Splitting emulsions, separates oil phase in tank, precipitates heavy metal hydroxides from aqueous phase, dissolves them in acid and pumps to emulsion

摘要

First the emulsion is split in a tank (2), separating-off the oil phase. Then the aqueous phase is removed and subjected to a hydroxide precipitation which precipitates (3) the heavy metal content. The hydroxide phase obtained, is blended with an acid to dissolve it, before pumping it to the emulsion. The acid is organic or inorganic. They are supplied by a metering system and then the resultant second aqueous phase is transferred to a mixer. The pH value of the second aqueous phase is less than about 2. Before adding the acids, the hydroxide phase enters a buffer tank (4). Stirring in the mixer employs speeds of 10-1000 rpm. Using an alkaline solution in the second stage, the pH value is adjusted into the range 8-12. An independent claim is included for plant carrying out this process.