Study On Recovery Of Manganese,Cobalt And Nickel From Purified Sulfide Slag And Its Kinetic Mechanism

In the production process of electrolytic manganese dioxide,vulcanizing agents such as BaS are often used to sulfide and remove heavy metals such as cobalt and nickel in the leaching solution,and the purified sulfide slag obtained contains a large amount of valuable metals such as manganese,cobalt,and nickel.Most of these purified sulfide slag are buried in the slag yard selected by the company,which not only causes waste of valuable metals,but also seriously pollutes the environment.In order to recover the manganese,cobalt,and nickel metals in the purified sulfide slag,this paper uses the purified sulfide slag as raw material,and proposes the pyrolusite synergistic oxidative leaching,P204 extraction of manganese,and P507-Cyanex301 synergistic extraction system to extract cobalt.Manganese,cobalt,and nickel metals,and simultaneously studied the kinetics of cooperative oxidation leaching and the kinetics of co-extracting cobalt with P507-Cyanex301.The main research results are as follows:(1)The contents of manganese,cobalt,and nickel in the purified sulfide slag are 11.71%,1.21%and 0.97%respectively.Under the conditions of coordinated oxidation leaching that the slag ratio is 1:12.5,the initial acid concentration is 90g/L,the liquid-solid ratio is 7:1,the temperature is 363K and the leaching time is 180min,the leaching rate of manganese,cobalt,and nickel reaches the highest,and the highest leaching rate is 93.5%,87.4%,and 86.3%respectively.(2)The kinetic mechanism of the cooperative oxidation leaching process is analyzed.The results show that the main control step of the process is internal diffusion control,the apparent activation energy is 51.24kJ/mol,and the kinetic equation is:1-2/3X-(1-X)2/3=e10.40·[H2SO4]1.2078·[MnO2/MS]2.339·exp(-51.4/T)·t(3)For the concentrations of manganese,cobalt,and nickel is34.58g/L,2.81g/L,2.19g/L respectively,the collaborative oxidation leaching solution adopts process of secondary extraction of manganese using P204-reverse extraction of cobalt,nickel-reverse extraction of manganese to enrich.In the primary extraction,the extraction rate of manganese is 65.49%under the conditions that the volume content of P204 is 30%,the phase ratio is 2.5:1,the pH is 3.5,and the saponification rate is 30%.In the secondary extraction,the total extraction rate of manganese reaches 98.67%under the conditions that the P204 content of is 30%,the saponificating rate is 30%,and the O/A is 2:1.The manganese-loaded organic phase is stripped of cobalt and nickel with dilute sulfuric acid.The stripping rates of cobalt and nickel reach 92.1%and 93.2%under the conditions of O/A=10:1 and acidity of 70g/L respectively.The concentration of cobalt and nickel in the organic phase are both less than 0.01g/L,and the manganese can be enriched by stripping directly.The manganese-loaded organic phase is enriched by dilute sulfuric acid by stripping.Under the conditions of O/A=4:1 and acidity of 110g/L,the stripping rate of manganese reaches 99.1%.The concentration of manganese in the manganese-loaded water phase is up to 28.32g/L,and the concentration of cobalt and nickel is less than 0.05g/L.(4)Cobalt and nickel in solutions were extracted and separated by P507-Cyanex301 co-extraction system.It is determined that the system has a positive synergistic extraction effect.The synergistic extraction system performs secondary countercurrent extraction of cobalt and nickel.The extraction rate of cobalt is 99.2%under the conditions that the volume content of the extractant is 30%,the O/A is 1:2,and the ratio of extractant is P/C(The volume ratio of P507 and Cyanex301)is 1:2,the saponification rate is 40%,the pH of the external water phase is 4.0,and the extraction time is 5 minutes,while the extraction rate of nickel is only 8.35%.The constant boundary cell method was used to analyze the kinetics of the co-extraction system for cobalt extraction,and the equation of extracting kinetic was obtained:R=k[Co2+][P507]0.7332[301]0.5766.(5)The contents of manganese,cobalt and nickel are 11.71%,1.21%and 0.97%of purified sulfide slag respectively.The total recovery rate of manganese,cobalt,and nickel is 84.7%,77.24%and 71.62%respectively after cooperative oxidation leaching and extraction separation process.