| 摘要 |
A cement-bonded particle board with finer particles concentrated at the surfaces of the board and coarser particles concentrated within the board is formed by spreading the particulate material onto a moving carrier (50), the particulate material initially being projected in a first generally horizontal direction above the carrier and allowed to fall gravitationally without interacting with any fixed surface, whilst the falling particles are subjected to a through-flow of air [B] immediately above the carrier in a second direction opposite to that in which the particles are initially projected, the coarser particles being projected preferentially in said first direction and the finer particles being carried preferentially in said second direction by the airstream [B] to effect a second stage of separation.
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