The newly redesigned Lab Vertical Blender is intended for vacuum operation and includes a jacketed-vessel wall for heating or cooling. A special high-speed chopper is also provided in the bottom portion of the side wall to reduce agglomerates or to control the particle size of a granulate. The blender has an automatic raising and lowering mechanism to enhance the charging and discharging of raw materials. Sizes range from 1- to 500-cubic-feet capacity, and materials include stainless steel, carbon steel and special alloys.