System And Method For Treating Tailings From Bitumen Extraction

Abstract

A system and method for treating tailings from a bitumen froth treatment process such as TSRU tailings. The tailings are dewatered and then combusted to convert kaolin in the tailings into metakaolin. Calcined fines and heavy minerals may be recovered from the combustion products, namely from the flue gas and bottom ash.

1 . A system for treating tailings from a bitumen froth treatment process, the tailings comprising sand, clay comprising kaolin, and water, and hydrocarbons, the system comprising:
 a dewatering unit for removing water from a tailings stream, producing a dewatered tailings stream and a tailings water stream;   a combustion chamber for combusting the dewatered tailings stream, carrying out a chemical reaction whereby kaolin converts to metakaolin, and producing a fly ash and a bottom ash; and   a calcined fines fly ash recovery unit for recovering calcined fines comprising metakaolin from the fly ash or a calcined fines bottom ash recovery unit for recovering calcined fines comprising metakaolin from the bottom ash.   
     
     
         2 . The system of  claim 1  wherein the dewatering unit comprises at least two dewatering units. 
     
     
         3 . The system of  claim 2  wherein the dewatering unit comprises a hydrocycloning unit for removing coarse residue and a thickening unit for removing fine residue. 
     
     
         4 . The system of  claim 3  wherein the thickening unit uses a flocculent, a coagulant, and dilution water to flocculate fine particles for removal. 
     
     
         5 . The system of  claim 4  wherein the flocculent and the coagulant are added to the thickening unit at a single injection point. 
     
     
         6 . The system of  claim 4  wherein the flocculent and the coagulant are added to the thickening unit at multiple injection points. 
     
     
         7 . The system of  claim 4  wherein the dilution water is a portion of hot water separated from the thickening unit. 
     
     
         8 . The system of  claim 7  wherein a portion of the hot water separated from the thickening unit is for spraying at a water interface in the thickening unit to assist in settling of light asphaltene aggregates. 
     
     
         9 . The system of  claim 4  wherein the flocculent used in the thickening unit is anionic polyacrylamide. 
     
     
         10 . The system of  claim 1  wherein the bitumen froth treatment process is a paraffinic froth treatment process. 
     
     
         11 . The system of  claim 1  wherein the tailings are tailings solvent recovery unit tailings. 
     
     
         12 . The system of  claim 1  wherein the combustion chamber is for converting kaolin to metakaolin at 500° C. to 1000° C. 
     
     
         13 . The system of  claim 1  comprising the calcined fines fly ash recovery unit. 
     
     
         14 . The system of  claim 1  comprising the calcined fines bottom ash recovery unit. 
     
     
         15 . The system of  claim 1  wherein the combustion chamber is a fluidized bed combustion chamber. 
     
     
         16 . The system of  claim 15  wherein the fluidized bed combustion chamber comprises a bed, the bed further comprising material from the dewatered tailings stream, and inert products derived from bitumen mining. 
     
     
         17 . The system of  claim 16  wherein levels of calcium, and alkalinity in the tailings liquid are consumed to react with SO x .