Employee was balancing kiln ID fan. He had welded a balance weight to the side of the fan wheel and was wire wheeling the slag off his weld with a 4"" grinder when it came in contact with the edge of the fan wheel and got ripped from his grasp. The grinder hit his chest, ran up his coat and hit his chin. Causing employee to receive 1 internal stitch and 3 external stitches.