Abstract: A 140 t/h CDQ in an oversea steel plant has been running overload for a long time and the wall inside the ring duct of CDQ chamber was seriously bulged and a hole about 10 m2 emerged, which led to an emergency shutdown of the chamber for maintenance. After repairing the hole, heat-resistant stainless steel band is used to wind around the ring as one piece, and castables is grouted between the inner and outer walls of the ring duct to form a C-shape support. The CDQ chamber after resumption could maintain more than 90% of its design capacity for up to 13 months continuously

Key words: CDQ chamber, Ring duct, Heat-resistant S.S. bands, C-shape support