A Canadian plant for the direct reduction of iron

Abstract

The Canadian company "Quebec South Steel Corpora t ion" has recent ly announced the proposed construction of a steel plant near Montreal. Construction on the new plant should start in the early part of 1961. The planned capac i ty of the plant is 91 thousand tons of iron and semifinished product per year; there will be provision for future expansion. The main raw mater ia l will be magnet i te ores from the Ironsides Deposit, situated 7 km from Ottawa. The reserves of ores from this deposit with a 47% iron content will provide normal operat ion of the plant for about 17 years. In addit ion, ores will be used ~om the group of deposits at the Big Three Lake (Quebec Province). The reserves of ores from this group of de posits is compara t ive ly smal l (14-22 mi l l ion tons). The average iron content in the ore is 40-50%. It is expected that the plant wil l operate for 330 days in the year with an average output of 975 tons of meta l per day. This pIant wil t be the first on the American continent to use the so -ca l l ed "S t ra teg ic -U@" process for the d i rec t reduction of iron. An exper imenta l plant working with this process is operating at Niagara Fails. About 10 thousand tons of various ores have been processed in this plant . At the exper imenta l plant at Niagara Fails there are three t r iple-phase modernized e l ec t r i ca l "Volta" furnaces of 1000 kv-a , a rotating roasting furnace of d iameter 1872 ram, length 24.4 m,f i t ted with a dust trap and vent i la t ion device and operating on gas or off,and also auxi l iary equipment . In the "St ra tegic-Udy" process a mixture of iron ore, flux and carbon reducing agent is continuously fed into a rotating furnace in which the materials are dried, the volat i les are removed and the iron is par t ia l ly reduced from the ore. Depending on the type of ore, the furnace temperature is 1100-1300 ~ If the temperature system is distributed it is possible to have sintering of the charge and the formation of incrustations on the inner surface of the furnace. To ensure the desired degree of reduction of the iron from the ore the required amount of carbon is introduced into the roasting furnace. In addition, gas obtained in the e lec t r ica l inching furnace is brought i n , The carbon monoxide in the gas is fully used up in the ini t ia l stages of the reduction. To save the thermal and e lec t r i ca l power, the hot mass leading the roasting furnace passes through a special feeder di rect ly into the fusion zone of the e lec t r ica l furnace. In the e lec t r ica l furnace the "S t ra teg ic -U@" process is set up on the principle of the so-ca l led open bath ("floating charge"). The height to which the e l ec trode is raised is fixed in dependence on the conditions: from 12.5 cm above the level of the mohen slag to 87.5 cm below this level . In the bath of the furnace, a constant e l ec t r i ca l resistance is provided which makes it possibIe to operate with the maximum power of the furnace. The carbon reacts compara t ive ly quickly with the iron oxides which were not comple te ly reduced in the roasting furnace. Because of this, good quali ty meta l is obtained from the e lec t r ica l furnace. The /u rnace output is fairly high. The meta l and slag are tapped per iodica l ly from the e lec t r ica l furnace in the usual way. The main advantage of the "Strategic-Udy" process is its continuity from the moment the ore is charged until the finished meta l is tapped, In this process the mass leaving the roasting furnace is not cooled ; this mass does not have to be ground or have magnet ic separation, nor is it necessary to sinter the semifinished product obtained from the separators.