Fire extinguishers cannot be put into your household recycling bin.
However you can take them to larger household waste recycling centres for disposal. Please check with your local council to see if they accept fire extinuishers.
Fire extinguishers are classified as hazardous waste and need to be disposed of carefully. For safety reasons, most councils ask for the handles to be securely taped together or the safety pin to be in place. CO2 types should have the swivel horn in place or a blanking plate fitted.