Characterization and availability of cyanide in solid mine tailings from gold extraction plants

The aim of this study was to investigate the availability and fate of cyanide in gold mill solid tailings. For this purpose, aged (6-9 years) and recently discharged (3 months) tailings were sampled at various depths from two gold mining sites in Quebec (Canada). A physicochemical characterization of the tailings along with a bacterial enumeration was performed and batch-leaching tests with water and caustic solution were conducted to assess the soluble cyanide fraction. Following the standard acid reflux/distillation method, the total cyanide concentration (CN(T)) in fresh tailings was higher (average of 19.5 +/- 2.0 compared to 3.2 +/- 0.7 mg/kg) and the pH more alkaline (10.6 +/- 0.1 compared to 7.6 +/- 0.2) compared to aged ones. In aged tailings, the enumeration of total heterotrophic (10(4)-10(6) cfu/g) and cyanide-resistant bacteria (10(2)-10(5) cfu/g) showed a significant indigenous microflora, but no growth on agar plates was detected in fresh tailings, suggesting an evolution and a gradual acclimatization of bacterial populations with weathering. Elevated concentrations of CN(T), weak acid dissociable cyanide (CN(WAD)), cyanate (CNO-), and thiocyanate (SCN-) were measured in the supernatant solution of the fresh tailings samples collected in-situ, highlighting their reactivity, whereas these species were not detectable in aged tailings. Accordingly, when batch-leaching tests were performed with fresh samples, 68-72% of the total cyanide was released into aqueous solution with more than 20% being CN(WAD). Again, CN(T) and CN(WAD) were not detectable during leaching of aged tailings. In fresh tailings, approximately 50% of the cyanides were quantifiable with the standard acid reflux/distillation method (readily soluble cyanides, and weak to moderately strong complexes), whereas in aged tailings only 15 to 33% of the actual total cyanide content was measured by the standard method. These results stress the necessity of performing a preliminary alkaline extraction prior to total cyanide determination. In summary, this study revealed a difference in physicochemical properties, cyanide concentration and speciation, viable bacterial populations and cyanide leaching behavior between aged and fresh solid mine tailings. The findings indicate that the more reactive cyanide species initially associated with the solid tailings have naturally degraded within the mine tailings impoundment area, resulting primarily from volatilization (decrease in pH), leaching, and bacterial degradation.     

Investigations of groundwater bursting into coal mine seam floors from fault zones

This paper presents a case study of investigations into retarded groundwater bursting along the fault zones in the seam floors in coal mines. In addition to in situ measurements of ground stresses, a number of rock samples from the fault zones at the site of the case study were taken, and laboratory tests were performed for conventional and special rheological rock mechanics properties. The effects of different parameters on deformation and failure of the fault zone materials were analyzed, and the mechanism of retarded groundwater bursting along fault zones was further revealed. In the case study, different scenarios accounting for the different development phases of the fault weakness zone and groundwater bursting as well as different groundwater pressures were considered, and each of them was simulated using the 3D visual elastic–plastic numerical mechanics model FLAC^3D (Fast Lagrangian Analysis of Continua in 3 Dimensions). Through the case study, the applicability of rock mechanics modeling software for studying retarded groundwater bursting along a fault zone was examined. Several issues are discussed regarding the investigations of retarded groundwater bursting and a general structured approach to investigate and control this geological hazardous event is presented.     

法国鲁昂试验路堤与大气相互作用数值模拟

 在土–大气相互作用的模型和计算方法的基础上，采用现场记录的气象数据，对法国鲁昂试验路堤中心轴线上的温度、体积含水量和吸力随气候的变化进行一维数值模拟，并与现场实测结果进行对比。数值计算模拟与现场实测结果的对比分析表明，计算所采用的模型是合适的，但需要设置合理的边界条件以及土性参数。另外，由于试验路堤的压实使得填土具有较低的渗透性(＜10－8 m/s)，因而该试验中大气降雨和蒸发对路堤含水量和吸力的影响主要局限于距离路堤表面一定深度范围内。     

HDPE土工膜端部张拉力的大规模实测数据分析

 垃圾填埋场边土工膜主要受到温度应力和垃圾压缩引起的张拉力的作用，为评价垃圾填埋场防渗系统中高密度聚乙烯(HDPE)土工膜的温度应力和垃圾填埋压缩引起的端部张拉力，以短纤维无纺布、HDPE土工膜组成防渗系统，进行大规模现场试验。试验结果表明：伴随环境温度的下降，HDPE土工膜中产生温度应力，当填埋高度较小时作用在HDPE土工膜端部的张拉力主要为温度应力；随着填埋高度的增加，压缩引起的HDPE土工膜端部张拉力增大。用有限元算法对压缩引起的端部张拉力进行分析，并采用温度与HDPE土工膜张拉力的关系对温度应力进行分析。计算结果与实测结果的对比情况表明，考虑填埋压缩引起的张拉力的应力松弛后计算结果更加接近实测结果。     

Ni2O3/CuO/Sb2O3:SnO2下转换材料光谱特性试验研究

以氧化锡为主要材料,掺杂过渡元素氧化物,采用高温烧结法制备了在1.06 μm处具有激光吸收性能的下转换粉体材料.对材料的1.06 μm激光吸收性能、晶相结构、表面形貌以及光谱下转换位移进行了表征.最后,将合成材料制备成涂料样品,测试1.06 μm激光吸收性能.结果表明,该材料对1.06 μm激光具有较高的吸收性能.     

μC/OS-Ⅲ在STM32F103RC 上的移植

针对在 STM32F103RC 处理器组建的系统上移植μC/OS-Ⅲ时需要一定移植条件的问题,介绍一种移植μC/OS-Ⅲ的方法,Cortex-M3内核处理器为μC/OS-Ⅲ移植带来的便利性以及μC/OS-Ⅲ移植工作中涉及到的3方面内容,重点说明μC/CPU移植文件编写与修改的细节,并详述基于STM32F103RC产品平台下的μC/OS-Ⅲ成功移植案例。实践结果表明：该方法具有可操作性,能够实现μC/OS-Ⅲ在STM32F103RC上的移植。     

P92大规格钢锭锻制管坯穿管断裂致因分析

摘要：某钢厂生产的P92大规格钢锭锻制管坯常出现穿管后产生裂纹的现象,为了探究裂纹产生的原因,在断裂管坯裂纹及附近区域取样,使用金相显微镜与扫描电镜分析裂纹宏观形貌和成分,并进行夹杂物评级与成分分布分析,对无裂纹产品进行高温拉伸试验,考察热制度是否合理。结果表明:穿管断裂样品均存在夹杂物评级超标的问题,未能在精炼过程上浮去除的脱氧产物与卷渣形成的大型夹杂物在穿管过程中引起应力集中,导致裂纹萌生、扩展。针对脱氧产物未被去除的问题,对钙质脱氧剂和铝脱氧剂的加入量进行调整,并延长RH处理结束的弱搅拌时间。针对卷渣带入的夹杂物,对保护渣成分进行优化,选用低熔点保护渣。结果表明这些措施较好地解决了裂纹萌生的问题,产品夹杂物评级合格,大尺寸夹杂物数量大为减少。     

基于STM32的光伏发电自动跟踪系统设计

目前在光伏发电领域,大部分太阳电池板都是固定安装的,为了提高电池板的发电量,设计了一套基于STM32的太阳电池板自动跟踪系统。系统通过步进电机带动双轴机构,实现了电池板对太阳的二维跟踪。本系统以低功耗的STM32为核心处理器,在外围设计了光电跟踪传感器,阴晴检测以及GPS等模块,采用混合跟踪的控制方式提高了跟踪精度。介绍了系统的原理与组成,设计了一套低功耗的间歇跟踪算法。     

基于Modbus协议的多路数据采集器

为了满足一般中远距离工业现场数据采集的要求,基于Modbus通信协议,设计了一种光照度、温湿度数据采集器系统.硬件方面,以STM32作为主控制器,采用传感器BH1750与DHT11分别采集光照信息与温湿度;软件方面,基于I2C协议读取光照度,并通过单总线协议读取温湿度,基于Modbus协议的RTU工作模式实现了与上位机的通信.系统测试表明,数据采集器运行稳定,与上位机间的通信准确可靠,且该多路数据采集器已成功应用于广西某段高速公路隧道照明系统.