Method for producing large grain size cryolite

A production method and cryolite technology are applied in the production field of large-diameter cryolite, which can solve the problems of complex process and achieve the effects of simple process, less flying loss and less pollution

Inactive Publication Date: 2010-06-16
河南未来铝业(集团)有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The cryolite particles produced by this method are relatively large, but because the gel is used as the medium, the process is relatively complicated

Method used

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  • Method for producing large grain size cryolite
  • Method for producing large grain size cryolite
  • Method for producing large grain size cryolite

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Embodiment one: the production method of large particle diameter cryolite, see appendix figure 1 , including the following steps,

[0030] (1) Raw materials and dosage: with Bayer method semen, caustic soda and hydrofluoric acid as raw materials, the molar ratio of raw materials is Al:Na:F=1:3:6; 3+ :Na + :F - =1:3:6;

[0031] Requirements: Bayer semen caustic ratio α k =1.5~2.0, including Al 2 o 3 140~150g / L, SiO 2 2 o 3 2 SiF 6 The mass percentage of <0.3%.

[0032] (2) Composite liquid preparation: when synthesizing, add caustic soda to the Bayer method seminal fluid that temperature is 90 ℃, stir, mix to obtain compound liquid;

[0033] (3) Synthesis of cryolite: gradually add the composite solution and hydrofluoric acid into the synthesis tank in proportion under stirring, and control the feeding speed during the feeding process so that the reaction temperature is between 90-95 °C and the pH of the reaction solution is ≤ 2; the feeding is completed Then ...

Embodiment 2

[0035] Embodiment two: the production method of large particle diameter cryolite, no longer repeat with the same part of embodiment one, difference is,

[0036] (1) Raw materials and dosage: take Bayer method semen, caustic soda and hydrofluoric acid as raw materials, and the molar ratio of raw materials is Al:Na:F=1:3:5;

[0037] (2) Composite liquid preparation: when synthesizing, add caustic soda to the Bayer method seminal fluid that temperature is 95 ℃, stir, mix to obtain compound liquid;

[0038] (3) Cryolite synthesis: add part of the circulating filtrate to the synthesis tank, and the amount of addition reaches the height of the stirring shaft with the amount of filtrate. Under continuous stirring, the compound liquid and hydrofluoric acid are gradually added to the synthesis tank in proportion from the metering tank at the same time , control the feed rate, so that the reaction temperature is between 85 and 90°C; the pH of the reaction end point is ≤3, and the aging ...

Embodiment 3

[0040] Embodiment three: the production method of large particle diameter cryolite, no longer repeat with the same part of embodiment one, difference is,

[0041] (1) Raw materials and dosage: take Bayer process semen, caustic soda and hydrofluoric acid as raw materials, and the molar ratio of raw materials is Al:Na:F=1:2:6;

[0042] (2) Composite liquid preparation: when synthesizing, add caustic soda to the Bayer method seminal fluid that temperature is 90 ℃, stir, mix to obtain compound liquid;

[0043] (3) Synthesis of cryolite: gradually add the composite solution and hydrofluoric acid to the synthesis tank in proportion under stirring, the reaction temperature is 88-90°C; aging for 25 minutes;

[0044] (4) press-filter the aged cryolite slurry to obtain filter cake and filtrate, and the moisture content of the filter cake is 16%; then the filter cake is directly heated and dried in a rotary kiln at 160°C until the moisture content is 0.19% ( mass ratio), that is, cryoli...

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Abstract

The invention discloses a production method for a large grain size cryolite, which is characterized in that Bayer process concentrate solution, caustic soda, and hydrofluoric acid are used as raw materials, and the proportion of raw materials is represented in the equation that Al: Na: F equals to 1:1.8-3:5-6; when compounding, the caustic soda is added into the Bayer process concentrate solutionwith a temperature of 90-95 DEG C, and mixed evenly to obtain the composite solution; then, the composite solution and hydrofluoric acid are gradually added into a synthesis tank, and the material feeding and agitation are carried out in the meantime, the reaction temperature is maintained between 85 and 95 DEG C, and the PH value of the reaction solution is smaller than or equal to 2; after feeding materials, the mixture undergoes an ageing process for 20 to 30 minutes; finally, the slurry is filtered, the filter cake is dried until the water content drops below 0.2%, thus acquiring the finished cryolite. The production method has the advantages that: as wet method is adopted during the production, the reaction is conducted under normal temperature, the process is simple, and easy to operate and control; the heat source is derived from the reaction heat, and the need to add a heating apparatus is avoided; by adjusting the parameters, such as the reaction temperature, PH value and ageing time, the product D50 grain size can be increased by more than 10 Mu m compared with the prior art up to 26-30 Mu m; the molecular ratio of NaF to AlF3 is adjustable, thus meeting the demands of electrolytic aluminum industry.

Description

1. Technical field: [0001] The invention relates to an aluminum electrolytic flux, in particular to a production method of cryolite with a large particle size. 2. Background technology: [0002] Artificial cryolite is mainly used in the electrolytic aluminum industry as a flux for aluminum smelting. The traditional artificial cryolite wet production process mainly includes: aluminum hydroxide-hydrofluoric acid-soda ash method, sodium fluorosilicate-aluminum hydroxide-soda ash method, ammonium fluoride-sodium aluminate method and sodium aluminate-hydrofluoride The acid-caustic soda method, etc., the particle size D50 of cryolite synthesized by these methods is generally about 15 μm, and the water content of the filter cake is generally 30-35%. Because the particle size is small and fine, the flying loss is large, and the separation efficiency during filtration is low; In addition, the moisture content of the filter cake is high, the heat energy required for drying is large, ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F7/54
Inventor 王志勇李民菁史智慧李高军李淮颜廖学建
Owner 河南未来铝业(集团)有限公司
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