The invention relates to a
magnetic separation method for treating oil-containing
graphite wastewater, and aims to treat oil and suspended substances in the oil-containing
graphite wastewater by using a combined process of air flotation and
magnetic separation. The
magnetic separation method comprises the following steps: A, firstly, adding
wastewater into an air flotation tank so as to enable
suspended solids such as a part of oil and
graphite in the wastewater to emerge from the
water level in an air flotation manner, and scraping the
suspended solids into a residue tank, wherein an internal circulation type
jet flow pressurization
dissolved air flotation method is adopted for air flotation, the dissolved air pressure is 0.25-0.4MPa, the
reflux ratio is 10-15%, the separation load is 10-13m<3> / m<2>.h, and the
retention time is 20-30 minutes; B, feeding air flotation
effluent into a magnetic separation device, performing pre-
magnetization by using a pre-
magnetization treater in the magnetic separation device, feeding the air flotation
effluent into an inclined tube
sedimentation tank along with
sewage, controlling the flowing speed of the inclined tube
sedimentation tank to be 20-35mm / s, subsequently enabling flocculating constituents and
suspended solids retained in the water to adhere to a magnetic disc by using a magnetic disc separator, controlling the flowing speed of wastewater flowing through a single magnetic disc separator to be 200-400m<3> / h, scraping the
sludge into a
sludge discharge device by using a
sludge scraper plate, and discharging out treated
clean water from a water outlet. The magnetic
separation method is free of
water treatment agent, and is applicable to treatment on
sewage which contains oil and graphite and is not liable to naturally precipitate.