Nippon Kokan Kabushiki Kaisha

Katsuaki Shiohara

Akira Honda

Kazuharu Yatsunami

Satoru Miyakado

Tsuneo Kataoka

In the production of reduced pellets such as reduced iron pellets by the grate-kiln system for firing, a distributor and a belt conveyor provided with a weighing machine are arranged between a sieving machine that sieves produced green pellets to predetermined grain sizes and a travelling grate of a pretreatment furnace. The weight of green pellets fed from said sieving machine through said distributor onto said belt conveyor is continuously measured on said belt conveyor by means of said weighing machine, and a signal indicative of the measured value is fed back to said distributor. Said distributor operates in response to said signal and regulates the supply of green pellets so that the supply of green pellets to said belt conveyor, hence the supply of green pellets to said grate is kept constant. Said distributor is of such a construction as will not crush green pellets.

Method of feedig green pellets onto grate of pretreatment furnace in the

In the production of reduced iron pellets from a material mainly comprising dust exhausted from metallurgical furnaces for iron and steel production, such as blast furnaces, converters, hearth furnaces and electric furnaces, and/or a mixture thereof, by means of a grate-kiln a furnace including a pretreatment furnace comprising, a drying zone, a preheating zone a hardening zone and travelling grate passing sequentially through said zones, and a rotary kiln receiving the output pellets from the hardening zone, hot exhaust gases from the rotary kiln are first passed through said hardening zone and then through said preheating zone to harden and preheat green pellets moving therein. Said exhaust gases are then introduced into a first dust collector, where dust of a high zinc content is almost completely collected from said exhaust gases. Said exhaust gases so purified are then passed through said drying zone to dry green pellets moving therein. Said exhaust gases are then introduced into a second dust collector, where dust is further collected from said exhaust gases before said exhaust gases are discharged out of a stack to open air. When the temperature of said exhaust gases which have passed said first dust collector is not high enough for a heat source for drying green pellets moving in said drying zone, the temperature of gases for drying is raised by blowing hot gases, which are separately produced by a fuel burner, into said drying zone. The dust of a high zinc content collected by said first dust collector is used as a material for zinc refining.

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Fukuyama, Japan

Katsuaki Shiohara