Title of Invention

A METHOD FOR ESTIMATION OF CAF2 CONTENT IN A MIXTURE OF CAC2 AND CAF2 (DS COMPOUND) FOR DESULPHURISATION OF PIG IRON PRODUCED FROM BLAST FURNACES .

Abstract

A method for estimation of CaF2 content in a mixture of CaC2 and CaF2 (DS compound) for desulphurisation of pig iron produced from blast furnaces through ICPAES procedure comprising the sequential steps of preparing a sample of DS compound by taking a measured amount of DS compound with distilled water and acitic acid and the whole content is boiled and then cooled to room temperature, obtaining a residue on filtration of the solution and igniting the residue and transferring the resulted ash to a beaker wherein dilute nitric acid along with perchloric acid is added, and the beaker is then heated for complete fuming , the resulted thickened mass is cooled and redissolved in dilute HCI, from the resulted solution a small amount of it is transferred in a volumetric flask along with sodium carbonate and borax, concentrated HNO3 and pure copper solution and the volume is made upto a predetermined volume and measuring the CaF2 content for unknown test solution by measuring the emission spectrum of the sample solutions containing calcium ions by computer processing.

Full Text

Field Of Invention This invention relates to a method of estimation of CaF2 content in the mixtures of CaC2 and CaF2 (DS compound) through ICPAES test procedure for desuiphurisation of molten steels and alloy steels. Background of the Invention It is known since long that to obtain a steel or alloy steel with compatible strength and other physical characteristics as per specified chart, desuphurisation of molten steel/alloy is an essential criterion as sulphides precipitated in the grain boundary of final steel/alloy steel will deteriorate the steel quality and often cause steel to breakage and enhance corrosion. Hot metal desuphurisation is carried out using mainly calcium compound such as lime, fluorspar (CaF2) and calcium carbides. (CaC2). The compound that is mainly used for this purpose is an admixture of calcium fluoride and calcium carbide. Therefore quality maintenance of these material regarding their specified composition are extremely important to ensure production of graded metals of specified composition removed form sulphur impurities and judge the efficacy of desuphurisation of molten metals. The specifie composition of calcium carbide and calcium fluoride is judged by CaF2 content in the mixture of CaC2 and CaF2. There is no method existent in prior knowledge about estimation of CaF2 content in mixture of CaC2 and CaF2. The present invention is aimed to development of a method of estimation of CaF2 content in the mixture of CaC2 and CaF2 for providing means for improved process of desulphurization of steel and alloy steel. Another object of the invention is to prepare a synthetic standard containing mixture of CaC2 and CaF2. According to a further objective of the invention a test sample solution is prepared from the mixture of CaC2 and CaF2. According to a still further objective of the invention calibration standard are prepared by matching to amounts of sodium carbonate, borax and Hcl. According to yet another objective of the invention copper is used as an internal standard in the test solution sample. According to yet another objective of the invention calibrated solution of calcium is prepared for selection of calcium line. According to still yet another objective of the invention a mutti point calibrated program is prepared using the said calcium lines. According to the invention there is provided a method of estimation CaF2 content in a mixture of CaC2 and CaF2 (DS compound) through ICPAES procedure comprising the sequential steps of preparing a sample of DS compound by taking a measured amount of DS compound in a beaker and adding predetermined quantity of distilled water in the beaker, after the reaction ceases, acetic acid is added in the said beaker and the content of the beaker is boiled on warming gently for a while, the solution is cooled to room temperature and obtaining, a residue of CaF2 on filtration of the solution and igniting the residue at 600 - 650°c for about 30 minutes and the resulted ash is transferred to a beaker wherein a small amount of dilute nitric acid along with perchloric acid is added, and the beaker is then heated for complete fuming, after which the resulted thickened mass is cooled and redissolved in dilute Hcl and the resultant volume is made upto a predetermined volume in a volumetric flask by adding distilled water, from the resulted solution a small amount of it is transfered in a volumetric flask in which small amount of sodium carbonate borax are added and in which some amount of concentrated HNO3 and pure copper solution as internal standard are added and the volume is made upto a predetermined volume from which, the measurement datas are obtained through preparing calibration standard solution of calcium using pure calcium carbonate, developing a multi point analytical calibration programme through selection of Calcium lines in the programme according to calibrated standard solutions of calcium and measuring the CaF2 content for unknown test solutions when connected through led to a PC via the said programme. Description of the Invention CaC2 having known amount of CaF2 content and certified reference material of fluorspar having 96% CaF2 content were dry mixed mechanically in different proportions maintaining ratios in (wt / wt) of CaC2: CaF2 as 90: 10, 95: 5 and 97:3. The said constituents are preweighed and thoroughly mixed and homogenized in a pulveriser. Test sample solution of the said synthetic mixtures of CaC2 and CaF2 are prepared by adopting the following sequential steps- Sample Preparation • One gram of sample is taken in a beaker and 50 ml of distilled water is added during which the carbon from calcium carbide is liverated as acetylene and the calcium remains in the form of a slurry as calcium hydroxide along with un reacted calcium fluoride. CaF2 + CaC2 + 2H2O = C2H2 + Ca(OH)2 + CaF2 • After the reaction ceases, 10 ml of acetic acid is added and warmed gently for about 5 minutes, boiled and cooled during which the calcium hydroxide reacts with acetic acid to form calcium soluble acetate and the calcium fluoride remains as the residue. Ca(OH)2 + CaF2 + HOAc = Ca(Ac)2 + H2O + CaF2 • The solution is then filtered. • The residue of CaF2 is then ignited at 600 deg. C for about 30 minutes to convert it to ash and the ash is then transferred to a beaker. • 2 ml of dilute nitric acid along with 10 ml of perchloric acid is added to the beaker and heated for complete fuming to remove the fluoride by volatilization and calcium oxide remains as the residual mass. • After completion of the fuming, the residual mass is cooled and re dissolved in 20 ml of dilute HCI wherein calcium goes into solution as calcium choloride and volume is then macks up to 250 ml in a volumetric flask. CaO + 2HCI - CaF2 + H2 • From this solution, 0.1 equivalent is taken in a 250 mt volumetric flask along with 2gm of sodium carbonate and 1 gm of borax. • 20 mol of concentrated HNO3 is added and 5 ml of 2000 ppm pure copper solution as internal standard and volume made up to 250 ml for measurement by ICP AES. • The solution is then used for the measurement of Calcium ions in the solution which is then converted to % CaF2 by an empirical formula as given below: % CaF2 = 1.95 x % Ca The measurement datas are obtained through preparing calibration standard solution of calcium using pure calcium carbonate, developing a multi point analytical calibration programme. Calcium lines are selected in the analytical programme according to calibrated standard solution of calcium and the CaF2 content for unknown test solution are measured by connecting led to a PC via the said programme. Preparation of Calibration solutions • A five point analytical calibration program for the measurement of Ca was made. • First a 1000 ppm Calcium solution was made by dissolving 0.625 gm of pure calcium carbonate 20 ml of dilute hydrochloric acid and diluting it to 250 ml with distilled water. . Then calibration solutions for the above was made from the 1000ppm Ca solution having concentrations of 0, 15, 30, 75 and 150 ppm Ca in it. All the solutions were made in 100 ml volumetric flasks. To each of the flask 0.8 gm sodium carbonate and 0.4 gm borax along with 12 ml of cone HNO3 and 2ml of 2000 ppm copper was added. • The calibration standards are matched in amounts of sodium carbonate, borax, HCI and internal standard copper used in the sample preparation. The measurement of CaF2 via measurement of Ca lines by measurement through ICP Spectrometer is illustrated as follows in which Accompanying Figure 1 relates to a schematic diagram of the ICPAES method (Spectra Analytical, Germany). • The Ca line selected for the program is 422.24 nm. • A calibration curve was made on the spectrometer using the calibration solutions prepared. • The sample solution (1) is then delivered by sample introduction device (2) to the argon plasma via load coil (3) by nebulization in which energy [(by Radio Frequency generator (9) via an impedence matching network (10)] is supplied to the solution so that the surface tension isovercome and parts of the solution can leave it in the form of droplets. • The aerosol produced in the nebulizer chamber is transported to the plasma through a fine capillary in a stream of moistened argon gas, where the solution containing the analyte is vaporized and excited to produce the emission spectrum. • The radiation thus produced is passed into the entrance slit of the spectrometer optics or polychromator (5) where spectral dispersion takes place. The dispersed radiation is passed through an exit slit to the photomultiplier tube (7) via a detector (6) and measured by signal processing electronics. • The measured value is then converted into concentration of calcium using calibration functions with corresponding corrections through a computer processor (8) for final report of measured values. The measured values of the dispersed radiation is displayed and processed through the controller, • The measured value of Calcium is then converted to % CaF; using the empirical formula % CaF2 = % Ca x 1.95. Calcium lines are selected in the analytical programme according to calibrated standard solution of calcium and the CaF2 content for unknown test solution are measured by connecting led to a PC via the said programme. Illustration of the Invention Since no certified reference standards were available containing mixtures of CaC2 and CaF2, synthetic standards were prepared. CaC2 having known amount of CaC2 content and Certified reference material of Fluorspar having 96% CaF2 content were mechanically mixed in different proportions while keeping the ratios (wt/wt) of CaC2: CaF2 as 90:10, 95:5 and 97:3 by pre weighing each of them and then homogenizing the mixtures in a pulveriser in the laboratory. The solution of these synthetic mixtures were then prepared by following the sample preparation method given above and analyzed by ICP Spectrometry using the analytical program described above. The samples were analyzed in duplicate by two different chemists to ascertain its repeatability and reproducibility. The results are given below: Analysis of 90:10 mixture Analysis of 95:5 mixture Analysis of 97:3 mixture — .._, The results indicate that the developed method is capable of giving repeatable and reproducible results. This has now been introduced as a routine test method for quality control of mixtures of CaC2 and CaF2 used for desulphurization. The invention as herein described and illustrated should not be read in a restrictive manner as various adaptations, modifications and changes are possible as encampused within the scope of appended claims. WE CLAIM 1. A method for estimation of CaF2 content in a mixture of CaC2 and CaF2 (DS compound) for desulphurisation of pig iron produced from blast furnaces through ICPAES procedure comprising the sequential steps of preparing a sample of DS compound by taking a measured amount of DS compound in a beaker and adding predetermined quantity of distilled water in the baker forming a slurry of calcium hydroxide and unreacted calcium fluoride, after the reaction ceases, acetic acid is added in the said beaker and the content of the beaker is boiled on warming gently for a while, the solution is cooled to room temperature and obtaining a residue of CaF2 on filtration of the solution and igniting the residue at 600-650°C for 30 minutes and the resulted ash is transferred to a beaker wherein a small amount of dilute nitric acid along with perchloric acid is added, and the beaker is then heated for complete fuming to remove fluoride having a residual mass of calcium oxide,after which the resulted thickened mass is cooled and redissolved in dilute HCI and the resultant volume containing calcium chloride is made upto a predetermined volume in a volumetric flask by adding distilled water, from the resulted solution a small amount of it is transferred in a volumetric flask in which small amount of sodium carbonate and borax are added and in which an amount of concentrated HNO3 and pure copper solution as internal standard are added and the volume is made upto predetermined volume from which, the measurement datas are obtained through preparing calibration standard solution of calcium ions, developing a multi point analytical calibration programme by ICPAES method through selection of calcium lines in the programme according to calibrated standard solutions of calcium and measuring the CaF2 content for unknown test solutions by computer processing of the emission spectrum of sample solution containing calcium ions. 2. A method as claimed in claim 1 wherein calibration standards are matched in amounts of sodium carbonate, borax, Hcl and pure copper solution for internal standard and a calibration curve is made on the spectrometer using the calibration solutions prepared. 3. A method as claimed in the claims 1 & 2 wherein 1000 ppm Ca solution was prepared using calcium carbonate and the stock solution so prepared are diluted to the required levels for preparing the calibration solutions. 4. A method as claimed in the preceding claims wherein all calibration solutions were prepared in 100 ml volumetric flask. 5. A method as claimed in the preceding claims wherein the Ca lines selected for the programme is 4 22.24 nm and CaF2 content is determined from the empirical formula % CaF2 = % Ca x 1.95. 6. A method as claimed in the preceding claims wherein test datas as fof CaF2 are obtained form mixture of CaC2 and CaF2 in the ratios of 90:10.95:5 and 97:3. 7. A method as claimed in the preceding claims wherein in the ash 2 ml of dilute nitric acid along with 10 mi of perchloric acid are added and resultant solution is heated upto completion of fuming to remove fluoride leaving a residual mass of calcium oxide, 8. A method as claimed in claim 7 wherein the resulted thickened mass after completion of fuming is cooled and redissolved in 20 ml of dilute Hcl and the volume containing calcium chloride is made upto 250 ml in a volumetric flask. 9. A method as claimed in claim 8 wherein 0.1 equivalent solution form the said 250 ml solution is taken in a 250 ml volumetric flask along with 2gm of sodium carbonate and 1 gm of borax in which 20 ml of concentrated nitric acid and 5ml of 2000 ppm copper solution as internal standard are added and the volume is made upto 250 ml and the resulted sample is used for measurement of Ca ions by ICP AES procedures. 10.A method of estimation of CaF2 content in mixture CaC2 and CaF2 (DS compound) as herein described and illustrated. A method for estimation of CaF2 content in a mixture of CaC2 and CaF2 (DS compound) for desulphurisation of pig iron produced from blast furnaces through ICPAES procedure comprising the sequential steps of preparing a sample of DS compound by taking a measured amount of DS compound with distilled water and acitic acid and the whole content is boiled and then cooled to room temperature, obtaining a residue on filtration of the solution and igniting the residue and transferring the resulted ash to a beaker wherein dilute nitric acid along with perchloric acid is added, and the beaker is then heated for complete fuming , the resulted thickened mass is cooled and redissolved in dilute HCI, from the resulted solution a small amount of it is transferred in a volumetric flask along with sodium carbonate and borax, concentrated HNO3 and pure copper solution and the volume is made upto a predetermined volume and measuring the CaF2 content for unknown test solution by measuring the emission spectrum of the sample solutions containing calcium ions by computer processing.

Documents:

00923-kol-2006 abstract.pdf

00923-kol-2006 claims.pdf

00923-kol-2006 correspondence others.pdf

00923-kol-2006 description[complete].pdf

00923-kol-2006 drawings.pdf

00923-kol-2006 form-1.pdf

00923-kol-2006 form-2.pdf

00923-kol-2006 form-3.pdf

00923-kol-2006 g.p.a.pdf

00923-kol-2006-correspondence others-1.1.pdf

00923-kol-2006-form-9.pdf

923-KOL-2006-ABSTRACT 1.1.pdf

923-KOL-2006-CANCELLED DOCUMENT.pdf

923-KOL-2006-CLAIMS 1.1.pdf

923-KOL-2006-CORRESPONDENCE 1.1.pdf

923-KOL-2006-DESCRIPTION COMPLETE 1.1.pdf

923-KOL-2006-DRAWINGS 1.1.pdf

923-KOL-2006-FORM 1.1.pdf

923-kol-2006-form 15.pdf

923-KOL-2006-FORM 18.pdf

923-KOL-2006-FORM 2.1.pdf

923-kol-2006-granted-abstract.pdf

923-kol-2006-granted-claims.pdf

923-kol-2006-granted-correspondence.pdf

923-kol-2006-granted-description (complete).pdf

923-kol-2006-granted-drawings.pdf

923-kol-2006-granted-examination report.pdf

923-kol-2006-granted-form 1.pdf

923-kol-2006-granted-form 18.pdf

923-kol-2006-granted-form 2.pdf

923-kol-2006-granted-form 3.pdf

923-kol-2006-granted-gpa.pdf

923-kol-2006-granted-reply to examination report.pdf

923-kol-2006-granted-specification.pdf

923-KOL-2006-REPLY F.E.R.pdf

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