Tih2-based alloy powder was recovered and prepared
In recent years, harmful pollution of solid waste has been paid special attention to, at present the most widely used catalyst is SCR denitrification catalyst, the catalyst is TiO2(80 ~ 85wt %) as the matrix, the main components include SiO2(4 ~ 6wt %), WO3(4 ~ 10wt %), and a small amount of V2O5 and Al2O3 auxiliary components. SCR denitrification catalyst operating temperature in 300 ~ 400℃, long-term high temperature operation will lead to catalyst poisoning. Generally speaking, the service time of SCR denitrification catalyst is about 25,000 hours. The poisoned catalyst will undergo a series of treatments such as physical cleaning and removal of toxic elements to regenerate it, and the regenerated catalyst will be put into use again. However, after long-term use, some catalysts will be irreversible damage, then a large number of waste denitration catalyst will be treated by landfill, landfill treatment cost is high, waste of land resources, environmental risk, but also cause the waste of valuable resources. The recycling of waste SCR denitrification catalyst is of great significance for improving environmental quality, improving resource utilization efficiency and reducing production cost.
At present, there are two ways to deal with waste denitrification catalyst. One is to activate the deactivated waste denitrification catalyst for regeneration, the other is to use the wet method to recover the valuable metals, such as Vanadium, Tungsten, etc. The second way to recover precious metals only recycles part of the metal, and the other metals are still in the waste acid, which still has many hidden dangers. Moreover, wet recycling involves long process, high energy consumption, and the final product purity cannot meet the commercial requirements.
We need efficient methods to recover solid waste SCR denitrification catalysts and recycle valuable metals efficiently, which will help solve environmental problems, save resources and improve economic benefits.
(1) Pretreatment of the waste SCR denitrification catalyst: the waste SCR denitrification catalyst in turn for ash removal, cleaning and ball milling, and 100 ~ 200 mesh sieve, and then into the Muffle furnace, at 300 ~ 400℃ for 2 hours to remove the water of crystal;
(2) Mixed raw materials: the discarded SCR denitrification catalyst, molten salt (MgCl2 and CaCl2 mixed chloride) and Mg powder were mixed according to the mass proportion, and the mixed powder was put into the molybdenum crucible after mixing; Since the subsequent operation needs to be carried out at high temperature, the molybdenum crucible is the most suitable container.
(3) Mg thermal reduction: put the molybdenum crucible with mixed powder into the atmosphere furnace, Mg thermal reduction in H2 atmosphere, molybdenum crucible in the reduction temperature of 700 ~ 850℃ in the environment, with the furnace cooling after the molybdenum crucible to obtain the reduction powder;
(4) water immersion removal of chloride: the obtained powder in a water bath at 50 ~ 100℃ stirring, pumping and filtering to get water immersion powder and chloride solution, and the water immersion powder at 50 ~ 100℃ drying;
5) Recovery of molten salt: put the obtained chloride solution into the drying box to dry for 10 ~ 16h. After drying, put it into the Muffle furnace for heat treatment. Hold the heat at 800 ~ 950℃ to remove the water, and obtain the renewable molten chloride salt;
