How Is Tarmac Made?
We’ve previously discussed where bitumen comes from. In that article, we talked about the places where bitumen can be found naturally, and about the processes which create natural bitumen. To understand how artificial bitumen is made, it’s important to understand what bitumen is.
In that previous article, we discussed how natural bitumen is normally found near petroleum. This is because bitumen is a derivative of crude oil — the liquified remnants of ancient fossils, and so it’s likely that the conditions required to create bitumen can take place in nature.
However, while these conditions do happen in nature, they are relatively uncommon compared to the conditions that create base-level crude oil. This means that compared to crude oil, bitumen is relatively rare.
But while this process is relatively uncommon, there are methods of replicating it artificially. We do this by a process known as Fractional Distillation.
What Is Fractional Distillation?
Fractional Distillation is the method wherein chemicals are distilled and separated into their base parts, allowing people to make use of those parts. The process of chemical distillation is an old one, with a history that stretches back to at least the 12th century BCE.
Modern Fractional Distillation, however, can trace its origins much later — to the 13th-century Italian doctor and alchemist Tadeo Alderotti. Alderotti, who was a contemporary (and enemy) of the poet Dante Alighieri, was one of the first physicians to apply scientific logic to the practice. However, it wasn’t Alderotti’s medical practice which led to the creation of Fractional Distillation — it was his second job as an alcohol maker. Alderotti used this process to create what he called Agua Ardiente — the liquid of life.
But while Fractional Distillation was invented to distil alcohol, today its uses are many and varied — including the creation of artificial bitumen.
How Is Artificial Bitumen Distilled From Crude Oil?
To start with, the temperature of the crude oil is increased to roughly 200 degrees centigrade as it passes from a storage tank to a chemical furnace. Once there, the material is heated again until it reaches a temperature of 300 degrees.
At this temperature, the crude oil is vaporized, and the gaseous remnants are allowed to pass into a distillation column. Here, the components are separated into lighter and heavier components. The lighter parts of the crude oil rise to the top while the heavier elements stay near the bottom as a residue.
This heavy residue is then further distilled in a Vacuum Distillation Column, where it becomes usable bitumen. This material is known as Straight Run Bitumen. The grade of the bitumen created is dependent on how much volatile material is left in the bitumen following distillation — more volatile bitumen being less pure. Thus bitumen is normally further distilled until it reaches a level of useable purity.
This situation has led to a situation where most commercially available bitumen was distilled from crude oil. While this has led to an increase in the overall amount of bituchem, it has occasionally led to issues. For example, in 2022, there was a shortage of bitumen, as a result of international politics and material shortages.
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For more information about BituChem and our range of bitumen emulsions, please contact us today. Our high-quality highway bituminous products are suitable for road surfacing and highway maintenance.