MASS BALANCE Question 6 In a casein plant the entering coagulum containing casein and lactose is passed through two cookers and acidified to remove the casein. The curd is removed from the whey by screening and then washed and dried. The casein fines are removed from the whey and the wash water by hydrocyclones and mixed with the heated coagulum just before the screen. The whey is used for heating the first cooker and steam for the second by indirect methods. Some of the more accessible streams have been sampled and analysed for casein and lactose; the remainder of the steam can be assumed to be water without significantly effecting the results. In addition the moisture content of the final dried product has been determined. % Composition on a weight bases Casein Lactose Moisture Coagulum 2.76 3.68 Whey (raw) 0.012 4.1 Whey (cyclone) 0.007 4.1 Wash water 0.026 0.8 Waste wash water 0.008 0.8 Dried product 11.9 From this data calculate a complete mass balance for the process using simple step by step approach, starting with the hydrocylones. Assume that the lactose is completely soluble in all streams and concentrations are the same. a. Draw up and fill in the following table (27 marks) Mass Flow Kgh-1 Casein Lactose Total Coagulum + Fines mixed Mixed fines Dewheyed curd Raw whey Whey fines stream Waste wash water Wash water fines Pressed curd Dried Product b. What % of the casein going into the screen is recovered fines? (3 marks) c. What % recovery efficiencies do the two sets of hydro-cyclones display? (3 marks) d. What are the % compositions of the pressed curd and the dried product? (3 marks)