Calcium Hypochlorite (Ca(OCl)2) is an inorganic compound, marketed as granules or tablets, used for water treatment and as bleaching agent due the very high content of available chlorine, 65-70%, greater than sodium hypochlorite.
Calcium hypochlorite production process basically consists of hydrated lime reaction with gaseous chlorine.
Consito developed know-how and technologies for Calcium Hypochlorite production units.
OVERCHLOR® is our Calcium Hypochlorite production plant according to the patented process developed by Consito, which minimizes the caustic soda consumption.
The process has been designed to minimize the consumption of caustic soda and is patented, as per excerpt below.
Calcium hypochlorite production process basically consists of hydrated lime reaction with gaseous chlorine, according to complete reaction:
Raw materials are hydrated lime and gaseous chlorine.
An acqueous suspension of milk lime is fed to the first reactor, where the chlorination takes place.
Temperature is kept constant and the reaction heat is taken away by cooling water circulation through an external jacket.
The chlorine flow is controlled in order to obtain a prefixed conversion rate.
The product discharged from the first reactor is centrifuged in order to separate mother waters, rich of chlorides, from the solid which mainly contains dibasic hypochlorite.
The solid is, then, suspended again in water. It is introduced too a small quantity of NaOH solution.
The new suspension is fed to a 2nd reactor where the final stage of chlorination takes place. The reaction is guided at low temperature by means of cooling, till the maximum conversion rate, in correspondence of maximum percentage of hypochlorite in the suspension.
The product discharged from the reactor is filtered; the separated mother liquors, containing valuable percentage of hypochlorite, are recycled to the preparation tank of 1st stage chlorination.
The filtered solid is washed and discharged into a re-slurry tank where water is added to prepare a pumpable slurry to be fed into a spray-dryer.
The drying takes place at controlled temperature in order to avoid decomposition.
The dried product is finally stored, weighed and packed.
Typical final product quality:
| Hydrated lime | ||
|---|---|---|
| Ca(OH)2 content | % min | 97 |
| CaCO3 | % max | 1.5 |
| metallic oxides | % max | 0.5 |
| Hydrated lime | ||
| calcium hypo | % | 5.0 |
| calcium chloride | % | 20 |
| calcium chlorate | % | 3.5 |
| sodium chloride | % | 2.5 |
| water | % | 69 |
| Hydrated lime | ||
| Ca(OCl)2 | % min | 70 |
| moisture | % max | 15 |
| Ca(OH)2 | % max | 5 |
| CaCl2 | % max | 8 |
| CaCO3 | % max | 5 |
| others | % max | 2 |
| density | kg/dm3 | 2.3 |
| bulk density | kg/dm3 | 0.5 |
| appearance | white powder | |
Typical main raw material and utility consumptions:
Referred to 1 metric ton of finished product:
| Feedstock & utilities | ||
|---|---|---|
| Chlorine 100% | kg | 1,150 |
| Hydrated lime | kg | 1,150 |
| Caustic soda 100% | kg | 60 |
| Process water | m3 | 3.3 |
| Cooling water | m3 | 80 |
| Compressed air | Nm3 | |
| Steam | kg | 808700 |
| Electric power | kWh | 450 |
| Bleach liquor | kg | 3,000 |
Algicide, bactericide, deodorant, disinfectant, fungicide; in sugar refining; oxidizing agent; bleaching agent.