

Heavy metals can be removed from dilute aqueous solutions in many ways. Among the innovative ones may be classified a process consisting of biosorption followed by flotation. A metal cation, cadmium, was examined; the metal was abstracted by microorganisms belonging to the Actinomycetes, i.e., Streptomyces clavuligerus and Streptomyces griseus, which have a filamentous morphology, and hence present a flocculent character. Dissolved-air flotation was the technique applied on a laboratory scale without the addition of any flotation surfactant. The parameters investigated in the batch mode were contact time, recycle ratio, solution pH, Cd concentration, biomass addition, and use of a frother (ethanol). Promising results were obtained; in certain cases an almost quantitative cadmium abstraction, followed by higher than 90% biomass recovery, was found.     

Effects of residual concentration of collector CTAC on flotation behavior of illite

ABSTRACT

In present study, illite flotation behavior with Cetyl Trimethyl Ammonium Chloride (CTAC) as the collector has been studied to investigate the effects of its residual concentration on froth stability and flotation. Results showed that, with increasing conditioning time, the residual concentration (frother concentration) and froth height decreased simultaneously, while the adsorbed amount (particle hydrophobicity) increased. Increasing CTAC conditioning time decreased the residual concentration in solutions, resulting in poor froth stability and flotation recovery at high pH; the adsorption rate of CTAC on illite surface was relatively high at higher pH due to strong electrostatic mechanism, making CTAC residual concentration decrease.     

Removal of Molybdate and Arsenate from Aqueous Solutions by Flotation

Abstract

Ion flotation and adsorbing colloid flotation have been studied in this paper for the effective removal of molybdenum(VI) and arsenic(V) from dilute aqueous solutions. These different flotation methods were also compared. Ion flotation using a cationic surfactant (dodecylamine) as collector, as well as adsorbing colloid flotation using ferric hydroxide as coprecipitant (or sorbent) and an anionic surfactant (sodium dodecyl sulfate) as collector were examined. Laboratory-scale experiments were conducted in order to assess the effects of the following parameters on the efficiency of the process: pH value, dosages of chemical reagents, initial concentrations of arsenic and molybdenum, and the presence of foreign anions, such as Cl^- and SO² ₄ ^-. In practical applications, ion flotation or adsorbing colloid flotation may be selected according to the concentration of arsenic, molybdenum, and also the initial [Mo]/[As] molar ratios in solution.     

A new kinetic model for Ni(II) ion flotation based on gene expression programming

ABSTRACT

The Ni(II) ion flotation kinetics with sodium dodecylsulfate as collector was studied with the aim of developing new models to predict the flotation rate constant (k) of Ni(II) ions and water removal during the process of Ni(II) ion flotation. In this regard, the most influential parameters on Ni(II) ion flotation efficiency including the ratio of collector concentration on the Ni(II) ion concentration, impeller speed, activity coefficient, and pH were used to develop predictive models. The results show that the proposed gene expression programming models can be used to predict the flotation rate constant of Ni(II) ions and water removal.     

Ionic and Colloidal Flotation of 144Ce(lll) and 147Pm(lll)

Abstract

Ionic and colloidal flotation of ¹⁴⁴Ce(III) and ¹⁴⁷Pm(III) were studied on a laboratory scale from aqueous solutions with anion-active, cation-active, or non-ionic surface-active substances and the dependence on pH, on the concentration of the separated component, and on the surface-inactive electrolyte shown. In addition to separation in one stage, multistage separation was also used in order to achieve higher efficiency.     

Investigations of Kinetics of Removal of Trivalent Chromium Salts from Aqueous Solutions Using lon and Precipitate Flotation Methods

Abstract

Trivalent chromium salt solutions were flotated using cationic and anionic surfactants. The results indicate that the course of ion and precipitate flotation in the range of parameters investigated can be described by an equation analogous to a first-order rate equation. In the region of precipitate flotation the flotation rate constant reaches a maximum at a definite pH value. Increases in the surfactant concentration result in decreases in the flotation rate. Flotation of chromium at higher surfactant concentrations results in a delay effect which increases with the concentration of the surface-active agent. Increases in the flotation gas flow rate result in increases in the rates of ion and precipitate flotation.     

Studies in the Flotation of Colloidal Particulates: Effects of Aggregation in the Flotation Process

Abstract

An experimental investigation is reported of the effects of several solution parameters on the flotation of colloidal kaolin and montmorillonite using ethylhexadecyldimethylammonium bromide. The parameters examined were the zeta potential of the surfactant-particulate species, the concentration of selected cations, pH, and the ratio of initial surfactant concentration to initial particulate concentration. Two apparatuses were used to assess the affect of aggregation on flotation; one employed bubbles of 1-2 mm average diameter to effect the flotation, while the other used bubbles of about 0.2 mm. In the large bubble system, aggregation adversely affected the flotation of the particulates. For the small bubble (0.2 mm) system, the affect of aggregation on the flotation of particulates was contrary to that in the large bubble (1-2 mm) system. These observations are explained in terms of bubble sizes and their attachment to the particulate species during the flotation process. Studies also showed that several cations and pH variations cause little interference. A general discussion is given relative to the application of the process to large-scale clarification of turbid waters.     

Dissolved-Air Flotation of Metal Ions

Abstract

Metal ions (copper, nickel, zinc, and ferric ions) were separated from dilute aqueous solutions by dissolved-air flotation. The ions were either precipitated as sulfides or floated (as ions) by xanthates. Copper and nickel were selectively separated; promising results were obtained with single, binary, and ternary mixtures. The effect of several parameters (solution pH, addition of chemical reagents at varying concentrations, and the presence of other ions) on the removal of ions was studied. The collectorless flotation of copper ions was also investigated.     

Removal of Trace Levels off Phenols from Aqueous Solution by Foam Flotation

Abstract

Peritachlorophenol (PCP) was removed from water by foam flotation with the cationic surfactant cetyltrimethylammonium bromide (CTAB). With initial PCP concentrations of 20 ppm or less, residual PCP concentrations of less than 0.05 ppm were obtained after 5 min flotation. The CTAB concentration and flotation time are directly related to the amount of PCP removed. PCP removal is most efficient at neutral to basic pH and at low ionic strength. PCP removal is less effective with sodium dodecyl sulfate. As much as 80% of the CTAB can be replaced by dodecylamine without inhibiting PCP removal. Alcohols up to 10% by volume do not affect PCP removal. Other phenols can also be removed equally well by foam flotation if the phenol is in the anionic form during flotation.     

Selective Flotation‐Separation and Inductively Coupled Plasma‐Atomic Emission Spectrometric Determination of Ultra Trace Amounts of Silver Ion Using Bis(2‐mercaptoanil)acetylacetone

Abstract

A rapid, selective and highly sensitive flotation method is developed for separation and enrichment of ultra trace amounts of Ag⁺ ion from water samples. At pH 6.0 and using sodium dodecylsulfate as a foaming agent, Ag⁺ was separated with bis(2‐mercaptoanil)acetylacetone (BMAA) added to 1000 mL of aqueous solution. The proposed procedure of pre‐concentration is applied prior to the determination of silver ion using inductively coupled plasma‐atomic emission spectrometry (ICP‐AES). The influences of pH, concentration of BMAA, applicability of different surfactants and foreign ions on the separation efficiency were investigated. The pre‐concentration factor of the method is 1000 and the detection limit is 0.045 µg mL^?1.     

Removal of Cu(II) from Aqueous Solutions by the Foam Separation Techniques of Precipitate and Adsorbing Colloid Flotation

Abstract

Experimental investigations on the removal of Cu(II) from aqueous solution were carried out through two foam separation techniques: precipitate flotation and adsorbing colloid flotation with Fe(III). The optimum pH for good removal was found to be about 9 for the former and about 7 for the latter. The effects of surfactant (sodium lauryl sulfate), foreign ions (Na⁺, Ca²⁺, NO^? ₃, and SO^2- ₄), and Al(III) addition on the efficiency of Cu(II) removal are discussed.     

Flotation Using Microgas Dispersions for the Removal of Pentachlorophenol from Aqueous Solutions

ABSTRACT

Microgas dispersions called colloidal gas aphrons (CGAs) were generated using cationic, anionic, and nonionic surfactants, and were used in an adsorptive bubble flotation process in a semibatch mode to remove pentachlorophenol (PCP) from the aqueous phase. The aqueous solution was maintained at pH values by using buffers. CGAs generated with Tergitol, which is a nonionic surfactant, were found to be the most efficient for the removal of PCP; the efficiency remained nearly independent of pH. In the case of an anionic surfactant, sodium dodecylbenzene sulfonate (DDBS), the efficiency of removal improved from 15 to 36% with a change in pH from 10.1 to 3.0. For a cationic surfactant, hexadecyltrimethylammonium bromide (HTAB), the removal at pH 10.1 was 81%, which decreased to 68.1% at pH 3.0. The charges on the encapsulating film of CGAs may explain the higher percentage of adsorption of PCP on the CGAs generated using HTAB as compared to CGAs generated using DDBS. For all the surfactants, an increase in concentration improved the removal efficiency. These results were compared with the removal efficiencies using conventional flotation techniques used by other researchers. Solvent sublation appears to be effective in the removal of PCP, but even in the presence of a surfactant it required 300% more air volume per volume of liquid when compared with CGA flotation.     

Flotation Mechanisms of Boron Minerals

Abstract

The development of reagent strategies for the flotation of boron minerals requires an understanding of flotation chemistry of reagent/mineral interactions. The floatability of a typical boron mineral, colemanite, was investigated in a microflotation cell by using anionic and cationic surfactants as collectors and tannic acid as a depressant. The results obtained with zeta potential measurements together with flotation tests reveal that colemanite is floatable with both anionic and cationic surfactants at its natural pH of 9.3. While the floatability of colemanite with anionic surfactants decreases with increasing pH, that with a cationic surfactant exhibits a maximum at pH 10.2, indicating the major role of electrostatic interactions in the system.     

Foam Separation of Mercury(II) and Cadmium(II) from Aqueous Systems

Abstract

Mercury(II) and cadmium(II) were separated from aqueous systems by a number of batch-type precipitate flotation and adsorbing colloid flotation techniques. HgS, CdS, and Cd(OH)₂ were removed by precipitate flotation; Fe(OH)₃, Al(OH)₃, FeS, and CuS were used as adsorbing colloids. Sodium lauryl sulfate and hexadecyltrimethylammonium bromide (HTA) were used as collectors. Dependence of separation efficiency on pH and ionic strength was investigated. Floc foam flotation of both metals with CuS and HTA was found to be quite effective, resulting in residual Hg(II) levels as low as 5 ppb and residual Cd(II) levels as low as 20 ppb. Floc foam flotation of Cd(II) with FeS and HTA yielded residual Cd(II) levels as low as 10 ppb.     

Foam Separation of Lead(ll) and Cad mi urn (II) from Waste Water

Abstract

Foam separation techniques are evaluated to determine if they would be feasible for removing lead(II) and cadmium(II) from highly contaminated waste water. Variables such as pH, ionic strength, collector concentration, and interfering ions were studied to determine their effects on ion flotation. Increased ionic strength, calcium(II), and phosphate interference made ion flotation impractical. Precipitate flotation of lead sulfide and cadmium sulfide left approximately 0.20 ppm lead(II) and 0.08 ppm cadmium(II) in the bulk solution under optimum conditions—somewhat above the levels considered safe to release into the environment. Adsorbing colloid flotation gave excellent results; lead sulfide and cadmium sulfide were adsorbed to ferrous sulfide which was then removed by foaming with hexadecyltrimethylam-monium bromide. Lead(II) levels were reduced from 0.80 to 0.025 ppm in 34 min foaming with 15 ppm iron(III) added. Cadmium(II) levels were reduced from 1.0 to 0.008 ppm in 45 min foaming with 25 ppm iron(III) added.     

Removal of Cadmium from Aqueous Solution Using Adsorptive Bubble Separation Techniques

Abstract

Cadmium ion was removed from aqueous solutions using adsorptive bubble separation techniques. The effect of pH, coagulant and activator concentrations, and ionic strength on separation efficiency was studied. Adsorbing colloid flotation using ferric hydroxide and aluminum hydroxide as the coprecipitant and sodium lauryl sulfate as the collector and frother was found to be very effective provided that the ionic strength of the solution was no greater than 0.01 M. The residual cadmium concentration was less than 0.02 ppm after foaming for 10 min from a solution containing 20 ppm cadmium initially. Effective separation can be achieved from solutions containing 0.1 M NaNO₃ or 0.05 M Na₂SO₄ when zinc ion is used as the activator. The results of foam flotation were compared with the zeta potential of the floc. It was found that the zeta potential of the floc decreases with increasing ionic strength of the solution. The zeta potential of the floc is more positive when activators (aluminum and zinc ions) were added, which presumably gives the floc a stronger affinity for anionic surfactant adsorption, resulting in better separation efficiency. Adsorbing colloid flotation becomes less effective with increasing inert salt concentration of the solution; this effect can be compensated for to quite a large extent with the aid of activators, and the applicability of foam separation techniques for heavy metal removal from wastewater is thus greatly extended     

Removal of Organophosphorus Pesticides from Aqueous Solution by Using Adsorptive Bubble Separation Techniques

Abstract

Two organophosphorus pesticides, ddvp (phosphoric acid 2,2-dichlorovinyl dimethyl ester) and phorate (phosphorodithioic acid o,o-diethyl s-[(ethylthio)methyl] ester) were removed from aqueous solution by three adsorptive bubble separation techniques: air stripping, solvent sublation, and adsorbing colloid flotation. The effects of pH, flow rate, surfactant, ethanol, ionic strength, and coprecipitant concentration on the efficiency of pesticide removal were studied. Over 97% of phorate was removed in 30 min by solvent sublation, and 90% of phorate was removed in 10 min by adsorbing colloid flotation with Fe(OH)₃, floc. The separations of ddvp by these techniques were not effective.