Study On The Influencing Factors And Kinetics Of Phosphate Slurry Desulfurization

With the rapid development of socio-economic on our country and the ever-increasing living standard of residents,the contradiction between economic development and ecological protection is becoming increasingly apparen.SO₂ is one of the three major pollution sources,which can cause acid rain and water-soluble particles of smog.China proposed that SO ₂ should be reduced by 3%during the“13th Five-Year plan”to protect the ecological environment.Phosphorus slurry wet flue gas desulfurization is a kind of economical wet flue gas desulfurization,which is suitable for china's national conditions.There is good prospect for development on this technology.Phosphorus slurry is rich in metal ions,which have a significant influence on conversion of S?IV?to S?VI?.The intrinsic reaction kinetics of liquid-phase catalytic oxidation of S?IV?with single metal ions and composite metal ions was studied by a batch-type sealed reactor.The activation energies of the reaction in various metal ion systems were determined,and the catalytic performance was also compared.The kinetics of phosphate slurry wet flue gas desulfurization was researched by means of segmentation method.The rate control step and macroscopic reaction kinetics equation were obtained.?1?The effects of single metal ions(Fe³⁺/Fe²⁺/Mn²⁺/Mg²⁺/Al³⁺/Cu²⁺)on the oxidation of S?IV?were investigated.The order of the ability of liquid-phase oxidation of S?IV?was Mn²⁺>Fe³⁺>Fe²⁺>Mg²⁺>uncatalytic oxidation>Al³⁺>Cu²⁺.The experimental results showed that Mn²⁺,Fe³⁺,Fe²⁺and Mg²⁺can catalyze the oxidation of S?IV?,while Al³⁺and Cu²⁺inhibited the oxidation of S?IV?,the inhibition of Cu²⁺was stronger than that of Al³⁺.The activation energies of above systems were 23.25,41.00,54.97,61.87,63.59,70.96,80.75k J/mol.?2?The effects of seven composite metal ions(Fe³⁺-Mn²⁺,Fe³⁺-Cu²⁺,Mn²⁺-Cu²⁺,Fe³⁺-Al³⁺,Mn²⁺-Al³⁺,Fe³⁺-Mg²⁺,Mn²⁺-Mg²⁺)on the oxidation of S?IV?were investigated.The experimental results show ed that composite metal ions(Fe³⁺-Mn²⁺,Fe³⁺-Cu²⁺,Fe³⁺-Al³⁺,Mn²⁺-Al³⁺,Fe³⁺-Mg²⁺,Mn²⁺-Mg²⁺)all promoted the oxidation of S?IV?,the system of Fe³⁺-Mn²⁺had synergistic effect,while Fe³⁺-Cu²⁺,Fe³⁺-Al³⁺,Mn²⁺-Al³⁺,Fe³⁺-Mg²⁺and Mn²⁺-Mg²⁺had antagonistic effect.Mn²⁺-Cu²⁺had inhibitory effect on the oxidation of S?IV?.The activation energy of liquid-phase oxidation about S?IV?by Fe³⁺-Mn²⁺,Fe³⁺-Cu²⁺,Mn²⁺-Cu²⁺,Fe³⁺-Al³⁺,Mn²⁺-Al³⁺,Fe³⁺-Mg²⁺,Mn²⁺-Mg²⁺were 15.00,67.83,73.39,42.25,60.75,46.90,49.79k J/mol.?3?The reaction rate of gas-liquid mass transfer of SO₂,catalyzed oxidation of sulfurous acid and decomposition of phosphate rock were studied.The results showed that the gas-liquid mass transfer of SO₂ was the control link of the whole reaction,the further study show ed that the SO₂ gas film mass transfer was a control step in the gas-liquid mass transfer of SO₂.Macroscopic reaction kinetics equation was established on the basis of the control step:R?so₂?=3.19×10^-6A_g???.