Low-temperature low-pressure hydro chemical method for recovering aluminum oxide and sodium oxide from red mud

A low-temperature, low-pressure, alumina technology, applied in the direction of alumina/aluminum hydroxide, alkali metal oxides, etc., can solve the problems of difficult industrial operation, high energy consumption of calcium oxide, and high equipment investment, so as to improve resource utilization, Excellent operability and high recovery rate

Inactive Publication Date: 2009-09-23
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to propose a new method for processing red mud based on the high-pressure hydrochemical method—a low-temperature and low-pressure hydrochemical method to recycle alumina and sodium oxide in red mud, so as to overcome the performance of the existing industrial technology calcium oxide sintering method. A series of difficulties such as high consumption, difficulty in matching the main dissolution process of the Bayer method with the hydrothermal method, and high-temperature and high-pressure operation of the high-pressure hydrochemical method cause high investment in equipment and difficult industrial operations, providing an industrial application for the treatment of red mud New Ways of Prospect

Method used

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  • Low-temperature low-pressure hydro chemical method for recovering aluminum oxide and sodium oxide from red mud
  • Low-temperature low-pressure hydro chemical method for recovering aluminum oxide and sodium oxide from red mud
  • Low-temperature low-pressure hydro chemical method for recovering aluminum oxide and sodium oxide from red mud

Examples

Experimental program
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Effect test

Embodiment 1

[0018] Using Bayer process red mud as raw material, aluminum oxide and sodium oxide are recovered by low-temperature and low-pressure hydrochemical method. The composition (wt%) of the red mud used in the Bayer process is as follows:

[0019]

[0020] The specific processing steps are as follows:

[0021] 1. Take a certain amount of red mud and add it to the NaOH solution with a mass percentage concentration of 50%. The mass ratio of NaOH to red mud is 4:1. After mixing evenly, transfer it to the reaction kettle, adjust the stirring speed, and set the temperature control program. , raise the temperature of the reactor to 220°C to react for 4 hours, and then turn on the cooling water to complete the reaction; filter the reaction slurry while it is hot, separate the liquid and solid, and use the red mud filter cake for later use. Take 10g of red mud filter cake, wash at 95°C and dry at 120°C, analyze its composition (wt%), the results show that Al in red mud 2 o 3 Content ...

Embodiment 2

[0025] Using Bayer process red mud as raw material, aluminum oxide and sodium oxide are recovered by low-temperature and low-pressure hydrochemical method. The composition (wt%) of the red mud of the Bayer process used is the same as that of Example 1.

[0026] The specific processing steps are as follows:

[0027] 1. Take a certain amount of red mud and add it to the NaOH solution with a mass percentage concentration of 50%. The mass ratio of NaOH to red mud is 3:1. After mixing evenly, transfer it to the reactor, adjust the stirring speed, and set the temperature control program. , raise the temperature of the reactor to 230°C for 3.5 hours, and then turn on the cooling water to complete the reaction; filter the reaction slurry while it is hot, separate the liquid and solid, and use the red mud filter cake for later use. Take 10g of red mud filter cake, wash at 95°C and dry at 120°C, analyze its composition (wt%), the results show that Al in red mud 2 o 3 The content is 6...

Embodiment 3

[0031] Using low-temperature and low-pressure hydrochemical method to recover alumina and sodium oxide from high-alkali red mud obtained by dissolving medium and low-grade bauxite with less calcium oxide as raw material. The raw material red mud composition (wt%) is as follows:

[0032]

[0033] The specific processing steps are as follows:

[0034] 1. Take a certain amount of red mud and milk of lime and add it to the NaOH solution with a mass percentage concentration of 45%. The amount of milk of lime added is based on CaO and SiO in the red mud. 2 The molar ratio of NaOH and red mud is calculated as 1:1, and the mass ratio of NaOH to red mud is 4:1. After mixing evenly, transfer it to the reactor, adjust the stirring speed, set the temperature control program, and raise the temperature of the reactor to 210°C for 3.5 h, and then turn on the cooling water to end the reaction; filter the reaction slurry while it is hot, separate the liquid from the solid, and use the red ...

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Abstract

The invention belongs to the filed of processing, recovering and utilizing red mud waste from the production of aluminum oxide, and relates to a low-temperature low-pressure hydro chemical method for recovering aluminum oxide and sodium oxide from red mud. The method is also used for processing low-grade bauxite. The method comprises the following steps that: a red mud filter cake and lime milk are added in and evenly mixed with a concentrated solution of sodium hydroxide; the mixture is continuously stirred, heated up to the temperature of between 190 and 230 for reaction for 3 to 4h, and undergoes solid-liquid separation; the red mud filter cake undergoes deep sodium removal by the hydrothermal method, namely the red mud filter cake is added with water and lime milk and under the condition of liquid to solid ratio(L / S) of reaction pulp of 6, the mixture is reacted at a temperature of 170 DEG C for 2h, filtered and washed. By the method for processing the red mud, the A / S and N / S of the red mud are both reduced to below 0.18, so that the method provides a novel way of realizing the low-pollution emission and resource recovery of the red mud.

Description

technical field [0001] The invention belongs to the field of treatment and recycling of waste red mud in the alumina production industry, and relates to a low-temperature and low-pressure hydrochemical method for recycling alumina and sodium oxide in red mud. The method is also suitable for processing low-grade bauxite. Background technique [0002] The recovery and utilization of red mud has always been a problem and technical difficulty faced by the alumina industry. On average, about 1-1.7 tons of red mud are produced for every ton of alumina produced. At present, about 60 million tons of red mud are produced in the world every year. my country's red mud The emission is about 10 million tons or more per year, and the content of alumina in the red mud is high (mass percentage is about 20%-28%). If the alumina in the red mud is not recovered, it will inevitably lead to a shortage of bauxite resources. Serious waste; in addition, most of the domestic and foreign alumina factor...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02C01D1/02
Inventor 张亦飞钟莉孙旺郑诗礼张懿
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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