Brown Corundum Research Articles

Numerical investigation of particle behavior and erosion wear in a centrifugal pump using coarse-grained Discrete Element Method

Erosion wear presents a significant challenge in the operation of hydrodynamic systems, particularly in centrifugal pumps. To address this issue, this study employs the coarse-grained Discrete Element Method (CGDEM) coupled with Computational Fluid Dynamics (CFD) to predict erosion wear areas and elucidate particle behavior dynamics. The simulation considers spherical solid particles (brown corundum) with diameters ranging from 0.3 mm to 1 mm and volume fractions of 15% and 5%. The flow field is calculated using the Navier-Stokes equations and the shear-stress-transport (SST) k-ω model. Particle movement is tracked using Newton’s second law, considering drag and gravitational forces. Results indicate that the highest turbulent kinetic energy (TKE) occurs at a flow rate of Q = 15 m3/h. Moreover, the pressure reduces slightly when the flow rate increases, although flow velocity might increase with volumetric discharge. Additionally, increased particle diameter leads to greater erosion wear, particularly on blade leading edges, the volute tongue area, and the volute casing belly region. As particle mass concentration intensifies, wear rates on the volute wall and inner hub edge also increase. The study’s robustness is demonstrated through alignment between experimental and numerical data. This investigation offers valuable insights into erosion dynamics in centrifugal pumps, crucial for enhancing operational efficiency and mitigating erosion-induced challenges in these critical systems.

Study on mullitization of sillimanite group minerals and its effect on properties of the Al2O3‐SiC‐C gunning material

AbstractThis study aimed to compare and summarize the mullitization mechanism of the sillimanite group minerals and investigated its effect on the mechanical properties of Al2O3‐SiC‐C gunning materials. By comparing the phase composition and microstructure of kyanite, andalusite, and sillimanite at different temperatures, the mullitization mechanism of sillimanite group minerals was clarified. Furthermore, the Al2O3‐SiC‐C gunning materials with sillimanite group minerals addition were prepared by bauxite and fused brown corundum as aggregates, fused white corundum (≤0.045 mm), SiC (≤0.075 mm), α‐Al2O3 (≤10 µm), pitch sphere, SiO2 micropowder (≤2 µm) as a matrix, and silica sol as a binder. Then, the effect of the addition of sillimanite group minerals on the mechanical properties of Al2O3‐SiC‐C gunning materials was characterized. The results indicate that kyanite requires the lowest temperature for mullitization compared to andalusite and sillimanite. The mullitization process involves the migration of Al3+ and Si4+, resulting in a decrease in the lattice constant of sillimanite group minerals followed by the production of mullite and SiO2. Incorporating sillimanite group minerals into Al2O3‐SiC‐C gunning materials effectively controls their linear change rate after firing while enhancing their mechanical properties. Notably, the addition of kyanite yields superior performance in Al2O3‐SiC‐C gunning materials.

Erosion model of silicon carbide ceramics and YW3

In this study, an erosion model of silicon carbide ceramics and YW3 was established by combining experimental and numerical simulation data. This model can be applied for the prediction of erosion in natural gas equipment and transportation systems and also provides ideas for the establishment of erosion models. The erosion model was established by using quartz sand, brown corundum, and glass beads as abrasive materials, and then the accuracy of the erosion model was confirmed by numerical simulations. The results showed that when the abrasive was quartz sand, brown corundum, or glass beads, the erosion angle at which the maximum erosion of silicon carbide and YW3 occurred was related to the type of abrasive. When the abrasive was quartz sand, brown corundum, and glass beads, the velocity index n of silicon carbide was 3.24, 3.66, and 3.32, respectively, and the model constant k was 4.1959 × 10−11, 3.6436 × 10−11, and 4.1838 × 10−11, respectively. The velocity index n of YW3 was 2.29, 2.41, and 1.87, respectively, and the model constant k was 2.6176 × 10−7, 3.0017 × 10−7, and 3.1040 × 10−7, respectively. When the test results were compared with the numerical simulation results, the maximum error for silicon carbide was 6.59%, 7.71%, and 9.25%, respectively, and the maximum error for YW3 was 8.78%, 9.51%, and 5.97%, respectively. Finally, the erosion model of silicon carbide ceramics and YW3 was established via a large number of experiments and numerical simulations. When the target material and abrasive material are the same, it can be directly used for erosion prediction and structure optimization of natural gas equipment. Meanwhile, this paper provides a new idea for the establishment of gas–solid two-phase erosion model, and when the abrasive material and target material change, a new erosion model can be established according to the idea of this paper.

A zero-emission collaborative treatment method for brown corundum fly ash and carbide slag: Producing silicon fertilizer while recovering gallium and potassium

Brown corundum fly ash (BCFA) is a fine dust generated during the smelting process of brown corundum. It is rich in gallium and potassium, and improper handling can cause severe environmental damage. This study proposes a cyclic process of calcification leaching, carbonation precipitation, and lye regeneration for the collaborative treatment of BCFA and carbide slag. The leaching efficiencies of gallium and potassium were determined to be 94.02 % and 85.32 %, respectively, under the optimized conditions (120 min, 180 °C, Ca/Si molar ratio 0.9, KOH 10 g/L) of calcification leaching. The contents of effective SiO2 and CaO in the silicon fertilizer were measured at 34.71 wt% and 33.02 wt%, respectively. During the carbonation precipitation process, gallium and aluminum were extracted from the filtrate and achieved respective contents of 2.1429 wt% and 32.99 wt% in the resulting coprecipitate. The carbonated lye was regenerated through a causticization reaction, and after four cycles, the regenerated lye maintained a consistently high leaching efficiency for gallium and potassium. This method achieves the comprehensive utilization of BCFA and carbide slag without generating any waste residue or wastewater. Additionally, it provides a novel approach for the collaborative treatment of similar solid wastes.

Effect of aggregate type on the mechanical properties and slag resistance of Al2O3‐SiC‐C hot metal ladle bricks

AbstractAggregates are important factors that determine the performance of refractory materials. To explore the influence of aggregate types on refractory material properties, Al2O3‐SiC‐C bricks were prepared using bauxite, fused brown corundum, tabular corundum, fused white corundum, and microporous corundum with particle sizes of 5–3, 3–1, and ≤1 mm as aggregates, fused white corundum (≤.075 mm), SiC (≤.075 mm), or flake graphite (≤.15 mm) as the matrix, and a thermoset phenolic resin as the binder. Understanding the effects of the aggregate type on the mechanical properties and slag resistance of Al2O3‐SiC‐C bricks provides a theoretical basis for the selection of different aggregates during production. The results showed that the Al2O3‐SiC‐C brick had good high‐temperature mechanical properties and slag resistance when tabular corundum was used as an aggregate, owing to its high density and low content of cracks and impurity phases. When bauxite was used as an aggregate, its high‐temperature mechanical properties and slag resistance were poor, owing to its high porosity and impurity content.

A clean method for gallium recovery and the coproduction of silica-potassium compound fertilizer and zeolite F from brown corundum fly ash

Brown corundum fly ash (BCFA) is a solid waste from the brown corundum smelting process that contains abundant Ga, K, Si, and Al, but effectively extracting Ga can be challenging since most of it is located inside the particles. This study proposes a comprehensive utilization method of BCFA that combines hydrothermal leaching and alkali regeneration to extract Ga efficiently while producing silica-potassium compound fertilizer (SPCF) and zeolite F. By utilizing the transformation of phase and structure in the hydrothermal leaching process, Ga extraction is efficiently achieved. The results showed that under the conditions of 210 g/L KOH concentration, a liquidsolid ratio of 25 mL/g, and 160 °C hydrothermal leaching for 60 min, the extraction efficiencies of Ga, K, and Si were 95.91 %, 51.78 %, and 69.57 %, respectively. The solid product’s effective SiO2 and K2O contents increased to 24.72 wt% and 17.74 wt%, respectively, which can be further used as SPCF for agricultural production. The hydrothermal leaching solution was regenerated by adjusting the Al/Si molar ratio and crystalizing at 160 °C for 24 h. The Si was recovered in the form of high value-added zeolite F, with only a 3.60 % loss of Ga.

Extraction of Gallium from the Brown Corundum Dust with a One-Step Alkaline Leaching Process

Brown corundum dust, which is created during the manufacturing of brown corundum using bauxite as the raw material, is a vital carrier of gallium. To ascertain the presence of the contained gallium, the brown corundum dust was measured and characterized (XRF, XRD, ICP-OES, EPMA, SEM-EDS, etc.). Gallium was extracted from the brown corundum dust using a one-step alkali leaching process, and thermodynamic calculations were utilized to assess the viability of the leaching reactions. The effects of leaching parameters (NaOH solution concentration, leaching time, leaching temperature, solid–liquid ratio and stirring speed) on the recovery of gallium during the leaching process were investigated. A gallium recovery of 96.83% was discovered to be possible with the following parameters: 200 g/L of NaOH, 363 K for the leaching temperature, 60 min for the leaching time, 1:10 g/mL for the solid–liquid ratio, and 850 rpm for the stirring rate. Gallium extraction was negatively impacted by raising the leaching temperature above 363 K and the concentration of NaOH solution above 200 g/L due to the accelerated side reactions between Na+, K+, SiO44− and AlO2−, which led to the precipitation of aluminosilicates that absorbed gallium from the solution. The influences of leaching parameters such as the temperature, NaOH solution concentration, and solid–liquid ratio on the leaching kinetics were examined. It was demonstrated that the leaching process followed the unreacted shrinking core model, that the interfacial diffusion associated with the contacting surface area served as the controlling step, and that the apparent activation energy was 42.83 kJ/mol. It turned out that the final kinetic equation was 1/(1 − α)1/3 − 1 = 4.34 × 104 × (CNaOH)2.12 (L/S)0.43exp[−42835/(RT)] t.

Extraction of Gallium from Brown Corundum Dust by Roasting—Acid Leaching Process

Brown corundum dust is a solid waste produced during the preparation of brown corundum with bauxite as the raw material. The dust has a relatively high gallium content; therefore, it is of great value to recover the gallium from this kind of dust. In this paper, a range of analysis and characterization methods, including XRD, XRF, SEM-EDS, and EPMA, were used to determine the occurrence of gallium. It was found that gallium was mainly present in the potassium-rich phase, wrapped by amorphous silicate and the corundum phase. Roasting activation followed by an acid leaching process was proposed to extract gallium from brown corundum dust. An investigation was carried out on the effects of roasting temperature, roasting time, and additive dosage on the recovery of gallium and the evolution of the phase composition of the dust. The results show that the roasting activation of sodium carbonate was better than that of calcium oxide. After roasting at 1073 K for 40 min with a sodium carbonate dosage of 0.5 (mass ratio of sodium carbonate to dust), the phase composition changed completely to mainly consist of sodium silicate, sodium aluminosilicate, and potassium aluminosilicate. In that case, around 93% of Ga could be recovered from the roasted dust through H2SO4 (4.6 mol/L) leaching for 90 min. The leaching process was described well by the kinetic equation of k3t = 1/(1 − α)1/3 − 1, with an apparent activation energy of 16.81 kJ/mol, suggesting that the leaching rate was limited by the transfer of leaching agent across the contacting interface of the dust particles.

Microstructural evolution during H2 corrosion of Al2O3–SiO2 based refractory aggregates

Hydrogen-based direct reducing iron production (H-DRI) has caused more and more attention in metallurgical industry owing to the near-zero carbon emission. However, the strong reducibility of H2 at elevated temperature can possibly cause serious corrosion to the lining refractories of furnaces. In this study, four types of Al2O3–SiO2 based aggregates (brown corundum, bauxite, mullite and quartz) with various SiO2/Al2O3 mass ratios were utilized for the H2 corrosion test at 1673 K with a soaking time of 8 h. Based on the analysis of weight-loss ratios, phase-composition variation and reduction thermodynamics, the microstructure evolution during H2 corrosion was investigated in detail. The results indicates that the SiO2 impurity of brown corundum was partly reduced by H2 which led to the formation of rod-like or flaky intergranular grains. For bauxite, a porous structure was produced by the accumulation of rod-like or elongated grains owing to the significant reduction of intergranular silicon compounds. Nevertheless, due to the high sintering activity between the Al2O3 products from the reduction of mullite, a high densification structure was realized to effectively prevent the further H2 penetration, hence, mullite inversely obtained the better H2 corrosion resistance than bauxite in spite of its higher S/A ratio. The accumulation of SiO and H2O gases due to the high reduction rate of SiO2 led to the formation of a great deal of SiO2 fiber on the surface of quartz aggregates. The [O] provided by the phase-transformation from α-quartz to cristobalite could be partially captured by the H2 for the reduction, which caused the deterioration of corrosion. With this study, we aim to provide theoretical assistance for the refractory selection applied in hydrogen metallurgy.

Microstructure and enhanced slag resistance of Al2O3–SiC–C refractory castables with addition of ammonium metatungstate

The present study aims to clarify the influence of ammonium metatungstate (AMT) on composition, microstructural evolution and properties of Al2O3–SiC–C (ASC) refractory castables. Castables with different AMT contents were prepared using brown corundum, white corundum, silicon carbide, calcium aluminate cement, and AMT as major raw materials. The results show that hot modulus of rupture, thermal shock resistance and slag resistance were significantly improved for castables with addition of AMT (lower than 1.0 wt%), due to the optimized microstructure from the formation and development of mullite and SiC whiskers in castables. Along with the in-situ formed whiskers in pores, formation of Fe7W6 from the reaction between W ions in castables and Fe ions in the penetrated molten slag led to the enhanced slag viscosity and inhibited continuous penetration (penetration index decreased from 30.5% to 20.2%) for castables with AMT ranging from 0 to 0.5 wt%. The research of this work provides a new insight into microstructure and high-temperature properties enhancement of ASC refractory castables.

Innovative Recovery of Gallium and Zinc from Corundum Flue Dust by Ultrasound-Assisted H2SO4 Leaching

ABSTRACT Rare metal gallium is classified as a strategic material because of continued high demand, uncertain supply, and low reserves. Corundum flue dust (CFD) is generated during bauxite smelting to produce brown corundum. Gallium (Ga), Zinc (Zn), and potassium in the bauxite could be enriched with CFD through this process, so CFD is regarded as one of the potential sources of Ga and Zn. A novel that utilizes ultrasound to enhance the H2SO4 leaching efficiency of Ga and Zn from CFD was developed from CFD. The effects of ultrasound power, leaching time, sulfuric acid concentration, and leaching temperature on the leaching behavior of Ga and Zn were studied, and the corresponding kinetics model was established. It was found that the maximum Ga and Zn leaching efficiencies of 81.22% and 96.72% were obtained at optimum leaching conditions: the leaching temperature of 90°C, the leaching time of 60 min, 3 M H2SO4, the solid-to-liquid ratio of 1:5 (g/mL), and the ultrasound power of 750 W. In all cases, the leaching effect of Zn is not significantly improved by ultrasonic treatment, but the leaching efficiency of Ga has a positive effect (more than an 18% increase). Kinetic analysis shows that the leaching process of Ga and Zn were controlled by chemical reaction and diffusion, respectively. The apparent activation energy values are 20.39 kJ/mol for Ga and 13.44 kJ/mol for Zn. The characterization of the leaching residues reveals that the ultrasound effected to enable the whole block to be fractured or dispersed into fragments, accelerating the penetration of H2SO4 into the pores and cracks at the solid, which further prompts the dissolution of the encapsulated gallium and achieves the conspicuous improvement to Ga leaching efficiency.

Effect of post-processing methods on the surface quality of Ti6Al4V fabricated by laser powder bed fusion

Ti6Al4V is widely used in aerospace and medical applications, where high demands on dimensional accuracy and surface quality require the application of post-processing to achieve optimal performance. However, the surface quality of parts fabricated by LPBF is inferior due to the inherent defects of LPBF. Therefore, it is important to investigate the effect of post-processing on the surface quality of Ti6A14V parts fabricated by LPBF. In this work, the effect of post-processing methods (i.e., sandblasting, electrolytic polishing, chemical polishing, and abrasive flow polishing) on the surface quality of Ti6Al4V fabricated by laser powder bed fusion (LPBF) additive manufacturing was investigated. The changes in surface roughness and morphology of the 45° inclined square and curved pipe Ti6Al4V samples processed with post-processing were observed, and the weight and elemental changes of the parts were also analyzed. The result reveals that sandblasting, electrolytic polishing, chemical polishing, and abrasive flow polishing are all effective in improving the surface quality of Ti6Al4V parts fabricated by LPBF. The effect of sandblasting is mainly caused by sharp-edged grit driven by high-speed airflow, resulting in the lowest surface roughness and the least influence on the weight, but may contaminate the surface with residual brown corundum. Electrolytic polishing and chemical polishing achieve surface quality improvement through different corrosion patterns without changing the surface composition. The surface smoothness of parts processed with chemical polishing is the best, while the weight loss rate of the sample processed with electrolytic polishing is the most at about 7.47%. Abrasive flow polishing presents a remarkable effect on polishing the internal surface of the Ti6Al4V sample by the extrusion scratching, extrusion deformation, and micro-cutting effects of abrasive on the surface. The findings can provide important engineering references for the post-processing of precision Ti6Al4V parts fabricated by LPBF and further promote the engineering applications of Ti6Al4V parts.

Investigation on Application Prospect of Refractories for Hydrogen Metallurgy: The Enlightenment from the Reaction between Commercial Brown Corundum and Hydrogen.

Hydrogenous environments put forward new requirements to refractories for the hydrogen metallurgy field. The temperature and impurities in refractories played an important role in stability. A commercial brown corundum with many impurities was adopted as a raw material, thermodynamic calculations and reduction experiments of the brown corundum by high-purity hydrogen (99.99%) were accepted to investigate the stability of the oxides. The weight loss and mass fraction were tested to estimate the stability of the oxides in the brown corundum. XRD and SEM were used to analyze the mineral compositions and microstructures. The results showed that: the thermodynamic stability of the oxides in the brown corundum under high-purity hydrogen was in the order of Al2O3 > CaO > MgO > SiO2 > TiO2 > Fe2O3 at temperatures lower than 1400 °C. Obvious weight loss appeared after heating at 1400 °C for 8 h. The content of CaO did not decline after reduction even at 1800 °C, owing to the formation of hibonite (CaAl12O19), high-purity Al2O3 and CaAl12O19 -based refractories had the prospect for lining materials in the hydrogen metallurgy field, owing to their excellent chemical stability under hydrogenous environments.

Effective thermal conductivity and thermal cycling stability of solid particles for sCO2 CSP applications

A supercritical CO2 (sCO2) Brayton cycle solar power system based on solid particle thermal energy storage is proposed to enhance the efficiency of concentrated solar power (CSP). The effective thermal conductivity and thermal cycling stability of solid particles are crucial for sCO2 CSP applications. Some natural and artificial solid particles, such as black silicon carbide, green silicon carbide, white corundum, brown corundum, brown ceramsite sand, garnet, river sand and desert sand are considered as potential thermal energy storage medium due to its low cost and easy availability in large quantities. However, there are few studies about the effective thermal conductivity and stability of these solid particles after thermal cycling tests. In this study, the effective thermal conductivity of these solid particles was measured by the hot wire method. Particularly, the effective thermal conductivity of black silicon carbide and green silicon carbide was measured by modified hot wire method. In addition, the changes of mass, real density, bulk density, void fraction and mean diameter of the above-mentioned solid particles after 100 times thermal cycling tests were also recorded to analyze thermal cycling stability. Based on the results of all the above tests, green silicon carbide exhibits high effective thermal conductivity and good thermal cycling stability, which presents a great potential as a thermal energy storage medium.

Recovery of K by NH4HSO4 low-temperature roasting from brown corundum Fly Ash

Brown corundum dust ash(BCFA) is an industrial solid waste from the brown corundum production process. The alkali metal is a key factor limiting its comprehensive use. Currently, BCFA is mainly stockpiled and occupies a large amount of land. Its fine particles are easy to cause air pollution. The addition of NH4HSO4 allows for the effective extraction of K from BCFA and the efficient use of BCFA. Under optimum conditions: NH4HSO4 to BCFA mass ratio of 1.2:1, the roasting temperature of 240 °C, roasting time of 2 h, water leaching time of 90 min, water leaching temperature of 65 °C water leaching liquid to solid ratio of 3:1, the leaching rate of K from BCFA reached 97%. The leachate was crystallised by evaporation to obtain K, N compound fertiliser for agricultural use. The leaching residue is mainly Al and Si, which can be used for the preparation of refractory materials, aluminium and silicon molecular sieves, construction materials and other raw materials.

The study of heat-mass transfer characteristics and multi-objective optimization on electric arc furnace

It is crucial to reveal the energy conversion and heat and mass transfer characteristics in the electric arc furnaces (EAFs). In this paper, a transient mathematical model was built to adequately capture the distribution of multi-physical fields in EAF. The numerical modeling method was verified against brown corundum smelting experiment data. In addition, the influence on the brawn corundum smelting process of the typical operating parameters has been examined, and the major problems which limit the performance improvement of smelting were analyzed. Moreover, four indicators were proposed to comprehensively evaluate the EAF performance, consisting of liquid volume fraction β, energy efficiency η, temperature rise index ς, and temperature uniformity index ξ. Furthermore, the optimal combination of operating parameters was selected automatically based on the back propagation (BP) neural network predicting model and non-domestic sorting genetic algorithm II (NSGA-II). The results showed that the local overheating phenomenon is serious and that homogenizing the energy distribution in the furnace is the key to improving the melting performance. Increasing electrode immersion and voltage can significantly increase the rate of heat and mass transfer. In the case of ψ = 0.75, υ = 0.6, when χ is increased from 0.2 to 0.6, τmax is shortened by 13.3% and ηmax is increased by 12.0%. While with ψ = 0.75 and χ = 0.4, τmax is reduced by 36.0% when υ increases from 0.2 to 1.0, but ηmax is also decreased by 7.0%. It was found that decreasing the height diameter ratio will improve the overall EAF smelting performance, but it also increases the area of heat loss. In the case of χ = 0.4, υ = 0.6, ξave and ηmax improved by 3.1 and 14.5%, respectively, when ψ decreases from 1.0 to 0.5. The EAF performances are considerably enhanced in comparison to the operating basic parameters (ψ = 0.75, χ = 0.4 and υ = 0.6), subject to optimal operation parameters (ψ = 0.61, χ = 0.59 and υ = 0.59). In this case, τmax and ςmax reduced by 6.2 and 4.1%, respectively, while ηmax and ξave increased by 6.8 and 1.0%, respectively.

High-temperature performance in Al2O3–Cr2O3 refractories: Effect of Al2TiO5

In an effort to reduce resource consumption through recycling, Al 2 O 3 –Cr 2 O 3 refractories were prepared by sintering a mixture of brown corundum and recycled aluminum chromium slag at 1600 °C. To elucidate the significance of TiO 2 in refractory, the effect of TiO 2 addition on the room- and high-temperature mechanical properties of these refractories was investigated. The observed stepwise progression in the high-temperature mechanical properties of the specimens was explained by considering the results of thermodynamic simulations, as well as those of phase and microstructural analyses. This behavior was ascribed to the generation of Al 2 TiO 5 in the matrix of the specimens. Moreover, the addition of TiO 2 increased the content of undecomposed Al 2 TiO 5 , and it was accompanied by the appearance of several microcracks in the matrix portion. The high temperatures caused the integration of microcracks and counteracted the thermal stresses in the specimens, which considerably improved the high-temperature mechanical properties and the thermal shock resistance.

Evaluation of remelting low-fluxing ferrotitanium slag as a potential refractory raw material: Thermal characteristics and stability

To effectively promote the utilization of metallurgical waste slag, studies on the characteristics and stability of waste slag are essential for waste reuse. Ferrotitanium slag is a byproduct of smelting ferrotitanium with thermite reduction. Low-fluxing ferrotitanium slag (LFS) is the main type of dumping slags produced by ferrotitanium smelting. In this study, an electric arc furnace was used to prepare remelting LFS (RLFS) for homogenization and impurity removal. The characteristics and thermal stability of RLFS as a refractory raw material were characterized. The thermal stability of RLFS was tested under different working conditions. A phase-structure transition mechanism of RLFS particles was established according to the thermal stability test and thermodynamic calculations. The Al2O3 content in RLFS exceeded 80%, and RLFS had lower thermal conductivity than brown corundum, but a similar thermal expansion coefficient. The results show that RLFS is a suitable substitute for corundum raw material; the thermal stability test results show that RLFS was susceptible to crack propagation in an oxidizing environment above 1280 °C. The findings of this research provide suggestions for the utilization of RLFS to improve the application stability of refractory products using recycled raw materials.

Improved oxidation resistance of Al2O3–SiC–C castables by introducing a small amount of andalusite fine powder

AbstractIn our previous study, high amounts of andalusite aggregates (about 19%) were used to improve the oxidation resistance of Al2O3–SiC–C castables, attributed to the transformation of andalusite. However, for andalusite aggregates with large particle size, only a small part of the silica‐rich glass phase (about 20%) is extruded onto the surface of the particles to block the pores. Theoretically, the smaller particle size promotes the conversion of andalusite, and more silica‐rich glass phase would be extruded to the particle surface to block the pores in the castables, which is speculated to favor the enhancement of the oxidation resistance of the castables. Therefore, in this work, andalusite fine powder (≤0.055 mm) was employed to substitute the same‐weight proportion of fused brown corundum fine powder in the castables. The results demonstrate that a small amount of andalusite fine powder can achieve the similar antioxidation enhancement compared with high addition content of andalusite aggregate. And the properties of castables fired at different temperatures proved that the thermal decomposition of andalusite fine powder into silica‐rich glass and mullite is the key reason of elevated oxidation resistance as well as the improvement of strength and thermal shock stability.

A Method to Simulate the Migration and Accumulation of Hydrocarbon with Analogue Modeling

Subsurface migration and accumulation of oil and gas have interested researchers for a long time, but these processes may occur over very long geological periods and are difficult to observe directly, so experimental simulations are warranted. In this study, an experimental method was developed to model hydrocarbon migration in the subsurface structure. Oil migration was simulated in a sandbox model, and industrial CT scanning was used to observe both the internal geometry of the model and the oil migration pathways. In the sandbox model, a NaI solution was used to simulate water, white oil was used to simulate hydrocarbon, and fine quartz sand, glass bead, silica powder, and brown corundum were chosen to represent brittle crust, based on suitable material parameters. A NaI-saturated layered sandbox model was constructed with an along-strike basal discontinuity, which during compression allowed a simple anticline with doubly verging reverse faults to form. Oil was then released continuously at a low rate from an orifice under one limb of the anticline. Initially, the oil migrated vertically through the fault zone until it reached the top of the fault zone; it then migrated laterally along the core of the anticline, saturating a model reservoir by buoyancy and capillary force. This experimental analog helps to explain hydrocarbon migration and accumulation within the Anjihai and Santai anticlines in northwest China.