Kaolin refractories with a minimum amount of clay bond

Conclusions

When dry bond clay and some of the normal fine-ground chamotte are replaced by chamotte which has been finely ground with the addition of 0.1% C₇-C₉ acid for the same amount of grinding time, and when clay is added solely in the form of dross, it is possible to obtain dry specimens with a porosity of only 2% more and fired specimens in no way inferior in density to the control specimens, but even with less porosity after firing, though the shrink-age is slightly increased.

Hydrophobization of the chamotte fractions 2–0.5 mm without the addition of dried clay makes it possible to obtain fired specimens showing the same properties as the control ones, and less porous ones, though there is slightly increased shrinkage.

The replacement of the clay bond added to the mixture in dry form by fine-ground hydrophobized chamotte sharply reduces the after-effect in these mixtures during pressing.

The possibility has been established, in principle, of obtaining multichamotte parts from kaolinite raw materials by the addition of bond clay to the mixtures in the proportion of 2–4% in the form of dross alone.

The industrial production of these parts should be of practical interest since an increase in the alumina content and a reduction in the flux content in parts is thereby achieved; an increase in the efficiency of tube mills and the degree of dispersion of the fine-ground chamotte on account of being ground without clay and the addition of a dehardener, and a simplification of the production process by eliminating the preparation of the clay for the bond are also made possible.

The results and the behavior of parts during service should be tested under semi-plant and plant conditions. Here tests should be made on replacing all the ordinary fine-ground chamotte by chamotte ground with a hydro-phobizer, since this will simplify the production process still more.

The manufacture and testing of experimental-industrial batches of parts by the proposed method should be organized together with the UNIIO.