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    公开号:SE1151263A1
    申请号:SE1151263
    申请日:2009-09-18
    公开日:2012-02-23
    发明作者:Yariv Cohen
    申请人:Easymining Sweden Ab；
    IPC主号:
    专利说明:

    And the liberated gaseous vapors must be scrubbed with an acid. The slurry from the pre-neutralization reactor (s), which usually contains between 16 and 23% water, is usually fed into an ammoniator granulator to complete the ammonia feed adapted to the desired product. The completion of the neutralization and the further water evaporation result in the formation of solid particles. It is necessary to recover unreacted ammonia from the gaseous vapors by scrubbing with an acid. Thereafter, the solid ammonium phosphate is usually dried in a separate reactor to reduce the moisture content. Loss of ammonia from the dryer is usually recovered by scrubbing with acid. The solid ammonium phosphates are normally cooled by air passing through a cooling reactor.
    For your applications such as plant nutrient irrigation (application of water-soluble fertilizers via irrigation water) and foliar fertilization (when fertilizers are sprayed on leaves) completely water-soluble ammonium phosphates are required to prevent insoluble substances from clogging the spreading equipment. Phosphoric acid from the wet process contains a considerable amount of impurities such as iron, aluminum, calcium, magnesium, cadmium, etc. which form water-insoluble solids in the neutralization with ammonia and therefore ammonium phosphates of fertilizer grade are not completely water soluble. Therefore, fully soluble P-fertilizers for plant irrigation purposes must be produced especially with purified phosphoric acid.
    The current technique for phosphoric acid purification is based on the extraction of crude phosphoric acid from the wet process in an organic solvent (ketones, trialkyl phosphates, alcohols, etc.) followed by re-extraction with water to produce a dilute and pure phosphoric acid, which is then concentrated by water evaporation. Purified phosphoric acid is then neutralized with ammonia to form completely soluble ammonium phosphate products according to the procedure described above.
    In general, two processes for the liquid extraction of phosphoric acid can be identified: a) partial recovery of phosphoric acid from concentrated solutions, and b) complete recovery of phosphoric acid in the presence of other acids or salts.
    Partial extraction of phosphoric acid from concentrated phosphoric acid prepared by dissolving sulfuric acid in apatite is the most common process. In this process, only a portion of the phosphoric acid is extracted into an organic phase.
    The remaining non-extracted phosphoric acid together with residual metal impurities is used for the production of low value phosphate salts such as various fertilizers. Any solvents that can dissolve phosphoric acid can be used in this process, both solvents that have a fairly constant coefficient of distribution down to fairly low concentrations such as alcohols, and solvents that show very little extraction capacity for phosphoric acid below a certain concentration threshold, ie. the partition coefficient is very sharply concentration dependent as for ethers, esters and selected ketones.
    Another approach is to achieve complete recovery of phosphoric acid in the presence of other acids or salts in high concentrations. By adding a second acid such as e.g. H2SO4 (U.S. Pat. No. 3,573,005) or a salt such as CaCl2 (U.S. Pat. No. 3,304,157), an improvement in the coefficient of distribution (the distribution ratio of the solute between the organic and water-soluble phase) of phosphoric acid can occur even at rather low phosphoric acid concentrations. Although the added acid is also extracted with the solvent, its proportion in the organic solvent is normally less than in the incoming solution. Suitable solvents are alcohols, trialkyl phosphates such as tributyl phosphate, etc., which have a fairly constant coefficient of distribution down to rather low phosphoric acid concentrations. The method is recommended for extracting phosphoric acid from the remaining crude phosphoric acid which arises as a result of the partial recovery process. The main disadvantage of this approach is that the final aqueous phase has a high content of the added acid (eg sulfuric acid) or of salts together with impurities which are not useful.
    The disadvantages of prior art production of ammonium phosphates are many. The phosphoric acid obtained after the gypsum filter is not suitable for the direct production of ammonium phosphate salts. The acid must be further concentrated by evaporation of water to a suitable phosphoric acid concentration (usually about 54% P2O5). Normally, the concentration of phosphoric acid takes place in three steps. The low concentration acid from the filter (28% P2O5) is allowed to evaporate to 40% PZOS in one step in a vacuum evaporator. The acid is then treated to remove precipitated solid particles and the clarified acid is then concentrated to 54% P 2 O 5 in two steps. The intermediate concentration is about 48% P2O5.
    The 54 'Vo-iga PgOs acid is used for ammonium phosphate production according to the procedure described above.
    Concentrating acids by evaporation is a very energy-intensive process. The amount of steam required to concentrate phosphoric acid usually varies between 2.5 to 5 tons of steam per ton of phosphorus, depending on the significant production cost. Commercial grade phosphoric acid production requires expensive equipment such as production conditions. The energy requirement for the concentration of phosphoric acid includes a steam transport system, evaporators, scrubbers for emissions, condensing equipment, cooling water systems, wastewater treatment systems and storage options for acid. In addition, additional equipment is required for the neutralization of phosphoric acid with ammonia in your steps, drying, cooling and scrubbing of ammonia-containing gases. A major disadvantage is that the quality of the ammonium phosphate product is determined by the quality of the apatite raw material. Fertilizer grade ammonium phosphates are generally contaminated with heavy metals such as cadmium and are not completely soluble and therefore not suitable for use in e.g. plant nutrient irrigation.
    The production of completely soluble ammonium phosphate salts (technical quality) is more complex and requires purification of commercial grade phosphoric acid with liquid extraction before the neutralization with ammonia takes place.
    The energy cost of water evaporation in this process is much higher because the phosphoric acid must be concentrated twice: a) the acid must be concentrated before the liquid extraction, and b) the purified phosphoric acid is diluted and must therefore be concentrated again by water evaporation. Additional equipment required for the production of completely soluble ammonium phosphates are pre-treatment equipment before liquid extraction, extraction equipment (liquid extraction), stripping equipment (liquid extraction) and evaporators for concentrating the purified acid.
    U.S. Patent 3,298,782 discloses a process for purifying phosphoric acid from a wet chemical process, which consists of a) extraction of phosphoric acid from an aqueous phase to an organic alcohol-amine phase, b) separation of the alcohol-amine phase from the aqueous phase and c) recovery of the purified the phosphoric acid from the alcohol-amine phase. The main purpose was to recover purified phosphoric acid by stripping with water. The text also mentions that phosphate salts can be recovered from the alcohol-amine phase via a reaction with a base. In one of the examples, an aqueous solution of ammonia was used to strip phosphate from the organic phase to an aqueous phase.
    U.S. Patent 3,458,282 discloses a method for purifying phosphoric acid by using an amine dissolved in an organic solvent (eg kerosene) as the extractant phase to either remove certain impurities from phosphoric acid or to recover phosphoric acid from the aqueous phase. When phosphoric acid was extracted with the solvent, amine and diluent, the aim was to obtain purified phosphoric acid by stripping with water or to obtain an aqueous solution containing phosphate salt by reaction with a water-soluble base. The patent text also mentions that it may be possible to remove phosphate from the amine by evaporating the organic solvent and treating the remaining material with an aqueous solvent or with a gas such as ammonia to precipitate phosphate. Evaporating and condensing very large amounts of an organic solvent such as kerosene is both complex and costly.
    U.S. Patent 3,894,143 discloses a process for obtaining good quality crystallized ammonium phosphate from wet chemically produced phosphoric acid and ammonia. The process involves a) creating a mixture of anhydrous phosphoric acid and acetone where all components are miscible with water, b) precipitating impurities by adding ammonia after which precipitated impurities are separated and a purified mixture is created, c) contacting the purified mixture with ammonia for producing ammonium phosphate crystals and a supernatant liquid phase, and d) separating the ammonium phosphate crystals from the supernatant liquid phase and distilling the liquid phase to separate acetone for recovery. The disadvantages of this method are that it includes distillation of large amounts of acetone, limited production of ammonium phosphates, and production of large amounts of aqueous solution of dilute ammonium phosphate waste. The process has therefore not been applied industrially.
    In the published international patent application WO 2008/115121, a method and an arrangement for phosphorus recovery are presented. Phosphorus ions are extracted from solutions by adsorbing phosphorus ions in a scavenger and by releasing phosphorus ions to an eluate during regeneration of the scavenger. The regeneration takes place with ammonia. Phosphate anions are precipitated in the form of tri-ammonium phosphate in connection with the addition of excess ammonia.
    The ammonia remaining in the solution after precipitation of tri-ammonium phosphate is reused to regenerate the scavenger. Unfortunately, tri-ammonium phosphate is unstable at room temperature and normal atmospheric pressure whereby the crystal decomposes with concomitant release of ammonia. Such an unstable crystal form is not suitable for direct use in agriculture. U.S. Pat. No. 3,415,619 discloses a process for producing ammonium phosphate. Water-soluble ammonium phosphate is obtained by extracting a substantially iron-free phosphoric acid, in aqueous solution, resulting from the reaction of a calcium phosphate-containing ore and a strong mineral acid, into an extractant of a water-insoluble trialkyl phosphate, separating the phosphoric acid-removing aqueous phase contacting the phosphoric acid charged extractant with anhydrous ammonia at a temperature of between about 20 and 90 ° C, and separating the solid water-soluble ammonium phosphate from the extractant. It is stated that the solid ammonium phosphate should be washed with low boiling point hydrocarbon solvent to remove the associated organic extractant. U.S. Pat. No. 3,342,579 discloses slowly soluble ammonium polyphosphates and methods for their manufacture. An appliance has a vessel with a stirrer and inlet for superphosphoric acid and anhydrous ammonia. The reacted material is filtered to obtain a solid crystal product.
    GB 636,035 describes improvements in processes for producing di-ammonium phosphate. Mono-ammonium phosphate is introduced into a solution of di-ammonium phosphate in a reactor and anhydrous ammonia is fed into the reactor. Diammonium phosphate crystals accumulate at the bottom of the chamber.
    U.S. Patent 4,781,905 discloses a process for producing phosphoric acid and / or phosphates from chemically produced phosphoric acid and an extractant therein. Crude acid is extracted with a water-immiscible solvent mixture consisting of mixed trialkyl-phosphine oxide and a diluent. Some of the P2O5 in the crude acid is extracted into the solvent mixture and the remainder remains in the electrification. Pure phosphoric acid or phosphates are produced by stripping the charged solvent with a suitable aqueous phase and the secondary calcium phosphate fertilizer is obtained by neutralizing the raftinate with calcium carbonate.
    There is a need for an improved method for producing completely soluble ammonium phosphates such as mono-ammonium phosphate (MAP) or di-ammonium phosphate (DAP), where costs associated with concentrating phosphoric acid by evaporation of water can be ruled out.
    SUMMARY A general object of the present invention is to improve methods and equipment for the production of ammonium phosphate from phosphorus-containing solutions. A further object of the present invention is to provide a method for producing completely soluble ammonium phosphates without the need for phosphoric acid to be concentrated by evaporation of water. Another object of the present invention is to provide a cost-effective method for producing ammonium phosphates without the need for drying and scrubbing ammonia from process vapors. A further object of the present invention is to provide recovered ammonium phosphate in a form which can be easily used for fertilizing purposes.
    The above objects are achieved with methods and devices according to the appended claims. In general terms, in a first aspect, a method of producing ammonium phosphates comprises providing a phosphorus-charged immiscible liquid phase, adding anhydrous ammonia to the immiscible liquid phase, precipitating mono-ammonium phosphate and / or di-ammonium phosphate from the immiscible water. the liquid phase and recovery of the precipitated mono-ammonium phosphate and / or di-ammonium phosphate from the immiscible liquid phase. In addition, the method consists of controlling the temperature, to a predetermined range, of the immiscible liquid phase during the addition and precipitation steps. In a second aspect, an arrangement for producing ammonium phosphates comprises a mixing container.
    The mixing container has an inlet adapted for a phosphorus-charged immiscible liquid phase and an inlet adapted for the addition of anhydrous ammonia in the non-water-miscible liquid phase. The arrangement further comprises a heat exchanger which is arranged in thermal contact with the immiscible liquid phase. A regulator is arranged so that the operation of the heat exchanger keeps the water-immiscible liquid phase in the mixing container within a predetermined temperature range. The device also includes a precipitate remover which is arranged so that the precipitated mono-ammonium phosphate and / or di-ammonium phosphate crystals are removed from the mixing container.
    Preferably, phosphorus is extracted into the phosphorus-charged immiscible liquid phase from solutions by adsorbing phosphorus into a surface-scavenger having the affinity for phosphorus to create the phosphorus-charged immiscible liquid phase. Phosphorus is removed from the surface scavenger by adding anhydrous ammonia during regeneration of the scavenger. The temperature of the fl-surface scavenger is preferably kept below its boiling point. The regenerated scavenger is preferably recycled continuously to recover phosphorus from further incoming solutions.
    The separated crystalline ammonium phosphate is washed, initially with an aqueous solution in which the pH is adjusted to a predetermined level. The scavenger that accompanies the crystals is separated from the heavy water phase in a phase separator. The scavenger thus separated is continuously recycled to extract phosphorus from an incoming solution. The aqueous wash solution is also recycled for further washing.
    Then the washed ammonium phosphate crystals are dried. The drying can preferably, at least in part, be carried out with the heat obtained from the heat exchange process which cools the mixture of anhydrous ammonia and phosphoric acid.
    The invention enables, in an environmentally friendly and cost-effective manner, the extraction of phosphorus from process den in the form of high-quality products such as ammonium phosphate fertilizers. The invention enables the production of MAP or DAP regardless of the initial composition of the precipitated crystals. According to the invention, phosphorus can be extracted as concentrated, water-soluble, inorganic products of high quality, ie. a high plant availability of phosphorus and a low heavy metal content. Another advantage of the present invention is that it enables the reuse of the scavenger without the need for distilling large amounts of surface scavengers.
    BRIEF DESCRIPTION OF THE DRAWINGS The invention, together with its further object and advantages thereof, can best be understood by reference to the following description and accompanying drawings, in which: FIG. 1 is a block diagram of an embodiment of a phosphor recovery arrangement; FIG. 2 is a block diagram of an embodiment of an arrangement for the production of ammonium phosphates according to the present invention; FIG. 3 is a schematic diagram of an embodiment of a method according to the present invention; and Figs. 4-5 are block diagrams of further embodiments of arrangements for the production of ammonium phosphates according to the present invention.
    DETAILED DESCRIPTION All drawings use the same reference numerals for similar or equivalent elements.
    Terminology often used in the present description is to be interpreted as follows: Scavenger - Materials that have an affinity for solutes, e.g. materials that adsorb ions, by ion association or solution mechanisms. The term includes various types of extractants that are included in solvents.
    Solvent - A liquid phase, usually organic, which preferably dissolves extractable solutes from an aqueous solution.
    Extractant - An active component, usually organic, of a solvent that enables extraction.
    Liquid extraction - The separation of one or more solutes from a mixture by mass transport between immiscible phases of which at least one phase is typically an organic liquid.
    Regeneration - The transfer from the scavenger of the ions or acids removed from the process solution to make the capture substance ready for reuse.
    Diluent - A liquid, usually organic, in which an extractant is dissolved to form a solvent.
    Raffinate - An aqueous phase from which a solute has been removed by extraction.
    The main purpose of the invention is to provide a simple and cost-effective method for the production of ammonium phosphates. The method enables the production of ammonium phosphate without having to concentrate phosphoric acid by evaporating water. In addition, the method enables the production of fully soluble and pure mono-ammonium phosphate or di-ammonium phosphate salts.
    A possible general approach for the production of ammonium phosphates from phosphoric acid is to extract phosphoric acid into an organic solvent and use ammonia as a means of precipitating ammonium phosphates directly from the organic phase. As described below, it appears that the use of anhydrous liquid ammonia or gaseous anhydrous ammonia is beneficial. Anhydrous liquid ammonia or gaseous anhydrous ammonia has not been tested in U.S. Pat. No. 3,298,782 or U.S. Pat. No. 3,458,282 as a means of precipitating ammonium phosphate directly from an organic phase. One reason for not testing such alternatives may be that there are significant difficulties associated with such a general approach such as insufficient phosphoric acid charge in the organic phase at low phosphoric acid concentrations, problems with heat evolution and evaporation of the solvent, loss of expensive solvents resulting from precipitation, difficulties in predicting the shape of the precipitated ammonium phosphate, and difficulties in separating impurities. These difficulties are described in the following text and must be resolved to become a commercially interesting approach.
    Solvents used for the purification of phosphoric acid such as ketones, trialkyl phosphates and alcohols require high concentrations of phosphoric acid in the leach solution in order to achieve a sufficiently high phosphoric acid charge in the organic phase for a liquid extraction process to be practical. The use of such solvents requires a concentration of the phosphoric acid by water evaporation before the phosphoric acid extraction takes place. Although sufficient for the liquid extraction process to be practical, it is well known that the reaction between ammonia and high phosphoric acid charge can be achieved in the organic phase, concentrated phosphoric acid is strongly exothermic which can lead to the solvent evaporating. Stripping a solvent charged with phosphoric acid, with an alkaline aqueous solution generates a significant amount of heat. The problem of such heat generation is described in U.S. Patent 4,112,118, which relates to a process for producing phosphate salts from phosphoric acid extracted in an organic solvent by stripping with an alkaline aqueous solution. To minimize heat production, the molar ratio between base and phosphoric acid is reduced to between 0.1: 1 and 0.5: 1 in order to enable a workable process. This underlines the problem of heat generation and evaporation of the solvent in precipitation of mono-ammonium phosphate (MAP) or di-ammonium phosphate (DAP) with anhydrous ammonia directly in the organic phase as the molar ratio of ammonia to phosphoric acid must be above 1. It is also difficult to predict how much heat is generated in a reaction between anhydrous ammonia and phosphoric acid in a specific solvent mixture because entalpidates are specific for each solvent mixture and therefore must be determined experimentally.
    In addition to the difficulties due to heat development and evaporation of the solvent, large amounts of solvent are expected to accompany the precipitated ammonium phosphate crystals and such a loss of the expensive solvent mixture would be economically unacceptable, at least for some applications. Removal of the pendant solvent by distillation is difficult because the boiling point of solvents such as tributyl phosphate (289 ° C) exceeds the melting point of mono-ammonium phosphate (190 ° C). Furthermore, the process must be controlled to produce stable ammonium phosphate salts such as mono-ammonium phosphate or di-ammonium phosphate, which are the desired end products. Finally, methods for removing contaminants such as metals, silica, oils, etc. must be identified for such a process to be applicable.
    All the above-identified and mentioned difficulties meant that the above-mentioned general approach has not been tested and not implemented in the industry before the current invention.
    Hereinafter, in Figure 1, an embodiment of a process for producing ammonium phosphate from a phosphorus-containing mineral in accordance with the present invention is described in detail. However, although it is an advantageous approach, the present invention is not limited to the recovery of phosphorus from minerals, but is applicable in many different systems where phosphate ions / phosphoric acid are present. A similar process with minor modifications can be used for e.g. recovery of phosphorus from ash from incinerated sewage sludge, ash from incinerated animal by-products, P-rich power plants in sewage treatment plants, industrial waste, etc. An embodiment of an arrangement 100 for recycling phosphorus is shown in figure. Apatite concentrate 2 obtained by enriching broken crude phosphate is subjected to dissolution with sulfuric acid 1 in a dissolution reactor 4 according to known methods which gives dissolved apatite 3. Known process systems include di-hydrate, hemi-hydrate, hemihydrate-dihydrate-, and dihydrate- hemihydrate processes. Calcium sulphate (gypsum) 5 and a phosphorus-containing aqueous solution 7 in this embodiment phosphoric acid, are then separated by filtration in a solution separator 6. Phosphoric acid of filter grade 7 can optionally be pretreated so that impurities are removed by known methods. The whole arrangement for dissolving apatite 4 and separating impurities 6 can be seen as a pretreatment to provide a crude solution to the liquid extraction process, i.e. a phosphorus-containing aqueous solution 7.
    The crude solution is fed to an arrangement 10 for the production of ammonium phosphates, in this embodiment via liquid extraction. Liquid extraction involves the selective transfer of solutes between two immiscible phases, an aqueous phase and an organic phase. The two immiscible phases are first mixed thoroughly to facilitate the transfer of the solutes and then separated.
    To recover phosphate from a phosphorus-containing aqueous solution 7, a liquid extraction process is used, in which a raw water solution containing phosphate ions / phosphoric acid is exposed to an organic phase (here called scavenger).
    Phosphate ions / phosphoric acid are thus extracted into the scavenger. This is described in more detail below. In general terms, the arrangement 10 for producing ammonium phosphates extracts ammonium phosphate 9 from the phosphorus-containing aqueous solution 7, giving a residual process liquid 8, which can preferably be reused together with sulfuric acid 1 for further dissolution.
    An embodiment of an arrangement 10 for the production of ammonium phosphates is illustrated in more detail in the figure. 2.
    An extraction section 12 is provided to allow adsorption of phosphorus from a phosphorus-containing aqueous solution 7 to a surface scavenger 15 which has been refined for phosphorus. An aqueous solution depleted of phosphorus leaves the extraction section 12. When used in conjunction with the phosphor recovery arrangement shown in Fig. 1, the phosphorus depleted solution becomes the remaining process liquid 8. An outlet from the extraction section 12 for scavenger 15 loaded with phosphor is connected to a inlet 22 for a phosphor-charged, water-immiscible, liquid phase to a mixing container 20, in which the scavenger 15 charged with phosphor forms a phosphor-charged immiscible liquid phase 14. As will also be further discussed below, an inlet for scavenger 15 is depleted of phosphor 16 to the extraction section 12. , connected at least indirectly, to the mixing container 20. This inlet for scavenger 15 depleted of phosphorus 16 is thus arranged to reuse the recycled scavenger 15 in the mixing container 20 for continued phosphorus adsorption in the extraction section 12.
    All organic solvents (scavengers) that can remove phosphorus from aqueous solutions can be used in the liquid extraction in the extraction section. The mechanism of phosphorus extraction can be either ionic association or solution of phosphoric acid or both. The composition of the scavenger should be chosen taking into account the concentration of the phosphoric acid supply, the presence of additional acids or salts, etc., in order to have a high loading capacity and an efficient and operable extraction process. Processing of dilute phosphoric acid streams requires the use of scavengers with a strong extraction force for phosphates. Liquid scavengers suitable for the extraction of phosphoric acid from dilute solutions are fl liquid amines. In general, primary, secondary and tertiary liquid amines can be used. Amine extractants have a low water solubility, good miscibility with organic solvents, good chemical stability, high selectivity and a strong binding capacity that enables extraction from very dilute solutions. Preferably, those amines having a nitrogen atom attached to a large organic molecule containing more than seven aliphatic or aromatic carbon atoms should be selected. Such organic amines are highly soluble in organic solvents and almost insoluble in water. In contact with an acid-containing solution, the amine base reacts with the acid to form a protonated positive charge, which associates with the anion of the acid. Organic amines can extract more acid than the stoichiometric ratio of 1 acid molecule per 1 molecule of amine by dissolving additional neutral acid molecules. With concentrated phosphoric acid, up to four phosphate molecules can be extracted per molecule of liquid amine. At high concentrations of amines, polymerization can take place to a third, undesirable, separate phase.
    However, the formation of the undesired third phase can be avoided by dissolving the amines in another organic solvent which is a strong Lewis base such as tributyl phosphate or alcohols. Mixtures of soluble extractants such as tri-butyl phosphate and fl-surfactant amines are preferably used together to efficiently extract phosphate at both high and low concentrations. , etc.) which interacts with phosphoric acid to form hydrogen association. During this mechanism, the extractant replaces parts of water molecules and dissolves the phosphoric acid molecule in the organic phase. The binding of phosphoric acid via hydrogen association is weak. Dissolving extractants can be divided into two groups: a) solvents which have a fairly constant partition coefficient down to rather low concentrations such as alcohols, tributyl phosphate, etc., and b) solvents which show a very small extraction capacity for phosphoric acid below a certain threshold concentration, ie. the partition coefficient is strongly concentration dependent such as ethers, esters and selected ketones e.g. methyl isobutyl ketone. For the processing of klter grade phosphoric acid, it is preferable to use mixtures of solvents which have a relatively constant partition coefficient down to rather low concentrations such as tributyl phosphate and liquid amines which have a strong extraction capacity for phosphate even at very low concentrations due to an ionism association.
    By extracting phosphoric acid with two mechanisms linked to each other, ie. phosphate adsorption by ionic association and solution of neutral phosphoric acid, mixtures of dissolving extractants such as tributyl phosphate and liquid amines such as trioctylamine are effective scavengers for both highly concentrated and highly dilute phosphoric acid streams. Partition coefficients of acid extraction with such scavengers are high, which means that the number of necessary contact steps is few. The volume ratio between the organic phase and the aqueous solution for extracting phosphoric acid from yralter grade phosphoric acid with a concentration of 5M can be less than 1011 and preferably below 5: 1. The phosphate concentrations obtained in the scavenger should preferably be above 1M. In addition, mixtures of dissolving extractants and fl surfactant amines are selective for anions and do not bind positively charged metals, which means that metal impurities separate from the extracted phosphoric acid and remain in the aqueous solution.
    Filter-grade phosphoric acid is fed to a liquid extraction process characterized by the scavengers described above. The liquid extraction process is preferably a continuous liquid extraction process using preferably liquid extraction equipment such as pulsed columns. However, other types of liquid extraction equipment can be used such as stirring columns, stirring columns, mixer settlers, inline mixers, centrifuges, etc.
    The raffinate depleted in phosphate is further treated to remove metal precipitates. It can then be used for apathy dissolution or for plaster rinsing, (see eg fi g. 1).
    One can choose to scrub the phosphorus-charged scavenger to remove contaminants which have been co-extracted to create a phosphorus-charged immiscible liquid phase. Eat to FIG. 2, the phosphorus-charged water-immiscible liquid phase 14 is then treated with anhydrous ammonia to form crystalline ammonium phosphate directly in the scavenger. For this purpose, the arrangement 10 for producing ammonium phosphates comprises a mixing container 20 with an inlet 22 for the phosphor-charged immiscible liquid phase 14. The mixing container further has an inlet 24 for supplying anhydrous ammonia 18 to the phosphor-charged immiscible liquid phase 14. Anhydrous or anhydrous gaseous anhydrous ammonia can be used.
    To form a solid ammonium phosphate crystal, it is required that ammon your ammonia molecules react with fl your phosphoric acid or hydrogen phosphate molecules to form a crystal structure via hydrogen bonding of ammonium molecules to easily contact ammonium phosphate crystals have a high water solubility. It is known that several solid crystalline ammonium phosphate phases are phosphate molecules. The weak bonds are separated with water, which can be obtained by contacting ammonia, phosphoric acid and water at different concentrations and temperatures.
    The following crystalline solid phases are known: (NH4) 1H2 (PO4 )®, (NH4) 3PO4, (NH4) 3PO4-2H2O, (NH4) 3PO4-3H2O, (NH3HPOtt-H2Og, (NH4) 2HPO4, (NH4) 2H2O, NH4H2PO4, (NH4) 3H2 (PO4) 4, NH4H5 (PO4) 2-H2O and NH4H5 (PO4) 2. Several of these solid crystalline ammonium phosphates are unstable at room temperature and at atmospheric pressure resulting in degradation of the crystal to another structure with the simultaneous release of ammonia.Such unstable crystalline solid phases are not suitable for use in agriculture.
    It is known that completely dry ammonia will not react with completely dry hydrogen chloride to form ammonium salt. Thus, moisture is necessary to effect the reaction. Extraction of phosphoric acid with scavengers such as tributyl phosphate is accompanied by simultaneous uptake of water molecules. The molar ratio of the co-extracted water to tributyl phosphate varies between 0.7 to 1.7 .mu.g / .mu.g / UBPLNQ depending on the concentration of phosphoric acid in the scavenger and the temperature.
    However, it has surprisingly been found that by reacting anhydrous ammonia with phosphoric acid or phosphate molecules in an organic scavenger (eg tributyl phosphate, mixtures of tributyl phosphate and alcohols, mixtures of tributyl phosphate and amines), the crystalline solid phase a molar ratio of ammonium to phosphate which is about 1 and that the crystals are stable at room temperature and atmospheric pressure. The crystalline solid phase was found to consist mainly of mono-ammonium phosphate (MAP) NH4H2PO4. A small proportion of diammonium phosphate (DAP) (NH4) 2HPO4 was also present. Thus, crystalline solid ammonium phosphate can surprisingly be produced by contacting anhydrous ammonia and phosphate in the scavengers described above, used directly for agricultural purposes.
    Precipitation of phosphorus from the above-described organic solvents proved to be very effective and enables a phosphorus removal efficiency above 99%. The high efficiency of stripping enables high operational capacity during extraction from phosphoric acid. Unlike stripping with water, which is based on an equilibrium reaction and which gives an incomplete phosphorus stripping, the reaction of phosphorus with ammonia is not equilibrium dependent and the phosphorus stripping becomes complete. It is known that anhydrous ammonia is soluble in various organic solvents such as ethanol. % at 25 ° C), methanol (16% by weight at 25 ° C), etc. However, the solubility of ammonia in tributyl phosphate is only 0.6% by weight at 20 ° C and the solubility decreases as the temperature increases. Above 35 ° C the solubility of ammonia in tributyl phosphate is negligible.
    Thus, the residual amount of ammonia in the scavenger after precipitation of phosphorus is very low. It was also discovered that there is a relationship between the phosphorus charge in the organic solvent and the pH and conductivity.
    The conductivity decreases and the pH increases with a decreasing concentration of phosphoric acid in the solvent. Ammonia supply can thus be controlled by measuring the conductivity and / or the pH value in the scavenger to enable operation without an excess of ammonia. For this purpose, again with reference to fi g. 2, the arrangement 10 for producing ammonium phosphates comprises a sensor 26, in this embodiment a sensor for monitoring a conductivity in the immiscible liquid phase, in the mixing container 20.
    The arrangement 10 for producing ammonium phosphates further comprises an additive control unit 28 connected to the sensor 26 and arranged to control the amount of anhydrous ammonia 18 added in response to the measured conductivity. In an alternative embodiment, the sensor 26 is a sensor for monitoring the pH of the immiscible liquid phase in the mixing container 20, and the additive control unit 28 is consequently arranged to control the amount of added anhydrous ammonia 18 in response to the measured pH value.
    Reaction between ammonia and phosphoric acid is, as mentioned above, strongly exothermic and therefore a significant amount of heat is expected to be produced during this reaction. However, it was a surprising discovery that the heat generated during the neutralization of a solvent charged with 1.42 M H 3 PO 4 (~ 50 ° C liter 'solvent) is lower than that required for the solvent to evaporate. The scavenger temperature can therefore in practice be controlled by heat exchange to a temperature within a desired range. The arrangement 10 for producing ammonium phosphate comprises of a heat exchanger 30 arranged in thermal contact with the immiscible liquid phase 15. In the embodiment in fi g. 2, the heat exchanger 30 is arranged in the mixing container 20 for recovering heat from the immiscible liquid phase 15 inside the mixing container 20.
    The temperature in the mixing container 20 where the scavenger 15 and ammonia 18 are mixed is preferably measured with a thermometer 32 and this measuring device is used by a control unit 34 to drive the heat exchange in such a way that the temperature of the immiscible liquid phase 15 in the mixing container 20 is kept within a predetermined temperature range. . Preferably, the scavenger to be used in the extraction section 12 is cooled to a temperature lower than 60 ° C since a lower temperature is advantageous in the extraction of phosphoric acid with the scavenger 15. In a particular embodiment, the cooling of the heat exchanger 30 can be achieved by evaporating the surface. anhydrous ammonia to gaseous form. In such a way, cooling can be obtained by using ammonia which is an ingredient in the final product. This is stated in fi g. 2 of the dashed arrows 36 and 37. For this purpose, the arrangement 10 for the production of ammonium phosphates comprises a source of liquid ammonia 19. A heating unit 23 is connected to the source of liquid ammonia 19 and is connected to or integrated with the heat exchanger 30. The heating unit 23 is arranged to utilize at least a portion of the heat recovered in the heat exchanger 30 to produce gaseous ammonia, which is used as the anhydrous ammonia 18. This means that the inlet 24 for adding anhydrous ammonia 18 in the mixing vessel 20 is connected to extract the gaseous ammonia from the source with fl surface ammonia 19.
    Alternatively, cooling can be accomplished in some other way, e.g. heat exchange with cooling water. This alternative is preferable when it is desired to be able to recover the generated heat for use in other processes or to be used for drying the recovered ammonium phosphate crystals, which will be discussed further below.
    The crystalline solid ammonium phosphates are then separated from the scavenger by known techniques for the separation of solid and liquid phases such as filtration, decantation, centrifugation, etc. 2, a precipitate remover 40 is provided to remove precipitated crystals of mono-ammonium phosphate and / or di-ammonium phosphate from the mixing vessel 20. The phosphorus depleted scavenger 16 is then preferably recovered continuously for the purpose of again recovering phosphate from a crude solution 12 in extraction. .
    Relatively large amounts of the scavenger accompany the separated ammonium phosphate crystals. These amounts are usually large enough to give economically unacceptable losses of the expensive solvent mixture. It is therefore preferable to also return these amounts of the scavenger. In the embodiment according to fi g. 2, the arrangement 10 for producing ammonium phosphates comprises a washing arrangement 50, which in turn consists of a wash 52 connected to the precipitating remover 40. The wash 52 is arranged to wash the separated crystals of ammonium phosphate. A dryer 54 is connected to the scrubber 52 and is arranged to dry the washed crystals. A separator 60 is connected to the scrubber 52 and is arranged to separate the remaining scavenger 17 which has been washed away from the crystals. The separator 60 is thus connected to the inlet of the scavenger extraction section 12 depleted of phosphor 16 to reuse the separated residual scavenger 17 for continued adsorption of phosphorus in the extraction section 12. The separator is also arranged so that the washing liquid depleted of remaining scavenger 59 is reused for washing crystals in the wash 52.
    According to one embodiment of the present invention, the scavenger accompanying the separated ammonium phosphate crystals is removed by washing the ammonium phosphate crystals with an aqueous solution saturated with ammonium phosphate. The scavenger initially accompanied by the crystals forms a separate phase, which is usually lighter than the dense aqueous phase, and is, as mentioned earlier above, immiscible with water. The two phases are thus spontaneously separated from each other. The separator 60 in this embodiment is therefore a phase separator arranged for the separation of scavengers and the saturated aqueous solution of ammonium phosphate. It was surprisingly discovered that the above-mentioned washing procedure is very effective. The carbon content of the washed crystals of ammonium phosphate was found to be lower than the carbon content of commercial high purity ammonium phosphate salts. It is believed that washing with a saturated ammonium phosphate solution is a dynamic process in which ammonium phosphate crystals are constantly dissolved and recrystallized, enabling efficient removal of the accompanying solvent. The operation of the washing procedure is simple and not very energy intensive. The saturated ammonium phosphate solution as a wash. Production ammonium phosphate solution is done by dissolving produced ammonium phosphate salts in aqueous solutions as separated from the crystals are continuously recycled to further of saturated water, phosphoric acid, or some other acid / salt solutions. As previously mentioned, the separated water-immiscible scavenger is recycled continuously to recover phosphate from a crude solution.
    The washed ammonium phosphate crystals are then dried in the dryer 54. The drying can advantageously be carried out at least in part with heat from the heat exchange process which cools during the mixing of anhydrous ammonia with phosphoric acid. For this purpose, the dryer 54 is connected to the heat exchanger 30 as shown by the dashed arrows 37 and 39. The dryer 54 is thus arranged so that it can utilize at least a part of the heat recovered in the heat exchanger 30 for drying the washed crystals.
    The ammonium phosphates produced are completely water-soluble, heavily depleted of metal and can be used for agricultural purposes as well as fertilization or plant nutrient irrigation.
    Another important advantage of the washing process according to the preferred embodiment of the present invention is that it enables control of the production of ammonium phosphates for the production of either MAP or DAP regardless of the initial composition of the precipitated crystals. If MAP is the desired end product, then a wash solution is used which preferably consists of a saturated aqueous solution of mono-ammonium phosphate. The pH value in the slurry is controlled and adjusted to a value between 2 and 6, preferably between 3 and 5 and most preferably to about 4.1 by adding e.g. phosphoric acid or ammonia. This process results in the production of MAP regardless of the initial composition of the precipitated crystals. In a similar manner if DAP is the desired end product, a wash solution consisting of a saturated aqueous solution of diammonium phosphate is used. The pH value in the slurry is controlled and adjusted to a value between 6 and 10, preferably between 7 and 9 and most preferably to about 8.3 by adding e.g. ammonia. This process results in the production of DAP regardless of the initial composition of the precipitated crystals. In such a way, production of both MAP and DAP is possible according to the invention. For this purpose, the wash 52 is further arranged to control the pH value of the saturated aqueous solution of mono-ammonium phosphate and / or di-ammonium phosphate.
    Fig. 3 shows a flow chart with method steps according to an embodiment of the present invention. A method for producing ammonium phosphates begins in step 200. In step 210, a phosphorus-charged immiscible liquid phase is provided. anhydrous ammonia is added to the water-immiscible surface phase in step 212. In a particular embodiment, the addition step 212 comprises monitoring the conductivity of the immiscible liquid phase and controlling an amount of added anhydrous ammonia in response to the measured conductivity. In another particular embodiment, the addition step 212 comprises monitoring the pH of the immiscible liquid phase and controlling an amount of added anhydrous ammonia in response to the measured pH. Mono-ammonium phosphate and / or di-ammonium phosphate precipitates in step 214 from the immiscible liquid phase. In step 216, the temperature of the immiscible liquid phase is controlled during the addition and precipitation steps to fall within a predetermined temperature range. As discussed in more detail below, the actual regulation can take place before, during and / or after the various stages of addition and folding. The important function is to ensure that the temperature during the addition and precipitation steps is kept within predetermined limits. It is of less importance when the actual water diversion takes place. Step 216 may therefore be located in time, simultaneously with and / or after steps 212 and 214. The temperature control usually involves heat extraction from the immiscible liquid phase. This heat can, at least in part, be used to produce gaseous ammonia from liquid ammonia by heating. This gaseous ammonia can be used as the anhydrous ammonia supplied in step 212. In step 218, mono-ammonium phosphate and / or di-ammonium phosphate precipitate out of the immiscible liquid phase. In the embodiment illustrated in Fig. 3, the method comprises a further step 220, in which crystals of extracted precipitated mono-ammonium phosphate and / or di-ammonium phosphate are washed. In step 222, the remaining water-immiscible liquid phase is separated, i.e. typically the scavenger (as discussed below), which has been washed away from the crystals. The separated residual scavengem is preferably reused to re-adsorb phosphorus to obtain the phosphorus-charged immiscible liquid phase as indicated by the a_wj_ [ym_a arrow 224.
    Likewise, the washing liquid, which has been greatly reduced from the remaining scavenger, is reused for further washing of crystals as indicated by the dashed arrow 226. In this particular embodiment, the washing is performed with saturated aqueous ammonium phosphate and the remaining amount of scavenger is separated by phase separation of the scavenger. saturated the aqueous solution of ammonium phosphate. The washed crystals are dried in step 228. Preferably, at least a portion of the heat from the temperature control step is used for the drying. In a preferred embodiment, the pH of the saturated aqueous solution of mono-ammonium phosphate and / or di-ammonium phosphate is controlled so that the chemical reactions are controlled to produce specific compositions of MAP and / or DAP. In particular, pure MAP can be obtained by acidic pH and pure DAP can be obtained by a slightly basic pH, as discussed above. In the embodiment of Fig. 3, step 210, which provides a phosphorus-charged immiscible liquid phase, in turn comprises adsorption of phosphorus from a phosphorus-containing aqueous solution to a surface scavenger with an affinity for phosphorus. This means that the scavenger charged with phosphorus forms a phosphorus-charged water-immiscible liquid phase.
    The method of the embodiment of Fig. 3 then also includes the additional step 230 where the regenerated scavenger, which is created in the extraction step 218, is reused for further adsorption of phosphorus in step 210.
    The process is completed in step 299. 16 As already indicated above, the actual recovery of heat from the phosphorus-charged immiscible liquid phase can be carried out in various ways. In the embodiment according to fig. 2, the heat exchanger 30 is integrated in the mixing container 20. This is currently believed to be the best way, as it provides a well-controlled temperature. However, there are other possible alternatives. Fig. 4 illustrates an embodiment where the heat exchanger 30 is arranged in contact with the immiscible liquid phase leaving the precipitator 40. The control unit 34 can still be controlled based on the temperature in the mixing container 20, as measured with a thermometer 32. Alternatively or as a complement, a control unit 34 'is operated based on the temperature of the scavenger fed to the extraction section 12 by means of a thermometer 322. In this way, the temperature of the scavenger fed into the extraction section 12 is primarily controlled, which in turn will keep the temperature of the phosphorus-charged immiscible liquid phase inside the mixing container. during the next cycle within the desired temperature range, in particular if there is information on the expected phosphorus content leaving the extraction section 12 with the phosphorus-charged immiscible liquid phase.
    In other words, by controlling the temperature of the scavenger fed to the extraction section 12, an indirect control of the temperature in the mixing container will also be achieved. This can be a good alternative to arrangements where the initial phosphorus content is relatively stable or at least predictable. The scavenger fed to the extraction section 12 can then be temperature optimized relative to phosphorus affinity.
    I fl g. 5, a further embodiment is illustrated, in which the heat exchanger 30 is arranged in contact with the immiscible liquid phase which leaves the extraction section 12 before it is supplied to the mixing container 20.
    Here the control can be based on one or both of the temperature in the mixing container or of the temperature of the charged scavenger before it is introduced into the mixing container 20. The temperature in the scavenger before it is introduced into the mixing container is then measured with a thermometer 32 "and by means of a control unit 34 ". In this way, the temperature of the charged scavenger is reduced and the expected exothermic reaction in the mixing vessel 20 will cause the water-immiscible liquid phase to reach a temperature within the predetermined range. This embodiment can have an advantage in applications where it is difficult to combine ammonia supply and precipitation with an efficient heat recovery.
    The detailed embodiments above are only a few examples of how a method and an arrangement for the production of ammonium phosphate can be arranged. The phosphorus-containing immiscible liquid phase is preferably provided as described in more detail above, but there are also other possibilities. The phosphorus-containing water-immiscible liquid phase can be provided via any type of ion exchange process. The phosphorus-containing fl surface phase can also be created via other chemical processes, such as dissolution from solid phases. Likewise, the post-processing of precipitated MAP and / or DAP is only a now preferred example of how MAP and / or DAP can be handled. Other more conventional techniques are direct distillation of the precipitate to evaporate the scavenger or other solvents directly without any washing step. Furthermore, in certain applications where the scavenger or other solvents are not very expensive and are harmless as contaminants in the produced MAP / DAP, the washing procedure must be completely excluded. Tests have been performed with various systems to illustrate and verify the benefits obtained with the methods and arrangements according to the principles described above. Some examples are presented below.
    EXAMPLE 1 An organic solvent consisting of 80% by volume of tributyl phosphate and 20% by volume of heptanol, having a pH of 5.9, was charged with 1.42 M H 3 PO 4 by exposing the organic solvent to aqueous solutions with phosphoric acid. The two immiscible phases are first mixed thoroughly to facilitate the transfer of phosphoric acid and then separated. The charged organic solvent having a pH of -0.4 was contacted with an excess of ande liquid anhydrous ammonia (> 50 g NH 3 liters of solvent). Crystalline solids are formed in the organic phase. The solid particles were separated from the organic solvent by centrifugation and decantation. The separated solid particles were rinsed several times with methanol and dried for 2 hours at 90 ° C.
    The recovered inorganic salt consisted of 12.3% N and 26.8% P which corresponds to 98% by weight of NH4H2PO4 and 2% by weight of (NH4) 2HPO4. The degree of separation of phosphorus from the organic solvent was found to be as high as 99.4%.
    EXAMPLE 2 The same experiment as described in Example 1 was repeated with an organic solvent consisting of 80% by volume of tributyl phosphate and 20% by volume of tri-octyl / decyl amine. The recovered inorganic salt consisted of 13% N and 26.6% P, which corresponds to 90% by weight of NH4H2PO4 and 10% by weight (NHr) of 2HPO4.
    EXAMPLE 3 The same experiment as described in Example 1 was repeated, with the only difference that a limited amount of liquid anhydrous ammonia was used (<20 g NH; liter solvent). The recovered inorganic salt consisted of 12.2% N and 26.9% P, which corresponds to 99% by weight of NH4H2PO4 and 1% by weight (NHil2HPO1).
    EXAMPLE 4 The same experiment as described in Example 3 was repeated, the only difference being that an organic solvent was used consisting of 80% by volume of tributyl phosphate and 20% by volume of tri-octyl / decyl amine. The recovered inorganic salt consisted of 12.4% N and 26.8% P, which corresponds to 97% by weight of NH4H2PO4 and 3% by weight of (NH4) 2HPO4.
    EXAMPLE 5 Measured amounts of liquid anhydrous ammonia were added to a solvent consisting of 80% tributyl phosphate and 20% heptanol, charged with 1.42 M H 3 PO 4. The pH value and conductivity of the solvent (22 ° C) as a function of added amounts of ammonia are shown in the following table 1: 18 Ammonia added pH Conductivity (g NH3 liters * solvent) (ms / cm) 0 -0.40 1.18 1 0.54 0.74 2.7 0.62 0.50 5.7 0.70 0.23 8.9 I 0.78 0.14 12 0.78 0.13 18.2 1.24 0.05 21 3.32 23.3 4.9 0.02 25 7.6 0.01 Table 1. pH value and conductivity of the solvent (22 ° C) as a function of added amounts of ammonia in example 5.
    EXAMPLE 6 The same experiments as described in Example 5 were repeated, with the only difference that an organic solvent consisting of 80% by volume of tributyl phosphate and 20% by volume of tri-octyl / decyl amine was used here. The pH value and conductivity of the solvent (22 ° C) as a function of the amount of ammonia added are shown in the following table 2: Ammonia added pH Conductivity (g NH; liters' solvent) (ms / cm) 0 -0.09 3.73 1.0 0.12 2.98 3.0 0.55 2.76 4.3 0.79 2.47 6.0 0.89 1.53 7.3 1.27 1.47 9.0 2.29 1.24 11.0 2.67 1.11 15 20 25 19 13.0 2.78 15.3 4.62 0.56 24.6 7.10 0.03 Table 2. pH and conductivity of the solvent (22 ° C) as a function of the added amounts of ammonia in Example 6.
    EXAMPLE 7 An excess of gaseous anhydrous ammonia was added to a solvent consisting of 80% by volume of tributyl phosphate and 20% by volume of heptanol charged with 1.42 M H 3 PO 4. The temperature of the solvent increased from 22 ° C to 78 ° C.
    EXAMPLE 8 The same experiments as described in Example 7 were repeated, with the only difference that an organic solvent consisting of 80% by volume of tributyl phosphate and 20% by volume of tri-octyl / decyl amine was used. The temperature of the solvent increased from 23 ° C to 86 ° C.
    EXAMPLE 9 Crystals of mono-ammonium phosphate were separated from a solvent consisting of 80% tributyl phosphate and 20% heptanol by decantation. The separated crystals were fed into an aqueous solution saturated with mono-ammonium phosphate. The crystals were separated from the saturated aqueous solution by centrifugation and dried at 90 ° C. The organic solvent initially accompanying the crystals formed a separate phase above the aqueous phase. The carbon content of these washed mono-ammonium phosphate crystals was found to be lower than the carbon content of high quality commercial phosphate mono-ammonium salts. Similar results were obtained using a solvent consisting of 80% tributyl phosphate and 20% tri-octyl / decyl amine.
    EXAMPLE 10 Crystals of mono-ammonium phosphate were fed into an aqueous solution saturated with di-ammonium phosphate. The pH of the aqueous solution was then adjusted to a value of 8.3 by the addition of gaseous anhydrous ammonia. The crystalline particles were then separated from the saturated aqueous solution and dried. The solid particles were found to consist mainly of di-ammonium phosphate. Thus, crystals of mono-ammonium phosphate could be converted into crystals of di-ammonium phosphate.
    The embodiments described above are to be seen as a pair of illustrative examples of the present invention.
    Those skilled in the art will appreciate that various modifications, combinations, and changes may be made in the embodiments without departing from the scope of the present invention. In particular, partial solutions in the various embodiments can be combined into other configurations where technically possible. However, the scope of this invention is claimed by the appended claims.
    权利要求:
    Claims (20)
    [1]
    A process for producing ammonium phosphate, comprising the steps of: providing (210) a phosphor-charged immiscible liquid phase (14); adding (212) anhydrous ammonia (18) to the phosphorus-charged immiscible liquid phase (14); precipitation (214) of at least one of mono-ammonium phosphate and di-ammonium phosphate from the immiscible liquid phase (14); controlling (216) a temperature for the immiscible liquid phase (15) during the steps of adding (212) and precipitating (214) to a predetermined temperature range; extracting (218) said precipitated at least one of mono-ammonium phosphate and di-ammonium phosphate from the immiscible liquid phase (15); washing (220) crystals of said extracted precipitated at least one of mono-ammonium phosphate and di-ammonium phosphate; and drying (228) the washed crystals, characterized by the further steps: separating (222) the remaining scavengers (17) washed off from the crystals; reuse (224) of separated residual scavenger (17) for further absorption of phosphorus for reuse for further extraction; and reusing (226) washing liquid depleted from residual scavengers for further washing of crystals; which washing step (220) comprises washing with saturated aqueous solution of ammonium phosphate; and which step of separating (222) the remaining scavenger (17) comprises phase separation of the scavenger and the saturated aqueous solution of ammonium phosphate.
    [2]
    The process according to claim 1, characterized in that a washing solution used in the step of washing is composed of saturated aqueous solutions of mono-ammonium phosphate or di-ammonium phosphate for the production of mono-ammonium phosphate and di-ammonium phosphate, respectively.
    [3]
    The process according to claim 2, characterized by controlling a pH value of the saturated aqueous solution of mono-ammonium phosphate to a pH of 2-6 or controlling a pH value of the saturated aqueous solution of di-ammonium phosphate to a pH of 6 -10 to drive chemical reactions to produce specific compositions of mono-ammonium phosphate or di-ammonium phosphate. 10 15 20 25 30 35 22
    [4]
    The process according to claim 3, characterized in that the control of a pH value for the saturated aqueous solution of mono-ammonium phosphate comprises the addition of phosphoric acid or ammonia and that the control of a pH value for the saturated aqueous solution of di-ammonium phosphate comprises the addition of ammonia .
    [5]
    The method according to any one of claims 1 to 4, characterized in that the step of providing (210) a phosphor-charged immiscible liquid phase (14) comprises the step of adsorbing phosphorus from a phosphorus-containing aqueous solution to a liquid tangent scavenger having affinity for phosphorus, wherein the scavenger charged with phosphorus forms the phosphorus-charged immiscible liquid phase (14); and by the further step of reusing recycled scavengers formed at the extraction step (218) for further adsorption of phosphorus.
    [6]
    The method according to any one of claims 1 to 5, characterized in that the addition step (212) comprises monitoring a conductivity of the immiscible liquid phase (14) and controlling an amount of added anhydrous ammonia (18) in response to the monitored conductivity.
    [7]
    The method according to any one of claims 1 to 5, characterized in that the addition step (212) comprises monitoring a pH of the immiscible liquid phase (14) and controlling an amount of added anhydrous ammonia (18) in response to the monitored pH. value.
    [8]
    The method according to any one of claims 1 to 7, characterized in that the step of controlling (216) a temperature comprises extracting heat from the immiscible liquid phase before, during and / or after the steps of adding (212) and precipitating (214).
    [9]
    The process according to claim 8, characterized in that the anhydrous ammonia (18) is gaseous ammonia and in the further step of producing the gaseous ammonia from surface ammonia by heating with at least a part of the heat extracted from step control (216) of a temperature.
    [10]
    At least a portion of the heat extracted from the temperature control step (216). The method according to any one of claims 1 to 9, characterized in that the drying step (228) uses
    [11]
    An arrangement (10) for producing ammonium phosphate, comprising: a mixing container (20); said mixing container (20) having an inlet (22) for a phosphor-charged immiscible liquid phase (14); Which mixing vessel (20) has an inlet for adding anhydrous ammonia (18) to the immiscible liquid phase (14); a heat exchanger (30) arranged in thermal contact with the immiscible liquid phase (15); a control unit (34) arranged to operate the heat exchanger (30) to keep the water-immiscible liquid phase (14) in the mixing container (20) within a predetermined temperature range; a precipitator (40) arranged to remove crystals of at least one of precipitated mono-ammonium phosphate and di-ammonium phosphate from the mixing container (20), a wash (52, 52 ') connected to the precipitator (40) and arranged to wash the crystals; and a dryer (54) connected to the wash (52, 52 ') and arranged to dry the washed crystals, characterized by a separator (60) connected to the wash (52, 52') and arranged to separate the remaining immiscible liquid phase ( 17) washed from the crystals; which separator (60) is connected to the inlet of the non-water-miscible liquid phase extraction section (12) depleted in phosphorus for reuse of the separated remaining non-water-miscible liquid phase (17) for further adsorption of the phosphor extraction section (12); which separator (60) is further arranged to provide washing liquid (59) depleted of residual immiscible liquid phase for reuse for washing crystals in the wash (52, 52 '); which wash (52) is arranged to wash the crystals with saturated aqueous solution of ammonium phosphate; and which separator (60) comprises a phase separator (58) arranged for separating the immiscible liquid phase (17) and the saturated aqueous solution of ammonium phosphate.
    [12]
    The arrangement according to claim 11, characterized in that the wash (52) is arranged to use a washing solution composed of saturated aqueous solution of mono-ammonium phosphate or di-ammonium phosphate for the production of mono-ammonium phosphate and di-ammonium phosphate, respectively.
    [13]
    The arrangement according to claim 12, characterized in that the wash (52) is arranged to control a pH value for the saturated aqueous solution of mono-ammonium phosphate and / or di-ammonium phosphate,
    [14]
    The arrangement according to claim 13, characterized in that the scrubber (52) is arranged for adding phosphoric acid or ammonia to the saturated aqueous solution of mono-ammonium phosphate or ammonia to the saturated solution of di-ammonium phosphate.
    [15]
    The arrangement according to any one of claims 11 to 14, characterized by an extraction section (12), arranged to adsorb phosphorus from a phosphorus-containing aqueous solution to a surface scavenger having affinity for phosphorus; an outlet from the phosphor-laden scavenger extraction section (12) is connected to the inlet (22) for a phosphorus-charged immiscible liquid phase to the mixing container, the phosphor-laden scavenger forming the phosphorus-charged immiscible liquid phase (14); an inlet to the extraction section (12) for scavenger depleted of phosphorus (16) is connected to (20) formed in the mixing container (20) by the action of the precipitating remover (40) for further adsorption of phosphorus in the mixing container and arranged to reuse the recovered scavenger extraction section ( 12).
    [16]
    The arrangement according to any one of claims 11 to 15, characterized by a sensor (26) for monitoring a conductivity of the immiscible liquid phase (14); and an additive control unit (28) connected to the sensor (26) and arranged to control an amount of added anhydrous ammonia (18) in response to the monitored conductivity.
    [17]
    The arrangement according to any one of claims 11 to 15, characterized by a sensor (26) for monitoring a pH value of the immiscible liquid phase (14); and an additive controller (28) connected to the sensor (26) and arranged to control an amount of added anhydrous ammonia (18) in response to the monitored pH value.
    [18]
    The arrangement according to any one of claims 11 to 17, characterized in that the heat exchanger (30) operates to extract heat from the phosphor-charged immiscible liquid phase (14) entering the mixing container (20), from the non-water-miscible liquid phase inside the mixing container (20). ) and / or from phosphorus-depleted non-water miscible liquid phase (17) leaving the mixing container (20).
    [19]
    The arrangement according to claim 18, characterized by a source of fl liquid ammonia (19); a heating unit (23) connected to the source with fl surface ammonia (19) and connected to or integrated with the heat exchanger (30), which heating unit (23) is arranged to utilize at least a part of the heat extracted in the heat exchanger (30) to produce gaseous ammonia; which inlet (24) for adding anhydrous ammonia (18) to the mixing vessel is connected for extracting gaseous ammonia from the source with liquid ammonia (19). 25
    [20]
    The arrangement according to any one of claims 11 to 19, characterized in that the dryer (54) is connected to the heat exchanger (30) and arranged to use at least a part of the heat extracted in the heat exchanger (30) for drying the washed crystals.
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    同族专利:
    公开号 | 公开日
    HRP20150779T1|2015-08-28|
    EP2435364A4|2013-06-19|
    MA33379B1|2012-06-01|
    CN102448877A|2012-05-09|
    AU2009347055B2|2014-12-11|
    CN102448877B|2015-05-27|
    SE535871C2|2013-01-22|
    CA2763079A1|2010-12-02|
    JP5567664B2|2014-08-06|
    PL2435364T3|2015-10-30|
    CA2763079C|2016-11-01|
    ES2542524T3|2015-08-06|
    US8658117B2|2014-02-25|
    JP2012528065A|2012-11-12|
    IL216109D0|2012-01-31|
    PT2435364E|2015-09-01|
    JO3028B1|2016-09-05|
    WO2010138045A1|2010-12-02|
    US20120070359A1|2012-03-22|
    DK2435364T3|2015-08-10|
    HUE027021T2|2016-08-29|
    RU2011149388A|2013-07-10|
    IL216109A|2015-08-31|
    BRPI0924956B1|2019-12-10|
    EP2435364B1|2015-05-06|
    SI2435364T1|2015-08-31|
    AU2009347055A1|2011-11-24|
    EP2435364A1|2012-04-04|
    TN2011000559A1|2013-05-24|
    RU2516411C2|2014-05-20|
    SA3325B1|2014-03-12|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE0950376|2009-05-27|
    PCT/SE2009/051041|WO2010138045A1|2009-05-27|2009-09-18|Production of ammonium phosphates|
    SE1151263A|SE535871C2|2009-05-27|2009-09-18|Production of ammonium phosphates|SE1151263A| SE535871C2|2009-05-27|2009-09-18|Production of ammonium phosphates|
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