Post-mix burner and use of same for generating a flame curtain, the burner having a longitudinal central dividing wall (5) terminating in a wall head (7) towards the burner top (4), an oxidant inlet compartment (102) and an oxidant outlet compartment (103) on a first side of the central wall (5), a fuel inlet compartment (202) and a fuel outlet compartment on the opposite side of the central wall (5); the wall head (7) presenting a first set of oxidant outlet passages (107) and a second set of fuel outlet passages (207) terminating respectively in first oxidant ejection openings (100) and second fuel ejection openings (200) in an ejection surface (10) at the burner top (4), the oxidant and fuel ejection openings (100, 200) each extending in the longitudinal direction along the ejection surface (10).