CN115415292A - Red mud wet dealkalization method and treatment system - Google Patents
Red mud wet dealkalization method and treatment system Download PDFInfo
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- CN115415292A CN115415292A CN202211201647.1A CN202211201647A CN115415292A CN 115415292 A CN115415292 A CN 115415292A CN 202211201647 A CN202211201647 A CN 202211201647A CN 115415292 A CN115415292 A CN 115415292A
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- 238000000034 method Methods 0.000 title claims abstract description 72
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 90
- 238000003756 stirring Methods 0.000 claims abstract description 68
- 239000002002 slurry Substances 0.000 claims abstract description 62
- 239000010440 gypsum Substances 0.000 claims abstract description 53
- 229910052602 gypsum Inorganic materials 0.000 claims abstract description 53
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 45
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 45
- 238000002156 mixing Methods 0.000 claims abstract description 23
- 239000002131 composite material Substances 0.000 claims abstract description 22
- 239000007788 liquid Substances 0.000 claims abstract description 16
- 238000000926 separation method Methods 0.000 claims abstract description 14
- 239000007787 solid Substances 0.000 claims abstract description 6
- 238000010000 carbonizing Methods 0.000 claims abstract description 4
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 28
- 235000019270 ammonium chloride Nutrition 0.000 claims description 14
- 239000004094 surface-active agent Substances 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims description 2
- 239000003513 alkali Substances 0.000 abstract description 34
- 230000001603 reducing effect Effects 0.000 abstract description 7
- 230000009467 reduction Effects 0.000 abstract description 5
- 230000007774 longterm Effects 0.000 abstract description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 18
- 230000008719 thickening Effects 0.000 description 10
- 239000008394 flocculating agent Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- 239000011734 sodium Substances 0.000 description 7
- 238000003763 carbonization Methods 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
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- 239000003814 drug Substances 0.000 description 5
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
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- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- 229910021532 Calcite Inorganic materials 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 229910004283 SiO 4 Inorganic materials 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
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- HOOWDPSAHIOHCC-UHFFFAOYSA-N dialuminum tricalcium oxygen(2-) Chemical compound [O--].[O--].[O--].[O--].[O--].[O--].[Al+3].[Al+3].[Ca++].[Ca++].[Ca++] HOOWDPSAHIOHCC-UHFFFAOYSA-N 0.000 description 1
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- 229910052665 sodalite Inorganic materials 0.000 description 1
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 description 1
- RYYKJJJTJZKILX-UHFFFAOYSA-M sodium octadecanoate Chemical compound [Na+].CCCCCCCCCCCCCCCCCC([O-])=O RYYKJJJTJZKILX-UHFFFAOYSA-M 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
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- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/70—Chemical treatment, e.g. pH adjustment or oxidation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/30—Destroying solid waste or transforming solid waste into something useful or harmless involving mechanical treatment
- B09B3/32—Compressing or compacting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/30—Destroying solid waste or transforming solid waste into something useful or harmless involving mechanical treatment
- B09B3/38—Stirring or kneading
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- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Treatment Of Sludge (AREA)
Abstract
The invention discloses a wet dealkalization method and a treatment system for red mud. A wet dealkalization method for red mud comprises the following steps: (1) Introducing carbon dioxide gas into the red mud to be treated, and carbonizing; (2) Mixing and stirring the red mud slurry carbonized in the step (1) and the composite gypsum slurry, and calcifying; (3) And (3) carrying out solid-liquid separation on the calcified red mud slurry obtained in the step (2) to obtain solid, namely dealkalized red mud. The red mud wet dealkalization method utilizes the combination of carbon dioxide and gypsum to reduce alkali and control alkali, can obviously reduce the pH value, the alkalization degree, the free alkali and the bound alkali content of the red mud, reduce the alkalinity to the available range, and ensure that the alkali reducing effect has stability in a long term due to the reduction of the bound alkali content.
Description
Technical Field
The invention relates to the technical field of solid waste treatment, in particular to a red mud wet dealkalization method and a treatment system.
Background
Red mud is a solid waste produced in the industrial production process of alumina. According to statistics, 0.8-1.5 tons of red mud is additionally generated for each 1 ton of alumina. However, due to the strong alkaline characteristics of the red mud, the red mud is difficult to be recycled, and a large amount of red mud is accumulated. A large amount of red mud cannot be fully and effectively utilized, and can only be stacked by a large-area yard, so that the development of the alumina industry is hindered while serious pollution is caused to the environment. Because the red mud has various activities, the red mud with reduced alkalinity can be used for manufacturing glass, cement, roadbed materials and the like, and has wide application prospect.
At present, the methods for reducing alkali in red mud mainly comprise a water washing method, an acid leaching method, a carbonization method, a biological alkali regulation method and the like. However, the above methods generally have the disadvantages of long time and high cost, and are not suitable for large-scale industrial treatment of red mud. For example: the water washing method has large water consumption, poor dealkalization effect and poor technical economy; the acid leaching method can effectively remove alkali, but has the problems of high cost, difficult acid recovery and the like, and is not suitable for industrial production; the carbonization method has long time, the dealkalization rate can only reach about 40 to 50 percent, and the requirement of red mud reutilization can not be met.
Disclosure of Invention
In order to overcome the problem that the existing red mud cannot be dealkalized effectively, one of the purposes of the invention is to provide a method for dealkalizing the red mud by a wet method; the invention also aims to provide a red mud wet dealkalization treatment system.
The concept of the invention is as follows:
the alkalinity of the red mud mainly comes from free alkali and combined alkali, and the free alkali in the red mud mainly comprises NaOH and Na 2 CO 3 、NaHCO 3 、NaAl(OH) 4 Etc. the chemically bound alkali of the alkali-bound red mud mainly comprises calcite (CaCO) 3 ) And sodalite ([ Na ] 6 Al 6 Si 6 O 24 ]2NaX or Na 2 X]) Cancrinite ([ Na ] 6 Al 6 Si 6 O 24 ]·2[CaCO 3 ]) Tricalcium aluminate (TCA, ca) 3 Al 2 (OH) 12 ) Hydrated garnet (Ca) 3 Al 2 (SiO 4 ) x (OH) 12-4x ) In the prior art, such as a water washing method, an acid gas neutralization method and the like, only free alkali can be well removed, but bound alkali cannot be effectively removed.
The first aspect of the invention provides a wet dealkalization method for red mud, which comprises the following steps:
(1) Introducing carbon dioxide gas into the red mud to be treated, and carbonizing;
(2) Mixing and stirring the red mud slurry carbonized in the step (1) and the composite gypsum slurry, and calcifying;
(3) And (3) carrying out solid-liquid separation on the calcified red mud slurry obtained in the step (2) to obtain solid, namely dealkalized red mud.
Preferably, in the red mud wet dealkalization method, in the step (1), the solid content of the red mud to be treated is 20-30wt%.
Preferably, in the red mud wet dealkalization method, in the step (1), the mass-to-volume ratio of the red mud to the carbon dioxide in the red mud to be treated is (30-45) kg:1L; further preferably, the mass-volume ratio of the red mud to the carbon dioxide in the red mud slurry to be treated is (35-40) kg:1L of the compound.
Preferably, in the red mud wet dealkalization method, in the step (1), the introduction speed of carbon dioxide is 3-6L/min; the red mud to be treated cannot be effectively carbonized at an excessively high or excessively low feeding speed.
Preferably, in the red mud wet dealkalization method, in the step (1), the carbon dioxide is introduced for 25-40min.
Preferably, in the red mud wet dealkalization method, in the step (2), the composite gypsum slurry is a mixed solution of gypsum and ammonium chloride; the inventor finds that the ammonium chloride is added into the composite gypsum slurry, so that the gypsum is dissolved more fully, the alkalinity reducing effect is more obvious when the ammonium chloride is added into a red mud system and stirred together, and further optimization is achieved.
Further preferably, the mass ratio of the gypsum to the ammonium chloride in the composite gypsum slurry is (40-55): 1; still further preferably, the mass ratio of gypsum to ammonium chloride is (45-50): 1; when the adding amount of the ammonium chloride is too small, the alkali reducing effect is not obvious, when the adding amount of the ammonium chloride is too large, the alkali reducing effect cannot be further improved, the alkali reducing cost is increased, and the process economic benefit is reduced.
Preferably, in the red mud wet dealkalization method, in the step (2), the content of gypsum in the composite gypsum slurry is 1.6-5wt%; the mass ratio of the composite gypsum slurry to the red mud in the carbonized red mud slurry is 1: (8-12).
Preferably, in the red mud wet dealkalization method, in the step (2), a surfactant is added while mixing and stirring, and the surfactant can be selected from at least one of sodium dodecyl sulfate, sodium fatty alcohol-polyoxyethylene ether sulfate, sodium dodecyl benzene sulfonate, alkylolamide, sodium olefin sulfonate, sodium linear alkyl benzene sulfonate and sodium stearate; the red mud particles in the system are easy to gather together, so that the binding alkali is wrapped, and the solid particle aggregate can be divided into fine particles by the surfactant, so that the fine particles are dispersed and suspended in the solution, and the effect of releasing the binding alkali is further realized; more preferably, the mass ratio of the surfactant to the red mud in the carbonized red mud slurry is (0.1-0.2): 100.
preferably, in the red mud wet dealkalization method, in the step (2), the stirring time is 8-15min.
Preferably, in the method for dealkalizing the red mud by the wet method, in the step (3), a coagulant and/or a flocculant are added when the calcified red mud is subjected to solid-liquid separation; further preferably, when the calcified red mud slurry is subjected to solid-liquid separation, a flocculating agent is added, and a coagulant and/or a flocculating agent are/is added to accelerate the solid-liquid separation of the red mud slurry; still further preferably, the mass ratio of the red mud and the flocculating agent in the calcified red mud slurry is (42-45): 1.
the second aspect of the invention provides a treatment system for implementing the red mud wet dealkalization method, which comprises a tubular carbonizer, a red mud stirring tank, a mixing and stirring tank and a solid-liquid separation device which are connected in sequence; the mixing and stirring tank is also connected with the gypsum stirring tank.
Preferably, in the treatment system, the tubular carbonizer is in a vertical cylindrical shape, a screw shaft is arranged in the tubular carbonizer, and two openings are arranged at the bottom of the tubular carbonizer, wherein one opening is used for the inlet of the red mud slurry, and the other opening is used for the inlet of the carbon dioxide gas.
Further preferably, the rotating speed of the spiral shaft of the tubular carbonizer is 50-70r/min; still further preferably, the rotating speed of the spiral shaft of the tubular carbonizer is 55-65r/min; the tubular carbonizer is used for premixing carbon dioxide and red mud slurry, carbon dioxide gas enters the tubular carbonizer, the red mud slurry in the red mud stirring tank is conveyed to the tubular carbonizer through a pump, the red mud slurry and the carbon dioxide are premixed in the tubular carbonizer and then conveyed to the red mud stirring tank for further carbonization. The rotating speed of the spiral shaft of the tubular carbonizer has important influence on the premixing alkali reduction effect of the tubular carbonizer, and the good treatment effect cannot be realized when the rotating speed is too low or too high.
Preferably, in the treatment system, a stirring paddle is arranged in the red mud stirring tank, and the rotating speed of the stirring paddle is 50-70r/min.
Preferably, in the treatment system, a stirring paddle is arranged in the gypsum stirring tank, and the rotating speed of the stirring paddle is 50-70r/min; preparing composite gypsum slurry in a gypsum stirring tank, adding water, gypsum and ammonium chloride, stirring and mixing for more than or equal to 8min, and ensuring that the gypsum is fully dissolved.
Preferably, in the treatment system, a mixing stirring tank is provided with a stirring paddle, the rotating speed of the stirring paddle is 50-70r/min, and the stirring time is 15-30min.
Preferably, in the treatment system, the solid-liquid separation device comprises a thickening tank and a pressure filter, wherein a coagulant and/or a flocculant is added into the thickening tank, and the coagulant and/or the flocculant are added to accelerate the solid-liquid separation of the red mud slurry in the thickening tank.
Further preferably, a stirring paddle is arranged in the thickening tank.
The third aspect of the invention provides dealkalized red mud which is obtained by the treatment of the red mud wet dealkalization method.
The invention has the beneficial effects that:
1. the invention adopts a mode of combining carbonization and calcification for alkali reduction, and has obvious alkali reduction effect. The carbon dioxide and the gypsum are combined to reduce alkali and control alkali, so that the pH value, the alkalization degree, the free alkali and the bound alkali content of the red mud can be obviously reduced, the alkalinity is reduced to an available range, and the alkali reducing effect has stability in a long term due to the reduction of the bound alkali content.
2. The red mud dealkalization method has simple process and low cost. Compared with the existing red mud alkali reduction process, such as the existing lime dealkalization method, the process needs temperature rise and pressure rise, has higher requirements on devices and has complex flow; for example, the existing flocculation and inorganic acid neutralization method has high cost and is not easy to popularize, but the method has simple whole production process flow, can treat the red mud in a large scale, and uses extremely cheap medicines and is easy to popularize.
3. The red mud dealkalization method has good dealkalization effect and high dealkalization efficiency. The method provided by the invention can reduce the pH value of the red mud leaching solution to 8.5 within about 1h, and the existing alkali reduction process by the carbon dioxide gypsum method needs more than 6h due to low gypsum solubility and slow dissolution process, so that the reaction time is too long.
4. According to the invention, through optimizing the modes of carbonization and calcification and the process formula, the weight gain of the treated red mud is controlled to be 10-15%. Compared with the prior art which adopts the dry weight ratio of the gypsum to the red mud of 1:6, the dry weight ratio of the gypsum to the red mud is controlled to be about 1.
5. The red mud wet dealkalization treatment system creatively uses the tubular carbonizer, the center in the tubular carbonizer is provided with the spiral shaft, and the red mud can be stirred for multiple times after entering the tubular carbonizer; meanwhile, carbon dioxide is introduced from the lower end air hole, the contact area of the carbon dioxide and the red mud slurry is large, carbon dioxide bubbles introduced to the bottom can float upwards, the reaction area is greatly increased, the carbon dioxide bubbles are cut by the spiral shaft at the same time to form more tiny bubbles, the bubbles are stirred, the resistance of the liquid film side of the gas-liquid interface is reduced, the mass transfer of gas to a liquid phase is increased, the dealkalization reaction rate is increased, and the reaction efficiency is obviously improved.
Drawings
FIG. 1 is a diagram of a red mud wet dealkalization treatment system of the invention.
Fig. 2 is a schematic view of a red mud wet dealkalization treatment system of an embodiment.
Detailed Description
The embodiments of the present invention will be described in detail below, and the embodiments described by referring to the drawings are exemplary only for the purpose of illustrating the present invention and are not to be construed as limiting the present invention.
The present invention will be described in further detail with reference to specific examples.
The starting materials, reagents or equipment used in the examples are, unless otherwise specified, either conventionally commercially available or may be obtained by methods known in the art. Unless otherwise indicated, the testing or testing methods are conventional in the art.
As shown in attached figure 1, the invention provides a red mud wet dealkalization treatment system, which comprises a tubular carbonizer, a red mud stirring tank, a gypsum stirring tank, a mixing stirring tank and a solid-liquid separation device, wherein the tubular carbonizer is connected with the red mud stirring tank through a pipeline; the tubular carbonizer, the red mud stirring tank, the mixing stirring tank and the solid-liquid separation device are sequentially connected, and the gypsum stirring tank is connected with the mixing stirring tank.
The tubular carbonizer is in a vertical cylinder shape, a spiral shaft is arranged in the center of the interior of the tubular carbonizer, two openings are arranged at the bottom of the tubular carbonizer, one opening is used for allowing red mud to enter, and the other opening is used for allowing carbon dioxide gas to enter.
As shown in fig. 2, in some embodiments of the present invention, the red mud wet dealkalization treatment system includes a carbon dioxide gas tank, a tubular carbonizer, a red mud stirring tank, a circulating pump, a first sludge discharge pump, a gypsum stirring tank, a second sludge discharge pump, a mixing stirring tank, a dosing pump, a chemical tank, a third sludge discharge pump, a thickening tank, a filter press, a water return tank, and a water feeding pump.
The method for dealkalizing red mud by using the red mud wet dealkalizing treatment system according to the embodiment of the invention is described below with reference to fig. 2, and specifically comprises the following steps:
adding the red mud to be treated into a red mud stirring tank, adding a proper amount of water into the red mud stirring tank, and stirring; gas in the carbon dioxide gas tank enters a tubular carbonizer, a circulating pump simultaneously pumps red mud slurry at the bottom of a red mud stirring tank and conveys the red mud slurry to the tubular carbonizer, the carbon dioxide gas and the red mud slurry are premixed in the tubular carbonizer and finally enter the red mud stirring tank for full mixing, and the red mud slurry in the red mud stirring tank enters a mixing and stirring tank through a first sludge discharge pump;
clear water in the water return tank is added into a gypsum stirring tank through a water adding pump, meanwhile, gypsum and ammonium chloride are added into the gypsum stirring tank for stirring and mixing, and the clear water enters a mixing stirring tank through a second sludge discharge pump; adding a surfactant and water into a medicament barrel to prepare a medicament, feeding the medicament into a mixing and stirring tank through a medicament adding pump, and fully stirring in the mixing and stirring tank to realize further dealkalization of the red mud;
the red mud reacted in the mixing and stirring tank enters a thickening tank through a third sludge discharge pump for solid-liquid separation, the red mud slurry at the bottom enters a filter press for filter pressing, and harmless red mud is obtained after filter pressing; and the supernatant of the thickening tank enters a water return tank to be used for preparing gypsum slurry in a gypsum stirring tank and red mud slurry in a red mud stirring tank.
Example 1
The embodiment provides a red mud wet dealkalization method, which adopts a red mud wet dealkalization treatment system shown in the attached figure 2 for treatment, and specifically comprises the following steps:
(1) Carbonizing red mud and preparing composite gypsum slurry: adding the original red mud and water into a red mud stirring tank together, opening a carbon dioxide gas tank, enabling carbon dioxide gas to enter a tubular carbonizer, conveying red mud slurry in the red mud stirring tank into the tubular carbonizer through a circulating pump, and premixing the carbon dioxide gas and the red mud slurry in the tubular carbonizer; then the red mud enters a red mud stirring tank for comprehensive carbonization; meanwhile, gypsum, ammonium chloride and water are added into a gypsum stirring tank and stirred together to prepare composite gypsum slurry;
(2) Discharging the red mud slurry and the composite gypsum slurry into a mixing and stirring tank through a mud discharging pump, adding a surfactant, and stirring again;
(3) Discharging the red mud fully stirred into a thickening tank, and adding a flocculating agent to perform rapid solid-liquid separation;
(4) Quickly draining the settled red mud at the bottom of the thickening tank through a filter press to obtain the dealkalized red mud.
The technological parameters in the whole process are as follows:
in the step (1), the raw red mud: water =1:5, controlling the solid content in the red mud stirring tank to be 20-25%; before carbon dioxide is not introduced, the pH value of the supernatant of the red mud stirring tank is 11.4-11.6; red mud in red mud slurry: carbon dioxide =35kg:1L, the flow rate of carbon dioxide is 5L/min, the introducing time is 30min, and the pH value is 9.12 after the carbon dioxide is introduced for treatment;
in the step (1), every 5kg of water in the composite gypsum slurry contains 4g of ammonium chloride and 189.4g of desulfurized gypsum, and the stirring time in the preparation process is 10-15min;
in the step (2), the adding amount of the composite gypsum slurry is 10 percent of the total amount of the red mud in the red mud slurry;
in the step (2), red mud in red mud slurry: surfactant =100: (0.1-0.2), stirring for 10min;
in the step (3), red mud in red mud slurry: flocculant = (42-45): 1, standing in a thickening tank for 18-20min;
in the step (4), the pressure value of the filter press is 30t/m of the thrust of the filter press 2 。
In order to test whether the dealkalized red mud has the alkali return phenomenon or not, the red mud mixed solution obtained by adding the flocculant in the step (3) is placed in a barrel, the initial pH is measured to be 8.07, then the mixture is stood and stirred, and the pH is measured, wherein the specific operation process and the pH change are shown in the following table 1:
TABLE 1
As can be seen from the data in Table 1, the wet dealkalization method for red mud in the embodiment has no alkali return phenomenon after a long time.
Example 2
The red mud wet dealkalization method of the present embodiment is different from the red mud wet dealkalization method of the embodiment 1 in that in the step (1) of the present embodiment, the ratio of the red mud to the carbon dioxide in the red mud slurry =20kg:1L, and the pH was found to be 10.12 after the treatment with carbon dioxide.
Example 3
The difference between the red mud wet dealkalization method of the embodiment and the embodiment 1 is that in the step (1) of the embodiment, the ratio of the red mud to the carbon dioxide in the red mud slurry is =25kg:1L, and the pH was found to be 9.87 after the treatment with carbon dioxide.
Example 4
The difference between the red mud wet dealkalization method of the embodiment and the embodiment 1 is that in the step (1) of the embodiment, the ratio of the red mud to the carbon dioxide in the red mud slurry is =30kg:1L, and the pH was found to be 9.53 after the treatment with carbon dioxide.
Example 5
The difference between the red mud wet dealkalization method of the embodiment and the embodiment 1 is that in the step (1) of the embodiment, the ratio of the red mud to the carbon dioxide in the red mud slurry is =40kg:1L, and the pH was found to be 9.15 after the treatment with carbon dioxide.
Example 6
The red mud wet dealkalization method of the present embodiment is different from the red mud wet dealkalization method of the embodiment 1 in that in the step (1) of the present embodiment, the ratio of the red mud to the carbon dioxide in the red mud slurry is =45kg:1L, and the pH was found to be 9.18 after the treatment with carbon dioxide.
Example 7
The difference between the red mud wet dealkalization method of the embodiment and the embodiment 1 is that in the step (2) of the embodiment, the adding amount of the composite gypsum slurry is 5% of the total amount of the red mud; and (4) measuring the pH value of the red mud mixed liquor after the flocculating agent is added in the step (3) to be 8.49.
Example 8
The difference between the red mud wet dealkalization method of the embodiment and the embodiment 1 is that in the step (2) of the embodiment, the adding amount of the composite gypsum slurry is 15% of the total amount of the red mud; and (4) measuring the pH value of the red mud mixed liquor after the flocculating agent is added in the step (3) to be 8.39.
Example 9
The difference between the red mud wet dealkalization method of the embodiment and the embodiment 1 is that in the step (2) of the embodiment, the adding amount of the composite gypsum slurry is 20% of the total amount of the red mud; and (4) measuring the pH value of the red mud mixed liquor after the flocculating agent is added in the step (3) to be 8.42.
Example 10
The difference between the red mud wet dealkalization method of the embodiment and the embodiment 1 is that in the step (2) of the embodiment, the adding amount of the composite gypsum slurry is 25% of the total amount of the red mud; and (4) measuring the pH value of the red mud mixed liquor after the flocculant is added in the step (3) to be 8.47.
Comparative example 1
The difference between the red mud wet dealkalization method of the comparative example and the example 1 is that in the step (1) of the comparative example, no ammonium chloride is added into the composite gypsum slurry, the pH of the red mud mixed solution after the flocculating agent is added in the step (3) is measured to be 9.48, and the pH is rebounded within the following 1-2 days.
Comparative example 2
The red mud wet dealkalization method of the comparative example is different from the example 1 in that in the step (1) of the comparative example, carbon dioxide is introduced by replacing a tubular carbonizer with a common air pipe (D12 x 8), carbon dioxide gas and red mud slurry are mixed in a red mud stirring tank, and the pH value after the treatment of introducing the carbon dioxide is measured to be 10.12.
Although the present invention has been described with reference to the above embodiments, it should be understood that the present invention is not limited thereto, and various changes, substitutions, and alterations can be made without departing from the spirit and scope of the invention.
Claims (10)
1. A wet dealkalization method for red mud is characterized by comprising the following steps:
(1) Introducing carbon dioxide gas into the red mud to be treated, and carbonizing;
(2) Mixing and stirring the red mud slurry carbonized in the step (1) and the composite gypsum slurry, and calcifying;
(3) And (3) carrying out solid-liquid separation on the calcified red mud slurry obtained in the step (2) to obtain solid, namely dealkalized red mud.
2. The red mud wet dealkalization method according to claim 1, wherein in the step (1), the mass volume ratio of the red mud to the carbon dioxide in the red mud to be treated is (30-45) kg:1L of the compound.
3. The red mud wet dealkalization method according to claim 1, characterized in that in the step (1), the introduction speed of the carbon dioxide is 3-6L/min.
4. The red mud wet dealkalization method according to claim 1, characterized in that in the step (2), the composite gypsum slurry is a mixed solution of gypsum and ammonium chloride.
5. The red mud wet dealkalization method according to claim 4, characterized in that in the step (2), the mass ratio of the gypsum to the ammonium chloride is (40-55): 1.
6. the red mud wet dealkalization method according to claim 1, characterized in that in the step (2), the gypsum content in the composite gypsum slurry is 1.6-5wt%; the mass ratio of the composite gypsum slurry to the red mud in the carbonized red mud slurry is 1: (8-12).
7. The red mud wet dealkalization method according to claim 1, characterized in that in the step (2), a surfactant is added while the mixing and stirring are carried out.
8. A treatment system for implementing the red mud wet dealkalization method of any one of claims 1 to 7, which is characterized by comprising a tubular carbonizer, a red mud stirring tank, a mixing stirring tank and a solid-liquid separation device which are connected in sequence; the mixing and stirring tank is also connected with the gypsum stirring tank.
9. The treatment system according to claim 8, wherein the tube carbonizer is of a vertical cylindrical shape, provided with a screw shaft inside and two openings at the bottom, one for the red mud slurry and the other for the carbon dioxide gas.
10. Dealkalized red mud, which is obtained by treating the red mud with the wet dealkalization method according to any one of claims 1 to 7.
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