Method and device for preparing nitric acid through metal nitrate pyrolysis

Abstract

The invention relates to the field of industrial waste treatment, in particular to the field of hydrometallurgical production which requires nitric acid as an oxidant, and discloses a method and a device for preparing the nitric acid through metal nitrate pyrolysis. The method includes the steps of pyrolyzing metal nitrate powder in a closed device to generate O2, NO2 and metal oxide powder, injecting the obtained O2 and the obtained NO2 into a absorption tower, and circularly absorbing the O2 and the NO2 by absorption liquid in the absorption tower to obtain the nitric acid with the requiredconcentration. The device and the method have the advantages that the whole system is sealed with positive pressure, nitrate is fully pyrolyzed in a rotary kiln, the gases generated in the process arecompletely absorbed by the liquid in the absorption tower, and almost no waste gas and waste water are discharged; the nitric acid concentration can meet hydrometallurgical production requirements, high recovery of the nitric acid is realized, the production cost of the nitric acid is reduced greatly, and recycling of metal nitrate is achieved effectively at the same time.

Description

technical field [0001] The invention relates to a method for treating industrial waste and a preparation device thereof, in particular to a method for preparing nitric acid by pyrolysis of metal nitrate and a preparation device thereof. Background technique [0002] The salts formed by the reaction of nitrate HNO3 with metals are called metal nitrates. Nitrate is a general term for compounds derived from nitric acid, generally composed of metal ions - ammonium ions and nitrate ions. The common ones are sodium nitrate, potassium nitrate, ammonium nitrate, calcium nitrate, lead nitrate, cerium nitrate, etc. Nitrate is an ionic compound, containing nitrate ion NO3- and corresponding positive ion, such as NH4+ ion in ammonium nitrate. Common nitrates are: sodium nitrate, potassium nitrate, ammonium nitrate, calcium nitrate, lead nitrate, cerium nitrate, etc. Almost all nitrates are easily soluble in water, only urea nitrate is slightly soluble in water, and bismuth subnitrate...

AI Technical Summary

Problems solved by technology

[0006] In the process of industrial production, most industries will directly or indirectly produce metal nitrates, but these nitrates can be reduced to nitrite after entering the environment and ingested by the human body. On October 27, 2017, the world The list of carcinogens released by the International Agency for Research on Cancer of the World Health Organization is a preliminary collation reference. Nitrate or nitrite ingested under the conditions that lead to endogenous nitrosation is in the list of 2A carcinogens, which seriously endangers human safety, so it needs to be dealt with reasonably This part of nitrate

At the same time, in the field of hydrometallurgy, a large amount of nitric acid needs to be used in the production process, but the existing nitric acid production methods are expensive in equipment and high in production costs

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