Study on selective separation of V, Mo, W from Ti in spent SCR denitrification catalyst
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摘要: 废钒钛系SCR脱硝催化剂是一种含有V、Mo、W、Ti等有价金属的危险废物，实现其无害化处理和资源化利用具有重要意义。分别采用Na2CO3焙烧-水浸、NaOH焙烧-水浸、NaOH常压浸出、NaOH加压浸出等工艺处理废V2O5-MoO3-WO3/TiO2四元SCR脱硝催化剂，实现了钒、钼、钨等活性组分与钛的选择性分离。通过研究焙烧参数和浸出参数对钒、钼、钨浸出率及浸出渣物相的影响，确定了NaOH焙烧-水浸工艺为废V2O5-MoO3-WO3/TiO2四元SCR脱硝催化剂的优选处理工艺。在优选条件下，经过NaOH焙烧-水浸后，V、Mo、W的浸出率分别为97.29%、99.33%和87.57%，并获得了主要物相为六钛酸钠（Na2Ti6O13）的浸出渣。Abstract: Spent V-Ti based SCR denitrification catalyst is a hazardous waste containing valuable metals such as V, Mo, W and Ti. It is of great significance to realize its harmless treatment and resource utilization. This study adopted processes such as Na2CO3 roasting-water leaching, NaOH roasting-water leaching, NaOH atmospheric pressure leaching, and NaOH pressurized leaching to treat spent V2O5-MoO3-WO3/TiO2 quaternary SCR denitration catalyst respectively, achieving the selective separation of active components such as vanadium, molybdenum, and tungsten from titanium. By studying the influences of roasting parameters and leaching parameters on the leaching efficiencies of vanadium, molybdenum, and tungsten, as well as the phases of the leaching residues, the NaOH roasting-water leaching process was determined as the optimal treatment process for the spent V2O5-MoO3-WO3/TiO2 quaternary SCR denitration catalyst. Under the optimized conditions, after NaOH roasting-water leaching, the leaching efficiencies of V, Mo and W reached 97.29%, 99.33% and 87.57%, respectively, and the leaching residue with sodium hexatitanate (Na2Ti6O13) as the main phase was obtained.
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Key words:
- spent SCR catalyst /
- sodium roasting-water leaching /
- Na2CO3 /
- NaOH /
- selective separation
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图 2 废SCR催化剂的SEM及EDS图谱
（a）SEM图谱; （b）A处EDS能谱图
Figure 2. SEM and EDS patterns of spent SCR catalyst
图 3 Na2CO3焙烧-水浸工艺中焙烧条件对元素浸出率及浸出渣物相的影响
（a）Na2CO3用量；（b）焙烧温度；（c）焙烧时间对元素浸出率的影响；（d）Na2CO3用量；（e）焙烧温度；（f）焙烧时间对浸出渣物相的影响
Figure 3. Effects of roasting conditions on elements leaching efficiencies and leaching residue phases in the Na2CO3 roasting-water leaching process
图 4 Na2CO3焙烧-水浸工艺中浸出条件对元素浸出率的影响
（a）水浸温度；（b）水浸液固比；（c）水浸时间
Figure 4. Effects of leaching conditions on elements leaching efficiencies in the Na2CO3 roasting-water leaching process
图 5 NaOH焙烧-水浸工艺中焙烧条件对元素浸出率及浸出渣物相的影响
（a）NaOH用量；（b）焙烧温度；（c）焙烧时间对元素浸出率的影响；（d）NaOH用量；（e）焙烧温度；（f）焙烧时间对浸出渣物相的影响
Figure 5. Effects of roasting conditions on elements leaching efficiencies and leaching residue phases in the NaOH roasting-water leaching process
图 6 NaOH焙烧-水浸工艺中浸出条件对元素浸出率的影响
（a）水浸温度; （b）水浸液固比; （c）水浸时间
Figure 6. Effects of leaching conditions on elements leaching efficiencies in the NaOH roasting-water leaching process
图 7 NaOH常压浸出工艺中浸出条件对元素浸出率的影响及浸出渣的XRD图谱
（a）NaOH的浓度；（b）浸出温度；（c）浸出液固比；（d）浸出时间对元素浸出率的影响；（e）最佳浸出条件下浸出渣的XRD图谱
Figure 7. Effects of leaching conditions on elements leaching efficiencies and the XRD pattern of the leaching residue in the NaOH atmospheric pressure leaching process
图 8 NaOH加压浸出工艺中浸出条件对元素浸出率及浸出渣物相的影响
（a）NaOH浓度；（b）浸出温度；（c）浸出液固比；（d）浸出时间对元素浸出率的影响；（e）NaOH浓度；（f）浸出温度；（g）浸出液固比；（h）浸出时间对浸出渣物相的影响
Figure 8. Effects of leaching conditions on elements leaching efficiencies and leaching residues phase in the NaOH pressure leaching process
图 9 不同工艺处理废SCR催化剂浸出渣的XRD图谱
Figure 9. XRD patterns of leaching residue of the spent SCR catalyst treated by different processes
图 10 不同工艺处理废SCR催化剂浸出渣的SEM及EDS图谱
（a）Na2CO3焙烧-水浸；（b）NaOH焙烧-水浸；（c）NaOH常压浸出；（d）NaOH加压浸出
Figure 10. SEM and EDS diagrams of leaching residues from spent SCR catalyst treated by different processes
表 1 废SCR催化剂化学组成
Table 1. Chemical composition of spent SCR catalyst
% Ti V Mo W Si Ca Al S C O 其他 43.15 1.25 0.93 1.04 1.12 0.79 0.28 1.63 3.09 43.75 2.97 
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表 2 四种分离工艺的优选条件及浸出率总结
Table 2. Summary of optimized conditions and leaching efficiencies for four separation processes
工艺 优选条件 浸出率/% 质量比 T/℃ t/min L/S CNaOH/
(mol·L−1)V Mo W Na2CO3
焙烧-水浸焙烧 0.7 800 30 95.82 99.15 87.91 浸出 20 2 4:1 NaOH
焙烧-水浸焙烧 0.3 750 30 97.29 99.33 87.57 浸出 25 6 3:1 NaOH
常压浸出浸出 25 60 6:1 0.6 69.16 65.44 7.09 NaOH
加压浸出浸出 180 100 6:1 5 96.97 99.25 90.93
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表 3 NaOH焙烧-水浸工艺获得的浸出液元素浓度
Table 3. Element concentration of leaching solution obtained by the NaOH roasting-water leaching process
g/L V Mo W Al P Ti Si S Na Ca 3.39 2.72 2.63 1.27 0.32 0.08 3.72 4.34
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表 4 NaOH焙烧-水浸获得的浸出渣的化学组成
Table 4. Chemical composition of leaching residue obtained by the NaOH roasting-water leaching process
% TiO2 Na2O SiO2 CaO Al2O3 V2O5 MoO3 WO3 P SO3 69.53 21.87 3.43 1.59 0.94 0.12 0.17 0.26 0.04 0.67
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