SOME CONSIDERATIONS NECESSARY IN SELECTION OF REFRACTORIES FOR THE OPEN HEARTH1

The kind, quality and quantity of refractory brick used in steel plant furnaces, coke ovens, blast furnace, open hearth and auxiliaries are discussed. The factors that influence the life of refractory brick in the open hearth furnace, discussed numerically, with the economic situation indicated in monetary value.     

OPERATING CONDITIONS IN THE OPEN HEARTH AS THEY AFFECT THE LIFE OF REFRACTORIES

A discussion of the deterioration of refractories under operating conditions of the acid and basic types of open hearth furnaces is given.     

FIRE-CLAY BRICK FOR THE OPEN HEARTH1

Fire-clay brick in the open hearth are normally subjected to medium temperatures and to the action of slag containing high percentages of iron and lime. Temperatures near the maximum of the open hearth itself may exist due to failure to reverse the draft and for that reason brick of high refractoriness are used. Resistance to spalling action is not of primary importance because the temperature change is small. The indications obtained from a laboratory test were that brick having a high alumina content would resist the slag action better than ones higher in silica.     

ROOF BRICK FOR THE OPEN HEARTH1

The conditions under which a roof brick has to stand are considered and possible means of improving refractories in common use suggested. A brief mention is made of the possibility of utilizing other available refractories.     

CHROME REFRACTORIES1

A compilation from the available literature is presented, giving the more important data on chromite and chrome refractories. A bibliography is included.     

SPECIFIC HEATS OF CHROME AND MAGNESIA REFRACTORIES*

The previous work in the field is surveyed, the method of preparing the samples is described, and chemical, petrographic, and screen analyses and photomicrographs of the samples are presented. Specific-heat determinations were made by the method of mixtures in a calorimeter using carbon tetrachloride; the calorimeter and the auxiliary equipment are described; and the procedures for determining the heat capacity of the calorimeter system and for the specific heats of the test samples are given in detail. The results are summarized, tabulated, and compared with published data. In addition to the bibliography of the papers mentioned in the article, an additional section (Section B), which served as a background for the study, is included.     

REFRACTORIES FOR STOKERS

An outline is given of the general uses of refractories for stokers, and the requirements for an ideal fire brick. Temperatures which a refractory must stand are given and some of the troubles due to fluxing and spalling are described. Some analyses are made of typical brick and troublesome ash.     

METHOD FOR THE ANALYSIS OF ALUMINOUS SILICATE REFRACTORIES1

A method is given in which the solution of difficultly fusible refractory material is obtained by subjecting the finely pulverized material to two fusions, the first in sodium carbonate, followed by one in potassium bisulphate. The melts are dissolved in water and after adding sulphuric acid are evaporated to dense fumes. Care is taken to remove any calcium sulphate that may be formed. The final residue is treated with hydrofluoric and sulphuric acids. The alumina is determined according to the method described by Blum as given by Hillebrand especial care being used in heating the final precipitate to constant weight. A temperature of about 1150°C is necessary. Two precipitations are required in the determination of lime. The excess of ammonium salts are removed prior to the precipitation of the magnesia, by adding an excess of nitric acid, evaporating to dryness and heating, which expels the ammonium chloride according to the reaction NH₄Cl + HNO₃= HCI + 2H₂O + N₂O.     

REFRACTORIES AND REFRACTORY CEMENTS FOR THE NONFERROUS FOUNDRY1

Development in refractory linings for the various furnaces encountered in the nonferrous foundry industry is outlined, and figures given showing the present trend. These include open-flame, crucible, and electric furnaces. The open-flame furnaces formerly used firebrick linings, but silicon-carbide and high alumina refractories are coming into use. The crucible furnace linings show a decided preference for silicon-carbide refractories, while the electric furnaces are partial to the alumina and mullite bearing types. Progress in the manufacture of refractory cements and their use in the various types of furnaces is discussed. Data are given which indicate that the use of the proper types of cements for maintaining furnace linings of similar composition is becoming more general.     

CHEMICAL AND MINERALOGICAL CHANGES IN STACK AND HEARTH REFRACTORIES OF A BLAST FURNACE*

Refractory samples removed from the lining of a blast furnace exhibiting normal behavior were analyzed for chemical and mineralogical changes. The changes observed in the lining of this furnace are discussed and their probable effect upon the refractory life is indicated; On the basis of the findings, suggestions are made regarding blastfurnace refractory practice.     

REFRACTORIES FOR OIL-GAS MANUFACTURE1

The present investigations of refractories by the oil-gas industry on the Pacific Coast were stimulated by sporadic independent tests in the past whereby it was observed that different qualities of fire brick not only had varying lengths of service but also had an apparent influence on the amount and quality of gas made and on the efficiency of gas manufacture. The essential differences in generator design, including that of brick-work construction, in the two-shell type of generator as compared with the single-shell generator are such that longer refractories life is obtained in the former type. The operations in the manufacture of oil gas for the two-generator types are briefly discussed, showing that the refractories are subjected to alternating oxidizing and reducing conditions. Other causes contributing to ultimate refractories failures are carbon deposition in the brick, abrasion of hot gases and the impinging of long flames on the brick, heavy checker-brick loads on arches, faulty construction of arches, and erratic working conditions. In addition, super-saturated steam, heavy hydrocarbons, and salts and sulphur in the oil, are contributing causes to checker-brick disintegration, especially in the generator zones where the oil and steam are introduced. It is hoped that specifications for refractories may be drawn up from the results of practical service tests now being conducted. The heat-transfer and heat-absorption properties of various refractories, such as conductivity, specific heat, density, diffusivity, heat capacity, and time required for the refractories to reach near-heat saturation, are discussed, particular attention being given to their possible application as oil-gas generator checker brick. The need for more complete and accurate data on the fundamental constants necessary in heat-transfer calculations is pointed out. Researches on refractories with thermal properties superior to fire brick are now being conducted in generators in an endeavor to increase gas capacity and operating efficiency along the lines indicated by theoretical considerations.     

THE EFFECT OF ATMOSPHERIC CONDITIONS ON THE LOAD TEST FOR REFRACTORIES1

The literature relative to the investigation was reviewed and criticized. Iron pyrite was added to clays in amounts varying from 0 to 5%. Test pieces 2×2×41/2 inches were fabricated by the stiff-mud, and dry-press processes. After firing to cone 8 these were subjected to load tests at 1350°C under oxidizing, neutral, and reducing conditions. Expansion and contraction values were plotted against time and temperature. Results under reducing conditions. Expansion and contraction increased with increase of pyrite content.