Utilisation of by-products of an integrated steel plant improves productivity with diverse mix of raw materials used for iron making. The strength of a briquette made with Blast furnace flue dust and iron oxide with fly ash as a binder depends upon the briquetting pressure, particle size of fly ash, fly ash quantity, and curing temperature. In this study, the effect of process variables on the strength was investigated with ANOVA. The correlation between the process parameters and the strength was examined experimentally and RSM-based optimisation was performed during the preparation of briquettes. The RSM provided optimisation with a confidence level of 95% using the CCD design. This paper demonstrates the correlation between applied pressure, particle size, fly ash quantity, and curing temperature. The developed mathematical model would help in predicting the variation in the compressive strength with the change in the level of different parameters. This model can be useful for setting the optimum value of the parameters for achieving the target compressive strength.