Sintering, as one of the major sources of carbon emissions in the steel industry, is in urgent need of innovation in carbon reduction technology under the targets of carbon peaking and carbon neutrality in China. We propose the carbon free sintering process which is similar to the belt roaster, where heat is provided by gas fuel combustion for the layer. In order to achieve the process, this study uses the micro-sintering method to simulate it by varying the sintering temperature, sintering time and binary basicity of the mixture. It was investigated the process of mineralisation solidification of carbon-free sintering and to provide relevant guidance for future carbon-free sintering process experiments. As the sintering temperature increased, the strength and calcium ferrite of the samples first increased and then decreased, reach the maximum value at 1300°C and 1275°C respectively. However, the porosity of the samples first decreased and then increased, reach the minimum value at 1275°C. As the sintering time increased, the strength and calcium ferrite first increased and then decreased, reach the maximum values at 12 min and 6 min respectively, and the porosity of the samples first decreased and then increased, reach the minimum values at 6 min. As the binary basicity increased, the strength of the samples first decreased and then increased, reach the minimum value at basicity 1.8, and the calcium ferrite and porosity of the samples gradually increased. The carbon-free sintering process does not change the consolidation process of iron ore, and it has theoretical feasibility.

Sintering accounts for about 50% of the total NO_x emissions of the iron and steel industry. NO_x emissions from the sintering process can be simulated using the emissions from coke combustion. However, the generation and emission law for NO_x burning in the sintering process of pulverized coal is still not clear. The formation characteristics of NO_x during coal combustion catalyzed by iron ore fines and several iron-containing pure minerals were studied in this paper. The results showed that iron ore fines can improve the NO_x emission rate and increase the total NO_x emissions during coal combustion. The type and composition of the iron ore fines have an important impact on the generation and emission of NO_x in the process of coal combustion. The peak concentration and emissions of NO_x in coal combustion flue gas with limonite, hematite or specularite added increased significantly. The peak value for the NO_x concentration in the coal combustion flue gas with magnetite or siderite added increased, but the emissions decreased. Therefore, the generation of NO_x in the sintering process can to a certain extent be controlled by adjusting the type of iron-containing raw materials and the distribution of the iron-containing raw materials and coal.

An efficient sintering process was proposed based on the autocatalytic denitrification of the sintered ore. The catalytic denitrification of sintered ore, the effect of double-layer ignition sintering process on the emission reduction in nitrogen oxides, and the impact on the quality of sintered ore were studied. The results showed that the catalyzed reduction of NO with sinter ore as a catalyst has a significant effect; when the airspeed reaches 3000 h⁻¹, the temperature is 500 °C, and the conversion rate of NO can reach 99.58%. The sinter yield of double-layer ignition sintering is increased, solid fuel consumption is slightly reduced, falling strength is slightly increased, and drum strength is slightly decreased. Under the conditions of layer height proportion of 320/400 mm (lower/upper) and ignition time interval of 10 min, the yield, drum strength, shatter strength, and solid fuel consumption reached 61.60%, 54.82%, 46.75%, and 69.55%, respectively. NO_x concentration under the 16% baseline oxygen content ($c_{(N{O}_{x)}}^{’}$) in the flue gas of double-layer ignition sintering is reduced to a certain extent, and the generation time of NO_x is greatly shortened. The double-layer ignition sintering process can reduce the emission of nitrogen oxides in the sintering process under the condition of guaranteeing the quality of sinter, which has great economic and environmental benefits.

Steel and ceramic grinding media differ markedly in density and loss characteristics, so a laboratory-optimized charge composition may not translate directly into an industrial make-up strategy. Seven ceramic:steel mass ratios were screened in batch grinding tests, and 5:5 gave the highest technical grinding efficiency (87.91%). The result was then evaluated during an approximately two-month industrial trial. Daily 1:1 make-up (500 kg steel and 500 kg ceramic) did not provide sustained improvement, while retaining the 1:1 ratio with additions every other day also failed to restore grinding performance, with technical grinding efficiency decreasing to 47.66%. The strategy was subsequently changed to daily additions of 500 kg steel and 300 kg ceramic media. Grinding performance recovered and reached a maximum monitored efficiency of 70.90%. Under stabilized mixed-media operation, the −15 μm product fraction decreased from 33.85% to 27.33%, while the −74 μm fraction remained 87.17%. Average mill power was 1927.82 kW during the all-steel monitoring period and 1136.91 kW during stabilized mixed-media operation. These results show that charge composition, make-up ratio and addition frequency should be considered separately when mixed grinding media are transferred from laboratory tests to continuous industrial operation.