Development of the technology and results of commissioning the recycling water system of a continuous pipe-rolling plant

Summary

«ECO-PROJECT» Research and Development Company, LLC has developed an innovative technology of recycling water supply for continuous pipe-rolling plants (CPRU) at ironworks. While using traditional, conceptually similar technologies, including coagulation-flocculation, thin-lamellar sedimentation, clarifying filtration and operation in a wastewater free mode, the concentration of suspended solids (iron scale) and mineral oils in the prepared recycling water is several times higher than that regulated by the CPRU manufacturers. The reason is the high concentration of soluble phosphates in the processed recycling water that are stabilizers of disperse systems coming from the rolling process and concentrating during recycling. The low efficiency of sedimentation results in the colmatage of the filtering media of the clarification filters, their decommissioning, forced blowing of up to 30% or more of contaminated recycling water into the industrial storm sewer, and overspending massively more of makeup natural water. The high concentration of mineral oils and abrasiveness of the solid phase of the generated sludge result in the colmatage of the filter press membranes, generation of heavily contaminated centrate that is difficult to clean, and wear of the centrifuges. The developed technology provides for: the removal of phosphates from 5% of the initial recycling water by adding lime milk, CO2 recarbonization of flue gases and clarification; elimination of unreasonable discharge of spent phosphate-containing process lubricant into the recycling water; single-stage coagulation-flocculation treatment of all the feed water in highly efficient sedimentation tanks-flocculators of the EP OF type; gravity chemical-free dewatering in structurally simple OKUD type units. The package of process solutions provides for preparing recycling water of standard quality and eliminating the discharge into the environment; processing scale-oil-containing sludge with a moisture content of 30% for the utilization in metallurgy; reducing the dimensions of the water treatment plants, operating and capital costs. The technology was implemented in the CPRU recycling water supply system of one of the pipe factories with reaching all the design target values.

Key words

recycling water system , ironworks , continuous pipe-rolling plant , coagulation-flocculation treatment , scale-oil-containing sludge