Method for preparation of aluminum hydroxide by gas-solid technique

A technology of aluminum hydroxide and aluminum oxide, applied in the direction of aluminum oxide/aluminum hydroxide, etc., can solve the problems of long aging time, slow reaction speed, slow pH value control of ammonium aluminum sulfate solution, etc., and achieve easy control of reaction conditions, The effect of fast reaction speed and high conversion rate

Inactive Publication Date: 2014-11-12
NORTH UNITED POWER CO LTD
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Problems solved by technology

[0004] Disclosed in the related patent CN102120596B is a method for preparing aluminum hydroxide by precipitation method. Although the particle size of the obtained aluminum hydroxide is easy to control, the presence of aluminum ammonium sulfate solution requires slow pH value regulation and alkaline titration solution. Need to add surfactants, long aging time, slow reaction speed and other deficiencies, which inhibit industrial mass production

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  • Method for preparation of aluminum hydroxide by gas-solid technique

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Embodiment 1

[0023] Fly ash and ammonium sulfate are uniformly mixed and granulated, dried at 120°C, and roasted at 450°C for 1.5 hours. The ratio of fly ash to ammonium sulfate is expressed by the molar ratio of alumina and ammonium sulfate contained in fly ash. The molar ratio of alumina and ammonium sulfate contained in the fly ash is Al 2 o 3 :(NH 4 ) 2 SO 4 =1:5.3, take 300g of the clinker obtained under the above conditions and add water to dissolve in the autoclave, the dissolution pressure is 0.15Mpa, the dissolution time is 30min, and the dissolution filtrate is filtered and removed at room temperature (25°C) at 10r / min. Stir to obtain aluminum ammonium sulfate crystals with an average particle size of 40 mesh, dry them with hot air at 90°C for 8 minutes, take 50 g of the crystals and place them in a gas-solid reactor, and feed nitrogen gas with a flow rate of 66 L / min and ammonia gas with a flow rate of 40 L / min. , and the temperature of the gas phase is controlled by a gas h...

Embodiment 2

[0025] Fly ash and ammonium sulfate were uniformly mixed and granulated, dried at 120°C, and roasted at 410°C for 2 hours. The proportion of fly ash and ammonium sulfate was expressed by the molar ratio of alumina and ammonium sulfate contained in fly ash. The molar ratio of aluminum oxide and ammonium sulfate contained in the fly ash is Al 2 o 3 :(NH 4 ) 2 SO 4 =1:3.5, take 300g of roasted clinker under the above conditions and add water to dissolve in the autoclave, the dissolution pressure is 0.5Mpa, the dissolution time is 40min, and the dissolution filtrate is filtered and slag-removed at 15°C under 50r / min constant stirring, The average particle size obtained is 60 mesh aluminum ammonium sulfate crystals, dried with 40°C hot air for 20 minutes, 50 g of the crystals are taken and placed in a gas-solid reactor, and the flow rate is 5 L / min of nitrogen, 30 L / min of ammonia, and The temperature of the gas phase is controlled by a gas heater to be 35°C, and the ammonium a...

Embodiment 3

[0027] Fly ash and ammonium sulfate are uniformly mixed and granulated, dried at 120°C, and roasted at 440°C for 2.5 hours. The proportion of fly ash and ammonium sulfate is expressed by the molar ratio of alumina and ammonium sulfate contained in fly ash. The molar ratio of alumina and ammonium sulfate contained in the fly ash is Al 2 o 3 :(NH 4 ) 2 SO 4 =1:3.5 Take 300g of fly ash and ammonium sulfate roasting clinker under the above conditions, add water to dissolve in an autoclave, the dissolution pressure is 1Mpa, and the dissolution time is 1h. Stir to obtain aluminum ammonium sulfate crystals with an average particle size of 80 mesh, dry them with hot air at 65°C for 10 minutes, take 50 g of the crystals and place them in a gas-solid reactor, and feed in flow rates of 20 L / min nitrogen and 10 L / min ammonia. The temperature of the gas phase is controlled by a gas heater to be 40°C, and the aluminum ammonium sulfate crystals react under fluidized conditions. After 5 m...

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Abstract

The invention relates to a method for preparation of aluminum hydroxide by a gas-solid technique. The method includes: mixing fly ash with ammonium sulfate and conducting roasting, taking the roasting product aluminum ammonium sulfate and ammonia gas as raw materials, controlling the gas phase temperature lower than 45DEG C, subjecting solid aluminum ammonium sulfate to gas-solid phase non-catalytic reaction under a fluidization condition for 10s-5min, thus obtaining a solid product, i.e. a mixture of aluminum hydroxide and ammonium sulfate, washing and filtering the mixture to obtain aluminum hydroxide, carrying out evaporative crystallization on the ammonium sulfate in the washing liquid, and then returning the obtained ammonium sulfate to the roasting process, and subjecting the obtained aluminum hydroxide to impurity removal by alkali dissolution, carbonation decomposition or seed precipitation and calcination treatment so as to obtain metallurgical grade alumina. The method provided by the invention utilizes a gas-solid phase non-catalytic reaction process to prepare aluminum hydroxide, and compared with other method, has the advantages of simple production process, fast reaction speed, high conversion rate, easy filtration of product, significantly improved efficiency, and easy realization of large-scale production.

Description

technical field [0001] The invention relates to a method for preparing aluminum hydroxide, in particular to a method for preparing aluminum hydroxide by a gas-solid method. Background technique [0002] The most important ore resource in the production of aluminum hydroxide is bauxite, which is not abundant in my country. According to the current growth rate of aluminum hydroxide production and the waste in the mining and utilization of bauxite, even considering the prospective reserves, the guarantee period of bauxite in my country is very short. Therefore, there is an urgent need for a resource to replace bauxite to ensure the sustainable development of my country's aluminum industry. [0003] The related patent CN102120593B discloses a method for extracting alumina from fly ash, mixing the fly ash with ammonium sulfate and roasting, stripping the solids generated after sintering to obtain a solution containing ammonium aluminum sulfate; The solution containing aluminum ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02
Inventor 吴景龙薛惠民王瑾王少勋陈金燕刘晓明
Owner NORTH UNITED POWER CO LTD
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