Briefly describe the production principle of carbon black
Carbon black generally refers to simple carbon particles, generally due to insufficient combustion of organic matter, the hydrogen and oxygen elements in it are converted into water, and the carbon element is insufficiently burned, it will detach from molecules and form carbon black. Carbon black is a black powdery substance formed by incomplete combustion or pyrolysis of hydrocarbons in the gas phase. Due to different production processes, various products with different properties can be obtained through different process conditions.
carbon black production process
The raw oil is pumped into the reaction furnace from the storage tank, and the oil is preheated to above 260°C through the tube heat exchanger, and the raw oil is also preheated to above 130°C before spraying into the reaction furnace. Air and fuel are burned in the reactor, and the raw materials are sprayed into the burning flame after being atomized, and carbon black is generated by high-temperature pyrolysis. Carbon black is suspended in the exhaust gas to form smoke. The flue gas is quenched once and twice, so that the carbon black stops the reaction and is sent to the bag filter after cooling to 280°C. The collected carbon black enters the air delivery system through the air-tight valve, and the flue gas enters the pulse bag filter to make the carbon black Black and smoke separation. After the black enters the air delivery system, the hard carbon and impurities are crushed into particles smaller than 325 mesh through the micron pulverizer, and then sent to the main cyclone separator through the air delivery system, and then wet granulation or dry granulation, After the first stage elevator, the magnetic separator screens and removes the rust, and the air separator removes the carbon black and subdivides it. The qualified carbon black enters the product distribution screw, and then enters the finished product tank. After the carbon black is cooled to below 70°C, it is packaged by a packaging machine.
carbon black production process
The formation process of carbon black can be roughly divided into five stages: initial reaction, nucleation, particle aggregation, aggregate surface growth, and oxidation.
The chemical equation of typical carbon black formation: CnHm----nC+m1/2H2 The cracking reaction of most hydrocarbons is an endothermic process.
1. Initial reaction: It is the precursor and beginning of carbon black formation, including the transformation from molecular system to particle system. Nucleation: It is the process of crystal nucleus generation and crystal nucleus growth.
2. Particle aggregation: Under the action of nucleation, the collision between fine particles with a diameter of 12 is generated. Aggregate surface growth: Aggregates accumulate or adsorb on the surface of aggregates, resulting in chains of 100 to 1000 nanometers in length.
3. Oxidation: After the formation and growth of carbon black, surface functional groups are generated due to the oxidation process.
4. Aggregate surface growth: Aggregation or adsorption on the surface of the aggregate produces chains of about 100 to 1000 nanometers.
5. Oxidation After the formation and growth of carbon black, due to the oxidation process, surface functional groups are generated due to oxidation.
Uses of carbon black
According to different uses, carbon black is usually divided into carbon black for pigments, carbon black for rubber, reinforcing carbon black, insulating carbon black, spray carbon black, colored carbon black, metallurgical carbon black, conductive carbon black and special carbon black, etc. Widely used in rubber, ink, paint, paint, battery, electronic materials and other industries. Among them, rubber carbon black, pigment carbon black, and conductive carbon black are the most commonly used.
The use of rubber carbon black
In rubber products, a certain amount of carbon black can play a role of compensation and filling to improve the performance of rubber products, which is called carbon black for rubber. It accounts for about 95% of the total carbon black. In the rubber industry, in order to show the reinforcing effect of carbon black on rubber and the application parts on tires, it is also customary to divide carbon black into two categories: hard carbon black and soft carbon black. The former has a good reinforcing effect on rubber, while the latter has a poor reinforcing effect and has a filling effect to a large extent. Most of oil furnace carbon black (super wear-resistant furnace black, super wear-resistant furnace black, high wear-resistant furnace black, fine particle carbon black) belongs to hard carbon black; a small part of oil furnace Black, general carbon black, semi-reinforced furnace black), gas furnace black and warm carbon black belong to soft carbon black.
Uses of Pigment Carbon Black
Pigment carbon black color black is used as carbon black for coloring pigments in inks, paints, coatings and other products. According to the coloring strength (or blackness) and particle size, it is generally divided into four types: high pigment carbon black, medium pigment carbon black, ordinary pigment carbon black and low pigment carbon black. It is mainly produced by contact method and oil furnace method.
Uses of Conductive Carbon Black
Certain carbon blacks have low or high resistance properties and are used in different products, such as dry batteries, conductive rubber, cable materials, and electric components. Among them, acetylene carbon black is mainly used in dry batteries due to its good electrical conductivity.
Process for preparing carbon black
There are many ways to prepare carbon black, including lamp black production methods, gas black production methods, channel carbon black production methods, furnace carbon black production methods, etc. In fact, these are all carbon black production processes, so The carbon black products produced are also somewhat different, but their uses remain the same. Common carbon black production processes are divided into three categories: contact carbon black, furnace carbon black and pyrolytic carbon black.
1. Contact method carbon black: including channel method carbon black, roller method carbon black and disc method carbon black. Among them, channel carbon black is one of the older and important carbon black varieties, and it is a typical contact method carbon black.
2. Furnace carbon black: including gas furnace carbon black, oil furnace carbon black and gas-oil furnace carbon black, among which oil furnace carbon black is a kind of carbon black that has developed rapidly in the past 40 years.
3. Pyrolysis carbon black: including fine particle pyrolysis carbon black and particle pyrolysis carbon black.