Specialized metallurgical processes – compositions for use therei – Processes – Free metal or alloy reductant contains magnesium
Patent
1989-01-13
1991-07-30
Rosenberg, Peter D.
Specialized metallurgical processes, compositions for use therei
Processes
Free metal or alloy reductant contains magnesium
148 12, 423626, 423627, 423629, B01J 204
Patent
active
050357425
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a reduced chromium-ore bearing powder and a method for producing the same. More particularly, the present invention relates to a highly reduced chromium-ore bearing powder which is used for producing a chromium-containing steel, such as stainless steel, in a converter, and which is suitable for conveyance by carrier gas and is directly blown into the molten steel in the steel making process.
2. Background Art
Various methods have been devised for producing at low cost the chromium-bearing raw material of stainless steel. Merits and demerits of such methods are greatly influenced by the conditions of raw materials and electric power and by condition of location of a smelting plant. It is crucial, in Japan for example, to effectively utilize powdered chromium ore which has a poor grade, in order to minimalize production costs.
Incidentally, developments are being made on how to produce a stainless steel by means of blowing chromium-ore powder into an oxygen top-and/or bottom-blowing converter for steel making. Fundamental reaction in a converter oxidizes and removes carbon contained in molten pig iron with the aid of oxygen. Combustion heat is obtained by the oxidation and is utilized to elevate the temperature of molten steel. Upon injection of the chromium-ore powder into the molten steel, the chromium ore must not only be melted but also be reduced. Chromium ore must be first melted, and then the reduction of chromium ore occurs in the molten state. Heat source is indispensable for melting and reduction. A carbonaceous agent is usually added into a converter, and is utilized as both a reducing agent and heat source. In order that combustion of the carbonaceous agent take place, oxygen is necessary, with the result that the amount of oxygen blown increases, and the refining time becomes considerably longer. In a more metallurgical aspect, the addition of a carbonaceous agent into a converter necessitates simultaneous oxidation (combustion) of carbon and reduction of ore. There is a limitation as to whether both the oxidation and reduction reactions can proceed in an identical converter. In order to thoroughly reduce the chromium ore in a converter, the amount of reducing agent is considerably excessive more than the chemical equivalent amount for reducing the chromium ore added in a converter, with the result that productivity is decreased and cost is increased. In most of the steel making plants, a continuous-continuous casting is carried out. In this case, refining time matches casting time. When a carbonaceous reducing agent is added into a converter, the continuous-continuous casting is carried out with difficulty, with the result that such disadvantages as decrease in productivity and recovery and increase in labor are incurred.
Blowing of reduced chromium-ore bearing powder appears to overcome the difficulties involved in the addition of chromium ore. The following methods for producing the reduced chromium-ore bearing powder are known.
(1) Chromium ore, carbonaceous reducing agent and binder are agglomerated into pellets having appropriate size and strength and are reduced by heating in inert atmosphere (Japanese Examined Patent Publication No. 38-1959).
(2) Raw materials in the form of powder are stirred in a furnace which is equipped with inner burners for the combustion of hydrocarbonaceous fuel (U.S. Pat. No. 2,582,469).
(3) Raw materials in the form of powder are reduced by means of introducing hydrocarbonaceous gas therethrough (Japanese Unexamined Patent Publication No. 59-179725).
In method (1), in which pellets are produced and then reduced, the raw materials in the form of powder must intentionally be once pelletized and subsequently be again crushed to obtain powder. The production of pellets and crushing is complicated and results in increase in cost. In addition, in order to fulfill the certain strength requirement of the pellets, limitations are imposed upon the raw materials and production methods of pellets, and hence r
REFERENCES:
patent: 3872193 (1975-03-01), Smith
patent: 4150975 (1979-04-01), Miyake
Minagawa Tsutomu
Saito Sadahiro
Uemura Tadashi
Rosenberg Peter D.
Showa Denko K.K.
Shunan Denko K.K.
LandOfFree
Reduced chromium-ore bearing powder and method for producing the does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reduced chromium-ore bearing powder and method for producing the, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reduced chromium-ore bearing powder and method for producing the will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1540811