A sintered refractory product having the form of a block and consisting of a granulate formed by all the grains having a size larger than 100 μm, referred to as “coarse grains”, and a matrix binding the coarse grains and consisting of the grains having a size smaller than or equal to 100 μm, the granulate representing between 45% and 90% by mass of the product, the product having a composition such that, in a mass percentage based on the oxides: Al2O3>80%, SiO2