公婆泉盆地下白垩统新民堡群层序地层和铀成矿特点

本文论述了公婆泉盆地下白垩统新民堡群的层序地层特点———层序分布和时代、界面特征和内部构成、沉积相,以及层间氧化带和铀矿化特点。认为该盆地在公婆泉地段具有一定的找铀矿远景,但北骆驼泉地段铀成矿条件不佳,那林疏怀地段不具备铀成矿远景。     

含铜、铋和银的金精矿堆浸工艺综合回收试验研究

采用生物氧化技术和化学方法,利用堆浸工艺分步提取,对含Au 140~150 g/t、Ag 900~1 000 g/t、B i 9.0%~10.0%、Cu14%~17%的多金属浮选金精矿的综合回收工艺进行了研究。经小型搅拌试验,确定了生物氧化浸铜—氰化浸金、NaC l-FeC l3-HC l体系(氯盐法)浸出铋和银的技术方法。通过柱浸试验,研究了利用该方法分步浸取Au、Ag、Cu和B i在堆浸工艺中的可行性。在10 t精矿的扩大试验验中,验证了柱浸试验所取得的工艺指标和参数。试验中掺入骨架材料,解决了精矿在堆浸中的渗透问题;生物氧化过程中,菌种在含高浓度铜离子浸出液中反复驯化,对铜的耐受力提高到30 g/L;在NaC l-FeC l3-HC l体系浸出B i和Ag时,用H2O2将浸出液中的Fe2+氧化成Fe3+,使浸出液能循环使用,且B i和Ag同时浸出。Au、Ag、Cu和B i的最终浸出率分别为92.98%、65.09%、45.33%和53.49%。     

Product study of the reaction of OH radicals with isoprene in the atmosphere simulation chamber SAPHIR

Atmospheric oxidation of isoprene and its oxidation products methacrolein (MACR) and methyl vinyl ketone (MVK) have an important impact on the photochemical activity in the boundary layer, in particular in forested areas. The oxidation of isoprene by OH radicals was investigated in chamber experiments conducted under tropospheric conditions in the atmosphere simulation chamber SAPHIR at the Research Center Jülich. The aim was to determine the product yield of MVK and MACR in the OH-induced isoprene oxidation and the rate constant of their reaction with OH under real atmospheric conditions. The recently published updated degradation scheme for isoprene from Geiger et al. (2003) was used to determine rate constants and product yields. The fractional yields in the isoprene peroxy radical reaction with NO were found to be 0.41±0.03 for MVK and 0.27±0.03 for MACR. The rate coefficient for MACR with OH was found to be in very good agreement with the recommended value of IUPAC Atkinson (Atkinson et al., 2005). while the rate coefficient for MVK with OH was 27% lower.     

Evaluation of Electro-Oxidation of Textile Effluent Using Response Surface Methods

In the present investigation, treatment of textile effluent using an electrochemical technique was designed and analyzed using the Box-Behnken method. The influence of individual parameters on electro-oxidation of textile effluent has been critically examined using the response surface method (RSM), and a quadratic model for chemical oxygen demand (COD) reduction has been developed. It has been observed from the present analysis that the predicted values are in good agreement with experimental data with a correlation coefficient of 0.945.     

A comparative mineralogical and geochemical study of sulfide mine tailings at two sites in New Mexico, USA

A comparative study of sulfide mine tailings from two sites near Silver City in southwest New Mexico has shown the need for environmental monitoring in a geological context. The Cyprus-Piños Altos and Cleveland deposits consist of Cu and Zn skarn mineralization in the Piños Altos Mountains of New Mexico. Primary ore minerals in both deposits include chalcopyrite, sphalerite, and galena. The Cyprus-Piños Altos Mine ceased operation in 1995 and the Cleveland Mill closed in 1950. The deposits have similar mineralogical characteristics; however, the tailings are different in terms of age, degree of oxidation and method of disposal. The Cyprus-Piños Altos tailings (CPAT) are stored in a lined, bermed impoundment. They are dominantly water-saturated and exhibit no secondary-phase formation. The grains are not cemented and show no evidence of primary-mineral dissolution. The geochemical data show a predominantly primary signature. The tailings pond water is neutral to slightly alkaline (pH?from 7 to 8.3), partly as a result of processing methods. The Cleveland mill tailings (CMT) were deposited in a valley at the headwaters of an ephemeral stream. They are highly oxidized and differentially cemented. They have undergone numerous wet/dry cycles resulting in extensive oxidation. Secondary minerals predominate, and consist mainly of jarosite, goethite, hematite, and Fe-oxyhydroxides and -oxyhydroxysulfates. The pH of the stream draining the CMT is as high as 2.15. Maximum metal contents in the stream immediately downstream from the tailings are 5305?ppm Zn, 454?ppm Cu, 1.16?ppm Pb, 17.5?ppm Cd, 1.4?ppm As, and 0.01?ppm Hg.     

西藏玉龙铜矿床次生氧化富集作用机制

作文阐述了西藏玉龙铜矿床成矿过程中的“沉积初步富集期”和“西藏玉龙铜矿床次生氧化成矿作用模式”,这不仅对指导当前生产具有重要的现实意义,而且为在玉龙铜矿带进一步找矿共作劈了新的方向。     

松辽盆地西南部层间氧化带砂岩型铀矿找矿方向

松辽盆地西南部层间氧化带砂岩型铀矿找矿方向赵忠华刘广传崔长远（核工业东北地质局２４０研究所,沈阳１１００３２）关键词开鲁盆地层间氧化带砂岩型铀矿找矿松辽盆地西南部系指内蒙古自治区哲里木盟及昭乌达盟所辖地区,西临大兴安岭,南依辽西山地,面积约６００００...     

Fast Oxidation Reaction of Nitrite by Dissolved Oxygen in the Freezing Process in the Tropospheric Aqueous Phase

Nitrite oxidation in the tropospheric aqueous phase by freezing was evaluated by freezing a field sample. Nitrite oxidation by dissolved oxygen in the freezing process is much faster than by other oxidation processes, such as reactions with ozone, hydrogen peroxide or dissolved oxygen in an aqueous solution at pHs 3 to –6. At pH 4.5 and 25°C, the lifetime of nitrite in the aqueous phase is ca. 1 hr in oxidation by ozone (6×10^-10 mol dm^-3), ca. 10 hr in oxidation by H₂O₂ (2×10^-4 mol dm^-3), and 7.5 hr (Fischer and Warneck, 1996) in photodissociation at midday in summer. Under the same conditions at a temperature below 0°C, the lifetime of nitrite in the freezing process is estimated as ca. 2 sec when the droplets are frozen within a second. The reaction by freezing is affected by the presence of salts, such as NaCl or KCl, or orgnaic compounds, such as methanol or acetone. The results of freezing a field rain or fog sample showed that nitrite oxidation proceeds below pH 6, and the conversion ratio of nitrate from nitrite increases with decreasing pH. The oxidation of nitrite by freezing was also observed in freezing fog particles generated by an ultrasonic humidifier. The ratios of the concentrations of ions in the winter sample to those in the summer sample (or those in the fog sample) were almost the same values. However, the concentration of nitrite in the winter sample was lower than that estimated by the ratios of other ions. From the present study, it seems that the freezing process plays an important role in the nitrite sink process in the tropospheric aqueous phase.     

A Three-Dimensional Global Model Study of Carbonyl Sulfide in the Troposphere and the Lower Stratosphere

Global distributions of carbonyl sulfide and carbon disulfide have been calculated with a three-dimensional global model of the atmospheric general circulation (ECHAM). The model calculates a global sink strength for carbonyl sulfide of 0.3 Tg S yr^-1, with vegetation uptake being the largest sink. With this sink strength, the sources have to be close to the lower limit of the present estimate in the literature. The calculated mixing ratios are higher in the Southern Hemisphere than in the Northern Hemisphere. This interhemispheric gradient is the opposite of what is observed demonstrating that the present knowledge of the distribution of sinks and sources is not fully adequate. The model calculations support the idea that the open oceans could act as a net sink of carbonyl sulfide. The calculated stratospheric photolysis of carbonyl sulfide constitutes about 4% of the total sink of carbonyl sulfide. A stratospheric production of sulfate from carbonyl sulfide of 0.013 Tg S yr^-1 is obtained, which is 3 to 12 times less than what is needed to maintain the stratospheric sulfate aerosol layer. Although these results are associated with uncertainties, due to the low upper boundary and coarse vertical resolution of the model, they support recent findings of a low stratospheric production of sulfate from carbonyl sulfide. Instead, sulfur dioxide transported from the troposphere is calculated to be the most important precursor for the stratospheric sulfate aerosol layer.