US2237485A - Process for the deoxidation and degasification of steel - Google Patents

Description

Patented Apr. 8, 1941 OFFICE rnoccss eon rue DEOXIDATION AND DEGASIFICATIONOF STEEL Paul Hardt, volklingenesaar, Germany, assignor to Biichlingsche Eisenund Stahlwerkc Gesellschaft mit bcschriinkter Haftnng, Volklingen- Saar, Germany, a limited-liability company No Drawing. Application May 2, 1939, Serial No. 271,342. In Germany May 7, 1938 2 Claims; (CL 75-57l it is a imowniact, that carbon is unsuitable for the dcoxidation of soft steel, because small quantitles of carbon remain ineffective, whereas large quantities increase the carbon content of the steel. ".ihe use of a carbonizing liquid consisting of tar, oil, wax, parafiin or pitch for increasing the carbon content of ingot iron or steel is also known.

it has been recognized according to the invention that, contrary to the statements in older patent literature, hydrocarbon of high molecular weight, especially pit coal pitch, has no or only very little carbonizing effect but a strong deoiddiaing and degasification action when added to steel baths. Pit coal pitch has been found to be particularly effective when it is stiffened by an addition of pulverized burnt lime dust, silicater and fluxes. It is preferably used in the form oi pressed or cast bricks.

The cause for' the deoxidizing and degaslfication effects of pit coal pitch is partly due to the evaporating pitch forming over the steel bath heavy vapors which protect the bath against contact with the air. For example Kilograms 1 Nm of air W ih 1.3 l Nrn coke gas weighs 0.6 1' N111 anthracene vapor weighs 8.0

1700" C. anthracene vapor still has the same specific gravity as air at 50 0., that is the temperature of the surroundings prevailing during the casting. The steel is therefore always covered by a layer of pitch vapors.

Mixtures of pitch with pulverized burnt lime in a proportion of 1:3 have shown a strong deoxidizing eifect. The lime addition may, however, be varied. For lowering the sintering temperature of the lime, silicates. fiuor spar, soda and the. like may be added. Preferably additions are used which themselves have a purifying effect on .the steel. 0n the other hand substances such as into the liquid steel .when filling the ladle or can be added in themold during the casting.

I claim: l. A process for the deoxidation and degasification of steel, consisting of treating the liquid steel with a mixture of pitch and dust of lime with the proportion of lime greater than the pitch, and silicates and other fluxes in an amount suiiicient to lower the sintering temperature of the lime.

2. A process for the deoxidation and degasiflcation of steel, consisting of introducing a mixture in the steel bath in cold form in which the mixture comprises pitch with dust of lime with the proportion of lime greater than the pitch and silicates and other fluxes in an amount suflicien-t to lower the sintering temperature of the lime;

' PAU HARDT.