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Russian aircraft carrier Admiral Kuznetsov uses mazut as a fuel, leading to a visible trail of heavy black smoke that can be seen at a great distance. Russian naval officials have said that the failure to properly preheat the heavy mazut fuel prior to entering the combustion chamber may contribute to the heavy smoke trail associated with the ship.[1]

Mazut (Russian: Мазут, romanizedMazut) is a low-quality heavy fuel oil, used in power plants and similar applications. In the United States and Western Europe, by using FCC or RFCC processes, mazut is blended or broken down, with the end product being diesel.[2][3] Mazut may be used for heating houses in the former USSR and in countries of the Far East that do not have the facilities to blend or break it down into more conventional petro-chemicals. In the West, furnaces that burn mazut are commonly called "waste oil" heaters or "waste oil" furnaces.

There have been signs of mazut burning in Iran to compensate for the shortage of natural gas but it has caused environmental problems notably causing huge amounts of air pollution in big cities such as Tehran.[4]

Mazut-100 is a fuel oil that is manufactured to GOST specifications, for example, GOST 10585-75 (not active) or GOST 10585-2013 (active as per December 2019[5]). Mazut is almost exclusively manufactured in Russia, Kazakhstan, Azerbaijan, and Turkmenistan.[6] This product is typically used for larger boilers in producing steam, since the energy value is high.

The most important factor when grading this fuel is the sulfur content, which can mostly be affected by the source feedstock. For shipment purposes, this product is considered a "dirty oil" product, and because viscosity drastically affects whether it is able to be pumped, shipping has unique requirements. Mazut is much like No. 6 fuel oil (Bunker C) and is part of the products left over after gasoline and lighter components are evaporated from the crude oil.

Different types of Mazut-100[edit]

The main difference between the different types of Mazut-100 is the content of sulphur. The grades are represented by these sulfuric levels:[7]

  • "Very low sulphur" is mazut with a sulphur content of 0.5%
  • "Low sulphur" is a mazut with a sulphur content of 0.5–1.0%
  • "Normal sulphur" is a mazut with a sulphur content of 1.0–2.0%
  • "High sulphur" is a mazut with a sulphur content of 2.0–3.5%

Very-low-sulphur mazut is generally made from the lowest-sulfur crude feedstocks. It has a very limited volume to be exported because:

  • The number of producers in Russia is limited. Refineries that produce this are generally owned by the largest domestic oil companies, such as Lukoil and Rosneft, etc.
  • In Russia and the CIS countries a minimum of 50% from the total produced volume is sold only to domestic consumers in Russia and the CIS.
  • Most of the remainder amount is reserved by state quotas for state-controlled companies abroad.
  • The remaining volume available for export is sold according to state quotas, via state auctions, accessible only to Russian domestic companies.[citation needed]

Low- to high-sulfur mazut is available from Russia and other CIS countries (Kazakhstan, Azerbaijan, Turkmenistan). The technical specifications are represented in the same way, according to the Russian GOST 10585-99. The Russian origin mazut demands higher prices.


  1. ^ Gao, Charlie. "Russia's Aircraft Carrier Is a Smokey Mess: Here's Why". Yahoo! News. Retrieved 26 July 2020.
  2. ^ Keyvan Hosseini, Agnieszka Stefaniec (2019-12-15). "Efficiency assessment of Iran's petroleum refining industry in the presence of unprofitable output: A dynamic two-stage slacks-based measure". Energy. 189: 116112. doi:10.1016/ ISSN 0360-5442. S2CID 203996175.
  3. ^ "Prohibition of mazut consumption in Iran".
  4. ^ "Official: 'Iran Burning Mazut In 14 Power Plants' As Major Cities Suffer From Air Pollution - Iran Front Page". 2023-01-21. Retrieved 2023-01-24.
  5. ^ "GOST 10585-2013 – Petroleum fuel. Mazut. Specifications". – Russia & CIS standards norms regulations in English. Retrieved 2019-12-08.
  6. ^ Definition of mazut in English by Oxford Dictionaries: Origin: Late 19th century; earliest use found in Chambers's Journal of Popular Literature. From Russian mazut fuel oil, perhaps from an Azerbaijani Turkish derivative ultimately of Arabic zayt oil (plural zuyūt); probably unrelated to Russian regional mazutina oily stain (Tver′ region, 1897), Russian mazat′ to oil, to smear...
  7. ^ Mazut, Page 54, CIR Staff Paper, Center for International Research (U.S.), Publisher: U.S.S.R. Input-Output Branch, Center for International Research, Bureau of the Census, U.S. Department of Commerce, 1984.