Effect of low temperature oxidation on preparation of formed coke from low rank pulverized coal

The effect of low temperature oxidation of briquette on the composition and structure of formed coke products was studied, the coke which was prepared from low rank pulverized coal with binders such as coal tar, pitch and coking coal by using molding pyrolysis technology.The oxidation process of briquette and structure and properties of pyrolysis products were characterized by TG-DTG, FT-IR and SEM.The result shows that the carbonyl and carboxyl groups in the briquette are oxidized to produce CO and CO₂ during the air oxidation process, meanwhile, the content of cycloalkane and aliphatic hydrocarbons have decreased.In the dehydrogenation polymerization of heavy oil, asphalt and oxygen, the reaction produces polycyclic aromatic hydrocarbon macromolecular substances with higher degree of aromatic.The content of heavy components in briquette after oxidative treatment is greatly reduced, and the apparent increase of content of asphaltene and preasphaltene is the main reason for the increase of compressive strength.The oxidation of mixed samples with low rank coal and binder in air atmosphere is divided into two stages.The first stage is from room temperature to 120 ℃, mainly the escape of water and a small amount of adsorbed gas in the raw material.After 120 ℃, in the dehydrogenation polymerization of the aromatic substances in the raw material and oxygen to produce the part of the aromatic with a higher degree of polycyclic aromatic hydrocarbons.And this stage of weight loss rate can reach 11.08%, the maximum weight loss rate peaks at around 217.77 ℃.