CN112941632A - Method for preparing calcium sulfate hemihydrate crystal whisker by purifying phosphogypsum under normal pressure - Google Patents
Method for preparing calcium sulfate hemihydrate crystal whisker by purifying phosphogypsum under normal pressure Download PDFInfo
- Publication number
- CN112941632A CN112941632A CN202110101811.0A CN202110101811A CN112941632A CN 112941632 A CN112941632 A CN 112941632A CN 202110101811 A CN202110101811 A CN 202110101811A CN 112941632 A CN112941632 A CN 112941632A
- Authority
- CN
- China
- Prior art keywords
- phosphogypsum
- calcium sulfate
- sulfate hemihydrate
- slurry
- normal pressure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical compound O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 title claims abstract description 156
- 239000013078 crystal Substances 0.000 title claims abstract description 87
- 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 title claims abstract description 70
- 238000000034 method Methods 0.000 title claims abstract description 66
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 92
- 239000002002 slurry Substances 0.000 claims abstract description 64
- 238000006243 chemical reaction Methods 0.000 claims abstract description 55
- 238000005188 flotation Methods 0.000 claims abstract description 49
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 46
- 230000009466 transformation Effects 0.000 claims abstract description 36
- 238000001914 filtration Methods 0.000 claims abstract description 27
- 238000004519 manufacturing process Methods 0.000 claims abstract description 26
- 238000001035 drying Methods 0.000 claims abstract description 21
- 239000011259 mixed solution Substances 0.000 claims abstract description 18
- YXJYBPXSEKMEEJ-UHFFFAOYSA-N phosphoric acid;sulfuric acid Chemical compound OP(O)(O)=O.OS(O)(=O)=O YXJYBPXSEKMEEJ-UHFFFAOYSA-N 0.000 claims abstract description 17
- 238000005406 washing Methods 0.000 claims abstract description 16
- 238000001027 hydrothermal synthesis Methods 0.000 claims abstract description 4
- 238000004064 recycling Methods 0.000 claims abstract description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 78
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 68
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 57
- 239000000377 silicon dioxide Substances 0.000 claims description 39
- 239000000047 product Substances 0.000 claims description 37
- 235000012239 silicon dioxide Nutrition 0.000 claims description 36
- 239000012065 filter cake Substances 0.000 claims description 30
- 239000006260 foam Substances 0.000 claims description 26
- 238000002156 mixing Methods 0.000 claims description 24
- 239000003795 chemical substances by application Substances 0.000 claims description 16
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 12
- 150000001412 amines Chemical class 0.000 claims description 8
- 239000002893 slag Substances 0.000 claims description 8
- 239000000706 filtrate Substances 0.000 claims description 3
- 230000033558 biomineral tissue development Effects 0.000 claims description 2
- 239000012535 impurity Substances 0.000 abstract description 17
- 230000008569 process Effects 0.000 abstract description 15
- 230000008901 benefit Effects 0.000 abstract description 9
- 229910052710 silicon Inorganic materials 0.000 abstract description 9
- 239000010703 silicon Substances 0.000 abstract description 9
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 238000002360 preparation method Methods 0.000 abstract description 2
- 238000010438 heat treatment Methods 0.000 description 26
- 239000012141 concentrate Substances 0.000 description 19
- 239000000463 material Substances 0.000 description 17
- 229910052698 phosphorus Inorganic materials 0.000 description 17
- 239000011574 phosphorus Substances 0.000 description 16
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 14
- 238000003756 stirring Methods 0.000 description 14
- 239000000126 substance Substances 0.000 description 14
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 13
- 239000011737 fluorine Substances 0.000 description 13
- 229910052731 fluorine Inorganic materials 0.000 description 13
- 239000002994 raw material Substances 0.000 description 11
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 10
- 229910052593 corundum Inorganic materials 0.000 description 10
- 229910001845 yogo sapphire Inorganic materials 0.000 description 10
- 239000006227 byproduct Substances 0.000 description 9
- 238000002425 crystallisation Methods 0.000 description 8
- 230000008025 crystallization Effects 0.000 description 8
- 239000013043 chemical agent Substances 0.000 description 6
- -1 phosphorus compound Chemical class 0.000 description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 229910052500 inorganic mineral Inorganic materials 0.000 description 3
- 239000011707 mineral Substances 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 239000003607 modifier Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000003337 fertilizer Substances 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 229910004725 CaSiF6 Inorganic materials 0.000 description 1
- 229910021532 Calcite Inorganic materials 0.000 description 1
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 229910004883 Na2SiF6 Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000010426 asphalt Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 229910001610 cryolite Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000002367 phosphate rock Substances 0.000 description 1
- OJMIONKXNSYLSR-UHFFFAOYSA-N phosphorous acid Chemical compound OP(O)O OJMIONKXNSYLSR-UHFFFAOYSA-N 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 230000001105 regulatory effect Effects 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
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 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
- C30B7/10—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions by application of pressure, e.g. hydrothermal processes
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention discloses a method for preparing calcium sulfate hemihydrate whiskers by purifying phosphogypsum under normal pressure, and relates to the technical field of preparation of calcium sulfate hemihydrate whiskers. Firstly, removing impurities such as silicon, organic matters and the like from phosphogypsum through flotation to obtain purified phosphogypsum; preparing the purified phosphogypsum and a sulfuric acid-phosphoric acid mixed solution into slurry with the mass concentration of the evolved phosphogypsum of 30-40%; then carrying out hydrothermal reaction on the slurry at the temperature of 90-110 ℃ for crystal transformation, and reacting for 0.5-2 h at normal pressure to obtain crystal transformation slurry; and filtering, washing and drying the crystal conversion slurry to obtain a calcium sulfate hemihydrate crystal whisker product. The method has the advantages of simple process, low production cost, capability of being combined with the existing wet-process phosphoric acid production process, small diameter, high length-diameter ratio, short production time, high conversion efficiency, mild reaction conditions, no need of high-pressure reaction facilities, capability of recycling the sulfuric acid-phosphoric acid mixed solution and the like, and has remarkable social, economic and environmental benefits.
Description
Technical Field
The invention relates to the technical field of preparation of calcium sulfate hemihydrate whiskers, in particular to a method for preparing calcium sulfate hemihydrate whiskers by purifying phosphogypsum under normal pressure.
Background
Phosphogypsum is a by-product of wet process phosphoric acid production, typically producing 1 ton phosphoric acid (at 100% P)2O5Measured) produces 4.8 to 5 tons of phosphogypsum. Phosphoric acid is a basic raw material for preparing various phosphorus compound fertilizers, and with the continuous increase of the demand of the phosphorus compound fertilizers, the productivity of the phosphoric acid is continuously improved, and the yield of the phosphogypsum is increased, but the comprehensive utilization rate of the phosphogypsum is low. The main component of the phosphogypsum is calcium sulfate dihydrate, harmful impurities such as phosphorus, iron, aluminum, silicon and the like are contained in the phosphogypsum, organic matters are reduced, the pH value is 4-5, the use of the phosphogypsum is seriously restricted by the existence of the impurities and the organic matters, however, a large amount of land is wasted due to long-term accumulation treatment, and the harmful substances can pollute the environment.
The calcium sulfate hemihydrate crystal whisker is a fine fibrous sub-nanometer material formed by taking gypsum, limestone, calcite and the like as main raw materials and growing in a single crystal form through certain process control, has the advantages of high strength, wear resistance, corrosion resistance, no toxicity, easiness in compounding with polymers and the like, and is widely applied to industries of building materials, plastics, resins, rubber, papermaking, asphalt and the like. The phosphogypsum has high content of calcium sulfate dihydrate, and if the phosphogypsum can be purified, the phosphogypsum is an ideal raw material for preparing the calcium sulfate hemihydrate crystal whisker.
The patent CN106480507A discloses a novel process for preparing low-cost calcium sulfate hemihydrate whiskers from phosphogypsum, which comprises the steps of taking floating phosphogypsum as a raw material, adding water into the ground and uniformly mixed raw material for size mixing, adding a certain amount of a crystal modifier and industrial-grade sulfuric acid or hydrochloric acid, reacting in a pressure reaction kettle at 120-140 ℃ for 2 hours, after the reaction is completed, quickly filtering, dehydrating, and drying at the temperature higher than 80 ℃ to obtain the calcium sulfate hemihydrate whiskers. Wherein the filtrate contains a crystal modifier and sulfuric acid and is returned to the step for continuous recycling. The process has high reaction temperature, needs to add a crystal modifier, and has serious corrosion to equipment by hydrochloric acid at high temperature.
Patent CN105350066A discloses a method for preparing calcium sulfate hemihydrate whiskers by using phosphogypsum, which is to prepare the calcium sulfate hemihydrate whiskers by using flotation desiliconized phosphogypsum as a raw material and through calcination, washing activation and hydraulic hot processes. The method has the advantages of complex process flow, high cost and the need of calcining the raw materials.
The patent CN110747503A discloses a method for preparing calcium sulfate hemihydrate whiskers by microwave irradiation of phosphogypsum under normal pressure, which is characterized in that conventional heating modes such as water bath, oil bath, steam pressure and the like are replaced by microwave irradiation, high dielectric constant impurities in the phosphogypsum and alcohol and water in an alcohol-water solution are utilized to absorb electromagnetic waves, and the phosphogypsum is used as a raw material to prepare the calcium sulfate hemihydrate whiskers in the alcohol-water sulfate solution under normal pressure. The product obtained by the method has poor stability and low purity.
Patent CN110541188A discloses a method for preparing calcium sulfate hemihydrate whiskers with high length-diameter ratio by using calcium sulfate dihydrate, mixing the calcium sulfate dihydrate with alkali liquor, then carrying out fine grinding, fully reacting impurity elements with the alkali liquor, transferring into liquid phase, then taking the solid phase, carrying out acid leaching to remove impurities, and removing carbonate, oxides and the like; and after the reaction, adding an oxidant into the solid phase, removing organic matters to obtain pure calcium sulfate dihydrate, performing hydrothermal reaction, adding a crystal form regulating agent to convert the calcium sulfate dihydrate into calcium sulfate hemihydrate whisker slurry, and filtering and drying to obtain the calcium sulfate hemihydrate whisker. The inorganic and organic impurities in the raw material are physically and chemically removed from the raw material calcium sulfate dihydrate, so that the obtained calcium sulfate hemihydrate has high purity and large length-diameter ratio, and the added value of the product is improved. The method has multiple working procedures and complex process flow.
In conclusion, the former has made a great deal of work on the aspect of preparing the calcium sulfate hemihydrate crystal whisker by the phosphogypsum, but the defects of complex process, unstable crystal whisker products, high production cost and the like still exist.
Disclosure of Invention
The invention aims to provide a method for preparing calcium sulfate hemihydrate whiskers by purifying phosphogypsum under normal pressure, and solves the problems that in the prior art, the impurity removal process of phosphogypsum is complex, and a crystal transformation agent needs to be added in the whisker transformation process, so that the production cost is high.
In order to solve the technical problems, the invention adopts the following technical scheme: a method for preparing calcium sulfate hemihydrate crystal whiskers by purifying phosphogypsum under normal pressure is characterized by comprising the following steps:
(1) removing silicon dioxide and Al from phosphogypsum by flotation2O3、Fe2O3Organic matters are adopted to obtain purified phosphogypsum;
(2) preparing a sulfuric acid-phosphoric acid mixed solution with a certain mass concentration by using industrial sulfuric acid, industrial phosphoric acid and water for later use; wherein the mass concentration of the phosphoric acid is 20-40%, and the mass concentration of the sulfuric acid is 0-20%;
(3) preparing the purified phosphogypsum in the step (1) and the sulfuric acid-phosphoric acid mixed solution in the step (2) into slurry with the mass concentration of the evolved phosphogypsum of 30-40%;
(4) calcium sulfate hemihydrate whisker conversion: carrying out hydrothermal reaction on the slurry obtained in the step (3) at the temperature of 90-110 ℃ for crystal transformation, and reacting for 0.5-2 h under normal pressure to obtain crystal transformation slurry;
(5) and filtering, washing and drying the crystal conversion slurry to obtain a calcium sulfate hemihydrate crystal whisker product.
The further technical scheme is that the content of calcium sulfate dihydrate in the purified phosphogypsum in the step (1) is more than or equal to 95 percent, the content of silicon dioxide is less than or equal to 3 percent, and the content of organic matters is less than or equal to 0.2 percent.
The further technical scheme is that the washing in the step (5) is hot water washing, the temperature of the hot water is 70 ℃, and the washing is carried out until the pH value of a filter cake is 6-7.
A further technical proposal is that the drying temperature in the step (5) is 110 ℃.
The further technical scheme is that the diameter of the calcium sulfate hemihydrate crystal whisker is 1-4 um, the length is 100-200 um, and the length-diameter ratio is 20-200.
The further technical proposal is that the filtered filtrate in the step (5) replaces part of the mixed solution of sulfuric acid and phosphoric acid to be continuously recycled.
The further technical scheme is that the phosphogypsum flotation specific steps in the step (1) are as follows:
(1-1) adding water into filtered phosphogypsum generated in the wet-process phosphoric acid production process for size mixing to obtain slurry with the mass concentration of 25% -35% and the pH value of 2-3, and adding a direct flotation collecting agent for mineralization size mixing;
(1-2) performing direct flotation roughing on the slurry after size mixing, performing fine selection on coarse selection foam to obtain purified phosphogypsum, and combining the fine selection tailings and the coarse selection tailings into final tailings.
The further technical scheme is that the positive flotation collector is a fatty amine collector, and the using amount of the collector is 0.1-0.3 kg/t of slurry.
The further technical scheme is that water used for size mixing in the step (1-1) is phosphogypsum slag dam backwater.
The further technical scheme is that water used for size mixing in the step (1-1) is clear water, sulfuric acid is used as a pH value regulator, and the adding amount of the sulfuric acid is 0.5-1.5 kg/t of slurry.
Compared with the prior art, the invention has the beneficial effects that:
1. the phosphogypsum purification adopts a phosphogypsum direct flotation silicon dioxide removal process, and the impurity content in the purified phosphogypsum product is greatly reduced. In the flotation process, unreacted phosphorite and Na3AlF6、CaSiF6、Na2SiF6、CaF2，Al2O3、Fe2O3And because the zero-electricity points of the indissolvable minerals are higher than those of calcium sulfate dihydrate, the beneficiation reagent cannot be adsorbed on the surfaces of the minerals in the flotation process, so that the minerals are difficult to enter the purified phosphogypsum product, and the aims of removing silicon dioxide and other oxides, removing part of water-soluble phosphorus and water-soluble fluorine and obtaining the high-grade low-silicon phosphogypsum concentrate are fulfilled.
2. The invention adopts a conventional heating mode and prepares the calcium sulfate hemihydrate crystal whisker in a sulfuric acid-phosphoric acid mixed solution by taking purified phosphogypsum as a raw material under normal pressure. The invention uses the mixed solution of sulfuric acid and phosphoric acid to adjust the reaction speed, reduce the reaction temperature and accelerate the dissolution of calcium sulfate dihydrate and the precipitation of calcium sulfate hemihydrate crystals. In the environment of high-temperature sulfuric acid-phosphoric acid solution, hydrogen ions are adsorbed on the side surfaces of the calcium sulfate hemihydrate crystals to form hydrogen bond layered structures to hinder the lateral growth of the calcium sulfate hemihydrate crystals, and meanwhile, anions precipitated from phosphogypsum dihydrate and cations precipitated from sulfuric acid salt form ion pairs to enable calcium ions to migrate to the crystal surfaces to promote the growth of the calcium sulfate hemihydrate crystals on the C axis, so that the calcium sulfate hemihydrate crystal whiskers with high length-diameter ratio are formed.
3. The method has the advantages of simple process and low production cost, can be combined with the existing wet-process phosphoric acid production process, and the prepared calcium sulfate hemihydrate crystal whisker has the advantages of small diameter, high length-diameter ratio and complete and uniform appearance, can complete the conversion from calcium sulfate dihydrate to the calcium sulfate hemihydrate crystal whisker within 30-120 min, and has the conversion rate of over 99 percent. The method has the advantages of short production time, high conversion efficiency, mild reaction conditions, no need of high-pressure reaction facilities, capability of recycling the sulfuric acid-phosphoric acid mixed solution and the like, and has remarkable social, economic and environmental benefits.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Figure 2 is a process flow diagram of phosphogypsum flotation in the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
A method for preparing calcium sulfate hemihydrate crystal whiskers by purifying phosphogypsum under normal pressure is shown in figure 1, and comprises the following specific steps:
firstly, taking the phosphogypsum which is a byproduct of a wet-process phosphoric acid production device, and carrying out flotation to remove silicon dioxide and Al2O3、Fe2O3And organic matters and other impurities are purified phosphogypsum for later use.
Specifically, filtered phosphogypsum generated in the wet-process phosphoric acid production process is added with return water (pH value is 1.9) of a phosphogypsum slag dam for size mixing, the using amount of the return water of the phosphogypsum slag dam is controlled, and sulfuric acid is added as a pH value regulator if necessary to obtain slurry with the mass concentration of 25% and the pH value of 2.8. The main chemical components of the selected phosphogypsum are 82.15 percent of calcium sulfate dihydrate, 13.86 percent of silicon dioxide, 0.98 percent of water-soluble phosphorus, 0.32 percent of water-soluble fluorine and 23.25 percent of water in percentage by weight.
And adding the slurry into flotation equipment, adding a fatty amine collecting agent as a positive flotation collecting agent according to the slurry of 0.20kg/t, stirring and mixing the slurry for 2 minutes, and performing positive flotation roughing, wherein the product in the tank is silicon dioxide tailings, and the foam product is rough concentrate. And then the foam product rough concentrate is selected, no chemical agent is added in the selection, the tailings obtained by flotation and selection and the tailings obtained by rough selection are combined into final tailings, and the foam product is the low-silicon phosphogypsum concentrate. Filtering the foam product by a filter to obtain a filter cake with the water content of less than 15%, and drying the filter cake by a baking oven at 45 ℃ to obtain the purified phosphogypsum, wherein the main chemical components of the purified phosphogypsum comprise 96.15% of calcium sulfate dihydrate, 2.36% of silicon dioxide, 0.15% of water-soluble phosphorus, 0.04% of water-soluble fluorine and 81.41% of silicon dioxide removal rate in percentage by weight.
Preparing the phosphoric acid-sulfuric acid mixed solution with the phosphoric acid mass concentration of 20% and the sulfuric acid mass concentration of 10% with water and industrial phosphoric acid with the phosphoric acid mass concentration of 85% and industrial sulfuric acid with the sulfuric acid mass concentration of 98%.
Thirdly, preparing the standby materials in the first step and the second step into slurry with the mass concentration of the purified phosphogypsum of 30 percent, and uniformly stirring.
Pouring the slurry obtained in the step III into a normal-pressure crystal transformation reaction container, heating to 90 ℃ by adopting a conventional heating mode, heating for reaction for 1 hour, and then stopping crystal transformation reaction.
Fifthly, filtering the crystal transformation reaction material in the step IV, washing a filter cake after filtering with hot water at 70 ℃ until the pH value is 6-7.
Sixthly, drying the washed filter cake in the fifth step to constant weight at 110 ℃ to obtain the calcium sulfate hemihydrate crystal whisker.
The prepared calcium sulfate hemihydrate crystal whisker has good and uniform crystallization property, the diameter is 2-4 um, the length is 100-200 um, the length-diameter ratio is about 50, and the conversion rate is more than 99%.
Example 2
A method for preparing calcium sulfate hemihydrate crystal whiskers by purifying phosphogypsum under normal pressure is shown in figure 1, and comprises the following specific steps:
firstly, taking the phosphogypsum which is a byproduct of a wet-process phosphoric acid production device, and carrying out flotation to remove silicon dioxide and Al2O3、Fe2O3And organic matters and other impurities are purified phosphogypsum for later use.
Specifically, filtered phosphogypsum generated in the wet-process phosphoric acid production process is added with return water (pH value is 1.9) of a phosphogypsum slag dam for size mixing, the using amount of the return water of the phosphogypsum slag dam is controlled, and sulfuric acid is added as a pH value regulator if necessary to obtain slurry with the mass concentration of 30% and the pH value of 2.2. The main chemical components of the selected phosphogypsum are 84.46% of calcium sulfate dihydrate, 11.45% of silicon dioxide, 0.96% of water-soluble phosphorus, 0.38% of water-soluble fluorine and 23.89% of water in percentage by weight.
And adding the slurry into flotation equipment, adding a fatty amine collecting agent as a positive flotation collecting agent according to the slurry weight of 0.15kg/t, stirring and mixing the slurry for 2 minutes, and performing positive flotation roughing, wherein the product in the tank is silicon dioxide tailings, and the foam product is rough concentrate. And then the foam product rough concentrate is selected, no chemical agent is added in the selection, the tailings obtained by flotation and selection and the tailings obtained by rough selection are combined into final tailings, and the foam product is the low-silicon phosphogypsum concentrate. Filtering the foam product by a filter to obtain a filter cake with the water content of less than 15%, and drying the filter cake by a baking oven at 45 ℃ to obtain the purified phosphogypsum, wherein the main chemical components of the purified phosphogypsum comprise 96.48% of calcium sulfate dihydrate, 1.94% of silicon dioxide, 0.15% of water-soluble phosphorus, 0.05% of water-soluble fluorine and 81.78% of silicon dioxide removal rate in percentage by weight.
Preparing the phosphoric acid-sulfuric acid mixed solution with the phosphoric acid mass concentration of 20% and the sulfuric acid mass concentration of 12.5% with water and industrial phosphoric acid with the phosphoric acid mass concentration of 85% and industrial sulfuric acid with the sulfuric acid mass concentration of 98%.
Thirdly, preparing the standby materials in the first step and the second step into slurry with the mass concentration of the purified phosphogypsum of 40 percent, and uniformly stirring.
Pouring the slurry obtained in the step III into a normal-pressure crystal transformation reaction container, heating to 90 ℃ by adopting a conventional heating mode, heating for reaction for 1 hour, and then stopping crystal transformation reaction.
Fifthly, filtering the crystal transformation reaction material in the step IV, washing a filter cake after filtering with hot water at 70 ℃ until the pH value is 6-7.
Sixthly, drying the washed filter cake in the fifth step to constant weight at 110 ℃ to obtain the calcium sulfate hemihydrate crystal whisker.
The prepared calcium sulfate hemihydrate crystal whisker has good and uniform crystallization property, the diameter is 2-4 um, the length is 100-200 um, the length-diameter ratio is about 45, and the conversion rate is more than 99%.
Example 3
A method for preparing calcium sulfate hemihydrate crystal whiskers by purifying phosphogypsum under normal pressure refers to figure 1, and comprises the following specific steps:
firstly, taking the phosphogypsum which is a byproduct of a wet-process phosphoric acid production device, and carrying out flotation to remove silicon dioxide and Al2O3、Fe2O3And organic matters and other impurities are purified phosphogypsum for later use.
Specifically, filtered phosphogypsum generated in the wet-process phosphoric acid production process is added with return water (pH value is 1.9) of a phosphogypsum slag dam for size mixing, the using amount of the return water of the phosphogypsum slag dam is controlled, and sulfuric acid is added as a pH value regulator if necessary to obtain slurry with the mass concentration of 35% and the pH value of 2.6. The main chemical components of the selected phosphogypsum are 82.15 percent of calcium sulfate dihydrate, 13.86 percent of silicon dioxide, 0.98 percent of water-soluble phosphorus, 0.32 percent of water-soluble fluorine and 23.25 percent of water in percentage by weight.
And adding the slurry into flotation equipment, adding a fatty amine collecting agent as a positive flotation collecting agent according to the slurry of 0.20kg/t, stirring and mixing the slurry for 2 minutes, and performing positive flotation roughing, wherein the product in the tank is silicon dioxide tailings, and the foam product is rough concentrate. And then the foam product rough concentrate is selected, no chemical agent is added in the selection, the tailings obtained by flotation and selection and the tailings obtained by rough selection are combined into final tailings, and the foam product is the low-silicon phosphogypsum concentrate. Filtering the foam product by a filter to obtain a filter cake with the water content of less than 15%, and drying the filter cake by a baking oven at 45 ℃ to obtain the purified phosphogypsum, wherein the main chemical components of the purified phosphogypsum comprise 95.94% of calcium sulfate dihydrate, 2.41% of silicon dioxide, 0.18% of water-soluble phosphorus and 0.06% of water-soluble fluorine by weight percentage. The silica removal rate was 80.43%.
Preparing the industrial phosphoric acid, the industrial sulfuric acid and water into a phosphoric acid-sulfuric acid mixed solution with the phosphoric acid mass concentration of 20% and the sulfuric acid mass concentration of 15% for later use.
Thirdly, preparing the standby materials in the first step and the second step into slurry with the mass concentration of the purified phosphogypsum of 30 percent, and uniformly stirring.
Pouring the slurry obtained in the step III into a normal-pressure crystal transformation reaction container, heating to 90 ℃ by adopting a conventional heating mode, heating for reaction for 1 hour, and then stopping crystal transformation reaction.
Fifthly, filtering the crystal transformation reaction material in the step IV, washing a filter cake after filtering with hot water at 70 ℃ until the pH value is 6-7.
Sixthly, drying the washed filter cake in the fifth step to constant weight at 110 ℃ to obtain the calcium sulfate hemihydrate crystal whisker.
The prepared calcium sulfate hemihydrate crystal whisker has good and uniform crystallization property, the diameter is 2-4 um, the length is 100-200 um, the length-diameter ratio is about 40, and the conversion rate is more than 99%.
Example 4
A method for preparing calcium sulfate hemihydrate crystal whiskers by purifying phosphogypsum under normal pressure refers to figure 1, and comprises the following specific steps:
firstly, taking the phosphogypsum which is a byproduct of a wet-process phosphoric acid production device, and carrying out flotation to remove silicon dioxide and Al2O3、Fe2O3And organic matters and other impurities are purified phosphogypsum for later use.
Specifically, filtered phosphogypsum generated in the wet-process phosphoric acid production process is added with clear water for size mixing, and sulfuric acid is added into the slurry according to the proportion of 1.5kg/t as a pH value regulator to obtain the slurry with the mass concentration of 30% and the pH value of 2.5. The main chemical components of the selected phosphogypsum are, by weight, 80.46% of calcium sulfate dihydrate, 14.73% of silicon dioxide, 0.94% of water-soluble phosphorus, 0.33% of water-soluble fluorine and 24.37% of water.
And adding the slurry into flotation equipment, adding a fatty amine collecting agent as a positive flotation collecting agent according to the slurry of 0.25kg/t, stirring and mixing the slurry for 2 minutes, and performing positive flotation roughing, wherein the product in the tank is silicon dioxide tailings, and the foam product is rough concentrate. And then the foam product rough concentrate is selected, no chemical agent is added in the selection, the tailings obtained by flotation and selection and the tailings obtained by rough selection are combined into final tailings, and the foam product is the low-silicon phosphogypsum concentrate. Filtering the foam product by a filter to obtain a filter cake with the water content of less than 15%, and drying the filter cake by a baking oven at 45 ℃ to obtain the purified phosphogypsum, wherein the main chemical components of the purified phosphogypsum comprise, by weight, 95.76% of calcium sulfate dihydrate, 2.48% of silicon dioxide, 0.16% of water-soluble phosphorus, 0.07% of water-soluble fluorine and 81.26% of silicon dioxide removal rate.
Preparing the industrial phosphoric acid, the industrial sulfuric acid and water into a phosphoric acid-sulfuric acid mixed solution with the phosphoric acid mass concentration of 30% and the sulfuric acid mass concentration of 15% for later use.
Thirdly, preparing the standby materials in the first step and the second step into slurry with the mass concentration of the purified phosphogypsum of 40 percent, and uniformly stirring.
Pouring the slurry obtained in the step III into a normal-pressure crystal transformation reaction container, heating to 95 ℃ by adopting a conventional heating mode, and stopping crystal transformation reaction after heating reaction for 0.5 h.
Fifthly, filtering the crystal transformation reaction material in the step IV, washing a filter cake after filtering with hot water at 70 ℃ until the pH value is 6-7.
Sixthly, drying the washed filter cake in the fifth step to constant weight at 110 ℃ to obtain the calcium sulfate hemihydrate crystal whisker.
The prepared calcium sulfate hemihydrate crystal whisker has good and uniform crystallization property and higher crystal transformation speed, the diameter is 2-4 um, the length is 100-200 um, the length-diameter ratio is about 40, and the transformation rate is more than 99%.
Example 5
A method for preparing calcium sulfate hemihydrate crystal whiskers by purifying phosphogypsum under normal pressure refers to figure 1, and comprises the following specific steps:
firstly, taking the phosphogypsum which is a byproduct of a wet-process phosphoric acid production device, and carrying out flotation to remove silicon dioxide and Al2O3、Fe2O3And organic matters and other impurities are purified phosphogypsum for later use.
Specifically, filtered phosphogypsum generated in the wet-process phosphoric acid production process is added with clear water for size mixing, and sulfuric acid is added into the slurry according to 0.8kg/t to serve as a pH value regulator, so that the slurry with the mass concentration of 30% and the pH value of 2.6 is obtained. The main chemical components of the selected phosphogypsum are 84.46% of calcium sulfate dihydrate, 11.45% of silicon dioxide, 0.96% of water-soluble phosphorus, 0.38% of water-soluble fluorine and 23.89% of water in percentage by weight.
And adding the slurry into flotation equipment, adding a fatty amine collecting agent as a positive flotation collecting agent according to the slurry weight of 0.15kg/t, stirring and mixing the slurry for 2 minutes, and performing positive flotation roughing, wherein the product in the tank is silicon dioxide tailings, and the foam product is rough concentrate. And then the foam product rough concentrate is selected, no chemical agent is added in the selection, the tailings obtained by flotation and selection and the tailings obtained by rough selection are combined into final tailings, and the foam product is the low-silicon phosphogypsum concentrate. Filtering the foam product by a filter to obtain a filter cake with the water content of less than 15%, and drying the filter cake by a baking oven at 45 ℃ to obtain the purified phosphogypsum, wherein the main chemical components of the purified phosphogypsum comprise, by weight, 95.89% of calcium sulfate dihydrate, 2.13% of silicon dioxide, 0.14% of water-soluble phosphorus, 0.09% of water-soluble fluorine and 81.48% of silicon dioxide removal rate.
Preparing the industrial phosphoric acid, the industrial sulfuric acid and water into a phosphoric acid-sulfuric acid mixed solution with the phosphoric acid mass concentration of 20% and the sulfuric acid mass concentration of 10% for later use.
Thirdly, preparing the standby materials in the first step and the second step into slurry with the mass concentration of the purified phosphogypsum of 40 percent, and uniformly stirring.
Pouring the slurry obtained in the step III into a normal-pressure crystal transformation reaction container, heating to 95 ℃ by adopting a conventional heating mode, and terminating the crystal transformation reaction after heating for 2 hours.
Fifthly, filtering the crystal transformation reaction material in the step IV, washing a filter cake after filtering with hot water at 70 ℃ until the pH value is 6-7.
Sixthly, drying the washed filter cake in the fifth step to constant weight at 110 ℃ to obtain the calcium sulfate hemihydrate crystal whisker.
The prepared calcium sulfate hemihydrate crystal whisker has good and uniform crystallization property and higher crystal transformation speed, the diameter is 2-4 um, the length is 100-200 um, the length-diameter ratio is about 50, and the transformation rate is more than 99%.
Example 6
A method for preparing calcium sulfate hemihydrate crystal whiskers by purifying phosphogypsum under normal pressure refers to figure 1, and comprises the following specific steps:
taking the by-product of phosphoric acid production apparatusPaste, flotation to remove silica and Al2O3、Fe2O3And organic matters and other impurities are purified phosphogypsum for later use.
Specifically, filtered phosphogypsum generated in the wet-process phosphoric acid production process is added with clear water for size mixing, and sulfuric acid is added into the slurry according to the proportion of 1.2kg/t as a pH value regulator to obtain the slurry with the mass concentration of 30% and the pH value of 2.6. The main chemical components of the selected phosphogypsum are 85.46% of calcium sulfate dihydrate, 9.34% of silicon dioxide, 0.92% of water-soluble phosphorus, 0.37% of water-soluble fluorine and 24.21% of water in percentage by weight.
And adding the slurry into flotation equipment, adding a fatty amine collecting agent as a positive flotation collecting agent according to the slurry of 0.10kg/t, stirring and mixing the slurry for 2 minutes, and performing positive flotation roughing, wherein the product in the tank is silicon dioxide tailings, and the foam product is rough concentrate. And then the foam product rough concentrate is selected, no chemical agent is added in the selection, the tailings obtained by flotation and selection and the tailings obtained by rough selection are combined into final tailings, and the foam product is the low-silicon phosphogypsum concentrate. Filtering the foam product by a filter to obtain a filter cake with the water content of less than 15%, and drying the filter cake by a baking oven at 45 ℃ to obtain the purified phosphogypsum, wherein the main chemical components of the purified phosphogypsum comprise 96.38% of calcium sulfate dihydrate, 1.95% of silicon dioxide, 0.12% of water-soluble phosphorus, 0.09% of water-soluble fluorine and 81.16% of silicon dioxide removal rate in percentage by weight.
Preparing phosphoric acid-sulfuric acid mixed solution with the phosphoric acid mass concentration of 25% and the sulfuric acid mass concentration of 15% by taking industrial phosphoric acid, industrial sulfuric acid and water for later use;
thirdly, preparing the standby materials in the first step and the second step into slurry with the mass concentration of purified phosphogypsum of 35 percent, and uniformly stirring;
pouring the slurry obtained in the step III into a normal-pressure crystal transformation reaction container, heating to 95 ℃ by adopting a conventional heating mode, heating for reaction for 1 hour, and then stopping crystal transformation reaction;
fifthly, filtering the crystal transformation reaction material in the step IV, washing a filter cake after filtering with hot water at 70 ℃ until the pH value is 6-7;
sixthly, drying the washed filter cake in the fifth step to constant weight at 110 ℃ to obtain the calcium sulfate hemihydrate crystal whisker.
The prepared calcium sulfate hemihydrate crystal whisker has good and uniform crystallization property, the diameter is 1-4 um, the length is 80-200 um, the length-diameter ratio is about 45, and the conversion rate is more than 99%.
Example 7
A method for preparing calcium sulfate hemihydrate crystal whiskers by purifying phosphogypsum under normal pressure refers to figure 1, and comprises the following specific steps:
firstly, taking the phosphogypsum which is a byproduct of a wet-process phosphoric acid production device, and carrying out flotation to remove silicon dioxide and Al2O3、Fe2O3And organic matters and other impurities are purified phosphogypsum for later use.
Preparing the industrial phosphoric acid, the industrial sulfuric acid and water into a phosphoric acid-sulfuric acid mixed solution with the phosphoric acid mass concentration of 30% and the sulfuric acid mass concentration of 10% for later use.
Thirdly, preparing the standby materials in the first step and the second step into slurry with the mass concentration of the purified phosphogypsum of 40 percent, and uniformly stirring.
Pouring the slurry obtained in the step III into a normal-pressure crystal transformation reaction container, heating to 90 ℃ by adopting a conventional heating mode, heating for reaction for 1 hour, and then stopping crystal transformation reaction.
Fifthly, filtering the crystal transformation reaction material in the step IV, washing a filter cake after filtering with hot water at 70 ℃ until the pH value is 6-7.
Sixthly, drying the washed filter cake in the fifth step to constant weight at 110 ℃ to obtain the calcium sulfate hemihydrate crystal whisker.
The prepared calcium sulfate hemihydrate crystal whisker has good and uniform crystallization property, the diameter is 1-4 um, the length is 100-200 um, the length-diameter ratio is about 55, and the conversion rate is more than 99%.
Example 8
A method for preparing calcium sulfate hemihydrate crystal whiskers by purifying phosphogypsum under normal pressure refers to figure 1, and comprises the following specific steps:
firstly, taking the phosphogypsum which is a byproduct of a wet-process phosphoric acid production device, and carrying out flotation to remove silicon dioxide and Al2O3、Fe2O3And organic matters and other impurities are purified phosphogypsum for later use.
② no sulfuric acid is added, and industrial phosphoric acid and water are prepared into aqueous solution with the phosphoric acid mass concentration of 40 percent for standby.
Thirdly, preparing the standby materials in the first step and the second step into slurry with the mass concentration of the purified phosphogypsum of 30 percent, and uniformly stirring.
Pouring the slurry obtained in the step III into a normal-pressure crystal transformation reaction container, heating to 90 ℃ by adopting a conventional heating mode, heating for reaction for 1 hour, and then stopping crystal transformation reaction.
Fifthly, filtering the crystal transformation reaction material in the step IV, washing a filter cake after filtering with hot water at 70 ℃ until the pH value is 6-7.
Sixthly, drying the washed filter cake in the fifth step to constant weight at 110 ℃ to obtain the calcium sulfate hemihydrate crystal whisker.
The prepared calcium sulfate hemihydrate crystal whisker has good and uniform crystallization property, the diameter is 1-4 um, the length is 100-200 um, the length-diameter ratio is about 60, and the conversion rate is more than 99%.
In the embodiment, the chemical components of the purified phosphogypsum are as follows:
| composition (I) | CaSO4·2H2O | SiO2 | Al2O3 | Fe2O3 | Total P2O5 | Water soluble P2O5 | Total F | Water soluble F | Organic matter |
| Content% | 95.63 | 2.25 | 0.22 | 0.20 | 0.83 | 0.15 | 0.10 | 0.08 | 0.059 |
While the invention has been described herein with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the scope of the disclosure. More particularly, various variations and modifications are possible in the component parts or arrangements within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts or arrangements, other uses will also be apparent to those skilled in the art.
Claims (10)
1. A method for preparing calcium sulfate hemihydrate crystal whiskers by purifying phosphogypsum under normal pressure is characterized by comprising the following steps:
(1) removing silicon dioxide and Al from phosphogypsum by flotation2O3、Fe2O3Organic matters are adopted to obtain purified phosphogypsum;
(2) preparing a sulfuric acid-phosphoric acid mixed solution with a certain mass concentration by using industrial sulfuric acid, industrial phosphoric acid and water for later use; wherein the mass concentration of the phosphoric acid is 20-40%, and the mass concentration of the sulfuric acid is 0-20%;
(3) preparing the purified phosphogypsum in the step (1) and the sulfuric acid-phosphoric acid mixed solution in the step (2) into slurry with the mass concentration of the purified phosphogypsum of 30-40%;
(4) calcium sulfate hemihydrate whisker conversion: carrying out hydrothermal reaction on the slurry obtained in the step (3) at the temperature of 90-110 ℃ for crystal transformation, and reacting for 0.5-2 h under normal pressure to obtain crystal transformation slurry;
(5) and filtering, washing and drying the crystal conversion slurry to obtain a calcium sulfate hemihydrate crystal whisker product.
2. The method for preparing calcium sulfate hemihydrate whiskers by purifying phosphogypsum under normal pressure according to claim 1, characterized by comprising the following steps: in the purified phosphogypsum in the step (1), the content of calcium sulfate dihydrate is more than or equal to 95 percent, the content of silicon dioxide is less than or equal to 3 percent, and the content of organic matters is less than or equal to 0.2 percent.
3. The method for preparing calcium sulfate hemihydrate whiskers by purifying phosphogypsum under normal pressure according to claim 1, characterized by comprising the following steps: and (5) washing with hot water at the temperature of 70 ℃ until the pH value of the filter cake is 6-7.
4. The method for preparing calcium sulfate hemihydrate whiskers by purifying phosphogypsum under normal pressure according to claim 1, characterized by comprising the following steps: the drying temperature in the step (5) is 110 ℃.
5. The method for preparing calcium sulfate hemihydrate whiskers by purifying phosphogypsum under normal pressure according to claim 1, characterized by comprising the following steps: the calcium sulfate hemihydrate crystal whisker is 1-4 um in diameter, 100-200 um in length and 20-200 in length-diameter ratio.
6. The method for preparing calcium sulfate hemihydrate whiskers by purifying phosphogypsum under normal pressure according to claim 1, characterized by comprising the following steps: and (5) replacing part of the sulfuric acid-phosphoric acid mixed solution with the filtered filtrate for continuous recycling.
7. The method for preparing calcium sulfate hemihydrate whiskers by purifying phosphogypsum under normal pressure according to claim 1, characterized by comprising the following steps: the specific steps of phosphogypsum flotation in the step (1) are as follows:
(1-1) adding water into filtered phosphogypsum generated in the wet-process phosphoric acid production process for size mixing to obtain slurry with the mass concentration of 25% -35% and the pH value of 2-3, and adding a direct flotation collecting agent for mineralization size mixing;
(1-2) performing direct flotation roughing on the slurry after size mixing, performing fine selection on coarse selection foam to obtain purified phosphogypsum, and combining the fine selection tailings and the coarse selection tailings into final tailings.
8. The method for preparing calcium sulfate hemihydrate whiskers by purifying phosphogypsum under normal pressure according to claim 7, characterized by comprising the following steps: the positive flotation collector is a fatty amine collector, and the using amount of the positive flotation collector is 0.1-0.3 kg/t of slurry.
9. The method for preparing calcium sulfate hemihydrate whiskers by purifying phosphogypsum under normal pressure according to claim 7, characterized by comprising the following steps: and (2) the water used for size mixing in the step (1-1) is phosphogypsum slag dam backwater.
10. The method for preparing calcium sulfate hemihydrate whiskers by purifying phosphogypsum under normal pressure according to claim 7, characterized by comprising the following steps: the water used for size mixing in the step (1-1) is clear water, sulfuric acid is used as a pH value regulator, and the adding amount is 0.5-1.5 kg/t of slurry.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110101811.0A CN112941632A (en) | 2021-01-26 | 2021-01-26 | Method for preparing calcium sulfate hemihydrate crystal whisker by purifying phosphogypsum under normal pressure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110101811.0A CN112941632A (en) | 2021-01-26 | 2021-01-26 | Method for preparing calcium sulfate hemihydrate crystal whisker by purifying phosphogypsum under normal pressure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112941632A true CN112941632A (en) | 2021-06-11 |
Family
ID=76236817
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110101811.0A Pending CN112941632A (en) | 2021-01-26 | 2021-01-26 | Method for preparing calcium sulfate hemihydrate crystal whisker by purifying phosphogypsum under normal pressure |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112941632A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114605095A (en) * | 2022-04-01 | 2022-06-10 | 湖北裕得水环保科技有限公司 | One-tower step separation, impurity removal and purification process for phosphogypsum |
| CN115010162A (en) * | 2022-04-15 | 2022-09-06 | 湖北省长江资源循环利用及装备创新中心有限公司 | Method for removing impurities and whitening by floating-chemical coupling of phosphogypsum |
| CN115650276A (en) * | 2022-10-25 | 2023-01-31 | 湖北三峡实验室 | Comprehensive recovery method of phosphogypsum resources |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103464288A (en) * | 2013-09-17 | 2013-12-25 | 云南省化工研究院 | Method for removing silicon from phosphogypsum in obverse floatation way under acidic condition |
| CN111286787A (en) * | 2020-02-27 | 2020-06-16 | 武汉工程大学 | Method for preparing gypsum whisker by sulfur-phosphorus mixed acid method |
-
2021
- 2021-01-26 CN CN202110101811.0A patent/CN112941632A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103464288A (en) * | 2013-09-17 | 2013-12-25 | 云南省化工研究院 | Method for removing silicon from phosphogypsum in obverse floatation way under acidic condition |
| CN111286787A (en) * | 2020-02-27 | 2020-06-16 | 武汉工程大学 | Method for preparing gypsum whisker by sulfur-phosphorus mixed acid method |
Non-Patent Citations (2)
| Title |
|---|
| 孙晓灵: "半水硫酸钙晶须的制备及改性研究", 中国优秀硕士学位论文全文数据库工程科技Ⅰ辑, vol. 8, no. 8, 15 August 2019 (2019-08-15), pages 28 - 36 * |
| 孙晓灵: "半水硫酸钙晶须的制备及改性研究", 中国优秀硕士学位论文全文数据库工程科技Ⅰ辑, vol. 8, pages 28 - 36 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114605095A (en) * | 2022-04-01 | 2022-06-10 | 湖北裕得水环保科技有限公司 | One-tower step separation, impurity removal and purification process for phosphogypsum |
| CN115010162A (en) * | 2022-04-15 | 2022-09-06 | 湖北省长江资源循环利用及装备创新中心有限公司 | Method for removing impurities and whitening by floating-chemical coupling of phosphogypsum |
| CN115010162B (en) * | 2022-04-15 | 2023-11-10 | 湖北省长江资源循环利用及装备创新中心有限公司 | Phosphogypsum floating-chemical coupling impurity removal and whitening method |
| CN115650276A (en) * | 2022-10-25 | 2023-01-31 | 湖北三峡实验室 | Comprehensive recovery method of phosphogypsum resources |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112941632A (en) | Method for preparing calcium sulfate hemihydrate crystal whisker by purifying phosphogypsum under normal pressure | |
| CN102925956B (en) | Method for preparing calcium sulfate hemihydrate whiskers by taking ardealite as main raw material | |
| EP3351506B1 (en) | Method for producing phosphoric acid and by-producing alpha-hemihydrate gypsum by wet-process | |
| CN102531001B (en) | Comprehensive soda ash producing process and product application thereof | |
| CN103508689B (en) | A kind of low cost prepares the method for alpha semi-hydrated gypsum and prepared alpha semi-hydrated gypsum and gypsum block | |
| CN104445311B (en) | Poly-generation clean preparation method of high-content silicon dioxide fly ash | |
| CN100494051C (en) | Technology for preparing fine calcium phosphate using phosphor-gypsum backwater and its wash liquid | |
| CN110747503B (en) | Method for preparing calcium sulfate hemihydrate crystal whiskers by irradiating phosphogypsum with microwaves under normal pressure | |
| CN102001636A (en) | Method for producing broad-concentration phosphoric acid and clean plaster by middle-low grade phosphorus ore wet process | |
| CN100545324C (en) | The preparation method of a kind of calcium sulfate crystal whiskers and phosphoric acid | |
| CN107419335A (en) | The method that hydrochloric acid method Cycle-decomposition ardealite and phosphorus mine tailing prepare calcium sulfate crystal whiskers | |
| CN107879321B (en) | Method for demagging phosphate rock and co-producing sodium fluosilicate and magnesium sulfate | |
| CN108796612B (en) | Method for preparing calcium sulfate whisker and co-producing ammonium sulfate by phosphogypsum cyclic decomposition | |
| CN105350066B (en) | A kind of method that ardealite prepares hemihydrate calcium sulfate crystal whisker | |
| CN111392702B (en) | Method for preparing concentrated phosphoric acid and gypsum powder by semi-hydrated dihydrate process | |
| CN107381610A (en) | A kind of method that aluminium polychloride is prepared using red mud | |
| CN103466579A (en) | Method for producing full-water-soluble monoammonium phosphate by phosphoric acid by wet process | |
| CN103232052B (en) | Method for preparing high-purity calcium carbonate directly from phosphogypsum | |
| CN1062844C (en) | Process for producing potassium sulfate and its by-product using potassium ore | |
| CN105002521A (en) | Method for removing magnesium impurities in electrolytic manganese system through fluorine-bearing minerals | |
| CN105384157A (en) | Technology for producing phosphoric acid through half-hydrate-dihydrate method | |
| CN108439451A (en) | The method for preparing precipitated calcium carbonate using ardealite | |
| CN116768170A (en) | Method for preparing phosphoric acid and derivatives thereof by using phosphorite | |
| CN115716721A (en) | Method for directly preparing anhydrous gypsum by using phosphogypsum | |
| CN110894066A (en) | Method for preparing sheet iron phosphate from titanium dioxide slag |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |