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采用结晶动力学方法对Li2 O :B2 O3=1 :4和 1 :5在 2 0 %LiCl-H2 O中的过饱的溶液在 2 0℃时的结晶动力学过程进行了研究 ,两种不同Li2 O :B2 O3(摩尔比 )配比的过饱和溶液均析出LiB5O8·5H2 O一种固相 ,通过X -ray粉末衍射、IR光谱和热分析对结晶析出固相进行了表征。同时拟合给出了结晶动力学方程 ,并对结晶反应机理进行了探讨。 相似文献
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用动力学方法对标题体系过饱和溶液的结晶过程进行了研究,MgO:B_2O_3(mol比)为1:2、1:5和1:7时的结晶固相分别为多水硼镁石、三方硼镁石和硼酸,与MgCl_2浓度为28％时的结果对比表明,MgCl_2浓度越低,该四元体系溶液过饱和度越小,因此,液固相关系也变得比较简单,在本文研究的浓度条件下出现了多水硼镁石固相,而MgCl_2浓度为28％时却没有,拟合出结晶动力学方程,对结晶机制进行了探讨。 相似文献
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以细粒高钠光卤石为原料,研究光卤石中的细粒氯化钠对氯化钾品位的影响,并探讨其原因。实验结果表明光卤石中含有的细粒 NaCl会严重降低 KCl品位,细粒 NaCl浮选夹带不是导致 KCl品位降低的主要原因。溶解速率实验结果表明,光卤石中的细粒 NaCl溶解速度较快,溶液中 NaCl浓度很快达到较高值,随溶液 MgCl2浓度不断升高,新生 NaCl晶体析出量增加, NaCl和 KCl之间的共生晶体数量增加,新生 KCl和 NaCl晶体之间的共生现象是导致 KCl品位降低的主要因素。 相似文献
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以盐湖卤水为原料提取并制备Li2CO3的过程中,共存离子对其结晶过程影响较大,尤其西藏盐湖卤水为原料制备碳酸锂的原料中,K/Li约为0.3左右,所以研究K+对Li2CO3晶体的影响具有重要意义。本研究通过实验和计算模拟相结合研究不同K/Li条件下K+对Li2CO3晶体的影响程度,建立晶体中K+含量与比表面积关联式。实验结果表明,K+的存在对Li2CO3的高品质性影响较大,且随着钾离子含量增加,晶体比表面积增大易于吸附杂质离子,表面粗糙度增强,且K+存在对碳酸锂晶体的收率影响较大,而当K/Li控制在0.1以内时,K+对碳酸锂晶体的影响相对较小;通过第一性原理计算,计算并分析了K掺入碳酸锂晶体中的几何结构、缺陷形成能及态密度,结果表明K原子在碳酸锂晶体中更易替代晶体中的Li原子,且K原子的掺入对碳酸锂晶体的晶格参数以及电子结构性质的影响较小。本文对西藏盐湖高效提锂和制备高附加值碳酸锂晶体提供理论依据。 相似文献
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以盐湖卤水为原料提取并制备Li2CO3的过程中,共存离子对其结晶过程影响较大,尤其我国西藏盐湖卤水为原料制备碳酸锂的原料中,K/Li约为0.3左右,所以研究K+对Li2CO3晶体的影响具有重要意义。通过实验和计算模拟相结合研究不同K/Li条件下K+对Li2CO3晶体的影响程度,建立晶体中K+含量与比表面积关联式。实验结果表明,K+的存在对Li2CO3的高品质性影响较大,且随着钾离子含量增加,晶体比表面积增大易于吸附杂质离子,表面粗糙度增强,且K+存在对碳酸锂晶体的收率影响较大,而当K/Li控制在0.1以内时,K+对碳酸锂晶体的影响相对较小。通过第一性原理计算,计算并分析了K掺入碳酸锂晶体中的几何结构、缺陷形成能及态密度,结果表明K原子在碳酸锂晶体中更易替代晶体中的Li原子,K原子的掺入对碳酸锂晶体的晶格参数以及电子结构性质的影响较小。对西藏盐湖高效提锂和制备高附加值碳酸锂晶体提供了理论依据。 相似文献
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Bedded trona (Na2CO3·NaHCO3·2H2O) in the lacustrine Green River Formation of Eocene age in the Green River Basin, southwest Wyoming, constitutes the largest known resource of natural sodium carbonate in the world. In this study, 116 gigatons (Gt) of trona ore are estimated to be present in 22 beds, ranging from 1.2 to 11 meters (m) in thickness. Of this total, 69 Gt of trona ore are estimated to be in beds containing less than 2 percent halite and 47 Gt in beds containing 2 or more percent halite. These 22 beds underlie areas of about 130 to more than 2,000 km2 at depths ranging from about 200 m to more than 900 m below the surface. The total resource of trona ore in the basin for which drilling information is available is estimated to be about 135 Gt.Underveloped trona beds in the deeper southern part of the basin may be best developed by solution mining. Additional unevaluated sodium carbonate resources are present in disseminated shortite (Na2CO3·2CaCO3) in strata interbedded with the trona and in shallow sodium carbonate brines in the northeast part of the basin. Estimates of the shortite and brine resources were not made. 相似文献
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合理开发利用四川盆地地下卤水资源,对卤水体系开展多温相平衡与相图的研究具有重要意义。本文通过等温溶解平衡法对在288 K时五元体系NaCl+KCl+MgCl2+SrCl2+H2O(NaCl饱和)进行了相平衡实验研究,运用化学分析法以及X-ray粉晶衍射法分别确定了在288 K温度条件下该体系的平衡液相和平衡固相组成。通过固液相平衡实验数据,绘制了该五元体系以NaCl为饱和区域的干盐相图、水含量图以及氯化钠含量变化图。研究结果表明在288 K且NaCl饱和条件下,该五元体系干盐相图含有2个五元共饱和点、5条等温溶解度曲线和4个固相结晶区(KCl、MgCl2·6H2O、KCl·MgCl2·6H2O和SrCl2·6H2O)。固相结晶区KCl在该干盐相图中面积最大,其次是SrCl2·6H2O,而MgCl2·6H2O的结晶区面积最小,说明KCl在饱和溶液中的溶解度较小,易析出而得到分离,而MgCl2的溶解度最大,难以从饱和溶液中结晶析出,且MgCl2·6H2O对KCl和SrCl2·6H2O有强烈盐析作用。通过对本体系热力学相平衡实验研究和多温相平衡的对比讨论,揭示了钾锶镁等含氯化物卤水体系在多温相平衡与相图条件下的结晶析盐规律,为液态矿产资源开发利用提供理论指导。 相似文献
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Prescribed fire in a Great Basin sagebrush ecosystem: Dynamics of soil extractable nitrogen and phosphorus 总被引：1，自引：0，他引：1
Pinyon and juniper have been expanding into sagebrush (Artemisia tridentata) ecosystems since settlement of the Great Basin around 1860. Herbaceous understory vegetation is eliminated as stand densities increase and the potential for catastrophic fires increases. Prescribed fire is increasingly used to remove trees and promote recovery of sagebrush ecosystems. We quantified the effects of prescribed fire, vegetation type, and time following fire on soil KCl extractable nitrogen and NaHCO3 extractable phosphorus in a pinyon–juniper woodland and its associated sagebrush ecosystem immediately before and for 4 years after a spring prescribed burn. Potassium chloride extractable NH4+ and total inorganic-N increased immediately following prescribed fire, and extractable NO3− decreased immediately after the burn. In the surface layer (top 8 cm), extractable NH4+ remained elevated compared to the control through year 2 after the burn. By the first fall post-burn extractable NO3− and total extractable inorganic-N increased and remained elevated over the control through year 3 after the burn in the surface layer. For the entire soil profile (52 cm), the burn had no effect on NH4+, and the effects on total extractable inorganic-N were no longer significant after year 1. However, NO3− remained elevated over the control through year 2 post-fire for the soil profile. Near surface NaHCO3 extractable ortho-P increased immediately following fire, and remained elevated through year 2 post-fire. No fire effects were observed for extractable ortho-P in deeper horizons. Our data show that plant available nitrogen can remain elevated for extended periods following prescribed fire. This can influence regrowth and seedling establishment of native plant species, invasion of exotic plant species and, ultimately, site recovery potential. 相似文献
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为了获取锂钠钾共存硫酸盐体系298.2 K下各盐结晶形式,采用等温溶解平衡法研究了298.2 K下四元体系Li2SO4+Na2SO4+K2SO4+H2O的相平衡关系,测定了该体系的溶解度和密度,采用X-ray粉晶衍射法测定了平衡固相组成,并绘制了相应的稳定相图和多温对比图。研究表明,298.2 K下该四元体系为复杂四元体系,有复盐2Li2SO4·Na2SO4·K2SO4、Li2SO4·3Na2SO4·12H2O、LiKSO4、Na2SO4·3K2SO4生成。其稳定相图由6个四元共饱点、12条单变量曲线以及7个结晶区组成。其中,复盐Na2SO4·3K2SO4结晶区最大,表明其在该体系中最易结晶析出;Li2SO4·H2O结晶区最小。对比273.2 K、288.2 K、298.2 K、323.2 K、373.2 K四元体系多温相图可知,273.2 K时未发现复盐Na2SO4·3K2SO4和2Li2SO4·Na2SO4·K2SO4结晶形式;Na2SO4·10H2O和Li2SO4·3Na2SO4·12H2O结晶形式在323.2 K和373.2 K时转变为Na2SO4和Li2SO4·Na2SO4。288.2~373.2 K时随温度升高,K2SO4和Na2SO4·10H2O结晶相区减小,Li2SO4·H2O、Na2SO4、LiKSO4和Li2SO4·Na2SO4结晶相区增大;Na2SO4·3K2SO4结晶相区先增大后减小,在298.2 K时结晶相区最大;2Li2SO4·Na2SO4·K2SO4结晶相区先减小后增大,298.2 K时结晶相区最小。 相似文献
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大气CO2浓度升高和施氮对棉田土壤理化性质及微生物区系的影响 总被引：2，自引：0，他引：2
针对耕地非农转化过程中产生的一系列社会问题,采用参与性农户调查方法,对西部欠发达地区西宁市郊区5个样本村190户农户进行了随机入户调查。根据城市开发进程、到市区距离和种植类型等条件,将调查样本村分为近郊城区化农村、近郊农村和远郊农村,就农户对耕地非农转换的基本认知及耕地非农转换的经济、社会和环境价值感知进行分析。结果表明:耕地征用后农户能理性感知和判别耕地非农转换价值,并普遍认为失去耕地后生活费用增加、生活保障降低、收入来源和就业机会少;感知主要受耕地数量、区位条件、耕地开发阶段等因素的影响;处于不同区位条件的农户对耕地非农转换的价值感知存在差异性,城区化农户已逐渐适应城市生活,近郊农户的非农转换经济和社会感知压力最大,远郊农民也感知经济和生活保障压力,但更希望能通过打工增加收入。 相似文献
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Seed germination and early seedling growth are crucial stages for plant establishment. Two neutral (NaCl and Na2SO4) and two alkali (NaHCO3 and Na2CO3) salts were selected to investigate their effects on germination and recovery responses in Reaumuria soongorica. Results show that both salt types significantly reduced germination and radicle elongation. The rate of germination and emergence of R. soongorica seeds continuously decreased as salinity increased, and the time to achieve maximum germination rate was delayed. The speed of seed germination dropped rapidly as salt concentration increased. Alkaline salts restricted the germination rate of R. soongorica seeds, and stresses resulting from alkaline salts and high concentrations of neutral salts resulted in many deformed seedlings. The length of the radicle and germ decreased with increasing salt concentration, but certain concentrations of salt and increased pH promoted germ growth. The results of regression analysis show that salt concentration was the dominant factor inhibiting R. soongorica seed germination rate. Salinity, buffering capacity, and pH all affected embryo growth, but salinity had the most pronounced effect. Seed viability under highly saline conditions appears to be a better indicator of adaptation to saline environments than seed germination under saline conditions. 相似文献