Raw gypsum from a fertilizer plant is being leached out of its salt (NaCl) content in a 2-step continuous countercurrent system using salt-free water as leaching medium. The underflow, CaSO4 slurry is then sent to a drier to obtain the final product. The operating data are as follows:
Raw gypsum feed = 10 MT/day
Salt content of raw gypsum = 1 wt%
Water feed rate = 90 m3/day
Water content of slurry = 0.09 MT H2O per MT CaSO4
1. The percent of salt removed in the process is?
2. The resulting salt content in the overflow in weight percent is?
(90×100)÷100 = 90%