地聚合物混凝土配比及力学性能研究

混凝土是巷道支护过程中的重要建筑材料,然而混凝土在巷道施工中常常出现质量问题,为了不影响正常生产,需要对其进行修补。地聚合物混凝土凝结时间快,早期强度高,界面结合能力强,耐高温性和抗冻性强,耐腐蚀性良好,具有用作修补材料的潜力。以粉煤灰和矿粉为原料,Na₂SiO₃溶液和NaOH为碱激发剂制备地聚合物胶砂,研究不同的碱激发剂模数（1.0、1.2、1.4）和掺量（10%、15%、20%）对不同龄期胶砂力学性能的影响。结果表明：当碱激发剂模数为1.2,碱掺量为15%时,胶砂强度达到最大值。设计正交试验,研究了不同水胶比（0.45、0.50、0.55）、粉煤灰掺量（30%、50%、70%）和砂率（30%、35%、40%）对不同龄期地聚合物混凝土的工作性能和力学性能的影响。结果表明：粉煤灰掺量对抗压强度影响最为显著,水胶比次之,而砂率对强度发展几乎没有影响。最优的配合比为水胶比为0.50,粉煤灰掺量为50%,砂率为35%。     

Optimization study of sodium hydroxide consumption in the coal demineralization process

Demineralization study on flotation tailings coal with an objective to minimize the consumption of sodium hydroxide was explored. In the present work, the effect of process parameters such as pulp density (PD) of coal slurry, alkali (NaOH) concentration and reaction temperature on the ash content of product coal and NaOH consumption was investigated. Optimum process conditions were selected based on the minimum loss of NaOH and maximum PD (so that reactor volume required per ton of raw coal treatment can be minimized) along with the desired level of ash reduction. Experimental results shows that the consumption of sodium (Na) per unit ash removal increases with increase in alkali concentration for a given PD and at the same time decreases with increase in PD for a given alkali concentration. Furthermore, it was observed that the amount of Na consumption per unit ash removal is directly proportional to the reaction temperature.     

冶金竖炉反应器处理垃圾焚烧飞灰工艺

摘要：当前国内的生活垃圾大部分都依靠焚烧技术处理，相应地会产生大量急需无害化处理的危险废物─垃圾焚烧飞灰，目前采用冶金方法处理垃圾焚烧飞灰是一个新的研究方向。首先对垃圾焚烧飞灰的成分进行分析，并在此基础上，对垃圾焚烧飞灰的压块制度及高温性能进行了探究。造块实验结果表明，水分配比为20%（质量分数），水泥配比为10%（质量分数），成型压力为10MPa，养护时间为48h，飞灰压块的抗压强度达到了512N；高温性能实验以及热力学软件计算结果表明，飞灰的融化温度控制在1400～1550℃，碱度控制在1.0～1.2之间时，炉渣具有较好的流动性。     

氢氧化钠循环母液杂质对高铝粉煤灰预脱硅过程的影响

以高铝粉煤灰为原料进行预脱硅,在预脱硅过程中控制氢氧化钠循环母液中碳碱浓度和氧化铝浓度,研究两种杂质成分对预脱硅过程液相成分、液相黏度和脱硅粉煤灰铝硅比变化的影响。结果表明,随着循环母液中碳碱浓度的提升,液相中的氧化硅含量稍有下降,脱硅灰的铝硅比呈小幅下降趋势,循环母液中的碳碱浓度的提升会增大液相的黏度,对过滤过程不利,应将碳碱浓度控制在10g/L以下。循环母液中的氧化铝会与脱硅液中的氧化硅反应生成羟基方钠石等沸石类前驱体,从而降低脱硅液中的氧化硅浓度和脱硅灰的铝硅比,增加脱硅灰中化合碱含量,生产中循环母液中氧化铝浓度不应超过3g/L。     

碱法从粉煤灰中提取铝硅的新探索

碱石灰烧结法从粉煤灰中提取氧化铝的最佳工艺条件是:生料配比[N/R]为0.95,[C/S]为2.0,烧结温度1250℃,烧结时间30min;熟料溶出温度80℃,时间30min,调整液αK为1.60±0.05,氧化铝浓度10g/L,碳酸钠浓度12g/L;采用三段脱硅,精液硅量指数>600,精液分解温度90℃,种子加量20g/L。证明用粉煤灰碱-石灰烧结法生产氧化铝技术上可行,同时,提出了碱石灰烧结法生产粗氢铝后再重溶及低浓度处理粉煤灰联合生产水玻璃的工业应用改进途径。     

地质聚合物的制备与应用研究现状

地质聚合物是由硅铝酸盐原料经激发剂激发得到的一种无机非金属材料,具有原料来源广泛、制备工艺简单、碳排放量低、高强耐久等优点,应用前景非常广阔。介绍了地质聚合物及其性能特点,对制备过程中的原料活化、激发剂、外加剂和养护制度等工艺的研究现状进行了总结,列举了地质聚合物在胶凝材料、隔热吸音、催化剂和固封材料等领域的应用实例,并评述了其在制备及应用方面需要进一步探索的问题。     

某难浸金矿的次氯酸钠浸出研究

采用次氯酸钠对贵州某难浸金矿进行浸出,考察次氯酸钠浓度,浸出时间和温度对金浸出率的影响。结果表明,次氯酸钠不仅可氧化分解矿石中的FeAsS和FeS2,同时还可以打开包裹的金;在下述优化条件下,金浸出率可达到75%以上:次氯酸钠质量浓度0.6mol/L,pH 13～14,液固比6,35℃浸出4h。     

低浓度拜耳赤泥充填材料制备及水化机理

针对矿山充填中拜耳法赤泥利用率较低或低浓度赤泥充填材料存在强度低、泌水量高、易收缩等问题,研究粉煤灰添加比例、脱硫石膏、石灰及激发剂对赤泥充填材料早期强度及体积稳定性的影响,采用扫描电子显微镜-能谱仪（SEM-EDS）和X射线衍射（XRD）分析手段探讨赤泥基充填材料的水化机理。结果表明,脱硫石膏促进钙矾石的生成,石灰促进粉煤灰火山灰效应,激发剂可以加快赤泥?粉煤灰水化反应进程,三者协同作用提高赤泥充填体强度。充填材料28 d抗压强度3.35 MPa,且初始及60 min流动度在200 mm以上。微观实验表明,硬化体水化产物为钙矾石、硬柱石、硅铝酸盐凝胶类矿物,水化产物通过填充孔隙,提高浆体强度。赤泥基充填材料固体废弃物利用率达到92%,无泌水,无沉缩,具有较高的经济价值和环保价值。      

Electrical conductivity and dielectric property of fly ash geopolymer pastes

The electrical conductivity and dielectric property of fly ash geopolymer pastes in a frequency range of 100 Hz-10 MHz were studied.The effects of the liquid alkali solution to ash ratios(L/A)were analyzed.The mineralogical compositions and microstructures of ash geopolymer materials were also investigated using X-ray diffraction(XRD)and scanning electron microscopy(SEM).The 10 mol sodium hydroxide solution and sodium silicate solution at a sodium silicate-to-sodium hydroxide ratio of 1.0 were used in making geopolymer pastes.The pastes were cured at 400C.It is found that the electrical conductivity and dielectric constant are dependent on the frequency range and L/A ratios.The conductivity increases but the dielectric constant decreases with increasing frequency.     

废轮胎热解炭黑灰渣中锌提取工艺

废轮胎经煤油预处理后, 经热解生成炭黑, 之后煅烧生成灰渣, 针对废轮胎热解炭黑煅烧后灰渣中锌的提取进行了相关研究, 采用酸溶-分步沉淀法, 最终锌以氧化锌产品回收。分别采用4种无机酸(HCl、HNO₃、H₂SO₄及醋酸)对灰渣进行酸溶处理, 得出盐酸对灰渣酸溶效果最佳; 在此基础上, 考察了酸浓度、液固比(酸体积/炭黑质量)、浸出时间、酸解温度等因素对锌离子浸出效果的影响, 得到锌浸出的优化工艺条件为:酸浓度2 mo1/L、温度20 ℃、浸出时间60 min和液固比6:1 (mL/g), 在此条件下浸出锌离子的浸出率约为91.4%。经分步沉淀法对滤液进行沉淀、煅烧后, 得到纯度约为98.2%氧化锌产品, 灰渣中锌提取率达到81.4%左右。      

铝酸钠粗液氧化铝浓度对熟料溶出过程的影响

以脱硅粉煤灰熟料为原料进行熟料溶出,控制液固比得到不同氧化铝浓度的铝酸钠粗液,通过分析上述粗液在不同溶出时间溶液成分及固相成分的变化规律,研究溶出过程发生的二次反应历程。结果表明,随着氧化铝浓度的升高、溶出时间的延长,铝酸钠溶液中的氧化铝浓度和氧化硅浓度大致呈下降趋势;固相中氧化铝和氧化钠含量呈上升趋势,熟料氧化铝溶出率和氧化钠溶出率呈逐渐下降趋势。对于原硅酸钙含量大于50%的脱硅粉煤灰熟料而言,建议将铝酸钠粗液氧化铝浓度控制在100~120g/L,熟料溶出后浆液的液固分离时间控制在180min以内。在不同初始氧化铝浓度条件下,随着溶出时间的延长,二次反应产物及反应历程随着氧化铝浓度的变化而变化。溶出固相的主要产物为水化石榴石、钠硅渣、原硅酸钙和少量方解石。     

COMPARISON OF CLASS C AND CLASS F FLY-ASHES AS FOUNDARY SAND BINDERS AND THE EFFECTIVENESS OF ACCELERATORS IN REDUCING CURING TIME

Fly-ashes are a potential alternative to conventional bentonite to be used as binders for the production of foundry sand molds. The performance of two different fly-ashes in this application was evaluated. These fly-ashes were classified as a Class F (pozzolanic) ash and a Class C (pozzolanic and cementitious) ash according to American Society for Testing and Materials (ASTM) specifications. It was determined that both types of fly-ash could reach bonding strengths in the test specimens that were higher than that achieved with bentonite. However, the Class C ash required less than one-tenth as much curing time as the Class F ash to reach strengths comparable to those of bentonite-bonded specimens. It was also determined that the use of accelerators allowed the necessary curing time of Class C ash to be reduced to less than an hour.     

Use of Sewage Sludge Ash as Brick Material

Brick manufactured from incinerated sewage sludge ash and clay is investigated. The results of Atterberg limits tests of molded ash-clay mixtures indicated that both plastic index and dry shrinkage decrease with an increasing amount of ash in the mixture. Results of tests indicated that the ash proportion and firing temperature were the two key factors determining the quality of brick. Increasing the firing temperature and decreasing the amount of ash in the brick resulted in a decrease of water absorption. The appropriate percentage of ash content for producing quality bricks was in the range of 20 to 40% by weight with a 13 to 15% optimum moisture content prepared in the molded mixture and firing at 1,000°C for 6 h. With 10% ash content, the ash-clay bricks exhibited higher compressive strength than normal clay bricks. This study showed that the pulverized sludge ash could be used as brick material. The bonding strength can be further enhanced by controlling operating conditions.     

用粉煤灰在不同条件下合成A型分子筛

研究了在不同条件下高温碱熔融处理粉煤灰合成A型沸石分子筛,考察了不同碱熔融温度、不同灰碱质量比、不同水热晶化温度、不同水热晶化时间对产物的影响,用XRD、SEM和FT-IR等手段对产品进行了表征,研究结果表明,以粉煤灰为原料用水热合成法合成微孔分子筛时,在碱熔融温度为600℃,灰碱比为1∶2,晶化温度为90℃,晶化时间...     

锰浸出渣制备白炭黑的工艺研究

以工业锰浸出渣、氢氧化钠、硫酸为主要原料通过沉淀法制备白炭黑,研究了锰渣与氢氧化钠的配比、氢氧化钠浓度、反应时间、反应温度等因素对白炭黑回收率的影响。获得了制备白炭黑的最佳工艺条件为:反应温度为140℃、氢氧化钠/锰渣的质量比为0.8∶1、反应时间为8 h,白炭黑的回收率达到44%。通过红外光谱、TEM等技术表征了白炭黑的结构,粒径为50nm左右,经测试二氧化硅的含量达到90.5%,达到国家标准。     

固化剂对磷酸盐胶黏剂气密性的影响

以Al（H₂PO4）₃溶液为磷酸盐胶黏剂基体,研究了MgO、Al₂O₃、CuO三种固化剂对胶黏剂固化速率、固化温度、固化气密性的影响,分析了高温煅烧前后MgO和CuO对胶黏剂性能的影响。结果表明:MgO活性大,与Al（H₂PO4）₃基体反应迅速,不适合用作固化剂;以Al₂O₃为固化剂的胶黏剂密封性能差,Al₂O₃也不适合用作固化剂;未煅烧CuO作为磷酸盐胶黏剂的固化剂,反应速率适中且密封性能良好,当Al（H₂PO4）₃基体与CuO质量比为5.0:4.5时,气密性最好,为0.15 MPa（非上限）。     

Dobutamine maintains intestinal villus blood flow during normotensive endotoxemia: an intravital microscopic study in the rat

OBJECTIVE: This in vitro investigation compared the amount of linear shrinkage that occurs when a light-cured composite resin is cured with a visible light source, and also with an argon laser. SUMMARY BACKGROUND DATA: When composite resins are light-cured, they undergo a certain degree of polymerization shrinkage, which can be clinically significant and affect the efficacy of the restoration. A new protocol utilizes laser curing instead of conventional visible light. METHODS: Two hybrid composite resins were used, Z100 and TPH-Spectrum. Dimensional change was measured in a linear direction, using a calibrated light-microscope. A total of 40 samples of composite resin was tested using two curing lights, and two hybrid composite resins, resulting in four groups of 10 samples (n = 10) each. According to manufacturer instructions, curing time for the laser was 10 sec, and for visible light was 40 sec. RESULTS: With TPH-Spectrum, the mean shrinkage with visible light was 0.583% compared to that with laser light which was 0.591%. With Z100, the mean shrinkage with visible light was 0.565%, compared to that with laser light which was 0.551%. CONCLUSIONS: There was no significant difference in amount of shrinkage of hybrid composite resins between using visible light or laser light. There was also no significant difference in shrinkage between the two hybrid composites for either light source.     

高炉喷吹煤粉的灰熔融特性

 高炉喷吹煤粉的灰熔点太低会加速煤粉颗粒间的聚集及沉积,易导致风口或喷枪前结渣。同时,低灰熔点灰分熔化时会阻碍氧气进入尚未燃尽的煤粉颗粒内部,降低煤粉燃烧率。灰熔点太高,会影响高脱硫及炉渣的排放。因此,灰熔融特性是高炉喷吹煤粉不容忽视的性质。采用灰熔点测定仪和FactSage软件对济钢常用的贫瘦煤、无烟煤和烟煤的灰熔融特性进行对比研究。结果表明：两种方法得到的灰熔点结果具有一致性,煤的灰熔点与煤灰成分密切相关,煤灰的硅、铝含量高,灰熔点就偏高,钙、镁含量高,则灰熔点偏低。这为济钢高炉合理配煤提供了一项重要指标。     

氨—碳铵法浸出含锌烟灰

研究氨—碳铵体系中pH、总氨浓度、液固比(L/S)、反应温度、反应时间等因素对三种含锌烟灰中锌和主要杂质元素浸出行为的影响。结果表明,较佳的工艺条件是:浸出剂总氨浓度9mol/L、pH=10.00、L/S=5、反应温度50℃、反应时间60min。此时锌浸出率大于80%。     

从废荧光粉中回收稀土的工艺研究

研究了从废荧光粉(REO^12.00%)中回收稀土元素的工艺。采用碳酸钠焙烧-酸浸出工艺回收废荧光粉中的稀土,研究了碳酸钠加入量、焙烧温度、焙烧时间以及浸出条件对稀土回收率的影响。研究结果表明,碳酸钠焙烧试验的最佳条件为碳酸钠与荧光粉焙烧比例1∶2,焙烧温度700℃,焙烧时间1 h;焙烧产物用盐酸浸出,浸出试验最佳条件:盐酸浓度、液固比、浸出温度、浸出时间分别为3 mol/L、10∶1、70℃、2 h,在上述焙烧及浸出最优条件下,稀土总回收率(REO)达97%以上。