Method for producing impurity-bearing calcium chloride solution by utilization of cold rolling acid-bearing wastewater

Abstract

The invention discloses a method for producing heterogeneous calcium chloride solution by using cold-rolled acid-containing waste water, comprising cold-rolled acid-containing waste water, pickling waste liquid, dust removal ash or carbide slag, and the specific steps are: a. testing the acid-containing waste water and the molar concentration of HCl in the pickling waste liquid of steel materials, the mass percentage of CaO in dust removal ash or calcium carbide slag; according to the molar concentration of the impurity-containing CaCl2 solution to be prepared, the required addition of CaCl2 solution per unit volume to generate the impurity-containing CaCl2 solution is calculated according to the following formula The molar number of acid-containing wastewater, dedusting ash or carbide slag, and pickling waste liquid, and then calculate the unit volume based on the molar concentration of HCl in pickling waste liquid, acid-containing wastewater, and the mass percentage of CaO in dedusting ash or carbide slag. Containing impurity CaCl2 solution needs to add acid-containing waste water, the volume of pickling waste liquid and the quality of dedusting ash or carbide slag; CaO+2HCl=CaCl2+H2O; Prepare the emulsion in the tank; c, add the emulsion prepared in step b into the neutralization tank, and add pickling waste liquid and acid-containing waste water at the same time; d, flow the solution obtained in step c into the precipitation for static precipitation, the upper layer is clear and ready to It is a liquid calcium chloride solution containing impurities.

Description

technical field [0001] The invention belongs to the technical field of environmental protection and resource utilization, and in particular relates to a method for producing a solution containing calcium chloride by using cold-rolled acid-containing waste water in iron and steel metallurgy. Background technique [0002] Iron and steel enterprises use hydrochloric acid to pickle the iron oxide scale on the surface of the strip, and the strip after pickling is washed with water to wash the residual hydrochloric acid and oxides on the surface of the steel plate, resulting in a large amount of acid-containing wastewater. The pH value of acid-containing wastewater is generally 1 to 3, and acid-containing wastewater also contains Cl ions and COD, which are harmful to the environment. Therefore, a large amount of acid-containing wastewater from cold rolling must be treated before it can be discharged. At present, it is generally used to neutralize the acid-containing wastewater by ...

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Problems solved by technology

Problems existing in the prior art: Because the acid-containing wastewater is controlled by adding alkali and neutralizing treatment, the pH value exceeds the standard or the suspended matter SS exceeds the standard, which seriously affects the normal operation of the next process; the wastewater after neutralization treatment is harmful to the environment Cl ions and COD still exceed the standard, for example, the Cl ions in a large-scale cold rolling acid-containing wastewater are 2110mg / L, and the COD Cr It is 462.3mg / L, and the new national standard released in 2009 stipulates that COD in wastewater Cr If it is less than 100mg / L, harmful substances such as Cl ions and COD are discharged beyond the standard, causing great harm to the regional ecological environment, and enterprises have to pay a considerable amount of sewage charges every year

The advantage of this method is that the waste hydrochloric acid after the pickling of the strip is used, the reaction speed is controllable, and the gas after the reaction is treated. The disadvantage is that the crude calcium chloride solution after the reaction between the massive limestone and the waste hydrochloric acid after the pickling of the strip is It needs 3-4 days of precipitation treatment, long production cycle and relatively high cost

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