Abstract:The microchannel refers to structural channel of minerals with sperture from 0.3 nm to 2.0 nm. The microtunnel with K filling constructed by active Mn—O octahedron in cryptomelane is quite similar to that with Na and Ca fillings constructed by Si—O and Al—O tetragonal molecular sieve in zeolite. They have the function of molecular sieve. Here the author points out that ultra-microchannel of natural minerals has aperture below 0.3 nm. Most natural minerals with ultra-microchannel structures have the features of ion exchanges among geomaterials. The ultra-microchannel of feldspar that is half of the mass of the crust has been ignored due to its aperture being too small to understand. However, the author's recent experimental research work shows that feldspar has certain ion exchange functions and channel structure features under high or low temperature conditions. At higher temperature Na+ can go into the channel of feldspars. The content of Na2O in feldspar increases up to 15.9 percent. At medium temperature Pb2+ can also enter the channel of feldspar with functions of ion exchange and lead to the formation of Pb-feldspar. At room temperature about 97.94% Cd2+ can be removed by feldspar and hence Cd-feldspar occurs. The effects of typical ultra-microchannel of feldspar are helpful to treat heavy metal pollution and dispose nucleus waste. The ultra-microchannel of natural minerals has played a special role in migration and exchange of geomaterials. The molecular sieves of the microchannel of handful natural minerals have the function of purifying molecular gas pollution, whereas the ionic sieves of ultra-microchannel of most natural minerals are likely to purify ionic water contaminates.

Abstract:Feldspar and Pb(NO3)2 power were mixed and reacted at 380℃. The product was analyzed with XRD. The XRD power diagram of the reaction results was observed, which had five strong reflection peaks of Pb-feldspar, with d values being 6.54, 3.42, 3.32, 3.27 and 2.57A, respectively. XPS analysis of reaction results shows that the binding energy of Pb 4f7/2in feldspar is between 138.39 and 138.44 eV. Pb2+can replace alkali and alkali earth elements in feldspar structure through ion exchange reactions, forming Pb-feldspar

Abstract:With TEM, XRD, FT-IR, and the physical gas adsorption techniques, porous properties of nano-fibriform silica (MLD: 92.73%) from natural chrysotile were studied. The results indicate that nano-fibriform silica is porous and that the nano-fibriform structure is attributed to the complete dissolution of the brucite octahedral sheets of chrysotile and the collapse of some Si-O tetrahedral sheets. Its length is at the micron or nanometer scale. There are two types of pores: cumulate pores and pores on the nanofibre. The latter pores, whose apertures are less than 5 nm, consist of pores among the particulate SiO_2, pores among the aggregates of particulate SiO_2, remnant nano-tunnels and capillaries. These pores belong to mesopores whose apertures are mainly of 2.1 and 3.8 nm. As the carrier of catalyzer and the filler to reinforce rubber and plastics, nano-fibriform silica shows better performance than traditional silica.

Abstract:Although hydrotalcite or layered double hydroxides (LDHs) is not a common mineral, it is an important material that can be easily synthesized in laboratory. In this study, structural evolution and BET surface area changes of heat treated Mg/Al-LDH was evaluated by XRD, TEM and N2-BET analyses. The results indicate that for magnesium-aluminum LDH with carbonate as interlayeranion, periclase-like oxide was formed at the temperature of 400～800℃. Meanwhile, 2-3 nanometer mesopores were formed during the decomposition of LDH. However, the heat treated samples still preserve the morphology of original LDH plates. Periclase-like oxide formed from LDH heat treatment may re-hydrolyze and recover the structure of LDH. However, crystallinity of the recovered LDH is lower than that of original LDH. Such a heat treatment will result in the formation of (Mg, Al)-oxide nano-crystals and nanopores among the nano-crystals. When the heating temperature exceeds 1 000℃, the periclase-like (Mg, Al)-oxide was transformed into a composite with periclase (MgO) and spinel phases. The periclase can be re-hydrolyzed and dissolved in HCl solution. After acid treatment, the sample with high surface area is composed of spinel nano-crystals and nanopores among them. The results of this study will provide a new and economical way to synthesize mesoporous materials through pathways of phase transformation of precursor materials with different compositions.

Abstract:In order to improve the superficial performance of palygorskite and raise its application value, the authors treated the natural palygorskite (NP) with three processing methods, namely, acid dipping, acid dipping + calefaction, and acid dipping + calefaction + formaldehyde infusing. The performance of the modified palygorskite (MP) was also investigated by such means as SEM, FT-IR, XRF, BET-SSA and full hole distribution analysis. The results show that, compared with characteristics of NP, the gracile and aggregated compact crystal bundles in MP are subjected to fragmentation and decentralization, the roughness of microcrystalline surface increases, some impurities, especially the carbonates, are removed remarkably after treatment, and the specific surface area and the total pore volume (Vtotal) in MP are more than and close to two times of the area and the volume in NP, respectively. The mesopore volume (Vmeso) increases from 0.092 cm3/g to 0.15 cm3/g, while the mean pore size decreases by 2～3 nm. The phoney pore size distribution peak of MP is 17nm, which is 5nm smaller than the 22 nm of NP. In addition, the pores in all samples are mostly mesopores whose sizes vary in the range of 2～50 nm, and macropores and micropores are rarely seen. However, the three processing methods show no remarkable differences in the treatment results.

Abstract:Several Mn oxide minerals commonly existent in soils were synthesized by the modified or optimized methods. Their morphologies, structures, compositions and surface properties were characterized. Adsorption and redox reactions of heavy metals on them and effects of mineral structures and surface properties were also investigated. The synthesized birnessite, todorokite, cryptomelane and hausmannite are all single-phase minerals and have the typical morphology, as indicated by analyses of XRD and TEM/ED. The PZCs of the synthesized birnessite, todorokite and cryptomelane are 1.75, 3.50 and 2.10, respectively. The magnitude order of their surface variable negative charges is birnessite ≥ cryptomelane > todorokite. The PZC of the synthesized hausmannite is much higher than PZCs of other minerals, and it has the least surface variable negative charge. Among the tested Mn oxide minerals, birnessite has the greatest adsorption capacity for heavy metals such as Pb2+ , Cu2+, Co2+, Cd2+and Zn2+ , whereas hausmannite has the weakest capacity. Except for hausmannite, these minerals have the greatest adsorption capacity for Pb2+ . Hydration constants of the heavy metals and the surface variable charges of the Mn minerals remarkably affect the adsorption. Both of the factors affect the hydration induced by surfaces of the minerals and species of the adsorbed ions. Their ability in Cr (Ⅲ) oxidation and concomitant release of Mn2+varies greatly depending on the structure, composition, surface property and crystallinity. The maximum amounts of Cr (Ⅲ) oxidized by the Mn oxide minerals are in order of (mmol/kg) birnessite (1 330.0) > cryptomelane (422.6) > todorokite (59.7) > hausmannite (36.6).

Abstract:This paper made an experimental study of Cr(Ⅵ)-bearing wastewater treated by natural pyrite. XPS peaks of Cr2p apparently appeared on the pyrite surface and colloidal precipitates during and after the reaction, which can be fitted into three peaks at different binding energies of 574.7～575.1 eV, 576.6～576.9 eV and 578.2～578.7 eV. The relative peaks represent the phases of Cr2S3, Cr2O3 and CrO3, respectively. The precipitate phase of Cr2S3 was found for the first time in this experiment. The results show that the phase of chromium-bearing sulfides can be produced in aqueous media under the conditions of room temperature and normal ambient pressure. Taking full advantage of this chromium-bearing sulfide phase, we can utilize natural pyrite including pyrrhotite to transfer Cr (Ⅲ) precipitates directly into colloidal precipitates without adding base in the process of reducing Cr(Ⅵ). The content of totalchromium in the upper treated supernatant is lower than that of the National Standards of Sewage Treatment. The heavy metals dissolved by natural pyrite itselfare very low in content so that they don't affect the effluent quality. In order to apply and extend the new technology for one-step treatment of Cr(Ⅵ)-bearing wastewater in which Cr(Ⅵ) was reduced and Cr (Ⅲ) was precipitated simultaneously by natural pyrite and pyrrhotite, we should exploit and apply chromium-bearing precipitate phase.

Abstract:Two kinds of modified montmorillonites were synthesized from Na-montmorillonite, namely Ni-Ti-cross-linked-montmorillonite and Ni-Ti-organic compound montmorillonite. Some factors were examined in the experiments of Cr（Ⅵ）=bearing wastewater disposal. The feeding amount of modified montmorillonite, the pH of wastewater and the stirring time, and the Cr（Ⅵ）removal rate on three kinds of montmorillonites were studied. The results show that the removal rate of Cr（Ⅵ） on modified montmorillonite under optimized conditions has reached 87% and 96%, that the adsorption obeys Langmuir adsorption isotherm, and that the saturated adsorption amount and the Langmuir constant are 3.182?7 mg/g,8.554 3 mg/g and 3.500 7, 1.273 8, respectively.

Abstract:High-concentrated sulfur waste water from a certain factory in Jiangsu was treated by the process of jarosites deposition. In this paper, a method for treating high-concentrated sulfur waste water in the industry is discussed. The experiment utilized the deposition process to remove parts of SO 2- _4, caused the continuous transform of low-valence S into SO 2- _4 and oxidized low-valence S by H_2O_2. The second deposition could remove more S, thus sharply decreasing the COD of the waste water. According to the experimental results, the optimal operational parameters are confirmed,the pH value is between 2.50 and 3.20,and the optimal FeCl_3 addition amount is 50 g/L. The whole waste water flow needs two deposition processes,which make the disposal rate COD of the waste water up to 85.29%. And the disposal rate COD of the waste water can eventually reach 96% by H_2O_2 oxidation. The results obtained provide fundamental data for practical operation before biochemical treatment.

Abstract:The absorption reactions of goethite and its precursors onarsenite were studied. The three absorbent types were Fe(OH)3 gel and two goethites, in which the Fe(OH)3 gel had been dried in a microwave oven under the vacuum condition and at 80℃. It was found that, due to the replacement of OH- by arsenite in goethite and Fe(OH)3, pH changed from 9.71 to 10.36 6 minutes after the Fe(OH)3 gel was mixed with NaAsO2 solution. At 40 minutes after the start of the reaction, pH decreased, which was caused by the condensation reaction between the arsenite and the absorbent. The decline in pH values did not indicate the end of the absorption, but was an indication of a change in the reaction type. Temperatures and dissolved gas had little effect on these two types of reactions. The total absorption of aresenite increased after the absorbent had been irradiated with ultrasound, which also caused difficulty in separating the solids from the solution. The absorption capacity for arsenite of Fe(OH)3 gel dried in a microwave oven under vacuum was 53.18% and 17.22% better than that of Fe(OH)3 gel and gel dried at 80℃, respectively. The reasons for such phenomena might be that the water molecules in the gel vibrated with high frequency under the action of microwave irradiation, thereby producing higher porosity and improving surface activity.

Abstract:The adsorption of pentachlorophenol (PCP) on quartz, kaolinite, illite, montmorillonite and iron oxides were investigated by batch equilibrium techniques. The pH-dependence isotherms are curves with a peak value, whose position is at about pH=5～6 depending on the mineral species. Based on the distribution of both speciation of surface hydroxyls on minerals and PCP in solution, the authors put forward a surface reaction model involving surface complexation and surface electrostatic attraction to fit the pH-dependence isotherms, and calculated both reaction constants. The results show that on quartz and phyllosilicate minerals the predominant adsorption reaction is surface complexation, whereas both surface electrostatic attraction and surface complexation are involvedin the iron oxide minerals. The reaction constants of surface electrostatic adsorption are usually one to three orders of magnitude larger than that of surface complexation. The concentration-dependence isotherms can be well fitted by Langmuir equation with correlation coefficient R>0.93 for kaolinite and iron oxides.The maximum adsorption has been found in order of hematite>lepidocrocite>goethite>kaolinite>quartz>montmorillonite≈illite, which can be interpreted by consideration of both reaction mechanism and surface hydroxyl density. The significant adsorption of PCP on mineral surfaces suggests that clay and iron oxide mineralscan play an important role as HIOCs adsorption in laterite or latertoid soil, which is widely spread in south China.

Abstract:Chlorinated hydrocarbons are widely detected in groundwater, but the conventional methods for their removal are not economical both in time and in cost. This paper deals with the factors affecting the removal of PCE bynano-Ni/Fe. The data shows that the reaction rate of the unexposed nano-Ni/Fe is 4 times larger than the exposed one. Temperature is one of the important affecting factors. The reaction rate constant will increase by 2～3 times with the elevation of temperature by 10℃. Under certain conditions, the larger the percentage of Ni on the iron, the faster the dechlorination reaction. Nevertheless, 8% is the best amount for dechlorination. Dissolved oxygen in solution is not helpful to the removal of chlorinated hydrocarbons.

Abstract:HDTMA+_pillared montmorillonites with surfactant arrangements of lateral-monolayer, lateral-bilayer and paraffin_bilayer, respectively, were prepared at different concentrations (0.5～2.5 CEC) of hexadecyltrimethylammonium bromide (HDTMAB). The sorption properties of the resultant organoclays were tested using p-nitrophenol as a model pollutant. The sorption efficiency of the organoclays increases with the increase of the solution pH, depending on the ionization extent of p-nitrophenol, whereas the sorption efficiency decreases with the increase of solution temperature, suggesting that the sorption reaction is exothermic. Generally, the sorption efficiency of organoclays increases with the increase of the surfactant packing density within montmorillonite interlayer, i.e., in the order of lateral-monolayer, lateral-bilayer and paraffin-bilayer.The isotherms for Na-montmorillonite, organoclays with lateral-monolayer and lateral-bilayer arrangements display S-type, implying that p-nitrophenol is mainly adsorbed on clay surfaces. For organoclays with paraffin_bilayer arrangement of the confined surfactants, their isotherms belong to Linear-type, demonstrating that p-nitrophenol enters the clay interlayer.

Abstract:This paper utilizes minerals to resolve the problem of the obvious reduction of the efficiency of ozonization, which is caused by the high acidification of the dye wastewater during ozonization. First, high specific area mordenites modified with copper oxide dipping were used as adsorbent to improve the efficiency of ozonization. Second, natural alkaline mineral brucites were employed to counteract the high acidification. The results of the experiments show that two schemes of Cu_mordenite combined with brucite added to dye wastewater, with mass ratios between Cu-mordenite and brucite being 2∶1 and 1∶1 respectively, could increase pH value of the wastewater and improve the efficiency of ozonization. The value of COD decreasing rate of the dye wastewater with mCu-mordedite/mbrucitebeing 1∶1 is enhanced by almost 30 percent compared with that of the organic water with ozone only. In the end, the authors deduce three possible mechanisms for minerals in organic wastewater ozonization processes. They are adsorption of Cu-mordenites, alkali catalysis related to brucite decomposition and complex reaction between Mg2+ and organic acids.

Abstract:ZnS pillared kaolinite_montmorillonite (ZnS-PKM) nanocomposite was successfully prepared in situ via the ion exchange and solvothermal process of a complex precursor of thiourea and Zn (CH3COO)2 at the molar ratio of 2∶1 at 170℃ for 4 h. XRD result shows that the d001 of kaolinite-montmorillonite (KM) is pillared to 1.95 nm from 0.98 nm, which is due to the accommodation of ZnS in the gallery of KM. SEM images illustrate that the uniformly distributed ZnS agglomeration exists on the partially exfoliated KM layers, and TEM verifies that the agglomerated ZnS (～25 nm) is stacked by ZnS subparticles (3～5 nm), which is intercalated in the layers of KM. SAED and EDS confirm that the particles are of hexagonal ZnS with low crystallization. Photo degradation of eosin-B was performed to test the catalytic activity of the prepared ZnS-PKM. UV-Vis absorption spectrum tracking the course of the degradation reaction shows that eosin-B is demineralized in 20min without the formation of new pollutant, and its activity is much higher than activities reported ZnS nanoparticles in references. The probable mechanism lies in the protection of ZnS nanoparticles by the layers of KM from agglomeration, which leads to the possibility of the reuse of ZnS-PKM.

Abstract:Radioactive wastes arising from a wide range of human activities are in many different physical and chemical forms, contaminated with varying radioactivity. Their common feature is the potential hazard associated with their radioactivity, and their disposal is of vital importance to the protection of human environment. The geological disposal is commonly regarded in the world as the most reasonable and effective way to the safe disposal of high-level radioactive wastes. The conceptual model of geological disposal in China is based on a multi-barrier system that combines an isolated geological environment with an engineered barrier system. The buffer is one of the main engineered barriers for HLW repository. The buffer material is expected to maintain its low water permeability, self-sealing property, radio nuclides adsorption and retardation property, thermal conductivity, chemical buffering property, overpack supporting property, and stress buffering property over a long period of time. Benotite is selected as the main content of the buffer material that can satisfy the above requirements. GMZ deposit is selected as the candidate supplier for Chinese buffer materials of high level radioactive waste repository. This paper presents geological features of GMZ deposit and basic property of GMZ Na bentonite. GMZ bentonite deposit is a superlarge scale deposit with a high content of montmorillonite (about 75%), and GMZ-1, which is Na-bentonite produced from GMZ deposit, is selected as a reference material for Chinese buffer material study.

Abstract:The decomposition behavior of calcium sulfate and the influence of various additives at high temperature were investigated in this paper. The results show that SiO2, ZnO and the compound of SiO2-Fe2O3 can effectively restrain the decomposition of calcium sulfate, attributed mainly to the formation of new products Ca2SiO4 and Ca2Fe2S2O3. A high sulfur retention rate can be achieved by incorporating compound Al2O3-CaCO3 into CaSO4 at the molar ratio of CaCO3∶Al2O3∶CaSO4=3∶3∶1, and XRD proves that large amounts of sulfoaluminates occur in the slag.

Abstract:On the basis of investigating characteristics of solid wastes in two different kinds of mines, i.e., the Fenghuangshan copper mine and the Xinqiao pyrite mine in Tongling, the possibility of acid drainage of the mine tailings and the waste rocks and the difference in acid drainage between these two sorts of materials are discussed, and the modes of occurrence of heavy metal elements in the mine solid waste are also studied. The results indicate that the Fenghuangshan copper mine on the whole does not produce AMD, whereas the Xinqiao pyrite mine produces such materials. What is more, the modes of occurrence of heavy metal elements in the tailings of the Fenghuangshan copper mine are different from those in the mining waste rocks of the Xinqiao pyrite mine. In the former, the toxic heavy metals such as Cu, Pb, Zn, Cd, As and Hg mostly exist in the slag phase, while in the latter, the deoxidization state has much higher content, which suggests that large amounts of heavy metals have migrated in the tailings, and minerals in the waste rocks have begun to oxidize at the surface. The existence of AMD is beneficial to the migration and spread of the heavy metals in mining waste rocks, and hence leads to the environment pollution of the surrounding areas.

Abstract:The experiments in this paper employed the strains of Bacillus HRS4 isolated from oil reservoir. By growing in the facultatire aerobic condition the cells acted on selenite. After 36 hours, all the samples with sodium selenite radical from 1mM up to 11mM produced many red deposits. Under biomicroscope the authors found one or more red round intracellular deposits in the cell with free floating deposits outside the cell. Intracellular organization of deposits includes one or two regular chains, curve or irregular in form. The XPS patterns of the deposits show that the sodium selenite has been exclusively reduced to elemental selenium. Furthermore, glucove in the culture media can impact greatly the quantity of the deposits of the reduced elemental selenium.

Abstract:The characteristics of sepiolite and sepiolite absorbing nano-TiO2 particles were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). The changes of the surface area of the sepiolite after absorbing nano-TiO2 were investigated by BET method. The hydroxyl free radical (·OH) produced by the materials was measured by electron spin resonance (ESR) spectra. It is found that nano-TiO2 particles can be evenly absorbed on the fibersof the sepiolite which can also disperse the nano-TiO2 particles, and that the ·OH can be produced under the natural light. The sepiolite absorbing nano-TiO2 can not only solve the dispersing problem but also increase photocatalysis.

Abstract:The formation conditions of jarosite in the system Fe2(SO4)3-K2SO4-H2O were studied. The results show that jarosite can be formed rapidly under normal temperature and pressure by controlling suitable pH value and Fe2(SO4)3 and K2SO4 concentrations. The pH value, temperature and concentration of Fe2(SO4)3 media are key factors affecting the formation of jarosite. At normal temperature, the precipitation of jarosite can be seen within 24 hours when the pH value is between 2.60 and 3.10, and a great quantity of jarosite is formed within 48 hours. At about 90℃, the pH value range forming jarosite extends to 1.20～3.10, and within this range, the rising pH value is advantageous to the formation of jarosite. High Fe2(SO4)3 concentration is also favorable for the formation of jarosite. Relative pure jarosite can be synthesized when Fe2(SO4)3 concentration is high (>0.05 M) and jarosite containing melanterite and colloid amorphous hydroxide vitriol iron can be formed when Fe2(SO4)3 concentration is low. The depositing process of jarosite canbe used to tackle waste water from mines and other industries and remove S, Fe and other toxic and harmful elements such as As, Cr, Hg and Pb in water. The achievement of rapid formation of jarosite under normal temperature and pressure presents a potential good application prospect in using the precipitation of jarosite colloid and its analogues as isolation mantle layers of mine tailing producing acid mine drainage

Abstract:The vermiculites were intercalated by hexadecyltrimethylammonium bromide (HDTMA·Br) through stirring in hot water, ball milling, boiling and stirring in HAAKE mixer. The microstructures and properties of organic vermiculites were characterized by means of XRD. The results indicate that the configu rations of HDTMA ＋refer to paraffin type monolayer, paraffin type bilayer and lateral bilayer, and that the configuration types decrease while the values of interlayer spaces increase with the rising of temperature and intensifying of me chanical force in different intercalation means.

Abstract:In this paper, the authors applied microwave techniques to the preparation of kaolinite/organics intercalated compound. The effects of microwave during intercalation, displacement and in situ polymerization were investigated through DMSO and aerylamide. The result shows that the microwave energy can accelerate intercalation and displacement reactions. After 30 minutes of reaction, the intercalation rate reached 75%. The displacement rate of acrylamide reached above 77% after 50 minutes of irradiation. It is also found that the microwave energy has the exfoliation effect on kaolinite. The intercalated compound and the reaction principle of microwave irradiation were studied by such means as FT-IR, XRD, TG and TEM.

Abstract:The phlogopite-vermiculite interstratification mineral samples from the Weli mine of Xinjiang were acidized with hydrochloric acid. Based on an analysis of chemical composition and XRD of the samples, the authors studied chemical composition and contents of the acid soak-out substances as well as the structure characteristics of the samples treated with hydrochloric acid. The acid corrosion mechanism and the content variation tendency of the soak-out substances with the increase of hydrochloric acid concentration were also investigated. The results show that the acid soak-out ratios of CaO and Na2O are the highest, followed by K2O. The acid soak-out ratios of MgO, Fe2O3 and Al2O3 are relatively high, while the acid soak-out ratios of SiO2 are the lowest. The acid corrosion amounts of the samples with more vermiculite layers are relatively high. The acid-resistant property of the phlogopite-vermiculite interstratification mineral is not so good as phlogopite.

Abstract:The FeCl3 graphite intercalation compounds (FeCl3-GICs) have aroused special attention for their highly electrical conductivity and stability. In this paper, FeCl3-exfoliated graphite intercalation compounds (Abs. FeCl3-EGICs) have been synthesized under the protection of nitrogen gas with the melting salt method. The experimental results show that pure stage-I FeCl3-EGICs can be synthesized at 360℃ for 12 hours, and pure stage-II FeCls3-EGICsat 460℃ for 12 hours when FeCl3 is excessive. In addition, the electrical conductivity of FeCl3-EGICs was measured at different temperatures, the number of stage Ⅰ EGICs is 7.513×10 6S·m-1 at 297K which is 3.7 times larger than pristine exfoliated graphite, and stage Ⅱ is 6.87×10 6 S.m-1at the same temperature which is 3.4 times larger. The conductance of FeCl3-EGICs is similar to that of metals, and its electrical resistivity shows a linear relation with the temperature from 297K to decomposition temperature. The resistivityincreases with temperature, with the mechanism being phonon scattering.

Abstract:In order to study the possibilities of applying tailings dissolved in acid mine drainage in the Jinchuan copper and nickel mine to the integrated treatment of mine tailings and acid mine drainage, the authors performedthe dissolution experiments in sulfuric acid. It is found that tailings dissolve quickly under the following constant parameters: higher than 3 mol/L sulfuricacid concentration, above 90℃ temperature, a appropriate liquid/solid, and strong agitation. The dissolution can produce amorphous silicon dioxide. The pre-roasting of samples in a laboratory Muffle furnace at 300℃ for 4 hours would be of benefit to the dissolution of chlorite, but not beneficial to the dissolution of tremolite. Olivine, serpentine and diopside can dissolve easily while the dissolution of tremolite and plagioclase is rather difficult. Such phenomena are related to the properties of the tailing minerals.

Abstract:After the synthesis of tobermorite from potassium feldsparof Lushi County, Henan Province, the authors successfully prepared potassium carbonate from the mother solution. The solution was acidified by CO2 and concentrated by vaporizing after the removal of residue by filtration. When the density increased to 1.444 1 mg/L, the ethanol was added to the solution to reduce the solubility of potassium bicarbonate. Thus, the potassium carbonate was prepared. The electronic class K2CO3 prepared by the filtrated solution is up to GB/T1587-2000Ⅱ specification.

Abstract:In this paper, the clastic samples from Jurassic Ahe-Qigu Formations in Kuche depression were collected. Combining the methods of synchronous pick-up and centrifuge based on Stokes Law, the authors separated the samples into five grades, namely above 20 μm, 20～5 μm, 5～2 μm, 2～0.2 μm and below 0.2 μm. The SEM analysis shows different clay characteristics for different particle sizes. In 20～2 μm, the existence of flaky clays suggests that the clays are mostly detrital clays; in <2 μm, the clays are mostly autogenic clays inthe form of aggregates. The XRD analysis shows the clay minerals are mostly illite, kaolinite, chlorite and mixed-layer illite/smectite. The mixed-layer illite/smectite is mainly concentrated in <0.2 μm particles. The amount of kaolinite increases with coarsening lithology. In early Jurassic, the amount of kaolinite is high, but in late Jurassic, when the environment changed from dry to humid, the amount of kaolinite decreased and that of illite increased. An analysis of clays with different geneses contributes to further study of the sedimentary environment and diagenetic process.

Abstract:Palygorskite is a typical indicator mineral for arid and strong evaporation environment. The distribution of palygorskite in loess-red clay sequence may act as an important indicator for reconstruction of paleoenvironment and paleoclimate in ～7.0 Ma eolian sequence from the Chinese Loess Plateau.In this paper, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations on Renjiapo red clay-loess-paleosol profile in Lingtai, Gansu Province were performed. The results indicate that palygorskite extensively existed in red clay sequence deposits before 3.6 Ma, while no alygorskitehas been observed in the eolian sediments in the last 3.6 Ma, including 3.6～2.6 Ma red clay sequence and Quaternary loess-paleosol sediments. Micromorphology and microstructure shows that palygorskite is an autogenic mineral formed during pedogenesis. The results of this study indicate that the horizon where palygorskite disappeared in the red clay sequence was consistent with that of magnetic susceptibility enhancement, and eolian flux and dust depositional rate increased in about 3.6～3.2 Ma，which was a conversion period of east Asian monsoon type, during which paleomonsoon climate pattern shifted from summer monsoon dominated by sustainable dry_warm climate to east Asian paleomonsoon characterized by the alternation of winter monsoon with dry and cold climate and summer monsoon with warm and humid climate, noted for simultaneous strengthening of east Asian winter and summer monsoon.

Abstract:The function of clay minerals and the effect of clay mineral dehydration on land subsidence have become an increasingly important key point in the evaluation and solution of many problems in such aspects as geology,engineering geology,hydrogeology,environmental geology,and hence aroused more and more attention in geologists. This paper describes characteristics of montmorillonite interlayer water and factors affecting the swelling with hydration and the contraction with dehydration. The solid solution properties of the montmorillonite interlayer are pointed out. Based on the achievements made in investigating the relationship between montmorillonite dehydration and land subsidence,this paper puts forward the train of thought for further study of the secondary land subsidence in the light of montmorillonite dehydration. The possibilities of using the montmorillonite dehydration to the study of delayed land subsidence and the prediction of land subsidence are also discussed in this paper.

Abstract:Being important in such geological processes as crystallization, dissolution, alteration, mineralization and weathering and applied widely to environmental science and material science, the surface reaction of minerals has recently become a geological focus in the world. Based on analyzing the research advances in surface reaction of sulfide minerals, this paper points out that there are problems which have not yet been solved in the study of pyrite dissolution. However, pyrite dissolution is of great significance in many fields such as (1) the theoretical importance (e.g., how is S 2- _2 transformed into S 2- ? How are the charges balanced when S 2- _2 is transformed into S 2- ?), (2) the significance in evaluating mining environment, (3) the phenomenon that most of pyrite in tailing is under the reductive acidic condition, and (4) the control of the dissolution of pyrite over the cycle of sulfur in the ocean. Furthermore, the primary kinetic results from the experiment of pyrite dissolution are also reported in this paper.

Abstract:This paper gives a review of interrelationships between the adsorption behavior and chemical structures of natural organic material (NOM) associated with minerals. The interaction mechanisms of NOM on minerals such as ligand exchange, Van der Waals interaction electrostatic force, hydrophobic effects, ionic exchange and cation bridge are dealt with in detail, and the effects of compositional heterogeneities inherently existing in NOM like hydrophobic properties and molecular sizes upon the adsorption process are also investigated. Generally, the fractions with components of higher hydrophobe and molecular weight are preferentially absorbed by minerals. Solution chemical factors affecting the adsorption such as pH and ionic strength, and environmental effects of NOM- mineral complexation on the global carbon cycle, heavy metals and organic contaminants are described on the basis of abundant information from previous researches. The prospects for future researches in this aspect are given in the end of this paper.

Abstract:Being economical, effective and free from secondary pollution, environment mineral materials have increasingly shown their superiority in the treatment of wastewater containing heavy metals and the soil remediation. They can therefore replace the traditional means. In this paper, the advances in applying environmental mineral materials to tackling cadmium pollution are reviewed, with a discussion on the future application prospects in this aspect.