Solid-waste-discharge-free membrane method total halogenated caustic production method

Abstract

The invention relates to a solid-waste-discharge-free membrane method total halogenated caustic production method. The solid-waste-discharge-free membrane method total halogenated caustic production method comprises the following steps that brine is sent to an organic tubular membrane system for filtration after refining reaction, and the filtered permeate is divided into two parts, and one part of the permeate is denitrated to obtain low nitrate brine and high nitrate brine; the other part of the permeate is mixed with the low nitrate brine obtained in the step S1 to obtain first brine; and the first brine is adsorbed and then caustic soda and light slat brine are prepared through an ion membrane alkali produced system. According to the solid-waste-discharge-free membrane method total halogenated caustic production method, an alkali resistant nanofiltration membrane is used for denitrating the brine directly. Compared with a traditional process that water is added firstly for dilutionand then salt is dissolved to saturation, salt consumption, steam consumption and water consumption are saved, and the denitration cost is greatly reduced. In addition, the high nitrate brine is injected into wells with Mg(OH)2 and CaCO3 mud to solve the outlet problem of the high nitrate brine and the subsequent difficulties of treating the salt mud.

Description

technical field [0001] The invention belongs to the technical field of brine refining, and in particular relates to a membrane-based all-halogen soda production method without solid waste discharge. Background technique [0002] At present, the domestic chlor-alkali industry mainly adopts the ion-exchange membrane method to make alkali, and uses saturated brine as raw material to electrolyze to produce sodium hydroxide and other products. OH - The insoluble matter produced by the reaction is deposited on the ionic membrane, which seriously affects the life of the ionic membrane. Therefore, brine refining is extremely important in the production process of ionic membrane alkali production. [0003] The domestic traditional primary brine refining process based on the "barrel reactor + Doyle clarifier + sand filter" process route has been basically eliminated. At present, domestic chlor-alkali enterprises mainly use the following two membrane filtration processes: Gore membran...

AI Technical Summary

Problems solved by technology

At present, domestic chlor-alkali enterprises only use the membrane method for denitrification of light brine, but not for denitrification of high-concentration brine (NaCl>260g / L).

Therefore, for brine denitrification, this requires that the saturated brine mined from the ground must first be added with water to reduce the NaCl content in it, and then increase the NaCl content through the denitrification process, which is inefficient

In addition, the content of calcium and magnesium ions in brine is relatively high, and domestic chlor-alkali enterprises mainly use the two-alkali method to remove them, by adding NaOH, Na 2 CO 3 , the reaction produces Mg(OH) 2 , CaCO 3 The solid matter is then trapped in the concentrated solution through the membrane, and then the salt mud is pressed out through the filter press, and the salt mud is sent to the outside for treatment, but the subsequent treatment of the salt mud is becoming more and more difficult