New Utilization of Specific Biomass: Lignin in the Iron Ore Sintering Process

The use of lignin can be one of the methods of coke powder substitution in the agglomeration process. This article specifies the material research of lignin and the technological and ecological parameters of the agglomeration process in laboratory conditions using biomass lignin. The methodology of the Raman and infrared spectroscopy, representing a new approach in the analysis and assessment for the purposes of material characteristics for the agglomeration process, was applied to study the structure of carbonaceous matter. The material research of lignin has determined that its calorific value corresponds to ca. 80% of the calorific value of coke powder, while its reactivity is higher than that of the coke. Although the substitution of coke powder using different types of waste biomass (e.g., wood sawdust) in the production of the agglomerate is limited to the maximum of 8–15%, in case of lignin, more than 20% can be substituted, while the standard properties of the produced agglomerate are maintained. The lower emissions of sulfur and nitrogen oxides as well as the reduction of carbon footprint in the agglomeration process as a result of the so-called zero CO2 balance in the formation and processing of the biomass represent its positive aspects. Based on the laboratory research of lignin, up to a 50% substitution of coke powder with this type of biomass can be predicted for the technology of agglomerate production in real operation.

Experimental study on tribological characteristics in coke powder lubrication

Pushing coke is an important process in coke oven production. In the process of pushing coke, under the three-body contact state of steel, coke powder, and refractory brick, coke powder plays an important role in lubrication. In this article, a study on the macro- and micro-behavior and mechanism of coke powder lubrication is carried out through tribological tests. The results show that in the process of sliding friction, coke powder plays a role of lubrication through forming a powder layer and shearing occurred inside the powder layer. The load keeps at 5 MPa, under the lower velocity, the powder layer is thinner and delamination occurred in local position. While under the higher velocity, the coke powder can form a compact and complete powder layer and exhibit better lubrication characteristics. However, when the velocity increases to 0.52 m/s, the continuous powder layer is not formed, so the friction coefficient is higher, the frictional surface wears seriously and results in vibration to occur. The velocity keeps at 0.40 m/s, and the powder layer inclines to deteriorate under higher load. When the load increases to 20 MPa, a part of the powder layer is damaged, and severe wear occurs on the surface.

Improved Removal of Quinoline from Wastewater Using Coke Powder with Inorganic Ions

In this paper, laboratory batch adsorption tests were performed to study the adsorption behavior of coke powder in a quinoline aqueous solution with the absence and presence of inorganic ions (K+ and Ca2+). Adsorption isotherms, thermodynamic parameters, and kinetic models were used to understand the sorption mechanism, and zeta potential measurements were performed to elucidate the effect of the inorganic ions on the adsorption. The results showed that coke powder exhibited a reasonably good adsorption performance due to its pore structure and surface characteristics, and the presence of K+ and Ca2+ could further improve the adsorption. Without inorganic ions, the adsorption capacity of coke powder for quinoline and the removal efficiency of quinoline were 1.27 mg/g and 84.90%, respectively. At the ion concentration of 15 mmol, the adsorption capacity of coke powder and quinoline removal efficiency in the presence of K+ reached 1.38 mg/g and 92.02%, respectively, whereas those in the solutions with Ca2+ reached 1.40 mg/g and 93.31%, respectively. It was found that the adsorption of quinoline onto coke powder in the absence and presence of inorganic ions fit the Freundlich isotherm. Changes in the Gibbs free energy, the heat of adsorption, the entropy, and the activation energy of adsorption suggest that the adsorption was spontaneous and exothermic, which was dominated by physical adsorption, and that the added K+ and Ca2+ would favor the adsorption. In addition, the pseudo-second-order kinetic model was found to provide the best fit to the adsorption kinetic data, and K+ and Ca2+ increased the rate of quinoline adsorbed onto coke power. This improved adsorption due to inorganic ions was found to be a consequence of the decrease in the surface potential of coke powder particles, which resulted in a reduced thickness of water film around particles, as well as a decreased electrostatic repulsion between coke powder particles and quinoline molecules.

β-Si3N4 Microcrystals Prepared by Carbothermal Reduction-Nitridation of Quartz

Single phase β-Si3N4 with microcrystals was synthesized via carbothermal reduction-nitridation (CRN) of quartz and carbon coke powder as starting materials. The effects of reaction parameters, i.e., heating temperature, holding time, C/SiO2 ratio, Fe2O3 additive and β-Si3N4 seeds on the phase transformation and morphology of products were investigated and discussed. Rather than receiving a mixture of both α- and β- phases of Si3N4 in the products, we synthesized powders of β-Si3N4 single polymorph in this work. The mechanism for the CRN synthesis of β-Si3N4 from quartz and the formation mechanism of Fe3Si droplets were discussed. We also firstly reported the formation of Fe3Si Archimedean solids from a CRN process where Fe2O3 was introduced as additive. Comparing to the gear-like short columnar morphology observed in samples without β-Si3N4 seeding, the addition of β-Si3N4 seeds led to an elongated morphology of final products and much finer widths. In addition, the β-Si3N4 microcrystals exhibited a violet‒blue spectral emission range, which could be highly valuable for their future potential optoelectronic applications.