Comprehensive treatment method for harmless recycling of pickling sludge and pickling waste liquid

Abstract

The invention discloses a comprehensive treatment method for harmless recycling of pickling sludge and pickling waste liquid. The comprehensive treatment method comprises the following steps: (1) mixing the pickling sludge with the pickling waste liquid, and successively carrying out a reaction and filtering so as to obtain a filter cake and a filtrate; (2) adding waste scrap iron into the filtrate, and then carrying out filtering; (3) adding waste iron scraps to a filtrate obtained in the step 2, and successively carrying out a reaction and filtering; (4) adjusting the pH value of a filtrateobtained in the step 3, adding an auxiliary agent, successively carrying out stirring, standing and filtering, and measuring the total Fe concentration of the obtained filtrate; (5) adding water intothe filtrate for dilution so as to obtain a solution I, adjusting the pH value of the solution I, adding an oxidant for oxidation, controlling a pH value and a ratio of Fe<3+> to Fe<2+> in a system, preparing iron black or iron yellow, successively carrying out filtering, drying and grinding so as to obtain iron black or iron yellow powder, and calcining the powder to obtain iron oxide red. A solid obtained in the step (1) is used as a building material, and liquid and solids obtained in the rest steps can be used in the corresponding steps of next treatment. The comprehensive treatment methodof the invention solves technical problems in the treatment of the pickling sludge and the pickling waste liquid, and high economic return is obtained through preparation of the medium-grade and high-grade iron oxide.

Description

technical field [0001] The invention relates to the fields of iron and steel industry and preparation of inorganic materials, in particular to a harmless and comprehensive treatment method for pickling sludge and pickling waste liquid, which can prepare iron oxide inorganic materials. Background technique [0002] In the steel industry, since pickling (hydrochloric acid pickling or sulfuric acid washing) is an inevitable step, a large amount of steel pickling waste is produced every day. The waste liquid of iron and steel pickling contains high concentration of acid and iron ions, the content of free acid in the pickling waste liquid is about 6-10%, and the main component of iron ion is Fe 2+ , the content is between 80-150g / L, and there is also a small amount of Fe 3+ and some impurities, in addition, some pickling waste liquid also contains other traces of PO 4 3- , Zn 2+ Wait. These waste acids, which have the characteristics of high iron ion concentration, high acid...

AI Technical Summary

Problems solved by technology

At present, the level of centralized treatment of pickling wastewater is very low. Most of the pickling wastewater is mainly neutralized and precipitated by cheap and easy-to-obtain lime. Due to the poor effect of lime on heavy metal precipitation, there is still a large amount of lime that does not participate in the reaction during the reaction process. Wrapped by other flocs and sink in the sludge, resulting in the amount of sludge produced

At the same time, pickling sludge contains a large amount of heavy metals such as nickel, chromium, iron, and residual acid that have not been effectively precipitated and removed. If it is dumped randomly or simply landfilled, it will easily cause serious environmental pollution problems.

At present, there is no qualified technology for treating pickling sludge in my country, and the main problems in sludge treatment and disposal are as follows: (1) The production of pickling sludge is large and the composition is complex

At present, the treatment of pickling wastewater is mainly done by the enterprise itself by adding lime or sodium hydroxide. Lime has a poor effect on the precipitation of heavy metals, resulting in a large amount of sludge, complex metal components and difficult extraction, which is not conducive to subsequent resource utilization.

(2) The disposal method is unscientific and irregular, and there are potential environmental safety hazards

At present, there is no qualified technology for the treatment and disposal of pickling sludge in China. The existing resource utilization enterprises mainly use the pickling sludge for the production of cement or bricks after simple doping pretreatment, and the scale is small, and the disposal method is not standardized. , there are environmental safety hazards

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