US1873457A - Process for the production of chemically pure phosphoric acid - Google Patents
Process for the production of chemically pure phosphoric acid Download PDFInfo
- Publication number
- US1873457A US1873457A US393837A US39383729A US1873457A US 1873457 A US1873457 A US 1873457A US 393837 A US393837 A US 393837A US 39383729 A US39383729 A US 39383729A US 1873457 A US1873457 A US 1873457A
- Authority
- US
- United States
- Prior art keywords
- acid
- phosphoric acid
- raw
- chemically pure
- production
- 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 - Lifetime
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
- C01B25/237—Selective elimination of impurities
Definitions
- This invention relates to the production of chemically pure phosphoric acid.
- the cathodic current density is kept below 0.01 amperes per square centimeter, for instance, at 0.005 amperes per phorous acid are oxidized at the anode to orthophosphoric acid, whereas all metallic contaminat1ons, as well as arsenic and antimony are separated at the cathode.
- the acid is filtered so as to separate particles of the slime I precipitated at the cathode which may have passed over into the acid.
- electrolytic purification of the acid may be ef-' fected more rapidly and with better output of energy, when working at elevated temperatures of the electrolytic bath, viz. atabout 50 C. or more.
- the heating may be reflected either by the electrolyzing electric current itself, or by external means.
- the former method is preferred in most cases, as it may be carried out in a very simple manner.
- the electrolytic separation-of arsenic is not easily attained, but may be promoted by the presence of relatively small qllllantities of copper salt, probably owing to t e fact that a copper arsenide compound is deposited upon the cathode.
- a copper salt preferably copper phosphate
- the raw acid to be refined is analyzed and the copper salt added to such an extent that the ratio of .Cu-to As is brought to 1 to at least 2, preferably 1 t0 2.5-4. 7
- Example 2 A raw acid showing a specific gravity of 1.70 at 17.5 C., correspondin to a concentration of 84.5% H PO was su jected to our improved process. This raw acid contained the following contaminations Milligrams per liter Phosphorous acid 520 Arsenic 115 Heavy metals, except iron Iron- 20 The raw acid was electrolized with platinum anodes and copper cathodes at a bath temperature of about C.
- the process of producing chemically pure phosphoric acid from a technical raw acid which comprises subjecting the raw phosphoric acid to electrolysis at a bath temperature exceeding 50 (3., cathodes being used upon which the contaminations are deposited in the form of metals and metalloids without the phosphoric acid being reduced to lower stages of oxidation, the cathodic current density not exceeding 1 ampere per square decimeter.
- the cathodic current density not exceeding 1 ampere per square decimeter.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Electrolytic Production Of Metals (AREA)
Description
Patented Aug. 23, 1932 UNITED STATES PATENT OFFICE WILHELM M'O'LLER ANI) JOSEF MARTIN MICHEL, OF BITTERFELD, GERMANY, AS- SIGNORS TO I. G. FARBENINDUSTRIE .AKTIEENGESELLSCHAFT, OF FRANKFORT-ON- THE-MAIN, GER-MANY, A. CORPORATION OF Y PROCESS FOR THE PRODUCTION OF GHEMICALLYjPURE PHOSPHORIC ACID No Drawing. Application filed September 19, 1929, Serial No. 393,837, and in Germany September 25, 1928.
This invention relates to the production of chemically pure phosphoric acid.
For purifying acids, it has been proposed to subject them to electrolysis (see Lunges Schwefelsaurefabrikation, 2nd Volume, pages 1198/1199), but no particulars were a successful refinement of acids.
For purifying technical phosphoric acid which, as a rule, contains arsenic, arseneous acid, phosphorous acid and heavy metals as the most undesired contaminations, various purely chemical methods have been proposed, which, however, generally contemplate the removal of only a single one of these .contaminations, in the most cases arsenic.
Now we have found that all the abovementioned contaminations can be removed from the raw acid in a single operation and in a very simple manner by subjecting the raw acid to an electrolytic refinement, whenemploying cathodes upon which the metals or metalloids obtained from the contaminations by cathodic reduction are deposited without simultaneously reducing the orthophosphoric acid to lower phosphoric oxides. Chromium, platinum or tantalum .may be employed for the cathodes, the best results,
. however, bein obtained with copper or silver 'lll cathodes, as these require the lowest decomposition voltage whereby a maximum output of energy is attained. For the anodes only platinum practically comes into consideration. Preferably the cathodic current density is kept below 0.01 amperes per square centimeter, for instance, at 0.005 amperes per phorous acid are oxidized at the anode to orthophosphoric acid, whereas all metallic contaminat1ons, as well as arsenic and antimony are separated at the cathode. When the electrolysis is completed, the acid is filtered so as to separate particles of the slime I precipitated at the cathode which may have passed over into the acid. Moreover our improved process aifords the remarkable adinstance, an acid of 80 to 90%, can be refined immediately after its fabrication. The refining methods hitherto used are limited to acid concentrations of 25% asan upper limit, given as to the essential details required for as the usual precipitation of the heavy metals in the form of sulfides by means of sulfurettedhydrogen is only possible with such low concentrations. In order to oxidize the phosphorous acid when working according to this old method, nitric acid must'be added after-filtration, and finally the solution is evaporated to the desired concentration in quartz vessels.
Ea /ample 1 Milligrams per liter Phosphorous acid 490 Arsenic 25 Heavy metals, including iron 240 The raw acid was electrolyzed with anodesof platinum and cathodes of copper, the .cathodic current density amounting to 0.004 amperes/cm? and the anodic current density to 0.25 amperes/cm After 4 to 5 kiloampere-hours had passed through, the acid proved to be free from the above-mentioned contaminations and met all requirements demended of a pharmaceutically pure acid.
Further experiments have shown that electrolytic purification of the acid may be ef-' fected more rapidly and with better output of energy, when working at elevated temperatures of the electrolytic bath, viz. atabout 50 C. or more. The heating may be reflected either by the electrolyzing electric current itself, or by external means. However, the former method is preferred in most cases, as it may be carried out in a very simple manner. We have further observed that in some cases, when either none, or only an extremely small quantity of heavy metals are present in the raw acid, the electrolytic separation-of arsenic is not easily attained, but may be promoted by the presence of relatively small qllllantities of copper salt, probably owing to t e fact that a copper arsenide compound is deposited upon the cathode. Therefore small quantities of a copper salt, preferably copper phosphate, are added to the raw acid, to facilitate the separation of the arsenic in absence of heavy metals. The raw acid to be refined is analyzed and the copper salt added to such an extent that the ratio of .Cu-to As is brought to 1 to at least 2, preferably 1 t0 2.5-4. 7
Example 2 A raw acid showing a specific gravity of 1.70 at 17.5 C., correspondin to a concentration of 84.5% H PO was su jected to our improved process. This raw acid contained the following contaminations Milligrams per liter Phosphorous acid 520 Arsenic 115 Heavy metals, except iron Iron- 20 The raw acid was electrolized with platinum anodes and copper cathodes at a bath temperature of about C. with the addition of 0.2 grams of copper phosphate Gu (P00 .3 H O, per liter, the cathodic current density being kept at 0.004 amp/cm and the anodic current density at 0.25 amp/cm After 3 kiloainpere-hours had been passed through, the acid was found to be ,free from contaminations and answered the requirements of the Pharmacopoea Germanica, 6th edition. The elevation of the temperature up to 50 C.-was attained by simply embaling the electrolyzers. The voltage was thereby reduced from 22.5 to 18' volts, corresponding to a saving of energy of about 20%.
The technical progress of our improved process is due to its extraordinary simplicity as compared with the methods hitherto used, as acids of any concentration can be subjected to the refinement according to the present invention and the refined products are immediately ready for further use. This progress was rendered possible by recognizing that for the electrolytic refinement of phosphoric acid it does not suflice to subject the phosphoric acid to the action of a direct current between and acid-proof electrodes,but that the maximum current density of about 1 ampere per square decimeter must be employed in order to avoid the reduction of phosphoric acid, whereas the anodic current density may be higher.
We claim: I 1. The process of producing chemically pure phosphoric acid from a technical raw acid .which comprises: subjecting the raw phosphoric acid to electrolysis, cathodes being used upon. which'the contaminations are deposited in the'form of metals and metals loids without the phosphoric acid being reduced to lower stages of oxidation, the cathodic current density not exceeding 1 ampere per square decimeter.-
2. The process of producing chemically pure phosphoric acid from a technical raw acid which comprises subjecting the raw phosphoric acid to electrolysis at a bath temperature exceeding 50 (3., cathodes being used upon which the contaminations are deposited in the form of metals and metalloids without the phosphoric acid being reduced to lower stages of oxidation, the cathodic current density not exceeding 1 ampere per square decimeter.
\ 3. The process of producing chemically pure phosphoric acid from a technical rawacid poor in heavy metals which comprises adding a small quantity of a cop er salt to the raw phosphoric acid and sub ecting the raw acid to electrolysis, cathodes being used upon which contaminations are deposited in the form of metals and metalloids without the phos horic acid being reduced to lower stages 0 oxidation, the cathodes current density not exceeding 1' ampere per square decimeter.
4. The process of producing chemically pure phosphoric acid from a technical rawacid poor in heavy metals which comprises acid poor in heavy metals which comprises adding a copper salt to the raw phosphoricv acid to such an extent that the ratio of Cu to As is confined between the limits 1:2 and 1: 4, and subjecting the raw acid to electrolysis, cathodes being used upon which the contaminations are'de osited in the form of -metals and metalloi s without the phos-.
phoric acid being reduced to lower stages of oxidation, the cathodic current density not exceeding 1 ampere per square decimeter.
In testimony whereof, we aflix our signs.
tures.
WILHELM MULLER. JOSEF MARTIN MICHEL.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE1873457X | 1928-09-25 |
Publications (1)
Publication Number | Publication Date |
---|---|
US1873457A true US1873457A (en) | 1932-08-23 |
Family
ID=7747013
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US393837A Expired - Lifetime US1873457A (en) | 1928-09-25 | 1929-09-19 | Process for the production of chemically pure phosphoric acid |
Country Status (1)
Country | Link |
---|---|
US (1) | US1873457A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2839408A (en) * | 1957-03-04 | 1958-06-17 | Monsanto Chemicals | Method of producing condensed phosphoric acids |
US20050072667A1 (en) * | 2003-10-01 | 2005-04-07 | Permelec Electrode Ltd. | Apparatus and method for electrolytically treating chemical plating waste liquor |
-
1929
- 1929-09-19 US US393837A patent/US1873457A/en not_active Expired - Lifetime
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2839408A (en) * | 1957-03-04 | 1958-06-17 | Monsanto Chemicals | Method of producing condensed phosphoric acids |
US20050072667A1 (en) * | 2003-10-01 | 2005-04-07 | Permelec Electrode Ltd. | Apparatus and method for electrolytically treating chemical plating waste liquor |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
DE2453739C3 (en) | Process for the production of hydrogen peroxide | |
US1980381A (en) | Method of making ductile electrolytic iron from sulphide ores | |
US1945107A (en) | Method of making ductile electrolytic iron | |
US2044888A (en) | Process of purifying alkali metal hydroxide solutions | |
US1873457A (en) | Process for the production of chemically pure phosphoric acid | |
US2119560A (en) | Electrolytic process for the extraction of metallic manganese | |
DE1171919B (en) | Process for the electrolytic production of tetraalkylene lead | |
DE2445505A1 (en) | METHOD FOR PRODUCING SODIUM CHLORATE BY ELECTROLYSIS | |
DE3834807A1 (en) | METHOD FOR PRODUCING CARBONIC SALTS OF ALKALI METALS | |
US2066347A (en) | Production of nickel by electrolytic deposition from nickel salt solutions | |
US2417259A (en) | Electrolytic process for preparing manganese and manganese dioxide simultaneously | |
DE2456058C2 (en) | Process and arrangement for the recycle or batch processing of final pickling solutions associated with iron pickling | |
DE3872079T2 (en) | METHOD FOR ELECTROLYTIC REDUCTION AND SEPARATION OF EUROPIUM. | |
US1754125A (en) | Electrolytic recovery of metals | |
US1304222A (en) | George d | |
US3334034A (en) | Electrolytic method for the recovery of nickel and cobalt | |
DE302735C (en) | ||
DE503202C (en) | Manufacture of chemically pure phosphoric acid | |
SU61975A1 (en) | Method of processing manganese ores | |
US2133290A (en) | Anodic oxidation of ferrophosphorus | |
US572512A (en) | Phosphates of alkalies | |
US2135545A (en) | Process for the electrolytic production of ammonium perphosphate in solid form | |
US1290269A (en) | Production of alumina. | |
DE2943533A1 (en) | Metal, esp. copper and zinc electrowinning from sulphate - and opt. chloride soln., in diaphragm cell using chloride anolyte to give chlorine and alkali(ne earth) chloride by products | |
GB357630A (en) |