Study On Extracting Mo From Ni-Mo Ore Leaching Solution By Ion Exchange

Accroding to the characteristics of Ni-Mo ore leaching solution, a new process was proposed, namely, the use of D301 resin in a tank with blender adsorbs molybdenum blue solution, which was obtained by acidizing the leaching solution, and then desorbs the loaded resins with ammonia in the same tank. The behaviors both adsorption and desorption of D301 resin to molybdenum blue were investigated. Furthermore, the flowsheet from leaching solution to ammonium tetramolybdate was also developed.The main research results in this study are as follows:1) By compared the adsorbing effects of three resins (D201, D301 and D363) on molybdenum blue and their intrinsic performance, D301 resin was chosen as a further research candidate.2) The adsorption studies indicate that D301 shows very good adsorbing effects under the following experiental conditions:temperature 60℃, the pH value in solution 3.5-5.0, the resin consumption Z (Z=resin mass (g)/Mo mass (g) in solution) 1.8-3.1, respectively. The stirring rate has little effect on the adsorption capacity on condition that the resin was fully mixed up. In order to gain a higher adsorption capacity and lower Mo concentration in sulution after the process of adsorption, countercurrent adsorption process was selected to extract Mo. The five-countercurrent adsorption experimental results show that when the initial Mo concentration is 37.57 g/L, the total Mo adsorption ratio is over 99%, the Mo concentration in sulution after adsorption is dropped down 0.1 g/L and the adsorption capacity of D301 resin is more than 450 mg/g(dry) before being desorbed.3) The distribution of the free-state Mo in the leaching solution has been studied.The results demonstrate that the acidized leaching solution contains iopoly-molybdenum blues and hteropoly-molybdenum blues. When the pH value in solution is 4.0, iopoly-molybdenum blue can be obtained by reducing those polyions with similar structures including HMo7O245-, H2Mo7O244-,Mo7O246-, HMo8O287-, H3Mo8O285- and Mo8O265- with H2S, S2O32- or HSO3-. However, hteropoly-molybdenum blue obtained through the reduction of PMo12O403-, AsMo120403- and SiMo,20402- by H2S, S2O32- or HSO3- to lose 2e,4e or 6e. The thermodynamic study of D301 adsorption demonstrates that its adsorption behavior to Mo well obeys the Freundlich isotherm and n value lies between 2 and 10. It means that Mo is easy to be adsorbed by D301 resin. And the adsorption process is spontaneous and endothermic, and the system disorder increases in the duration. Meanwhile, kinetic studies indicate that the Mo adsorption follows the intraparticle diffusion model. The calculated activation energy Ea is 12.48 KJ/mol and the reaction order is 0.919. The total kinetic equation is determined as,4) The desorption study indicates that ammonia can elute loaded resin D301, when the ammonia concentration is 4.65 mol/L, the ammonia excess coefficient is 1.4～1.5, and eluted sustains 2h with stiring, the loaded resin D301 shows good desorption behavior. The eluted ratio can reach up 80% after one time desorption and the concentration of Mo in eluted solution is more than 90 g/L5) Based on the above exploration, the flowchart is determined. Experiments from this flowchart show that the removal ratio of impurity As is more than 99%, while V and W are 92.6% and 62%, respectively. The sinker ratio of ammonium tetramolybdate can reach 95.8%, and the end product ammonium tetramolybdate can conform to the standard of MSA-2.