Hi guys. Just a few questions on how coke is used for iron extraction and about air.
On a website about iron extraction, they mentioned how :"A high quality coke should be able to support a smooth descent of the blast furnace burden with as little degradation as possible while providing the lowest amount of impurities, highest thermal energy, highest metal reduction, and optimum permeability for the flow of gaseous and molten products. Introduction of high quality coke to a blast furnace will result in lower coke rate, higher productivity and lower hot metal cost."
What does the smooth descent of the blast furnace burden (what's that?) refer to? And how will the coke degrade in this descent? Also, what is coke rate? And in the quote it states that it should have an optimum permeability for the gaseous and molten products. What do these products refer to? And why should the coke be permeable to them since most of it will react with the oxygen in the hot air injected to form carbon monoxide anyway? Or does the gaseous product refer to the carbon dioxide gas that will further react with more carbon to form carbon monoxide?
Also, regarding nitrogen combusting in air, according to wikipedia, "Nitrogen is not considered to be a combustible substance when oxygen is the oxidant, but small amounts of various nitrogen oxides (commonly designated NOx species) form when air is the oxidant." Why is this so? Shouldn't pure oxygen be better since given a volume of gas there will be more oxygen to react in pure oxygen as compared to air? And also since all the heat will go into heating the oxygen gas instead of having to "waste" energy heating the other gases to the same temperature as well? Or are there certain catalyst in the air that facilitate the reaction of nitrogen with oxygen? And lastly as for the reason why this reaction has to take place at high temperatures because nitrogen molecules are held together by triple covalent bonds so presumably the activation energy/heat required to overcome these bonds are very high ? (N2 used as gas in some lightbulbs? )
Thanks!