| There are a lot of industrial boilers, and their distribution is very wide in our country. Along with their pollution to the atmosphere becoming more and more serious, developing desulfurization technologies of middle and small scale boilers and reducing emissions of sulfur oxides to the atmosphere has become an important and urgent work. Wet flue gas desulphurization technology(WFGD)as a relatively mature technology that has higher desulfurization efficiency, is the most widely used method in the world, and the most popular of which is the wet-type limestone/lime-gypsum process. Yet it often encounters problems such as fouling, clogging, and difficulty of selling the by-products during the system working. In China, especially in the southern provinces such as Hunan, Hubei, Zhejiang, Guizhou Province. There are abundant navajoite ore resources, which are often used in the field of hydrometallurgical technology, and there has not yet been reports of the use in desulfurization areas. In conventional technology, Vanadium Pentoxide(V2O5) is extracted from navajoite by roasting with adding sodium chloride. Large amounts of chlorine, hydrogen chloride, sulfur dioxide and other harmful gases and waste water produced in the process, simultaneously, the energy consumption is high, while the yield of vanadium is low.An innovative flue gas desulfurization (FGD) coupling process was proposed in this study to overcome the problems in wet-type limestone/lime processes which include fouling, clogging, and difficulty of selling the by-products and the problems in traditional process for vanadium extraction from navajoite ore such as excessive consumption of sulphuric acid and emissions of pollutants. The performance of a jet bubbling reactor(JBR) at pilot-scale was evaluated using navajoite ore produced in the process of extracting vanadium pentoxide as desulfurization absorbent.Results showed that roasting additives used in the process were the new environment-friendly chlorine-free sodium salt compound additives, the amount of adding additives was 10%, optimum calcination temperature was 850℃, roasting time was 2.5-3.0 hours. Temperature of putting ore sample into furnace should be controlled at lower temperature, especially for the large-scale industrial production, the temperature should be below 200℃; Navajoite ore slurry achieved better desulfurization performance than limestone slurry. When the inlet flue gas pressure drop was 3.0 kPa, the gas flow was about 2350 m·h-1 and the pH of the navajoite ore slurry was higher than 4.5, the desulfurization efficiency was stable about 90%; The SO2 removal efficiency appeared to increase along with the increasing of absorbent cycle-index. The efficiency of the second circulation was improved 3.5% compared to the first circulation; After an operating duration of 40 minutes, the leaching rate of vanadium pentoxide was about 20%, and reached 62% when the by-products were leached with 5% dilute sulphuric acid for 10 hours; The leaching rate of V2O5 improved along with the increasing of sulphuric acid concentration, and it could reach the maximum 70.01% when the sulphuric acid concentration was 15% and leaching time was 10 hours, however, the sulphuric acid concentration increased again, the leaching rate had a decreasing trend. The by-product from this process not only could be used to produce vanadium pentoxide which is a valuable industrial product, but also could significantly overcome the pollution problem existing in the traditional refining process of vanadium pentoxide when navajoite ore is used as the feed material. This FGD process using roasted navajoite slurry as absorbent is environmental sound and cost-effective, and shows the potential for application in the field of flue gas desulfurization as well as hydrometallurgy. |
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