1.

Laboratory experiments have demonstrated the feasibility of reducing a stationary layer of cast iron powder at a specific load of 14.2 g/cm2 (bed height 40 mm). Reduction under these conditions is possible thanks to the high porosity of the resultant sponge, amounting, according to measurements, to 60–65%.




2.

Use of converted natural gas widens the permissible range of fluctuation of the O/C ratio in starting cast iron powders to ±0.1, compared with ±0.02 for the self-annealing process, and enables iron powders to be produced by a single-stage process meeting the oxygen content requirements of GOST 9849-74 standard for grade PZh3.




3.

To lower the carbon potential of converted gas (without decreasing its reducing power) and obtain iron powders meeting the carbon content requirements of GOST 9849-74 standard for grade PZh3, it is necessary to raise the temperature in the last zone of the furnace., This may be accomplished by suitably changing the positions of the burners or by reversing the direction of flow of the gas (concurrent flow).

Reduction and decarburization annealing of atomized powders in converted gas

Development of new types of continuous furnace for the reduction and annealing of powders

1.

Study of the reduction and carburization kinetics in iron powder furnaces exposed and led to the removal of several shortcomings in these units.




2.

A method has been developed for reducing the charge in porous drip pans made from rolled powders. Trials using this method showed that the porous drip pans improve heat transfer and gas permeability of the charge and so increase the productivity of the reduction process as a whole by 55%. Moreover, this method will provide the basis for mechanized and automated charged pallet preparation and discharge of the sponge iron from the pallets. Preliminary calculations indicate that even a 10% rise in productivity obtained by using the porous drip pans is enough to make these an economic proposition.

I. M. Fedorenko

Papers

Reduction and carburization in iron powder production at the brovary powder metallurgy factory