Development of novel refractory ceramic continuous fibers of fly ash and comparison of mechanical properties with those of E-glass fibers using the Weibull distribution

This study aimed to develop manufacturing technology for high-strength refractory ceramic fibers (RCFs) using fly ash, which is a highly promising material for the exterior and thermal insulation industry. The technology also contributes to reducing the environmental pollution caused by landfilling fly ash after coal is burned. Fly ash discharged from a thermal power plant, which had aluminosilicate chemical compositions, was used as the main material. As auxiliary materials, basalt, anorthite, feldspar, dolomite, and calcite were used to adjust the melt flowability, and frit, silica sand, and burr stone were used to lower the melting temperature. Moreover, the development of aluminosilicate fly ash fiber has the advantages of lower cost for raw materials and processing. Fly ash and natural rocks are inexpensive, and most of all, unlike the case for glass fiber production, the high cost of B₂O₃ is not a necessary expense. Fly ash is retrieved in powder form, which is advantageous compared to the starting materials for glass; the grinding process of raw materials can be skipped. From the fibrilization index calculation, we showed that the spinnability was influenced by the chemical composition of the salt-forming oxides in the fly ash compounds. We also found a correlation between the winding speed and the fiber diameter. The mechanical properties of a series of fly ash fibers were assessed by the Weibull distribution and then compared with those of the E-glass fibers that were melt-spun under an analogous condition.     

六铝酸钙材料及其在铝工业炉中的应用

较系统地介绍了六铝酸钙材料的一些独特优良性能以及六铝酸钙的合成及其制品,同时还阐述了六铝酸钙材料在铝工业中的应用.     

上引法生产线铜熔化炉耐火材料

介绍了引进无氧铜杆上引法生产线中１２ｔ有芯感应炉炉衬耐火０材料材料的选用和砌筑工艺;运行状况良好,整个材料费仅为进口同类材料的１／５～１／８;该熔铜炉炉衬的成功砌筑和使用,为其他同类炉子炉衬耐火材料的国产化提供了范例。     

近年我国复杂难选铁矿石选矿技术进展

我国铁矿资源长期紧缺已是不争的事实,合理开发利用复杂难选铁矿石资源对于缓解我国铁矿石供求矛盾及保障我国钢铁工业经济的安全具有重大意义。对我国复杂难选铁矿石选矿技术进展进行了综述,同时针对我国复杂难选铁矿石的性质特点及存在的问题,提出了下一步的研究方向。     

甘肃某难处理金精矿的预处理与生产实践

针对甘肃某含砷、含锑难处理金精矿,采用"浸锑—两段焙烧"脱锑、脱砷,然后进行氰化提金的流程。考察了浸锑条件和焙烧条件对脱锑、脱砷的影响。试验结果表明,在优化后条件下,含砷、含锑难处理金精矿的脱砷、脱锑率分别达到78.59%、93.8%,然后通过氰化浸出工艺提金,金的回收率可从48%提高到92.3%。     

低品位复杂多金属矿中黑白钨矿分选试验研究

对低品位复杂多金属矿脱除硫化矿和磁铁矿后的尾矿,采用强磁选分组,磁性产品及非磁性产品分别进行黑钨浮选和白钨浮选,白钨浮选精矿加温精选和酸浸的工艺流程,最终得到含WO372.59%的白钨精矿,回收率30.15%,含WO355.36%的黑钨精矿,回收率47.81%.      

青海某难选金锑矿石综合回收选矿试验研究

青海某金矿石属少硫化物石英斑岩型微细浸染状金矿石,金粒度小于0.005mm,主要包裹在硅酸盐、碳酸盐以及含砷黄铁矿等硫化物中,有害元素砷含量较高,属于难选冶矿石。针对该矿石性质进行了原矿直接氰化浸金,原矿氧化焙烧-氰化浸金及浮选等工艺流程的对比试验。结果表明,锑金优先浮选-金精矿抑砷浮选是处理该矿较为合理的工艺。锑、金分别经过两次粗选、两次扫选、两次精选,可获得锑品位为57.00%,锑回收率为62.70%的锑精矿,金品位为32.35g/t,金回收率为73.28%的金精矿。      

Chelants to inhibit magnesia (MgO) hydration

Magnesium oxide (MgO) presents excellent refractoriness and high resistance to basic slag. However, in the presence of water, MgO undergoes an expansive hydration reaction generating Mg(OH)₂, which can lead to swelling and cracking. In this work, additives called chelants were added to dead burnt magnesia suspensions in order to check their effectiveness as inhibitors of the magnesium oxide hydration. Zeta potential, ionic conductivity, pH and temperature measurements were used to provide information related to the magnesia surface and the chelant adsorption. Assessment of the hydration degree and volumetric expansion provided indications of the amount of Mg(OH)₂ formed, as well as its likelihood to damage the ceramic bodies. The results showed that citric acid can inhibit hydration to some extent, whereas ethylenediamine tetraacetic acid (EDTA) was more effective in preventing volume expansion. An addition of 0.3 wt% of these chelants was sufficient to prevent hydration and avoid expansion.     

Preparation and characterisation of self-flowing refractory material containing 971U type microsilica

Abstract

A newer composition of self-flowing low cement brown fused alumina castable containing 971U type microsilica was developed. Optimum flow characteristics were achieved using water addition of 4·6?wt-%. This batch was sintered at different firing temperatures up to 1500°C. To understand the effect of both firing temperatures and corresponding phases, the present castable was characterised in terms of X-ray diffraction, scanning electron microscopy, bulk density (BD), apparent porosity (AP), water absorption (WA), cold crushing strength (CCS) and self-leveling flowability. The results revealed that gradual increase in firing temperature from 1100 through 1500°C caused low AP and WA, and high CCS properties due to the densification of the castable.     

Thermodynamic optimization of the K2O-Al2O3-SiO2 system

A critical evaluation and thermodynamic optimization of experimental phase diagrams and thermodynamic properties of the K₂O-Al₂O₃-SiO₂ system was performed at 1?bar total pressure. A set of self-consistent thermodynamic functions of all phases in the K₂O-Al₂O₃-SiO₂ system was obtained. The liquid phase was described using the Modified Quasichemical Model with the KAlO₂ associate component. The set of optimized model parameters obtained for all phases reproduces available and reliable thermodynamic properties and phase diagram data as well as the melt structure of the K₂O-Al₂O₃-SiO₂ system within the experimental error limits.