| 摘要 |
An air sifting or separating machine for dry separation of raw material, including a carrier member having openings and receiving material to be sifted or separated from a material feed mechanism, and a discharge mechanism for heavy material and light material layered on the carrier member during a sifting process. A pulsating air stream is passed through the carrier member to loosen up and layer the material fed to it. A control device for the discharge mechanism is operative via radiometrical measurement of the thickness of the material, and is comprised of a source of radiation mounted on a wall of the machine, and an associated scintillation unit that measures absorption of radiation given off by the source of radiation. The scintillation unit is disposed within a protective pipe freely mounted at a suitably set distance from the source of radiation and within a sifting or separating bed formed by the heavy material layer. The protective pipe is carried by the support mechanism connected to the machine and extending over the carrier member.
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