Odda Process With Calcium Precipitation

Hydro processes, however, are similar in these two sections. 

In the dissolving section phosphate rock and nitric acid are mixed together in the dissolving reactors. Nitric acid of about 60% concentration is used in slight stoichiometric excess. The temperature in the reactors is kept constant at 60 -70 C by cooling or heating nitric acid. In addition to fresh nitric acid, wash acid from the inerts filter and from the calcium nitrate tetrahydrate (CNTH) filter is fed to the reactors. 

The dissolving solution contains suspended solids, mostly quartz, originating from the rock. Quantity and size of the solids vary with the source of rock. Inerts act as an undesirable diluent of the nutrients in the final product and can cause damage to equipment and piping by erosion. 

Inerts are separated from the dissolving solution by gravity in lamella separators the clear solution overflows 

R-1 Dissolving reactoe- v-7 Neutralizer GR-13, GR-aS Crusher Storage tank 

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