METHOD OF RECYCLING WASTE LUBRICANT

1 . A method of recycling waste lubricant, the method comprising:

providing a waste lubricant-derived oil fraction;

pretreating the waste lubricant-derived oil fraction; and

hydrocracking the pretreated waste lubricant-derived oil fraction.

2 . The method of claim 1 , wherein the waste lubricant-derived oil fraction has a kinematic viscosity at 40° C. in a range of 20 to 60 cSt and a pour point of lower than 0° C.

3 . The method of claim 1 , wherein the pretreating comprises performing solvent extraction on the waste lubricant-derived oil fraction.

4 . The method of claim 1 , further comprising a first blending operation of blending the waste lubricant-derived oil fraction with a hydrocarbon feedstock to produce a first formulation, prior to the hydrocracking.

5 . The method of claim 4 , wherein the first formulation comprises 1% to 10% by volume of the waste lubricant-derived oil fraction with respect to the total volume thereof.

6 . The method of claim 1 , wherein the method further comprises recovering a plurality of fractions including a first fraction and a second fraction, from the product of the hydrocracking.

7 . The method of claim 6 , wherein the first fraction has a boiling point in a range of boiling point of fuel oil.

8 . The method of claim 6 , wherein the second fraction has a boiling point higher than the boiling point of the first fraction.

9 . The method of claim 6 , further comprising a second blending operation of blending the second fraction with a separate waste lubricant-derived oil fraction to produce a second formulation.

10 . The method of claim 9 , wherein the separate waste lubricant-derived oil fraction used in the second blending is introduced in an amount of 3% to 50% by volume with respect to the volume of the second formulation.

11 . The method of claim 9 , further comprising catalytically dewaxing the second formulation.

12 . The method of claim 11 , further comprising:

hydrofinishing the catalytically dewaxed second formulation; and

recovering the product of the hydrofinishing as a lube base oil.

13 . A method of recycling waste lubricant, the method comprising:

providing a first waste lubricant-derived oil fraction;

blending the waste lubricant-derived oil fraction with a hydrocarbon feedstock to produce a first formulation;

pretreating the first formulation by subjecting the first formulation to a solvent extraction operation;

hydrocracking the pretreated first formulation;

recovering a first fraction and a second fraction from the hydrocracking operation;

blending the second fraction with a second waste lubricant-derived oil fraction to produce a second formulation;

catalytically dewaxing the second formulation, and

hydrofinishing the dewaxed second formulation to produce a lube base oil.

14 . The method of claim 13 , wherein the first waste lubricant-derived oil fraction has a kinematic viscosity at 40° C. in a range of 20 to 60 cSt and a pour point of −21° C. to 0° C.

15 . The method of claim 14 , wherein the waste lubricant-derived oil fraction is a refined oil fraction from a process in which waste lubricant undergoes at least one of a centrifugal separation, atmospheric distillation, vacuum distillation, or any combination thereof, and

wherein the refined oil fraction has a sulfur content of less than 200 ppm, a nitrogen content of less than 100 ppm, and a chlorine content of less than 2000 ppm.