Catalytic spectrophotometric determination of trace vanadium in fly ash and coal gangue by Triton X-100 enhancing effect

Trace Ⅴ(Ⅴ) catalyzes mightily the decolorization reaction of arsenazo Ⅲ(AsA Ⅲ) by oxidizing with H_2O_2 in a pH 4.0 HAc-NaAc buffer solution, and the addition of TritonX-100 can further increase the sensitivity of the reaction and its catalytic extent is linear withthe content of Ⅴ(Ⅴ). A catalytic spectrophotometric procedure for determining trace Ⅴ(Ⅴ)wasdeveloped. The results show that the maximun absorption of the color solution is at 560 nm and thedetection limit of the method for Ⅴ(Ⅴ) is 0.014 mg·L^(-1). Beer's law is obeyed for Ⅴ(Ⅴ) in therange of 0.00-0.20 mg·L^(-1). The recoveries are 99.0%-104.6%, and the relative standarddeviations (RSD) are 2.7%-3.7%. Combined with ion-exchange resin, the method has been applied to thedetermination of trace vanadium in fly ash and coal gangue with satisfactory results.

Leaching Behavior of Fly Ashes from Power Plants

The Yanzhou mine district, located in southwestern Shandong Province, is about 1300 km2 with more than 8×109tons of proved coal reserves and there are 10 big power plants in this area. A large amount of coal ashes, which are regarded as waste materials, have been stockpiled in the area and have influenced the environment of the mine district. In this paper, analysis of fly ash samples from three power plants is carried out, the enrichment and concentration of trace elements, Pb, Zn, Cu and As, in coal ashes are analyzed, and petrological and mineralogical characteristics and chemical compositions of coal ashes are studied. The aim of this work is to provide basic scientific data for utilization of ashes and reduction of environmental pollutions.

Heavy metals distribution in fly ash from gangue power plant

To make assessment on its environmental security, fly ash samples were collected from the gangue power plant. Total content of heavy metals in sieved fly ash were analytically determined. We also carried out Tessier extractive experiments to check the chemical species of heavy metals. Experiment results show that the content of Cu, Zn, Pb and Cd ascend when particle size is smaller. Cu, Zn, Pb and Cd obviously enrich in particulate fly ash. The chemical species of heavy metal distribution ranking sequence generally is residual〉organic combinative〉Fe-Mn oxide combinative〉carbonate combinative〉ion-exchangeable. Lead＇s amiable-move species were high in proportion, amounted to 35%. Total content of Cadmium is at low level, but its ion-exchangeable species is relatively high in proportion. Nickel and zinc is mainly distributed in residue. Cu is mainly distributed in residue and organic combinative form. The content of manganese is relatively high in fly ash, and the carbonate combinative iron-manganese oxide combinative species are main chemical form. Cr is mainly distributed in residue, and its other chemical species are at low level. Compared with the soil background value of study area and Shandong Province, the content of Cu, Ni, Zn, Mn and Cr in fly ash of gangue power plant is lower. While contents of Pb and Cd were higher than background value, and amiable-move species is relatively high in proportion. They are more apt to cause heavy metal pollution.

Preparation of biological aerated filter media with coal fly ash and coal gangues

A novel kind of filter media has been studied using in biological aerated filter process which is produced by waste coal fly ash and coal gangues.The specific surface area and sum of braking and ware rate are viewed as the main factor for determining preparation conditions,including calcination temperature (in the range of 900 ℃ to 1250 ℃),proportion of coal gangue (in the range of 0 to 25%) and soaking time (in the range of 0 to 40 min).The effects of sintering conditions on the main property parameters are researched and the reasons have been analyzed.Considered with all factors,the optimum technological conditions are chosen as follows:the calcination temperature is 1050 ℃ ;the soaking time is 10 min and the proportion of coal gangue is 5%.When at these condition,the main property parameters of the filter media in the technological conditions are 1.6 m 2 /g for the specific surface area and 2.96 % for sum of braking and are rate respectively.Finally,a scanning electron microscope is used for analyzing the microstructure of the filter media.

Effects of NaOH Concentrations on Properties of the Thermal Power Plant Ashes-Bricks by Alkaline Activation

The use of the thermal power plant ashes including fly ash(FA) and bottom ash(BA) for producing unfired building bricks(UBB) using sodium hydroxide(NaOH) solution as an alkaline activator was investigated. A low applied forming pressure of 0.5 MPa and various NaOH concentrations of 5, 8, 10, and 12 M were used for the preparation of brick samples with different solution-to-binder(S/B) ratios of 0.35 and 0.40. The bricks were subjected to various test programs with reflecting the effect of both NaOH concentrations and S/B ratios on the brick’s properties. The compressive strength, unit weight, ultrasonic pulse velocity, and thermal conductivity of bricks increased with increasing NaOH concentration, whereas the contrary trend was found with increasing S/B ratio. Also, the water absorption of bricks was observed to reduce with increasing NaOH concentration and decreasing S/B ratio. As the results, the combined utilization of both low forming pressure and coal power plant ashes can produce the UBBs with low unit weight, low heat conductivity, and acceptable strength and water absorption rate as stipulated by TCVN 6477-2016. Furthermore, the outcomes of chemical analysis and microstructure observation also demonstrate that a high concentration of the Na OH promoted the geopolymerization process. Notably, the use of NaOH solution of either 10 M or above is recommended for the production of UBBs, which are classified as grade M5.0 or higher.

The experimental study of the coal gangue as gel filling materials

The odd axes resist pressure intensity with large quantity coal gangue was dis- cussed and experimented on fly ash and coal gangue gel filling body between different concentration,proportion and additive dosage.The results show that forepart intensity of new gangue filling body is very low,and anaphase intensity have some increase which still go up after sixty days.The intensity of tao gangue can reach 1.0 MPa in seven days,and anaphase intensity can reach about 2.0 MPa.In the same term,the odd axes resist pres- sure intensity of gel filling body with tao gangue is higher than new gangue No.1 and No.2. To mix into proper additive dosage which occupied the quality point of cement and fly ash not more than 1.5% can improve the fluidity of slurry body and intensity of filling body.

Heavy Metals in Dust Deposition in the Vicinity of Coal Ash Disposal Site Divkovici Ⅱ

DD （Dust deposition） was monitored over a 6-month period （April to September, 2011） at four sites located in villages near CADDⅡ（coal ash disposal site Divkovici Ⅱ）, one inside recultivated CADDⅠ （coal ash disposal site Divkovici Ⅰ） and at one in the middle of forest barrier as control site. The main aim of this paper is to perform monitoring of air dust pollution in the area by measuring of dust deposition, different metals associated with it, and probable adverse effects on human health. Concentrations of metals were measured by using Perkin-Elmer model Inductively Coupled Plasma and statistically evaluated with SPSS 17.0 statistical program. There was a correlation between some metals （Mn, Mo and Pb） and DD distribution. The daily limit values for concentration of DD proposed by national ＂Regulations on air quality＂ （200 mg/m^2d average annual value and 350 mg/m^2d high value） exceed at three measuring sites. The average maximum content of DD was 684.8 mg/m^2d downwind of CADDII, and the average minimum was 46.8 mg/m^2d at measuring site F. Concentrations of pollutants hazardous to the environment as Ni, Cr, Cu, Mo, Mn and Pb vary from one site to another.

Development of Sensible Heat Storage Materials Using Sand, Clay and Coal Bottom Ash

In this paper, the mechanical and thermal properties of a sand-clay ceramic with additives coal bottom ash (CBA) waste from incinerator coal power plant are investigated to develop an alternative material for thermal energy storage (TES). Ceramic balls are developed at 1000°C and 1060°C using sintering or firing method. The obtained ceramics were compressed with a compression machine and thermally analyse using Decagon devise KD2 Pro thermal analyser. A muffle furnace was also used for thermal cycling at 610°C. It was found that the CBA increased the porosity, which resulted in the increase of the axial tensile strength reaching 3.5 MPa for sand-clay and ash ceramic. The ceramic balls with the required tensile strength for TES were selected. Their volumetric heat capacity, and thermal conductivity range respectively from 2.4075 MJ·m-3·°C-1 to 3.426 MJ·m-3·°C-1 and their thermal conductivity from 0.331 Wm-1·K-1, to 1.014 Wm-1·K-1 depending on sand origin, size and firing temperature. The selected formulas have good thermal stability because the most fragile specimens after 60 thermal cycles did not present any cracks. These properties allow envisioning the use of the ceramic balls developed as filler material for thermocline thermal energy storage (structured beds) in Concentrating Solar Power plants. And for other applications like solar cooker and solar dryer.

A review of the synthesis and application of zeolites from coal-based solid wastes

Zeolite derived from coal-based solid wastes(coal gangue and coal fly ash)can overcome the environmental problems caused by coal-based solid wastes and achieve valuable utilization.In this paper,the physicochemical properties of coal gangue and coal fly ash are introduced.The mechanism and application characteristics of the pretreatment processes for zeolite synthesis from coal-based solid wastes are also introduced.The synthesis processes of coal-based solid waste zeolite and their advantages and disadvantages are summarized.Furthermore,the application characteristics of various coal-based solid waste zeolites and their common application fields are illustrated.Finally,we propose an alkaline fusion-assisted supercritical hydrothermal crystallization as an efficient method for synthesizing coal-based solid waste zeolites.In addition,more attention should be given to the recycling of alkaline waste liquid and the application of coal-based solid waste zeolites in the field of volatile organic compound adsorption removal.

Effect of temperature on the hydration process and strength development in blends of Portland cement and activated coal gangue or fly ash

This paper describes the results of an investigation into the effect of the variation of curing temperatures between 0 and 60 °C on the hydration process,pore structure variation,and compressive strength development of activated coal gangue-cement blend(ACGC) . Hardened ACGC pastes cured for hydration periods from 1 to 360 d were examined using the non-evaporable water method,thermal analysis,mercury intrusion porosimetry,and mechanical testing. To evaluate the specific effect of activated coal gangue(ACG) as a supplementary cementing material(SCM) ,a fly ash-cement blend(FAC) was used as a control. Results show that raising the curing temperature accelerates pozzolanic reactions involving the SCMs,increasing the degree of hydration of the cement blends,and hence increasing the rate of improvement in strength. The effect of curing temperature on FAC is greater than that on ACGC. The pore structure of the hardened cement paste is improved by increasing the curing temperature up to 40 °C,but when the curing temperature reaches 60 °C,the changing nature of the pore structure leads to a decrease in strength. The correlation between compressive strength and the degree of hydration and porosity is linear in nature.

电厂燃煤飞灰固化脱硫污泥重金属铅特性研究

【目的】燃煤电厂脱硫污泥中重金属富集显著,降低脱硫污泥中重金属含量十分必要。【方法】提出利用电厂飞灰固化脱硫污泥重金属的思路,并和常见固化剂开展对比。【结果】以铅为对象,在水泥、飞灰、螯合剂二硫代氨基甲酸酯(dithiocarbamate,DTC)和螯合剂三聚硫氰酸三钠盐(TMT-15)中,飞灰对脱硫污泥中铅固化效果最好;不同飞灰及脱硫污泥固化效率在40%~100%。机理分析表明,类似于水泥,飞灰化学成分主要含有SiO2、Al2O3、CaO、Fe2O3等,可与脱硫污泥发生水化反应等,生成对重金属固化稳定有利的水化硅酸钙C-S-H等水化产物及钙矾石等物质,同时生成物对重金属铅等具有吸附作用。【结论】在燃煤电厂脱硫污泥中掺入一定比例的飞灰可以实现铅的固化稳定,为脱硫污泥从危险固废降低为一般固废提供了方法。

矸石电厂粉煤灰薄喷材料制备及性能研究

为实现矸石电厂粉煤灰的综合利用,在分析了陕西黄陵矸石电厂粉煤灰理化性能基础上,研究粉煤灰掺量、胶沙比、粉煤灰质量分数对薄喷材料流动性能及抗压强度的影响规律。通过正交实验确定了矸石电厂粉煤灰薄喷材料基础配比,并采用扫描电镜(SEM)对薄喷材料1、28 d龄期的微观结构进行表征。通过外加剂对材料流动性能进行调控,揭示了调控机理。研究结果表明,当粉煤灰∶水泥(质量比)为6∶1,胶沙比(质量比)为1.0∶1.2,粉煤灰质量分数为77%,聚羧酸减水剂掺量为0.5%(质量分数),SD-WJ40液体无碱速凝剂掺量为11%(质量分数)时,薄喷材料性能满足混凝土基层喷浆处理技术规程要求。

巴基斯坦某燃煤电站工程除灰渣系统设计

该文介绍巴基斯坦某燃煤电站的工程条件,除灰渣系统的设计原则,详述除渣系统、除灰系统、灰库系统、气化风系统、压缩空气系统和石子煤系统的设计,给出各系统主要设备的参数和数量、除渣系统和除灰系统的工艺流程图,从设计标准、当地温度和湿度、灰渣综合利用、盐雾腐蚀、细渣处理和各单位配合的几个方面,总结本工程的设计经验。解决现场反馈的干灰散装机的适用性、干燥器前进口阀门的类型和空压机房排污水管道设计等问题,高质量地完成除灰渣系统的设计任务。

宁东能源化工基地燃煤电厂粉煤灰的矿物学及元素地球化学特征

粉煤灰的类型、元素及矿物组成等理化性质是决定粉煤灰资源化利用途径的基础。为实现宁东能源化工基地周边燃煤电厂粉煤灰的潜在高值化利用,以马莲台电厂和银星电厂原煤、炉渣、粗灰、细灰为研究对象,用X射线荧光广谱(XRF)、电感耦合等离子体质谱(ICP-MS)手段分析粉煤灰化学组成及微量元素含量,用X射线衍射仪(XRD)、扫描电子显微镜分析粉煤灰矿物组成与形态特征。结果表明:马莲台电厂和银星电厂的粗灰、细灰氧化物化学组成以SiO_(2)、Al_(2)O_(3)、Fe_(2)O_(3)和CaO为主,含少量TiO_(2)、MnO、MgO、Na_(2)O、K_(2)O、P_(2)O_(5);两电厂粉煤灰中CaO质量分数均小于10%、w(SiO_(2))+w(Al_(2)O_(3))+w(Fe_(2)O_(3))>75.39%,均属F型低钙粉煤灰;结晶矿物相均以石英、莫来石、赤铁矿、生石灰、钙长石、硬石膏、白云石、方解石等为主,玻璃质主要由SiO_(2)和Al_(2)O_(3)组成,且以SiO_(2)/Al_(2)O_(3)高质量比(2.18~2.36)为特征;粗灰和细灰中大多微量元素含量均低于欧洲飞灰中对应元素最大值,B、V、Co、Cu、Ga、Sn、Cs、Ti、Pb、Zn、Sn等挥发性强且冷凝性相对高的元素易在飞灰中富集,Mg、Ca、Sr、Fe、Mn、Cr、Ni等挥发性弱的元素易在炉渣中富集;两电厂粉煤灰中微量元素含量低、淋滤能力低、玻璃质含量高、SiO_(2)/Al_(2)O_(3)质量比高,表明其在资源化利用过程中利用价值高、环境风险低。

关于煤电行业除尘除灰系统标准体系修订的探讨

首先阐述了“双碳目标”背景下煤电机组除尘、除灰系统的运行现状及面临的安全挑战,探讨了积极开展除尘、除灰系统相关标准修订工作的紧迫性和重要性。其次系统梳理了涉及除尘器、除灰系统和钢结构安全等国家、行业标准的使用现状,剖析了标准的空白缺位,以及标准之间存在的主要矛盾、不适应性等,并提出了除尘、除灰系统标准体系构建的总体框架,分析了标准体系修订的必要性及产生效益。最后围绕煤电行业除尘除灰系统标准体系的近期、中期和远期修订计划提出了针对性建议。

火电厂运行调整及锅炉燃烧调整对飞灰品质的影响分析

锅炉是火电厂运行中的重要设备,主要利用煤粉燃烧产生的热量进行汽轮发电。但是,锅炉燃烧期间会产生大量飞灰,如果飞灰中的含碳量超出了要求标准,则会影响飞灰品质,还容易对周围环境造成污染。火电厂运行调整和锅炉燃烧调整都会对飞灰品质产生不同程度的影响,要清楚各类要素的影响程度,并从提高飞灰品质和降低飞灰中含碳量的角度出发,做好火电厂运行调整、锅炉燃烧调整以及优化煤种质量和配置等工作,完善调整控制措施,切实提升锅炉燃烧中飞灰的质量。