NO822973L - PROCEDURE FOR THE PREPARATION OF CADMA-FREE RAW PHOSPHORIC ACID - Google Patents
PROCEDURE FOR THE PREPARATION OF CADMA-FREE RAW PHOSPHORIC ACIDInfo
- Publication number
- NO822973L NO822973L NO822973A NO822973A NO822973L NO 822973 L NO822973 L NO 822973L NO 822973 A NO822973 A NO 822973A NO 822973 A NO822973 A NO 822973A NO 822973 L NO822973 L NO 822973L
- Authority
- NO
- Norway
- Prior art keywords
- phosphoric acid
- sulphide
- acid
- cadmium
- ammonia
- Prior art date
Links
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 title claims description 50
- 229910000147 aluminium phosphate Inorganic materials 0.000 title claims description 25
- 238000000034 method Methods 0.000 title claims description 15
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 30
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 claims description 17
- 229910021529 ammonia Inorganic materials 0.000 claims description 14
- 229910019142 PO4 Inorganic materials 0.000 claims description 11
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 10
- 239000010452 phosphate Substances 0.000 claims description 10
- 229910052793 cadmium Inorganic materials 0.000 claims description 8
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 7
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims description 7
- 229910017604 nitric acid Inorganic materials 0.000 claims description 7
- 239000002244 precipitate Substances 0.000 claims description 7
- CJOBVZJTOIVNNF-UHFFFAOYSA-N cadmium sulfide Chemical compound [Cd]=S CJOBVZJTOIVNNF-UHFFFAOYSA-N 0.000 claims description 6
- 229910052980 cadmium sulfide Inorganic materials 0.000 claims description 6
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 238000005119 centrifugation Methods 0.000 claims description 2
- 239000000243 solution Substances 0.000 description 19
- 229910001385 heavy metal Inorganic materials 0.000 description 15
- 239000002253 acid Substances 0.000 description 14
- 150000004763 sulfides Chemical class 0.000 description 11
- 235000021317 phosphate Nutrition 0.000 description 9
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 8
- 238000001556 precipitation Methods 0.000 description 7
- 238000010521 absorption reaction Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 159000000007 calcium salts Chemical class 0.000 description 4
- 239000003337 fertilizer Substances 0.000 description 4
- 229910052500 inorganic mineral Inorganic materials 0.000 description 4
- 239000011707 mineral Substances 0.000 description 4
- 239000011541 reaction mixture Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 3
- 235000011114 ammonium hydroxide Nutrition 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000029087 digestion Effects 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 229910052753 mercury Inorganic materials 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910021607 Silver chloride Inorganic materials 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 238000005188 flotation Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 2
- 238000006386 neutralization reaction Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 2
- ZHJGWYRLJUCMRT-UHFFFAOYSA-N 5-[6-[(4-methylpiperazin-1-yl)methyl]benzimidazol-1-yl]-3-[1-[2-(trifluoromethyl)phenyl]ethoxy]thiophene-2-carboxamide Chemical compound C=1C=CC=C(C(F)(F)F)C=1C(C)OC(=C(S1)C(N)=O)C=C1N(C1=C2)C=NC1=CC=C2CN1CCN(C)CC1 ZHJGWYRLJUCMRT-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000000184 acid digestion Methods 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 235000019728 animal nutrition Nutrition 0.000 description 1
- 229910052586 apatite Inorganic materials 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000001506 calcium phosphate Substances 0.000 description 1
- 239000001175 calcium sulphate Substances 0.000 description 1
- 235000011132 calcium sulphate Nutrition 0.000 description 1
- 239000013065 commercial product Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 239000013530 defoamer Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000011017 operating method Methods 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000020477 pH reduction Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- VSIIXMUUUJUKCM-UHFFFAOYSA-D pentacalcium;fluoride;triphosphate Chemical compound [F-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O VSIIXMUUUJUKCM-UHFFFAOYSA-D 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- CYQAYERJWZKYML-UHFFFAOYSA-N phosphorus pentasulfide Chemical compound S1P(S2)(=S)SP3(=S)SP1(=S)SP2(=S)S3 CYQAYERJWZKYML-UHFFFAOYSA-N 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 1
- 150000003464 sulfur compounds Chemical class 0.000 description 1
- 229910021653 sulphate ion Inorganic materials 0.000 description 1
- YUKQRDCYNOVPGJ-UHFFFAOYSA-N thioacetamide Chemical compound CC(N)=S YUKQRDCYNOVPGJ-UHFFFAOYSA-N 0.000 description 1
- DLFVBJFMPXGRIB-UHFFFAOYSA-N thioacetamide Natural products CC(N)=O DLFVBJFMPXGRIB-UHFFFAOYSA-N 0.000 description 1
- 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 description 1
- 229940078499 tricalcium phosphate Drugs 0.000 description 1
- 229910000391 tricalcium phosphate Inorganic materials 0.000 description 1
- 235000019731 tricalcium phosphate Nutrition 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05B—PHOSPHATIC FERTILISERS
- C05B7/00—Fertilisers based essentially on alkali or ammonium orthophosphates
-
- 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
- C01B25/22—Preparation by reacting phosphate-containing material with an acid, e.g. wet process
- C01B25/2208—Preparation by reacting phosphate-containing material with an acid, e.g. wet process with an acid or a mixture of acids other than sulfuric acid
- C01B25/2216—Preparation by reacting phosphate-containing material with an acid, e.g. wet process with an acid or a mixture of acids other than sulfuric acid with nitric acid or nitrous vapours in aqueous medium
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Fertilizers (AREA)
- Removal Of Specific Substances (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Macromonomer-Based Addition Polymer (AREA)
- Saccharide Compounds (AREA)
Description
Oppfinnelsen vedrører en fremgangsmåte til fremstilling av kadmiumfri råfosforsyre fra råfosfat, idet man oppslutter råfosfatet med salpetersyre. The invention relates to a method for producing cadmium-free raw phosphoric acid from raw phosphate, whereby the raw phosphate is digested with nitric acid.
Til oppslutning av råfosfater (forforitt, apatitt) anvendes mange fremgangsmåter hvor ved innvirkning av en mineralsyre det tungtoppløselige trikalsiumfosfat av mineralet omdannes til fosforsyre og kalsiumsaltet av den anvendte mineralsyre. Dette kalsiumsalt må deretter adskilles for å få rå fosforsyre. De i råfosfatet tilstedeværende tungmetall-ioner som bly, kadmium, kvikksølv og arsen blir for en stor del tilbake i råfosforsyren. Many methods are used to dissolve raw phosphates (forphorite, apatite) where, by the action of a mineral acid, the sparingly soluble tricalcium phosphate of the mineral is converted into phosphoric acid and the calcium salt of the mineral acid used. This calcium salt must then be separated to obtain crude phosphoric acid. The heavy metal ions present in the raw phosphate such as lead, cadmium, mercury and arsenic remain to a large extent back in the raw phosphoric acid.
Når man videreforarbeider denne syre, f.eks. til gjødnings-middel eller dyrefor, kommer de nevnte tungmetaller i slutt-produktet. Av sunnhetsmessige grunner er det imidlertid uønsket når det over gjødningsmiddelet eller dyrefor og plante eller dyrisk næring disse tungmetaller, spesielt kadmium kommer i den menneskelige organisme. Man har derfor tilstrebet å utarbeide fremgangsmåter for å fjerne de nevnte forurensninger fra råfosforsyren. When this acid is further processed, e.g. for fertilizer or animal feed, the mentioned heavy metals end up in the final product. For health reasons, however, it is undesirable when these heavy metals, especially cadmium, enter the human organism via the fertilizer or animal feed and plant or animal nutrition. Efforts have therefore been made to develop methods for removing the aforementioned contaminants from the raw phosphoric acid.
Således kan man raffinere fosforsyre fra sure oppslutninger Thus, phosphoric acid can be refined from acidic digestions
ved ekstrahering med organiske oppløsningsmidler eller rense ved ioneutveksling eller absorbsjon. Disse fremgangsmåter kommer av økonomiske grunner mindre på tale for en stor- by extraction with organic solvents or purification by ion exchange or absorption. For economic reasons, these methods are less suitable for a large
teknisk anvendelse. technical application.
Det er også kjent at man fra råfosforsyre som fremkommer ved oppslutning med svovelsyre (såkalt våtfosforsyre) ved be-handling med svovelhydrogen kan fjerne tungmetaller som kadmium som tungtoppløselig sulfider. Dermed må i første rekke den samlede frie svovelsyre nøytraliseres eller fjernes som uopp-løselig sulfat. Et atomforhold alkali/fosfor fra ca. 0,05 It is also known that heavy metals such as cadmium can be removed as sparingly soluble sulphides from raw phosphoric acid produced by digestion with sulfuric acid (so-called wet phosphoric acid) by treatment with hydrogen sulphide. Thus, in the first place, the total free sulfuric acid must be neutralized or removed as insoluble sulphate. An atomic ratio of alkali/phosphorus from approx. 0.05
til 0,3 er nødvendig. Først da kan det gjennomføres utfelling mes sulfid (Europeisk patentsøknad publikasjonsnummer o23 195). to 0.3 is required. Only then can precipitation of sulphide be carried out (European patent application publication number o23 195).
Av en relativt ren fosforsyre med et innhold på over 45 vekt-% ^ 2°s ^~ ar kadmiumsulfidet seg også utskille ved innpresning av svovelhydrogen under trykk (DE-OS 24 22 902). From a relatively pure phosphoric acid with a content of over 45% by weight ^ 2°s ^~ the cadmium sulphide is also separated by pressing in hydrogen sulphide under pressure (DE-OS 24 22 902).
Ifølge Chemical Abstract Bd. 89, referat 18 18 94a (1978) be-handles vårfosforsyre med en blanding av et oppløselig sulfid og kalsiumhydroksyd. Derved skal det samtidig utfelles kal-siumsulfat og tungmetallsulfider. According to Chemical Abstract Vol. 89, report 18 18 94a (1978), spring phosphoric acid is treated with a mixture of a soluble sulphide and calcium hydroxide. Thereby, calcium sulphate and heavy metal sulphides are to be precipitated at the same time.
De nevnte sulfidutfellings-fremgangsmåter har den ulempe at The aforementioned sulphide precipitation methods have the disadvantage that
de ikke er direkte overførbare på råfosforsyre som ble opp-sluttet etter Odda-fremgangsmåten. Ved denne fremgangsmåten oppsluttes råfosfatet med konsentrert salpetersyre og det fåes en sterk salpetersyreholdig råfpsforsyre. Til adskillelse av kalsiumnitrat hvis oppløselighet er sterkt temperatur-avhengig avkjøles og det utkrystalliserte kalsiumnitrat-tetrahydrat adskilles. De i den sterkt sure oppslutnings-oppløsning tilstedeværende tungmetallioner, f.eks. fra bly, kvikksølv, aren, spesielt imidlertid fra kadmium blir for en stor del i oppløsningen, den såkalte modersyre. Den inneholder ved siden av vann og forskjellige forurensninger dessuten ca. 15 - 20 vekt-% P2°5'ca* 30~35 vekt-% HN03°9they are not directly transferable to crude phosphoric acid which was suspended according to the Odda method. In this method, the raw phosphate is digested with concentrated nitric acid and a strong nitric acid-containing crude phosphoric acid is obtained. For the separation of calcium nitrate, the solubility of which is strongly temperature-dependent, is cooled and the crystallized calcium nitrate tetrahydrate is separated. The heavy metal ions present in the strongly acidic digestion solution, e.g. from lead, mercury, arene, especially, however, from cadmium becomes for a large part in the solution, the so-called mother acid. In addition to water and various contaminants, it also contains approx. 15 - 20 wt% P2°5'ca* 30~35 wt% HN03°9
ca. 7-10 vekt-% CaO. Modersyren nøytraliseres vanligvis trinnvist med ammoniakk og den dannede krystallgrøt blandes med kalsiumsalter og granuleres til gjødningsmidler. about. 7-10 wt% CaO. The mother acid is usually neutralized step by step with ammonia and the formed crystal slurry is mixed with calcium salts and granulated into fertilisers.
Det besto derfor den oppgave å finne en fremgangsmåte som muliggjør minst mulig teknisk oppbud å adskille tungmetallene, spesielt kadmium fra modersyren fra Odda-fremgangsmåten. The task was therefore to find a method that enables the least possible technical effort to separate the heavy metals, especially cadmium from the parent acid from the Odda method.
Derved måtte det tas hensyn til at denne inneholder små mengder fluorid og derfor er sterkt korrosiv. Videre er den forurenset med sanddeler som virker sterkt abrasivt. Dertil kommer at på grunn av nærvær av gelformet kiselsyre er skylleoperasjoner vanskelige å gjennomføre. ' . r, In doing so, it had to be taken into account that this contains small amounts of fluoride and is therefore highly corrosive. Furthermore, it is contaminated with sand particles that have a highly abrasive effect. In addition, due to the presence of gelled silicic acid, flushing operations are difficult to carry out. ' . r,
Det er nu funnet en fremgangsmåte til fremstilling av kadmium fri råfosforsyre fra råfosfat, hvor man oppslutter råfosfatet med salpetersyre, man fjerner hovedmengden av det dannede kalsiumnitrat således at det blir tilbake kadmiumholdig vandig råfosforsyre med et innhold på ca. 30 - 35% HNO^, ca. 15 - 20%<P>2°5°^ca"^~10% Ca0fidet fremgangsmåten erkarakterisertved at man innstiller denne råfosforsyre med ammoniakk til et pH-område på 0,9 - 1,5, man tilsetter svovelhydrogen og man adskiller den utfelte kadmiumsulfidholdige utfelling fra råfosforsyren. A method has now been found for the production of cadmium-free raw phosphoric acid from raw phosphate, where the raw phosphate is dissolved with nitric acid, the main amount of calcium nitrate formed is removed so that cadmium-containing aqueous raw phosphoric acid with a content of approx. 30 - 35% HNO^, approx. 15 - 20%<P>2°5°^ca"^~10% Ca0fidet the method is characterized by adjusting this raw phosphoric acid with ammonia to a pH range of 0.9 - 1.5, adding hydrogen sulphide and separating the precipitated cadmium sulphide-containing precipitate from the crude phosphoric acid.
Når man unnlater tilsetningen av ammoniakk eller tilsetter mindre ammoniakk enn krevet så kommer det ved tilsetning av svovelhydrogen til en sterk utvikling av nitrogenoksyder respektiv en ufullstendig dannelse av en kadmiumsulfidholdig utfelling. Npr man med ammoniakk innstiller på høyere pH-verdier så danner det seg en slimaktig meget vansjelig filtrerbar utfelling som hovedsakelig er sammensatt av kiselgel, fosfat, kalsium-, magnesium- og aluminiumsalter. Dertil strander også forsøket på å utfelle sulfidene av tungmetallene ved hlyere pH-verdier og å adskille dem. When one omits the addition of ammonia or adds less ammonia than required, the addition of hydrogen sulphide results in a strong development of nitrogen oxides or an incomplete formation of a cadmium sulphide-containing precipitate. When you use ammonia to set higher pH values, a slimy, very unfilterable precipitate is formed which is mainly composed of silica gel, phosphate, calcium, magnesium and aluminum salts. In addition, the attempt to precipitate the sulphides of the heavy metals at higher pH values and to separate them also fails.
Ved de ifølge oppfinnelsen på pH-verdier mellom 0,9 og 1,5 innstilte salpetersure oppslutningsoppløsninger av råfosfat opptrer ofte allerede få timer uønskede utfellinger. Ut-fellingene av adskillelsen av tungmetallsulfidene bør derfor fortrinnsvis foregå omgående. With the nitric acid digestion solutions of raw phosphate set according to the invention at pH values between 0.9 and 1.5, unwanted precipitation often occurs within a few hours. The precipitation of the separation of the heavy metal sulphides should therefore preferably take place immediately.
Det er foretrukket ved tilsetning av ammoniakk å innføre minst mulig vann for at ved den etterfølgende fremstilling av faste gjødningsmidler lite vann må fordampes. It is preferred when adding ammonia to introduce as little water as possible so that during the subsequent production of solid fertilisers, little water has to evaporate.
Utfelling av sulfidene foregår fortrinnsvis ved pH-verdier Precipitation of the sulphides takes place preferably at pH values
på 1,0 - 1,2. Tilstedeværende uklarheter kan fjernes før eller etter behandlingen med ammoniakk fra modersyren ved sentrifugering eller filtrering. For den etterfølgende sulfitutfelling kan svovelhydrogen innføres gassformet eller of 1.0 - 1.2. Any turbidity present can be removed before or after the treatment with ammonia from the mother acid by centrifugation or filtration. For the subsequent sulphite precipitation, hydrogen sulphide can be introduced in gaseous form or
ved tilsetning av et oppløselig sulfid som f.eks. natriumsulfid frembringes i oppløsning. Likeledes kan man arbeide med svovelforbindelser som i surt miljø lett innbinder svovelhydrogen som f.eks. fosforpentasulfid eller tioacetamid. Det har vist seg egnet å anvende et overskudd av sulfid, spesielt et hundre til femtusen ganger molart overskudd, fortrinnsvis et femhundre til totusen ganger molart overskudd, referert til mengden tungmetallioner. Sulfidfellingen kan gjennomføres ved normalt trykk eller under forhlyet trykk. by adding a soluble sulphide such as e.g. sodium sulphide is produced in solution. Similarly, you can work with sulfur compounds which in an acidic environment easily incorporate hydrogen sulphide, such as e.g. phosphorus pentasulfide or thioacetamide. It has proved suitable to use an excess of sulphide, in particular a one hundred to five thousand times molar excess, preferably a five hundred to two thousand times molar excess, referred to the amount of heavy metal ions. The sulphide precipitation can be carried out at normal pressure or under reduced pressure.
Til måling av pH-verdiene i de konsentrerte mineralsure oppløsninger anvendes glasselektroder hensiktsmessig enstav-målekjeder med referansesystem Ag/AgCl, referanseelektrolytt 3m KCl+AgCl eller 3,5m KC1. Det kan spesielt anvendes svovelhydrogen-sikre enstav-målekjeder som f.eks. er utrustet med to etter hverandre koplede ved hjelp av diafragmer adskilte elektrolyttkamre. pH-verdiene måles i den konsentrerte opp-løsning uten fortynning. Til adskillelse av sulfidet sentrifugeres fortrinnsvis reaksjonsblandingen ved normalttrykk eller overtrykk og hvis nødvendig filtreres deretter. En an-rikning av tungmetallsulfider fra reaksjonsblandingen kan også foregå ved flottasjon, f.eks. således at som flottasjons-gass anvendes svovelhydrogen eller en svovelhydrogenholdig gass. Den for tungmetallsulfidene befridde oppløsning må To measure the pH values in the concentrated mineral acid solutions, glass electrodes are used, suitably single-rod measuring chains with reference system Ag/AgCl, reference electrolyte 3m KCl+AgCl or 3.5m KC1. In particular, hydrogen sulphide-safe single-rod measuring chains such as e.g. is equipped with two electrolyte chambers connected one after the other, separated by diaphragms. The pH values are measured in the concentrated solution without dilution. To separate the sulphide, the reaction mixture is preferably centrifuged at normal pressure or overpressure and, if necessary, then filtered. An enrichment of heavy metal sulphides from the reaction mixture can also take place by flotation, e.g. so that hydrogen sulphide or a gas containing hydrogen sulphide is used as flotation gas. The solution freed from the heavy metal sulphides must
ved utblåsning f.eks. ved hjelp av nitrogen befris for svovelhydrogen. Hvis man arbeider ved forhøyet trykk og/ eller forhøyet temperatur kan dette også foregå ved avspenning. when blowing out, e.g. hydrogen sulphide is liberated with the help of nitrogen. If you work at elevated pressure and/or elevated temperature, this can also take place during relaxation.
Den rensede råfosforsyre kan deretter på kjent måte nøytral-iseres med ammoniakk og den dannede saltoppløsning inndampes til fler-næringsstoff-gjødningsmiddel. Ved tilsetning av kalsiumsalter før eller etter inndampning får man derved et verdifullt NPK-gjødningsstoff. The purified crude phosphoric acid can then be neutralized with ammonia in a known manner and the salt solution formed is evaporated into multi-nutrient fertiliser. By adding calcium salts before or after evaporation, a valuable NPK fertilizer is obtained.
Som reaktorer for delnøytralisasjon med ammoniakk til pH As reactors for partial neutralization with ammonia to pH
1,5 og omsetningmed svovelhydrogen eller sulfider er det 1.5 and reaction with hydrogen sulphide or sulphides is
egnet såvel rørekar som også rørreaktorer av forskjellig konstruksjon. En driftsmåte for omsetning med ammoniakk og svovelhydrogen foretas ved 8 0 - 100°C under overtrykk i en rørreaktor og deretter adskilles dessuten under trykk sulfidene fordelaktig. Ved den etterfølgende avspenning fordampes svovelhydrogen og vann. Etter kodensasjonen av dampene tilbakeføres gjenvunnet svovelhydrogen i prosessen. suitable for mixing vessels as well as tube reactors of different constructions. An operating method for reaction with ammonia and hydrogen sulphide is carried out at 80 - 100°C under overpressure in a tube reactor and then the sulphides are also advantageously separated under pressure. During the subsequent relaxation, hydrogen sulphide and water evaporate. After the co-condensation of the vapours, recovered hydrogen sulphide is fed back into the process.
Den for delnøytraliseringen nødvendige ammoniakkmengde utgjør vanligvis 4 til 5 mol NH^/mol P2°5"The amount of ammonia required for the partial neutralization usually amounts to 4 to 5 mol NH^/mol P2°5"
Oppfinnelsen skal forklares nærmere ved hjelp av noen eks-empler. The invention will be explained in more detail with the help of some examples.
Eksempel 1 Example 1
Klaret modersyre innstilles ved hjelp av konsentrert vandig ammoniakkoppløsning på forskjellige pH-verdier. Hver gang 100 g av den dannede oppløsning ble ved væreIsetemperatur blandet med 0,005 mol natriumsulfid, hvilket tilsvarer ca. tusen ganger molart overskudd referert til tungmetall-innholdet, omrøres en time og sentrifugeres. De for ut-fellingene befridde oppløsninger ble analysert ved hjelp av atomabsorbsjon. Clarified mother acid is adjusted to different pH values using concentrated aqueous ammonia solution. Each time 100 g of the formed solution was mixed at room temperature with 0.005 mol of sodium sulphide, which corresponds to approx. thousand times molar excess referred to the heavy metal content, stirred for one hour and centrifuged. The solutions freed from the precipitates were analyzed by means of atomic absorption.
Eksempel 2 Example 2
I 500 g klaret modersyre ble det under omrøring og tilsetning av avskummer (Bayer 7800 ny, handelsprodukt på basis av alkylsulfonsyre) innført ammoniakkgass til det var oppnådd en pH-verdi fra 1,0 til 1,3. Ved en pH-verdi på 1,3 utgjorde Cd-innholdet 3,8 ppm. I hver gang 100 g av de dannede fosfor-sure oppløsninger ble det innført i 10 minutter svovelhydrogen og deretter sentrifugert i vekslende tider og eventuelt filtrert. Den for sulfiden adskilte oppløsning ble blandet med salpetersyre ved utblåsning med nitrogenbefridd for svovelhydrogen og analysert ved hjelp av atomabsorbsjon. Det funnede Cd-innhold ble omregnet til den for sulfider adskilte oppløsning. Ammonia gas was introduced into 500 g of clarified mother acid with stirring and addition of defoamer (Bayer 7800 new, commercial product based on alkylsulfonic acid) until a pH value of 1.0 to 1.3 had been achieved. At a pH value of 1.3, the Cd content was 3.8 ppm. In each time 100 g of the formed phosphoric acid solutions were introduced for 10 minutes hydrogen sulphide and then centrifuged for alternating times and optionally filtered. The solution separated for the sulphide was mixed with nitric acid by blowing with nitrogen freed from hydrogen sulphide and analyzed by atomic absorption. The Cd content found was converted to the solution separated for sulphides.
Eksempel 3 Example 3
Klaret modersyre (500 g) ble ved hjelp av 25 %ig ammoniakk-oppløsning (161 g) ved væreIsetemperatur innstilt på pH 1,3. Av den dannede oppløsning ble det hver gang dannet 100 g med de i følgende tabell oppførte mengder av natriumsulfid-oppløsning og omrørt en time. De deretter sentrifugerte (1 time) og for bunnavsetning adskilte prøver ble filtrert surgjort og analysert ved atomabsorbsjon. De funnende tung-metallinnhold ble omregnet på oppløsningen med pH 1,3. Clarified mother acid (500 g) was adjusted to pH 1.3 using a 25% ammonia solution (161 g) at room temperature. From the solution formed, 100 g were each time formed with the quantities of sodium sulphide solution listed in the following table and stirred for one hour. The samples that were then centrifuged (1 hour) and separated for sedimentation were filtered, acidified and analyzed by atomic absorption. The heavy metal content found was recalculated on the solution with pH 1.3.
Eksempel 4 Example 4
Klaret modersyre (500 g) ble ved hjelp av 25 %ig ammoniakk-oppløsning (164 g) ved værelsetemperatur innstilt på pH 1,3. Ved prøver av den dannede oppløsning (3,2 yg Cd/g-oppløsning) ble det såvel ved 60°C som også ved 78°C i 10 minutter ført r^S. Deretter ble reaksjonsblandingen filtrert ved de even-tuelle reaksjonstemperaturer. Clarified mother acid (500 g) was adjusted to pH 1.3 using 25% ammonia solution (164 g) at room temperature. When samples of the formed solution (3.2 ug Cd/g solution) were heated both at 60°C and also at 78°C for 10 minutes, r^S was carried out. The reaction mixture was then filtered at the possible reaction temperatures.
Filtratene ble surgjort og Cd-innholdet bestemt ved atomabsorbsjon. Det lå under 0,15'y°g Cd/g-oppløsning. The filtrates were acidified and the Cd content determined by atomic absorption. It was below 0.15 µg Cd/g solution.
Eksempel 5 Example 5
I klaret modersyre (443 g) ble det innført 43,4 g ammoniakk ved 25-30°C således at det ble oppnådd en pH-verdi på 1,1. Deretter ble oppløsningen oppvarmet til 70°C og behandlet i 10 minutter med ^S. Prøver av reaksjonsblandingen ble på den nedenfor nevnte måte adskilt fra tungmetallsulfidene ved 70°C og etter surgjøring.analysert på Cd og Hg. In clarified mother acid (443 g) 43.4 g of ammonia was introduced at 25-30°C so that a pH value of 1.1 was obtained. Then the solution was heated to 70°C and treated for 10 minutes with ^S. Samples of the reaction mixture were separated from the heavy metal sulphides in the manner mentioned below at 70°C and, after acidification, analyzed for Cd and Hg.
Claims (3)
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19813134847 DE3134847A1 (en) | 1981-09-03 | 1981-09-03 | "METHOD FOR PRODUCING CADMIUM-FREE RAW PHOSPHORIC ACID" |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| NO822973L true NO822973L (en) | 1983-03-04 |
Family
ID=6140746
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| NO822973A NO822973L (en) | 1981-09-03 | 1982-09-02 | PROCEDURE FOR THE PREPARATION OF CADMA-FREE RAW PHOSPHORIC ACID |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0074556B1 (en) |
| DE (2) | DE3134847A1 (en) |
| ES (1) | ES515429A0 (en) |
| NO (1) | NO822973L (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3212675A1 (en) * | 1982-04-05 | 1983-10-06 | Hoechst Ag | METHOD FOR SEPARATING HEAVY METAL COMPOUNDS FROM INTERMEDIATE PRODUCTS OF THE FABRICATION OF PHOSPHOROUS AGENTS |
| DE3327394A1 (en) * | 1982-05-18 | 1985-02-14 | Chemische Fabrik Budenheim Rudolf A. Oetker, 6501 Budenheim | Process for the elimination of cadmium from acidic, in particular P2O5-containing, solutions |
| DE3330224A1 (en) * | 1983-08-22 | 1985-03-14 | Chemische Fabrik Budenheim Rudolf A. Oetker, 6501 Budenheim | Process for removing cadmium and zinc from acid phosphate-containing and nitrate-containing solutions |
| DE3622597A1 (en) * | 1986-07-04 | 1988-01-07 | Budenheim Rud A Oetker Chemie | METHOD FOR FELLING AND SEPARATING CADMIUMSULFID FROM THE REFINATES OF PHOSPHORIC ACID PURIFICATION |
| NO164768C (en) * | 1988-03-04 | 1990-11-14 | Norsk Hydro As | PROCEDURE FOR THE REMOVAL OF HEAVY METALS, SPECIAL CADMIUM, FROM PHOSPHORIC ACID SOLUTIONS. |
| DE3826981A1 (en) * | 1988-08-09 | 1990-02-15 | Hoechst Ag | METHOD FOR PROCESSING DUST WHICH ARISES IN ELECTROTHERMAL PHOSPHORUS PRODUCTION |
| DE4010778A1 (en) * | 1989-05-26 | 1990-11-29 | Budenheim Rud A Oetker Chemie | Selective removal of cadmium from wet process phosphoric acid |
| JP4316946B2 (en) * | 2003-07-01 | 2009-08-19 | 日本化学工業株式会社 | High purity phosphoric acid and method for producing the same |
| DE102014006278B3 (en) * | 2014-05-02 | 2015-02-26 | Remondis Aqua Gmbh & Co. Kg | A process for purifying crude phosphoric acid (e.g., MGA acid) by adding ashes from waste incinerators comprising recovery of pure phosphoric acid, calcium sulfate, water soluble calcium hydrogen phosphates, and metal salt solution |
| FR3039830B1 (en) * | 2015-08-03 | 2018-09-07 | Ocp Sa | PROCESS FOR PRODUCING AN AMMONIUM PHOSPHATE FERTILIZER WITH A REDUCED CADMIUM CONTENT |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL7004350A (en) * | 1970-03-26 | 1971-09-28 | Stamicarbon | |
| DE2422902A1 (en) * | 1974-05-11 | 1975-11-20 | Kalk Chemische Fabrik Gmbh | Cadmium sulphide prodn. from contaminated phosphoric acid - by treating with gaseous hydrogen sulphide |
| DE2447390C3 (en) * | 1974-10-04 | 1983-11-17 | Hoechst Ag, 6230 Frankfurt | Process for purifying wet phosphoric acid |
| SE418845B (en) * | 1979-05-10 | 1981-06-29 | Boliden Ab | PROCEDURE FOR PURIFICATION OF VAT PROCESS PHOSPHORIC ACID |
-
1981
- 1981-09-03 DE DE19813134847 patent/DE3134847A1/en not_active Withdrawn
-
1982
- 1982-08-31 DE DE8282107985T patent/DE3267309D1/en not_active Expired
- 1982-08-31 EP EP82107985A patent/EP0074556B1/en not_active Expired
- 1982-09-01 ES ES515429A patent/ES515429A0/en active Granted
- 1982-09-02 NO NO822973A patent/NO822973L/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| ES8400071A1 (en) | 1983-11-01 |
| ES515429A0 (en) | 1983-11-01 |
| EP0074556A1 (en) | 1983-03-23 |
| DE3267309D1 (en) | 1985-12-12 |
| EP0074556B1 (en) | 1985-11-06 |
| DE3134847A1 (en) | 1983-03-17 |
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