Resource utilization method of half-dry desulfurized fly ash

A semi-dry desulfurization and recycling technology, applied in the field of solid waste recycling, can solve the problems of unstable properties of calcium sulfite, insufficient use of desulfurization ash, prolonging the setting time of cement, etc., to solve the problem of low resource utilization value , high promotion and application value, and broad market application prospects

Active Publication Date: 2014-10-15
武汉钢铁有限公司
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  • Abstract
  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In the process of research on the resource utilization of semi-dry desulfurization ash, due to the unstable properties of calcium sulfite in semi-dry flue gas desulfurization ash, problems such as pyrolysis and prolonged cement setting time are prone to occur in the process of resource utilization, so In recent years, desulfurization enterprises and scientific research institutes have focused on how to improve the oxidation efficiency of calcium sulfite in semi-dry desulfurization ash. The main components of oxidized desulfurization ash are calcium sulfate, calcium carbonate and hydroxide Calcium is currently mainly used to replace gypsum as a raw material for the production of mineral powder or cement. However, this method of utilization does not give full play to the high calcium and high sulfur characteristics of desulfurization ash; moreover, gypsum is relatively cheap and easy to obtain As a raw material, it is of little practical significance to replace gypsum with desulfurization ash

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Take 100g of semi-dry desulfurization ash and use H 2 o 2 is oxidized so that the CaSO 3 Fully converted to CaSO 4 Add water to make the oxidized desulfurized ash into a desulfurized ash slurry, add water at a solid-to-liquid weight ratio of 1:5-7, preferably add 700ml of water, and then fill the desulfurized ash slurry with CO 2 , so that CO 2 and Ca(OH) in desulfurization ash slurry 2 Fully react to form CaCO 3 , where, by CO 2 with Ca(OH) 2 The molar ratio is 1.2~1.5:1 and filled with CO 2 , preferably at a ratio of 1.4:1, and the reaction time is 5-10 minutes, preferably 5 minutes; 4 HCO 3 Add NH at a molar ratio of 1.2 to 1.5:1 to calcium 4 HCO 3 , preferably at a ratio of 1.3:1, and adjust the pH to 7-9, so that the sulfur-containing calcium is fully converted into calcium carbonate precipitation, and the reaction time is 1-2h, preferably 2h; the aforementioned obtained slurry is subjected to solid-liquid separation, and the filtrate is sent to Ammonia...

Embodiment 2

[0028] Take 50g of semi-dry desulfurization ash from a steel plant, after oxidation, add 300ml of water, stir evenly, and then press CO 2 with Ca(OH) 2 The molar ratio is 1.5:1 into CO 2 , after 10 minutes of reaction, according to the molar ratio of ammonium bicarbonate and calcium content (2n) of 1.5:1, add ammonium bicarbonate, and at the same time adjust the pH value of the system with ammonia water, and maintain it at 7-9. After 1 hour of reaction, centrifuge After separation, the supernatant was evaporated and crystallized to obtain ammonium sulfate, and the solid was calcined at 825°C to obtain calcium oxide, and the decomposed CO 2 Gas can be recycled.

[0029] After testing, the conversion rate of calcium in the desulfurization ash reaches 97.6%, the conversion rate of sulfur reaches 97%, the index of ammonium sulfate meets the requirements of the national standard GB535-1995, and the quality of calcium oxide meets the desulfurization requirements of desulfurization...

Embodiment 3

[0031] Take 50g of semi-dry desulfurization ash from a steel plant, after oxidation, add 250ml of water, stir evenly, and then press CO 2 with Ca(OH) 2 The molar ratio is 1.2:1 into CO 2 , after 10 minutes of reaction, according to the molar ratio of ammonium bicarbonate and calcium content (2n) of 1.2:1, add ammonium bicarbonate, and at the same time adjust the pH value of the system with ammonia water, and maintain it at 7-9. After 1 hour of reaction, centrifuge After separation, the supernatant was evaporated and crystallized to obtain ammonium sulfate, and the solid was calcined at 825°C to obtain calcium oxide, and the decomposed CO 2 Gas recycling.

[0032] After testing, the conversion rate of calcium in the desulfurization ash reaches 95.6%, the conversion rate of sulfur reaches 96%, the index of ammonium sulfate meets the requirements of the national standard GB535-1995, and the quality of calcium oxide meets the desulfurization requirements of desulfurization enter...

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Abstract

The invention discloses a resource utilization method of half-dry desulfurized fly ash. The resource utilization method comprises the following steps: (1) the half-dry desulfurized fly ash is oxidized to fully convert CaSO3 into CaSO4; (2) water is added to prepare the oxidized desulfurized fly ash to desulfurized fly ash slurry; and then, CO2 is filled in the desulfurized fly ash slurry, so that the CO2 is fully reacted with Ca(OH)2 in the desulfurized fly ash slurry to generate CaSO3, wherein the CO2 is filled by 1.2-1.5: 1 of the mol ratio of the CO2 to the Ca(OH)2; (3) NH4HCO3 is added by 1.2-1.5: 1 of the ratio of the NH4HCO3 to calcium in the obtained slurry, and the pH is adjusted within 7-9, so that sulfur-contained calcium is fully converted to calcium carbonate precipitate; and (4) the slurry obtained in the step (3) is prepared to a calcium oxide and ammonium sulfate solid. The method fully uses the characteristics of high calcium and high sulfur in the half-dry desulfurized fly ash to convert the desulfurized fly ash into ammonium sulfate and calcium carbonate, so that the conversion rates of a calcium element and a sulfur element respectively reach above 95%, and the resource value of the desulfurized fly ash is fully realized.

Description

technical field [0001] The invention relates to solid waste recycling technology, in particular to a semi-dry desulfurization ash recycling method. Background technique [0002] The semi-dry desulfurization process has been widely used in recent years due to its advantages of small investment, low land occupation, and no waste water generation. The desulfurization ash produced in the semi-dry desulfurization process has not yet been well utilized, and it is mainly stockpiled, which has brought about land occupation and environmental problems. [0003] In the process of research on the resource utilization of semi-dry desulfurization ash, due to the unstable properties of calcium sulfite in semi-dry flue gas desulfurization ash, problems such as pyrolysis and prolonged cement setting time are prone to occur in the process of resource utilization, so In recent years, desulfurization enterprises and scientific research institutes have focused on how to improve the oxidation ef...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B09B3/00C01F11/46C01F11/18
Inventor 卢丽君薛改凤朱丽华张垒汤静芳
Owner 武汉钢铁有限公司
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