The invention relates to an inoculant mixture for the treatment of molten cast iron, comprising 5 to 75% by weight of a ferro-silicon alloy of type A where Si/Fe>2, containing 0.005 to 3% by weight of rare earths, 0.005 to 3% bismuth, lead and/or antimony and less than 3% calcium, with a ratio (Bi+Pb+Sb)/TR of between 0.9 and 2.2 and 25 to 95% of at least one alloy of type B, based on silicon or ferro-silicon such that Si/Fe>2, containing calcium to a level such that the total amount of calcium in the mixture is from 0.3 to 3%. The above mixtures have a good granulometric stability over time and provide an efficient inoculation of cast pieces, in particular of thin pieces. |