Abstract: The control strategies include controlling the slurry concentration (SCON) by making an energy balance calculation around a slurry reactor and a material balance of liquid in, and liquid and solids out, of the reactor to determine the SCON. The feed rate of a diluent (hexane) stream into the reactor is adjusted to cause the SCON to approach or be at a target SCON. Further the control strategies include controlling the melt flow rate (MFR) by measuring the temperature and pressure in the slurry reactor and by gas chromatography, determining the ratio of hydrogen to propylene, calculating the MFR from a correlation developed from polypropylene process results from these parameters and then adjusting the feed rate of a hydrogen stream into the reactor to cause the MFR to approach or be at a target MFR which will yield a desired product of polypropylene.