METHOD OF PROCESSING NEPHELINE Russian patent published in 2012 - IPC C01F7/24 

FIELD: chemistry.

SUBSTANCE: nepheline is fed into preheated nitric acid via uniform batching and the solution of nitrates is separated from the silicate residue by filtering. Nepheline is decomposed by nitric acid in the presence of carbamide which taken in amount of 0.20-0.45% of the weight of nepheline. Nepheline, nitric acid and carbamide are fed simultaneously with a flow rate which ensures concentration of free nitric acid in the nitric acid pulp of not less than 0.5%. The nepheline decomposition process is carried out at temperature 60-90°C. The rate of feeding reactants is controlled such that the dwell time of pulp in the reactor is 1-4 hours. The obtained pulp is separated into a solution of nitrates and a silicate residue, which are then processed into commercial products.

EFFECT: invention increases efficiency of the process, reduces release of nitrogen oxides into the gaseous phase.

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