Iron Ore Mixtures Research Articles

A Canadian plant for the direct reduction of iron

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.

Production of pig iron with the use of coke iron

The investigations on the production of coke iron and its appl icat ion for iron smelt ing were started during the Korean War. At first, by making use of the experience accumula ted during the investigation of the possibil i ty of the production of pig iron with the use of anthracite, and by ut i l iz ing the method of the manufacture of ore briquettes, we ~.~t0,5 carried out some e lementary experiments and thermody~aamic ~ ~ o O ~ 01ff ~ _ calculat ions which showed that i f the blast furnace is o ~ ~ ~ f i l led with briquettes made of a mixture of iron ore con~ = . centra te and coal then the iron oxide is rapidly reduced ~ . ~Yg~ ~ O t/ to a me ta l l i c state, provided that the strength of the bri~ ~ o O3 que~te is retained. Therefore, one can obtain pig iron from these briquettes in low shaft furnaces (during the war we were not in a position to build blast furnaces of a normal height but there was an urgent demand for pig iron). The workers and technica l pe r sonne lo f theKim Chak Iron and Steel Factory undertook to continue the invest igation of the production of pig iron in low shaft furnaces. In September~ 195!, we started to make briquettes from a mixture of Musan iron ore concentra te and various coals. These briquette~ were resistant to cold and high temperature and stood up well to the pressure in Iow shaft furnaces. They were ca l led "reducing i ron-ore briquettes." Under war eonditious, no exper imenta l apparatus Was ava i lab le for testing briquettes at a high tempera ture and, therefore, we carried out industrial tests direct iy in a small blast furnace during a tr ial smelt ing operation. To strengthen the briquette we subjected i t to thermal t rea t ment under pressure. The strongest briquettes were obta ined from a mixture of iron ore concentrate and coking coal. This is explained by the fact that, in the course of the thermal t reatment , the coal was converted into coke, and oxides of iron were reduced to m e t a l l i c iron. We ca l led such briquettes " i ron-conta in ing coke," and la te r on we gave it the name of coke iron. As a result of the laboratory preparat ion of coke iron the following facts were ascertained: 1. During the coking most o f the Musan iron ore concentrate is reduced to m e t a l l i c iron, the extent of the reduction being dependent on the conditions of coking. At the same t ime the grains of the reduced me ta l l i c iron adhere strongly to the neighboring grains of iron or carbon. Therefore, the mechan ica l strength of the coke iron produced depends on the content of iron ore concentra te in the charge prepared for coking. Up to a certain I imi t of the concentrate content the mechan ica l strength increases and then gradually decreases (F ig . ) . 2. When coke iron is used there is no need for high blast furnaces since the iron contained in the coke iron is a lready part ly reduced, 3. Cokei ron production makes i t possible to u t i l i ze pulvemlent iron ores.

On the Shielding Qualities of Different Concrete Mixtures

Absorption curves for neutrons and γ-radiation produced by 16-Mev protons on beryllium are measured in absorber blocks of various concrete mixtures to obtain information on their shielding properties. It is shown that a mixture of cement, scrap iron, and limonite ore is as efficient as water in slowing down and capturing neutrons and, in addition, has sufficient density (ρ=3.5 g/cm3) to be an effective absorber for γ-radiation. Compared to ordinary concrete, a three-foot wall of iron and limonite concrete is superior by a factor of 280 for neutrons and by a factor of 20 for γ-radiation. Boron is shown to be of little value in this type of shielding. Mechanical properties of the scrap iron-limonite concrete are satisfactory for structural purposes. From the practical cost standpoint, a concrete made entirely of limonite ore is shown to be a reasonable compromise.