微波与常规加热酸浸废SCR催化剂提钒效果比较

Comparison of effect of microwave and conventional heating acid leaching waste SCR catalyst on vanadium extraction

以废SCR(选择性催化还原法)脱硝催化剂为研究对象,采用H_2SO_4酸浸提钒,并引入微波强化浸出,考察H_2SO_4浓度、浸出温度、液固比、助浸剂及微波功率等因素对钒浸出率的影响,同时比较微波强化及常规加热对钒浸出效果的影响,并建立废SCR催化剂中的钒酸浸动力学模型.结果表明:H+在废SCR催化剂提钒浸出过程中起到关键作用,钒的浸出率随着H_2SO_4浓度、CaF_2助浸剂添加量、液固比及温度的增加而增大;微波加热可强化废SCR催化剂中的钒浸出,钒浸出率随微波功率增加而增大;在H_2SO_4浓度5mol/L、CaF_2助浸剂添加量20kg/t、液固比10∶1、微波功率600 W、浸出时间30min及浸出温度100℃的最佳微波强化浸出工艺条件下,钒的浸出率达到92.3%,比常规加热浸出提高了31.8%;废SCR催化剂提钒酸浸过程主要为固膜扩散和化学反应过程,其表观活化能为24.57kJ/mol.

In this study, extraction of vanadium from SCR （selective catalytic reduction） denitration catalyst by microwave and conventional leaching methods were investigated. The parameters such as H2SO4 concentration, leaching temperature, liquid-solid ratio, leaching agent and microwave power on the effects of H2SO4 on the extraction of vanadium were also investigated. The results of conventional acid leaching experiments were compared to the microwave leaching method. A kinetic model for the leaching of vanadium in waste SCR catalyst was established. The results shows that H＋ ions play an important role in the process of leaching vanadium for the waste SCR catalyst. The vanadium recovery output increases with the increasing of the sulfuric acid concentration, temperature,liquid-solid ratio and dosage of CaF2. Besides, the leaching rate could be enhanced with microwave heating in comparison with conventional heating. Consequently,the optimized experimental conditions were achieved： 5 mol/L sulfuric acid, 100 ℃ leaching temperature, 10 ： 1 liquid-solid ratio,20 kg/t dosage of CaF2 as assisted leaching reagent, 600 W microwave power. The vanadium recovery output reached up to 92.3% in 30 mins, having an increase of 31.8% compared with conventional heating under the same conditions. Furthermore, the process of leaching of vanadium was controlled by the combination of the diffusion of solid layer and chemical reaction, and the apparent activation energy was 24.57 kJ/mol.