Pickling waste liquid treatment process of steel industry

Abstract

The invention discloses a pickling waste liquid treatment process of the steel industry. The pickling waste liquid treatment process comprises the following technical steps: a, primarily filtering a pickling waste liquid so as to filter off solid impurities and grease; b, adding alkali into the filtrate to adjust the pH value; c, feeding the solution obtained in the step b into a heavy metal capturer, and performing reaction on various metal ions in the solution and a heavy metal capturing agent, thereby forming a heavy metal precipitate; d, feeding the reactant obtained in the step c into a filter, filtering and recycling the heavy metal precipitate, and collecting the filtrate for later use; and e, feeding the filtrate obtained in the step d into a reverse osmosis device, and deeply treating, thereby obtaining water which almost meets the standard of pure water and can be recycled for production of washing water, wherein the thick water can be recycled to be used as primary pickling water used in a pickling process. The pickling waste liquid treatment process is simple and convenient to operate, low in cost, and applicable to industrialization popularization and application; the pickling waste liquid can be thoroughly treated, the recycling rate of heavy metal ions is high, and no secondary pollution is caused as the waste liquid is circulated and reused in a completely sealed manner after being treated.

Description

technical field [0001] The invention relates to a treatment process for pickling waste liquid in the iron and steel industry, belonging to the field of environmental protection wastewater treatment. Background technique [0002] Before surface electroplating and spraying, steel component blanks are generally pickled to remove oxides on the surface, thus producing pickling waste liquid and pickling wastewater. Among them, the pickling waste liquid contains a higher acid concentration, which can be recycled to regenerate the acid. However, a large amount of flushing water, that is, pickling wastewater has a low acid content, and it is very uneconomical to recycle, so it is discharged as wastewater. Among them, the main component of pickling wastewater is Fe 2+ , Fe 3+ 、Na + 、Cr 6+ , Mn 2+ 、Ni + , SO4 2- , F - 、H + Wait. At present, the common method for treating high-concentration iron and steel pickling wastewater is to use lime floating liquid to neutralize the pi...

AI Technical Summary

Problems solved by technology

At present, the common method of treating high-concentration iron and steel pickling wastewater is to use lime floating liquid to neutralize the pickling wastewater. This method is not thorough and causes secondary pollution.

Removal of metal ions by evaporation and crystallization, high investment in equipment and energy costs, and incomplete treatment, resulting in a large amount of acid mist, which has a bad impact on equipment and the environment

[0003] Chinese patent CN201410354864 discloses a treatment method for pickling wastewater in the iron and steel industry, which includes the following steps: a) introducing the pickling wastewater into a regulating tank, a chromium reduction tank, and a heavy metal trap; The heavy metal precipitation is separated from the clear liquid, and the clear liquid is introduced into the defluoridation filter for primary defluorination; c) The mixed solution after the primary defluoridation is introduced into the primary sedimentation tank for the separation of non-metallic precipitates and water , and then the clear liquid flows into the fluorine reaction tank for secondary defluorination; d) The mixed solution after the secondary defluorination is introduced into the secondary sedimentation tank to separate non-metallic precipitates from water, and the separated clear liquid is discharged to Storage in a clear water pool; the invention has a high separation efficiency of metal particles, and at the same time, the ultra-micro separator has a concentration effect, and no need to set up a concentration pool to separate the sediment from the clear liquid, saving space and labor, and is discharged from the secondary sedimentation tank The iron, chromium, nickel, fluorine and other indicators in the clear liquid all meet the first-level requirements of the national standard; it can be seen that the process in this method is complicated and the demand for facilities and sites is large; secondly, adding additional chemicals such as calcium chloride will not only increase the cost, but also introduce Additional components increase the difficulty of separation; third, resources are not comprehensively utilized, resulting in a large waste

[0004] In addition, Chinese patent 201210311772.8 (CN102828192A) discloses a recycling method for pickling waste liquid in the iron and steel industry, which is characterized in that it includes the following continuous steps: a) introducing the pickling waste liquid into a freezing crystallization tank for cooling and crystallization; b) Use a centrifuge to separate salt and acid; c) pass the above-mentioned desalted acid through a strong basic anion exchange resin, and then elute it with distilled water, and return the recovered sulfuric acid to the acid wash for use; d) separate the separated sulfuric acid Ferrous iron is dissolved in the above-mentioned resin effluent, and under the condition of stirring, catalyst and concentrated sulfuric acid are added until a reddish-brown transparent liquid is obtained, which is polyferric sulfate PFS; it can be seen that although this method has its unique features, but For the pickling waste liquid in the iron and steel industry with complex components, in addition to the effective recovery of ferrous ions, other ions still exist in the waste liquid, and further purification is required to meet the waste liquid discharge standard