Mingyin Kou

Establishment of a Static Model Based on Measured Heat Loss for COREX Process

The heat loss and its distribution are of great importance for the calculation and simulation of COREX process. Based on Baosteel COREX process, a method was applied to measure the heat loss of the furnace shell, the accessory equipments and the cooling water system. Then, a static model was established based on the measured heat loss of COREX process. The results showed that the main heat loss of furnace shells took place at the dome of the COREX melter-gasifier and the reducing gas entrance position of the shaft furnace while the main heat loss caused by cooling water occurred at the tap hole area. And the heat loss caused by cooling water accounts for about 85% of the total heat loss in COREX process. The measured total heat loss for producing every 1 t hot metal was 542. 164 MJ, which accounted for about 92% of the theoretical total heat loss.

Analysis of Operational Parameters Affecting the Degree of Metallization of DRI in a Reduction Shaft of the COREX Process and Improvement Measures

The COREX process, which is considered to be able to replace the blast furnace, still has some gaps to reach the designed productivity. The metallization degree is regarded as one of the limitations of the COREX process. In the present work, several parameters affecting the metallization degree of direct reduced iron (DRI) are analysed by SPSS software (Statistical Product and Service Solution). Melting rate, oxidation degree of reducing gas, oxidation degree of top gas, top gas consumption per ton of burden, temperature of reducing gas, and burden distribution index are confirmed as the main factors affecting metallization degree. Based on this, a linear equation has been developed for predicting metallization degree. Additionally, improving the melter gasifier vault temperature appropriately, increasing the proportion of high volatile matter coal, and optimizing the type and particle size of iron ore and the pattern of burden distribution have been shown to improve the metallization degree.

DEM Simulation of Dispersion of Cohesive Particles by Spontaneous Inter-particle Percolation in a 3D Random Packed Bed

Spontaneous inter-particle percolation is a common phenomenon in nature and industries. Dispersion of cohesionless particles has been investigated by means of various physical and numerical experiments. However, many granular materials are in cohesive or wet state in metallurgical and mineral processes, and the previous works have a lack of understanding the effect of cohesive force on particle dispersion behaviour. Thus, the present work systematically studies the dispersion of cohesive particles by spontaneous inter-particle percolation in a packed bed using discrete element method (DEM). The results indicate that the vertical velocity of percolating particles increases with increasing the cohesive force from 0 to 2 mg (the gravity force of percolating particle, given by ρ gπd 3/6). While for a higher cohesive force, e.g. f c = 8 mg, insufficient percolation occurs and percolating particles stick in the packed bed. Percolating particles in the packed bed shows a diffusivity for the cases of smaller cohesive force, and the diffusion property can be described by Einstein-Smoluchowski equation. The transverse dispersion of f c = 2 mg is smaller than that of f c = 0, while the longitudinal dispersion becomes larger when the cohesive force changes from 0 to 2 mg. This study provides a fundamental understanding on dispersion behaviour of cohesive particles in a packed bed, and is useful for processes understanding and optimization in cohesive particles handling and mixing.

Influence of Coke Quality on Main Technical Indexes of Blast Furnace

Coke plays an important role on the actual blast furnace production (BF), and its quality significantly influences the BF ironmaking process. In this study, the effects of physical properties, chemical composition and high-temperature properties of coke on main technical indexes of blast furnace were investigated. Some coke indexes were defined to evaluate the coke quality. The main technical indexes of BF include production, quality of HM, and fuel consumption. The quantitative relationship between coke quality and main technical indexes of BF were obtained after a series of statistical analysis. What’s more, the effect of these coke quality indexes on blast furnace smelting process was also explored, and all the relationships obtained from the analysis will provide a theoretical basis for the appropriate use of coke in blast furnace. The most reasonable range of coke quality indexes can be determined combining with the actual production as well.

Study on the sintering melting characteristics of Meishan concentrate and its influencing factors

ABSTRACT The melting characteristics of iron ore plays an important role in the process of sintering and mineralization. The softening and melting process of Meishan concentrate, the main mineral in the sintering of Meishan Iron and Steel Company, and four typical imported iron ores were observed through a visual micro-sintering test device. The results show that the Meishan concentrate has a relatively gentle liquid-phase velocity, good liquid-phase temperature control property, and relatively good safety. In addition, with the increase in alkalinity, its melting characteristics become worse. When combined with OA, its melting characteristics became worse, and with OD ore, its melting characteristics had improved in our study. Therefore, based on the principle of optimizing the complementary ore blending, in order to ensure the good temperature control and safety of the Meishan concentrate in the liquid phase of the sintering process, the appropriate sinter basicity and the appropriate type of iron ores should be selected.

Experimental study and numerical simulation of dust accumulation in bustle pipe of COREX shaft furnace with areal gas distribution beams

ABSTRACT The following study investigated the dust accumulation in the bustle pipe of the shaft furnace with Areal Gas Distribution (AGD) through physical and numerical simulations. Although the experimental and numerical results were obtained from different-sized furnaces, the results had a similar tendency, where an initial dust deposition zone formed in the packed bed located in front of slots 8–12. The growth velocity of the deposition zone became larger than the descending velocity. It then spread upwards, to plug the slots, until the dust accumulation was formed. The gas velocity in the bustle pipe decreased after passing the AGD beam due to nearly 60% gas that went into the furnace through the AGD inlet. This was the primary cause for the dust accumulation in slots 8–12. Both the physical and the numerical results showed that when the blast volume increased, it effectively reduced the dust flux in each slot and decreased the clogging effect.

Characteristics and analyses of COG injection from tuyere in COREX melter gasifier

ABSTRACT Coke oven gas (COG), as an environment-friendly source, is projected to be introduced into the COREX process to reduce solid fuel consumption. In this paper, a static model has been developed based on mass and heat balance, which can calculate characteristics of melter gasifier, such as the raceway adiabatic flame temperature (RAFT), volume and component of bosh gas. The results showed that compared with N2, the COG injection from tuyere is more effective on reducing the RAFT and improving the bosh gas volume. The quantity of COG injected is limited for the RAFT, and without other thermal compensation, the largest injection quantity is about 150 Nm3 t−1. The quantity of COG injection can be increased by preheating tuyere oxygen, adjustment of fuel structure and addition of tuyere oxygen. COG injection can promote the reduction and hearth permeability, decrease the RAFT and protect the tuyere, which is beneficial to COREX operation.

Influence of Operation Parameters on Sticking Behavior of Pellets in COREX Shaft Furnace

The sticking behavior of iron ores in the shaft furnace is one of the most important problems in the COREX melting progress, which directly influence the smooth operation and productivity of shaft furnace. Therefore, it is of great importance to study the sticking behavior of pellets in COREX shaft furnace. The results showed that porous metallic iron produced at the interface of pellets samples was the main reason for the sticking of pellets in the COREX shaft furnace. The SI (sticking index) and metallization rate increased with the reduction temperature and gas flow, and decreased with melting rate. However, the SI of pellets in the COREX shaft furnace could be decreased by the proper match of melting rate and reduction temperature, reduction temperature and gas flow, while the metallization rate of pellets were kept at a certain level. Furthermore, the matching of melting rate and reduction temperature was more effective than the matching of reduction temperature and gas flow.

Low CO2 Emission by Improving CO Utilization Ratio in China’s Blast Furnaces

In recent years, the CO2 emission in China is the highest all around the world, accounting for about 30 %. China’s 15 % CO2 emission is produced from iron and steel companies, where blast furnace contributes more than 60 %. Therefore, blast furnace is the key to reduce CO2 emission for iron and steel companies. Blast furnace is a countercurrent reactor between descending burdens and ascending gas. The higher the CO utilization ratio is, the lower the CO2 emission. There are two main measures to improve CO utilization ratio—upper adjustment and lower adjustment. The upper adjustment is mainly about the burden distribution which includes adjusting batch weight, charging mode, stock line and so on. The lower adjustment is mainly about the gas distribution in the lower part of the blast furnace, which includes adjusting the gas volume, gas temperature, gas humidity and so on. The paper presents the upper and lower adjustments to improve CO utilization ratio in China’s blast furnaces.

Studying on Softening and Melting Behavior of Lump Ore in Blast Furnace

Softening and melting experiments were conducted on four kinds of imported lump ores named A-D, under different temperature intervals within the self-developed visualization high temperature furnace. By calculating the reduction and shrinking degree under different intervals, softening and melting indexes were determined. These ores all expanded firstly followed by shrinkage with the temperature increasing. The difference of lump ore’s own characteristic led to different softening and melting behavior. The results showed that the looser the structure was, the better the reducibility will be. The compact structure and good reducibility led to high expansion rate. The beginning softening temperature declined and the ending softening temperature increased because of high porosity, which resulted in wide softening temperature interval. The charging ratio of lump ore A should be improved. Lump ore B should be distributed in the center of the blast furnace. Lump ores C and D should be used less.