A three-zone SMB was proposed to reduce the adsorbent usage, where zone I normally used to regenerate the adsorbent is discarded and the desorbent is directly pumped into zone II. An analysis on the movement of the concentration band indicates that the tail of the more retained solute is desorbed successively in zones II and IV, without overlapping with the front of the less retained solute in zone IV. As a result, the raffinate and extract product can be collected from the outlets of zones III and IV, respectively. The model simulations confirm that the three-zone SMB dropping zone I can lower the adsorbent usage and system pressure without losing the purity. In comparison with the four-zone SMB and another three-zone SMB dropping zone IV, the solvent consumption is lower than that by the latter, but higher than that by the former. The partial withdrawal operation can reduce the solvent consumption in the two SMBs without zone I and without zone IV. For anti-Langmuir isotherm dropping zone I is more effective than dropping zone IV.