Preparation Of Formed Coke With Low Rank Coal And Binder

Formed coke was prepared by using low-rank coal as the main material and asphalt,heavy oil,and coking coal as the binder.It has important significance for grading,quality and value-added utilization of low rank coal resource.In this paper,formed coke was prepared by using low rank coal as the main material which from Sunjiacha area of northern Shaanxi Province,preparation of formed coke by cold briquetting pyrolysis technology under the function of binder,the mechanism of the increase of coke compressive strength and the coking mechanism of the pyrolysis process were studied.The pyrolysis products of formed coke,tar and gas were analyzed through scanning electron microscopy(SEM),fourier transform infrared spectroscopy(FT-IR),and gas chromatography-mass spectrometry(GC-MS).The results show that the low temperature air oxidation of briquette can effectively improve the formed coke compressive strength.Under the conditions of oxidation temperature 200 ℃,oxidation time 2.5h and air flow 200L/h,the formed coke compressive strength increased 66.7%.After the low temperature oxidation treatment,the carbonyl and carboxyl groups produced by the oxidation of the low rank coal are further reacted to CO,as the oxygen content increased,CO was oxidized to CO2.The asphaltenes and pre-asphaltene content of the formed coal significantly increased.In the asphalt,the aromatics decrease gradually,and the dehydrogenation reaction occurred,and then condensed into macromolecule aromatic asphaltene,etc.And in the pyrolysis process,the formation of liquid colloidal material is beneficial to bond between coal particles,improving the formed coke compressive strength.The pyrolysis experimental results show that the formed coke compressive strength is 11.8MPa at 800 ℃ for 4hours.The formed coke with different binder ratio was carbonized at 1000℃,pyrolysis time is 4h.When the content of low rank coal,coal asphalt,heavy oil and coking coal were added 60%,20%,10% and 10% respectively,the compressive strength reached 18 MPa,CRI was 29%,and the reaction intensity was6.33 MPa.The addition of asphalt contributed to the improvement of the coke compressive strength,while the pyrolysis tar medium content increased.The hydrogen content of low rank coal is high,which will act a hydrogen donor during pyrolysis,caused heavy oil to be light.At the same time,pyrolysis of light components in pyrolysis tar increased,the contents of medium and heavy components.The addition of coking coal is beneficial to improve the content of colloid and the quality of formed coke,but the influence is not as significant as asphalt.