EP0648198A1 - Verfahren zum modifizieren körniger feststoffe und so hergestellte feststoffpartikeln - Google Patents

Verfahren zum modifizieren körniger feststoffe und so hergestellte feststoffpartikeln

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Publication number
EP0648198A1
EP0648198A1 EP93914848A EP93914848A EP0648198A1 EP 0648198 A1 EP0648198 A1 EP 0648198A1 EP 93914848 A EP93914848 A EP 93914848A EP 93914848 A EP93914848 A EP 93914848A EP 0648198 A1 EP0648198 A1 EP 0648198A1
Authority
EP
European Patent Office
Prior art keywords
salt
reaction product
water soluble
particulate solid
water
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP93914848A
Other languages
English (en)
French (fr)
Inventor
Aharon Meir Eyal
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Yissum Research Development Co of Hebrew University of Jerusalem
Original Assignee
Yissum Research Development Co of Hebrew University of Jerusalem
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Yissum Research Development Co of Hebrew University of Jerusalem filed Critical Yissum Research Development Co of Hebrew University of Jerusalem
Publication of EP0648198A1 publication Critical patent/EP0648198A1/de
Ceased legal-status Critical Current

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Classifications

    • 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
    • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
    • B01J2/006—Coating of the granules without description of the process or the device by which the granules are obtained
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
    • C05G5/00—Fertilisers characterised by their form
    • C05G5/30—Layered or coated, e.g. dust-preventing coatings

Definitions

  • the present invention relates to water soluble inorganic salts having substantially water insoluble coatings and to processes for the preparation thereof. More particularly the present invention relates to the water soluble fertilizers provided with substantially water insoluble coatings for slow/sustained release thereof.
  • Water soluble salts are of extensive use in aqueous solutions. Especially salts selected from the group consisting of halides, nitrates, phosphates and sulfates are of extensive use in the fertilizer industry. Such salts often contain cations of Li, Na, Mg and Ca and preferably contain cations which also serve as nutrients and micronutrients e.g., K, NH., Fe, Mn, Cu, Co, Mo and Zn. In certain cases, however, slow release of the salt into the aqueous solution is required. An important example is slow release fertilizers. Use of slow release fertilizers instead of direct application of the fertilizer as a soluble salt provides many advantages such as: increased efficiency, reduced number of applications, reduced soil toxicity, reduced nutrient losses and thereby lower contamination of underground water.
  • SUBSTITUTESHEET Tne first aoproacn involves the preparation of low solubility compounds sucn as: urea formaldehyde (Hasegawa and Onishi, JP63, 134,593, Stajer, Glaser, Vidensky and Vosolsobe (CS 2588147), syngemte (Von Maessennausen, Czikkely and Jung, DE 3,518,369) ana magnesium ammonium phosonate (JP 82 67,089); or water soluble salts granulated, pressed or sintered with other compounds such as gypsum (Koike JP 61,295,294), coal (Fujimori BR 88 03,282), coal ash (Oshikata, JP 60,239,381) and silicates (JP 59 04,397).
  • the main disadvantage of low-solubility compounds or formulations is the high cost of raw materials and/or manufacturing.
  • Coatings of soluble salts comprise polymers (Hansen, L'S 3,223,518, Showa, JP 60,103,093; U.S. 3,223,518), sulfur, wax ( ⁇ ibner, DE 3,321,053), pitch (Zou, CM 1,030,745), soybean formulation (NL 34 03,505), salts of fatty acids (Pipko, Manor and Ziv, EP 276,179), sodium silicate (Ko ⁇ ssarov and Panfileva SU 1,353,767), iron phospnate (Eibner DE 3,321,053), magnesium ammonium phosphate (Ninon JP 81,164,090) and gypsum or cement (JP 59,50,086).
  • SUBSTITUTESHEET With this state of the art in mind, it is an object c: the present invention to provide a process for modifying a particulate solid comprising a water soluble inorganic salt, said salt being selected from the group consisting of halides, nitrates, phosphates and sulfates, so as to decrease the rate of dissolution of such salts in water.
  • the surface of the water soluble, inorganic salt particles can be converted through reaction with suitable reagents into a water insoluble coating thereby decreasing the dissolution of the water soluble salt. It was surprisingly found that such coating can be formed even when the reagent is applied in aqueous solution.
  • the present invention provides a process for modifying a particulate solid comprising a water soluble inorganic salt, said salt being selected from the group consisting of halides, nitrates, phosphates and sulfates, so as to decrease the rate of dissolution of said salt in aqueous solution, said process comprising contacting said salt with at least one reagent which reacts with one or more ions of
  • SUBSTITUTESHEET said salt to form a reaction product which coats said salt, said reaction product containing at least one ion of said water soluble inorganic salt as a component thereof and having a water solubility not more than half that of the original uncoated organic salt.
  • particulate solids as used herein concerns particulate solids that range from soluble salts only to compositions that contain at least one water soluble salt as one constituent amongst others that may be water soluble or water insoluble.
  • particulate table salt consisting of 100% sodium chloride is included in the present invention as is a particulate dry soup containing about 10% sodium chloride.
  • particulate solid for the purposes of the present invention, several fertilizer materials are listed below. These were chosen since controlling the rate of dissolution of particulate fertilizer is a major, though by no means exclusive, object of this invention.
  • a) muriate of potash which is over 95% KC1 and the remainder of which is mainly NaCl, both of which are fully water soluble: b) granulated "triple super phosphate" which is made fr om phosphate rock and wet process acid and contains soluble monocalci urn phospnate as the main constituent and may contain some 20% of insoluble solids originating in the rock (silica, iron oxide%) and in clay used as a binder for the granulation process; c) granulated NPK made of ammonium phosphate, muriate of potash arid phosphate rock, which may contain over 50% of the water insoluble rock.
  • the water soluble salts present in the particulate solids to which this invention refers are halides, sul ⁇ fates, nitrates and phosphates. Naturally, when anions of these salts report to an aqueous solution an equivalent amount of cations do so.
  • said reagent can react with either said anion or its companion cation.
  • a process for modifying a particulate solid comprising a water soluble inorganic salt, so as to decrease the rate of dissolution of said salt in aqueous solution, said salt being selected from the group consisting of halides, nitrates, phosphates and sulfates and optionally including cations of K, MH ⁇ , re, Mn, Cu, Co, Mo and Zn, said process comprising contacting said salt with at least
  • SUBSTITUTESHEET one reagent whic. reacts with one or more ions of said salt to form a reaction product which coats said salt, sai ⁇ reaction product containing at least one of said ions as a component thereof and having a water solubility not more tnan half that of the original uncoated organic salt.
  • a process for modifying a particulate solid comprising a water soluble inorganic salt, said process comprising contacting particles of said particulate solid with at least one reagent which reacts with one or more ions of said salt to form a reaction product which coats said particles.
  • the invention also provides a particulate solid comprising a water soluble inorganic salt, said salt being selected from the group consisting of halioes, nitrates, phosphates ana sulfates, and sai ⁇ salt having a substantially water insoluble coating, said coating having been formed by contacting said salt with at least one reagent which reacts with one or more ions of said water soluble salt to form a reaction product which coats said salt, said reaction product containing at least one ion of said water soluble organic salt as a component thereof and having a water solubility not more than half that of the original uncoated organic salt.
  • a water soluble inorganic salt said salt being selected from the group consisting of halioes, nitrates, phosphates ana sulfates, and sai ⁇ salt having a substantially water insoluble coating, said coating having been formed by contacting said salt with at least one reagent which reacts with one or more ions of said water
  • the invention provides a particulate solid comprising a water soluole inorganic salt, sai ⁇ salt
  • SUBSTITUTESHEET being selected from the group consisting of halides, nitrates, phosphates and sulfates, and optionally including cations of K, NH., Fe, Mn, Cu, Co, Mo and Zn, said salt having a substantially water insoluble coating, said coating having been formed by contacting said salt with at least one reagent which reacts with one or more of said ions to form a reaction product which coats said salt, said reaction product containing at least one of said ions as a component thereof and having a water solubility not more than half that of the original uncoated organic salt.
  • the invention also provides a particulate solid according to the present invention comprising a water soluble inorganic salt wherein particles of said particulate solid are provided with a substantially water insoluble coating, said coating on said particles having been formed by contacting said salt with at least one reagent which reacts with one or more of said ions to form a reaction product which coats said particles, said reaction product containing at least one of said ions as a component thereof and having a water solubility not more than half that of the original uncoated organic salt.
  • said reaction product has a water solubility less than 10% of that of the original uncoated water soluble inorganic salt.
  • the reagent is applied in a combination with at least one of the group comprising surfactants, viscosity, modifiers, water-repellants and binders, to improve mechanical strength, adhesivity to the particle and to further reduce solubility in water.
  • SUBSTITUTESHEET One example is treatment by a surface active agent (which is arice to the reagent or applied at a subsequent stage).
  • a surface active agent which is arice to the reagent or applied at a subsequent stage.
  • Such agent might be selected, for example, from those used for anticaking of crystals or for flotation (e.g. amines).
  • the polar side of the surface active agent (surfactant) interacts with the reaction product in the particulate cover, while the hydrophobic end decreases interaction with water and thereby affects solubility.
  • This hydrophobic end also provides for further coating of the particle by hydrophobic solvents as hydrocarbons.
  • Other treatments may include thermal treatment for affecting the coating's characteristics (e.g., converting gypsum dihydrate to hemi-hydrate), a second treatment by the same reagent or treatment by a second reagent (e.g., treatment by a base to convert CaHPO, in the coating to the less soluble Ca,(P0.) ? ), etc.
  • tne aDove method suffers from tne disadvantages that it requires the introduction ana use cf bctn an organic acid or salt and a metal oxide or caroonate to interreact with each otner to form a coating around the fertilizer particles as opposed to tne present invention in which water soluble fertilizer particles tnemselves actively interact with the reagent and ions of said water soluble fertilizer form an integral component of the formed water insoluble coating.
  • tne present invention assures that the reaction to form the water insoluble coating takes place on the surface of the water soluble salt, since in the present invention this salt functions as one of the reactants, which is not the case with said prior art process. This further assures that loss of reagent due to precipi ⁇ tation away from the surface of the salt does not take place.
  • the fertilizer to be coated according to the present invention may be selected from the well known water scluole fertilizers such as: potassium nitrate, ootassiu- sulfate, ammonium nitrate. monopotassium pnosohate, ammonium ohosonates, mixtures of N. P.K. fertilizers, etc.
  • water scluole fertilizers such as: potassium nitrate, ootassiu- sulfate, ammonium nitrate. monopotassium pnosohate, ammonium ohosonates, mixtures of N. P.K. fertilizers, etc.
  • SUBSTITUTESHEET The main nutrients providec tnrougn fertilizers are N, ? ano K.
  • Micro-nutrients consist of Fe, Mn, Cu, Co, Mo, In, etc. N is provi ⁇ ed as ammonium salts (e.g., (NH birthdayS0 ⁇ ), NO.*,- salts (e.g., Ca(N0-.) 2 , NaNC,) and urea. is provided in its soluble salts such as KC1 ana KoSO. and P as pnosonates.
  • ammonium salts e.g., (NH birthdayS0 ⁇ )
  • NO.* - salts
  • urea is provided in its soluble salts such as KC1 ana KoSO. and P as pnosonates.
  • fertilizers m whicn both the amon and the cations comprise a nutrient, e.g. KNO, ( H 4 ) 2 HP
  • Reagents forming water insoluble salts with the anion or the cation of the water soluble salts are suitable for tne process.
  • the surface cf tne particle is converted according to the reaction: K-.SO4 ⁇ * rUSiF, > K 2 SiF 6 + H 2 S0 4 .
  • the modified particle thus comprises K ⁇ SO. coated with K ⁇ S F ⁇ - with substantially no decrease of nutrient content.
  • nutrient replacement is low and the replaced nutrient can oe recovered as in the reaction: 2 S0 4 + Ca(N0 3 ) 2 > CaS0 4 ⁇ « ⁇ KN0 3 .
  • the reagent can be chosen to also add micro-nutrients to tne fertilizer.
  • micro-nutrients e.g, ZnCHN. ⁇ SO. ) 2 or cobalt ammonium nitrate are suitable insoluble coatings of ammonium salts.
  • preferred embodiments of the present invention will include the nutrients N, P or K as a component of the reaction product and especially preferred embodiments of the present invention will also incorporate one or more micronutrients selected from Fe, Mn, Cu, Co, Mo and Zn in said coating.
  • Reagents for the process are those forming water insoluble salts with at least one of the ions comprising the fertilizer.
  • K salts can be coated with K 2 Ca(S0 4 ) 2 , K 3 Co(N0 2 )g and K 2 SlF g ;
  • NH 4 + salts form insoluble coatings such as H 4 CaP0 4 , NH 4 CoP0 4 - H 4 gP0 4 and H 4 MnP0 4 ;
  • soluble calcium phosphates or Ca(NC ) can be coated with insoluble salts such as CaCO ⁇ , CaF-, Ca laurate, Ca oxalate, Ca 3 (P0 4 ) 2 and Ca tartarate;
  • water soluble phosphate can be coated with water insoluble phosphates such as FeP0 4 and water soluble sulfates with water
  • reagents may be applied in vapor phase (NH 3 , SiF ⁇ ), in non-aqueous liquid, as a dispersion, emulsion or even in aqueous solution.
  • the reagent may also be sprayed over the solid particles.
  • the rate of release of the water soluble salt is dependent on coating thickness, which can be affected by parameters of reagent application.
  • the rate of release is also affected by solubility of the coating wherein less soluble coatings provides for slower release.
  • Particles coated in the process of this invention can be further coated by other coating materials such as wax.
  • SUBSTITUTESHEET Modified particulate solids obtained according to the invention having a low rate of dissolution in aqueous solutions, provide excellent starting material for additional treatments for further improvement of their properties, i.e., improvement of mechanical strength, further reduction of rate of dissolution, etc.
  • Such additional treatment may, for example, use components such as surfactants, binders and polymeric materials dissolved or dispersed in aqueous solution.
  • Such option is, in fact, impractical with unmodified water-soluble particulate solids, as it would lead to the dissolution of a major part of the unmodified particulate.
  • the reaction product of low water solubility that coats the soluble salt in the modified particulate solid may, in some cases, perform as a low-cost filler in other coatings formed cocurrently with, or subsequently to, it.
  • the coating is formed on reaction with the soluble salt particle and includes at least one of its ions, good adhesion to the particle is ootained avoiding the need of binders and improving the ability to affect the coating of less spherical particles.
  • Formation of inorganic coating reduces the ⁇ anger of flammability ana of formation of explosive materials.
  • SUBSTITUTE SHEET The process of the invention allows using reagents in vapor phase, in non-aqueous liquid, as an emulsion or even in aqueous solution. Melting of reagents is not required. In addition reaction of the reagent with the water soluble particle is spontaneous requiring no energy introduction. The process thus does not require energy input or temperature elevation. In fact in most cases low temperature is favorable, which is advantageous for coating of temperature-sensitive compounds such as HN.N0-,.
  • the reagent is introduced in an organic solvent.
  • organic solvents such as those defined in Israel
  • Patent 57024 corresponding to U.S. Patent No. 4,291,007, the teachings of which are incorporated herein by reference, bind H-,SiF, to form the fluosilicate of the amine according to the reaction
  • R NH- + H-,SiF, > R NH. HSiF, or (R NH. 7 SiF,. n J-n n 4-n 6 n 4-n . o wherein n 1 , 2 or 3.
  • Reaction may be affected and controlled by the properties of the solvent, e.g., it is known that amines prefer nitric acid over
  • the solvent may be use ⁇ to extract a reagent from its a ⁇ ueous solution thereny permitting the use of reagents formed as by-products even if in dilute solutions (e.g., H-,SiFg formed on scrubbing Sir, , in phosphoric acid industry); and
  • the solvent may be chosen so as to form tne required organic coating on the top of the insoluble salt which is formed.
  • the process of the invention provides for higher compatibility with fertilizer production and utilization.
  • SUBSTITUTESHEET examples wnich include preferred embodiments will serve to illustrate the practice of tms invention, it being understood that tne particulars shown are by way of example and for purposes of illustrative discussicn of preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of formulation procedures as well as of the principles and conceptual aspects of the invention.
  • Potassium nitrate granules with sizes ranging between about 1 mm and 5 mm were introduced into water in w/w ratio of 1:20 respectively. Strong shaking was applied in a mechanical shaker at ambient temperature. Complete dissolution was observed after about 3 minutes. (No insoluble matter was left in the solution).
  • Potassium nitrate granules from the batch used in Comparative Example A were introduced into 36% w/w a ⁇ ueous solution of fluosilicic acid and gently stirred in a mechanical shaker at ambient temperature for a period of about five hours to effect the coating thereof. No indication of potassium nitrate dissolution was found and it is assumed that any potassium nitrate exiting from the coated granules was immediately reacted with the fluosilicic acid still in solution and adds to the coating. Independent precipitation of I SiFg was not
  • the treated granules were separated from tne solution, washe ⁇ and introduced into water in w/w ratio of 1:20 respectively. Strong shaking was applied in a mechanical shaker at ambient temperature. Potassium nitrate dissolution could be visually followed as the coating formed is partially transparent. About eight hours were required for substantial dissolution of the potassium fluosilicate coated potassium nitrate. After 16 hours only the coating remains in solution.
  • This example shows that coating potassium nitrate with potassium fluosilicate slows its dissolution by a factor of 2 orders of magnitude.
  • Magnesium phosphate Magnesium fluoride 0.008 Magnesium laurate 0.007 Magnesium oleate 0.024 Magnesium oxalate 0.07

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Pest Control & Pesticides (AREA)
  • Fertilizers (AREA)
EP93914848A 1992-06-30 1993-06-30 Verfahren zum modifizieren körniger feststoffe und so hergestellte feststoffpartikeln Ceased EP0648198A1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
IL10237092 1992-06-30
IL10237092A IL102370A (en) 1992-06-30 1992-06-30 Process for modifying particulate solids and particulate solids prepared thereby
PCT/GB1993/001370 WO1994000405A1 (en) 1992-06-30 1993-06-30 A process for modifying particulate solids and particulate solids prepared thereby

Publications (1)

Publication Number Publication Date
EP0648198A1 true EP0648198A1 (de) 1995-04-19

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Application Number Title Priority Date Filing Date
EP93914848A Ceased EP0648198A1 (de) 1992-06-30 1993-06-30 Verfahren zum modifizieren körniger feststoffe und so hergestellte feststoffpartikeln

Country Status (4)

Country Link
EP (1) EP0648198A1 (de)
AU (1) AU4507193A (de)
IL (1) IL102370A (de)
WO (1) WO1994000405A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9716961B2 (en) 2013-08-10 2017-07-25 Advanced Acoustic Sf Gmbh Wave field synthesis system

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AUPN003894A0 (en) * 1994-12-13 1995-01-12 Xenotech Research Pty Ltd Head tracking system for stereoscopic display apparatus
CN1040096C (zh) * 1995-08-17 1998-10-07 郑州乐喜施磷复肥技术研究推广中心 一种控制释放肥料
DE29518155U1 (de) 1995-11-16 1996-01-11 Göttfert Küchentechnik, 74392 Freudental Küchengerät
FR2787799B1 (fr) * 1998-12-23 2001-03-09 Rhodia Chimie Sa Composition comprenant une ecorce inorganique et un noyau comportant au moins un compose polyhydroxyle
FR2801810B1 (fr) * 1999-12-07 2002-05-03 Rhodia Food S A S Capsule comprenant au moins une ecorce minerale constituee d'un compose chimique unique et d'un noyau comportant au moins un compose polyhydroxyle
DE102014100026A1 (de) * 2014-01-02 2015-07-02 Chemische Fabrik Budenheim Kg Gemischtmetallische kristalline Orthophosphate für die zeitlich kontrollierte Freisetzung von Spurenelementen im rhizodermalen und epidermalen Bereich von Pflanzen
WO2024105570A1 (en) * 2022-11-14 2024-05-23 SABIC Agri-Nutrients Company Method for multi-phase preparation of complex mineral fertilizer from phosphate rock and nitric acid

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3378363A (en) * 1965-02-23 1968-04-16 Shell Oil Co Method of imparting hardness on water-soluble particles
US5152821A (en) * 1988-02-01 1992-10-06 Hi-Fert Pty. Ltd. Addition of supplemental macro & micro nutrients to granular phosphatic fertilizers

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9400405A1 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9716961B2 (en) 2013-08-10 2017-07-25 Advanced Acoustic Sf Gmbh Wave field synthesis system

Also Published As

Publication number Publication date
WO1994000405A1 (en) 1994-01-06
IL102370A (en) 1995-03-30
IL102370A0 (en) 1993-01-14
AU4507193A (en) 1994-01-24

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