The Dissolution Experiment of Polyhalite at Different Temperature and Pressure

正Polyhalite(K2SO4·Mg SO4·2Ca SO4·2H2O)is one of the insoluble potassium mineral which is widely distributed in sulfate-type potassium-bearing deposit,and the theoretical concentration of K2SO4 is 28%.It can be directly used as a     

Calcium Isotopic Composition of Various Reference Materials and Seawater

A compilation of δ^44/40Ca (δ^44/40Ca) data sets of different calcium reference materials is presented, based on measurements in three different laboratories (Institute of Geological Sciences, Bern; Centre de Géochimie de la Surface, Strasbourg; GEOMAR, Kiel) to support the establishment of a calcium isotope reference standard. Samples include a series of international and internal Ca reference materials, including NIST SRM 915a, seawater, two calcium carbonates and a CaF₂ reference sample. The deviations in δ^44/40Ca for selected pairs of reference samples have been defined and are consistent within statistical uncertainties in all three laboratories. Emphasis has been placed on characterising both NIST SRM 915a as an internationally available high purity Ca reference sample and seawater as representative of an important and widely available geological reservoir. The difference between δ^44/40Ca of NIST SRM 915a and seawater is defined as -1.88 O.O4%o (δ^44/42Ca_{NISTSRM915a/Sw}= -0.94 0.07%o). The conversion of values referenced to NIST SRM 915a to seawater can be described by the simplified equation δ^44/40Ca_Sa/Sw=δ^44/40Ca_{Sa/NIST SRM 915a} - 1.88 (δ^44/42Ca_Sa/Sw=δ^44/42Ca_{Sa/NIST SRM 915a} - 0.94). We propose the use of NIST SRM 915a as general Ca isotope reference standard, with seawater being defined as the major reservoir with respect to oceanographic studies.     

不同生态处理方法对黑臭河道底泥细菌多样性与群落结构的影响

底泥细菌代谢是城市河道底泥代谢物的主要来源,最终决定城市河道的生态状况.本文研究了黑臭河道底泥经添加硝酸钙、生物促生剂和种植沉水植物处理后底泥中细菌群落结构的响应,以期为城市黑臭河道细菌群落的改善和综合治理提供理论依据.实验结果表明:经过不同生态处理后,上覆水中,添加硝酸钙组总氮(TN)含量显著高于对照组,添加生物促生剂组溶解氧浓度显著高于对照组.沉积物中,所有处理组的氧化还原电位值(ORP)均显著高于对照组,种植沉水植物组和添加硝酸钙组TN含量均显著低于对照组,沉积物理化性质得到一定改善.对不同生态处理组底泥细菌群落的研究发现,处理组底泥细菌群落产生了较大变化,且不同处理组细菌群落变化不同,生物促生剂组底泥中细菌的Sobs指数和Chao 1指数显著高于对照组和硝酸钙组,且生物促生剂组Shannon指数和PD指数显著高于硝酸钙组.Proteobacteria(Deltaproteobacteria、Betaproteobacteria、Gammaproteobacteria)、Chloroflexi、Firmicutes、Bacteroidetes和Spirochaetae是各实验组的...     

菌剂添加对不同树种根际土壤微生物及碳酸钙溶蚀的影响

本实验通过对云南省建水地区植被根际土壤中高产碳酸酐酶（CA）的微生物进行分离筛选和溶蚀效应的测定,将溶蚀效果较好的菌株制成菌悬液进行盆栽实验,探究该菌株对不同树种根际土壤微生物代谢活性和碳酸钙类岩石溶蚀效应的影响。结果表明：从根际土壤中筛选到一株能够高产CA,且具有较强溶蚀效果的沙雷氏菌,施加该菌剂的处理组显著增加了土壤微生物数量,提高微生物的代谢活性和多样性,并加速碳酸钙类岩石的溶蚀。本研究旨在为今后岩溶区生态恢复过程中植物树种的选择与微生物菌剂的联合应用提供一种技术手段,为岩溶地区生态系统的治理提供一定的理论支持。     

方解石型重质碳酸钙的表面改性及其在橡胶中的应用研究

作者对方解石型重质碳酸钙进行了表面改性及其在橡胶中的应用试验研究,研究表明,重质碳酸钙的粒度组成、矿浆浓度、改性药剂种类及用量和改性时间等均对改性效果有重要的影响。通过对改性效果效果的预先评价,确定了最佳的改性工艺条件。在橡胶中的应用试验显示,改性重质碳酸钙充填橡胶制品的性能良好,其应用前景广阔。     

磷石膏制备硫酸钙晶须的结晶行为

以磷石膏为原料制备硫酸钙晶须,从固液比、溶剂浓度、溶解温度以及降温速率对晶须影响的4个方面研究了晶须的结晶行为。对磷石膏和晶须进行了分析测试;利用显微观察及图像分析,讨论了实验条件对晶须长度、长径比和晶须形貌的影响;结合结晶学原理讨论了晶须的结晶行为。结果表明,随固液比的增大,晶须长度和长径比先降后升;随溶剂浓度的增大,晶须的长度和长径比上升;随溶解温度的增大和降温速率的增加,晶须的长度和长径比下降。所制备的晶须平均长度为200~400μm,平均长径比为25~30。晶须长度和长径比的变化能够反映晶须形貌的变化。晶须的结晶分为晶核的形成和晶须的生长两个阶段,实验条件通过影响晶核形成的速率、过饱和度以及磷石膏的溶解量对晶须的结晶行为产生影响。     

鄂西方解石矿系列产品开发应用研究

率述了鄂西构造蚀变型方解石矿的质量,超细重碳酸钙产品生产工艺流程,改性超细重碳酸钙系列产品在造纸涂料,塑料及橡胶中的应用研究。     

Weathering of phosphorus-bearing mineral powder and calcium phosphate by Aspergillus niger

The weathering of phosphorus-bearing mineral powder(PBMP) and calcium phosphate(CP) by Aspergillus niger was compared,and the mechanism involved was analyzed for the comprehensive utilization of PBMP.The concentration of water-soluble phosphorus(WSP),Mg2+,and Ca2+at different culture times,microstructures of particles,and mineral compositions was examined by ultraviolet-visible spectrometer(UV),atomic absorption spectrometry(AAS),scanning electron microscopy(SEM),and X-ray diffraction(XRD).Results showed that the change in the concentrations of WSP,Mg2+,and Ca2+were related to the growth of A.niger and the different mineral compositions.Compared with CP,PBMP was weathered harder by fungi.Traces of the weathered mineral were found through SEM.CP not only showed traces of erosion damage but also appeared as a rhombohedron-like substance.The XRD test indicated that the weathering minerals can form water calcium oxalate.Further analysis revealed that the mechanism of PBMP and CP weathering by A.niger was the collaborative result of mycelium biomechanical effects and the acid-soluble role of acidic metabolites.The phosphorus dissolution rate of PBMP after 20 d was 46.83%,whereas that of CP after 12 d was 91.01%.The findings of this study are significant to the effective use of waste PBMP and to the exploitation of low-grade phosphate rock resources.     

Strengthening crushed coarse aggregates using bio-grouting

This paper focuses on using urea hydrolysis as a bio-grouting process to increase the strength of crushed aggregates commonly used in stone columns. Various reagent phases (2, 4, 6 and 12 phases) consisted of alternately percolating solutions containing bacterial suspension and cementation solution through the soil column. In addition, a multi-soil lift strategy with options of up to four soil lifts was undertaken to test the applicability of bio-grout to cement crushed aggregate columns. While the average amount of calcium carbonate precipitation was roughly unchanged in both techniques, the distribution within the crushed aggregate columns was heterogeneous. However, the distribution of the precipitated calcium carbonate is almost uniform in crushed aggregates treated by a two-soil lift strategy and a four-phase treatment strategy. It is also deducted that both techniques can be combined to gain a uniform calcium carbonate and strength along a long sand/stone column. Furthermore, a one-soil lift resulted in higher strength than using multi-soil lifts, and a maximum strength of approximately 2.3 MPa was achieved using 4-reagent phase treatment strategy. Scanning electron microscopy and electron dispersive spectroscopy analysis validate that calcium carbonate was deposited as white crystals on the surface of the crushed aggregate particles.