Production methods summary

The fertiliser industry uses dilute nitric acid in the range 50 - 65% strength, but other processes require concentrated acid. The production process used results in dilute acid, which must then be further treated to produce the concentrated acid.
The production of nitric acid involves two stages:

  • The air oxidation of ammonia using a platinum/rhodium alloy catalyst

  • The absorption and further oxidation of the resulting gases in water

Pressure

Some plants operate at a single pressure (medium or high), but some operate at dual pressure, the absorption taking place at a higher pressure than the oxidation. This affects the emissions from the process, and whether additional measures need to be taken to reduce these.

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Concentrated Acid
Dilute nitric acid is concentrated using sulphuric acid.

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