Deashing and demetallization of used oil using a membrane process

A method for treating used oil to remove ash and metal contaminants therefrom, the metal contaminants including at least one of the components of iron, lead, copper, zinc, sodium, magnesium, and calcium, to provide a purified oil product having less than 10 ppm of at least one of the contaminants and less than 0.15 wt. % of ash content, the method consisting essentially of:

• (a) providing a body of oil to be purified;
• (b) contacting said oil with diammonium phosphate to condition said ash and said metal contaminants therewith to form an ash and metal containing material removable during membrane purification of said oil, said treating being effected at a temperature range of 50 to 200.degree. C.;
• (c) providing a porous inorganic membrane module having a high pressure side and a low pressure side, said membrane having a pore size in the range of 50 to 2000 .ANG.;
• (d) introducing said chemically treated oil at a temperature in the range of 60 to 175.degree. C. to the high pressure side of said membrane module to provide an oil permeate on the low pressure side and an ash and metal-rich concentrate on the high pressure side to separate ash and metals in said oil to provide said highly purified oil product.

A method for treating used oil to remove ash and metal contaminants therefrom, the metal contaminants including at least one of the components of iron, lead, copper, zinc, sodium, magnesium, and calcium, to provide a highly purified oil product having very low levels of metal contaminants and ash content, the method consisting essentially of:

• (a) providing a body of oil to be purified;
• (b) contacting said oil with diammonium phosphate to condition said ash and said metal into a material rejectable during membrane purification of said oil, said treating being effected at a temperature range of 50 to 160.degree. C. to provide chemically treated oil;
• (c) providing a porous inorganic membrane module having a high pressure side and a low pressure side, said membrane having a pore size in the range of 50 to 2000 .ANG.;
• (d) introducing said chemically treated oil at a temperature in the range of 60 to 175.degree. C. to the high pressure side of said membrane module to provide an oil permeate on the low pressure side and an ash and metal-rich concentrate on the high pressure side to remove ash and metals, said method having the ability to yield an oil permeate containing 10 ppm or less of at least one of the group consisting of iron, copper and lead, 15 ppm or less of zinc, and less than 300 ppm ash, thereby providing a highly purified oil product.

A method suitable for treating used oil to remove ash and metal contaminants therefrom to provide a purified oil product having a reduced level of ash and metals, the method consisting essentially of:

• (a) providing a body of oil to be purified;
• (b) providing a porous inorganic membrane module having a high pressure side and a low pressure side;
• (c) introducing said oil to the high pressure side of said membrane module to provide an oil permeate on the low pressure side and an ash and metal-rich concentrate on the high pressure side to remove ash and metals from said oil to provide an oil permeate extremely low in ash and metal content;
• (d) chemically treating the ash and metal-rich concentrate to facilitate removal of ash and metal therefrom to provide chemically treated oil;
• and
• (e) introducing said chemically treated oil to said membrane module to provide an ash and metal-rich concentrate and a purified oil permeate.

A method suitable for treating used oil to remove ash and metal contaminants therefrom with minimum oxidation of the oil, the metal including at least one of the components of iron, lead, copper, zinc, sodium, magnesium, and calcium, to provide a highly purified oil product, the method consisting essentially of:

• (a) providing a body of oil to be purified;
• (b) chemically treating at least a portion of said oil to form said ash and metals in the oil into a material rejectable during membrane purification of said oil;
• (c) providing a porous inorganic membrane module having a high pressure side and a low pressure side;
• (d) introducing said chemically treated oil to the high pressure side of said membrane module to provide an oil permeate on the low pressure side and an ash and metal-rich concentrate on the high pressure side to separate ash and metals from said oil to provide said highly purified oil product at an improved level of throughput of said membrane compared to feed oil not chemically treated, said highly purified oil product having less than 10 ppm of at least one of the contaminants selected from iron, copper, boron and calcium and having less than 0.15 wt. % ash;
• and
• (e) recycling said metal-rich concentrate to said body oil to be purified.

A method suitable for treating used oil to remove ash and metal contaminants therefrom with minimum oxidation of the oil, the metal including at least one of the components of iron, lead, copper, zinc, sodium, magnesium, and calcium, to provide a highly purified oil product, the method consisting essentially of:

• (a) providing a body of oil to be purified;
• (b) introducing used oil to said body;
• (c) withdrawing a first stream of oil from said body;
• (d) chemically treating said first stream of oil to react ash and metals contained therein to provide a chemically treated stream and to facilitate removal of ash and metals during membrane purification of said oil;
• (e) returning said chemically treated stream to said body;
• (f) withdrawing a second stream of oil from said body;
• (g) introducing said chemically treated oil to the high pressure side of said membrane module to provide an oil permeate on the low pressure side and an ash and metal-rich concentrate on the high pressure side to separate ash and metals from said oil to provide said highly purified oil product at an improved level of throughput of said membrane compared to feed oil not chemically treated, said highly purified oil product having less than 10 ppm of at least one of the contaminants selected from iron, copper, boron and calcium and having less than 0.15 wt. % ash;
• and
• (h) recycling said ash and metal-rich concentrate back to said body of oil.

A method suitable for treating used oil to remove ash and metal contaminants therefrom with minimum oxidation of the oil, the metal including at least one of the components of iron, lead, copper, zinc, sodium, magnesium, and calcium, to provide a highly purified oil product, the method consisting essentially of:

• (a) providing a body of oil to be purified;
• (b) chemically treating at least a portion of said oil at a temperature not greater than 200.degree. C. to form said ash and metals in the oil into a material rejectable during membrane purification of said oil;
• (c) providing a porous inorganic membrane module having a high pressure side and a low pressure side;
• and
• (d) introducing said chemically treated oil to the high pressure side of said membrane module to provide an oil permeate on the low pressure side and an ash and metal-rich concentrate on the high pressure side to separate ash and metals from said oil to provide said highly purified oil product at an improved level of throughput of said membrane compared to feed oil not chemically treated, said highly purified oil product having less than 10 ppm of at least one of the contaminants selected from iron, copper, boron and calcium and having less than 0.15 wt. % ash.