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A method for preparing non-metallurgical grade alumina by electrolysis

A non-metallurgical-grade alumina technology, which is applied in the field of preparing non-metallurgical-grade alumina by electrolysis, can solve the problems of alumina application performance changes, prolonging the treatment process, and high production costs, and achieves low cost, high purity, and decomposition The effect of low temperature

Active Publication Date: 2020-06-05
贵州博汇联润铝业有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The treatment process of this method is simple, but it needs to consume a large amount of penetrant, and the cost is high
Some researchers also add mineralizers or organic reagents to react with sodium oxide to form volatile compounds, which are then calcined and decomposed into aluminum hydroxide. This method not only has high production costs, but also easily leads to failure of the application performance of alumina. Variety
Therefore, in view of the current alumina production level, in order to produce low-sodium high-purity non-metallurgical-grade alumina, it is necessary to use unconventional means to improve the purity and particle size of aluminum hydroxide seed crystals to reach the ultra-fine nanoscale level, in order to make Separating high-quality aluminum hydroxide from sodium aluminate solution and obtaining it through calcination will inevitably increase costs and prolong the treatment process

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] The industrial sodium aluminate produced by an enterprise contains 105 mg / L iron and 350 mg / L silicon dioxide after removing iron by sodium sulfide and desiliconization by calcium oxide. It is prepared with industrial alumina or aluminum hydroxide to a caustic ratio (α k ) is 1.2, the concentration of caustic (sodium hydroxide) is 140g / L, and then it is added to an electrolytic cell, with 316 stainless steel plates as the cathode and anode at the same time. Anode chamber and cathode chamber, the upper part of the two chambers is level with the top of the electrolytic cell, and the lower part is 100mm away from the bottom of the electrolytic cell. A stainless steel valve with a diameter of 60 mm is provided at the bottom of the electrolytic cell for discharging sediments. There are 12 sets of cathodes and anodes (12 anodes and 13 cathodes) in the electrolysis cell. The electrolytic control tank voltage is 4V, and the anode current density is 400A / m 2 , the electrolysis ...

Embodiment 2

[0027] An enterprise uses sodium aluminate to remove iron and desiliconize, its αk value is 1.25, and the concentration of caustic alkali is 150g / L. The electrolytic cell of Example 1 is used for electrolysis. Control the electrolysis conditions as tank voltage 4.5V, anode current density 700A / m2, electrolysis temperature 60°C, electrolyte flow rate 500L / h, extract the electrolytic deposit every 8 hours for filtration, wash with 80°C hot water and place it in a single microwave oven Microwave radiation treatment was carried out. The microwave radiation frequency is controlled to 3GHz, the power is 0.8-2kW, the temperature in the furnace is 300°C, and the radiation time is 30 minutes to obtain alumina powder products.

[0028] The average value of 5 sampling tests was taken, and the test results showed that the particle size of alumina was 2.3 microns, the purity was 99.85%, the sodium oxide was 0.053%, and the electrolytic residual liquid α k The value is 1.7, the caustic con...

Embodiment 3

[0030] The iron-removing sodium desilicate sodium aluminate solutions of Example 1 and Example 2 were produced by the seed separation method, and the aluminum hydroxide crystals obtained were washed with hot water at 80 ° C. The amount of hot water was 1.5% of that of Example 1 or Example 2. -3x quality. Then it is calcined in an electric heating furnace at 250°C-300°C for 2-3 hours. Sampling and laboratory testing were carried out for 5 times, and the results showed that the product had a purity of 94.5-95.2% of alumina, 4.3-5.5% of aluminum hydroxide, 0.65-0.92% of sodium oxide, and a particle size of 50-85 microns. The output rate is 52.3%.

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Abstract

The invention relates to the technical field of aluminum hydroxide manufacturing, and especially relates to a method for preparing non-metallurgical alumina by an electrolysis process. Reasonable control of the caustic-to-alumna molar ratio of a sodium aluminate solution and electrolysis, washing and microwave radiation treatments make the sodium oxide content of the prepared alumina greatly reduced to 0.1% or less, so the method has the advantages of low cost and high yield; the alumina product has a high purity and a high yield, and a byproduct sodium hydroxide is obtained, so the recyclingof the sodium hydroxide is achieved.

Description

technical field [0001] The invention relates to the technical field of aluminum hydroxide production, in particular to a method for preparing non-metallurgical grade alumina by electrolysis. Background technique [0002] Since low-sodium non-metallurgical alumina is widely used in refractory materials, fine ceramics, electrical appliances, insulating ceramic devices, catalyst carriers, etc., its sales price is more than 2 times higher than that of metallurgical alumina. An important means to improve efficiency. [0003] Low-sodium alumina is alumina with a sodium content of less than 0.1%, a purity of more than 99.5%, and a particle size of less than 10 μm. At present, low-sodium alumina is mainly produced by thermal decomposition of high-purity ultra-fine aluminum hydroxide. High-purity ultra-fine aluminum hydroxide is mainly produced by adding high-purity ultra-fine aluminum hydroxide seeds to sodium aluminate solution to decompose and crystallize by using the seed separ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C25B1/00C01F7/44C25B1/16
CPCC01F7/441C25B1/00C25B1/16
Inventor 刘安荣刘俊良王振杰刘荣心刘权姚亮
Owner 贵州博汇联润铝业有限公司
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