the strong growing of the iron and steel industry in the following centuries, coal coke as reducing agent in blast furnaces became – in terms of quantity – the most important form of technical carbon, but with inclusion of the ash‐forming inorganic parts of the crude coking coal. The history of coking techniques for coal has been published by some other handbooks [6]. Worldwide, in modern coking plants, more than 650 × 106 t blast furnace cokes are produced annually for iron smelting with more than ×106 t high‐temperature coal tar per year as by‐product (see Chapter 6.1.5). Therefore the coking of coal for the manufacturing of iron and steel is also an important process to maintain suitable forms of industrial carbon.
3.5 History of Carbon Black
As already mentioned in above, carbon black can be denoted as oldest form of man‐made carbon [7]. Cave paintings with carbon black as color pigment have been dated as far back as 20 000 years ago. The cave artists probably scraped it from the walls and ceiling of the caves under which Stone Age man lighted wood fires. Later on man learned a direct way of making carbon black by incomplete burning of oil. A Chinese wood engraving dating from around 2630 BC shows how lampblack used to be made from sesame oil: a vessel filled with water to cool it was held over a burning oil lamp, and the carbon black deposited on the outer wall of the vessel was scraped off by hand (Figure 3.2).
Figure 3.2 Manufacture of lampblack in China (wood engraving 2630 BC).
As early as 3500 BC, at Attrituwarum in India, the Hindu scholar Panningrishee discovered a way to make writing paper from palm pulp and used a pen, oil, and lampblack (“Indian ink”) to write on it. In China, lampblack was mixed with water and bone glue and added turtle urine to this ink mixture. In solid form, this Chinese ink (developed by Tientschen around 2600 BC) became a valuable trading for those peoples able to write such as the Egyptians who had already mastered the art of making paper from the papyrus plants, growing in the Nile marshes in northern Egypt. The papyrus sheets were glued together and rolled up into scrolls. Egyptian scribes wrote onto the scrolls with black viscous ink consisting usually of a mixture of lampblack powder and water with gum arabic as binder. Papyrus scrolls with ink writing have survived several thousands of years and are still preserved today; many, however, were destroyed in the fire of Alexandria in the year 47 BC. Prior to this disaster, the entire store of knowledge of the antiquity was recorded in black ink on around 700 000 papyrus scrolls. Thus, the discovery of Indian ink for writing on paper represented a major technical and cultural progress compared with cuneiform writing on wood and stone.
Since the invention of letterpress printing by Johannes Gutenberg (1400–1468) in Mainz, printer’s ink became the most important application of carbon black, and many “huts” were built in Europe to produce the black pigment by incomplete burning of pine wood (esp. in the Black Forest), turpentine, and wood tar. Later, also whale oil and gas flame coal were used as raw materials, the latter one especially in the Saarland and Lorraine coal region in combination with low‐temperature carbonization of that special coal to coke. In modified form, the lampblack process of the antiquity is still employed today on a small scale as the flame black process especially in Germany [8]. Aromatic oils, e.g. from coal tar, are fed continuously into flat steel vessels, measuring up to 1.5 m in diameter, in which they undergo incomplete combustion with air. The carbon black formed is separated from the exhaust gas. A single unit can produce around 100 kg of carbon black per hour.
In 1822, the American brothers Samuel and Godfrey Cabot invented the channel or gas black process by thermal fission of natural gas into hydrogen and carbon. The yield was only 3–6% of theory, but natural gas was extremely cheap in America. In the course of the nineteenth century, this method became the most important process for the industrial production of carbon black. A major boost came at the beginning of the twentieth century following the discovery of the useful reinforcing properties of this type of gas black for vulcanized rubber and especially for the blends of rubber used to make car tires. With the addition of “activated” gas black produced by the American Cabot Corporation, the mileage of a car tire could be improved 10‐ to 20‐fold compared with tires without this additive. In contrast, the old flame black produced in German carbon black “huts” only effected a slight reinforcement in vulcanized tire rubber. This prompted considerable efforts in Germany to develop the production of “activated” carbon black for car tires based on indigenous raw materials. At that time, only an insignificant quantity of natural gas was available in Germany, which made it too expensive. Badische anilin und soda fabrik (BASF) and other firms therefore developed “thermal carbon black” on the basis of coal‐based acetylene. Despite the higher yield, this process was also too expensive, especially as the price of a high‐grade American gas black was only 50 pfennig per kilo, including the cost of freight to Germany [9].
The breakthrough was achieved by the Degussa inventor Harry Kloepfer (1897–1973) in the years 1933–1935 with his technical development of the German gas black process on the basis of coal‐tar aromatics, initially naphthalene, and later on the tar oils as also used for the production of flame black [9]. The quality of the new types of carbon black was rated as very good by the leading German tire manufacturer Continental in Hanover. In December 1934, the first pilot plant was started up in Gutleutstrasse in Frankfurt am Main, and already in May 1935, a large‐scale plant with 56 individual units went into production at the Kalscheuren Works of Degussa near Cologne [8]. With the addition of coke‐oven gas as fuel, the carbon black yield could be increased to 65 wt%, relative to the tar oil used. In addition to that at Kalscheuren, plants based on this process were built at the Deutsche Gasrusswerke in Dortmund and at Gleiwitz in Upper Silesia, and during the Second World War, they reached a maximum production of around 50 000 t per year. Gas blacks by this process were produced until 1976 for the tire industry; today they are supplied as worthwhile pigments for printing inks and paints.
In the meantime, the “furnace black process” developed in the United States in the 1920s was on the advance. This process is also based on aromatic oils from coal tar and petrochemical sources as raw materials. They are sprayed into a drum reactor, which is kept at temperatures of around 1500 °C by a direct gas heating, and pyrolyzed. With quenching and filtering of the pyrolysis gas, depending on the quality of the raw material oil and the required quality of the carbon black, 40–70 wt% carbon black can be obtained, relative to the oil used. A single reactor could produce around 30 000 t per year. Today, over 95% of all carbon black worldwide (more than 10 × 106 t per year) is produced according to this process.
3.6 History of Activated Carbon
Porous charcoals from wood and other biomaterials (plants, blood, bones) have been used since ancient times as medicine against stomach and intestinal troubles [10]. In the nineteenth century, an additional usage became decolorizing charcoals for crude sugar solutions. The first industrially activated carbons were Eponit decolorizing carbons, produced since 1909 by the “Chemische Werke Ratibor” according to patents of R. von Ostrejko by heating wood charcoal with steam and carbon dioxide in a special furnace [11]. In 1911, the Dutch company Norit N.V. started commercial activation of peat by using steam. In addition to this gas activation, “chemical activation” of charcoals from several carbon‐containing raw materials such as sawdust, coconut shells, peat, lignite, and bituminous coal by zinc chloride solution or acids are applied in European countries and the United States since the twentieth century to produce adsorbing carbons for gas masks, gas and water purification, solvent recovery, and many other purposes (e.g. molecular sieving of gas mixtures). The production rate grew to more than 1 × 106 t per year.
3.7
