The thermal insulation consists of high-density ceramic fiber panels, ble for the working temperature of the oven. Heating is obtained with molybdenum disilicide elements, which do not require a protective atmosphere and do not give rise to aging prcesses. This has the advantage of a simple and safe operation of the oven and a long life of the resistances with the possibility of replacing even just one of them without altering the behavior of the others. It is a fixed crucible laboratory kiln suitable for melting a quantity of mixture which, depending on the model chosen, can vary from +/- 600/1000 gr. up to 3000/5000 gr. The mixture to be melted is placed in the crucible inside the oven, through a hole of suitable size in the upper part of the oven. As the mixture is melted through the crucible and from the kiln, first, through a suitably sized hole in the bottom of the crucible and then a larger hole in the bottom of the furnace, under the crucible, which runs through the entire insulation of the oven.