Comparative study on simultaneous removal of calcium and sulfate ions from flotation recycling water by aluminum hydroxide

Due to the environmental policies and economic reasons,the water used in some flotation operations of complex sulfide ores is recirculated,causing the ion concentration of some species to increase over time,affecting the flotation of the minerals of interest.In this work,an experimental and thermodynamic analysis of the synthetic solutions was presented with a high content of calcium and sulfate ions.The study focused on evaluating the use of two aluminum compounds for the precipitation of Ca^(2+)and SO_(4)^(2−)in the form of ettringite.The amorphous aluminum hydroxide was found to be more efficient than the crystalline one,giving rise to 83%calcium and 91%sulfate removal.The XRD analysis of the solids showed the main reaction product of ettringite,accompanied by small amounts of calcite,due to the absorption of atmospheric carbon dioxide.The final solution after the chemical treatment showed residual calcium and sulfate concentrations below 200 mg/L.Finally,the kinetics of calcium removal appeared to correspond to a second order reaction with respect to calcium concentration,with an apparent activation energy of 53.48 kJ/mol,which may suggest that the ettringite precipitation process is governed by the chemical reaction.

Thermodynamic and experimental studies on removal of calcium and sulfate ions from recycling water of complex sulfide flotation operations

A chemical method for removing calcium sulfate saturated solutions(0.016 mol/L CaSO_(4))using barium chloride(BaCl_(2)∙2H_(2)O)and sodium phosphate(Na_(3)PO_(4))was experimentally studied.The main interest is to remove these ions from the solution through the precipitation of two solid species:sulfate(SO_(4)^(2−))as barite(BaSO4),and calcium(Ca^(2+))as hydroxyapatite(Ca_(5)(PO_(4))_(3)OH).Additionally,a solid/liquid separation method(i.e.,flotation)was explored,using oleic acid and dodecylamine as collectors.The results show that,the chemical treatment of saturated solutions at 60℃,pH 11.5 and using 3.9 g/L BaCl_(2)·2H_(2)O and 1.6 g/L Na_(3)PO_(4),promotes the precipitation of barium sulfate and calcium-deficient hydroxyapatite(Ca_(10−x)(HPO_(4))_(x)(PO_(4))_(6−x)(OH)_(2−x)),with residual concentrations of calcium and sulfate below 0.10 and 5 mg/L,respectively.The residual calcium concentration increases to 28 mg/L when using the same amount of reactants,at temperature and pH values below those quoted.The highest flotation recovery of hydroxyapatite with oleic acid at pH 9.5 was about 80%,while that of barite floated with dodecylamine at pH 6.5 was about 90%.

Effect of Temperature and the Organic Phase Content on the Stripping of Mn(II) from a D2EPHA-KEROSENE Pseudo-Emulsion Using a Sulfuric Acid Aqueous Solution

There are few studies oriented to analyze the interaction between the variables of the stripping process of actual leaching solutions. The aim of this work was to study the effect of temperature and the percent of organic phase in the stripping pseudo-emulsion (D2EPHA and kerosene) on the manganese stripping process. Other studied variables were the acid concentration (H2SO4) in the aqueous phase, the percent of the organic phase in the pseudo-emulsion and the number of stripping stages. This information may be of interest to countries with radical temperature variations. It was discovered that in the range of 10?C to 50?C, temperature improves the depletion of manganese from the D2EPHA. Additionally, the percent of the organic phase should be less than 90% by volume of the pseudo-emulsion to favour the manganese exchange. Moreover, the H2SO4 concentration in the aqueous phase should be less than 1 M to avoid chemical instability of the organic phase.