Effects of several casting parameters on slag entrapment in mould( part A: water modeling)

The mechanism of slag entrapment in the mould was analyzed and the water modeling experiment was done according to the industrial manufacturing. The results show that the flow of the liquid steel becomes more active and the level fluctuation in the mould becomes bigger when the casting speed increases from 1.0 m/min to 1.2 m/min. So the control of slag entrapment in the mould becomes more difficult. When the depth of the nozzle increases from 30mm to 42. 5mm and the angle increases from 15~ downward to 30° downward, the level fluctuation in the mould becomes smaller and the slag entrapment in the mould also decreases. But the impact depth increases and the circumfluence vortex center moves downward, which is unfavorable for the flotation of gas bubbles and inclusions. Furthermore, the impact depth with side holes a （ 16.3 × 20mm2 ） and b （ 10 × 10 mm2 ） is almost equal, but a smaller level fluctuation can be obtained with side hole a.

Application of Air-cooled Blast Furnace Slag Aggregates as Replacement of Natural Aggregates in Cement-based Materials：A Study on Water Absorption Property

The influence of air-cooled blast furnace slag aggregates as replacement of natural aggregates on the water absorption of concrete and mortar was studied, and the mechanism was analyzed. The interface between aggregate and matrix in concrete was analyzed by using a micro-hardness tester, a laser confocal microscope and a scanning electron microscope with backscattered electron image mode. The pore structure of mortar matrixes under different curing conditions was investigated by mercury intrusion porosimetry. The results showed that when natural aggregates were replaced with air-cooled blast furnace slag aggregates in mortar or concrete, the content of the capillary pore in the mortar matrix was reduced and the interfacial structure between aggregate and matrix was improved, resulting in the lower water absorption of mortar or concrete. Compared to the concrete made with crushed limestone and natural river sand, the initial absorption coefficient, the secondary absorption coefficient and the water absorption capacity through the surface for 7 d of the concrete made from crushed air-cooled blast furnace slag and air-cooled blast furnace slag sand were reduced by 48.9%, 52.8%, and 46.5%, respectively.

Tests on Alkali-Activated Slag Foamed Concrete with Various Water-Binder Ratios and Substitution Levels of Fly Ash

To provide basic data for the reasonable mixing design of the alkali-activated (AA) foamed concrete as a thermal insulation material for a floor heating system, 9 concrete mixes with a targeted dry density less than 400 kg/m3 were tested. Ground granulated blast-furnace slag (GGBS) as a source material was activated by the following two types of alkali activators: 10% Ca(OH)2 and 4% Mg(NO3)2, and 2.5% Ca(OH)2 and 6.5% Na2SiO3. The main test parameters were water-to-binder (W/B) ratio and the substitution level (RFA) of fly ash (FA) for GGBS. Test results revealed that the dry density of AA GGBS foamed concrete was independent of the W/B ratio an RFA, whereas the compressive strength increased with the decrease in W/B ratio and with the increase in RFA up to 15%, beyond which it decreased. With the increase in the W/B ratio, the amount of macro capillaries and artificial air pores increased, which resulted in the decrease of compressive strength. The magnitude of the environmental loads of the AA GGBS foamed concrete is independent of the W/B ratio and RFA. The largest reduction percentage was found in the photochemical oxidation potential, being more than 99%. The reduction percentage was 87% - 93% for the global warming potential, 81% - 84% for abiotic depletion, 79% - 84% for acidification potential, 77% - 85% for eutrophication potential, and 73% - 83% for human toxicity potential. Ultimately, this study proved that the developed AA GGBS foamed concrete has a considerable promise as a sustainable construction material for nonstructural element.

Preparation of Granulated Adsorption Material of Water-quenched Slag/rectorite Composite for Removal of Cu(Ⅱ)Ions from Copper Smelter Wastewater

The preparation of granulated adsorption material of water-quenched slag/rectorite composite and the treatment of Cu （ Ⅱ ）-containing copper smelter wastewater with the adsorption material were studied. The experimental results showed that under the conditions with the mass ratio of water-quenched slag to rectorite of 1：1, 10% additive of industrial starch （IS）, and 50% water, and a calcination temperature of 400 ℃, the granulated adsorption material prepared had a density of 1.06 kg/m^3, a porosity of 62.29%, water absorption rate of 58.82%, and compressive strength of 2.22 MPa. The efficiency of wastewater treatment was the best, whereas the rate of spallation loss was low. Under the conditions of natural pH, with the addition of the granulated adsorption material of 0.05 g/mL, a reaction time of 40 minutes, and temperature of 25 ℃, the efficiency of the granulated adsorption material for the removal of Cu （ Ⅱ ） ions from the copper smelter wastewater attained 98.2%, and the quality indexes of the wastewater after treatment conformed with the first level of integrated wastewater discharge standard （GB8978-1996）. The reclamation of the used granulated adsorption material was carried out by de-sorption of the Cu （ Ⅱ） ions from the surface with 1 mol/L sodium chloride solution. The de-sorption rate was 96.4%, and the adsorption material can be reused many times to treat copper smelter wastewater.

Water Vapour Solubility in Tundish Slags

In the present work,the solubility of water vapour in tundish slag has been studied in the temperature range from 1 400 C to 1 600 C by a thermogravimetric technique.The water vapour capacity of the slags was calculated and compared with the data from earlier studies.The results confirm that the solubility of water vapour in slags increases with increasing water vapour pressure.The relation between the two parameters obeys Sievert’s law.For slags with optical basicities from 0.5 to 0.8,a regression equation was obtained to express the relation between the water vapour capacity and optical basicity of slags.A tundish slag system with the desired properties can be designed according to the correlations between the optical basicity and various capacities of slags.

磷建筑石膏矿渣水泥的水化过程与耐水性能

通过凝结时间、流动度、孔溶液pH值、抗折强度、抗压强度、吸水率、软化系数、水化热和水化产物分析测试,探究了磷建筑石膏(CPG)掺量对石膏矿渣水泥水化过程与耐水性能的影响.结果表明:随着CPG掺量的增加,石膏矿渣水泥的凝结时间缩短,流动度减小,吸水率与3 d水化累计放热量均增大;水泥净浆孔溶液的pH值在水化早期快速下降,56 d时保持不变;当CPG掺量从40%增加到70%时,56 d水泥净浆孔溶液的pH值从11.02减小到10.62,水泥胶砂的软化系数从0.98减小到0.91,主要水化产物均为二水石膏和钙矾石,并且钙矾石的含量随着CPG掺量的增加而减少.

西北干旱露天煤矿排土场土壤重构与水盐运移机制

矿山排土场生态修复是煤矿露天开采面临的重大环境问题,是制约建设绿色露天煤矿的重要因素。土壤重构是排土场生态修复的重要步骤,以新疆为代表的西北煤炭基地,水资源短缺,盐碱化突出,土壤水盐运移是决定土壤重构是否成功的关键指标。目前研究集中在表层土壤重构改善土壤养分促进植物生长,针对保水控盐的功能化土壤重构的研究甚少,对不同土壤重构方式下的水盐运移机制尚不明晰。研究立足新疆煤炭资源禀赋特征,从煤炭循环经济的角度出发,采用能源化工副产物煤气化渣(CGS)作为重构材料,通过毛细水上升-蒸发试验,分析CGS重构后水盐垂向运移和水分供给能力,通过Van Genuchten模型拟合土壤水分特征曲线,分析CGS重构后土壤持水能力,研究CGS作为含水层重构材料的可行性。采用煤矿开采伴生岩石矿物红泥岩作为重构材料,通过土柱入渗蒸发试验,分析红泥岩重构后不同土壤深度的水盐变化情况,研究泥岩作为隔水层重构材料的可行性。结果表明,CGS重构改善土壤质地,优化孔隙结构,促进了土壤水盐运移,毛细作用增强,促进了下层水分向上供给,同时也增加了盐分表聚,重构改变土水特征曲线参数,增加了饱和含水量θ_(s),降低了参数a和n,改善了土壤持水性能。CGS添加量越高,细渣质量分数越大,效果越明显。CGS作为重构含水层材料具有可行性。红泥岩黏粒和次生矿物含量高,孔隙结构丰富,物理吸附性良好,重构后0~24 cm深度下土壤含水率高于对照组,蒸发后的盐分在20~24 cm达最高值,红泥岩有效阻隔了盐分上移。红泥岩作为重构隔水层材料具有可行性。研究以期探索出一条适合西部煤炭基地排土场土壤重构模式。

The Influence of Free Water Content on Dielectric Properties of Alkali Active Slag Cement Paste

The dielectric performance of alkali activated slag （AAS） cement paste was investigated in the frequency range of 1 to 1000 MHz. The experimental results showed the unstable dielectric properties of harden paste were mostly influenced by the fraction of free water in paste or absorbed water from ambient, but not including hydration water and microstructure. The free water was completely eliminated by heat treatment at 105 ℃ about 4 hours, and then its dielectric loss was depressed; but with the exposure time in air increasing, the free water adsorption in ambient air made the dielectric property of harden cement paste to be bad. The temperature and relative humidity of environment was the key factors of free water adsorption; hence, if the influence of free water on dielectric constant was measured or eliminated, the cement-based materials may be applied in humidity sensitive materials or dielectric materials domains.

矿渣水泥基复合材料在杂散电流作用下的抗软水溶蚀机理研究

在轨道交通工程运营期间,复杂的服役环境导致混凝土结构耐久性下降。本文主要研究了在杂散电流与软水溶蚀耦合作用下,矿渣掺量、水胶比和杂散电流电压强度对矿渣水泥基复合材料微观结构的影响。结合X射线衍射、热重、扫描电子显微镜和压汞等方法,分析了矿渣水泥基复合材料经溶蚀90 d后的物相组成、Ca(OH)_(2)含量、微观形貌以及孔结构变化。研究结果表明:矿渣掺量越大,矿渣水泥基复合材料内部的Ca(OH)_(2)含量越少,材料的孔隙率越低,结构更均匀致密;随着杂散电流电压强度的增加,矿渣水泥基复合材料内部的Ca(OH)_(2)和AFt含量变少,且AFt和Ca(OH)_(2)等物相边界变得模糊不清;矿渣水泥基复合材料中C-(A)-S-H的含量略有增多,孔隙率略有下降;随着水胶比的增大,矿渣水泥基复合材料内部的Ca(OH)_(2)含量变少,剩余物相含量变少,微观结构变得松散多孔,孔径结构整体粗化,孔隙率增大。

利用垃圾焚烧渣制备陶瓷透水路面砖的试验研究

垃圾焚烧渣是一种危险的固体废弃物,无害化利用垃圾焚烧渣具有重要意义。以垃圾焚烧渣为主要原料,通过高温烧结工艺制备了一种综合性能较佳的透水砖,研究了垃圾焚烧渣的添加量与烧成温度对样品结构与性能的影响规律。结果表明:添加适量的废玻璃及适当提高烧成温度能够改善试样的强度及环境安全性;当垃圾焚烧渣、废玻璃与煤粉(外加)的添加量分别为60%、40%、20%(质量分数)时,在1 200℃下烧成制品的透水系数、抗折强度与抗压强度分别为0.58 mm/s、6.23 MPa和18.58 MPa,其强度和透水系数分别达到了R_(f)4.5与B等级,且制品的Cu^(2+)、Pb^(3+)和Zn^(2+)浸出浓度满足GB 5085.3—2007《危险废物鉴别标准浸出毒性鉴别》要求。XRD与SEM-EDS分析结果表明,由废玻璃熔融而成的高温液相溶解了三氧化二铅、氧化锌和氧化铜,抑制了Cu^(2+)、Pb^(3+)和Zn^(2+)的浸出。提高烧成温度能够降低样品的气孔率,促进三氧化二铅、氧化锌与氧化铜的溶解,进而协同改善制品的环境安全性。莫来石与玻璃相相互胶结,连通气孔均匀分布,赋予了透水砖较高的强度与优良的透水性能。

某固废资源综合利用项目产生水淬渣的危险特性鉴别研究

为明确某固废资源综合利用项目中产生水淬渣的危险特性,通过属性判断、腐蚀性鉴别、急性毒性初筛、易燃性鉴别、浸出毒性鉴别、反应性鉴别、毒性物质含量鉴别等手段对水淬渣是否具有危险特性进行鉴别。鉴别结果表明,在生产工艺不变、原辅料来源稳定、原辅料配比稳定且相关生产设备运行良好,生产工况稳定的情况下,鉴别对象水淬渣不属于危险废物,可作为一般工业固体废物进行管理和处置。

含铜污泥搭配发热危废协同处理及综合利用技术

本文介绍了富氧侧吹熔池熔炼炉协同处理含铜污泥和发热危废的技术,该工艺具有金属回收率高、熔炼强度大、一次能源消耗低,实现了含铜污泥的有价金属的综合回收和发热危废的无害化处理。生产实践表明:处理量10万吨/a含铜污泥和发热危废,可降低煤率约10%,节约成本770万/a,产出约4000t/a的多金属合金(其中含铜55%、含镍11.9%),为企业提质增效打开了的突破口。

碱激发矿渣-赤泥新型低碳透水混凝土性能研究

以粒化高炉矿渣与拜耳法赤泥两种工业固废作为胶凝材料,硅酸钠溶液作为碱激发剂,石灰岩碎石作为粗骨料,制备透水混凝土,研究了设计孔隙率、水胶比与骨料粒径对透水混凝土强度与透水性能的影响。结果表明:随设计孔隙率增大,试样的强度逐渐减小,但透水性能逐渐增强。最优水胶比受设计孔隙率和骨料粒径的影响,当透水混凝土设计孔隙率为15%、骨料粒径为4.75~9.50 mm时,最优水胶比为0.36,其强度较高且具有良好的透水性能。碱矿渣-赤泥透水混凝土的力学与透水性能均优于水泥透水混凝土,符合低碳绿色的发展理念。

建筑物下特厚煤层镁渣基全固废连采连充开采技术与实践

我国建筑物下压煤量巨大,同时煤矸石、粉煤灰等煤基工业固体废弃物排放量日益增加,严重制约地方经济社会发展。以榆林麻黄梁煤矿为试验矿井,针对其特厚煤层、建筑物下压煤、充填成本高等问题,提出了特厚煤层全固废连采连充开采技术。采用四阶段工序并将特厚煤层分为上、下2部分二次回采压覆煤炭,最大程度控制地面沉降。为降低充填原材料成本,采用化学优化剂对镁渣进行源头改性,抑制镁渣冷却粉化,稳定水化活性,协同粉煤灰、脱硫石膏等煤基固废,研发了改性镁−煤渣基胶凝材料。采用改性镁−煤渣基胶凝材料胶结煤矸石、粉煤灰制备了全固废充填材料。针对麻黄梁煤矿四阶段强、弱充填强度要求,设计不同配比的改性镁渣基充填材料试验,优选配比并应用于井下充填。论述了膏体充填系统与充填接顶方法。麻黄梁煤矿全固废胶结充填工艺试验显示,井下28 d龄期充填体钻芯平均单轴抗压强度超设计强度27%,钻芯浸出毒性满足相关国家标准要求,成功回收了建筑物下压覆煤炭资源,社会经济效益显著。麻黄梁煤矿特厚煤层全固废胶结充填开采实践为国内类似矿井提供了有益借鉴,同时为我国大型煤炭基地的“煤−电−化−冶”固废大规模资源化利用提供了新的思路。

侧吹熔炼处置锌冶炼渣炉渣组成对导热性及析出物相的影响

侧吹熔炼炉采用水冷挂渣炉壁时,高导热系数炉渣可在炉衬表面形成稳定渣皮,保护并延长炉衬的使用寿命。针对铁矾渣和铅银渣处理用FeO-CaO-SiO_(2)-PbO-ZnO五元渣系,采用稳态平板法对炉渣渣皮的导热系数进行了测定,并通过扫描电镜对固态渣皮进行微观结构分析,以探究炉渣组分改变对渣皮导热系数及结晶矿相的影响。结果表明,增加CaO和SiO_(2)都会使渣皮导热系数增大,其中添加CaO对渣型影响最显著。优化渣型的导热系数从原渣的7.62 W/(m·K)增大到了17.94 W/(m·K),提高了135%。在冷凝过程中,高温析出的物相为黄长石,其熔点、黏度相较于原渣也有显著降低。调整后的渣型更容易形成稳定的渣皮,有利于水冷挂渣护炉。

碱与矿物掺和料对磷石膏霉变与性能影响研究

为解决磷石膏制品易发霉、力学性能低和耐水性差等问题,本研究通过复合石灰、电石渣等碱性材料和矿渣、偏高岭土等矿物掺和料来改善其各项性能。采用扫描电镜、X射线衍射仪、压汞仪等测定了磷石膏制品的水化产物。结果表明:碱可以有效抑制磷石膏制品发霉;在碱性条件下,矿物掺和料可以提升磷石膏制品力学性能和耐水性。磷石膏制品的最佳配比(质量分数)为:磷石膏72%、矿渣20%、偏高岭土8%、电石渣5%,其抗压强度为23.19 MPa,吸水率为27%,软化系数为0.85。水化硅酸钙(C-S-H)对孔结构优化优于钙矾石(AFt)。

碎煤加压气化固态排渣系统工艺技术分析比较

固定床碎煤加压气化是一种重要的煤气化技术,根据其灰渣特性采取适当排渣技术是一个重要环节,目前主要有水力湿法排渣、水冷干法排渣及风冷干法排渣等排渣方式。从灰渣收集、冷却方式、综合利用、节水节能等方面对三种排渣方式进行了分析比较,认为水力湿法排渣技术成熟,但已相对落后,水冷干法排渣技术介于风冷干法和水力湿法排渣两者之间,风冷干法排渣技术具有诸多优势,但目前没有在碎煤加压气化系统的应用业绩,煤化工项目在碎煤加压气化排渣技术选择中,应综合考虑各种因素,选择与项目匹配的排渣技术。

电石渣-矿渣固化膨胀土强度及微观机制研究

针对南水北调中线地区膨胀土因环境湿度变化引起力学特性劣化导致的工程地质灾变问题,采用电石渣、矿渣作为固化材料对膨胀土进行改良,通过素膨胀土和改良固化膨胀土无侧限抗压强度、劈裂抗拉强度和水稳性等对比试验,分析改良固化前后的性能差异;通过X射线衍射(X-ray diffraction,XRD)、电镜扫描(electron microscope scanning,SEM)、热重分析(thermogravimetric analysis,TGA)试验及核磁共振(nuclear magnetic resonance,NMR)试验分析了电石渣-矿渣固化土的强度增长机制,揭示其微观作用机制。结果表明:以6%电石渣掺量为基础,不同矿渣掺量下的电石渣-矿渣复合改性固化土,总体上强度和耐水性能均有明显提高,并在矿渣掺量为9%时达到最大值。而随着养护龄期的增加,无侧限抗压强度和劈裂抗拉强度不断增加,水稳系数则有所减小。电石渣-矿渣复合固化土水化生成的水化硅酸钙(C-S-H)和水化铝酸钙(C-A-H),胶结土颗粒形成了紧密的团聚体,有效改善了土体的孔结构分布,提高了固化土的强度。电石渣-矿渣膨胀土复合固化方法效果明显,具有较好的工程应用前景。

基于灰色关联分析的钢渣沥青混凝土水稳定性研究

该文采用灰色关联法,分析了不同生产工艺的钢渣、级配、沥青以及集料粒径的水稳定性能,并通过计算它们的关联度,得出了影响钢渣沥青混凝土水稳定性能的主次因素。研究结果显示,影响钢渣沥青混凝土水稳定性的因素相对影响程度依次为沥青、集料、级配和粒径。

拉林铁路弃渣场水土保持型生态恢复技术探讨

为研究高寒高海拔地区铁路建设项目弃渣场的生态恢复措施,该文以拉(拉萨)林(林芝)铁路工程为依托,结合青藏高原的地域条件探讨弃渣场的水土保持型生态恢复技术。研究得到以下结论,根据恢复区立地条件,系统阐明弃渣场的选址原则及水土保持型生态恢复理论;基于物种选择原则和防护措施设计建立适应于青藏高原地区的水土保持型生态恢复技术。研究成果可为该地区铁路工程建设项目的弃渣治理提供一定的借鉴意义。