Chlorine removal agent, and method and application for removing chlorine from waste acid wastewater by using same

Abstract

The invention belongs to the technical field of waste water and waste liquid treatment and recycling, and particularly relates to a chlorine removal agent, and a method and an application for removing chlorine from waste acid wastewater by using same. The method comprises the following steps: firstly, heating the acid wastewater to a certain temperature, then adding a proper amount of a dechlorinating agent, continuously heating and stirring the system for a certain time to efficiently remove chloride ions in the waste acid wastewater, and absorbing chlorine generated in the reaction process by using alkali liquor. The reaction principle is different from that of the prior art: chlorine ions in the contaminated acid wastewater are oxidized into chlorine by means of the principle of oxidation reduction and the high oxidation potential of a chlorine removal agent or an intermediate product in the reaction process, and the chlorine is volatilized due to the fact that the chlorine is not dissolved in an acidic solution. The concentration of chloride ions in the waste acid wastewater treated by the method is lower than 20 mg / L, so that the concentration of chloride ions in the waste acid wastewater meets the recycling requirement. The method not only solves the problem of removal of chloride ions in the acid wastewater, but also has low requirements on equipment, and realizes resource recovery of chlorine in the wastewater.

Description

technical field [0001] The invention belongs to the technical field of waste water and liquid treatment and reuse, and in particular relates to a chlorine removal agent and a method and application of using the same to remove chlorine from polluted acid wastewater. Background technique [0002] Sewage acid wastewater mainly comes from the flue gas purification process of sulfuric acid, non-ferrous metal smelting and other industries. It has the characteristics of large production volume and high acidity (sulfuric acid content reaches 5-20%). It not only contains heavy metals, but also contains high concentrations of fluorine and chlorine. It is a type of wastewater that is extremely difficult to treat, especially the concentration of chloride ions in this type of wastewater can reach thousands to tens of thousands of ppm, and its removal is extremely difficult. In order to realize the utilization of waste resources and reduce the damage caused by waste discharge to the envir...

AI Technical Summary

Problems solved by technology

One is to use waste copper slag containing a certain amount of zero-valent copper and copper sulfate produced in the smelting process as a dechlorination agent, and the dechlorination agent reacts with chloride ions to form cuprous chloride precipitation, thereby realizing the removal of chloride ions, but this The dechlorination effect of the method is limited (the dechlorination efficiency is only about 60%), which cannot meet the requirements for the reuse of polluted acid wastewater, and the price of waste copper slag is relatively high, resulting in high cost of the method

Another method is to evaporate and concentrate the polluted acid wastewater. After concentrating until the concentration of sulfuric acid reaches more than 50%, use hot air to blow off and remove the chloride ions in the form of hydrogen chloride (HCl) gas, so as to realize the removal of chloride ions in the polluted acid wastewater. Except, although the dechlorination efficiency of this method can reach more than 90%, and the residual chloride ion concentration can reach the level below 300mg / L, this method also has obvious shortcomings, mainly reflected in: (1) sulfuric acid in the polluted acid wastewater after concentration The concentration increases several times to dozens of times, and the concentration equipment and pipelines are severely corroded. Therefore, this method requires equipment and pipelines made of special materials, and the equipment construction cost is high, and it is operated under the condition of high concentration multiples, resulting in extremely serious scaling of equipment and pipelines , there are hidden dangers of explosion accidents; (2) a large amount of heat energy is consumed during the concentration process of dirty acid wastewater, and the operating cost is extremely high; (3) during the concentration and stripping process, hydrogen fluoride and hydrogen chloride in the dirty acid wastewater volatilize at the same time and enter the condensate, Since the condensate contains hydrogen fluoride and hydrogen chloride at the same time, not only can it not be used as a resource, but also it is extremely difficult to meet the standard and the cost is extremely high

[0004] In view of the above-mentioned technical defects, the removal of chlorine ions from polluted acid wastewater still has a large technical bottleneck, which greatly limits the smooth progress of resource treatment and reuse technologies of polluted acid wastewater.