CN115286030B - Method for producing gypsum whisker by transforming gypsum powder - Google Patents
Method for producing gypsum whisker by transforming gypsum powder Download PDFInfo
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- 229910052602 gypsum Inorganic materials 0.000 title claims abstract description 108
- 239000010440 gypsum Substances 0.000 title claims abstract description 108
- 239000000843 powder Substances 0.000 title claims abstract description 46
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 19
- 230000001131 transforming effect Effects 0.000 title description 4
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims abstract description 84
- 229910000019 calcium carbonate Inorganic materials 0.000 claims abstract description 42
- 238000006243 chemical reaction Methods 0.000 claims abstract description 37
- 238000003756 stirring Methods 0.000 claims abstract description 31
- 238000000034 method Methods 0.000 claims abstract description 27
- 239000011575 calcium Substances 0.000 claims abstract description 24
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims abstract description 21
- 235000011130 ammonium sulphate Nutrition 0.000 claims abstract description 21
- 239000002002 slurry Substances 0.000 claims abstract description 20
- 238000010438 heat treatment Methods 0.000 claims abstract description 17
- 238000001914 filtration Methods 0.000 claims abstract description 14
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 claims abstract description 13
- PRKQVKDSMLBJBJ-UHFFFAOYSA-N ammonium carbonate Chemical compound N.N.OC(O)=O PRKQVKDSMLBJBJ-UHFFFAOYSA-N 0.000 claims abstract description 11
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims abstract description 9
- 238000002156 mixing Methods 0.000 claims abstract description 8
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 30
- 239000001110 calcium chloride Substances 0.000 claims description 27
- 229910001628 calcium chloride Inorganic materials 0.000 claims description 27
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims description 27
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 claims description 24
- 230000009466 transformation Effects 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 16
- 239000007788 liquid Substances 0.000 claims description 13
- 239000001099 ammonium carbonate Substances 0.000 claims description 9
- 235000019270 ammonium chloride Nutrition 0.000 claims description 8
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims description 7
- 229910001424 calcium ion Inorganic materials 0.000 claims description 7
- 238000001556 precipitation Methods 0.000 claims description 7
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 claims description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 5
- 235000012538 ammonium bicarbonate Nutrition 0.000 claims description 5
- 229910052791 calcium Inorganic materials 0.000 claims description 5
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 claims description 4
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 4
- 235000012501 ammonium carbonate Nutrition 0.000 claims description 4
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 4
- 230000035484 reaction time Effects 0.000 claims description 4
- 239000003153 chemical reaction reagent Substances 0.000 claims description 3
- 238000000354 decomposition reaction Methods 0.000 claims description 3
- 238000007670 refining Methods 0.000 claims description 3
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 claims description 2
- 239000001166 ammonium sulphate Substances 0.000 claims description 2
- 239000011736 potassium bicarbonate Substances 0.000 claims description 2
- 235000015497 potassium bicarbonate Nutrition 0.000 claims description 2
- 229910000028 potassium bicarbonate Inorganic materials 0.000 claims description 2
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 2
- 235000011181 potassium carbonates Nutrition 0.000 claims description 2
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 claims description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 2
- 235000017550 sodium carbonate Nutrition 0.000 claims description 2
- 238000005979 thermal decomposition reaction Methods 0.000 claims description 2
- 239000002699 waste material Substances 0.000 claims description 2
- 230000008569 process Effects 0.000 abstract description 9
- 239000000243 solution Substances 0.000 description 34
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical group N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 19
- 150000002500 ions Chemical class 0.000 description 18
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical group O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 16
- 239000000047 product Substances 0.000 description 13
- 238000002360 preparation method Methods 0.000 description 12
- 239000000706 filtrate Substances 0.000 description 11
- 229940095672 calcium sulfate Drugs 0.000 description 10
- 150000004683 dihydrates Chemical class 0.000 description 10
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical group O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 description 9
- 229910021529 ammonia Inorganic materials 0.000 description 8
- 239000001569 carbon dioxide Chemical group 0.000 description 8
- 229910002092 carbon dioxide Chemical group 0.000 description 8
- 238000004090 dissolution Methods 0.000 description 6
- 239000002994 raw material Substances 0.000 description 6
- 238000003786 synthesis reaction Methods 0.000 description 6
- 238000002425 crystallisation Methods 0.000 description 5
- 238000004064 recycling Methods 0.000 description 5
- 239000002893 slag Substances 0.000 description 5
- 239000012065 filter cake Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000003960 organic solvent Substances 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000005342 ion exchange Methods 0.000 description 3
- 239000011777 magnesium Substances 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 239000012266 salt solution Substances 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- 238000001027 hydrothermal synthesis Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000000593 microemulsion method Methods 0.000 description 2
- 238000000614 phase inversion technique Methods 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229940095564 anhydrous calcium sulfate Drugs 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- NKWPZUCBCARRDP-UHFFFAOYSA-L calcium bicarbonate Chemical compound [Ca+2].OC([O-])=O.OC([O-])=O NKWPZUCBCARRDP-UHFFFAOYSA-L 0.000 description 1
- 229910000020 calcium bicarbonate Inorganic materials 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- -1 meanwhile Chemical compound 0.000 description 1
- 239000000693 micelle Substances 0.000 description 1
- 239000004530 micro-emulsion Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000012066 reaction slurry Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000011426 transformation method Methods 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
- C01F11/466—Conversion of one form of calcium sulfate to another
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention discloses a method for producing gypsum whiskers by converting gypsum powder, which comprises the steps of mixing gypsum powder slurry with ammonium carbonate salt and/or ammonium bicarbonate salt, stirring at room temperature for reaction I, and then heating and stirring for reaction II; or mixing gypsum powder slurry with carbonate, stirring at room temperature for reaction I, filtering to separate calcium carbonate, adding the calcium carbonate into a solution containing ammonium sulfate, and heating and stirring for reaction II to obtain the gypsum. The method is realized by controlling Ca in solution 2+ Is supersaturated with NH 4 + Is guided to force Ca 2+ With SO 4 2‑ When combined again, the fibrous gypsum whisker is formed by directional growth, and the method has the advantages of simple process, high production efficiency, good product quality, low production cost, convenient operation and the like, and is suitable for industrial application of gypsum powder for producing the gypsum whisker in large scale under normal pressure.
Description
Technical Field
The invention relates to a preparation method of gypsum whisker, in particular to a method for producing gypsum whisker by converting gypsum powder, belonging to the field of preparation of inorganic materials.
Background
In general, ca is contained in 2+ Solutions of ions and SO-containing 4 2- After mixing the ionic solutions, calcium sulfate dihydrate (CaSO) having a layered crystal structure is formed 4 ·2H 2 O) gypsum powder, but by controlling the rate of growth of calcium sulfate dihydrate crystals, gypsum whiskers having a diameter reaching the nanometer level can be obtained in a fibrous structure. The gypsum whisker is a material with high cost performance, good mechanical property and environmental friendliness, and can be applied to the fields of composite materials, papermaking, catalysis, biodegradable materials and the like.
As early as 1960, a preparation method of the gypsum whisker has been proposed abroad, and after decades of development, the preparation technology of the gypsum whisker is gradually mature, and the preparation method of the gypsum whisker is divided into three types, namely a phase transformation method, a crystallization method and a chemical synthesis method.
The phase inversion method is to prepare whisker by converting gypsum dihydrate phase into semi-aqueous phase. The raw material is dihydrate gypsum, and the product is hemihydrate gypsum whisker. The transition temperature of the dihydrate gypsum to the hemihydrate gypsum is 107 ℃, and the endothermic phenomenon is found to exist at about 110 ℃ in the phase change reaction through experiments. Therefore, the conversion of the dihydrate gypsum to the hemihydrate gypsum can be performed by adopting a hydrothermal method, a salt solution method and an organic solvent method. The hydrothermal method adopts pure water as a solvent, and the gypsum powder is added and then high-pressure reaction is carried out in an autoclave; due to the adoption of high pressure, the boiling point of water is increased toThe transition temperature from the dihydrate gypsum to the hemihydrate gypsum is reached, and the preparation of hemihydrate gypsum whisker is further realized. The salt solution method is to add CaCl into pure water 2 And H 2 SO 4 Or HCl is prepared into salt solution, then gypsum powder is added, and the semi-hydrated gypsum whisker is prepared by heating reaction under normal pressure. The organic solvent method adopts an organic solvent aqueous solution mainly containing alcohol substances as a reaction system to improve the boiling point of water, thereby meeting the requirement of the transition temperature from the dihydrate gypsum to the hemihydrate gypsum. Thereby enabling whisker preparation in the liquid phase. The phase inversion method has the defect that the phase inversion is incomplete, and the yield of gypsum whiskers is affected.
The crystallization method is based on the principle that calcium sulfate dihydrate is dissolved in solvents of different media and supersaturated crystals are generated when the temperature is lowered. The powdered gypsum is dissolved at 70-110 deg.c, and the solution is cooled to 20-40 deg.c to crystallize gypsum dihydrate whisker, with the gypsum dihydrate whisker being produced with the material and product. The crystallization method mainly depends on the reduction of the system temperature to reduce the solubility to provide supersaturation, so the cooling process is the most important process in the crystallization method for preparing gypsum whiskers. However, calcium sulfate has limited solubility in solution, and its solubility does not change much with temperature rise and fall, and the production efficiency of producing gypsum dihydrate whiskers by crystallization is low.
The chemical synthesis method uses Ca 2+ With SO 4 2- Combine to form CaSO 4 Whisker preparation is carried out by double decomposition reaction of (a) and the raw material is Ca-containing 2+ Salts of (e.g. CaCl) 2 ) And SO-containing 4 2- Salts (e.g., (NH) 4 ) 2 SO 4 ) The product is typically calcium sulfate hemihydrate whiskers. The chemical synthesis method needs to strictly control the reaction conditions to avoid Ca 2+ With SO 4 2- The reaction is too fast to form a large number of un-grown nuclei. The chemical synthesis method mainly comprises an ion exchange method and a microemulsion method. The ion exchange method is to reduce Ca by ion exchange 2+ With SO 4 2- The reaction rate of (2) to achieve whisker preparation. The microemulsion method uses a thermodynamically stable heterogeneous dispersion system formed by two immiscible liquids to reduce the reaction rate for carrying out gypsum whiskerPreparing, forming reverse micelle by adopting organic solvent and surfactant, and adding Ca 2+ With SO 4 2- Is wrapped inside, and the nonpolar end is left outside to form a microemulsion system. Because of the harsh technological conditions for producing the gypsum whisker by the chemical synthesis method, the yield of the gypsum whisker is limited, the production cost is high, and the product price is high.
Disclosure of Invention
Aiming at the defects of low yield, low production efficiency, complex process and the like of the gypsum whisker in the prior art, the invention aims to provide a method for producing the gypsum whisker by converting gypsum powder.
In order to achieve the technical aim, the invention provides a method for producing gypsum whiskers by converting gypsum powder, which comprises the steps of mixing gypsum powder slurry with ammonium carbonate salt and/or ammonium bicarbonate salt, stirring at room temperature for reaction I, and then heating and stirring for reaction II to obtain the gypsum whisker; or mixing gypsum powder slurry with carbonate, stirring at room temperature for reaction I, filtering to separate calcium carbonate, adding the calcium carbonate into a solution containing ammonium sulfate, and heating and stirring for reaction II to obtain the gypsum.
The invention uses gypsum powder as raw material, firstly uses carbonate to convert calcium sulfate into calcium carbonate, then uses calcium carbonate as raw material, uses ammonium sulfate solution as transforming agent, under the heating condition, makes calcium carbonate slowly decompose in ammonium sulfate weak acid solution, and at the same time controls Ca in solution 2+ Supersaturation of ions and at NH 4 + Under the guidance of ions, ensure Ca 2+ Ions and SO 4 2- When the ions are recombined, the ions grow directionally to form fibrous gypsum whiskers.
The basic principle of the method is as follows:
CaSO 4 +(NH 4 ) 2 CO 3 ＝(NH 4 ) 2 SO 4 +CaCO 3 ↓ (1)
CaCO 3 +(NH 4 ) 2 SO 4 +H 2 O＝Δ＝CaSO 4 ·2H 2 O↓+CO 2 ↑+2NH 3 ↑ (2)
CaCO 3 +(NH 4 ) 2 SO 4 ＝Δ＝CaSO 4 ·0.5H 2 O↓+0.5H 2 O+CO 2 ↑+2NH 3 ↑ (3)
in the above preparation process, the calcium carbonate reacted with the solution containing ammonium sulfate may be crude calcium carbonate or refined calcium carbonate or reagent calcium carbonate. The solution containing ammonium sulfate can be obtained by purifying filtrate containing ammonium sulfate obtained by reacting gypsum powder slurry with ammonium carbonate salt, or solution prepared by ammonium sulfate reagent, wherein the solution also contains 0-2 mol/L Cl - 、Na + Mg and Mg 2+ . The purification process comprises the following steps: adding calcium sulfate into the obtained filtrate containing ammonium sulfate, stirring at room temperature or ball milling with stirring, and adsorbing and removing impurities such as fluorine, phosphorus and the like in the solution; or adding soluble calcium selected from at least one of calcium chloride, calcium nitrate, calcium bicarbonate and calcium hydroxide, and stirring to remove fluorine, phosphorus and other impurities in the solution.
As a preferred embodiment, the gypsum powder includes at least one of natural gypsum powder, industrial gypsum powder, refined gypsum powder, gypsum whisker waste, and a calcium sulfate agent. The industrial gypsum is gypsum formed by treating sulfur-containing industrial wastewater and waste gas with lime.
As a preferable scheme, the solid-to-liquid ratio in the gypsum powder slurry is 1:1-10 g/mL.
As a preferred embodiment, the carbonate includes at least one of ammonium carbonate, ammonium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate. The ammonium carbonate or bicarbonate can be replaced with ammonia and carbon dioxide.
As a preferred embodiment, the molar amount of the ammonium carbonate salt and/or ammonium bicarbonate salt is 1 to 2 times the molar amount of calcium ions in the gypsum powder slurry.
As a preferred embodiment, the molar amount of the carbonate is 1 to 2 times the molar amount of calcium ions in the gypsum powder slurry.
As a preferred embodiment, the conditions for stirring reaction I are: the pH value is 8.5-10.5, and the time is 0.5-2.5 h.
As a preferred embodiment, the calcium carbonate precipitate is subjected to the following refining pretreatment: adding water into calcium carbonate to slurry, adding ammonium chloride and/or ammonium nitrate to perform thermal decomposition reaction, filtering to obtain calcium chloride and/or calcium nitrate solution, performing calcium precipitation reaction on the calcium chloride and/or calcium nitrate solution and ammonium carbonate salt, and filtering to obtain refined calcium carbonate.
The basic principle of the method for refining calcium carbonate is as follows:
CaCO 3 +2NH 4 Cl＝Δ＝CaCl 2 +H 2 O+CO 2 ↑+2NH 3 ↑ (4)
CaCO 3 +2NH 4 NO 3 ＝Δ＝Ca(NO 3 ) 2 +H 2 O+CO 2 ↑+2NH 3 ↑ (5)
CaCl 2 +(NH 4 ) 2 CO 3 ＝2NH 4 Cl+CaCO 3 ↓ (6)
Ca(NO 3 ) 2 +(NH 4 ) 2 CO 3 ＝2NH 4 NO 3 +CaCO 3 ↓ (7)
CaCl 2 +(NH 4 ) 2 SO 4 +2H 2 O＝2NH 4 Cl+CaSO 4 ·2H 2 O↓ (8)
Ca(NO 3 ) 2 +(NH 4 ) 2 SO 4 +2H 2 O＝2NH 4 NO 3 +CaSO 4 ·2H 2 O↓ (9)
the ammonia and carbon dioxide-containing gas generated in the process is collected and utilized, the slurry obtained by the reaction is filtered to obtain filtrate containing calcium chloride or calcium nitrate and insoluble filter residues, wherein the insoluble filter residues are collected and then are concentrated, the obtained filtrate containing the calcium chloride or the calcium nitrate is added with ammonium carbonate or is blown into ammonia gas and carbon dioxide gas to enable calcium ions in the filtrate to be precipitated in the form of calcium carbonate, and the filtrate containing the refined calcium carbonate and the filtrate containing the ammonium chloride or the ammonium nitrate can be obtained after filtration, and the filtrate containing the ammonium chloride or the ammonium nitrate can be recycled. In addition, the obtained filtrate containing calcium chloride or calcium nitrate is mixed with ammonium sulfate to react, so that refined gypsum can be obtained, and the refined gypsum can be used as a raw material for producing gypsum whiskers, thereby realizing the internal recycling of the material.
As a preferable embodiment, the decomposition reaction conditions are: the solid-liquid ratio of the calcium carbonate to the water is 1:2-8 g/mL, the total molar amount of the ammonium chloride and/or the ammonium nitrate is 2-4 times of the molar amount of the calcium carbonate, the reaction temperature is 75-115 ℃, and the reaction time is 0.5-3.5 h.
As a preferred embodiment, the calcium precipitation reaction conditions are: the molar amount of the ammonium carbonate salt is 1 to 1.5 times of the total molar amount of calcium ions in the calcium chloride and/or calcium nitrate solution; the pH value of the solution system is 8.5-10.5, the reaction temperature is room temperature, and the reaction time is 0.5-1.5 h.
As a preferable scheme, ca in the calcium carbonate 2+ With SO in a solution containing ammonium sulphate 4 2- The molar ratio of (2) is 1:1-1.5.
As a preferable scheme, the conditions of the heating and stirring reaction II are as follows: the temperature is 60-115 ℃ and the time is 1-3 h.
As a preferable scheme, after the heating and stirring reaction II is completed, fibrous products are separated from the reaction slurry, and the obtained products are washed and dried to obtain the gypsum whisker products.
The invention also provides a gypsum whisker, which is prepared by the method.
As a preferable scheme, the gypsum whisker is at least one of calcium sulfate dihydrate whisker, calcium sulfate hemihydrate whisker and anhydrous calcium sulfate whisker.
Compared with the prior art, the invention has the following advantages and effects:
(1) The invention uses gypsum powder as raw material, firstly uses carbonate solution to convert calcium sulfate into calcium carbonate, then adds the obtained calcium carbonate into ammonium sulfate weak acid solution, and makes it be heated and slowly decomposed so as to control Ca in the solution 2+ Supersaturation of ions by NH 4 + Ion guiding to ensure Ca 2+ Ions and SO 4 2- When the ions are recombined, the ions grow directionally to form fibrous gypsum whiskers;
(2) The preparation process is simple, the production efficiency is high, the product quality is good, the production cost is low, the operation is convenient, and the like, and the method is suitable for industrial application of gypsum powder for large-scale production of gypsum whisker at normal pressure.
Detailed Description
The invention is further described in connection with the following examples which are intended to illustrate the invention and are not intended to be limiting.
Example 1
Taking CaSO 4 ·2H 2 100g of desulfurized gypsum with 88.9% of O content is added with water and ground to obtain 300mL of slurry, 50g of ammonium bicarbonate is added, the pH value is regulated to 8.6-9.3 by ammonia, the slurry is stirred at room temperature for 1.5h for primary transformation, calcium sulfate in the slurry is converted into calcium carbonate, primary transformation slag and primary transformation liquid are obtained by filtration, water is added into the primary transformation slag according to the solid-to-liquid ratio of 1:4g/mL, ammonium chloride is added according to 1.2 times of the theoretical amount of calcium chloride in the primary transformation slag, the secondary transformation is carried out on the primary transformation slag by heating and stirring, the temperature is 89-102 ℃ for 2h, the calcium carbonate in the primary transformation slag is decomposed and converted into calcium chloride, ammonia and carbon dioxide-containing gas generated in the secondary transformation process is collected, the primary transformation is returned for recycling, the solution containing calcium chloride and insoluble filter residues are obtained by filtering, the insoluble filter residues are collected and concentrated and treated, the obtained calcium chloride solution is blown into carbon dioxide and ammonia according to 1.2 times of the required chemical conversion of calcium carbonate, the ammonia and the pH value is maintained to be 1.2 times of the theoretical amount of calcium chloride, the solution containing calcium chloride is refined, the obtained by stirring is returned to the filter cake after the secondary transformation is stirred for 1h, the calcium chloride-containing calcium chloride is refined, the obtained is filtered, the solution is recycled according to the pH value is subjected to the secondary transformation, and the calcium chloride-containing solution is obtained after the calcium chloride is subjected to the secondary precipitation and is recycled to the filter and is subjected to the recycling to the step of the calcium chloride precipitation and is subjected to the recycling to 1h to the calcium chloride precipitation and is recycled to 2+ /SO 4 2- Adding refined calcium carbonate filter cake into primary transformation liquid purified by calcium sulfate in a molar ratio of 1:1.1, adding 2.5g anhydrous magnesium chloride, heating and stirring, reacting for 1.5h at 85-97 ℃, filtering until no bubbles are generated in the slurryThe fibrous product and the synthesized liquid thereof are obtained, and the fibrous product is washed and dried to obtain the dihydrate gypsum whisker with the whiteness of more than 95 percent, the diameter of 7-13 mu m and the length of 118-246 mu m. Carbon dioxide and ammonia gas generated during the synthesis of the gypsum whisker are collected and returned to be used for producing refined calcium carbonate, and the synthesized liquid of the obtained gypsum whisker is returned to be used as a primary transformation solution of the desulfurized gypsum, so that the closed cycle of water, ammonium chloride, ammonia and carbon dioxide gas used in the process is realized.
Example 2
Taking CaSO 4 ·2H 2 150g of natural gypsum powder containing a small amount of magnesium and sodium with the O content of 95.2 percent is added with water for size mixing according to the solid-to-liquid ratio of 1:4g/mL, ammonium bicarbonate is added according to 1.2 times of the theoretical amount of calcium sulfate converted into calcium carbonate, meanwhile, ammonia is used for regulating the pH value of the solution to 8.5-9.6, stirring and transforming is carried out for 1h at room temperature, after the calcium sulfate is converted into calcium carbonate, heating and stirring are carried out, firstly, the residual ammonium carbonate salt is decomposed to be converted into a solution containing ammonium sulfate, and the characteristic that the ammonium sulfate solution is slightly acidic is utilized to promote the calcium carbonate to be slowly decomposed when being heated, so as to control Ca in the solution 2+ Supersaturation of ions by NH 4 + Ion guiding to ensure Ca 2+ Ions and SO 4 2- When the ions are recombined, the ions grow directionally to form gypsum whiskers, stirring and reacting for 2 hours at 95-108 ℃, stopping heating and stirring when no bubble is generated in the slurry, taking out fibrous products, and washing and drying the fibrous products to obtain 109.5g of semi-hydrated gypsum whiskers with the whiteness of more than 94% and the diameter of 13-37 mu m and the length of 286-512 mu m; filtering residual liquid after the fibrous products are fished out to obtain filtrate and filter residues, carrying out centralized treatment on the filter residues, and returning the filtrate to a decomposing liquid for preparing calcium carbonate; carbon dioxide and ammonia gas generated in the process of decomposing calcium carbonate are collected and returned to the process of converting calcium sulfate into calcium carbonate for recycling.
Comparative example 1
80g of analytically pure anhydrous calcium chloride (CaCl) was first taken 2 ) Adding 200mL of water for dissolution, then adding 100g of ammonium sulfate into 400mL of water for dissolution, heating and stirring, and slowly dropwise adding the calcium chloride solution obtained by dissolution into the water at 115 ℃ for 1h after the completion of dropwise addition,stirring for 0.5h, filtering, washing, and drying the filter cake to obtain 100.6g of calcium sulfate hemihydrate powder.
Comparative example 2
100g of analytically pure calcium nitrate (Ca (NO) 3 ) 2 ) Adding 300mL of water for dissolution, adding 82g of ammonium sulfate into 500mL of water for dissolution, heating and stirring, slowly dripping the calcium nitrate solution obtained by dissolution into the ammonium sulfate solution at 90 ℃, stirring for 0.5h at constant temperature after 1.5h of dripping is finished, filtering, washing, and drying a filter cake at 85 ℃ for 2h to obtain 98.2g of calcium sulfate dihydrate powder.
As is clear from the experiment of the comparative example, only gypsum powder can be obtained by directly adopting the reaction of soluble calcium salt and ammonium sulfate, and gypsum whisker can not be obtained, but by adopting the preparation method of the invention, calcium carbonate is added into the weak acidic solution of ammonium sulfate to be heated and slowly decomposed, so that Ca in the solution is effectively controlled 2+ Supersaturation of ions to achieve Ca 2+ Ions and SO 4 2- And during ion bonding, the oriented ordered growth is carried out to form fibrous gypsum whiskers, so that the gypsum whiskers are obtained.
Claims (7)
1. A method for producing gypsum whiskers by gypsum powder transformation is characterized in that: mixing gypsum powder slurry with ammonium carbonate salt and/or ammonium bicarbonate salt, stirring at room temperature for reaction I, and heating for stirring for reaction II to obtain the gypsum powder; or mixing gypsum powder slurry with carbonate, stirring at room temperature for reaction I, filtering to separate calcium carbonate, adding the calcium carbonate into a solution containing ammonium sulfate, and heating for stirring for reaction II to obtain the gypsum powder;
ca in the calcium carbonate 2+ With SO in a solution containing ammonium sulphate 4 2- The molar ratio of (2) is 1:1-1.5;
the conditions of the stirring reaction I are as follows: the pH is 8.5-10.5, and the time is 0.5-2.5 h;
the conditions of the heating and stirring reaction II are as follows: the temperature is 60-115 ℃ and the time is 1-3 h.
2. A method for producing gypsum whiskers from a gypsum powder of claim 1, wherein:
the gypsum powder comprises at least one of natural gypsum powder, industrial gypsum powder, refined gypsum powder, gypsum whisker waste and a calcium sulfate reagent;
the solid-liquid ratio in the gypsum powder slurry is 1:1-10 g/mL.
3. A method for producing gypsum whiskers by transformation of gypsum powder according to claim 1 or 2, characterized in that: the carbonate comprises at least one of ammonium carbonate, ammonium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate.
4. A method for producing gypsum whiskers by transformation of gypsum powder according to claim 1 or 2, characterized in that:
the molar amount of the ammonium carbonate salt and/or ammonium bicarbonate salt is 1-2 times of the molar amount of calcium ions in the gypsum powder slurry;
the molar amount of the carbonate is 1-2 times of the molar amount of calcium ions in the gypsum powder slurry.
5. A method for producing gypsum whiskers from gypsum powder according to claim 1, characterized in that: the calcium carbonate was subjected to the following refining pretreatment: adding water into calcium carbonate to slurry, adding ammonium chloride and/or ammonium nitrate to perform thermal decomposition reaction, filtering to obtain calcium chloride and/or calcium nitrate solution, performing calcium precipitation reaction on the calcium chloride and/or calcium nitrate solution and ammonium carbonate salt, and filtering to obtain refined calcium carbonate.
6. A method for producing gypsum whiskers from gypsum powder according to claim 5, characterized in that:
the decomposition reaction conditions are as follows: the solid-to-liquid ratio of the calcium carbonate to the water is 1:2-8 g/mL, the total molar amount of the ammonium chloride and/or the ammonium nitrate is 2-4 times of the molar amount of the calcium carbonate, the reaction temperature is 75-115 ℃, and the reaction time is 0.5-3.5 h;
the conditions of the calcium precipitation reaction are as follows: the molar amount of the ammonium carbonate salt is 1-1.5 times of the total molar amount of calcium ions in the calcium chloride and/or calcium nitrate solution; the pH value of the solution system is 8.5-10.5, the reaction temperature is room temperature, and the reaction time is 0.5-1.5 h.
7. A gypsum whisker, characterized in that: is prepared by the method of any one of claims 1 to 6.
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| JP2000053418A (en) * | 1998-08-07 | 2000-02-22 | Shikoku Chem Corp | Production of gypsum fiber |
| CN104495774A (en) * | 2014-12-08 | 2015-04-08 | 宜昌市三峡天润纳米材料工程技术研究中心有限公司 | Method for co-production of nanometer hydroxyapatite and calcium sulfate whisker from phosphogypsum |
| CN107583466A (en) * | 2017-09-27 | 2018-01-16 | 四川恒泰环境技术有限责任公司 | A kind of method that wet desulphurization gypsum is converted into ammonium sulfate and calcium carbonate and recycled |
| CN112877780A (en) * | 2021-01-14 | 2021-06-01 | 江西理工大学 | Method for preparing calcium sulfate hemihydrate crystal whisker by ammonia distillation waste liquid hydrothermal method |
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| US11148956B2 (en) * | 2019-01-24 | 2021-10-19 | Elixsys, Inc. | Systems and methods to treat flue gas desulfurization waste to produce ammonium sulfate and calcium carbonate products |
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| JP2000053418A (en) * | 1998-08-07 | 2000-02-22 | Shikoku Chem Corp | Production of gypsum fiber |
| CN104495774A (en) * | 2014-12-08 | 2015-04-08 | 宜昌市三峡天润纳米材料工程技术研究中心有限公司 | Method for co-production of nanometer hydroxyapatite and calcium sulfate whisker from phosphogypsum |
| CN107583466A (en) * | 2017-09-27 | 2018-01-16 | 四川恒泰环境技术有限责任公司 | A kind of method that wet desulphurization gypsum is converted into ammonium sulfate and calcium carbonate and recycled |
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