The production process of oxidized bitumen
In this article, we explain the blowing process and the production of oxidized bitumen, its applications, uses and benefits.
First, let’s look through the production procedure of blown bitumen types.
Aeration which is the main section of the making oxidized bitumen can be both in stages or continuously.
In the continuous method in refineries, there are two traditional methods and turbo oxidizer.
In fact, the traditional method requires precise control
and operation, while the turbo control method is more advance.
Additionally, the air injection and diffusion system are not ideal in the traditional way, although the specialists can install a stirrer inside the aeration tower.
However, the air does not evenly distribute and some areas may become very hard.
Because the reaction is exothermic, water and steam are essential to control the temperature.
On the other hand, we have a turbo oxidizer that also has the same story, but its difference is the available hardware which allows for more control.
In this system, air enters through a pipe and efficiently distributes and disperses with the help of turbines in several stages.
Therefore, the maximum amount of reaction will appear so that a small amount of oxygen goes into some exhaust gases.
By optimizing the reaction intensity, the operating temperature also minimizes and as a result, all bitumen and not part of it become oxidized. Since compression reactions and carbonyl formation are desirable at lower temperatures, increasing the viscosity also optimizes. The fracture point of the road and industrial blown bitumen with this method is lower compared to the industrial method because polar aromatics with lower molecular mass will have better distribution.
It’s good to know that the aeration parameters that can lead to the formation of bitumen with the relationship between the soft point and the degree of penetration are:
- Chemical composition of feed;
- Tower temperature;
- stay time;
- Air to feed ratio; and
- Reaction efficiency.
Note that the feed to make road bitumen is different from the feed of industrial bitumen because:
- It has a lower viscosity;
- It blows with less air distribution channels;
- I t has more aromatics so that the asphaltene disperses well;
- Aeration has a shorter time;
- The amount of air is less; and
- Aeration needs a lower temperature.
Applications of oxidized bitumen
The characteristics of the final product are highly dependent on the feed. For example, with the construction of road bitumen, it is not possible to reach industrial bitumen grades by aeration. As you may know, the efficiency and application of blown or oxidized bitumen vary in different grades. The grades are 115/15 90/15 95/25 85/25 75/25 90/40 and 150/5.
These types of oxidized bitumen are suitable for production and consumption in isolation due to high temperatures.
For example, this type of bitumen mixes with gasoline and sprays on concrete that has both penetrations and dries quickly and in the next step can be ready for the application. It is very effective for the production of asphalt in places such as China where has a high temperature and makes it more durable in the summer with the braking of trucks and heavy vehicles. As a matter of fact, one of the main uses is in covering pipes and producing paint. These items are widely applicable in the production of isogum and bathroom floor coverings and insulation.
What are the specifications of 25/75 modified oxidized bitumen?
25/75 modified oxidized bitumen is a bitumen product from a special non-oxidation process, which is by modifying the VB at a temperature of 230 ° C and has a high penetration index. This product is highly apropos for industry. Besides, it is solid at ambient temperature and has more adhesion and waterproof properties than ordinary oxidized bitumen.
Effects of temperature rise on bitumen
If bitumen stays at high temperatures, its properties can become weak. In other words, if bitumen overheats or exposes to oxygen when the temperature is high, this can harm the properties of this material. Another point of the properties of bitumen that can change in poor storage conditions is the degree of hardness or consistency of the bitumen.
Effects of excessive increase in storage temperature and bitumen transport
One of the most important risks associated with the production, transportation and storage of bitumen is excessive temperature rise.
That is why to reduce the risk of overheating of bitumen, storage tanks are essential with precision
sensors to control the temperature of bitumen. Sometimes explosions may occur in bitumen transport
or storage tanks due to excessive temperature rise.
To be more specific, there are two possible reasons for this. First, the H2S gas inside the bitumen reacts with iron oxide in the floor or wall of the tank. Second, if the amount of oxygen inside the tank suddenly increases, the coke in the walls and bottom of the tank will catch fire.
Another effect of rising temperatures
is the release of toxic gases. As you know, bitumen is a mixture of different hydrocarbons with different boiling points.
Usually at 150 ° C, the first vapors release from the bitumen and for every
10 to 12 ° C increase in temperature, the amount of these vapors doubles.
Consequently, vapors from the rise of bitumen heat contain light hydrocarbons and small amounts of H2S.
Since H2S vapors are lethal even in small amounts, care must be taken not to accumulate
them in the bitumen storage tank due to rising temperatures.