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AU601373B2 - Hydrated calcium hypochlorite tablets containing lime compounds as lubricants and solubility retardants - Google Patents
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AU601373B2 - Hydrated calcium hypochlorite tablets containing lime compounds as lubricants and solubility retardants - Google Patents

Hydrated calcium hypochlorite tablets containing lime compounds as lubricants and solubility retardants Download PDF

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Publication number
AU601373B2
AU601373B2 AU62375/86A AU6237586A AU601373B2 AU 601373 B2 AU601373 B2 AU 601373B2 AU 62375/86 A AU62375/86 A AU 62375/86A AU 6237586 A AU6237586 A AU 6237586A AU 601373 B2 AU601373 B2 AU 601373B2
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AU
Australia
Prior art keywords
calcium hypochlorite
percent
tablets
weight
hydrated calcium
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
AU62375/86A
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AU6237586A (en
Inventor
Frank Salvatore Natoli
John Alfred Wojtowicz
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Olin Corp
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Olin Corp
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Publication date
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Publication of AU6237586A publication Critical patent/AU6237586A/en
Application granted granted Critical
Publication of AU601373B2 publication Critical patent/AU601373B2/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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  • Agricultural Chemicals And Associated Chemicals (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)
  • Detergent Compositions (AREA)

Description

G CA, Z~XMAnp, jbdoUu !!iq619 p:)jo zI X,'YAnsNdONW1lrIHod3GJ)V'id Ot 11111
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1.15 1.25 1[4 4 AUSTRALIA 6 Paten ts Act 137 COMPLETE SPECIFICATION
(ORIGINAL)
Class Int. Class Application Number: CP S)V Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: APPLICANT'S REF.: Name(s) of Applicant(s): OLIN CORPORATION USSN 773-733 Address(es) of Applicant(s): P.O. Box 586, Cheshire, Corinectiout. 06410-0586.
UNITED STATES OF AMERICA, Actual Iiv~entor(s): Frank Salvaftore Natoli and John Alfred Wojtowicz Address for Service is: PHI LLIPS, ORMONDE AND FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne, Australia, 3000 Complete Specification for the invention entitled: HYDRATED CALCIUM HYPOCHLORITE TABLETS CONTAINING LIME COMPOUNDS AS LUBRICANTS AND SOLUBILITY RETARDANTS The following statement is i: f'1. description of this invention, including the bqst method of performing it known to applicant(s): P19 3'84 -la- C-9200 HYDRATED CALCIUM HYPOCHLORITE TABLETS CONTAINING LIME COMPOUNDS AS LUBRICANTS AND SOLUBILITY RETARDANTS This invention relates to chlorine-containing products for the sanitation of water bodies. More particularly the invention relates to tablets of hydrated calcium hypochlorite and the preparation thereof.
Calcium hypochlorite is a well known source of "available chlorine" for sanitation purposes, for example, in disinfecting water bodies such as swimming pools or waste streams. Calcium hypochlorite is added to the water to maintain a small residual of "available chlorine", which is generally sufficient to insure prompt destruction of bacterial contamination, so that the water is safe for swimming, bathing or disposal from sanitation treatment facilities.
Anhydrous calcium hypochlorite compositions having Ca(OC1) 2 concentrations of about 70 percent by weight have been commercially available in granular or tablet form to be added to the water body to provide the desired levels of available chlorine.
U.S. Patent 4,192,763 issued March 11, 1980 to P. W. W. Buchan describes a method of forming tablets by mixing calcium hypochlorite with chloride of lime and zinc stearate as a tabletting lubricant and pressing the mixture into a tablet. The tablets, containing from 5 to 15 percent chloride of lime and a minor amount of zinc stearate as a lubricating agent, have a decreased rate of dissolution in water.
Anhydrous calcium hypochlorite is used as water or moisture results in an accelerated decomposition rate fo, mixtures containing the hygroscopic chloride of lime.
A similar method of decreasing the solubility of calcium hypochlorite is described in Japanese Patent Publication No. 90404-1980 published on July 9, 1980.
Mixtures of calcium chloride and calcium hydroxide and anhydrous calcium hypochlorite are formed into tablets ini which Ca,1 2 is present at 3-4 percent by weight and the calcium hydroxide/calcium chloride weight ratio is 0.5 to 3.0. These amounts of CaCl2 Ca(OH) 2 are required to provide reduced S solubility for the tablets. The presence of water or moisture, however, would seriously effect the stability of these tablets.
Hydrated calcium hypochlorite compositions have been developed having a water content of 4 percent by weight or greater which are more resistant to ignition and exothermic decomposition than the anhydrous product. Tabletting of calcium hypochlorite i 30 having a water content of above 3 percent by weight cannot be accomplished efficiently in commercial tabletting apparatus as caking of the punches results in excessive wear of the equipment. Frequent shutdowns for maintenance of the equipment are required and product control with respect to both the uniformity and the appearance of the tablets is difficult to maintain.
3-- -3- One object of the present invention is to provide tablets of hydrated calcium hypochlorite compositions which can be produced commercially while minimizing costs and equipment wear.
Another object of the present invention is to provide a process for producing hydrated calcium hypochlorite tablets which are stable and have extended shelf life.
An additional object of the present invention is to provide a tablet of hydrated calcium hypochlorite composition having contxolled active chlorine release properties for santizing water supplies.
These and other objects of the present invention are accomplished in tablets for sanitizing water bodies consisting essentially of hydrated calcium hypochlorite admixed with a lime compound in amounts of from about 0.1 to about 3 percent by weight of the hydrated calcium hypochlorite.
The FIGURE is a graph illustrating the effect of calcium hydroxide on the solubility of hydrated caliium hypochlorite tablets in water.
Granules of solid, hydrated calcium hypochloriteLcontain from about 55 to about 75 percent e-c andkpreferably from about 65 to about 72 percent by 29 weight of calcium hypochlorite, Ca(OCl) 2 from about 4 to about 10 percent, and/preferably from about 5.5 to about 8.5 percent by weight of water; and from about 1 to about 3 percent by weight of calcium hydroxide, the balance being inert material usually resulting from the process of manufacture, e.g. sodium chloride, calcium chloride, agd calcium carbonate. The hydrated calcium 9( e QLtC hypochloritekhas a specific gravity of about 2.1 to about 2.2. Hydrated calcium hypochlorite particles of the type used in the present invention may be produced by known processes such as those described in U.S.
Patent No. 3,544,267, issued cn December 1, 1970 to G.
/T Rq R. Dychdala or U.S. Patent No. 3,669,894, issued on June 13, 1972 to J. P. Faust.
I_-
-4- Granules of hydrated calcium hypochlorite used in the tablets of the present invention are those which are normally produced commercially and have a particle size in the range of from about 150 to about 2,000 microns. I. The lime compound employed is calcium oxide, commercially available as quick lime; calcium hydroxide, commercially available as hydrated lime; and mixtures thereof.
I
9( I I I 4 4* 4.
A
10 The hydrated calcium hypochlorite particles are admixed with particles of a lime compound to produce mixtures containing amounts of the lime compound in the range of from about 0.1 to about 3 percent, and preferably from about 0,5 to about 2 percent by weight of the hydrated calcium hypochlorite. Larger amounts may be used if desired, however, they do not provide substantial increases in benefits with respect to cost.
As stated above, calcium hypochlorite may contain process calcium hydroxide as an integral part of the composition as calcium hydroxide is one of the raw materials commonly used in producing calcium hypochlorite. The presence, however, of process calcium hydroxide or lime in the calcium hypochlorite 25 suprisingly does not provide the beneficial results which are accomplished when calcium oxide or calcium hydroxide are admixed with the hydrated calcium hypochlorite granules in the amount disclosed above.
The hydrated hypochlorite granules are admixed with commercially available quick lime or hydrated lime to form a substantially homogeneous mixture. Any suitable means of admixing or blending the two components may be employed.
The mixture is then tabletted using commercially available tabletting machines. In
I
*tt 4 producing tablets, it has unexpectedly been found that a lubricating agent is not required as the lime compound provides excellent lubricating properties in the amounts used in the mixtures. Tablets produced from the mixtures of the present invention are readily released from the tabletting die. The novel tablets of the present invention, having an available chlorine content of from about 65 to about 70 percent, provide a controlled rate of dissolution in water which is substantially reduced over the rate of dissolution of hydrated calcium hypochlorite.
Further illustrations are provided by the following examples with no intention of being limited thereby. All percentages and parts are by weight unless otherwise indicated.
-6- EXAMPLE 1 Anhydrous calcium oxide was added to hydrated calcium hypochlorite granules in an amount of percent by weight of the hydrated calcium hypochlorite. The compounds were blended in a V-blender to provide a homogeneous mixture.
A stainless steel die [7.6 centimeters (3 inches) in diameter, No. 420C] and a punch were placed in a Wabash press and a sufficient amount of the hydrated calcium hypochlorite-calcium oxide mixture was added to produce six tablets at a tabletting pressure of 20 tons. The tablets (200 grams each) were released from the tabletting press without sticking to the die and the appearance of the tablets was excellent. No cleaning of the die was required during the tabletting operation.
Three of the tablets were placed in an errosion type dissolver where the water flow rate was gallons per minute and the temperature about 26.7°C (800F). The tablets were allowed to dissolve for 3.0 hours after which time the remainder of the tablets was removed, dried for 4.0 hours and weighed. The amount of dissolved Ca(OC1) 2 was calculated by subtracting the quantity of Ca(OC1) 2 remaining after the test from the initial weight. The tablets prepared with calcium oxide retained 68 percent of their original weight.
Comparative Example A The procedure of EXAMPLE 1 was repeated with the exceptions that hydrated calcium hypochlorite was tabletted in place of the mixture of hydrated calcium hypochlorite and calcium oxide, and the stainless steel die was coated with a sodium stearate solution as a -7lubricating agent. During the tabletting operation a significant quantity of hydrated calcium hypochlorite st'.ck to the die. The die had to be cleaned and coated with sodium stearate solution after each tablet was made otherwise the punch could not be removed.
The dissolving rate determination was repeated with three of the tablets containing only hydrated calcium hypochlorite. The tablets retained 42 percent of their original weight.
Using the novel tabletting composition of the present invention, the tablets dissolved at a reduced rate which was 38 percent slower than the hydrated calcium hypochlorite tablets of Comparative Example A.
EXAMPLES 2-4 Four homogeneous mixtures were made containing granular hydrated calcium hypochlorite and calcium hydroxide (reagent grade) where the calcium hydroxide was added in amounts of 0, 0.75, 1.5, and weight percent. The hydrated calcium hypochlorite had the following analysis: COMPONENT BY WEIGHT Ca(OC1) 2 66.5-66.6 Ca(C0O3)2 1.7-1.8 Ca(OH)2 1.8-2.0 CaCl2 4.5-5.2 CaCO 3 1.37 NaCl 16.2-18.2
H
2 0 6.8 Each mixture was tabletted at pressures of 17,000 pounds to produce tablets weighing 25.3 grams and having a diameter of about 2.54 centimeters (1.00 inch), a height of about 2.37 centimeters (0.93 inch), and a surface area of 29.05 square centimeters.
71 -8- Tablets of each mixture were placed in an open mesh basket and immersed in a tank of water having a temperature of 32 0 C where the water was slowly agitated. During the initial dissolution period of about three hou):s, the tablets were removed at time intervals of 0.5 to 1.0 hour, dried and weighed.
Tablets having 0 content of lime admixed dissolved at a rate of 0.53 grams per square centimeter of surface area per hour. Tablets having a Ca(OH) 2 content of 0.75 percent by weight dissolved at a rate of 0.40 grams per square centimeters per hour. Tablets having Ca(OH) 2 contents of 1.5 and 3.0 percent by weight had a dissolving rate of 0.32 and 0.243 grams per square centimeters per hour, respectively. The results are illustrated on the FIGURE.
EXAMPLES 5-7 Tablets weighing 275 grams and having a diameter of about 7.6 centimeters (3 inches) were produced from homogeneous mixtures of compacted granular calcium hypochlorite and lime where the lime was present in amounts of 0.5, 1.5 and 2.5 percent by weight. the calcim hypochlorite granules had the following analysis: COMPONENT BY WEIGHT Ca(OC1)2 69.5 Ca(OH)2 CaCC3 CaC1 2 ca Ca(C10 3 2 ca NaC1 ca 18.0
H
2 0 -9- The tablets were placed in a basket and submerged in a swimming pool skimmer having a water flow rate of 35 gallons per minute. The total time to dissolve the tablets was measured and found to be: OF LIME DISSOLVING TIME (HRS.) 11.5 2.5 15.0 Comparative Example B The procedure of EXAMPLES 5-7 was repeated using tablets of hydrated calcium hypochlorite which were identical to those used in EXAMPLES 5-7 except for the omission of lime. These tablets had a dissolving time of 6.0 hours.
m

Claims (7)

1. A water body sanitizing tablet comprising hydrated calcium hypochlorite admixed with a lime compound in amounts of from 0.1 to 3 percent by weight of said hydrated calcium hypochlorite and a water content of from 4 to 10 percent by weight, or--graa-er.
2. A tablet according to claim 1 in which said lime compound is selected from the group consisting of calcium oxide, calcium hydroxide and mixtures thereof,
3. A tablet according to any one of the previous claims in which said available chlorine content is from 55 to percent.
4. A tablet according to any one of the preceding claims in which said lime compound is present in amounts of from 0.5 to 2.0 percent by weight. o00 00 o o
5. A process of producing a tablet according to any one o0 of the previous claims which comprises admixing particles of hydrated calcium hypochlorite with particles of a lime compound to form a homogeneous mixture containing from 0.1 to 3 percent by weight of said lime compound, and compressing said homogeneous mixture to form tablets,
6. A tablet according to claim 1 as hereinbefore described with reference to examples 1 to 7.
7. A process according to claim 5 substantially as hereinbefore described with particular reference to examples 1 to 7. DATED: 25 June 1990 PHILLIPS ORMONDE FITZPATRICK Attorneys For: OLIN CORPORATION 4W (7512h) JC
AU62375/86A 1985-09-09 1986-09-05 Hydrated calcium hypochlorite tablets containing lime compounds as lubricants and solubility retardants Ceased AU601373B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US77373385A 1985-09-09 1985-09-09
US773733 1985-09-09

Publications (2)

Publication Number Publication Date
AU6237586A AU6237586A (en) 1987-03-12
AU601373B2 true AU601373B2 (en) 1990-09-13

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AU62375/86A Ceased AU601373B2 (en) 1985-09-09 1986-09-05 Hydrated calcium hypochlorite tablets containing lime compounds as lubricants and solubility retardants

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JP (1) JPS62123103A (en)
AU (1) AU601373B2 (en)
BR (1) BR8604277A (en)
CA (1) CA1274441C (en)
ZA (1) ZA866796B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU654091B2 (en) * 1990-07-06 1994-10-20 Lettela Proprietary Limited Screen panel fixing system

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU3314378A (en) * 1977-02-16 1979-08-16 Buchan P W W Chlorine tablet

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5241283B2 (en) * 1973-06-30 1977-10-18
EP0005286A1 (en) * 1978-04-18 1979-11-14 THE PROCTER & GAMBLE COMPANY Compact solid disinfecting composition containing a mixture of lithium hypochlorite and calcium hypochlorite

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU3314378A (en) * 1977-02-16 1979-08-16 Buchan P W W Chlorine tablet

Also Published As

Publication number Publication date
CA1274441A (en) 1990-09-25
AU6237586A (en) 1987-03-12
CA1274441C (en) 1990-09-25
BR8604277A (en) 1987-05-05
JPS62123103A (en) 1987-06-04
ZA866796B (en) 1987-05-27

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