Treatment method of spent lye from ethylene production

• Main Authors: QIN LIJIAO, XU YING, ZHOU TONG, DENG DEGANG
• Format: Patent
• Language: English
• Published: 13.05.2015
• Subjects: CHEMISTRY; COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM,RUBIDIUM, CAESIUM, OR FRANCIUM; INORGANIC CHEMISTRY; METALLURGY; TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE

The invention relates to a treatment method of spent lye from ethylene production. The method comprises the following steps: (1) air-floating deoiling: oil substances in spent lye from ethylene production are removed; (2) high-temperature and humid oxidation treatment: sodium hydroxide is added into the deoiled spent lye such that the spent lye reacts under the alkaline condition; (3) vitriolization: concentrated sulfuric acid is added into the spent lye which has undergone high-temperature and humid oxidation treatment, so as to generate sodium sulfate; (4) evaporation and concentration: the spent lye which has undergone vitriolization undergoes evaporation and concentration; and (5) adjustment of alkali concentration: solid sodium hydroxide is added into the spent lye which has undergone evaporation and concentration, precipitated sodium sulfate is recovered, and a generated high-concentration sodium hydroxide solution is recycled to the step (2) and/or an upstream alkaline tower. According to the invention, COD and sulfide in the ethylene spent lye can be efficiently removed. Meanwhile, calcium carbonate and sodium sulfate can be effectively recovered. The processed sodium hydroxide solution is recycled, thus realizing zero emission of the ethylene spent lye.