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A treatment method for circulating fluidized bed fly ash

The technology of a circulating fluidized bed and a treatment method is applied in the field of high-value utilization of fly ash, which can solve the problems of difficulty in generating economic benefits, low resource utilization rate, secondary pollution, etc., and achieve comprehensive high-value utilization and investment. small, harm-reducing effect

Active Publication Date: 2017-09-12
GUIYANG AL-MG DESIGN & RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Most reported in the literature is the addition of co-solvents (such as NH 4 F and CaF), but the dissolution rate is still relatively low, only 35-45%, the resource utilization rate is low, and the fluorine element that pollutes the environment is added, causing secondary pollution.
In short, the current high-value utilization of fly ash only focuses on the extraction of aluminum, while ignoring the extraction of silicon, iron and other elements, it is difficult to produce economic benefits

Method used

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  • A treatment method for circulating fluidized bed fly ash

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] (1) Grind the fly ash in a circulating fluidized bed (see Table 1 for chemical composition) to 200 mesh. Take 1 kilogram of ground coal ash and mix with 1.8 kilograms of concentrated hydrochloric acid with a mass fraction of about 35%, react for 1.5 hours, and filter to obtain filter residue and leaching liquid. The filter residue was reversely washed with water and further processed to obtain white carbon black. According to calculations, the extraction rate of silicon was 97%.

[0028] (2) Adjust the pH of the extract with ammonia water to 3.2, precipitate at 50°C for 3 hours and filter with a filter to obtain filter residue and filtrate. The filter residue is washed with water and dried at 100°C to obtain iron oxide yellow. Iron oxide yellow is burned at 260°C to obtain iron oxide red, and the extraction rate of iron is 78%.

[0029] (3) Adjust the pH of the filtrate after iron extraction with ammonia water to be 5.1. After precipitation at 50°C for 3 hours, filter with ...

Embodiment 2

[0034] (1) Grind the circulating fluidized bed fly ash of a certain place with the chemical composition shown in Table 1 to 250 mesh. Take 1 kg of ground coal ash and mix with 1.5 kg of concentrated hydrochloric acid with a mass fraction of about 34%, react at 100°C for 1 hour, and filter to obtain filter residue and leaching liquid. The filter residue was reversely washed with water and further processed to obtain white carbon black. According to calculations, the extraction rate of silicon was 96%.

[0035] (2) Adjust the pH of the leaching solution to 2.2 with ammonia water, and filter it with a filter after 3 hours of precipitation at 50°C to obtain filter residue and filtrate. The filter residue is washed and dried at 100°C to obtain iron oxide yellow. Iron oxide red is obtained by burning iron yellow at 260°C, and the extraction rate of iron is 55%.

[0036] (3) Adjust the pH value of the filtrate after iron extraction with ammonia to 4.4. After precipitation at 50°C for 3 h...

Embodiment 3

[0039] (1) Grind the circulating fluidized bed fly ash of a certain place with the chemical composition shown in Table 1 to 300 mesh. Take 1 kg of ground coal ash and mix with 2 kg of concentrated hydrochloric acid with a mass fraction of about 36%, react at 150°C for 3 hours, and filter to obtain filter residue and leaching solution. The filter residue was reversely washed with water and further processed to obtain white carbon black. According to calculations, the extraction rate of silicon was 97%.

[0040] (2) Adjust the pH value of the extract with ammonia water to 3.5, precipitate at 50°C for 3 hours and filter with a filter to obtain filter residue and filtrate. The filter residue is washed and dried at 100°C to obtain iron oxide yellow. Iron oxide red is obtained by burning iron yellow at 260°C, and the extraction rate of iron is 81%.

[0041] (3) Adjust the pH value of the filtrate after iron extraction with ammonia water to be 5.1. After precipitating at 50°C for 3 hours...

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Abstract

The invention relates to a treatment method for circulating fluidized bed fly ash, which comprises the steps of dissolving the fly ash from the circulating fluidized bed through hydrochloric acid, and obtaining filter residue and leaching solution after filtering; adjusting the pH value of the leaching solution with ammonia water After precipitation and filtration, the filter residue and filtrate are obtained, and the filter residue is washed and dried to obtain iron compounds; the pH value of the filtrate after iron extraction is adjusted with ammonia water to 3.8-5.2, and the filter residue and filtrate are obtained after precipitation and filtration. The filtrate and filter residue are washed and dried to obtain aluminum hydroxide, which is further calcined to obtain metallurgical grade alumina; the ammonium chloride solution obtained after aluminum extraction is added with magnesium oxide for ammonia distillation and hydrolysis to obtain hydrogen chloride gas, ammonia gas and magnesium oxide. The invention can realize step-by-step extraction of useful elements such as aluminum, silicon, and iron in fly ash, and at the same time, the materials of the invention can be recycled, the process is simple, and the cost is low, which is a high-value utilization of circulating fluidized bed fly ash opened up new avenues.

Description

Technical field [0001] The invention belongs to the field of high-value utilization of fly ash, and particularly relates to a method for extracting useful elements such as aluminum, silicon, iron and the like from circulating fluidized bed fly ash by using a step precipitation method. Background technique [0002] In recent years, the rapid development of my country’s coal-fired power industry has brought about a sharp increase in solid waste and fly ash emissions. By 2007, my country’s annual fly ash emissions had exceeded 200 million tons and were still increasing year by year. , The cumulative stockpile exceeds 2.5 billion tons. The large amount of discharged fly ash not only takes up a lot of land, but also causes serious pollution to soil, water resources and air. Therefore, the comprehensive utilization of fly ash has become a top priority. [0003] At present, fly ash has been used in many fields such as construction and construction. Although the amount of fly ash is large...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/12C01G49/06C01F7/02C01C1/02C01B7/01
Inventor 马家玉
Owner GUIYANG AL-MG DESIGN & RES INST
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