Bayer process alumina dissolution grading control method

Abstract

The invention discloses a Bayer process aluminum oxide dissolution grading control method, which is characterized in that in the dissolution process of Bayer process aluminum oxide production, grade grading of bauxite is carried out, and the ratio C / S of ash blending calcium to silicon is correspondingly controlled in a grading manner, so that the addition amount of a lime cosolvent is controlled. According to the method, the grade of the bauxite is graded, and the calcium-silicon ratio of the mixed ash is controlled in a corresponding grading manner, so that the accurate control of the mixed ash is facilitated, the dissolution effect of the bauxite can be ensured, the waste of the lime is avoided, the optimal allocation and use of resources are realized, the consumption of production raw materials is saved, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to a Bayer process alumina dissolution classification control method, belonging to the technical field of Bayer process alumina production. Background Art

[0002] With the scarcity of bauxite resources, the alumina grade varies greatly across the country. Even in different mining areas in the same region, the bauxite grade varies greatly. Therefore, the fluctuation of ore grade has a great impact on production organization. In the Bayer process of bauxite dissolution, lime needs to be added as a solvent. The amount of lime added directly affects the relative dissolution rate of bauxite. However, affected by the grade of bauxite, production needs to achieve a relatively balanced and stable bauxite grade through ore blending. However, at different times, due to the difference in the grade of the incoming ore, the aluminum-silicon ratio (A / S) of the blended ore will also vary greatly. A / S generally fluctuates between 4-7. The fluctuation range of A / S of bauxite is large, which brings difficulties to production blending. The most intuitive blending in production is usually measured by the percentage of lime and bauxite. Due to the change in the silica content in bauxite, the blending is not accurate enough. Too little or too much ash blending will lead to a decrease in the relative dissolution of bauxite, thereby affecting the recovery rate of alumina. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a Bayer process alumina dissolution classification control method, which can overcome the shortcomings of the prior art.

[0004] The objective of the present invention is achieved through the following technical solutions: The invention discloses a Bayer process alumina dissolution classification control method, which performs bauxite grade classification in the dissolution process of Bayer process alumina production, controls the lime-calcium-silicon ratio C / S accordingly, and further controls the addition amount of lime solvent.

[0005] Furthermore, the grade of the bauxite is expressed by the aluminum-silicon ratio (A / S), which is divided into at least five levels, and the lime-calcium-silicon ratio C / S is controlled accordingly, thereby controlling the amount of lime solvent added. The specific steps are as follows: s1. Constructing a hierarchical control database, wherein the hierarchical control database includes the aluminum-silicon ratio grade data of bauxite and the corresponding lime-calcium-silicon ratio grade data; s2. The Bayer process is used to produce alumina. The grade of bauxite is controlled by means of ore blending and homogenization. The lime-calcium-silicon ratio grade data corresponding to the grade of bauxite in the graded control database is called to control the amount of lime solvent added.

[0006] Furthermore, in step s1, the aluminum-silicon ratio grade data of the bauxite and the corresponding lime-calcium-silicon ratio grade data are specifically: The A / S ratio of bauxite is 4.0-5.0, and the ratio of lime, calcium and silicon is controlled at 0.7-0.8; The A / S ratio of bauxite is 5.0-5.5, and the ratio of lime, calcium and silicon is controlled at 0.8-0.9. The A / S of bauxite is 5.5-6.0, and the ratio of lime, calcium and silicon is controlled at 0.9-1.0; The A / S of bauxite is 6.0-7.0, and the ratio of lime, calcium and silicon is controlled at 1.0-1.1. The A / S of bauxite is 7.0-8.0, and the ratio of lime, calcium and silicon C / S is controlled at 1.1-1.3.

[0007] Furthermore, in step s2, the Bayer process is used to produce alumina, and the dissolution temperature involved is controlled in the range of 260-270°C.

[0008] Furthermore, within the temperature control range, the higher the dissolution temperature is controlled, the lower the required optimal ash-calcium-silicon ratio C / S is.

[0009] Furthermore, when the Bayer process is used to produce alumina, the amount of lime solvent added is controlled in stages by online monitoring, and the specific steps are as follows: (1) Processing the bauxite raw materials by means of ore blending and homogenization, and grinding the bauxite raw materials into bauxite powder; (2) Analyze the aluminum and silicon content in bauxite powder, obtain aluminum-silicon ratio data, and determine the grade of bauxite; (3) According to the grade of bauxite, the lime-calcium-silicon ratio grade data corresponding to the grade of bauxite in the classification control database is called up to reversely calculate the amount of lime to be added.

[0010] Furthermore, the lime involved in step (3) has an effective calcium content of 80-90%.

[0011] Furthermore, the caustic ratio ak of the sodium aluminate solution of the dissolution solution is monitored online synchronously, and the amount of lime added is further controlled so that the caustic ratio ak is controlled within a range of 1.35-1.40.

[0012] Compared with the prior art, the beneficial effects of the present invention are: Aiming at bauxite of different grades, the present invention involves grading the grade of bauxite and controlling the calcium-silicon ratio of lime blending according to the grade, which is beneficial to the precise control of lime blending, can ensure the dissolution effect of bauxite without causing lime waste, realize the optimal allocation and use of resources, save the consumption of production raw materials, and reduce production costs.

[0013] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] 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 control flow diagram of the present invention. DETAILED DESCRIPTION

[0015] 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.

[0016] like Figure 1 As shown, a Bayer process alumina dissolution classification control method is used, which performs bauxite grade classification in the dissolution process of Bayer process alumina production, and controls the lime-calcium-silicon ratio C / S accordingly, thereby controlling the amount of lime solvent added.

[0017] The grade of bauxite is represented by the aluminum-silicon ratio (A / S), which is divided into at least five levels, and the lime-calcium-silicon ratio C / S is controlled accordingly, thereby controlling the amount of lime solvent added. The specific steps are as follows: s1. Constructing a hierarchical control database, wherein the hierarchical control database includes the aluminum-silicon ratio grade data of bauxite and the corresponding lime-calcium-silicon ratio grade data; s2. The Bayer process is used to produce alumina. The grade of bauxite is controlled by means of ore blending and homogenization. The lime-calcium-silicon ratio grade data corresponding to the grade of bauxite in the graded control database is called to control the amount of lime solvent added.

[0018] In step s1, the aluminum-silicon ratio grade data of bauxite and the corresponding lime-calcium-silicon ratio grade data are specifically: The A / S ratio of bauxite is 4.0-5.0, and the ratio of lime, calcium and silicon is controlled at 0.7-0.8; The A / S ratio of bauxite is 5.0-5.5, and the ratio of lime, calcium and silicon is controlled at 0.8-0.9. The A / S of bauxite is 5.5-6.0, and the ratio of lime, calcium and silicon is controlled at 0.9-1.0; The A / S of bauxite is 6.0-7.0, and the ratio of lime, calcium and silicon is controlled at 1.0-1.1. The A / S of bauxite is 7.0-8.0, and the ratio of lime, calcium and silicon C / S is controlled at 1.1-1.3.

[0019] In step s2, alumina is produced by the Bayer process, and the dissolution temperature control range involved is 260-270° C. Specifically, within this temperature control range, the higher the dissolution temperature control, the lower the required optimal ash-calcium-silicon ratio C / S.

[0020] When using the Bayer process to produce alumina, the amount of lime solvent added is controlled in stages using online monitoring. The specific steps are: s2.1. The bauxite raw materials are transported to the alumina plant. During the storage and use process, the bauxite with different components is mixed and blended in proportion by using the stacking method to make it into a mixed ore of corresponding grade. Then, the mixing and reclaiming machine is used to flatten and cut it. After secondary mixing, it is transported to the finished bauxite slurry preparation and ground into bauxite powder. Among them, the bauxite type involved is mainly diaspore-type bauxite; s2.2. Analyze the aluminum and silicon content in bauxite powder, obtain aluminum-silicon ratio data, and determine the grade of bauxite; s2.3. According to the grade of bauxite, the lime-calcium-silicon ratio grade data corresponding to the grade of bauxite in the classification control database is called up to reversely calculate the amount of lime added; wherein the effective calcium of the lime involved is 80-90%.

[0021] Furthermore, the caustic ratio ak of the sodium aluminate solution of the dissolution solution is monitored online synchronously, and the amount of lime added is further controlled so that the caustic ratio ak is controlled within a range of 1.35-1.40.

[0022] Example 1 The alumina content of bauxite is 56.44%, the aluminum-silicon ratio (A / S) is 6.23, the dissolution temperature is 265°C, the lime-calcium-silicon ratio (C / S) is 0.7 (the lime-calcium-silicon ratio is insufficient), and the relative dissolution rate is 92.73%.

[0023] The alumina content of bauxite is 56.44%, the aluminum-silicon ratio (A / S) is 6.23, the dissolution temperature is 265°C, the lime-calcium-silicon ratio (C / S) is 1.03 (the best lime-calcium-silicon ratio), and the relative dissolution rate is 96.37%.

[0024] The alumina content of bauxite is 56.44%, the aluminum-silicon ratio (A / S) is 6.23, the dissolution temperature is 265°C, the lime-calcium-silicon ratio (C / S) is 1.4 (the lime-calcium-silicon ratio is excessive), and the relative dissolution rate is 94.65%.

[0025] Conclusion: Under the same conditions of aluminum-silicon ratio (A / S) of bauxite, insufficient or excessive ash content will lead to a decrease in the relative dissolution of bauxite, while ash blending within the corresponding optimal calcium-silicon ratio (C / S) range can effectively increase the relative dissolution rate of bauxite.

[0026] Example 2 The alumina content of bauxite is 56.44%, the aluminum-silicon ratio (A / S) is 6.23, the dissolution temperature is 250°C, the ash-calcium-silicon ratio (C / S) is 1.03, and the relative dissolution rate is 92.35%.

[0027] The alumina content of bauxite is 56.44%, the aluminum-silicon ratio (A / S) is 6.23, the dissolution temperature is 260°C, the ash-calcium-silicon ratio (C / S) is 1.03, and the relative dissolution rate is 94.26%.

[0028] The alumina content of bauxite is 56.44%, the aluminum-silicon ratio (A / S) is 6.23, the dissolution temperature is 265°C, the ash-calcium-silicon ratio (C / S) is 1.03, and the relative dissolution rate is 96.37%.

[0029] The alumina content of bauxite is 56.44%, the aluminum-silicon ratio (A / S) is 6.23, the dissolution temperature is 270°C, the ash-calcium-silicon ratio (C / S) is 1.03, and the relative dissolution rate is 96.55%.

[0030] The alumina content of bauxite is 56.44%, the aluminum-silicon ratio (A / S) is 6.23, the dissolution temperature is 280°C, the ash-calcium-silicon ratio (C / S) is 1.03, and the relative dissolution rate is 96.75%.

[0031] Conclusion: Under the same conditions of bauxite aluminum-silicon ratio (A / S), and within the corresponding optimal calcium-silicon ratio (C / S) range, too low or too high dissolution temperature will lead to a decrease in the relative dissolution of bauxite, while controlling the dissolution temperature at 260-270℃ can effectively increase the relative dissolution rate of bauxite.

[0032] Example 3 The alumina content of bauxite is 56.44%, the aluminum-silicon ratio (A / S) is 6.23, the dissolution temperature is 265°C, the ash-calcium-silicon ratio (C / S) is 1.03, and the relative dissolution rate is 96.37%.

[0033] The alumina content of bauxite is 55.13%, the aluminum-silicon ratio (A / S) is 5.70, the dissolution temperature is 265°C, the ash-calcium-silicon ratio (C / S) is 0.98, and the relative dissolution rate is 96.17%.

[0034] The alumina content of bauxite is 54.55%, the aluminum-silicon ratio (A / S) is 4.86, the dissolution temperature is 265°C, the ash-calcium-silicon ratio (C / S) is 0.78, and the relative dissolution rate is 96.05%.

[0035] Conclusion: Under the same temperature conditions, the aluminum-silicon ratio (A / S) of bauxite is different, and the corresponding optimal lime-calcium-silicon ratio (C / S) is also different. However, as long as it is within the optimal lime-calcium-silicon ratio (C / S) range, the relative dissolution rate of bauxite can be effectively improved.

[0036] Example 4 The alumina content of bauxite is 54.90%, the aluminum-silicon ratio (A / S) is 4.54, the dissolution temperature is 260°C, the optimal ash-calcium-silicon ratio (C / S) is 0.9, and the relative dissolution rate is 96.60%.

[0037] The alumina content of bauxite is 54.90%, the aluminum-silicon ratio (A / S) is 4.54, the dissolution temperature is 265°C, the optimal ash-calcium-silicon ratio (C / S) is 0.8, and the relative dissolution rate is 96.63%; The alumina content of bauxite is 54.90%, the aluminum-silicon ratio (A / S) is 4.54, the dissolution temperature is 270°C, the optimal ash-calcium-silicon ratio (C / S) is 0.70, and the relative dissolution rate is 97.14%.

[0038] The alumina content of bauxite is 55.73%, the aluminum-silicon ratio (A / S) is 5.18, the dissolution temperature is 260°C, the optimal ash-calcium-silicon ratio (C / S) is 1.0, and the relative dissolution rate is 96.74%; The alumina content of bauxite is 55.73%, the aluminum-silicon ratio (A / S) is 5.18, the dissolution temperature is 265°C, the optimal ash-calcium-silicon ratio (C / S) is 0.8, and the relative dissolution rate is 96.74%; The alumina content of bauxite is 55.73%, the aluminum-silicon ratio (A / S) is 5.18, the dissolution temperature is 270°C, the optimal ash-calcium-silicon ratio (C / S) is 0.7, and the relative dissolution rate is 96.62%.

[0039] Conclusion: Within this temperature range, the optimal ash-calcium-silicon ratio (C / S) decreases with increasing dissolution temperature, but as long as it is kept within the optimal dissolution temperature range, the relative dissolution rate of bauxite can be effectively improved.

[0040] The above description is only a preferred embodiment of the present invention and does not constitute any form of confidentiality restriction on the present invention. Any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A Bayer process alumina dissolution classification control method, characterized in that: In the dissolution process of Bayer process alumina production, the grade of bauxite is classified, and the lime-calcium-silicon ratio C / S is controlled accordingly, thereby controlling the amount of lime solvent added.

2. The Bayer process alumina classification control method according to claim 1, characterized in that: The grade of the bauxite is expressed by the aluminum-silicon ratio (A / S), which is divided into at least five levels, and the lime-calcium-silicon ratio C / S is controlled accordingly, thereby controlling the amount of lime solvent added; the specific steps are as follows: s1. Constructing a hierarchical control database, wherein the hierarchical control database includes the aluminum-silicon ratio grade data of bauxite and the corresponding lime-calcium-silicon ratio grade data; s2. The Bayer process is used to produce alumina. During the preparation process, the grade of bauxite is detected, and the lime-calcium-silicon ratio grade data corresponding to the grade of bauxite in the classification control database is called to control the amount of lime solvent added.

3. The Bayer process alumina classification control method according to claim 2, characterized in that: In step s1, the aluminum-silicon ratio grade data of bauxite and the corresponding lime-calcium-silicon ratio grade data are specifically: The A / S ratio of bauxite is 4.0-5.0, and the ratio of lime, calcium and silicon is controlled at 0.7-0.8; The A / S ratio of bauxite is 5.0-5.5, and the ratio of lime, calcium and silicon is controlled at 0.8-0.

9. The A / S of bauxite is 5.5-6.0, and the ratio of lime, calcium and silicon is controlled at 0.9-1.0; The A / S of bauxite is 6.0-7.0, and the ratio of lime, calcium and silicon is controlled at 1.0-1.

1. The A / S of bauxite is 7.0-8.0, and the ratio of lime, calcium and silicon C / S is controlled at 1.1-1.

3.

4. The Bayer process alumina classification control method according to claim 2, characterized in that: In step s2, the Bayer process is used to produce alumina, and the dissolution temperature involved is controlled in the range of 260-270°C.

5. The Bayer process alumina classification control method according to claim 4, characterized in that: Within this temperature control range, the higher the dissolution temperature is controlled, the lower the required optimal ash-calcium-silicon ratio C / S is.

6. The Bayer process alumina classification control method according to any one of claims 1 to 5, characterized in that: When using the Bayer process to produce alumina, the amount of lime solvent added is controlled in stages using online monitoring. The specific steps are: (1) Processing the bauxite raw materials by means of ore blending and homogenization, and grinding the bauxite raw materials into bauxite powder; (2) Analyze the aluminum and silicon content in bauxite powder, obtain aluminum-silicon ratio data, and determine the grade of bauxite; (3) According to the grade of bauxite, the lime-calcium-silicon ratio grade data corresponding to the grade of bauxite in the classification control database is called up to reversely calculate the amount of lime to be added.

7. The Bayer process alumina classification control method according to claim 6, characterized in that: The lime involved in step (3) has an effective calcium content of 80-90%.

8. The Bayer process alumina classification control method according to claim 7, characterized in that: The caustic ratio ak of the sodium aluminate solution of the dissolution solution is monitored online simultaneously, and the amount of lime added is further controlled to control the caustic ratio ak within a range of 1.35-1.40.

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