Sulphur removal of iron ore tailings by flotation

Iron ore tailings have become one kind of the most hazardous solid waste. Beneficiation of iron ore tailings is a significant issue in the world steel industries, from the point of view of both pollution control and secondary resources. This investigation addressed the processing of tailings with high sulphur content from an iron ore concentrator to produce pellet feed fines and to prevent acid mine drainage. This study was the lab-scale testing of an integrated method consisting of froth flotation combined with gravity and magnetic separation. Reverse flotation located at the end of the primary treatment circuit (high- and low-intensity magnetic separation) will lower a large amount of the sulphur from magnetic separator concentrate. The effects of various operating parameters such as concentrations of collector, frother, depressant and activator, pH, solid-in-pulp concentration have been studied on the sulphur removal using reverse flotation. According to the data presented in this study, the maximum recovery of total sulphur was obtained when the operational parameters were set to the PAX dosage160?gr/t, MIBC dosage 140?gr/t, CuSo₄ 100?gr/t, air flow rate 10?l/min, pH 8.5, and pulp density 30%. With these optimum parameters, final concentrate with the grade of 63.7% Fe and 0.085% S was obtained. The results of this study indicated that, with this method, a great amount of iron concentrate is produced and, simultaneously, the sulphidic fraction is separated that can later be managed more easily owing to the reduced volume.     

Solvent extraction of Mo(V) and Mo(VI) from hydrochloric acid into Aliquat 336 chloroform solution

Solvent extraction of macro amounts of Mo(V) and Mo(VI) from HCl using Aliquat 336 in chloroform was performed for the electrochemistry of Sg. The extraction reaction attained equilibrium with a shaking time of 10 s in higher than 8 M HCl. The D values of Mo(V) obtained by the electrochemical reduction of Mo(VI) were in good agreement with those obtained by the extraction of MoCl₅, and the D values of Mo(V) were higher than those of Mo(VI). These results suggested that the reduction behavior of Sg might be studied by electrochemical reduction combined with the present solvent extraction.     

Solvent extraction of some metals from aqueous solutions

The results for the extractions of divalent (manganese, cobalt, zinc and cadmium) and trivalent (gallium and indium) metals and hexavalent uranium from aqueous solutions by various extractants such as organophosphorus compounds (tributyl phosphate, trioctylphosphine oxide, di-(2-ethylhexyl)phosphoric acid and 2-ethylhexyl 2-ethylhexylphosphonic acid), sulfur-containing compound (dihexyl sulfoxide), high-molecular weight amines (trioctylamine and trioctylmethylammonium chloride) and 7-alkylated hydroxyquinoline (7-(5,5,7,7-tetramethyl-1-octen-3-yl)-8-hydroxyquinoline are discussed in the viewpoint of separation chemistry.     

Actinide and lanthanide extraction from nitric acid solutions by flotation

Flotation of thorium, plutonium (IV), uranium(VI) and gadolinium from aqueous nitric acid solutions (HNO₃ concentration from 0.01 to 5.0M) was investigated using lauryl phosphoric acid (LPA) as a SAS-collector. It is established that the extent of removal of the metal ions increases with the amount of LPA introduced, regardless of the solution acidity. At a fixed mole LPA to metal ratio the extent of uranium(VI) and gadolinium removal is reduced with increasing acidity, while in case of plutonium(IV) and thorium this parameter remains constant. It is shown that in principle 100% extraction of plutonium(IV) and thorium by flotation is possible regardless of the acidity of aqueous solutions. Ca(NO₃)₂ added to the system in the amount of 0.5M does not significantly affect the flotation extraction of thorium.     

Solvent extraction of reduced technetium from mineral acid solutions

The extraction of reduced^99mTc with 5,7-dichloroxine, tributyl phosphate (TBP) and 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (PMBP) from HCl−LiCl mixtures has been studied. A mechanism of extraction is proposed and the stability of the chlorocomplexes of technetium (V) in a hydrochloric and—lithium chlorid—perchloric acid mixture has been established using extraction data of^99mTc and spectrophotometric measurements with⁹⁹Tc.     

Solvent extraction of uranium from lean grade acidic sulfate leach liquor with alamine 336 reagent

This paper describes the solvent extraction studies carried out on an acidic low assay uranium bearing leach liquor generated during sulfuric acid leaching of a refractory uranium ore using alamine 336?Cisodecenol?Ckerosene reagent combine. The leach liquor has a U₃O₈ content of about 270?mg/L, free acidity 2.4?N H₂SO₄ and total dissolved solids concentration of 260?g/L. Process parameteric variation studies indicated strong influence of free acidity of the leach liquor, alamine 336 concentration and aqueous to organic phase ratio on the extraction efficiency of uranium. An extraction efficiency of about 95% was achieved when the free acidity of leach liquor was 1?N H₂SO₄ or lower, using 2% (v/v) alamine 336 at ambient temperature with an aqueous to organic phase ratio of 1:1. The loading capacity under these conditions was 1.2?g/L of U₃O₈. About 98% of the uranium values could be stripped from the loaded organic using 1?N NaCl in 0.2?N H₂SO₄. The solvent extraction studies aided in developing a suitable process flowsheet for treating refractory uranium ores which need high acidity during leaching and relatively lower acidity for purification by solvent extraction.     

Solvent extraction of tetraphenylarsonium ion pairs from mixed aqueous-organic solutions

Ion pairs of tetraphenylarsonium cation with iodide, bromide, and perrhenate anions were extracted into chloroform from mixed aqueous-organic solutions. The extraction of these ion pairs was found to increase in the presence of polar aprotic solvents in the mixed aqueous-organic phase. This effect was correlated with literature data on free energy of transfer of the Ph₄As⁺ ion, and ascribed to ion pair/solvent and/or ion/solvent interactions in the organic phase.     

Solvent extraction of europium from aqueous-organic solutions by solvating extractants

The partition of Eu(III) between benzene containing solvating extractants (TBP, TOPO, dioctylsulfoxide) and aqueous nitrate, perchlorate and thiocyanate solutions containing various organic solvents miscible with water (alcohols, acetone, acetonitrile, ethylene glycol, dimethyl sulfoxide and dimethylformamide) was investigated. Depending on the specific extraction system, the presence of organic solvents in the mixed phase showed various effects on the distribution ratio of Eu(III). These were discussed in terms of solute-solvent interactions. The results in the systems containing dimethylformamide and dimethyl sulfoxide indicated complexation of Eu(III) with these solvents in the polar phase.     

Solvent extraction of uranium(VI) and separation of vanadium(V) from sulfate solutions using Alamine 336

The present scientific study on uranium(VI) solvent extraction and vanadium(V) separation from sulfate solutions using Alamine 336 as an extractant diluted in kerosene was established. The preliminary experiments indicating the uranium extraction process will follow the solvation as well as ion-exchange mechanisms. In the present acid region (0.1–1.0 mol dm⁻³ H₂SO₄) it showing the ion-exchange type mechanism. Time (1–120 min) and temperature (25–55 °C) not influencing the present extraction system. Other experimental parameters like loading capacity of Alamine 336, stripping of uranium from loaded organic phase, recycling of Alamine 336 and separation of uranium(VI)/vanadium(V) was studied.     

Solvent extraction of alkali metal ion-pairs into nitrobenzene from aqueous-organic solutions

Solvent extraction of¹³⁷Cs,⁸⁶Rb and⁴²K by dipicrylaminate and tetraphenyl borate into nitrobenzene was studied from solutions containing various solvents miscible with water. In all cases the distribution ratios of alkali metals were lower in mixed solutions than in water. In discussing the results, water structure, ion-association, solubility of Cs(I) ionpairs, ionic strength, and organic phase effects were taken into account. Part III in the series Solvent Extraction of Ion-pairs. Part II. Ref.⁸     

A rapid titrimetric determination of iron in copper concentrates and copper-bearing leach solutions

A titrimetric method for the determination of iron(III) in the presence of copper is presented. This method involves the reduction of iron(III) with titanous sulphate followed by titration with dichromate. It has been successfully used for the determination of iron in both leach solutions and copper concentrates with a relative error of 1%.     

Vanadium(V) extraction from sulfuric acid solutions

We studied vanadium(V) extraction by di-2-ethylhexylphosphoric acid (DEHPA) from 1.0–12.0 M sulfuric acid. Optimal extraction parameters were determined. IR, ⁵¹V NMR, and electronic spectroscopy was used to determine the stoichiometry of the extracted complex and the reaction equation for vanadium(V) extraction by DEHPA. The equilibrium constant of vanadium(V) extraction by DEHPA was determined.     

Solvent extraction of zirconium from hydrochloric acid solutions by sulphoxides and their mixtures

The solvent extraction of zirconium from HCl solutions by dipentyl sulphoxide (DPSO), dioctyl sulphoxide (DOSO), tributyl phosphate (TBP), and their mixtures in various solvents has been studied. At a given H⁺ strength, the extraction coefficient η of the metal increases with an increase in Cl⁻ activity whereas it is almost independent of H⁺ at constant Cl⁻. Under otherwise identical conditions, η increases with an increase in the extractant concentration but is virtually independent of the metal ion concentration over a wide range. The species extracted are ZrCl₄·DPSO, ZrCl₄·DOSO, and ZrCl₄·2TBP. In the case of mixtures, the slope of the log η−log M extractant plot for one component decreases with an increase in the concentration of the second component, the lines crossing at a common point. Extraction is favoured by solvents of low dielectric constant. It is possible to separate zirconium from thorium and uranium by solvent extraction with sulphoxides.     

Solvent extraction of ionic solutes in aqueous solutions

Extraction of ionic solutes in aqueous solutions into various organic solvents is reviewed by showing several examples. The extraction of strong acids into polar organic solvents and nonpolar solvents containing hydrogen-bonding extractants is described as the first example and the extraction of simple metal salts into strongly dielectric or solvating polarsolvents and nonpolar solvents containing solvating extractants is then reported. Finally, the solvent extraction of anionic metal complexes with bulky cations into nonpolar solvents as ion-paris is described and the statistical method for such extraction equilibria is considered.     

Solvent extraction of Co/III/ by benzoylacetone from acetate solutions

The extraction of Co/III/ by benzoylacetone solutions has been carried out from acetateacetic acid solutions. The effect of different parameters affecting the distribution coefficient of Co/III/ have been determined. Lg D for Co was found to be a third order dependent on extractant concentration and a negative first order with respect to [H⁺]. From the thermodynamic parameters and the data of distribution ratios, the extraction mechanism has been suggested. Addition of some electron donor compounds shows no possibility for the increase of coordination number.     

Solvent extraction of Cobalt/II/ from thiocyanate solutions by sulphoxides

The extraction of cobalt/II/ from ammonium thiocyanate solutions by di-n-pentyl sulphoxide /DPSO/, di-n-octyl sulphoxide /DOSO/ and their mixtures in carbon tetrachloride has been studied. The species extracted were found to be Co/SCN/₂. 4S /where S=DOSO or DOSO/. Synergic effects have been observed which are ascribed to the formation of mixed ligand metal complexes. The influence of the metal concentration, temperature and the diluent on the extraction of cobalt/II/has been investigated.