Method and apparatus for removing bottom dross from molten zinc during galvannealing or galvanizing

A pump for removing bottom dross from a molten metal in a dip coating container, said molten metal having a top surface, said pump comprising:

• a shaft having a bottom portion and a top portion;
• an impeller, having a lateral cylindrical wall and a top wall forming an impeller chamber, said impeller being operatively connected to the bottom portion of the shaft, the cylindrical wall having a plurality of holes therethrough, each of said holes having cross sectional area in the range from about 1 square inch to about 6 square inches;
• a housing surrounding the top and the sides of the impeller and defining an inlet, said housing having an inside lateral wall, an annular channel being formed between the impeller and the lateral wall of the housing, the distance between the inside wall and the cylindrical wall in the annular channel being in the range from about 5 to about 15 times the average diameter of the bottom dross to be removed;
• an outlet conduit having a pump and communicating with the annular channel and having an upper end extending above the top surface of the molten metal;
• a motor operatively connected to the top portion of the shaft for rotating the shaft and the impeller connected to the bottom portion of the shaft so as to force the molten metal to flow through the inlet, into the impeller chamber through the holes of the cylindrical wall, into the channel and through the outlet conduit past the upper end.