Mobile phones are a fire risk and should never be disposed of in any of your household bins.
Other recycling options:
Mobile phones can be taken to local Household Waste Recycling Centre in the 'electrical items' container.
Mobile phones contain precious metals which take huge amounts of energy and environmental destruction to mine.
They often have a monetary value and many charities, and some schools, collect unwanted phones which are sold on for reuse, refurbishment or recycling.
Alternatively use one of the many online companies who will send a freepost envelope to recycle your mobile phone and possibly give you money too.