Electrodes calcined coke used

Petroleum coke is an excellent fuel, and that is its main use, especially for the coke from fluid coking". There are some other markets that have to do with calcined coke electrodes for aluminum production or for all other electrolytic cells, carbons for electro-mechanical equipment, graphite, and pigments. 

By using two commercial plants conventionally, the trial production of two-stage calcined coke has been carried out and calcined coke samples have been distributed to the graphite electrode manufacturing companies for their evaluation. 

T he carbon electrodes used in the production of aluminum by the Hall-Heroult process normally are produced from a combination of calcined coke and a pitch binder. While coal tar pitch traditionally has been used as the binder in electrode fabrication, variations in methods of production and the diversity of sources of supply result in variations in pitch quality. In addition, some locations in North America import pitch from areas such as Europe and Japan. With the desire for a more consistent quality product and more accessible sources of supply, alternative methods of producing binder pitch have been sought. This has led to a number of studies in the production of binder pitch from petroleum-derived materials (1-5). In these developments, the preferred feedstock... 

Coke consists mainly of carbon (90-95%) and has a low mineral matter content (determined as ash residue). Coke is used as a feedstock in coke ovens for the steel industry, for heating purposes, for electrode manufacture, and for production of chemicals. The two most important categories are green coke and calcinated coke. This latter category also includes catalyst coke deposited on the catalyst during refining processes this coke is not recoverable and is usually burned as refinery fuel. 

Calcined cokes are used, depending on their quality, to produce shaped graphite products (e.g. electrodes), anodes for aluminum electrolysis or as reduction agents (e.g. in titanium production). 

Petroleum coke (also known as pet coke) is a carbonaceous solid derived from the cracking processes of oil refineries and has been a source of relatively cheap pulverized fuel for the kiln industry. It is called green coke until it is thermally treated into crystalline or calcined pet coke used in the manufacture of electrodes for steel and aluminum extraction. Green coke comes from several sources, all from the petroleum refinery industry. Table 6.2 gives some green coke analyzed by Polak (1971) showing their sources and their elemental analyses. 

A specialized application of petroleum coke is the production of electrodes for the steel industry. For this application, it is necessary to use needle coke because its low coefficient of thermal expansion and low resistivity. The needle coke must have low sulfur and low metals content. After production in a delayed coker, needle coke is crushed and calcined in preparation for electrode production. 

These microcracks may have some effect in terms of mechanical strength when these cokes are processed into artificial graphite electrodes. However, no significant difference in strength between graphitized test pieces obtained from actual electrodes under the new and traditional method was found. An optimum commercial new process system has been studied by using a model calciner pilot plant. 

Industrial carbon materials are used for molds, structural forms, electrodes of all kinds to be used in current production, metal deposition, and chemicals manufacturing [92]. Their fabrication involves a number of specific operations and processes. For instance, carbon blacks are deposited, collected, and processed. Cokes must be crushed and calcined binders (pitches) must be pulverized and classified. Green mixtures are formed, molded, extruded, baked, and some carbons are also graphitized to provide special properties. 

Petroleum coke is used principally as a fuel or, after calcining, for carbon electrodes. The feedstock from which the coke is produced controls the coke properties, especially sulfur, nitrogen, and metal content. A concentration effect tends to deposit the majority of the sulfur, nitrogen, and metals in the coke. Cokes exceeding about 2.5% sulfur content and 200 ppm vanadium are mainly used, environmental regulations permitting, for fuel or fuel additives. The properties of coke for non-fuel use include a low sulfur, metal, and ash content as well as a definable physical structure. 

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