Clean Preparation of Formed Coke from Semi-coke by the Carbonated Consolidation Process.

In order to address the low thermal efficiency of low-rank coal combustion and the accompanying serious environmental issues, formed coke was prepared using a carbonization consolidation method with low-rank coal semi-coke. The test for briquetting and carbonation consolidation conditions revealed that the optimal parameters were a briquetting pressure of 93.63 MPa, moisture content of 16%, Ca(OH)2 binder amount of 10%, and a CO2 concentration of 30% at 20 °C. Under these conditions and a carbonation consolidation time of 60 min, high-quality formed coke was produced, exhibiting a compressive strength of 1256.2 N/a, redrying strength of 286.2 N/a, and a dropping strength of 10.6 number/a. The combustion characteristics of the prepared formed coke were investigated, revealing that ignition temperatures (345.39 °C), burnout temperatures (495.57 °C), and peak of the maximum weight loss rate temperatures (437.93 °C) are slightly higher than those of bituminous coal. The low calorific value of the briquette was 20.4 MJ/kg. During the combustion process, the emission concentrations of SO2, NOX, and solid particles from the formed coke were significantly lower than those of bituminous coal, indicating that it is a cleaner energy source. Moreover, adding Ca(OH)2 effectively reduced SO2 emissions and achieved sulfur fixation and emission reduction.

Performance on desulfurization and denitrification of one-step produced activated carbon for purification of sintering flue gas.

An innovative one-step process for activated carbon production from low-rank coal is proposed in this research by applying oxidized pellets as activator. The new process can realize synchronous production of the activated carbon and direct reduction iron through combination of carbonization and activation of low-rank coal in one step while no solid wastes were discharged. The desulfurization and denitrification performance of the obtained activated carbon was also evaluated on the simulative sintering flue gas in comparison with one type of commercial activated carbon. The results indicated that a superior activated carbon with high specific surface area of 370.42 m2 g-1, iodine sorption value of 695.13 mg g-1, compressive strength of 315 N·per-1and abrasive resistance of 96.61%, can be prepared under suitable conditions of activation temperature at 850 °C for 140 min with C/Fe mass ratio of 2.5. Meanwhile, the direct reduction iron has a metallization ratio of 88.31%. The activated carbon has a preferable desulfurization performance with the breakthrough sulfur capacity of 5.463 mg/g and breakthrough time of 46.33 min, and single denitrification performance with the breakthrough nitric capacity of 1.935 mg/g and breakthrough time of 90.17 min at flue gas temperature of 80 °C, airspeed ratio of 8370 h-1, gas flow of 1.8 m3/h, and oxygen concentration of 16%. The denitrification of activated carbon in the simultaneous desulfurization and denitrification process can be improved by catalytic reduction via the transformation from NO to N2. The good results show that this process has a bright future with high technical and economic feasibility.

Enhanced adsorption of NO onto activated carbon by gas pre-magnetization.

The NO removal efficiency was relatively low in the traditional activated carbon adsorption process. In this work, a gas pre-magnetization and activated carbon adsorption process was developed to enhance the adsorption of NO onto activated carbon. In this innovative and green process, the mixed gas was magnetized in the external magnetic field and then absorbed by activated carbon. The results indicated that the maximal removal rate of NO could be increased from 75.0% to 89.5%, and the NO adsorption capacity of commercial activated carbon in one hour elevated from 2.28 to 2.60 mg/g when the magnetic induction intensity of external magnetic field increased from 0 T to 2 T. The strengthening mechanism of the gas pre-magnetization was investigated. It was found that magnetic field could elevate the oxidation rate of NO by 11.4% and thus promote the physical adsorption of NO onto activated carbon. External magnetic field could increase the reaction activity of NO and promote the chemical reaction between NO and some functional groups (CO, CO and COOH) on the activated carbon and thus promote the chemisorption process of NO.