Preparation technology of ultra-fine powders of Auricularia auricular

Conventional mechanical method and mechanical method combined with vacuum freeze-drying technology were used to make the ultra-fine powders of edible fungus (Auricularia auricular). The content of basic nutrients, amino acid, micro structure and their properties of raw edible fungus and the edible fungus powders obtained with the two methods were analyzed and compared. The granularity size and micro-structure of the pulverized samples were analyzed by SEM and TEM technology. The average granularity size of the edible fungus powder obtained with mechanical method was 1–5 μm, while that obtained with mechanical method combined with vacuum freeze-drying process was 0.5–1 μm. The ultra-fine powders of edible fungus obtained with the two methods had better water recovery capability and quality, and their preserving time was longer than that of raw edible fungus. All the properties of the ultra-fine powders of edible fungus obtained with the vacuum freeze-drying technology were evidently superior to that of the conventional mechanical method. Keywords Auricularia auricula - Edible fungus - Ultra-fine powders - Vacuum freeze-drying CLC number TS205 Document code B Biography: YANG Chun-yu (1975), female, Ph. D. in Engineering Technology Center of Forestry and Wood Workine, Machinery, Northeast Forestry University, Harbin 150040, P. R. China.Responsible editor: Zhu Hong

Optimal Conditions for Preparing Ultra-Fine CeO_2 Powders in A Submerged Circulative Impinging Stream Reactor

Cerium carbonate powders were produced in a submerged circulation impinging stream reactor （SCISR） from Ce（NO3）3· 6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted to produce ultra-fine cerium dioxide （CeO2） powders. The optimal conditions of such production process were obtained by orthogonal and one-factor experiments. The results showed that ultra-fine and narrowly distributed cerium carbonate powders were produced under the optimal flowing conditions. The concentrations of Ce（NO3）3 and NH4HCO3 solutions were 02,5 and 0.3 mol · L^-1, respectively. The concentration of PEG4000 added in these two solutions was 4 g · L^-1. The stirring ratio, reaction temperature, feeding time, solution pH, reaction time and digestion time were 900 r · min^- 1,80 ℃, 20 min, 5 - 6, 5 min and 1 h, respectively. The final product, CeO2 powders, was obtained by roasting the produced cerium carbonate in air for 3 h at 500 ℃. The finally produced CeO2 powders were torispherical particles with a narrow size distribution of 0.8 -2.5 μm. The crystal structure of CeO2 powders belonged to cubic crystal system and its space point 5 group was OH^5-FM3M. Under optimal conditions, powders produced by SCISR were finer and more narrowly distributed than that by Stirred Tank Reactor （STR）.

DYNAMIC RHEOLOGICAL BEHAVIOR OF POLYPROPYLENE FILLED WITH ULTRA-FINE POWDERED RUBBER PARTICLES

Dynamic rheological characteristics of polypropylene (PP) filled with ultra-fine full-vulcanized powdered rubber (UFPR) composed of styrene-butadiene copolymer were studied through dynamic rheological measurements on an Advanced Rheometric Expansion System (ARES). A specific viscoelastic phenomenon, i.e. 'the second plateau', appeared at low frequencies, and exhibits a certain dependence on the amount of rubber particles and the dispersion state in the matrix. This phenomenon is attributed to the formation of aggregation structure of rubber particles. The analyses of Cole-Cole diagrams of the dynamic viscoelastic functions suggest that the heterogeneity of the composites is enhanced on increasing both particle content and temperature.

An improved sodium silicate binder modified by ultra-fine powder materials

This paper presents a new method of modifying sodium silicate binder with ultra-fine powders. The sodium silicate binder modified by ultra-fine powder A and the organic B can reduce the addition amount of the binder. The results indicate that the 24 h strength has increased by 39.9% at room temperature and the residual strength has decreased by 30.7% at 800℃, compared to the conventional sodium silicate. An available material to improve the moisture resistance was also found by adding about 2% more inorganic C, and it can increase the moist strength by 20%. In the end, the microanalyses are given to explain the modifying machanism, i. e., the ultra-fine powder A can refine the sodium silicate binder to avoid holes in the binder bond, which can increase the 24 h strength at room temperture, and can lead to more cracks in the bond after the molding sand is heated to 800℃. This is because of the stress caused by the new eutectic complex of modified sodium silicate binder.

Hydrogen Reduction:A Novel Method of Synthesizing Ultra-fine Chromic Oxide Powder

The ultra-fine chromic oxide powder was prepared by a novel gas-solid reduction reaction.Na2CrO4 was firstly reduced with hydrogen at 400-600 ℃.The obtained reduction products,mainly the mixture of NaCrO2 and sodium hydroxide（NaOH）,were converted into chromic oxide through hydrolysis followed by calcination.The obtained chromic oxide product was characterized by powder X-ray diffraction（XRD） and SEM.The results show that the hydrolysis process of sodium chromite is the key step and lower reduction temperature helps intensify the hydrolysis process.

Strengthening of HT250 by modified ultra-fine ceramic powders

In this study, three kinds of modified ultra-fine ceramic powders marked A, B and C, which were prepared by each of three different modifiers mixing with a commercial SiC, were added to HT250 cast iron, respectively, and the effects of the modified ultra-fine ceramic powders on microstructure, mechanical properties and wear resistance were studied. Metallographic examination, tensile test, scanning electron microscopy, and three-dimensional surface topography were applied to analyze and compare the samples containing modified powder with the original samples. The results showed that the most obvious modification effect among the powders was seen in the sample containing powder A, with the graphite and eutectic cells being refined, the tensile strength being increased by 36.9%, and the wear resistance being improved by 45.5% and 47.2% under loads of 150 N and 300 N, respectively. The improvements of mechanical properties and wear resistance in the HT250 cast iron with the modified ultra-fine ceramic powders were attributed to the synergistic effect of the grain refinement with the powder acting as a hard particle phase and the lubrication by the graphite.

Preparation of Ultra-fine Salbutamol Sulfate Particles by Reactive Precipitation and Characterization of Dry Powder Inhalant

The preparation of ultra-fine particles of salbutamol sulphate （SS） was accomplished with a reactive precipitation pathway, in which salbutamol and sulphuric acid were Used as reactants with the solvents of ethanol.The effects of sulphuric acid concentration, reaction temperature, stirring rate, and reaction time onthesize of the particle were investigated. A binary mixture composed of lactose and SS was prepared to evaluate SS. The results showed that ultra-fine SS particles with controlled diameters ranging between 3 μm and 0.8 μm and with a narrow distribution could be achieved. The morphology consisting of clubbed particles wassuccess.fully obtained. The purity of the particles reached above 98% with-UV detection. The dose- of dry powder inhalation was obtained by blending the particles with recrystallized lactose, which acted as a carrier. The deposition quantity of the drug in breathing tract was estimated using a twin imPinger apparatus. Compared with the Shapuer powder （purchased in the market）, the results showed that SS_particles had more quantifies.subsided in simulative lung.. _

Preparation of Well Dispersed and Ultra-Fine Ce(Zr)O_2 Mixed Oxide by Mechanochemical Processing

Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the crystalline Ce_2(CO_3)_3·8H_2O and ZrOCl_2·xH_2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce_(0.15)Zr_(0.85)O_2 mixed oxide with pure tetragonal phase structure and medium particle size(D_(50))less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O_2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.

从铂化合物制备尾液中回收超细铂粉的研究

将不同的铂化合物制备尾液经过氯化铵沉淀,实现与其他杂质元素的分离,将铂转化为氯铂酸铵中间体,经液相化学还原得到超细铂粉。研究了中间体形态、(NH_(4))2PtCl6溶液浓度、分散剂种类及加入量对铂粉粒度、比表面积、形貌的影响。结果表明,铂化合物尾液种类不影响超细铂粉的形貌及颗粒尺寸,以PVP为分散剂,硼氢化钠为还原剂,在优化条件下制备的铂粉平均粒度约150nm,纯度99.99%,直收率97.8%,颗粒形貌均匀、分散程度高、比表面积及颗粒尺寸均符合超细铂粉国家标准,方法可用于从多种铂类化合物制备尾液直接制备超细铂粉。

改性磷尾矿粉对红壤生境玉米生长及土壤理化性状的影响

通过玉米田间试验,研究改性磷尾矿粉对红壤生境玉米生长及土壤理化性状的影响,为磷尾矿的合理利用以及酸性红壤农田防治施肥技术提供理论依据。供试玉米试验地位于曲靖市马龙县旧县镇,设置如下处理:(1)当地习惯施肥(CK);(2)当地习惯施肥+改性磷尾矿粉3000 kg/hm^(2)(T_(1));(3)当地习惯施肥+改性磷尾矿粉6000 kg/hm^(2)(T_(2));(4)当地习惯施肥+改性磷尾矿粉9000 kg/hm^(2)(T_(3));(5)当地习惯施肥+改性磷尾矿粉12000 kg/hm^(2)(T_(4));(6)当地习惯施肥+改性磷尾矿粉15000 kg/hm^(2)(T5),每个处理3次重复,测定玉米产量和pH、有机质、交换性钙等土壤理化性质。结果表明:施用改性磷尾矿粉显著提高土壤pH,较CK最高提高了23.20%,显著降低了交换性酸总量、交换性Al^(3+)含量和有效锰含量,最高分别降低了79%、70%和29.18%;施用改性磷尾矿粉提高了土壤交换性钙,较CK,最高显著提升了38.19%;施用改性磷尾矿粉的百粒重最高较CK处理提高了4.03%,对玉米产量无显著影响。施用改性磷尾矿粉可通过降低土壤交换性酸,提高阳离子交换量、土壤交换性钙来消减土壤酸化,不同施用量的改性磷尾矿粉对土壤和玉米的影响有所差异,其中施用6000 kg/hm^(2)的改性磷尾矿粉(T_(3)处理)是最优的施肥方案,它可以在不影响玉米产量的前提下,最大程度地改善土壤理化性质,降低土壤酸化程度,增加土壤团聚体稳定性。

融合石膏组分和微纳米结构“双基因”调控的铁尾矿粉无熟料固结体力学性能

为了探究超细铁尾矿粉颗粒表面非晶态SiO_(2)和Al_(2)O_(3)在石灰-石膏体系中的水化固化机理及调控因素,本工作考察了石膏掺量和铁尾矿粉中微纳米级颗粒含量之间的匹配对固结体强度的影响,利用XRD、TG-DSC、SEM和化学滴定法测试分析了固结体试样中水化产物的种类、形貌及含量的变化,研究了这些变化对固结体强度的影响及作用机理。结果表明,超细铁尾矿粉中小于1.096μm的微纳米颗粒含量显著影响着铁尾矿粉在碱溶液中Si和Al元素的溶出行为,固结体强度随着这些微纳米颗粒含量的增加而提高。固结体中的主要水化产物是铝掺杂的水化硅酸钙(C-(A)-S-H)和钙矾石(AFt)。石膏掺量与铁尾矿粉中微纳米颗粒含量的最佳匹配值对固结体的强度具有显著影响,并且微纳米颗粒含量越高,对应的石膏最佳掺量越大。石膏组分保证了AFt的生成和稳定,同时也加速了铁尾矿粉颗粒表面非晶态成分的水化。本工作探明了固结材料中最佳石膏掺量与微纳米铁尾矿粉颗粒含量的关联关系及其机理,证实了微纳米级颗粒是无熟料固结体结构中的基本活性单元,石膏的掺入对微纳米颗粒的水化起到调控作用,水化后的微纳米颗粒演变为固结体的基本结构单元,这种组分和结构的“双基因”调控机制影响着固结体的力学性能。

铁尾矿粉对石灰石粉混凝土力学性能和氢氧化钙含量的影响

这是一篇陶瓷及复合材料领域的论文。本文研究了复掺铁尾矿粉和石灰石粉的掺量和比例对混凝土性能的影响。结果表明:随着复掺矿粉比例的不断增大,复掺矿粉混凝土强度均呈现出先增大后减小的变化规律,并在复掺矿粉比例为1∶2时取得较大值。在同一冻融循环次数作用下,混凝土质量损失率随着复掺矿粉比例的增大呈现出先减小后增大的趋势,而混凝土的相对动弹性模量却呈现出先增大后减小的变化趋势。在同一测定位置处,随着复掺矿粉比例的不断增大,复掺矿粉混凝土氯离子含量均呈现出不断减小,且在比例为1∶2时复掺矿粉混凝土氯离子含量的下降变快。综合实验结果得到,石灰石粉掺量为20%时混凝土的强度特性较佳,复掺矿粉比例为1∶2时混凝土的强度和耐久性均达到较佳。

三元固废掺和料耦合机理分析和活化

为实现铁尾矿固废材料的再生利用,提高工业固废利用率,利用陶瓷粉和钢渣组成三元固废掺和料(铁尾矿-陶瓷粉-钢渣)并耦合活化。通过对铁尾矿进行不同时间的机械研磨,加入不同活化剂进行化学活化来提高铁尾矿的活性。采用差热-热重(DTA-TG)分析、扫描电镜(SEM)等方法研究三元掺和料的耦合活化和机械-化学活化机理。结果表明,适当增加铁尾矿研磨时间可以提升掺和料体系的活性指数,Na2SiO3活化剂对掺和料体系活性提升最显著。在三元掺和料体系中,铁尾矿、陶瓷粉主要起填充作用,而钢渣中活性CaO、硅酸二钙(C2S)和硅酸三钙(C3S)成分可以参与水化反应生成较多水化产物,从而提升后期强度,复掺时活性指数均满足普通型Ⅱ级掺和料使用标准,最高活性指数可达88.29%,具备制备三元复合掺和料的潜力。

多元固废地聚合物的制备与性能研究

为实现尾矿等固废材料的再生利用,提高工业固废利用率,以铝土矿尾矿、矿渣和陶瓷粉为原料,NaOH-Na_(2)SiO_(3)复合溶液为碱激发剂合成多元固废地聚合物,研究复合激发剂在不同碱当量时对地聚物抗压强度的影响,并通过X射线衍射(XRD)、傅里叶红外光谱(FTIR)和扫描电镜(SEM)探究影响机理。结果表明,随着复合激发剂碱当量的增加,地聚物各龄期抗压强度呈先增大后减小的趋势,当复合激发剂碱当量为5%时,制品28 d抗压强度达到最佳值,为63.3 MPa。适当增加碱当量对抗压强度有利,但碱当量过大会导致抗压强度降低。微观分析表明,不同碱当量合成的地聚物均发生了一定程度的聚合反应,并生成了以水化硅铝酸钙(C-A-S-H)为主的无定形水化产物,聚合反应程度随着碱当量的增加而增大,微观结构则表现为基体更均匀致密。

钼尾矿粉作为水泥基材料掺合料的适用性研究

为了解决钼尾矿资源化利用的问题,以黑龙江伊春鹿鸣矿业的钼尾矿为原材料制备了磨细钼尾矿粉。通过标准稠度用水量、凝结时间、流动性、强度、活性指数、微观结构及水化产物等性能指标,研究了钼尾矿粉作为掺合料对水泥基材料工作性能、力学强度和微观结构的影响。研究结果表明:钼尾矿粉的掺入使水泥的标准稠度用水量增大了3.2%,初凝时间和终凝时间分别延长了75%和93%;且钼尾矿粉的掺入降低了砂浆流动度,增大了砂浆需水量比,降低了砂浆60 min流动度经时变化;随着钼尾矿粉取代率增加,砂浆的抗折强度、抗压强度、活性指数均逐渐降低,但砂浆7 d、28 d活性指数均大于60%;当钼尾矿粉取代率为30%时,净浆微观结构存在较少孔隙,但内部结构较为致密,且净浆中除钙矾石、氢氧化钙等水化产物,还含有SiO_(2)、长石、云母等钼尾矿粉中矿物。实验结果可为钼尾矿作为水泥基材料掺合料提供基础性实验数据。

尾泥微粉-粉煤灰-水泥复合胶凝体系性能研究

为了探究尾泥微粉在水泥基材料中应用的可行性,提高提锂尾渣资源利用率,利用提锂过程中产生的尾泥微粉与粉煤灰复掺后部分替代水泥,对尾泥微粉-粉煤灰-水泥复合胶凝体系的性能进行研究。结果表明:复掺适量提锂尾泥微粉与粉煤灰对复合胶凝体系流动性能有一定改善作用;复掺提锂尾泥微粉与适量粉煤灰部分替代水泥使得复合胶凝体系早期抗压强度略有降低,后期强度有明显增长。复掺5%(质量分数)提锂尾泥微粉与10%(质量分数)粉煤灰试验组的90 d抗压强度达到55.15 MPa,相比对照组提高了9.75%;复掺提锂尾泥微粉与粉煤灰在水化后期能够有效发挥复合活性效应与填充效应,促进水化产物生成并使其填充到大孔中,增加水泥浆体中毛细微孔(<10 nm)的比例,从而细化水泥浆体孔隙结构,提高体系致密度,宏观上表现为抗压强度增大。

固废资源合成堇青石工艺及其性能研究

为了合理利用固废资源、缓解资源紧张,根据堇青石的化学组成,以质量分数分别为12%的电熔镁砂收尘粉、40%的电熔刚玉收尘粉、48%的石英尾砂为原料,分别在1320、1350、1380、1390、1400、1410℃保温3 h煅烧,制备堇青石质耐火原料,研究了煅烧温度对堇青石试样相组成、显微结构、物理性能等的影响。结果表明:在1390℃之前,镁铝尖晶石和方石英逐渐反应生成堇青石直至方石英相完全消除,当煅烧温度达到1390℃时,试样中的堇青石相含量达94%(w),次晶相为镁铝尖晶石,此时试样的热膨胀系数最低,为3.2×10^(-6)℃^(-1),体积密度较低,为1.85 g·cm^(-3),热导率较低,为1.279 W·(m·K)^(-1),显微结构较致密,综合性能最优。

低硅铁尾矿制备轻质泡沫混凝土试验研究

为解决低硅铁尾矿堆存量大、利用困难等问题,以杨家湾尾矿库内低硅铁尾矿为矿物掺和料,水泥为胶凝材料,Al粉为发泡剂,制备轻质泡沫混凝土,并考察了水泥掺量、水料比、发泡剂Al粉掺量、激发剂CaO掺量等因素对泡沫混凝土性能的影响。结果表明:在铁尾矿掺量55%、Al粉掺量0.14%、CaO掺量5%、聚丙烯纤维掺量0.3%、稳泡剂掺量0.25%、水料比0.55的条件下,经20±1℃恒温恒湿养护28d,可制备出抗压强度1.84MPa、干密度768.61kg/m^(3)、比强度2.394×10^(-3)Nm/kg的轻质泡沫混凝土,综合性能良好,符合JG/T266—2011《泡沫混凝土》之A08干密度等级、C1强度等级要求。机理分析表明:孔隙率的过度提高会破坏制品内部的孔隙结构,对制品强度造成负面影响;铁尾矿的添加有助于混匀料浆,促进Ca(OH)2的生成,为料浆进一步创造碱性环境,促进钙矾石、C—S—H凝胶等水化产物的生成,其与铁尾矿的交织分布会支撑起孔隙结构,改善力学结构,使泡沫混凝土即使在较低密度下仍表现出较好的力学性能。

钨尾矿粉对水泥基3D打印混凝土流变、水化及力学性能的影响

采用钨尾矿粉(TTP)部分取代水泥制备3D打印低碳混凝土,研究了钨尾矿粉对复合浆体流变性能及水化特性的影响,在此基础上,通过调整外加剂用量优化打印性能,成功制备了不同钨尾矿粉掺量的3D打印低碳混凝土。结果表明:受颗粒堆积和体系总比表面积的影响,钨尾矿粉的加入会降低复合浆体的初始静态屈服应力、动态屈服应力和塑性黏度;受稀释作用的影响,钨尾矿粉的加入会降低复合浆体最初2 h内的水化放热,从而降低静态屈服应力增长速率;3D打印混凝土试件的抗压强度随钨尾矿粉掺量的增大逐渐降低,在钨尾矿粉掺量相同时,浇筑成型试件抗压强度略高于3D打印试件。当钨尾矿粉掺量在45%以内时,可制备出28 d抗压强度在30~60 MPa范围内的3D打印混凝土试件。在实际工程应用中,可根据不同场景的需求,确定适宜的钨尾矿粉掺量。钨尾矿粉具备作为3D打印低碳混凝土原材料的潜力。

铁尾矿粉混凝土在荷载与硫酸盐干湿循环耦合作用下的性能劣化机理

铁尾矿粉作为矿物掺合料应用于混凝土有助于固废高值化利用和节能减排,而关于铁尾矿粉混凝土抗硫酸盐侵蚀性能的研究,大多只考虑了单一条件或者加速条件环境,其在多种环境耦合下的劣化特征尚未得到探究.本文将铁尾矿粉作为矿物掺合料应用于混凝土中,以相对动弹性模量、质量损失率为性能指标,研究荷载-硫酸盐干湿循环耦合作用下铁尾矿粉混凝土劣化过程,探究铁尾矿粉掺量和荷载率对铁尾矿粉混凝土内部劣化的影响,结合扫描电镜(SEM)、X-ray衍射分析(XRD)、压汞(MIP)等微观手段揭示铁尾矿粉混凝土在耦合作用下损伤劣化机理.结果表明:适量铁尾矿粉的掺入有利于其与矿粉的协同水化作用,提高混凝土水化程度和基体密实度,减少硫酸根离子传输路径,提高混凝土抗硫酸盐侵蚀能力;荷载的施加使试块内部微裂纹宽度和数量增加,为硫酸根离子的进入提供更多渗透路径,加速铁尾矿粉混凝土损伤劣化过程;耦合作用使得铁尾矿粉混凝土内部损伤不断累积,在微观上表现为结构的疏松和裂缝的衍生扩展,在宏观上表现为力学性能的衰减和整体结构完整性的下降.