| 摘要 |
A process for removing fluorides from water, comprising a step of treating the water to be purified with calcium hydroxide in a concentration between 1.5 and 3 equivalents of calcium per equivalent of fluoride in which said water and said calcium hydroxide are agitated for a time between 45 and 120 minutes at a temperature less than 45°C, characterised by:
a) adding a flocculating agent to the solution to sediment the sludge formed from Ca(OH) 2 and CaF 2
b) separating from the solution a first sludge containing Ca(OH) 2 and CaF 2 in excess
c) acidifying the solution until neutral pH is achieved
d) adding to the remaining solution an Al compound to obtain a second sludge consisting of a poorly soluble compound of F and Al
e) basifying the solution until a pH greater than 8.5 is achieved
f) adding a flocculating agent to the solution
g) separating said second sludge from the solution
h) measuring the concentration of the fluorides in the residual solution and, if this concentration exceeds a predetermined value, repeating steps c) - h). |
