For the recovery of arsenic in waste acid water produced in copper smelting

a two-stage operation was investigated

in which arsenic from waste acid water was first precipitated by ferrous sulfide

then lime was used to adjust the pH

and arsenic was removed further.The experiment showed that the parameters including dosage of material

pH of solution

reaction and aeration time affected the efficiency of arsenic removal.The experimental results indicated that the first stage required 3 h for the precipitation by ferrous sulfide at room temperature

the second stage required 30 min for aeration

and the best dosage of ferrous sulfide was two times of the calculated molar quantity.In this condition

after the two-stage treatment

the arsenic concentration in waste acid water was reduced from 6240 mg·L-1 to 0.5 mg·L-1.The average removal rate of arsenic from waste acid water was more than 99.9%

and the content of arsenic in the sludge was above 15%.