Gele Qing’s research while affiliated with Shougang Institute of Technology and other places

The detachment regimes and corresponding detachment height of lower liquid from a coated bubble during the bubble passage through an immiscible liquid–liquid interface were studied. High-speed imaging techniques were used to visualize the lower liquid detachment from a rising bubble near the interface. Analysis of industrial slag samples by a scanning electron microscope (SEM) was also carried out. The results indicate that the detachment height of lower liquid from a rising bubble showed a distinct correlation to penetration regimes. Bubble size and a fluid’s physical properties exerted a significant influence on the detachment height of the lower liquid. The detachment height for medium bubbles (Weber number: 4~4.5; Bond number: 2.5~7.5) varied significantly with increasing bubble size, which contributes to the lower liquid entrainment in the upper phase due, significantly, to the higher detachment height and large entrainment volume. The maximum detachment height for large bubbles is limited to approximately 100 mm due to the early detachment with the liquid column at the interface though large bubbles transporting a larger volume of lower liquid into the upper phase.

In the settlement zone of the copper smelting furnace, SO2 bubbles will be generated due to the insufficient oxidization of copper matte concentrate by injected oxygen-rich air in the reaction zone, entailing mass transfer in the liquid–liquid system by a rising bubble penetrating through the liquid–liquid interface. Different operating conditions between the bottom blown furnace and side blown furnace lead to different slag and matte viscosity. To investigate the copper smelting slag viscosity effect on the matte entrainment volume, cold model experiments using high-speed imaging techniques and high-temperature experiments were carried out. Results show that the lower liquid entrainment volume increases with the decreasing upper liquid viscosity and increasing bubble size. Higher slag viscosity and more SO2 bubbles generated in the side blown furnace probably deteriorate the matte entrainment in the slag phase, while matte viscosity exerts slight influences due to the stable viscosity variation.

More and larger blast furnaces have been constructed for ironmaking across the world in recent years due to the advantages of high productivity, high energy efficiency and low cost. Slag plays important role in a blast furnace to produce high-quality hot metal and maintain smooth operations. Liquidus temperatures are the essential information of the slag to avoid the formation of the solid phase during the ironmaking process and slag tapping. The principal components of the iron blast furnace slags can be described by the system CaO-MgO-Al2O3-SiO2. With the significant changes in the raw materials and different requirements of the blast furnace operations, phase equilibria in this slag system have been extensively investigated from different directions. Phase diagrams were presented in various pseudo-ternary and pseudo-binary forms to meet the requirements of wide applications. Reliable thermodynamic modelling is the target of the researchers which can predict accurate liquidus temperatures of the slag. Development of the reliable thermodynamic modelling relies on systematic and accurate experimental data including liquidus temperatures and compositions of the solid solutions. Experimental data on the phase equilibria of the system CaO-MgO-Al2O3-SiO2 are summarised and compared with the thermodynamic predictions which can provide systematic information for the researchers and blast furnace operators.

With the raw materials for ironmaking are becoming increasingly complex, more accurate control of blast furnace operation is essential to reduce the energy cost and CO 2 emission. CaO–SiO 2 –Al 2 O 3 –MgO is a basic system of ironmaking slag in which CaO and MgO are mainly come from the flux, SiO 2 and Al 2 O 3 are mainly from the raw materials. Effect of raw material composition on phase equilibrium of the slag can be described by a pseudo-ternary system (CaO + MgO)–SiO 2 –Al 2 O 3 at a fixed MgO/CaO ratio of 0.2. High-temperature experiments have been carried out in this system, and the quenched samples were analyzed by an electron-probe microanalyzer. The results are presented in a pseudo-ternary phase diagram (CaO + MgO)–SiO 2 –Al 2 O 3 with a fixed MgO/CaO weight ratio of 0.2. Dicalcium silicate (Ca 2 SiO 4 ), Melilite (2CaO·MgO·2SiO 2 –2CaO·Al 2 O 3 ·SiO 2 ), spinel (MgO·Al 2 O 3 ), merwinite (3CaO·MgO·2SiO 2 ), and anorthite (CaO·Al 2 O 3 ·2SiO 2 ) are the major primary phases in the composition range investigated. A series of pseudo-binary phase diagrams have been constructed to demonstrate the applications of phase diagram on blast furnace operation. CaO-rich cordierite solid solution has been first time reported with the accurate compositions and microstructure. The liquidus temperatures and solid solution compositions are compared between the experimental data and FactSage predictions to provide useful information for optimization of the thermodynamic database.

The increased utilization of pellets in blast furnaces is one of the directions for low-carbon ironmaking. As a result, the low slag rate may affect the desulfurization of the hot metal and the removal of alkali in the blast furnace. Effective desulfurization and the removal of alkali in the low slag ironmaking process have become the focus of the steel industry. In this paper, the effects of slag quantity, temperature, reaction time and slag composition on the desulfurization and removal of alkali were studied using the slag-metal reaction method. It was found that the slag quantity had the same influence trend on the desulfurization and the removal of alkali. The greater the slag quantity, the more effective the desulfurization and the removal of alkali. The slag composition, temperature and reaction time had the opposite effect on the desulfurization and the removal of alkali. High temperature, long reaction time, high MgO concentration, high CaO/SiO2 ratio and low Al2O3 concentration increased the desulfurization of hot metal but reduced the removal rate of alkali from the blast furnace. Applications of the experimental results on high-proportion pellet blast furnace operation are discussed.

With the raw materials for ironmaking becoming increasingly complex, more accurate phase equilibrium information on the slag is needed to refine the blast furnace operation to reduce the energy cost and CO2 emissions. CaO-SiO2-Al2O3-MgO is a basic system of ironmaking slag in which CaO and MgO mainly come from the flux, SiO2 and Al2O3 are mainly from raw materials. The effect of flux additions on the phase equilibrium of the slag can be described by a pseudo-ternary system CaO-MgO-(Al2O3+SiO2) at a fixed Al2O3/SiO2 ratio of 0.4. Liquidus temperatures and solid solutions in the CaO-MgO-Al2O3-SiO2 system with Al2O3/SiO2 weight ratio of 0.4 have been experimentally determined using high temperature equilibration and quenching techniques followed by electron probe microanalysis. Dicalcium silicate (Ca2SiO4), cordierite (2MgO·2Al2O3·5SiO2), spinel (MgO·Al2O3), merwinite (3CaO·MgO·2SiO2), anorthite (CaO·Al2O3·2SiO2), mullite (Al2O3·SiO2), periclase (MgO), melilite (2CaO·MgO·2SiO2-2CaO·Al2O3·SiO2) and forsterite (Mg2SiO4) are the major primary phases in the composition range investigated. A series of pseudo-binary phase diagrams have been constructed to demonstrate the application of the phase diagrams on blast furnace operation. Composition of the solid solutions corresponding to the liquidus have been accurately measured and will be used for the development of the thermodynamic database.

As an important source of copper losses to the slag, SO2 bubbles formed in the quiescent settlement zone of smelting furnace bring matte into slag phase through the immiscible matte-slag interface. The penetration and entrainment mechanisms of large bubbles were studied while the entrainment by micro bubbles was rarely investigated. In this paper, attachment of matte droplets to micro SO2 bubbles in the industrial smelting slags and laboratory samples have been confirmed by high-temperature experiments. The bubble penetration behaviors through liquid–liquid interface were simulated by the cold model experiments using water and silicone oil. Results showed that fine gas bubbles can pass through the liquid–liquid interface and cause the heavier liquid entrainment. Although the critical bubble penetration size deduced in previous studies is inconsistent with the phenomenon observed in cold model experiments, it is an important parameter to classify the bubble entrainment regimes which is closely associated with the bubble penetration regimes. Greene’s theoretical derived values of critical bubble penetration and entrainment sizes are in good agreement but comparatively higher than the experimental results. The Weber numbers based on the critical bubble penetration size, heavier liquid density, and interfacial tension under different experimental conditions are normally between 4 and 4.5.KeywordsCopper lossMicro bubblesLiquid–liquid interfacePenetration mechanisms

In this paper, an iron ore with high iron grade and low silicon content was used in pelletizing experiments. Specific surface areas were tested, and it would increase slowly and then have a rapid increase with the increasing of particle sizes. Thirty percentage of the high iron grade ore could be used when −200 meshes content of the ore reached to 89% or the ore was grinded by high pressure roller. Compression strength of firing pellet would decrease, higher than 2500 N/P yet, when the ore was added. SiO2 content of firing pellets would decrease from 4.22 to 3.36%, a 20.38% decline, while 30% of the high iron grade ore was added.KeywordsPelletizingSpecific surface areaHigh pressure rollerSiO2 content

Pellet is one of the important feeds to ironIronblast furnaceBlast furnace and increased proportion of the pellet is used around the world. Pellet production is cleaner than sinter and its uniform properties allow stable blast furnaceBlast furnace operations. Boron ironIronconcentrateBoron iron concentrate is a by-product during production of boron and contains approximately 54% Fe, 3–6% B2O3, and 10% MgO. B2O3 can form liquid binding phase inside the pellet at relatively lower temperature which reduces the fuel and refractory consumption during the pellet production. MgO can reduce the reduction expansion rate of the pellets. Effects of boron iron concentrateBoron iron concentrate, preheating temperature, and time on the strength of the preheated pellet have been investigated. It was found that the compressive strengthCompressive strength of the preheated pellet with addition of boron iron concentrateBoron iron concentrate was increased with increasing preheating temperature and time. When the pellets were preheated at 1030 °C for 25 min, the strength of the pellets with 50% boron iron concentrateBoron iron concentrate can reach more than 600 N/P. The optimized parameters can significantly increase the strength of the pellet and reduce the loop formation of the rotary kiln.

In this paper, study on sinter iron oresSinter iron ores and titanium oresTitanium ores used in pelletizing was carried out. Bond work indexes of different sinter iron oresSinter iron ores and titanium oresTitanium ores were measured. Ballability would be improved, and falling strength and compression strength of green pelletsPellet would be increased after fine-grinded sinter iron oresSinter iron ores have been added. High-titanium pelletsPellet with good metallurgical propertiesMetallurgical properties and high compression strength could be produced by using fine-grinded titanium oresTitanium ores. The application of sinter iron oresSinter iron ores and titanium oresTitanium ores used in pelletizing could not only reduce the cost of ironmaking but also expand the iron ore resources for pelletizing.