A significant development in the theory of countercurrent extraction will be presented in this article. New expressions of the term in countercurrent extraction process analysis, “Adjacent Stage Impurity Ratio” (ASI...A significant development in the theory of countercurrent extraction will be presented in this article. New expressions of the term in countercurrent extraction process analysis, “Adjacent Stage Impurity Ratio” (ASIR), are deduced. Furthermore, based on the term together with mass balance and extraction equilibrium, the conditions where a given countercurrent extraction separation operation can have minimum amounts of both extracting solvent and scrubbing agent solution can be estimated, and the equations of the two minimum amounts can be deduced. It was found that the equations for a two-component separation using a single aqueous or organic feed are exactly the same as they appeared in the theory initially established in 1970s. Unlike its earlier version, the present derivation does not involve feed-stage-composition hypothesis, and also has the advantage of dealing with a double-feed system where both aqueous and organic feeds are simultaneously employed whereas the earlier theory can only analyze a separation using a single aqueous or organic feed.展开更多
For the purpose of developing an alkali leaching solvent extraction directly from alkali solution process, the extraction of niobium from alkali solution by long chain alkyl quaternary ammonium salt (methyltrioctylamm...For the purpose of developing an alkali leaching solvent extraction directly from alkali solution process, the extraction of niobium from alkali solution by long chain alkyl quaternary ammonium salt (methyltrioctylammonium chloride R 4NCl) in toluene was investigated. The experiments were carried out under conditions of 25 ℃, Nb(Ⅴ) concentration 0.01 mol/L, pH 10.7 13.8, R 4NCl concentration 0.02 0.14 mol/L. It has been found that the distribution ratio of niobium increases with increasing R 4NCl concentration and with decreasing KCl concentration, but it shows maximum value at pH value of about 12 and decreases below or above this pH value. Distribution ratio of niobium goes up to over 1 000 in appropriate conditions, and so it has been proved that R 4NCl is an effective extractant for extraction of niobium from alkali solution.展开更多
文摘A significant development in the theory of countercurrent extraction will be presented in this article. New expressions of the term in countercurrent extraction process analysis, “Adjacent Stage Impurity Ratio” (ASIR), are deduced. Furthermore, based on the term together with mass balance and extraction equilibrium, the conditions where a given countercurrent extraction separation operation can have minimum amounts of both extracting solvent and scrubbing agent solution can be estimated, and the equations of the two minimum amounts can be deduced. It was found that the equations for a two-component separation using a single aqueous or organic feed are exactly the same as they appeared in the theory initially established in 1970s. Unlike its earlier version, the present derivation does not involve feed-stage-composition hypothesis, and also has the advantage of dealing with a double-feed system where both aqueous and organic feeds are simultaneously employed whereas the earlier theory can only analyze a separation using a single aqueous or organic feed.
文摘For the purpose of developing an alkali leaching solvent extraction directly from alkali solution process, the extraction of niobium from alkali solution by long chain alkyl quaternary ammonium salt (methyltrioctylammonium chloride R 4NCl) in toluene was investigated. The experiments were carried out under conditions of 25 ℃, Nb(Ⅴ) concentration 0.01 mol/L, pH 10.7 13.8, R 4NCl concentration 0.02 0.14 mol/L. It has been found that the distribution ratio of niobium increases with increasing R 4NCl concentration and with decreasing KCl concentration, but it shows maximum value at pH value of about 12 and decreases below or above this pH value. Distribution ratio of niobium goes up to over 1 000 in appropriate conditions, and so it has been proved that R 4NCl is an effective extractant for extraction of niobium from alkali solution.
