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Method for processing fly ash used for circulating fluidized bed

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, low dissolution rate, etc. Simple and easy effects

Active Publication Date: 2015-03-25
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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  • Method for processing fly ash used for circulating fluidized bed

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] (1) Grind the fly ash of a circulating fluidized bed in a certain place (see Table 1 for the chemical composition) to 200 mesh. Mix 1 kg of ground fly ash with 1.8 kg of concentrated hydrochloric acid with a mass fraction of about 35%, react for 1.5 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, and the extraction rate of silicon was calculated to be 97%.

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

[0029] (3) Use ammonia water to adjust the pH value of the filtrate after iron extraction to 5.1,...

Embodiment 2

[0034] (1) Grind a circulating fluidized bed fly ash whose chemical composition is shown in Table 1 to 250 mesh. Mix 1 kg of ground fly ash 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 solution. The filter residue was reversely washed with water, and further processed to obtain white carbon black, and the extraction rate of silicon was calculated to be 96%.

[0035] (2) Use ammonia water to adjust the pH value of the leaching solution to 2.2, and filter it with a filter after settling at 50°C for 3 hours to obtain the filter residue and filtrate. The filter residue is washed and dried at 100°C to obtain iron oxide yellow, which is oxidized Iron yellow was burned at 260°C to obtain iron oxide red, and the extraction rate of iron was calculated to be 55%.

[0036] (3) Use ammonia water to adjust the pH value of the filtrate after iron extraction to 4.4, and filter it ...

Embodiment 3

[0039] (1) Grind a circulating fluidized bed fly ash whose chemical composition is shown in Table 1 to 300 mesh. Mix 1 kg of ground fly ash 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, and the extraction rate of silicon was calculated to be 97%.

[0040] (2) Use ammonia water to adjust the pH value of the leaching solution to 3.5, and filter it with a filter after settling at 50°C for 3 hours to obtain the filter residue and filtrate. The filter residue is washed and dried at 100°C to obtain iron oxide yellow, which is oxidized Iron yellow was burned at 260°C to obtain iron oxide red, and the extraction rate of iron was calculated to be 81%.

[0041] (3) Use ammonia water to adjust the pH value of the filtrate to 5.1, precipitate at 50°C for 3 hours and t...

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Abstract

The invention relates to a method for processing fly ash used for a circulating fluidized bed, which comprises the following steps: dissolving fly ash from the circulating fluidized bed out by hydrochloric acid, filtering to obtain filter residue and a leaching liquid; adjusting pH value of the leaching liquid to 1.5-3.5 by ammoniacal liquor, deposing, filtering to obtain the filter residue and a filtrate, washing filter residue, drying to obtain a compound of iron; adjusting the pH value of the filtrate after extracting iron to 3.8-5.2 by the ammoniacal liquor, deposing, filtering to obtain the filter residue and the filtrate, washing filter residue, drying to obtain aluminium hydroxide, further calcining to obtain metallurgy alumina; adding magnesium oxide in an ammonium chloride solution after extracting aluminium and performing ammonia distilling and hydrolysis reactions to obtain hydrogen chloride gas, ammonia gas and magnesium oxide. According to the invention, stepwise extraction of useful elements such as aluminium, silicon and iron in fly ash can be realized, cycle utilization of the materials can be realized, process is simple, cost is low, and the method opens new approach for high value utilization of fly ash from the circulating fluidized bed.

Description

technical field [0001] The invention belongs to the field of high-value utilization of fly ash, in particular to a method for extracting useful elements such as aluminum, silicon and iron from circulating fluidized bed fly ash by using a step-by-step precipitation method. Background technique [0002] In recent years, the rapid development of my country's coal power industry has brought about a sharp increase in the discharge of solid waste fly ash. By 2007, the annual discharge of fly ash in my country has exceeded 200 million tons, and it is still increasing year by year. , and the cumulative stockpiles exceed 2.5 billion tons. A large amount of fly ash not only occupies a large amount 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 it is used in a large amount,...

Claims

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Application Information

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