Bitumen expertise

Methods for obtaining petroleum bitumen

There are several ways in which bitumen is produced:

• By concentrating oil residues by vacuum distillation under the influence of water vapor or inert gas;
• With the oxidation of oil residues with oxygen at high temperatures;
• By mixing residual oil with residual products and distillate;
• In a combination of several of the above methods.

The best raw materials for manufacturing are the residues of heavy oil refining - asphalts, cracking residues, tar, etc. The best bitumen are obtained with a low content of paraffins (paraffins prevent adhesion with minerals) and with a high content of resinous-asphaltene components. At the same time, oil must be well demineralized for production.

Where are residual products used?

In the West, bitumen produced from residues is widely used. France, for example, has 85 percent of them. Such materials are distinguished by increased strength, density, ability to resist tearing, and resistance to temperature changes. Not all types of oil are used for their production, but only those that have less paraffins.

The great need of the national economy for bitumen dictates the need to produce them from heavy, highly resinous oil. By deasphalting tar, precipitated bitumen is obtained, for which special installations are used in the USA and other countries. At the same time, paraffin oils, which are of little use for the main bitumen production, are more often used for production.

In the entire territory of the former Soviet Union, there is not a single deasphalting plant that would work directly on the production of these products. The existing installations are aimed at the release of residual oil. At the same time, the quality of asphalt is not regulated and is not subject to real control.

At the same time, the use of heavy grades of oil abroad does not always provide high-quality distillation and quality. Therefore, the oxidation process increases the viscosity and temperature sensitivity. And the development of oxidation for industrial production seems to be a good help when using the secondary use of oil residues in the development of secondary refining processes.

Oxidation under pressure

Oxidation is more active with increasing pressure in the oxidation zone. At the same time, raw materials with a low amount of oils give bitumen with high elongation, and plasticity intervals, as well as penetration. With an increase in air consumption, the intensity of the process also increases and the heat resistance of the final bitumen product increases. Residual fractions are usually oxidized in the cube - this method is used abroad, in old plants and in the production of low-tonnage types of bitumen.

The use of column apparatus in continuously operating bitumen plants

Recently, bitumen hollow columns have been actively used for production. The presence of several columns makes the production more flexible, which is important given the seasonal fluctuations of bitumen. This method makes it possible to stabilize the thermal regime of oxidation by changing the temperature of the feedstock entering the columns and using compressors. An example of a high-quality and effective application of this method can be called an Austrian company with its Pörner technology. This technology is distinguished by the presence of an inner cup in the column.

Compounding method

It is used when working with a bituminous mixture. It replaces the oxidation method and is used abroad quite actively in the production of construction bitumen. Such bitumens can be obtained in different ways, in order to choose the preferred one, it is necessary to conduct special studies taking into account the characteristics of the processed raw materials, the conditions of a particular refinery. In short, the main thing can be highlighted:

• the most promising bitumen production is on column-type apparatuses;
• research on such oxidation is ongoing;
• non-oxidized bitumen have a high level of adhesion, extensibility, high aging resistance against oxidized bitumen;

In the CIS, the production of peroxidized bitumen is developed with a further compounding process with weighted tar.

Requirements for the quality of bitumen

Road bitumen is used under conditions of increased load, therefore, the requirements for their quality are increased. There is a certain list of qualities that bitumen can have for use in road conditions:

• heat resistance - these materials must withstand elevated temperatures, therefore heat resistance is one of the first requirements;
• frost resistance - even at negative temperatures, bitumen on the roads must retain the elasticity it should be;
• the ability to adhere to mineral materials - adhesion should be provided equally well with both dry and wet surfaces;
• preservation of viscosity and strength for a long time;
• good resistance to compression and shock , which are inevitable in heavy traffic on the road.

Construction bitumen differ from road bitumen, which may be less flexible, but at the same time must have no less strength and wear resistance.

General characteristics of all types of bitumen, which make them suitable for use in different sectors of the national economy:

• preservation of the original plasticity during temperature fluctuations;
• high degree of viscosity and ability to cement;
• durability and stability;
• the ability to tolerate elevated temperatures;
• an increased level of elasticity of the material, which allows bitumen to retain plasticity even under negative temperatures.

The properties of bitumen are influenced by their composition, more precisely, the ratio of resins, oils, asphaltenes in the material, as well as the absence of paraffins or their content in small quantities. All these substances are contained in the original product - oil. Thus, the quality of the final product also depends on the quality of the oil. In addition, the quality is also influenced by the crosslinking oxidation process.

What performance characteristics determine the quality of bitumen?

The quality of bitumen depends on their technical and physical and technical properties, thermal and dielectric characteristics, optical properties and their relation to water and solvents.

Among the important characteristics are indicators of the loss of mass of bitumen during heating, as well as indicators of adhesion and cohesion of bitumen. Today, the whole world needs quality bitumen that can withstand the increased loads on the roadway. Therefore, in many countries, new binders are being developed for synthetic materials that will help preserve and increase the life of the road surface.

It becomes obvious that good results of road operation can be achieved if bitumen with a wide plasticity range is used, that is, one that has less brittleness in frost and a higher temperature at which softening occurs. Road bitumen perform not only a binding role, but also a waterproofing role, binding the mineral substances of the filler. Therefore, there is the concept of "ideal bitumen", which has collected all the existing positive characteristics of bitumen. Such bitumen has:

• high adhesion to mineral filler and compatibility to it;
• a certain temperature of brittleness, softening and glass transition;
• strength and elasticity.

Recently, there has been a tendency to unify all bitumen produced in Europe under a single standard. Such a task was received by the European Organization for Standardization or the European Union. Their meaning is to bring all national standards to a single similarity of norms that will be the same for all countries that now have their own standards, but taking into account the climate and characteristics of road use in each individual country.

And although the CIS does not yet have new pan-European standards approved by Europe, it is important to know that bitumen producers who plan to supply them to the EU market will carry out tests under the conditions adopted in Europe.

Petroleum bitumen production

The increased flow of cars, the increased loads on the roadway make bitumen producers think about improving its performance characteristics. Today, instead of the declared 15-20 years, which the asphalt road should serve, in fact, it serves five to twelve years at most.

It becomes problematic to make high-quality and timely road repairs, primarily due to the lack of raw materials and materials. According to the analysis of the needs of construction organizations, it is satisfied less than half. And since in bitumen-mineral compositions for road repair, bitumen occupies 5-9 percent, not counting the filler, it becomes obvious that the quality of road repair to a large extent depends on its quality as a binder with mineral fillers. Therefore, the question of the quality of bitumen is the most important for solving the whole problem of saving resources.

And here the opinions of road builders and bitumen producers differ on the reasons for such a poor quality of the product. The first consider this a consequence of its poor adhesion to mineral materials, and the second - a violation of the rules of transportation and laying technology. At the same time, our product sold to European countries shows good results.