Strength properties of concrete incorporating coal bottom ash and granulated blast furnace slag

Coal bottom ash (CBA) and fly ash (FA) are by-products of thermal power plants. Granulated blast-furnace slag (GBFS) is developed during iron production in iron and steel plants. This research was conducted to evaluate the compressive strength property and some durability characteristics of concrete incorporating FA, CBA, and GBFS. FA is used as an effective partial cement replacement; CBA and GBFS are used as partial replacement for fine aggregate without grinding. Water absorption capacity, unit weight and compressive strengths in 7, 28, and 90-day ages were assessed experimentally. For these experiments, concrete specimens were produced in the laboratory in appropriate shapes. The samples are divided into two main categories: M1, which incorporated CBA and GBFS; and M2, which incorporated FA, CBA, and GBFS. Remarkable decreases are observed in compressive strength and water absorption capacity of the concrete; bulk density of the concrete is also decreased. It can be concluded that if the content of CBA and GBFS is limited to a reasonable amount, the small decreases in strength can be accepted for low strength concrete works.     

Mechanical properties and microstructure of ground granulated blast furnace slag-based geopolymer reinforced with polyvinyl alcohol fibers

Journal of Material Cycles and Waste Management - Ground granulated blast furnace slag (GGBFS) is a solid waste characterized by a high reactivity with alkali solutions, which is normally used...     

Efficiency of a blast furnace slag cement for immobilizing simulated borate radioactive liquid waste

The efficiency of a blast furnace slag cement (Spanish CEM III/B) for immobilizing simulated radioactive borate liquid waste [containing H3BO3, NaCl, Na2SO4 and Na(OH)] has been evaluated by means of a leaching attack in de-mineralized water at the temperature of 40 degrees C over 180 days. The leaching was carried out according to the ANSI/ANS-16.1-1986 test. Moreover, changes of the matrix microstructure were characterized through porosity and pore-size distribution analysis carried out by mercury intrusion porosimetry (MIP), X-ray diffraction (XRD) and thermal analysis (TG). The results were compared with those obtained from a calcium aluminate cement matrix, previously published.     

Use of Pb blast furnace slag as a partial substitute for fine aggregate in cement mortar

The technical properties of cement mortars containing natural fine aggregate that is replaced by lead blast furnace slag at 25 and 35% level were assessed at fixed water-to-cement (W/C) ratio and at fixed flow table value. The leachabilities of some toxic elements from the cement mortars were also assessed to test the environmental suitability of the slag for use in preparation of cement mortar. At fixed W/C ratio, the strength of the mortar decreased with increase of the slag content. On the other hand, at fixed consistency, strength increased with increasing slag content in the mortar composition. The concentrations of some toxic elements in the leachates collected from the mortars containing slag were slightly higher than for the control mortar, but the concentrations in the leachates remained within the regulatory limits for recycling in construction applications. For most elements, leaching from a mortar containing 35% of slag was similar to that from a mortar containing 25% of slag. Therefore, 35% of natural sand can be beneficially replaced with Pb slag to produce cement mortar without affecting the mechanical and leaching properties studied in this work.     

脱硫装置采用钢与混凝土组合湿烟囱探讨

烟气脱硫装置采用湿烟囱排放可降低工程投资,降低电耗、水耗和年运行费。介绍了一种钢与混凝土组合湿烟囱,烟囱底部是混凝土部分,上部是钢烟囱;烟囱采用内壁涂抹环氧乙烯基玻璃鳞片树脂进行防腐。     

Stabilization of chloro-organics using organophilic bentonite in a cement-blast furnace slag matrix.

The application of cement-based stabilisation/solidification treatment to organic-containing wastes is made difficult by the adverse effect of organics on cement hydration. The use of organophilic clays as pre-solidification adsorbents of the organic compounds can reduce this problem because of the high adsorption power of these clays and their compatibility with the cementitious matrix. This work presents an investigation of the effect on hydration kinetics, physico-mechanical properties and leaching behaviour of cement-based solidified waste forms containing 2-chlorophenol and 1-chloronapthalene adsorbed on organophilic bentonites. These were prepared by cation exchange with benzyldimethyloctadecylammonium chloride and trimethyloctadecylammonium chloride. The binder was a 30% pozzolanic cement, 70% granulated blast furnace slag mixture. Several binder-to-bentonite ratios and different concentrations of the organics on the bentonite were used. Kinetics of hydration were studied by measurement of chemically bound water and by means of thermal and calorimetric analyses. Microstructure and other physico-mechanical properties of the solidified forms were studied by means of mercury intrusion porosimetry, scanning electron microscopy and unconfined compressive strength measurement. Leaching was checked by two different leaching tests: one dynamic, on monolithic samples, and the other static, on powdered samples. This study indicates that the incorporation of the organic-loaded bentonite in the binder matrix causes modifications in the hardened samples by altering cement hydration. The effects of the two organic contaminants are differentiated.     

Enhancing performance and durability of slag made from incinerator bottom ash and fly ash

This work presents a method capable of melting the incinerator bottom ash and fly ash in a plasma furnace. The performance of slag and the strategies for recycling of bottom ash and fly ash are improved by adjusting chemical components of bottom ash and fly ash. Ashes are separated by a magnetic process to improve the performance of slag. Analytical results indicate that the air-cooled slag (ACS) and magnetic-separated slag (MSS) have hardness levels below 590 MPa, indicating fragility. Additionally, the hardness of crystallized slag (RTS) is between 655 and 686 MPa, indicating toughness. The leached concentrations of heavy metals for these three slags are all below the regulatory limits. ACS appears to have better chemical stability than MSS, and is not significantly different from RTS. In the potential alkali-silica reactivity of slag, MSS falls on the border between the harmless zone and the potentially harmful zone. ACS and RTS fall in the harmless zone. Hence, the magnetic separation procedure of ashes does not significantly improve the quality of slag. However, RTS appears to improve its quality.     

煤气化细渣制备碳硅复合材料吸附去除水中Pb2+

以煤气化细渣为原料制备了高比表面积碳硅复合材料,并利用过硫酸铵对其进行表面改性,用于吸附100.0 mg/L PbCl₂溶液中Pb²⁺。表征结果显示：碳硅复合材料的比表面积为1 347 m²/g,改性后降为474 m²/g;改性后材料表面的羟基、羰基和羧基等含氧基团的含量显著增加。实验结果表明：溶液pH为5时,改性碳硅复合材料对Pb²⁺的平衡吸附量为124 mg/g,Pb²⁺去除率可达98.2%;吸附过程符合准二级动力学模型,以化学吸附为主,伴有物理吸附;吸附过程分为外扩散和内扩散两个阶段,受内扩散控制。     

Utilization of high-volume mine tailing and by-products in composite binder production: hardened properties and sustainable development

Journal of Material Cycles and Waste Management - This study was designed to investigate the hardened performance of the paste specimens produced using a composite binder with high volumes of mine...     

半干法脱硫灰生产蒸压砖技术研究

国网能源开发有限公司焦作电厂针对半干法脱硫灰难以利用的现状,提出了用脱硫灰生产蒸压砖技术方案,该方案可完全利用脱硫灰中的CaO、CaCO3、Ca（OH）2、CaSO3和CaSO4。介绍了脱硫灰的理化特性及脱硫灰蒸养砖的工业化试验,实现了半干法脱硫灰制蒸压砖工业化生产的综合利用。     

GGH换热元件堵塞原因分析及解决措施探讨

分析了湿法脱硫系统中GGH换热元件堵塞的原因及对系统运行的影响,并结合目前GGH使用状况给出了解决措施,为脱硫系统安全运行提供参考。     

Processing and characterization of a new biodegradable composite made of a PHB/V matrix and regenerated cellulosic fibers

In this study, a biodegradable composite consisting of a degradable continuous cellulosic fiber and a degradable polymer matrix—poly(3-hydroxybutyrate)-co-poly(3-hydroxyvalerate (PHB/V with 19% HV)—was developed. The composite was processed by impregnating the cellulosic fibers on-line withPHB/V powder in a fluidization chamber. The impregnated roving was then filament wound on a plate and hot-pressed. The resulting unidirectional composite plates were mechanically tested and optically characterized by SEM. The fiber content was 9.9 ±0.9 vol% by volumetric determination. The fiber content predicted by the rule of mixture for unidirectional composites was 13.8 ±1.4 vol%. Optical characterization showed that the fiber distribution was homogeneous and a satisfactory wetting of the fibers by the matrix was achieved. Using a blower to remove excess matrix powder during processing increased the fiber content to 26.5 ±3.3 vol % (volumetric) or 30.0 ±0.4 vol% (rule of mixture). The tensile strength of the composite parallel to the fiber direction was 128 ±12 MPa (10 vol% fiber) up to 278 ±48 MPa (26.5 vol% fiber), compared to 20 MPa for the PHB/V matrix. The Young’s modulus was 5.8 ±0.5 GPa (10 vol% fiber) and reached 11.4 ±0.14 GPa (26.5 vol% fiber), versus 1 GPa for the matrix.     

Regeneration of used sand with sodium silicate binder by wet method and their core manufacturing

Journal of Material Cycles and Waste Management - Organic binders that are used in sand casting emit high amounts of hazardous pollutants and volatile organic compounds during the casting process....     

Crystal structure of a new high-performance magnesium slag desulfurizer modified by quenching hydration

Journal of Material Cycles and Waste Management - The original magnesium slag has poor desulfurization activity, so modification treatments are needed to improve its desulfurization activity. In...     

Evaluation of chemical stability of heavy metals in industrial waste slag by infrared spectroscopy

Our aim was to clarify the chemical bonding type and stability of heavy metals in industrial waste slag (IWS) by using Fourier transform infrared (FT-IR) spectroscopy. The chemical composition of the IWS sample used in this study was an Al/Si ratio of 0.50 with Fe, Pb, and other minor heavy metals present. The IR peak position of the Si-OSi( M) band (M: Al, Pb, or Fe) was lower for IWS (971 cm⁻¹) than for synthetic Si-Al glass with an Al/Si ratio of 0.5 (1029 cm⁻¹). This implies the formation of covalent Si-O-Pb and Si-O-Fe bonds in the IWS, which caused a shift in the peak position toward a lower wavenumber. FT-IR spectra of synthetic Si-Al-Pb and Si-Al-Fe glasses with various Pb/Si and Fe/Si ratios with a constant Al/Si ratio of 0.5 showed that the peak position of the Si-O-Si(M) band continuously shifted toward lower wavenumbers with increasing Pb/Si and Fe/Si ratios. This suggests that covalent Si-O-Pb and Si-O-Fe bonds are formed in IWS. The comparison of peak positions of the Si-O-Si(M) band between IWS and Si-Al-Fe glass indicated that not only Pb but also other minor heavy metals such as Cu and Cr were included by covalent bonds into the structure of IWS. Therefore, we concluded that most of the heavy metals in IWS formed covalent Si-O-M bodings and were chemically stable.     

锰渣脱硫制硫酸锰技术在电解锰行业的应用

介绍了某电解锰企业锰渣煅烧含高浓度SO₂烟气的资源化处理路线,阐述了氧化锰矿浆烟气脱硫制MnSO₄技术的工艺设计。该烟气脱硫制MnSO₄装置运行稳定,尾气中SO₂质量浓度为32.1~51.9 mg/m³,达到排放设计要求,脱硫装置产生的MnSO₄浆液中Mn²⁺质量浓度为(40±1)g/L,连二硫酸锰质量浓度小于5 g/L,满足电解锰生产要求。     

Improvement of permeability of waste sludge by mixing with slag or construction and demolition waste

To determine the allowable ratio of waste sludge required to ensure an aerobic zone in the landfill, we investigated sludge permeability, which involved mixing sludge, the major landfill waste in Japan, at different mixing ratios with other wastes (slag and construction and demolition waste (C&D)). We measured parameters of sample permeability and analyzed parameters that exert a large influence on oxygen penetration depth with a simulation model accounting for both diffusion and convection driven by temperature gradients. We also determined the critical volumetric contents in which gas and/or water permeability change significantly when sludge is mixed with sand or gravel. From the results of the simulations, gas permeability of the layer, the difference between inside and outside temperatures and the oxygen consumption rate exert a large influence on the resulting oxygen penetration depth. The allowable ratio of sludge required to ensure an aerobic zone in the landfill was determined by considering the balance of the above three parameters. By keeping volumetric sludge content to below 25%, air convection and oxygen penetration depth of several meters were achieved in the modeling.     

铜渣催化H2O2氧化处理棉浆黑液

采用铜渣催化H2O2类Fenton氧化反应处理棉浆黑液,研究了酸析pH、H2O2投加量、铜渣投加量对棉浆黑液COD和TOC去除率及溶出Fe2+质量浓度的影响,考察了铜渣重复使用性能,讨论了铜渣催化作用机制.结果表明:在酸析pH为2、H2O2投加量为25 mmol/L、铜渣投加量为2.5 g/L条件下,反应180 min...     

Alkali-silica reactions of mortars produced by using waste glass as fine aggregate and admixtures such as fly ash and Li2CO3

Use of waste glass or glass cullet (GC) as concrete aggregate is becoming more widespread each day because of the increase in resource efficiency. Recycling of wastes is very important for sustainable development. When glass is used as aggregate in concrete or mortar, expansions and internal stresses occur due to an alkali-silica reaction (ASR). Furthermore, rapid loss in durability is generally observed due to extreme crack formation and an increase in permeability. It is necessary to use some kind of chemical or mineral admixture to reduce crack formation. In this study, mortar bars are produced by using three different colors of glass in four different quantities as fine aggregate by weight, and the effects of these glass aggregates on ASR are investigated, corresponding to ASTM C 1260. Additionally, in order to reduce the expansions of mortars, 10% and 20% fly ash (FA) as mineral admixture and 1% and 2% Li(2)CO(3) as chemical admixture are incorporated by weight in the cement and their effects on expansion are examined. It is observed that among white (WG), green (GG) and brown glass (BG) aggregates, WG aggregate causes the greatest expansion. In addition, expansion increases with an increase in amount of glass. According to the test results, it is seen that over 20% FA and 2% Li(2)CO(3) replacements are required to produce mortars which have expansion values below the 0.2% critical value when exposed to ASR. However, usages of these admixtures reduce expansions occurring because of ASR.