Continuous production vacuum distillation equipment and process for recovery of iron-containing waste acid liquid

Abstract

The invention relates to the field of the recovery of waste acids, and particularly relates to a continuous-production reduced pressure distillation device and a continuous-production reduced pressure distillation process for recovering iron-containing waste acid liquid. The continuous-production reduced pressure distillation device comprises a blending tank, an evaporation reaction kettle, a crystallization kettle, a solid-liquid separation tank, a ferrous chloride solution collection pool and a ferrous chloride solution collection tank, and also comprises an exhaust pipe and a HCl collection tank, wherein the blending tank is used for blending a ferrous chloride solution; the evaporation reaction kettle is connected with an output end of the blending tank and is used for evaporating the ferrous chloride solution to be concentrated liquid; the crystallization kettle is connected with an output end of the evaporation reaction kettle and is used for separating out a ferrous chloride crystal from the concentrated liquid; the solid-liquid separation tank is connected with an output end of the crystallization kettle and is used for separating the crystallized ferrous chloride crystal from the ferrous chloride solution; the ferrous chloride collection pool and the ferrous chloride collection tank are connected with an output end of the separation tank and are used for collecting the separated ferrous chloride solution; the exhaust pipe is connected with the top of the evaporation reaction kettle and is used for outputting evaporated acid-containing steam; the HCl collection tank is connected with the exhaust pipe and is used for collecting the acid-containing steam. The continuous-production reduced pressure distillation device and the continuous-production reduced pressure distillation process for recovering the iron-containing waste acid liquid are low in treatment cost, high in treatment efficiency, low in safety production requirement and free from secondary pollution; the resource utilization rate can be improved.

Description

technical field [0001] The invention relates to the field of waste acid recovery, in particular to a vacuum distillation equipment and process for continuous production of iron-containing waste acid liquid recovery. Background technique [0002] In chemical production, waste hydrochloric acid is often produced. For example, iron castings are widely used as raw materials in electroplating and steel industries. Before use, these iron castings often need to be dipped and rinsed with concentrated hydrochloric acid to remove surface rust. After cleaning, waste hydrochloric acid is produced. The waste hydrochloric pickling liquid is brownish yellow, the concentration of HCl is 0.8-3mol / L, the content of divalent iron ions is 70g / L-100g / L, and the content of ferric ions is 0-10g / L. [0003] Because these waste acids contain impurities, they cannot be directly recycled, and direct discharge will cause waste of resources on the one hand, and environmental pollution on the other hand,...

AI Technical Summary

Problems solved by technology

Due to the high cost of the traditional neutralization method and the difficulty in disposing of the settled sludge, most enterprises have eliminated them.

The high-temperature roasting method is only industrially applied by large iron and steel enterprises due to the large initial investment, strict equipment and process requirements, even if the economic value of recovering hydrochloric acid and iron oxide powder is high.

After crystallization treatment by evaporation crystallization method, the residual iron content in the effluent liquid cannot reach the standard

Ion exchange method and membrane treatment method are limited by high concentration iron content, which is easy to cause resin and membrane fouling

The evaporative distillation method is favored by small iron and steel enterprises because of its advantages of simple equipment and low processing cost. However, when the hydrochloric acid waste liquid is evaporatively distilled, it will encounter the hydrochloric acid-water azeotrope obstacle, which will cause the acid-containing fraction to expand (expansion refers to the acid-containing fraction). distillate volume to the volume of hydrochloric acid waste acid), the concentration of the acid-containing fraction is very low and cannot be reused, which increases the processing cost of the back-end

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