НссдедоВаНИе ВЯЗКОСТИ СИНТЕТИЧеСКИХ ШДаКОВ СИСТеМ CaO-MgO-BaO-SiO_2-Al_2O_3 BaO 0—30％ BaO ((CaO+0.366 BaO)/SiO_2) 0.7—0.9 (CaO+0.366 BaO)/SiO_2 0.7—0.9. BaO 10％ 0.9—1.2.

Theoretical coke rate means the necessary amount of coke to satisfy the thermal and chemical requirements under given conditions of raw materials, blast temperature, etc. The newly proposed method is characterized by combination of material and heat balance into one equation, and by that, the only thermal income is the heat of combustion before the tuyere with subtraction of heat carried away by the hot top gas. With this thermal balance, the necessary tuyere carbon is found. By adding to this carbon the solution carbon in pig iron and direct reduction carbon, the total carbon is finally obtained.By partial differentiation, a convenient and practically accurate method is derived for calculating effects of different factors on coke rate. Calculations for some Chinese and Japanese blast furnaces are given to show how this method might be used to examine operational efficiency, to calculate effects on coke rate of new technology like fuel injections through tuyere, and used for design purposes. Comparisons of this method with others like that of Runm and Pavlov are briefly given.

The viscosity of slags containing Al_2O_3 15%, MgO 10%, TiO_2 15—35% and with a CaO/SiO_2 ratio of 0.6—1.6 has been measured with an oscillating viscosimeter. Experimental results indicate that the viscosity of titanoslags is very low provided they are not previously subjected to a strong reducing action. The melting point of the slags depends on the CaO/SiO_2 ratio and TiO_2 content. Under a strong reducing condition, however, the TiO_2 can be reduced to lower oxides and even titanium carbide, and the slags become, quite viscous. An increase of temperature and decrease of CaO/SiO_2 ratio increase the rate of thickening. Experimental evidence verifies the presence of finelydispersed titanium carbide, which is the primary cause for thickening. The addition of an oxidizing agent or blowing of slightly oxidizing gases such as CO+CO_2 through the slag can prevent the latter from becoming viscous. These measures might prove helpful in blast-furnace smelting of titanium-containing iron ores.The main mineral constituents of the titanoslgs under investigation are perovskite, anosovite, baikovite and titaniferrous augite. Their relative amount depends upon the chemical composition of the slags and the degree of reduction.

An investigation of the kinetics of the reactions between liquid slags and carbonsaturated iron including the reduction of FeO, MnO, CrO and V_2O_3 by carbon and the desulphurization of iron leads to the conclusion that the chemical reactions come to equilibrium rapidly at the slag-metal interface, while the controlling step is convective diffusion. It has been found that the reactions are of the first order when the melt is kept in a rotational motion, caused by the use of a rotating crucible or stirrer, and are of second order when the melt is kept in a stationary crucible and stirred by CO gas bubbles only. The thickness of the diffusion boundary layer δ, obtained from a treatment of Chipman's desulphurization data and Philbrook's data on the reduction of FeO, which correspond to the two fore-mentioned cases respectively, has been found to be inversely propertional to ω~(1/2), the square root of the angular velocity, and C_(FeO), the concentration of FeO in the slag phase.The present problem has been treated on the basis of the principle of convective diffusion across a solid-liquid interface according to Levich. It has been found that our findings can be satisfactorily explained by an application of this principle. An exceptional case is the reduction of SiO_2 from slags, which is probably controlled by interfacial chemical reaction.

Rates of volatilization of SnO from the binary silicate melts containing 60.60 to 91.00 wt.-% SnO were measured by the "Loss Weight" method. It was found that the logarithm of volatilization rate or vapour pressure of SnO is proportional to the composition of the melt. From these experimental results the activities of SnO and SiO_2 were calculated, and it occurred that they exhibit considerable negative deviation from Raoult's Law. Since the rate of volatilization varies exponentially with the SnO content in the binary melt, it is unlikely that this deviation is associated with the formation of compound between. SnO and SiO_2.

On the basis of the analysis of the previous paper, the present work poses a series of problems in dilute-phase heat transfer technique as applied to chemical metallurgy, and illustrates its practical aspects through pilot-scale measurements and experiments in the development of new metallurgical processes.In actual practice, particles are more often than not in accelerative motion while heat is being transported between them and the surrounding fluid medium, with the result that the transfer coefficient seldom retains a constant value. An acceleration integral∫F(x)=integral from n=Re_0 to (Re_0+Re)((Re_s~xdRe_s)/(Ar_(Δρ)-fRe_s~2)) is proposed from which four dimensionless groups are derived (Eqs. (28), (29), (31), and (36)) which permit comparison of analogous heat transfer equipment on a generalized basis. Towards this end, Eq. (43) is derived for calculating the effectiveness of heat recovery for multi-layer dense-phase fluidization with full allowance for heterogeneous nonuniformity, so that the dense-phase operation may be compared directly with the corresponding dilute-phase operation as given by Eqs. (26) and (26a).After heat transfer measurements had been conducted on pilot scale, the authors applied the dilute-phase technique to heat transfer problems in the magnetizing roasting of low-grade iron ores and the sulfatizing roasting of an iron ore containing small amounts of copper and cobalt. In both cases pilot plant results indicate that the capital investment of dilute-phase equipment would be much lower that those of the conventional counterparts of corresponding capacities. Finally, it is concluded that dilute-phase technique is a new, yet rapidly developing field in the application of fluidization to chemical metallurgy, and a few important problems are proposed for future investigation.

It was known that the Cr-Mn-C-N austenitic steels become brittle (a_k<5) after long ageing at the service temperatures. The aim of the present investigation is to examine the effect of the various alloying elements on the age brittleness in a steel with the basic composition of 14% Cr, 17% Mn, 0.3% N and 0.1% C. From the impact tests after ageing up to 2000 hours at 650 and 700℃, it may be concluded that the carbide forming elements as Mo, V, or W deteriorate the toughness of the steel, while B has a beneficial effect.By a combination of electrolytic extraction, X-ray identification, optical and electron microscopic examination, it was found that the ageing embrittlement is caused mainly by the precipitate of carbide and nitride films along the grain boundaries. If the steel contains more than 1% Mo, x and σ phases will appear after ageing for longer periods; whether these intermetallic phases will cause brittleness or not, it depends upon the quantity and distribution of the brittle phases. The addition of boron to this steel will not only retard the precipitation processes but also make the grain boundary precipitate discontinuous, thus improving the toughness after long ageing.

The cold-rolling and recrystallization textures of Fe-Si (3.25% Si) single crystals with orientations close to (110) [001], (320) [001] and (110) [1(?)2] were investigated. As the reduction increased from 60 to 85 pct, for lower rates of reduction, the recrystallization texture of (110) [001] single crystal changed gradually from the (110) [001] to (310) [001] orientation, but it remained in the (110) [001] orientation in the case of higher rates of reduction. The behavior of the (320) [001] single crystal during coldrolling was similar to the (110) [001] single crystal, whereas in the (110) [1(?)2] single crystal the rate of reduction showed no pronounced effect on the recrystallization texture.These results were discussed according to the theory of recrystallization in situ, and the change of recrystallization textures with reduction rates can be explained satisfactorily.

Metallographic investigation shows that the isothermal reaction, near M_s point (100℃) in 1.4% C-1.4% Cr steel quenched from 1100℃, takes place by martensitic transformation. The major portion of the isothermal reaction occurs by the growth of existing martensite when the amount of retained austenite is less than 40%, while occurs by the formation of new plates when it is more than 50%. Isothermal martensite may form at some preferred sites of existing plates in small amount, which is independent of the amount of retained austenite. A probable explanation is suggested.