In this study a propane-propylene rectification column was investigated in terms of diameter of the column, number of trays, reflux ratio and the construction material costs of the column. During the calculations the reflux ratio was modified between 8 and 30. The chosen material of the column and trays was 1.4404 grade austenitic steel. The calculation has shown that with higher reflux ratio the diameter of the column and the number of trays were changing. Next, the necessary wall thickness of the shell of the column was determined with strength calculation. A material cost function was also determined with these parameters applying various reflux ratio values. From the results it can be concluded that the optimal reflux ratio is 12, because in this case the material cost function has a minimum point.