Manufacturing

Different crude oils will form different types of paraffin wax during distillation, depending on boiling range. The final de-waxing of most lubricating oils is done by its dilution with solvent. It is then cooled down to approximately -30°C, forming a crystallized paraffin wax, which is then removed in large drum-filters.

The remaining paraffin-containing residue has a high oil content and is now the raw paraffin wax (gatsch or slack wax), the wax refineries’ basic product.

The paraffin wax producer now separates the different slack wax fractions that have not been extracted from the low boiling ingredients (up to approx. 400°C), but from the high boiling ones (from 350-550°C).

After de-waxing of these fractions, the remaining slack wax now forms the basic material. This now ranges from light spindle oil to machine oil slack wax to cylinder oil slack wax to the residue called petroleum. The raw slack wax still has a relative high oil content of approx. 3-20% which is more or less useless for consumers, since it should generally lie at a level of 0.5-1.5%. To extract oil from this kind of slack wax, two methods are mostly used:

 

The sweating process and
The solvent oil extraction

 

The sweating process

It has been observed that when raw paraffin wax was placed in a container with a filter and was slowly heated up, oil would extract from the substance.

By slowly heating further, the very low-melting paraffin waxes are separated and the residue, which depends on the sweating process, contains a relatively high-melting low-oil content paraffin fraction.

By using this old-fashioned technology, it was only possible to work up a slack wax that contained insufficient oil binding properties. This method was used for many years. However, today this method is seldom used.

 

The solvent extraction process

Using the solvent oil extraction process there are different procedures resulting in oil-extracted paraffin.

Here we shall only mention one method that is primarily used. By using this procedure, almost all slack waxes can be processed.

The liquid slack wax is sprayed from the top of a spray-tower and falls down as a fine powder with a diameter of approx. 0.1- 1 mm. The cooling is done by a counterstream of atmospheric air. The powder is then mixed with a cold solvent (Dichlorethan) in a mixing vessel.

As this process is done cold, the paraffin wax particles are kept intact and only the oil is extracted due to the difference in specific gravity of the paraffin (0.78) and the solvent (1.26).

The mix of paraffin and solvent is then placed in large centrifuges where the main part of the solvents is extracted. After a further reheating, the remaining solvents are removed. What is now left over is paraffin with a low oil content.

The result of this method is an almost oil free paraffin or micro wax that now can be additionally processed to meet special requirements. Hereafter the paraffin is filtered with bleaching earth or refined with a concentrated sulphuric acid, after which it is neutralized and treated with bleaching earth and/or is hydro-finished.

By doing this, the coloured components are separated from the paraffin wax. Along with the refining residue, components such as compounds of aromatic rings or chains with reacting carbon atoms are extracted. The result is a refined product with great stability towards light and heat. The resistance against oxidation can be further improved by adding stabilizers.

The refined product can additionally be processed to be odourless. This desodorizing usually happens in vacuum by using steam.

One now has paraffin wax that can be transported as liquid in bulk or in drums if the paraffin is too soft and to produce slabs. By additional processing, slabs, pastilles and powder can be produced.

 

From raw slack wax to fully refined paraffin