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A method for recycling and treating waste liquid produced by combining steel slag with desulfurization and denitrification process as absorbent

A technology for desulfurization, denitrification, and waste liquid recovery, which is applied in the direction of gaseous effluent wastewater treatment, filtration treatment, multi-stage water treatment, etc., and can solve problems such as difficult to handle, difficult to obtain pure nitrate products, and complex metallurgical slag components. Achieve good economic benefits and broad industrial application prospects

Active Publication Date: 2020-11-03
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] However, this treatment process will produce a large amount of desulfurization and denitrification waste liquid. Due to the complex composition of metallurgical slag, there are many types of anions and cations in the combined desulfurization and denitrification waste liquid, and it also contains NO 3 - , NO 2 - , SO 4 2- , SO 3 2- 、HSO 4 - 、HSO 3 - Isoanions and Mg 2+ , Ca 2+ , Mn 2+ or Fe 3+ Cationic, difficult to handle
And the NO 3 - and NO 2 - mixed together, and NO 2 - It is difficult to be completely oxidized, so it is difficult to obtain pure nitrate products when the waste liquid is subsequently recycled

Method used

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preparation example Construction

[0047] The specific embodiment part of the present invention provides a method for recycling and treating waste liquid produced by using steel slag as an absorbent combined with desulfurization and denitrification process. The preparation method includes the following steps:

[0048] (1) Using steel slag as an absorbent in conjunction with the waste liquid produced by the desulfurization and denitrification process for solid-liquid separation;

[0049] (2) adding unslaked lime and / or slaked lime to the liquid obtained after the solid-liquid separation in step (1) to adjust the pH to remove impurities, and filter after the precipitation is complete;

[0050] (3) the pH of the filtrate obtained in step (2) is adjusted to 5-7, and then oxidized by a micro-nano bubble generating device;

[0051] (4) evaporating and concentrating the liquid obtained after oxidation in step (3) to crystallize, filter, and dry to obtain a calcium nitrate product.

[0052] Wherein, the specific opera...

Embodiment 1

[0055] In this embodiment, the steel slag slurry absorbs SO 2 and NO x The content of steel slag in the waste liquid generated later is 15wt%, pH=6, and total salt concentration is 30wt%.

[0056] (1) the waste liquid is filtered to remove solid impurities;

[0057] (2) The filtrate obtained in step (1) is adjusted to pH 9 with unslaked lime, and precipitation removes NO 3 - , NO 2 - and Ca 2+ other impurity ions, filtered to obtain the filtrate;

[0058] (3) the filtrate obtained by step (2) is added with nitric acid to adjust the pH to be 6, then the filtrate in the filtrate tank is passed into from the water inlet of the micro-nano bubble generating device, and the amount of feed per hour is controlled to be 1 / of the total amount of filtrate 2. At the same time, add hydrogen peroxide with 10% of the total mass of the filtrate from the water inlet, and introduce air (21% oxygen content) from the inlet. After 3 hours of aeration in the generating device, it enters th...

Embodiment 2

[0061] In this embodiment, the steel slag slurry absorbs SO 2 and NO x The content of steel slag in the waste liquid generated later is 10wt%, pH=5.5, and total salt concentration is 40wt%.

[0062] (1) the waste liquid is filtered to remove solid impurities;

[0063] (2) The filtrate obtained in step (1) is adjusted to pH 10.8 with CaO saturated solution, and the precipitation removes NO 3 - , NO 2 - and Ca 2+ other impurity ions, filtered to obtain the filtrate;

[0064] (3) the filtrate obtained by step (2) is added with nitric acid to adjust pH=6.5, then the filtrate in the filtrate tank is passed into from the water inlet of the micro-nano bubble generating device, and the amount of feed per hour is controlled to be 0.8 of the total amount of filtrate, Add the hydrogen peroxide of filtrate gross mass 5% from water inlet simultaneously, pass into air and oxygen mixed gas (oxygen content 30%) from inlet, the volume mass ratio of intake and liquid intake is 30L / t, and f...

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Abstract

The invention provides a method for recycling and processing a waste liquid produced by a combined desulfurization and denitrification technology using steel slag as an absorbent. Firstly, solid-liquid separation is conducted on the waste liquid which absorbs SO2 and NOx and reaches a total salt concentration; then, after the separation, quick lime and / or slaked lime are / is added into the obtained liquid phase to adjust pH, and after filtration, the pH of the filtrate is adjusted to 5-7; the filtrate is introduced into a micro-nano bubble generator, nitrite in the filtrate is completely oxidized to nitrate, and by subsequent operations such as evaporation, concentration, crystallization, filtration, desiccation and the like, calcium nitrate products are obtained. The method is a subsequent process of a metallurgy-slug combined desulfurization and denitrification technology, and solves the problem that secondary pollution is caused by the waste liquid which is produced by the metallurgy-slug combined desulfurization and denitrification technology, the nitrite is completely converted into the nitrate, the complete utilization of the N element in the waste liquid is achieved, and the pure calcium nitrate products are obtained. Meanwhile, the calcium nitrate products reach national standards of industrial calcium nitrate and agricultural calcium nitrate, and have good application prospects.

Description

technical field [0001] The invention relates to the fields of environmental protection and waste water recycling, in particular to a method for recycling and treating waste liquid produced by using steel slag as an absorbent combined with a desulfurization and denitrification process. Background technique [0002] In recent years, with the improvement of my country's industrialization level and rapid economic growth, air pollution has become increasingly serious. SO 2 and NO x emissions are increasing. Domestic for containing SO 2 and NO x The gas needs to be treated and discharged up to standard. [0003] In the desulfurization and denitrification methods disclosed in the prior art, the process involving ammonia has problems such as long process, ammonia leakage, and the need for catalysts; while the dry desulfurization and denitrification cost is high and the removal rate is low; the use of nano-scale materials for desulfurization and denitrification, There are proble...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C02F9/04C01F11/36C01F11/44
CPCC01F11/36C01F11/44C02F1/001C02F1/048C02F1/52C02F1/66C02F1/72C02F1/727C02F1/74C02F9/00C02F2103/18C02F2301/08
Inventor 王晨晔陈艳李会泉王兴瑞孟子衡
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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