Abstract: The loading car (25) transfers the batch and deposits it on the plug (10) of the furnace (1).The batch is introduced into the furnace (1) and the latter is closed by means of the lift (12) which is lowered after the treatment to an intermediate position, from which moment the furnace (1 ) can be displaced horizontally, the lower belt (4) pushing the grid at the bottom of the batch over the cover (17) and the platform (22) of the lift (18) being in the upper position. The cover (17) ensures the imperviousness of the furnace opening to the gases protecting the batch.This lift allows the batch to be introduced into the hardening vat then brought back into a drain position and deposited on the unloading car (38) which moves along the track (36, 37).