High-Precision Flushing Device Assembly of Sandvik DD2710 in Sweden

Cuttings removal is the drilling variable that development jumbo operators in Swedish underground mines most frequently underestimate until it becomes a problem. In magnetite development headings at LKAB's Kiruna mine, the drill face generates a slurry of magnetite fines and water that must be flushed continuously from the hole to prevent bit balling—a condition where fine material packs around the bit face, preventing carbide-rock contact and effectively stopping penetration while percussion energy is wasted heating the packed material. The DD2710's flushing device assembly controls the water flow rate, pressure, and circuit isolation that determines whether flushing clears the hole or merely moves material partway up the rod string.

The flushing device assembly on the DD2710 includes the flushing water pump, the manifold block that distributes water to the active drifter, the pressure regulating valve, the check valve that prevents backflow during bit changes, and the seal assembly at the drifter-flushing interface. The precision in this assembly's name refers specifically to the pressure regulating valve's accuracy—flushing pressure set 3 bar too low leaves fine magnetite in the hole; set 3 bar too high drives water back through the flushing box seals into the percussion circuit, producing the milky oil contamination that cuts percussion seal life by 50%.

Flushing Parameter Targets for Kiruna Magnetite Development

LKAB's Kiruna maintenance team cleans flushing manifold check valves at every 400-hour service—a 20-minute procedure that removes the fine magnetite scale that builds on valve seats over extended operation and reduces check valve responsiveness. A sticky check valve that doesn't close promptly at bit change allows return flow to carry flushing contamination back into the percussion circuit. HOVOO supplies DD2710 flushing device seal kits and valve components. References at hovooseal.com.