Investigation of the medium calcium based non-burnt brick made by red mud and fly ash: durability and hydration characteristics

Red mud is a type of highly alkaline waste residue produced in the process of alumina smelting by the Bayer process.Based on the idea of medium calcium content,solid wastes such as red mud and fly ash were used to prepare non-burnt bricks;and the mass ratio of CaO/SiO2 was selected in the range of 0.88–1.42.Mechanical properties and durability were investigated with a compressive strength test.X-ray diffractometry(XRD),scanning electron microscope(SEM),and Fourier transform infrared spectroscopy(FTIR)techniques were used to characterize the hydration characteristic.The environmental performance was analyzed by Inductively Coupled Plasma Mass Spectrometry(ICP).The results indicated that the mechanical properties and the durability were optimal when the mass ratio of CaO/SiO2 was 1.23.The hydration products were mostly C–S–H gel,ettringite,Na4Ca(Si10All6)O32·12H2O and Ca3Al2(SiO4)(OH)8.They were responsible for the strength development,and the CaO/SiO2 mass ratio of 1.23 had the best polymerized structure.The results of an environmental performance test showed that the heavy metals in the raw materials were well-solidified in the brick.Therefore,this paper provides an effective solution for use of solid wastes in building material.

An improved algorithm for mapping burnt areas in the Mediterranean forest landscape of Morocco

The identification of burnt forests and their monitoring provide essential information for the suitable management and conservation of these ecosystems. This research focuses on the use of remote sensing with MODIS sensor data in a Mediterranean environment, precisely in the Rif region known for its high occurrence of forest fires and the largest burnt areas in Morocco. It mapped the burnt areas during the summer of 2016 using spectral indices from MODIS images, namely the Normalized Burn Ratio (NBR) and the Burnt Area Index for MODIS (BAIM). Two field surveys were used to calibrate spectral indices and validate the maps. First, a monotemporal analysis using a single pre-fire image determined the appropriate threshold of the spectral indices (BAIM and NBR) for burn detecting. Secondly, a multitemporal method was applied based on dBAIM and dNBR images which represented pre-fire and postfire differences of the BAIM and NBR images, respectively. The results show that separate use of monotemporal postfire and multitemporal methods produced an overestimation of the burnt areas. Finally, we propose a new algorithm combining both methods for burnt area mapping that we name Burnt Area Algorithm. MCD45A1 and MCD64A1 MODIS burnt area products were compared to the proposed algorithm. Validation of the estimated burnt areas using reference data of the Moroccan High Commission for Water, Forests and Fight against Desertification showed satisfactory results using the proposed algorithm, with a determination coefficient of 0.68 and a root mean square error of 44.0 ha.

Petrologic and REE Geochemical Characters of Burnt Rocks

The study of burnt rocks is beneficial to the discussion on the tectonic movement, paleoclimate and paleogeography that coal seams are subjected to after they were formed. In order to obtain the basic data on the features of the burnt rocks, a systematic study of petrology and REE geochemistry on burnt rocks in Shenmu, Northern Shaanxi Province has been done, using the methods of SEM, EDS, susceptibility measurements and ICP-MS. The burnt rocks are divided into two series in the section： the melted rocks and the baked rocks. SEM and EDS analyses reveal that all the minerals show burnt and melted traces, and there are no clay minerals except illite found in the burnt rocks. Susceptibility measurements reveal that the burnt rocks have abnormally high susceptibility values, whereas a geochemical analysis shows that the REE distribution pattern of burnt rocks is similar to that of sedimentary rocks （initial rocks）. In the longitudinal section, with increasing degree of burning （from baked rocks to melted rocks）, the ∑REE gradually decreases, and the total REE of melted rocks is obviously lower than that of baked rocks. Besides, the melted rocks show apparent negative Ce anomalies, while the baked rocks show no anomaly of Ce, and sometimes even show positive anomalies.

Sensitive Evaluation on Early Cracking Tendency of Concrete with Inclusion of Light-burnt MgO

The advanced temperature and stress test machine was introduced to determine the early cracking tendency of concrete with inclusion of light-burnt MgO under full restraint by tracking the development of thermal,physical and deformation properties.Results showed that light-burnt MgO being incorporated ranging between 4 wt% and 6 wt% of cementitious materials was beneficial to increase the maximum compressive stress and cracking stress of concrete by 0.37 MPa and 0.2 MPa on average respectively.The second zero stress temperature was reduced by 11.4 ℃ and the maximum temperature was slightly reduced while cracking thermal impact was significantly enhanced from 59.8 ℃ to 66.2 ℃.Sensitive anti-cracking coefficient F was forwarded to assess the early cracking tendency of concrete and the inclusion of 4 wt% light-burnt MgO with activity of 109 s ranked the best in crack resistance.

Temperature field distribution of burnt surrounding rock in UCG stope

In order to study temperature field distribution in burnt surrounding rock and to determine ranges of burnt surrounding rock, coal-wall coking cycle and heat influence in the underground coal gasification(UCG) stope, based on the Laplace transform and inversion formula, we studied the temperature analytical solution of one-dimensional unsteady heat conduction for multi-layer overlying strata under the first and the forth kinds of boundary conditions, and we also carried out a numerical simulation of twodimensional unsteady heat conduction by the COMSOL multiphysics. The results show that when the boundary temperature of surrounding rock has a linear decrease because of a directional movement of heat source in the UCG flame working face, the temperature in surrounding rock increases first and then decreases with time, the peak of temperature curve decreases gradually and its position moves inside surrounding rock from the boundary. In the surrounding rock of UCG stope, there is an envelope curve of temperature curve clusters. We analyzed the influence of thermophysical parameters on envelope curves and put forward to take envelope curve as the calculation basis for ranges of burnt surrounding rock, coal-wall coking cycle and heat influence. Finally, the concrete numerical values are given by determining those judgement standards and temperature thresholds, which basically tally with the field geophysical prospecting results.

Forest structure, diversity and regeneration in unburnt and burnt Anogeissus latifolia forests in Garhwal Himalayas

The present study was carried out at two different gradients of unbumt and burnt Anogeissus latifolia forest sites in the Garhwal region, India. At each gradient, the unburnt and burnt forest sites were further categorized into three different elevations, i.e., lower （700 m）, middle （850 m） and upper （1000 m）. At each elevation, the density of trees, saplings and seedlings was higher at the unburnt sites except for trees at the upper elevation which was higher at the burnt sites. The total basal area of each layer of for- est was also higher at the unburnt sites. The study revealed that the lower number of saplings and seedlings at the burnt forest sites might be due to the effect of fire. Most trees in the lower dbh classes were affected by forest fire at the burnt sites which reduced the total density and total basal area of the trees compared to the unburnt sites. The diversity of trees increased with increasing elevation. However, the diversity of saplings and seedlings reduced with increasing elevation.

Adult with mass burnt lime aspiration: A case report and literature review

BACKGROUND Foreign body aspiration mainly occurs in children,which can cause a severe concurrent syndrome and even death without timely treatment.As a rare foreign body,aspiration of lime is seldom reported,and most cases involve a small amount of hydrated lime.Although the symptoms are usually severe,the prognosis is good after suitable treatment.Experience of treatment for lime aspiration is lacking,and this report provides novel evidence for treatment of mass burnt lime aspiration using bronchoscopy.CASE SUMMARY We report an adult with a large amount of burnt lime aspiration.Because of delay in clearance of the inhaled lime in the trachea and bronchus at the local hospital,he suffered several severe complications,including complete occlusion of the right primary bronchus,aeropleura,aerodermectasia,pneumomediastinum,secondary infection and hypoxemia at 4 d after injury.After transferring to our department,bronchoscopy was immediately carried out to clear the lime in the major airway,using foreign body forceps,biopsy forceps,puncture needle,and hairbrush.The patient’s condition recovered rapidly and at 3-months’follow-up,he demonstrated good recovery of the bronchus and lung parenchyma.CONCLUSION After mass lime aspiration,flexible fiberoptic bronchoscopy is suggested as early as possible,using clamping,flushing or cryotherapy.

Distributions of rare-earth elements in two Chinese coals and their burnt products

The concentrations of two fresh Chinese coals (lignitie and fatty coal ) from dif-ferent geological origin and the corresponding fly and bottom ashes were determined us-ing inductively coupled plasma mass spectrometry(ICP-MS). The ranges and means of concentrations of these elemennts were given. Based on the combustion simulating ex-periment in the one-dismensional boiler, the contents of REE (rare-earth element) of 18 samples in lignite, fatty coal and their fly and bottom ashes in different combustion condi-tion were determined, and geochemical feature of REE were analyzed.

“Burnt-Out” Endomyocardial Fibrosis—An Overview

Tropical endomyocardial fibrosis (EMF) is a public health problem affecting the children, young adults and elderly individuals in an epidemic fashion in the coastal districts of south India. Due to lack of resources for research in these endemic areas, its etiology remains elusive and hypotheses ranging from infections and allergic causes to malnutrition and toxins have not been tested rigorously. The disease is characterized by endocardial fibrosis and the right ventricle is the cardiac chamber most frequently affected. Patients may present clinically with heart failure and an associated AV (atrioventricular) valve regurgitation is common. Several features of the advanced disease called as “burnt-out” stage of endomyocardial fibrosis (EMF) are not fully understood. Background of these case studies described the clinical presentation, echocardiographic features and management of this late stage of the disease.

Disaster victim identification operations with fragmented,burnt,or commingled remains:experience-based recommendations

Human-made and natural disasters can result in severely fragmented,compromised,and commingled human remains.The related disaster victim identification(DVI)operations are invariably challenging,with the state of the remains potentially precluding some identifications.Practitioners involved in these DVI operations will routinely face logistical,practical,and ethical challenges.This review provides information and guidance derived from firsthand experiences to individuals tasked with managing DVI operations with fragmented human remains.We outline several key issues that should be addressed during disaster preparedness planning and at the outset of an operation,when incident-specific strategies are developed.Specific challenges during recovery and examination of fragmented remains are addressed,highlighting the importance of experienced specialists at the scene and in the mortuary.DNA sample selection and sampling techniques are reviewed,as well as downstream effects of commingling and contamination,which can complicate reconciliation and emphasise the need for rigorous quality control.We also touch on issues that may arise during communication with families.While recommendations are provided,they are not intended as proscriptive policy but rather as an addition to the general recommendations given in the International Criminal Police Organization(INTERPOL)DVI Guide,to inform preparative discussions between government officials,judiciary,police,and forensic specialists.

Preparation and Metallurgical Analysis of High Activity Burnt Lime for Steelmaking

Burnt lime is an important material in steelmaking and its activity degree is a key factor for liquid steel quality. The burnt lime was made by the calcination of limestone in a high pressure electric furnace. The burnt lime mineralogical phases and micro-morphologies were characterized by X-ray diffraction （XRD） and field emission scan- ning electron microscopy （FE-SEM）. The burnt lime activity degree was determined by acid-base titration, the burnt lime pore distribution was measured by mercury intrusion porosimetry （MIP）, and the thermal effect of a mixture of burnt lime and slag was measured by differential scanning calorimetry （DSC）. The results showed that the CaO grain size and pore size of burnt lime made under high pressure were larger than those of burnt lime made under atmos- pheric pressure. The CaO grain size and pore size increased and the laminate phenomenon also occurred clearly under high pressure. The activity degree of burnt lime made under high pressure was greater than that made under atmos- pheric pressure. The maximum activity degree was 437 mL for burnt lime made under a pressure of 0.4 MPa. For the same ratio of CaO to SiOz, the melting temperature, hemisphere temperature and fluidity temperature of slag decreased with increasing burnt lime activity degree. The higher the activity degree the burnt lime had, the better the slag forming occurred. It was advantageous for -2CaO · SiO2 and 3CaO · SiO2 forming at lower temperatures if the burnt lime activity degree was increased.

Burnt Rubber

Driving away Chinese tires has not benefited the U.S. tire industry, but has harmed their trade ties Two years after imposing punitive tariffs on Chinese-manufactured passenger vehicle and truck tires, the United States may launch a new round against truck and bus tires imported from China, reported 21st Century Business Herald based in Guangzhou, capital of Guangdong Province.

陕西省煤矿典型水灾隐患特征及治理技术

陕西省煤炭资源丰富,2022年煤炭产量达7.46亿t,是我国主要产煤省份之一。由于全省煤矿区地质及水文地质条件差异明显,煤矿水灾类型多样,随着近年煤炭开采强度的增大,水灾事故时有发生,防治水形势较为严峻。以煤炭赋存条件为基础,系统总结区域水文地质结构特征,界定典型水灾类型及各类水灾影响区域分布,论述典型水灾的形成机理及特征,并提出了相应的防控技术。研究表明:(1)陕西省主要煤炭产区分为陕北、黄陇、渭北三大区,陕北侏罗纪煤田主要有顶板松散沙层水灾隐患、厚层砂岩水灾隐患、溃水溃沙灾害,局部区域分布有烧变岩对煤矿造成水灾隐患;黄陇煤田主要受顶板巨厚砂岩水灾隐患、离层溃水隐患、泥砂溃涌灾害隐患威胁;陕北石炭—二叠纪煤田和渭北煤田,主要受到煤层底板奥陶系灰岩水灾隐患威胁。(2)陕北侏罗系煤田顶板水灾隐患主要为顶板含水层受开采导水裂隙带扰动形成,导水裂隙波及砂岩含水层或松散沙层可形成持续大流量涌水,部分区域充水强度较大,在短时间水量较大超过排水系统能力时造成顶板水灾,在薄基岩区域垮落带直接导通松散沙层时可转变为溃水溃沙灾害,导水裂隙带影响到烧变岩富水区域时可形成瞬时水量大且持续的烧变岩水灾;黄陇煤田顶板巨厚砂岩含水层受采动导水裂隙带波及形成高强度持续涌水并可能形成顶板水灾,当含水层下部隔水层厚度较大时,可能形成离层溃水灾害,当近煤层顶板岩层松软遇水易崩解时可转变为泥砂溃涌灾害;陕北石炭—二叠纪煤田和渭北煤田,煤层开采底板扰动破坏带或断层等构造导通奥陶系灰岩含水层时,会引发极为严重的底板突水灾害,该类灾害具突发性强、瞬时水量大的特征。(3)各区域的顶板水灾隐患治理技术主要包括钻孔疏泄、注浆治理、开采参数控制等,底板水灾隐患治理技术主要包括区域注浆加固及封堵等;烧变岩水灾隐患主要采取帷幕注浆与钻孔探放有机结合的防治技术。

某大型集装箱船中间轴承故障分析与处理

某大型集装箱船为系列船,其中有2条船发生了同样的中间轴承轴瓦烧毁故障,因此开展该型船故障原因分析尤为重要。通过对推进系统的设计、安装调试和运营记录等多方面进行问题排查,并进行失效分析,还原故障的发生过程,分析故障的发生机理,从而提出了改进措施。通过故障案例分析,可为推进系统类似故障分析及处理提供经验和参考。

玄武岩纤维对C40混凝土高温后碳化的抑制作用

隧道衬砌混凝土的碳化问题尤为突出,而玄武岩纤维混凝土(BFRC)作为适用于隧道结构的高性能混凝土,其在常温下和火灾后的碳化机理尚不明确。开展了C40混凝土和玄武岩纤维混凝土的高温试验和快速碳化试验,监测了BFRC碳化深度的发展规律。基于半经验半理论模型,引入混凝土高温烧损层深度和高温后碳化速率等参数,建立了BFRC高温后碳化深度预测模型,分析了玄武岩纤维对混凝土高温后碳化深度发展的抑制作用。结果表明:掺入适量玄武岩纤维后,混凝土常温下碳化速率降低为原来的82%,高温烧损层深度大大降低,高温后碳化系数随温度的升高降低比例从21.5%达到37.5%,明显抑制了高温对混凝土碳化发展的影响,从而显著提高了混凝土的抗碳化性能。

气相色谱-质谱法测定加热卷烟气溶胶中14种焦甜香成分

建立气相色谱-质谱法测定加热卷烟气溶胶中14种焦甜香成分释放量。采用直线型吸烟机,在HCI(加拿大深度)抽吸模式下对加热卷烟进行抽吸,采用剑桥滤片对加热卷烟气溶胶进行捕集,用二氯甲烷溶液萃取剑桥滤片,萃取液经过滤后用气相色谱-质谱法测定,以选择离子监测(SIM)模式采集质谱数据,以D8-苯乙酮作为内标定量分析。14种焦甜香化合物的质量浓度在0.1~80μg/mL范围内线性关系良好,相关系数均不小于0.998,方法检出限为0.004~0.028μg/mL,定量限为0.012~0.093μg/mL。空白样品加标回收率为85.0%~110.0%,测定结果的相对标准偏差为5.84%~9.48%(n=5)。该方法简单快速、测定结果准确可靠,适用于加热卷烟气溶胶中14种焦甜香成分的定量测定。

烧变作用下巷道劣化围岩破坏机制与控制技术

针对烧变岩巷道围岩力学性能显著偏低的问题,以王才伙盘煤矿烧变岩区3202工作面回风巷为研究对象,利用Hoek-Brown修正准则求解了巷道围岩各分区应力及塑性区半径解析表达式,揭示了围岩稳定性的关键影响因素;明确了烧变岩区围岩控制策略,阐述了巷道浅部注浆和主、被动支护控制原理;对无支护、锚杆(索)支护以及浅部注浆+主被动联合支护等3种支护方式的围岩应力分布、变形特征、裂隙发育以及支护系统受力特征进行了模拟。研究结果表明:巷道松动圈主要与地质强度指标、岩体破碎度等因素密切相关;综合理论计算和现场实测结果,得到松动范围为4.2 m;3种支护方式拉应力峰值分别为1.14,0.85和0.81 MPa;偏应力峰值距巷道表面的最大距离分别为2.59,1.44和0.83m;顶板最大移近量分别收敛于350,205和24 mm;采用“注浆+锚杆(索)+金属架棚”支护形式,可在围岩浅部形成稳定承载点,实现有效支撑,同时锚杆、锚索支护作用得到充分发挥。现场工程实践结果显示,采用联合支护方式,巷道顶板及两帮移近量均小于50mm,有效稳定了烧变岩区的巷道围岩。研究成果可为同类地质条件下的巷道围岩控制提供参考。

隐伏火烧区烧变岩含水层水害治理技术研究

我国西北地区烧变岩分布范围广、孔隙裂隙发育、富水性强,是当地的主要含水层,其中的隐伏火烧区烧变岩地表遗迹不明显、发现难度大,煤矿开采一旦导通烧变岩含水层将导致水害事故,同时会破坏烧变岩含水层水资源。为治理隐伏火烧区烧变岩水害并保护烧变岩含水层水资源,分析我国烧变岩分布特征及烧变岩水对煤矿开采影响,研究隐伏火烧区烧变岩探查和治理技术,开展隐伏火烧区烧变岩含水层水害治理的示范应用,结合现场监测数据分析评价陕西柠条塔煤矿南翼隐伏火烧区含水层水害治理和水资源保护效果。结果表明:我国烧变岩主要分布于以昆仑山-秦岭-大别山为界的北方地区,隐伏烧变岩主要分布在鄂尔多斯盆地东北部、伊犁盆地南缘,被第四系松散层覆盖;隐伏火烧区烧变岩含水层与风化基岩含水层大多直接接触且连为一体,水力联系密切;烧变岩水害防治措施主要有留设烧变岩含水层防隔水煤柱、疏降烧变岩含水层积水和帷幕截流,其中截水帷幕可有效解放烧变岩含水层压覆的煤炭资源,解除烧变岩水害威胁并保护烧变岩含水层宝贵的地下水资源;通过精确探查出隐伏火烧区范围、布设注浆钻孔,将隐伏火烧区烧变岩含水层隔离为若干个含水体,断绝截水帷幕内外的水力联系,可保障工作面不受烧变岩水威胁,同时实现烧变岩水资源保护;柠条塔煤矿S1232工作面和S1233工作面隐伏火烧区烧变岩含水层治理后,其回采期间涌水量降至20m^(3)/h以内,工作面得以安全回采,截水帷幕内侧水位下降,外侧水位逐渐抬升,烧变岩水资源得到有效保护。

烧变岩矿物相特征及其转化

【目的】烧变岩作为一类由煤层自燃烘烤围岩形成的特殊岩石,在鄂尔多斯盆地东北缘延安组广泛发育,该类岩石中烧变相关的矿物相特征及形成机理尚不清楚。【方法】对陕西张家峁煤矿井下烧变岩进行分析测试和原岩高温加热模拟,进行烧变岩矿物相特征分析。【结果和结论】研究发现:井下烧变岩中铁镁质成分富集,Zn、Rb、Sr、Zr等微量元素相较原岩异常迁移,稀土元素Eu迁出,La/Yb−ΣREE分配模式更接近花岗岩。显微镜下烧变岩发育绿泥石化、磁铁矿化和赤铁矿化,发育变余结构和矿物烧熔现象,同时发育高温变质结晶矿物,如方石英、鳞石英、莫来石和堇青石。烧变岩变质作用类型主要为重结晶作用和熔融作用,缺少典型热变质岩中的交代蚀变或同化混染作用,也不发育含水或含羟基矿物,这种特征可能是由于烧变作用条件为近地表低压和开放环境,其变质作用体系内无H2O流体作用于矿物间的物质交换。结合烧变作用条件和矿物组合特征,认为烧变作用是不同于其他热变质作用的特殊变质类型。综合前人和本次研究,将烧变岩变质相作为一类特殊的热接触变质作用提出,按变质温度由低到高将其分为4个阶段:(1)低温脱水相阶段(绿泥石化、含水矿物被破坏)、(2)中温氧化相阶段(磁铁矿化、赤铁矿化)、(3)高温烧熔相阶段(莫来石、堇青石、方石英和鳞石英)、(4)完全熔融相阶段(辉石、假玻璃质长石)。研究对烧变岩矿物相及其转化做了系统总结,并在变质岩相系及其变质条件研究的基础上总结烧变相系,认为温度和近地表低压开放体系是不同烧变岩相形成的原因。

浓香型基酒中糊味特征物质解析

为探究浓香型白酒基础酒糊味特征物质,采用顶空固相微萃取-气相色谱-质谱联用技术,对浓香型白酒正常基酒和带有糊味基酒的风味成分进行分析。结果显示,两类基酒检测出139种风味物质,其中20种差异性物质可用于区分两类酒体,聚类热图分析结果表明2,4-二叔丁基苯酚、月桂酸乙酯、己酸丁酯、辛酸己酯、庚酸庚酯、己酸戊酯、己酸己酯、己酸和辛酸9种风味物质在糊味基酒中含量较为突出。感官重组、缺失、添加实验结果表明浓香型白酒中糊味的表征并不是由单一化合物引起,而是多个化合物的相互作用。本研究发现2,4-二叔丁基苯酚和酯类物质与浓香型基酒中糊味的表征有重要联系。