The method of purification of wet-process phosphoric acid

 

The invention relates to a method for producing phosphoric acid with a low content of impurities, used in the production of phosphate salts technical and food skills using solvent extraction with tributyl phosphate with subsequent separation of the aqueous and organic phases and reextracting phosphoric acid from the organic phase with water. Extraction and reextraction carried out in a pulsating columns by mixing of aqueous and organic phases with the formation of the emulsion under the influence of air at a temperature of extraction 30-50oC and the temperature of the Stripping 40-80oC. the essence of the method is that the total flow of water coming on stage Stripping, divided into two parts in the ratio V1: V2=1:(3-9), the first part of the water is mixed with the extract after separation of the phases contaminated by impurities, the aqueous phase is mixed with phosphoric acid in a volume ratio of 1:(6-15) and then passed to the stage of extraction with tributyl phosphate in the beginning of the process, and the extract is sent to the mixing with the second part water to obtain a purified phosphoric acid. This method allows to reduce the content of metal impurities in the purified acid in 2-4 times, i.e. to improve the quality of purified kioti with low content of impurities, used in the production of phosphate salts technical and food skills. The invention consists in a method that includes the step extraction of phosphoric acid tributyl phosphate at 30-50oWith the release of raffinate and reextraction phosphoric acid from the organic phase under 40-80oWith obtaining purified phosphoric acid and the subsequent circulation of the extractant, extraction and reextraction are a mixture of aqueous and organic phases with the formation of the emulsion under the influence of air, the total flow of water entering reextraction, divided into two parts in the ratio V1: V2=1:(3-9), the first part of the water mixed with the extracts and after separation of the phases contaminated by impurities, the aqueous phase is mixed with phosphoric acid in a volume ratio of 1:(6-15) and then passed to the stage of extraction with tributyl phosphate in the beginning of the process, and the extract is sent to the mixing with the second part water to obtain a purified phosphoric acid. It is helpful for cleaning feeding 50-63% R2About5wet-process phosphoric acid. The mixture of the first part of the water extract is useful to volume ratio phase 1:(25-50), mixing the second part water with ex is -2000 mm/min, reextraction done in two pulsating columns with the number of theoretical steps 0.5-2 and 3-7.

The use of re-extraction of phosphoric acid from the extract with water in two stages allows you to allocate the major part of the impurities from the extract with the first flow of water, disposal of resulting contaminated phosphoric acid by mixing it with a stream of wet-process phosphoric acid applied to clean, allows to reduce the content of impurities of Fe, SB, SO4and F in the purified phosphoric acid. The use of small amounts of water in the first stage of Stripping compared with the second stage allows you to get contaminated acid in small quantities, thereby to cause a significant decrease in the concentration of the original wet-process phosphoric acid and thus does not significantly affect the production of purified phosphoric acid.

The invention relates to methods of producing phosphoric acid with a low content of impurities, used in the production of phosphate salts technical and food skills.

Wet-process phosphoric acid (EPA), sulfuric acid obtained by decomposition of natural phosphates, contains a significant amount of impurities, the removal of which use n purification method (EPA) using tributyl phosphate (TBP) (RF patent N2149830, CL 01 In 25/46, 12.10.1999), including manual extraction of the phosphoric acid tributyl phosphate at a temperature of 30-50oWith and reextraction phosphoric acid from the organic phase at a temperature of 40-80oWith that carried out by mixing the aqueous and organic phases with the formation of the emulsion and separation of the aqueous and organic phases after extraction stages and water Stripping, in which the extraction is carried out at a volume ratio of organic and aqueous phase, equal to 2.5 to 5.5:1, and the number of steps 1-6, then the resulting extract is subjected to a washing step in the mode of pulsation at a temperature of 30-60oWith production of the acid obtained in stage water Stripping and taken in quantities of 25-65% of its total mass, the formed emulsion is divided, separated leaching acid production output, and the extract is treated at the stage of Stripping water until acid production.

In the method for purification of the extract coming on stage Stripping, use purified production of phosphoric acid in the amount of 25-65% of the formulation, thus, the output of the acid with a low content of impurities is only 35-75%. During this process the values of SO4per million parts of P2O5and the solution purified acid content 147 parts Fe and 1579 parts SO4. The formation of two varieties production of acid in the production chain complicates the technological process of cleaning, complicates the sales production of the acid with a high content of impurities Fe, SO4.

Closest to the claimed method is a known method of purification of EPA (RF patent N2075436, CL 01 In 25/46, 30.09.94), including manual extraction of the phosphoric acid tributyl phosphate at a temperature of 30-50oWith and reextraction phosphoric acid from the organic phase at a temperature of 40-80oWith that carried out by mixing the aqueous and organic phases with the formation of the emulsion under the influence of air in the mode of pulsation, and the separation of the aqueous and organic phases after extraction stages and Stripping.

According to this method, the stage of Stripping is carried out in one step and get purified phosphoric acid with a content of 40% P2About5; 0,014% Fe; 0,13% SO4and 0.08% F. In the case of use for cleaning abesolutely Apatite acid composition of 52.84% P2O5, 0,28% Fe, 0,31% SO4and 0.25% F.

The degree of purification of the acid is: from Fe - 95%; F - 68%; SO4- 55,08% P2O5; Mg is 1.48%; Fe - 0,218%; SO4- 0,38%; F - 0,09% is obtained acid composition: P2O5- 41%; Fe - 0,03%; F - 0,017%; SO4is 0.025%. The degree of purification of the acid is from Mg - 93,2%; Fe - 86.2 per cent; SO4- 93,4%; F - 81,1%.

The disadvantages of this method are the relatively low degree of purification from impurity metals.

We were set a task to improve the quality of the purified phosphoric acid.

The problem is solved by the proposed method, including manual extraction of the phosphoric acid tributyl phosphate at 30-50oWith the release of raffinate and reextraction phosphoric acid from the organic phase under 40-80oWith obtaining purified phosphoric acid and the subsequent circulation of the extractant, extraction and reextraction are a mixture of aqueous and organic phases with the formation of the emulsion under the influence of air in the mode of pulsation, in which the total flow of water coming on stage Stripping, divided into two parts in the ratio V1:V2=1:(3-9), the first part of the water is mixed with the extract after separation of the phases contaminated by impurities, the aqueous phase is mixed with phosphoric acid in a volume ratio of 1:(6-15) and then passed to the stage of extraction with tributyl phosphate in the beginning of the process, and the diversified differences of the proposed method are: 1. The separation of the flow of water supplied to reextraction into two parts in the ratio V1:V2=1:(3-9), while the first part is fed to the first mixing the extract, in which the water phase is transferred to 50% of the impurities present in the extract and about 10% of the P2O5.

2. Contaminated with impurities aqueous phase formed after the first mixing the extract with water, mixed with phosphoric acid in a volume ratio of 1:(6-15) and then passed to the stage of extraction with tributyl phosphate in the beginning of the process. These proportions are not significantly reduce the concentration of the original EPA.

3. Feather from impurities extract is directed to mixing with the second, larger part of the water supplied to reextraction, forming a purified phosphoric acid, which passes about 80% R2About5from the extract.

4. Use for the purification of EPA with concentration 50-62% R2About5provides disposal of contaminated phosphoric acid in the process and reduces the impurities in the purified phosphoric acid.

For the implementation of the proposed method at the stage of extraction and re-extraction using pulse columns with the optimal number of stages of consualia to reduce the content of metal impurities in the purified acid in 2-4 times, i.e., to improve the quality of the purified acid.

Example 1 In the pulsation of the Packed column gives EPA with a mass concentration of 52.8% P2O5derived from Apatite concentrate. As impurities EPA contains, by weight. %: Fe - 0,28; SO4- 0,31; F - 0,25. In the upper part of the extraction column is fed 4902 kg/h of EPA. Phosphoric acid from EPA extracted in the mode of pulsation intensity 300 ml/min and a temperature of 40oWith tributyl phosphate at 80% and get 2942 kg/h of raffinate containing P2O5-23,88 wt.%, passed in the production of ammophos. 16233 hip hop kg/h of extract containing 14.6% of P2O5transmit to the first Stripping column, countercurrent washing serves to 590 kg/h of water. The process is conducted in the mode of pulsation when the intensity of the pulsations of 1000 mm/min, a temperature of 50oC. this forms 687 kg/h contaminated with impurities acid of the following composition, wt.%: P2About5- 37,12; Fe - 0,077; SO4- 0,29; F - 0,13; which is sent to the mixture with phosphoric acid and then in the beginning of the process to the stage of extraction.

Partially washed extract is passed into the second column reextraction where moisten countercurrent with 2433 kg/h of water in the mode of pulsation at the intensity pulsations TV, wt.%: P2O5- 39,2; Fe - 0,0049; SO4- 0,11; F - 0,07. The degree of purification of the acid is: from Fe - 98,25%, F - 72%, SO4and 64.5%.

Example 2 In the pulsation of the Packed column serves EPA with a mass concentration of 55,08% P2About5obtained from the Kovdor phosphate concentrate. As impurities EPA contains, wt%: MD - 1,48; Fe - 0,218; SO4- 0,38; F - 0,09. In the upper part of the extraction column is fed 5827 kg/h of EPA. Phosphoric acid from EPA extracted with tributyl phosphate in the mode of pulsation intensity of 300 mm/min, temperature 40oWith and get 3099 kg/h of raffinate containing P2About5-46,6 wt.%, passed in the production of ammophos. 10923 kg/h of extract containing 16,25% P2About5transmit to the first Stripping column, jet wash serves 250 kg/h of water. The process is conducted in the mode of pulsation intensity 800 mm/min in one step and at a temperature of 50oC. this forms 349 kg/h contaminated with impurities acid of the following composition, wt. %: P2O5- 43,13; Mg - 0,88; Fe - 0,19; SO4- 0,165; F - 0,037; which is sent to the mixture with phosphoric acid and then in the beginning of the process to the step of extraction with tributyl phosphate.

Partially washed extract is passed in and the intensity of the pulsations of 1200 mm/min in 6-speed and a temperature of 50oWith; and get productive purified acid number 3441 kg/h of the following composition, wt.%: P2About5- 41,0; Mg - 0,023; Fe - 0,014; SO4- 0,011; F - 0,012. The degree of purification of the acid is: Mg - 98,4%, Fe - 93,5%, F - 87%, SO4- 97%.

The calculations for the table (the table given at the end of the description).

Example 1 the Joining column acids EPA 4902 kg/h,=to 1.617 g/cm3volume 3030 l/h After extraction with TBP receive 16233 hip hop kg/h extract=1.1 g/cm3V=14756 l/h Extract was washed with 590 kg/h water in the ratio 590:14756=1:25,01.

While getting 687 kg/h contaminated acid=1,372 g/cm3V=501 l/h 501 l/h contaminated acid is mixed with 3030 l/h EPA ratio 501:3030=1:6,05.

Partially washed extract the number 16233 hip hop-(687-590)= 16136 kg/h with=1,086 g/cm3V=14845 l/h II is directed to mix with the water supplied in the number 2433 kg/h

The ratio of I part of water from part II is 590 l/h : 2433 l/h=1: 4,12. The ratio of the volume II of the water extract is 2433 l/h : 14845 l/h=1:6,1.

Example 2 In the upper part of the column serves 5827 kg/h of EPA,=1,665 g/cm3volume of 3500 l/h After extraction with TBP receive 10923 kg/h extract=1,400 g/cm3or V= 250 l/h of the Acid is mixed with a source of EPA in a ratio of 250 l/h : 3500=1:14. A mixture of I part of water extract produced at a ratio of 250 l/h : 9844 l/h=1:40.

Partially washed extract the number 10923-(349-250)= 10824 kg/h,=1,100 g/cm3V=9840 l/h is mixed with part II of the water supplied to the number 895 l/h Ratio of volumes I and II parts of water is 250 l/h : 895 l/h=1:to 3.58. The ratio of the volume II of the water extract is 895 l/h : 9840 l/h=1:10,99.

Claims

1. The method of purification of wet-process phosphoric acid comprising the step extraction of phosphoric acid tributyl phosphate at 30-50With the release of raffinate and reextraction phosphoric acid from the organic phase under 40-80With obtaining purified phosphoric acid and the subsequent circulation of the extractant, extraction and reextraction are a mixture of aqueous and organic phases with the formation of the emulsion under the influence of air in the mode of pulsation, characterized in that the total flow of water coming on stage Stripping, divided into two parts in the ratio of V1:V2=1:(3-9), the first part of the water mixed with extract lines the ratio of 1:(6-15) and then passed to the stage of extraction with tributyl phosphate in the beginning of the process, and the extract is sent to the mixing with the second part water to obtain a purified phosphoric acid.

2. The method according to p. 1, characterized in that the cleaning serves 50-63% R2O5wet-process phosphoric acid.

3. The method according to PP.1 and 2, characterized in that the mixture of the first part of the water extract is carried out at a volume ratio of phases 1:(25-50).

4. The method according to PP.1-3, characterized in that the mixture of the second part of the water extract is carried out at a volume ratio of phases 1:(5-11).

5. The method according to PP.1-4, characterized in that the extraction and reextraction lead to pulsating columns with intensity pulsations of 100-2000 mm/min

6. The method according to PP.1-5, characterized in that reextracted is carried out in two pulsating columns with the number of theoretical steps 0.5-2 and 3-7.

 

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FIELD: technology of restoration of extracting agent in the course of cleaning extraction phosphoric acid obtained by sulfuric acid decomposition of natural phosphates by means of liquid extraction with tributyl phosphate followed by separation of aqueous and organic phases and re-extraction of phosphoric acid from organic phase by means of water.

SUBSTANCE: extraction and re-extraction are performed in pulsation columns by mixing the aqueous and organic phases for forming emulsion under action of air at extraction temperature of 30-50°C and re-extraction temperature of 40-80°C during process of mixing with water and organic phases for forming emulsion under action of air in pulsation mode when part of circulating extracting agent is separated for washing with alkaline solution and water followed by returning it to extraction stage; aqueous phase which is just alkaline solution is treated with phosphoric acid at concentration of 20-54% and volume ratio of Valk. : (V1 + V2) = (0.4-2.5) : 1 at 10-60°C in two stages in succession separating the phosphoric acid flow in volume ratio of V1:V2 = 1: (0.5-13) obtaining salt solution at pH of 4-7 at 1st stage, pH of 1-3 at 2nd stage followed by separation of gummy agents at 1st stage, settling and decanting and filtration at 2nd stage.

EFFECT: reduced losses of extracting agent; enhanced purity of phosphoric acid salts.

3 cl, 1 tbl, 1 ex

FIELD: inorganic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for preparing phosphoric acid with low content of impurities and used in producing phosphate salts of technical and nutrition quality by using liquid extraction with tributyl phosphate and the following separation of an aqueous and organic phases and re-extraction of phosphoric acid from organic phase with water. Extraction and re-extraction are carried out in pulsation columns by mixing aqueous and organic phases to form emulsion under air effect at the extraction temperature 30-50°C and the re-extraction temperature 40-80°C followed by separation of the re-extraction process for some steps. At the first step the preliminary washed out extract is prepared and then it is fed to the step for preparing purified phosphoric acid and polluted acid recovered to the stage for extraction with tributyl phosphate. The total water flow feeding to the re-extraction step is divided for three parts in the following ratio: V1:(V2 + V3) = 1:(2.5-10) and (V2 : V3) = 1:(1-2.5). Extract is mixed with the first part of water and after separating phases is fed successively to mixing with other part and then with the third part of water for preparing purified and highly purified phosphoric acids. Mixing the first part of water with extract is carried out in the volume ratio of phases = 1:(20-55), and mixing the second and third part of water with extract is carried out in the ratio = 1:(5-20). Proposed method provides decreasing the content of impurities in highly purified phosphoric acid preparing at the third step of re-extraction by 2-fold, i. e. to enhance quality of acid.

EFFECT: improved treatment method of phosphoric acid.

7 cl, 2 tbl, 2 ex

FIELD: chemical industry; methods of purification of the extractive phosphoric acid.

SUBSTANCE: the invention is pertaining to the method of purification of the extractive phosphoric acid by the organic extractants and production of the phosphoric acid with the low content of impurities, that allows to use it in production of the phosphoric of the industrial and alimentary qualities. In particular, the invention is pertaining to purification of the extractive phosphoric acid containing the significant amount of ions of magnesium. The method includes extraction of the phosphoric acid by tributyl phosphate, washing of the produced extract by the phosphate solution and the subsequent reextraction with production of the reextract and after that its evaporation by the purified phosphoric acid. The extraction is conducted using 4-5 stages, and for washing they feed the phosphate solution in the amount providing the ratio P2O5:Mg in the extract equal to (5-8 : 1). As the phosphate solution of washing use either a part of the reextract, or the purified water diluted phosphoric acid. The technical result of the invention consists in purification of the phosphoric acid containing a significant amount of magnesium, at simultaneous increase of extraction of P2О5.

EFFECT: the invention ensures purification of the phosphoric acid containing a significant amount of magnesium, at simultaneous increase of extraction of P2О5.

2 cl, 1 ex

FIELD: inorganic compounds technologies.

SUBSTANCE: invention relates to purification of phosphoric acid containing considerable amount of magnesium ions, in particular phosphoric acid produced in chemicals plant "Belorechenski", with organic extractants. Specifically, phosphoric acid is extracted with tributyl phosphate by mixing organic and aqueous phases followed by further separation thereof to produce raffinate. Organic phase is re-extracted to produce purified phosphoric acid. Extraction is carried out in 4-5 steps while performing mixing in each step for 1.0-1.5 min.

EFFECT: enabled purification of phosphoric acid to low impurity level so that can be used to produce technical and food-grade phosphate salts.

1 tbl

FIELD: production of pure phosphoric acid and calcium monohydrophosphate.

SUBSTANCE: proposed method includes decomposition of phosphate ore by first hydrochloric acid solution at concentration not exceeding 10 mass-%, separation of liquid decomposition product into insoluble solid phase containing admixtures and separate aqueous phase containing phosphate, chloride and calcium ions in form of solution, neutralization of aqueous phase separated from liquid decomposition product by adding calcium compound for obtaining insoluble settled-out calcium phosphate by means of phosphate ions, separation of neutralized aqueous phase into aqueous phase containing calcium and chloride ions in form of solution and settled solid phase on base of water-insoluble calcium phosphate and dissolving of at least part of separated settled solid phase in second aqueous hydrochloric acid solution containing hydrochloric acid in the amount exceeding its content in first hydrochloric acid solution, thus forming aqueous solution containing phosphate, chloride and calcium ions extracted by organic extracting agent at extraction in "liquid-liquid" system. Proposed method makes it possible to avoid fine grinding or roasting of ore.

EFFECT: enhanced efficiency of extraction for production of pure concentrated phosphoric acid solution with no contamination of surrounding medium.

24 cl, 2 dwg, 1 tbl, 4 ex

FIELD: chemical engineering.

SUBSTANCE: method comprises sampling the extract supplied to the tower for re-extraction by water and extracting agent discharged from the re-extraction tower, cooling the samples down to 20°C, measuring density of extract and extracting agent and amount of purified acid discharged from the re-extraction tower, and calculating the extracting agent flow rate from the formula presented.

EFFECT: enhanced precision of measurements and simplified method of control.

FIELD: inorganic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for treatment of wet-process phosphorus acid from impurities. Method for treatment of wet-process phosphoric acid involves step-by-step extraction of phosphoric acid with tributyl phosphate, aqueous re-extraction of phosphoric acid from organic phase carried out in pulsation regimen, separation of aqueous and organic phases after extraction and re-extraction steps and recovery of regenerated extractant to extraction step. Step-by-step extraction is carried out for two stages. At the first stage the parent wet-process phosphoric acid and extractant containing 5-12% of phosphoric acid from the second extraction stage are fed. Process in the first stage is carried out up to extraction of 0.5-0.75 mas. p. p. of H3PO4 from the parent acid to extract that is fed to re-extraction, and raffinate obtained in this stage is fed to the second extraction stage that is carried out in the presence of sulfuric acid and in the ratio H3PO4 : H2SO4 = (1.5-10.5):1. Invention provides enhancing yield of purified acid.

EFFECT: improved method of treatment.

3 cl, 1 tbl, 6 ex

FIELD: chemical industry; food-processing industry; other industries; production of the heat-resistant alloys on the basis of the nickel.

SUBSTANCE: the invention is pertaining to the method of purification of the extracting phosphoric acid (EPA) with production of the product having the low content of the impurities, which may be used in production of the phosphorus salts of technical and alimentary qualification. The method of purification of the extracting phosphoric acid provides for extraction of the phosphoric acid by the tributyl phosphate with the withdrawal of the raffinate, water flushing of the extract with withdrawal of the water flushing solution and the flushed extract, the water reextraction pf the phosphoric acid from the flushed extract with obtaining of the productional acid, which are exercised by commixing of the water and organic phases with formation of the emulsion in the mode of pulsation. The water flushing of the extract is conducted by means of dispergation of the water in the organic phase at the consumption of the dispergated water of 0.04-0.25 t per 1 t of Р2О5 in the original extract and intensity of the pulsation equal to 1200-3000 mm/minute. The flushing solution is routed for extraction, where it is either admixed with the extracting phosphoric acid before treatment with the extragent, or it is introduced directly into the mixture of the acid and the extragent containing in the aqueous phase , 35-42 % of Р2О5. The water flushing of the extract is conducted in 1-4 stages. The method ensures the substantial improvement of the water flushing column performance standards, reduction of the losses of the expensive extragent and the metal consumption of the production process, stabilization of the process of the water flushing of the extract, and also the increased outlet of the productional extracting phosphoric acid.

EFFECT: the invention ensures the substantial improvement of the water flushing column performance standards, reduction of the expensive extragent losses and the metal consumption, stabilization of the process of the water flushing of the extract, the increased outlet of the productional extracting phosphoric acid.

3 cl, 1 tbl, 5 ex

FIELD: inorganic substances technologies.

SUBSTANCE: invention relates to technology of restoring extractant in the purification process of extraction phosphoric acid obtained via sulfuric acid decomposition of naturally occurring phosphates utilizing liquid extraction with tributyl phosphate. Extractant is purified by washing it with water at volume ratio (1-2):1, respectively, and temperature 20 to 55°C in one-two steps followed by transferring water phase into phosphoric acid purification process and transferring extractant to vacuum distillation stage carried out at 140-200°C and pressure 5-20 mm Hg. Resulting distillate is recycled to phosphoric acid purification process and bottom residue is otherwise utilized or sent to secondary vacuum distillation.

EFFECT: increased extractant purification degree, reduced number of process stages, and accelerated washing operation.

3 cl, 1 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: extracting agent is sampled prior to and after regeneration, diluted with tributyl phosphate and evaluated within photometric measurements at equal wavelength within the range 195-440 nanometres. The obtained data are applied to calculate purification efficiency of extracting agent considering optical densities and dilution ratio of samples within photometric measurements. Offered method enables to monitor purification efficiency of extracting agent during regeneration cycle within wide range from few percents up to 99 and more percents and to compare purification efficiency when applying various regeneration methods. Monitor duration is not more than 10 minutes.

EFFECT: elimination of necessity for calibration diagram construction.

3 cl, 1 tbl, 1 ex

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