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WO1999061376A1 - Calcium hypochlorite composition - Google Patents

Calcium hypochlorite composition

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Publication number
WO1999061376A1
WO1999061376A1 PCT/US1999/010927 US9910927W WO1999061376A1 WO 1999061376 A1 WO1999061376 A1 WO 1999061376A1 US 9910927 W US9910927 W US 9910927W WO 1999061376 A1 WO1999061376 A1 WO 1999061376A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
calcium
hypochlorite
aluminum
salt
hydrated
Prior art date
Application number
PCT/US1999/010927
Other languages
French (fr)
Inventor
Stanley R. Pickens
Fred Abraham
Charles R. Wiedrich
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

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Classifications

    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/72Treatment of water, waste water, or sewage by oxidation
    • C02F1/76Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
    • AHUMAN NECESSITIES
    • A01AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01NPRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES, AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
    • A01N59/00Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B11/00Oxides or oxyacids of halogens; Salts thereof
    • C01B11/04Hypochlorous acid
    • C01B11/06Hypochlorites
    • C01B11/068Stabilisation by additives other than oxides, hydroxides, carbonates of alkali or alkaline-earth metals; Coating of particles; Shaping; Granulation
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/50Treatment of water, waste water, or sewage by addition or application of a germicide or by oligodynamic treatment
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/42Nature of the water, waste water, sewage or sludge to be treated from bathing facilities, e.g. swimming pools

Abstract

A solid calcium hypochlorite composition that is not classified as a Division 5.1 oxidizer material is described. The composition comprises an admixture of particulate (a) calcium hypochlorite, (b) hydrated borate salt, e.g., disodium tetraborate decahydrate, and (c) aluminum salt, e.g., hydrated aluminum sulfate and/or anhydrous aluminum sulfate. The calcium hypochlorite is present in the composition in an amount sufficient to provide a free available chlorine content that would result in the composition being classified as a Division 5.1 oxidizer in the absence of (b) and (c). The aluminum salt is present in the composition in at least a flocculating amount, and the hydrated borate salt is present in an amount at least sufficient to neutralize 100 % of the aluminum salt. Also described are solid shaped articles, e.g., tablets, comprising the calcium hypochlorite composition of the present invention.

Description

CALCIUM HYPOCHLORITE COMPOSITION

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of U.S. Patent Application Serial No. 09/083,844 filed May 22, 1998.

DESCRIPTION OF THE INVENTION

Compositions of particulate calcium hypochlorite admixed with both particulate hydrated borate salts and particulate aluminum salts are described. The components comprising the calcium hypochlorite compositions of the present invention are combined in amounts such that the resultant composition is not classified as a Division 5.1 oxidizer material, as defined in 49 CFR §173.127 (a) (1). The present invention also relates to solid shaped articles, e.g., tablets, fabricated from such calcium hypochlorite compositions.

The sanitization of an aqueous medium typically involves adding to it a sanitizing amount of halogen or halogen- containing material, e.g., calcium hypochlorite, to establish a desired level of free available halogen, e.g., free available chlorine (FAC) , in the aqueous medium. The presence of free available chlorine within the aqueous medium, such as a swimming pool, serves to eradicate deleterious amounts of bacteria that may be present. Ingestion of or even topical exposure to unsanitized or inadequately sanitized water having bacteria therein can lead to sickness and disease in animals and humans. Further, the ingestion by animals and humans of foods that have been processed on unsanitized or inadequately sanitized surfaces, e.g., harvested fruits and poultry products, can lead to sickness and disease in animals and humans . Free available chlorine can be introduced into water by adding a source of hypochlorous acid (H0C1) or hypochlorite anion (CIO") to the water. Recreational bodies of water, e.g., swimming pools, hot tubs, spas, etc., typically contain FAC in an amount of from 1 to 3 parts per million parts (ppm) . Water having an 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 water by the addition of a source of chlorine to the water, e.g., passing the water to be treated, or a portion thereof, through a chlorination unit, which provides 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 when contacted with the water introduced into the unit.

In the case of standing bodies of water, e.g., swimming pools, batch additions of higher levels of FAC may be made in addition to the relatively steady and lower level additions made through the use of a chlorination unit. Such batch additions of FAC are commonly referred to as "shock treatments" or "super chlorinations" and are made on a periodic basis, e.g., once a week or once a month. Typically, the purpose of a shock treatment is to briefly increase the FAC of the body of water, e.g., by 10 to 20 ppm, to consume accumulated organic material, destroy chloramines and / or control algae blooms. A shock treatment may be administered by, for example, preparing a concentrated aqueous solution of calcium hypochlorite from granulated calcium hypochlorite, and then adding this solution to the body of water, or distributing, e.g., broadcasting, granulated calcium hypochlorite directly over the surface of the body of water.

If the amount of organic material accumulated in the body of water is either greater than the capacity of the shock treatment applied or resistant to oxidation, then a suspension of partially consumed or unconsumed organic material may remain. Consequently, a flocculating agent, e.g., aluminum salts, can be added separately to enhance the removal of this suspended material from the water by means of filtration. The removal of suspended material from the body of water is desirable in that it is often accompanied by improved clarity and reduced chlorine demand.

The pH of a recreational body of water, e.g., a swimming pool, is typically maintained between 7.2 and 7.8.

Disadvantages of the pH falling below 7.2 include, for example, rapid dissipation of FAC, etching of contacted surfaces, and eye discomfort. Disadvantages of the pH rising above 7.8 include, for example, low chlorine efficiency, scale formation and eye discomfort. The administration of a calcium hypochlorite shock treatment will often result in an increase in the pH of the body of water treated and as a result will require either the concurrent or subsequent addition of an acidic agent, e.g., hydrochloric acid. Addition of an acid such as hydrochloric acid can be problematic in terms of the personal safety of the individual administering it and the possibility of adding too much or too little.

Depending on the volume of water that is to be sanitized, the amount of calcium hypochlorite that is stored on site for use in a chlorination unit and / or for shock treatments can be large. Calcium hypochlorite, depending on its purity, is a material that can cause or enhance the combustion of organic materials by providing oxygen for combustion, i.e., it serves as an oxidizer. The calcium hypochlorite used to treat bodies of water, such as swimming pools, typically has an FAC content of at least 40 % by weight and is classified as an oxidizer, in particular a Division 5.1 oxidizer, according to Title 49, Code of Federal Regulations, part 173, section 127, paragraph (a), subparagraph (1) (i.e., 49 CFR §173.127 (a) (1) ) . The storage and transport of a material classified as an oxidizer requires the use of special precautions, which may include the use of special containers and separate free standing storage facilities, and which therefore results in increased costs.

In addition to the special handling associated with the storage of calcium hypochlorite due to its oxidizer classification, there is also the matter of its storage stability, i.e., shelf life. In particular, loss of FAC upon storage of calcium hypochlorite will result in a material of low assay (lower FAC content) and inadequate sanitization of water to which the low assay calcium hypochlorite is added. Loss of FAC upon storage can be accelerated if the calcium hypochlorite is formulated with other ingredients so that an aqueous solution prepared from such composition has a low pH, e.g., less than 7. For example, solid compositions prepared from an admixture of calcium hypochlorite and an aluminum salt, e.g., hydrated aluminum sulfate, can lose an appreciable amount of its FAC upon storage. It would be desirable to develop a solid calcium hypochlorite composition that is not classified as a Division 5.1 oxidizer, and has a favorable balance of: stability with regard to FAC loss upon storage; pH in aqueous solution; and flocculation properties. It is also desirable that such a newly developed solid calcium hypochlorite composition have an FAC content at least sufficient to allow its use in the batch and / or continuous sanitization of an aqueous stream or body of water.

United States Patent No. 3,793,216 discloses a calcium hypochlorite composition containing at least 55 % Ca(OCl)2, which is resistant to exothermic, self-propagating decomposition when contacted by a flame, spark or a contaminating organic substance. The composition described in that patent consists essentially of calcium hypochlorite uniformly mixed with a water soluble hydrated inorganic salt, e.g., sodium tetraborate decahydrate or aluminum sulfate octadecahydrate . Combinations of water soluble inorganic salts are not disclosed in the 216 patent.

United States Patent No. 3,969,546 discloses granular calcium hypochlorite particles having a core of calcium hypochlorite encapsulated in from 5 % to 40 % by weight of an anhydrous or hydrated inorganic salt. Such inorganic salts can be aluminum sulfate or sodium tetraborate. Combinations of aluminum salts and hydrated borate salts are not described in the '546 patent.

United States Patent No. 5,676,844 discloses a method of treating a standing water system with an admixture of calcium hypochlorite, borate salts, e.g., sodium tetraborate decahydrate, and optionally boric acid. The admixture of the v 844 patent is described as containing from 20 % to 40 % by weight of borate molecule.

United States Patent No. 4,747,978 discloses a composition of calcium hypochlorite and from about 0.1 to about 3.0 percent by weight water soluble aluminum-containing inorganic salt, e.g., aluminum sulfate octadecahydrate. The composition of the 978 patent is described as being useful for disinfecting a body of water, e.g., a swimming pool, and enhancing water clarity.

In accordance with the present invention there are provided, non-oxidizer solid calcium hypochlorite compositions, i.e., compositions that are not classified as a Division 5.1 oxidizer. These calcium hypochlorite compositions comprise an admixture of particulate:

(a) calcium hypochlorite;

(b) hydrated borate salt; and (c) aluminum salt selected from hydrated aluminum salt, anhydrous aluminum salt and mixtures thereof. The particulate calcium hypochlorite in the composition is present in an amount and is of a concentration such that said solid calcium hypochlorite composition would be classified as a Division 5.1 oxidizer (hereinafter referred to as an "Oxidizer") in the absence of components (b) and (c) . The aluminum salt is present in the composition in at least flocculating amounts, and the hydrated borate salt is present in an amount at least sufficient to neutralize 100 % of said aluminum salt. The hydrated borate salt and aluminum salt are together present in an amount sufficient to render classification of the solid composition as a non-Division 5.1 oxidizer, hereinafter referred to as a "Non-Oxidizer" or other similar terms. Solid calcium hypochlorite compositions according to the present invention are in the form of a substantially homogenous admixture of the above-recited particulate components (a) , (b) and (c) .

In accordance with the present invention there is further provided a solid shaped article comprising the above-recited solid calcium hypochlorite composition.

Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, values or reaction conditions used in the specification and claims are to be understood as modified in all instances by the term "about".

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment of the present invention, the calcium hypochlorite composition comprises solid, e.g., particulate, calcium hypochlorite, which is a known and commercially available material. Chemically, commercially available calcium hypochlorite typically contains at least 40 weight percent available chlorine, more typically at least 55 weight percent available chlorine, e.g., between 60 and 75 percent available chlorine. Presently, commercially available calcium hypochlorite generally contains between 65 and 75 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. In current commercially available calcium hypochlorite materials, water typically comprises between 2 and 15 percent, e.g., between 5.5 and 10 percent, by weight, based on the total weight of the calcium hypochlorite material .

The particle size distribution of the particulate calcium hypochlorite materials used to prepare the admixed particulate compositions of the present invention may vary, for example, from a powdery material to a granular material . As a general guideline, particulate calcium hypochlorite typically has a principal size distribution between 100 and 6 mesh, as measured by the American Standard Test Method E-11 Alternative Sieve Designation (ASTM E-11 ASD) , i.e., the particles vary in size principally between 0.15 millimeters (mm) (0.006 inches) and 3.35 mm (0.13 inches) . More commonly, the particles will have a principal size distribution between 60 (0.25 mm) and 18 (1.00 mm) mesh based on ASTM E-11 ASD. An example of a granular calcium hypochlorite useful in the present invention is available commercially from PPG Industries, Inc. under the trademark PITTCLOR.

In a preferred embodiment, at least 80 percent by weight, preferably at least 90 percent by weight, and more preferably at least 94 percent by weight of the particulate calcium hypochlorite, based on the total weight of the particulate calcium hypochlorite used to prepare the admixed particulate compositions of the present invention has particle sizes between 60 mesh (0.25 mm) and 25 mesh (0.71 mm), inclusive of the recited values. It is also preferred that the particulate calcium hypochlorite contain a minimum of particles having sizes greater than 25 mesh (0.71 mm), e.g., less than 10 percent by weight, preferably less than 5 percent by weight, and more preferably less than 3 percent by weight of the particulate calcium hypochlorite, based on the total weight of the particulate calcium hypochlorite used. It is further preferred that the particulate calcium hypochlorite contain a minimum of particles having sizes less than 60 mesh (0.25 mm), e.g., less than 10 percent by weight, preferably less than 6 or 5 percent by weight, and more preferably less than 3 percent by weight of the particulate calcium hypochlorite, based on the total weight of the particulate calcium hypochlorite used.

Particulate compositions according to the present invention that contain particulate calcium hypochlorite having a particle size distribution as recited immediately above have been found to posses an improved rate of dissolution in an aqueous body of water, e.g., when broadcasted over the surface of a swimming pool. That is an improved rate of dissolution compared to compositions according to the present invention that contain particulate calcium hypochlorite having a particle size distribution outside of these recited ranges.

Calcium hypochlorite is typically present in the compositions of the present invention in an amount at least sufficient to provide an FAC content that would result in the composition being classified as an Oxidizer in the absence of both the hydrated borate salt and aluminum salt components of the composition. A calcium hypochlorite composition having an FAC content of 20 % by weight, based on total weight, was prepared from an admixture of 28 parts of calcium hypochlorite, having an FAC content of 70.5 % by weight, based on the calcium hypochlorite, and 72 parts of sodium chloride. This 20 % FAC calcium hypochlorite composition was evaluated using the test methods described in the Examples herein and found to be a Non-Oxidizer . A similarly prepared solid calcium hypochlorite composition having an FAC content of 39 % by weight was found to be an Oxidizer. See Example 3 and Tables 1 and 3 of the Examples herein.

To most effectively sanitize an aqueous stream or body of water, it is preferred that the calcium hypochlorite in the compositions of the present invention be present in amounts sufficient to provide at least 39 % by weight FAC, and typically at least 45 % by weight FAC, based on total composition weight. Calcium hypochlorite may be present in the compositions of the present invention in amounts sufficient to provide less than 75 % by weight FAC, and typically less than 65 % by weight FAC, based on total composition weight. Compositions prepared in accordance with the present invention may have present therein calcium hypochlorite in an amount sufficient to provide an FAC content ranging between any combination of these values, inclusive of the recited values. Solid calcium hypochlorite compositions according to the present invention also include one or more hydrated borate salts and one or more aluminum salts. The hydrated borate salt(s) and aluminum salt(s) are together present in an amount sufficient to result in the composition being classified as a Non-Oxidizer. The exact amount of hydrated borate salt(s) and aluminum salt(s) required for the composition of the present invention will depend on the FAC content of the calcium hypochlorite with which they are both admixed. Generally, as the FAC content of the calcium hypochlorite used increases, the amount of hydrated borate salt and aluminum salt required for the composition also increases.

More particularly, when the hydrated borate salt is hydrated alkali metal tetraborate and the aluminum salt is selected from hydrated and/or anhydrous aluminum sulfate, they are typically present in the solid compositions of the present invention in a combined amount of at least 10 % by weight, preferably at least 15 % by weight, and more preferably at least 20 % by weight, based on total composition weight. Also, hydrated alkali metal tetraborate salt and hydrated and/or anhydrous aluminum sulfate are typically present in the compositions of the present invention in combined amounts of less than 35 % by weight, preferably less than 30 % by weight, and more preferably less than 28 % by weight. The hydrated alkali metal tetraborate and aluminum sulfate may be present in the composition of the present invention in combined amounts ranging between any combination of these values, inclusive of the recited values. The hydrated borate salt and aluminum salt are also present in the solid composition of the present invention in amounts relative to each other, e.g., in a molar ratio, such that the aluminum salt is: (a) present in at least a flocculating amount; and (b) in an amount that is preferably substantially neutralized, e.g., at least 100 % neutralized, by the hydrated borate salt . As used in this description and the appended claims, the term "100 % neutralized" means that an aqueous solution of the hydrated borate salt(s) and aluminum salt(s) used would have a substantially neutral pH, i.e. , a pH of 7.0.

When the aluminum salt is less than 100 % neutralized, it is likely that the calcium hypochlorite composition of the present invention will have decreased storage stability, i.e., increased loss of FAC on storage. The choice of molar ratios of hydrated borate salt to aluminum salt will depend on the specific salts used, e.g., hydrated alkali metal borates, hydrated alkali metal metaborates, aluminum sulfates, or aluminum halides. For example, the molar ratio of hydrated alkali metal tetraborate to hydrated and/or anhydrous aluminum sulfate that will result in 100 % neutralization of the aluminum sulfate is 3 : 1.

In addition to the presence of at least a flocculating amount of aluminum salt, the upper limit of the molar ratio of hydrated borate salt to aluminum salt is also governed by the aqueous solution pH of the calcium hypochlorite composition of the present invention. As the molar ratio of hydrated borate salt to aluminum salt increases, the pH of an aqueous solution of the calcium hypochlorite composition will also increase, approaching the buffered pH of the hydrated borate salt alone, e.g., 9.2 in the case of sodium tetraborate decahydrate. As the pH of the aqueous solution increases, the amount of acid required to adjust the pH down to the desired range of 7.2 to 7.8, in the case of a swimming pool will also increase, as previously discussed herein.

When the hydrated borate salt is hydrated alkali metal tetraborate and the aluminum salt is selected from hydrated aluminum sulfate and/or anhydrous aluminum sulfate, the molar ratio of the borate to the aluminum salt will be at least 3 : 1, and preferably at least 3.5 : 1. The molar ratio of hydrated alkali metal tetraborate to hydrated and/or anhydrous aluminum sulfate is also less than 18 : 1 and preferably less than 9 : 1. The molar ratio of hydrated alkali metal tetraborate to aluminum sulfate may range between any combination of these ratios, inclusive of the recited ratios.

By "flocculating amount" is meant that amount of aluminum salt which is sufficient to result in a measurable improvement in the flocculation and settling of water- insoluble materials and any organic materials or suspended solids present in the water, e.g., as a result of the addition of the calcium hypochlorite composition of the present invention to the water being treated. The effectiveness with which such materials are flocculated can be determined by testing the treated water, e.g., using an Imhoff cone as described in the Examples herein. The flocculating amount of aluminum salt in the solid compositions of the present invention will depend in part on how the compositions are used. If the composition is used to continuously introduce FAC into a body of water, e.g., using a chemical feeder, the flocculating amount can be as low as 0.1 % to 3 % by weight, based on the total weight of the composition. However, when the composition is used as a shock treatment for a body of water, the flocculating amount will typically be higher, e.g., 1 % to 10 % by weight, based on the total weight of the composition.

The particle size distribution of the particulate hydrated borate salt(s) and aluminum salt(s) used to prepare the admixed particulate compositions of the present invention may vary, for example, from powdery to granular materials. In an embodiment of the present invention, when the hydrated borate salt is hydrated alkali metal tetraborate, it preferably has a principal size distribution between 70 mesh (0.21 mm) and 30 mesh (0.60 mm) ; and when the aluminum salt is hydrated and/or anhydrous aluminum sulfate, it preferably has a principal size distribution between 325 mesh (0.05 mm) and 100 mesh (0.15 mm) .

Hydrated borate salts useful in the calcium hypochlorite compositions of the present invention are preferably solid, i.e., particulate, at room temperature and water soluble. Examples of useful hydrated borate salts include, but are not limited to, hydrated alkali metal borates, e.g., dipotassium tetraborate tetrahydrate, disodium tetraborate tetrahydrate, disodium tetraborate pentahydrate, disodium tetraborate octahydrate, disodium tetraborate decahydrate, sodium metaborate dihydrate, sodium metaborate tetrahydrate, potassium pentaborate tetrahydrate, sodium pentaborate pentahydrate, disodium octaborate tetrahydrate, sodium perborate monohydrate, sodium perborate trihydrate and sodium perborate tetrahydrate; hydrated alkaline earth metal borates, e.g., barium metaborate hydrate and dicalcium hexaborate pentahydrate; hydrated transition metal borates, e.g., zinc diborate dihydrate, zinc triborate monohydrate and dizinc hexaborate heptahydrate ; hydrated mixed salt borates, e.g., sodium calcium pentaborate pentahydrate and sodium calcium pentaborate octahydrate; and mixtures of these hydrated borate salts.

In a further preferred embodiment of the present invention, the hydrated borate salt is hydrated alkali metal tetraborate selected from the group consisting of dipotassium tetraborate tetrahydrate, disodium tetraborate tetrahydrate, disodium tetraborate pentahydrate, disodium tetraborate octahydrate, disodium tetraborate decahydrate and mixtures thereof. In a particularly preferred embodiment of the present invention, the hydrated borate salt is disodium tetraborate decahydrate . Aluminum salts useful in the composition of the present invention are preferably solid, e.g., particulate, at room temperature, act as flocculating agents, and are at least dispersible in water and preferably are soluble in water. Examples of useful aluminum salts include, but are not limited to, hydrated aluminum sulfates containing, for example, from 14 to 18 moles of water, such as aluminum sulfate octadecahydrate or a mixture of hydrated aluminum sulfates containing on average between 14 to 18 moles of water; hydrated aluminum alkali metal mixed salt sulfates, e.g., hydrated aluminum sodium sulfates and hydrated aluminum potassium sulfates; hydrated aluminum halides, e.g., aluminum bromide hexahydrate, aluminum bromide pentadecahydrate, aluminum chloride hexahydrate and aluminum iodide hexahydrate; anhydrous aluminum sulfate; anhydrous aluminum alkali metal mixed salt sulfates; anhydrous aluminum halides ; and mixtures of such aluminum salts. In a preferred embodiment of the present invention, the aluminum salt is selected from hydrated aluminum sulfate, e.g., aluminum sulfate octadecahydrate, anhydrous aluminum sulfate and combinations thereof.

In an embodiment of the present invention, the solid calcium hypochlorite composition further includes at least an effective amount of an anti-caking additive. When the aluminum salt is selected from only hydrated aluminum salts, e.g., aluminum sulfate octadecahydrate, the particulate composition of the present invention can be more prone to clumping or caking, and the use of one or more anti-caking additives is advantageous. Examples of useful anti-caking additives include, but are not limited to, alkaline earth metal silicates, e.g., calcium silicate, magnesium silicate and tricalcium silicate; aluminum alkaline earth metal silicates, e.g., aluminum calcium silicate; alkali metal aluminosilicates, e.g., sodium aluminosilicate and potassium aluminosilicate; alkali metal alkaline earth metal aluminosilicates, e.g., sodium calcium aluminosilicate; precipitated silica; and mixtures of such anti-caking additives. When used, the anti-caking additive is typically present in an amount of from 0.5 to 5 percent by weight, e.g., from 1 to 3 percent by weight, based on the total weight of the particulate calcium hypochlorite composition of the present invention. The anti-caking additive is typically in granular form and preferably in the form of a fine powder. Calcium hypochlorite compositions according to the present invention may also contain additives that would not cause the composition to be classified as an Oxidizer. When the calcium hypochlorite compositions are formed into solid shaped articles, e.g., tablets, additives that may be present include, but are not limited to, dissolution rate modifiers, e.g., calcium stearate, aluminum stearate, magnesium stearate, sodium stearate and fine powdered silicic acid; binders, e.g., boric acid; lubricants, e.g., calcium stearate, magnesium stearate and talc. Other additives that may be present when the calcium hypochlorite compositions are in either tablet or granular form include, but are not limited to, colorant- containing inorganic salts, such as those described in United States Patent No. 5,049,385, the disclosure of which is incorporated herein in its entirety; and polyfluorinated polymers, such as those described in United States Patent No.'s 4,865,760, 4,970,020 and 5,205,961, the disclosures of which are incorporated herein in their entirety. The solid compositions of the present invention may contain additives in amounts totaling, for example, from 0.001 % to 15 % by weight, preferably from 0.01 % to 5 % by weight, based on the total weight of the composition.

The calcium hypochlorite compositions of the present invention may be added in the form of granules, pellets or tablets, to any suitable chlorination unit or device, which is used to sanitize an aqueous stream. Examples of suitable chlorination units are those described in United States Patent No.'s 5,384,102 and 5,089,127.

An aqueous stream or body of water sanitized by contact with the calcium hypochlorite composition of the present invention, i.e., a sanitized aqueous stream or sanitized body of water, may be used in any number of applications, e.g., as cooling tower water, swimming pools or to sanitize the surface of an article. When used to sanitize the surface of an article, the sanitized aqueous stream or a sanitized aqueous stream drawn from the sanitized body of water, 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. Examples of surfaces or articles to which the sanitized aqueous stream may be applied include, but are not limited to, metal surfaces in meat and food processing plants; and equipment in breweries, e.g., fermenting tubs, and the interior and exterior of pipes .

Solid, e.g., particulate, 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 the solid shaped article is to be used. In the case of a solid shaped article in the form of a tablet having a mass of 300 grams, it is preferred that 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 have a thickness of 2.5 cm (1 inch) to 5.1 cm (2 inches), e.g., 3.2 cm (1.25 inches), inclusive of the recited values. Particularly suitable for use in producing solid shaped articles is granular calcium hypochlorite having a size distribution predominantly between 45 and 10 mesh ASTM E-11 ASD, i.e., the granules are principally between on average 0.36 mm (0.014 inches) and 2.00 mm (0.08 inches). Particles smaller than 50 mesh ASTM E-11 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 particle size distribution of the hydrated borate salt and aluminum salt are each preferably the same as that of the granular calcium hypochlorite, i.e., between 45 and 10 mesh ASTM E-11 ASD.

The present invention is more particularly described in the examples that follow, which are intended to be illustrative only, since numerous modifications and variations therein will be apparent to those skilled in the art. Unless otherwise specified, all parts and percentages are by weight. Examples 1 through 8 describe calcium hypochlorite compositions, of which Examples 1 through 6 are comparative compositions, and Examples 7 and 8 are compositions according to the present invention. The ingredients of the compositions of Examples 1 through 8 are enumerated in Table 1. Physical data obtained from the calcium hypochlorite compositions is summarized in Tables 2 through 4.

As presented in Table 3, oxidizer classifications were assigned in accordance with the October 1, 1997 edition of 49 CFR §173.127 (a) (1) . Oxidizer classifications were made by comparing burn test data of test samples and reference samples . Burn test data were generated according to the test method and procedures as detailed in section 34 of the Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria, second revised edition, United Nations 1995, ISBN 92-1-139049-4. The burn test evaluation is summarized as follows. A 30 cm length of nickel-chromium wire having a diameter of 0.6 + 0.05 mm and a resistivity of 6.0 + 0.5 ohms / meter was laid in a serpentine fashion over a circular area of 38.5 square centimeters (cm2) on a 15 cm x 15 cm x 1.2 cm cement block. The wire was held in place by two electrically conductive screw-type contacts, located outside of the 38.5 cm2 circular area. A 30 gram homogeneously mixed reference sample was prepared from potassium bromate and cellulose in a weight ratio of 3 : 7 respectively. The potassium bromate and cellulose were mixed together by hand in a small glass beaker using a spatula. The potassium bromate used had a purity of 99 % by weight, and was obtained commercially from Fisher Scientific, catalog number P207-250. The cellulose used was in the form a medium fiber powder having a Whatman® advanced ion exchange cellulose designation of CF-11, available commercially from Fisher Scientific (catalog number 05-713- 004) , and was stored under controlled conditions such that it had a water content of between 0.05 % and 0.5 % by weight, based on total weight.

To a 60° conical glass funnel, having a large end diameter of 70 mm and a sealed small end, was added 30 grams of the reference sample. The 38.5 cm2 circular area of the cement block having the wire fixed thereto, was placed over the 70 mm diameter opening of the filled funnel. The cement block and funnel were together flipped over such that the funnel sat in an inverted fashion upon the block. The funnel was lifted away leaving a conical pile of reference sample over the nickel-chromium wire to which was applied an alternating current sufficient to provide 150 ± 7 Watts of power. Current was applied to the wire throughout the duration of the test or for a maximum of three minutes if no burning of the sample was observed. Burn times were taken from the moment power was applied to the wire until the sample was observed to stop burning. The burn time for the reference sample was taken from the average of five separate burn tests, which were performed under ambient atmospheric conditions. To minimize subjective influences on the results of the burn tests, a separate set of reference sample burn times were generated every time a set of test samples was evaluated.

Homogeneously mixed test samples of calcium hypochlorite compositions and cellulose were prepared in 30 gram amounts in ratios of 4 : 1 and 1 : 1 respectively. The test samples were evaluated in the same manner as the reference sample. For a given test sample, the shorter of the average observed burn times for either the 4 : 1 or 1 : 1 ratios were compared to the burn time of the reference sample. Based on this comparison, it was determined whether a given test sample, i.e., a calcium hypochlorite composition, would be classified as a Division 5.1 oxidizer. If the average burn time of a test sample was observed to be less than or equal to that of the reference sample, then the test sample was classified as a Division 5.1 oxidizer. Correspondingly, if the average burn time of a test sample was observed to be greater than that of the reference sample, then the test sample was not classified as a Division 5.1 oxidizer.

Table 1

Example

Ingredients 4 5

Parts Calcium hypochlorite a 100 56 70.5 % FAC

Parts Calcium hypochlorite a 100 75 75 75 75 . 0 0 73.3 % FAC

Parts Calcium Hypochlorite a 68 . 1 72 . 1 % FAC

Parts NaCl 44 25

Parts Na2B4O7»10H20 25 18.8 27.0

Parts A12 (S04) 3»18H20 25 6.2 Parts Anhydrous Al, (SO. c2 4.9

% FAC α by weight 70.5 73 39 55 55 55 55 49

a Granular calcium hypochlorite, 98 % by weight of which had a particle size of from 60 to 18 mesh ASTM E-11 ASD. The granular calcium hypochlorite used had an FAC content, as indicated, of 70.5 %, 73.3 % or 72.1 % by weight, based on total weight, and each contained from 5.5 % to 8.5 % by weight of water, based on total weight. b Disodium tetraborate decahydrate was obtained commercially from U.S. Borax Inc. cl Aluminum sulfate octadecahydrate was obtained commercially from Fisher Scientific, catalog number A613-500. c2 Anhydrous aluminum sulfate was obtained commercially from GEO Specialty Chemicals. d The free available chlorine (FAC) content of each composition as shown is a theoretical value, which was calculated based on the FAC content of the granular calcium hypochlorite used.

The calcium hypochlorite compositions of Table 1 were prepared by adding the ingredients to a beaker and mixing them by hand using a stainless steal spatula. The compositions were mixed by hand until they were observed visually to be substantially homogenous.

Table 2

Stability and pH Data Example Test 2 4 5 6 7 Accelerated aging e

% loss of FAC N . D . * 7 . 6 8 . 9 77 . 8 10 . 7 pH of a 2 . 8 weight % aqueous solution £ 11 . 4 11 . 4 9 . 2 5 . 6 8 . 8

N.D. = Not Determined e Accelerated aging was determined by exposing 28 grams of each composition, contained in a sealed 2 ounce glass jar, to a temperature of 45 °C for 6 days in an electric oven. Initial and final FAC values were measured before and after removing the test samples from the oven, respectively. The FAC values were determined analytically using a standardized method, comprising the sodium thiosulfate titration of iodine liberated from the addition of acetic acid and excess potassium iodide to a known weight of calcium hypochlorite composition. The percent loss of FAC was calculated using the following equation: 100 X ((Initial FAC - Final FAC ) / (Initial FAC)). Lower values of % loss of FAC are desirable.

£ The aqueous solutions containing 2.8 % by weight, based on total weight, of the respective calcium hypochlorite compositions were prepared using deionized water, and pH values were obtained at room temperature . Table 3

Oxidizer Classification Results

3 : 7 h Test Sample to Test Sample Reference Division Cellulose Burn Time Sample 5.1

Example Weight Ratio 9 (seconds) Burn Time (sec) Oxidizer?1 — 4 : i Ϊ2 80 Yes

1 1 : 1 71

3 4 : 1 37 80 Yes 3 1 : 1 204

5 4 : 1 153 144 N.C.j

5 1 : 1 460

6 4 : 1 45 80 Yes

6 1 : 1 N.D. 7 4 : 1 151 144 N.C.

7 1 : 1 417

8 4 : 1 102 67 N.C. 8 1 : 1 299

9 The test sample weight ratios shown are given as calcium hypochlorite composition to cellulose. h These are the average burn times observed for the 3 : 7 potassium bromate to cellulose reference samples, and were used to determine if the test sample in question was a Division 5.1 oxidizer.

1 According to 49 CFR §173.127 (a) (1). j N.C. = Not Classified, i.e., the test sample was observed to have a burn time greater than that of the 3 : 7 potassium bromate to cellulose reference sample.

Table 4

Flocculation Test Results k Examples 1 7

Volume of solids settled out (ml) 0 3

Time at which visual clarity was observed (minutes) m N.A. n 120

k The flocculation test was performed by taking 1000 ml of swimming pool water containing about 1 ppm FAC, and adding to it an amount of calcium hypochlorite composition sufficient to increase the FAC content of the water by 800 ppm. The calcium hypochlorite composition and 1000 ml sample of swimming pool water were mixed together using a magnetic stir bar for a period of 3 minutes at ambient temperature, and then transferred to a 1000 ml Imhoff cone. Upon transfer to the Imhoff cone, observations were taken periodically over 120 minutes . λ The volume of solids settled out was determined by visually reading the graduated scale on the side of the Imhoff cone. The values listed were noted at the conclusion of the flocculation test. m During periodic observations of the Imhoff cone, the time at which the water was observed to become visually clear was noted. n Not applicable. The calcium hypochlorite sample corresponding to Example 1 was observed to contain finely divided suspended solids throughout the duration of the flocculation test and did not become visually clear.

The data of Tables 2 through 4 taken together shows that compositions according to the present invention, i.e., as represented by Examples 7 and 8, are not classified as a Division 5.1 oxidizer, and with particular reference to Example 7 also have a desirable balance of: stability with regard to FAC loss; pH in aqueous solution; and flocculation characteristics .

The present invention has been described with reference to specific details of particular embodiments thereof. It is not intended that such details be regarded as limitations upon the scope of the invention except insofar as and to the extent that they are included in the accompanying claims .

Claims

We Claim :
1. A non-oxidizer classified solid calcium hypochlorite composition comprising an admixture of solid: (a) calcium hypochlorite; (b) hydrated borate salt; and
(c) aluminum salt selected from the group consisting of hydrated aluminum sulfate, hydrated aluminum alkali metal mixed salt sulfate, hydrated aluminum halide, anhydrous aluminum sulfate, anhydrous aluminum alkali metal mixed salt sulfate, anhydrous aluminum halide and mixtures thereof, wherein said calcium hypochlorite is present in an amount sufficient to provide a free available chlorine content that would result in said solid composition being classified as an oxidizer in the absence of (b) and (c) , said aluminum salt being present in at least a flocculating amount, and said hydrated borate salt being present in an amount at least sufficient to neutralize 100 % of said aluminum salt.
2. The solid composition of claim 1 wherein said calcium hypochlorite provides from 39 % to 75 % by weight free available chlorine, based on the total weight of said composition.
3. The solid composition of claim 2 wherein said calcium hypochlorite provides from 45 % to 65 % by weight free available chlorine, based on the total weight of said composition.
4. The solid composition of claim 1 wherein said hydrated borate salt is hydrated alkali metal tetraborate.
5. The solid composition of claim 4 wherein said hydrated alkali metal tetraborate is selected from the group consisting of dipotassium tetraborate tetrahydrate, disodium tetraborate tetrahydrate, disodium tetraborate pentahydrate, disodium tetraborate octahydrate, disodium tetraborate decahydrate and mixtures thereof .
6. The solid composition of claim 1 wherein said aluminum salt is selected from the group consisting of hydrated aluminum sulfate, anhydrous aluminum sulfate and mixtures thereof.
7. The solid composition of claim 1 further comprising at least an effective amount of anti-caking additive.
8. The solid composition of claim 7 wherein said anti- caking additive is selected from the group consisting of alkaline earth metal silicates, aluminum alkaline earth metal silicates, alkali metal aluminosilicates, alkali metal alkaline earth metal aluminosilicates, precipitated silica and mixtures thereof.
9. The solid composition of claim 1 wherein at least 80 percent by weight of said calcium hypochlorite, based on the total weight of said calcium hypochlorite has particle sizes between 60 mesh and 25 mesh; less than 10 percent by weight of said calcium hypochlorite, based on the total weight of said calcium hypochlorite has particle sizes greater than 25 mesh; and less than 10 percent by weight of said calcium hypochlorite, based on the total weight of said calcium hypochlorite has particle sizes less than 60 mesh.
10. A non-oxidizer classified solid calcium hypochlorite composition comprising an admixture of solid:
(a) calcium hypochlorite; (b) hydrated alkali metal tetraborate; and
(c) aluminum salt selected from the group consisting of hydrated aluminum sulfate, anhydrous aluminum sulfate and mixtures thereof, wherein said calcium hypochlorite is present in an amount sufficient to provide a free available chlorine content that would result in said solid composition being classified as an oxidizer in the absence of (b) and (c) , said aluminum salt being present in at least a flocculating amount, and said hydrated alkali metal tetraborate being present in an amount at least sufficient to neutralize 100 % of said aluminum salt.
11. The solid composition of claim 10 wherein said calcium hypochlorite provides from 39 % to 75 % by weight free available chlorine, based on the total weight of said composition.
12. The solid composition of claim 11 wherein said calcium hypochlorite provides from 45 % to 65 % by weight free available chlorine, based on the total weight of said composition.
13. The solid composition of claim 12 wherein the molar ratio of said hydrated alkali metal tetraborate to said aluminum salt is from 3 : 1 to 18 : 1.
14. The solid composition of claim 13 wherein said hydrated alkali metal tetraborate is selected from the group consisting of dipotassium tetraborate tetrahydrate, disodium tetraborate tetrahydrate, disodium tetraborate pentahydrate, disodium tetraborate octahydrate, disodium tetraborate decahydrate and mixtures thereof .
15. The solid composition of claim 14 wherein said hydrated alkali metal tetraborate is disodium tetraborate decahydrate, said aluminum salt is selected from aluminum sulfate octadecahydrate, anhydrous aluminum sulfate and mixtures thereof, and the molar ratio of said hydrated alkali metal tetraborate to said aluminum salt is from 3.5 : 1 to 9 : 1.
16. The solid composition of claim 10 further comprising at least an effective amount of anti-caking additive.
17. The solid composition of claim 10 wherein at least 90 percent by weight of said calcium hypochlorite, based on the total weight of said calcium hypochlorite has particle sizes between 60 mesh and 25 mesh; less than 5 percent by weight of said calcium hypochlorite, based on the total weight of said calcium hypochlorite has particle sizes greater than 25 mesh; and less than 5 percent by weight of said calcium hypochlorite, based on the total weight of said calcium hypochlorite has particle sizes less than 60 mesh.
18. A non-oxidizer classified solid shaped article comprising an article formed from an admixture comprising particulate : (a) calcium hypochlorite;
(b) hydrated borate salt; and
(c) aluminum salt selected from the group consisting of hydrated aluminum sulfate, hydrated aluminum alkali metal mixed salt sulfate, hydrated aluminum halide, anhydrous aluminum sulfate, anhydrous aluminum alkali metal mixed salt sulfate, anhydrous aluminum halide and mixtures thereof, wherein said calcium hypochlorite is present in an amount sufficient to provide a free available chlorine content that would result in said solid composition being classified as an oxidizer in the absence of (b) and (c) , said aluminum salt being present in at least a flocculating amount, and said hydrated borate salt being present in an amount at least sufficient to neutralize 100 % of said aluminum salt.
19. The solid shaped article of claim 18 wherein said calcium hypochlorite provides from 45 % to 65 % by weight free available chlorine, based on the total weight of said composition.
20. The solid shaped article of claim 19 wherein said hydrated borate salt is hydrated alkali metal tetraborate selected from the group consisting of dipotassium tetraborate tetrahydrate, disodium tetraborate tetrahydrate, disodium tetraborate pentahydrate, disodium tetraborate octahydrate, disodium tetraborate decahydrate and mixtures thereof, and said aluminum salt is selected from the group consisting of hydrated aluminum sulfate, anhydrous aluminum sulfate and mixtures thereof.
21. The solid shaped article of claim 20 wherein said aluminum salt is selected from the group consisting of aluminum sulfate octadecahydrate, anhydrous aluminum sulfate and mixtures thereof, and the molar ratio of said hydrated borate salt to said aluminum salt is from 3 : 1 to 18 : 1.
22. The solid shaped article of claim 18 wherein said solid shaped article is in the form of a tablet.
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US7045077B2 (en) 2004-06-18 2006-05-16 Biolab, Inc. Calcium hypochlorite compositions
US7923036B2 (en) 2008-09-30 2011-04-12 Ppg Industries Ohio, Inc. Halogen-containing sanitizing composition
US8257748B2 (en) 2009-09-01 2012-09-04 Ppg Industries Ohio, Inc. Calcium hypochlorite compositions
US8920743B2 (en) 2011-04-06 2014-12-30 The Clorox Company Faucet mountable water conditioning devices

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US4146676A (en) * 1975-03-12 1979-03-27 Olin Corporation Granular calcium hypochlorite coated with a low melting inorganic salt by spray graining

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US4146676A (en) * 1975-03-12 1979-03-27 Olin Corporation Granular calcium hypochlorite coated with a low melting inorganic salt by spray graining

Cited By (8)

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Publication number Priority date Publication date Assignee Title
US7045077B2 (en) 2004-06-18 2006-05-16 Biolab, Inc. Calcium hypochlorite compositions
EP1781567A1 (en) * 2004-06-18 2007-05-09 Bio-Lab, Inc Calcium hypochlorite compositions
US7364669B2 (en) 2004-06-18 2008-04-29 Bio-Lab, Inc. Method for reducing reactivity of calcium hypochlorite
EP1781567A4 (en) * 2004-06-18 2011-06-22 Bio Lab Inc Calcium hypochlorite compositions
US7923036B2 (en) 2008-09-30 2011-04-12 Ppg Industries Ohio, Inc. Halogen-containing sanitizing composition
US8257748B2 (en) 2009-09-01 2012-09-04 Ppg Industries Ohio, Inc. Calcium hypochlorite compositions
US8920743B2 (en) 2011-04-06 2014-12-30 The Clorox Company Faucet mountable water conditioning devices
US8955536B2 (en) 2011-04-06 2015-02-17 The Clorox Company Faucet mountable water conditioning systems

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