Several common production processes of carbon black

Production of carbon black Pigment carbon black is a petroleum product and bituminous coal tar product. It cannot be produced under conditions of sub-atmospheric pressure and insufficient air, but is formed by incomplete combustion or pyrolysis of hydrocarbons at high temperatures.

1) Lamp black production process: The earliest carbon black production method in history is the lamp black production process. In this process, the raw materials are burned on a flat burning iron plate with a diameter of up to 1.5m. The combustion gas containing carbon black is The exhaust hood covered with bricks collects, and then passes through the elbow (folded 1/4) and the fire pipe to reach the deposition device. In order to control the characteristics of the carbon black produced, it should be ensured that the raw materials are mainly incompletely burned near the gap between the combustion plate and the exhaust hood. But in the pipe slightly into the pipeline, the combustion will be thermally decomposed under the lack of oxygen, thus forming larger carbon black particles. For these reasons, the composition has a wide range of particle size distribution, and the main feature is coarse particles. Since only a small part of the particles formed between the combustion disk and the exhaust hood can contact the oxygen in the air, these carbon blacks have only a small amount of surface oxides, the corresponding PH value is neutral, and the volatile content is very small.

2) The production process of gas black: The name of gas black is derived from its production process: the raw material hydrocarbon is firstly gasified when heated, and then the spontaneous combustion gas (for energy) is used as a carrier to be carried into the burner. The carbon black is in these bats. A large number of fan-shaped flames emitted by the shaped burner. Since each flame is small and burns in the air, the formation of carbon black is very different from the production process of lamp black (incomplete combustion). Here, the carbon black particles are very fine. According to different types, the average particle size is between 10~30nm, and the average particle size of gas black is 13nm. On the burning flame, there is a slowly rotating water-filled drum. Carbon black is deposited on the drum. When it is scraped, the carbon black is scraped away. When the temperature is still high, the newly formed carbon black comes into contact with oxygen in the air. As a result, partial oxidation occurs and a large number of acidic groups are formed, and the corresponding gas black PH value is in the acidic range. And about 6% of volatile matter can be obtained, which represents its surface oxide content.

3) Channel black production process: This production process uses natural gas as the raw material. The channel black process is similar to the gas combustion process of the gas black production process. Natural gas burns and emits many fan-shaped flames. The resulting product is similar to gas black but different Here, a flat water-cooled U-shaped groove is used as the deposition groove for carbon black. Due to ecological and economic reasons, the use of this method was discontinued many years ago. The production of gas black will not affect the ecological environment, and the gas black process is still in use.

4) Furnace black production process: Gas black is produced in an open atmosphere, but the furnace black production process is carried out in a closed furnace under oxygen-deficient conditions. Instead of many small fires, a large flame is used. Oil is used as the raw material and combustible gas is added to make it reach the required temperature in the furnace. By changing the furnace black production process conditions, the required pigment black can be obtained. For example, under different conditions, carbon black can reach a wide range of average particle size, from 80nm to as small as 15nmj, and even as small as gas black. But for the same particle size, there is still a difference between gas black and furnace black, mainly due to the difference in surface chemistry. Furnace black products are relatively rough, with an average particle size of 40nm. In addition, when the furnace black production process is used, a small amount of basic compounds or other additives can be added to change the degree and type of aggregates, thereby obtaining high-structure or low-structure carbon black.