Abstract:On the basis of studying the denitrifying capability of batch cultured Alcaligenes faecalis (A.faecalis), the electrochemical method was applied by poising different cathode potentials (-0.15 V, -0.06 V, +0.06 V vs. NHE) to simulate the energy of photoelectrons from conduction bands of semiconducting minerals. Based on the results obtained, the authors studied the influence of exogenous electrons with different energy levels on the growth and denitrification capability of A. faecalis in the electrochemical system. The result showed that in the case of batch culture, A. faecalis could reduce nitrite significantly under aerobic or anaerobic conditions, rather than reducing nitrate. In simulated photoelectron systems, the formation of cathodic biofilms with denitrification activity on the graphite electrode was observed at all three cathode potentials (-0.15 V, -0.06 V, +0.06 V vs. NHE). Quantitatively, the bacteria was obviously colonized on the cathode poised at -0.15 V, the removal rate of nitrate by A. faecalis was simultaneously the highest (52% after 10 d), compared with 30.5% reduction rate of NO₃^- in the -0.06 V system. Much fewer bacteria were attached sparsely to the electrode surface when the poised potential was at +0.06 V, resulting in the lowest removal rate of 10.6%. In the sterile systems (three cathode potentials without bacteria), the concentration of NO₃^- only decreased a little. The results of this study indicate that photoelectrons with different energies from semiconducting minerals influence the metabolism and denitrification capability of heterotrophic microbe-A. faecalis.

Abstract:Interactions between clay minerals and microbes are ubiquitous in natural environments. It is widely reported that some bacteria may greatly influence the decomposition and transformation of clay minerals by reducing structural Fe(Ⅲ) in Fe- rich smectites. However, the Fe-rich nontronite is not the most common type of smectite. Most natural smectite is montmorillonite bearing poor Fe. The question remains to be answered whether there is other ways of interaction between microbes and Fe-poor smectites except for the Fe(Ⅲ) reduction. The authors therefore studied the effect of Bacillus mucilaginosus on the local structure transformation of montmorillonite. Experiments were conducted under aerobic atmosphere at 35℃ and 1 atm. The mineral samples were bentonite containing about 90% Ca-montmorillonite and 10% cristobalite, collected from Jianping District of Liaoning Province. The aerobic bacteria named Bacillus mucilaginosus 3027, kindly donated by Chinese Academy of Agricultural Science, was inoculated into suspension of sterilized mineral powder and cultured for 20 days. During this period, 3.0 mL solutions were extracted regularly for pH and Si concentration analysis. After the experiments, minerals were collected and characterized by FTIR, XANES, XRD and SEM. Abiotic controls with only sterilized bentonite were conducted simultaneously. Initially, the pH of biotic solutions decreased, probably caused by acidic metabolites produced by bacteria during their growth and metabolism. Meanwhile, Si concentration in the solutions increased, suggesting the release of Si from the tetrahedral sheets of solid mineral. These factors might later trigger a local structure distortion in montmorillonite, as indicated by the FTIR spectrum. The local structure change was also implied by reduced symmetry of coordinate octahedral geometry, as observed from the broadened edge crest in the Fe K-edge XANES. More importantly, newly formed α-quartz was detected in SR-XRD patterns, possibly formed by the Si released from montmorillonite. Furthermore, partial layer and edge curling were observed by SEM.

Abstract:In order to explore the biogenic theory of Huanglong travertine, the authors studied succinic acid,the typical extracellular organic acid of psychrotrophic bacteria isolated from Huanglong. By simulating the low-temperature sedimentary environments of Huanglong water body, the authors investigated the effects of succinic acid on the calcification kinetics as well as the morphology and polymorphism of CaCO₃. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to characterize the morphology and polymorphs of CaCO₃ precipitation. The results were listed as followes: ① High concentration, low pH value and temperature inhibit the calcification to a certain extent. ② High concentration of succinic acid induces the formation of vaterite. ③ High temperature improves the aggregations of microcrystals. In conclusion, succinic acid, as the typical extracellular organic acid of Huanglong psychrotrophic bacteria, participates in the process of sedimentation to a certain extent and plays a role in regulating the morphology and polymorphism of CaCO₃.The results can provide a basis for biogenic theory of Huanglong travertine.

Abstract:Hydrolization and stabilization of iron in environmental media are usually impacted by iron bacteria and their metabolization substances. Iron bacteria are commonly present in natural environments and can use ferrous iron as energy sources for their growth. Bacteria producing extracellular polymeric substances (EPS) mainly including polysaccharides and proteins can combine ferrous iron. The combined ferrous iron can further be bio-oxidized and precipitated into iron minerals. Moreover, bacteria/EPS can catalyze Fe²⁺ bio-oxidization and promote Fe assembly. The biological iron minerals have good chemical properties such as surface adsorption and oxidization-reduction, and good environmental attributes including effective fixation of heavy metals and radioactive nuclides, and catalytic degradation of organic contaminations. So these biological iron minerals play an important role in the study of environmental and biological mineral materials as well as in the treatment of polluted circumstances. Based on the key regulation action on bio-mineralization of iron by bacteria/EPS, the authors introduced iron bacteria and their biological mineralization characteristics in the environment, and mainly described the composition, structure and attribute of EPS exuded by iron bacteria as well as its key role in iron bio-mineralization. Meanwhile, the environmental significance of iron-bacteria/EPS and biogenic iron minerals was also discussed in brief.

Abstract:As one of the essential trace elements in human bodies, zinc has close relationship with the occurrence and development of diseases. Up till now, the distribution of zinc in pathological mineralization is still obscure. This paper focuses on the mineralization of breast cancer, fibroadenoma of breast, breast hyperplasia, breast inflammation, ovarian serous cancer, aortic calcification and coronary artery calcification, based on 28 cases. After the mineral separation process, the measurement of element content was carried out by using micro-area synchrotron radiation X-ray fluorescence (μ-SRXRF). μ-SRXRF mapping was also conducted to determine the distribution of zinc and calcium. The distribution of zinc in all the types of diseases studied is generally consistent with that of calcium, but shows opposite trend in some parts, similar to the Sr-Ca relationship. Therefore, Zn might occupy the place of Ca in the crystal lattices of (carbonate) hydroxyapatite. Besides, Ca/Zn (mM concentration) values of the mineralization in breast cancer is significantly different from those in breast benign lesions (P<0.01), because the concentration of Zn in breast cancer is higher than that of breast benign lesions.

Abstract:The Jinchuan copper-nickel sulfide tailings are of large quantities and contain many Ni, Cu and Co valuable metals, suggesting great economic potentialities. A.f. was studied to reveal the effect of the microbial extraction of valuable metals. Samples were collected to interact with A.f. in different periods and then sulfuric acid chemical effects were conducted. The concentrations of Cu, Ni and Co were tested by Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) to characterize the capability of microbial extraction of valuable metals. The results showed that Cu²⁺, Ni²⁺ leaching rates of the tailings after direct chemical sulfuric acid effect were 73.78% and 69.87%, and Co²⁺ leaching rate was 39.57%. In 10 days' interaction between the tailing samples and A.f., the total leaching rates of Cu²⁺, Ni²⁺ could reach over 80% and Co²⁺ total leaching rate could be up to 70%, which indicates that the involvement of A. f. can greatly facilitate Cu²⁺, Ni²⁺, Co²⁺ leaching of Jinchuan tailings.

Abstract:Chinese hamster lung cells (V79 cells) were exposed to the powder suspensions of chrysotile and its substitutes with different concentrations, and the survival rate of cells was monitored by MTT. After 48 h, the location, distribution and expression of Survivin, Cap43, Bcl-2, p16 and p53 in V79 cell were comparatively examined by immunohistochemistry. The effects of chrysotile and four main artificial substitutes from China's two major production areas on the expression of oncoprotein in V79 cells were studied to investigate the factors of lung cancer. Some conclusions have been reached: ① In the six kinds of powder, the inhibition action of rockwool on the growth of cells was the weakest, whereas the inhibition action of chrysotile from Xinkang of Sichuan and Southern Shaanxi on the growth of cells was the strongest. Chrysotile from Xinkang of Sichuan, chrysotile from southern Shaanxi, glass fiber, ceramic fiber, rockwool and wollastonite have certain degrees of influence on the survival rate of V79 cells. With the increase of the concentration of powder, the survival rate of cells decreases, suggesting dose-effect relationship. ② The expression of Survivin, Cap43 and Bcl-2 is upward regulated and the expression of p16 and p53 was downward regulated in V79 cells, which is obvious in the powder suspension of chrysotile from southern Shaanxi and Xinkang of Sichuan and glass fiber. The expression is mainly in cytoplasm. The results prove that the influence of different kinds of powder on the cells differs in degree. Chrysotile and its substitutes can induce the development of cancer by upward regulating the expression of Survivin, Cap43 and Bcl-2 and downward regulating the expression of p16 and p53.

Abstract:In geological environment, the adsorption behavior of organic pollutants in organo-mineral complexes influences considerably the migration, transformation and end result of organic pollutants. Batch sorption experiments with clay mineral (montmorillonite) and organic matter (humic acid) ratio were designed to adsorb trichloroethylene (TCE) with the purpose of studying the formation and adsorption mechanism of organo-mineral complexes. The results indicate that the interaction between organic and clay mineral improves the interface hydrophobicity of organo-mineral complexes. Meanwhile, the compositions, structures and properties of organic matter in the organo-mineral complexes may change, which can also affect its adsorption behavior. The K_om of adsorbed TCE in the organo-mineral complexes is higher than that of the source humic acid (HA)(0.587 1 L/g), and hardly changes with the increase of the C/M value. TCE initial concentration also has an influence on the Kom value. With C₀=500 μg/L as the boundary, the K_om value increases with the increase of C/M when the concentration is lower than C₀, and it tends to be stable when the concentration is higher than C₀, with the TCE initial concentration having little effect on adsorption behavior.

Abstract:How to remove the formaldehyde from gases effectively has long been one of the hot issues due to its high toxicity in carcinogenicity and teratogenicity. In this paper, nano-magnetite with particle sizes of 0.84～3.35 mm was prepared by reduction of goethite at 300℃ in hydrogen. An heterogeneous oxidation reactor filled with the prepared magnetite was connected with a reactor used to catalyze hydroge peroxide (H₂O₂) oxidation of formaldehyde. The effects of the amount of H₂O₂, the initial concentration of formaldehyde and the flow rate of carrier gas on the formaldehyde removal were investigated in four kinds of reaction system, namely H₂O₂, H₂O₂-ultraviolet (UV), magnetite-H₂O₂, and magnetite- H₂O₂-UV. The mechanism of Fenton photocatalytic oxidation of formaldehyde was evaluated by the combined application of a mass spectrometer total carbon analyzer. The results show that the formaldehyde removal rate in the Fenton photocatalytic oxidation can reach 98% in the situation of UV-10%H₂O₂-magnetite. The stable result can be obtained in different gas velocity effects of different concentrations of formaldehyde. It is indicated that gaseous formaldehyde could be decomposed into CO₂ owing to the synergies of nanoscale magnetite catalyst and homogeneous UV-catalyzed hydrogen peroxide at room temperature, which is a low-cost purification method for gaseous organic contaminants, at least for formaldehyde.

Abstract:As a kind of photocatalytic semiconductor material, natural sphalerite has a considerable photocatalytic capability in visible light. However, its structural defects could be the capture trap of photo-generated electrons, which results in the decrease of its photocatalytic reaction efficiency. To further improve its photocatalytic efficiency in visible light, the authors conducted the heat-treating experimental study of natural sphalerite at 500～1 200℃ in static air. The physical and chemical semiconductor properties of the original and modified samples were analyzed and characterized by using testing means of X-ray Diffraction (XRD) and UV-Vis Diffuse Reflectance Spectra (UV-Vis DRS). Then the photocatalytic experimental study which utilized the original and modified samples to degrade methyl orange was performed. The X-ray diffraction results showed that sphalerite was converted into Zn₃O(SO₄)₂ and then into zincite and franklinite with the increasing heat-treating temperature. Samples were totally converted into ZnO-ZnFe₂O₄ binary compound semiconductor at 1 100～1 200℃. The UV-Vis Diffuse Reflectance Spectra results show that the response of modified samples to visible light is stronger than that of the original sample, and the absorption range of visible light of 900～1 200℃ modified samples is larger than that of 500～800℃ modified samples. The degradation experimental results show that the 1 100～1 200℃ heat-modification of natural sphalerite significantly improved its degradation rate of methyl orange from 54.2% to 99.7%, which indicates that the photocatalytic capability in visible light of 1 100～1 200℃ modified samples is the best. Based on these test and experimental results, the authors infer that the photocatalytic capability in visible light of ZnO-ZnFe₂O₄ binary compound semiconductor is higher than that of the single ZnS semiconductor and other types of compound semiconductor.

Abstract:In order to further investigate paleoclimate evolution of Cenozoic period in the southern margin of Junggar Basin, the authors systematically analyzed mineral compositions and mineralogical characteristics of palygorskite of mudstones and sandstones in the southern margin of Junggar Basin by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that mineral compositions of Cenozoic mudstones are smectite, illite, palygorskite, kaolinite and chlorite. Palygorskite is indicative of an arid, semi-arid and strong evaporation environment. Fibrous or beam palygorskites identified by mineral contact relation are typically authigenic. The arid paleoclimate is consistent with the color change of strata reflected by illite and chlorite mineral assemblages.

Abstract:PM₁₀ samples were collected in summer in coal mine cities of Yima, Pingdingshan and Yongcheng, Henan Province. Scanning electron microscopy (SEM) equipped with X-ray Energy-dispersion spectroscopy (EDX) was employed to study composition, sources and origins of aerosol particles. The result indicates that, according to the chemical composition, aerosol particles can be divided into 5 kinds, i.e., "Si-rich", "Ca-rich", "S-rich", "K-rich" and "Cl-rich" types. Samples from Pingdingshan have abundant Si-rich particles, and their mineral particles had the lowest sulfatization. Samples from Yongcheng had a moderate degree of sulfatization, and the alkaline "Ca-rich" carbonate particles were mostly altered into gypsum through sulfatization. Samples from Yima experienced a very high degree of sulfatization, and certain amounts of mascagnite were formed besides gypsum. In addition, quite a few "K-rich" and "Cl-rich" grains were found in Yima and Yongcheng samples, respectively, probably attributed to straw-burning activities. Based on the difference in the mineral and chemical composition of the PM₁₀ samples, it is concluded that alkaline carbonate mineral, high sulfur coal, high SO₂ concentration resulting from straw burning and relatively high air humidity are beneficial to sulfatization of mineral particles, and sulfate particles have an important effect on the regional climate of coal-mine cities.

Abstract:This paper describes the characteristics of natural dusts, artificial dusts and industrial dusts in such aspects as mineral phases, chemical components, morphology and sizes. Quartz, calcite, albite and sericite constitute the main phases of natural dusts and industrial dusts with high SiO₂, CaO and low K₂O, Na₂O in chemical composition. The fine particles are mainly in the range of 0.3 to 5 μm,of which the dusts of sizes less than 2 μm are over 85%. SEM observations show that the dusts are mainly irregular in shape, and the surface is rough. The dissolution and electrochemical action of dusts in valine acid liquor at the simulated human body temperature (37℃) in 32 hours were investigated. pH and electric conductivity values of these different dusts varied somewhat differently, and increased rapidly in the first 4 hours generally, and chemical reaction reached the equilibrium in 8 hours. Before and after the reaction, the pH values of the solution changed insignificantly; valine had larger buffer function on powder. The total amounts of dissolved ions of K, Ca, Na, Mg were in the range of 31 ～331 mg/L, with the amount of Ca dissolved ions being the highest, reaching 15 to 255 mg/L, followed by K, Mg, Na. The total amounts of dissolved ions of Fe, Zn, Mn, Pb, Ba, Cr, Ni, V were in the range of 3.06～20.60 mg/L and those of Al, Si were 1.12～22.8 mg/L. Each element was dissolved relatively rapidly in the first 8 hours. The relative solubility of dusts in valine acid was in order of wollastonite>serpentine>sepiolite; the cement plant industrial dusts>natural dusts>power plant industrial dusts. The wollastonite and power plant industrial dusts, which have high content of CaO, showed highest solubility, suggesting a poorer corrosion-resisting capability and lower bio-resistibility. Sepiolite and cement plant industrial dusts, which have high content of SiO₂, showed lowest solubility, suggesting a higher corrosion-resisting capability and stronger bio-resistibility.

Abstract:The analytical results of mineral phases and chemical composition show that quartz, calcite, albite and dolomite are the main phases, characterized by high SiO₂, Al₂O₃ and CaO in chemical composition. To discuss the dissolution characteristics of dustfall minerals in organic acid and further discover their harm to human health, the authors took dustfall collected in Xining as the study object and used XRD and FTIR analytical methods to analyze the initial samples and the residual solid and ICP-AES method to determine the concentrations of extracted cations. XRD analytical results show that, after 2 days' dissolution, the calcite was dissolved after 10 minutes, and the specific peak of dolomite disappeared after 16 h; according to the FTIR results, there are no obvious destruction of Si—O, Al—O band. However, the increasing mass of extracted cations in solution reflects the damage to these chemical bonds. In comparison with the dissolution rate of main indissoluble minerals such as quartz, albite and sericite under the same experiment condition, it can be concluded that albite is dissolved faster than sericite. However, the dissolution rate of quartz varies greatly during the dissolution period, and its dissolution sequence relative to albite and sericite should be further investigated. By analyzing the extracted cations and dissolution rate during the dissolution period of dustfall and minerals in citric acid solution, the dissolution sequence of different minerals apart from quartz is in order of calcite, dolomite, albite, sericite.

Abstract:Field emission scanning electron microscopy (FESEM) was used to study the aerosol samples collected in Nam Co and air of Shangri-La under different weather conditions during July～August, 2011. The results showed that particles could be subdivided into 5 major morphological categories, namely soot aggregates, spherical particles (tar ball and fly ash), spherical particles, mineral particles and bio-particles. There existed fly ash in Shangri-La aerosol samples, which however did not exist in Nam Co. Number-size and volume-size distribution of particles in Nam Co aerosol samples displayed peaks in the size range of 0.2～0.3 μm and 1～2.5 μm. The proportion of quantity(44.4%)and that of volume(61.7%)of mineral particles were the highest; size distribution of particles in Shangri-La aerosol samples displayed two major peaks in the size range of over 2.5 μm. The proportion of quantity (51.7%) and that of volume (58.7%) of mineral particles were the highest. Fine particles and coarse particles were the major types of aerosol samples of Nam Co and Shangri-La respectively. The amount (44.4%) of mineral particles was the highest in Nam Co, followed by soot aggregates (29.5%) and spherical particles (26.1%). The quantity proportion (32.59%) of Nam Co aerosol samples was mainly in the size range of 0.2～0.3 μm. Mineral particles were the highest (15%), followed by spherical particles (11.5%) and soot aggregates (6.1%). The quantity proportion (37.5%) of Shangri-La aerosol samples was mainly in the size range of over 2.5 μm. Mineral particles were the highest (17.9%), followed by spherical particles (10%) and soot aggregates (9.6%).

Abstract:Because tailings of Jinchuan nickel mine are of large quantities and contain considerable valuable metals, the recovery of valuable metals from them have aroused more and more attention. Investigations reveal that the modes of occurrence of Ni and Cu are complicated in old flotation tailings, and they occur in different amounts in all the phases of water soluble fraction, exchangeable fraction, carbonate fraction, poorly crystalline Fe oxide fraction, good crystalline Fe oxide fraction, sulfide fraction and silicate fraction. The metal ions released from metal sulfide oxidation are mainly precipitated and adsorbed in situ and not concentrated in tailings. The acid leaching is more appropriate for the recovery of Ni and Cu from the flotation tailings of Jinchuan nickel mine.

Abstract:The influences of slag ultrafine powder (SUP) on such cement hydration products as ettringite (AFt), Ca(OH)₂ and CSH gel under different hydration time spans were studied by using XRD, TG-DSC and ESEM techniques. The results show that SUP participates in the cement hydration process and remarkably affects the formation rate, product content and morphology of hydration products. Moreover, with increasing SUP dosage and prolonging hydration time, SUP gradually further affects the cement hydration products.

Abstract:The study adopting the improved soda lime sintering process was focused on the process of aluminum dissolution, with the desilication oil shale ash used as the raw material. This paper mainly deals with the influence of sintering temperature, sintering time, alkali aluminum ratio and calcium silicon ratio on the phase characteristics and the aluminum dissolution rate. The results show that the alumina extraction rate could be up to above 94% under the conditions of sintering temperature 1 150℃, sintering time 1.5 h, and ratio of raw feed rate Na₂O/Al₂O₃=1.0, CaO/SiO₂=1.0.

Abstract:The high Ti-bearing blast furnace slag is an important mineral resource which contains abundant TiO₂. In order to achieve the enrichment of TiO₂, the authors investigated the phase transitions and reaction mechanism of the blend of high Ti-bearing blast furnace slag and ammonium sulfate in the roasting process. The chemical calorific effect of the blend and the phase composition of high Ti-bearing blast furnace slag as well as the roasting products were characterized by means of TG-DTA and XRD. The results showed that the main mineral phases of the slag were perovskite, diopside and spinel, and there existed three endothermal valleys in the course of heating, which were caused by thermal decomposition of (NH₄)₂SO₄, reaction of the decomposition product with metal oxides in the slag and thermal decomposition of the intermediate product respectively. Ammonium sulfate was decomposed into (NH₄)₃H(SO₄)₂ under lower temperature, which reacted with the metal oxides in the perovskite and diopside to form CaSO₄. Al₂O₃ in the spinel, which reacted with (NH₄)₂SO₄ and (NH₄)₃H(SO₄)₂ to generate (NH₄)₃Al(SO₄)₃ at 300～375℃; at 375～425℃, (NH₄)₃ Al(SO₄)₃ reacted with Al₂O₃ to form NH₄Al(SO₄)₂, and then NH₄Al(SO₄)₂ was decomposed into Al₂(SO₄)₃ when the roasting temperature rose to 500℃.

Abstract:Based on the idea of "treatment of waste by waste", the authors studied the reaction temperature, time span, liquid-solid ratio and nitrogen-sulfur ratio of carbon dioxide fixation by phosphogypsum carbonation, which affect the rate of conversion of phosphogypsum by wet carbonation treatment. The mineral phases and micro appearance in phosphogypsum and the product were analyzed by XRD and SEM-EDS. The results show that gypsum in phosphogypsum is wholly transformed into calcite, a little anhydrite is transformed into calcite because of its low solubility, and quartz is inert in the reaction. Under the optimum technological conditions, the conversion of phosphogypsum takes place under the conditions of temperature 65℃, time of reaction 60 min, liquid-solid ratio 3.0, and nitrogen-sulfur ratio 2.25, with the best value being 95.24%. The result is of some practical significance for conversion of phosphogypsum into fixed carbon and reducing discharge as well as further resource utilization of phosphogypsum.

Abstract:Using X-ray fluorescence spectrometer (XRF), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), the authors studied mineralogical characteristics of chrysotile asbestos tailings from the Aksay ore district and the preparation of high purity silicon as well as magnesium compounds. The results show that the chemical compositions of the asbestos from three mines are SiO₂ 37.01%～39.35%,MgO 37.00%～38.92% and TFe₂O₃ 6.02%～8.37%, the ignition loss is 12.29%～13.56%, and the main mineral composition of chrysotile asbestos tailings is serpentine, together with small amounts of talc, magnetite, brucite and magnesite. Magnesium sulfate was obtained by acid leaching of chrysotile asbestos tailings, and magnesium hydroxide powders in "house of cards" form, "flake" basic magnesium carbonate sample powders and magnesium oxide powders in "house of cards" form were prepared. The acid slag alkali leaching reaction produced sodium metasilicate, and then salt leaching reaction synthesized white carbon black sample. These results have an important theoretical significance and practical significance for resource utilization and environmental protection of chrysotile asbestos tailings from the Aksay ore district.

Abstract:Based on the characteristics of magnesium oxides which are very abundant in the chrysotile asbestos tailing and mineralogical research on asbestos tailings, the authors employed the ammonium sulfate calcination method to extract magnesium from asbestos tailing, and used the leaching liquid as the raw material to prepare the basic magnesium carbonate. The influence of the reaction temperature on the phase, morphology and structure of the product during the preparation of the basic magnesium carbonate were characterized by means of XRD, SEM, FT-IR and TG-DTA. The results indicated that the products were needle-like magnesium carbonate hydrate at the temperatures below 65℃, flake-like magnesium carbonate hydrate at the temperatures higher than 85℃,and short column-like or granule-like magnesium carbonate hydrate and flake-like magnesium carbonate hydrate at 75℃. Heated magnesium carbonate hydrate would remove part of H₂O and CO₂, which turned into flake-like basic magnesium over 100℃. Research performed in this paper has some theoretical and practical significance for environmental protection and comprehensive utilization of chrysotile asbestos tailings.

Abstract:Releasing large amounts of acidic water and heavy metals, polluting groundwater and surface water, and damaging ecosystem, mine tailings have become a focus of attention. Using multiple analytical technologies such as scanning electron microscope (SEM), Electro-Probe Microanalyzer (EPMA), (X-Ray Powder Diffraction) XRD, Raman Spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES), the authors studied the modes of occurrence of arsenic in the tailings from the Yangshanchong tailing pool in Tongling, Anhui Province. The results show that there are three different valences of arsenic in tailings, i.e., As(-Ⅰ), As(Ⅲ) and As(Ⅴ). In the less weathered tailings of the lower part,arsenic exists as As(-Ⅰ), As(Ⅲ) and As(Ⅴ); in the strongly weathered tailings of the upper part, only As(Ⅴ) has been observed. The analysis reveals that As(-Ⅰ) and As(Ⅲ) gradually turns to As(Ⅴ) from bottom to top. Arsenic of the lower tailings mainly occurs in pyrite, while on the surface, arsenic is mostly distributed in ferric oxyhydroxides and sulfates.

Abstract:As there exists the serious problem of environmental pollution caused by antibiotics at present, the experimental research on the adsorption of montmorillonite (Mt), a highly active clay mineral, for tetracycline (TC) from aqueous solutions was carried out in this paper. Batch adsorption experimental methods were used to make the investigation with the emphasis placed on the influences of initial TC concentration, initial pH as well as cation types of electrolytes and their concentrations on the adsorption properties of Mt for TC. The results show that the adsorption behavior of Mt for TC can be well described with Freundlich isotherm, and the maximum adsorption capacity calculated by the Langmuir equation was 625 mg/g; however, the strongest adsorption of TC on Mt may occur under the condition of higher acidic medium pHs (pH=2～4), followed by weak acidic-weak basic pHs from 5 to 9. In addition, varying types of cations can obviously affect the adsorption capabilities of Mt, suggesting that the higher their state of valence, the more evident the impact extent of TC adsorption. Mt is therefore a highly efficient adsorbent and can be applied to the treatment process of TC wastewater.

Abstract:In this study, orthoclase and sodium chloride powder were mixed up, and their chemical reaction was carried out at 810℃. The XRF analysis was applied to analyze the chemical composition before and after the reaction quantitatively. Two grams of orthoclase were mixed with 20 g and 40 g powders of NaCl, and the reaction lasted for 12, 24, 36, 48, 72 hours respectively. After mixture with 20 g NaCl, the content of Na₂O in orthoclase varied from 3.35% in original samples to 9.05%, 9.33%, 10.1%, 10.5% and 10.8% in the resultant materials, separately. However, after mixture with 40 g NaCl, the content varied to 9.98%, 10.3%, 10.5%, 10.9% and 11.9% correspondingly in the same time span. Ion exchange velocities for orthoclase slowed down after 12 hours and the quantity of ion exchange increased slowly. The Na⁺ distribution coefficient was calculated according to the formula of ion exchange reaction. The Na⁺ distribution coefficient for molten salt of higher concentration was higher than that of lower concentration in the experiment and the reaction under the condition of higher concentration proceeded more thoroughly. Orthoclase could serve as a good material of ion exchange.

Abstract:In this paper, magnetic zeolite was synthesized by kaolinite by using the hydrothermal method. Before crystallization the synthesized Fe₃O₄ magnetic fluid was added so as to synthesize the magnetic zeolite 4A in which Fe₃O₄ content came to 4.48%. Then the zeolite was applied in the adsorption experiments for the ammonia nitrogen in the solution. A combination of XRD and magnetic susceptibility analysis was performed in this synthesized magnetic zeolite 4A. Besides, the experimental data were utilized to fit the adsorption isotherm equation and then to perform the kinetic analysis. The results showed that the loading of Fe₃O₄ had little effect on the crystal structure, and magnetic susceptibility of magnetic zeolite 4A was stable enough to be reused. Two isotherm adsorption models were used and the Freundlich isotherm was in better agreement with the adsorption results. Furthermore, the fitting results of Lagergren quasi second-order rate equation showed that the adsorption rate was controlled by the chemical adsorption, and the adsorption of ammonia nitrogen conformed to the quasi second-order dynamics mechanism.

Abstract:The associated diatomaceous earth mining area in the Xianfeng large-size lignite ore district is the second largest diatomaceous earth mining area in China with high organic matter from 15% to 30%, belonging however to low-grade diatomite which has not been effectively utilized by traditional processes due to low economic value. This study aimed at utilizing high organics-bearing diatomite as waste resources and improving the comprehensive utilization proportion of mineral resources in the Xianfeng coal mining area. The diatomite with high organics was purified by acid washing and then calcined under N₂ as a protective atmosphere at high temperatures of 500 to 800℃. The organic matter was carbonized with the formation of amorphous activated carbon/diatomite compound materials. Electronic microscopy showed that the amorphous activated carbon was uniformly dispersed on the surface and interior pores to form a stable amorphous active carbon/diatomite compound material. The specific surface area and methylene blue adsorption test showed that carbon/diatomite had much higher performance than conventional diatomite products. The novel carbon/diatomite had specific surface area of 55.79 m²/g and methylene blue saturated adsorption capacity of 41.87 mg/g. The significantly saturated adsorption capacities of heavy metal ions were Pb²⁺ 54.47 mg/g, Co²⁺ 37.34 mg/g and Sr²⁺ 25.1 mg/g, respectively. The results show that the proposed technological processes are helpful to substantial improvement of economic values of Xianfeng diatomite, and hence has broad potential applications as a novel absorbent.

Abstract:The palygorskite clay coated with iron oxide was prepared as the adsorbent and the adsorption properties and mechanisms of adsorbing Cr(Ⅵ) were investigated, with a discussion on the adsorption kinetics and thermodynamic characteristics. The results demonstrate that the adsorption function of Cr (Ⅵ) on modified palygorskite decreases significantly with increasing pH. The equilibrium can be reached in about 90 minutes and the adsorption processes seem to follow pseudo-second-order equation most effectively at an optimum pH of 4.0, the rate constant increases with the rise of temperature and the adsorption activation energy is 18.90 kJ/mol. Adsorption isotherms fit Langmuir equation fairly well, the adsorption enthalpy is 28.29 kJ/mol and the adsorption Gibbs free energy changes are in the range of -25～-20 kJ/mol. The adsorption process is endothermic and spontaneous, with the coexistence of physical adsorption and chemical adsorption.

Abstract:Phenolic wastewater is one of the common industrial pollution sources. Ozonation with brucite and natural hydroxide magnesium has more effective impact than single ozonation of phenol degradation. The function of brucite in ozonation of phenolic wastewater was discussed previously as OH^- from hydrolyzed Mg(OH)₂ forming basic catalyst and raising the activities of O₃. In this study, two batch experiments with different brucite-phenol ratios were carried out with close attention paid to the final sedimentary products. The experiments show that Mg²⁺ from hydrolyzed Mg(OH)₂ could combine with intermediate products of phenol oxidation to form indissoluble deposits and raise the processes of phenol degradation. When the initial concentration of phenol was 47 g/L, and the controlled dosage of brucite by C/Mg (atoms ratio of carbon to magnesium) equal to 30, the only residual solid after 3 hours O₃ aeration was glushinskite (magnesium oxalate dihydrate) which substituted for the brucite, as supported by XRD and TG/DSC examination. At the terminal of the reaction, the test solution showed pH below 4 and removal of nearly 40% of TOC (Total Organic Carbon). In a comparative experiment changing the initial concentration of phenol to 1.5 g/L with C/Mg (atoms ratio) equal to 1 and under the same condition of O₃ aeration, the residual solid of the exam was still brucite, the terminal pH was 10 and 92.8% of TOC was removed. The results from two examinations reveal that the process of ozonation of phenolic wastwater is characterized by continued acidification. At least under the higher initial C/Mg ratio condition, the primary proton can neutralize hydroxyl from hydrolyzed brucite. In this case the terminal sediments are only glushinskite. Obviously, Mg²⁺ is derived from hydrolyzed of brucite; however, glushinskite is stable in an acidic environment. Both Mg²⁺ and OH^- from brucite play a role of degrading phenol in water.

Abstract:The zinc-bearing iron-rich mineral material (wasted magnetite, WMT) was separated from an iron-rich industrial solid waste. This WMT was applied as a heterogeneous Fenton catalyst to investigate decolorization and degradation of the azo-dye orange G (OG) in wastewater. The Fenton catalytic activity of WMT was explored in batch experiments conducted under varying conditions with the emphasis placed on the evaluation of the performance properties via their Fenton process optimization. The result showed that WMT-catalyzed heterogeneous Fenton reactions mostly followed zero-order kinetic model (R²>0.96) in dark irradiation, and followed pseudo-first-order kinetic model (R²>0.97) in visible irradiation. Moreover, WMT represented good heterogeneous photo-Fenton catalytic activity for the OG oxidative removal in the process. It is suggested that WMT may be a potential heterogeneous photo-Fenton catalyst available for the removal of the azo-dyes under the irradiation condition.

Abstract:K-birnessite was synthesized by air oxidation of Mn(Ⅱ) under alkaline conditions for ion exchange experiment. Energy-dispersive spectroscopy showed that K-birnessite has better cation exchange capacities with Ba²⁺, Pb²⁺, NH⁺₄ and Ag⁺ than Li⁺, Cu²⁺, Zn²⁺, Ni²⁺, Mg²⁺, Ca²⁺, Na⁺ and Cd²⁺. X-ray powder diffraction and infrared spectra revealed that Li⁺, Cu²⁺, Ba²⁺, Zn²⁺, Ni²⁺, NH⁺₄, Pb²⁺, Mg²⁺, Ca²⁺, Na⁺ and Cd²⁺ exchanged birnessites preserved the interlayer structure with d spacing of about 0.7 nm except for Ag-birnessite, but this exchange process greatly changed the crystallinity or the ordering of cations in the interlayer and MnO₆ octahedra in the layers of birnessite. The thermal property of cation-exchanged birnessites examined by DSC-TGA curves indicated that the important phase transformation and structure evolution occurred in the ranges of 150～250℃ and 500～700℃. Cation-exchanged birnessites experienced a disorder state and recrystallization for new structural arrangement as the temperature increased. The nature of heated products depends on the nature of cations, especially the size of ion radius. Large cations of K⁺, Ba²⁺, Na⁺, Pb²⁺ and Ag⁺ with radius larger than or close to 0.1 nm gave rise to hollandite type (2×2) tunnel and even todorokite type (3×3) tunnel manganese oxides. Birnessites doped with small cations (<0.1 nm) of Mg²⁺, Ca²⁺, Cd²⁺ and Zn²⁺ cations decomposed into hausmannite and of Cu²⁺, Ni²⁺, Li⁺ and heat-labile NH⁺₄ cations decomposed into bixbyite.

Abstract:Synthetic alkaline birnessites with the average Mn oxidation states of 4.02、3.85 and 3.70 are applied to investigate the kinetic characteristics of As(Ⅲ) and Cr(Ⅲ) oxidation. The results show that initial stage of As(Ⅲ) and Cr(Ⅲ) oxidation by Bir-OHs comply with the first order kinetics and then the apparent rate constant (k_obs) decrease with the reaction down to zero due to both the effects of the reverse reaction and the reaction site passivation resulting from the product accumulating on the mineral surface. Nearly no Mn(Ⅱ) release was detected in the initial reaction stage of As(Ⅲ) oxidation, Mn(Ⅱ) were adsorbed to the surface of mineral and then shielded the reaction sites, thus the k_obs decreased sharply. In contrast, for Cr(Ⅲ) oxidation, although Mn(Ⅱ) release lagged behind of Cr(Ⅵ) release in the initial reaction stage, then more and more Mn(Ⅱ) were released to the solution as the reaction went on, the ratios of released Mn(Ⅱ) to Cr(Ⅵ) gradually increased up to the theoretical reaction stoichiometry. The effect of Mn(Ⅱ) shielding the surface reaction sites in the Cr(Ⅲ) oxidation is much less than that in the Cr(Ⅲ) oxidaton, the k_obs decreases much slowly after the initial reaction stage. The higher the Mn AOS, the longer it maintained the first order kinetics in the initial reaction stage. Therefore, alkaline birnessite with higher Mn AOS exhibits the more rapid oxidation reaction towards As(Ⅲ) and Cr(Ⅲ), and the behavior of product release to the solution is a significant factor determining the kinetics of the reaction.

Abstract:The sphalerite oxidative kinetics in hypergene condition was simulated and studied by means of a mixed flow reactor in the pH range of 1.0～7.8, dissolution temperature from 20℃ to 55℃, ferric ion concentration from 1.0×10^-5 to 1.0×10^-2 mol/L, and O₂ flux 0.5 L/min, with ferric ion and O₂ as oxidants. The results indicate that, with ferric ion as the oxidant, the oxidation rate of sphalerite increases with increasing ferric ion concentration, temperature and decreasing pH value, and that, under the conditions studied, the dissolution rates of Zn and Cd are approximately similar to each other, with the activation energy being 41.75 kJ/mol and 42.51 kJ/mol, respectively, which suggests the oxidation rate of sphalerite is controlled by mineral surface chemical reaction. However, with O₂ as the oxidant, the oxidation mechanism of sphalerite varies with the pH value, and its oxidation rate decreases with increasing pH value in the pH range lower than 5.95, whereas the increase of pH value results in a increase of the oxidation rate in the range of pH value greater than 7. The oxidation rate of sphalerite based on double logarithmic dealing with data can be set up.

Abstract:X-ray diffraction analysis shows that it is difficult to discriminate various kinds of A Fe₃(SO₄)₂(OH)₆(A=K⁺, H₃O⁺) jarosites because their XRD data are very similar to each other. However, a series of jarosites could be discriminated by XRD and EDS method. The XRD result shows that 003 and 107 lattice spacing (d) of the jarosite increases with K⁺ ion content, whereas 033 and 220 lattice spacing (d) decreases with increasing K⁺ ion content. Their relationship is described by the regression equation. The explanation of this result from the crystal structure theory is that K⁺ and H₃O⁺ ions are located in the larger space and distributed along Z axis. Obvious change of jarosite crystal structure in the Z axis occurs with the mutual substitution between K⁺ and H₃O⁺ ions.

Abstract:Thermal decomposition reactions of dolomite samples from Wansheng area of Chongqing were investigated by the simultaneous TG/DTG experiments to reveal the thermal decomposition mechanism and influential factors. The results show that the thermal decomposition process of dolomite samples follows the three-dimensional diffusion (three dimensional particle shape, Jander equation) model, and the value of the activation energy for the thermal composition is 357.4 kJ/mol. The kinetic model of the thermal decomposition process has been established based on the research results. The contrast experiments of the influential factors show that the value of the activation energy for the thermal composition would be increased significantly with the decrease of sample particle size and the increase of sample weight; nevertheless, the change of the SiO₂ content of dolomite and the flow rate of protective gas has little impact on the activation energy of thermal decomposition of the dolomite samples.

Abstract:Two abiotic synthesis methods of Schwertmannite were studied through overall comparison, and cleaning methods of synthetic Schwertmannite were improved. Schwertmannite mineral synthesis time of the slow synthesis method and that of the rapid synthesis method are approximately the same. Mineral characteristic peaks and infrared spectrum characteristics of Schwertmannite by the slow synthesis method were more obvious than those of Schwertmannite's by rapid synthesis method. The mineral particle diameters of synthetic Schwertmannite by slow method were larger than synthetic Shcwertmannite by the rapid method. Dialysis cleaning process of synthetic Schwertmannite in traditional slow synthesis method is time consuming, but cleaning procedures of synthetic Schwertmannite are not included in the rapid synthesis method. Dialysis method is more suitable for cleaning synthetic Schwertmannie than the centrifugal method. Dialysis time can be reduced by 20 d through using dialysis bag with 3 500 molecular weight cutoff, and cleaning efficiency is raised greatly. Freeze-drying method can reduce greatly the aggregation degree of synthetic Schwertmannite than constant temperature (40℃) drying. Colors and characteristics of dried synthetic Schwertmannite can be recovered by grinding.

Abstract:The trace element and mineral characteristics of the soil in the Dexing copper deposit were analyzed in this paper. The analytical results show that the soil is enriched with heavy metals, and the heavy metals and clay minerals show good consistency in top soil. The leaching experimental results of the soil column indicated that, when the leaching time was 451 hours, the adsorption capacity of the soil for Pb²⁺ was 2 584.75 mg/kg, and the adsorption was unstable during the first half period and then gradually attained equilibrium during the second half period. After leaching, the relative mass fraction of minerals in the soil column changed, and the amount of clay minerals decreased. The adsorption capability of clay minerals for Pb²⁺ was different in different soil layers.

Abstract:The Yongqing granodiorite, located in the inner part of the Jiamusi massif in eastern Northeast China, was previously considered as a part of the Early Paleozoic Mashan complex. LA-ICP-MS zircon U-Th-Pb isotopic analysis yields a middle Permian age of 265±1 Ma (MSWD=2.1). The granodiorite is composed of subhedral to euhedral plagioclase (30%～35%), anhedral quartz (25%～30%), anhedral K-feldspar (20%～25%) and subhedral biotite (10%～15%). Geochemically, the granodiorite is high-K calc-alkaline to calc-alkaline and peraluminous in composition, and shows very good linear correlation between Sm/Dy and Dy, Sr/Y and Y, and Ce/Sm and δEu, probably resulting from assimilation and contamination of some country rocks during the emplacement without melt fractionation. Taking the effects of assimilation and contamination into consideration, the authors hold that the high Sr/Y and Sm/Dy ratios of parental magma of the Yongqing granodiorite might imply the presence of garnet in the source. The depth of the source rocks might have been greater than 25 km, distinctly different from the depths of contemporaneous intrusions in southern Jiamusi massif and the Zhangguangcai Mountain. Combined with previous studies, it is suggested that the Yongqing granodiorite was formed during or after the collision between the Jiamusi massif, Songnen block and Xingkai block.

Abstract:The metamorphism and age of UHP eclogites and their country rocks constitute the key to understanding the formation and evolution of the UHP metamorphic terranes. However, because of simple mineral assemblages and lack of P-T sensitive minerals, it is difficult to relate the petrological characteristics with the metamorphic ages of the country rock paragneiss. This paper focused on the petrology and in-situ electronic microprobe monazite U-Th-total Pb dating of three paragneisse samples from Dulan terrane in North Qaidam UHP metamorphic belt. As a result, ages of 433±15.4 Ma (8S01 from Shaliuhe cross-section), 440±11.2 Ma (8S55 from Yematan in North Dulan) and 435±14.7 Ma (8S116 from South Dulan) were obtained respectively. Monazites in paragneiss from Shaliuhe section and South Dulan yielded similar ages, which are different from ages of samples from North Dulan by about 5 Ma. The analyses of the three monazite samples from the Dulan terrane show that they are enriched in LREE and lack of HREE, characterized by positive Eu anomaly. The Eu/Eu^* ratios of monazite have coupling relationship with Ca content in garnet in the matrix. In combination with petrological investigation, P-T calculation and monazite microprobe analysis, the authors hold that the monazite in this study grew or recrystallized under the amphibolite facies metamorphic conditions during retrogression. The monazite analyses with ages from 440 Ma to 430 Ma in paragneiss from South Dulan are characterized by relatively high Y content. Furthermore, the Y content has an obvious negative correlation with Eu/Eu^*, suggesting that part of the paragneiss in Dulan terrane had experienced amphibolite facies metamorphism during 440～430 Ma.