Treatment method and treatment system for zero discharge and fractional crystallization of concentrated brine

Abstract

The invention relates to a treatment method and treatment system for zero discharge and fractional crystallization of concentrated brine. The method comprises the following steps: pre-reaction, to bemore specific, converting HCO3<2-> into CO3<2-> and removing heavy metal ions; magnetic flocculation, to be more specific, flocculating the pre-reacted wastewater; precipitation, to be more specific,precipitating the flocculated wastewater; concentration, to be more specific, sequentially carrying out positive osmosis and reverse osmosis separation on the precipitated supernatant, and outputtingseparated purified water; crystallization, to be more specific, crystallizing the concentrated highly concentrated brine; crystal separation, to be more specific, carrying out solid-liquid separationon crystallization slurry generated by the crystallization, and outputting a separated crystalline matter; and magnetic seed separation, to be more specific, separating a magnetic seed, sludge and water and recycling the magnetic seed. The system comprises a reaction tank, a flocculation tank, a sedimentation tank, a concentration device, a crystallization reaction reactor, a solid-liquid separation device and the like. The system is suitable for treating desulfurization concentrated brine of catalytic cracking flue gas and other similar high salt wastewater, and can realize zero discharge ofconcentrated brine and crystallization salt productization.

Description

technical field [0001] The present invention relates to the field of environmental protection technology, more specifically, to a treatment method for concentrated brine zero discharge and fractional crystallization, and to a concentrated brine zero discharge and fractional crystallization treatment system using this method. This method and system are suitable for treating catalytic Desulfurization concentrated brine of cracked flue gas and other similar high-salt wastewater. Background technique [0002] SO in the atmosphere x Mainly SO 2 , SO 2 The mass concentration in the air reaches (0.3~1.0)×10 -6 mg / m 3 When people smell the odor, humans and other animals react to SO 2 The response is bronchoconstriction. It is reported that SO in the atmosphere 2 The direct economic loss caused to our national economy accounts for about 2% of GDP, which seriously hinders the development of our national economy. Therefore, to SO 2 Emission control is imperative. [0003] Acc...

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Problems solved by technology

[0005] The main domestic methods used for catalytic cracking flue gas desulfurization are EDV wet scrubbing technology and WGS wet scrubbing technology of non-resource wet desulfurization process, but the main defects of these two technologies are the large consumption of fresh water and the high concentration of the discharged Saline sewage is difficult to treat, and has the following characteristics: 1) The concentration of suspended solids is high, the percentage of catalyst dust particle size less than 1.44 μm is high, and the hardness is high; 2) It contains 3% to 8wt% Na 2 SO 4 , catalyst dust, and heavy metal compounds, if they are directly evaporated and crystallized, the crystalline salt produced can only be treated as hazardous waste, which greatly increases operating costs. Therefore, there is no domestic device and technology for treating concentrated brine produced by catalytic cracking flue gas desulfurization

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