Title of Invention | AN ELECTROLYSIS PROCESS FOR REMOVAL OF HEXAVALENT CHROMIUM FROM WASTE WATER OF CHROME ORE MINES |
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Abstract | The present invention relates to an electrolysis process for removal of hexavalent chromium from waste water of chrome ore mines comprising the following steps of passing a DC current through electrodes in an electrolysis tank containing hexavalent chromium waste water and electrolysing water to produce bubbles of hydrogen and oxygen characterised in that during anodic oxidation reaction, the Fe2+ ions and large number of electrons are released which reduce the hexavalent dispersed chromium to Cr(III) at cathode, forming dispersed particles of chromite which collide and adhere with the upward moving hydrogen and oxygen gas bubbles and float them to the surface of the water in the form of foam and skimming off the top surface foam of waste water containing chromite in the electrolysis tank. |
Full Text | FIELD OF THE INVENTION The present invention relates to an electrolysis process treatment to minimize hexavalent chromium to trace levels from waste water of chrome ore mines BACKGROUND OF THE INVENTION Chromlte ore mining operations involve the handling of the mines waters which is termed as mines wastewater. This water contain hexavalent chromium in the range of 0.3 ppm to less than 1 ppm depending on natural weathering conditions and nature of deposit and if It exceeds 0.05 ppm It could be environmental unfriendly as per world health organization norm. The conversion of this toxic hexavalent chromium, Cr(VI) to non-toxic Cr(III) is useful way for the remediation of hexavalent chromium. Conventionally chemical reduction of Cr(VI) to Cr(111) using reductant like FeS04, has been a common method employed for Cr(VI) remediation in mines wastewater. However, use of chemical reluctance is undesirable in industrial practice due to their unavoidable process and environmental unfriendly nature. This method also adds other pollutant like sulphur to the wastewater which Is not desirable. Hence there is need to address this issue using alternative clean and environmental friendly process technologies which does not add pollutants to the mine wastewater. The present invention has proposed solution of the above mentioned difficulties of the existing practice through employment of electrolysis process. DESCRIPTION OF THE INVENTION One objective of the invention is to use electrolysis of water containing the hexavalent chromium by passing Dc current through iron electrodes in a tank. Another objective of the invention is to produce hydrogen and oxygen gas bubbles during electrolysis. A yet another objective of the invention is to reduce hexavalent chromium to Cr(III) at cathode by electrons released from anodic oxidation reaction when Fe2+ions and large number of electrons are released and forming dispersed solid particles of Chromite. A further objective of the Invention Is to float the suspended particles of Chromite at the top of the electrolysis tank through colliding those particle with hydrogen and oxygen gas bubbles and floating those particles at the surface adhered with the upwardly moving hydrogen and oxygen gas bubbles. A still another objective of the invention is to skimming off the accumulated dispered particles in the form of foam at the surface of the tank with a bladded transport system or skimmer. The proposed Invention will be better understood from the following description with reference to the accompanying drawings in which Figure 1 shows, in photograph the experimental set up for electrolysis of wastewater from chromite mines. Figure 2 shows in graph plotted time Vs Cr(VI) [ppm] Hexavalent chromium content in waste waters with time variation. The electrolysis experimental setup is shown in Fig. 1. The Iron electrodes (1) are arranged at the bottom of a tank ((2) filled with the wastewater (3) containing hexavalent chromium. DC current is passed through the electrodes, electrolyzing the water and producing bubbles of hydrogen and oxygen gas. During the anodic oxidation reaction, the Fe2+ ions and large number of electrons are released which reduces the hexavalent chromium to Cr(III) at cathode, and forms the dispersed solid particles of chromite. As the hydrogen and oxygen bubbles float to the top of the tank, they collide with these particles suspended in the water on the way up, adhere to them and Moat them to the surface of the water. Dispersed particles accumulate at the surface of the tank in the form of foam. The foam is then skimmed off the surface of the tank with the bladed transport system or skimmer. The electrolysis operation is carried out with a stirring arrangement (4) to enhance homogenised generation in the electrolytic tank. An AC to DC rectifier (5) supply DC current In the tank through electrodes (1). The stirring assembly (4) is also connected as the DC supply of the rectifier to provide stirring during electrolysis. The reactions taking part in electrolysis process is stated as below Anodic oxidation reactions Cathodic reduction reaction The invention is exemplified with the equipment of Fig 1 as follows:- The electrolysis experiments with wastewater for removing hexayalent chromium were carried out at current density of 42 A/m2 and a sample size of 4 liters. The water samples collected at different time Intervals were subjected to hexavalent chromium analysis. The results of hexavalant chromium reduction with respect to time are shown In Fig. 2. It can be seen from Fig. 2, that the complete reduction of dissolvable Cr (VI) to trace levels (i.e. less than 0.01 ppm) have taken place in the initial 5 minutes Itself. Hence even 5 minutes of time at current density of 42 A/m2 is sufficient to remove hexavalent chromium from the mines wastewater. The present invention for Cr +6 removal from waste water is faster, easier to control, cost and space effective. The invention as narrated herein above should not be read and construed in a restrictive manner as varbus modifications, alterations of sizes and parameters used in the process and adaptations are possible within the scope and ambit of the invention as defined in the encompassed appended claim. WE CLAIM 1. An electrolysis process for removal of hexavalent chromium from waste water of chrome ore mines comprising the following steps: - passing a DC current through electrodes in an electrolysis tank containing hexavalent chromium waste water; - electrolysing water to produce bubbles of hydrogen and oxygen; characterised in that during anodic oxidation reaction, the Fe2+ ions and large number of electrons are released which reduce the hexavalent dispersed chromium to Cr(III) at cathode, forming dispersed particles of chromite which collide and adhere with the upward moving hydrogen and oxygen gas bubbles and float them to the surface of the water in the form of foam and skimming off the top surface foam of waste water containing chromite in the electrolysis tank. 2. An electrolysis process for removal of hexavalent chromium as claimed in claim 1, wherein the electrolysis tank is maintained with a current density of 42 A/m2 for 4 liters of waste water sample. 3. An electrolytic process as claimed in claim 1, wherein the Cr(VI) from waste water is removed less than 0.01 ppm. 4. An electrolytic process as claimed in claim 3, wherein hexavalent chromium is removed to trace levels of less than 0.01 ppm within 5 minutes on carrying out the electrolysis at current density of 42 A/m2. 5. An electrolytic process as claimed in the preceding claims, wherein the foam containing chromite is skimmed off the surface of the electrolytic tank with a bladed transport system or a skimmer. 6. An electrolysing process as claimed in the preceding claims, wherein a stirring arrangement is provided with the electrolysing cell to stir the waste water during electrolysis when required. 7. An electrolysing device for removal of hexavalent chromium from waste water of chrome ore mines comprising a electrolysing cell (2) with Cr(VI) containing waste water (3) having iron electrodes (1), stirring assembly (4), and an AC to DC rectifier to supply a DC current to the electrolysis tank (2) through the electrodes (1) containing the waste water, wherein at anode oxidation reaction occur to release Fe2+ ions and large number of electrons and at cathode reduction reaction occur to release suspended solid particles of chromite, which are collided with upward moving hydrogen and oxygen gas bubbles generated by anodic reaction and the said upward moving gas bubbles being adhered with the suspended chromite particles float the same to the top surface of waste water in the electrolysis cell (2) in the form of foam and is removed by skimming. 8. The clean water being removed of hexavalent chromium from waste water of chrome ore mines, produced according to the method of claim 1. The present invention relates to an electrolysis process for removal of hexavalent chromium from waste water of chrome ore mines comprising the following steps of passing a DC current through electrodes in an electrolysis tank containing hexavalent chromium waste water and electrolysing water to produce bubbles of hydrogen and oxygen characterised in that during anodic oxidation reaction, the Fe2+ ions and large number of electrons are released which reduce the hexavalent dispersed chromium to Cr(III) at cathode, forming dispersed particles of chromite which collide and adhere with the upward moving hydrogen and oxygen gas bubbles and float them to the surface of the water in the form of foam and skimming off the top surface foam of waste water containing chromite in the electrolysis tank. |
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01049-kol-2007-correspondence others 1.1.pdf
01049-kol-2007-correspondence others.pdf
01049-kol-2007-description complete.pdf
1049-KOL-2007-(05-12-2011)-FORM-27.pdf
1049-KOL-2007-ABSTRACT 1.1.pdf
1049-KOL-2007-AMANDED CLAIMS.pdf
1049-KOL-2007-CANCELLED PAGES 1.1.pdf
1049-KOL-2007-CORRESPONDENCE 1.2.pdf
1049-kol-2007-correspondence.pdf
1049-KOL-2007-DESCRIPTION (COMPLETE) 1.1.pdf
1049-KOL-2007-DRAWINGS 1.1.pdf
1049-kol-2007-examination report.pdf
1049-kol-2007-granted-abstract.pdf
1049-kol-2007-granted-claims.pdf
1049-kol-2007-granted-description (complete).pdf
1049-kol-2007-granted-drawings.pdf
1049-kol-2007-granted-form 1.pdf
1049-kol-2007-granted-form 2.pdf
1049-kol-2007-granted-specification.pdf
1049-KOL-2007-PETITION UNDER RULE 137.pdf
1049-kol-2007-reply to examination report-1.1.pdf
1049-KOL-2007-REPLY TO EXAMINATION REPORT.pdf
Patent Number | 247407 | |||||||||
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Indian Patent Application Number | 1049/KOL/2007 | |||||||||
PG Journal Number | 14/2011 | |||||||||
Publication Date | 08-Apr-2011 | |||||||||
Grant Date | 05-Apr-2011 | |||||||||
Date of Filing | 27-Jul-2007 | |||||||||
Name of Patentee | TATA STEEL LIMITED | |||||||||
Applicant Address | JAMSHEDPUR | |||||||||
Inventors:
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PCT International Classification Number | C02F1/50 | |||||||||
PCT International Application Number | N/A | |||||||||
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