Effect of coating structure of granulated quasi‐fuel particles in iron ore sintering

Abstract

To reduce greenhouse gas emissions, biomass fuels are used to gradually replace fossil fuels in the sintering process. Unfortunately, the sinter quality will deteriorate sharply due to too fast combustion rate when using biomass fuels. To address this problem, pregranulation proved to be an effective method. In this study, the pilot‐scale sinter pot tests were carried out to study the effect of coating structure of granulated quasi‐fuel particles on the granulation properties, flame front propagation in sintering, sinter indexes, sinter mineralogy, and pore structure. The experimental results show that when substituting coke with biomass char, the average size of the granules decreased whereas bed voidage increased due to the irregular shape and lower apparent density of granules. Pregranulation can reduce the flame front speed and increase the maximum bed temperature, thereby alleviating the deterioration of sinter quality and sinter yield. By pregranulating biomass char and 2% magnetite concentrate, the tumbler strength, sinter yield, and productivity can be increased from 44.9% to 55.0%, from 41.9% to 49.3%, and from 28.54 to 31.10 t/m2/d, respectively. The microscopic observation results show that substituting coke with biomass char for sintering decreased the content of calcium ferrite in sinter and increased sinter porosity. On the contrary, pregranulating increased calcium ferrite content in sinter and decreased sinter porosity, and thus sinter quality was improved.

Effect of raw material composition on combustion behavior of quasi‐particles in the iron ore sintering process

“…The coke breeze and biomass char used are consistent with the materials used in our previous research, as shown in Tables 1 and 2. 29 The ores, fuels, and hydrated lime used are fine powders of less than 250 μm after grinding and screening, the chemical composition of which is shown in Table 3.…”

Iron Ore Granulation for Sinter Production: Developments, Progress, and Challenges

“…The contact angle between coke breeze and water was significantly larger than that between iron ore and water, which was the main reason for the hydrophobicity of fuel during the granulation process 85) . For the granulation performance of biomass fuels, extensive results have shown that the average particle size of the mixture decreases after the replacement of coke breeze by biomass fuels [86][87][88] , and due to the larger specific surface area and porosity, biomass fuels require more water to be added during granulation compared to coke breeze and anthracite.…”

“…It is worth mentioning that when sintering with biomass fuels, processes that use biomass fuels as the core with other feedstock coating are proposed to solve the problems of insufficient liquid phase generation and low productivity caused by the fast combustion rate of biomass fuels 88,119) . The specific step is to pre-granulate the biomass fuel with the flux for 4 minutes, and then add other materials as a coating to wrap the biomass fuel and continue granulation for 4 minutes, as shown in Fig.…”

Industrial waste and biomass charcoal composite fuel for iron ore sintering: harmless disposal of waste and carbon reduction

“…Ji et al used the pregranulation method to encapsulate CaO and magnetite around the fuel, and the experimental results showed that this method slowed charcoal combustion while achieving NOx reduction. Lai et al also demonstrated in their experiments that charcoal coating sintering can reduce the flame front speed, increase the highest bed temperature, and alleviate the decline in sinter quality and output. However, the pregranulation for charcoal is relatively simple, which results in an unsatisfactory coating effect of flux or ore powder on charcoal.…”