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Method for producing alumina by curing fly ash with sulphuric acid

A technology of fly ash and aluminum sulfate, applied in the direction of chemical instruments and methods, silicon oxide, silicon dioxide, etc., can solve the problems of high equipment material requirements, high cost, low aluminum leaching rate, etc., to achieve equipment material resolution, equipment The effect of easy material and high aluminum recovery rate

Active Publication Date: 2017-03-08
BEIJING GENERAL RES INST OF MINING & METALLURGY
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

However, since the aluminum in fly ash mainly exists in the form of mullite or other aluminosilicates with low chemical activity, direct acid leaching is difficult, and high-temperature leaching with concentrated sulfuric acid or pressurized hydrochloric acid leaching or fluoride-assisted leaching is required. Strong performance, high equipment material requirements, high cost, low aluminum leaching rate, high energy consumption and high cost of alumina production

Method used

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  • Method for producing alumina by curing fly ash with sulphuric acid

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Effect test

Embodiment 1

[0033] Mix the fly ash of the circulating fluidized bed boiler with concentrated sulfuric acid with a concentration of 93%, and then mature it at 200°C for 2 hours to obtain sulfated clinker. 2 SO 4 Al with fly ash 2 o 3 The molar ratio is 3.5:1, the clinker is leached with water, the leaching solution is evaporated and concentrated, crystallized, dried and dehydrated to obtain aluminum sulfate, and the aluminum sulfate is reduced and roasted to obtain crude alumina. The sodium aluminate solution is obtained by lower leaching, and the sodium aluminate solution is sorted and calcined to obtain metallurgical grade alumina.

Embodiment 2

[0035] Mix the fly ash of the circulating fluidized bed boiler with concentrated sulfuric acid with a concentration of 93% and then mature it in the rotary kiln. 2 SO 4 Al with fly ash 2 o 3 The molar ratio is 3.5:1, the residence time of the mixed material in the temperature range of 100-150°C is 1h, and the residence time in the temperature range of 200-250°C is 0.5h to obtain sulfated clinker, the clinker is leached with water, and the leachate is evaporated and concentrated. Crystallization, drying and dehydration to obtain aluminum sulfate, aluminum sulfate is reduced and roasted to obtain crude alumina, crude alumina is leached with 100g / L sodium hydroxide solution at 95°C to obtain sodium aluminate solution, and the sodium aluminate solution is seeded and calcined Metallurgical grade alumina is obtained.

Embodiment 3

[0037] Mix the fly ash of the circulating fluidized bed boiler with concentrated sulfuric acid with a concentration of 93% and then mature it in the rotary kiln. 2 SO 4Al with fly ash 2 o 3 The molar ratio is 3.5:1, the residence time of the mixed material in the temperature range of 100-150°C is 1h, and the residence time in the temperature range of 200-250°C is 0.5h to obtain sulfated clinker, and the aluminum sulfate obtained in Example 2 is used The clinker is leached with the crystallization mother liquor and an appropriate amount of supplementary water. The leaching solution is evaporated and concentrated, crystallized, dried and dehydrated to obtain aluminum sulfate, and the aluminum sulfate is reduced and roasted to obtain crude alumina. The crude alumina is leached at 95°C with 100g / L sodium hydroxide solution A sodium aluminate solution is obtained, and the sodium aluminate solution is sorted and calcined to obtain metallurgical grade alumina.

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Abstract

The invention discloses a method for producing alumina by curing fly ash with sulphuric acid, belonging to the technical field of comprehensive utilization of the fly ash. The method comprises the following steps: uniformly mixing a proper amount of concentrated sulfuric acid and the fly ash, then carrying out curing so as to obtain a sulfated clinker, then leaching the clinker with an aluminum sulfate crystallized mother liquor or water so as to obtain an aluminum sulfate and high-silicon slag, subjecting the aluminum sulfate solution to evaporation, concentration, crystallization, drying and dehydration so as to obtain aluminum sulfate, subjecting obtained aluminum sulfate and a proper amount of a reducing agent to rapid reduction and calcination so as to obtain crude alumina, then treating the crude alumina by adopting a low-temperature Bayer process so as to produce metallurgical-grade alumina, wherein the obtained high-silicon slag can be leached by sodium hydroxide to produce white carbon black or active calcium silicate. The method provided by the invention has the advantages of high aluminum recovery rate, easily-available equipment and materials, good alumina product quality, etc.; and the slag obtained by leaching of aluminum is the high-silicon slag with good alkali-soluble activity, and can be used for further production of a variety of high-value-added silicon products.

Description

technical field [0001] The invention belongs to the comprehensive utilization of fly ash, and relates to a method for producing alumina from fly ash, in particular to a method for producing alumina by adopting a sulfuric acid aging process. Background technique [0002] The coal combustion process produces a large amount of fly ash, except for a small part that is partially utilized for the production of cement building materials, and most of the fly ash is stockpiled, which not only occupies a large amount of land resources, but also seriously pollutes the environment. There are a large amount of high-aluminum coal in my country, and a large amount of high-alumina fly ash is produced during the combustion and power generation process. The aluminum content in the fly ash is as high as 40-60%, which has a high value for extracting aluminum. However, due to the low aluminum-silicon ratio in fly ash, the traditional alumina production process is difficult to adapt to fly ash, a...

Claims

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Application Information

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IPC IPC(8): C01F7/26C01B33/32C01B33/24C01B33/18
CPCC01B33/18C01B33/24C01B33/32C01F7/26
Inventor 蒋开喜蒋训雄汪胜东范艳青李达张登高蒋伟冯林永靳冉公刘巍赵峰白旭阳
Owner BEIJING GENERAL RES INST OF MINING & METALLURGY
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