稻壳灰应用研究进展

稻壳灰作为重要的农业废弃物,其资源丰富。合理地利用稻壳灰可以促进农业经济效益的增长以及资源的持续发展。由于稻壳灰中含有大量的二氧化硅,使得稻壳灰的应用受到了极大的关注。介绍了近年来稻壳灰在多个行业和领域的应用和研究工作。     

粉煤灰建材资源化的研究进展

粉煤灰是火力发电厂的副产品,利用粉煤灰生产建材是粉煤灰资源化的有效途径;结合粉煤灰的性质,介绍了粉煤灰建材资源化的研究进展,尤其是在水泥、混凝土、烧结砖和微晶玻璃等方面的最新研究成果;指出粉煤灰建材资源化还存在一些不足,需要进一步研究来提高粉煤灰利用量.     

稻壳及其产品在环保等领域中的应用

本文综述了稻壳及其产品(如稻壳灰和稻壳活性炭)在环保、化工、食品、农业及建材方面的最新应用与研究进展，并简要的介绍了其综合利用的前景。     

用稻壳灰生产硅酸钙制品

实验证明稻壳灰是制造硅酸钙防火隔热材料的优质原料,在温度达１０００℃时具有极好的热耐用性。其特征为ＳｉＯ２含量高,ＳｉＯ２相（由非晶质ＳｉＯ２、方石英和／或磷石英组成）活性高,比表面积大,在与石灰的水热反应中生成结晶良好的硬硅钙石晶体,这些晶体形成隔热材料体。由稻壳灰和石灰加玻璃纤维作增强材料所制得的产品,体密在０．１１～０．４１ｇ／ｃｍ＾３之间,不仅能满足日本工业标准ＪＩＳＡ９５１０的要求,且抗     

稻壳及其产品在环保等领域中的应用

本文综述了稻壳及其产品(如稻壳灰和稻壳活性炭)在环保、化工、食品、农业及建材方面的最新应用与研究进展,并简要的介绍了其综合利用的前景。     

稻壳灰制白炭黑和活性炭的研究

稻壳灰用烧碱浸取，得水玻璃和炭。炭经水洗、干燥和活化得粉状活性炭。水玻璃与硫酸反应得沉淀物，经过滤、洗涤、干燥得白炭黑，二种产品质量均符合标准。可行性确研究表明，工业化的经济效益相当好。     

我国稻壳资源化利用的研究进展

综述了我国稻壳资源的主要利用途径及最新研究进展,包括稻壳作为能源的利用、稻壳中硅与碳资源的利用、稻壳中纤维素类物质水解利用等各种利用方式,指出利用稻壳作为能源是目前最好的利用方式,稻壳制取高附加值的化工产品将会有较好的发展前景。     

国外稻壳灰水泥研究的新进展

在稻谷的加工生产中会副产大量谷壳。一般每吨稻谷有谷壳约二百千克,因此稻谷作为世界上的主要农作物之一,每年副产的谷壳数量极大。除了部分谷壳被用作饲料、燃料和某些工业生产的原料以外,其余的被作为废物白白扔掉。既浪费了资源,又污染了环境。这一问题在盛产稻谷的亚州、太平洋地区非常突出。中国是世界上最大的稻谷生产国,每年副产的谷壳达三千多万吨,因     

Reactivity of rice husk ash

Effect of lime:silica ratio on the kinetics of the reaction of silica with saturated lime has been investigated. Below C/S=0.65 the reaction does not proceed to completion and even in the presence of a large excess of silica only 90% lime is consumed. A parameter, lime reactivity index, has been defined to quantity the reactive silica present in rice husk ash. The product of the reaction between rice husk ash and saturated lime is a calcium hydrosilicate, CSH(I)⁷. The fibrilar structure and the hollow tubular morphology of the fibres of CSH, have been explained by a growth mechanism, where the driving force is osmotic pressure.     

稻壳生物质资源利用技术研究进展

稻壳是一种产量巨大的农业废弃物,直接丢弃或掩埋不但会造成资源浪费更会引起环境污染。稻壳中含有丰富的SiO₂、纤维素、半纤维素和木质素等。资源化利用是稻壳有效利用的发展方向和趋势。本文综述了近年来国内外稻壳资源化利用的研究进展。根据稻壳的特性,将资源化利用方式分为能源化利用、工业化利用及农业化利用,并对其研究现状进行了介绍。重点阐述了稻壳在气化制备可燃气、热裂解制备生物油、改性制备吸附剂、合成分子筛、制备催化剂载体、生产白炭黑与活性炭、水解制备糠醛、木聚糖、低聚木糖及发酵制备饲料等方面的研究进展,同时对其发展方向和趋势进行了展望,指出最大限度控制成本将成为稻壳资源化利用实现工业化的重要因素。     

Application of rice husk ash as fillers in the natural rubber industry

Rice husk ash (RHA) obtained from agricultural waste, by using rice husk as a power source, is mainly composed of silica and carbon black. A two‐stage conventional mixing procedure was used to incorporate rice husk ash into natural rubber. For comparison purposes, two commercial reinforcing fillers, silica and carbon black, were also used. The effect of these fillers on cure characteristics and mechanical properties of natural rubber materials at various loadings, ranging from 0 to 40 phr, was investigated. The results indicated that RHA filler resulted in lower Mooney viscosity and shorter cure time of the natural rubber materials. The incorporation of RHA into natural rubber improved hardness but decreased tensile strength and tear strength. Other properties, such as Young's modulus and abrasion loss, show no significant change. However, RHA is characterized by a better resilience property than that of silica and carbon black. Scanning electron micrographs revealed that the dispersion of RHA filler in the rubber matrix is discontinuous, which in turn generates a weak structure compared with that of carbon black and silica. Overall results indicate that RHA can be used as a cheaper filler for natural rubber materials where improved mechanical properties are not critical. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 34–41, 2005     

Pastes of tricalcium silicate with rice husk ash

Pastes of tricalcium silicate with rice husk ash (RHA) were cured at 25°C for 1–245 days and examined by XRD, analytical electron microscopy, TG, acid extractions to determine unreacted rice husk ash, and trimethylsilylation. The rice husk ash was highly reactive, and contents of calcium hydroxide, referred to the ignited weight, never exceeded 3%. Initially, a product having a Ca/Si atom ratio of 0.1–0.2 was formed, but this was later replaced by one having a Ca/Si ratio of approximately 1.3. The proportion of the Si in the hydration products that was present as polymeric ions was greater than that found in pure C₃S or C₃S-fly ash pastes of similar age, but the anion size distributions within the polymer were all broadly similar.     

稻壳灰在橡胶工业中的应用

概述稻壳灰在橡胶和热塑性弹性体(TPE)中的应用,并对目前存在的问题进行分析,指出今后的研究方向.稻壳灰是稻壳燃烧后的产物,主要成分为二氧化硅.稻壳灰具有来源丰富、价廉和废物回收利用的特点,在橡胶和TPE中可以作为填料使用,其补强作用需在低填充量条件下或经过处理后才能显示出来.今后应加强其性质、表面改性方法和生产工艺对其性质的影响等方面的研究.     

Technological properties of glass-ceramic tiles obtained using rice husk ash as silica precursor

This paper reports the results of a study focused on the obtainment of glass-ceramic by using rice husk ash (RHA) as silica precursor. RHA is a by-product generated in biomass plants using rice husk as fuel for kilns or in the rice mills to generate steam for the parboiling process. Worldwide, it is annually produced about 132 Mt of rice husk, which gives rise to a production of 33 Mt/year of RHA. Glass-ceramic tiles were produced by a sinter-crystallization process using a glassy frit formulated in the MgO–Al₂O₃-SiO₂ composition system. The realized glass-ceramics were studied according to ISO rules for sintering and technological properties (water absorption, apparent density, bending strength, Young's modulus, deep abrasion, Mohs hardness). To complete the investigation crystalline phase formation and microstructural characterization of the glass-ceramic materials was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Finally, chemical durability tests on parent glass and derived glass-ceramics were performed. The results obtained showed that it is possible to use RHA to produce glass-ceramic tiles by a sinter-crystallization process, obtaining nepheline (Na₂O*Al₂O₃*SiO₂) as main crystalline phase and forsterite (2MgO*SiO₂) at 900 °C. Regarding technological features, the sintered materials showed bending strength values and Mohs hardness higher with respect to commercial glass-ceramics like NeopariesR. Other properties as water absorption (0.5%) allowed to classify these materials into the Group BIa characteristic of high sintered ceramic tiles according to European Standard rule.     

Characterizing pozzolanic activity of rice husk ash by impedance spectroscopy

Rice husk ash (RHA) has long been known to possess a pozzolanic property. The abundance of rice husk as agricultural waste makes RHA the most promising candidate to be used as a supplementary cementitious material (SCM) in many rice-exporting countries. The use of RHA as an SCM helps reduce the use and thus the production of cement that involves great energy consumption and CO₂ emission. To promote the use of RHA as an SCM, a method to assess its pozzolanic activity is needed for the process of optimizing the burning conditions and/or selecting RHA from uncontrolled burning of rice husk as biomass fuel.The present work aims to use impedance spectroscopy to characterize pozzolanic activity of RHAs prepared on a pilot scale. The method is based on the rate of the normalized conductivity change of the Ca(OH)₂ + RHA paste, d(σ/σ₀)/dt, during the first 24 h of hydration. The measurement was found to be sensitive to the unburnt carbon content in the 6–8 wt.% range and the amorphous SiO₂ content (regardless of the unburnt carbon content). When used to evaluate two separate groups of RHAs, each with comparable unburnt carbon contents, the method gives very high correlation coefficients to the strength activity index at 3, 7, and 28 days. However, the correlation coefficients fall significantly when RHAs with vast difference in the unburnt carbon contents are considered together. The method thus proves to be powerful for evaluation of the pozzolanic activity of RHAs with comparable carbon contents.     

Reaction product of lime and silica from rice husk ash

Rice husk ash (about 95% silica) with known physical and chemical characteristics has been reacted with lime and water. The setting process for a lime-excess and a lime-deficient mixture has been investigated. The product of the reaction has been shown to be a calcium silicate hydrate, C-S-H(I)⁺ by a combination of thermal analysis, XRD and electron microscopy. Formation of C-S-H(I) accounts for the strength of lime-rice husk ash cement.     

Competitive adsorption of phenol and resorcinol onto rice husk ash

The present study deals with the adsorptive removal of phenol and resorcinol from aqueous solution onto rice husk ash. The competitive adsorption equilibrium of the binary mixtures (phenol/resorcinol) was determined by conducting batch experiments with initial concentration varying in the range of 50 to 1000 mg/L. In order to evaluate multicomponent adsorption isotherm parameters, individual adsorption equilibrium studies were also carried out. Langmuir, Freundlich and Redlich-Peterson equilibrium isotherm models were used for single compound equilibrium sorption data modeling. All three models almost similar fit for single compound equilibrium data. Binary equilibrium adsorption data and the parameter evaluated from single adsorption data were fitted to various multicomponent isotherm models by minimizing the sum of square of error. The extended Langmuir model gave the better fit to the experimental adsorption data of phenol and resorcinol from binary systems onto rice husk ash. It seems that both phenol and resorcinol compete for the same adsorption sites on rice husk ash. The net interactive effect of phenol and resorcinol on the adsorption of resorcinol by rice husk ash was found to be antagonistic.     

磷石膏建材资源化利用研究进展

磷石膏的建材资源化利用既可以消纳大量磷石膏,又具有较高的附加值,是处理磷石膏的重要措施之一。总结了近年来磷石膏在石膏板、石膏砌块、抹灰石膏、自流平石膏、石膏模盒等建材生产领域的研究进展,分析了目前磷石膏建材资源化面临的分布不均匀、供需不协调,产品质量差、市场认可度低,规范不健全、政策激励不充分等问题,并提出了通过开展磷石膏预处理清洁技术研发、提高磷建筑石膏质量稳定性等技术措施,以及通过政策引导和财税激励,进一步扩大磷石膏在建材领域的资源化利用。