A method of producing alumina

Abstract

The present application relates to the technical field of alumina production, and provides an alumina production method, which comprises the following steps: stirring and mixing desilication seeds, adjusting liquid and sintering method coarse liquid according to a ratio of 1:(2-4):(10-15) to form a mixed liquid, the initial desilication seeds are bayer process red mud, the adjusting liquid is seed separation mother liquor with a NK concentration of 185-235 g / L and ak of 3.2-3.8; the mixed liquid is pumped into a jacketed heater by a centrifugal pump for preheating; the preheated mixed liquid is stirred and left to desilicate at a desilication pressure of 1.0-1.5 MPa; the liquid is separated and washed by three times of sedimentation after desilication; the silicon residue at the bottom of the three times of sedimentation and washing tanks is mixed with the bayer process red mud according to a ratio of 1:(3-6) to form new desilication seeds for circulation; the overflow of the first sedimentation and washing tank is subjected to leaf filtration, decomposition, filtration and calcination to obtain alumina. The present application can enhance the desilication effect of the sintering method coarse liquid, improve the efficiency and product quality of alumina production, and reduce the cost of alumina production.

Description

Technical Field

[0001] This invention relates to the field of alumina production technology, and in particular to a method for producing alumina. Background Technology

[0002] There are several methods for producing alumina, including the pure Bayer process, the pure sintering process, the hybrid process, and the series process. Among these, the traditional sintering process uses a desiliconizer to desiliconize the crude solution. The desiliconizing seed used is the silica slag flowing from the bottom of the sintering separation settling tank. This seed has low activity, and the original process can only achieve a silica index of around 300 in a single desiliconization step, requiring a secondary deep desiliconization. However, this deep desiliconization requires the addition of lime slurry, which dilutes the concentration of the system solution and increases production costs.

[0003] The series method combines the sintering crude liquid and the Bayer process leaching slurry and then separates them by sedimentation before proceeding with subsequent production. It has the following advantages: it eliminates the need for separate desilication of the sintering crude liquid. Instead, it utilizes the temperature of approximately 120°C during the final flash evaporation of the Bayer process leaching slurry to heat the sintering crude liquid, which is only around 70°C, to around 105°C. After the Bayer process leaching slurry and the sintering crude liquid are combined, they undergo residence desilication, reducing the consumption of new steam. It also eliminates the need for carbon decomposition. However, it still has the following drawbacks: First, the sintering crude liquor and Bayer leaching slurry merge, crowding out the Bayer process's liquid volume and reducing its capacity. Simultaneously, due to the low concentration of the crude liquor, mixing it with the Bayer leaching slurry requires reducing the amount of washing water added to ensure the concentration of the refined liquor, leading to increased alumina loss in the Bayer process. Second, the continuous desilication after the sintering crude liquor and Bayer leaching slurry merge accelerates the scaling of the process network, affecting its heat transfer efficiency and limiting the full utilization of process formulation capabilities, resulting in increased alumina loss, reduced capacity, and higher production costs. Third, the existing series process is more expensive and less competitive than advanced imported low-temperature ore production. Only by utilizing existing processes and fully leveraging their characteristics to produce high-value-added products can a company gain a foothold in the fierce market competition. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides an alumina production method that can enhance the desiliconization effect of the sintering crude liquid, improve the efficiency and product quality of alumina production, and reduce the cost of alumina production.

[0005] The technical solution of this invention is as follows:

[0006] A method for producing alumina includes the following steps:

[0007] Step 1: Mixing

[0008] The crude sintering liquid from alumina production is loaded into a pre-desiliconization tank. Desiliconization seed and conditioning solution are then added to the pre-desiliconization tank, and the mixture is stirred at a rate of 20-40 r / min (e.g., 20 r / min, 22 r / min, 25 r / min, 27 r / min, 30 r / min, 33 r / min, 35 r / min, 38 r / min, 40 r / min, etc.). The mixture is allowed to stand for 4-8 hours (e.g., 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, etc.) to form a mixed solution. The initial desiliconization seed is Bayer red mud, and the conditioning solution is NK with a concentration of 185-2... Seed mother liquor with a concentration of 35 g / L (e.g., 185 g / L, 190 g / L, 195 g / L, 200 g / L, 205 g / L, 210 g / L, 215 g / L, 220 g / L, 225 g / L, 230 g / L, 235 g / L, etc.) and an ak of 3.2–3.8 (e.g., 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, etc.), and a ratio of desilication seeds, conditioning solution, and sintering crude liquor of 1:(2-4):(10-15) (e.g., 1:2:10, 1:2.5:11, 1:3:12, 1:3.5:13, 1:4:14, 1:4:15, etc.);

[0009] Step 2: Preheating

[0010] The mixture is pumped through a centrifugal pump at a speed of 350–480 m. 3 / h (e.g., 350m) 3 / h、360m 3 / h, 380m 3 / h, 400m 3 / h、420m 3 / h, 450m 3 / h、470m 3 / h、480m 3 A flow rate of (e.g., / h) is fed into the casing heater for preheating for 20–40 min (e.g., 20 min, 22 min, 25 min, 26 min, 28 min, 30 min, 33 min, 35 min, 37 min, 40 min, etc.), with a heating temperature of 140–145℃ (e.g., 140℃, 140.5℃, 141℃, 141.5℃, 142℃, 142.5℃, 143℃, 143.5℃, 144℃, 144.5℃, 145℃, etc.).

[0011] Step 3: Desilication at rest

[0012] The preheated mixture is sent to a residence desilication tank for stirring and residence desilication. The residence desilication time is 1-3 hours (e.g., 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.), the stirring rate is 20-40 r / min (e.g., 20 r / min, 22 r / min, 25 r / min, 27 r / min, 30 r / min, 33 r / min, 35 r / min, 38 r / min, 40 r / min, etc.), and the desilication pressure is 1.0-1.5 MPa (e.g., 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, etc.).

[0013] Step 4: Sedimentation and Washing

[0014] The liquid after desilication is subjected to three sedimentation separation and washing processes. The bottom silica slag from the three sedimentation separation and washing tanks is mixed with Bayer red mud in a ratio of 1:(3-6) (e.g., 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, etc.) to form new desilication seeds. The initial desilication seeds in step 1 are replaced with the new desilication seeds.

[0015] Step 5: Crude liquid refining

[0016] The overflow from the primary sedimentation and separation washing tank is sent to a leaf filter for leaf filtration to obtain semen;

[0017] Step 6: Decomposition

[0018] Add aluminum hydroxide seeds to semen to decompose the seeds;

[0019] Step 7: Filtering

[0020] The slurry after seed decomposition is subjected to hydrocyclone classification, and the underflow of the hydrocyclone classifier is sent to a flat plate filter for filtration to obtain aluminum hydroxide. The aluminum hydroxide product obtained by this invention has high purity and can be used as a raw material for producing high-quality non-metallurgical grade downstream customers, or it can be sent to step 8 to produce alumina.

[0021] Step 8: Roasting

[0022] Aluminum hydroxide is used as a raw material in a roasting furnace to produce alumina.

[0023] Furthermore, in step 1, the molecular ratio of caustic alkali to alumina in the mixture is 1.5 to 1.6 (e.g., 1.5, 1.52, 1.55, 1.57, 1.59, 1.6, etc.).

[0024] Furthermore, in step 1, the mixture is stirred and heated to 80-90°C (e.g., 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, etc.).

[0025] Furthermore, in step 1, the stirring rate is 30 r / min.

[0026] Furthermore, in step 1, the ratio of the desilication seed, the conditioning liquid, and the sintering crude liquid is 1:2:10.

[0027] Furthermore, the ratio of underflow silica slag to Bayer red mud in the new desilication seed is 1:4.

[0028] Furthermore, in step 3, the desilication time is 1 hour and the stirring rate is 30 r / min.

[0029] Furthermore, in step 3, the dimensions of the desilication tank are φ2.8*16m.

[0030] Furthermore, in step 4, the overflow of the tertiary sedimentation separation washing tank is returned to the secondary sedimentation separation washing tank as washing liquid, and the overflow of the secondary sedimentation separation washing tank is returned to the primary sedimentation separation washing tank as washing liquid.

[0031] The beneficial effects of this invention are as follows:

[0032] (1) This invention controls the molecular ratio of the mixed liquid by adding desilication seeds and conditioning liquid to the crude liquid of the sintering process, stirring and holding the mixture, preheating the mixture in a casing, stirring and holding it to remove silicon, purifying the solution through three sedimentation separation washings and leaf filtration, and producing alumina through decomposition filtration and roasting steps. Initially, Bayer red mud is used, and subsequently, the bottom silica slag from the three sedimentation separation washing tanks and Bayer red mud are used in a ratio of 1:(3-6) as desilication seeds. Seed mother liquor with an NK concentration of 185-235 g / L and an ak concentration of 3.2-3.8 is used as conditioning liquid. The stirring rate of the mixed liquid is controlled at 20-40 r / min, the residence time is 4-8 h, and the ratio of desilication seeds, conditioning liquid, and crude liquid of the sintering process is 1:(2-4):(10-15). The flow rate of the mixed liquid pumped into the casing heater is controlled at 350-480 m³ / min. 3 With a stirring rate of 20-40 r / min and a heating temperature of 140-145℃, the desilication time during the desilication process is controlled at 1-3 h, the stirring rate at 20-40 r / min, and the desilication pressure at 1.0-1.5 MPa. This method can enhance the desilication effect of the sintering crude liquor, increasing the silicon index from about 50 in the sintering crude liquor to 550-650 in the refined liquor, thus achieving continuous and efficient production and improving the quality of alumina products.

[0033] (2) This invention involves mixing the crude liquid from the sintering method with the conditioning liquid and desilication seed, stirring thoroughly, and then heating the mixture at an appropriate temperature. The temperature of the mixture is raised from about 70°C to 80-90°C, causing a small amount of desilication reaction during the mixing process. Initially, Bayer red mud with high activity is used as the desilication seed. Subsequently, the bottom silica slag from the three sedimentation separation and washing tank after desilication of the crude liquid from the sintering method is recycled with Bayer red mud at a ratio of 1:(3-6). At the same time, the seed is replaced regularly, which can improve the activity of the desilication seed, enhance the desilication effect, and increase the silica index of the concentrate. After one desilication, the silica index of the concentrate reaches 550-650. This avoids the secondary deep desilication of the traditional sintering method and the use of lime milk, which affect the quality of the sintering product during carbon separation. It reduces the cost of desilication, significantly reduces the impurity content of aluminum hydroxide intermediates, and improves the quality of alumina products.

[0034] (3) The present invention uses a shell heater to indirectly heat and preheat the mixture, and then performs desiliconization after preheating. The preheating process will not reduce the concentration of the crude liquid in the sintering method, and the steam condensate can be returned to the thermal power plant for reuse. This avoids the problem in the existing alumina production method that the concentration of the crude liquid in the sintering method is reduced due to direct steam heating for desiliconization, and the steam condensate cannot be returned to the thermal power plant for reuse.

[0035] (4) The present invention purifies the solution by three sedimentation separation washing and leaf filtration of the desiliconized liquid and then performs seed decomposition on the sintering liquid obtained by the present invention, instead of performing carbon separation on part of the liquid and seed separation on part of the liquid in the traditional sintering method. This can improve the quality of aluminum hydroxide and aluminum oxide products.

[0036] (5) This invention completely separates the series production of alumina into two independent processes: sintering and Bayer process. This reduces the amount of crude liquid in the Bayer process that is squeezed by the co-flow of crude liquid in the series process, avoids the reduction of crude liquid concentration in the sintering process by the co-flow of crude liquid, fully releases the production capacity, increases the system concentration, increases the amount of washing water for sedimentation, improves the sedimentation and washing efficiency, and eliminates the process pipeline scaling caused by the continuous desiliconization of crude liquid in the sintering process during the co-flow of crude liquid in the series process. Attached Figure Description

[0037] Figure 1 This is a flowchart of the alumina production method of the present invention in a specific embodiment. Detailed Implementation

[0038] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0039] Example 1

[0040] like Figure 1 As shown, the alumina production method of the present invention includes the following steps:

[0041] Step 1: Mixing

[0042] The crude sintering liquid produced by alumina production was loaded into a pre-desiliconization tank. Then, desiliconization seed and conditioning liquid were added to the pre-desiliconization tank and stirred at a stirring rate of 30 r / min. After mixing and holding for 4 hours, a mixed liquid was formed. The initial desiliconization seed was Bayer red mud, and the conditioning liquid was a seed mother liquor with an NK concentration of 185 g / L and an ak concentration of 3.2. The ratio of desiliconization seed, conditioning liquid and crude sintering liquid was 1:2:10. The mixed liquid was stirred and heated to 80℃. The molecular ratio of caustic alkali to alumina in the mixed liquid was 1.5.

[0043] Step 2: Preheating

[0044] The mixture was pumped through a centrifugal pump at 350 m³ / h 3 A flow rate of / h is fed into the bushing heater for preheating for 20 minutes, with a heating temperature of 140℃;

[0045] Step 3: Desilication at rest

[0046] The preheated mixture is sent to a residence desilication tank for stirring and residence desilication; the residence desilication time is 1 hour, the stirring rate is 30 r / min, the desilication pressure is 1.0 MPa, and the dimensions of the residence desilication tank are φ2.8*16m.

[0047] Step 4: Sedimentation and Washing

[0048] The liquid after desilication is subjected to three sedimentation separation and washing processes. The bottom silica slag from the three sedimentation separation and washing tanks is mixed with Bayer red mud at a ratio of 1:4 to form new desilication seeds, which replace the initial desilication seeds in step 1. The overflow from the three sedimentation separation and washing tanks is returned to the second sedimentation separation and washing tank as washing liquid, and the overflow from the second sedimentation separation and washing tanks is returned to the first sedimentation separation and washing tank as washing liquid.

[0049] Step 5: Crude liquid refining

[0050] The overflow from the primary sedimentation and separation washing tank is sent to a leaf filter for leaf filtration to obtain semen;

[0051] Step 6: Decomposition

[0052] Add aluminum hydroxide seeds to semen to decompose the seeds;

[0053] Step 7: Filtering

[0054] The slurry after seed decomposition is subjected to hydrocyclone classification, and the underflow of the hydrocyclone classifier is sent to a flat plate filter for filtration to obtain aluminum hydroxide.

[0055] Step 8: Roasting

[0056] Aluminum hydroxide is used as a raw material in a roasting furnace to produce alumina.

[0057] Example 2

[0058] In this embodiment 2, the alumina production method of the present invention includes the following steps:

[0059] Step 1: Mixing

[0060] The crude sintering liquid produced from alumina was loaded into a pre-desiliconization tank, and then desiliconization seed and conditioning liquid were added to the pre-desiliconization tank. The mixture was stirred at a stirring rate of 20 r / min and kept for 5 h to form a mixed liquid. The initial desiliconization seed was Bayer red mud, and the conditioning liquid was a seed mother liquor with an NK concentration of 200 g / L and an ak concentration of 3.5. The ratio of desiliconization seed, conditioning liquid and crude sintering liquid was 1:3:12. The mixed liquid was stirred and heated to 85℃. The molecular ratio of caustic alkali to alumina in the mixed liquid was 1.55.

[0061] Step 2: Preheating

[0062] The mixture was pumped through a centrifugal pump at 400m... 3 A flow rate of / h is fed into the bushing heater for preheating for 30 minutes, with a heating temperature of 143℃;

[0063] Step 3: Desilication at rest

[0064] The preheated mixture is sent to a residence desilication tank for stirring and residence desilication; the residence desilication time is 2 hours, the stirring rate is 35 r / min, and the desilication pressure is 1.2 MPa.

[0065] Step 4: Sedimentation and Washing

[0066] The liquid after desilication is subjected to three sedimentation separation and washing processes. The bottom silica slag from the three sedimentation separation and washing tanks is mixed with Bayer red mud at a ratio of 1:3 to form new desilication seeds, which replace the initial desilication seeds in step 1. The overflow from the three sedimentation separation and washing tanks is returned to the second sedimentation separation and washing tank as washing liquid, and the overflow from the second sedimentation separation and washing tanks is returned to the first sedimentation separation and washing tank as washing liquid.

[0067] Step 5: Crude liquid refining

[0068] The overflow from the primary sedimentation and separation washing tank is sent to a leaf filter for leaf filtration to obtain semen;

[0069] Step 6: Decomposition

[0070] Add aluminum hydroxide seeds to semen to decompose the seeds;

[0071] Step 7: Filtering

[0072] The slurry after seed decomposition is subjected to hydrocyclone classification, and the underflow of the hydrocyclone classifier is sent to a flat plate filter for filtration to obtain aluminum hydroxide.

[0073] Step 8: Roasting

[0074] Aluminum hydroxide is used as a raw material in a roasting furnace to produce alumina.

[0075] Example 3

[0076] In this embodiment 3, the alumina production method of the present invention includes the following steps:

[0077] Step 1: Mixing

[0078] The crude sintering liquid produced by alumina production was loaded into a pre-desiliconization tank. Then, desiliconization seed and conditioning liquid were added to the pre-desiliconization tank and stirred at a stirring rate of 35 r / min. After mixing and holding for 7 h, a mixed liquid was formed. The initial desiliconization seed was Bayer red mud, and the conditioning liquid was a seed mother liquor with an NK concentration of 220 g / L and an ak concentration of 3.6. The ratio of desiliconization seed, conditioning liquid and crude sintering liquid was 1:4:12. The mixed liquid was stirred and heated to 90℃. The molecular ratio of caustic alkali to alumina in the mixed liquid was 1.6.

[0079] Step 2: Preheating

[0080] The mixture was pumped through a centrifugal pump at 450 m³ / h 3 A flow rate of / h is fed into the bushing heater for preheating for 35 minutes, with a heating temperature of 145℃;

[0081] Step 3: Desilication at rest

[0082] The preheated mixture is sent to a residence desilication tank for stirring and residence desilication; the residence desilication time is 2.5h, the stirring rate is 40r / min, and the desilication pressure is 1.4MPa.

[0083] Step 4: Sedimentation and Washing

[0084] The liquid after desilication is subjected to three sedimentation separation and washing processes. The bottom silica slag from the three sedimentation separation and washing tank is mixed with Bayer red mud at a ratio of 1:5 to form a new desilication seed, which replaces the initial desilication seed in step 1. The overflow from the three sedimentation separation and washing tank is returned to the second sedimentation separation and washing tank as washing liquid, and the overflow from the second sedimentation separation and washing tank is returned to the first sedimentation separation and washing tank as washing liquid.

[0085] Step 5: Crude liquid refining

[0086] The overflow from the primary sedimentation and separation washing tank is sent to a leaf filter for leaf filtration to obtain semen;

[0087] Step 6: Decomposition

[0088] Add aluminum hydroxide seeds to semen to decompose the seeds;

[0089] Step 7: Filtering

[0090] The slurry after seed decomposition is subjected to hydrocyclone classification, and the underflow of the hydrocyclone classifier is sent to a flat plate filter for filtration to obtain aluminum hydroxide.

[0091] Step 8: Roasting

[0092] Aluminum hydroxide is used as a raw material in a roasting furnace to produce alumina.

[0093] Example 4

[0094] In this embodiment 4, the alumina production method of the present invention includes the following steps:

[0095] Step 1: Mixing

[0096] The crude sintering liquid produced by alumina production was loaded into a pre-desiliconization tank. Then, desiliconization seed and conditioning liquid were added to the pre-desiliconization tank and stirred at a stirring rate of 40 r / min. After mixing and holding for 8 hours, a mixed liquid was formed. The initial desiliconization seed was Bayer red mud, and the conditioning liquid was a seed mother liquor with an NK concentration of 235 g / L and an ak concentration of 3.8. The ratio of desiliconization seed, conditioning liquid and crude sintering liquid was 1:4:15. The mixed liquid was stirred and heated to 90℃. The molecular ratio of caustic alkali to alumina in the mixed liquid was 1.6.

[0097] Step 2: Preheating

[0098] The mixture was pumped through a centrifugal pump at 480 m... 3 A flow rate of / h is fed into the bushing heater for preheating for 40 minutes, with a heating temperature of 145℃;

[0099] Step 3: Desilication at rest

[0100] The preheated mixture is sent to a residence desilication tank for stirring and residence desilication; the residence desilication time is 3 hours, the stirring rate is 40 r / min, and the desilication pressure is 1.5 MPa.

[0101] Step 4: Sedimentation and Washing

[0102] The liquid after desilication is subjected to three sedimentation separation and washing processes. The bottom silica slag from the three sedimentation separation and washing tank is mixed with Bayer red mud at a ratio of 1:6 to form a new desilication seed, which replaces the initial desilication seed in step 1. The overflow from the three sedimentation separation and washing tank is returned to the second sedimentation separation and washing tank as washing liquid, and the overflow from the second sedimentation separation and washing tank is returned to the first sedimentation separation and washing tank as washing liquid.

[0103] Step 5: Crude liquid refining

[0104] The overflow from the primary sedimentation and separation washing tank is sent to a leaf filter for leaf filtration to obtain semen;

[0105] Step 6: Decomposition

[0106] Add aluminum hydroxide seeds to semen to decompose the seeds;

[0107] Step 7: Filtering

[0108] The slurry after seed decomposition is subjected to hydrocyclone classification, and the underflow of the hydrocyclone classifier is sent to a flat plate filter for filtration to obtain aluminum hydroxide.

[0109] Step 8: Roasting

[0110] Aluminum hydroxide is used as a raw material in a roasting furnace to produce alumina.

[0111] Obviously, the above embodiments are merely some, not all, of the embodiments of the present invention. The above embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention. Based on the above embodiments, all other embodiments obtained by those skilled in the art without inventive effort, that is, all modifications, equivalent substitutions, and improvements made within the spirit and principle of this application, fall within the scope of protection claimed by the present invention.

Claims

1. A method for producing alumina, characterized in that, Includes the following steps: Step 1: Mixing The crude sintering liquid produced by alumina production is loaded into a pre-desiliconization tank. Then, desiliconization seed and conditioning liquid are added to the pre-desiliconization tank and stirred at a stirring rate of 20-40 r / min. After mixing and holding for 4-8 hours, a mixed liquid is formed. The initial desiliconization seed is Bayer red mud, and the conditioning liquid is a seed mother liquor with an NK concentration of 185-235 g / L and an ak concentration of 3.2-3.

8. The ratio of desiliconization seed, conditioning liquid and crude sintering liquid is 1:(2-4):(10-15). The molecular ratio of caustic alkali to alumina in the mixed liquid is 1.5-1.

6. Step 2: Preheating The mixture is pumped through a centrifugal pump at a speed of 350–480 m. 3 A flow rate of / h is fed into the casing heater for preheating for 20-40 minutes, with a heating temperature of 140-145℃; Step 3: Desilication at rest The preheated mixture is sent to a residence desilication tank for stirring and residence desilication; the residence desilication time is 1-3 hours, the stirring rate is 20-40 r / min, and the desilication pressure is 1.0-1.5 MPa. Step 4: Sedimentation and Washing The liquid after desiliconization is subjected to three sedimentation separation and washing processes. The bottom silica slag of the three sedimentation separation and washing tank is mixed with Bayer red mud in a ratio of 1:(3-6) to form a new desiliconization seed. The initial desiliconization seed in step 1 is replaced with the new desiliconization seed. Step 5: Crude liquid refining The overflow from the primary sedimentation and separation washing tank is sent to a leaf filter for leaf filtration to obtain semen; Step 6: Decomposition Add aluminum hydroxide seeds to semen to decompose the seeds; Step 7: Filtering The slurry after seed decomposition is subjected to hydrocyclone classification, and the underflow of the hydrocyclone classifier is sent to a flat plate filter for filtration to obtain aluminum hydroxide. Step 8: Roasting Aluminum hydroxide is used as a raw material in a roasting furnace to produce alumina.

2. The alumina production method according to claim 1, characterized in that, In step 1, the mixture is stirred and heated to 80-90°C.

3. The alumina production method according to claim 1, characterized in that, In step 1, the stirring rate is 30 r / min.

4. The alumina production method according to claim 1, characterized in that, In step 1, the ratio of the desilication seed, the conditioning liquid, and the sintering crude liquid is 1:2:

10.

5. The alumina production method according to claim 1, characterized in that, The ratio of underflow silica slag to Bayer red mud in the new desilication seed is 1:

4.

6. The alumina production method according to claim 1, characterized in that, In step 3, the desilication time is 1 hour and the stirring rate is 30 r / min.

7. The alumina production method according to claim 1, characterized in that, In step 3, the dimensions of the desilication tank are φ2.8*16m.

8. The alumina production method according to claim 1, characterized in that, In step 4, the overflow of the tertiary sedimentation separation washing tank is returned to the secondary sedimentation separation washing tank as washing liquid, and the overflow of the secondary sedimentation separation washing tank is returned to the primary sedimentation separation washing tank as washing liquid.

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