A professional who tends battery of digester vessels that dissolve bauxite in plant liquor. Respnsibilities include:

• Turns valves on pumps to transfer liquor and bauxite slurry through heaters into digester vessels.
• Turns valves to inject milk of lime into vessels.
• Adjusts pumps and valves to circulate cleaning solution through process lines.
• Collects samples of slurry and alumina solution for laboratory analysis.
• Keeps log of operations.