Natural bitumen (mineral bitumen) is bitumen that is found in ready form and freely and with many impurities in nature.
The cause of mineral bitumens is speculated that in ancient times some crude oil reservoirs were on the ground or near the surface, and in many years due to sunlight, its light oils were emitted and bitumen, which is the heaviest element of crude oil. Remains in the mine and is now in use.
Bitumen is formed from the evaporation of crude oil oils over a long period of time. The oldest bitumen mines to be exploited were in the Jordan River Valley and around the Dead Sea and Mosul. Most of the mineral bitumen consumed in the Americas and Western Europe came from the Trinidad and Bermuda Is achieved.
Many mineral bitumens are found in Iran:
Such as Behbahan-Kermanshah bitumen mines (Gilsonite Maad mine) and also in front of and behind Lorestan mountain, etc., but due to the fact that bitumen is abundant in Iran and is cheaper and its characteristics can be controlled, less attention is paid to mineral bitumens. Has been.
Natural bitumen is also similar to bitumen produced from crude oil and refers to natural, non-crystalline hydrocarbons and black or dark brown viscose. Natural bitumen is often called asphalt (pure bitumen).
The origin of bitumen is from crude oil, which is formed after the gradual migration of crude oil to the surface layers and the gradual evaporation of light materials under the influence of three factors of time, heat and pressure and processes such as oxidation, sulfurization, polymerization and condensation. .
General specifications of bitumen:
Bitumen, depending on the location of the mine, have their own impurities, including mineral objects and so on.
For example, Trinidad’s bitumen contains 4% sulfur and other ores contain about 1% ash.
If so, the refining bitumens are free of ash and other foreign matter. Therefore, mineral bitumen must be refined before consumption.
In some natural bitumen mines, in addition to bituminous minerals, bitumens contain other mixtures such as organic matter, especially plant roots:
Such as Trinidad bitumen, which contains 40% minerals and 5% organic matter, or Bermuda bitumen, which contains about 5% by weight of minerals.
Regarding the difference between natural bitumen and petroleum bitumen, it should be said that petroleum bitumen or refined bitumen is in fact oil residue that has a liquid state.
Of course, there is also a very hard part, which is called oil coke or oil coal. From the part that is in the form of a very concentrated liquid, called vacuum baton, two products are produced.
If the oil is paraffin, due to the presence of high paraffin and low adhesion, bitumen is not made from it and it is directly converted to fuel oil (furnace oil).
But if the percentage of paraffin is low – for example below five percent – they either mix it with lighter products such as kerosene or diesel or some kind of refinery waste, which does not meet the diesel standard, and produce and sell fuel oil. Or if the same vacuum baton is blown a little, it turns into bitumen with very small compounds, which is known as industrial bitumen or petroleum bitumen, and this bitumen is usually converted into different grades. And it is mainly used for asphalt 70-60 or 100-85 or 100-80 which has pen grades (concentration).
But bitumen has almost the same characteristics in mines and the amount of gray mixed with it improves its quality. For example, the ash of some bitumens is less than five percent, which is one of the best natural bitumens and reaches below ten, fifteen, twenty, thirty and even below fifty percent, respectively, that the more ash mixed with it, the lower the quality of bitumen.
More important is the separation, which is a difficult step and usually lowers the quality and price of the bitumen.
The main difference between natural bitumen and petroleum bitumen is as follows:
A. Petroleum bitumen has less than 1% sulfur, mineral bitumen has more sulfur. Trinidad bitumen has 3.8%, California bitumen 3.9% and Mexican bitumen 3.2% sulfur.
B- Petroleum bitumen is pure, mineral bitumen has mineral bodies and up to 1% ash.
C- Petroleum bitumen oil is more than mineral bitumen, water petroleum bitumen oil, up to 70% of their weight reaches the purchase of bitumen
D- The number of acidification and saponification of petroleum bitumen is less than mineral bitumen.
Not much information is available on how bitumen is formed; Because the process of its formation takes a very long time.
Mineral bitumen is a substance similar to black or brown oil that contains a varying degree of concentration from a viscous liquid to a solid glass. The results of bitumen analysis show that this substance is obtained from oil distillation residues or natural sediments.
Bitumen is formed from compounds of hydrogen and carbon with small proportions of nitrogen, sulfur and oxygen. This material is formed during the early stages of decomposition of marine organic reserves into oil and contains minerals.
Such a process may eventually lead to the formation of bitumen, which is a type of solid bitumen that is supplied to us through oil resources.
The difference between mineral and non-petroleum bitumen is that mineral bitumen is mainly used as a modifier for refinery bitumens used in asphalt and isogum.
Therefore, it is expected that the purchase and sale of bitumen will take place mainly in the road transport and housing sectors.
Contrary to popular belief, bitumen production is done only in refineries. In some parts of the world, there are natural bitumen mines that were formed about 360 million years ago. During the Carboniferous period, when the earth’s surface was full of swamps and ponds, many living organisms lived inside the swamps, which after death for many years, with the accumulation of sediment on the remains of these organisms, created the conditions for the formation of fossil fuels. Conditions such as high pressure, lack of oxygen and high temperature that over time cause the fermentation and chemical change of organic molecules. Under these conditions, especially at temperatures above 50 ° C, organic matter in the sediments is converted to kerogen, oil or bitumen.
Currently, most of the world’s bitumen reservoirs are located in Canada, Venezuela and Oman. This type of bitumen, like crude oil, needs to be extracted and processed. In cases where bitumen is shallow, for example in Canada, mining equipment is used to extract the bitumen.
Finally, it should be noted that bitumen extraction is more expensive than refinery oil. In addition, natural bitumens contain up to 5% sulfur, heavy metals and other impurities, which also include processing costs.
Types of bitumen:
Bitumen is usually found in the shallow layers of the earth and in some cases protrudes from the earth’s crust. Surface crude oils evaporate over time and then take the form of bitumen due to weathering.
This substance is divided into several categories based on its physical properties and chemical composition:
Asphaltic Pyrobitumen thermal bitumen
Non-asphalt thermal bitumen of a bitumen (Non-Asphaltic Pyrobitumen)
Natural bitumen applications:
In today’s industrialized world, bitumen is widely used. Generally, when using bitumen, the required quality is checked. This control is performed by laboratory methods based on the application and performance of the product.
Adhesive quality and moisture penetration along with cheap price, uses bitumen as the main materials to protect the roofs.
One of the main uses of natural bitumen is its use in making bitumen asphalts.
Insulators, adhesives, acoustic coatings, paints, floor coverings, multilayer fiber panels and various types of mastics. In most cases, their properties can be improved by adding minerals to the bitumen.
Applications of bitumen:
1- Civil works: roads, airports, sports fields, building foundations, building insulation and…
2 – Hydraulic fields: canals, bridges, water tanks, dams and…
3- Industrial uses: protective coating of metals, painting, sealing, battery making, tire making, shoe making, underground gas pipe coating and… sale of bitumen
4- Agriculture: Preservation of moisture, early maturity of the plant, prevention of tuberculosis and creation of artificial forests, erosion of soil and quicksand and….
5 – Electrical: Asphalt strips, filling of electrical connections, covering wires, insulation and…
Properties of bitumen:
The nitrogen content of natural bitumen significantly increases its resistance to temperature and oxidation, and therefore, this material is very suitable for use in asphalt paving.
Analysis of bitumen has shown that its use in isogum reduces the percentage of moisture penetration to zero and retains more heat inside the building.
Natural bitumen, on the other hand, has no wax. Wax impairs the quality of asphalt and reduces its resistance to abrasion.
Road construction companies also use bitumen in asphalt for this purpose; Because its strength increases the useful life of asphalt up to five times.
Shipping and storage:
Loading, transporting and loading of natural bitumen must be done carefully. Different types of bitumen must be classified and stored separately.
Testing of samples taken from different types of bitumen must comply with the required properties in the specifications.
Bitumens should be kept in a clean place and covered as much as possible to prevent contamination with soil, harmful substances, water, ice and snow.
Closed warehouses need to be continuously ventilated to prevent the accumulation of flammable gases in them.
These warehouses must be away from fire and flammable materials and the necessary measures must be taken to declare and extinguish possible fires.