Pozzolanic activity of pulverized fuel ash

The pozzolanic activity of pulverized fuel ash (p.f.a.) has been determined by measuring the rate of dissolution of silica from p.f.a. in 0.1 M hydrofluoric acid. The rate of extraction of silica follows a logarithmic law and the rate constant is an index of the pozzolanic activity of the ash.     

Effect of demineralization of El-lajjun Jordanian oil shale on oil yield

The effect of demineralization on oil yield and mineral composition of Jordanian oil shale was investigated. A standard digestion procedure using a range of inorganic and organic acids including HCl, HNO₃, HF, and CH₃COOH was used to enhance the oil recovery of oil shale samples collected from the El-lajjun area. The total yield of the digested samples, as determined by Fischer Assay, has shown a maximum value (two folds the untreated sample) obtained when using CH₃COOH. The kaolin in the treated oil shale with a high concentration of CH₃COOH is believed to have transformed to illite as found in the XRD analysis. The treatment of oil shale using HCl has shown an increased ratio of oil to gas as a result of the digestion of calcite in the oil shale. At higher concentrations of HNO₃, the acid is believed to react with the kerogen in the oil shale resulting in high levels of low molecular weight compounds. Therefore, the amount of non-condensable gases produced by Fischer assay after treatment with a high concentration of HNO₃ is relatively high. HF is believed to drive off water from the oil shale by dissolving the clay minerals leading to increased oil to gas ratio.     

Evaluation of several methods of extraction of oil from a Jordanian oil shale

A Jordanian oil shale from the El Lajjun deposit has been reacted with N₂, H₂ and CO in the presence and absence of water in the temperature range 300–425 °C. The effect of adding Fe, Cu, Ni, Sn and NaAlO₂ as potential catalysts to some of these reactions has been studied but none led to improved oil yields. Most of the organic material in the oil shale was converted to asphaltene at 355 °C, but the oil yield was low at this temperature. At 425 °C nearly all the organic product was in the form of oil.     

油页岩灰渣制备聚氯化铝的工艺研究

以广东省茂名市油页岩灰渣为原料,用碱法制备聚氯化铝(PAC),考察了酸溶条件对产品的铝浸出率与盐基度的影响。结果表明,以油页岩灰渣制备聚氯化铝的最佳酸溶条件为:酸的质量分数为12%,酸量比n(HCl)∶n(Al2O3)=10,酸溶温度为110℃,酸溶时间为3 h。此条件下,铝浸出率为62.92%,聚合氯化铝的盐基度为82.25%。     

Copper and zinc sorption by treated oil shale ash

Jordanian oil shale ash was used as an adsorbent for the removal of copper and zinc from aqueous solution. This ash was treated with either hydrochloric, nitric, sulfuric or phosphoric acids followed by washing and/or neutralization with sodium hydroxide in order to enhance its adsorption capacity. The sample that was treated with nitric acid showed the highest cation exchange capacity (CEC) of 146 meq/100 g, while the one that was treated with sulfuric acid showed a value of 32 meq/100 g. Different adsorption isotherm data for both copper and zinc were obtained using the nitric acid-treated sample at different pH values. Freundlich and BET models were used to fit the experimental data, which showed that BET best-fitted these data. The separation factor for these isotherms shows unfavorable adsorption type at lower pH value.     

Removal of nitrogen compounds from shale oil by adsorption on to acid-treated shale ash

Basic nitrogen compounds occurring in shale oil can be selectively adsorbed by spent oil shale ash that has first been treated with either a mineral acid, e.g. HCl, or a Lewis acid, e.g. CuCl₂. For Rundle shale oil a reduction in the basic nitrogen level from 0.55 wt% to less than 0.05 wt%, and total nitrogen from 1.2 wt % to 0.5 wt%, has been achieved using an ash rich in clay minerals and low in carbonates. It has also been shown that pyridine, quinoline and 2,6-dimethylpyridine are all readily adsorbed by ash treated with several common transition metal chlorides. Selection of an appropriate Lewis acid, or mixture of acids should enable adsorption to be optimized when specific impurities are known to be present. Under appropriate conditions most of the reference basic nitrogen compounds can be adsorbed in less than 1 h.     

Synthesis of Na-A and -X zeolites from oil shale ash

The solid by-product of oil shale processing (PETROBRAS-Brazil) was used as a raw material to synthesize Na-A and -X zeolites. Two preparation methods using the same starting material composition were carried out. In Method (1), alkaline fusion was used to prepare a glass, which was then hydrated by refluxing. The largest amount of crystallinity was reached with 2 h 30 min of refluxing. In Method (2), alkaline fusion was followed by hydrothermal treatment. The most crystalline sample was obtained after 12 h of heat treatment, and after 96 h hydroxysodalite zeolite was formed. In both procedures, the synthesis products were mainly composed of Na-X zeolite, whose content was influenced by the crystallization time, and of Na-A zeolite, with a practically constant content.     

油页岩灰渣综合利用技术研究进展

介绍了我国油页岩资源的开发与利用概况。针对油页岩开发中产生的大量灰渣,认为采用填埋和堆积的处理方式,不仅造成资源的浪费,且占用大量的土地资源、破坏周边生态环境。参考国内外对油页岩灰渣的处理工艺,总结了油页岩灰渣制作水泥、轻质砖材、白炭黑、微晶泡沫玻璃,烧制陶粒以及提取氧化铝等综合利用的方法,并对油页岩灰渣综合利用提出了建议。     

Hydrothermal alkaline treatment of oil shale ash for synthesis of tobermorites

The hydrothermal alkaline activation of the oil shale fly ash was studied using SEM/EDX, XRD and ²⁹Si and ²⁷Al high-resolution MAS-NMR spectra. The silicon in the original fly ashes was completely converted into calcium-alumino-silicate hydrates, mainly into 1.1 nm tobermorite structure during 24 h treatment under hydrothermal conditions at 160 °C in the presence of NaOH. The local structure of synthesized tobermorite samples implies long silicate chains with small number of bridging sites. The results obtained in the study prove that the oil shale fly ash can be used for production of Al-substituted tobermorites.     

燃烧过程对页岩灰孔隙结构的影响

页岩灰为油页岩及其半焦的燃烧产物,可作为建筑原材料、化工填料和吸附剂等,具有一定的工程应用价值。采用氮气等温吸附/脱附法对油页岩燃烧生成的页岩灰的孔隙结构进行了测量,并对不同升温速率和不同终温所得到的页岩灰的孔隙结构进行了比较,结果表明：如果油页岩在快速升温条件下燃烧所放出的热量能够被周围环境吸收而使得油页岩颗粒温度始终低于其灰熔点温度,所得到的页岩灰的孔容积和孔比表面积较大,适宜工业应用。     

油页岩灰渣碱法制取白炭黑的工艺研究

以广东省茂名市油页岩灰渣为原料,采用碱溶法制备白炭黑,考察了碱溶条件对白炭黑产率的影响。结果表明,碱溶法制取白炭黑的碱溶最佳工艺为：c（氢氧化钠）=4 mol/L, n（氢氧化钠）/n（二氧化硅）=5∶1,碱溶温度为110 ℃, 碱溶时间为4 h,焙烧温度为750 ℃,焙烧时间为2.5 h。在最佳条件下制备的产品,白炭黑的产率为81.49%、白度为98.1%。对白炭黑进行了FT-IR表征及性能测试,所制白炭黑符合化工行业标准（HG/T 3061—2009）的要求。     

CO2 supercritical fluid extraction of Jordanian oil shale utilizing different co-solvents

In this study, extracting shale oil from Jordanian oil shale using supercritical fluid extraction has been investigated. Experimental data indicates that by using supercritical extraction with carbon dioxide, using co-solvents can be viable. A relatively high yield can be obtained at relatively moderate pressure. At the highest temperature and pressure of 450 °C and 3200 psi, respectively, and with hexane as a co-solvent, the highest yield obtained was 100 kg/ton of oil shale, which was at the highest temperature and pressure of 450 °C and 3200 psi, respectively, and with hexane as a co-solvent. Increasing both the operating pressure and temperature increases the oil yield. In the supercritical state, carbon dioxide along with other co-solvents, such as hexane and acetone, interact with the kerogen leading to the dissolution of fragments due to an increase in solubility and mass transfer.Increasing the particle size of oil shale for extraction decreases the oil yield. Most of the extracted oil obtained is saturated hydrocarbons, olefinic and a portion of aromatic hydrocarbons. As the extraction temperature increases, the production of low-molecular weight compounds increases.     

页岩灰和FCC催化剂调控油页岩热解产物二次反应特性

采用两段反应器对油页岩热解初级挥发分进行二次催化反应特性研究,考察了第2段反应器内不同的催化载体、反应气氛与停留时间对油气收率及品质的影响。结果表明,在考察的停留时间范围内页岩灰具有相对适中的催化活性来调控热解挥发分产物的二次反应,水蒸气气氛能够进一步提高热解油收率约5%,并能够在一定程度上抑制裂解气体中C₂~C₃组分的生成。页岩灰作为催化载体能够转化热解油中VGO（馏程>350℃）等重质组分,随停留时间增加油品馏程向轻组分转移。油品组分GC-MS结果表明,较短停留时间内（<3 s）,水蒸气添加能够有效抑制热解油中脂肪烃类的过度裂解,与氮气相比提高汽柴油馏分含量20%以上。过长的停留时间（3~5 s）会造成VGO等馏分缩聚生成焦炭,从而大幅降低热解油收率。     

Preparation of silica aerogel from oil shale ash by fluidized bed drying

The silica aerogel with high specific surface area and large pore volume was successfully synthesized using oil shale ash (OSA) via ambient pressure drying. The oil shale ash was burned and leached by sulfuric acid solution, and then was extracted using sodium hydroxide solution to produce a sodium silicate solution. The solution was neutralized with sulfuric acid solution to form a silica gel. After washing with water, the solvent exchange with n-hexane, and the surface modification with hexamethyldisilazane (HMDZ), the aged gel was dried by fluidization technique and also using a furnace to yield silica aerogels. The physical and textural properties of the resultant silica aerogels were investigated and discussed. The results have been compared with silica aerogel powders dried in a furnace. From the results, it is clear that the properties of silica powders obtained in fluidized bed are superior to that of powders dried in the furnace. Using fluidization technique, it could produce silica aerogel powders with low tapping density of 0.0775 g/cm³, high specific surface area (789 m²/g) and cumulative pore volume of 2.77 cm³/g.     

Pozzolanic activity of silica dust

Highly reactive aggregates and unusually alkali-rich cement call for special precautions in connection with concrete making in Iceland. Search in the past for efficient ways to counteract alkali-aggregate reactions is cited. High hopes are now connected with the pozzolanic use of silica fume from a ferrosilicon plant now under erection. The influence of this dust on cement strength and mortarbar expansion is described.     

Pozzolanic properties of reject fly ash in blended cement pastes

Low-grade fly ash (reject fly ash, r-FA), a significant portion of the pulverized fuel ash (PFA) produced from coal-fired power plants and rejected from the ash classifying process, has remained unused due to its high carbon content and large particle size. But it may be used in certain areas, such as in solidification and stabilization processes of hazardous waste and materials for road base or subbase construction, which require relatively lower strength and reactivity. It is therefore necessary to extend research on the properties of r-FA and explore its possible applications. This paper presents experimental results of a study on the mechanical and hydration properties of cementitious materials prepared by blending r-FA with ordinary Portland cement (OPC). Parallel mixes were also prepared with the good ash [i.e., classified fine fly ash (f-FA)] for comparison. Selective chemical activators were added to the mix to study the effects of the activators on the properties of the blend system. The results show that r-FA generally has a lower rate of hydration than f-FA particularly at the early stage of hydration. Adding Ca(OH)₂ alone almost had no effect on accelerating the hydration of r-FA. But adding a small quantity of Na₂SO₄ or K₂SO₄ together with Ca(OH)₂ significantly accelerated the hydration reaction. The results of the compressive strength measurement correlated nicely with the degree of hydration results. It was also found that water-to-binder ratio (w/b) was an important factor in affecting the strength development and the hydration degree of r-FA pastes.     

Properties and structure of oil shale ash pastes I: Composition and physical features

The composition and physical features of oil shale ash pastes were determined and compared with the corresponding properties of portland cement paste. In the first part presented here, the composition, chemically combined water, porosity (total, capillary and gel porosity), pore-size and pore-size distribution, and specific surface area were determined by water vapor adsorption, mercury penetration and X-ray diffraction. It was established that the structural features and the factors which control and determine these features, are essentially the same in both the ash and the portland cement pastes. In the ash paste, however, total porosity remained virtually unchanged with time. This aspect, as well as the mechanical properties of the ash paste, are presented and discussed in the second part of the paper.     

Pozzolanic activity of various siliceous materials

The accelerated pozzolanic activity of various siliceous materials, like silica fume, fly ash (as received and fine ground), quartz, precipitated silica, metakaolin and rice husk ash (RHA; various fineness and carbon content), has been determined. The compressive strength of accelerated tests has been compared with cubes cured in water at 7 and 28 days. Maximum activity has been observed in case of RHA (<45 μ), followed by quartz and silica fume. The 10% replacement of cement by sand has shown accelerated pozzolanic index of 92% compared with 85% required in ASTM for silica fume as mineral admixture.     

Dielectric properties of Jordanian oil shales

Microwave heating has been suggested by various authors as a suitable technology for extraction of organic material from oil shales. However, one of the limiting factors in the development of this technology is a lack of accurate dielectric property data for design purposes. In this study the dielectric behaviour of El-lajun oil shale is quantified. The dielectric constant and loss factor of El-lajun oil shale were measured at 2470 and 912 MHz using the cavity perturbation technique. The effects of organic content, temperature, and moisture content on the microwave heating efficiency were quantified. Coaxial probe technique was also employed to study the effect of frequency on dielectric properties of oil shale. Generally, it was found that all samples were of low dielectric loss at room temperature with the imaginary part of permittivity falling significantly after the moisture was removed. This suggests that the major contribution in the dielectric loss is due to the presence of free and/or interlayer water. It was found that both the real and imaginary part of complex permittivity increased with a rise in temperature from 20 up to 80 °C, then dropped significantly at about 100 °C before staying approximately constant up to a temperature of about 480 °C. From this temperature both the real and imaginary parts of complex permittivity increased sharply with further increase in temperature. An attempt was also made to correlate the dielectric properties of the bulk shale sample with the organic content. However, no correlation between dielectric properties and organic matter content was found.