碱激发碳酸盐矿-矿渣胶凝-灌浆材料缓凝与流动性能的改善

苹果酸、硝酸锌、硝酸铅、消石灰等对水玻璃-矿渣水泥具有良好的缓凝作用,但不能有效地延缓碱激发碳酸盐矿-矿渣胶凝灌浆材料浆液的凝胶化时间。研究发现：外加剂氯化钡能很好地改善该灌浆材料浆液工作性能,如凝胶化时间、Marsh流出时间和扩展度等,而且还有利于强度性能的提高。外加剂氯化钡的缓凝作用是由于在矿渣粉的表面形成了良好的包裹层。     

CaO-SiO2-FeO体系中选择性分离锌铅的实验研究

为了探讨CaO-SiO2-FeO体系中选择性分离回收Zn, Pb的可行性,在系统分析该体系中Zn, Pb挥发行为的基础上,研究了温度、基体成分及Cl含量等因素如对Zn, Pb挥发率的影响. 结果表明,低温、低碱度、低FeO含量、低Cl含量条件下,Zn与Pb的挥发率差异达到最大,原因在于该种条件下Zn倾向于以ZnFe2O4等复杂化合物形式滞留在渣基体中,而Pb以氯化物形式挥发;在此基础上,对实验后的渣基体进行升温、并添加一定量的C粉等还原剂后,渣中Zn会以单质形式挥发分离,从而实现粉尘及飞灰熔融处理过程中Zn、Pb的选择性分离回收.     

Hydration and durability of sulphate-resisting and slag cement blends in Caron's Lake water

The problem of aggressive attack of sulphate and chloride ions has been of considerable scientific and technological interest because this attack is one of the factors responsible for damage to concrete. The corrosive action of chlorides is due to the formation of chloroaluminate hydrates, which causes softening of concrete. Sulphate ions can enter into chemical reactions with certain constituents of concrete, producing sulphoaluminate hydrates and gypsum, which cause the expansion of concrete. The aim of the present work is to study the hydration and the durability of mixed cement (sulphate-resisting and slag cement blends) pastes and mortars in Caron's Lake water. Different mixes of sulphate-resisting cement (SRC) with various proportions of slag cement were prepared and immersed in tap water for 3, 7, 28 and 90 days. The durability of the cement mortars was followed by curing the samples in tap water for 28 days (zero time) then immersed in Caron's Lake water for 1, 3, 6, 9 and 12 months. The hydration behavior was measured by the determination of the compressive strength, free lime, evaporable and nonevaporable water, total chloride and total sulphate contents at each curing time. The increase of substitution of SRC with blast-furnace slag cement (BFSC) up to 30% increases slightly the total pore volume. The free lime contents decrease sharply in the first months of immersion then slightly up to 1 year. The blended cement pastes made of SRC with BFSC up to 30 mass% have lower values of total chloride and total sulphate, while the mortars containing only SRC have lower values of compressive strength than those of all blended cement mortars at all curing ages of immersion under Caron's Lake water. Useful conclusions and recommendations concerning the use of 70 mass% of SRC with 30 mass% slag cement produces a highly durable mixed cement.     

Effect of supplementary cementitious materials on the compressive strength and durability of short-term cured concrete

This research focuses on studying the effect different supplementary cementitious materials (silica fume, fly ash, slag, and their combinations) on strength and durability of concrete cured for a short period of time—14 days. This work primarily deals with the characteristics of these materials, including strength, durability, and resistance to wet and dry and freeze and thaw environments. Over 16 mixes were made and compared to the control mix. Each of these mixes was either differing in the percentages of the additives or was combinations of two or more additives. All specimens were moist cured for 14 days before testing or subjected to environmental exposure. The freeze-thaw and wet-dry specimens were also compared to the control mix.Results show that at 14 days of curing, the use of supplementary cementitious materials reduced both strength and freeze-thaw durability of concrete. The combination of 10% silica fume, 25% slag, and 15% fly ash produced high strength and high resistance to freeze-thaw and wet-dry exposures as compared to other mixes. This study showed that it is imperative to cure the concrete for an extended period of time, especially those with fly ash and slag, to obtain good strength and durability. Literature review on the use of different supplementary cementitious materials in concrete to enhance strength and durability was also reported.     

Mineralogical Reconstruction of Lead Smelter Slag for Zinc Recovery

The lead smelter slag may be regarded as an important secondary resource, since tons of the slag containing 10 to 25% Zn, 3% Pb and other minor valuable elements are discharged every year by industries. It is difficult to economically justify the recovery of valuable metals (mainly zinc) using traditional technologies. In this study, mineralogical reconstruction obtained by sulfidation roasting with pyrite and carbon in the presence of sodium carbonate was conducted to recover Zn from the lead smelter slag. The effects of temperature, dosage of sodium carbonate, carbon and pyrite, and the time on the formation of ZnS were studied by XRD and optimum condition was established. The average crystal size of ZnS obtained was 2.63 µm under the optimal condition and its existence as both sphalerite and wurtzite was confirmed. The flotation tests performed indicated that zinc sulfides produced could be separated from the treated slag. The zinc grade increased from 13.63 to 32.76% and a total zinc recovery of 88.17% was obtained in the open circuit flotation test.     

Steam-cured concrete incorporating mineral admixtures

This paper explores the potential benefits of steam-cured concrete, particularly on mixes incorporating mineral admixtures. Twenty mixes with various combinations of Portland cement, fly ash (FA), slag and silica fume (SF) were investigated. For each mix, specimens were either standard-cured in a water bath of 27 °C or steam-cured at 55 °C maximum temperature over 8 h. For the materials and test conditions reported in this study, it was found that steam-cured concretes were more porous as indicated by the much higher sorptivity values compared with standard-cured specimens. Mixes with SF have the best performance and hold promise in precast manufacturing due to their high early strength development and low sorptivity values.     

冶炼铅锌废渣配料对湿法回转窑生产的影响

研究了冶炼铅锌废渣配料对湿法水泥生产的影响。研究结果表明，冶炼铅锌废渣配料，在相同水分情况下，可使生料浆流动度增加2－3mm，生料易烧性较好；冶炼铅锌废渣配料不仅有利于A矿的形成与发育，促进A矿的快速生长，增加A矿含量，提高熟料烧成质量，而且有利于延长烧成带镁铬砖的寿命。     

水胶比矿渣粉对混凝土力学性能影响的试验及机理研究

以不同配比的水胶比和矿渣粉掺量为影响因素,配制混凝土试件进行抗压强度正交试验,深入系统的研究其对高性能混凝土力学性能的影响。在此基础上,通过电镜观测,从微观机理角度对宏观性能进行分析解释。研究表明,混凝土的抗压强度均随着水化龄期的延长而增大。水化早期,掺有矿渣粉的高性能混凝土强度都较低;水化后期,矿渣粉活性效应发挥显著。在水胶比不变时,随着矿渣粉掺量的增加混凝土的强度是在逐渐降低的。使用42．5R普通水泥,控制水胶比在0．40—0．20,掺加矿渣粉,可配制出C45～C65的高性能混凝土。微观机理研究显示矿渣粉的存在使混凝土中孔隙减少,孔径变小,结构变密实,起到了很好的填充和微集料作用。     

掺钢渣混凝土开裂机理研究

钢渣作为混凝土骨料应用可能会引起水泥混凝土的稳定性不良的问题,例如混凝土开裂。本文选择了两个批次不同龄期的掺矿渣混凝土试样进行试验,进行了SEM试验从钢渣混凝土的微观形貌寻找引起钢渣混凝土开裂的原因,因为钢渣中含有的游离氧化钙和游离氧化镁等组分发生反应生成氢氧化钙等体积膨胀性产物最终导致混凝土开裂。     

磷化渣废液除锌制备高纯度磷酸三钠

为了实现磷化渣碱溶后所得废液的综合利用,采用中和沉淀法和硫化钠沉淀法去除磷化渣废液中的杂质锌,对中和沉淀法和硫化钠沉淀法的工艺条件进行优化,并由此设计磷化渣废液除锌制备高纯度磷酸三钠的生产工艺。对于中和沉淀法,在反应体系pH=8.85,反应时间为10 min时,Zn2+去除率可达97.96%;对于硫化钠沉淀法,在反应体系pH=6.85,硫化钠投加量与Zn2+的摩尔比为1:1,反应时间为10 min时,Zn2+去除率可达99.80%。相比于中和沉淀法除锌制备磷酸三钠工艺,硫化钠沉淀法除锌制备磷酸三钠工艺具有更高的磷酸三钠纯度,为98.85%,固相产品中Zn2+含量更低,仅为0.0004%,符合化工行业分析纯标准。该工艺大幅度地回收了磷化渣废液中的PO43-离子和Na+离子,为实现磷化渣综合利用的工业化提供新思路。     

Effect of pH and impurities on the surface charge of zinc oxide in aqueous solution

The surface charge on some commercially available zinc oxide powders in aqueous solution has been studied. Aqueous suspensions of zinc oxide could not be stabilized electrostatically because of the decreasing pH of suspensions in the region between 7.2 and 12 as a result the transformation of colloidal Zn(OH)_2(S) particles to Zn(OH)_2(aq) ions. The major cationic impurity in the zinc oxide powders is lead, whereas in the aged suspensions of the same powders, zinc and sulphate ions dominate. These ions have the the most significant effect in creating an electrical double layer shell around the zinc oxide particles. The effect of these ions on the surface potential of zinc oxide was studied and the point of zero charge and charge reversal were found to be a direct function of the zinc and sulphate ions' concentration in the supernatant.     

Utilization of secondary lead slag as construction material

Secondary lead slag, a waste product from battery smelting using CaCO₃ as flux, has been investigated for its use as an admixture and/or aggregate in the production of concrete blocks. The slag was added as partial replacements of cement and/or aggregate. The results revealed that the oxide components of the slag were similar to those of ordinary Portland cement (OPC). The CaO content in the slag is 6.2 times less than that in OPC, while its iron content, as FeO, is 15.1 times higher. Interestingly, it also possesses magnetic property. All samples exhibited higher compressive strengths than that of the sample without slag (STD) which increased with increasing the slag contents and ages. The highest compressive strength was of the sample containing 20% slag as cement substituent and 100% slag as aggregate replacement owing to 259% of that of the STD at 60 days. All samples showed higher water absorption than that of the STD. The higher the slag contents, the more the water absorption. The absorption was, as expected, decreased with ages. Magnetic property of the slag plays an important role in the properties of the concrete blocks. For environmental concern, leachability of lead (Pb) from all samples was also carried out.     

钢渣粉在水泥基材料中应用研究综述

目前,钢渣废弃物堆存造成了严重的环境污染和资源浪费,钢渣资源化利用迫在眉睫。将钢渣粉应用于水泥基材料中,不仅可以提高固废资源利用率,还可以减少天然资源的消耗,替代水泥降低CO₂的排放。本文介绍了钢渣的物理化学特性、胶凝性能和活性激发方式,综述了钢渣粉在混凝土复合胶凝材料、全固废胶凝材料、充填胶结材料、干混砂浆四个领域的资源化利用现状。从凝结时间、和易性、力学性能、耐久性和体积稳定性等方面分析了钢渣粉对水泥基材料性能的影响。掺入适量的钢渣粉,可有效改善水泥基材料的性能,特别是在调控拌合物和易性与提升耐久性方面有显著优势。最后,提出了将钢渣粉应用在水泥基材料中存在的问题和未来的研究发展方向。     

资源化消纳高浸铅银渣底吹+侧吹炼铅工艺优化

铅锌资源互补是企业实现多金属综合回收的主流方向。针对汉中锌业底吹+侧吹炼铅系统混配高浸铅银渣、冶炼烟灰等含铅物料后,面临的氧化熔炼热量不足、炉渣过程控制困难、还原渣稳定性差等难题,在对原有工艺综合评价基础上,结合热力学分析和炉渣性能测定结果,提出了以渣型调控为主线的工艺优化思路。研究表明,底吹炉补热方式由硫磺为主转向以烟煤为主、硫铁矿为辅,可提升氧化熔炼温度至1050℃,还原熔炼降温至1250℃;控制还原熔炼渣FeO/SiO2质量比在1.2~1.6,CaO/SiO2质量比在0.4~0.6之间,ZnO≤20wt%,可确保混配含铅废料的直接炼铅过程顺行。工艺优化后,氧料比由120 Nm3/t降至110 Nm3/t,混配高浸铅银渣比例升至24wt%;氧化熔炼与还原熔炼烟尘率同比降低13.47%与15.82%,粗铅成本同比降低10.63%。     

Influence of Ge4+ and Pb2+ ions on the kinetics of zinc electrodeposition in acidic sulphate electrolyte

The effect of Ge⁴⁺ ions, a deleterious impurity for zinc deposition in acidic sulfate electrolytes, and that of Pb²⁺ ions, which inhibit hydrogen evolution, have been investigated by means of steady-state polarization curves and impedance analysis. Typical impedance plots have been shown to characterize the processes of zinc deposition, hydrogen evolution on zinc, and hydrogen evolution on adsorbed germanium. From changes in the double layer capacitance, the charge transfer resistance and the low-frequency relaxation processes, it is concluded that lead adsorbed on zinc generates a lessened activation of hydrogen evolution with increasing cathodic potential, and enhances the formation of H_ad on the zinc deposit. With the addition of Pb²⁺ ions to the Ge⁴⁺-containing electrolyte, the features characteristic of zinc deposition are observed to prevail in the electrode impedance.     

铅锌尾矿和冶炼渣双掺制备复合水泥的试验研究*

广西河池市铅锌尾矿和冶炼渣大量堆存,缺少有效处理途径的,通过对铅锌尾矿和冶炼渣进行化学成分分析,其主要成分与水泥熟料相似,因此进行了铅锌尾矿和冶炼渣制备复合水泥的实验。实验主要研究了尾矿和冶炼渣对复合水泥强度、标准稠度需水量、凝结时间和安定性的影响。结果表明单掺尾矿能配置P·O32.5水泥,单掺冶炼渣能配置P·C42.5水泥,并结合扫描电镜对微观结构进行了分析,表明混合材掺入后使体系结构更加致密。     

Environmentally friendly copolymeric beads of Chlorella vulgaris and poly(methacrylamide) grafted aliginic acid di‐block copolymers for biosorption of zinc ions

The synthesis of biodegradable environmentally friendly copolymeric beads for water treatment biosorption processes is demonstrated. The synthesized poly(methacrylamide) grafted aliginic acid copolymers were characterized using ¹H NMR, Fourier transform infrared spectroscopy, TGA and SEM. The di‐block copolymers showed a morphological change from two‐dimensional layer‐by‐layer structures to three‐dimensional well‐compacted wrinkles as grafting efficiency increased. The copolymeric beads were formed from the di‐block copolymer and algae crosslinked with 5% calcium ions (w/w). These copolymeric beads were then subjected to biosorption investigations for zinc ions as a model heavy metal ion at different pH values and stirring time periods. Batch adsorption experiments showed that the copolymeric beads were effective in zinc ion removal from aqueous solutions with maximum uptake exceeding 89.0 mg g^–1 using higher grafting efficiency copolymeric beads at pH 5.5. Equilibrium pH studies revealed that zinc biosorption was pH dependent and maximum uptake was obtained at pH 5.5. Dynamics studies showed that the biosorption of zinc was rapid with equilibrium attained within 40 min and the data followed pseudo‐second‐order kinetics. The equilibrium biosorption of zinc ions on the copolymeric beads exhibited a Freundlich isotherm fit. © 2012 Society of Chemical Industry     

Refractory concrete lining in open-hearth y-shaped pouring spouts

Conclusions The life of concrete linings in y-shaped pouring spouts is threefold that of chamotte linings. The main wear of the concrete lining is accounted for by the mechanical removal of the 8 to 10 mm thick slag — concrete contact layer during cleaning operations.The applicating of coatings of different composition substantially affects the structure of the concrete — slag contact layer.There was no difference in quality between metal poured through chamotte lined spouts and concrete — lined spouts.The use of concrete lining for y-shaped pouring spouts is warranted for technical and economic reasons. Further increase in the service life of this type of lining requires more testing and extensive adaption to industrial furnaces.     

Modeling the hydration of concrete incorporating fly ash or slag

Granulated slag from metal industries and fly ash from the combustion of coal are industrial by-products that have been widely used as mineral admixtures in normal and high strength concrete. Due to the reaction between calcium hydroxide and fly ash or slag, the hydration of concrete containing fly ash or slag is much more complex compared with that of Portland cement. In this paper, the production of calcium hydroxide in cement hydration and its consumption in the reaction of mineral admixtures is considered in order to develop a numerical model that simulates the hydration of concrete containing fly ash or slag. The heat evolution rates of fly ash- or slag-blended concrete is determined by the contribution of both cement hydration and the reaction of the mineral admixtures. The proposed model is verified through experimental data on concrete with different water-to-cement ratios and mineral admixture substitution ratios.     

钢渣混凝土性能优化研究综述

钢渣混凝土存在着诸多缺陷,限制了其在实际工程中的应用,因此本文探究并提出了钢渣混凝土性能优化方案。首先分析了钢渣对混凝土自重、和易性和体积安定性的不利影响,并建议了可行的优化方案。接着,从钢渣替代率的角度,对钢渣混凝土的耐久性能和力学性能进行了分析,发现合适比例的钢渣用量在混凝土中的再生利用是可行的,且钢渣混凝土的整体性能较优于普通混凝土。最后,在全文分析的基础之上,为了充分优化钢渣混凝土的性能,建议将钢渣作为粗、细骨料和钢渣粉的替代率控制在合理范围之内。本文旨在探究钢渣及其替代率对钢渣混凝土性能优化的影响,并建议可行的优化方案,为工程应用试验提供参考。