The request limits are shown on the bottom of the api page https://blockchain.info/api
Which you obviously cannot see if you are banned!
blockchain.info Request Limits:
Requests in 8 Hours: 1957 (Soft Limit = 28800, Hard Limit = 28900)
Requests in 5 minutes: 223 (Soft Limit = 700, Hard Limit = 725)
It is possible to bypass the request limiter using API with an API Key.
API key can be requested at http://blockchain.info/api/api_create_code