Fractional precipitation method for extraction of aluminum, silicon, iron and calcium elements in fly ash

A step-by-step precipitation and fly ash technology, applied in the field of aluminum extraction, can solve the problems of neglected extraction, low resource utilization, secondary environmental pollution, etc., and achieve the effects of simple and easy process, small investment and simple equipment

Inactive Publication Date: 2014-01-01
GUIYANG AL-MG DESIGN & RES INST
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  • Abstract
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  • Application Information

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Problems solved by technology

[0006] The purpose of the present invention is to provide a step-by-step precipitation method for extracting aluminum, silicon, iron and calcium elements from fly ash, so as to realize comprehensive high-value utilization of fly ash and to overcome the low utilization rate of resources existing in the prior art , causing secondary pollution to the environment, or neglecting the extraction of silicon, iron, calcium and other elements

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  • Fractional precipitation method for extraction of aluminum, silicon, iron and calcium elements in fly ash

Examples

Experimental program
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Effect test

Embodiment 1

[0028] (1) Grind the fly ash of a certain place (see Table 1 for chemical composition) to 200-400 mesh, and activate it by roasting at 800°C for 2 hours. Mix 1 kg of roasted fly ash with 1.8 kg of concentrated hydrochloric acid with a mass fraction of about 35%, react at 90°C for 1.5 hours, and filter to obtain filter residue and filtrate. The filter residue was washed and further processed to obtain white carbon black, and the extraction rate of silicon was calculated to be 95%.

[0029] (2) Adjust the pH value of the filtrate obtained in step (1) to 3.2. After precipitation and filtration, the filter residue and filtrate are obtained. The filter residue is washed and dried at 100°C to obtain iron oxide yellow. Iron oxide yellow is burned at 260°C Iron oxide red was obtained, and the extraction rate of iron was calculated to be 73%.

[0030] (3) Adjust the pH value of the filtrate obtained in step (2) to 5.1. After precipitation and filtration, the filter residue and filtrat...

Embodiment 2

[0035] (1) Grind the fly ash of a certain place whose chemical composition is shown in Table 1 to 200-400 mesh, and activate it by roasting at 800°C for 1 hour. Mix 1 kg of roasted 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 filtrate. The filter residue was washed and further processed to obtain white carbon black, and the extraction rate of silicon was calculated to be 96%.

[0036] (2) Adjust the pH value of the filtrate obtained in step (1) to 2.2. After precipitation and filtration, the filter residue and filtrate are obtained. The filter residue is washed and dried at 100°C to obtain iron oxide yellow. Iron oxide yellow is burned at 260°C Iron oxide red was obtained, and the extraction rate of iron was calculated to be 53%.

[0037] (3) Adjust the pH value of the filtrate obtained in step (2) to 4.4. After precipitation and filtration, the filter residue and fi...

Embodiment 3

[0040] (1) Grind the fly ash of a place whose chemical composition is shown in Table 1 to 200-400 mesh, and activate it by roasting at 900°C for 3 hours. Mix 1 kg of roasted 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 filtrate. The filter residue was washed and further processed to obtain white carbon black, and the extraction rate of silicon was calculated to be 97%.

[0041] (2) Adjust the pH value of the filtrate obtained in step (1) to 3.5. After precipitation and filtration, the filter residue and filtrate are obtained. The filter residue is washed and dried at 100°C to obtain iron oxide yellow. Iron oxide yellow is burned at 260°C Iron oxide red was obtained, and the extraction rate of iron was calculated to be 78%.

[0042] (3) Adjust the pH value of the filtrate obtained in step (2) to 5.1. After precipitation and filtration, the filter residue and filtrate a...

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Abstract

The invention discloses a fractional precipitation method for extraction of aluminum, silicon, iron and calcium elements in fly ash, and the method comprises (1) the fly ash activated by roasting is leached by hydrochloric acid, and then filtered to obtain filter residue and filtrate, and the filter residue is further processed to obtain white carbon black; (2) the pH value of the filtrate obtained by the step (1) is adjusted to 1.5 - 3.5, then filter residue and filtrate are obtained by precipitation and filtering, and an iron compound is obtained by washing and drying of the filter residue; (3) the pH value of the filtrate obtained by the step (2) is adjusted to 3.8 - 5.2, then filter residue and filtrate are obtained by precipitation and filtering, and aluminum hydroxide is obtained by washing and drying of the filter residue, and then metallurgical grade alumina is obtained by further calcinations; and (4) calcium chloride dihydrate is obtained by evaporating of the filtrate obtained by the step (3), and anhydrous calcium chloride is obtained by further calcinations. Through use of the method, fractional extraction of the aluminum, silicon, iron and calcium elements in the fly ash can be realized, and the extraction rates are more than 70%. At the same time, the method is simple in process and low in cost.

Description

technical field [0001] The invention belongs to the field of fine and high-value utilization of fly ash, in particular to a step-by-step precipitation method for extracting aluminum, silicon, iron and calcium from fly ash. 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. , with a cumulative stockpiling capacity of more than 2.5 billion tons, covering an area of ​​50,000 hm 2 above. 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 an important subject to be studied and solved in our country for many years. [0003] At present, fly ash has been used in many fields such as c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G49/06C01F11/24C01F7/02C01B33/12
Inventor 马家玉
Owner GUIYANG AL-MG DESIGN & RES INST
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