Abstract A series of silane-containing polymers with specific characteristics has been developed for complete elimination of sodalite scale in Bayer process. With practical dosages of those reagents effective protection against scale has been demonstrated in an alumina pilot plant and subsequently in several production plants. No negative effects were observed on the throughput as well as the quality of alumina produced with the use of those reagents. It is believed that the reagents are adsorbed onto red mud solids and are removed subsequently with red mud in filtration step. A possible mechanism of scale inhibition by the reagents was proposed.