Editing Bitumen (section)

== Production ==
[[File:Asphalt plant pic.jpg|thumbnail|right|Typical asphalt plant for making asphalt]]
About 164,000,000 tons were produced in 2019. It is obtained as the "heavy" (i.e., difficult to distill) fraction. Material with a [[boiling point]] greater than around 500{{nbs}}°C is considered asphalt. Vacuum distillation separates it from the other components in crude oil (such as [[naphtha]], gasoline and [[Diesel fuel|diesel]]). The resulting material is typically further treated to extract small but valuable amounts of lubricants and to adjust the properties of the material to suit applications. In a [[de-asphalting unit]], the crude bitumen is treated with either [[propane]] or [[butane]] in a [[Supercritical fluid|supercritical]] phase to extract the lighter molecules, which are then separated. Further processing is possible by "blowing" the product: namely reacting it with [[oxygen]]. This step makes the product harder and more viscous.<ref name=UllmannAsph/>
[[File:Stealth Communications laying down asphalt over fiber-optic trench in NYC.jpg|thumb|NYC Internet Provider, [[Stealth Communications]], laying down asphalt over fiber-optic trench]]
Bitumen is typically stored and transported at temperatures around {{convert|150|°C|°F|abbr=on}}. Sometimes [[diesel oil]] or [[kerosene]] are mixed in before shipping to retain liquidity; upon delivery, these lighter materials are separated out of the mixture. This mixture is often called "bitumen feedstock", or BFS. Some [[dump truck]]s route the hot engine exhaust through pipes in the dump body to keep the material warm. The backs of tippers carrying asphalt, as well as some handling equipment, are also commonly sprayed with a releasing agent before filling to aid release. Diesel oil is no longer used as a [[release agent]] due to environmental concerns.

=== Oil sands ===
{{Main|Oil sands}}
Naturally occurring crude bitumen impregnated in sedimentary rock is the prime feed stock for petroleum production from "[[oil sands]]", currently under development in Alberta, Canada. Canada has most of the world's supply of natural bitumen, covering 140,000 square kilometres<ref name=oilsands/> (an area larger than England), giving it the second-largest proven [[oil reserves]] in the world. The [[Athabasca oil sands]] are the largest bitumen deposit in Canada and the only one accessible to [[surface mining]], although recent technological breakthroughs have resulted in deeper deposits becoming producible by ''[[in-situ#Petroleum|in situ]]'' methods. Because of [[world oil market chronology from 2003|oil price increases after 2003]], producing bitumen became highly profitable, but as a result of the decline after 2014 it became uneconomic to build new plants again. By 2014, Canadian crude bitumen production averaged about {{convert|2.3|Moilbbl|m3}} per day and was projected to rise to {{convert|4.4|Moilbbl|m3}} per day by 2020.<ref name="CAPP"/> The total amount of crude bitumen in Alberta that could be extracted is estimated to be about {{convert|310|Goilbbl|e9m3|sigfig=1}},<ref name=ST98/> which at a rate of {{convert|4400000|oilbbl/d}} would last about 200 years.

=== Alternatives and bioasphalt ===
{{Main|Peak oil|Global warming|Bioasphalt}}
Although uncompetitive economically, bitumen can be made from nonpetroleum-based renewable resources such as sugar, [[molasses]] and rice, corn and potato [[starch]]es. Bitumen can also be made from waste material by [[fractional distillation]] of used [[motor oil]], which is sometimes otherwise disposed of by burning or dumping into landfills. Use of motor oil may cause premature cracking in colder climates, resulting in roads that need to be repaved more frequently.<ref>{{Cite journal| doi = 10.1080/10298436.2010.488729| issn = 1029-8436| volume = 11| issue = 6| pages = 541–553| last = Hesp| first = Simon A.M.|author2=Herbert F. Shurvell| title = X-ray fluorescence detection of waste engine oil residue in bitumen and its effect on cracking in service| journal = International Journal of Pavement Engineering| year = 2010| s2cid = 138499155}}</ref>

Nonpetroleum-based asphalt binders can be made light-colored. Lighter-colored roads absorb less heat from solar radiation, reducing their contribution to the [[urban heat island]] effect.<ref>[http://www.epa.gov/heatisland/ Heat Island Effect]. From the website of the US Environmental Protection Agency.</ref> Parking lots that use bitumen alternatives are called [[green parking lot]]s.

=== Albanian deposits ===
Selenizza is a naturally occurring solid hydrocarbon bitumen found in native deposits in [[Selenice]], in [[Albania]], the only European asphalt mine still in use. The bitumen is found in the form of veins, filling cracks in a more or less horizontal direction. The bitumen content varies from 83% to 92% (soluble in carbon disulphide), with a penetration value near to zero and a softening point (ring and ball) around 120{{nbs}}°C. The insoluble matter, consisting mainly of silica ore, ranges from 8% to 17%.

Albanian bitumen extraction has a long history and was practiced in an organized way by the Romans. After centuries of silence, the first mentions of Albanian bitumen appeared only in 1868, when the Frenchman [[Henri Coquand|Coquand]] published the first geological description of the deposits of Albanian bitumen. In 1875, the exploitation rights were granted to the Ottoman government and in 1912, they were transferred to the Italian company Simsa. Since 1945, the mine was exploited by the Albanian government and from 2001 to date, the management passed to a French company, which organized the mining process for the manufacture of the natural bitumen on an industrial scale.<ref>{{cite book|last1=Giavarini|first1=Carlo|title=Six Thousand Years of Asphalt|year=2013|publisher=SITEB|isbn=978-88-908408-3-8|pages=71–78}}</ref>

Today the mine is predominantly exploited in an open pit quarry but several of the many underground mines (deep and extending over several km) still remain viable. Selenizza is produced primarily in granular form, after melting the bitumen pieces selected in the mine.

Selenizza<ref>[http://www.selenicebitumi.com/engindex.php] {{Webarchive|url=https://web.archive.org/web/20150222162429/http://selenicebitumi.com/engindex.php|date=22 February 2015}}, Selenice Bitumi for more information about Selenizza</ref> is mainly used as an additive in the road construction sector. It is mixed with traditional bitumen to improve both the viscoelastic properties and the resistance to ageing. It may be blended with the hot bitumen in tanks, but its granular form allows it to be fed in the mixer or in the recycling ring of normal asphalt plants. Other typical applications include the production of mastic asphalts for sidewalks, bridges, car-parks and urban roads as well as drilling fluid additives for the oil and gas industry. Selenizza is available in powder or in granular material of various particle sizes and is packaged in sacks or in thermal fusible polyethylene bags.

A [[life-cycle assessment]] study of the natural selenizza compared with petroleum bitumen has shown that the environmental impact of the selenizza is about half the impact of the road asphalt produced in oil refineries in terms of [[Greenhouse gas emissions|carbon dioxide emission]].<ref>{{cite journal|last1=Giavarini|first1=C.|last2=Pellegrini|first2=A.|title=Life cycle assessment of Selenice bitumen compared with petroleum bitumen|journal=The 1st Albanian Congress on Roads|pages=234–237}}</ref>