The foam separation of metal in model wastewater is performed by using two different bubble columns in a continuous operation mode. The equipment and operation conditions are changed, and the foam flow rate and metal concentration in foam flow are measured. The foam flow ratio (the ratio of foam flow rate to the inlet one) increases with increasing gas velocity, with decreasing liquid velocity, with decreasing foam layer height and with decreasing metal concentration in model wastewater. Metal enrichment (the ratio of metal concentration in foam flow to that in inlet flow) shows the reverse tendencies. When a draft tube is inserted in the bubbling layer, the foam flow rate decreases. The enrichment is strongly governed by the foam flow ratio. Since the foam flow ratio is adjusted by means of the equipment and operation conditions, the metal concentration in foam flow is controlled to be a desired value.