| 摘要 |
<p>Disclosed is an improved method of recovering a salt having a solubility which increases with increasing temperatures from a multiple salt aqueous solution also containing a salt having a solubility which increases less with increasing temperatures than the solubility of the salt to be recovered. The solution is subjected to multiple effect evaporation having a plurality of evaporator effects operating at progressively higher temperatures. In the improved method a means is provided whereby the mother liquor effluent overflow from the hottest evaporator effect is saturated with the salt to be recovered. Additionally, solution being concentrated in other effects having at least one preceding cooler evaporator effect may be allowed to become saturated with respect to the salt to be recovered, A slurry of the salt having a solubility increasing less with temperature is withdrawn from all effects. This slurry is recycled from effects operated at saturation with respect to the salt to be produced and fed to at least one cooler effect. The solution in at least one cooler effect is concentrated to less than saturation with respect to the salt to be recovered. Thus, the solids of the slurry withdrawn from the cooler effect is not introduced back into the evaporation system thereby purging in a heat efficient manner the salt having a solubility increasing less with temperature.</p> |
