This disclosure relates generally to a method and system for predicting safe time of operation for a rotary kiln. Over the period of time, the rotary kiln develops a ring within the inner walls of the kiln and suffers sudden shut down due to choking of the kiln. State-of-the-art methods provide the various methods of predicting safe time of operation, but the prediction is based on limited features and hence suffers accuracy. The disclosed method predicts safe time of operation for a rotary kiln based on mathematical model that estimates size of ring by estimating plurality of derived parameters based on operational parameters and design parameters. The derived parameters are the estimations provided by a solid bed height variation model, a gas stream model, a solid stream, a melt model, an agglomeration model, a volatile model, and a ring formation model.