Wax manufacturing, particularly for paraffin wax (a common type), involves a process of oil removal (de-oiling or de-waxing) from a substance called slack wax through crystallization. Here's a breakdown:
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Source Material: Slack Wax. Slack wax is a byproduct of lubricating oil production from petroleum.
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Heating and Solvent Mixing: The slack wax is heated and then mixed with one or more solvents. Commonly used solvents include ketones (like methyl ethyl ketone or MEK) or other suitable organic solvents.
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Crystallization: The mixture is gradually cooled. As the temperature decreases, the wax begins to crystallize out of the solution. This is because the solubility of wax in the solvent decreases at lower temperatures.
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Separation: The crystallized wax is then separated from the oil and solvent mixture. This is typically done through filtration using equipment like rotary drum filters or filter presses. The process separates the solid wax crystals from the liquid oil and solvent.
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Solvent Recovery: The solvent used in the process is recovered and recycled to minimize waste and cost. This is typically achieved through distillation or evaporation. The recovered solvent is then reused in subsequent batches.
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Wax Refining (Optional): The separated wax may undergo further refining processes to improve its color, odor, and stability. These refining steps can include hydrotreating (treating with hydrogen) or clay treatment.
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Finishing: The refined wax is then processed into various forms, such as slabs, flakes, or pellets, depending on the intended application.
Therefore, the core principle of paraffin wax manufacturing is to selectively crystallize the wax from a mixture containing oil and solvent, then separate the crystals to yield a purified wax product. Different types of wax may have variations in the specific solvents, temperatures, and refining steps used, but the fundamental process remains the same.
