Patent ID: 8871003

Claim:
A scalable and reproducible process for producing a ferric containing solution by the controlled oxidation of a ferrous containing solution, the process including two competing reactions comprising a ferrous oxidation reaction (1) and a sulfuric acid producing reaction (2): 2FeSO 4 +O 2 ( aq )+SO 2 ( aq )→Fe 2 (SO 4 ) 3 (1) SO 2 +½O 2 +H 2 O→H 2 SO 4 (2) wherein reaction (1) has a maximum oxidation rate, the process comprising: treating the ferrous containing solution in a reactor with one or more inlet gases containing sulfur dioxide and oxygen; controlling the delivery rate of the sulfur dioxide gas to a sulfur dioxide gas delivery rate that is at or below a maximum oxidation rate of ferrous to ferric in reaction (1); measuring and controlling the dissolved oxygen in the ferrous containing solution at a value between about 0.5 ppm and about 10 ppm at which: i. ferric reduction to ferrous is avoided, and ii. the selectivity of ferric production using reaction (1) over acid production using reaction (2) is set according to an acid requirement of the process; and controlling the dissolved oxygen at the value while maintaining the sulfur dioxide gas delivery rate, wherein the process is capable of being reproduced under different process and/or reactor conditions by operation of the process under the different conditions at the value of dissolved oxygen.