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1.
在反应体系pH≤1．5时，硅灰石与盐酸快速反应，经40－100min反应后，体系分为固液两相，固相为水合 二氧化硅沉淀及少量酸不溶性杂质矿物，液相为以溶胶形式存在的二氧化硅和大量CaCl2；当反应pH值在0．3－0．6时，液相中以硅溶胶形式存在的二氧化硅量最大，占总量46％以上。快速反应中仍存在少量具有慢速反应特征的柱状颗粒，该颗粒中心CaSiO3很难反应完全。快速反应产物经表面积较大，若在酸反应前添加有机助剂聚乙二醇（PEG）,反应pH值在0．3－0．6。反应时间40－100min，反应后用KOH溶液中和到pH＝4，可制备高比表面积多孔SiO2，比表面积＞430m^2／g，孔径1－2nm。 相似文献
2.
硅灰石与盐酸反应合成高比表面积多孔SiO2 条件为pH值≤ 1.5 ,添加剂为聚乙二醇和NH4Cl,反应后体系中和到pH =4.0 ,经固液分离 ,烘干 ,6 5 0～ 75 0℃灼烧 2h得产物。产物比表面积 479± 45m2 g ,表观密度 0 .34± 0 .0 3g cm3 ,DBP吸着率 173± 16ml 10 0g ,平均中位径D50 为 6 .9± 0 .5um ,孔径分布集中在 1～ 2nm。上述结果得到透射电镜分析证实。 相似文献
3.
根据红土镍矿中镁橄榄石的存在形式,采用高温固相法合成Mg2SiO4,通过正交试验优化Mg2SiO4在高浓度氢氧化钠中的浸出过程,利用XRD对浸出反应渣进行物相分析,探讨了液固比、氢氧化钠浓度、反应时间和反应温度对Mg2SiO4中SiO2的浸出率的影响。结果表明:Mg2SiO4在高浓度氢氧化钠中浸出过程优化实验条件为,反应温度220℃,反应时间120min,液固比6∶1,NaOH浓度85%;浸出反应渣的XRD分析结果表明:NaOH介入硅酸盐晶格中,其中间产物为Na2MgSiO4,Mg2+经过碱熔融过程可以脱离SiO4阵列,以Mg(OH)2形式从其硅酸盐中得以释放。 相似文献
4.
根据红土镍矿中镁橄榄石的存在形式,采用高温固相法合成Mg2SiO4,通过正交试验优化Mg2SiO4在高浓度氢氧化钠中的浸出过程,利用XRD对浸出反应渣进行物相分析,探讨了液固比、氢氧化钠浓度、反应时间和反应温度对Mg2SiO4中SiO2的浸出率的影响。结果表明:Mg2SiO4在高浓度氢氧化钠中浸出过程优化实验条件为,反应温度220℃,反应时间120min,液固比6∶1,NaOH浓度85%;浸出反应渣的XRD分析结果表明:NaOH介入硅酸盐晶格中,其中间产物为Na2MgSiO4,Mg2+经过碱熔融过程可以脱离SiO4阵列,以Mg(OH)2形式从其硅酸盐中得以释放。 相似文献
5.
采用多顶砧高压实验装置研究了Mg2SiO4-MgAl2O4体系在压力为22 GPa,温度为1550～1750℃条件下的相变,并考查了Al2O3在γ相中的固溶度.结果表明,随着体系中MgAl2O4组分含量的增加,相组合发生了变化,依次为γ相+镁铝硅酸盐固溶体+方镁石→镁铝硅酸盐固溶体+方镁石→镁铝硅酸盐固溶体+方镁石+刚玉固溶体;镁铝硅酸盐固溶体具有石榴子石结构,其化学成分随着体系中共存相的改变而有所变化;Al2O3在γ相中的固溶度很低(其重量百分比＜0.8%),因此,在Mg2SiO4-MgAl2O4体系中Al2O3可能对γ相超尖晶石分解转变的压力不会有很大的影响. 相似文献
6.
直接酸溶法浸取硫铁矿烧渣中铁的实验研究 总被引：4，自引：0，他引：4
对常压下用盐酸直接酸溶提取硫铁矿烧渣中的铁进行了实验研究，探讨了影响硫铁矿烧渣酸溶的因素。结果表明，影响铁溶出率的主要因素为液固比、反应时间和温度；当液固比为4．0mL／g、反应温度100℃时，高速搅拌反应2h后，铁的溶出率可达72％，浸取液经进一步处理可生产氯化铁系列产品，有较好的应用前景。 相似文献
7.
蒙脱石对黄曲霉毒素B1的吸附作用 总被引：5，自引：0，他引：5
试验研究了蒙脱石对黄曲霉毒素B1的等温吸附，以及赖氨酸、酸碱度、温度、离体肠管吸收和透析袋透析对其吸附的影响。结果表明：蒙脱石在pH2．0和pH8．0时对黄曲霉毒索B1的最大吸附量分别为613．5和628．9μg/g；赖氨酸含量为2～4mg／mL时对吸附无影响；酸碱度在pH2．0至pH8．0及温度在20℃至60℃时对吸附无明显影响；蒙脱石可减少离体肠管对黄曲霉毒素B1的吸收率及黄曲霉毒素B1通过透析袋的透析率。鸡小肠对黄曲霉毒素B1存在主动吸收过程。在吸附反应的初始阶段，蒙脱石对黄曲霉毒素B1的吸附符合一级吸附动力学方程，黄曲霉毒素B1半衰期为6．3～7．3min；20min后达到吸附平衡。 相似文献
8.
江西雅山黄玉锂云母花岗岩属典型的华南[富氟高磷花岗岩（P2O5＝0．15％－0．55％），表现为富氟（F＝1．07％－2．04％），强过铝性（A／NKC＝1．26－1．60），具有很高的Li,Rb,Cs,Be,Nb,Ta含量和很低的Y、REE含量.磷锂铝石是雅山黄玉锂云母花岗岩中的主要磷酸盐矿物，其产出与否同体的Li,Rb,Cs含量密切相关；磷锂铝石和长石矿物都是雅山黄玉锂云母花岗岩中磷的主要贮体，并且相互之间呈互补关系，当出现磷锂铝石时，磷锂铝石为全岩磷的主要贡献者，当无磷锂铝石晶出时，长石矿物为全岩磷的主要贡献者，体系的强过铝性以及很低的REE，Y，Ca含量使得磷灰石，独居石，磷钇矿都难以达到饱和结晶，磷灰石为少量出现，并且大部分为晚期形成；独居石和磷钇矿都为极少出现，反映出雅山岩体演化过程中具有独居石，磷钇矿等稀土磷酸盐矿物的结晶分离，铍磷酸盐矿物－羟磷铍钙石的出现反映了雅山黄玉锂云母花岗岩存在岩浆期后的含Be,Ca热液流体的作用。 相似文献
9.
成岩作用中的地下水碳酸体系与方解石溶解度 总被引：4，自引：1，他引：4
方解石在沉积岩成岩环境中的溶解度与地下水化学特征、温度等有着极为密切的关系。地下水碳酸体系中各碳酸组分的比例是溶液pH值的函数,可溶性CO2、HCO3-和CO32-分别在pH≤pK1的酸性介质、pK1≤pH≤pK2的弱酸至中性介质和pH≥pK2的碱性介质中具有绝对数量。而地下水体系中碳酸总量及各组分的变化受到pH值、气相CO2分压PCO2及固相方解石的溶解-沉淀效应的控制。通过限定溶液中离子的电价平衡和质量守恒约束条件可以确定各种温压环境中的地下水组成及方解石的溶解度特征。溶液pH值和温度是方解石溶解度的最直接的控制因素,且方解石的溶解随pH值不同分别在强酸、弱酸和碱性介质中表现出不同的反应方式。基于质量守恒条件,溶液中初始[ΣCO2]-[Ca2+]值对中性至碱性介质中的方解石溶解度带来很大的影响,当[ΣCO2]0<[ca2+]0有利于方解石的溶解,当[σco2]0>[Ca2+]0时有利于方解石的沉淀。如果CO2—H2O—CaCO3体系同时受到电价平衡和质量守恒条件的约束,则方解石只在酸性介质中溶解,碱性介质中沉淀。新疆塔里木盆地库车坳陷克拉2气田及相关储层中方解石分布特征表明,该区碎屑岩储层中方解石的大量沉淀发生于重碳酸钠型地下水环境中,而孔隙度极好、次生孔隙发育的储集段则出现于氯化型的地下水环境,从而验证了成岩作用中地下水类型对方解石溶解—沉淀的控制机制。 相似文献
10.
观察了三种吸附剂吸附亚砷酸根离子过程中溶液pH值随时间的变化。氢氧化铁在吸附过程中的pH值变化大致可分为三个阶段，0～6分钟为第一阶段，体系的pH值快速上升，指示亚砷酸根置换了固相中的氢氧根；7～40分钟为第二阶段，pH值变化不大，指示Fe(OH)3凝胶对亚砷酸根离子的吸附达到动态平衡；40分钟后为第三阶段，溶液的pH值呈单边下降趋势，这一阶段吸附剂与被吸附的阴离子之间发生了缩合反应，并释放出H＋。Mg-Al-LDO在吸附亚砷酸根的反应过程中pH值持续上升，它具有从水溶液中获取阴离子以恢复其前驱体结构的能力，这一反应中有氢氧根生成；Mg-Fe-LDO兼有前两者的吸附机理，吸附反应过程pH值的变化趋势此介于二者之间。氢氧化铁在加热前后吸附容量变化不大，25C和90C时分别为69.7mg/g和73.7mg/g，而Mg-Al-LDO和Mg-Fe-LDO的吸附容量在25C时分别为62.4mg/g和82.5mg/g，在90C时分别增加到114.9 mg/g和199.0 mg/g。Mg-Al-LDO和Mg-Fe-LDO在90C条件下吸附容量的大幅增加，可能和溶解CO2的干扰被抑制有关。 相似文献
11.
12.
页岩的微观孔隙结构对页岩气的赋存至关重要,气体吸附法可以较好对页岩的微观孔隙结构进行表征。通过测量丁页1井不同深度样品的矿物含量、RO值和TOC含量,结果表明丁页1井龙马溪组页岩样品的矿物含量比较稳定,有机质成熟度变化不大,均为过成熟。通过低温氮吸附法计算样品的比表面积和微、介孔容积和孔径分布,结果表明：（1）样品的平均孔径为2.8 ~ 4.9 nm,10 nm以下的孔隙提供了大部分的微、介孔容积。微、介孔容积为0.00136 ~ 0.0108 cm3/g,平均0.004 cm3/g,比表面积为2.54 ~ 13.69 m2/g,平均6.68 m2/g;（2）微、介孔容积、比表面积和TOC三者之间有很强的正相关性。通过计算TOC含量为0时的微、介孔容积和比表面积推算无机孔和有机孔之间的比例和其对比表面积的影响,发现有机孔提供了大部分的微、介孔容积,有机孔还是比表面积的主要贡献因素;（3）样品的吸附曲线符合IPUAC分类中的第IV型吸附曲线,样品的脱附曲线反映样品孔隙形态随TOC含量的增加,由楔形孔（不定型孔）变为连通的墨水瓶型孔（狭缝型孔）或墨水瓶型孔。 相似文献
13.
Joan D. Willey 《Geochimica et cosmochimica acta》1980,44(4):573-578
In three separate experiments, one using a bicarbonate buffered aqueous NaCl solution and two using natural seawater. the solubility of chemically pure X-ray amorphous precipitated silica decreased by approximately 20‰ after aging in contact with solution for several months. The specific surface area of the silica decreased by approximately half during the same experimental time periods. The solubility decrease in buffered NaCl solution occurred at both 2 and 22°C and over the pressure range from 1.01 × 105 to 7.45 × 107 Pa (1–740 atm). The aging process which causes the solubility and surface area decreases may be caused by the formation of a smooth surface silica layer that is more dense than the original surface. No change in the bulk chemistry of the silica could be defined after aging. This short term aging process contributes to the scatter in published solubilities for amorphous silica in seawater. 相似文献
14.
Jacques Schott Robert A Berner E.Lennart Sjöberg 《Geochimica et cosmochimica acta》1981,45(11):2123-2135
The short term (2–40 days) dissolution of enstatite, diopside, and tremolite in aqueous solution at low temperatures (20–60°C) and pH 1–6 has been studied in the laboratory by means of chemical analyses of reacting solutions for Ca2+, Mg2+, and Si(OH)4 and by the use of X-ray photoelectron spectroscopy (XPS) for detecting changes in surface chemistry of the minerals. All three minerals were found to release silica at a constant rate (linear kinetics) providing that ultrafine particles, produced by grinding, were removed initially by HF treatment. All three also underwent incongruent dissolution with preferential release of Ca and/or Mg relative to Si from their outermost surfaces. The preferential release of Ca, but not Mg for diopside at pH 6 was found by both XPS and solution chemistry verifying the theoretical prediction of greater mobility of cations located in M2 structural sites. Loss mainly from M2 sites also explains the degree of preferential loss of Mg from enstatite at pH 6; similar structural arguments apply to the loss of Ca and Mg from the surface of tremolite. In the case of diopside and tremolite initial incongruency was followed by essentially congruent cation-plus-silica dissolution indicating rapid formation of a constant-thickness, cation-depleted surface layer. Cation depletion at elevated temperature and low pH (~ 1) for enstatite and diopside was much greater than at low temperature and neutral pH, and continued reaction resulted in the formation of a surface precipitate of pure silica as indicated by solubility calculations, XPS analyses, and scanning electron microscopy.From XPS results at pH 6, model calculations indicate a cation-depleted altered surface layer of only a few atoms thickness in all three minerals. Also, lack of shifts in XPS peak energies for Si, Ca, and Mg, along with undersaturation of solutions with respect to all known Mg and Ca silicate minerals, suggest that cation depletion results from the substitution of hydrogen ion for Ca2+ and/or Mg2+ in a modified silicate structure and not from the precipitation of a new, radically different surface phase. These results, combined with findings of high activation energies for dissolution, a non-linear dependence on aH+ for silica release from enstatite and diopside, and the occurrence of etch pitting, all point to surface chemical reaction and not bulk diffusion (either in solution or through altered surface layers) as the rate controlling mechanism of iron-free pyroxene and amphibole dissolution at earth surface temperatures. 相似文献
15.
为研究褐煤生物产气规律及其液相体系中常见阳离子变化特征，以内蒙古胜利褐煤为产气底物，寺河矿区煤层气井排采水中微生物作为发酵菌群，利用5 L厌氧发酵罐进行模拟生物产气实验，采用离子色谱仪对发酵液中的NH4+、K+、Ca2+、Mg2+和Na+5种阳离子浓度进行动态监测。结果表明:煤模拟生物产气周期为33 d，分为缓慢增长期、快速增长期和平缓期3个阶段，33 d单位质量煤净产甲烷量最高达23 μmol/g；产气体系中NH4+（741.5 mg/L）和K+（994.5 mg/L）离子质量浓度变化最为明显，Ca2+（26 mg/L）、Mg2+（10.7 mg/L）和Na+（72 mg/L）次之，表明发酵液中5种阳离子均参与了褐煤生物产气过程，且被不同程度地释放和利用；褐煤生物产气量与阳离子浓度有一定相关性，单位质量煤产气量与NH4+和K+浓度呈正相关，与Ca2+、Mg2+浓度呈负相关。此外，NH4+和K+以及Ca2+和Mg2+之间浓度呈显著正相关。由实验结果可知:褐煤生物产气液相体系中4+、K+、Ca2+、Mg2+和Na+5种阳离子会随着煤中有机组分的厌氧降解而缓慢释放、再吸附，同时可被微生物利用参与细胞内的生物化学反应。 相似文献
16.
The global rise in atmospheric greenhouse gas concentrations calls for practicable solutions to capture CO2. In this study, a mineral carbonation process was applied in which CO2 reacts with alkaline lignite ash and forms stable carbonate solids. In comparison to previous studies, the assays were conducted at low temperatures and pressures and under semi-dry reaction conditions in an 8 L laboratory mixing device. In order to find optimum process conditions the pCO2 (10-20%), stirring rate (500-3000 rpm) and the liquid to solid ratio (L/S = 0.03-0.36 L kg−1) were varied. In all experiments a considerable CO2 uptake from the gas phase was observed. Concurrently the solid phase contents of Ca and Mg (hydr)oxides decreased and CaCO3 and MgCO3 fractions increased throughout the experiments, showing that CO2 was stabilized as a solid carbonate. The carbonation reaction depends on three factors: Dissolution of CO2 in the liquid phase, mobilization of Ca and Mg from the mineral surface and precipitation of the carbonate solids. Those limitations were found to depend strongly on the variation of the process parameters. Optimum reaction conditions could be found for L/S ratios between 0.12 and 0.18, medium stirring velocities and pCO2 between 10% and 20%.Maximum CO2 uptake by the solid phase was 4.8 mmol g−1 after 120 min, corresponding to a carbonation efficiency for the alkaline material of 53% of the theoretical CO2 binding capacity. In comparison to previous studies both CO2 uptake and carbonation efficiencies were in a similar range, but the reaction times in the semi-dry process were considerably shorter. The proposed method additionally allows for a more simple carbonation setup due to low T and P, and produces an easier to handle product with low water content. 相似文献
17.
水热法分解钾长石制备雪硅钙石的实验研究 总被引：10，自引：3，他引：7
采用CaO作为助剂,在低温、中压的水热条件下分解钾长石,继而合成一种水合硅酸钙--雪硅钙石,同时得到KOH稀溶液,可用于制备高纯碳酸钾。影响晶化反应的主要因素有n(Ca)/n(Al+Si)、晶化温度、晶化时间、水固比（质量比）、搅拌速度等。讨论了各因素对钾长石分解及雪硅钙石形成的影响,通过X射线粉末衍射、热重-差热分析、扫描电镜等手段对合成产物进行结构性能表征。实验结果表明,以CaO为助剂分解钾长石,同时合成雪硅钙石的工艺方法可行,资源利用率接近100%。实验得到的优化工艺条件为：晶化温度为220～250 ℃,n(Ca)/n(Al+Si)在0.8～1.0之间,晶化时间5～8 h,水固比为20～25,搅拌速度400 r/min。在此条件下,钾长石中K2O的溶出率达80%以上,同时得到结晶良好的针状雪硅钙石晶体。 相似文献
18.
通过对双朋西金铜矿床流体包裹体岩相学、测温学及矿石铅、硫同位素等的分析,研究成矿流体性质和演化、成矿流体来源。结果表明:流体包裹体主要为气液两相包裹体,另有少量液相和含子矿物包裹体。包裹体液相成分阳离子以Na+,K+,Ca2+为主,阴离子主要以SO42-,Cl-为主;气相以H2O,CO2为主。均一温度范围为210~370℃和370~460℃,盐度3.0%~6.5%,密度集中于0.600~0.800 g/cm3,压力主要为8.0~20.0 MPa,为中高温、中等盐度、中等密度、中等压力的成矿流体。铅同位素206Pb/204Pb为18.058~18.710,207Pb/204Pb为15.581~15.641,208Pb/204Pb为38.191~38.531,δ(34S)为+3.1×10-3~+6.2×10-3,平均值为+4.42×10-3,成矿流体铅、硫同位素来源为壳幔混合源。 相似文献
19.
Data on the composition of the absorbed complex of riverine solid substances and its transformation in marine environments obtained from field observations and experimental investigations are systematized and generalized. Average values of the specific surface of the riverine suspended particulates (~20 m2/g) and the total exchange capacity of solid substances of the continental runoff (~28 mg-equiv/100 g or 280 g-equiv/t of the transported terrigenous material) are determined. It is shown that the composition of the absorbed complex in the riverine suspended particulates, as well as bottom sediments of rivers and inland water bodies differs principally from that of bottom sediments in oceans and seas: Ca dominates in the first case; Na, in the second case. When the riverine terrigenous material enters oceans and seas, the composition of the absorbed complex is subjected to the ion-exchange transformation reflected in the replacement of exchange Ca (~80%) mainly by Na and also by K and Mg of seawater. This process is responsible for the influx of 45.5 Mt/yr of dissolved Ca to ocean and the removal of 37.3, 12.8, and 3.9 Mt/yr of Na, K, and Mg, respectively. The relative transport of Ca, Na, K, and Mg to ocean with the river runoff is +7.5,–12.3,–22.4, and–2.6%, respectively. 相似文献
20.
硅灰石与盐酸反应模式及产物性质研究 总被引：16，自引：3，他引：13
报道了硅灰石与盐酸反应在ＰＨ≥２条件下的反应模式,并从反应产物颗粒形态、粒径分布、表面电位、比表面积等性质及反应动力学规律来证实这种反应模式。 相似文献