Method for extraction of bitumen from oil sands using lime

Abstract

In a method for enhancing the efficiency of bitumen recovery from oil sands ore, CaO lime (or Ca(OH) 2 ) is mixed into an oil sands ore-water slurry prior to or during the operation of slurry-based bitumen extraction processes. The lime is introduced at dosages effective to reduce the electro-chemical attraction between clay particles and bitumen in the slurry, thereby promoting detachment of clay particles from bitumen droplets in the ore-water slurry. This occurs because water-soluble asphaltic acids formed at the bitumen-water interface act as surfactants which reduce or eliminate the activity of Ca 2+ and Mg 2+ ions binding the clay particles and bitumen together. The detachment of clay particles promotes the attachment of air bubbles to the bitumen droplets, thereby forming a bitumen-rich froth which will float to the surface of the ore-water slurry, thus facilitating bitumen recovery.

1 . A method for reducing clay dispersion in oil sands tailings, said method comprising the step of mixing lime into an oil sands ore-water slurry in association with a slurry-based bitumen extraction process. 
     
     
         2 . A method as in  claim 1  wherein the lime is introduced into the ore-water slurry in a chemical form selected from the group consisting of calcium oxide (CaO) and calcium hydroxide (Ca(OH) 2 ). 
     
     
         3 . A method as in  claim 1  wherein the lime is introduced into the ore-water slurry in the form of calcium oxide (CaO) and at a dosage in the range between approximately 60 mg of CaO per kg of oil sands ore and 350 mg of CaO per kg of oil sands ore. 
     
     
         4 . A method for reducing claim content in bitumen froth produced in a slurry-based bitumen extraction process, said method comprising the step of mixing lime into an oil sands ore-water slurry in association with the slurry-based bitumen extraction process. 
     
     
         5 . A method as in  claim 4  wherein the lime is introduced into the ore-water slurry in a chemical form selected from the group consisting of calcium oxide (CaO) and calcium hydroxide (Ca(OH) 2 ). 
     
     
         6 . A method as in  claim 4  wherein the lime is introduced into the ore-water slurry in the form of calcium oxide (CaO) and at a dosage in the range between approximately 60 mg of CaO per kg of oil sands ore and 350 mg of CaO per kg of oil sands ore. 
     
     
         7 . A method for reducing the concentration of water-soluble naphthenic acid salts in release water produced in a slurry-based bitumen extraction process, said method comprising the step of mixing lime into an oil sands ore-water slurry in association with the slurry-based bitumen extraction process. 
     
     
         8 . A method as in  claim 7  wherein the lime is introduced into the ore-water slurry in a chemical form selected from the group consisting of calcium oxide (CaO) and calcium hydroxide (Ca(OH) 2 ). 
     
     
         9 . A method as in  claim 7  wherein the lime is introduced into the ore-water slurry in the form of calcium oxide (CaO) and at a dosage in the range between approximately 60 mg of CaO per kg of oil sands ore and 350 mg of CaO per kg of oil sands ore.