A method for improving seed decomposition rate and cycle efficiency in alumina production

Abstract

The invention discloses a method for improving the seed decomposition rate and cycle efficiency in alumina production. The method comprises the steps of: (1) subjecting a aluminum hydroxide slurry to settling separation, and separating an obtained mother solution into an evaporation mother liquor and a treatment mother liquor, letting the evaporation mother liquor enter an evaporation process to perform evaporation concentration, and subjecting the treatment mother liquor to standing treatment, and then carrying out solid-liquid separation to obtain a supernatant and aluminum hydroxide; (2) sending the supernatant and evaporation return water into a cation membrane diffusion dialyzer to conduct countercurrent exchange so as to obtain raffinate and recovered alkali liquid; and (3) sending the raffinate back to the seed decomposition process to conduct further decomposition, sending the recovered alkali liquid into an evaporation process to perform evaporation concentration, then sending the concentration product to a wet grinding process and mixing the product with ores. The method has the characteristics of high alkali cycle efficiency, high mother solution primary circulation decomposition rate, high alumina output rate, and low alumina production unit energy consumption.

Description

technical field

[0001] The invention relates to a production process of alumina, in particular to a method for improving the decomposition rate and cycle efficiency of the alumina produced by the Bayer process. Background technique

[0002] In order to ensure the quality index of the obtained alumina in the production of Bayer process alumina, the primary decomposition rate of the concentrate liquid is about 50%-55%, and about 50% of the alumina cannot be decomposed, and enters the next step with the mother liquor. In the second cycle, the alkali cycle efficiency of the evaporated mother liquor is about 0.5-0.55 tAl 2 o 3 / tNa 2 Between O, the stripping ability is weak, and the output of a mother liquor cycle is low. At the same time, due to the high content of alumina in the mother liquor, the effective heat energy of evaporation, stripping and other processes is low, resulting in high unit energy consumption.

[0003] In the production of alumina, with the improvement o...

Examples

Embodiment 1

[0033] The ore used in the dissolution of this embodiment is diaspore, and the sodium hydroxide slurry produced in the seed crystal decomposition process has a value of αk of the mother liquor obtained through the slurry sedimentation and separation process at about 3.1, wherein the caustic alkali content is expressed as Na 2 O is about 155g / L, the content of aluminum is Al 2 o 3 Calculated as about 80g / L. The method for improving the decomposition rate and cycle efficiency of alumina production comprises the following steps:

[0034] (1) Divide the mother liquor obtained by settling and separating the aluminum hydroxide slurry in the seed crystal decomposition process in the alumina production process into two parts, one part is the evaporated mother liquor accounting for 80% of the total, and the other part is the treated mother liquor accounting for 20% of the total %; the evaporated mother liquor is sent to the evaporation process for evaporation and concentration, and ...

Embodiment 2

[0039] The ore used in the dissolution of this embodiment is diaspore, and the sodium hydroxide slurry produced in the seed crystal decomposition process has a value of αk of the mother liquor obtained through the slurry sedimentation and separation process at about 3.1, wherein the caustic alkali content is expressed as Na 2 O is about 155g / L, the content of aluminum is Al 2 o 3 Calculated as about 80g / L. The method for improving the decomposition rate and cycle efficiency of alumina production comprises the following steps:

[0040] (1) Divide the mother liquor obtained by settling and separating the aluminum hydroxide slurry in the seed crystal decomposition process in the alumina production process into two parts, one part is the evaporated mother liquor accounting for 70% of the total, and the other part is the treated mother liquor accounting for 30% of the total %; the evaporated mother liquor is sent to the evaporation process for evaporation and concentration, and ...

Embodiment 3

[0045] The ore used in the dissolution of this embodiment is diaspore, and the sodium hydroxide slurry produced in the seed crystal decomposition process has a value of αk of the mother liquor obtained through the slurry sedimentation and separation process at about 3.1, wherein the caustic alkali content is expressed as Na 2 O is about 155g / L, the content of aluminum is Al 2 o 3 Calculated as about 80g / L. The method for improving the decomposition rate and cycle efficiency of alumina production comprises the following steps:

[0046] (1) Divide the mother liquor obtained by settling and separating the aluminum hydroxide slurry in the seed crystal decomposition process in the alumina production process into two parts, one part is the evaporated mother liquor accounting for 60% of the total, and the other part is the treated mother liquor accounting for 40% of the total %; the evaporated mother liquor is sent to the mother liquor evaporation process for evaporation and conce...

technical field

[0001] The invention relates to a production process of alumina, in particular to a method for improving the decomposition rate and cycle efficiency of the alumina produced by the Bayer process. Background technique

[0002] In order to ensure the quality index of the obtained alumina in the production of Bayer process alumina, the primary decomposition rate of the concentrate liquid is about 50%-55%, and about 50% of the alumina cannot be decomposed, and enters the next step with the mother liquor. In the second cycle, the alkali cycle efficiency of the evaporated mother liquor is about 0.5-0.55 tAl 2 o 3 / tNa 2 Between O, the stripping ability is weak, and the output of a mother liquor cycle is low. At the same time, due to the high content of alumina in the mother liquor, the effective heat energy of evaporation, stripping and other processes is low, resulting in high unit energy consumption.

[0003] In the production of alumina, with the improvement o...

Examples

Embodiment 1

[0033] The ore used in the dissolution of this embodiment is diaspore, and the sodium hydroxide slurry produced in the seed crystal decomposition process has a value of αk of the mother liquor obtained through the slurry sedimentation and separation process at about 3.1, wherein the caustic alkali content is expressed as Na 2 O is about 155g / L, the content of aluminum is Al 2 o 3 Calculated as about 80g / L. The method for improving the decomposition rate and cycle efficiency of alumina production comprises the following steps:

[0034] (1) Divide the mother liquor obtained by settling and separating the aluminum hydroxide slurry in the seed crystal decomposition process in the alumina production process into two parts, one part is the evaporated mother liquor accounting for 80% of the total, and the other part is the treated mother liquor accounting for 20% of the total %; the evaporated mother liquor is sent to the evaporation process for evaporation and concentration, and ...

Embodiment 2

[0039] The ore used in the dissolution of this embodiment is diaspore, and the sodium hydroxide slurry produced in the seed crystal decomposition process has a value of αk of the mother liquor obtained through the slurry sedimentation and separation process at about 3.1, wherein the caustic alkali content is expressed as Na 2 O is about 155g / L, the content of aluminum is Al 2 o 3 Calculated as about 80g / L. The method for improving the decomposition rate and cycle efficiency of alumina production comprises the following steps:

[0040] (1) Divide the mother liquor obtained by settling and separating the aluminum hydroxide slurry in the seed crystal decomposition process in the alumina production process into two parts, one part is the evaporated mother liquor accounting for 70% of the total, and the other part is the treated mother liquor accounting for 30% of the total %; the evaporated mother liquor is sent to the evaporation process for evaporation and concentration, and ...

Embodiment 3

[0045] The ore used in the dissolution of this embodiment is diaspore, and the sodium hydroxide slurry produced in the seed crystal decomposition process has a value of αk of the mother liquor obtained through the slurry sedimentation and separation process at about 3.1, wherein the caustic alkali content is expressed as Na 2 O is about 155g / L, the content of aluminum is Al 2 o 3 Calculated as about 80g / L. The method for improving the decomposition rate and cycle efficiency of alumina production comprises the following steps:

[0046] (1) Divide the mother liquor obtained by settling and separating the aluminum hydroxide slurry in the seed crystal decomposition process in the alumina production process into two parts, one part is the evaporated mother liquor accounting for 60% of the total, and the other part is the treated mother liquor accounting for 40% of the total %; the evaporated mother liquor is sent to the mother liquor evaporation process for evaporation and conce...

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