Calcium sulfate whisker prepared by flue gas desulfurization gypsum:A physical–chemical coupling production process

In this paper,the solid waste desulfurization gypsum produced by coal-fired power plants was used as a raw material to prepare calcium sulfate whiskers with high application prospects.Calcium sulfate whiskers with uniform morphology and high aspect ratio can be prepared by hydrothermal method in sulfuric acid solution.A new process of desulfurization gypsum activated by high-energy grinding to reduce the reaction temperature and sulfuric acid concentration was developed.Through the comparison of product morphology,the best grinding time was determined to be 3.5 h.The mechanism of desulfurization gypsum through physical–chemical coupling to reduce energy consumption was clarified.The activation of desulfurization gypsum by grinding and the acidic environment provided by the sulfuric acid solution made the calcium sulfate solution reached rapid saturation and accelerated the nucleation rate.By calculating the conversion and crystallization rate of calcium sulfate whiskers,it was found that there were obvious"autocatalytic"kinetic characteristics during the crystallization process.

Rheological and physicochemical characteristics of asphalt mastics incorporating lime kiln dust and dolomite powder as sustainable fillers

The filler-bitumen interaction mechanism is one of the most essential phases for comprehending the asphalt mixture's performance.However,despite numerous studies,in-depth knowledge of filler-bitumen reciprocity at a microscale level is yet to be ascertained.The goal of this research is to gain a better understanding of the fillerbitumen microscale interaction in terms of the synergy and coaction between the physicochemical and rheological performance of mastics due to filler inclusions.The rheological properties of two sustainable mastics,dolomite powder(DP)and lime kiln dust(LKD),together with a neat PEN 60/70 binder,were analysed based on a temperature sweep at elevated temperature conditions.Meanwhile,frequency sweep and multiple stress creep recovery(MSCR)tests were also conducted at pavement serviceability temperature using the dynamic shear rheometer(DSR).Physicochemical tests using a scanning electron microscope(SEM)and energy dispersive X-rays(EDX)were conducted to analyse the impact of parameters such as particle shape,grain size,texture,and chemical compositions.The DSR test results showcased how the incorporation of fillers in asphalt binder considerably improved the performance of the binder in terms of rutting and fatigue.Likewise,its strain and nonrecoverable compliance parameters were substantially reduced at higher filler and binder concentrations.Physical filler attributes of low rigden voids(R.V),high fineness modulus(FM),and high specific surface area(SSA)led to greater interfacial stiffness and elasticity in LKD mastics compared to DP mastics at different loading frequencies and temperature levels.The SEM/EDX results also indicated that the elemental calcium and carbon composition of each filler component,together with its grain morphology,strongly influenced its rheological performance.

XPS,Chemical Trapping, and DRFTIR Study on Mechanism of By-Products Formation in Selective (AMM)Oxidation of Propylene on MoO_3 and γ-Bi_2MoO_6

XPS and chemical trapping experments with H2, NH3, and CH3I as trapping agents were carried out for studying the adsorption of propylene over MoO3 or r-Bi2MoO6. The results show that the fragmentation of carbon chain takes place during the adsorption of propylene through breaking C -C double bond and C-C bond on Mo2+ and the adjacent lattice oxygen, leading to formation of the oxygen- or nitrogen-containing by-products of C1 and C2 species. Diffuse-Reflection Fourier Transform Infrared (DRFTIR) Spectroscopy was used to study the surface species formed during the chemisorption and reaction of propylene over y-Bi2MoO6 at a lower temperature. The results that C1, C2 adspecies were detected by DRFTIR at 175℃ are consistent with the results of XPS and chemical trapping experiments, whlle the results at 50℃ Grasselli et al.

Chemical Composition and Nutritive Value of Agro-Industrial By-Products in Ruminant Nutrition

This study was carried out to determine the chemical composition and in situ degradability of agro-industrial by-products found in Eritrea. Three categories of by-products were evaluated and were the milling industry (wheat bran;WB, short;WS, and middling;WM), brewery (brewers’ dry grain;BDG, hops;BDH, and yeast;BDY) and sesame cakes (sesame cake machine extracted;SCM and manually extracted;SCT). The dry matter (DM) varied between 88.46% in BDY to 92.39% in SCT. The lowest (P < 0.05) crude protein (CP) content was recorded in WM at 10.11% while the highest was from the BDY at 48.20%. The metabolisable energy (ME) value of the agro-industrial by-products ranged from 8.72 to 11.18 MJ per kg DM with the BDH recording the lowest value (P The sesame cakes (SCM and SCT) recorded higher values of 11.17 and 11.18 MJ per kg DM respectively. The SCT recorded the highest ash content at 10.93% followed by BDY at 10.16% with the least being obtained from WM at 2.48%. The ether extract and acid detergent lignin contents were generally low in all cases for all the by-products. Generally, the results indicated that there was no clear pattern in terms of nutrients content amongst the by-products. The in situ DM, organic matter (OM) and CP degradability differed amongst and within the sesame cakes, milling and brewery by-products. The wide variation in chemical composition, DM, OM, CP degradability, and ME obtained from this study offer farmers huge flexibility in formulating rations according to the productive performance of target animals.

木屑共热解活化钛石膏材料的吸附除磷性能研究

以工业副产钛石膏(TiG)为原料,与木屑共热解制备吸附材料(单独热解TiG-a与木屑共热解TiG-s),研究了不同pH、初始浓度、接触时间、共存物质等条件下TiG-s对水中磷酸盐的吸附性能和吸附机理。结果显示,木屑共存、氮气氛围、700℃热解条件下TiG-s的磷吸附容量是TiG-a的近20倍,计算饱和吸附容量112.6 mg/g;TiG-s对初始浓度小于25 mg/L的磷溶液去除率大于99%,吸附平衡TP质量浓度满足《地表水环境质量标准》(GB 3838-2002)Ⅲ类要求;水中共存物质对TiG-s吸附磷影响不明显。材料表征分析表明TiG-s比表面积BET小于10 m^(2)/g,物理吸附贡献少;溶液pH<3.5环境下TiG-s的Zeta电位为正,磷吸附机理为静电吸附和表面化学沉淀共同作用;FTIR、XRD、XPS图谱显示,更广泛pH条件下,TiG-s吸附磷以Ca-P表面化学沉淀为主。木屑共热解制备磁性钛石膏基吸附材料为钛石膏资源化利用、去除水中磷提供了新路径。

Mercury Speciation of Flue Gas Desulphurization By-Products in Coal-Fired Power Plants in China

The aim of this study was to develop and examine the morphology and distribution of mercury (Hg) in flue gas desulfurization (FGD) by-product. Mercury in the coal of coal-fired power plants is concentrated in the by-products of desulfurization process, and it is widely used as an additive in cement, building materials and other industries. Due to the different stability of various forms of mercury in the environment, subsequent use of products containing desulfurization by-product additives will continue to be released into the environment, endangering human health. Therefore, it is very necessary to study the form and distribution of mercury in the by-products of desulfurization in coal-fired power plants to provide a theoretical basis for subsequent harmless treatment. For content and morphology of mercury analysis, 1 sample of dry FGD ash and 6 samples of wet FGD gypsum were analyzed. The total 7 samples were extracted using a modification of sequential chemical extractions (SCE) method, which was employed for the partitioning Hg into four fractions: water soluble, acid soluble, H2O2 soluble, and residual. The Hg analysis was done with United States Environmental Protection Agency (USEPA) method 7471B. Comparing with the wet FGD gypsums of coal-fired boilers, the total Hg content in the dry FGD by-product was as high as 1.22 mg/kg, while the total Hg content in the FGD gypsum is 0.23 - 0.74 mg/kg, which was 2 times over the wet FGD gypsum. The concentration of water soluble Hg in the dry FGD by-product was the highest amount (0.72 mg/kg), accounting for 59.02% of the total mercury. While residual Hg content was 0.16 mg/kg, only about 13.11% of the total mercury. Mercury content in FGD gypsum was expressed in the form of ρ (residual Hg) > ρ (H2O2 soluble Hg) > ρ (water soluble Hg) > ρ (acid soluble Hg). The morphology and distribution of mercury in FGD by-products is supposed to be analyzed before utilization, and the impact of mercury on the environment should be considered.

大掺量磷石膏矿渣水泥的水化历程与长期强度研究

采用大掺量磷石膏、粒化高炉矿渣和熟石灰制备石膏矿渣水泥,通过水化热、化学收缩、孔溶液pH值和抗压强度试验,并结合XRD和SEM-EDS测试,探究磷石膏掺量对石膏矿渣水泥的水化历程与长期强度的影响规律。结果表明,当磷石膏的掺量从40%增大到70%(质量分数,下同)时,水泥浆体的第三放热峰峰值逐渐减小,14 d化学收缩从0.066 mL·g^(-1)增大到0.193 mL·g^(-1),早期(0~1 d)化学收缩速率明显增大,孔溶液pH值在28 d龄期内趋于稳定,且与28 d龄期相比,90 d龄期试件的抗压强度提高了12.3%~27.8%。XRD和SEM-EDS分析表明,水泥浆体中主要包含二水石膏、石英、钙矾石和C-S-H凝胶等物质。28 d龄期时,随着磷石膏掺量的增大,钙矾石的生成量从7.48%减小到2.84%,C-S-H凝胶的钙硅比(摩尔比)从1.08增大到2.24。

高效化学沉淀法处理磷石膏堆场渗滤液工程实例

某磷石膏堆场已堆放近30年,为了缓解堆场磷石膏利用期间的二次污染问题,修建渗滤液收集和处理设施。采用高效化学沉淀法对该堆场渗滤液进行处理,通过投加石灰对酸及污染物进行预处理,固液分离后清水进入三级化学反应沉淀系统,上清液经过滤和pH调节后出水。实际运行数据表明,该磷石膏渗滤液废水处理站出水水质正磷酸盐优于0.3 mg/L,其余主要指标达到《污水综合排放标准》(GB 8978—1996)一级排放标准,可为同类型磷石膏堆场治理工作提供工程实践经验。

不同土壤改良剂对陕北低洼盐碱地土壤理化性质及水稻产量和经济效益的影响

为探究不同土壤改良剂对陕北低洼盐碱地的改良效果,采用田间试验和室内分析相结合的方法,比较了3种土壤改良剂(脱硫石膏、“金阜丰”和腐殖酸)对土壤理化性质、水稻产量及经济效益的影响。结果表明,3种土壤改良剂均可有效降低土壤容重、改善土壤物理性质,降低土壤酸碱度。其中,腐殖酸可显著降低表层土壤含盐量;“金阜丰”土壤改良剂和腐殖酸对土壤有机质、全氮含量的影响达到显著水平,对速效钾、有效磷含量影响不显著;脱硫石膏对土壤速效钾含量的影响达到显著水平,对有机质、全氮、有效磷含量影响不显著。此外,施加土壤改良剂可以显著提升水稻千粒重和产量,与对照相比千粒重和产量分别增加10.19%~13.59%和13.54%~27.95%,其中,施加腐殖酸改良剂处理的水稻千粒重和产量最大,分别达到23.4 g和7380 kg·hm^(-2);通过经济效益分析发现,施加改良剂可以显著提升水稻产值和纯利润,其中,施加腐殖酸处理获得了最大的产值、纯利润和产投比,综合考虑稻米质量、水稻产量和经济效益,建议优先选用腐殖酸土壤改良剂改良陕北低洼盐碱地。

无水Ⅱ型石膏活性激发及应用研究现状

工业副产石膏由于杂质含量高制约了其资源化利用,目前采用的低温煅烧处理工艺无法有效脱除杂质,导致产品质量存在问题,通过高温煅烧可以有效解决该问题。综述了煅烧副产石膏制备无水Ⅱ型石膏的工艺控制条件,归纳了无水Ⅱ型石膏水化机理及各类型活性激发技术的特点,探讨了无水Ⅱ型石膏在化工填料和自流平砂浆方面的应用现状及开发前景,以期为工业副产石膏以无水Ⅱ型石膏的形式实现资源化利用提供参考。

Fate of mercury in flue gas desulfurization gypsum determined by Temperature Programmed Decomposition and Sequential Chemical Extraction

A considerable amount of Hg is retained in flue gas desulfurization（FGD） gypsum from Wet Flue Gas Desulfurization（WFGD） systems. For this reason, it is important to determine the species of Hg in FGD gypsum not only to understand the mechanism of Hg removal by WFGD systems but also to determine the final fate of Hg when FGD gypsum is disposed. In this study, Temperature Programmed Decomposition（TPD） and Sequential Chemical Extraction（SCE） were applied to FGD gypsum to identify the Hg species in it. The FGD gypsum samples were collected from seven coal-fired power plants in China, with Hg concentrations ranging from 0.19 to 3.27 μg/g. A series of pure Hg compounds were used as reference materials in TPD experiments and the results revealed that the decomposition temperatures of different Hg compounds increase in the order of Hg_2Cl_2〈 HgCl_2〈 black HgS 〈 Hg_2SO_4〈 red HgS 〈 HgO 〈 HgSO_4. The Hg compounds existing in FGD gypsums identified by TPD included HgCl_2, Hg_2Cl_2, Hg_2SO_4, black HgS and red HgS, of which mercury sulfides were the primary compounds. The results of SCE indicated that Hg was mainly distributed in the strongly complexed phase. The low Hg content in FGD gypsum increases the ambiguity of assigning extraction fractions to certain Hg species by SCE. The fact that the primary compounds in FGD gypsum are HgS phases leads the leaching of Hg in the natural environment to be quite low, but a considerable amount of Hg may be released during the industrial heating process.

高氯脱硫石膏中氯离子的调控技术研究进展

高氯脱硫石膏中所含氯离子杂质严重劣化了脱硫石膏的性能,限制了其在建材领域的高效资源化利用,因此开展高氯脱硫石膏中氯离子的调控技术研究势在必行。本文从氯离子的调控技术思路出发,归纳了物理吸附和化学改性技术在脱硫石膏氯离子调控方面的研究进展,并剖析了脱硫石膏中氯离子调控技术难度大的成因,最后展望了高氯脱硫石膏中氯离子调控技术的研究方向。本文旨在为脱硫石膏中氯离子的调控技术提供研究思路,为高氯脱硫石膏的资源化利用提供理论指导。

北寒水石的质量标准研究

目的:建立北寒水石的质量标准。方法:采用理化鉴别和红外光谱技术对北寒水石进行定性鉴定与红外光谱扫描分析,采用(乙二胺四乙酸)EDTA配位滴定法测定北寒水石中含水硫酸钙(CaSO4·2H2O)的含量。结果:经理化鉴别北寒水石样品表明该样品含结晶水和硫酸钙;采用红外光谱测定硫酸盐类矿物药的红外图谱,结合矿物药材的特点对北寒水石进行整体评价,得到12个特征峰。EDTA配位滴定法测定北寒水石中含水硫酸钙(CaSO4·2H2O)的含量,线性回归方程为:y=111.9x-0.515(r=0.9985),含水硫酸钙(CaSO2·2H2O)的含量在0.0500~0.2500 g范围内呈良好线性关系。所建立方法测定北寒水石中含水硫酸钙(CaSO2·2H2O)的含量为97.29%。结论:所建立的北寒水石定性定量测定方法准确简便,能够提供较为规范的质量评价依据。

实验室废液与脱硫石膏配施对碱土化学性质及苜蓿生长的影响

为研究实验室废液资源化利用途径,将实验室废液进行无害化处理后与脱硫石膏配施,进行碱土改良与栽培苜蓿的盆栽试验。通过比较各处理土壤pH、碱化度、电导率、全盐量、八大离子、有效氮磷钾和有机质含量及苜蓿出苗率、株高和地上部生物量,评价实验室废液与脱硫石膏配施对碱土化学性质的改善效果及其对苜蓿生长的效应。结果表明:实验室废液呈强酸性,通常pH<2,其主要污染物是汞(Hg)、镉(Cd)、铜(Cu)、锌(Zn)、镍(Ni)、铅(Pb)和六价铬(Cr^(6+))等重金属,其中六价铬超标,可以用活性炭(添加量0.8 g/200 mL)吸附(48 h)法进行无害化处理,使废液的六价铬含量达到灌溉水质标准,从而加以资源化利用。实验室废液与脱硫石膏适当配施对碱土化学性质有显著的改良作用,对苜蓿苗期的生长有显著的促进作用,其中w(脱硫石膏)=1.3%配施φ(实验室废液)=30%和w(脱硫石膏)=2.0%配施φ(实验室废液)=30%这2个处理的效果最为显著。

化学结晶反应对相似材料力学性质影响研究

相似材料的研制通常应避免材料组分之间产生化学反应。将化学反应引入以石膏作为胶结剂的相似材料中,硅酸钠与石膏发生化学反应,通过力学试验对比未发生化学反应和发生化学反应的两组试样的重度、单轴抗压强度、弹性模量、粘聚力、内摩擦角等5个参数表明:发生化学反应后,材料依然保持了高重度的特性,对内摩擦角影响也很小,单轴抗压强度、弹性模量、粘聚力等3个力学参数大幅降低,分别降低44.96%、36.63%、22.94%。

脱硫石膏基轻质保温材料的制备和性能研究

以建筑脱硫石膏为原料,分别通过物理发泡和化学发泡两种方式制备发泡石膏制品。通过测定石膏制品的抗压强度、导热系数、干密度等性能指标,评定发泡石膏工艺。结果表明,采用物理发泡法时,影响制品因素主次顺序为泡沫掺量>水胶比>HPMC掺量;采用化学发泡法制备发泡石膏制品时,发泡剂掺量直接影响发泡脱硫石膏的干密度、强度等性能,水灰比应控制在0.7左右,双氧水发泡剂掺量以6%为宜。

室内淋洗条件下脱硫石膏对滨海吹填土理化性质的影响

为改善吹填土的理化性质,实现吹填土在城市生态建设方面的充分利用,通过室内土柱淋洗试验,研究在不同施用量下脱硫石膏对吹填土各种离子动态变化的影响。结果表明:脱硫石膏可以显著改善滨海吹填土的理化性质,脱硫石膏施用量分别为0.7%,1.4%,2.1%,3种处理下土柱的饱和导水率分别是6.21,7.41,9.51mm/h;淋洗后土壤电导率、Na+和Cl-浓度、钠吸附比(SAR)和碱化度(ESP)等指标较淋洗前均有90%以上的降幅程度;且在前20h的淋洗过程中,各种化学指标的下降效果最为明显,而在将近150h的剩余时间内虽有下降,但下降速率很缓慢。

化工废石膏粉煤灰复合胶凝材料的改性研究

钛石膏是一种化工废石膏 .研究了热处理对钛石膏 粉煤灰复合胶凝材料物理性能的改性作用 .研究结果表明 ,采用低温煅烧可激发钛石膏的化学活性 ,大幅度缩短钛石膏 粉煤灰复合胶凝材料的凝结时间 ,提高强度 ,因此 ,该方法不失为一种行之有效的改善钛石膏

盐渍化土壤施用有机物-脱硫石膏改良剂效果的研究

研究了在盐渍化园田土壤上施用有机物与脱硫石膏混合改良剂对土壤理化性状和白菜产量的影响。试验采用改良剂的2种配方（成分比例不同）、3个施用量,以不施改良剂处理为对照,7个处理,3次重复。结果表明：施用有机物-脱硫石膏混合改良剂Ⅲ、Ⅳ可降低土壤容重最多为10.34%,11.30%;增加土壤总孔隙度最多达8.94%,9.84%。0-5 cm土壤全盐量由0.72%降至0.26%-0.46%;5-20 cm土壤全盐量由0.32%降至0.14%-0.19%。改良剂2种配方的不同施用量与对照相比,土壤ESP、pH、土壤交换性Na＋和土壤Cl-占阴离子总量分别下降了2.59%-16.28%,0.12-0.19,2.87%-24.53%和9.26%-213.05%。增加土壤SO42-和Ca2＋最多达137.45%和228.24%。与对照相比,白菜增产10.19%-30.99%。施用有机物-脱硫石膏混合改良剂不仅能够改善土壤的理化环境,同时也为作物提供了丰富的腐殖酸及Ca,S等营养物质。

不同盐碱地改良剂对土壤理化性质、紫花苜蓿生长及产量的影响

为明确国产化盐碱地改良剂在重度盐碱地的施用效果,采用田间试验和室内分析相结合的方法,以牧草和绿肥兼用型紫花苜蓿为供试作物,研究重度盐碱地施用国产1号（2 250 kg·hm-2）、国产2号（7 960kg·hm-2）和脱硫石膏（22 500 kg·hm-2）3种改良剂对土壤理化性质、紫花苜蓿（Medicago sativa L.）出苗率和鲜草产量的影响,以及施用脱硫石膏对土壤（0~20 cm）和紫花苜蓿茎、叶中重金属含量的影响。结果表明,与对照（不施改良剂）相比,施用改良剂处理的紫花苜蓿出苗率提高18.4%~31.7%,3茬鲜草总产量提高18.9%~43.5%;土壤pH下降0.11~1.46,容重降低0.01~0.06 g·cm-3、孔隙率提高1.15%~10.15%,土壤理化性状得到改善;施用脱硫石膏和含有脱硫石膏的国产2号使土壤和紫花苜蓿中汞、铅和铬含量有显著提高,但土壤重金属含量未超过国家《农业土壤环境质量标准》GB15618—2001规定的二级土壤使用标准,紫花苜蓿中汞、镉、铅和铬的含量检测符合国家饲料卫生指标（GB13078—2001）的规定。本研究表明,3种盐碱地改良剂以国产2号的施用效果最好,可在同类型盐碱地大力推广应用。