Underground coal hypergravity field separation system and separation process

A coal separation process based on the underground coal hypergravity field separation system, comprising the following steps:

• raw coal screening and breaking, the raw coal screening and breaking comprising:
• adopting a 6 mm screening standard for raw coal;
• conveying an undersized product smaller than 6 mm to a grading hydrocyclone group;
• conveying an oversized product greater than or equal to 6 mm to a crushing machine;
• crushing the oversized product into particles smaller than 6 mm;
• and
• returning the particles to a screening process;
• raw coal grading comprising:
• conveying the raw coal smaller than 6 mm to the grading hydrocyclone group;
• taking 1 mm as a grading standard;
• discharging coarse particles of 1-6 mm from an underflow port of the grading hydrocyclone group;
• conveying the particles to a hypergravity field separator corresponding to the underflow port;
• discharging a fine particle product smaller than 1 mm from an overflow port of the grading hydrocyclone group;
• and
• conveying the particles to a hypergravity field separator corresponding to the overflow port;
• raw coal separation comprising:
• feeding the raw coal smaller than 1 mm into a rotating drum of the hypergravity field separator corresponding to the overflow port of the grading hydrocyclone group at a certain pressure along a tangential direction through a feeding pump;
• feeding the raw coal of 1-6 mm into the rotating drum of the hypergravity field separator corresponding to the underflow port of the grading hydrocyclone group at a certain pressure along a tangential direction through a feeding pump so that a material forms descending spiral flow along an inner wall at an upper part of the rotating drum and medium-density and high-density materials descend along outer spiral flow under the action of a centrifugal force to form upward inner spiral flow at an axis of the rotating drum due to a negative pressure, where the low-density material ascends along the inner spiral flow and is discharged through a floating object discharging port, the medium-density and high-density materials are accelerated by a high-speed rotor when descending to the bottom of the rotating drum along the outer spiral flow, the high-density material continues going downward along the inner wall under an action of an additional strong centrifugal force in a hypergravity field and is discharged through a sediment discharging port, and the medium-density material goes upward along the inner spiral flow and is discharged through a floating object discharging port;
• and
• dehydrating a product by respectively conveying clean coal and gangue obtained by separation to dehydration treatment.