Development prospects of concentrated nitric acid using the magnesium nitrate method
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The prospects for the use of the magnesium nitrate method in the production of concentrated nitric acid: Currently, there are only two methods for producing concentrated nitric acid in China, namely the direct method and the indirect method (with the magnesium nitrate method being the most common). The biggest obstacle to the development of this method is related to the materials used; high-silicon cast iron can be used for the concentration towers. However, due to limitations associated with this material, the maximum diameter of such towers is currently only 1.2 meters (with the majority having a diameter of 1 meter), which significantly limits their production capacity. To increase production capacity, it is necessary to use multiple towers in series.
It is recommended to use a steel glass-lined tower, which can withstand temperatures of 180 degrees and has no issues with corrosion resistance. The diameter can reach 1.6 meters, and the height of each section can reach 2 meters. It’s not much more expensive than ferrosilicon.
Currently, a single production unit using the nitromagnesium method for the production of concentrated nitric acid can achieve a capacity of 20 kt/a. All the concentration towers are made of high-silicon cast iron; the diameter of these towers is generally 1 m, with the largest ones having a diameter of 1.2 m. By using corrugated packing instead of traditional packing, the capacity of the unit can be increased by about 20%. Many facilities, such as the Jinan Fertilizer Plant, Nanhua, Chuanhua, and Huaihua, are equipped with nitrate-magnesium processes for the production of concentrated nitric acid.
Although a series of modifications have increased the production capacity of single towers using the nitromagnesium method for concentrated nitric acid, it remains a bottleneck preventing large-scale production. To increase capacity, more single towers and multiple series would need to be used. What I’m asking is whether it’s possible to reform the process by adopting a third method for producing concentrated nitric acid, namely a azeotropic distillation method. Currently, Russia already has production facilities using this method with a capacity of 100,000 tons per year, and these facilities achieve zero emissions. I think it’s time for our country to consider this production process, as it is beneficial not only in terms of investment but also for increasing production capacity
Given the actual conditions in China, the nitromagnesium method for concentrated nitric acid production is the best and most feasible option. The sulfuric acid method for nitric acid production involves the problem of concentrating waste sulfuric acid, while the direct method for concentrated nitric acid poses issues related to high pressure and considerable risk ； Azeotropic distillation is still in the experimental stage at present and has not reached industrial application, and the investment required would be enormous.
The last edit to this post was made by lxq700918 on 2009-7-13 at 19:59. In response to the second comment, using glass-lined materials is still worth trying; their strength and toughness need further improvement. Pipes can be used in this application, but the sealing surfaces must be properly handled