Coking coal, cleaning

Coking coal is cleaned so that the coke ash content is not over 10%. An upper limit of 1—2 wt % sulfur is recommended for blast furnace coke. A high sulfur content causes steel (qv) to be brittle and difficult to roU. Some coal seams have coking properties suitable for metallurgical coke, but the high sulfur prevents that appHcation. Small amounts of phosphoms also make steel brittle, thus low phosphoms coals are needed for coke production, especially if the iron (qv) ore contains phosphoms. 

Rein-kohle,/. pure coal, clean(ed) coal solid carbon, -koks, m. pure coke, clean coke. >kultur, kultivierung, /. Bact.) pure culture, pure cultivation. 

Polynuclear aromatic hydrocarbons (from coke, coal tar. Steelmaking, rooting, chimney cleaning Skin, scrotum, bronchus... 

The passing of the Clean Air Act in the United Kingdom in 1956 resulted in a revival of interest in low temperature carbonization to produce a very reactive coke suitable for open fires. In the CoaUte process, the coal is heated at 600—650°C for 4 h in small retorts each hoi ding 6—7 metric tons (5). The Rexco process employed large internally heated retorts in which charges of 34 metric tons were heated to 700—750°C for 6 h, but is no longer in operation in the United Kingdom (6). 

Phenol was originally recovered during the coking of coal, essentially being a by-product. Eventually, commercial routes were developed based on benzene (from coal or petroleum) for example, sulfonation of benzene to ben-zenesulfonic acid followed by reaction with water to phenol plus regenerated sulfuric acid. Phenol is used to make plastics (phenol-formaldehyde and epoxy resins) and textile fibers (nylon). Phenol is also used in solution as a general disinfectant for cleaning toilets, stables, floors, drains, etc. and is used both internally and externally as a disinfectant for animals. 

Clean Coke A process for making coke and chemicals from high-sulfur coals. Developed by the United States Steel Corporation with support from the U.S. Department of Energy. See also carbonization. 

Gasification technologies offer the potential of clean and efficient energy. The technologies enable the production of synthetic gas from low or negative-value carbon-based feedstocks such as coal, petroleum coke, high sulfur fuel oil, materials that would otherwise be disposed as waste, and biomass. The gas can be used in place of natural gas to generate electricity, or as a basic raw material to produce chemicals and liquid fuels. 

Desulfurization of fossil fuels was the subject of an authoritative review by J. B. Hyne (Alberta Sulphur Research Institute). This is a topic of increasing importance as Canada relies more and more on sulfur-containing fuels such as tar sands and heavy oils. Hyne reviewed the present state of the chemistry and technology for both precombustion desulfurization of natural gas and crude oils and postcombustion tailgas clean up of coals and cokes. He clearly identified areas of possible future research such as the high temperature-high pressure chemistry pertaining to in-situ desulfurization processes. 

In Japan, there is a project aimed at capturing the considerable volume of hydrogen gas which can be obtained as a by-product steel production. R D will focus on the purification process of fuel from coke oven gas to an acceptable level for fuel cell utilisation. METI, the Japan Research and Development Centre for Metals and Nippon Steel are working on the project with a 2003 budget allocation of 549 million. Japan also operates the 4C/.f project which aimsto develop an optimum coal gasifier for fuel cells and the establishment of gas clean-up system for purification of coal gas to the acceptable level for utilisation for MCFC and SOFC. The budget allocations for 2000-2003 total 4.6 billion. 

The enormous importance of carbon in such diverse fields as inorganic and organic chemistry and biology is well known however, only the aspects of carbon relevant to catalysis will be described here. The main topics we are concerned with are porous activated carbons, carbon black as catalyst supports and forms of coking. Carbon is also currently used as storage for natural gas and to clean up radioactive contamination. Carbon is available at low cost and a vast literature exists on its uses. Coal-derived carbon is made from biomass, wood or fossil plants and its microstructure differs from carbon made from industrial coke. Activated carbons are synthesized by thermal activation or by chemical activation to provide desirable properties like high surface area. 

A combination of coal beneficiation and relatively high-temperature roasting of the char is required for production of low-sulfur char from high-sulfur coal. When an equilibrium recycle gas composition (at about 70 psi H2) is used, char must be roasted at about 1400°F for periods of about 1 hr, as in the U.S. Steel Clean Coke process. Alternatively, the use of low-sulfur coal permits production of low-sulfur char under a wider range of hydrocarbonization conditions so that higher liquid yields, for example, may be obtained. 

---