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Treatment process for preparing baking soda from desulfurization ash

A treatment process and desulfurization ash technology, applied in the direction of sulfate/bisulfate preparation, carbonate preparation, bicarbonate preparation, etc., can solve the problems of sulfuric acid consumption, soil, groundwater pollution, and the purity of baking soda and sodium sulfate products Guarantee and other issues, to achieve the effect of high recovery rate and guaranteed purity

Active Publication Date: 2022-07-15
BEIJING CYCLE COLUMBUS ENVIRONMENTAL SCI & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Desulfurization ash is easily soluble in water. When it is piled up or landfilled, it will seep into the soil and cause serious pollution to soil and groundwater.
[0003] CN11207363A has proposed a kind of resource utilization method of baking soda desulfurization ash, after using pure water to dissolve desulfurization ash, clarify solid-liquid separation, add sodium bicarbonate crystal in clarified liquid, carry out evaporation and concentration to obtain bicarbonate product, but this technology does not provide And the removal technology of impurity ions in desulfurization ash, the purity of the obtained baking soda and sodium sulfate products cannot be guaranteed
[0004] CN109850922A proposes a method and device for resource utilization of baking soda desulfurization ash. On the basis of desulfurization ash dissolution and filtration, it proposes to use milk of lime and carbon dioxide and oxygen to convert carbonate in the solution into bicarbonate to improve The purity of baking soda is improved, and the by-product calcium sulfate is recovered, but the added value of calcium sulfate is lower than that of baking soda
And due to the existence of organic matter and fluoride ions in the desulfurization ash, the purity of the recovered calcium sulfate cannot be guaranteed
[0005] CN111701419A has proposed a kind of sodium-alkali dry desulfurization ash recycling method, at first desulfurization ash is mixed and dissolved with evaporative condensed water, then fed into compressed air to oxidize sodium sulfite to sodium sulfate, then add sulfuric acid solution to dissolve sodium bicarbonate and sodium carbonate It is all converted into sodium sulfate, and then the impurities are filtered out, and then through the double decomposition reaction, sodium sulfate is converted into baking soda and ammonium sulfate by adding ammonium bicarbonate, but this technology first converts sodium carbonate and sodium bicarbonate into Sodium sulfate releases a large amount of carbon dioxide, which consumes a large amount of sulfuric acid, and then converts sodium sulfate back to sodium bicarbonate by adding ammonium bicarbonate (first remove carbonate and bicarbonate, and then replenish bicarbonate, resulting in waste of resources ), repeated operations, resulting in waste of chemicals and resources, failing to truly realize the resource utilization of waste
[0006] CN110697738A proposes a resource-recycling method for baking soda dry desulfurization ash, which recycles desulfurization ash into sodium sulfate solid, but the added value of sodium sulfate is lower than that of baking soda for enterprises, and cannot be reused within the enterprise

Method used

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  • Treatment process for preparing baking soda from desulfurization ash
  • Treatment process for preparing baking soda from desulfurization ash

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] The composition analysis of desulfurization ash in a coal coking enterprise is shown in Table 1.

[0043] Table 1 Analysis results of the mass percentage of desulfurized ash components

[0044] Element proportion NaCl 7.618% Na 2 SO 3

0.512% Na 2 SO 4

61.419% Na 2 CO 3、 NaHCO 3

24.66~31.11% NaF 0.612% Sodium nitrate 0.809% COD (TOC) 1.042%（0.137%） Other substances such as water insolubles 0~3.82%

[0045] Step 1: Under the constant temperature condition of 30°C, dissolve and filter according to the ratio of mass desulfurization ash: water = 1:4 to remove insoluble solid impurities to obtain a filtrate.

[0046] Step 2: Add 10g / L powdered activated carbon to the filtrate, adsorb for 1h, precipitate for 30min, filter, and the filtrate is light yellow and transparent.

[0047] Step 3: According to the molar ratio O 2 :SO 3 2- =3:1 Bubble O into the filtrate after adsorption 2 , SO was ...

Embodiment 2

[0053] The composition analysis of desulfurization ash in a coal coking enterprise is shown in Table 1.

[0054] Step 1: Under the constant temperature condition of 30°C, dissolve and filter according to the ratio of mass desulfurization ash: water = 1:3, remove insoluble solid impurities, and obtain a filtrate that is dark yellow.

[0055] Step 2: Pass the filtrate through the resin for adsorbing organic matter at a flow rate of 3BV / h, and the effluent is colorless and transparent.

[0056] Step 3: According to the molar ratio O 2 :SO 3 2- =2:1 Bubble O into the filtrate after adsorption 2 , SO was detected in water 3 2- After it has been completely oxidized, a sufficient amount of CO is introduced 2 , until pH≤8.3, at which time there is a large amount of NaHCO 3 Precipitate.

[0057] Step 4: Add molar ratio Al:F to the solution separated in step 3 - =3:1 aluminum sulfate reaction for 1h, precipitation for 30min, after detection of F in the filtrate - From 702.24 m...

Embodiment 3

[0062] The composition of desulfurization ash in a coal-electricity-aluminum enterprise is shown in Table 2

[0063] Table 2 Analysis results of the mass percentage of desulfurized ash components

[0064] Element proportion NaCl 2.31% Na 2 SO 3

13.52% Na 2 SO 4

70.74% NaF 0.4639% Sodium carbonate 13.1452% Sodium nitrate 0.4232% Ca 0.1093% K, Fe, Al, Pb, Zn, Mo trace COD 0.2483% Oil 0.03% Water insoluble matter 0.005%

[0065] Step 1: Under the constant temperature of 30 °C, wash and filter according to the ratio of quality desulfurization ash: saturated sodium sulfate solution = 1:3, and the filter cake is dried and then filtered. 2 SO 4 The content accounts for 99.18%, and the composition analysis of the filtrate after leaching is shown in Table 3.

[0066] Table 3 Composition analysis results of the elution filtrate

[0067] project index SO 4 2- (mg / L)

1...

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Abstract

The invention discloses a treatment process for preparing baking soda from desulfurized fly ash and belongs to the technical field of desulfurized fly ash treatment. According to one technical scheme, the method comprises the following steps: (1) dissolving and filtering; (2) removing organic matters; (3) aerating and removing impurities; (4) removing fluorine; (5) salt separation; (6) preparing baking soda from sodium sulfate; and (7) treatment of crystallization mother liquor. According to the other technical scheme, the step (1) is replaced by a saturated Na2SO4 solution for leaching and filtering. According to the method, firstly, a large amount of sodium bicarbonate in the system is transferred out, then sodium sulfate in the system is converted into baking soda, the use amount of a conversion agent for converting sodium sulfate into baking soda is reduced, and resource recycling of desulfurized fly ash is fully achieved.

Description

technical field [0001] The invention belongs to the technical field of desulfurization ash treatment, and relates to a treatment process for desulfurization ash to make baking soda. Background technique [0002] Flue gas desulfurization ash uses sodium carbonate and sodium bicarbonate as desulfurization agents, and is a first-class hazardous solid waste generated in the flue gas desulfurization process of coke ovens. The main components are sodium carbonate, sodium bicarbonate and sodium sulfate, etc., and contain a certain proportion of impurity ions. In general, Na in desulfurized ash 2 SO 3 The content of NaF is 10%~20%, NaF accounts for 0.5%~1%, NaF 2 CO 3 It accounts for 5% to 15%, and also contains a small amount of insoluble solid impurities, and the rest are sodium bicarbonate and sodium sulfate. Desulfurized ash is easily soluble in water. When it is piled up or disposed of in landfill, it will infiltrate into the soil after being dripped with rainwater, causin...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01D7/02C01D7/10C01D5/04C01D5/16C01C1/244C05C3/00
CPCC01D7/02C01D7/10C01D5/04C01D5/16C01C1/244C05C3/00C01P2006/80
Inventor 李保震李雅王美娇赵宇靖韦凤密王天慧
Owner BEIJING CYCLE COLUMBUS ENVIRONMENTAL SCI & TECH