Improvement of geotechnical properties of sabkha soil utilizing cement kiln dust

Improvement of properties of weak soils in terms of strength,durability and cost is the key from engineering point of view.The weak soils could be stabilized using mechanical and/or chemical methods.Agents added during chemical stabilization could improve the engineering properties of treated soils.Stabilizers utilized have to satisfy noticeable performance,durability,low price,and can be easily implemented.Since cement kiln dust(CKD) is industrial by-product,it would be a noble task if this waste material could be utilized for stabilization of sabkha soil.This study investigates the feasibility of utilizing CKD for improving the properties of sabkha soil.Soil samples are prepared with 2% cement and 10%,20% or 30% CKD and are tested to determine their unconfined compressive strength(UCS),soaked California bearing ratio(CBR) and durability.Mechanism of stabilization is studied utilizing advanced techniques,such as the scanning electron microscope(SEM),energy dispersive X-ray analysis(EDX),backscattered electron image(BEI) and X-ray diffraction analysis(XRD).It is noted that the sabkha soil mixed with 2% cement and 30% CKD could be used as a sub-base material in rigid pavements.The incorporation of CKD leads to technical and economic benefits.

A New Kind of Eco-Cement Made of Cement Kiln Dust and Granular Blast Furnace Slag

A research project wus conducted to manufacture eco-cement for sustainable development using cement kiln dust（ CKD ） and granular blast furnace slag（ GBFS ）. In the project, the burning process and minerul compositions of CKD dinker were investigated. Different minerulizers such as CaSO4 and CaF2 , sulfur and alkali corttent were coasidered. The strength of CKD and GBFS eco-cement were evaluated. The results indicate the CKD clinker can not only form ordinary cement clinker minerals such as C3 S, C2 S and C4 AF , but also form such high-reuctive minerals as C4 A3 S and C. A7 · CaF2 . The CKD and GBFS eco-cement will have the similar strength to the Portland cement grade 32.5 when blend proportion is properly applied.

Hydrothermal Characteristics of Blended Cement Pastes Containing Silica Sand Using Cement Kiln Dust as an Activator

The hydrothermal reactivity of silica sand was studied using cement kiln dust (CKD) as an activator in addition to the Portland cement fraction of El-Karnak cement (a blend of ordinary Portland cement and ground sand). Autoclaved EI-Karnak cement pastes were studied at pressures of 0.507, 1.013 and 1.520 MPa of saturated steam with respect to their compressive strength, kinetics of hydrothermal reaction and the phase composition of the formed hydrates. The role of CKD in affecting the physicochemical and mechanical properties of EI-Karnak cement pastes was studied by autoclaving of several pastes containing 5, 7.5, 10 and 20% CKD at a pressure of 1.013 MPa of saturated steam. CKD was added either as a raw CKD (unwashed) or after washing with water (washed CKD). The results of these physicochemical studies obtained could be related as much as possible to the role of CKD (raw or washed) in affecting the hydrothermal reactivity of silica sand in EI-Karnak cement pastes.

Utilization of Cement Kiln Dust (CKD) with Silica Fume (SF) as a Partial Replacement of Cement in Concrete Production

This research aimed to clarify the role of by-product materials, such as CKD with SF as partial replacement by weight of cement in concrete manufacturing and inclusion on different characteristics of concrete. Concrete test specimens were mixed with 0%, 5%, 10%, 15%, 20% and 25% (CKD) with 15% (SF) as partial replacement by weight of Cement (CEM I-52.5N). Fresh concrete properties have been evaluated by workability measurement slump test. While hardened concrete properties have been evaluated by compressive, split tensile and flexural strengths tests at ages 7, 28 and 56 days, but evaluated for bond strength, modulus of elasticity and chemical composition measurement with X-Ray Fluorescence at age of 28 days. The test results have revealed that the increase of CKD amount with fixed amount of SF in concrete mixtures as partial replacement by weight of cement leads to gradual decrease of fresh concrete workability. In concrete mixtures, 20% CKD in the presence of 15% SF as partial replacement by the weight of cement are the optimum ratios which can be used without any negative effect on mechanical properties compressive, indirect tensile, flexural and bond strength at all the ages of concrete. Also modulus of elasticity and bond strength increased by 8.81% and 0.69% respectively at the age 28 days compared with control mixture.

Modeling and optimization of rotary kiln treating EAF dust

Electric arc furnace （EAF） dust from steel industries is listed by the United Sates EPA as a hazardous waste under the regulations of the Resource Conservation and Recovery Act due to the presence of lead, cadmium and chlorine. The disposal of the approximately 650000 t of EAF dust per year in the U.S. and Canada is an expensive and unresolved problem for the majority of steel companies. The Waelz process has been considered as the best process for treating the EAF dust. A process model, combined thermodynamic modeling with heat transfer calculations, has been developed to simulate the chemical reactions, mass and heat trans- fer and heat balance in the kiln. The injection of air into the slag and the temperature profile along the kiln have been modeled. The effect of （CaO＋MgO）/SiO2 on the solidus temperature of slag has also been predicted and discussed. Some optimized results have been presented.

双膛石灰竖窑粉尘排放特性及控制技术研究

分析了石灰双膛竖窑在泄压过程中的粉尘排放特性,初始冲击波压力过高导致烟气无法直连布袋除尘器,这是造成粉尘污染的主要原因。弄清了初始冲击波的形成、传播与演化行为特征,比对了延长直管长度、增加弯管数量、增加变径结构与泄压腔体三种方式对冲击波压力的衰减效果,提出了一种基于压块泄压阀的柔性泄压直联布袋技术,将放散烟气初始冲击波压力由8 kPa降至1 kPa,达到烟气直连布袋、环境粉尘污染得到大幅改善的效果。同时,针对粉尘在阀体和管道中易沉降的难题,提出了一种基于3通内旋阀的扇形旋塞防沉降技术,解决了粉尘在阀体与管道系统内的沉降难题。

电除尘器在镍铁回转窑“袋改电”项目上的设计应用

主要是介绍采用C480板配侧部振打阴极系统的电除尘器在镍铁回转窑“袋改电”项目上的应用,考虑镍铁回转窑冶炼、某具体项目的烟尘特点,考虑“袋改电”改造项目场地情况,及考虑这些特点所采用的结构,以满足某具体项目的持续安全运行。

钢铁企业含锌尘泥回转窑处置设计原理及工业实践

钢铁企业产生的含锌尘泥主要是高炉、转炉、电炉除尘系统收集的除尘灰或湿式除尘产生的污泥,该含锌尘泥含有大量的锌元素等杂质,直接返回钢铁冶炼流程会影响高炉等设备的正常运行并造成锌资源浪费。回转窑工艺因成熟稳定、投资及运行成本低、原料适应性强,已成为处置含锌尘泥的主流工艺。随着“固废不出厂”等理念的深入推进,含锌尘泥回转窑处置技术也将在钢铁企业中得到广泛的应用。本文主要介绍某钢铁企业1.5×10^(5)t/a含锌尘泥回转窑处置生产线的设计原理、工艺流程和实际运行情况。该生产线设计采用具有“低碳、稳定、协同、智能、环保”的新型回转窑处置技术,有效解决了回转窑易结圈问题、智能控制水平较高、原料的适用性广泛,且具有工序能源消耗低、锌回收率高、窑渣铁金属化率高等特点,可实现含锌尘泥的资源化综合利用。项目投产后,运行稳定,生产指标达到或超过设计要求,取得了良好的经济效益。

浅析双膛窑除尘器对烟气颗粒物排放浓度的影响

阐述了双膛窑脉冲布袋除尘器的基本原理、技术指标,分析了除尘器在复杂工况下引起烟气颗粒物浓度排放值超标的主要原因,并提出了相应的解决对策。

JGMC金属纤维高温袋除尘器的应用

贯彻实施碳达峰,碳中和及工业企业超低排放的大背景下,硫酸法钛白粉煅烧尾气处理推荐配套JGMC金属纤维高温袋除尘器。本文重点介绍该设备的结构特点、技术性能,并与目前大量在运行的高压静电除尘器进行了全方位对比。结果表明:JGMC金属纤维高温袋除尘器性价比更优,具有广阔的应用空间。

A Review on Stabilization of Expansive Soil Using Industrial Solid Wastes

In developing countries like India, Industrialization is rising rapidly, and also?a great paucity of land is there, the demand for exploitation of industrial?wastes?which coming from industries is increasing. From geotechnical perspective,?fly ash, granite and quarry waste, cement kiln dust, silica fume, rice husk etc.?are the waste materials?which?have effectual features requisites by an excellent soil stabilization admixture. Stabilization using solid wastes is one of the different?methods of treatment, to improve the engineering properties and make it?suitable for construction. This paper briefs about the recent trends in stabilization of expansive soil using industrial waste (granite and quarry waste, cement kiln?dust, silica fume, rice husk) as stabilizers for decreasing the environmental?hazards.

一种用于双膛窑上料小车倒料过程中的抑尘装置

双膛窑的原料上料系统中,采用卷扬提升上料小车的方式。小车倒料过程中,因设备布置有高差,不可避免会产生扬尘。为解决这个问题,保护作业环境,本文介绍一种喷雾装置,通过喷出的微米级雾滴,在形成的雾池里实现抑尘,解决上料小车受料过程中产生的扬尘问题,可实现落料口处周围粉尘浓度低于10 mg/Nm3。

回转窑生产直接还原铁工艺结圈及预防措施

介绍了回转窑处理含铁粉尘生产直接还原铁的生产过程,重点分析了回转窑烧环境内FeO、SiO_(2)、Al_(2)O_(3)等化合物形成结圈的机理,并提出了相应的控制措施。

回转窑处理含锌尘泥技术现状及改进方向

通过对入窑原料粒度、回转窑结圈、回转窑焙烧制度、环境保护措施等影响回转窑生产运行的关键因素进行了分析和研究,提出通过调整入窑原料的粒度、加强配料管理、合理控制窑内温度、完善环保设施等手段,能够改进现有回转窑生产线存在的难题,促进回转窑处理钢铁企业含锌尘泥技术的推广和应用,助力钢铁行业技术提升与绿色发展。

水泥窑尾收尘器用水刺覆膜滤袋的寿命预估分析

通过追踪某新型干法水泥生产线窑尾收尘器用水刺覆膜滤袋不同使用时长的性能变化,证实水刺覆膜滤袋能够满足水泥窑尾粉尘排放质量浓度长期不大于10 mg/m^(3)的要求,同时根据试验数据进行寿命预估分析,推算滤袋剩余使用寿命。研究结果可为滤袋在袋式收尘器中更加科学精准地应用提供指导。

净化灰掺烧对烘干窑中产品质量的影响研究

结合净化灰的特点,将其作为碳材烘干用的燃料,但净化灰的理化性质在燃烧过程中对烘干的产品质量的影响,会进一步影响焦粉在电石炉与白灰反应的速率及反应程度。鉴于此,重点研究了掺烧净化灰对烘干产品质量的影响。研究结果表明,掺烧净化灰对烘干产品影响很小,但会影响碳材除尘灰热值,进而影响碳材除尘灰的经济价值,也会增加放散烟气中氮氧化物的含量。因此,将电石炉净化灰作碳材烘干燃料时,应考虑放散烟气是否达标,是否需要配套增加放散烟气净化系统。

高温除尘脱硝一体化联合钠碱法脱硫工艺在锂冶炼转型窑烟气净化中的应用

锂冶炼多以锂云母和锂辉石为原料,采用回转窑内进行火法冶炼,产生的烟气含有大量的重金属粉尘、SO_(2)和NO_(x)。以某5万t/a电池级锂盐项目回转窑烟气净化为对象,探究锂冶炼烟气的特点,选择高温尘硝一体化联合钠碱法脱硫工艺净化烟气,对工艺流程、各系统配置、核心设计参数进行详细说明,并提供了现场运行数据。烟气经过该工艺除尘脱硝脱硫后,装置出口净烟气SO_(2)浓度均低于100 mg/Nm^(3),NO_(x)浓度低于100 mg/Nm^(3),粉尘排放浓度低于10 mg/Nm^(3),各项参数达到超低排放要求,为同类锂行业火法冶炼窑尾烟气净化设计提供参考。

水泥窑灰替代粉煤灰的固井水泥浆体系研究

以50%API G级水泥和50%粉煤灰组成的混合材,并以0%、5%、15%、30%窑灰替代混合材,在20℃评价窑灰在粉煤灰水泥浆中的应用性能。结果表明,随着窑灰替代量的增加,水化反应的诱导期逐步缩短、热流曲线的峰值到来时间逐步提前、静胶凝强度的发展时间及稠化时间呈现缩短趋势,说明窑灰具有低温早强作用;虽水泥浆表观黏度随窑灰替代量增加有所降低,但水泥柱上下密度差仍在0. 025～0. 033 g/cm^3之间以及API失水呈现减少趋势,说明窑灰具有稳定水泥浆体的作用;可能由于窑灰属于非胶凝材料,累计放热量、绝热条件下的最高温升及后期强度(6 d)均呈现下降趋势。上述结果表明,在构建低温早强和低水化热的深水固井水泥浆体系构建中,窑灰应具有应用潜力。

水泥窑铅镉等重金属的污染及防治

利用原子吸收分光光度法、振荡溶出等方法,研究了水泥窑铅镉等重金属污染的防治。氟会促进Pb,Cd,Zn和Cu的逸放。无论何种水泥窑,Hg逸放率高达89%～96%。Pb,Cd,Zn和Cu在不同类型水泥窑中其逸放率有明显差别,立窑的逸放率较高,Pb和Cd为84%～90%,Zn和Cu为36%～47%;湿法回转窑次之;新型干法窑的逸放率最低。使用高效的除尘设备,不仅可减少粉尘的污染,还可减少Pb等重金属的逸放。把Pb等重金属含量较高的窑灰用作水泥混合材既可使Pb等重金属被固封于水泥混凝土中不会产生二次污染,又能减少因窑灰循环入窑而导致Pb等重金属的再次逸放。