CN113845137A - Method for producing high-purity white phosphogypsum from high-impurity-content phosphorite - Google Patents
Method for producing high-purity white phosphogypsum from high-impurity-content phosphorite Download PDFInfo
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- 239000002367 phosphate rock Substances 0.000 title claims abstract description 93
- OJMIONKXNSYLSR-UHFFFAOYSA-N phosphorous acid Chemical compound OP(O)O OJMIONKXNSYLSR-UHFFFAOYSA-N 0.000 title claims abstract description 83
- 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 41
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 35
- 239000010440 gypsum Substances 0.000 claims abstract description 48
- 229910052602 gypsum Inorganic materials 0.000 claims abstract description 48
- 239000012535 impurity Substances 0.000 claims abstract description 48
- 238000006243 chemical reaction Methods 0.000 claims abstract description 46
- 238000000034 method Methods 0.000 claims abstract description 45
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000002893 slag Substances 0.000 claims abstract description 16
- 238000002425 crystallisation Methods 0.000 claims abstract description 14
- 230000008025 crystallization Effects 0.000 claims abstract description 14
- 239000002253 acid Substances 0.000 claims abstract description 13
- 230000000694 effects Effects 0.000 claims abstract description 12
- FFBHFFJDDLITSX-UHFFFAOYSA-N benzyl N-[2-hydroxy-4-(3-oxomorpholin-4-yl)phenyl]carbamate Chemical compound OC1=C(NC(=O)OCC2=CC=CC=C2)C=CC(=C1)N1CCOCC1=O FFBHFFJDDLITSX-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 10
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910001424 calcium ion Inorganic materials 0.000 claims abstract description 7
- 239000007787 solid Substances 0.000 claims abstract description 6
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 68
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 62
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 34
- 238000005406 washing Methods 0.000 claims description 29
- 239000007788 liquid Substances 0.000 claims description 17
- 238000001914 filtration Methods 0.000 claims description 14
- 239000002002 slurry Substances 0.000 claims description 13
- 239000007791 liquid phase Substances 0.000 claims description 12
- 239000000243 solution Substances 0.000 claims description 10
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 9
- 238000005903 acid hydrolysis reaction Methods 0.000 claims description 9
- 229910052698 phosphorus Inorganic materials 0.000 claims description 9
- 239000011574 phosphorus Substances 0.000 claims description 9
- 238000000926 separation method Methods 0.000 claims description 7
- 239000002994 raw material Substances 0.000 claims description 6
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Inorganic materials [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims description 5
- 239000013078 crystal Substances 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 238000003860 storage Methods 0.000 claims description 4
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 claims description 4
- 238000012545 processing Methods 0.000 claims description 2
- 238000004537 pulping Methods 0.000 claims description 2
- 239000012266 salt solution Substances 0.000 claims description 2
- 238000003828 vacuum filtration Methods 0.000 claims description 2
- 150000004683 dihydrates Chemical class 0.000 abstract description 9
- 238000000354 decomposition reaction Methods 0.000 abstract description 6
- 238000009776 industrial production Methods 0.000 abstract description 4
- 238000005265 energy consumption Methods 0.000 abstract description 3
- 238000002360 preparation method Methods 0.000 abstract description 3
- 230000026676 system process Effects 0.000 abstract 1
- 238000002474 experimental method Methods 0.000 description 32
- 238000003756 stirring Methods 0.000 description 20
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 17
- 239000000292 calcium oxide Substances 0.000 description 17
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 17
- 239000000706 filtrate Substances 0.000 description 10
- 238000012360 testing method Methods 0.000 description 9
- 238000010438 heat treatment Methods 0.000 description 8
- 238000002386 leaching Methods 0.000 description 6
- 239000000843 powder Substances 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 238000005485 electric heating Methods 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- 238000005070 sampling Methods 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- 239000004254 Ammonium phosphate Substances 0.000 description 3
- 229910000148 ammonium phosphate Inorganic materials 0.000 description 3
- 235000019289 ammonium phosphates Nutrition 0.000 description 3
- 239000004568 cement Substances 0.000 description 3
- 238000013480 data collection Methods 0.000 description 3
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- FNDXFUBHPXBGMD-UHFFFAOYSA-N OP(O)O.OP(O)(O)=O Chemical compound OP(O)O.OP(O)(O)=O FNDXFUBHPXBGMD-UHFFFAOYSA-N 0.000 description 1
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 1
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 1
- 235000011130 ammonium sulphate Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 238000005352 clarification Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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Classifications
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- 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
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- 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 high-purity white phosphogypsum from high-impurity-content phosphorite, which comprises but is not limited to the following production processes: process 1: the phosphorite is pretreated to remove impurities, high-impurity phosphorite (phosphorite index: P2O5: 18-32%) is added into part of production system process hot water to prepare ore pulp with the temperature of 40-80 ℃ and the solid content of 20-70%, then phosphorite pretreatment agent is added to ensure the pH value to be 2-5, and the low-impurity high-activity phosphorite (P2O5: 18-32%) is obtained after reaction for 1-5 h. Has the advantages that: according to the invention, the phosphorite is subjected to impurity pre-removal treatment before preparation, so that the reaction activity of the phosphorite and the saturation concentration of calcium ions in acid are effectively improved, the problem that black slag generated in the production process of white phosphogypsum is difficult to treat is effectively solved, the black slag is recycled, a higher-concentration dihydrate crystallization process is realized, the reaction energy consumption can be effectively reduced, the yield of white gypsum of the phosphorite is improved, and acidolysis equipment is not excessively large when the decomposition of ore is ensured, so that the industrial production is realized.
Description
Technical Field
The invention relates to the technical field of preparation of high-purity white phosphogypsum, in particular to a method for producing the high-purity white phosphogypsum from phosphorite with high impurity content.
Background
The waste residue produced by wet-process phosphoric acid production is a worldwide problem, the requirement of phosphorus element is indispensable, the production of phosphogypsum is inevitable, and the production of phosphogypsum, whether the phosphogypsum is used for building or used for preparing cement, or used for producing ammonium sulfate and calcium carbonate as by-products, can put forward higher quality requirements on the purity of the phosphogypsum. Namely, the application range can be effectively widened only by improving the purity of the waste slag, and the waste slag is really changed into valuable.
However, with the increasing demand of phosphorus for the development of human socioeconomic, the exploitation amount of phosphorite is increased dramatically, high-grade phosphorite is reduced, the grade of phosphorite is gradually reduced, in the last 80 th century, China adopts concentrated ammonium phosphate slurry for producing high-concentration ammonium phosphate aiming at medium-grade phosphorite, compared with concentrated phosphoric acid, the slurry reduces blockage, and after success, three, four and six cycle engineering is developed in a matching way, namely, thirty thousand tons of ammonium phosphate are produced annually, and gypsum is used for producing forty thousand tons of sulfuric acid and coproducing sixty thousand tons of cement. The technological process has high requirement on the quality of phosphogypsum, SO that the requirement on the quality of phosphorite is high, (the content of gypsum SO3 is required to reach more than 43 percent, wherein the content of phosphorus, fluorine, iron and aluminum is also quite high, the content of gypsum SO3 is mainly used for ensuring the self-heating balance of a sulfuric acid system during the start, SO that the production cost of sulfuric acid is effectively reduced, the content of phosphorus, fluorine, iron and aluminum is mainly used for ensuring the quality of cement clinker), finally, four sets of devices built in the whole country in the last 90 th century are stopped because the cost is high due to the influence of phosphorite, as the grade of the phosphorite is reduced, the price of high-grade phosphorite is higher and higher, the use of low-grade phosphorite is greatly limited, the quality of phosphogypsum is poor, the utilization of the phosphogypsum is influenced, and as the content of impurities of the phosphorite is increased, and as the impurity content of the phosphorite is increased, the dihydrate technology in China is only required to reduce the concentration of an extraction tank P2O5 for maintaining production to ensure that the gypsum crystal is washed, but only alleviates a little contradiction of production, and a large amount of phosphogypsum is piled up like a mountain and cannot be treated.
Disclosure of Invention
The invention aims to solve the problems and provide a method for producing high-purity white phosphogypsum from phosphorite with high impurity content.
The invention realizes the purpose through the following technical scheme:
a method for producing high-purity white phosphogypsum from phosphorite with high impurity content comprises but is not limited to the following production processes:
process 1: pre-treating and removing impurities from phosphorite, namely adding high-impurity phosphorite (the phosphorite index is P2O5: 18-32%) into part of process hot water of a production system to prepare ore pulp with the temperature of 40-80 ℃ and the solid content of 20-70%, adding a phosphorite pre-treating agent, ensuring the pH value to be 2-5, and reacting for 1-5h to obtain low-impurity high-activity phosphorite (P2O5: 18-32%);
and (2) a process: acidolysis separation, namely reacting the low-impurity high-activity phosphorite obtained in the process 1 with phosphoric acid at the temperature of 50-85 ℃ for 1-5h, settling, filtering and separating black residues in the slurry to obtain a clear phosphoric acid solution containing soluble calcium phosphate salt, wherein the acid concentration is 20-32%;
and 3, process: reacting and crystallizing the clear liquid and separating white gypsum, adding the soluble calcium phosphate salt solution obtained in the process 2 into clean industrial sulfuric acid, controlling the temperature to be 50-90 ℃, reacting for 1-4h, crystallizing to generate calcium sulfate dihydrate, settling and concentrating phosphoric acid slurry containing the calcium sulfate dihydrate, returning the clear liquid to an acid hydrolysis tank in the process 2 to react with the phosphorite from the impurity removal in the process 1, wherein part of filter washing liquid returns to the acid hydrolysis tank in the process 2, part of filter washing liquid is used as low-impurity finished phosphoric acid to enter a finished product phosphoric acid storage tank, and high-purity white phosphogypsum (the content of the calcium sulfate dihydrate is more than 99 percent) is used as a subsequent gypsum deep processing raw material;
and 4, process: and (3) black slag treatment, wherein the black slag separated in the process 2 contains 5-35% of incompletely separated phosphorite, part of industrial sulfuric acid is added, the temperature is controlled at 50-90 ℃, the reaction is carried out for 1-4 hours, the ore is continuously decomposed, the calcium sulfate crystallization, filtration, washing and separation are completed, and low-impurity finished phosphoric acid is put into a finished product storage tank.
Furthermore, the ratio of acid hydrolysis phosphoric acid to phosphorite in the process 2 is 8-16 times, so that the activity of the phosphorite and the activity of the phosphoric acid are ensured.
Furthermore, the control of the amount of the reaction sulfuric acid in the process 3 ensures that the concentration of the liquid phase SO3 is controlled to be 8-25g/l, thereby ensuring that the phosphorite is fully decomposed.
Furthermore, the concentration of acid hydrolysis phosphoric acid is controlled to be 20-32%, so that the saturated solubility of calcium sulfate dihydrate is lower, the concentration of calcium ions in an acid neutralization liquid phase is high enough to improve the yield of white gypsum and effectively reduce the black slag amount, the separation of black slag and the mother acid balance of an acid hydrolysis system are convenient to realize, and the discharge amount of waste slag is reduced.
Furthermore, the control of the amount of the reaction sulfuric acid in the process 3 ensures that the concentration of the liquid phase SO3 is controlled to be 8-25g/l, the addition amount of the industrial sulfuric acid is calculated by taking the concentration of the liquid phase calcium ions as a basis, and the concentration of the excessive liquid phase SO3 is controlled to be 8-25g/l, SO that the excessive free sulfuric acid is not introduced into the acid hydrolysis system to generate calcium sulfate precipitate and enter a solid phase, the amount of black slag is increased, the yield of the white gypsum is reduced, and the excessive sulfate radicals are properly controlled to ensure the intercrystalline substitution of the hydrogen phosphate radicals in the crystallization process of the white gypsum.
Further, in order to ensure white gypsum crystallization in the process 3, the returned materials in the thick slurry provide the supersaturation degree of calcium ions and sulfuric acid in the seed crystal and the diluted clear liquid for crystallization, so that the white gypsum crystallization is effectively ensured to be thick, and the intercrystalline phosphorus is reduced.
Further, the purpose of adding part of sulfuric acid in the process 4 is to further decompose the phosphorus ores which are not completely decomposed in the process 2 and complete the crystallization of calcium sulfate, and the adding amount of the sulfuric acid is controlled by 25g/l of the content of liquid-phase SO 3.
Further, the liquid-solid separation in the process 1, the process 2 and the process 3 adopts vacuum filtration, wherein the process 1 adopts primary washing, and washing liquor returns to a system for pulping; no washing in the process 2; 3 times of countercurrent hot water washing is adopted in the process 3.
The invention has the beneficial effects that:
according to the invention, the phosphorite is subjected to impurity pre-removal treatment before preparation, so that the reaction activity of the phosphorite and the saturation concentration of calcium ions in acid are effectively improved, the problem that black slag generated in the production process of white phosphogypsum is difficult to treat is effectively solved, the black slag is recycled, a higher-concentration dihydrate crystallization process is realized, the reaction energy consumption can be effectively reduced, the yield of white gypsum of the phosphorite is improved, and acidolysis equipment is not excessively large when the decomposition of ore is ensured, so that the industrial production is realized.
Drawings
FIG. 1 is a production flow chart of the method for producing high-purity white phosphogypsum from high-impurity content phosphorite.
Detailed Description
Unless defined otherwise, technical terms used in the following examples have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs.
The present invention will be described in detail below with reference to specific experiments.
Experiment one
1. The name of the experiment: adding phosphorite pretreating agent (inorganic mixed acid) into powdered rock phosphate to remove impurities
2. Experimental equipment and model: the heating electric furnace, the 316L reactor with frequency-variable speed-regulating stirring (self-made) and the glass beaker. An electric heating oven, a vacuum pump, a Buchner funnel, filter paper and pH test paper.
3. Experiment raw materials: phosphate rock pretreating agent, phosphate rock powder and distilled water
4. The experimental principle is as follows: the impurities existing in the chemical state of carbonate in the ground phosphate rock have high chemical reaction activity, can be quickly decomposed when meeting acid to release gaseous carbon dioxide, and cations are dissolved in the phosphoric acid. The experiment utilizes the characteristic to find a proper pretreating agent and control parameters to remove impurities in the phosphorite and obtain the high-activity phosphorite.
5. Purpose of the experiment: remove impurities in the phosphorite and improve the activity of the phosphorite.
6. The experimental steps are as follows:
1) and (5) checking the self-made reaction system, adding two thirds of water, and checking whether the reaction tank leaks water. Whether the stirring is flexible or not and whether the connection is stable or not. After all is normal, the position is adjusted (the paddle is 7 cm from the bottom of the reaction tank).
2) And after the system is normal, the power supply is switched on, whether the power supply is normally electrified or not is switched on, the electric furnace is heated, and the electric furnace is detected by the test pencil, so that the system is ensured to be electricity-tight.
3) And electrifying, starting stirring to test after all the components are normal, stopping stirring after all the components are normal, powering off, and cleaning the reaction tank.
4) Meanwhile, a plastic utensil capable of containing 60kg of phosphate rock is prepared, and two plastic barrels with enough strength are prepared. Thermometer, 500ml beaker, 100ml graduated cylinder, etc.
5) Adding a phosphorite pretreating agent to a height of 17.5cm, starting stirring, starting an electric furnace to raise the temperature of acid to 70 ℃, adding 12kg of phosphorite powder (slowly adding), starting timing after detecting the temperature to 70 ℃, keeping the temperature at 70 ℃, stirring at a speed of 200rmp, stopping reaction after reacting for 150min, transferring slurry to a prepared plastic barrel, filtering and fully washing the phosphorite, draining, and placing the phosphorite into a prepared plastic utensil containing 60kg of phosphorite. And sampling and detecting the filtrate, and detecting the full index after sampling and drying the phosphorite.
7. Data collection:
and (4) conclusion:
the technological parameters of the phosphorite pretreatment impurity removal are completely feasible. Namely the concentration of the reaction acid P2O5 is 20.4 percent; SO3: 2.36; the liquid-solid ratio is 1.5: 1; reaction time: 150 min; the reaction temperature is 40-75 ℃; the stirring strength is 200-500 rmp. The removal rate of main impurities reaches 83 percent, and the yield of phosphorus reaches 98.5 percent.
Experiment two
1. The name of the experiment: experiment for preparing white gypsum by phosphorite reaction in production system of phosphoric acid decomposition
2. Experimental equipment and model: the heating electric furnace, the 316L reactor with frequency-variable speed-regulating stirring (self-made) and the glass beaker. An electric heating oven, a vacuum pump, a Buchner funnel, filter paper and pH test paper.
3. Experiment raw materials: phosphoric acid, ground phosphate rock and sulfuric acid in production system
4. The experimental principle is as follows: wet phosphoric acid decomposing phosphate rock by a dihydrate method is adopted to leach calcium oxide, sulfuric acid is added for reaction after black impurities are separated, and pure white dihydrate gypsum is obtained.
5. Purpose of the experiment: white gypsum is prepared by adopting phosphorite phosphoric acid reaction of the existing production system, and the yield of the white gypsum is obtained.
6. The experimental steps are as follows:
1) checking the self-made reaction system, and whether stirring is flexible or not and whether connection is stable or not. After all the reaction solution is normal, the position is adjusted (the paddle is 7 cm away from the bottom of the reaction tank), and 14kg of phosphoric acid of a production system is added.
2) And after the system is normal, the power supply is switched on, whether the power supply is normally electrified or not is switched on, the electric furnace is heated, and the electric furnace is detected by the test pencil, so that the system is ensured to be electricity-tight.
3) After normal, starting stirring, turning on an electric furnace switch system, raising the temperature to 50 ℃, turning down the electric furnace gear, and slowly adding 1.2kg of phosphorite (dry mineral powder) of the production system. And adjusting the stirring speed to 400-500 rpm, slowly adding the phosphorite into the reaction tank, adjusting the gear of the electric furnace, and ensuring the temperature of the reaction tank to be 50 ℃.
4) And stopping the reaction after reacting for 3.5h, adding a settling agent into the slurry, stirring for clarification, and separating out clear liquid by siphoning.
5) Adding the calcium oxide leaching solution into a reaction tank, heating to 60 ℃, slowly adding excessive sulfuric acid, reacting for 30min, and filtering and separating. Filtering and washing the phosphogypsum, and respectively containing the filtrate and washing water in different containers for later use. 7. Collecting index data:
the experimental results are as follows:
settling clear liquid with settling agent, layering after 20min, making the clear liquid contain white precipitate, and floating a little black oily matter on the surface. The volume ratio of the black slag in the measuring cylinder is 20 percent, and the whiteness of the gypsum is 83 percent.
The sulfuric acid is added into the reaction kettle to react with liquid phase calcium oxide to generate white gypsum, and the white gypsum is filtered, washed and dried for 431 g, and the yield of the white gypsum is 27 percent.
The content of liquid phase calcium oxide in the experiment is low, the yield of the white gypsum is low, namely the white gypsum obtained by one ton of ore is 270kg, and the industrial production cannot be realized.
In view of the above situation, the ore is subjected to impurity removal treatment according to the first experiment, and the treated phosphorite is prepared into phosphoric acid to be carried out on the third experiment.
Experiment three
1. The name of the experiment: the experiment for preparing the white gypsum by the phosphoric acid decomposition, pretreatment and impurity removal reaction in the pretreatment and impurity removal production.
2. Experimental equipment and model: the heating electric furnace, the 316L reactor with frequency-variable speed-regulating stirring (self-made) and the glass beaker. An electric heating oven, a vacuum pump, a Buchner funnel, filter paper and pH test paper.
3. Experiment raw materials: water, powdered rock phosphate and sulfuric acid
4. The experimental principle is as follows: wet phosphoric acid decomposing phosphate rock by a dihydrate method is adopted to leach calcium oxide, sulfuric acid is added for reaction after black impurities are separated, and pure white dihydrate gypsum is obtained.
5. Purpose of the experiment: the calcium oxide leaching solution is prepared from the phosphorite after pretreatment and impurity removal and the phosphoric acid produced by the phosphorite corresponding to the impurity removal to obtain the white gypsum.
6. The experimental steps are as follows:
1) checking the self-made reaction system, and whether stirring is flexible or not and whether connection is stable or not. After all the materials are normal, the position is adjusted (the paddle is 3 cm away from the bottom of the reaction tank), and 12kg of self-made roguing phosphoric acid is added (wherein 8kg of filtrate and 4kg of washing water are provided, and the indexes are shown in the following table).
2) And after the system is normal, the power supply is switched on, whether the power supply is normally electrified or not is switched on, the electric furnace is heated, and the electric furnace is detected by the test pencil, so that the system is ensured to be electricity-tight.
3) After the normal operation, the stirring is started, the electric furnace switch is turned on, the system is heated to 50 ℃, the electric furnace gear is reduced, and 1.0kg of pre-treated rogue phosphate ore (dry mineral powder, the index is shown in the following table) is slowly added. And adjusting the stirring speed to 400-500 rpm, slowly adding the phosphorite into the reaction tank, adjusting the gear of the electric furnace, and ensuring the temperature of the reaction tank to be 50 ℃.
4) After the total reaction time was 3.0 hours, the reaction was stopped, and the slurry was filtered under vacuum and the clear solution was separated. And (5) washing black residues. The filtrate (i.e., the calcium oxide leachate) and wash water are collected for use.
5) Sampling and measuring the calcium oxide leaching solution, heating to 50 ℃, slowly adding excessive sulfuric acid for reaction for 30min, and filtering and separating. Filtering, washing the white phosphogypsum, and respectively filling the filtrate and the washing water into different containers for later use.
7. Data collection:
experimental conditions:
1. the clear liquid is filtered in vacuum, the clear liquid is transparent, and no crystal is separated out when the temperature is reduced to 25 ℃. The whiteness of the gypsum is 93.9 percent.
2, adding excessive sulfuric acid to react with liquid-phase calcium oxide to generate white gypsum, filtering, washing and drying 786 g, wherein the yield of the white gypsum is 57%.
The content of liquid phase calcium oxide in the experiment is two times of that in the experiment II, the yield of the white gypsum is greatly improved by more than two times, namely, the amount of the white gypsum obtained by one ton of ore is 786 kg.
Experiment four (cycle of 6 times leaching calcium oxide to make white gypsum in the production of phosphoric acid from purified phosphorite)
1. The name of the experiment: and (3) performing impurity-removed ore circulating phosphoric acid and impurity-removed ore reaction to prepare white gypsum experiment.
2. Experimental equipment and model: the heating electric furnace, the 316L reactor with frequency-variable speed-regulating stirring (self-made) and the glass beaker. An electric heating oven, a vacuum pump, a Buchner funnel, filter paper and pH test paper.
3. Experiment raw materials: circulating phosphoric acid, ground phosphate rock and sulfuric acid
4. The experimental principle is as follows: the method comprises the steps of carrying out impurity-removing ore circulating phosphoric acid decomposition pretreatment on impurity-removing phosphorite to leach calcium oxide, separating black impurities, and then adding sulfuric acid to react to obtain pure white dihydrate gypsum.
5. Purpose of the experiment: and (3) preparing calcium oxide leaching solution by adopting phosphorite subjected to impurity removal treatment and phosphoric acid for producing white gypsum by correspondingly removing the impurities from the phosphorite to obtain white gypsum, and verifying the yield of the white gypsum.
6. The experimental steps are as follows:
1) checking the self-made reaction system, and whether stirring is flexible or not and whether connection is stable or not. After all the materials are normal, the position is adjusted (the paddle is 3 cm away from the bottom of the reaction tank), and 12.8kg of self-made circulating phosphoric acid (8.5 kg of filtrate and 4.3kg of washing water, the indexes are shown in the following table) is added.
2) And after the system is normal, the power supply is switched on, whether the power supply is normally electrified or not is switched on, the electric furnace is heated, and the electric furnace is detected by the test pencil, so that the system is ensured to be electricity-tight.
3) After the normal operation, the stirring is started, the electric furnace switch is turned on, the system is heated to 50 ℃, the electric furnace gear is reduced, and 1.067kg of the magnesium-removed phosphate ore (dry ore powder, the index is shown in the following table) is slowly added. And adjusting the stirring speed to 400-500 rpm, slowly adding the phosphorite into the reaction tank, adjusting the gear of the electric furnace, and ensuring the temperature of the reaction tank to be 50 ℃.
4) After the total reaction time was 3.0 hours, the reaction was stopped, and the slurry was filtered under vacuum and the clear solution was separated. And (5) washing black residues. The filtrate (i.e., the calcium oxide leachate) and wash water are collected for use.
5) Sampling and measuring the calcium oxide leaching solution, heating to 50 ℃, slowly adding excessive sulfuric acid for reaction for 30min, and filtering and separating. Filtering, washing the white phosphogypsum, and respectively filling the filtrate and the washing water into different containers for later use.
7. Data collection:
the experimental results are as follows:
in the experiment, white gypsum is prepared by circularly decomposing phosphorite to leach calcium oxide through circularly reacting white gypsum prepared filtrate and primary washing water. And (3) circulating the system for the sixth time, adding 1.067kg of dry ore according to the acid ore proportion of about 12, reacting for 2-3 h, adding 10-20 ppm of settling agent, settling, siphoning, and filtering and washing thick slurry (filtrate is added into clear liquid). Adding sulfuric acid (the amount of sulfuric acid is added according to the amount of substances such as calcium oxide in the ore) into the clear liquid, controlling the temperature to be 50 ℃ for crystallization reaction for 1-2 h, filtering and washing to obtain 815g of dried white gypsum, wherein the yield of the white gypsum is 58%, and the yield of the white gypsum is still stable after circulation.
Comparing experiment two with experiment three and four: in the second experiment, the impurity removal pretreatment of the phosphorite is not carried out, while in the third and fourth experiments, the impurity removal pretreatment of the phosphorite is adopted, and the white gypsum obtained by the third experiment is 2 times of that obtained by devices with the same specification and different processes, so that the technology is the key for realizing industrial production. The core technology is as follows:
1. the concentration of the decomposed acid is reduced, and the problem that the black slag is difficult to separate is solved;
2. the reaction energy consumption can be effectively reduced by adopting a dihydrate method;
3. the saturated concentration of calcium ions in acid liquor is improved, so that the acidolysis equipment is not excessively huge when the decomposition of ores is ensured, the industrial value is not realized, and the yield of the phosphorite white gypsum is effectively improved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (6)
1. A method for producing high-purity white phosphogypsum from high-impurity-content phosphorite is characterized by comprising the following steps: it includes but is not limited to the following production processes:
process 1: pre-treating and removing impurities from phosphorite, namely adding high-impurity phosphorite (the phosphorite index is P2O5: 18-32%) into part of process hot water of a production system to prepare ore pulp with the temperature of 40-80 ℃ and the solid content of 20-70%, adding a phosphorite pre-treating agent, ensuring the pH value to be 2-5, and reacting for 1-5h to obtain low-impurity high-activity phosphorite (P2O5: 18-32%);
and (2) a process: acidolysis separation, namely reacting the low-impurity high-activity phosphorite obtained in the process 1 with phosphoric acid at the temperature of 50-85 ℃ for 1-5h, settling, filtering and separating black residues in the slurry to obtain a clear phosphoric acid solution containing soluble calcium phosphate salt, wherein the acid concentration is 20-32%;
and 3, process: reacting and crystallizing the clear liquid and separating white gypsum, adding the soluble calcium phosphate salt solution obtained in the process 2 into clean industrial sulfuric acid, controlling the temperature to be 50-90 ℃, reacting for 1-4h, crystallizing to generate calcium sulfate dihydrate, settling and concentrating phosphoric acid slurry containing the calcium sulfate dihydrate, returning the clear liquid to an acid hydrolysis tank in the process 2 to react with the phosphorite from the impurity removal in the process 1, wherein part of filter washing liquid returns to the acid hydrolysis tank in the process 2, part of filter washing liquid is used as low-impurity finished phosphoric acid to enter a finished product phosphoric acid storage tank, and high-purity white phosphogypsum (the content of the calcium sulfate dihydrate is more than 99 percent) is used as a subsequent gypsum deep processing raw material;
and 4, process: and (3) black slag treatment, wherein the black slag separated in the process 2 contains 5-35% of incompletely separated phosphorite, part of industrial sulfuric acid is added, the temperature is controlled at 50-90 ℃, the reaction is carried out for 1-4 hours, the ore is continuously decomposed, the calcium sulfate crystallization, filtration, washing and separation are completed, and low-impurity finished phosphoric acid is put into a finished product storage tank.
2. The method for producing high-purity white phosphogypsum from phosphorite with high impurity content according to claim 1, is characterized in that: the ratio of acid hydrolysis phosphoric acid to phosphorite in the process 2 is 8-16 times.
3. The method for producing high-purity white phosphogypsum from phosphorite with high impurity content according to claim 1, is characterized in that: the control of the amount of the reaction sulfuric acid in the process 3 ensures that the concentration of the liquid phase SO3 is controlled to be 8-25 g/l.
4. The method for producing high-purity white phosphogypsum from phosphorite with high impurity content according to claim 1, is characterized in that: in the process 3, in order to ensure the white gypsum crystallization, the returned materials in the thick slurry provide the crystallization with the supersaturation degree of calcium ions and sulfuric acid in the crystal seeds and the diluted clear liquid, thereby effectively ensuring that the white gypsum crystallization is thick and regular and reducing the intercrystalline phosphorus.
5. The method for producing high-purity white phosphogypsum from phosphorite with high impurity content according to claim 1, is characterized in that: the purpose of adding part of sulfuric acid in the process 4 is to further decompose the phosphorus ores which are not completely decomposed in the process 2 and complete the crystallization of calcium sulfate, and the adding amount of the sulfuric acid is controlled by 25g/l of liquid-phase SO 3.
6. The method for producing high-purity white phosphogypsum from phosphorite with high impurity content according to claim 1, is characterized in that: the liquid-solid separation in the process 1, the process 2 and the process 3 adopts vacuum filtration, wherein the process 1 adopts primary washing, and washing liquor returns to a system for pulping; no washing in the process 2; 3 times of countercurrent hot water washing is adopted in the process 3.
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