Use of fireclay dust from rotary furnaces

Conclusions Dust removed by electric filters from the gases of rotary furnaces can be used for the preparation of firebrick articles. The composition of the bodies recommended is as follows; for standard brick 45% grog, 35% dust and 20% kaolin; for lightweight insulating brick 30% dust, 35% thermal-anthracite, 17.5% kaolin, and 17.5% Chasov-Yar clay.With combined firing into grog of kaolin and dust in the briquette it is possible to add not more than 20% dust; with an increase in the content the water absorption of the grog increases.When designing refractory factories in the complex of which we introduce rotary furnaces with electric filters, it is necessary to specify equipment for transporting dust into the body-preparation section with the aim of using it.The use of dust from rotary furnaces for the production of refractories will be a useful innovation for refractory workers in completing the directives of the 23rd congress of the party aimed at improving use of raw materials.The work was shared by L. S. Shchetina and S. D. Svidlo.     

Investigation of fireclay dust from rotary furnaces

Conclusions Dust removed during the firing of clay raw materials into grog in rotary furnaces consists mainly of dehydrated material with a low plasticity and bonding capacity.The temperature of vitrification of the dust is higher than for the original raw materials. Therefore, with the use of dust for firing into grog it is necessary to densify it before firing (for example briquetting) and to increase the temperature in the kiln.     

Dense Mullite from Attrition-Milled Kyanite and Aluminum Metal

Dense mullite was produced through the reaction and sintering of an attrition-milled mixture of kyanite (Al₂O₃·SiO₂) and aluminum metal. Kyanite and aluminum were attrition-milled then slowly heated at 1°3C/min to 1100°3C in air, and rapidly heated to 1600°3C and held for 1 h. During heating, the aluminum metal is oxidized first in the solid state and then as a liquid. The attrition-milled kyanite decomposes yielding mullite and rejecting silica, which then reacts with the alumina formed from oxidation of the aluminum. Expansion from the aluminum oxidation and kyanite decomposition partially compensates for the normal sintering shrinkage. A dense, fine-grain-size mullite results.     

Development of fireclay aluminosilicate refractory from lithomargic clay deposits

Lithomargic clay until now has not been utilised to produce refractory bodies due to its low plasticity. In this work, the development and evaluation of fireclay refractory material produced from lithomargic clay deposit has been studied by addition of clay binder. Three formulations were prepared by mixing, semi-dry moulding, drying and firing at temperatures ranging from 1200 to 1400 °C. The fired samples were investigated to determine their physical properties such as bulk density, apparent porosity, linear firing shrinkage, and cold crushing strength. The chemical and mineralogical compositions were also determined. The results show that the linear firing shrinkage values were within limits acceptable for refractory clays. The cold crushing strength increases as temperature increased to 1400 °C. Cold crushing strength increased with increasing binder content. The increase of the highly refractory phases (cristobalite and mullite) and the densification of the bricks due to the presence of fluxing agents were responsible for the high cold crushing strength values. The investigated properties indicate that lithomargic clay underlying bauxite deposits could be used to produce fire clay aluminosilicate refractories.     

采用蓝晶石制造堇青石陶瓷的可行性研究

对于采用蓝晶石精矿和传统的氧化铝原料高岭石制造的堇青石陶瓷的矿物形成过程和性能进行了对比研究。查明,在原料配料进行烧成的开始阶段相转化的差异对由堇青石及少量莫来石和石英组成的最终产物的矿物组成并无影响。由蓝晶石制造的堇青石陶瓷的物理性能与由高岭石制造的该类陶瓷类似,但其收缩率稍小些。     

Investigation on Synthesis of Sintered Mullite from Low-medium Grade Kyanite

Sintered mullite is prepared by kyanite powder with Al_2O_3 content of 45% and 50%(Yinshan, Nanyang City, China),and the industrial alumina is added to control the chemical composition. The different series of sintered mullite according to the Al_2O_3 content(45%-70%) are designed. The raw materials are mixed and compacted, and then sintered at different temperatures. Physical properties, phase composition, microstructure and refractoriness under load of the synthesized samples are characterized by physical property test, XRD, SEM and RUL test, in order to confirm the quality of sintering and the relationship between temperature and mullitization reaction. The results show that the sintered mullite from low-medium grade kyanite has well developed mullite crystals and a continuous staggered network structure is formed, which has a significant contribution to increasing the high temperature performance of mullite.     

特种低气孔率粘土砖的研制

以特级焦宝石和合成其来石为主要原料并加入适量添加剂，采用四级配料、共磨细粉等工艺，研制出气孔率为８．７％、体积密度为２．２ｇ／ｃｍ３、０．２ＭＰａ荷重软化温度（Ｔ０．６）为１５４０℃低气孔率粘土砖，该砖具有较高的抗碱蒸汽侵蚀性。     

Fabrication of low to high duty fireclay refractory bricks from lignite fly ash

The development of refractory bricks made of new materials has recently drawn a lot of interest to address sustainability issues. So, in this study, the recycling of lignite fly ash produced by coal-fired thermal power plants has been investigated to make fireclay refractory bricks. The lignite fly ash and ball clay are the primary raw materials characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray fluorescence (XRF), and differential thermal analysis (DTA). The samples were prepared using a uniaxial hydraulic press, and firing was done in the range of 1000–1200 °C for 2 h. The fired samples were characterized in terms of chemical composition, mineralogical phase, and microstructural using different characterization tools such as XRF, XRD, and SEM. The physical, mechanical, and thermal properties such as linear firing shrinkage, apparent porosity (AP), bulk density (BD), cold crushing strength (CCS), cold modulus of rupture (CMOR), and thermal conductivity of the fired sample were investigated. The linear firing shrinkage, AP, BD, and CCS values were achieved estimated to be 5.32%, 2.10 g m/cc, 15%, and 52 MPa, respectively. The SEM analysis shows dense, rod-like mullite structure and interlocking microstructure of the fired samples. The results were well matched with ASTM standards and commercially available products. So, this promising result indicates lignite fly ash can be used as a potential raw material to produce fireclay refractory bricks.     

Process-water residues in fireclay and magnesia refractory production

Conclusions Particle size analyses of process water residues from fireclay and magnesia refractory production enable settlement rates to be established within water cleaning plant.From wet volume tests on residues it is possible to work out sludge volumes and cleaning cycle times for settlement plantl.Residues consisting of grog, magnesite, chromite, magnesite-chromite mixtures, and grog-clay mixtures with seven-tenths grog or over, should be removed mechanically from a horizontal settling tank after 1 day or longer, e.g., with a bucket crane or similar mechanism. A clay residue should be pumped out, but if it stands for 2 days or more it may be dug out.A coagulated residue of clay or a clay-grog mixture with seven tenths clay or more should be pumped out, but a 73 clay-grog mixture can be removed mechanically after settling for 3 days.Coagulated grog, magnesite, or chromite residues can be moved hydraulically for the first day, but if they stand longer they must be moved mechanically. If sludge is to be moved mechanically from a settling tank the clean water over it must be removed first, and appropriate equipment must be allowed for. If a sludge is to be removed hydraulically it must first be stirred up in some way.Translated from Ogneupory, No. 2, pp. 11–16, February, 1969.     

煅烧蓝晶石制品的研究

用两个温度下煅烧后的蓝晶石为原料,研制烧结蓝晶石制品,对其烧成温度、高温性能、抗热稳定和显微结构作了研究。结果表明：合适的制品烧成温度为1400℃,添加锆英砂或焦宝石可以提高其热稳定性,可望成为较好的窑具材料。     

China Standards on Refractories Kyanite Sillimanite and Andalusite

1 Scope This standard specifies classification, symbol, brand,technical requirements, test methods, inspection rules,packing, marking and quality certificate of concentrated kyanite, sillimanite and andalusite.