A large-span bulk material conveying system, comprising a folding arm conveyor and a dike-striding elevation-type conveying device, wherein the folding arm conveyor comprises three sections of conveying arms, a tower top (10), a balance arm (17), a tower body (24), an undercarriage (25), a windlass, wire ropes, portal frames and a limit apparatus;
- and the undercarriage (25) is fixedly mounted in a stockyard through foundation bolts, and the tower body (24) is also connected with the undercarriage (25) through bolts;
- the three sections of conveying arms are respectively a first conveying arm (7), a second conveying arm (4) and a third conveying arm (1);
- the first conveying arm (7) is mounted on the tower body (24) through a pin shaft;
- the second conveying arm (4) is connected to the first conveying arm (7) through a pin shaft;
- the third conveying arm (1) is connected to the second conveying arm through a pin shaft;
- the third conveying arm (1) is a trapezoidal structure, and the conveying arm is provided with an unloading trolley (9);
- the portal frame I (5) is mounted on one end (4) of the first conveying arm (7) close to the second conveying arm (4), and the limit apparatus I (6) is also mounted on the first conveying arm;
- the portal frame II (2) is mounted on one end of the third conveying arm (1) close to the second conveying arm (4), and the limit apparatus II (3) is also mounted on the third conveying arm;
- the balance arm (17) is mounted on the tower body (24) through a pin shaft;
- the tower top (10) is connected to the tower body (24) through bolts;
- and the windlass comprises a windlass I (21), a windlass II (20), a windlass III (19) and a windlass IV (18), which are successively mounted on the balance arm (17);
- a wire rope I (11) controlled by the windlass I (21) successively bypasses a pulley block on a top end of the tower top, a pulley block on a top end of the portal frame I (5) and a pulley block on a lower portion of the second conveying arm (4);
- a wire rope II (12) controlled by the windlass II (20) bypasses the pulley block mounted on the tower top (10) and finally bypasses a pulley block located on an upper portion of the second conveying arm (4);
- a wire rope III (13) controlled by the windlass III (19) successively bypasses the pulley block located on the tower top (10), the pulley block on a top end of the portal frame II (2) and a pulley block on a side portion of the third conveying arm (1);
- and the tower body (24) is provided with a gyration apparatus (23) and a hopper (22);
- distances from the pulley block on the lower portion of the second conveying arm to two ends of the second conveying arm are respectively a first distance and a second distance, and the first distance is twice the second distance;
- and distances from the pulley block on the side portion of the third conveying arm to two ends of the third conveying arm are respectively a third distance and a fourth distance, the third distance is twice the fourth distance, and the pulley block on the upper portion of the second conveying arm and the pulley block on the lower portion of the second conveying arm are arranged side by side;
- the dike-striding elevation-type conveying device comprises a rail system (101), an elevation feeding trolley (102), a feeding hopper system (103), a telescopic conveyor (104), a windlass (105), an amplitude changing conveyor (107) and a fixed conveyor (109);
- and the rail system (101) comprises a buffering spring (101.1) and a guide rail (101.2), and the buffering spring (101.1) is located right below the guide rail (101.2);
- the elevation feeding trolley (102) comprises supporting rods (102.1), clamp-type brakes (102.2), a lower bottom plate (102.3), a lifting hook (102.4), an upper supporting plate (102.5) and a water level sensor (102.6);
- and the clamp-type brakes (102.2) are mounted at two sides of the elevation feeding trolley (102), and the lifting hook (102.4) is mounted in front of the elevation feeding trolley (102);
- the feeding hopper system (3) comprises a feeding hopper (103.1), a hopper door (103.2), a vibrating stick (103.3), suspension rods (103.4), ribs (103.5), level rods (103.6), valve rails (103.7), a valve plate (103.8), supporting legs (103.9) and oblique rods (103.10);
- the vibrating stick (103.3) is mounted inside the feeding hopper (103.1);
- an opening is arranged below the feeding hopper, the valve plate can movably open and close the opening;
- four corners of the feeding hopper are provided with the four supporting legs;
- the inner side of each supporting leg is connected with the rib;
- the four ribs extend upwardly, and the extension end of each rib is connected with the level rod;
- the four level rods form a square and are connected to the bottom surface of the feeding hopper;
- the lower end of one level rod is connected with three suspension rods;
- lower ends of the three suspension rods are connected with the valve rails;
- the valve plate is mounted on the valve rails, and the valve plate can move along the valve rails so as to open and close the opening;
- two oblique rods are connected between two supporting legs at one side of the suspension rod so as to strengthen the supporting for the suspension rods and the valve plate, and the other three sides are not provided with the oblique rod;
- and the four supporting legs are connected to four corners of the upper supporting plate (102.5).