Methods of processing waste oil into grease after filtration treatment
Using waste oil to produce grease is an economically viable method, but it requires proper treatment and additives to ensure that the performance of the grease meets the requirements. The following is a simple production process without vacuum distillation or oil regeneration equipment.
- Waste oil treatment (purification of waste oil)
Because waste oil contains impurities, oxides and metal particles, basic purification treatment must be carried out to ensure that it is suitable for grease production. - Standing sedimentation
Pour the waste oil into a large container and let it stand for 24-48 hours to allow heavy impurities and water to naturally settle to the bottom.
Carefully extract the relatively clean oil on the upper layer to avoid stirring up the bottom sediment.
- Coarse filtration (removal of solid impurities)
Use filter cloth, filter screen (100-200 microns) or sand filtration equipment to remove coarse particle contaminants. - Adsorption purification (removal of colloids and oxides)
Add activated clay (Fuller’s Earth) or activated carbon to the oil, stir and heat to 80-100°C, and keep for 1-2 hours.
Filter to remove the clay or carbon residue to make the oil clearer.
- Grease manufacturing (thickening treatment)
The core of grease is to use thickeners to convert waste oil into semi-solid state. - Choose a suitable thickening system
Different thickeners determine the final performance of grease. The following are several common formulas:
✅ Calcium-based grease (low cost, good water resistance)
Suitable for lubrication of general mechanical equipment, simple to manufacture.
✅ Lithium-based grease (strong versatility)
Suitable for high-temperature parts such as automobile wheel hub bearings and motors.
✅ Aluminum-based grease (good high-temperature stability)
Suitable for high-temperature environments, but complex to manufacture.
- Preparation method of calcium-based grease (recommended)
Raw materials:
Waste oil 80-85%
Calcium hydroxide (slaked lime) 2-5%
Fatty acid (stearic acid or palmitic acid) 10-15%
Water appropriate amount
Steps:
1️⃣ Heat the waste oil to 80-90°C, add fatty acid (such as stearic acid), and stir until completely dissolved.
2️⃣ Add calcium hydroxide, continue stirring and heating to 100-110°C, and react to form soap base.
3️⃣ Continue heating and dehydration. When the temperature reaches above 120°C, the water evaporates and forms the basic structure of the grease.
4️⃣ Cool to 80°C and stir evenly until the grease thickens to the desired consistency.
5️⃣ Add antioxidants, rust inhibitors and other additives to further improve the performance of the grease.
6️⃣ Cool to room temperature and package for use after passing the inspection.
- Additives to improve grease performance
In order to improve the extreme pressure performance, oxidation resistance, water resistance, etc. of grease, the following additives can be added:
✅ Extreme pressure anti-wear agents (such as molybdenum disulfide MoS₂, sulfurized fatty acids) – improve wear resistance
✅ Antioxidants (such as phenols, amines) – improve high temperature stability
✅ Rust inhibitors (such as organic phosphates) – enhance corrosion resistance
✅ Thickeners (such as polyisobutylene) – enhance the adhesion of grease
IV. Summary
✔ Feasibility: It is feasible to produce grease using waste oil, as long as it is properly purified and thickened.
✔ Low cost: No vacuum distillation or expensive equipment is required, and grease can be produced by simple filtration + thickener.
✔ Scope of application: It can be used in non-high temperature and high load environments such as ordinary mechanical equipment, low-speed bearings, and agricultural machinery.
✔ Key control points:
Waste oil must be thoroughly purified, otherwise it will affect the performance of the grease.
The choice of thickener is very important. Calcium-based is suitable for ordinary lubrication, and lithium-based is suitable for high temperature and high load lubrication.
Necessary additives enhance the performance of grease.
Waste oil and new oil recycling resources reuse oil filter
If you want to recycle waste oil and new oil, and want to use an oil filter for treatment, the following are some common waste oil regeneration technologies and oil filter types to help you choose the right solution.
- The main methods for recycling waste oil and new oil
✅ Physical filtration regeneration method (suitable for lightly contaminated oil products)
It is mainly used to remove moisture, particulate impurities and partial oxidation products, suitable for hydraulic oil, gear oil, transformer oil, etc.
Equipment: centrifugal separator, vacuum oil filter, precision oil filter.
✅ Chemical treatment method (suitable for heavily polluted oil products)
It is suitable for waste oil with severe oxidation and high colloid content, such as engine oil, gear oil, etc.
Typical processes include ** acid washing, alkali washing, neutralization, adsorption (activated clay)**, etc.
Equipment: chemical reactor + vacuum filtration equipment
✅ Distillation regeneration method (suitable for high-quality regenerated oil)
Using high-temperature distillation technology to separate light components from heavy pollutants in oil products, the quality of new oil can be restored.
Equipment: thin film evaporator, molecular distillation unit (suitable for high-end lubricating oil regeneration).
✅ Hydrogenation treatment method (industrial regeneration, large investment)
Remove impurities such as sulfur, nitrogen, and oxygen through hydrocracking, so that the oil products can restore the performance similar to new oil.
Equipment: Hydrogenation reactor, high-pressure catalytic system, suitable for large-scale refineries or professional regeneration plants.
- Common oil filter types
Depending on the degree of oil pollution, processing volume and usage scenarios, different types of oil filters can be selected:
| Oil filter type | Working principle | Scope of application | Advantages and disadvantages |
| Vacuum oil filter | Removes moisture and gas through heating and vacuum suction | Applicable to turbine oil, hydraulic oil, transformer oil | Can remove moisture, but not suitable for heavily polluted oil |
| Centrifugal oil filter | Uses high-speed rotation centrifugal force to separate impurities | Applicable to lightly polluted lubricating oil | Can remove moisture, but ineffective for oxidation products |
| Precision oil filter (multi-stage filtration) | Uses PP cotton + activated carbon + ultrafiltration membrane to remove impurities and colloids | Applicable to gear oil, hydraulic oil, turbine oil | High filtration accuracy, but not suitable for heavily polluted oil |
| Plate and frame filter press | Uses filter cloth + pressure filtration to remove solid pollutants | Applicable to waste engine oil, gear oil, etc. | Large processing capacity, but filter cloth needs to be replaced frequently |
| Adsorption regeneration machine (activated clay method) | Adsorbs oxidation products and color through activated clay or silica gel | Applicable to engine oil and hydraulic oil | Can improve color and performance, but the cost is relatively high |
| Distillation regeneration equipment | Separates light and heavy components in waste oil through high-temperature distillation | Applicable to waste engine oil and industrial lubricants | Products close to new oil can be obtained, but the investment is relatively large |
- How to choose the right regeneration technology and oil filter?
👉 If it is lightly contaminated oil (high water content and few impurities)
✅ Vacuum oil filter + precision filter element filtration can remove moisture, gas and particulate impurities, suitable for transformer oil, hydraulic oil, etc.
👉 If it is heavily contaminated oil (severe oxidation, containing colloid and sediment)
✅ Adsorption regeneration machine + precision oil filter can remove oxides, colloids, and improve color and viscosity, suitable for engine oil, industrial lubricating oil, etc.
👉 If high-quality regenerated oil is required (similar to the effect of new oil)
✅ Thin film distillation + activated clay adsorption + precision filtration can remove most of the pollutants and obtain high-quality base oil, which can be re-deployed lubricating oil
- Recommended regeneration process
If you want to build a small waste oil regeneration production line, you can refer to the following process:
🛠️ Option 1: Lightly polluted oil (filtration + dehydration)
1️⃣ Preliminary sedimentation separation (stand for 24-48 hours to remove large particles of sediment)
2️⃣ Coarse filtration (50-100 micron filter) Remove larger impurities
3️⃣ Vacuum dehydration (heat to 80°C, vacuum extract water)
4️⃣ Precision filtration (5-10 microns) Further remove tiny impurities
✅ Suitable for lightly polluted oils such as hydraulic oil, transformer oil, turbine oil, etc.
🛠️ Option 2: Heavily polluted oil (chemical + filtration + adsorption)
1️⃣ Sedimentation + coarse filtration Remove solid impurities
2️⃣ Heat to 80°C, add appropriate amount of activated clay, stir for 1 hour
3️⃣ Stand and settle, filter clay residue
4️⃣ Precision filtration (5 microns) Improve cleanliness
✅ Suitable for engine oil, gear oil, and heavily polluted hydraulic oil
🛠️ Option 3: High-end regeneration (distillation + refining)
1️⃣ Sedimentation + coarse filtration Remove large particle impurities
2️⃣ High-temperature distillation (250-350°C) Separate light and heavy oils
3️⃣ Hydrofining (if conditions permit) Improve oil stability
4️⃣ Activated clay adsorption Remove color and oxides
5️⃣ Precision filtration (1-5 microns)
✅ Suitable for regeneration of high-quality base oils and re-adjustment of new lubricants
- Conclusion
💡 Waste oil can be regenerated using an oil filter, but the appropriate treatment method should be selected according to the degree of pollution.
💡 Lightly polluted oil can restore its performance through simple filtration + dehydration, and heavily polluted oil requires chemical or adsorption regeneration.
💡 If you want high-end regenerated oil, distillation + refining is required, but the equipment cost is relatively high.