Study On The Extraction Of Boroc From The High Magnesium And Low Boron Strong Acid Brine

Taking the brine as raw material, the extraction of boric acid from the high magnesium and low boron strong acid brine was studied. From the bench scale experiment, the optimal extractant and extraction condition were obtained. The feasibility of the extraction process was validated by pilot scale experiment, and the reflux model was established based on the pilot scale experimental data.The extraction of boric acid by the mixed solvents of iso-octyl alcohol and aviation kerosene was studied. The result shows that the optimal ratio of iso-octyl alcohol and aviation kerosene is 1:1, the optimal Mg2+ concentration is more than 85g·l-1. The liquid-liquid equilibrium data of the system were measured, the optimum conditions of extraction were obtained that phase ratio (O/A) was 0.5, extraction series were 8. Under the optimum conditions, boron acid concentration of extraction raffinate was lower than 30mg·l-1. The extractant was reextracted by water. When the organic/water ratio was 1:0.7 and the reextraction series were 6, the boron acid of the organic phase was reextracted cleanlily.In order to the further study on the mechanism of boric acid extraction, the compositions of complex were determined by slope method, the structures of complex were validated by IR. The mechanism of boron acid extraction was determined that boron acid and iso-octyl alcohol synthesized neutral ester. The main reaction generate dibasic ester, simultaneity go with monobasic ester. The result shows that the dibasic ester/monobasic ester molar ratio is 7:3. For validated the feasibility of the extraction process, the pilot scale experiment was carried with sieve-plate column(tower diameter is 800mm, tower height is 17430mm, plate number is 40, plate spacing is 300mm). The experimental data are satisfactory. When the flow of brine was 14m3·h-1, the boric acid concentration of extraction raffinate was 0.563g·l-1.A reflux model based on the countercurrent extraction was established. The extraction raffinate concentration from model was in good agreement with the experimental data, the average relative error was 10.2%. The extraction process was optimized using the model, the best structure parameters were obtained that plate spacing was 300mm, plate number was 52.