Calcium hypochlorite composition containing magnesium and process for making same

• US 4,108,792 A
• Filed: 03/25/1977
• Issued: 08/22/1978
• Est. Priority Date: 03/25/1977
• Status: Expired due to Term

• Current Assignee: OLIN Corporation
• Original Assignee: OLIN Corporation
• Inventors: Wojtowicz, John A., Farmer, Jr., Douglas A.
• Primary Examiner(s): Padgett, Benjamin R.
• Assistant Examiner(s): Gluck, Irwin
• Application Number:
  US05/781,372
• Time in Patent Office: 515 Days
• Field of Search: 252/187 H, 252/95, 252/99, 8/108 R, 8/108 A, 423/474, 424/149
• US Class Current: 252/187.29
• CPC Class Codes: C01B 11/06 Hypochlorites
• CPC Class Codes: C01B 11/064 Hypochlorites of alkaline-earth metals

Abstract

The present invention describes a solid calcium hypochlorite composition comprising calcium hypochlorite and about 0.5% to about 50% by weight of substantially water-insoluble and unchlorinated magnesium compounds, said magnesium compounds being derived from impure hydrated lime. Furthermore, the present invention describes a process for making this composition, which is an improvement in the known process for the manufacture of a solid calcium hypochlorite composition wherein an aqueous slurry comprising a hydrated lime, a mixture of hydrated lime and at least one alkali metal hydroxide, or a mixture of hydrated lime and at least one alkali metal hypochlorite, is chlorinated to form an aqueous chlorinated slurry containing calcium hypochlorite and further processing said chlorinated slurry to recover a solid calcium hypochlorite composition.

Claims

1. In a process for the manufacture of a solid calcium hypochlorite composition wherein an aqueous slurry comprising hydrated lime is chlorinated to form an aqueous chlorinated slurry containing calcium hypochlorite and further processing said chlorinated slurry to recover a solid calcium hypochlorite composition, the improvement which comprises:

(a) employing a hydrated lime having about 97% to about 50% by weight calcium hydroxide and more than about 0.5% by weight magnesium based on the total dry weight of said hydrated lime,

(b) terminating said chlorination reaction when from about 75% to about 99.5% by weight of said calcium hydroxide is chlorinated and from 0% to about 5% by weight of said magnesium is chlorinated to form an aqueous chlorinated slurry containing substantially water-insoluble and unchlorinated magnesium compounds and calcium hypochlorite, and

(c) further processing said chlorinated slurry to remove a solid calcium hypochlorite composition having admixed therein said substantially water-insoluble and unchlorinated magnesium compounds.

2. The process of claim 1 wherein said aqueous slurry is selected from the group consisting essentially of hydrated lime, a mixture hydrated lime and at least one alkali metal hydroxide and a mixture of hydrated lime and at least one alkali metal hypochlorite.

3. The process of claim 2 wherein said aqueous slurry is a mixture of said hydrated lime as defined in (a) and sodium hydroxide.

4. The process of claim 2 wherein said aqueous slurry is a mixture of said hydrated lime as defined in (a) and sodium hypochlorite.

5. The process of claim 4 wherein said chlorination reaction is carried out at a temperature below 30°

C and the triple salt - Ca(OCl)₂.NaOCl.NaCl.12H₂ O - is formed.

6. The process of claim 1 wherein said chlorination reaction is terminated when at least about 90% by weight of said calcium hydroxide is chlorinated and from less than about 2.5% by weight of said magnesium is chlorinated.

7. The process of claim 1 wherein said chlorinated slurry is further processed which comprises drying said chlorinated slurry to reduce the water content to the range of from about 0.1% to about 15% by weight of the composition.

8. A solid calcium hypochlorite composition comprising calcium hypochlorite and about 0.5 to about 50% by weight substantially water-insoluble and unchlorinated magnesium compounds derived from hydrated limes.

9. A composition of claim 8 wherein the amount of said calcium hypochlorite is at least about 60% by weight of the composition and the amount of said magnesium compounds is from 0.5% to about 10% by weight of the composition.

10. A composition of claim 8 wherein the amount of said calcium hypochlorite is less than about 30% by weight of the composition and the amount of said magnesium compounds is from about 10% to about 50% by weight of the composition.