Carbon blacks production processes

Since the price of both feedstocks and fuels, and thus, the profitability of the carbon black production processes, is highly dependent on the petrochemical indus-... 

The lamp black process (Figure 4.7) is the oldest commercially used carbon black production process [4.8, 4.15]. 

Mineral impurities come from quench and pelletization steps in the carbon black production process. As presented before, the decrease in temperature of carbon black and exhaust gases is mainly obtained by injection of a great mass of water. Additional water is also added to carbon black during pelletization. Even if this water is purified, the remaining mineral salts precipitate onto the carbon black surface and, because of the high temperature, are reduced to basic salts. Mineral impurities of carbon blacks can easily be extracted by solubilization in water, as in the so-called pH of carbon black, in which carbon black is suspended in water and the pH then filtered and the pH of the filtered water measured. Mineral impurities don t seem to alter carbon black reinforcement properties but they have a significant effect on vulcanization speed, which increases with the pH value of carbon black. 

Like all other operators of combustion equipment, carbon black plants are subject to the usual pressures for reduced sulfur and nitrogen oxide emissions. It appears that the use of lower sulfur feedstock is the most economic way of reducing sulfur emissions. Redesign of combustion equipment for nitrogen oxide reduction is showing some promise. The primary NOx issues arise from the combustion of tail gas since the carbon black production process is exceedingly fuel-rich. 

The first commercial oil-fumace process was put into operation in 1943 by the Phillips Petroleum Co. in Borger, Texas. The oil-fumace blacks rapidly displaced all other types used for the reinforcement of mbber and today account for practically all carbon black production. In the oil-fumace process heavy aromatic residual oils are atomized into a primary combustion flame where the excess oxygen in the primary zone bums a portion of the residual oil to maintain flame temperatures, and the remaining oil is thermally decomposed into carbon and hydrogen. Yields in this process are in the range of 35 to 50% based on the total carbon input. A broad range of product quaHties can be produced. 

The oil furnace process is the most common method of production today and is the source of over 95% of the total output of carbon black globally. In this process, a heavy aromatic fraction of petroleum distillate is atomized and sprayed into a furnace preheated to 1200-1900°C. The feedstock vaporizes and decomposes to form carbon black and combustion gases that are immediately cooled with a series of water sprays and heat exchangers to terminate the carbon black reaction and cool the carbon black product stream. The carbon black is separated from the combustion gases in bag filters and is conveyed for further densification either in pelletization processes or in agitator tanks (from which powdered, fluffy black is collected). 

Modern carbon black products are direct descendants of early lampblack , first produced in China over 3500 years ago. These early lampblacks were not very pure and differed greatly in their chemical composition from current carbon blacks. Since the mid-1970s most carbon black has been produced by the oil furnace process, which is most often referred to as furnace black. Table 4.1 contains selected information on carbon black. 

Carbon black, initially used as pigment in ink, has the longest history of all the materials discussed in this book. It was produced in China about 3000 B.C. and exported to Japan around 500 A.D. But only in the last 50 years has the technological development in both carbon black production and processing of rubber and polymers resulted in the tremendous variety of products which we know today. 

Therefore, hydrocarbon-containing materials have the potential to be used in carbon black production. Raw materials can be in the form of hydrocarbon gases, such as methane and acetylene, but mostly viscous residual aromatic hydrocarbons are used. Depending on chemical composition, the reaction is exo- or endothermic. Only when carbon black is produced from acetylene the reaction is exothermic and the process demands intensive cooling, whereas in other cases the reaction is endothermic and needs a substantial amount of energy in order to form carbon black. 

The Oil-Fumace Process is by far the most prevalent method of carbon black production. It is a further development of the Gas Furnace Process. A reactor is fed by liquid hydrocarbon feedstock which is injected, atomized, and mixed with preheated air and auxiliary fuel (usually natural gas). Part of the feedstock is used to maintain the reaction temperature (I450-1800°C) and the remainder is converted to... 

The product obtained from the vapor process is frequently termed fumed silica because it looks like smoke or fumes. This process was developed by applying carbon black production technology and equipment to silica tetrachloride in an invention by Degussa AG. Fumed silica manufactured is presently based on Degussa s license, which was sold to only a few other corporations. Metallic silicon and gaseous dry HCl are reacted to form silica tetrachloride, which is mixed with hydrogen and air and fed into the burner tube of the reactor where the following reactions occur ... 

For many decades carbon black has enjoyed a practical monopoly as a filler in the tire industry. It retains this position today, the tire industiy consumes 70% of carbon black production. A major breakthrough for non-black fillers came in the early 1970s when a winter tire containing silica in its treading compound was introduced. This resulted in numerous problems with rubber compound processing. The tire compound had different flow and molding characteristics. The development initiated friendly competition (friendly because the major producers of carbon black are also major manufacturers of precipitated silica) which continues to bring improvements to tire performance. 

The solar-thermal process is enviromnentally friendly. The most environmentally friendly option is when selling carbon black into the tire carbon black market as the energy and pollution associated with normal carbon black production are avoided. If carbon is fed to a carbon conversion fuel cell, the total green house gas emissions are still 60% of those of a steam reformer and the bulk of the released CO2 is in a pure form so it can be easily sequestered. 

Industrial processes, e.g., coke production Carbon black production Aluminum plants Asphalt production Petroleum cracking Industrial waste discharge Power plants and industrial boilers... 

In the furnace process, which today dominates carbon black production, oils rich in aromatics from naphtha or gas oil pyrolysis, cat-cracker residues (decant oils) together with mixtures of aromatics from coal tar, are used as feedstock. Table 13.5 summarizes the characteristic data for decant oil, pyrolysis oil from naphtha cracking and a carbon black feedstock derived from coal tar. 

Over 90% of carbon black production is consumed by the rubber processing industry as reinforcing black. The remaining 5 to 10% is used as pigments for paints, paper, printing inks and plastics. 

Two main production routes are used for the manufacture of carbon black, the thermal process and furnace process. The furnace process is used for the bulk (approximately 98%) of carbon black production today. 

The most widely employed industrial process for carbon black production is the furnace process. 

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