WO1999016711A1 - Single-stage gypsum bed process for producing potassium salts - Google Patents
Single-stage gypsum bed process for producing potassium salts Download PDFInfo
- Publication number
- WO1999016711A1 WO1999016711A1 PCT/FI1998/000763 FI9800763W WO9916711A1 WO 1999016711 A1 WO1999016711 A1 WO 1999016711A1 FI 9800763 W FI9800763 W FI 9800763W WO 9916711 A1 WO9916711 A1 WO 9916711A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- potassium
- gypsum
- sulfate
- bed
- process according
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
- C01D5/06—Preparation of sulfates by double decomposition
- C01D5/10—Preparation of sulfates by double decomposition with sulfates of magnesium, calcium, strontium, or barium
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
- C01D5/16—Purification
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Fertilizers (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention relates to a single-stage gypsum bed process for separating potassium and for producing potassium salts from organic residual solutions from the food, fermentation and animal feed industries by filtering the said residual solution through a gypsum bed so that the potassium ions of the residual solution react during the filtration in the gypsum bed with sulfate ions or with sulfate and calcium ions, forming potassium salts.
Description
Single-stage gypsum bed process for producing potassium salts
The present invention relates to a single-stage gypsum bed process for the separation of potassium and for the simultaneous production of potassium salts from the residual solutions from the food, fermentation and animal feed industries.
The residual solutions from the food, fermentation and animal feed industries, such as cane molasses, beet molasses, vinasse, potato cell sap, brown silage effluent, etc., contain large amounts of potassium and many valuable organic compounds, such as amino acids, proteins, organic acids and sugars, for which reason these residual solutions have typically been used as components of animal feeds or been spread as fertilizer on fields.
Previously, such dilute residual solutions, having a dry matter content of approx. 5- 15% by weight, have also been released into watercourses. Stricter environmental legislation has, however, led to a large proportion of the solutions being currently recovered, concentrated, and then used for the production of, for example, animal feeds. However, the use, in animal feeds, of these concentrated solutions having a dry matter content of approx. 65% is limited by their high salt content, potassium 5- 15% by weight of the dry matter.
Numerous processes have been developed for the removal of potassium from solutions of this type. Such processes include the crystallization of potassium as potassium sulfate (Swenson Process SA, Gist Brocades, Cultor) or as syngenite (N.V. Centrale Suiker Maatschappij). Attempts have also been made to apply special processes such as ion exchange (Suiker Unie, Cultor Oy, Kampen, W H) to this problem.
The process most commonly used in industry for the removal of potassium from the said residual solutions is the crystallization of potassium either as potassium sulfate (K2S04) or as syngenite (K2Ca(S04)2*H 0), of which final products neither one is pure and both contain as impurities organic compounds derived from the residual solution. These crystallization processes, also described in the literature, for example in patent publications DE-1 817 550, DE-1 900 242, NL-9 200 402 and EP-654 448, generally comprise at least two different process stages, i.e. crystallization and separation stages, and often also, for example, a separate pH control stage. According to them, sulfuric acid is added to the residual solution at the crystallization stage and is stirred. The separation of the formed salt is
implemented by commonly known methods, for example by filtration as a separate process stage.
Owing to the high viscosity of the said residual solutions, one problem in these known processes is a poorer miscibility and lesser transfer of heat, for which reason the crystallization of potassium salts in them is difficult. Furthermore, the crystals formed often remain small (approx. 10 μm), since the other components, in particular organic compounds, present in the residual solutions may cover crystal surfaces and thereby slow down crystal growth.
It is generally known that in viscous solutions there form more crystals as the temperature decreases, but the separation of the crystals becomes more difficult. In order to separate the formed potassium salt crystals from the formed slurry it has been preferable to cool the said slurry to a temperature of approx. 20-30 °C, at which temperature the potassium salt amount is maximal. However, the viscosity of both the solution and the crystal slurry increases rapidly as the temperature decreases. The separation of finely divided crystals from viscous solutions is very slow. It is true that with suitable auxiliary agents the filtration can be accelerated, but the use of auxiliary agents renders the process more complicated and increases the number of process stages and the required apparatus. In addition, the said auxiliary agents end up as impurities in the product.
A specific, significant problem decreasing the financial profitability of the methods currently used is that such residual solutions are produced in many units all over Europe; even within the area of the European Community there are some 200 sugar- producing units.
The present invention provides a novel single-stage process, simpler than the previously known methods, for the separation of potassium from the residual solutions from the food, fermentation and animal feed industries, such as cane and beet molasses, vinasse, potato cell sap or brown silage effluent. The obtained potassium salt product is suitable as such as raw material for fertilizers or animal feeds. When so desired, the potassium salt product may be washed with a saturated potassium sulfate solution in order to remove the organic impurities derived from the residual solution.
It has been observed that, when any residual solution mentioned above is filtered through a gypsum bed (CaS04*2H20), the potassium and sulfate ions present in the residual solution are caused to react with the gypsum, whereupon syngenite
(K2Ca(S04)2*H20) and potassium sulfate (K2S04) and/or glaserite (K3Na(S0 )2) are formed as reaction products. The sulfate ions required in the reaction can be added as sulfuric acid to the residual solution, either before or after the concentration of the solution. Alternatively, the sulfate can be added by mixing it in a solid form, for example, as ammonium sulfate, with the gypsum bed. Thereby the nitrogen content in the solution remaining after the filtration increases, and at the same time its value as a raw material for animal feed increases. The dissolution rate of ammonium sulfate, and thereby the reaction becoming maximally complete, can be affected by selecting the particle size of the ammonium sulfate so as to be the best suited for the conditions in each given case.
It is known that, instead of dihydrate gypsum, it is possible to use for the forming of syngenite also other compounds which produce calcium and sulfate ions and which react in a corresponding way, such as hemihydrate gypsum or potassium penta- calcium sulfate, K2S04*5CaS04*H20.
If the sulfate is added as sulfuric acid or ammonium sulfate to the residual solution before the solution is directed to the gypsum bed, primarily potassium sulfate, K2S04, is formed in the topmost part of the gypsum bed. If sodium is present in a sufficient amount, glaserite, K3Na(S04) , is formed instead of potassium sulfate. In the lower parts of the gypsum bed, where the potassium concentration is no longer sufficient for the forming of these compounds, there forms syngenite, K2Ca(S04)2*H20.
If the sulfate is added to the gypsum as ammonium sulfate, the preferable particle size being 0.1-1.0 mm, sulfate is freed so slowly that the forming product is in the main syngenite. A compact syngenite cake is formed, which slows down the flow of the solution through the gypsum bed. The rate of progress of the syngenite front in the gypsum bed is preferably approx. 5 cm/hour when the filtration is carried out under an overpressure of 1 bar.
In the process according to the invention, the filtration through a gypsum bed can be carried out under a pressure of 0.1-2.0 bar, the flow rate being preferably 1-10 cm/h.
In the process according to the invention, there form in the gypsum bed two deposits, the upper being mainly made up of potassium sulfate and/or glaserite, and the other, lower, being made up of syngenite. From this it follows that the potassium concentration in the product obtained from the process is approx. 10-30% by weight higher than that of a product obtained in corresponding conditions from a
conventional syngenite process and having a potassium concentration generally in the order of 15-20% by weight, expressed as K20. It can also be noted that the purification efficiency of the gypsum bed process is higher than that of the potassium sulfate process alone.
The process according to the present invention removes potassium more effectively than known methods from, for example, vinasse. After conventional sulfate precipitation, the potassium concentration in the solution is approx. 4% by weight; by the process according to the invention the potassium concentration in the solution can be lowered to below 2% by weight, calculated as K20.
In the single-stage process according to the invention, the two successive reaction stages of the conventional process have been combined to take place in the same apparatus. At the first stage, the potassium of the residual solution is separated by crystallization as potassium sulfate and/or glaserite, and at the second stage as syngenite. The advantage of the gypsum bed process is that, instead of the two crystallization stages and two filtration stages required by prior methods, there is thus required only one stage, in which the reaction and the filtration are combined.
Figure 1 shows schematically a gypsum bed process according to the invention, where the different reaction and filtration stages have been combined into one single stage (C). For the sake of comparison, Figure 2 shows schematically also a cor- responding conventional two-stage crystallization process wherein potassium sulfate (K2S04) is formed at stage (A) and syngenite at stage (B). After each reaction stage there is a separate separation stage.
In practice, the process according to the invention can be implemented, for example, by directing the residual solution through at least two gypsum beds in series. The gypsum beds are preferably placed on movable supports, for example containers. By pumping the solution through both of the gypsum beds (bed 1 and bed 2), the best possible purification result is obtained and at the same time it is ensured that the purification process is continuous. When the gypsum of the first bed (bed 1) in the process has reacted completely, forming syngenite, this bed (bed 1) is removed, the second gypsum bed (bed 2) is transferred to the place of the first one, and a new, unreacted gypsum bed (bed 3) is transferred to the second position in the series, and this procedure is repeated in the continuation.
Any excess vinasse solution remaining in the formed syngenite cake can, if so desired, be washed off with water and/or with the saturated potassium sulfate
solution which is formed when the said syngenite cake is washed with water. Alternatively, the syngenite cake can be washed with ample water to dissolve and separate the potassium sulfate, and thereby the syngenite is regenerated to gypsum which can be recycled to the reaction stage.
A particular advantage of the gypsum bed process according to the present invention is its movability, the usability of devices of various types, such as containers and filters, in the process, and the low amount of the investment required. Vinasse, as are other residual solutions from agriculture and fermentation, is produced by numerous small plants (approx. 50 m vinasse/d), for example in Europe. The purification capacity of the gypsum bed of one 30 m3 purification unit (container) according to the invention is approx. 150 m of vinasse. Thus, if the flow rate is 5 cm/h, it suffices that the used gypsum bed is replaced with a new one 2-3 times a week. A process such as this is profitable even in a small unit, and thus the collection of residual solutions and their transportation to special purification plants is rendered unnecessary; the overall transportation need is reduced to approx. 20% of the previous need.
The formed potassium-containing reaction product may either be spread as such as a fertilizer on fields, or it may be sluπϊed in water before being spread. Syngenite, as well as the other potassium compounds formed, may also be used as a raw material in the production of conventional fertilizers, for example granular field fertilizers. The residues of organic substances in the product may promote the granulation of the fertilizer product, and in the soil the organic matter will activate the action of soil microbes.
Examples
The following experiments were performed in order to show the functioning of the invention. All of the experiments were carried out at room temperature, a dihydrate gypsum (CaS04*2H20) was used for the gypsum bed, and solution analyses were carried out at different stages of the process in order to verify the purification of the vinasse and the formation of potassium salts. The reaction products were identified by X-ray diffraction analyses.
Example 1
An amount of 0.384 kg of a 50 per cent sulfuric acid (H2S04) was mixed with 2.0 kg of vinasse, and the mixture was filtered immediately through gypsum bed 1 (gypsum bed 1 = 0.2 kg of dihydrate gypsum). The flow rate being 5 cm/h, the
filtration took 1.5 h, which was also the total reaction time. The filtration was carried out under a pressure of 1 bar. The filtrate obtained from gypsum bed 1 was further caused to flow through two similar gypsum beds (beds 2 and 3). The initial substances, the reaction products formed at the different stages, and the filtrates obtained were analyzed. The results of the analyses are shown in Table 1.
Table 1
Example 2 (Experiments 2A and 2B; sulfuric acid or ammonium sulfate as the source of sulfate)
In Experiment 2 A, 1.664 kg if a 50 weight per cent sulfuric acid was mixed with 8.665 kg of vinasse, the mixture was filtered through a gypsum cake (1.664 kg), the reaction time being 3 hours. At the beginning of the filtration the pressure was 0.5 bar, but it was increased during the filtration as syngenite formed and the gypsum cake compacted. At the end the pressure was 2.0 bar. A water wash was carried out by filtering 3.5 kg of water through the cake.
In Experiment 2B, an amount of 1.089 kg of a coarse-grained ammonium sulfate having a particle size of approx. 1 mm was mixed with the gypsum bed (1.621 kg).
An amount of 8.443 kg of vinasse was filtered through this bed. The reaction time and the filtration pressure were the same as in Experiment 2A. Analyses according to Example 1 were performed, and their results are shown in Table 3.
Analyses according to Example 1 were performed on Experiments 2A and 2B, and their results are shown in Table 2.
Table 2
Example 3
Comparison experiments were carried out among sulfate precipitation, syngenite precipitation and the gypsum bed process according to the invention. In each experiment, a mixture was used which contained the same amount of a mixture of
residual molasses and sulfuric acid; the amount of sulfuric acid (100% by weight) was 10% by weight of the amount of the residual molasses. Both in the syngenite precipitation and the gypsum bed process, a stoichiometric amount of gypsum was used for forming syngenite. The arrangements for the experiment and the results of the analyses of the initial substances and the final products are shown in Table 3.
The final product obtained in the sulfate precipitation was glaserite, which was precipitated by agitating the reaction mixture for 1 hour, the final temperature being 40 °C.
In the syngenite precipitation, the agitation time was 5 hours and the final temperature was 45 °C.
In the gypsum bed process, the mixture of molasses and sulfuric acid was filtered through the gypsum bed in the course of 1 hour, filtration was repeated through the same bed, the final temperature was 20 °C. A vacuum of 0.9 bar was used for the filtration. The surface layer of the formed cake was analyzed, and the composition of the entire cake was calculated on the basis of a solution analysis.
On the surface of the cake there was a glaserite layer and in its center a syngenite layer; at the bottom of the cake there still remained unreacted gypsum.
Table 3
Claims
1. A single-stage gypsum bed process for producing potassium salts and for removing potassium from organic residual solutions, characterized in that the residual solution is filtered through a gypsum bed so that the potassium ions in the residual solution react during the filtration in the gypsum bed with sulfate ions or with sulfate ions and calcium ions, forming potassium salts.
2. A process according to Claim 1, characterized in that syngenite (K2Ca(S04)2*H20) and glaserite (K3Na(S04)2) and/or potassium sulfate (K2S04) are formed in the reaction.
3. A process according to Claim 1 or 2, characterized in that, before filtration, sulfuric acid and/or ammonium sulfate is added to the residual solution, or that a solid ammonium sulfate is mixed with the gypsum bed so that in the reaction the molar ratio (K+Na):S04 is 2.
4. A process according to any of the above claims, characterized in that the gypsum bed is formed from dihydrate gypsum (CaS04*2H 0).
5. A process according to any of the above claims, characterized in that the filtration can also be implemented as either overpressure or vacuum filtration under a pressure of 0.1-2.0 bar, the flow rate being 1-10 cm/h.
6. A process according to any of the above claims, characterized in that the potassium salt cake obtained after the filtration may be washed with water and/or a saturated potassium sulfate solution in order to remove any organic residues.
7. A process according to any of the above claims, characterized in that the potassium salt cake formed in the reaction may be regenerated to dihydrate gypsum by washing it with ample water.
8. A potassium salt product having a high potassium content or a high potassium and sodium content, characterized in that it is prepared by a process according to any of Claims 1-7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU93516/98A AU9351698A (en) | 1997-09-29 | 1998-09-28 | Single-stage gypsum bed process for producing potassium salts |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI973836A FI103199B1 (en) | 1997-09-29 | 1997-09-29 | One step gypsum bed process for producing potassium salts |
| FI973836 | 1997-09-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1999016711A1 true WO1999016711A1 (en) | 1999-04-08 |
Family
ID=8549630
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/FI1998/000763 WO1999016711A1 (en) | 1997-09-29 | 1998-09-28 | Single-stage gypsum bed process for producing potassium salts |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU9351698A (en) |
| FI (1) | FI103199B1 (en) |
| WO (1) | WO1999016711A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008040358A1 (en) * | 2006-10-03 | 2008-04-10 | Protanol Bv | A method for providing proteins and fermentation products from a plant material |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1900242A1 (en) * | 1968-01-09 | 1969-07-31 | Centrale Suiker Mij Nv | Cattle food from sugar-free molasses |
| DE1817550A1 (en) * | 1968-01-09 | 1970-12-10 | Centrale Suiker Mij Nv | Removal of potassium from molasses |
| NL9200402A (en) * | 1992-03-04 | 1993-10-01 | Avebe Coop Verkoop Prod | Method for reducing the potassium content of concentrated deproteinized potato juice. |
| EP0654448A1 (en) * | 1993-11-19 | 1995-05-24 | Swenson Process S.A. | Process for treating waste liquid produced in agriculure and food industries |
-
1997
- 1997-09-29 FI FI973836A patent/FI103199B1/en active
-
1998
- 1998-09-28 WO PCT/FI1998/000763 patent/WO1999016711A1/en active Application Filing
- 1998-09-28 AU AU93516/98A patent/AU9351698A/en not_active Abandoned
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1900242A1 (en) * | 1968-01-09 | 1969-07-31 | Centrale Suiker Mij Nv | Cattle food from sugar-free molasses |
| DE1817550A1 (en) * | 1968-01-09 | 1970-12-10 | Centrale Suiker Mij Nv | Removal of potassium from molasses |
| NL9200402A (en) * | 1992-03-04 | 1993-10-01 | Avebe Coop Verkoop Prod | Method for reducing the potassium content of concentrated deproteinized potato juice. |
| EP0654448A1 (en) * | 1993-11-19 | 1995-05-24 | Swenson Process S.A. | Process for treating waste liquid produced in agriculure and food industries |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008040358A1 (en) * | 2006-10-03 | 2008-04-10 | Protanol Bv | A method for providing proteins and fermentation products from a plant material |
Also Published As
| Publication number | Publication date |
|---|---|
| FI103199B (en) | 1999-05-14 |
| FI973836A (en) | 1999-03-30 |
| FI103199B1 (en) | 1999-05-14 |
| AU9351698A (en) | 1999-04-23 |
| FI973836A0 (en) | 1997-09-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1288084C (en) | Process for producing soft potassium magnesium vanadium | |
| CN111330943B (en) | Method for dealkalizing red mud and ecologically soil-transforming | |
| WO1989003364A1 (en) | Method of reforming soluble salts to effect purification and increase crystal size thereof | |
| WO2019149405A1 (en) | Pedosphere-improving granulate, method for producing same, and use thereof | |
| BG63775B1 (en) | Method for potassium sulphate production | |
| US7687046B2 (en) | Method of producing phosphoric acid salt | |
| US5035872A (en) | Method of preparing potassium magnesium phosphate | |
| US6143271A (en) | Process for producing potassium sulfate from potash and sodium sulfate | |
| CN1184091A (en) | Potash fertilizer producing method by using potassium-rock | |
| EP0904251A1 (en) | A process for producing high-purity potassium salts | |
| CN1220970A (en) | Technology for producing magnesium sulfate in treatment of titanium white waste sulfuric acid | |
| WO1999016711A1 (en) | Single-stage gypsum bed process for producing potassium salts | |
| CN217350771U (en) | System for coproduction phosphoric acid through nitrophosphate fertilizer device | |
| US4301130A (en) | Method of washing waste phosphogypsum | |
| US4152397A (en) | Method for the conversion of phosphate rock containing magnesium into phosphoric acid and a mixture of magnesium and calcium carbonates | |
| CN112645367B (en) | Method for preparing calcium sulfate, magnesium oxide and potassium calcium magnesium nitrate from calcium-magnesium-containing leaching solution | |
| RU2238906C2 (en) | Manufacture of alkali metal salts via combined ion-exchange/crystallization method | |
| US4536376A (en) | Method of producing potassium magnesium phosphate | |
| RU2509724C1 (en) | Method of producing highly pure calcium carbonate and nitrogen-sulphate fertiliser during complex processing of phosphogypsum | |
| CN112723404A (en) | Method for separating calcium, magnesium and phosphorus in chemical beneficiation by-product | |
| Dunseth et al. | Removal of scale-forming elements from sea water | |
| US3515534A (en) | Recycling ammonium sulfate in nitric phosphate processing | |
| RU2716048C1 (en) | Method of processing salt solution wastes containing a mixture of sulphates and nitrates of ammonium and sodium | |
| CN112758972A (en) | Method for preparing calcium sulfate, magnesium hydroxide and potassium magnesium nitrate from calcium-containing magnesium leaching solution | |
| CN112777622A (en) | Method for preparing calcium sulfate, magnesium hydroxide and potassium calcium nitrate/potassium calcium magnesium nitrate from calcium and magnesium-containing leaching solution |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| AK | Designated states |
Kind code of ref document: A1 Designated state(s): AL AM AT AU AZ BA BB BG BR BY CA CH CN CU CZ DE DK EE ES FI GB GD GE GH GM HR HU ID IL IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT UA UG US UZ VN YU ZW |
|
| AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): GH GM KE LS MW SD SZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG |
|
| 121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
| DFPE | Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101) |
Free format text: (EXCEPT GD) |
|
| NENP | Non-entry into the national phase |
Ref country code: KR |
|
| REG | Reference to national code |
Ref country code: DE Ref legal event code: 8642 |
|
| 122 | Ep: pct application non-entry in european phase | ||
| NENP | Non-entry into the national phase |
Ref country code: CA |