So far we have reported on the physical and chemical analyses of the reduction kiln. The present study is concerned with heat balances including the rate of input energy and that of energy consumption in the kiln. The calculation of thermal balance is necessary not only for efficient and economical operation of the kiln, but also for reasonable improvement of the kiln-process as a reduction device. As the result of measurement of energy balances in several typical operations, we reach the following conclusions:- The total heat consumption for the kiln reduction amounts to 1.9-2.6×103 kcal per kg of half-reduction iron sand sponge, combustion efficiencies ranging 70-80%, and over-all thermal efficiencies ranging 30-35% on the test kiln. Considerable heat loss amounting to 15-30% of total input is found in the exhaust gas forming CO and soot. However, we find that the heat loss in the kiln-shell is not very large. Furthermore, by examining the enthalpy curves of raw material in the operation kiln, we find that heat of reduction reacts as buffer for temperature of raw material under radiation of burner flame. Since the dry part of kiln has a high efficiency of heat transference the rate of fuel consumption is not influenced by the moisture content of the charged material. The recovery of avoidable heat loss may contribute to reduction of a considerable amount of heat consumption.
The spinel hercynite (FeAl2O4) occurs as a reaction product with the deoxidation by aluminium of liquid steel, or when iron oxides come into contact with alumina refractories. The behaviors of hercynite in liquid iron and steel are of great interest, but until recently, few investigations of the rate of formation and reduction of hercynite have been carried out. In this work, the rate of formation of hercynite from mixture of ferrous oxide and alumina at temperatures from 850°C to 1200°C was measured. The rate of reduction by hydrogen stream at 700°C to 900°C was measured by the thermo-balance method. As the supplementary work, the products of reduction by hydrogen, solid carbon and soluble carbon in liquid iron were examined by X-ray diffraction. The results obtained are as follows: 1) The rate of formation agrees with Jander's equation and the value of activation energy is 60kcal/mol, approximately. The relation between rate constant (k) and temperature (T°K) is represented by the equation: logk=-14410/T+7.69 2) The rate of reduction agrees with McKewan's equation and the relation between log k and T can be expressed by the following equation: logk=-8390/T+2.42 From this equation, the activation energy is found to be approximately 39kcal/mol. 3) It is found that FeAl2O4 is decomposed into Fe and materials of spinel type with H2 or carbon, in the first stage of reduction, and at high temperature the spinel materials finally become α-Al2O3.
The abrasion of line pipes by sands is a serious problem.In this report 29 steels including low alloy steels, tool steels and austenitic stainless steel, were tested by the machine designed in our laboratories, which had four rotating arms with four test pieces mounted. Because of the scattering of abrasion losses, it was difficult to judge the results, but the introduction of statistical method, Youden squares, made it possible to. distinguish the small differences between the effects of microstructures and alloying compositions with certain. reliability. The results are as follows: (1) The abrasion loss decreases with increasing hardness under the same condition of microstructures. (2) The results depend definitely on the microstructures of steels with the same hardness.Ferrite pearlite structure shows the best result. (3) Under the same conditions except composition, carbon and chromium improve the abrasion resistance.
The embrittlement of steels by neutron irradiation is one of the most important problems in the construction and operation of reactors. An in-pile test rig was constructed by the authors in JRR-2 for the irradiation test of structural steels. In the present report, the authors describe the test rig, experimental conditions available with the rig in vertical experimental tube of JRR-2, and the results of the irradiation tests, including the post-irradiation V-notch Charpy tests on the A 302 B steel, its welded portion and an aluminium killed steel.