Patent ID: 8124554

Claim:
A fused, cast, and annealed refractory block comprising a mean zirconia (ZrO 2 +HfO 2 ) content of more than 85% and a silica SiO 2 content of 1% or more, as a percentage by weight based on the oxides, wherein the standard deviation σ of the local zirconia content divided by the volume of the block is less than 7.5, the standard deviation σ being evaluated by taking “n” samples, selected randomly or at positions distributed in the block, as follows: σ = 1 n ⁢ ∑ i = 1 n ⁢ ( z i - z _ ) 2 in which: z i denotes the zirconia content, in percentage by weight, in sample “i” of the block; and z denotes the mean zirconia content, in percentage by weight, in the block, obtained by taking the arithmetic mean of values z i .