Title of Invention	METHOD OF DETERMINATION OF SINTER REDUCTION DEGRADATION INDEX (RDI) USING MAGNETIC PROPERTY OF IRON ORE SINTER
Abstract	The present invention is a simplified version of the RDI test by using innovative technique. The results obtained by the new method of determining RDI corroborates well with the actual measured value in the laboratory. The invention uses a strong magnet to assess the RDI by using an empirical formula. The results obtained corroborate well with the actually measured value of RDI in the lab.

Full Text

FIELD OF APPLICATION The present invention relates to a method of Testing of Sinter Reduction Degrading Index (RDI), a high temperature property of iron ore sinter. BACKGROUND OF THE INVENTION RDI and its significance in Blast Furnace Operation RDI is a significant property of sinter which determines the degree of degradation of sinter in the upper stack region of blast furnace. Sinter is known to degrade at low temperature of 500-600°C under reducing condition. RDI is also known as 'Low Temperature Reduction Degradation'.The degradation is caused by reduction of hematite into magnetite in the upper stack region owing to the volume expansion. Usually the weight loss after reduction is generally less than 1% indicating very little reduction. When hematite reduced to magnetite at temperatures between 525 to 625°C, there is a volume increase of about 25%. This induces stresses in the materials surrounding the reduction area, which generates cracks. It is the propagation of these cracks through the sinter matrix, which is responsible for the high degree of degradation of sinter under such condition. If the degradation of sinter is high in the upper stack region of a blast furnace, the resultant hot fines disturbs the gas distribution, lower the thermal reserve zone and cause high FeO inputs to the cohesive zone and dripping zones. This results in irregular burden descent, higher coke ate and lower productivity. Method of determination of RDI Since RDI is a degradation index, lower the value is better. RDI is determined in laboratory only. There are international standards to carry out this test in laboratory-ISO 4696, IS 10823: 1994 and JIS RDI test. Tata Steel follows the IS 10823:1994 method. The procedures are slightly different in the ISO and RDI test. In both cases, a packed bed of material of a specified mass and size is reduced for a definite time at 550°C. This is followed by tumbling in a small drum (JIS drum). The specification are given below: Cost and Time of Testing According to the experience of Central Raw Material Testing Laboratory of Tata Steel we have the following estimates: Approximate cost: Rs 10,000 per test excluding the cost of manpower (salary,etc) Approximate time: Seven (7) hours including the time of sample collection, sample preparation and RDI testing. Therefore,it may be observed that the testing of sinter RDI requires not only the use of precision instruments and scientific equipments at laboratory, it is quite costly and time taking process to determine even one value of sinter RDI. Therefore, many industries cannot afford to have such elaborate set-up for regular testing of RDI. OBJECTS OF THE INVENTION It is therefore, an object of the present invention to propose a method of testing sinter RDI which eliminates the disadvantages of the prior Art. Another object of the present invention is to propose a method of testing sinter RDI which is time saving (only 30 minutes takes for testing). A further object of the present invention is to propose a method of testing sinter RDI which is simple that plant operators can determine at any time they want. A still further object of the present invention is to propose a method of testing sinter RDI which is very economic. An yet further object of the present invention is to propose a method of testing sinter RDI which is customer friendly. SUMMARY OF THE INVENTION The present invention is a simplified version of the RDI test by using innovative technique. The results obtained by the new method of determining RDI corroborates well with the actual measured value in the laboratory. The invention uses a strong magnet to assess the RDI by using an empirical formula. The results obtained corroborate well with the actually measured value of RDI in the lab. BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS Fig-1 shows the graph of sinter Predicted vs Actual Fig-2 shows the testing of sinter product DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Sample Collection Sinter pieces in the size range 10-15 mm are collected manually either from conveyor belt or from the sampler increments. Approximately 40 to 50 pieces of the sample is enough. 1) If sample is collected from belt, 2-3 pieces may be picked up at a time and kept in a sampling tray. Between two pick-ups, a gap of 3 minutes is to be maintained. This is to make the sample representative. 2) If sample is collected from auto sampler, 40-50 pieces in the size range 10-15 mm should be picked up randomly from a sample increment. Test Method (a) Strong magnet The test requires the use of one strong magnet. The same magnet has to be used for analysis. If the test has to be carried out by different persons, it is recommended that all tests are carried out by magnets of approximately same strength and weight. Recommended magnet: all tests noted in this invention has been carried out using strong magnets easily available at a low cost. The inventor used magnets of 'Magnetic Rattle'. The magnet weighs 35g and it can pull a triangular paper clip from a distance of 45 mm. (b) Testing of sinter particles Taking one particle of sinter at a time and test with the standard magnet whether it is strong, week or medium category as far as its attraction by the magnet is concerned. To standardize the category, the magnet is left freely on a wooden table or on the palm of left hand. Then take one particle at a time and try to lift up the magnet. If the particle is able to lift up the magnet against gravity and hold it without releasing the magnet (weight 35g), the particle is categorized as 'Strong Category'. If the particle is not at all lift up the magnet, it is termed as 'Week Category'. In case, the particle is able to move or partially lift the magnet but unable to lift and hold, it is categorized as 'Medium Magnet'. The particle may be rotated, if necessary, to touch the magnet with all surfaces before categorizing it as 'week' or 'medium'. (c) Calculation/Determination of RDI The sinter particles are kept separately as per the above categorization method of 'Strong', 'Medium' and 'Week". Number of particles of each category is then counted. It has been found by testing numerous samples of sinter produced that the average RDI for Strong, Medium and Week are as indicated in Table 1. Table 1: Category-wise Average RDI Let, No. of pieces of strong category=nl No. of pieces of medium category=n2 No. of pieces of week category=n3 Then RDI of the given sample should be calculated as: RDI= (24* nl+ 32* n2+38* n3)/(nl+n2+n3) This empirical formula has been widely applied in sinters and the result obtained has been tallied with the actual RDI value determined by Raw Material Testing Laboratory. A shown in Fig 1 above, the predicted value is quite close to the actual value of RDI. WE CLAIM 1. A method of testing Sinter Reduction Degrading Index (RDI) comprising: - collection of 40-50 sinter pieces in the size range 10-15 mm manually either from conveyor belt or from sample increment; - taking a standard magnet having weight 35gm and left freely on a wooden table or on the palm of left hand; - taking one particle of sinter at a time and try to lift the magnet; - the particle able to lift up the magnet against gravity and hold it without releasing the magnet is a 'strong category'; - the particle is not at all lift up the magnet is a 'week category'; - the particle is able to move or partially lift the magnet but unable to lift and hold is a 'medium category'; - counting the number of pieces of each category and categorywise average RDI; - calculating the RDI of sample from an empirical relation RDI= ( average RDI of strong category X nl+ average RDI of medium category X n2+ average RDI of week category X n3)/ (nl+n2+n3) Where nl= no. of pieces of strong category n2= no. of pieces of medium category n3= no of pieces of week category 2. The method as claimed in claim 1, wherein 2-3 pieces of sample are collected by picking up at a time where the samples are collected from conveyor belt keeping an interval of 3 minutes. 3. The method as claimed in claim 1, wherein 40-50 pieces in size range 10- 15 mm are picked up randomly when the samples are collecting from a sample increment. 4. The method of testing Sinter Reduction Degrading Index (RDI) is substantially described and illustrated herein. The present invention is a simplified version of the RDI test by using innovative technique. The results obtained by the new method of determining RDI corroborates well with the actual measured value in the laboratory. The invention uses a strong magnet to assess the RDI by using an empirical formula. The results obtained corroborate well with the actually measured value of RDI in the lab.

Documents:

1479-KOL-2008-(12-03-2014)-ABSTRACT.pdf

1479-KOL-2008-(12-03-2014)-CLAIMS.pdf

1479-KOL-2008-(12-03-2014)-CORRESPONDENCE.pdf

1479-KOL-2008-(12-03-2014)-DESCRIPTION (COMPLETE).pdf

1479-KOL-2008-(12-03-2014)-DRAWINGS.pdf

1479-KOL-2008-(12-03-2014)-FORM-1.pdf

1479-KOL-2008-(12-03-2014)-FORM-2.pdf

1479-KOL-2008-(12-03-2014)-OTHERS.pdf

1479-KOL-2008-(12-03-2014)-PA.pdf

1479-kol-2008-abstract.pdf

1479-kol-2008-claims.pdf

1479-KOL-2008-CORRESPONDENCE 1.1.pdf

1479-kol-2008-correspondence.pdf

1479-kol-2008-description (complete).pdf

1479-kol-2008-drawings.pdf

1479-KOL-2008-FORM 1.1.pdf

1479-kol-2008-form 1.pdf

1479-kol-2008-form 2.pdf

1479-kol-2008-form 3.pdf

1479-kol-2008-gpa.pdf

1479-kol-2008-specification.pdf

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