Document Type : Original Article
School of chemistry and chemical engineering, Yulin University, Yulin City, Shaanxi Province，China
Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization,Yulin, Shannxi, China
National Coal and Salt Chemical Product Quality Supervision and Inspection Center,Yulin, Shannxi, China
Taking Shanxi fat coal, Shanxi 4# coke coal and Shenmu low rank pulverized coal as raw materials, three different concentrations of NaOH modified corn stalk were used as binder. The effect of changing NaOH concentrations and coal particle size used in moulding briquette and formed coke on its SEM micrographs, combustion property and FTIR absorption strength were investigated. The micro-properties of corn stalk before and after modification was also discussed. Results showed that the moisture content and ash yield of modified corn stalk increased obviously and the volatile yield showed opposite trend. 2.0% NaOH modified corn stalk showed more voids or porosity which could wrap a large number of coal particles to form strong strength briquette. Addition of modified corn stalk could reduces the briquette burning time and increased burning rate with strong flame and good ignition. From SEM micrograph, briquette had rough surface, and different sizes coal particles and fiber were bound together firmly. Formed coke showed light gray metallic luster, light mass, obvious circular holes and small gaps among particles.The melting colloid and binder could better infiltrate and encapsulate coal particles to form a dense and impermeable entity, which blocked the channels of organic group decomposition during pyrolysis process. Thus, it is forming many holes of different sizes on the surface and inside formed coke. The infrared spectrum of formed coke was simplier than briquette, and the absorption peak number was less and absorption strength was weaker also.