| In order to realizing the purification of vanadium, the experiments of separating of silicon and chromium from vanadium leaching solution were carried out by methods of precipitation and precipitation combined with ion exchange respectively. The enhanced separation of chromium from vanadium leaching solution were studied in detail, the experiment results provided theoretical base of available technologies and routes for separating chromium and vanadium, which is likely to supply significant references for the industrial application of vanadium purification.The methods of efficient separation of silicon from vanadium leaching solution were studied in this paper, the influence factors such as the precipitant type, dosage of precipitant, pH of leaching solution, reaction time, reaction temperature and standing time on effects of separation of silicon and vanadium loss were investigated in detailed. The results showed that under the weak basic condition, adding aluminum salt has a good effect on the separation of silicon process with the silicon separation rate approximately 99.12 % and vanadium loss 1.22 %, which indicates the methods we adopted are simple and easy for operation that have good effect on separating silicon from vanadium.The separation of chromium from the vanadium solution that had been separated silicon by precipitation. The optimum precipitant reagent was selected from several chemical reagents, and influence factors such as dosage of precipitant reagent, reaction time, temperature and standing time on chromium separation rate and vanadium loss rate. The results showed that the chromium separation rate reached 98.55 %. And the purity of V2O5 powder has reached 98.91 % by precipitation and calcination, which means it has achieved the Metallurgical Grade 98 Standard of V2O5(YB/T 5304-2011).The efficiency of separating chromium and vanadium for vanadium leaching solution were explored. Through the comparison of the selective adsorption, adsorption capacity and adsorption rates of five types resin, we found that the SQ-20 A resin has strong adsorption capacity for vanadium while has weak adsorption capacity for chromium, which could realize the objective of separating chromium and vanadium. Meanwhile the adsorption desorption performances for vanadium and chromium by the SQ-20 A resin, as well as their adsorption kinetics and thermodynamics were also investigated.The effecting factors such as pH value, contact time, temperature and initial concentration of vanadium on separating chromium and vanadium by anion resin were investigated through a series of static experiments. Meanwhile, the effecting factors such as desorbing agent, concentration of the eluent and temperature on desorption of vanadium and chromium were also investigated. The results showed that the maximum separation factor have reached 251.23 on the conditions of pH=9.0 and T=298 K, which indicates the SQ-20 A resin have good selective adsorption capacity for vanadium that could meet the demands of separating chromium and vanadium. Moreover, the vanadium ions could be completely desorbed from the SQ-20 A resin by 1M NaOH solution at 298 K.The dynamic adsorption experiments were carried out by using the SQ-20 A resin as ion exchanger, the effect factors of temperature and flow speed on the adsorption and desorption performances for vanadium and chromium from vanadium leaching solution were investigated. The results showed that the suitable conditions for dynamic adsorption of vanadium are flow rate 1 BV·h-1 and T=288K~308K. The concentration of vanadium in the elution could reached 46.05 g·L-1, while the concentration of chromium was 0.0050 g·L-1 by using 1M NaOH as the eluent and controlling the flow rate in 3 BV·h-1 and T=298 K, which realized the deeply separation of vanadium and chromium.The Langmuir and Freundlich models were used to fit the vanadium adsorption isotherm data on the SQ-20 A resin for investigating the adsorption thermodynamics. The results showed the isotherm equilibrium process could be well described by both the Langmuir and Frendlich models, the correlation coefficients were 0.9990 and 0.9888 respectively. The adsorption free energy(ΔGθ<0) and the enthalpy change(ΔHθ >0) revealed that the spontaneous endothermic nature of vanadium adsorption on the SQ-20 A resin. Meanwhile, the investigation of adsorption kinetics showed that the vanadium adsorption kinetics process on the SQ-20 A resin conformed the pseudo-second-order model(R2=0.9990) and the adsorption was controlled by pellet diffusion.The results show that the purity of V2O5 powder has reached 99.90 % by precipitating vanadium and calcining the ammonium metavanadate, which is superior to the GR grade of chemical reagent V2O5(HG/T 3485-2003). It has attained requirements of the high purity vanadium. |
PDF Full Text Request