Extractive Coking Process

The overhead product is fractionated to yield recycle solvent (which is hydrotreated prior to use in the process) and a variety of other products (1) gases (2) light oil (C4 230 C [C4 445°F]) and (3) middle distillates (230°C-400°C [445°F-750°F]). 

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For most chemical reactions, a catalyst is required to obtain the desired product. The catalyst performance in MRs can be influenced positively or negatively by the use of a membrane. It is well known that the withdrawal of hydrogen during dehydrogenation in an MR will likely favor coking processes, promoting deactivation of the catalyst. This implies that MRs require catalysts with improved stability. However, in the Fischer-Tropsch synthesis, the use of membranes to extract water from the reaction zone may protect the catalyst from... 

Feedstocks for this very flexible process are usually vacuum distillates, deasphalted oils, residues (hydrotreated or not), as well as by-products from other processes such as extracts, paraffinic slack waxes, distillates from visbreaking and coking, residues from hydrocracking, converted in mixtures with the main feedstock. 

The process of extraction requires first smelting (to obtain the crude metal) and then refining. In smelting, iron ore (usually an oxide) is mixed with coke and limestone and heated, and hot air (often enriched with oxygen) is blown in from beneath (in a blast furnace). At the lower, hotter part of the furnace, carbon monoxide is produced and this is the essential reducing agent. The reduction reactions occurring may be represented for simplicity as ... 

The Phenox process (254) removes phenol (qv) from the efduent from catalytic cracking in the petroleum industry. Extraction of phenols from ammoniacal coke-oven Hquor may show a small profit. Acetic acid can be recovered by extraction from dilute waste streams (255). Oils are recovered by extraction from oily wastewater from petroleum and petrochemical operations. Solvent extraction is employed commercially for the removal of valuable... 

The Iron Bla.stFurna.ee, The reduction of iron oxides by carbon in the iron (qv) blast furnace is the most important of all extractive processes, and the cornerstone of all industrial economies. Better understanding of the reactions taking place within the furnace has made possible a more efficient operation through better preparation of the burden, higher blast temperature, and sometimes increased pressure. Furnace capacity has doubled since the 1800s, whereas coke consumption has been reduced by about half The ratio of coke to iron produced on a per weight basis is ca 0.5 to 1. 

In the case of low temperature tar, the aqueous Hquor that accompanies the cmde tar contains between 1 and 1.5% by weight of soluble tar acids, eg, phenol, cresols, and dihydroxybenzenes. Both for the sake of economics and effluent purification, it is necessary to recover these, usually by the Lurgi Phenosolvan process based on the selective extraction of the tar acids with butyl or isobutyl acetate. The recovered phenols are separated by fractional distillation into monohydroxybenzenes, mainly phenol and cresols, and dihydroxybenzenes, mainly (9-dihydroxybenzene (catechol), methyl (9-dihydtoxybenzene, (methyl catechol), and y -dihydroxybenzene (resorcinol). The monohydric phenol fraction is added to the cmde tar acids extracted from the tar for further refining, whereas the dihydric phenol fraction is incorporated in wood-preservation creosote or sold to adhesive manufacturers. Naphthalene Oils. Naphthalene is the principal component of coke-oven tats and the only component that can be concentrated to a reasonably high content on primary distillation. Naphthalene oils from coke-oven tars distilled in a modem pipe stiU generally contain 60—65% of naphthalene. They are further upgraded by a number of methods. 

Blended coal is first heated in coke ovens to produce coke. This process is known as carbonization. The gas produced during carbonisation is extracted and used for fuel elsewhere in the steelworks. Other by-products (such as tar and benzole) are also extracted for further refining and sale. Once carbonised, the coke is pushed out of the ovens and allowed to cool. 

Recovering the bitumen is not easy, and the deposits are either strip-mined if they are near the surface, or recovered in situ if they are in deeper beds. The bitumen could be extracted by using hot water and steam and adding some alkali to disperse it. The produced bitumen is a very thick material having a density of approximately 1.05 g/cm. It is then subjected to a cracking process to produce distillate fuels and coke. The distillates are hydrotreated to saturate olefinic components. Table 1-8 is a typical analysis of Athabasca bitumen. ... 

A schematic diagram of the liquid solvent extraction process is illustrated in Figure 1. Where the production of liquid hydrocarbons is the main objective an hydrogenated donor process solvent is used, whereas in the production of needle coke this is not necessary and a coal derived high boiling aromatic solvent may be used (e.g. anthracene oil). An essential economic requirement of the process is that a high extraction yield of the coal is obtained and this will depend upon the coal used and the digestion conditions. 

Silver is usually found in extremely low concentrations in natural waters because of its low crustal abundance and low mobility in water (USEPA 1980). One of the highest silver concentrations recorded in freshwater (38 pg/L) occurred in the Colorado River at Loma, Colorado, downstream of an abandoned gold-copper-silver mine, an oil shale extraction plant, a gasoline and coke refinery, and a uranium processing facility (USEPA 1980). The maximum recorded value of silver in tapwater in the United States was 26 pg/L — significantly higher than finished water from the treatment plant (maximum of 5.0 pg/L) — because of the use of tin-silver solders for joining copper pipes in the home, office, or factory (USEPA 1980). 

Ashcroft-Elmore A process for extracting tin from its ores. The ore is mixed with coke and calcium chloride and heated in a rotary kiln to 800°C. Stannous chloride, formed by the reaction ... 

Boliden (2) A lead extraction process in which a sulfide ore, mixed with coke, is smelted in an electric furnace, air jets forming vortices between the electrodes. Discontinued in 1988 in favor of the Kaldo process, using a rotating furnace. 

DISTAPEX A process for removing aromatic hydrocarbons from pyrolysis gasoline or coke-oven benzole by extractive distillation with added N-methyl pyrrolidone. The operating temperature is at least 170°C. Developed by Lurgi. First announced in 1961 by 1993, 22 plants had been built. 

Hojanas Also called Siurin. An iron extraction process. Magnetite, mixed with carbon-coke breeze and limestone, is heated in a ceramic retort by passage through a tunnel kiln at 1,200°C. Used commercially in Sweden since 1911. See also DR. 

Mansfield A process for extracting copper from sulfide ores by roasting with anthracite or coke and a silicious flux in a special blast furnace. 

Pedersen A process for extracting aluminum from bauxite, which also yields metallic iron. The ore is first smelted in an electric furnace with limestone, iron ore, and coke at 1,350 to 1,400°C to produce a calcium aluminate slag and metallic iron. Aluminium is leached from the slag by sodium carbonate solution, and alumina is then precipitated from the leachate by carbon dioxide. The process requires cheap electricity and a market for the iron. It was invented by H. Pedersen in 1924 and operated at Hoy anger, Norway, from 1928 until the mid-1960s. British Patent 232,930. 

Peniakoff A process for extracting aluminum from bauxite or other aluminous ores. The ore is roasted with coke and sodium sulfate in a rotary kiln at 1,200 to 1,400°C this converts the aluminum to sodium aluminate, which is leached out with dilute sodium hydroxide solution. The basic reactions are ... 

Phenolsolvan A process for extracting phenols from coke-oven liquor and tar acids from tar by selective solvent extraction with di-isopropyl ether (formerly with -butyl acetate). Developed by Luigi in 1937. 

Phenoraffin A process for recovering phenols from carbonizer tar and coke-oven tar. The tar is dissolved in aqueous sodium phenolate and extracted with isopropyl ether. 

St. Joseph Also known as St. Joe. A process for extracting zinc from zinc sulfide ore by electrothermic reduction, practised by the St Joseph Lead Company at its Josephtown refinery in the United States, in the 1930s. A mixture of zinc blende with coke was heated by passing electricity through the mixture. The zinc vapor thus produced was condensed in a bath of molten zinc. The name has also been applied to a similar lead extraction process. 

SULF-X [Sulfur extraction] A regenerable flue-gas desulfurization process in which the sulfur dioxide is absorbed by aqueous sodium sulfide in a bed packed with pyrite. Ferrous sulfate is produced this is removed by centrifugation and calcined with coke and fresh pyrite. Sulfur vapor is evolved and condensed, and the residue is re-used in the scrubber. Piloted in the mid-1980s. Not to be confused with Sulfex or Sulph-X. 

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