Abstract: A fly ash-based fire-prevention and extinguishing material with carbon dioxide mineralized and stored, and a preparation method thereof are provided. The preparation method includes: separately weighing 100 parts to 120 parts of water, 1 part to 3 parts of a solid strong alkali, and 20 parts to 40 parts of a fly ash as raw materials, pouring the raw materials into a reactor successively to obtain a resulting mixture, and stirring the resulting mixture at a high rotational speed; adding 10 parts to 20 parts of a solubilizing agent to the reactor, sealing the reactor, introducing carbon dioxide to the reactor at room temperature to maintain a carbon dioxide pressure to obtain a resulting slurry, and stirring the resulting slurry at a high rotational speed; and further introducing carbon dioxide into the reactor to increase the carbon dioxide pressure, and stirring the resulting slurry at a low rotational speed.

Abstract: A coaxial powder-feeding nozzle includes a partition wall-type shell, a powder flow area, a cooling liquid flow area and a shielding gas conveying channel. A powder self-cleaning filter is on the outer side of the partition wall-type shell; the powder self-cleaning filter includes a set of powder collecting tubes on each side of the partition wall-type shell in the axial direction; each set of powder collecting tubes includes at least one powder collecting tube; under the coaction of a suction force applied by a powder collecting system and the self-weight of residual powder, a residual powder inlet of each powder collecting tube causes the residual powder on the opposite side to roll down to the bottom along the wall surface of a metal tube to be processed on the same side, and to be gathered at the front end of the residual powder inlet of the powder collecting tube.

Abstract: A coaxial powder-feeding nozzle includes a partition wall-type shell, a powder flow area, a cooling liquid flow area and a shielding gas conveying channel. A powder self-cleaning filter is on the outer side of the partition wall-type shell; the powder self-cleaning filter includes a set of powder collecting tubes on each side of the partition wall-type shell in the axial direction; each set of powder collecting tubes includes at least one powder collecting tube; under the coaction of a suction force applied by a powder collecting system and the self-weight of residual powder, a residual powder inlet of each powder collecting tube causes the residual powder on the opposite side to roll down to the bottom along the wall surface of a metal tube to be processed on the same side, and to be gathered at the front end of the residual powder inlet of the powder collecting tube.