Dense Shaped Refractory Products——Determination of Bulk Density, Apparent Porosity and True Porosity

1 Scope This standard specifies the definition, prineiple, apparatus and materials, procedure, expression of resuits and test report of determination of bulk density, apparent porosity and true porosity of dense shaped refractory products.

Effect of Coal Source on Quality of Bauxite for Refractories Applications

Bauxite from Qingzhen is calcined for refractories :tpplications. Three fuel sources with different amounts of residual ash and ferric oxide were used for bauxite calei- 'zation in a rotary kiln. It is found the quality, inclu- ling the content of ferric oxide, bulk density, apparent porosity and water absorption, of the bauxite is highly itfluenced by the fitel source of rotary kiln. In essence, the effect of fuel on the quality of bauxite is attributed to !he amount of ferric oxide introduced by the fitel. Intro- duction of a modest quantity of ferric oxide is beneficial for promoting the densification of bauxite.

Effect of La2O3 Addition on Sintering Properties of Magnesia

Light burned magnesia powders with different particle sizes were obtained by calcining crystalline magnesite.Sintered magnesia was prepared from the light burned magnesia powders by adding different amounts of La2O3.The effect of the La2O3 addition on the densification of magnesia was studied.The results show that the densification of sintered magnesia can be promoted both by reducing the particle size of the light burned powder and by adding small amounts of La2O3.The effect of the La2O3 addition is more significant:the maximum bulk density of the sintered magnesia can reach 3.49 g·cm-3 and the apparent porosity can be reduced to 0.33%.During sintering,Ca2+from the impurities enters La2O3 lattices,causing lattice distortion of La2O3 thus promoting the formation of La4.67(SiO4)3O phase and CaLa4(SiO4)3O phase,which fill the pores between the MgO grains and promote the densification of sintered magnesia.

Effect of Heredity of Raw Materials on Properties of Alumina-magnesia Refractory Castables

Regarding the morphology of alumina,effect of the heredity of raw materials on properties of aluminamagnesia refractory castables was investigated by adding platelet alumina as the specific template.In-situ spinel platelet formed derived from platelet alumina.By comparing phase evolution,apparent porosity,bulk density,permanent linear expansion and strength,it was demonstrated that the utilization of the microstructures＇ heredity of platelet alumina was a new alternative for controlling properties of alumina-magnesia refractory castables.

Abstracts Selected from Naihuo Cailiao (Refractories)——A Chinese Language Bimonthly

Volume 50,Number 3,2016 Preparation and properties of infrared ceramics with high infrared emissivity/Yang Jinping,Wang Chunmei,Wei Hengyong,Chen Yang//Naihuo Cailiao.-2016,50（4）：241Abstract：This work aims at preparing ceramics with high infrared emissivity.Analytically pure Fe_2O_3,Co_2O_3,CuO,MnCO_3,Bi_2O_3,MgCO_3,talcum（≤0.1mm industrially pure）,kaolin clays,high temperature solid state synthesized spinel type ferrite.

State of the art of lightweight aggregates used in lightweight refractories for working lining of high-temperature furnaces

Lightweight refractories for the working lining of high-temperature furnaces play an important role in the smelting of advanced steels and superalloys.To prepare lightweight refractories for the working lining of high-temperature furnaces,the synthesis of lightweight aggregates is the basis.Recently,the research on the synthesis of lightweight aggregates with high service temperature,low thermal conductivity,high strength,and good slag resistance has received widespread attention.The available literature on the synthesis of lightweight aggregates was summarized,including corundum,mullite,mullite-corundum,spinel,corundum-spinel,cordierite,cordierite-mullite,calcium hexaluminate,corundum-calcium hexaluminate,bauxite,magnesia,magnesia-based,and forsterite-based aggregates.Finally,the future development trend of lightweight aggregates was proposed.

Preparation of steel slag porous sound-absorbing material using coal powder as pore former

The aim of the study was to prepare a porous sound-absorbing material using steel slag and fly ash as the main raw material, with coal powder and sodium silicate used as a pore former and binder respectively. The influence of the experimental conditions such as the ratio of fly ash, sintering temperature, sintering time, and porosity regulation on the performance of the porous sound-absorbing material was investigated. The results showed that the specimens prepared by this method had high sound absorption performance and good mechanical properties, and the noise reduction coefficient and compressive strength could reach 0.50 and 6.5 MPa, respectively. The compressive strength increased when the dosage of fly ash and sintering temperature were raised. The noise reduction coefficient decreased with increasing ratio of fly ash and reducing pore former, and first increased and then decreased with the increase of sintering temperature and time. The optimum preparation conditions for the porous sound-absorbing material were a proportion of fly ash of 50%（wt.%）, percentage of coal powder of 30%（wt.%）, sintering temperature of 1130°C,and sintering time of 6.0 hr, which were determined by analyzing the properties of the sound-absorbing material.