dear:

     S element in limestone change to SO2 from the mill to the cylclone 2. most of S in limestone are FeS2 and some organics containing S element.

     We have do some research of S's circle in cement industry.

     If you would want to discuss more details, you could cantact me.My email is xinyutatala@126.com. I work for Tianjin cement industry design and research inistiture in China.

 The attachments is S's circle in kiln in Chinses language.