The New Study Treatment Process Of Acid Mine Drainage

The new set of sewage treatment facilities built by a mining enterprise located insouthern Shanxi was used to treat acidic wastewater discharged by mine. Thewastewater contained a large number of heavy metal ions, the range of the pH is2～4,the Ion content in water and the water flow vary widely. Accordingly, the treatmentfacility based on LB-HMR (Xi’an, a patented technology) treatment process, to reducethe dosage of lime agents, improve the resistance of the load.The best way to fill andreflux, the effect of different dosing modes of lime on the moisture content of sludge,potassium permanganate pre-oxidation, sludge characteristics and so on. Some specificoperation parameters were obtained. During the debugging process, the task forcestudied on the characteristics of the treatment process, including dosing strategies, waterand mud reflux way, pretreatment measures.The main results were as follows:1. The process obviously achieved better effect than the LDS process, which couldeffectively reduce the dosing quantity of lime. Which was reduced about14%~28%compared to the three-stage neutralization process originally built by the mine.Meanwhile, improving the density of the sludge, filter press cloth replacement cycle hasbeen extended, reducing maintenance costs and labor intensity.2. When the lime was not added into the pre-reaction pool, LB-HMR main reactorwith the method of bottom water reached a better effect than the method of the methodof upper water, the optimal dosing quantity of cationic PAM is5ppm. When used themethod of bottom water, the moisture of sludge in the inner barrel was lower than themethod of upper water, the high density of sediment at the bottom was hit by the water with a certain speed, leading to the disturbance of high density of sediment and form akind of adsorption on heavy metal ions and water particles produced by neutralizationreaction, increased the compactness of particles.Under the condition of without PAM,when the inlet valve at the bottom of the reactor opened and only added lime into themain reactor, the minimum value of moisture content of sludge in the inner barrelminimum was95%, which was lower than96%obtained under the condition the both ofpretreatment pool and the main reactor were added lime. No matter what kind of waterway was adopt, the moisture content of sludge in the inner barrel was lower than that inthe outer barrel.3. When the activation time of PAM activation time is4hour, flocculation effect ofsludge in the outer barrel was best, in the meanwhile adding the PAM can reduce themoisture content of filter cake, reduce the sinotrans frequency of mud cake. Mud slagwas found to adhere on the filter cloth by scanning electron microscopy, crystal particlesin the sludge and flocculent unified density together densely, which was extruded intoflat under the under the large hydraulic press of plate and frame filter, clogged the watergap of the filter cloth, result in the filter cloth lose the ability of filtration.4. In the dry season, when the waste water filtered the consumption of lime is more0.1g/L than that without filtration, mainly because there was a certain amount ofsuspended matter in raw water, the suspension had the ability of adsorption of heavymetal ions, and could play the role of crystal nucleus, reducing the dosage of lime. Inthe rainy season, when the content of heavy metal ions in surface runoff scouringwastewater, the consumption of lime also increased, when the waste water filtered theconsumption of lime is more0.2g/L than that without filtration.5. When wastewater was pre-oxidized by KMnO4, sludge sedimentation rateincreased after adding lime neutralization, the volume of sediment also dropped.Because the Fe2+in the water was oxidized to Fe3+, and combined with hydroxyl ions toform iron hydroxide floc, which could effectively adsorb small particles and suspendedsolids in water, making the sludge particles become more compact.