FI69317B - FOERFARANDE FOER ATT SAENKA SVAVELHALT I VANADIN-KOLMATERIAL SOM ANVAENDES SOM TILLSATSAEMNEN FOER STAOL - Google Patents

Description

NOTICE I11 'UTLÄGG Nl NGSSKRIFT 0 ^ 01 / C (45) Patent granted

Patent application 10 01 10CG v (51) Kv.lk. * / Lnt.CI. * C 22 B 34/22, C 22 C 35/00 FINLAND — FINLAND (21) Patent application - Patentansökning 771991 (22) Application date - Ansökningsdag 27.06.77 (FI) (23) Starting date - Giltighetsdag 27.06.77 (41) Made public - Blivit offentlig 2¾ 12 77

National Board of Patents and Registration Date of publication and publication. -

Patent and Registration Office in the United States of America and Public Accounts 30.09.85 (32) (33) (31) Privilege claimed — Begärd priority 28.06.76 United States (US) 700472 (71) Union Carbide Corporation, 270 Park Avenue, New York, NV 10017, USA (72) James Herbert Downing, Clarence, New York, Rodney Francis Merkert,

Buffalo, New York, USA (74) Oy Borenius & Co Ab (54) Method for reducing the sulfur content of vanadium carbon materials used as steel additives - Förfarande för att sanka svavelhalt i vanadin-trisaterial som användes som ti11satsämnen för Stal

The invention relates to a process for reducing the sulfur content of vanadium and carbon-containing materials which are produced under reduced pressure by burning a mixture of vanadium oxide and carbon.

Vanadium-carbon materials of the above type are prepared by burning vanadium oxide and carbon at high temperature and vacuum, as described, e.g., in U.S. Patent 3,334,992 (J.H. Downing and R.F. Merkert), the disclosure of which is incorporated herein by reference.

The vanadium-carbon materials described in the above patent are prepared by a method of mixing V 2 O 3 and carbon, compacting the mixture into briquettes, and firing the mixture under reduced pressure and elevated temperature, e.g., 1200 to 1400 ° C, with a pressure of less than about 300 x 10 “3 mmHg (about 40 Pa) to produce a product that is essentially entirely a combination of vanadium and carbon. This material is widely used as a source of vanadium added to molten steel. It has been found that the sulfur content of this vanadium-carbon product is of the order of about 1/3 of the sulfur content of the starting mixture of V2O2 and carbon, the sulfur content of this starting mixture being mainly of the sulfur content of the domestic carbon source, e.g. coal, carbon black and the like.

Since it is detrimental to add sulfur impurities to the steel, it is important to reduce the sulfur content of the vanadium carbon material described above, especially in the case that low sulfur carbon materials are not readily available.

It is therefore an object of the invention to provide a method for reducing the sulfur content of vanadium-carbon materials prepared under reduced pressure by burning a mixture of vanadium oxide and carbon.

Other objects of the invention will become apparent from the following description and claims.

The process according to the invention is based on adding a smaller amount of at least one material selected from silicon, silica and tin to a mixture of vanadium oxide and carbon containing sulfur as an impurity and burning this mixture under reduced pressure to obtain a material which is essentially entirely vanadium and a combination of carbon, i.e., at least about 80% by weight, and having a sulfur content significantly lower than the sulfur content of the starting mixture.

In a particular embodiment of the invention, a mixture of finely divided V 2 O 3 and carbon is prepared with at least one finely divided material selected from silicon, silica and tin. The total amount of this selected material, when the selected material means tin, is about 1 to 5 times the weight of the sulfur contained in the carbon component of the mixture. When the selected material means silicon or silica, the total amount of silicon is about 1 to 9 times the weight of sulfur in the carbon component of the mixture. The mixture is then briquetted and subjected to a temperature in the range of about 1200 to 1400 ° C in a vacuum oven, whereby the components of the mixture react with each other and complete the reaction at a pressure of less than 300 x 10 ~ 3 mmHg (about 40 Pa) and the reaction time is long enough for carbon and

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6931 7 v2 ° 3 to combine to form a product containing at least 80% by weight of combined vanadium and carbon. The sulfur content of the material thus prepared will be less than about 0.05% by weight.

The following examples further illustrate the invention. The screen dimensions used in the examples are from the U.S. screen series.

Example 1

A mixture of about 454 kg of V 2 O 3 smaller than 2 μm, about 152 kg of petroleum coke with 0.65% sulfur and less than 2 μm, 9.1 kg of "Mogul" was prepared. binder (trademark of Corn Products Company) and 23% by weight of water based on the dry weight of the mixture. From this mixture, briquettes having a size of about 4.5 cm x 3.2 cm x 2.5 cm were prepared by pressing in a K-G type roller briquette press and drying at 107 ° C. About 1.4 kg of briquettes were obtained, which were loaded into a vacuum oven with internal operating dimensions of 17.8 cm x 30.5 cm x 101.6 cm. The furnace pressure was reduced to 175 x 10-3 mmHg (about 23 Pa), and the furnace was heated to 1400 ° C. Due to the evolution of CO gas, the pressure increased to about 1600 x 10-3 mmHg (about 213 Pa). After about 8 hours at 1400 ° C, the pressure dropped to 100 x 10-3 mmHg (about 13 Pa) and the contents of the oven were allowed to cool to room temperature under argon overpressure. According to the analysis, the briquette product contained 8.49% Combined Carbon and 0.18% Sulfur.

Example 2

Substantially the same procedure as in Example 1 was applied, except that the mixture contained 1.7% silicon, based on a weight of V 2 O 3 of 200 "Mesh by Down" (0.074 mm or less), with a silicon to sulfur ratio of about 7 , 8: 1. The briquettes obtained contained 7.94% Combined Carbon and 0.013% Sulfur.

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Example 3 - 69317

Applying essentially the same procedure as in Example 1, an alloy of 0.5% tin based on the weight of V 2 O 3 having a size of 100 "Mesh by Down" (0.149 mm or less) was prepared, with a tin to sulfur ratio of about 2.3 : 1. The briquettes obtained contained 7.44% Combined Carbon and 0.042% Sulfur.

Example 4

Substantially the same procedure as in Example 1 was applied, except that the mixture contained 3.6% SiO 2, based on the weight of V 2 O 3, with a size of 200 "Mesh by Down" (0.074 mm or less), the silicon to sulfur ratio being about 8.8 : 1. The briquettes obtained contained 9.34% Combined Carbon and 0.012% Sulfur.

Claims (3)

1. For the purpose of framställning av ett material som innehäller vanadin ooh koi genom att i undertryck bränna en blandning av vanadinoxid oci koi, kännetecknat därav, att man för att sänka materialets svavelhalt tillsätter blandningen minst at material som valts bland kisel. A process for preparing a material containing vanadium and carbon by burning a mixture of vanadium oxide and carbon under reduced pressure, characterized in that the sulfur content of this material is reduced by adding to this mixture at least one material selected from silicon, silica and tin. 2. Förfarande enligt patentkravet 1, känne te cknat därav, att nämnda Valda material är kisel, varvid mängden kisel är ca 1 ... 9 gänger viktsmängden av svavel i kolkomponenten i blandningen av vanadinoxid oci koi. A method according to claim 1, characterized in that said selected material is silicon, wherein the amount of silicon is about 1 to 9 times the weight of sulfur contained in the carbon component of the mixture of vanadium oxide and carbon. A method according to claim 1, characterized in that said selected material is silica, wherein the amount of silicon in the silica is about 1 to 9 times the weight of sulfur contained in the carbon component of the mixture of vanadium oxide and carbon. A method according to claim 1, characterized in that said selected material is tin, wherein the amount of tin is about 1 to 5 times the weight of sulfur contained in the carbon component of the mixture of vanadium oxide and carbon. 3. The present invention is defined in claim 1, the invention having the same characteristic, as described above, the material of which is a mixture of about 10 to 9 parts of a mixture of three components and a mixture of vanadium oxides and moth.