WO1999029632A1 - Composition a base d'hypochlorite de calcium - Google Patents

Composition a base d'hypochlorite de calcium Download PDF

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Publication number
WO1999029632A1
WO1999029632A1 PCT/US1998/025403 US9825403W WO9929632A1 WO 1999029632 A1 WO1999029632 A1 WO 1999029632A1 US 9825403 W US9825403 W US 9825403W WO 9929632 A1 WO9929632 A1 WO 9929632A1
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WO
WIPO (PCT)
Prior art keywords
solid
calcium hypochlorite
composition
present
alkali metal
Prior art date
Application number
PCT/US1998/025403
Other languages
English (en)
Inventor
Stanley R. Pickens
Donald P. Iwanski
Original Assignee
Ppg Industries Ohio, Inc.
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 Ppg Industries Ohio, Inc. filed Critical Ppg Industries Ohio, Inc.
Priority to AU16131/99A priority Critical patent/AU1613199A/en
Publication of WO1999029632A1 publication Critical patent/WO1999029632A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/76—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens

Definitions

  • Solid calcium hypochlorite compositions containing a scale-inhibiting amount of a solid alkali metal phosphate, e.g., sodium tripolyphosphate are described.
  • the present invention also relates to solid shaped articles, e.g., tablets, fabricated from such solid compositions.
  • the sanitization of an aqueous stream typically involves adding to it a halogen or halogen-containing material, e.g., chlorine or calcium hypochlorite, to establish a desired level of free available halogen, e.g., free available chlorine, in the aqueous stream.
  • a halogen or halogen-containing material e.g., chlorine or calcium hypochlorite
  • free available halogen e.g., free available chlorine
  • Drinking water typically contains from 0.5 to 1 part free available chlorine (FAC) per million parts of water (ppm) .
  • Free available chlorine can be introduced into water by adding a source of hypochlorous acid (H0C1) or hypochlorite anion (CIO " ) into the water.
  • a source of hypochlorous acid H0C1
  • CIO hypochlorite anion
  • Recreational bodies of water e.g., swimming pools, hot tubs, spas, etc., typically contain from 1 to 3 ppm of FAC.
  • Water having a FAC content in amounts of greater than 10 ppm can be used to sanitize surfaces or articles to which it is applied.
  • Free available chlorine is commonly introduced into an aqueous stream by passing the stream or a portion thereof through a chlorination unit having therein a source of FAC.
  • a particularly common source of FAC is calcium hypochlorite, which is typically placed in the chlorination unit in a solid form, e.g., granules or tablets, and dissolves upon contact with the aqueous stream.
  • Dissolving calcium hypochlorite in an aqueous stream by passing the stream through a chlorination unit also results in the co-release of calcium ions, which can form calcium carbonate in solution, e.g., by absorption of carbon dioxide from the atmosphere.
  • the level of calcium carbonate in solution becomes high, e.g., in excess of 100 parts calcium carbonate per million parts of water (ppm) , it is more likely to precipitate from solution and form scale deposits.
  • Calcium carbonate levels in excess of 100 ppm often exist both within the chlorination unit and in the outlet conduits leading immediately away from the unit. Consequently, deposits of scale are more likely to form in these locations.
  • the formation of scale deposits can be further increased if the aqueous stream entering the chlorination unit has a high pH, e.g., 7.8 or greater, high concentrations of bicarbonate and / or carbonate, i.e., high alkalinity, or contains minerals, e.g., calcium and magnesium carbonate, dissolved therein, i.e., a hard water stream.
  • a high pH e.g., 7.8 or greater
  • high concentrations of bicarbonate and / or carbonate i.e., high alkalinity
  • minerals e.g., calcium and magnesium carbonate
  • Scale deposits e.g., calcium carbonate scale
  • This occlusion of liquid passages can result in a reduction in the amount of sanitizing agent introduced into the aqueous stream charged to the chlorination unit.
  • the aqueous stream exiting the chlorination unit may not have an adequate level of FAC for its intended use, e.g., as drinking water or for sanitizing a surface or larger body of water, e.g., a swimming pool .
  • HEI 5 [1993] -123697 discloses a method of inhibiting the generation of calcium scale in equipment used for dissolving inorganic bleaching powder.
  • the inorganic bleaching powder e.g., calcium hypochlorite
  • water containing a polyphosphate compound e.g., sodium tripolyphosphate.
  • the polyphosphate compound is disclosed as being present in the water in an amount of from 0.1 to 20 parts by weight, with respect to 100 parts by weight of the dissolved inorganic bleaching powder.
  • 3,793,216 discloses a calcium hypochlorite composition resistant to exothermic decomposition consisting essentially of calcium hypochlorite uniformly mixed with water-soluble, hydrated inorganic salt in an amount sufficient to provide a water content in the total mixture in the range of 3 % to 13 %.
  • United States Patent No. 3,969,546 discloses granular calcium hypochlorite particles having a core of calcium hypochlorite encapsulated in a plurality of layers of calcium hypochlorite and being coated with a plurality of layers of an inorganic salt .
  • the protective layer or layers of anhydrous and / or hydrated inorganic salt may comprise from 5 % to 40 % by weight, based on the total weight of the particle.
  • United States Patent No. 2,695,274 discloses a dry stable composition of lithium hypochlorite and potassium carbonate to which a water-soluble alkali metal salt of the class including polyphosphates is added to prevent the precipitation of insoluble calcium or magnesium salts when the composition is dissolved in hard water.
  • United States Patent No. 5,112,521 discloses a solid calcium hypochlorite composition comprising at least 0.005 % by weight of an alkali metal salt of phosphonobutane polycarboxylic acid.
  • the disclosed composition can significantly reduce scale formation in dispensers for calcium hypochlorite, particularly where water having high total alkalinity is used.
  • a solid calcium hypochlorite composition comprising a mixture of: (a) calcium hypochlorite; and (b) a scale-inhibiting amount of a solid alkali metal phosphate, wherein said solid alkali metal phosphate is commingled with the calcium hypochlorite.
  • a solid shaped article comprising the solid calcium hypochlorite composition as recited above.
  • the novel solid calcium hypochlorite composition of the present invention comprises solid calcium hypochlorite, which is a known and commercially available material. Chemically, commercially available calcium hypochlorite typically contains at least 55 weight percent available chlorine, e.g., between 60 and 72 percent available chlorine. Presently, commercially available calcium hypochlorite generally contains between 65 and 70 weight percent available chlorine. The remainder of such commercially available calcium hypochlorite is usually composed of varying amounts of water, and inorganic by-product calcium and alkali metal salts incorporated during the manufacturing process. Such salts include sodium chloride, calcium chloride, calcium hydroxide, calcium carbonate and calcium chlorate.
  • Water may comprise between 2 and 15 percent, e.g., between 4 and 10 percent, by weight, based on the total weight of the calcium hypochlorite material.
  • the particle size distribution of particulate calcium hypochlorite materials may vary and often depends upon its ultimate use.
  • the particulate size and particle size distribution of the calcium hypochlorite that may be used in the present invention is not critical and thus any particulate material, e.g., from a powdery material to a granular material, may be used to prepare compositions of the present invention.
  • particulate calcium hypochlorite typically has a principal size distribution between 6 and 100 American Standard Test Method E-ll Alternative Sieve Designation (ASTM E-ll ASD) , i.e., the particles vary in size principally between 3.35 millimeters (mm) (0.13 inches) and 0.15 mm (0.006 inches). More commonly, the particles will have a principal size distribution between 18 (1.00 mm) and 60 (0.25 mm) ASTM E-ll ASD.
  • An example of a preferred granular calcium hypochlorite is available commercially from PPG Industries, Inc. under the tradename PITTCLOR ® .
  • Calcium hypochlorite is typically present in the solid compositions of the present invention in an amount of at least 55 % by weight, preferably at least 60 % by weight, and more preferably at least 65 % by weight, based on the total weight of the composition. Also calcium hypochlorite is typically present in an amount of less than 75 % by weight, preferably less than 70 % by weight, and more preferably less than 68 % by weight, based on the total weight of the composition. The calcium hypochlorite may be present in an amount ranging between any combination of these values, inclusive of the recited values.
  • the solid calcium hypochlorite compositions of the present invention also contain a scale-inhibiting amount of a solid alkali metal phosphate commingled, e.g., substantially homogeneously mixed, with the particulate calcium hypochlorite.
  • scale-inhibiting amount is meant that amount of alkali metal phosphate which is at least sufficient to inhibit or minimize, and preferably prevent, the surface deposition of scale, e.g., calcium carbonate scale, when the solid composition of the present invention is dissolved in water.
  • the solid alkali metal phosphate introduces orthophosphate into the aqueous solution, which acts to disrupt the crystalline structure of forming scales, e.g., calcium carbonate scale, and inhibits or prevents their deposition upon solid surfaces, such as the interior surfaces of a chlorination unit.
  • the alkali metal phosphate is a solid and, preferably, a particulate solid.
  • the particle size and particle size distribution of particulate alkali metal phosphate used in the present invention may vary and is not critical.
  • the alkali metal phosphate may, for example, be in a form ranging from a powdery material to a granular material .
  • the alkali metal phosphate is in the form of particulates, e.g., granules, and is of about the same particle size range as the calcium hypochlorite.
  • the particulate alkali metal phosphate used has a size distribution of from 20 to 40 ASTM E-ll ASD, i.e., the particles vary in size between 0.85 mm (0.034 inches) to 0.43 mm (0.017 inches).
  • phosphates suitable for use as solid alkali metal phosphates in the present invention include, but are not limited to, tripolyphosphate, pyrophosphate, trimetaphosphate, hexametatphosphate, orthophosphate and mixtures of such exemplary phosphates.
  • the alkali metal of the solid alkali metal phosphate may be, for example, lithium, sodium or potassium, preferably sodium.
  • the solid alkali metal phosphate may be hydrated or nonhydrated, i.e., anhydrous. In a particularly preferred embodiment of the present invention, the solid alkali metal phosphate is sodium tripolyphosphate.
  • the solid alkali metal phosphate is typically present in the composition of the present invention in an amount of at least 0.05 % by weight, preferably at least 0.1 % by weight, and more preferably at least 0.5 % by weight, based on the total weight of the composition.
  • the solid alkali metal phosphate is also typically present in an amount of less than 4 % by weight, preferably less than 3 % by weight, and more preferably less than 2 % by weight, based on the total weight of the composition.
  • the solid alkali metal phosphate may be present in an amount ranging between any combination of these values, inclusive of the recited values.
  • Solid calcium hypochlorite compositions according to the present invention may also contain additives that do not interfere with the scale-inhibiting properties of these compositions.
  • Additives that may be present include, but are not limited to: dissolution rate modifiers, e.g., calcium stearate, magnesium stearate, sodium stearate, fine powdered silicic acid and fine powdered calcium silicate; binders, e.g., poly (ethylene glycol) , poly(vinyl pyrrolidone) , carboxymethylcellulose, sodium alginate and boric acid; lubricants, e.g., calcium stearate, magnesium stearate and talc; colorant-containing inorganic salts, such as those described in United States Patent No.
  • the solid compositions of the present invention may contain additives in amounts totaling, for example, from 0.001 % to 15 % by weight, and from 0.01 % to 5 % by weight, based on the total weight of the composition, inclusive of the recited values.
  • the balance of the solid compositions of the present invention typically comprises substantially inert by-products resulting from the preparation of calcium hypochlorite, e.g., water and calcium and alkali metal salts as previously recited with regard to commercially available calcium hypochlorite.
  • These by-products are generally present in amounts ranging from 6 % to 45 % by weight, e.g., from 25 % to 35 % by weight, based on the total weight of the composition, inclusive of the recited values.
  • the solid calcium hypochlorite compositions of the present invention may be added to any suitable chlorination unit or device, which is used to sanitize an aqueous stream.
  • suitable chlorination units are those described in United States Patent No.'s 5,384,102 and 5,089,127.
  • the solid compositions of the present invention can be used in existing chlorination units without requiring any structural modification or augmentation to these units.
  • the aqueous stream introduced into the chlorination unit, and contacted with the solid calcium carbonate composition of the present invention may be from any suitable source, e.g., wells, cisterns, reservoirs, municipal water systems, streams and rivers .
  • the amount of solid alkali metal phosphate present in the solid calcium hypochlorite composition of the present invention can be adjusted accordingly.
  • the solid alkali metal phosphate would typically be present in the solid composition of the present invention in an amount of from 1 % by weight to 4 % by weight, based on the total weight of the composition.
  • An aqueous stream sanitized by contact with the solid calcium hypochlorite composition of the present invention, i.e., a sanitized aqueous stream, may be used in any number of applications, e.g., as drinking water, cooling tower water, swimming pools or to sanitize the surface of an article.
  • the sanitized aqueous stream may be applied by any appropriate method, examples of which include but are not limited to: spray application; wiping with soaked rags; curtain or waterfall application; and soaking by immersion.
  • surfaces or articles to which the sanitized aqueous stream may be applied include, but are not limited to: harvested vegetables such as potatoes, sweet potatoes, and mushrooms; harvested fruits, such as apples; metal surfaces in meat and food processing plants; equipment in breweries, e.g., fermenting tubs, and the interior and exterior of pipes; and chicken carcasses in chicken processing plants.
  • Solid calcium hypochlorite compositions of the present invention may be formed into solid shaped articles, e.g., tablets, bricks, briquettes, pellets, etc., by conventional size enlargement equipment such as a molding press, tableting press, roll-type press, pellet mill and screw extruder.
  • the solid shaped article may typically have a mass of between 1 gram and 350 grams or more, e.g., between 7 and 300 grams.
  • the size of the solid shaped articles is determined typically by the internal dimensions and specifications of the chlorination unit in which they are to be used.
  • the diameter of the tablet be between 7.6 centimeters (cm) (3 inches) and 8.9 cm (3.5 inches), e.g., between 7.9 cm (3.125 inches) and 8.3 cm (3.25 inches), and be 2.5 cm (1 inch) to 5.1 cm (2 inches), e.g., 3.2 cm (1.25 inches) thick, inclusive of the recited values .
  • Particularly suitable for use in producing solid shaped articles is granular calcium hypochlorite having a size distribution predominantly between 10 and 45 ASTM E-ll ASD, i.e., the granules are principally between on average 2.00 mm (0.08 inches) and 0.36 mm (0.014 inches) .
  • Particles smaller than 50 ASTM E-ll ASD, i.e., 0.30 mm (0.012 inches), that are present in the granular calcium hypochlorite represent a minor percentage, usually less than 2 percent, of the material charged to a size enlargement device.
  • the solid alkali metal phosphate preferably has an average principal particle size distribution of from 20 to 40 ASTM E-ll ASD, i.e., from 0.85 mm to 0.43 mm.
  • Solid shaped articles in the form of tablets representative of an embodiment of the present invention were prepared as follows. Granulated calcium hypochlorite available commercially from PPG Industries, Inc. under the tradename PITTCLOR ® and granulated NITRIFOS ® sodium tripolyphosphate (STPP) obtained commercially from Monsanto Co. were dry blended in amounts appropriate to provide an STPP level of 0.9 % by weight, based on the total weight of the dry blend. A portion of the homogenous dry blend was introduced into a tableting press, and 300 gram tablets having a thickness of 3.2 cm and a diameter of 7.9 cm were produced. Similarly, comparative calcium hypochlorite tablets of the same dimension and weight but containing no alkali metal phosphate were prepared by introducing PITTCLOR calcium hypochlorite alone into the same tableting press.
  • Water having a calcium hardness 3 of 82 ppm, an alkalinity of 84 ppm, a pH of 7.8 and temperature of 19 °C was fed at a rate of 23 liters per minute (6 gallons per minute) to a model number N-200 chlorinator available commercially from PPG Industries.
  • the chlorinator was operated using the comparative calcium hypochlorite tablets as described above and had a free available chlorine delivery rate of 1.8 to 2.7 kilograms per day (4 to 6 pounds per day) .
  • the chlorinator and its outlet conduit had to be disassembled and cleaned to remove occluding scale deposits once every 10 days on average .
  • Calcium hardness was determined in accordance with method 2340 C of Standard Methods for the Examination of Water and aste atp.r, 19th Edition 1995, American Public Health Association.
  • Alkalinity was determined in accordance with method 2320 B of Standard Methods for the Examination of Water and Wastewater . 19th Edition 1995, American Public Health Association.
  • EXAMPLE 2 Water having a calcium hardness 3 of 260 ppm, an alkalinity of 190 ppm, a pH of 7.8 and temperature of 20°C was fed at a rate of 23 liters per minute (6 gallons per minute) to a model number N-200 chlorinator available commercially from PPG Industries.
  • the chlorinator was operated using comparative calcium hypochlorite tablets as described in Example 1 and had a free available chlorine delivery rate of 1.8 to 2.7 kilograms per day (4 to 6 pounds per day) .
  • the chlorinator and its outlet conduit had to Joe disassembled and cleaned to remove occluding scale deposits once every 3 days on average .

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  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Detergent Compositions (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)

Abstract

La présente invention concerne une composition solide d'hypochlorite de calcium inhibant la formation de dépôts en couches, par exemple, ceux formés par le calcium et le carbonate de magnésium, lors de leur dissolution dans l'eau. Cette composition solide contient un mélange d'hypochlorite de calcium et une quantité d'un phosphate métallique alcalin solide inhibitrice de la formation de dépôts, tel que le tripolyphosphate de sodium, mélangé à l'hypochlorite de calcium. Cette invention concerne par ailleurs des produits formés solides, tels que des comprimés, renfermant la composition solide d'hypochlorite de calcium. Les compositions solides de cette invention, en particulier les produits formés solides, tels que les comprimés, peuvent être utilisées dans des unités de chloration existantes sans avoir à modifier ou à augmenter structurellement ces unités.
PCT/US1998/025403 1997-12-08 1998-11-30 Composition a base d'hypochlorite de calcium WO1999029632A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU16131/99A AU1613199A (en) 1997-12-08 1998-11-30 Calcium hypochlorite composition

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US98689397A 1997-12-08 1997-12-08
US08/986,893 1997-12-08

Publications (1)

Publication Number Publication Date
WO1999029632A1 true WO1999029632A1 (fr) 1999-06-17

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PCT/US1998/025403 WO1999029632A1 (fr) 1997-12-08 1998-11-30 Composition a base d'hypochlorite de calcium

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AU (1) AU1613199A (fr)
CO (1) CO5040116A1 (fr)
WO (1) WO1999029632A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100446165B1 (ko) * 2001-10-10 2004-08-30 정순영 액상 폐기물 처리제
WO2007000747A1 (fr) * 2005-06-28 2007-01-04 Ppa Water Industries (Proprietary) Limited Artefact de traitement de l'eau
US7410938B2 (en) 2004-02-24 2008-08-12 Arch Chemicals, Inc. Calcium hypochlorite/scale inhibitor/residue disperser triblend
DE102013111150A1 (de) * 2013-10-09 2015-04-09 Witty-Chemie Gmbh & Co. Kg Wässrige Suspension zur Dosierung in ein wässriges System, insbesondere in Schwimmbadwasser und Verfahren zur Dosierung einer wässrigen Suspension in ein wässriges System

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3639284A (en) * 1969-08-14 1972-02-01 Olin Corp Bleaching composition

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3639284A (en) * 1969-08-14 1972-02-01 Olin Corp Bleaching composition

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100446165B1 (ko) * 2001-10-10 2004-08-30 정순영 액상 폐기물 처리제
US7410938B2 (en) 2004-02-24 2008-08-12 Arch Chemicals, Inc. Calcium hypochlorite/scale inhibitor/residue disperser triblend
WO2007000747A1 (fr) * 2005-06-28 2007-01-04 Ppa Water Industries (Proprietary) Limited Artefact de traitement de l'eau
DE102013111150A1 (de) * 2013-10-09 2015-04-09 Witty-Chemie Gmbh & Co. Kg Wässrige Suspension zur Dosierung in ein wässriges System, insbesondere in Schwimmbadwasser und Verfahren zur Dosierung einer wässrigen Suspension in ein wässriges System
DE102013111150B4 (de) 2013-10-09 2018-05-03 Witty Gmbh & Co. Kg Verwendung eines Komplexierungsmittels in einer wässrigen Suspension, insbesondere zur Dosierung in Schwimmbadwasser, sowie Verfahren zur Dosierung einer wässrigen Suspension in ein wässriges System
AT514910A3 (de) * 2013-10-09 2020-09-15 Witty Gmbh & Co Kg Wässrige Suspension zur Dosierung in ein wässriges System, insbesondere in Schwimmbadwasser
AT514910B1 (de) * 2013-10-09 2020-10-15 Witty Gmbh & Co Kg Wässrige Suspension zur Dosierung in ein wässriges System, insbesondere in Schwimmbadwasser

Also Published As

Publication number Publication date
CO5040116A1 (es) 2001-05-29
AU1613199A (en) 1999-06-28

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