| Title of Invention | A METHOD TO IMPROVE THE PROPERTIES OF GREEN AND FIRED CHROMITE PELLETS BY USING ALKALINE COMPOUND |
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| Abstract | This invention relates to a process for the preparation of green pellets from chromite filter cake, comprising adding a binder to chromite filter cake, followed by a alkaline compound, mixing thoroughly to obtain a mixture, preparing pellets from the mixture, followed by firing the same to obtain fired green pellets. |
| Full Text | FIELD OF THE INVENTION: This invention relates to a process for the preparation of green and fired chromite pellets with improved properties. BACKGROUD OF THE INVENTION; Chromite green pellets are made from the mixer of chromite filter cake along with coke fines and bentonite as binder. Green pellets are prepared in pelletizing disc. Green pellets after screening are fired in a shaft furnace at around 1300°C. However, it is necessary to improve the green and dry strength of the chromite pellets as well as the mean strength of the fired chromite pellets for efficient performance and reduced electric consumption of the submerged arc furnaces during the manufacture of ferrochrome. OBJECTS OF THE INVENTION: It is therefore an object of this invention to propose a process for the preparation of green and fired chromite pellets with improved properties. It is a further object of this invention to propose a process for the preparation of green and fired chromite pellets which have improved green and dry strength. It is another object of this invention to propose a process for the preparation of green and fired chromite pellets which have uniform and controlled size. Yet another object of this invention to propose a process for the preparation of green and fired chromite pellets, in the pellets having increased mean strength. These and other object of the invention will be apparent from the ensuing description. DETAILED DESCRIPTION OF THE INVENTION: Thus according to this invention is provided a process for the preparation of green and fired chromite pellets. In accordance with this invention an alkaline compound is used to improve the pelletization characteristics of chromite filter cake. A diluted solution of the sodium based alkaline compound is mixed to the pelletizing mix in the range of 0.01-0.05 weight percentage of the binder. With the addition of this compound in the range of 0.01-0.05%, green and dry strength of pellets is improved. Chromite fines are mixed with coke fines, the coke fines being added in 1 to 10% by weight of the chromite fines, preferably in 1 to 3% by weight. The mixture is ball milled with water to provide a slurry. The slurry is then subjected to filtration to a moisture content of 6 to 20%, to obtain the chromite filter cake. The chromite filter cake with coke is mixed with bentonite as binder. This mixture contains 49% Cr2O3, 13% Fe (t) and 6% silica. This mixer is divided in to 2 parts as Mix-A and Mix-B. Green pellets are directly prepared from Mix-A. An alkaline compound is mixed to Mix-B in the range of 0.01-0.05 weight percent of binder. The green pellets are prepared from Mix-B. Green pellets from Mix-A and Mix-B are fired to 1200°C to 1300°C. The invention will now be explained in greater detail with the help of the following non-limiting example. However, the invention is not limited to the ranges provided in the description and examples, and variations thereof would still be within the scope of the invention. EXAMPLE: One tonne of chromite fines is mixed with 10 kgs of coke fines and mixture is ball milled with water, to obtain a slurry. The slurry is filtered to a moisture content of 10%, to obtain the chromite filter cake. One tonne of chromite filter cake with coke is mixed with 10 kgs of bentonite as binder. This mixture contains 49% Cr203, 13% Iron (t) and 6% silica. About l-5gms of a sodium based alkaline compound is mixed with the mixture and green pellets are prepared. The green pellets are fired to 1200°C to obtain the fired green pellets. Properties of green and fired pellets of Mix-A and Mix-B are given in the following table. By the method according to this invention, size of the green pellets is controlled during balling to the required size; the green and dry strength of the chromite pellet is increased by 65% and 40% respectively; mean strength of the fired chromite pellet is increased remarkably by 53% and there is considerably less dust generation as observed during firing of the green pellets. WE CLAIM: 1. A process for the preparation of green pellets from chromite filter cake, comprising adding a binder to chromite filter cake, followed by a alkaline compound, mixing thoroughly to obtain a mixture, preparing pellets from the mixture, followed by firing the same to obtain fired green pellets. 2. The process as claimed in claim 1, wherein the chromite filter cake is prepared by mixing coke fines and chromite fines or chromite concentrate, and ball milling the mixture, followed by adding water to obtain a slurry, followed by filtration of the slurry to obtain the chromite filter cake. 3. The process as claimed in claim 2, wherein coke is mixed in 1 to 10%, preferably 1 to 3% by weight of the chromite fines. 4. The process as claimed in claim 2, wherein the slurry is filtered to reduce the moisture content to 6 to 20%. 5. The process as claimed in claim 1, wherein the binder is added in a proportion of 1 to 3% by weight, preferably 1 to 3% by weight of the filter cake. 6. The process as claimed in claim 1, wherein the binder is bentonite. 7. The process as claimed in claim 1, wherein the alkaline compound is selected from sodium hydroxide, sodium carbonate, potassium carbonate and the like. 8. The process as claimed in claim 1, wherein the alkaline compound is added in a range of 0.01 to 0.05 percent by weight of the binder. This invention relates to a process for the preparation of green pellets from chromite filter cake, comprising adding a binder to chromite filter cake, followed by a alkaline compound, mixing thoroughly to obtain a mixture, preparing pellets from the mixture, followed by firing the same to obtain fired green pellets. |
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01157-kol-2007-correspondence others 1.1.pdf
01157-kol-2007-correspondence others.pdf
01157-kol-2007-description provisional.pdf
1157-KOL-2007-(04-03-2014)-CORRESPONDENCE.pdf
1157-KOL-2007-(19-06-2013)-CORRESPONDENCE.pdf
1157-KOL-2007-(20-02-2014)-CORRESPONDENCE.pdf
1157-KOL-2007-(20-02-2014)-FORM-1.pdf
1157-KOL-2007-(20-02-2014)-FORM-13.pdf
1157-KOL-2007-(20-02-2014)-FORM-5.pdf
1157-kol-2007-correspondence.pdf
1157-kol-2007-description (complete).pdf
1157-KOL-2007-EXAMINATION REPORT.pdf
1157-KOL-2007-GRANTED-ABSTRACT.pdf
1157-KOL-2007-GRANTED-CLAIMS.pdf
1157-KOL-2007-GRANTED-DESCRIPTION (COMPLETE).pdf
1157-KOL-2007-GRANTED-FORM 1.pdf
1157-KOL-2007-GRANTED-FORM 2.pdf
1157-KOL-2007-GRANTED-FORM 3.pdf
1157-KOL-2007-GRANTED-FORM 5.pdf
1157-KOL-2007-GRANTED-SPECIFICATION-COMPLETE.pdf
1157-KOL-2007-PETITION UNDER RULE 137.pdf
1157-KOL-2007-REPLY TO EXAMINATION REPORT.pdf
1157-kol-2007-specification.pdf
| Patent Number | 260838 | |||||||||
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| Indian Patent Application Number | 1157/KOL/2007 | |||||||||
| PG Journal Number | 22/2014 | |||||||||
| Publication Date | 30-May-2014 | |||||||||
| Grant Date | 23-May-2014 | |||||||||
| Date of Filing | 22-Aug-2007 | |||||||||
| Name of Patentee | TATA STEEL LIMITED | |||||||||
| Applicant Address | JAMSHEDPUR | |||||||||
Inventors:
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| PCT International Classification Number | C22B1/14 | |||||||||
| PCT International Application Number | N/A | |||||||||
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