Installation and method for melting glass

A plant for melting glass or rock including: a first melting tank including a batch material inlet, a heater that makes it possible to heat the batch materials until a liquid glass is obtained; a liquid glass outlet; and downstream of the melting tank, a second heating tank including metallic walls that are not covered with refractory insulating materials and that include a system of internal ducts allowing circulation of a coolant, a plurality of injectors of submerged burners, and a liquid glass outlet, in a form of an overflow, which limits a height of the glass bath in the heating tank to a value between 50 mm and 300 mm. A process for melting glass or rock uses such a melting plant.