2022 Vol.31, No.3 Date of publication: 15 July 2022

Production and Running Status of China’s Refractories and Main Downstream Industries in 2021

LI Yongquan

2022 Vol.31 (3): 1-4. doi:10.19691/j.cnki.1004-4493.2022.03.001

Application of Mullite Composite Lining Plates in Rotary Coke Tanks for Coke Dry Quenching Equipment

To reduce the burning loss and the spalling and to improve energy efficiency, the mullite composite lining plates were used to replace cast steel or alloy lining in rotary coke tanks for coke dry quenching equipment. The results show that: the dense mullite composite lining plate in the cone part has the density of 2.20 g·cm^-3 and the wear test,s volume loss of 4.08 cm³, and the light weight mullite composite lining plate in the straight cylinder part has the density of 1.95 g·cm^-3 and the wear test,s volume loss of 17.6 cm3. After using, there is no shrinkage gap, no burn loss or holes in the plates, indicating good sealing of the mullite composite lining plates. The lining plate for the cone part has low burning loss, without spalling for more than half a year. The outer surface temperature of coke tanks adopting the cast steel or the alloy lining is 480 to 570 ℃, while that of the ones adopting mullite composite lining plates is 120 to 170 ℃, showing a largely improved insulating property. Adopting mullite composite lining plates on the basis of the current coke tank cage, the lining plates can be timely treated and wholly replaced, improving the service life and reducing the maintenance workload.

XU Guotao, SHENG Junbo, FENG Qiang, TU Hongbing, WANG Dachun, LIU Li, ZHANG Yanwei, ZHANG Honglei

2022 Vol.31 (3): 5-8. doi:10.19691/j.cnki.1004-4493.2022.03.002

Effect of Submicron SiO₂ Powder Addition on Properties of Cement Free Iron Trough Castables

A new cement free iron trough castable was prepared with dense corundum and silicon carbide as the main raw materials and submicron SiO2 powder (d50=0.242 μm, SiO2=99.9 mass%) as the binder. The effect of the submicron SiO2 powder addition (3%, 4%, 5%, 6%, 7%, 8%, and 9%, by mass, respectively) on the properties of the prepared castables was studied. The working mechanism of submicron SiO2 powder was analyzed from the perspective of the particle size distribution and infrared absorption spectrum. The results show that: (1) cement free iron trough castables can be prepared using submicron SiO2 powder alone as the binder; (2) compared with traditional castables, the cement free castables have made a breakthrough in the water addition and hot modulus of rupture. The optimal submicron SiO2 powder addition is 4%-6%.

CHENG Shuiming, CHEN Jinfeng, WEI Jianxiu, CAI Wei, ZHAO Huizhong

2022 Vol.31 (3): 9-13. doi:10.19691/j.cnki.1004-4493.2022.03.003

Phase Reconstruction and Microstructure Evolution of Magnesia-carbon Refractories at High Temperatures in Nitrogen

Magnesia-carbon refractories were prepared using fused magnesia, flake graphite and metal aluminum powder as starting materials, phenolic resin as the binder, heat-treating at 1 300-1 600 ℃ in nitrogen atmosphere. The phase reconstruction and the microstructure evolution of the obtained magnesia-carbon refractories were analyzed. The formation mechanisms of magnesia crystals with different morphologies by chemical vapor deposition were revealed. The results show that at 1 300-1 500 ℃, the non-oxides within the specimens are aluminum carbide (Al4C3), aluminum nitride (AlN) and magnesium aluminum nitride (Mg3AlnNn+2, n=2 or 3); at 1 600 ℃, the diffraction characteristic peak intensity of Al4C3 and AlN decreases sharply, and sharp diffraction characteristic peaks of nitrogen aluminum carbide (Al7C3N3) appear. Mg(g) is produced by the aluminothermic reduction and carbothermal reduction of magnesia. On the surface of the specimens, Mg(g) reacts with oxygen to form MgO whiskers. Inside the specimens, Mg(g) and O2(g) undergo a CVD chemical deposition reaction to form cubic MgO crystals. There is a phase relationship between flake AlN and flake Mg3AlnNn+2, and they are so associated with each other that the morphology is difficult to distinguish.

YAN Mingwei, YANG Yumin, TONG Shanghao, ZHANG Jiayu, SUN Guangchao, LIU Kaiqi

2022 Vol.31 (3): 14-23. doi:10.19691/j.cnki.1004-4493.2022.03.004

Effect of Calcium Aluminate Cement Addition on Properties of Al₂O₃-SiO₂ Based Gunning Mixes

Al2O3-SiO2 based gunning mixes were prepared with electric porcelain waste, silica fume, bauxite, quartz powder, and calcium aluminate cement (CAC) of different additions as raw materials firing at different temperatures to research the effect of the CAC addition on their phase change and properties. The results show that: from theoretical analysis of the phase diagram, with the CAC addition increasing from 8% to 14%, anorthite increases from 40.0% to 77.7%, by mass. With the rising CAC addition, the permanent linear change on heating of specimens increases; for the specimens dried at 110 ℃ or hot-treated at 1 000 ℃, the bulk density and the mechanical properties increase, and the apparent porosity decreases; and for those hot-treated at 1 300 ℃, the bulk density and the mechanical properties firstly increase, and then decrease, while the apparent porosity shows an opposite trend. Taking into account the phases at high temperatures and the properties, the optimal CAC addition of Al2O3-SiO2 based gunning mixes is 12%.

ZHOU Junjie, HAN Junhua

2022 Vol.31 (3): 24-27. doi:10.19691/j.cnki.1004-4493.2022.03.005

Preparation of ZrO₂ Fibers by Template Impregnation Method

Viscose fiber templates (15 cm×15 cm×1 cm) were put into ZrOCl2 solutions of different concentrations (1, 2 and 3 mol·L-1) and impregnated at different temperatures (20, 40 and 60 ℃) for 20 h. After washing, centrifugation and drying, ZrO2 fiber precursors were obtained. ZrO2 fibers were prepared by heat treatment of the precursors at different temperatures (600, 800, 1 000 and 1 200 ℃) for 2 h. The effects of the impregnation temperature, the impregnation solution concentration and the heat treatment temperature on the microstructure and the phase composition of the ZrO2 fibers were studied. The results show that with the increase of the impregnation temperature from 20 ℃ to 60 ℃ and the impregnation solution concentration increase from 1 mol·L-1 to 3 mol·L-1, the microstructure of fiber cross section changes from flat to cylindrical, and the average fiber diameter increases, indicating that the increase of the impregnation solution concentration and the impregnation temperature is beneficial to increasing the adsorption capacity of Zr4+ on viscose fiber templates. After heat treatment, ZrO2 fiber mainly exists in the form of monoclinic ZrO2. With the increase of the heat treatment temperature, the grains in ZrO2 fibers become larger and the crystallinity degree increases, meanwhile the fiber surface undergoes a transition from smooth to small grains and then to cracks.

ZHANG Lei, YAN Senwang, LI Hongyu, SUN Xiaofei, WANG Gang, ZHANG Yifan, WANG Shouye

2022 Vol.31 (3): 28-33. doi:10.19691/j.cnki.1004-4493.2022.03.006

Preparation of Magnesia Insulation Materials by Walnut Shell Powder Impregnated with Silica Sol

In order to reduce the thermal energy loss of high temperature kilns and furnaces and lower the surface temperature of the kiln body, magnesia insulation materials were prepared using self-made magnesia porous aggregates (using high purity magnesia powder as starting material and potassium oleate as the foaming agent), middle grade magnesia powder, calcium aluminate cement, and SiO2 micropowder as starting materials, introducing walnut shell powder impregnated with silica sol (short for Sws) as a pore-forming agent. The effects of the Sws addition (0, 10%, 15%, and 20%, by mass) and the sintering temperature (1 300, 1 350, 1 400, and 1 480 ℃) on the properties of magnesia insulation materials were studied. The results show that (1) for the specimens fired at 1 480 ℃, when the Sws addition is 10%, the cold compressive strength is 22 MPa; when the Sws addition is 20%, the thermal conductivity is 0.368 W·m-1·K-1 (350 ℃); (2) nano-silica in the silica sol reacts with MgO in the matrix to form forsterite, which encapsulates the pores volatilized from the walnut shell powder and forms closed pores.

JIAO Changfa, LI Guohua, KANG Chi

2022 Vol.31 (3): 34-37. doi:10.19691/j.cnki.1004-4493.2022.03.007

Determination of Chlorine Content in Zirconia Containing Special Refractories

In this study, zirconia containing refractory samples were decomposed by dilute nitric acid. The chloride ion content in the leaching solution was determined by thiocyanate spectrophotometry. The influences of the leaching method of the sample pretreatment and the coloration condition of the solution to be tested on the test results were studied. The precision test was carried out and the results were compared with those determined by ion chromatography. The results showed that the zirconia containing refractories were boiled with dilute nitric acid to obtain the test solution. The influence of zirconium hydrolysis on determination was removed by centrifugation. The chlorine contents in zirconia containing refractories determined by spectrophotometry have low relative standard deviation (RSD), showing slight testing difference with those determined by ion chromatograghy.

XU Xiaoying, CAO Haijie, DUAN Xueke, LEI Xiaoyu

2022 Vol.31 (3): 38-40. doi:10.19691/j.cnki.1004-4493.2022.03.008

China's Refractories

Production and Running Status of China’s Refractories and Main Downstream Industries in 2021

Application of Mullite Composite Lining Plates in Rotary Coke Tanks for Coke Dry Quenching Equipment

Effect of Submicron SiO₂ Powder Addition on Properties of Cement Free Iron Trough Castables

Phase Reconstruction and Microstructure Evolution of Magnesia-carbon Refractories at High Temperatures in Nitrogen

Effect of Calcium Aluminate Cement Addition on Properties of Al₂O₃-SiO₂ Based Gunning Mixes

Preparation of ZrO₂ Fibers by Template Impregnation Method

Preparation of Magnesia Insulation Materials by Walnut Shell Powder Impregnated with Silica Sol

Determination of Chlorine Content in Zirconia Containing Special Refractories

Unified International Technical Conference on Refractories (UNITECR)

18^th China's Refractories Youth Symposium Held in Changsha, China

First Youth Editorial Committee Meeting of Naihuo Cailiao and China's Refractories Held

Abstracts Selectedfrom NaihuoCailiao (Refractories)-A Bimonthly in Chinese

Downloads More

Paper Template

References instruction of China’s Refractories

Journal News More

Links More