| In this paper, a kind of column combined with separation and reaction to produce inorganic potassium crystals was studied. K+ was separated from molasses vinasse by the resin column, then regenerated the resin column, at the same time, inorganic potassium was desorbed into the eluate, which can produce inorganic potassium crystals. Meanwhile, the other molasses vinasse could be used as feed additive after concentrating.1. Molasses vinasse was flocced by polyacrylamide and Ca(OH)2 to remove the suspended matters. Then, some experiments were taken to select the resins among BK001,ZGC108,S-9,001×7 and D001. Under the static condition, ZGC108 was the suitable resin to extract K+ from molasses vinasse, according to the adsorption capacity of K+, rate of desorption, kinetics of adsorption and elution, as well as adsorption isotherm parameters etc.. The influence of stirring speed, temperature, potassium concentration and particle size of resin on K+ extraction process was researched to determine the speed-controlling step, energy of activation and reaction order of ZGC108. Then, the kinetics model of K+ extraction process by ZGC108 was established.2. Single factor experiment was employed to determine the factors effecting the resin penetration exchange capacity of single resin column. Then, the optimal technique was obtained by the L9(34) orthogonal experiments. The results showed that under the technique of columns filling height 14cm (height-diameter ratio 5.38), velocity 1.2mL/min, concentra- -tion of K+ 5g/L, and temperature 25℃, the penetration exchange capacity of the resin ZGC108 was 52.98 mg/mL (wet resins). The analysis of variance indicated that the effects of velocity rate and temperature on the penetration exchange capacity were significant, the order of factors was as followed: velocity﹥temperature﹥concentration of K+﹥height of resin. The experiments were proving it was feasible that 0.6mol/L sulfuric acid eluting K+ from the posterior segment of the eluate recovery 30% (volume fraction) to match the mixed eluate at velocity 3BV/h and temperature 35℃.3. The effect of double-exchange column in parallel or series, flow in sequence or countercurrent on penetration exchange capacity of resin and the total volume of eluant was studied. The greatest penetrable adsorption capability of resin was 56.79 mg/mL wet resin, which the double-exchange column were parallel first, then connect in series. Using this type of resin, 0.4mol/L sulfuric acid eluant was adopted to extract K+ at 3BV/h velocity and temperature 35℃. The results showed that the volume of eluant using in parallel resins accounted for 13% of the total was best to avoid generating crystal in the column, meanwhile, the total volume of eluent reduced to 4.2BV, the average use ratio of H+ is 38.1%, and the elution ratio of K+ is 99.7%.4. The potassium sulfate crystal seeds prepared under the condition of water bath 30℃, stirring speed 250r/min, ultrasound 50W, and Ethanol: Potassium sulfate solution= 1:1 had uniform size, smooth surface, and the average particle chord of crystal was 14.5μm. The crystal seeds were applied to promote the generation of potassium sulfate crystal in the concentrated eluant, which had significant improvement on crystal structure and particle compared with commercially available products. The quality of crystal over 40 held 81.2% of the total, and crystal recovery ratio of K+ was 85.8%. After extracting potassium sulfate crystal, it is feasible to recover the eluant in the industry.
|
PDF Full Text Request