Economic analyses are presented for two conceptual casein plants of commercial scale. For the first analysis, costs were estimated for a plant that used CO2 as precipitant to manufacture casein. The results were compared with estimated costs for Ca caseinate plants. In the second analysis, costs were estimated for the precipitation step only for a casein plant that used CO2 as a precipitant.In the first case, the equipment was sized for a Ca caseinate plant with a flow rate of 10,000L of milk/h and a caseinate output of 320 kg/h. Unit operating costs for production of CO2-precipitated casein with recycling of CO2 were $0.038/kg less than for Ca caseinate manufactured from fresh casein and $0.103/kg less than for casein manufactured from dried casein.In the second case, operating costs for precipitation of casein with CO2 in a plant with a flow rate of 50,000L of milk/h and a casein output of 1500 kg/h are $0.095/kg more than with lactic acid or HCl if CO2 was not recycled. If CO2 was recycled, capital costs were increased, but operating costs were significantly reduced. With recycling of CO2, the cost difference between CO2-precipitated casein and the other caseins was $0.021/kg.