WO2024047228A1 - Réactifs et procédés d'élimination de métaux lourds de solutions d'acide phosphorique - Google Patents

Réactifs et procédés d'élimination de métaux lourds de solutions d'acide phosphorique Download PDF

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WO2024047228A1
WO2024047228A1 PCT/EP2023/074029 EP2023074029W WO2024047228A1 WO 2024047228 A1 WO2024047228 A1 WO 2024047228A1 EP 2023074029 W EP2023074029 W EP 2023074029W WO 2024047228 A1 WO2024047228 A1 WO 2024047228A1
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process according
heavy metal
phosphoric acid
acid
dimercapto
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PCT/EP2023/074029
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English (en)
Inventor
Lei Zhang
Ravi Rajshekar HIREMATH
Kewei Wang
Kenan TOKMIC
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Cytec Industries Inc.
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Publication of WO2024047228A1 publication Critical patent/WO2024047228A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/18—Phosphoric acid
    • C01B25/22—Preparation by reacting phosphate-containing material with an acid, e.g. wet process
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
    • B01J20/045—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium containing sulfur, e.g. sulfates, thiosulfates, gypsum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28016—Particle form
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/18—Phosphoric acid
    • C01B25/234—Purification; Stabilisation; Concentration
    • C01B25/237—Selective elimination of impurities
    • C01B25/238—Cationic impurities, e.g. arsenic compounds

Definitions

  • the present invention generally relates to purification in industrial process streams. More particularly, the present invention relates to removing heavy metal ions from phosphoric acid process streams.
  • phosphoric acid is produced according to the wet process, which is conventionally prepared by acidulating phosphate rock (which contains calcium phosphate) with sulfuric acid to yield a crude wet-process phosphoric acid (WPA) and insoluble calcium sulfate (gypsum).
  • WPA wet-process phosphoric acid
  • gypsum insoluble calcium sulfate
  • the filtered crude WPA is then sent to clarifiers and evaporators for further purification and concentration.
  • the purified phosphoric acid is either sent out as Merchant Grade Acid (MGA) or continued to make 69 % P2O5 Super Phosphoric Acid (SPA), where it can be converted to many end products ranging from a chemical reagent, rust inhibitor, food additive, dental and orthopedic etchant, electrolyte, flux, dispersing agent, industrial etchant, fertilizer feedstock, and component of home cleaning products.
  • MGA Merchant Grade Acid
  • SPA Super Phosphoric Acid
  • crude phosphoric acid is concentrated to 54 % (P2O5) before sent for Monoammonium Phosphate (MAP), Diammonium Phosphate (DAP), or ammonium phosphate-sulfate (APS) production.
  • MAP Monoammonium Phosphate
  • DAP Diammonium Phosphate
  • APS ammonium phosphate-sulfate
  • metal impurities in the form of heavy metal ions such as cadmium, copper, arsenic, lead, and mercury, are present as minerals in the phosphate rock and are dissolved into the phosphoric acid.
  • the metal impurities are considered unacceptable above a certain level, depending on the application of the phosphoric acid, because of their toxicity. Accordingly, the metal impurities have to be either completely removed or their levels have to be significantly reduced.
  • Cd cadmium
  • Phosphate fertilizers have been identified as an important source that introduces Cd to the soil, which can be easily absorbed by agricultural plants and accumulated into the food chain (“Cadmium in phosphate fertilizers; ecological and economical aspects”, CHEMIK 2014, 68, 10, 837-842).
  • Cd in phosphate fertilizer comes from phosphoric acid, the major raw material used to produce phosphate fertilizer. In fact, the majority of phosphoric acid production is used to produce fertilizer. Cd in phosphoric acid further stems from the phosphate bearing ores. Therefore, Cd can be removed either from the phosphate ore or from the phosphoric acid stream, with the latter being the focus of research in the past decades.
  • U.S. Patent No. 4,378,340 (1983) discloses a method of removing heavy metals, particularly cadmium, from wet process phosphoric acid through partial neutralization of acids with alkali, followed by precipitation with sulfide compounds.
  • U.S. Patent No. 5,431,895 (1995) also discloses using alkali solution and aqueous sulfide solution simultaneously with thorough mixing to remove lead and cadmium from phosphoric acid.
  • U.S. Patent No. 4,986,970 (1991) discloses using metal salt of dithio carbonic acid-O-esters to precipitate the heavy metals, especially cadmium, from partially neutralized (pH 1.4-2) and pre-cooled (5-40 °C) phosphoric acid. Afterwards, the complexes can be separated from the acid using methods like flotation or filtration.
  • EP0333489 Bl (1989) disclose methods of separating heavy metals, especially cadmium, mercury, and lead, from phosphoric acid using a diorganyldithiophosphoric acid ester and an adsorbent, a diorganyldithiophosphorus compound and an adsorbent, a diorganyldithiophosphoric acid ester and an adsorbent and a reductant, and a thioorganophosphine reagent and a reducing agent, respectively.
  • 2004/0179984 also discloses methods of removing heavy metals from wet process phosphoric acid by adding a mixture reagents of diorgano dithiophosphinic acid (or alkali metal or ammonia salts thereof), a first dithiophosphoric acid (or alkali metal or ammonia salts thereof) with alkyl or alkylaryl or aralkyl moieties, and optionally a second diaryl dithiophosphoric acid (or alkali metal or ammonia salts thereof).
  • compositions and methods presently available for heavy metal removal from phosphoric acid in the production process require further improvement. Since many factors (e.g., ore type, temperature, agitation, reactor design, acid chemistry, foreign ions, organic species, and viscosity of phosphoric acid medium) can affect the performance of reagents, it is a great challenge to develop high-efficiency reagents useful for removing heavy metals from phosphoric acid. Successful reagents for removing heavy metals in industrial process streams such as wet process phosphoric acid would be a useful advance in the art and could find rapid acceptance in the industry.
  • heavy metal chelating agents comprising a plurality of sulfur groups are effective in reagents useful for removing heavy metal ions from aqueous solutions containing phosphoric acid.
  • heavy metal chelating agents can include 2,5-Dimercapto-l,3,4-thiadiazole, 2,3-Dimercapto-l-propanol, a thiocontaining polymer, derivatives thereof, and mixtures thereof. Accordingly, the processes for removing heavy metal ions according to various embodiments of the present invention as described herein are applicable for use with the various stages of wet process phosphoric acid production.
  • processes for removing heavy metal ions from a solution containing phosphoric acid by adding an effective amount of a reagent including a heavy metal chelating agent comprising plurality of sulfur groups to the solution to form heavy metal precipitates and/or complexes and separating the heavy metal precipitates and/or complexes from the solution.
  • the process can further include adding an effective amount of organothiophosphorus compounds to the solution containing phosphoric acid.
  • FIG. 1 is a graph illustrating the results of Examples 1A & 1 J- 1 to 1 J-5, showing the percentage of As removed from the plant weak phosphoric acid at ⁇ 75 °C with dosages of heavy metal chelating agent 2,3 -dimercapto- 1 -proanol (“DTG”) at 0 to 4 kg/T P2O5 level;
  • TSG heavy metal chelating agent 2,3 -dimercapto- 1 -proanol
  • FIG. 2 is a graph illustrating the results of Examples 1C-1, IK-1, IK-3, IK-4 & IK-5, showing the percentage of Cd removed from the plant weak phosphoric acid at ⁇ 75 °C with dosages of heavy metal chelating agent DTG at 0 to 4 kg/T P2O5 level and a subsequent dosage of sodium diisobutyl dithiophosphinate (“Na- DTPi”) at 0.5 kg/T P2O5 level;
  • FIG. 3 is a graph illustrating the results of Examples 2A & 2B-1 to 2B-4, showing the percentage of heavy metal removed from the digestion slurry of phosphoric acid at ⁇ 80 °C with dosages of heavy metal chelating agent 2,5-dimercapto-l,3,4- thiadiazole dipotassium salt (“DMTD-2K”) at 0 to 9 kg/T P2O5 level;
  • FIG. 4 is a graph illustrating the results of Examples 3A & 3B-1 to 3B-4, showing the percentage of heavy metal removed from the concentrated plant phosphoric acid at ⁇ 70 °C with dosages of heavy metal chelating agent DMTD-2K at 0 to 4 kg/T P2O5 level;
  • FIG. 5 is a graph illustrating the results of Examples 3E-1, 3C-2, & 3F-1, showing the percentage of Cd removed from the concentrated plant phosphoric acid at ⁇ 70 °C with various dosages of heavy metal chelating agent DTG and Na-DTPi; and FIG.
  • FIG. 6 is a graph illustrating the results of Examples 4A & 4B-1 to 4B-4, showing the percentage of heavy metal removed from the concentrated plant phosphoric acid at ⁇ 70 °C with dosages of heavy metal chelating agent comprising polyamine/alkyl glycidyl ether/(glycidyloxypropy)trimethoxysilane/(mercaptopropyl)trimethoxysilane (“Pl”) at 0 to 10 kg/T P2O5 level.
  • heavy metal chelating agent comprising polyamine/alkyl glycidyl ether/(glycidyloxypropy)trimethoxysilane/(mercaptopropyl)trimethoxysilane (“Pl”) at 0 to 10 kg/T P2O5 level.
  • the present invention generally relates to purification of solutions in industrial process streams. More particularly, the inventors describe herein for the first time processes for removing and/or recovering heavy metal ions from solutions containing phosphoric acid by adding an effective amount of a reagent comprising a heavy metal chelating agent having a plurality of sulfur groups to the solution.
  • compositions and processes described herein provide improvement and/or an unexpected advantage when compared to the prior art processes and compositions.
  • the following terms are provided to assist the reader. Unless otherwise defined, all terms of art, notations and other scientific or industrial terms or terminology used herein are intended to have the meanings commonly understood by those of skill in the chemical and/or phosphoric acid production arts. In some cases, terms with commonly understood meanings are defined herein for clarity and/or for ready reference, and the inclusion of such definitions herein should not necessarily be construed to represent a substantial difference over the definition of the term as generally understood in the art unless otherwise indicated. As used herein and in the appended claims, the singular forms include plural referents unless the context clearly dictates otherwise. Throughout this specification, the terms retain their definitions.
  • heavy metal or “metal” shall refer to those elements of the periodic table having a density of more than 5 g/cm 3 and an oxidation state higher than 0, (i.e., heavy metal ions).
  • heavy metal ions include, for example, one or more of copper (Cu), cadmium (Cd), nickel (Ni), mercury (Hg), zinc (Zn), arsenic (As), manganese (Mn) and lead (Pb).
  • cadmium ions and arsenic ions can be removed from solutions containing phosphoric acid.
  • heavy metal chelating agent generally refers to any such compound that interacts, reacts, or binds with heavy metal ions to form a “heavy metal complex”.
  • Heavy metal chelating agents as described herein include a plurality of sulfur groups. More preferred heavy metal chelating agents according to the invention are described herein.
  • Heavy metal complexes can be solid, waxy, or oily in the phosphoric acid solutions. They can precipitate, float, or suspend in the phosphoric acid solutions.
  • phosphoric acid solutions or “solutions containing phosphoric acid,” in the context of the invention includes any aqueous acidic solution or mixture containing crude phosphoric acid, digestion slurries, filtered acid, and/or concentrated acid.
  • Effective amount means the dosage of any of the reagents disclosed herein on an active basis necessary to provide the desired performance in the phosphoric acid system or circuit being treated (such as the formation of heavy metal complexes) when compared to an untreated control system or system using a reagent product of the prior art.
  • hydrocarbyl is a generic term encompassing aliphatic, alicyclic and aromatic groups having an all-carbon backbone and consisting of carbon and hydrogen atoms.
  • one or more of the carbon atoms making up the carbon backbone may be replaced or interrupted by a specified atom or group of atoms, such as by one or more heteroatom of N, O, and/or S.
  • hydrocarbyl groups include alkyl, cycloalkyl, cycloalkenyl, carbocyclic aryl, alkenyl, alkynyl, alkylcycloalkyl, cycloalkylalkyl, cycloalkenylalkyl, and carbocyclic aralkyl, aralkenyl and aralkynyl groups.
  • Recitation or discussion of such hydrocarbyl groups includes their substituted or unsubstituted forms. This concept is sometimes phrased as “optionally substituted.” When substituted, it can be by one or more substituents as defined herein elsewhere.
  • the examples and preferences expressed below also apply to each of the hydrocarbyl substituent groups or hydrocarbyl-containing substituent groups referred to in the various definitions of substituents for compounds of the formulas described herein unless the context indicates otherwise.
  • Preferred non-aromatic hydrocarbyl groups are saturated groups such as alkyl and cycloalkyl groups.
  • the hydrocarbyl groups can have up to fifty carbon atoms, unless the context requires otherwise.
  • Hydrocarbyl groups with from 1 to 30 carbon atoms are preferred.
  • C1-20 hydrocarbyl groups such as C1-12 hydrocarbyl groups (e.g., C1-6 hydrocarbyl groups or Ci-4 hydrocarbyl groups), specific examples being any individual value or combination of values selected from Ci through C30 hydrocarbyl groups.
  • alkyl is intended to include linear, branched, or cyclic hydrocarbon structures and combinations thereof. Preferred alkyl groups are those of C30 or below. Lower alkyl refers to alkyl groups of from 1 to 8 carbon atoms. Examples of lower alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, s- and t-butyl, pentyl, hexyl, octyl and the like. Cycloalkyl is a subset of alkyl and includes cyclic hydrocarbon groups having from 3 to 30 carbon atoms, preferably from 3 to 8 carbon atoms as well as polycyclic hydrocarbons having 7 to 10 carbon atoms.
  • aryl refers to cyclic (mono or multi-cyclic), aromatic hydrocarbons that do not contain heteroatoms in the ring portion.
  • aryl groups contain from 6 to 14 carbons in the ring portions of the groups.
  • aryl groups include, but are not limited to, phenyl, azulenyl, heptalenyl, biphenyl, indacenyl, fluorenyl, phenanthrenyl, triphenylenyl, pyrenyl, naphthacenyl, chrysenyl, biphenylenyl, anthracenyl, and naphthyl groups.
  • Aryl groups can be unsubstituted or substituted, as defined herein.
  • Representative substituted aryl groups can be mono- substituted or substituted more than once, such as, but not limited to, 2-, 3-, 4-, 5-, or 6-substituted phenyl or 2-8 substituted naphthyl groups, which can be substituted with carbon or non-carbon groups such as those known to persons of skill in the art.
  • Aryl groups of C6-C12 are preferred.
  • aralkyl as used herein is a broad term and is used in its ordinary sense, including, without limitation, to refer to an alkyl having at least one alkyl hydrogen atom replaced with an aryl moiety, such as benzyl, -CH l or 2-naphthyl), - (CH2)2phenyl, -(CH2)3phenyl, -CH(phenyl)2, and the like. Particularly preferred are C7-20 aralkyl groups. In any or all embodiments, one or both alkyl and aryl may be optionally substituted with one or more ubstituents as described herein elsewhere.
  • Substituted hydrocarbyl groups e.g., alkyl, aryl, aralkyl, cycloalkyl, alkoxy, etc., refer to the specific substituent wherein up to three H atoms in each residue are replaced with alkyl, halogen, haloalkyl, hydroxy, alkoxy, carboxy, carboalkoxy (also referred to as alkoxycarbonyl), carboxamido (also referred to as alkylaminocarbonyl), cyano, carbonyl, nitro, amino, alkylamino, dialkylamino, mercapto, alkylthio, sulfoxide, sulfone, acylamino, amidino, phenyl, benzyl, halobenzyl, heteroaryl, phenoxy, benzyloxy, heteroaryloxy, benzoyl, halobenzoyl, or lower alkylhydroxy.
  • the term “about” or “approximately” means an acceptable error for a particular value as determined by one of ordinary skill in the art, which depends in part on how the value is measured or determined. In certain embodiments, the term “about” or “approximately” means within 1, 2, 3, or 4 standard deviations. In any or all embodiments, the term “about” or “approximately” means within 50%, 30%, 25%, 20%, 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, or 0.05% of a given value or range.
  • a heavy metal chelating agent having a plurality of sulfur groups refers to a compound that performs as a chelator of heavy metals and has two or more sulfur groups.
  • sulfur groups or “sulfur group” as used herein can refer to thiols, thiolates, or sulfur atoms present in a ring system of a compound as hetero atoms.
  • an element, component, or feature is said to be included in and/or selected from a list of recited elements, components, or features
  • the element, component, or feature can also be any one of the individual recited elements, components, or features, or can also be selected from a group consisting of any two or more of the explicitly listed elements, components, or features. Additionally, any element, component, or feature recited in such a list may also be omitted from such list.
  • any recitation herein of a numerical range by endpoints includes all numbers subsumed within the recited range (including fractions), whether explicitly recited or not, as well as the endpoints of the range and equivalents.
  • the term “et seq.” is sometimes used to denote the numbers subsumed within the recited range without explicitly reciting all the numbers, and should be considered a full disclosure of all the numbers in the range. Disclosure of a narrower range or more specific group in addition to a broader range or larger group is not a disclaimer of the broader range or larger group.
  • certain heavy metal chelating agents comprising plurality of sulfur groups are effective in reagents useful for removing heavy metal ions from aqueous solutions containing phosphoric acid.
  • 2,5-Dimercapto-l,3,4-thiadiazole; 2,3- Dimercapto-1 -propanol; thio-containing polymers; derivatives thereof, and mixtures thereof can be used in reagents useful for removing heavy metal ions from aqueous solutions containing phosphoric acid.
  • heavy metal chelating agents having a plurality of sulfur groups can be used with a surfactant.
  • a surfactant can be added with 2,5-Dimercapto-l,3,4-thiadiazole; 2, 3 -Dimercapto- 1 -propanol, a thio- containing polymer; derivatives thereof, and mixtures thereof.
  • the surfactant compound can be selected from the group consisting of sulfosuccinates; aryl sulfonates; alkarylsulfonates; diphenyl sulfonates; olefin sulfonates; sulfonates of ethoxylated alcohols; petroleum sulfonates; sulfosuccinamates; alkoxylated surfactants; ester/amide surfactants; EO/PO block copolymers; and mixtures thereof.
  • the surfactant can be a sulfosuccinate.
  • the sulfosuccinate can be sodium dioctylsulfosuccinate.
  • Suitable sodium dioctylsulfosuccinate compounds include, but are not limited to, AEROSOL® OT-70 and DHAYSULF® 70B available from Solvay S.A.
  • Suitable alkoxylated surfactants can include, but are not limited to, polyethyleneglycol sorbitan monooleate (such as TWEEN® 80 available from Croda), and polyethyleneglycol sorbitol hexaoleate (such as ATLAS® G1086 available from Croda).
  • 2,5-Dimercapto-l,3,4-thiadiazole, 2,3- Dimercapto-1 -propanol, a thio-containing polymer, derivatives thereof, and mixtures thereof can be added to either the crude acid or digestion slurries prior to gypsum filtration, or to the filtered acid or the concentrated acid to complex the heavy metals. Afterwards, heavy metal complexes can be separated from the acid or slurry. In any or all embodiments, the methods of separation include, but are not limited to, filtration, centrifugation, sedimentation, creaming, flocculation, adsorption, and/or flotation.
  • 2,5-Dimercapto-l,3,4-thiadiazole, 2,3- Dimercapto-1 -propanol, a thio-containing polymer, derivatives thereof; and mixtures thereof can be added to the solution containing phosphoric acid all in one stage or added in several stages.
  • 2,5- Dimercapto-l,3,4-thiadiazole, 2,3 -Dimercapto- 1 -propanol, a thio-containing polymer, derivatives thereof; and mixtures thereof can be added as a blend, or separately in any order such as concurrently together or sequentially.
  • Treatment times in various embodiments can be from a few seconds (z.e., 5 to 10 seconds) to 24 hours. In those instances where the reagent complexes the heavy metals very rapidly, the preferred treatment times are from about 5 seconds to 3 hours. Most typically, the treatment times are from 10 seconds to 60 seconds or 120 seconds.
  • the dosage of the reagent for complexing heavy metals and removal efficiency for the various heavy metals will depend on the amount of heavy metal impurities present in the ore and/or solution containing phosphoric acid. Generally, the greater number of heavy metals present and the higher their concentrations, the greater will be the overall dosage of the reagent. Those skilled in the art will be able to readily determine and establish the optimum dosage of 2,5-Dimercapto- 1,3,4-thiadiazole, 2,3-Dimercapto-l-propanol, a thio-containing polymer, derivatives thereof; and mixtures thereof required using no more than routine experimentation. Generally, the dosages may be in the range of from 0.01 to 50 kg (e.g..).
  • the dosages can be from 0.1 kg to 10 kg (e.g., 0.10, 0.15, 0.20, 0.25, 0.30, et seq.
  • any of the recited dosages can also be recited as “less than” a particular dosage, e.g., less than 50 kg; or that any of the recited dosages (except the highest dosage point) can also be recited as “greater than” a particular dosage, e.g., greater than 0.10 kg.
  • the ratio of heavy metal chelating agents comprising a plurality of sulfur groups to surfactant is, in some embodiments, from 1 to 2 to 100 to 1. In some embodiments where surfactant is added, the ratio of heavy metal chelating agents comprising a plurality of sulfur groups to surfactant is from 2: 1 to 50: 1.
  • the solution containing phosphoric acid has a P2O5 concentration from 1 wt. % to 70 wt. %. In some embodiments, the solution containing phosphoric acid has a P2O5 concentration from 20 wt. % to 70 wt. %. Specific concentrations of P2O5 contemplated for use with the invention include 24 wt. %, 25 wt. %, 26 wt.%, 28 wt. %, 30 wt. %, 42 wt. %, 48 wt. %, 52 wt. %, 56 wt. %, 60 wt. % and 69 wt. %.
  • compositions and processes described herewith as the present invention can be used over a wide temperature range.
  • the processes according to the invention can be performed at a temperature from 0 °C to 120 °C.
  • the temperature is in the range from 10 °C to 80 °C.
  • the process can further include adding an effective amount of a reducing agent and/or an adsorbent agent to the solution containing phosphoric acid. Such agents are known to be useful in the field.
  • one or both of these agents can enhance the activity of the reagent comprising heavy metal chelating agents comprising a plurality of sulfur groups in reagents useful for removing heavy metal ions from aqueous solutions containing phosphoric acid as described herein.
  • one or both of these agents can enhance the activity of reagents including 2,5-Dimercapto-l,3,4-thiadiazole, 2,3 -Dimercapto- 1 -propanol, a thio-containing polymer, derivatives thereof; and mixtures.
  • the reducing and/or adsorbent agent can be added to the solution containing phosphoric acid all in one stage or added in several stages.
  • the reducing and/or adsorbent agent can be added together as a blend with the reagent comprising heavy metal chelating agents comprising plurality of sulfur groups in reagents useful for removing heavy metal ions from aqueous solutions containing phosphoric acid as described herein.
  • the reducing and/or adsorbent agent can be added together as a blend with the reagent including 2,5-Dimercapto-l,3,4-thiadiazole, 2,3- Dimercapto-1 -propanol, a thio-containing polymer, derivatives thereof; and mixtures, or separately in any order with 2,5-Dimercapto-l,3,4-thiadiazole, 2,3- Dimercapto-1 -propanol, a thio-containing polymer, derivatives thereof; and mixtures such as concurrently together or sequentially.
  • Reducing agents useful in any or all processes according to the invention include, but are not limited to, iron powder, zinc, red phosphorus, iron (II) sulfate, sodium hypophosphite, hydrazine, hydroxymethane sulfonate, and mixtures thereof.
  • the reducing agent includes sodium hypophosphite.
  • the reducing agent is used in an amount from 0.01 kg to 50 kg of reagent per ton of P2O5, based on the type and quantity of the oxidants in the phosphoric acid solution, which can be readily determined by those skilled in the art using no more than routine methods.
  • the amount of reducing agent is from 0.1 kg to 5 kg of reagent per ton of P2O5 of the phosphoric acid solution.
  • Adsorbent agents useful in any or all embodiments according to the invention include all those substances that are capable of adsorbing at their surface a sufficiently large quantity of the chelation products of heavy metal ions with 2,5- Dimercapto-l,3,4-thiadiazole, 2,3-Dimercapto-l-propanol, a thio-containing polymer, derivatives thereof, and mixtures.
  • Such compounds include, but are not limited to, active charcoal/carbon, carbon black, ground lignite, adsorbents containing silicate (e.g., synthetic silicic acids, zeolites, calcium silicate, bentonite, perlite, diatomaceous earth, and fluorosilicate), calcium sulfate (including gypsum, hemihydrate, and anhydride), and mixtures thereof.
  • silicate e.g., synthetic silicic acids, zeolites, calcium silicate, bentonite, perlite, diatomaceous earth, and fluorosilicate
  • calcium sulfate including gypsum, hemihydrate, and anhydride
  • the adsorbent is present in an amount from 0.05 wt. % to 50 wt. %, and preferably from 0.1 wt. % to 5 wt. %, based on the quantity of phosphoric acid in the solution.
  • a process for removing heavy metal ions from a phosphoric acid mixture comprising adding to the phosphoric acid mixture an effective amount of a reagent comprising a heavy metal chelating agent comprising a plurality of sulfur groups.
  • the phosphoric acid mixture is a solution.
  • the phosphoric acid mixture is a slurry.
  • the heavy metal the heavy metal ion can be selected from the group consisting of cadmium, copper, arsenic, mercury, lead, and mixtures of any of the foregoing.
  • the heavy metal ion is cadmium.
  • the heavy metal ion is arsenic.
  • the heavy metal chelating agent having a plurality of sulfur groups is selected from a compound according to Formulas 1(A) or 1(B): and salts thereof, wherein each M and M’ of Formula 1(A) or 1(B) is independently chosen from H, Na, K, Li, NFL, NR’ 4, wherein each R’ is independently chosen from a C1-C4 alkyl group; and R of Formula 1(B) is chosen from a Ci-Cis alkyl group; C6-C12 aryl group; or a C7-C18 aralkyl group.
  • the compound according to Formulas 1(A) or 1(B) is selected from the group consisting of 2,5-dimercapto- 1,3,4-thiadiazole; 2,5-dimercapto-l,3,4-thiadizaole dipotassium salt; 5-mercapto- 3-phenyl-l,3,4-thiodiazole-2(3H)-thione potassium salt; and mixtures thereof.
  • the heavy metal chelating agent having a plurality of sulfur groups is selected from the group consisting of: 2, 3 -dimercapto- 1 -propanol; 1,2- dithioethane; 1,3 -dithiopropane; benzene- 1,2-dithiol; l,3-dimercapto-2-propanol; 1,2,3-tri-mercaptopropane; and mixtures thereof.
  • the heavy metal chelating agent is 2, 3 -dimercapto- 1 -propanol.
  • the heavy metal chelating agent having a plurality of sulfur groups is a polymer according to wherein each M is independently chosen from H, Na, K, Li, NFL and NR’ 4, each
  • R’ is independently chosen from a C1-C4 alkyl group, and n is the number of repeating units of the polymer backbone, and is an integer from 2 to 1000. In some embodiments, n is 2 to 100.
  • the polymer backbone comprises a backbone selected from the group consisting of: polyamine, polysaccharide, polyvinylpyrrolidone, polyglutamicacid, polyacrylamide, polydiacetone acrylamide, polyvinyl alcohol, polyethylene glycol, polyacrylic acid, chitosan, dextrin and mixtures of any of the foregoing; and co-polymers of any of the foregoing.
  • a process for removing heavy metal ions from a phosphoric acid mixture comprising adding to the phosphoric acid mixture an effective amount of a reagent comprising a heavy metal chelating agent comprising a plurality of sulfur groups as substituents wherein the reagent further comprises an effective amount of an organothiophosphorus compound.
  • the organothiophosphorus compound is selected from the group consisting of: organodithiophosphinic acid, organodithiophosphonic acid, organodithiophosphoric acid, organomonothiophosphinic acid, organomonothiophosphonic acid, organomonothiophosphoric acid, their corresponding salts in the form of sodium, ammonium, or potassium, and mixtures thereof.
  • the organothiophosphorus compound comprises organodithiophosphinic acid or corresponding salts thereof; or organodithiophosphoric acid or corresponding salts thereof.
  • the organodithiophosphinic acid is a dialkyldithiophosphinic acid
  • the organodithiophosphoric acid is a dialkyldithiophosphoric acid.
  • the phosphoric acid mixture further comprises an adsorbent.
  • the adsorbent is calcium sulfate solid particles.
  • the process is performed at a temperature from 0 °C to 120 °C. In some embodiments, the process is performed at a temperature from about 10 °C to about 80 °C.
  • the phosphoric acid mixture has a concentration of P2O5 from 3 weight % to 70 weight %, based on the total weight of the mixture. In some embodiments, the phosphoric acid mixture has a concentration of P2O5 from 20 weight % to 60 weight %. In some embodiments of the process for removing heavy metal ions from a phosphoric acid mixture disclosed herein, the reagent comprising a heavy metal chelating agent comprising a plurality of sulfur groups is added to the phosphoric acid mixture at a dosage from 0.1 kg/ton and 10 kg/ton of P2O5.
  • the process further comprises a step of separating the phosphoric acid mixture.
  • the separating step further comprises flocculation.
  • the separating step further comprises filtration.
  • the separating step further comprises skimming.
  • a reagent for removing heavy metal ions from a phosphoric acid mixture comprising (a) a heavy metal chelating agent comprising a plurality of sulfur groups and (b) an organothiophosphorus compound comprising an organodithiophosphinic acid or corresponding salts thereof; or organodithiophosphoric acid or corresponding salts thereof.
  • the heavy metal chelating agent having a plurality of sulfur groups is selected from the group consisting of (i) 2,5-dimercapto-l,3,4- thiadiazole; 2,5-dimercapto-l,3,4-thiadiazole dipotassium salt; and 5-mercapto-3- phenyl-l,3,4-thiodiazole-2(3H)-thione potassium salt; (ii) 2, 3 -dimercapto- 1- propanol; 1,2-dithioethane; 1,3 -dithiopropane; benzene- 1,2-dithiol; 1,3- dimercapto-2-propanol; and 1,2,3-tri-mercaptopropane.
  • the heavy metal chelating agent having a plurality of sulfur groups is a polymer as defined by wherein each M is independently chosen from H, Na, K, Li, NH4 and NR’ 4, each R’ is independently chosen from a C1-C4 alkyl group, and n is the number of repeating units of the polymer backbone, and is an integer from 2 to 1000. In some embodiments, n is 2 to 100.
  • the polymer comprises a backbone selected from the group consisting of: polyamine, polysaccharide, polyvinylpyrrolidone, polyglutamicacid, polyacrylamide, polydiacetone acrylamide, polyvinyl alcohol, polyethylene glycol, polyacrylic acid, chitosan, dextrin and mixtures of any of the foregoing; and co-polymers of any of the foregoing.
  • the reagent comprises mixtures of any of the foregoing heavy metal chelating agent comprising a plurality of sulfur groups as substituents.
  • the heavy metal chelating agent is 2,3 -dimercapto- 1 -propanol.
  • a reagent for removing heavy metal ions from a phosphoric acid mixture comprising
  • a heavy metal chelating agent comprising a plurality of sulfur groups which comprises a member selected from the group consisting of:
  • a polymer as defined by the heavy metal chelating agent having a plurality of sulfur groups is a polymer as defined by wherein each M is independently chosen from H, Na, K, Li, NH4 and NR’ 4, each R’ is independently chosen from a C1-C4 alkyl group, and n is the number of repeating units of the polymer backbone, and is an integer from 2 to 1000, and wherein in some embodiments, n is 2 to 100, and in some embodiments, the polymer comprises a backbone selected from the group consisting of: polyamine, polysaccharide, polyvinylpyrrolidone, polyglutamicacid, polyacrylamide, polydiacetone acrylamide, polyvinyl alcohol, polyethylene glycol, polyacrylic acid, chitosan, dextrin and mixtures of any of the foregoing; and co-polymers of any of the foregoing; and
  • an organothiophosphorus compound comprising an organodithiophosphinic acid or corresponding salts thereof; or organodithiophosphoric acid or corresponding salts thereof.
  • the heavy metal chelating agent is 2,3 -dimercapto- 1- propanol.
  • the phosphoric acids with different P2O5 levels are obtained from plants.
  • the phosphoric acid slurries are generated with a bench-scale digestion process.
  • To separate the heavy metal precipitates from the acid either a syringe filter or a vacuum filtration is used. Afterwards, the filtrate acids are analyzed with ICP (Inductively Coupled Plasma) to determine the level of various heavy metal elements.
  • ICP Inductively Coupled Plasma
  • DMTD-2K (2,5-Dimercapto-l,3,4-thiadiazole dipotassium salt), DMTD (2,5- Dimercapto-l,3,4-thiadiazole), Bismuthiol II (5-Mercapto-3-phenyl-l,3,4- thiodiazole-2(3H)-thione potassium salt), 2-Aminothiophenol, and Trimercapto- s-triazine trisodium salt are purchased from Sigma Aldrich.
  • DTG (2,3- Dimercapto-1 -propanol) is purchased from Sigma Aldrich.
  • Na-DTPi sodium diisobutyl dithiophosphinate
  • Na-DTP sodium diisobutyl dithiophosphate
  • 2-Aminothiophenol is dosed directly into acid without dilution.
  • DTG is dosed into phosphoric acid/slurry as-is.
  • Solutions of other reagents are prepared first before being dosed into phosphoric acid/slurry.
  • a 10 wt% solution of DMTD-2K in water is prepared before dosed into acid.
  • a 10 wt% solution of Bismuthiol II in water is prepared before dosed into acid.
  • a 10 wt% solution of DMTD in basic sodium hydroxide solution is prepared before dosed into acid.
  • a 10 wt% solution of Trimercapto-s-triazine trisodium salt in water is prepared before dosed into acid.
  • a 5 wt% solution of sodium diisobutyl dithiophosphinate in water is prepared before dosed into acid.
  • a 5 wt% solution of sodium diisobutyl dithiophosphate in water is prepared before dosed into acid.
  • a solution of 6% DMTD-2K and 2% Na-DTPi is prepared before dosed into acid. The dosages shown in the tables are calculated based on the amount of dry reagents relative to the amount of P2O5 in acid/slurry.
  • Example 1 Process for removing heavy metals from plant weak phosphoric acids ( ⁇ 30 % at elevated temperature (75°C and 50°C)
  • results from Table 1 show the performance of various reagents for heavy metal removal from various plant phosphoric acids at variant temperatures.
  • DMTD-2K compound when dosed at 3kg/t P2O5 to the plant phosphoric acid #2 (30% P2O5) at 50 °C, was able to remove arsenic and cadmium by up to 75.0% and 93.7% respectively (Example IN).
  • DMTD and Bismuthiol II were also able to remove a significant amount of arsenic and cadmium from the plant phosphoric acid.
  • DTG compound more than 90% reduction in arsenic was observed at dosages of 2 kg/t P2O5 (Example 1 J-4).
  • Example 2 Process for removing heavy metals from digestion phosphoric acid slurries ( ⁇ 30 % P2O5) at ⁇ 80°C). Calcium sulfate solid particles in the slurry act as adsorbents
  • Phosphoric acid slurries are generated via bench-scale digestion of phosphate ore by using a 500 ml jacketed reactor connected with a thermal bath for keeping temperature at around 80 °C. The reactor is also connected to a cooling condenser to avoid water evaporation during the digestion. Phosphoric acid and sulfuric acid are added continuously to the reactor through two peristaltic pumps (MasterFlex L/S). Phosphate rock/ore powder is manually added roughly continuously at a corresponding rate. The feed rate of sulfuric acid (52.4%) is 3.67 g/minute; feed rate of phosphoric acid (37.1%) is 7.67 g/minute; and phosphate ore powder is 2 g/minutes. The feeding time is around 30 minutes.
  • the digestion is continued for an additional 2 to 3 hours to fully digest the phosphate ores.
  • reagents of interest and other additives such as defoamer reagents
  • effective amounts of reagents are first mixed with the aforementioned phosphoric acid and then continuously pumped into the reactor.
  • the digestion slurry is stirred with an overhead stirrer (Glas-Col Precision Speed Controlled Stirrer) and a propeller-type impeller set at 300 rpm.
  • phosphoric acid slurry ( ⁇ 30 % solid level, ⁇ 30 % P2O5) post-digestion is transferred into a glass jar with a magnetic stir bar.
  • the slurries contain a large amount ( ⁇ 30 wt. %) of solid particles, with the majority being calcium sulfate generated during the digestion of phosphate ore.
  • An effective amount (as listed in Table 2) of a reagent of interest for heavy metal ions removal is dosed into the slurry under agitation at 600 rpm.
  • the 1st reagent is dosed into slurry under agitation of 600 rpm and agitated for 1 minute, and then the 2nd reagent is dosed into acid under agitation of 600 rpm and agitated for 1 minute.
  • the slurry is transferred to a vacuum filtration funnel (on a filtration setup with a 45 pm polypropylene net filter (Millipore PP4504700)) and the vacuum filtration starts in ⁇ 15 seconds. The filtrate is collected and then submitted for ICP elemental analysis.
  • Results from Table 2 show that DMTD-2K, by itself or with Na-DTPi, effectively removes arsenic and cadmium from the plant phosphoric acid (30% P2O5). The performance improves with increase in the dosage of DMTD-2K.
  • Example 3 Process for removing heavy metals from concentrated phosphoric acids ( ⁇ 50 % P2O5) at elevated temperature (70°C) or room temperature (20°C)
  • Results shown in Table 3 indicate significant reduction (over 80%) in the arsenic and cadmium from concentrated plant phosphoric acid (50% P2O5) when treated with DMTD-2K (Examples 3B-3 and 3B-4). Similar performance for As removal was observed when the concentrated plant phosphoric acid was treated with DTG (Example 3E-3). In both cases, the performance improved when the dosage of these compounds was increased. Great performance were also observed when DMTD-2K or DTG is co-dosed with Na-DTPi at various sequences.
  • Example 4 Process for removing arsenic from concentrated phosphoric acids ( ⁇ 46 % P2O5) at elevated temperature (70°C) using thiol-containing polymers
  • Polyethylenimine (Epomin SP-018, 0.35g, 0.0002 mol) and Cs-Cio alkyl glycidyl ether (GE-7, 0.18 g, 0.0008 mol) are added to a flask, and stirred at 80 °C for 1 h.
  • Deionized water (2.63 g) and 10% NaOH solution (0.65 g) are added to the flask to form a clear solution, followed by the addition of (3-glycidyloxypropyl)trimethoxysilane (GPTS, 0.19 g, 0.0008 mol).
  • Polyethylenimine (Epomin SP-018, 0.68 g, 0.0004 mol) and Cs-Cio alkyl glycidyl ether (GE-7, 0.36 g, 0.0016 mol) are added to a flask, and stirred at 80 °C for 1 h.
  • Deionized water (7.69 g) and 10% NaOH solution (0.51 g) are added to the flask to form a clear solution, followed by the addition of (3-glycidyloxypropyl)trimethoxysilane (GPTS, 0.75 g, 0.0032 mol).
  • Synthesis of thiol-containing polymer P6 Tetraethylenepentamine (0.58g, 0.0031 mol) and Cs-Cio alkyl glycidyl ether (GE-7, 0.69 g, 0.0031 mol) are added to a flask, and stirred at 80 °C for 1 h.
  • Deionized water (7.51 g) and 50% NaOH solution (0.49 g) are added to the flask to form a clear solution, followed by the addition of (3-glycidyloxypropyl)trimethoxysilane (GPTS, 0.72 g, 0.0031 mol).
  • Table 5 he results in Table 5 show that the thiol-containing polymers and neat MPTS can effectively remove the arsenic content in the plant phosphoric acid ( ⁇ 46 % P2O5).
  • Example 5 Process for removing heavy metals from plant phosphoric acids ( ⁇ 30 % at elevated temperature (75°C)

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  • Inorganic Chemistry (AREA)
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Abstract

L'invention concerne des procédés d'élimination d'ions de métaux lourds dans des mélanges d'acide phosphorique par ajout d'une quantité efficace de réactifs comprenant une pluralité de groupes de soufre au mélange d'acide phosphorique pour former des complexes de métaux lourds, et séparation des complexes de métaux lourds de la solution.
PCT/EP2023/074029 2022-09-02 2023-09-01 Réactifs et procédés d'élimination de métaux lourds de solutions d'acide phosphorique WO2024047228A1 (fr)

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