Process method for extracting aluminum oxide in coal ash of pulverized coal furnace by using acid method

A process method, fly ash technology, applied in the direction of alumina/aluminum hydroxide, etc., can solve the problems of difficult extraction of alumina, and achieve the effect of easy roasting operation, industrial production, and low equipment requirements

Inactive Publication Date: 2017-07-21
XIAN AEROSPACE PROPULSION TESTING TECHN INST
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Problems solved by technology

[0005] In order to solve the problem that the traditional acid-dissolution method or alkali-dissolution method is not easy to extract alumina in pulverized coal furnace fly ash, the present invention provides a process for extracting alumina in pulverized coal furnace fly ash by acid method. Ammonium sulfate roasting is used to break the Si-O-Al bond in the fly ash of the pulverized coal furnace, and the alumina in the fly ash is activated; the alumina is leached by hydrochloric acid; the solubility of aluminum chloride in different concentrations of hydrochloric acid is different, The method of passing hydrogen chloride gas is used to realize the one-step completion of the crystallization of aluminum chloride hexahydrate and the removal of impurity ions; all materials can be recycled after treatment

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  • Process method for extracting aluminum oxide in coal ash of pulverized coal furnace by using acid method

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Effect test

Embodiment 1

[0037] 2.00kg fly ash (containing 52.00% Al 2 o 3 , 37.27% SiO 2 ) and 4.04kg ammonium sulfate (Al 2 o 3 Mixed evenly with ammonium sulfate (molar ratio 1:3), roasted in a roasting furnace at 300°C for 0.5h, then raised the temperature to 600°C for 0.5h to obtain fly ash clinker. Take 2.00kg of clinker, add 6.00kg of 20% hydrochloric acid solution to the 2.00kg of clinker, carry out dissolution reaction at 90°C for 0.5h, filter to achieve solid-liquid separation, and wash the filter residue with 1.00kg of water. Take 8.60kg of filtrate and feed it with HCl gas under stirring, control the solution temperature to be 20°C, stop the ventilation when the concentration of hydrochloric acid in the solution reaches 36%, leave it to age for 1h, filter and separate, and wash with 2.00kg of concentrated hydrochloric acid (37%) Aluminum chloride hexahydrate crystals were obtained after crystallization, and the crystals were calcined at 900°C for 0.5h to obtain 0.88kg of alumina, with ...

Embodiment 2

[0039] 2.00kg fly ash (containing 52.00% Al 2 o 3 , 37.27% SiO 2 ) and 6.06kg ammonium sulfate (Al 2 o 3 Mix evenly with ammonium sulfate (mole ratio 1:6), roast in a roasting furnace at 410°C for 1.5h, then raise the temperature to 750°C and continue calcining for 2h to obtain fly ash clinker. Take 2.00kg of clinker, add 14.00kg of 30% hydrochloric acid solution to the 2.00kg of clinker, carry out dissolution reaction at 140°C for 1.5h, filter and separate, and wash the filter residue with 2.00kg of water. Take 17.60kg of filtrate and feed it with HCl gas under stirring, control the solution temperature to be 30°C, when the concentration of hydrochloric acid in the solution reaches 38%, stop the aeration, leave it to age for 5 hours, filter and separate, wash with 3kg of concentrated hydrochloric acid (37%) Aluminum chloride hexahydrate crystals were obtained, and the crystals were calcined at 1100° C. for 1.5 h to obtain 0.93 kg of alumina, with an extraction rate of 89....

Embodiment 3

[0041] 2.00kg fly ash (containing Al 2 o 3 52.00%, SiO 2 37.27%) and 8.08kg ammonium sulfate (Al 2 o 3 Mix evenly with ammonium sulfate (molar ratio 1:8), roast in a roaster at 500°C for 3h, then raise the temperature to 900°C and continue calcining for 5h to obtain fly ash clinker. Take 2.00kg of clinker, add 20.00kg of 35% hydrochloric acid solution to the 2.00kg of clinker, carry out dissolution reaction at 150°C for 3 hours, filter and separate, and wash the filter residue with 4.00kg of water. Take 25.6kg of filtrate and feed it with HCl gas under stirring, control the solution temperature to 45°C, stop ventilation when the concentration of hydrochloric acid in the solution reaches 40%, leave it to age for 10 hours, filter and separate, wash with 6kg of concentrated hydrochloric acid (37%) Aluminum chloride hexahydrate crystals were obtained, and the crystals were calcined at 1200° C. for 3 hours to obtain 0.94 kg of alumina, with an extraction rate of 90.4%. The chem...

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Abstract

The invention relates to a process method for extracting aluminum oxide in coal ash of a pulverized coal furnace by using an acid method. The process method comprises the following steps; adding ammonium sulfate into the coal ash of the pulverized coal furnace for activating, and performing the high-temperature calcination to obtain activated coal ash clinker, adding hydrochloric acid, heating and dissolving out, to obtain aluminum chloride digesting liquor; pumping hydrogen chloride gas into the digesting liquor for crystallizing, performing the solid-liquid separation and washing to obtain high-purity aluminum chloride hexahydrate crystal and waste acid solution, calcining the crystal to generate metallurgy-level aluminum oxide; adding inorganic salt chloride, such as calcium chloride or magnesium chloride, into the waste acid, heating, extractive-distilling and recycling the hydrochloric acid and the hydrogen chloride gas for the dissolving out and crystallization working procedures, performing the absorption-crystallization to tail gas generated in the roasting-calcining activation to generate ammonium sulfate, and realizing the cyclic utilization of materials, wherein the obtained solid residue with abundant silicon dioxide can be used for generating white carbon black or the materials for building. The process method is capable of realizing the reduced recycling of the coal ash of the pulverized coal furnace, and realizing the full cyclic utilization of the materials. The purity of the obtained aluminum oxide product is the first level, the quality of the metallurgy-level aluminum oxide is standard, and the extraction efficiency is up to 84.6%-90.4%.

Description

technical field [0001] The invention relates to the technical field of pulverized coal furnace fly ash treatment, in particular to a process for extracting alumina from pulverized coal furnace fly ash by an acid method. Background technique [0002] Fly ash is a solid waste produced after coal combustion, with huge emissions. According to statistics, my country's annual emissions in 2015 were as high as 620 million tons. It is estimated that by 2020, the total accumulation of fly ash in my country will reach more than 3 billion tons. Issues such as air and water pollution, land desertification and alkalization caused by land occupation and loss have had a great impact on human beings and the environment. Alumina is the main component of fly ash with refined utilization value, especially the high-alumina fly ash produced by coal combustion in Shaanxi, Shanxi, Inner Mongolia and other provinces in my country, the average mass fraction of alumina is more than 40%, which is equiv...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02
CPCC01F7/02
Inventor 徐涛兰海平杨超李宁季增宝张建宁张瑞华
Owner XIAN AEROSPACE PROPULSION TESTING TECHN INST
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