WO2009113088A2 - Procédé de fabrication de fluorure de potassium - Google Patents

Procédé de fabrication de fluorure de potassium Download PDF

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Publication number
WO2009113088A2
WO2009113088A2 PCT/IN2009/000030 IN2009000030W WO2009113088A2 WO 2009113088 A2 WO2009113088 A2 WO 2009113088A2 IN 2009000030 W IN2009000030 W IN 2009000030W WO 2009113088 A2 WO2009113088 A2 WO 2009113088A2
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WO
WIPO (PCT)
Prior art keywords
potassium
process step
silica
fluoride
potassium fluoride
Prior art date
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Ceased
Application number
PCT/IN2009/000030
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English (en)
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WO2009113088A3 (fr
Inventor
Sanjaya Ranjana Mohapatra
Rahul Jadhav.
Mandal Sisir
Narendrasingh Patil
Ravi Kelkar
Prashant Mickey Puri
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Aditya Birla Science and Technology Co Ltd
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Aditya Birla Science and Technology Co Ltd
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Publication date
Application filed by Aditya Birla Science and Technology Co Ltd filed Critical Aditya Birla Science and Technology Co Ltd
Publication of WO2009113088A2 publication Critical patent/WO2009113088A2/fr
Anticipated expiration legal-status Critical
Publication of WO2009113088A3 publication Critical patent/WO2009113088A3/fr
Ceased legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/02—Fluorides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/01—Chlorine; Hydrogen chloride

Definitions

  • This invention relates to a process of manufacturing of Potassium Fluoride.
  • Potassium fluoride [7789-23-3] is a chemical compound with the formula
  • KF is an alkali metal halide and occurs naturally as the rare mineral carobbiite.
  • Potassium fluoride is the preferred source of fluorine in the conversion of chlorocarbons to fluorocarbons.
  • potassium hydroxide is reacted with hydrofluoric acid and the resulting salt can then be purified by recrystallization.
  • potassium metal is reacted vigorously with a halogen to form potassium halide.
  • GB1419393 and US3842161 disclose a method for preparation of metal fluoride which comprises two stages. In the first stage, KOH solution is treated with solid potassium silico fluoride at molar ratio less than 4 to form potassium fluoride solution and then separating off the silica. In the second stage, the remaining KOH is reacted with potassium silica fluoride. The silica is separated by filtration and potassium fluoride solution is recovered as a product.
  • the method suffers from many disadvantages like high silica content, contamination with heavy metals because of alkaline pH, involves many stages of reaction and separation.
  • It is an object of the present invention is to provide a process for preparation of potassium fluoride having low silica content and heavy metals.
  • Another object of the present invention is to provide a cost-effective and economically feasible process for preparation of potassium fluoride.
  • Yet another object of the invention is to provide a process for preparation of potassium fluoride by cheaply available raw materials.
  • Yet another object of the invention is to provide a process for preparation of potassium fluoride in high yield and high purity.
  • Still another object of this invention is to provide a process for preparation of potassium fluoride which reduces the wastage of toxic byproducts.
  • a process for manufacturing high purity potassium fluoride comprising the following steps: a. reacting a by product of the fertilizer industry predominantly containing hydrofluorosilicic acid with a suspension containing potassium chloride, potassium fluoride and silica cake to obtain a first resultant mass containing potassium silicofluoride and hydrochloric acid; b. cooling the first resultant mass to room temperature; c. filtering the first resultant mass to obtain a first residue containing potassium silicofluoride; d. washing the first residue with water to obtain a washed mass predominantly containing potassium silicofluoride; e.
  • the reactants have the following relationship a. for 2 moles of KCl at least 1 mole of hydrofluorosilicic acid is added; and b. for each 6 moles of KF present along with KCl at least 2 moles of hydrofluorosilicic acid are added along with about 1 mole of silica.
  • the concentration of hydrofluorosilicic acid is in the range of 5% to 25 % in the process step (a).
  • the process step (a) is carried out at 40-100 C for 40-45 minutes.
  • the potassium chloride in the process step (a) is a by-product of organic fluorination reaction.
  • the potassium chloride is present in the range of 0% to 100% along with potassium fluoride and with or without organic impurities.
  • the suspension of potassium chloride is added as a slurry or solid form to the hydrofluorosilicic acid in the process step (a).
  • the first resultant mass is filtered to remove hydrochloric acid in the process step (c).
  • the potassium silicofluoride is dried in an oven to remove moisture in the process step (d).
  • the potassium silicofluoride is obtained as a white solid powder having purity more than 99% in the process step (d).
  • the molar ratio of potassium hydroxide to potassium silicofluoride is in the range of 3.5: 1 to 4.1 : 1 in the process step (f).
  • the potassium hydroxide is used as a solid or as an aqueous solution in the process step (f).
  • the potassium hydroxide is added slowly over a period of 5 min. to 300 min. in the process step (f).
  • the concentration of potassium silicofluoride in aqueous slurry is in the range of 5 to 50 % in the process step (f).
  • the process step (g) is carried out at 5 to 105 0 C for 40-45 minutes.
  • the insoluble silica is washed with water to remove potassium fluoride or unreacted potassium hydroxide present with silica in the process step (g).
  • the silica is obtained as a silica cake having 40% moisture content in the process step (g).
  • the silica cake is dried at 110 0 C for 4 hrs. to obtain dry silica in the process step (g).
  • the dry silica is used to prepare potassium silicofluoride.
  • the washing solution is used to prepare slurry of potassium fluorosilicate or potassium hydroxide in the process step (g).
  • the process step (h) is carried out at 20-100 0 C for 10 to 120 minutes.
  • the third resultant mass is filtered out and the third residue obtained in the process step (i) can be reused.
  • the solid potassium fluoride is obtained by heating the second filtrate to remove water in the process step (j).
  • the solid potassium fluoride is obtained by air drying the filtrate in the process step (J).
  • Figure 1 illustrates the X-Ray powder diffractogram of potassium silicofluoride (K 2 SiF 6 );
  • Figure 2 illustrates the X-ray Powder diffractogram of organic fluorination by-product KCl-KF mixture
  • FIG 3 illustrates the X-ray Powder diffractogram of Potassium fluoride (KF)
  • FIG. 4 shows a flowchart of the process for preparation of Potassium fluoride in accordance with the invention.
  • Potassium fluoride is an alkali metal halide occurs naturally as the rare mineral carobbiite. Potassium fluoride is the preferred source of fluorine in the conversion of chlorocarbons to fluorocarbons.
  • the conventional methods for manufacturing potassium fluoride suffers from many disadvantages like use of expensive raw materials, low productivity and involves many reaction steps. Accordingly, the present invention provides an effective process for manufacturing of potassium fluoride, a source of fluorine for organic fluorinations in high yield and purity. A process in accordance with the present invention is also a cost-effective process over the other conventional methods used for manufacturing of potassium fluoride.
  • Hydrofluorosilicic acid which is a raw material useful for producing potassium fluoride, is a by-product produced in large amount in the manufacture of well known phosphate fertilizers.
  • Rock phosphate is a raw material used in the manufacture of most commercial phosphate fertilizers.
  • Rock phosphate containing fluorides such as calcium fluoride and silica as impurity and mineral phosphates having 5% to 10% calcium fluoride is treated with previously diluted sulphuric acid. This reaction converts the tertiary calcium phosphate into primary phosphate rendering it soluble in water and liberates the fluorine of the calcium fluoride, forming hydrofluoric acid.
  • This acid in turn combines with the silica forming silicon tetrafluoride, a gas, escapes into the air and is detrimental to surroundings.
  • the gas is then sprayed with water in condensing towers into a series of scrubbers and dissolved in water and this decomposes the silicon tetrafluoride into Hydrofluorosilicic acid and silicic acid .
  • This is the crude form of fluorosilicic acid.
  • the purified form is obtained by distillation of the crude acid.
  • the hydrofluorosilicic acid can also be prepared by the reaction of hexafluorosilicate, apatite and/or fluorite (fluorspar) with sulphuric acid.
  • the source of fluoride ion which is an alkali metal fluoride (normally potassium fluoride) and solvent are charged in the reactor.
  • the heat is applied to dry the system by distilling out any water with some of the solvent.
  • the substrate which is usually aryl chloride and phase transfer catalyst are then fed into the reactor.
  • the reaction is carried out at the predetermined temperature for the required time to yield potassium salts like potassium chloride and potassium fluoride as a residue with any involatile organic byproducts.
  • This halogen exchange is usually referred as a Halex fluorination.
  • the by-product of the organic fluorination reactions can also be utilized for the preparation of potassium fluoride in a cost-effective manner.
  • a process for manufacturing high purity potassium fluoride comprises the following steps.
  • a by product of the fertilizer industry predominantly containing hydrofluorosilicic acid having concentration in the range of 5% to 25% by mass is heated to a temperature of 95-98 C in a vessel and is reacted with a suspension containing potassium chloride (a by-product of organic fluorination reaction containing (potassium fluoride 10%, potassium chloride (in slurry form or in solid form) 89.5% and other impurities 0.5%) and silica cake (having 40% moisture).
  • the reaction is continued for 40-45 min. at 40-100 0 C to obtain a first resultant mass containing insoluble potassium silicofluoride and hydrochloric acid.
  • the reactants have the following relationship for 2 moles of KCl at least 1 mole of hydrofluorosilicic acid is added and for each 6 moles of KF present along with KCl at least 2 moles of hydrofluorosilicic acid are added along with about 1 mole of silica.
  • the first resultant mass is cooled to room temperature and then filtered to obtain a first residue containing potassium silicofluoride.
  • the first residue is washed with water to obtain a washed mass containing potassium silicofluoride and to remove hydrochloric acid.
  • the product is then dried inside oven at 130 C for 3 hrs. to obtain a white solid powder of Potassium fluorosilicate free from moisture having more than 99% purity and isolated product yield.
  • the resultant Potassium fluorosilicate and water are added to the pp conical flask and the aqueous slurry is heated to 88 to 92 0 C. Then the 45% KOH solution is added slowly over a period ranging from 5 min. to 300 min. More preferably, the KOH solution is added within 20 min. The reaction is continued for 40-45 min. at 88 to 92 0 C to obtain a second resultant mass predominantly containing potassium fluoride in solution and silica as residue.
  • the potassium silicofluoride is employed as aqueous slurry having concentration in the range of 5% to 50%.
  • the potassium hydroxide is used as a solid or as an aqueous solution.
  • the molar ratio of potassium hydroxide to potassium silicofluoride is in the range of 3.5:2 to 4.1 : 1.
  • the second resultant mass is then cooled to room temperature and then it is filtered to obtain a first filtrate predominantly containing potassium fluoride, unreacted potassium hydroxide, soluble silica and a second residue containing insoluble silica.
  • the insoluble silica is removed.
  • This silica cake residue having 40% moisture is washed with water to remove any potassium fluoride and un-reacted potassium hydroxide.
  • the washing solution is reused to prepare slurry of potassium silicofluoride or potassium hydroxide in the next reaction.
  • the pH of the first filtrate is more than 8 (generally 10) is adjusted to 6.5 - 7.5 using 48% aqueous solution of hydrogen fluoride or hydrofluorosilicic acid.
  • the reaction mixture is heated for 10-120 min. at a temperature of 10 to 120 min. and then cooled at room temperature to obtain a third resultant mass.
  • the third resultant mass is then filtered to obtain a second filtrate containing potassium fluoride and a third residue containing potassium silicofluoride and fluorosilicates of heavy metals.
  • the residue containing potassium fluorosilicate, fluorosilicates and other heavy metals is filtered out.
  • the residue is reused for next batch.
  • the second filtrate (potassium fluoride solution) is obtained having about 29% (by wt.) of potassium fluoride. Solid potassium fluoride having purity in the range of 99% to 99.9% is obtained by removing water by heating.
  • the solid potassium fluoride is obtained by air drying the second filtrate.
  • the reaction mixture was cooled to room temperature and then filtered.
  • the product was isolated and washed with 1.5 ltr water to remove any solubles including hydrochloric acid generated in the reaction.
  • the resultant product was dried inside oven at 13O 0 C for 3 hrs to obtain 482.7 gm of white solid powder of Potassium fluorosilicate.
  • the product has more than 99 % purity and more than 99 % isolated product yield.
  • Example 2 Preparation of Potassium Fluoride 66.67 gm of wet cake of Potassium Fluorosilicate (having moisture content 40%) and 58.33 gm of water were added to 500 ml poly propylene conical flask equipped with overhead stirrer. Then, the mixture was heated to 92 0 C and 85.2 gm of potassium hydroxide solution (45%) was added slowly within 20 minutes. Mole ratio of potassium hydroxide to Potassium silico fluoride was 3.76: 1. The reaction was continued for 40 minute at 92 0 C. The reaction mixture was cooled to room temperature (25 deg C) and stirred for another 30 minutes and then filtered.
  • the reaction was carried out for different reaction mole ratio of potassium hydroxide: Potassium silico fluoride following the same process as described in Example 2, wherein 66.67 gm of wet cake of Potassium Fluorosilicate (moisture: 40%) and 58.33 gm of water added to 500 ml poly propylene conical flask equipped with overhead stirrer. Reaction was carried out with different amount of 45% potassium hydroxide solution.
  • Example- 1 45% solution of potassium hydroxide was reacted with potassium silicofluoride slurry and in Example-4, potassium hydroxide pellets were added to the potassium silicofluoride slurry within 10 minutes. It was found that upon fast addition of potassium hydroxide into the reaction mass, the lumps were formed making the stirring difficult. Thus, slow addition of potassium hydroxide either as a solution or as a solid form was found to be desirable.
  • the process as described herein above offers several advancement over processes disclosed in the prior art in terms of yield, purity, cost- effectiveness and the recoverability of almost all the reagents. Furthermore, the process uses toxic waste materials from fertilizer industry and organic fluorination reaction for effective manufacture of potassium fluoride in high purity (more than 99%) and high yield which could have wasted otherwise which in turn saves the natural resources and reduces the environmental pollution.
  • the process in accordance with the present invention results into potassium fluoride having low silica content and heavy metals.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Fertilizers (AREA)
  • Silicon Compounds (AREA)

Abstract

La présente invention a trait à un procédé de fabrication de fluorure de potassium d’une grande pureté. Un dérivé de l’industrie des engrais contenant principalement de l’acide silicofluorhydrique est utilisé en tant que matière première. Le fluorure de potassium solide tel qu’il est obtenu par le procédé selon la présente invention a une pureté allant de 99 % à 99,99 %.
PCT/IN2009/000030 2008-01-14 2009-01-09 Procédé de fabrication de fluorure de potassium Ceased WO2009113088A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IN94/MUM/2008 2008-01-14
IN94MU2008 2008-01-14

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WO2009113088A2 true WO2009113088A2 (fr) 2009-09-17
WO2009113088A3 WO2009113088A3 (fr) 2010-11-25

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102887531A (zh) * 2012-10-15 2013-01-23 张军航 一种使用氟硅酸钾生产氟化钾的工艺
CN104591224A (zh) * 2015-02-02 2015-05-06 嘉应学院 生产高锰酸钠废渣的处理方法
CN104591223A (zh) * 2015-02-02 2015-05-06 嘉应学院 一种氟硅酸盐废渣的处理方法
CN112174168A (zh) * 2020-10-21 2021-01-05 承德莹科精细化工股份有限公司 一种利用钾水玻璃与氟硅酸或氟硅酸钾反应制备高纯氟化钾的方法
CN114180600A (zh) * 2022-01-04 2022-03-15 江苏中旗科技股份有限公司 一种三元或四元混合钾盐的分离方法

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JPH0656421A (ja) * 1992-06-23 1994-03-01 Dowelanco カリウムおよびセシウムフツ化物の製造
US6551417B1 (en) * 2000-09-20 2003-04-22 Ge Betz, Inc. Tri-cation zinc phosphate conversion coating and process of making the same
CN101134581A (zh) * 2006-09-01 2008-03-05 多氟多化工股份有限公司 一种氟化钠的制备方法
CN101134563A (zh) * 2006-09-01 2008-03-05 多氟多化工股份有限公司 一种生产氢氟酸、无水硫酸镁、氟化钠的方法
CN101134580A (zh) * 2006-09-01 2008-03-05 多氟多化工股份有限公司 氟化钾的生产方法
RU2327634C1 (ru) * 2007-03-06 2008-06-27 Открытое акционерное общество "Научно-исследовательский институт по удобрениям и инсектофунгицидам им.Я.В.Самойлова" Способ концентрирования экстракционной фосфорной кислоты с одновременным получением кремнефтористоводородной кислоты

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102887531A (zh) * 2012-10-15 2013-01-23 张军航 一种使用氟硅酸钾生产氟化钾的工艺
CN104591224A (zh) * 2015-02-02 2015-05-06 嘉应学院 生产高锰酸钠废渣的处理方法
CN104591223A (zh) * 2015-02-02 2015-05-06 嘉应学院 一种氟硅酸盐废渣的处理方法
CN112174168A (zh) * 2020-10-21 2021-01-05 承德莹科精细化工股份有限公司 一种利用钾水玻璃与氟硅酸或氟硅酸钾反应制备高纯氟化钾的方法
CN114180600A (zh) * 2022-01-04 2022-03-15 江苏中旗科技股份有限公司 一种三元或四元混合钾盐的分离方法
CN114180600B (zh) * 2022-01-04 2024-04-30 江苏中旗科技股份有限公司 一种三元或四元混合钾盐的分离方法

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Publication number Publication date
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