CN113106536A - Method for preparing calcium sulfate whiskers from calcium chloride solution and sodium sulfate as phosphoric acid byproducts - Google Patents
Method for preparing calcium sulfate whiskers from calcium chloride solution and sodium sulfate as phosphoric acid byproducts Download PDFInfo
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- CN113106536A CN113106536A CN202110262674.9A CN202110262674A CN113106536A CN 113106536 A CN113106536 A CN 113106536A CN 202110262674 A CN202110262674 A CN 202110262674A CN 113106536 A CN113106536 A CN 113106536A
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- calcium
- calcium sulfate
- phosphoric acid
- solution
- calcium chloride
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- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 title claims abstract description 116
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 title claims abstract description 80
- 238000000034 method Methods 0.000 title claims abstract description 59
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 title claims abstract description 52
- 229910000147 aluminium phosphate Inorganic materials 0.000 title claims abstract description 40
- 239000006227 byproduct Substances 0.000 title claims abstract description 40
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 title claims abstract description 37
- 229910052938 sodium sulfate Inorganic materials 0.000 title claims abstract description 37
- 235000011152 sodium sulphate Nutrition 0.000 title claims abstract description 36
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 48
- 239000013078 crystal Substances 0.000 claims abstract description 24
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 claims abstract description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000001354 calcination Methods 0.000 claims abstract description 12
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 239000002244 precipitate Substances 0.000 claims abstract description 6
- 230000002378 acidificating effect Effects 0.000 claims abstract description 5
- 230000020477 pH reduction Effects 0.000 claims abstract description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 4
- 159000000007 calcium salts Chemical class 0.000 claims abstract description 4
- 229940095672 calcium sulfate Drugs 0.000 claims description 48
- 239000000243 solution Substances 0.000 claims description 31
- 238000006243 chemical reaction Methods 0.000 claims description 15
- 239000011259 mixed solution Substances 0.000 claims description 14
- 238000001914 filtration Methods 0.000 claims description 12
- 239000001110 calcium chloride Substances 0.000 claims description 10
- 229910001628 calcium chloride Inorganic materials 0.000 claims description 10
- 239000000706 filtrate Substances 0.000 claims description 10
- 238000004321 preservation Methods 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 8
- 229940095564 anhydrous calcium sulfate Drugs 0.000 claims description 7
- 238000005406 washing Methods 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- 238000003756 stirring Methods 0.000 claims description 5
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 3
- 239000000920 calcium hydroxide Substances 0.000 claims description 3
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 3
- 238000007865 diluting Methods 0.000 claims description 2
- 238000000746 purification Methods 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 239000002994 raw material Substances 0.000 abstract description 8
- 238000005265 energy consumption Methods 0.000 abstract description 6
- 238000002360 preparation method Methods 0.000 abstract description 6
- 230000008901 benefit Effects 0.000 abstract description 4
- 230000008569 process Effects 0.000 abstract description 4
- 229910052602 gypsum Inorganic materials 0.000 description 9
- 239000010440 gypsum Substances 0.000 description 7
- 239000000203 mixture Substances 0.000 description 6
- 229910052925 anhydrite Inorganic materials 0.000 description 4
- 238000000879 optical micrograph Methods 0.000 description 4
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 3
- 235000011941 Tilia x europaea Nutrition 0.000 description 3
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 3
- 238000009776 industrial production Methods 0.000 description 3
- 239000004571 lime Substances 0.000 description 3
- 239000008267 milk Substances 0.000 description 3
- 210000004080 milk Anatomy 0.000 description 3
- 235000013336 milk Nutrition 0.000 description 3
- 239000012086 standard solution Substances 0.000 description 3
- 238000006467 substitution reaction Methods 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000002783 friction material Substances 0.000 description 2
- 238000001027 hydrothermal synthesis Methods 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- -1 papermaking Substances 0.000 description 2
- 239000007832 Na2SO4 Substances 0.000 description 1
- 239000010426 asphalt Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000009970 fire resistant effect Effects 0.000 description 1
- 239000012767 functional filler Substances 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 239000011256 inorganic filler Substances 0.000 description 1
- 229910003475 inorganic filler Inorganic materials 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 239000012783 reinforcing fiber Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
- 239000003566 sealing material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000012745 toughening agent Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/46—Sulfur-, selenium- or tellurium-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/60—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape characterised by shape
- C30B29/62—Whiskers or needles
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B7/00—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions
- C30B7/14—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions the crystallising materials being formed by chemical reactions in the solution
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
The invention belongs to the technical field of calcium sulfate whisker preparation, and particularly relates to a method for preparing calcium sulfate whiskers from a calcium chloride solution as a phosphoric acid byproduct and sodium sulfate, wherein the calcium chloride solution as the phosphoric acid byproduct is a calcium chloride solution as a phosphoric acid byproduct obtained by a hydrochloric acid wet process, and the calcium sulfate whiskers are prepared by an acidification method: calcium salt and sulfate generate calcium sulfate precipitate under acidic condition, the calcium sulfate precipitate is dried and dehydrated after being washed by hot water to obtain calcium sulfate hemihydrate crystal whisker, and the calcium sulfate hemihydrate crystal whisker is obtained after calcination. The method has the advantages of easily available raw materials, improved value of industrial by-products, full utilization of resources, reduction of production energy consumption due to the adoption of an acidification method for preparing the calcium sulfate whiskers, and high-whiteness, high-purity and high-content calcium sulfate whiskers.
Description
Technical Field
The invention belongs to the technical field of calcium sulfate whisker preparation, and particularly relates to a method for preparing calcium sulfate whiskers from a calcium chloride solution as a phosphoric acid byproduct and sodium sulfate.
Background
The calcium sulfate whisker is a novel high-performance inorganic material, integrates the advantages of reinforcing fiber and superfine inorganic filler, can be used as a reinforcing toughening agent or a functional filler in resin, plastic, rubber, coating, paint, papermaking, asphalt, friction and sealing materials, and can also be directly used as a filtering material, a heat insulating material, a fire-resistant heat insulating material, an infrared reflecting material and a high-insulation material for coating wires.
At present, natural gypsum is mainly used as a main raw material for preparing the calcium sulfate whisker, and the natural gypsum is an unrecoverable resource and inevitably faces the problem of exhaustion, so that the problem of searching a method for producing the calcium sulfate whisker by using the raw material capable of replacing the natural gypsum is urgently needed to be solved.
The raffinate of the hydrochloric acid wet-process phosphoric acid contains 15-30% of calcium chloride, the traditional method is to prepare calcium chloride or common gypsum, the equipment investment in the two directions is high, the energy consumption is large, the profit margin is small, and the preparation of the calcium sulfate whisker by using the raffinate of the hydrochloric acid wet-process phosphoric acid is a new development and research direction.
The generation of calcium sulfate whisker is essentially a process of dissolution, crystallization and dehydration, and the reaction formula is as follows:
Ca2++SO4 2-+2H2O→CaSO4·2H2O
CaSO4·2H2O→CaSO4·1/2H2O
CaSO4·1/2H2O→CaSO4
at present, the industrial production of calcium sulfate whisker usually adopts a hydrothermal method: the gypsum is crushed and dissolved in water, calcium sulfate dihydrate crystal whisker is converted into calcium sulfate hemihydrate crystal whisker at the temperature of about 160 ℃, and then the calcium sulfate hemihydrate crystal whisker is obtained after drying. The preparation method has high requirement on the transformation temperature and high energy consumption, and is not beneficial to resource protection.
Disclosure of Invention
In order to solve the technical problems of large consumption of raw materials of the calcium sulfate whisker and high energy consumption in preparation, the invention provides a method for preparing the calcium sulfate whisker by using a calcium chloride solution as a phosphoric acid byproduct and sodium sulfate, which has the advantages of easily obtained raw materials, relatively low energy consumption and full utilization of resources.
The invention conforms to the following reaction principle: CaCl2+Na2SO4＝CaSO4↓+2NaCl
The invention provides a method for preparing calcium sulfate whiskers from a phosphoric acid by-product calcium chloride solution and sodium sulfate, wherein the phosphoric acid by-product calcium chloride solution is a hydrochloric acid wet-process phosphoric acid by-product calcium chloride solution, and the calcium sulfate whiskers are prepared by an acidification method: calcium salt and sulfate generate calcium sulfate precipitate under acidic condition, the calcium sulfate precipitate is dried and dehydrated after being washed by hot water to obtain calcium sulfate hemihydrate crystal whisker, and the calcium sulfate hemihydrate crystal whisker is obtained after calcination.
Further, the method specifically comprises the following steps:
(1) purifying the calcium chloride solution as the byproduct of wet-process phosphoric acid production by hydrochloric acid method, filtering and extracting filtrate, adding hydrochloric acid into the filtrate to adjust the pH value of the solution to 0-3, and diluting;
(2) preparing sodium sulfate into a sodium sulfate solution, and mixing the sodium sulfate solution with the diluted calcium chloride solution;
(3) placing the mixed solution into a heat-preservation reaction device, heating and stirring the mixed solution to 110-120 ℃, and preserving heat for reaction;
(4) filtering the mixed solution after heat preservation while the mixed solution is hot, repeatedly washing the filter residue with hot water for 2-5 times, and then drying and dehydrating the filter residue to obtain calcium sulfate hemihydrate crystal whiskers;
(5) and calcining the obtained calcium sulfate hemihydrate crystal whisker to obtain the anhydrous calcium sulfate crystal whisker.
Further, in the step (1), the method of the purification treatment is: adding calcium hydroxide into the calcium chloride solution as the byproduct of wet-process phosphoric acid production by hydrochloric acid method to adjust the solution to be alkaline, and removing impurities such as iron ions in the solution. The length-diameter ratio of the product is improved by the filtration, and the added calcium hydroxide reacts with the added hydrochloric acid to generate calcium chloride which can be used as a reaction raw material and does not bring other impurities.
Further, in the step (1), the concentration of calcium chloride after dilution of the calcium chloride solution which is a byproduct of wet-process phosphoric acid by a hydrochloric acid method is 10-100 g/L.
Further, in the step (2), the concentration of the prepared sodium sulfate solution is 10-120 g/L.
Further, in the step (3), the reaction time is kept for 10-30 min.
Further, in the step (3), the heat-preserving reaction equipment is a reaction tank with a stirrer and heated by an outer jacket or a coil pipe.
Further, in the step (4), the hot water temperature is 85-100 ℃, and the drying temperature is 140-200 ℃. The hydration process of the calcium sulfate whisker can be effectively slowed down by using hot water with the temperature of 85-100 ℃ for washing.
Further, in the step (5), the calcination temperature is 500-550 ℃, and the calcination time is 0.5-1.5 h.
Further, in the step (5), the length-diameter ratio of the anhydrous calcium sulfate whisker is 60-100, the whiteness is above 90%, and the purity is above 99%.
The invention has the beneficial effects that:
1. the invention selects the calcium chloride solution as the byproduct of phosphoric acid wet process by hydrochloric acid method as the raw material, has sufficient raw material source, is different from natural gypsum, belongs to renewable resources, reduces excessive exploitation and consumption of natural gypsum, improves the value of industrial byproduct, realizes full utilization of resources and improves economic benefit.
2. The invention finds a novel method for preparing the calcium sulfate whisker, adopts an acidification method to prepare the calcium sulfate whisker, generates calcium sulfate precipitation by calcium salt and sulfate under an acidic condition, can reduce the transition temperature (the transition temperature is between 110 ℃ and 120 ℃) of the calcium sulfate whisker from dihydrate to semi-hydrate under the acidic condition, and greatly reduces the production energy consumption, effectively saves resources and reduces the production cost compared with a hydrothermal method (the transition temperature is about 160 ℃) adopted by the current industrial production.
3. The calcium sulfate whisker with high whiteness, high purity and high content is obtained by the preparation method, meets the performance requirement on the calcium sulfate whisker, and is suitable for industrial production.
Drawings
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
FIG. 1 is a flow chart of a method for preparing calcium sulfate whiskers from a calcium chloride solution as a byproduct of phosphoric acid and sodium sulfate according to the invention;
FIG. 2 is a 100-fold optical microscope image of calcium sulfate whiskers prepared in example 1;
FIG. 3 is a 100-fold optical microscope image of calcium sulfate whiskers prepared in example 2;
fig. 4 is a 100-fold optical microscope image of the calcium sulfate whiskers prepared in example 3.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
As shown in fig. 1, the method for preparing calcium sulfate whiskers from a calcium chloride solution as a byproduct of phosphoric acid and sodium sulfate provided by the embodiment of the present invention includes the following steps:
(1) adding lime milk into a hydrochloric acid wet-process phosphoric acid byproduct calcium chloride solution to adjust the solution to be alkaline, filtering and extracting a filtrate, and adding a hydrochloric acid standard solution into the filtrate to adjust the pH value to 1; taking 32ml of filtered calcium chloride solution as a byproduct of wet-process phosphoric acid by a hydrochloric acid method, and adding water to dilute the calcium chloride solution to 500ml to obtain 20g/L calcium chloride solution;
(2) taking 15g of sodium sulfate to prepare a sodium sulfate solution of 500ml to obtain a sodium sulfate solution of 30 g/L;
(3) mixing the two solutions, putting the mixture into a heat-preservation reaction device, heating and stirring the mixture to 120 ℃, and preserving heat for reaction for 15 min;
(4) filtering the mixed solution after heat preservation while the mixed solution is hot, repeatedly washing the filter residue for 3 times by using hot water at the temperature of 90 ℃, and then drying and dehydrating the filter residue at the temperature of 150 ℃ to obtain calcium sulfate hemihydrate crystal whiskers;
(5) calcining the obtained calcium sulfate hemihydrate crystal whisker at 510 ℃ for 0.5h to obtain the anhydrous calcium sulfate crystal whisker.
Example 2
As shown in fig. 1, the method for preparing calcium sulfate whiskers from a calcium chloride solution as a byproduct of phosphoric acid and sodium sulfate provided by the embodiment of the present invention includes the following steps:
(1) adding lime milk into a hydrochloric acid wet-process phosphoric acid byproduct calcium chloride solution to adjust the solution to be alkaline, filtering and extracting a filtrate, and adding a hydrochloric acid standard solution into the filtrate to adjust the pH value to 1; taking 128ml of filtered calcium chloride solution as a byproduct of wet-process phosphoric acid by a hydrochloric acid method, and adding water to dilute the calcium chloride solution to 500ml to obtain 80g/L calcium chloride solution;
(2) taking 60g of sodium sulfate to prepare 500ml of sodium sulfate solution to obtain 120g/L of sodium sulfate solution;
(3) mixing the two solutions, putting the mixture into a heat-preservation reaction device, heating and stirring the mixture to 120 ℃, and preserving heat for reaction for 30 min;
(4) filtering the mixed solution after heat preservation while the mixed solution is hot, repeatedly washing the filter residue with hot water at 95 ℃ for 5 times, and then drying and dehydrating the filter residue at 180 ℃ to obtain calcium sulfate hemihydrate crystal whiskers;
(5) calcining the obtained calcium sulfate hemihydrate crystal whisker at 530 ℃ for 1.5h to obtain the anhydrous calcium sulfate crystal whisker.
Example 3
As shown in fig. 1, the method for preparing calcium sulfate whiskers from a calcium chloride solution as a byproduct of phosphoric acid and sodium sulfate provided by the embodiment of the present invention includes the following steps:
(1) adding lime milk into a hydrochloric acid wet-process phosphoric acid byproduct calcium chloride solution to adjust the solution to be alkaline, filtering and extracting a filtrate, and adding a hydrochloric acid standard solution into the filtrate to adjust the pH value to 2; taking 32ml of filtered calcium chloride solution as a byproduct of wet-process phosphoric acid by a hydrochloric acid method, and adding water to dilute the calcium chloride solution to 500ml to obtain 20g/L calcium chloride solution;
(2) taking 15g of sodium sulfate to prepare a sodium sulfate solution of 500ml to obtain a sodium sulfate solution of 30 g/L;
(3) mixing the two solutions, putting the mixture into a heat-preservation reaction device, heating and stirring the mixture to 110 ℃, and preserving heat for reaction for 20 min;
(4) filtering the mixed solution after heat preservation while the mixed solution is hot, repeatedly washing the filter residue for 4 times by using hot water at 85 ℃, and then drying and dehydrating the filter residue at 160 ℃ to obtain calcium sulfate hemihydrate crystal whiskers;
(5) calcining the obtained calcium sulfate hemihydrate crystal whisker at 500 ℃ for 1h to obtain the anhydrous calcium sulfate crystal whisker.
Fig. 2 to 4 are 100-fold optical microscope images of the calcium sulfate whiskers of examples 1 to 3, respectively, diameter and length data of the calcium sulfate whiskers can be obtained from the images, whiteness data of the calcium sulfate whiskers is obtained by detection with a whiteness detector, purity data of the calcium sulfate whiskers is obtained by chemical analysis, and specific performance test results are shown in table 1:
table 1-calcium sulfate whisker property test results
| Scheme(s) | Whisker diameter (mum) | Whisker length (mum) | Aspect ratio | Whiteness (%) | Purity (%) |
| Example 1 | 1.05 | 95.74 | 91.18 | 94.7 | 99.14 |
| Example 2 | 1.13 | 89.86 | 79.52 | 92.6 | 99.03 |
| Example 3 | 1.08 | 81.23 | 75.21 | 94.3 | 99.11 |
From the table, the whiteness of the calcium sulfate whisker in the examples 1 to 3 is more than 90 percent, the purity is more than 99 percent, and the calcium sulfate whisker meets the national standard of the whisker for the friction material GB/T35471-2017.
Although the present invention has been described in detail by referring to the drawings in connection with the preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (9)
1. A method for preparing calcium sulfate whiskers from a phosphoric acid by-product calcium chloride solution and sodium sulfate is characterized in that the phosphoric acid by-product calcium chloride solution is a hydrochloric acid wet-process phosphoric acid by-product calcium chloride solution, and an acidification method is adopted to prepare the calcium sulfate whiskers: calcium salt and sulfate generate calcium sulfate precipitate under acidic condition, the calcium sulfate precipitate is dried and dehydrated after being washed by hot water to obtain calcium sulfate hemihydrate crystal whisker, and the calcium sulfate hemihydrate crystal whisker is obtained after calcination.
2. The method for preparing calcium sulfate whiskers from a calcium chloride solution as a byproduct of phosphoric acid and sodium sulfate according to claim 1, which comprises the following steps:
(1) purifying the calcium chloride solution as the byproduct of wet-process phosphoric acid production by hydrochloric acid method, filtering and extracting filtrate, adding hydrochloric acid into the filtrate to adjust the pH value of the solution to 0-3, and diluting;
(2) preparing sodium sulfate into a sodium sulfate solution, and mixing the sodium sulfate solution with the diluted calcium chloride solution;
(3) placing the mixed solution into a heat-preservation reaction device, heating and stirring the mixed solution to 110-120 ℃, and preserving heat for reaction;
(4) filtering the mixed solution after heat preservation while the mixed solution is hot, repeatedly washing the filter residue with hot water for 2-5 times, and then drying and dehydrating the filter residue to obtain calcium sulfate hemihydrate crystal whiskers;
(5) and calcining the obtained calcium sulfate hemihydrate crystal whisker to obtain the anhydrous calcium sulfate crystal whisker.
3. The method for preparing calcium sulfate whiskers from a calcium chloride solution as a byproduct of phosphoric acid and sodium sulfate according to claim 2, wherein in the step (1), the purification treatment method comprises: adding calcium hydroxide into the calcium chloride solution as the byproduct of wet-process phosphoric acid production by hydrochloric acid method to adjust the solution to be alkaline, and removing impurities in the solution.
4. The method for preparing calcium sulfate whiskers from a solution of calcium chloride as a byproduct of phosphoric acid and sodium sulfate according to claim 2, wherein in the step (1), the concentration of calcium chloride diluted by a solution of calcium chloride as a byproduct of wet phosphoric acid production by a hydrochloric acid method is 10-100 g/L.
5. The method for preparing calcium sulfate whiskers from a calcium chloride solution as a byproduct of phosphoric acid and sodium sulfate according to claim 2, wherein the concentration of the prepared sodium sulfate solution in the step (2) is 10-120 g/L.
6. The method for preparing calcium sulfate whiskers from a calcium chloride solution as a byproduct of phosphoric acid and sodium sulfate according to claim 2, wherein in the step (3), the reaction time is kept at 10-30 min.
7. The method for preparing calcium sulfate whiskers from a solution of calcium chloride as a byproduct of phosphoric acid and sodium sulfate as claimed in claim 2, wherein the hot water temperature in the step (4) is 85-100 ℃, and the drying temperature is 140-200 ℃.
8. The method for preparing calcium sulfate whiskers from a solution of calcium chloride as a byproduct of phosphoric acid and sodium sulfate as claimed in claim 2, wherein in the step (5), the calcination temperature is 500-550 ℃, and the calcination time is 0.5-1.5 h.
9. The method for preparing calcium sulfate whiskers from a calcium chloride solution as a byproduct of phosphoric acid and sodium sulfate according to claim 2, wherein in the step (5), the aspect ratio of the anhydrous calcium sulfate whiskers is 60-100, the whiteness is above 90%, and the purity is above 99%.
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| CN202110262674.9A Pending CN113106536A (en) | 2021-03-11 | 2021-03-11 | Method for preparing calcium sulfate whiskers from calcium chloride solution and sodium sulfate as phosphoric acid byproducts |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113999039A (en) * | 2021-10-29 | 2022-02-01 | 江苏博拓新型建筑材料股份有限公司 | In-situ whisker reinforced autoclaved aerated concrete prepared from gasified slag and preparation method thereof |
| CN114836624A (en) * | 2022-04-20 | 2022-08-02 | 荆门市格林美新材料有限公司 | Calcium removal method for chloride or sulfate solution |
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| CN113999039A (en) * | 2021-10-29 | 2022-02-01 | 江苏博拓新型建筑材料股份有限公司 | In-situ whisker reinforced autoclaved aerated concrete prepared from gasified slag and preparation method thereof |
| CN114836624A (en) * | 2022-04-20 | 2022-08-02 | 荆门市格林美新材料有限公司 | Calcium removal method for chloride or sulfate solution |
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