An in-depth discussion on the acid-base washing and clay refining process for lubricating oils – A highly practical technical discussion for experts
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In China, acid washing is still the dominant method for producing lubricating oils. What I would like to discuss is this: after acid washing, is it done by neutralizing the mixture with alkali once to reach a pH level of 6.5–7, and then are the alkaline residues discarded together with the acid residues? Put the acid slag first, then neutralize it, and after that add the alkali slag? Refined post-white clay - filtration! It’s hard to filter! This is rather troublesome! Still, perform alkaline cleaning until the pH reaches 3-5, while removing the acid and alkali residues! Then, the white rabbit undergoes refinement and filtration; it must also be neutralized. The problem is that neutralization is very difficult! After filtration, the neutralization process takes a long time; even when the pH is adjusted to 6-7, the oil remains opaque due to white suspended particles! It can’t be sold! If it’s under filtration, that’s impossible, right? It simply can’t get through at all! We use a plate and frame filter, with two layers of diaphragms! May I ask experts how the first method addresses the difficulty in filtering, and how the second method solves the problems of long neutralization time and poor oil brightness (are there suspended particles, i.e., alkaline residues)?
Poster: I don’t dare claim to be an expert; we’re just discussing this. In my opinion, after pickling, the mixture should be left to settle for 12 hours before the acid sludge is removed. Then, the waste oil should be heated to 80 degrees for alkaline cleaning; after stirring for 30 minutes, it should be left to settle again for 12 hours before the alkaline sludge is removed. The pH value should be checked, and if it’s within the normal range, the process can proceed to steps such as clay purification and filtration. To improve the filtration speed, the waste oil can be heated to 60–80 degrees. A negative pressure can also be applied to the filtration tank to speed up the filtration process. The main reason why the filtering doesn’t work, as you mentioned, is that the lubricant has a high viscosity and poor fluidity. Second, the settling time is short, and the oil contains a large amount of particulates. Thirdly, it’s possible that the mesh size of the filtering fabric is too large; as a result, the lubricant molecules are relatively large in size, which slows down the filtration process. I’m not sure if the above will be helpful to you. Also, I’m not very familiar with your manufacturing processes. We can discuss more things together in the future.
Thank you! Viscosity shouldn’t be an issue; it’s grade 100 at 40 degrees Celsius, and filtering is done after heating to 80 degrees!
Yeah, after filtering the oil isn’t clear; it’s hazy (slightly cloudy). This problem can’t be solved. I’m seeking advice!
I do have some experience regarding acid-base purification. The issue of the oil not being transparent and being difficult to filter, as mentioned by the original poster, is caused by certain salts that are produced as a result of acid-base neutralization. The presence of these substances affects the quality of the oil. It’s indeed difficult to solve this problem, but there are methods available; however, cost and other factors pose constraints
What is your filter level? Our factory also specializes in the refinement of white clay, though on a much larger scale than yours. Let’s see if our experience can be of help to you
I wonder if the original poster’s problem has been solved? Do you have any good insights? Could you share them?
Do you have any good methods for acid-base purification?
“Is pickling still the mainstream method for lubricant production in China today? ? That’s a fresh perspective! May I ask: How can the problem of the three wastes be solved?
The main issue is that the precipitation does not occur properly after pickling. For grade 100, when precipitation is adequate, the color and brightness are excellent; however, if the temperature exceeds 75 degrees, it affects the color, unless hydrogenated oil is used. There are many methods to ensure thorough precipitation