Process for reducing contaminants in condensate resulting from the conversion of bauxite to alumina

Abstract

This invention relates to a process for reducing the contaminants in condensate resulting from the refining of alumina.

1 . A process for reducing contaminants in contaminated condensate resulting from the refining of aluminum, wherein said process comprises the steps of: 
 (a) adding an inorganic coagulant to the condensate in an amount sufficient to partially or completely coagulate the solids in said condensate; and    (b) filtering said condensate.    
     
     
         2 . The process of  claim 1  wherein the temperature of the condensate is from 80° C. to 100° C.  
     
     
         3 . The process of  claim 2  wherein pH of the condensate is adjusted to from about 7.0 to about 9.0.  
     
     
         4 . The process of  claim 3  wherein the acid is sulfuric acid.  
     
     
         5 . The process of  claim 4  wherein the filter used for filtering is an upflow sand filter.  
     
     
         6 . The process of  claim 5  wherein the condensate is generated from the production of alumina from bauxite ore.  
     
     
         7 . The process of  claim 6  wherein the process used to prepare the alumina from bauxite ore is the Bayer process.  
     
     
         8 . The process of  claim 7  wherein the condensate is selected from the group consisting of digestion condensate, evaporator condensate, and clean condensate from surface condensers.  
     
     
         9 . The process of  claim 8  wherein the condensate is clean condensate from surface condensers.  
     
     
         10 . The process of  claim 9  wherein the purified condensate is recycled in the Bayer process for converting bauxite ore to alumina.  
     
     
         10 . The process of  claim 9  wherein the wherein the condensate is further purified by demineralization with ion exchange, reverse osmosis, evaporation, partial demineralization, degassification, decarbonation, and/or mixed bed demineralization.  
     
     
         11 . The process of  claim 10  wherein the purified process condensate is used as boiler feedwater.  
     
     
         12 . The process of  claim 1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  9 ,  10  or  11  wherein the inorganic coagulant is selected from the group consisting of polychlorinated aluminum, polyaluminum silicate sulfate, lime, alum, ferric chloride, ferrous sulfate, ferric sulfate, aluminum sulfate, aluminum chloride, polyaluminum chloride, aluminum chlorohydrate, and sodium aluminate, and alkali metal silicates, and mixtures thereof.