Smelting furnace for continuously smelting crude tin from tin concentrate and continuously fuming slag

The smelting furnace comprises a front-end top-blowing smelting furnace and a rear-end side-blowing fuming depletion furnace, wherein the bottoms of the front-end top-blowing smelting furnace and therear-end side-blowing fuming depletion furnace are communicated; wherein the front-end top-blown smelting furnace comprises a cylindrical furnace body (4), a material inlet (1) in the top of the furnace, a smelting spray gun (3) inserted from the top of the furnace, a smelting smoke outlet (5) formed in the top of the furnace, and a crude tin discharge port (10) formed in the bottom of the furnacebody; the side-blown fuming depletion furnace comprises a cuboid box-type furnace body (18), a vulcanizing agent adding port (20) in the top of the furnace, blowing systems (14) symmetrically arranged on the two sides of the lower portion of the furnace body and used for blowing air and fuel into the furnace, a lean furnace slag discharging port (15) formed in the lower portion of the furnace body, and a fuming smoke outl