Separation method for completion liquid of caustic soda liquid-phase oxidation of chromite

A technology of chromite and caustic soda, which is applied in the field of chromate, can solve the problems of difficult solid-liquid separation and unrealized industrialization

Inactive Publication Date: 2013-09-25
余华强
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0022] ②In solution carbonation, impurities such as silicon, iron, and aluminum are easy to form colloids, making subsequent solid-liquid separation very difficult
[0029] So far, the technology of preparing sodium chromate or sodium dichromate by caustic soda liquid phase oxidation (three-phase oxidation) from ferrochrome or chromite has made progress in oxidation, but there is no such technology at home and abroad. On the whole, a technical and economical feasible process route is formed, that is, industrialization has not been realized

Method used

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  • Separation method for completion liquid of caustic soda liquid-phase oxidation of chromite

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0074] with a Cr 2 o 3 38.42%, Fe 2 o 3 15.24%, MgO 17.78%, Al 2 o 3 23.24%, SiO 3 4.46%, CaO 0.91% chromite, oxidation completion solution obtained by three-phase oxidation, containing Na 2 CrO 4 33.05%, NaOH 28.15%, NaAlO 2 9.27%, Na 2 SiO 3 1.97%.

[0075] For 1 ton, 0.828 tons of the above oxidation completion liquid and 0.172 tons of crude product sodium chromate (containing Na 2 CrO 4 90.91%), calculated according to formula (7) and formula (8), the minimum amount of chromite that needs to be added is 0.73 tons, and the maximum amount is 1.0 tons.

[0076] Spray 0.828 tons of this oxidized solution on 0.85 tons of chromite and 0.172 tons of crude sodium chromate at 280°C, dry and granulate at 90—280°C, so that 90% of the particles are within 0.05—5mm within range. Calcined in air, the temperature of the material was slowly (within 1.5 hours) raised from 280°C to 680°C and held at 680°C for 50 minutes.

[0077] After cooling the material to room ...

Embodiment 2

[0083] Oxidation completion liquid and crude product sodium chromate identical with embodiment 1 composition and quantity, but use another kind of ore with higher silicon content, i.e. Cr 2 o 3 34.84%, Fe 2 o 3 18.56%, MgO 20.09%, Al 2 o 3 13.24%, SiO 3 11.66%, CaO 1.09% chromite. By 0.828 tons of the above oxidation completion liquid and 0.172 tons of crude product sodium chromate (containing Na 2 CrO 4 90.91%), calculated according to formula (7) and formula (8), the minimum amount of chromite that needs to be added is 0.81 tons, and the maximum amount is 1.10 tons.

[0084] Spray 0.828 tons of this oxidation-completed liquid on 0.9 tons of chromite and 0.172 tons of crude sodium chromate at 240°C, dry and granulate at 80—240°C, so that 90% of the particles are within 0.05—5mm within range. Roasting in the air, the temperature of the material is slowly (within 1.5 hours) raised from 240°C to 600°C for 0.5 hour, and then heated to 650°C for 0.5 hour.

[008...

Embodiment 3

[0092] with a Cr 2 o 3 46.31% of chromite, obtained through three-phase oxidation to obtain the oxidation completion solution, plus the hot-pressed leaching solution of one process cycle to concentrate the crude product sodium chromate, comprehensively calculate the Na content of the material 2 CrO 4 43.44%, NaOH 25.64%, NaAlO 2 5.91%, Na 2 SiO 3 1.70%, water 16.99%, insoluble matter 6.32%.

[0093] When dealing with this oxidation completion liquid, use a Cr-containing 2 o 3 34.84%, Fe 2 o 3 18.56%, MgO 20.09%, Al 2 o 3 13.24%, SiO 3 11.66%, CaO 1.09% chromite. By 0.842 tons of the above oxidation completion liquid and 0.158 tons of crude product sodium chromate (containing Na 2 CrO 4 90.91%), calculated according to formula (7) and formula (8), the minimum amount of chromite that needs to be added is 0.81 tons, and the maximum amount is 1.07 tons.

[0094] 0.842 tons of the above-mentioned oxidation completion solution is sprayed on 0.95 tons of th...

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Abstract

The invention provides a method for separation and preparation of sodium chromate or heavy sodium chromate from completion liquid of caustic soda liquid-phase oxidation or three-phase oxidation of chromite or ferrochrome. The method comprises the following five steps: caustic soda solid-phase roasting, solid-phase carbonation, counter-current leaching, secondary roasting and hot-pressing leaching. The invention has the following advantages: 1, high recovery rates are obtained, wherein the recovery rate of chromium reaches 95 to 98%, the recovery rate of alkali is more than 80%, the cyclic utilization rate of CO2 is more than 70%, so consumption of materials is low; 2, energy consumption is substantially decreased compared to a traditional method; and 3, the amount of waste residue is only 0.9 to 1.3 ton per ton of sodium dichromate, the content of Cr<6+> (in terms of Na2Cr2O72H2O) in the waste residue is less than 0.05%, far less than the content of Cr<6+> (less than 0.2%) in a traditional calcium-free roasting method, and thus, total pollution amount of Cr<6+> in the waste residue in the invention is less than that in the traditional calcium-free roasting method.

Description

[0001] This application is a supplement and replacement for the original application: 2013102810460. technical field [0002] The present invention relates to the manufacture of chromates, in particular sodium chromate or sodium dichromate. background of the invention [0003] Since the beginning of the 19th century, the traditional method of preparing sodium chromate or sodium dichromate from chromite (references ①, ②, ③) has been using soda ash (Na 2 CO 3 ) A method for solid-phase high-temperature roasting of chromite. due to Na 2 CO 3 The reaction with chromite must be carried out at high temperature (900──1200°C): [0004] 4FeO·Cr 2 o 3 + 8Na 2 CO 3 + 7O 2 = 8Na 2 CrO 4 + 2Fe 2 o 3 + 8CO 2 , (1) [0005] And the product sodium chromate (Na 2 CrO 4 ) has a melting point of 792°C. In order to prevent the molten sodium chromate from agglomerating, scarring or even sticking to the wall of the roasting kiln, at the same time, impurities such a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G37/14
Inventor 余华强
Owner 余华强
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