In-situ measurement of mineral phase transition and kinetics in roasting process of Bayan Obo mixed rare earth concentrate by sodium carbonate

In this study, the Bayan Obo rare earth concentrates mixed with Na₂CO₃ were used for roasting research. The phase change process of each firing stage was analyzed. The kinetic mechanism model of the continuous heating process was calculated. This study aims to recover valuable elements and optimize the production process to provide a certain theoretical basis. Using X-ray diffraction (XRD), Fourier infrared spectroscopy, scanning electron microscopy with energy dispersive spectrometry, the reaction process and the existence of mineral phases were analyzed. The variable temperature XRD and thermogravimetric method were used to calculate the roasting kinetics. The phase transition results show that carbonate-like substances first decompose into fine mineral particles, and CaO, MgO, and SiO₂ react to form silicates, causing hardening. Further, REPO₄ and NaF can directly generate CeF₃ and CeF₄ at high temperatures, and a part of CeF₄ and NaF forms a solid solution substance Na₃CeF₇. Rare earth oxides calcined at a high temperature of 750 °C were separated to produce Ce_0.6Nd_0.4O_1.8, Ce₄O₇, and LaPrO_3+x. Then, BaSO₄, Na₂CO₃, and Fe₂O₃ react to form barium ferrite BaFe₁₂O₁₉; the kinetic calculation results show that during the continuous heating process, the apparent activation energy E reaches the minimum in the entire reaction stage in the temperature range of 440–524 °C, and the reaction order n reaches the maximum, which indicates that the decomposition product REFO significantly impacts the reaction system and reduces the activation energy. The mechanism function is F(α) = [?ln (1?α)]^1/3. The reaction order n reaches the minimum in the temperature range of 680–757 °C, and the apparent activation energy E is large. The difficulty of the reaction increases during the final stage. The reaction mechanism function is F(α) = [1?(1?α)^1/3]². Observing the entire reaction stage, the step of controlling the reaction rate changes from random nucleation to three-dimensional diffusion (spherical symmetry).     

Drivers of revitalization in Great Lakes coastal communities

Sediment remediation and habitat restoration projects have been increasingly employed along the coast of the Great Lakes to improve environmental quality since the designation of 43 highly degraded Areas of Concern (AOCs) by the 1987 Great Lakes Water Quality Agreement between the U.S. and Canada. Improvements in water quality, habitat, and other environmental conditions can also support community wellbeing and revitalization; however, the mechanisms that support these connections are relatively unclear. We address this gap through a case study of three AOCs near Lake Michigan: 1) Grand Calumet River; 2) White Lake, and 3) Muskegon Lake. By analyzing secondary data and planning documents, we found that alongside environmental cleanup, anchor institutions, housing and economic development, and local events drive revitalization. Our research also illustrates that, rather than acting as discrete processes, environmental cleanup and revitalization drivers overlap in time and space. Finally, our research reveals a high level of variation within and across AOCs in terms of diverse socioeconomic contexts, planning capacities, and existing partnerships. Together, our findings point to the need for collaborative and inclusive planning processes that account for the heterogeneity present within and across AOCs to simultaneously support remediation, restoration, and revitalization and to sustain continued revitalization in AOC communities after delisting.     

内蒙古某银铅锌矿选矿试验研究

对内蒙古含银铅锌矿石进行了浮选分离工艺研究。在查明矿石的主要矿物组成及嵌布特征的基础上,依据矿石特性采用铜铅混选-锌浮选的工艺流程进行选矿试验,从含银310.92g/t、铅6.10%、锌4.95%的矿石中获得含铅76.63%、含银3 659.74g/t、铅回收率为91.50%、银回收率为87.11%的铅精矿和含锌55.48%、含银282.84g/t、锌回收率为89.15%、银回收率为7.34%的锌精矿。实现了矿石中银、铅、锌的综合回收。     

对加快建设我国现代化天然气市场体系的战略思考

为了适应我国推动建设现代化市场体系、现代化经济体系和现代化能源体系的需求,应加快建设统一开放、竞争有序、体系完整、运维智慧的现代化天然气市场体系,以保障天然气市场在资源配置中的决定性作用。为此,根据国外天然气市场建设经验与启示,基于我国天然气市场发展的良好基础条件,集成创新提出了我国现代化天然气市场体系的架构,即由天然气产业链资源市场、要素市场、市场基础设施、市场结构、市场机制、市场制度(规则)和市场管理等7个子体系构成。进而提出了加快我国现代化天然气市场体系建设的政策建议:(1)切实推进天然气市场改革深化,为现代化市场体系建设提供组织保障;(2)强化天然气市场基础设施协同建设,推进市场智慧发展;(3)进一步理顺天然气价格体系,完善价格动态调整机制;(4)积极发展天然气科技与技术装备市场;(5)健全和完善天然气金融市场体系,规避市场风险;(6)健全天然气行业相关法律体系,保障公平开放透明的市场规则建立。结论认为:我国天然气市场已迎来大发展的新时代,应按照国家和市场化发展的要求,加快实现现代化天然气市场体系建设的目标,实现优质天然气清洁高效利用,以促进天然气市场在资源配置中发挥决定性作用。     

岩溶城市(贵阳市)水资源可持续利用评价研究

为研究贵阳市水资源可持续利用评价问题,基于DPSIR模型构建贵阳市水资源可持续利用评价指标体系,运用熵权法与综合指数模型测算2001~2015年贵阳市水资源可持续利用综合指数,并以障碍度模型对影响水资源可持续利用的障碍因子进行诊断。结果表明,2001~2015年,除压力指数外,驱动力、状态、影响、响应和综合指数均呈波动上升的趋势;可持续利用类型可划分为失调(2001~2006年)和协调(2007~2013年)两个阶段;人均GDP、万元GDP耗水量、森林覆盖率、三产增加值占GDP比重、生活污水处理率为5大影响贵阳市水资源可持续利用的重要因素。研究结果为贵阳市水资源可持续利用提供指导。     

Effect of CaO mineral change on coal ash melting characteristics

The change of mineral composition in ash and the effect of CaO on the melting characteristics of coal ash were studied by adding different contents of CaO to coal ash. At the same time, the Factsage thermodynamics software was used to simulate the mineral changes in the synthetic ash to support and verify the experimental results. The results show that with the increase of CaO content, the melting characteristic temperature of coal ash first decreases and then rises. After adding a certain amount of CaO, the quartz with higher melting point completely disappears, and the melting point of the coal ash reaches a minimum value. And with the increase of CaO content, the appearance of wollastonite and single crystal calcium oxide mineral makes the melting point of coal ash gradually increase. It can be seen from the phase diagram calculated by Factsage that as the CaO content increases, the corresponding position of the coal ash gradually moves from the hematite region to the calcareous region. And the phenomenon of low temperature eutectic occurs when the CaO content is 35%, which is consistent with the trend of temperature change of the melting characteristics. These phenomena all indicate that the change in the melting point of coal ash is nonlinear as the content of CaO minerals increases.     

污染价值损失模型在清潩河流域的应用研究

鉴于污染价值损失的核算对掌握流域水污染状况、制定科学合理的治理对策具有重要意义,通过分析污染物浓度跟水资源价值损失的关系,将水量、水质和水资源价值三者结合起来,从理论上构建了基于污染损失率和水资源价值的污染价值损失模型,且给出了完整的水污染经济损失量的数学表达式,并将其应用于许昌市清潩河流域水污染经济损失核算中。结果表明,清潩河流域水环境污染的经济损失在2011~2014年间呈现波动变化,2013年污染损失量最大,达到7 365.41万元。三个行政分区中,2011~2012年间长葛市水污染损失量最大,2013~2014年间许昌县水污染损失量最大,与当地的实际情况相符。可见该模型可行、有效。     

陕西省宝鸡市日月耦合降水随机序列模拟

为了生成可同时保持日、月尺度的关键统计特性的降水序列,提出一种日、月尺度耦合方法使模拟序列可在日、月尺度上均保持实测序列均值、方差和变差系数,该方法利用一阶马尔科夫链模拟干湿期,以两参数Gamma分布模拟降水量,并使用比例调整算法。对陕西省宝鸡市降水序列模拟的结果表明,耦合方法较好地保留了日、月尺度上原有的统计特性,且比例调整算法对日序列的调整较小。同时,耦合方法简单、适用性强,可用于其他尺度间的尺度耦合。     

Mineral composition and organic geochemistry of the Lower Cretaceous Xiagou Formation source rock from the Qingxi Sag, Jiuquan Basin, Northwest China

The Lower Cretaceous Xiagou Formation contains the major source rocks for the crude oils discovered in the Qingxi Sag and the South Uplift in the Jiuquan Basin, northwestern China. The Xiagou Formation source rock was formed in a closed, anoxic, reducing, alkaline lacustrine environment with a high salinity. Its high content of brittle minerals is favorable for the fracturing of reservoirs in source rock formations in the Qingxi Sag. The Xiagou Formation contains a great number of fair to excellent source rocks, and their organic matter (OM) came chiefly from plankton/algae and high plants as well as possibly bacterial organisms. The Xiagou Formation source rocks mainly contain Type II OM and some Type III and Type I OM, with good oil-generating potential. The source rock maturity is mainly in the early-mature and mature stages, and its R_o value corresponding to oil peak is about 0.8%, which is lower than classic oil peak Ro value of 1.0%; therefore, a great deal of hydrocarbon was generated before the classic oil peak R_o = 1.0%. Mature source rock in the Xiagou Formation tends to be distributed in the older members and at a greater depth. There is a better exploration potential of tight oil in the deep Qingxi Sag.     

含金黄铁矿选冶研究进展

我国金矿资源储量丰富,但难处理金矿比重较大,含金黄铁矿作为最主要的载金矿物,其中的金赋存状态复杂、伴生矿物种类繁多,导致开采和选冶困难。金在黄铁矿中的赋存状态可分为裂隙金、间隙金、表面吸附金、包裹金和晶格金,本文以此为基础,分别介绍了重选、浮选、化学浸出、生物处理的选别工艺的研究现状。