Method and system for reducing carbon and alkali accumulation in process of producing aluminum oxide by Bayer process

Abstract

The invention discloses a method for reducing carbon and alkali accumulation in a process of producing aluminum oxide by a Bayer process, which comprises the following steps of: feeding strong alkali liquor filtered by a salt discharging machine into a strong alkali tank through a first pipeline assembly, and feeding strong alkali liquor overflowing from a salt settling tank into the strong alkali tank through a second pipeline assembly; the middle of the strong alkali tank in the depth direction is connected with the circulating mother liquor blending tank through a strong alkali liquor conveying pipeline assembly, the bottom of the strong alkali tank is connected with the salt settling tank through an underflow conveying pipeline assembly, and the bottom of the salt settling tank is connected with the salt discharging machine through a salt discharging pipeline assembly; the invention also discloses a system for reducing carbon alkali accumulation in the process of producing alumina by the Bayer process, strong alkali liquor in the middle of the depth direction of the strong alkali tank is clear, and is conveyed to the circulating mother liquor blending tank through the strong alkali liquor conveying pipeline assembly for adjusting the circulating mother liquor, so that sodium carbonate returned to the process of producing alumina by the Bayer process is obviously reduced; the problems of high solid content and unsmooth alkali supplement caused by sodium carbonate are avoided, and the concentration of the circulating mother liquor meets the requirement.

Description

Technical Field

[0001] The invention relates to the field of producing alumina by the Bayer process, in particular to a method for reducing carbon and alkali accumulation in the process of producing alumina by the Bayer process, and also to a system for reducing carbon and alkali accumulation in the process of producing alumina by the Bayer process. Background Art

[0002] In the Bayer process of producing alumina, strong alkali solution is a high-concentration alkali used to prepare the circulating mother liquor. It is mainly obtained by alkali treatment and forced evaporation concentration, and filtering and precipitating sodium carbonate solids through a salt discharge machine. Part of it is obtained through the overflow of the salt settling tank 2, such as Figure 2 As shown, the strong alkali solution enters the strong alkali tank 1 for use in preparing the circulating mother liquor.

[0003] In the strong alkali tank 1, sodium carbonate will precipitate again due to the cooling of the strong alkali solution, and the overflow turbidity of the salt sedimentation tank 2 will also bring in sodium carbonate, resulting in a large amount of sodium carbonate solids accumulating at the bottom of the strong alkali tank 1 after a period of operation. During the preparation of the circulating mother liquor, the strong alkali tank 1 is supplemented with strong alkali at a low level, and some sodium carbonate enters the process again, which will cause the carbon-alkali ratio of the circulating mother liquor to increase, affecting the normal operation of production and greatly reducing the salt discharge efficiency. In addition, as sodium carbonate continues to accumulate at the bottom of the strong alkali tank 1, the alkali supplementation will be poor, and the concentration of the circulating mother liquor will not meet the production requirements, so it has to exit the strong alkali tank 1 for cleaning. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a method and system for reducing carbon alkali accumulation in the Bayer process for producing alumina, so as to at least solve the technical problems mentioned in the background technology.

[0005] The objective of the present invention is achieved through the following technical solutions: A method for reducing carbon alkali accumulation in a Bayer process for producing alumina, wherein the strong alkali solution obtained by filtering a salt discharger is sent into a strong alkali tank through a first pipeline assembly, and the strong alkali solution overflowing from a salt settling tank is sent into the strong alkali tank through a second pipeline assembly, so that the middle of the strong alkali tank in the depth direction is connected to a circulating mother liquor preparation tank through a strong alkali solution delivery pipeline assembly, and the bottom of the strong alkali tank is connected to a salt settling tank through an underflow delivery pipeline assembly, and the bottom of the salt settling tank is connected to a salt discharger through a salt discharge pipeline assembly.

[0006] Furthermore, the strong alkali solution delivery pipeline assembly includes a strong alkali solution delivery pipe and a pump and a valve arranged on the strong alkali solution delivery pipe.

[0007] Furthermore, the underflow delivery pipeline assembly includes an underflow delivery pipe and a pump and a valve arranged on the underflow delivery pipe.

[0008] Furthermore, the salt discharge pipeline assembly includes a salt discharge pipeline and a pump and a valve arranged on the salt discharge pipeline.

[0009] A system for reducing carbon alkali accumulation in the Bayer process for producing alumina, comprising a desalter, a filtrate outlet of the desalter connected to a strong alkali tank via a first pipeline assembly, and a salt settling tank, an overflow port of the salt settling tank connected to the strong alkali tank via a second pipeline assembly, a middle portion of the strong alkali tank in a depth direction connected to a circulating mother liquor preparation tank via a strong alkali liquid delivery pipeline assembly, a bottom of the strong alkali tank connected to the salt settling tank via an underflow delivery pipeline assembly, and a bottom of the salt settling tank connected to the desalter via a salt discharge pipeline assembly.

[0010] Furthermore, the strong alkali solution delivery pipeline assembly includes a strong alkali solution delivery pipe and a pump and a valve arranged on the strong alkali solution delivery pipe.

[0011] Furthermore, the underflow delivery pipeline assembly includes an underflow delivery pipe and a pump and a valve arranged on the underflow delivery pipe.

[0012] Furthermore, the salt discharge pipeline assembly includes a salt discharge pipeline and a pump and a valve arranged on the salt discharge pipeline.

[0013] The beneficial effects of the present invention are: The invention discloses a method and system for reducing the accumulation of carbon alkali in the Bayer process for producing aluminum oxide. The strong alkali solution in the middle of the strong alkali tank in the depth direction is relatively clear and contains very little sodium carbonate. The strong alkali solution is transported to the circulating mother liquor preparation tank through the strong alkali solution delivery pipeline component for adjusting the circulating mother liquor, so that the sodium carbonate returned to the Bayer process for producing aluminum oxide is significantly reduced, and there is no problem of high solid content and poor alkali replenishment due to sodium carbonate, and the concentration of the circulating mother liquor meets the requirements. In the strong alkali tank, sodium carbonate is precipitated at the bottom of the tank and is transported to the salt settling tank through the underflow delivery pipeline component for salt discharge. When there is less alkali, the sodium carbonate returns, which improves the salt discharge efficiency and increases the operation cycle of the strong alkali tank.

[0014] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which: Figure 1 It is a schematic diagram of the present invention.

[0016] Figure 2 It is a schematic diagram of the prior art.

[0017] In the figure: 1. Strong alkali tank; 2. Salt sedimentation tank; 3. Pump. DETAILED DESCRIPTION

[0018] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the preferred embodiments are only for illustrating the present invention, rather than for limiting the protection scope of the present invention.

[0019] Embodiment 1 like Figure 1 As shown, a method for reducing carbon alkali accumulation in the Bayer process of producing alumina is provided. The strong alkali solution obtained by filtering a salt discharger is sent to a strong alkali tank through a first pipeline assembly, the first pipeline assembly includes a first pipeline and a valve arranged on the first pipeline, the strong alkali solution overflowing from a salt settling tank is sent to the strong alkali tank through a second pipeline assembly, the second pipeline assembly includes a second pipeline and a valve arranged on the second pipeline, the middle part of the strong alkali tank in the depth direction is connected to a circulating mother liquor preparation tank through a strong alkali solution delivery pipeline assembly, the strong alkali solution delivery pipeline assembly includes a strong alkali solution delivery pipe and a pump and a valve arranged on the strong alkali solution delivery pipe, the bottom of the strong alkali tank is connected to a salt settling tank through an underflow delivery pipeline assembly, the underflow delivery pipeline assembly includes an underflow delivery pipe and a pump and a valve arranged on the underflow delivery pipe, the bottom of the salt settling tank is connected to a salt discharger through a salt discharge pipeline assembly, the salt discharge pipeline assembly includes a salt discharge pipeline and a pump and a valve arranged on the salt discharge pipeline, and the salt discharge pipeline assembly includes a salt discharge pipeline and a pump and a valve arranged on the salt discharge pipeline.

[0020] Embodiment 2 A system for reducing carbon alkali accumulation in a Bayer process for producing alumina, comprising a desalter, a filtrate outlet of the desalter connected to a strong alkali tank via a first pipeline assembly, the first pipeline assembly comprising a first pipeline and a valve arranged on the first pipeline, and a salt settling tank, an overflow port of the salt settling tank connected to the strong alkali tank via a second pipeline assembly, the second pipeline assembly comprising a second pipeline and a valve arranged on the second pipeline, the middle of the strong alkali tank in the depth direction is connected to a circulating mother liquor preparation tank via a strong alkali liquid delivery pipeline assembly, the strong alkali liquid delivery pipeline assembly comprising a strong alkali liquid delivery pipe and a pump and a valve arranged on the strong alkali liquid delivery pipe, the bottom of the strong alkali tank is connected to the salt settling tank via an underflow delivery pipeline assembly, the underflow delivery pipeline assembly comprising an underflow delivery pipe and a pump and a valve arranged on the underflow delivery pipe, the bottom of the salt settling tank is connected to the desalter via a salt discharge pipeline assembly, the salt discharge pipeline assembly comprising a salt discharge pipe and a pump and a valve arranged on the salt discharge pipe.

[0021] The strong alkali solution in the middle of the strong alkali tank in the depth direction of the above embodiment is relatively clear, and contains very little sodium carbonate. It is transported to the circulating mother liquor preparation tank through the strong alkali solution delivery pipeline assembly for regulating the circulating mother liquor, so that the sodium carbonate returned to the Bayer process for producing alumina is significantly reduced, and there is no problem of high solid content and poor alkali replenishment due to sodium carbonate, and the concentration of the circulating mother liquor meets the requirements. In the strong alkali tank, sodium carbonate is precipitated at the bottom of the tank, and the pump and valve on the bottom flow delivery pipe are opened to send the sodium carbonate at the bottom of the tank to the salt sedimentation tank for sedimentation, and then the slurry at the bottom of the sedimentation tank is sent to the salt discharge machine for filtration through the pump and valve on the salt discharge pipeline to filter out the sodium carbonate solids. The use of the above embodiment significantly extends the operation cycle of the strong alkali tank, and the sodium carbonate returns when there is less alkali, which improves the salt discharge efficiency.

[0022] After the implementation of the above embodiment, the operation cycle of the strong alkali tank 1 is extended from twice a year to once a year (there are two strong alkali tanks 2, which can save 85,000 yuan in cleaning costs each year).

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for reducing carbon alkali accumulation in the Bayer process for producing alumina, characterized in that: The strong alkali liquid obtained by filtering the salt discharger is sent into the strong alkali tank through the first pipeline assembly, and the strong alkali liquid overflowing from the salt sedimentation tank is sent into the strong alkali tank through the second pipeline assembly, so that the middle part of the strong alkali tank in the depth direction is connected to the circulating mother liquor preparation tank through the strong alkali liquid delivery pipeline assembly, and the bottom of the strong alkali tank is connected to the salt sedimentation tank through the underflow delivery pipeline assembly, and the bottom of the salt sedimentation tank is connected to the salt discharger through the salt discharge pipeline assembly.

2. The method for reducing carbon alkali accumulation in the Bayer process for producing alumina according to claim 1, characterized in that: The strong alkali solution delivery pipeline assembly comprises a strong alkali solution delivery pipe and a pump and a valve arranged on the strong alkali solution delivery pipe.

3. The method for reducing carbon alkali accumulation in the Bayer process for producing alumina according to claim 1, characterized in that: The underflow delivery pipeline assembly comprises an underflow delivery pipe and a pump and a valve arranged on the underflow delivery pipe.

4. The method for reducing carbon alkali accumulation in the Bayer process for producing alumina according to claim 1, characterized in that: The salt discharge pipeline assembly comprises a salt discharge pipeline and a pump and a valve arranged on the salt discharge pipeline.

5. A system for reducing carbon alkali accumulation in a Bayer process for producing alumina, characterized in that: It includes a salt discharger, the filtrate outlet of the salt discharger is connected to a strong alkali tank through a first pipeline assembly, and it also includes a salt sedimentation tank, the overflow port of the salt sedimentation tank is connected to the strong alkali tank through a second pipeline assembly, the middle of the strong alkali tank in the depth direction is connected to a circulating mother liquor preparation tank through a strong alkali liquid conveying pipeline assembly, the bottom of the strong alkali tank is connected to the salt sedimentation tank through an underflow conveying pipeline assembly, and the bottom of the salt sedimentation tank is connected to the salt discharger through a salt discharge pipeline assembly.

6. The system for reducing carbon alkali accumulation in the Bayer process for producing alumina according to claim 5, characterized in that: The strong alkali solution delivery pipeline assembly comprises a strong alkali solution delivery pipe and a pump and a valve arranged on the strong alkali solution delivery pipe.

7. The system for reducing carbon alkali accumulation in the Bayer process for producing alumina according to claim 5, characterized in that: The underflow delivery pipeline assembly comprises an underflow delivery pipe and a pump and a valve arranged on the underflow delivery pipe.

8. The system for reducing carbon alkali accumulation in the Bayer process for producing alumina according to claim 5, characterized in that: The salt discharge pipeline assembly comprises a salt discharge pipeline and a pump and a valve arranged on the salt discharge pipeline.

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