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Process method for treating hot-dip galvanizing waste hydrochloric acid

A process method and waste hydrochloric acid technology are applied in the field of industrial waste resource treatment, which can solve the problems of wasting enterprise costs, unfavorable small and medium-sized enterprises to promote the use of hot-dip galvanizing waste hydrochloric acid treatment, and environmental pollution, so as to avoid the increase of waste water treatment volume Large, conducive to the protection of the ecological environment, the effect of low operational risk factor

Inactive Publication Date: 2020-04-17
3R ENVIRONMENTAL TECH CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Hot-dip galvanizing waste hydrochloric acid has a large amount, strong acidity, and high concentration. The main pollutants are zinc chloride 40-70g / L, ferrous chloride 80-120g / L, and acidity (calculated as HCl) 40-50g / L If the direct discharge is not dealt with, it will not only cause serious pollution to the environment, but also cause waste of zinc, iron, and acid resources and increase the cost of enterprises. At present, my country has included it in the "National Hazardous Waste List" for management
[0005] The traditional treatment method for hot-dip galvanizing waste hydrochloric acid is generally to use liquid caustic soda, quicklime, slaked lime or carbide slag for neutralization, but this method will produce a large amount of waste residue after treatment, causing secondary pollution to the environment
There is also the oxidation roasting method, which sprays waste hydrochloric acid into a kiln at 600°C, and Fe 2 o 3 Discharged from the bottom of the furnace, hydrogen chloride gas is absorbed by water to produce hydrochloric acid as a by-product, but this method requires large equipment investment, high energy consumption, and high operating costs, which is not conducive to the promotion and use of small and medium-sized enterprises and the treatment of a large amount of hot-dip galvanizing waste hydrochloric acid

Method used

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  • Process method for treating hot-dip galvanizing waste hydrochloric acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] (1) Beat the hot-dip galvanizing waste hydrochloric acid with a zinc content of 9985ppm into the stirring tank, add excess coil iron, stir for 30 minutes, and then feed the three-effect evaporation after passing through a 300μm pore size filter.

[0038] (2) When the specific gravity of the evaporated material liquid reaches 1.45, start to discharge the material to the crystallization kettle, and the crystallization kettle is covered with cooling water.

[0039] (3) When the feed liquid temperature in the crystallization tank was down to 45°C, it began to discharge to the centrifuge, and a primary crystallization and mother liquor of ferrous chloride were obtained. After testing, the zinc content of the primary crystallization was 2085ppm, and the zinc content of the mother liquor was 2085ppm. 33125ppm.

[0040] (4) the primary crystallization in step (3) is dissolved in 0.16% evaporative condensed water with an acid content (in HCl, the same below), and the gained soluti...

Embodiment 2

[0048] (1) Beat hot-dip galvanizing waste hydrochloric acid with a zinc content of 4820ppm into the stirring tank, add excess iron sheet, stir for 30 minutes, and then feed the three-effect evaporation after passing through a 100μm pore size filter.

[0049] (2) When the specific gravity of the evaporated material liquid reaches 1.49, start to discharge the material to the crystallization kettle, and the crystallization kettle is covered with cooling water.

[0050] (3) When the feed liquid temperature in the crystallization tank was down to 23°C, it began to discharge to the centrifuge, and the primary crystallization and mother liquor of ferrous chloride were obtained. After testing, the zinc content of the primary crystallization was 945ppm, and the zinc content of the mother liquor was 945ppm. 14500ppm.

[0051] (4) the primary crystallization in step (3) is dissolved in 5.34% evaporative condensed water with acid content (in terms of HCl, the same below), and the gained s...

Embodiment 3

[0056] (1) Beat hot-dip galvanizing waste hydrochloric acid with a zinc content of 6640ppm into the mixing tank, add excess iron sheet, stir for 30 minutes, and then filter through a 1300-mesh filter cloth press to feed the three-effect evaporation.

[0057] (2) When the liquid-solid-liquid ratio (volume ratio) of the evaporated material reaches 25%, start discharging to the crystallization kettle, and the crystallization kettle is covered with cooling water.

[0058] (3) When the feed liquid temperature in the crystallization tank was down to 32°C, it began to discharge to the centrifuge, and the primary crystallization and mother liquor of ferrous chloride were obtained. After testing, the zinc content of the primary crystallization was 1867ppm, and the zinc content of the mother liquor was 1867ppm. 21290ppm.

[0059] (4) the primary crystallization in step (3) is dissolved in 8.90% evaporative condensed water with an acid content (in terms of HCl, the same below), and the g...

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Abstract

The invention discloses a process method for treating hot-dip galvanizing waste hydrochloric acid, wherein the process method comprises the steps: pumping pretreated hot-dip galvanizing waste hydrochloric acid subjected to reduction and impurity removal into a triple-effect evaporation system for evaporation and concentration, cooling, and centrifugally filtering to obtain solid ferrous chloride and mother liquor. If the zinc content in the solid ferrous chloride does not exceed the control index, the solid ferrous chloride is used for producing a water treatment agent ferric trichloride product meeting the national standard requirement, otherwise, the solid ferrous chloride is dissolved with dilute acid water generated through evaporation and concentration and then recrystallized to obtain solid ferrous chloride with the zinc content meeting the control index, and then the water treatment agent ferric trichloride product meeting the national standard requirement is produced. Accordingto the technical scheme, the process is simple, the operation danger coefficient is low, secondary pollution is avoided, a new way is provided for resource utilization of the hot-dip galvanizing waste hydrochloric acid, the environmental protection pressure is effectively reduced, and meanwhile the economic benefits of enterprises are increased.

Description

technical field [0001] The invention belongs to the technical field of industrial waste resource treatment, and in particular relates to a process method for recycling hot-dip galvanizing waste hydrochloric acid. Background technique [0002] Hot-dip galvanizing is also called hot-dip galvanizing or hot-dip galvanizing. Hot-dip galvanizing products have the advantages of good corrosion resistance, high cost performance, long service life, large market capacity, low cost, and 100% recycling. It is a kind of Commonly used metal anti-corrosion methods, the principle of hot-dip galvanizing is to clean steel, iron and other parts to be plated, and then treat them with solvents, then dry them and immerse them in molten zinc liquid at about 430 ° C to make the parts to be plated The main process of hot-dip galvanizing is: alkali washing and degreasing→water washing→pickling and rust removal→water washing→coating flux→hot-dip galvanizing→water cooling→ passivation. [0003] The ac...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G49/10C02F1/52
CPCC01G49/10C02F1/5245C01P2006/80
Inventor 丁德才周小江杨东奎朱浩王权永樊文星
Owner 3R ENVIRONMENTAL TECH CO LTD
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