Mineral sizers

In a mineral breaker having at least a first breaker drum including a plurality of breaker teeth projecting radially from the drum and further including a plurality of opposed breaker teeth positioned so that on rotation of the drum mineral lumps to be broken are gripped between the leading face of the teeth of the drum and a pair of said opposed breaker teeth to thereby break the mineral lump gripped therebetween by a snapping action, the improvement of the breaker teeth mounted on the breaker drum each comprising a main tooth body in the form of a projection projecting from the drum and a sheath removably mounted on the tooth body, the sheath including a hollow tooth formation which defines the external shape of the tooth and which includes a pocket which is seated on and fully envelopes the tooth body, the shape of the tooth body and the pocket being complementary so that when the sheath is seated on the tooth body the leading and trailing faces of the tooth body and the respective facing internal walls of the pocket are in face contact with one another so that loadings applied to the tooth during said snapping action are transmitted through the sheath and onto the main tooth body.