Method for treating polluted acidic wastewater from smelting with activated pyrite concentrate

A method for treating a polluted acidic wastewater from a smelting with an activated pyrite concentrate, comprising:

• A, a pyrite concentrate pretreatment:
• drying and grinding a pyrite concentrate to produce a pyrite concentrate powder, and washing the pyrite concentrate powder twice with purified water and absolute ethanol successively to produce a washed pyrite concentrate powder for a later use, wherein the pyrite concentrate comprises the following components:
• 42.56% to 48.95% of Fe, 43.28% to 49.26% of S, 3.0% or less of SiO2, 1.12% or less of Zn, and 0.44% or less of Pb;
• B, a pyrite concentrate activation:
• thoroughly mixing the washed pyrite concentrate powder and a Na2S powder in a mass ratio of 10:(1-2) to produce a mixed powder;
• feeding the mixed powder into a reactor, and adding purified water, wherein a mass-to-volume ratio of the mixed powder to the purified water is (400-500) g:1,000 mL;
• allowing a reaction for 3.5 h to 4.5 h at 105° C. to 115° C., 0.3 MPa to 0.5 MPa, and 160 r/min to 200 r/min, and naturally cooling to a room temperature to produce a reaction solution;
• filtering the reaction solution to produce the activated pyrite concentrate;
• and subjecting the activated pyrite concentrate to an aeration and a standing, a drying, and a grinding to produce an activated pyrite concentrate powder for a later use, wherein the activated pyrite concentrate powder comprises the following components:
• 37.28% to 42.56% of Fe, 42.64% to 48.54% of S, 4.76% to 8.65% of Na, 2.35% or less of SiO2, 0.97% or less of Zn, and 0.38% or less of Pb;
• and
• C, a polluted acidic wastewater treatment:
• adding a first lime slurry to the polluted acidic wastewater to adjust a pH of the polluted acidic wastewater to 2.0 to 4.0;
• adding the activated pyrite concentrate powder at an amount of 12.0 g to 20.0 g per 1.0 L of the polluted acidic wastewater, and allowing an ultrasonic treatment at an ultrasonic frequency of 25 kHz to 28 kHz, wherein a temperature of the polluted acidic wastewater is maintained at 28° C. to 32° C., a continuous stirring is conducted at a rotational speed of 140 r/min to 180 r/min for 5 h to 6 h, and a dissolved oxygen content of the polluted acidic wastewater is maintained at 10.0 mg/L to 15.0 mg/L;
• allowing a first static settlement for 30 min to 60 min to produce a first supernatant;
• adding a second lime slurry to the first supernatant to adjust a pH of the first supernatant to 8.0 to 9.0;
• further allowing a second static settlement for 30 min to 60 min to produce a second supernatant;
• and centrifuging the second supernatant to obtain a final treated water.