Hydrometallurgical process development to recycle valuable metals from spent SCR deNO_X catalyst

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Spent SCR catalysts contain valuable metals like vanadium and tungsten, posing environmental risks due to toxic metal oxides.
• Increasing metal demand and resource depletion necessitate efficient recycling of secondary sources like spent catalysts.

Purpose of the Study:

• To investigate a soda roasting process using dissolved NaOH for spent SCR catalyst reprocessing.
• To compare this method with traditional dry roasting and evaluate its impact on subsequent water leaching.
• To optimize parameters for enhanced metal recovery and impurity reduction.

Main Methods:

• Optimized soda roasting of spent SCR catalyst using a 0.4 NaOH/catalyst ratio in solution at 973 K for 2 hours.
• De-ionized water leaching at 298 K for 30 minutes with a 30% pulp density.
• Analysis of leached metals (V, W) and impurities (Si).

Main Results:

• Achieved 95.4% tungsten and 80.2% vanadium leaching efficiency.
• Significantly reduced silicon compound leaching, minimizing the need for post-processing.
• Demonstrated reduced roasting temperature and leaching time compared to conventional methods.

Conclusions:

• The proposed dissolved NaOH soda roasting process is effective for spent SCR catalyst recycling.
• This method enhances leaching efficiency for vanadium and tungsten while minimizing silicon impurities.
• The process offers environmental and economic benefits through efficient metal recovery and reduced processing time.