Particulate material such as iron scrap is melted down into a melt which is received in a melt retaining zone. During the reception of the melt in this zone, liquid iron of the melt is contacted with an elongated upright body of carbon soluble in the liquid iron, or with a lining of such carbon adherent to the bottom of the melt retaining zone, below any slag which floats on the liquid iron of the melt. The liquidus point of the melt is lowered by the resulting carburization of the iron, thereby facilitating the retention of the liquid iron in the melt retaining zone.