| 摘要 |
The rubble, e.g. excavated from a trench and comprising a mixture of earth, stones, brick and bitumen-bound materials, is fed into a first crusher (8). The output material (11) from the first crusher is passed through riddles (16) to produce one fraction (12) with a granular size equal to or smaller than the maximum granular size for back-filling material, while the other reaction (13) is fed into a second crusher (9) which reduces its granular size, and then goes back to the riddles. The material issuing from the first crusher can be subjected to a metal-extraction process, and both slots of crushed and riddled material are mixed together prior to re-use as back-filling, if necessary after an appropriate storage time.
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