Modern Gasworks Practice

CHAPTER VI REFRACTORIES FOR GASWORKS PURPOSES Only within comparatively recent years has the study of various types of fireclays and their relative merits for retort-bench and other purposes received its füll measure of attention from the gas engineer. In years gone by there was not only a lack of knowledge as to home resources in raw materials for refractories, but an absence of co-operation between manufacturers and users. The result was that Irttle or no attempt was made to organize the industry, and manufacturers were in many cases producing materials without precise knowledge of the duties they were intended to fulfil. It may be said that gas engineers took a lead in the direction of improve-ment, and in many other trades their example has now been followed, so tliat the aid of all the component workers has been enlisted for the purpose of carrying out a definite policy. Recently, the science has developed to an amazing extent as a result of the co-operation between producer, consumer, and research, laboratories. The mass of information now available makes it impossible to deal thoroughly with the scientific aspects of th.e whole subject within a single cliapter. It is proposed, therefore, to consider the question in a more or less practical manner, with. special reference to those features which should influence the gas engineer when the selection and purchase of refractories is in view. For more detailed information the reader cannot do better th.an study the proceedings of the Ceramic Society, in which. all the more important developments are noted, while attention should be given to the annual reports of the Refractory Materials Committee of the Institution of Gas Engineers. The word “ refractory ” in. reality is merely a comparative term, and in. the literal sen.se means “ unable to melt.” A wide range of substances is included under the Classification of refractory materials ; among tliese, in addition to the more common types of fireclays, being carborundum, alundum, diamantin, quartz, etc. No material is completely refractory ; that is to say, all so-called refractory substances are capable of fusion, but their respective yielding points are abnormal in. comparison with. prevailing working temperatures. Stated in brief, fireclays are the result of the decomposition of the feldspathic constituents of particular rocks subjected for untold years to the destructive in-flu.en.ce of weathering. Differing degrees of the process of weathering account for modifications in the type of clay produced, and only in rare instances is the process so complete that the final stage (i.e., rechiction to true clay substance, kaolin, or china clay) is reached. The evolution of the true clay substance from the feldspars. 193 o