Clay processing: which mixing device is vacuum-operated specifically to de-air (remove entrained air from) clay before shaping?
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ABanbury mixer
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BPug mill
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CMuller-mixer
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DNone of these
Answer
Correct Answer: Pug mill
Explanation
Introduction / Context:In ceramics and brick/tile manufacture, clay must be homogenized and free of entrained air before extrusion or pressing. Air pockets cause cracks, blistering, and dimensional defects during drying and firing.
Given Data / Assumptions:
- Industrial clay preparation prior to shaping.
- Focus on a device that operates under vacuum to deair.
Concept / Approach:A vacuum pug mill blends, kneads, and simultaneously removes entrained air by drawing vacuum in the mixing chamber. This produces plastic, uniform, air-free clay suitable for continuous extrusion.
Step-by-Step Solution:Identify equipment with both mixing and vacuum deairing functions → vacuum pug mill.Banbury and muller mixers are intensive mixers but typically lack integrated vacuum deairing for clay bodies.Therefore, select “Pug mill.”
Verification / Alternative check:Equipment suppliers for ceramic industry list “vacuum deairing pug mills” as standard just before extrusion.
Why Other Options Are Wrong:Banbury: designed for rubber/plastics compounding.Muller: sands/clay mixing without integrated vacuum deairing.None: incorrect because a standard device exists (pug mill).
Common Pitfalls:Ignoring vacuum level and throughput matching; insufficient moisture control which still traps air despite deairing.
Final Answer:Pug mill