The beginning of the amazing events at Krakatoa in 1883 date to May 20 when there were initial rumblings and venting from the volcano, which had been dormant for about 200 years.
A refinery margin is the revenue associated with refining petroleum, expressed as a value per volume (e.g. $/L), net of the cost of the crude oil input. The simplest refining
Refining is the process of reducing the impurities in a substance. You can't turn crude oil into gasoline without first refining it. Refining is nowadays most commonly associated with the processing of petroleum products such as oil and gas, but it also applies to precious metals, especially those used in jewelry. Sugar is another substance that undergoes refining, which makes it less grainy and more consistent.