Alternative Processes

Acid Clay Treatment (not offered by CEP)

In the acid clay process, used oil is typically filtered and then heated to remove debris, solid particles and water. It is then mixed with sulfuric acid which extracts metal salts, acids, aromatics, asphaltenes and other impurities. This forms a byproduct of acidic sludge that settles out of the oil. The remaining slightly acidic oil is mixed with active fuller’s earth (clay) to remove mercaptans and other contaminants and to improve color. This process requires approximately 0.4 lb of clay per gallon of oil. After clay is filtered from the oil, the final steps are neutralization and distillation of the oil. Acid clay treatment saw its heyday in the 1960s. According to a US DOE study, in 1960, 150 re-refiners were using acid/clay to treat 300 million gallons per year. By 1976, only 25 active oil recyclers were operating in the USA, processing 51 million gallons per year. Today, this method of recycling has fallen out of favor because it creates large amounts of acid sludge that is recognized as dangerous and hard to dispose of.

Vacuum Distillation (offered by CEP)

Vacuum distillation is a simplified “Front End” of the CEP Process. It separates components of the used oil including water, light hydrocarbons, gas oil, lube distillate and asphalt flux by boiling point. The addition of a vacuum prevents thermal cracking of the hydrocarbons. The main product of vacuum distillation is the lube distillate. While lube distillate technically meets the definition of API Group I base oil, it is generally not suitable for motor oil without additional treatment. The typical uses for lube distillate are bar and chain lube, process oil, form oil or fuel. Clay treatment can be used to improve the quality of the lube distillate.

Clay Treatment (offered by CEP)

Clay treatment is often used as a finishing step for lube distillate from vacuum distillation. There are two methods of clay treatment. The first feeds lube distillate through static beds of clay at elevated temperatures. The second mixes lube distillate with clay in contact reactors which is then kept in suspension and filtered to remove the clay. For the clay to effectively treat the oil, it needs to be activated by heating. These clays can be regenerated multiple times through a controlled combustion cycle before disposal. The clay treatment removes color, odor and some sulfur. The finished product meets API Group I base oil specifications but does not remove the unsaturated compounds to meet API Group II specifications. Clay treatment is generally better suited for smaller plant capacities due to lower capital investment.

CEP-VGX — Solvent Extraction for API Group I Base Oils

Solvent extraction is used to improve the quality of lube distillate that is produced from a vacuum distillation process. The solvent extracts polar compounds, additives and color bodies. It removes aromatics and increases saturate levels. One drawback to solvent extraction is that it removes the unsaturated compounds, reducing the overall yield. (In contrast, hydrotreating converts these compounds into more valuable base oil). Solvent extraction produces API Group I base oil that meets motor oil specifications but does not meet API Group II specifications due to its inability to remove sulfur.

Contact Chemical Engineering Partners today to see how CEP can help you!