CN117585699A - Causticizing method in process of producing alumina from guinea bauxite - Google Patents
Causticizing method in process of producing alumina from guinea bauxite Download PDFInfo
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- CN117585699A CN117585699A CN202311643934.2A CN202311643934A CN117585699A CN 117585699 A CN117585699 A CN 117585699A CN 202311643934 A CN202311643934 A CN 202311643934A CN 117585699 A CN117585699 A CN 117585699A
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- Prior art keywords
- washing tank
- causticizing
- lime milk
- red mud
- bauxite
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- 238000009993 causticizing Methods 0.000 title claims abstract description 61
- 238000000034 method Methods 0.000 title claims abstract description 45
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 229910001570 bauxite Inorganic materials 0.000 title claims abstract description 23
- 238000005406 washing Methods 0.000 claims abstract description 66
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 44
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 44
- 239000004571 lime Substances 0.000 claims abstract description 44
- 239000008267 milk Substances 0.000 claims abstract description 40
- 210000004080 milk Anatomy 0.000 claims abstract description 40
- 235000013336 milk Nutrition 0.000 claims abstract description 40
- 239000007788 liquid Substances 0.000 claims abstract description 15
- 238000007865 diluting Methods 0.000 claims abstract description 12
- 238000004062 sedimentation Methods 0.000 claims abstract description 9
- 238000000926 separation method Methods 0.000 claims abstract description 8
- 210000000582 semen Anatomy 0.000 claims abstract description 6
- 238000001238 wet grinding Methods 0.000 claims abstract description 6
- 230000000694 effects Effects 0.000 abstract description 6
- 238000005265 energy consumption Methods 0.000 abstract description 6
- 238000006243 chemical reaction Methods 0.000 abstract description 3
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 18
- 238000004519 manufacturing process Methods 0.000 description 12
- 229910000029 sodium carbonate Inorganic materials 0.000 description 9
- 238000001704 evaporation Methods 0.000 description 6
- 239000003518 caustics Substances 0.000 description 4
- 238000004131 Bayer process Methods 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000003513 alkali Substances 0.000 description 3
- 239000006071 cream Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000008020 evaporation Effects 0.000 description 3
- 239000005416 organic matter Substances 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 239000002893 slag Substances 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 235000011116 calcium hydroxide Nutrition 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 229910001748 carbonate mineral Inorganic materials 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000008394 flocculating agent Substances 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012452 mother liquor Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000002455 scale inhibitor Substances 0.000 description 1
- 229910001388 sodium aluminate Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/06—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom by treating aluminous minerals or waste-like raw materials with alkali hydroxide, e.g. leaching of bauxite according to the Bayer process
- C01F7/066—Treatment of the separated residue
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Analytical Chemistry (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention discloses a causticizing method in a process of producing alumina from guinea bauxite, which comprises the following steps of S1: crushing and wet-grinding the guinea bauxite, and then dissolving out to obtain ore pulp; s2: diluting ore pulp, and performing sedimentation separation to obtain crude liquid and underflow red mud respectively; the crude liquid is filtered to obtain semen; the underflow red mud enters a washing tank for washing, the washing tank overflows and flows back to the pulp diluted by S2, and the underflow red mud enters a red mud yard; s3: adding lime milk into the washing tank; c in the lime milk a O f The concentration of the lime milk is 100-150g/L, and the addition amount of the lime milk is 1-5% of the overflow amount of the washing tank. According to the invention, lime milk is directly added into the washing tank for causticizing reaction, a causticizing system is not additionally increased, energy consumption is not additionally increased, personnel operation is not additionally arranged, the causticizing rate reaches 70-80%, the alumina loss is only 5-8%, and the effect is remarkable.
Description
Technical Field
The invention relates to the technical field of chemical industry, in particular to a causticizing method in a process of producing alumina from guinea bauxite.
Background
In the alumina production process, sodium carbonate in the flow is mainly brought in for the following reasons: 1. bauxite contains carbonate minerals and lime as an additive is often carried over into the limestone due to insufficient calcination, and these carbonates react with caustic to ultimately produce sodium carbonate. 2. Bauxite contains organic matter, and some additives such as flocculating agent, scale inhibitor and the like also contain organic matter, and part of the organic matter reacts with caustic alkali to finally generate sodium carbonate. 3. The carbon dioxide in the air of the seed separation system reacts with caustic to form sodium carbonate.
The formation of the sodium carbonate not only consumes caustic alkali to cause the increase of alkali consumption, but also is easy to cause blockage in the dissolution, flash evaporation and precipitation, and precipitation on the surface of evaporation heat exchange to cause the reduction of heat exchange efficiency, and simultaneously can cause difficulty in classification and sedimentation.
In the prior art, in order to reduce sodium carbonate in the alumina production process and eliminate the adverse effect caused by sodium carbonate, alumina enterprises generally have two methods: firstly, evaporating and concentrating a sodium aluminate solution in an evaporation process, then adding lime milk for causticizing, and causticizing sodium carbonate into sodium hydroxide, wherein the causticizing rate of the method is 85-90%, and the alumina loss is 10-20%; secondly, part of the washing tank with higher concentration in the washing system overflows and is led out, and then lime milk is added for causticizing, the causticizing rate of the method is less than 50%, and the alumina loss is more than 30%. Both methods require the establishment of additional causticizing systems, separate causticizing tanks, a matched stirring system, a solid-liquid separation settling tank and a pumping system to send overflow and bottom streams to different places, and steam to heat causticized slurry to a certain temperature. Therefore, the whole causticizing system is numerous in equipment, electricity consumption and steam consumption are additionally increased, and personnel operation is also required to be arranged. Therefore, the existing causticizing process is improved, and on the premise of a certain causticizing rate and low alumina loss, a great amount of investment can be saved, and the energy consumption is reduced, so that the operation is simple and convenient.
Disclosure of Invention
The invention solves the technical problems of large investment and high energy consumption of an extra causticization process in the alumina production process in the prior art, and provides a causticization method in the process of producing alumina from guinea bauxite.
A method of causticizing in a process for producing alumina from guinea bauxite, comprising the steps of:
s1: crushing and wet-grinding the guinea bauxite, and then dissolving out to obtain ore pulp;
s2: diluting ore pulp, and performing sedimentation separation to obtain crude liquid and underflow red mud respectively; the crude liquid is filtered to obtain semen; the underflow red mud enters a washing tank for washing, the washing tank overflows and flows back to the pulp diluted by S2, and the underflow red mud is discharged to the red mud yard;
s3: adding lime milk into the washing tank; c in the lime milk a O f The concentration of the lime milk is 100-150g/L, and the addition amount of the lime milk is 1-5% of the overflow amount of the washing tank.
Further, when the lime milk is added into the washing tank, the temperature of the washing tank is 75-95 ℃, and the overflow NT concentration of the washing tank is 5-50g/L.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, lime milk is directly added into a washing tank for causticizing reaction, a causticizing solution is overflow of the washing tank, causticizing slag is settled to the tank bottom along with red mud, a causticizing system is not additionally increased, energy consumption is not additionally increased, and personnel operation is not additionally arranged; meanwhile, the causticizing rate reaches 70-80%, so that sodium carbonate is sufficiently prevented from accumulating in the process, the alumina loss is only 5-8%, the alumina loss rate is remarkably lower than that of two traditional causticizing systems, and the effect is remarkable.
Description of the drawings:
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a process flow diagram of control group 6 according to the present invention;
fig. 3 is a process flow diagram of control group 7 according to the present invention.
Detailed Description
The invention is further illustrated by the following examples and experiments.
Example 1
This embodiment is an improvement of the causticizing process in the bayer process alumina production process in the prior art, and the specific alumina production process is shown in fig. 1, and the causticizing method in the guinea bauxite alumina production process in this embodiment includes the following steps:
s1: crushing and wet-grinding the guinea bauxite, and then dissolving out to obtain ore pulp;
s2: diluting ore pulp in a diluting tank, and then entering a separating tank for sedimentation separation to obtain crude liquid and underflow red mud respectively; the crude liquid is filtered to obtain semen; the underflow red mud enters a washing tank for washing, the washing tank overflows and flows back to the pulp (namely a diluting tank) diluted by S2, and the underflow red mud enters a red mud yard;
s3: adding lime milk into the washing tank, wherein the concentration of NT overflowed from the washing tank is 50 g/L; the concentration of CaOf in the lime milk is 150g/L, the addition amount of the lime milk is 5% of the overflow amount of the washing tank, and the temperature of the washing tank is 95 ℃.
Example 2
This embodiment is an improvement of the causticizing process in the bayer process alumina production process in the prior art, and the specific alumina production process is shown in fig. 1, and the causticizing method in the guinea bauxite alumina production process in this embodiment includes the following steps:
s1: crushing and wet-grinding the guinea bauxite, and then dissolving out to obtain ore pulp;
s2: diluting ore pulp in a diluting tank, and then entering a separating tank for sedimentation separation to obtain crude liquid and underflow red mud respectively; the crude liquid is filtered to obtain semen; the underflow red mud enters a washing tank for washing, the washing tank overflows and flows back to the pulp (namely a diluting tank) diluted by S2, and the underflow red mud enters a red mud yard;
s3: adding lime milk into the washing tank, wherein the concentration of NT overflowed from the washing tank is 5 g/L; the concentration of CaOf in the lime milk is 100g/L, the addition amount of the lime milk is 1% of the overflow amount of the washing tank, and the temperature of the washing tank is 75 ℃.
Example 3
This embodiment is an improvement of the causticizing process in the bayer process alumina production process in the prior art, and the specific alumina production process is shown in fig. 1, and the causticizing method in the guinea bauxite alumina production process in this embodiment includes the following steps:
s1: crushing and wet-grinding the guinea bauxite, and then dissolving out to obtain ore pulp;
s2: diluting ore pulp in a diluting tank, and then entering a separating tank for sedimentation separation to obtain crude liquid and underflow red mud respectively; the crude liquid is filtered to obtain semen; the underflow red mud enters a washing tank for washing, the washing tank overflows and flows back to the pulp (namely a diluting tank) diluted by S2, and the underflow red mud enters a red mud yard;
s3: adding lime milk into the washing tank, wherein the concentration of NT overflowed from the washing tank is 20 g/L; the concentration of CaOf in the lime milk is 120g/L, the adding amount of the lime milk is 3% of the overflow amount of the washing tank, and the temperature of the washing tank is 90 ℃.
Control group 1
One method of causticizing the process of producing alumina from guinea bauxite in control group 1 was the same as that of example 1, except that the temperature of the washing tank was 100 ℃ when lime milk was added to the washing tank in control group 1.
Control group 2
One method of causticizing control group 2 in the process of producing alumina from guinea bauxite was the same as that of example 1, except that the temperature of the washing tank was 65 ℃ when lime milk was added to the washing tank in control group 2.
Control group 3
One method of causticizing control 3 in the process of producing alumina from guinea bauxite was the same as that of example 1, except that control 3 added lime milk at an overflow NT concentration of 60g/L in the wash tank.
Control group 4
One method of causticizing control 4 in the process of producing alumina from guinea bauxite was the same as in example 1, except that control 4 added milk of lime at an overflow NT concentration of 2g/L in the wash tank.
Control group 5
One method of causticizing in the process of producing alumina from guinea bauxite in control group 5 was the same as in example 1, except that in control group 5, the lime milk was added in an amount of 8% of the overflow amount of the wash tank.
Control group 6
The control group 6 was processed as follows: the part of the overflow of the washing tank with higher concentration in the washing system is led out and heated, and then lime milk is added for causticizing. Specifically, referring to FIG. 2, 4 causticizing tanks with stirring are provided, and a continuous causticizing process is adopted to send primary washing liquid or secondary washing liquid of the washing tank and lime milk simultaneouslyIntroducing into a first causticizing tank, controlling the overflow NT concentration of the washing tank to 30g/l, controlling the solid content of lime milk to 160g/l, and controlling the addition amount to [ CaO ]]/[Na 2 O c ]=1.2. The causticized slurry flows from the first causticizing tank to each causticizing tank in turn, and each causticizing tank is additionally provided with a steam pipeline to be heated to 85 ℃ for a total residence time of 2h. And (5) returning the causticized slurry to the red mud sedimentation washing process.
Control group 7
Referring to FIG. 3, the causticizing process of the control group 7 is to continue evaporating part of the evaporating mother liquor to NT > 300g/l by a forced circulation evaporator to precipitate carbonate, separating by a settling tank, filtering by a salt filter, dissolving in a salt dissolving tank, mixing the dissolved salt and lime milk in a mixing tank, introducing into a causticizing tank in a continuous causticizing process for causticizing, controlling the causticizing temperature to 95 ℃, controlling the lime milk concentration to 160g/l, and controlling the lime milk adding amount to [ CaO ]]/[Na 2 O c ]=1.2, causticizing time is 2h. Separating by a filter after causticization, and returning causticized slag to a red mud sedimentation washing process.
The causticizing rate and alumina loss in examples 1 to 3 and in the control groups 1 to 7 are shown in Table 1 below.
TABLE 1
As can be seen from table 1, the causticizing rate of examples 1 to 3 is slightly lower than that of the control group 7 and is significantly higher than that of the control group 6, and the alumina loss of examples 1 to 3 is significantly lower than that of the control group 6 and the control group 7, which means that the lime milk added into the washing tank for causticizing has a remarkable causticizing technical effect compared with the prior art, and the lime milk is directly added into the washing tank for causticizing reaction, the causticizing solution is overflow of the washing tank, the causticizing slag is settled to the tank bottom along with red mud, no additional energy consumption is added, no additional personnel operation is arranged, and compared with the control group 6 and the control group 7, the energy consumption is low and the labor is reduced. The comparison of the embodiment 1 and the comparison of the comparison groups 1 to 5 shows that the lime cream has different adding conditions, different causticizing rates and different alumina losses, and the technical effects of high causticizing rate and low alumina losses are achieved only when lime cream is added under the condition that the overflow NT concentration of the washing tank is 5-50g/L, the adding amount of the lime cream is 1-5% of the overflow amount of the washing tank, and the temperature of the washing tank is 75-95 ℃. The lime milk is added into the washing tank for causticizing, and the causticizing conditions are strictly limited, so that the causticizing effect is remarkable.
The foregoing description is directed to the preferred embodiments of the present invention, but the embodiments are not intended to limit the scope of the invention, and all equivalent changes or modifications made under the technical spirit of the present invention should be construed to fall within the scope of the present invention.
Claims (2)
1. A method of causticizing in a process for producing alumina from guinea bauxite, comprising the steps of:
s1: crushing and wet-grinding the guinea bauxite, and then dissolving out to obtain ore pulp;
s2: diluting ore pulp, and performing sedimentation separation to obtain crude liquid and underflow red mud respectively; the crude liquid is filtered to obtain semen; the underflow red mud enters a washing tank for washing, the washing tank overflows and flows back to the pulp diluted by S2, and the underflow red mud enters a red mud yard;
s3: adding lime milk into the washing tank; c in the lime milk a O f The concentration of the lime milk is 100-150g/L, and the addition amount of the lime milk is 1-5% of the overflow amount of the washing tank.
2. The method according to claim 1, wherein the temperature of the washing tank is 75-95 ℃ and the overflow NT concentration of the washing tank is 5-50g/L when lime milk is added into the washing tank.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311643934.2A CN117585699A (en) | 2023-12-04 | 2023-12-04 | Causticizing method in process of producing alumina from guinea bauxite |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311643934.2A CN117585699A (en) | 2023-12-04 | 2023-12-04 | Causticizing method in process of producing alumina from guinea bauxite |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117585699A true CN117585699A (en) | 2024-02-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311643934.2A Pending CN117585699A (en) | 2023-12-04 | 2023-12-04 | Causticizing method in process of producing alumina from guinea bauxite |
Country Status (1)
| Country | Link |
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| CN (1) | CN117585699A (en) |
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2023
- 2023-12-04 CN CN202311643934.2A patent/CN117585699A/en active Pending
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