Loam backfill device for pull-back fluidized mining of natural gas hydrate

The invention discloses a loam backfill device for pull-back fluidized mining of natural gas hydrate, which comprises a separator, a loam channel, a flange disk, a sand conveying pipe, and a sand discharging hole; the sand discharging pipe in the separator is connected to an inner opening of the loam channel in a straight channel, an outer opening of the loam channel in the straight channel is linked to the upper end of the sand conveying pipe through the flange disk; the lower end of the sand conveying pipe is linked with an outer opening of the loam channel of a collecting cylinder through aflange disk, the inner opening of the loam channel of the collecting cylinder is connected with the sand discharging hole at the inner part of a drill bit, the separated loam can backfill to the bottom part through the channel. The loam backfill device has beneficial effects that (1) the loam conveying channel is arranged to prevent a well wall from blockage for the loam is directly discharged; (2), the device can avoid