Scraper for a Device for Breaking Bath Crust in an Electrolytic Cell Intended for Aluminium Production

Abstract

The invention relates to a scraper ( 40 ) for a crust breaking member ( 33 ) such as a crust breaker, useable to form an opening in an alumina and solidified bath crust in a fused bath electrolytic cell by a back and forth motion of the said member along a translation axis T. The scraper ( 40 ) according to the invention comprises a plurality of fingers ( 42 ) arranged around a reference axis S intended to coincide with the said translation axis T during use, so as to leave a space ( 44 ) between the fingers and the crust breaking member, and each finger ( 42 ) comprises at least one scraping member ( 43 ) projecting towards the crust breaking member ( 33 ). The scraper according to the invention is used to prevent the formation of an envelope on the surface of the crust-breaking member that can block the member in the scraper.

1 . A scraper for a crust breaking member in a crust breaking device useable to form an opening in an alumina and solidified bath crust in a fused bath electrolytic cell by a back and forth motion of the crust breaking member along a translation axis, the scraper comprising at least three fingers arranged around a reference axis that coincides with the translation axis during use, so as to form a space defined as a “clearance” between the fingers and the crust breaking member, and wherein each finger comprises at least one scraping member projecting towards the crust breaking member.  
   
   
       2 . The scraper of  claim 1 , wherein the number of fingers is between 6 and 10 inclusively.  
   
   
       3 . The scraper of  claim 1 , wherein the length of the fingers is greater than 100 mm.  
   
   
       4 . The scraper of  claim 1 , wherein the cross section of each finger is substantially uniform over at least 50% of its length.  
   
   
       5 . The scraper of  claim 1 , wherein each finger is straight and parallel to the reference axis of the scraper.  
   
   
       6 . The scraper of  claim 1 , wherein the distance between the points closest to the surface of the fingers adjacent to each other is greater than 10 mm over at least 50% of their length.  
   
   
       7 . The scraper of  claim 1 , wherein the separation between adjacent fingers increases with increasing distance from the reference axis so as to form an opening that flares outwards.  
   
   
       8 . The scraper of  claim 7 , wherein each finger comprises at least a first plane surface element and a second plane surface element arranged so that the first surface element of each finger and the second surface element of an adjacent finger are facing each other and at an angle from each other so as to form an opening that flares towards the outside of the scraper.  
   
   
       9 . The scraper of  claim 8 , wherein the angle is more than 10° with respect to the reference axis.  
   
   
       10 . The scraper of  claim 1 , wherein the clearance between each finger and the crust breaking member is more than 10 mm.  
   
   
       11 . The scraper of  claim 1 , wherein each finger has a free end and wherein the at least one scraping member is located at the free end of the finger.  
   
   
       12 . The scraper of  claim 1 , wherein each finger is fixed to a support element.  
   
   
       13 . The scraper of  claim 12 , wherein the at least one scraping members is arranged at a determined distance from the support element equal to at least 100 mm.  
   
   
       14 . The scraper of  claim 13 , wherein the support element comprises attachment means.  
   
   
       15 . A crust breaking device intended for an aluminium production cell using fused bath electrolysis, the crust breaking device comprising: a scraper for a crust breaking member in the crust breaking device useable to form an opening in an alumina and solidified bath crust in the fused bath electrolytic cell by a back and forth motion of the crust breaking member along a translation axis, the scraper comprising at least three fingers arranged around a reference axis that coincides with the translation axis during use, so as to form a space defined as a “clearance” between the fingers and the crust breaking member, and wherein each finger comprises at least one scraping member projecting towards the crust breaking member.  
   
   
       16 . A crust-breaker—feeder for use in an aluminium production cell using fused bath electrolysis and comprising a scraper for a crust breaking member in a crust breaking device useable to form an opening in an alumina and solidified bath crust in a fused bath electrolytic cell by a back and forth motion of the crust breaking member along a translation axis, the scraper comprising at least three fingers arranged around a reference axis that coincides with the translation axis during use, so as to form a space defined as a “clearance” between the fingers and the crust breaking member, and wherein each finger comprises at least one scraping member projecting towards the crust breaking member.  
   
   
       17 . A crust breaking and measurement device adapted for use in an aluminium production cell using fused bath electrolysis and comprising a scraper for a crust breaking member in the crust breaking and measurement device useable to form an opening in an alumina and solidified bath crust in a fused bath electrolytic cell by a back and forth motion of the crust breaking member along a translation axis, the scraper comprising at least three fingers arranged around a reference axis that coincides with the translation axis during use, so as to form a space defined as a “clearance” between the fingers and the crust breaking member, and wherein each finger comprises at least one scraping member projecting towards the crust breaking member.  
   
   
       18 . Use of the scraper of  claim 1 , in an aluminium production cell using fused bath electrolysis.