Recently the so-called Krupp's “Rennverfahren” which is a newly developed ironmetallurgical process operated in rotary kiln, has been commenced in our country. The “Luppezone” of the German kilns is lined by a special refractory materials such as Radex E or Quarzschiefer. On the other hand, an electrocasted block, Corhart, is increasing its demand for the same lining material in our country. In this paper, chemical composition, physical properties and microscopic constitutions have been studied on the above three materials and the results described in detail.
The corrosion test, then, with a slag of “Rennverfahren” was carried out by the dipping method. At the same time the corrosing mechanism was investigated by the petrographic method on the tested specimens. The results obtained were briefly summarized as follows:
(1) Although Radex E, a chrome-magnesite brick, is said to resist against both slags, basic and acidic, such a fact could not be recognized unfortunately. It was shown that the material has the least resistance to corrosion compared with others, on account of its structural defect, which permits easily the penetration of slag and accelerates the failure of bonding matrix.
(2) On the other hand, the German Quarzschiefer has exhibited a good resistance to a more acidic slag by its chemical and structural characteristics. It is noteworthy that the material was converted to a porcelain-like compact mass on firing and was released from the penetration of slag, excepting surface reaction. The similar researches on quartz shists (Quarzschiefer) found in our country have been also made, but there seemed to be no occurrence of the same material as the German one.
(3) Corhart black, which is a neutral refractory material consisting mainly of mullite, proved to have the greatest resistance to the slag whose composition varies from acidic to fairly basic. Such an excellent resistivity was ascribed to the facts that the corrosing zone of corhart was covered by a protecting layers and that the formation of such layers was due to a dense crystalline structure being doomed to electrocasting.
From the above statements, it is concluded that the corhart black is more superior than the German special refractories as the lining material for rotary kilns.

View full abstract