Method for slowing down scarring speed of evaporator

An evaporator and scarring technology, which is applied in the field of slowing down the speed of evaporator scarring, can solve the problems of affecting the operating efficiency of the evaporator, a large amount of crystallization, and accelerated precipitation speed.

Active Publication Date: 2012-07-25
中铝中州铝业有限公司
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Problems solved by technology

Since the content of impurities such as silicon oxide in the decomposed mother liquor is supersaturated, during the evaporation process of the mother liquor, as the temperature increases, the silicon oxide is replaced by sodium aluminosilicate (Na 2 O·Al 2 o 3 1.7SiO2 2 2H 2 O) The speed of morphological precipitation will be accelerated, and a large amount of crystallization will be precipitated on the surface of the heat exchange tube of the evaporator, forming scars, which will seriously affect the operating efficiency of the evaporator

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  • Method for slowing down scarring speed of evaporator
  • Method for slowing down scarring speed of evaporator

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Components of the evaporated stock solution: total alkali: 180.1g / l alumina: 87.33g / l caustic: 162.0g / l silicon oxide: 1.375g / l Rp: 0.539 silicon content index: 63.5. The amount of the fine filter cake is added at 4g / l, reacted in a water bath at 70°C for 1 hour, and evaporated after desiliconization The composition of the stock solution: total alkali: 183.30g / l alumina: 88.3g / l caustic alkali: 165.0g / l oxidation Silicon: 1.005g / l Rp: 0.535 Silicon content index: 87.9, silicon content index increased by 24.2.

Embodiment 2

[0014] Components of the evaporated stock solution: total alkali: 180.1g / l alumina: 87.33g / l caustic: 162.0g / l silicon oxide: 1.375g / l Rp: 0.539 silicon content index: 63.5. The amount of the fine filter cake is added at 10g / l, reacted in a water bath at 80°C for 2 hours, and evaporated after desiliconization The composition of the stock solution: total alkali: 193.0g / l alumina: 88.09g / l caustic alkali: 169.4g / l oxidation Silicon: 0.926g / l Rp: 0.520 Silicon content index: 95.1, silicon content index increased by 31.6.

Embodiment 3

[0016] Components of the evaporated stock solution: total alkali: 180.1g / l alumina: 87.33g / l caustic: 162.0g / l silicon oxide: 1.375g / l Rp: 0.539 silicon content index: 63.5. The amount of the fine filter cake is added at 30g / l, and it is reflected in a water bath at 90°C for 3 hours. After desiliconization, the original solution is evaporated. Components of the original solution: total alkali: 207.8. Silicon oxide: 0.597g / l Rp: 0.506 Silicon content index: 156.0, silicon content index increased by 92.5.

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Abstract

A method for slowing down scarring speed of evaporator relates to a technique improvement during production procedure of Bayer processed aluminium oxide. The present invention is characterized in that a Bayer processed coarse liquid is added into a mother liquid obtained by filtering after seed crystal decomposition is performed for refining liquid, so as to refine filter cakes discharged by a leaf filter of the system; in an evaporation raw liquid slot and under 70-90 DEG C, the filter cakes stays for about 1-3 hours, and enter an evaporation unit for performing an evaporation process. In the method of the present invention, seed crystal is added in the evaporation raw liquid, sodium silicoaluminate seed crystal surface is provided, and newly separated sodium silicoaluminate is separatedfrom the seed crystal surface, so that the amount of sodium silicoaluminate separated from the surface of an evaporator heat exchange tube is reduced, and the scarring speed of the evaporator is slowed down. Simultaneously, Al2O3 can be recovered from the filter cakes during the evaporation procedure, and alumina hydrolysis loss of the part to be delivered to refining liquid filter cake washed separately and acting as initiation during washing procedure is reduced.

Description

technical field [0001] A method for slowing down the scalding speed of an evaporator relates to a process improvement in the production process of Bayer process alumina. Background technique [0002] At present, in the process of producing alumina by the Bayer process, after the bauxite is dissolved, the main component of the crude liquid obtained after the separation of the slurry is Al 2 o 3 、Na 2 O, SiO 2 . Since the content of suspended solids in the crude liquid exceeds the requirements of the species classification system, it is necessary to reduce the content of suspended matter through the crude liquid refining system (leaf filter), the obtained semen enters the species classification process, and the obtained filter cake enters the separation and washing process, and is discharged with the red mud . [0003] The obtained semen is decomposed by seed crystals to separate out Al(OH)3. After the seed separation, the mother liquor obtained by filtration (that is, th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F7/02
Inventor 李培增郝红杰刘万城晏华钎陈晓静张继林尹海军
Owner 中铝中州铝业有限公司
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