CA1328344C - Reducing anti-foam consumption in phosphoric acid production - Google Patents
Reducing anti-foam consumption in phosphoric acid productionInfo
- Publication number
- CA1328344C CA1328344C CA 511836 CA511836A CA1328344C CA 1328344 C CA1328344 C CA 1328344C CA 511836 CA511836 CA 511836 CA 511836 A CA511836 A CA 511836A CA 1328344 C CA1328344 C CA 1328344C
- Authority
- CA
- Canada
- Prior art keywords
- phosphoric acid
- molecular weight
- polymer
- flocculant
- high molecular
- 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.)
- Expired - Fee Related
Links
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 title claims abstract description 38
- 229910000147 aluminium phosphate Inorganic materials 0.000 title claims abstract description 19
- 238000004519 manufacturing process Methods 0.000 title description 6
- 239000002518 antifoaming agent Substances 0.000 title description 3
- 229920000642 polymer Polymers 0.000 claims abstract description 30
- 238000005187 foaming Methods 0.000 claims abstract description 11
- 229920001577 copolymer Polymers 0.000 claims abstract description 7
- 239000012535 impurity Substances 0.000 claims abstract description 6
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims abstract description 5
- 125000000129 anionic group Chemical group 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 14
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 6
- 239000013530 defoamer Substances 0.000 claims description 3
- 230000029087 digestion Effects 0.000 claims description 3
- 239000002367 phosphate rock Substances 0.000 claims description 3
- 229920003169 water-soluble polymer Polymers 0.000 claims description 3
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims description 2
- 229920002401 polyacrylamide Polymers 0.000 claims description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims 3
- 229920001519 homopolymer Polymers 0.000 abstract description 4
- 229920006322 acrylamide copolymer Polymers 0.000 abstract description 2
- 239000006260 foam Substances 0.000 abstract description 2
- RNIHAPSVIGPAFF-UHFFFAOYSA-N Acrylamide-acrylic acid resin Chemical group NC(=O)C=C.OC(=O)C=C RNIHAPSVIGPAFF-UHFFFAOYSA-N 0.000 abstract 1
- 230000003311 flocculating effect Effects 0.000 abstract 1
- 239000002253 acid Substances 0.000 description 5
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 4
- 239000011435 rock Substances 0.000 description 4
- 229920006318 anionic polymer Polymers 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- PQUXFUBNSYCQAL-UHFFFAOYSA-N 1-(2,3-difluorophenyl)ethanone Chemical compound CC(=O)C1=CC=CC(F)=C1F PQUXFUBNSYCQAL-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 150000003839 salts Chemical group 0.000 description 2
- 229940047670 sodium acrylate Drugs 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- MVYVKSBVZFBBPL-UHFFFAOYSA-N 2-(prop-2-enoylamino)propane-1-sulfonic acid Chemical compound OS(=O)(=O)CC(C)NC(=O)C=C MVYVKSBVZFBBPL-UHFFFAOYSA-N 0.000 description 1
- IRLPACMLTUPBCL-KQYNXXCUSA-N 5'-adenylyl sulfate Chemical compound C1=NC=2C(N)=NC=NC=2N1[C@@H]1O[C@H](COP(O)(=O)OS(O)(=O)=O)[C@@H](O)[C@H]1O IRLPACMLTUPBCL-KQYNXXCUSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 239000005696 Diammonium phosphate Substances 0.000 description 1
- 239000004908 Emulsion polymer Substances 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 description 1
- 229910000388 diammonium phosphate Inorganic materials 0.000 description 1
- 235000019838 diammonium phosphate Nutrition 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 150000004665 fatty acids Chemical class 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 239000008394 flocculating agent Substances 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 238000012688 inverse emulsion polymerization Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 235000021313 oleic acid Nutrition 0.000 description 1
- 150000002889 oleic acids Chemical class 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 125000001273 sulfonato group Chemical group [O-]S(*)(=O)=O 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 239000003784 tall oil Substances 0.000 description 1
Landscapes
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
ABSTRACT OF THE INVENTION
Crude phosphoric acid which contains impurities tends to foam. It is customary to reduce foaming by using antifoams.
The foaming of such phosphoric acid solutions is eliminated or reduced by coalescing the suspended impurities by flocculating from the phosphoric acid solutions using a high molecular weight water-soluble flocculant polymer, which is an anionic or nonionic homo or copolymer of high molecular weight. A preferred polymer is an acrylic acid-acrylamide copolymer containing from 10% to 60% acrylic acid units with a molecular weight of at least 1,000,000.
Crude phosphoric acid which contains impurities tends to foam. It is customary to reduce foaming by using antifoams.
The foaming of such phosphoric acid solutions is eliminated or reduced by coalescing the suspended impurities by flocculating from the phosphoric acid solutions using a high molecular weight water-soluble flocculant polymer, which is an anionic or nonionic homo or copolymer of high molecular weight. A preferred polymer is an acrylic acid-acrylamide copolymer containing from 10% to 60% acrylic acid units with a molecular weight of at least 1,000,000.
Description
6530,407 1 328 3a4 INTRODUCTION
Production of phosphoric acid by the wet process involves the steps of (1) dissolving phosphate rock in sulfuric acid, (2) holding the acidulate slurry until the calcium sulfate crystals grow to adequate size, (3) separating the acid and calcium sulfate by filtration, and (4) concentrating the acid to the desired level. The reaction for the process used most extensively is as follows:
Cal0F2(po4)6+H2so4+2o 2 6H3PO4+10CaSO4.2H20+2HF
The reactor system varies widely between plants; a most recent type consists of a single large tank with associated cooling, fume removal, and recycling facilities.
Average retention time in the reactor system is about eight hours. In all systems, recirculation of slurry is required for temperature control. Also, it reduces the adverse effects on the process of surges and of local high concentrations of rock and acid. The recycled slurry also gives the control of super-saturation necessary for good growth of gypsum crystals.
Foaming in the reactor often is a problem, especially when the rock has a relatively high content of organic matter or carbonate. Various antifoam agents are used to control foaming;
they include tall oil fatty acids, oleic acids, and silicones.
Rates vary from 1.5 - 15 pounds per ton between plants depending on rock chemistry, reactor free-board, and agitator design.
Nalco Case 4000 The foaming of these crude phosphoric acid solutions not only impedes the basic rock digestion process but tends to reduce the efficiency of subsequent steps in the manufacturing process such as, for example, the use of phosphoric acid in the manufacture of diammonium phosphate. By eliminating or reducing foaming, it is possible to improve the efficiency of the pro-duction of crude phosphoric acid by the wet process as well as to improve its subsequent utilization in the production of other phosphorous-containing materials.
THE INVENTION
A method of reducing the foaming tendencies and attendant defoamer consumption of crude phosphoric acid produced by the digestion of phosphate rock in sulfuric acid which comprises treating the crude phosphoric acid in the reactor with up to 0.3 pounds per ton of active flocculant, based on the weight of P205 in the reactor, of a high molecular weight, water-soluble, flocculant polymer from the group consisting of anionic and nonionic flocculant polymers, whereby the suspended impurities contained in the crude phosphoric acid are coalesced, thus effectuating a reduction in the foaming tendencies of such crude phosphoric acid. The coalesced or settled solids are sub-sequently removed by filtration.
THE HIGH MOLECULAR WEIGHT WATER-SOLUBLE
FLOCCULANT POLYMERS
These materials are well known. These polymers, to be effective as flocculants, should be of a high molecular weight .. --2--.. :, .. - ~ . -` 1 328344 varlety. In most lnstances, the molecular welght of the polymers will be at least 500,000 and, preferably, at least 1,000,000.
Molecular welghts may range as hlgh as 25,000,000 or greater although typlcal commerclal products have molecular welghts wlthln the range of 1,000,000 - 15,000,000. The polymers may be either anlonlc or nonlonlc homo or copolymers.
THE ANIONIC POLYMERS
The polymers are anlonlc with the anlonlc portlon of the polymer belng derived from such well-known monomers as acrylic acld, methacryllc acld, malelc acld, ltaconlc acld, and the llke.
A preferred anlonlc monomer used to produce the polymers sultable for the practlce of the lnventlon ls acryllc acld.
In a preferred mode of the lnventlon, the copolymers ~
should contaln at least 10% by welght acryllc acld. Most pre- -ferably, the polymers are copolymers of acryllc acld wlth acryl-amlde whereln the acryllc acld portlon of the polymer ranges between 10-60~ by welght, partlcularly about 25~..
In referrlng to the anionlc carboxyllc acid polymers, lt ls understood that lncluded ln such materlals are the free acld form of the polymers as well as thelr alkall metal or other water-soluble salt forms such as the sodlum salt of such carboxyllc acld contalnlng polymers. --In addltlon to uslng acryllc acld polymers of the type descrlbed above, lt ls to be understood that other anlonlc water-soluble polymers may be used. Exemplary are hlgh molecular welght copolymers of malelc acld or malelc anhydrlde whlch, under conditions of use, would hydrolyze to the free acid form.
Another type of anionic polymers are the high molecular weight polystyrene sulphonates although these materials are not always effective at low dosages.
A very useful group of high molecular weight anionic polymers are the so-called "homo and copolymers of 2-acrylamidopropane sulfonic acid (AMPS~." These polymers are described in U.S. Pat. 3,692,673.
THE NONIONIC POLYMERS
High molecular weight flocculant nonionic polymers also find use in the practice of the invention. Particularly useful are the homopolymers of acrylamide.
The anionic and nonionic polymers are conveniently prepared using the so-called "Inverse Emulsion Polymerization"
technique described in Vanderhoff, U.S. 3,284,393.
The inverse emulsion polymers prepared as described in the Vanderhoff patent, when used in conjuction with water-soluble surfactants and other means equivalent thereto, may, by using the teachings of Anderson/Frisque, U.S. Re. 28,474 and 28,576, be readily converted into dilute aqueous solutions of such polymers which provide a convenient form for adding these polymers to the wet process crude phosphoric acid solutions to coalesce therefrom by flocculation the suspended impurities contained therein.
DOSAGE
The polymers may be used to effectively coalesce the suspended inorganic materials in amounts ranging from as little :: . . . , , , ., . , . . , : .: - .
as about 1 ppm up to as much as about 150 ppm by weight of active polymer. Usually a few ppm give good results. These dosages are by weight based on the P205 present in the system treated. These dosages correspond to a range of from about 0.002 Ibs/ton to about 0.3 lbs/ton, again based on the weight of P205 present.
ILLUSTRATION OF THE INVENTION
In a commercial wet process phosphoric acid fertilizer plant, an acrylamide homopolymer as well as a sodium acrylate/acrylamide copolymer containing about 35% by weight sodium acrylate, both with a molecular weight greater than 1,000,000, were added independently at dosages of about 0.1 active polymer pounds per ton of P205 to the phosphoric acid "attack" tank(s). It resulted in the coalescing of the fine, suspended impurities, reducing their effective surface area;
hence, their ability to stabilize foam. As a result of this, it was possible to substantially reduce the amount of antifoam/defoamer that was previously required to control foaming at this point in the process. ~ ;
Production of phosphoric acid by the wet process involves the steps of (1) dissolving phosphate rock in sulfuric acid, (2) holding the acidulate slurry until the calcium sulfate crystals grow to adequate size, (3) separating the acid and calcium sulfate by filtration, and (4) concentrating the acid to the desired level. The reaction for the process used most extensively is as follows:
Cal0F2(po4)6+H2so4+2o 2 6H3PO4+10CaSO4.2H20+2HF
The reactor system varies widely between plants; a most recent type consists of a single large tank with associated cooling, fume removal, and recycling facilities.
Average retention time in the reactor system is about eight hours. In all systems, recirculation of slurry is required for temperature control. Also, it reduces the adverse effects on the process of surges and of local high concentrations of rock and acid. The recycled slurry also gives the control of super-saturation necessary for good growth of gypsum crystals.
Foaming in the reactor often is a problem, especially when the rock has a relatively high content of organic matter or carbonate. Various antifoam agents are used to control foaming;
they include tall oil fatty acids, oleic acids, and silicones.
Rates vary from 1.5 - 15 pounds per ton between plants depending on rock chemistry, reactor free-board, and agitator design.
Nalco Case 4000 The foaming of these crude phosphoric acid solutions not only impedes the basic rock digestion process but tends to reduce the efficiency of subsequent steps in the manufacturing process such as, for example, the use of phosphoric acid in the manufacture of diammonium phosphate. By eliminating or reducing foaming, it is possible to improve the efficiency of the pro-duction of crude phosphoric acid by the wet process as well as to improve its subsequent utilization in the production of other phosphorous-containing materials.
THE INVENTION
A method of reducing the foaming tendencies and attendant defoamer consumption of crude phosphoric acid produced by the digestion of phosphate rock in sulfuric acid which comprises treating the crude phosphoric acid in the reactor with up to 0.3 pounds per ton of active flocculant, based on the weight of P205 in the reactor, of a high molecular weight, water-soluble, flocculant polymer from the group consisting of anionic and nonionic flocculant polymers, whereby the suspended impurities contained in the crude phosphoric acid are coalesced, thus effectuating a reduction in the foaming tendencies of such crude phosphoric acid. The coalesced or settled solids are sub-sequently removed by filtration.
THE HIGH MOLECULAR WEIGHT WATER-SOLUBLE
FLOCCULANT POLYMERS
These materials are well known. These polymers, to be effective as flocculants, should be of a high molecular weight .. --2--.. :, .. - ~ . -` 1 328344 varlety. In most lnstances, the molecular welght of the polymers will be at least 500,000 and, preferably, at least 1,000,000.
Molecular welghts may range as hlgh as 25,000,000 or greater although typlcal commerclal products have molecular welghts wlthln the range of 1,000,000 - 15,000,000. The polymers may be either anlonlc or nonlonlc homo or copolymers.
THE ANIONIC POLYMERS
The polymers are anlonlc with the anlonlc portlon of the polymer belng derived from such well-known monomers as acrylic acld, methacryllc acld, malelc acld, ltaconlc acld, and the llke.
A preferred anlonlc monomer used to produce the polymers sultable for the practlce of the lnventlon ls acryllc acld.
In a preferred mode of the lnventlon, the copolymers ~
should contaln at least 10% by welght acryllc acld. Most pre- -ferably, the polymers are copolymers of acryllc acld wlth acryl-amlde whereln the acryllc acld portlon of the polymer ranges between 10-60~ by welght, partlcularly about 25~..
In referrlng to the anionlc carboxyllc acid polymers, lt ls understood that lncluded ln such materlals are the free acld form of the polymers as well as thelr alkall metal or other water-soluble salt forms such as the sodlum salt of such carboxyllc acld contalnlng polymers. --In addltlon to uslng acryllc acld polymers of the type descrlbed above, lt ls to be understood that other anlonlc water-soluble polymers may be used. Exemplary are hlgh molecular welght copolymers of malelc acld or malelc anhydrlde whlch, under conditions of use, would hydrolyze to the free acid form.
Another type of anionic polymers are the high molecular weight polystyrene sulphonates although these materials are not always effective at low dosages.
A very useful group of high molecular weight anionic polymers are the so-called "homo and copolymers of 2-acrylamidopropane sulfonic acid (AMPS~." These polymers are described in U.S. Pat. 3,692,673.
THE NONIONIC POLYMERS
High molecular weight flocculant nonionic polymers also find use in the practice of the invention. Particularly useful are the homopolymers of acrylamide.
The anionic and nonionic polymers are conveniently prepared using the so-called "Inverse Emulsion Polymerization"
technique described in Vanderhoff, U.S. 3,284,393.
The inverse emulsion polymers prepared as described in the Vanderhoff patent, when used in conjuction with water-soluble surfactants and other means equivalent thereto, may, by using the teachings of Anderson/Frisque, U.S. Re. 28,474 and 28,576, be readily converted into dilute aqueous solutions of such polymers which provide a convenient form for adding these polymers to the wet process crude phosphoric acid solutions to coalesce therefrom by flocculation the suspended impurities contained therein.
DOSAGE
The polymers may be used to effectively coalesce the suspended inorganic materials in amounts ranging from as little :: . . . , , , ., . , . . , : .: - .
as about 1 ppm up to as much as about 150 ppm by weight of active polymer. Usually a few ppm give good results. These dosages are by weight based on the P205 present in the system treated. These dosages correspond to a range of from about 0.002 Ibs/ton to about 0.3 lbs/ton, again based on the weight of P205 present.
ILLUSTRATION OF THE INVENTION
In a commercial wet process phosphoric acid fertilizer plant, an acrylamide homopolymer as well as a sodium acrylate/acrylamide copolymer containing about 35% by weight sodium acrylate, both with a molecular weight greater than 1,000,000, were added independently at dosages of about 0.1 active polymer pounds per ton of P205 to the phosphoric acid "attack" tank(s). It resulted in the coalescing of the fine, suspended impurities, reducing their effective surface area;
hence, their ability to stabilize foam. As a result of this, it was possible to substantially reduce the amount of antifoam/defoamer that was previously required to control foaming at this point in the process. ~ ;
Claims (4)
1. A method of reducing the foaming tendencies and attendant defoamer consumption of crude phosphoric acid produced by the digestion of phosphate rock in sulfuric acid which comprises treating the crude phosphoric acid in the reactor with up to 0.3 pounds per ton of active flocculant based on the weight of P2O5 in the reactor of a high molecular weight, water-soluble, flocculant polymer from the group consisting of anionic and non-ionic flocculant polymers, whereby the suspended impurities contained in the crude phosphoric acid are coalesced, thus effectuating a reduction in the foaming tendencies of such crude phosphoric acid.
2. The method of Claim 1 wherein the high molecular weight water-soluble flocculant polymer is a polymer which contains at least 10% by weight of acrylic acid.
3. The method of Claim 2 where the high molecular weight flocculant water-soluble polymer is a copolymer of acrylic acid and acrylamide with the acrylic acid content thereof being about 25%.
4. The method of Claim 1 where the high molecular weight flocculant water-soluble polymer is an acrylamide polymer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US76216185A | 1985-07-19 | 1985-07-19 | |
| US762,161 | 1985-07-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1328344C true CA1328344C (en) | 1994-04-12 |
Family
ID=25064284
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 511836 Expired - Fee Related CA1328344C (en) | 1985-07-19 | 1986-06-18 | Reducing anti-foam consumption in phosphoric acid production |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1328344C (en) |
-
1986
- 1986-06-18 CA CA 511836 patent/CA1328344C/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |