Technical carbon, its preparation

Carbon (GOST 7885-86) - a kind of industrial carbon products, used mainly in the manufacture of rubber as a filler, reinforcing its useful performance properties.In contrast to coke and pitch is almost one carbon black in appearance resembles.

Scope

Approximately 70% of carbon black used for the manufacture of tires, 20% - for the production of rubber products.Also, technical carbon is used in paint manufacturing and delivery of printing inks, where it serves as a black pigment.

Another area of ​​application - the production of plastics and cable sheaths.Here the product is added as a filler and impart special properties to products.In small amounts carbon black is used in other industries.

Feature

Carbon - a product of a process involving the latest engineering techniques and control methods.Thanks to its purity and strictly defined set of physical and chemical properties, it has nothing to do with the soot produced as contaminated byproduct from burning coal and oil, or the unregulated internal combustion engines.According to generally accepted international classification of carbon black designated Carbon Black (black carbon translated from English), carbon black in English - soot.That is, these concepts are currently no way mix.

amplification effect by filling rubber carbon black was for the development of the rubber industry are not less important than the discovery of the vulcanization of rubber with sulfur.In the rubber composition of large carbon number of ingredients by weight ranks second rubber.The effect of the qualitative properties of carbon black in the rubber much more than quality indicators of the main ingredient - rubber.

reinforcing properties

improve the physical properties of the material by introducing a filler called gain (reinforcement), and such fillers are called amplifiers (carbon black, precipitated silica).Among the truly unique characteristics of amplifiers has a technical carbon.Even before curing it communicates with the rubber, and the mixture can not be completely separated into carbon black and rubber with solvents.

rubber strength derived from the major elastomers:

The table shows the properties of the vulcanizates obtained from different types of rubber without filling, and filled with carbon black.From these data it can be seen how the carbon content greatly influences on the rubber strength index in tension.By the way, other particulate powders used in rubber mixtures to impart the desired color or a mixture of cheaper - chalk, kaolin, talc, iron oxide and others do not have reinforcing properties.

structure

Net of natural carbon - a diamond and graphite.They have crystal structure significantly different from one another.X-ray diffraction found similarities in the structure of natural graphite and artificial material carbon black.Carbon atoms in graphite form large layers of fused aromatic ring-systems, with the interatomic distance 0.142 nm.These graphite layers of fused aromatic systems is called the basal plane.The distance between the planes is strictly defined and 0,335 nm.All the layers are arranged parallel to each other.The density of graphite is 2.26 g / cm3.

Unlike graphite, which has a three-dimensional ordering, technical carbon is characterized by only two-dimensional ordering.It consists of a well-developed graphite planes arranged approximately parallel to one another, but offset relative to adjacent layers - that is, randomly oriented plane with respect to the normal.

shaped structure of graphite compared with neatly stacked deck of cards, and the structure of the carbon black with a deck of cards in which cards are shifted.It interplanar spacing larger than that of graphite and 0,350-0,365 nm.Therefore, the density lower than the density of carbon black and graphite is in the range 1,76-1,9 g / cm3, depending on the grade (usually 1.8 g / cm3).

coloring pigment (coloring) carbon blacks used in the manufacture of printing inks, coatings, plastics, fibers, paper and building materials.They are classified into:

• vysokookrashivayuschy carbon black (NA);
• sredneokrashivayuschy (MS);
• normalnookrashivayuschy (RC);
• nizkookrashivayuschy (LC).

third letter stands for a method of producing - furnace (F) or channel (C).Example of designation: HCF - vysokookrashivayuschy furnace carbon black (Hiqh Colour Furnace).

coloring power of the product related to the size of its particles.Depending on the size of their carbon Technical divided into groups:

Classification

carbon black for rubber in the degreeenhancing effect is divided into:

• Vysokousilivayuschy (tread, firm).It provided high strength and abrasion resistance.The particle size small (18-30 nm).Used in conveyor belts, tire treads.
• Poluusilivayuschy (wireframe, soft).Average particle size (40-60 nm).Apply in diverse industrial rubber products, tire carcasses.
• Nizkousilivayuschy.The particle size of a large (over 60 nm).The tire industry uses limited.It provides the necessary strength while maintaining a high elasticity of rubber products.

complete classification is given of carbon black in the standard ASTM D1765-03, adopted by all the world's manufacturers of the product and its consumers.It classification, in particular, is conducted on a range of specific surface area of ​​the particles:

Production of carbon

are three technology of industrial carbon black, which is used in the cycleincomplete combustion of hydrocarbons:

• furnace;
• channel;
• tube;
• plasma.

also a thermal method in which the high temperature decomposition of natural gas or acetylene.

Numerous brands produced by different technologies, have various characteristics.

Technology of

theoretically possible to produce carbon black of all these methods, however, more than 96% of the manufactured product a furnace method from liquid raw materials.The method allows to obtain a variety of brands of carbon black with a specific set of properties.For example, the Omsk Carbon Black Plant by this technology produces more than 20 grades of carbon black.

General technology is.Lined reactor vysokoogneupornymi materials supplied natural gas and heated to 800 ° C air.By burning natural gas to produce products of complete combustion with a temperature of 1820-1900 ° C, containing a certain amount of free oxygen.In the high-temperature products of complete combustion of the liquid hydrocarbon feedstock is injected, carefully pre-mixed and heated to 200-300 ° C.Pyrolysis of the feedstock occurs at a strictly controlled temperature, which, depending on the grade of carbon black produced has different values ​​from 1400 to 1750 ° C.

At a certain distance from the feed thermal and oxidation reaction is stopped by injecting water.The resulting pyrolysis gases and the carbon black reaction enter the air preheater, in which they give a part of its heat to the air used in the process, the temperature of the mixture is lowered uglerodogazovoy from 950-1000 ° C to 500-600 ° C.

After cooling to 260-280 ° C by the additional injection of water the mixture of carbon black and gases is directed into the baghouse, where carbon black is separated from the gas and enters the hopper of the filter.Dedicated technical carbon filter from the hopper through the pipeline gas transportation is supplied by fans (blowers) into the granulation.

manufacturers of carbon

World production of carbon black exceeds 10 million tons.Such a large demand for the product is primarily due to its unique reinforcing properties.Locomotives industries are:

• Aditya Birla Group (India) - about 15% of the market.
• Cabot Corporation (USA) - 14% of the market.
• Orion Engineered Carbons (Luxembourg) - 9%.

largest Russian producers of carbon:

• Ltd. "Omsktehuglerod" - 40% of the Russian market.Plants in Omsk, Volgograd, Mogilev.
• OAO "Yaroslavl technical carbon" - 32%.
• of "Nizhnekamsktekhuglerod" - 17%.