The mechanisms of aid-leaching reagent calcium fluoride in the extracting vanadium processes were researched by comparing the blank extraction with the extraction with calcium fluoride as aid-leaching reagent. The lea...The mechanisms of aid-leaching reagent calcium fluoride in the extracting vanadium processes were researched by comparing the blank extraction with the extraction with calcium fluoride as aid-leaching reagent. The leaching experiments were carried out under the conditions of 95 ~C, 6 h, 1.5 ml.g-1, 15 vol % H2SO4, and 5 % calcium fluoride （mass ratio of CaF2 to stone coal）. The concentrations of hydrogen ion were adjusted from initial 1.82 and 4.79 mol.L-1 to the pH of 1.80 4- 0.05 by 200 g.L-1 lime milk, respectively. The solvent extraction experiments were carded out under the organic phase using 15 vol% D2EHPA, 5 vol% TBP, and 80 vol% sulfonated kerosene and O/A phase ratio of 1/4. The leaching rate of vanadium and six-stage countercurrent solvent extraction rate of vanadium can be remarkably improved from 66.71 to 92.97 % and 81.15 to 98.81%, respectively, when calcium fluoride was added as aid-leaching reagent. In the leaching process, fluorine can enhance the breakage of the structure of vanadium-bearing minerals. Meanwhile, fluoride ion can combine with iron ion to generate acid-insoluble iron fluoride hydrate （Fe2Fs.7H20） and consume all ferric ions and a portion of ferrous ions. In adjusting pH value process, the massive impurities are decreased to form KA1SO4 and FeA1Fs. In solvent extraction process, fluorine can prevent the formation of ferric hydroxide colloids and eliminate the formed unstable ferric hydroxide colloids and the silicon-containing colloids to promote the sufficient contact between the aqueous phase and the organic phase and the sufficient reaction.展开更多
Na2SiO3 and Na2SeO3 were chosen as stable reagents of alkaline thiourea solution substituting Na2SO3, according to the structure-property relationship between the stability of alkaline thiourea and the structure of th...Na2SiO3 and Na2SeO3 were chosen as stable reagents of alkaline thiourea solution substituting Na2SO3, according to the structure-property relationship between the stability of alkaline thiourea and the structure of thiourea and sulfite ion, and the effect of the stable reagents on stability of alkaline thiourea was investigated. The results show that contrary to Na2SeO3, Na2SO3 and Na2SiO3 affect the stability of alkaline thiourea solution remarkably. The stable effect of Na2SiO3 on alkaline thiourea is obviously better than that of Na2SO3. The stable reagents Na2SO3 and Na2SiO3 decrease the decomposition rate of alkaline thiourea solution greatly, and the decomposition rate of alkaline thiourea reduces from （72.5%） to （33.8%） with addition of (0.3 mol·L-1) Na2SiO3. Dissolution currents of gold in the alkaline thiourea solution containing Na2SO3 and Na2SiO3 are （2.0） (mA·cm-2) and （3.5） (mA·cm-2) at the potential of 0.42 V, respectively, and Na2SO3 is consumed excessively due to the oxidation reaction of Na2SO3 occurring in the studied potential range. Na2SiO3 is an efficient stable reagent of alkaline thiourea solution, and gold dissolution is accelerated much more obviously by Na2SiO3 than by Na2SO3.展开更多
基金financially supported by the Key Science and Technology Support Program (No. 2011BAB05B01) from the Ministry of ScienceTechnology of China and the Special Science and Technology Program (No. 201009013) from the Ministry of Environmental Protection of China
文摘The mechanisms of aid-leaching reagent calcium fluoride in the extracting vanadium processes were researched by comparing the blank extraction with the extraction with calcium fluoride as aid-leaching reagent. The leaching experiments were carried out under the conditions of 95 ~C, 6 h, 1.5 ml.g-1, 15 vol % H2SO4, and 5 % calcium fluoride （mass ratio of CaF2 to stone coal）. The concentrations of hydrogen ion were adjusted from initial 1.82 and 4.79 mol.L-1 to the pH of 1.80 4- 0.05 by 200 g.L-1 lime milk, respectively. The solvent extraction experiments were carded out under the organic phase using 15 vol% D2EHPA, 5 vol% TBP, and 80 vol% sulfonated kerosene and O/A phase ratio of 1/4. The leaching rate of vanadium and six-stage countercurrent solvent extraction rate of vanadium can be remarkably improved from 66.71 to 92.97 % and 81.15 to 98.81%, respectively, when calcium fluoride was added as aid-leaching reagent. In the leaching process, fluorine can enhance the breakage of the structure of vanadium-bearing minerals. Meanwhile, fluoride ion can combine with iron ion to generate acid-insoluble iron fluoride hydrate （Fe2Fs.7H20） and consume all ferric ions and a portion of ferrous ions. In adjusting pH value process, the massive impurities are decreased to form KA1SO4 and FeA1Fs. In solvent extraction process, fluorine can prevent the formation of ferric hydroxide colloids and eliminate the formed unstable ferric hydroxide colloids and the silicon-containing colloids to promote the sufficient contact between the aqueous phase and the organic phase and the sufficient reaction.
文摘Na2SiO3 and Na2SeO3 were chosen as stable reagents of alkaline thiourea solution substituting Na2SO3, according to the structure-property relationship between the stability of alkaline thiourea and the structure of thiourea and sulfite ion, and the effect of the stable reagents on stability of alkaline thiourea was investigated. The results show that contrary to Na2SeO3, Na2SO3 and Na2SiO3 affect the stability of alkaline thiourea solution remarkably. The stable effect of Na2SiO3 on alkaline thiourea is obviously better than that of Na2SO3. The stable reagents Na2SO3 and Na2SiO3 decrease the decomposition rate of alkaline thiourea solution greatly, and the decomposition rate of alkaline thiourea reduces from （72.5%） to （33.8%） with addition of (0.3 mol·L-1) Na2SiO3. Dissolution currents of gold in the alkaline thiourea solution containing Na2SO3 and Na2SiO3 are （2.0） (mA·cm-2) and （3.5） (mA·cm-2) at the potential of 0.42 V, respectively, and Na2SO3 is consumed excessively due to the oxidation reaction of Na2SO3 occurring in the studied potential range. Na2SiO3 is an efficient stable reagent of alkaline thiourea solution, and gold dissolution is accelerated much more obviously by Na2SiO3 than by Na2SO3.
