Study on resource utilization technology of nonferrous metals tungsten and lead-zinc tailings

The ZSM-5 molecular sieve was synthesized by conventional hydrothermal method (CH) and microwave hydrothermal method (MH), using non-ferrous metal tungsten ore and lead-zinc ore tailings as materials which were activated pretreatment by high-temperature alkali fusing after acid leaching and low-temperature alkali dissolving without acid leaching, respectively. The obtained products were characterizated by XRF, ICP-AES, FT-IR, XRD, SEM, BET and catalyst activity evaluation. The results show that, the synthesized product is ZSM-5 molecular sieve. BET shows that the total specific surface area of the product is between 273.21-350.51 m2/g, and the pore diameter of the product by the MH is small. Low-temperature alkali dissolution activate pretreatment can obtain higher n(SiO2)/n(Al2O3) liquid precursors, which leads to the transformation of the morphology of the product from a spherical shape to a hexagonal prism shape, and the particle size of the product decreases. The product synthesis by activation pretreatment with high-temperature alkali fusion has a higher utilization of the SiO2 of dried tailings, but the process is complicated and the energy consumption is high. The sequence of influence factors of SiO2 dissolution rate during activation from high to low are: CaO, Others, Fe2O3. The required time to synthesize ZSM-5 with the same crystallinity by MH method is only about a quarter of the that of CH method, and the product size by the MH method is smaller, the surface is cleaner, and the SiO2 utilization rate is also higher. The 1 L reactor has a small amplification effect, and the stirring conditions are conducive to the mass and heat transfer of the synthesis system, resulting in a decrease in the particle size of the product, and the NO conversion rate of the product applied to the denitration reaction can reach 94.31%. © 2021, Science Press. All right reserved.