Abstract: According to the present invention, there is provided a direct current electric furnace for melting metal capable of melting scraps rapidly and also capable of diminishing cold and hot spots formed on the furnace wall, wherein the direct current electric furnace is provided with a single top electrode, a plurality of furnace bottom electrodes, or a plurality of electrode units obtained by dividing a multitude of furnace bottom electrodes of a small diameter into plural units, and electric current controlling thyristor circuits for controlling each individually electric currents flowing through the plural furnace bottom electrodes or electrode units. The electric current controlling thyristor circuits may be substituted by thyristor circuits for controlling electric currents for each of plural groups obtained by dividing the above plural furnace bottom electrodes or the above many furnace bottom electrodes or the above plural electrode units into the plural groups.

Abstract: Disclosed herein is an apparatus for blowing a powdery refining agent into a refining vessel which is adapted to blow the powder into a molten metal bath of the refining vessel together with a refining gas by feeding the powder from a pressure vessel to a main pipe for the supply of the refining gas. The pressure vessel is connected to the main pipe through a plurality of transportation pipes each provided with an on-off valve and connected to a secondary gas pipe for introduction of the refining gas downstream of the on-off valve. The secondary gas pipe is provided with a flow control valve.

Abstract: A method of distributing powdered or granular material to a plurality of feeding ends in a system having a pressurizing tank for pressurizing and fluidizing a powdered or granular material, a plurality of transportation pipes having one ends constituting discharge nozzles opening above a fluidized bed in the tank and the other ends connected to different feeding ends so as to introduce the material to the feeding ends, and a plurality of booster gas supply pipes for supplying respective transportation pipes with a booster gas. The internal pressure of the tank is controlled by a controller provided with a set valve in accordance with the mean value of the terminal pressures at the feeding ends, the mean value of predetermined set flow rates of the booster gas in the booster gas supplying pipes, and the mean value of predetermined set rates of transportation of material to the feeding ends.

Abstract: Leakage of cooling water in means for cooling an equipment keeping a large amount of CO gas therein is detected by measuring an amount of CO dissolved in a given amount of discharged cooling water by means of a gas chromatograph. The apparatus for detecting such leakage is characterized by the combination of a sampling device, a metering device for taking up a given amount of the sample water, a degassing tank for separating CO gas and CO.sub.2 gas from water, and a gas analyzing device for quantitatively analyzing and recording the amount of CO gas dissolved in the metered sample water.

Abstract: A method of operating a blast furnace comprising the steps of selecting sight factors mathematically and statistically as effective in determining the operating condition of a blast furnace, sensing the eight factors as sample data, converting the sample data into variable factors, comparing the sample data and the variable factors with predetermined limiting factors, generating numerical non-dimension values corresponding to the level of satisfaction between the sample date or variable factors and the corresponding limiting values, multiplying the numerical non-dimensional values by predetermined corresponding weight allocation indices, summing separately the results of the multiplication for the sample data and the variable factors to form a numerical factor grand addition output and a variable factors grand addition output, summing the numerical factors grand addition output and the variable factors grand addition output to form an overall grand addition output and taking appropriate action to control the