Reuse of Used Oil in a Rolling Mill

Abstract

The present invention relates to a lubrication method in a hot-rolling mill by means of a lubricant comprising used oil, said used oil at least partly stemming from waste coming from a cold-rolling mill.

1 . A lubrication method in a hot-rolling mill by means of a lubricant comprising used oil, said used oil stemming at least partly from waste coming from a cold-rolling mill. 
     
     
         2 . The method according to  claim 1 , characterized in that said used oil stems from waste or from a mixture of wastes from one or several of the steps occurring in the manufacturing of a metal. 
     
     
         3 . The method according to  claim 1 , characterized in that the waste comprises a used emulsion, an oily sludge or a waste oil. 
     
     
         4 . The method according to  claim 3 , characterized in that the used emulsion and the oily sludge are treated by means of a separation technique in order to extract said used oil. 
     
     
         5 . The method according to  claim 3 , characterized in that said used oil is taken from a supernatant layer above the aqueous phase of the used emulsion. 
     
     
         6 . The method according to  claim 5 , characterized in that the used oil taken from the supernatant layer above the aqueous phase of the used emulsion is reused as a lubricant in a hot-rolling mill without being subjected to any purification treatment. 
     
     
         7 . The method according  claim 1 , characterized in that the lubricant comprises a mixture of used oil and of water. 
     
     
         8 . The method according to  claim 7 , characterized in that the mixture comprises an emulsifier. 
     
     
         9 . The method according to  claim 1 , characterized in that the lubricant comprises the used oil not mixed with water. 
     
     
         10 . The method according to  claim 1 , characterized in that it results in a force reduction of the order of 30% during hot-rolling of a steel sheet.