WO1995035257A1 - Process for the purification of phosphoric acid - Google Patents
Process for the purification of phosphoric acid Download PDFInfo
- Publication number
- WO1995035257A1 WO1995035257A1 PCT/FI1995/000354 FI9500354W WO9535257A1 WO 1995035257 A1 WO1995035257 A1 WO 1995035257A1 FI 9500354 W FI9500354 W FI 9500354W WO 9535257 A1 WO9535257 A1 WO 9535257A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- acid
- phosphoric acid
- process according
- impurities
- concentrated
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/18—Phosphoric acid
- C01B25/234—Purification; Stabilisation; Concentration
- C01B25/2343—Concentration concomitant with purification, e.g. elimination of fluorine
Definitions
- This invention relates to a process for removing impurities from phosphoric acid prepared by the wet process.
- Phosphoric acid can be prepared by the wet process by reacting a mineral acid, most commonly sulfuric acid, with a calcium phosphate concentrate, whereupon a dilute phosphoric acid, containing approx. 30 % P 2 0 5 , and a calcium sulfate precipitate are formed- After filtration, the acid contains many kinds of anionic impurities, such as sulfate and fluorine compounds, and cationic impurities, the most important of which are iron, aluminum, magnesium and calcium, and organic impurities.
- anionic impurities such as sulfate and fluorine compounds
- cationic impurities the most important of which are iron, aluminum, magnesium and calcium, and organic impurities.
- the quantity and type of the impurities depend above all on the raw phosphate used as the raw material.
- the dilute acid is concentrated by evaporation to a concentra ⁇ tion of 50-70 % P 2 0 5 , whereby volatile impurities, such as fluorine compounds, are mostly separated together with the evaporating water vapor, but the concentrations of other im ⁇ purities are increased.
- US patent specification 4 248 843 discloses a process for the purification of phosphoric acid wherein the magnesium ions present as an impurity are pre ⁇ cipitated as a pyrophosphate. The process has a disadvantage in a high viscosity at higher concentrations, complicating the crystallization of the pyrophosphate and the separation of the crystals.
- the crystallizing magnesium pyrophosphate is not biologically active, and therefore it as such has no utility purpose; the compound requires hydrolysis in order to be usable as a fertilizer or in animal feeds.
- An object of the present invention is indeed to produce very pure phosphoric acid at economical cost.
- a further object of the invention is to cause the metal ions present as impurities to precipitate as compounds which are usable in industry.
- the impurities present in phosphoric acid can be precipitated as compounds which crystallize within even lower concentration ranges of phosphoric acid than in state-of-the-art processes. It has additionally been observed that, if the initial acid used in the process does not contain impurities which are re ⁇ lodged as hazardous, such as cadmium, the process offers an additional advantage. Namely, the waste compound formed as an impurity can be utilized as a useful raw material in industry. Thus, the impurity compounds separated by the present process will not become environmental hazards.
- a process has been pro ⁇ vided for the removal of bivalent metal ion impurities from a wet-process phosphoric acid.
- a phosphoric acid of a fertilizer grade or filter acid grade is concentrated by heating to a P 2 0 5 concentration of 58-68 %.
- the bivalent metal ions which are present as impurities are caused to crystallize as a compound M 2+ (H 2 P ⁇ 4 ) 2 ' -H 3 P ⁇ 4 , wherein the metal ions are present as M 2+ , and the number n of associated phosphoric acid molecules is 2- 5.
- the initial acid used may be a we -process phosphoric acid the P 2 0 5 content of which may be approx. 20-60 %, typically 30 % P 2 C> 5 or 50 % P 2 0 5 .
- the sulfate content of such a phosphoric acid typically varies within 2-4 % S0 4 .
- Wet-process phosphoric acid contains a variety of anionic, cationic and organic impurities, the concentrations of which vary depending on the origin of the phosphate concentrate from which the acid was prepared.
- the process according to the invention it is possible to lower the cationic metal ion concentrations in phosphoric acid almost completely, or at least to an acceptable level.
- concentrations of, for example, the following metal ions have been lowered: Mg, Fe, Ca, Mn, Zn, Cd, Co, Cu, Pb, and Ni.
- the formed crystalline compound is neither magnesium pyrophosphate nor anhydrous monomagnesium phosphate.
- the crystals are washed with ethanol, some of the phosphoric acid dissolves, and Mg(H 2 P0 4 ) 2 and Fe(H 2 P0 4 ) 2 -2H 2 0 were identified as the compounds in an X-ray diffraction spectrum.
- the crystallized metal compound crystals can be separated from the phosphoric acid by methods known per se. such as centrifugation, pressure filtration, vacuum filtration, or sedimentation.
- the removal of the sulfate is not indispensable.
- the sulfate can, for example, be removed directly from the phos ⁇ phoric acid by precipitation as gypsum by means of a calcium salt. It has, however, been observed that a lowering of the sulfate concentration enables lower temperatures to be used in the acid concentration step than without a lowering of the sulfate concentration.
- the process also enables the waste compound crystallized out from phosphoric acid to be used as a raw material in industry.
- Magnesium phosphate crystallized out from a phosphoric acid prepared from a crude phosphate which has a low heavy metal content can be used, for example, in animal feeds and as a raw material for the fertilizer industry.
- concentrations of detrimental ions (F, As, Al and Cr) in the crystals are reduced and the concentrations of useful trace elements (Fe, Mn, Zn and Cu) increase in proportion to the concentrations of the feed acid.
- a fertilizer-grade phosphoric acid (Siilinjarvi) was con ⁇ centrated (150 °C, 65 mm Hg) to 67.5 % P 2 0 5 .
- the feed acid contained 2.76 % S0 4 .
- seed was added at a rate of 2 % of the mass of the concentrated acid.
- the crystals were separated in a centrifuge, and the compound was ascertained by means of an X- ray diffraction spectrum.
- the quality of the feed and product acids are presented in Table 1.
- a fertilizer-grade phosphoric acid (Siilinjarvi) in which the sulfate level had been lowered (0.8 % S0 4 ) was concentrated to 64.2 % P 2 0 5 . Seeds (1 %) were added at 95 °C, and the acid was cooled in five hours to 50 °C.
- the feed acid contained 1.5 % Mg and the product acid contained 0.6 % Mg.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Fertilizers (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
Abstract
Description
Claims
Priority Applications (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU27401/95A AU2740195A (en) | 1994-06-20 | 1995-06-19 | Process for the purification of phosphoric acid |
SK1616-96A SK161696A3 (en) | 1994-06-20 | 1995-06-19 | Process for the purification of phosphoric acid |
EP95922550A EP0768985A1 (en) | 1994-06-20 | 1995-06-19 | Process for the purification of phosphoric acid |
PL95318219A PL318219A1 (en) | 1994-06-20 | 1995-06-19 | Phosphoric acid purifying method |
RO96-02409A RO114886B1 (en) | 1994-06-20 | 1995-06-19 | Process for purifyng phosphoric acid |
RU96124067A RU2139240C1 (en) | 1994-06-20 | 1995-06-19 | Method of purifying phosphoric acid |
BG101023A BG101023A (en) | 1994-06-20 | 1996-12-03 | Process for the purification of phosphohoric acid |
NO965470A NO965470L (en) | 1994-06-20 | 1996-12-19 | Process for the purification of phosphoric acid |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI942947 | 1994-06-20 | ||
FI942947A FI95905C (en) | 1994-06-20 | 1994-06-20 | Process for the purification of phosphoric acid |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1995035257A1 true WO1995035257A1 (en) | 1995-12-28 |
Family
ID=8540956
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/FI1995/000354 WO1995035257A1 (en) | 1994-06-20 | 1995-06-19 | Process for the purification of phosphoric acid |
Country Status (12)
Country | Link |
---|---|
EP (1) | EP0768985A1 (en) |
AU (1) | AU2740195A (en) |
BG (1) | BG101023A (en) |
CZ (1) | CZ365596A3 (en) |
FI (1) | FI95905C (en) |
HU (1) | HUT76719A (en) |
NO (1) | NO965470L (en) |
PL (1) | PL318219A1 (en) |
RO (1) | RO114886B1 (en) |
RU (1) | RU2139240C1 (en) |
SK (1) | SK161696A3 (en) |
WO (1) | WO1995035257A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100454101B1 (en) * | 2002-03-15 | 2004-10-26 | 한국화학연구원 | Purification method and equipment for phosphoric acid |
KR100542969B1 (en) * | 2005-03-18 | 2006-01-20 | (주) 광진화학 | Method of refining high-purity phosphoric acid continuously using deserted liquid from process |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1166102A (en) * | 1965-10-04 | 1969-10-08 | Struthers Scientific Int Corp | Phosphoric acid process |
-
1994
- 1994-06-20 FI FI942947A patent/FI95905C/en active
-
1995
- 1995-06-19 PL PL95318219A patent/PL318219A1/en unknown
- 1995-06-19 SK SK1616-96A patent/SK161696A3/en unknown
- 1995-06-19 RO RO96-02409A patent/RO114886B1/en unknown
- 1995-06-19 AU AU27401/95A patent/AU2740195A/en not_active Abandoned
- 1995-06-19 CZ CZ963655A patent/CZ365596A3/en unknown
- 1995-06-19 WO PCT/FI1995/000354 patent/WO1995035257A1/en not_active Application Discontinuation
- 1995-06-19 RU RU96124067A patent/RU2139240C1/en active
- 1995-06-19 EP EP95922550A patent/EP0768985A1/en not_active Ceased
- 1995-06-20 HU HU9603513A patent/HUT76719A/en unknown
-
1996
- 1996-12-03 BG BG101023A patent/BG101023A/en unknown
- 1996-12-19 NO NO965470A patent/NO965470L/en not_active Application Discontinuation
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1166102A (en) * | 1965-10-04 | 1969-10-08 | Struthers Scientific Int Corp | Phosphoric acid process |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100454101B1 (en) * | 2002-03-15 | 2004-10-26 | 한국화학연구원 | Purification method and equipment for phosphoric acid |
KR100542969B1 (en) * | 2005-03-18 | 2006-01-20 | (주) 광진화학 | Method of refining high-purity phosphoric acid continuously using deserted liquid from process |
Also Published As
Publication number | Publication date |
---|---|
NO965470D0 (en) | 1996-12-19 |
FI942947A0 (en) | 1994-06-20 |
BG101023A (en) | 1997-08-29 |
PL318219A1 (en) | 1997-05-26 |
HUT76719A (en) | 1997-10-28 |
FI95905B (en) | 1995-12-29 |
HU9603513D0 (en) | 1997-02-28 |
AU2740195A (en) | 1996-01-15 |
CZ365596A3 (en) | 1997-05-14 |
EP0768985A1 (en) | 1997-04-23 |
RO114886B1 (en) | 1999-08-30 |
SK161696A3 (en) | 1997-07-09 |
FI95905C (en) | 1996-04-10 |
RU2139240C1 (en) | 1999-10-10 |
NO965470L (en) | 1996-12-19 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
HU217783B (en) | Process for the purification of phosphoric acid by the wet process | |
EP0161704B1 (en) | Process for the production of water soluble ammonium phosphates | |
US4299804A (en) | Removal of magnesium and aluminum impurities from wet process phosphoric acid | |
US4639359A (en) | Process of removing cationic impurities from wet process phosphoric acid | |
CN217350773U (en) | System for coproduction iron phosphate through nitrophosphate fertilizer device | |
US3975178A (en) | Purification of wet-process phosphoric acid with methanol and ammonia | |
CN1083034A (en) | The production method of ammonium potassium dihydrogen phosphate | |
CA2368699C (en) | Process for production of phosphoric acid by crystallisation of phosphoric acid hemihydrate | |
EP0768985A1 (en) | Process for the purification of phosphoric acid | |
EP0208422A2 (en) | Process for the manufacture of monopotassium phosphate | |
CA1045339A (en) | Process and apparatus for purifying wet-processed phosphoric acid | |
CA1066020A (en) | Process for obtaining pure orthophosphoric acid from superphosphoric acid | |
US4117089A (en) | Process for preparing sodium ammonium hydrogen-phosphate and ammonium chloride from wet process phosphoric acid | |
US3388966A (en) | Ammonium phosphate preparation | |
US4134964A (en) | Process and apparatus for purifying wet-processed phosphoric acid | |
US4147757A (en) | Method for producing ammonium phosphate which is substantially free of arsenic | |
CA1199471A (en) | Method of separating magnesium from wet process superphosphoric acid | |
GB2078694A (en) | Crystallizing phosphoric acid | |
RU2253639C2 (en) | Method of manufacturing granulated mineral fertilizer containing nitrogen and phosphorus; and granulated mineral fertilizer | |
US4536378A (en) | Phosphate fertilizer production | |
WO1997027157A2 (en) | Method for the preparation of sodium ammonium phosphate | |
SU1096259A1 (en) | Process for producing fodder dicalcium phosphate | |
SU929612A1 (en) | Process for producing fertilizer from ammonium phosphate mother liquors | |
RU1810319C (en) | Method of calcium hydrophosphate production | |
SU969697A1 (en) | Process for producing complex fertilizer |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): AM AT AU BB BG BR BY CA CH CN CZ DE DK EE ES GB GE HU IS JP KE KG KP KR KZ LK LR LT LU LV MD MG MN MW MX NO NZ PL PT RO RU SD SE SG SI SK TJ TM TT UA UG US UZ VN |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): KE MW SD SZ UG AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN ML MR NE SN TD TG |
|
DFPE | Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101) | ||
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
WWE | Wipo information: entry into national phase |
Ref document number: 1995922550 Country of ref document: EP |
|
WWE | Wipo information: entry into national phase |
Ref document number: PV1996-3655 Country of ref document: CZ |
|
WWE | Wipo information: entry into national phase |
Ref document number: 161696 Country of ref document: SK |
|
WWE | Wipo information: entry into national phase |
Ref document number: 96-02409 Country of ref document: RO |
|
REG | Reference to national code |
Ref country code: DE Ref legal event code: 8642 |
|
WWP | Wipo information: published in national office |
Ref document number: 1995922550 Country of ref document: EP |
|
WWP | Wipo information: published in national office |
Ref document number: PV1996-3655 Country of ref document: CZ |
|
NENP | Non-entry into the national phase |
Ref country code: CA |
|
WWR | Wipo information: refused in national office |
Ref document number: 1995922550 Country of ref document: EP |
|
WWR | Wipo information: refused in national office |
Ref document number: PV1996-3655 Country of ref document: CZ |
|
WWW | Wipo information: withdrawn in national office |
Ref document number: 1995922550 Country of ref document: EP |