Abstract: The invention relates to a simplified production process with which it is possible to obtain carbon blocks, in particular anodes intended for aluminium production using the Hall-Héroult electrolysis process, which have high thermal shock resistance. This process comprises a grain size distribution adjustment operation of a carbon aggregate which includes: a) separating an initial ungraded carbon aggregate AC into a first fraction F1 made up of grains whose sizes are smaller than X, and into a second fraction F2 made up of grains whose sizes are X or greater, X lying between 0.2 and 2 mm; b) crushing B1 the first fraction F1 and part P1 of the second fraction F2 such as to obtain a powder F comprising a controlled proportion of ultra-fine grains; c) mixing the remaining part P2 of fraction F2 and said powder F in proportions with which it is possible to obtain crude carbon blocks whose so-called “Gr/S” ratio between the proportion PGr of grains larger than 0.

Abstract: A coating composition is disclosed for protecting from corrosion and oxidation in the hot condition carrier bars of pre-baked anodes and the emergent carbonaceous part of the anodes for the protection of aluminum in the Hall-Heroult process. The composition consists essentially of dry matter formed by calcium alumnate cement having an alumina content of at least 70% and a low content of impurities, magnesium spinel, and optionally, further alumina, together with water in the amount of 10 to 80% by weight of the total dry matter.

Abstract: The invention concerns a coating for providing protection from corrosion and oxidation in the hot state, which coating is intended for the carrier bars of prebaked anodes and the emergent, or exposed, carbonaceous part of said anodes for Hall-Heroult electrolysis tanks, which elements are formed of a composition of carbonaceous aggregate selected from coke, graphite, semi-graphite and electrode scrap, together with calcium aluminate cement having an alumina content which is at least equal to 70% and a total amount of troublesome impurities (SiO.sub.2, Fe.sub.2 O.sub.3, TiO.sub.2, K.sub.2 O, Cr.sub.2 O.sub.3 and Mn.sub.2 O.sub.3) of less than 5% and preferably less than 2%. The protective coating may further comprise an addition of alumina powder in a proportion which can be up to 50% of the weight of the aggregate and an addition of 0.01% to 5% of metal powder such as passivated aluminium powder of a grain size of less than 0.1 mm. The coating may be used in the form of paste or be applied by spray gun.