无机矿质颗粒悬浮物对富营养化水体氨氮的吸附特性

利用蒙脱土、高岭土和太湖沉积物矿质组分3种材料,模拟研究了水体悬浮矿质颗粒物对富营养化水体中氨氮的吸附特性.实验表明,30min内3种材料对氨氮的吸附基本可达到平衡;等温平衡吸附均符合Henry吸附模式,在无机矿质颗粒悬浮物浓度1000mg/L,初始氨氮浓度1.0mg/L,pH=7.00实验条件下,吸附分配系数分别依次为548.30,287.36,191.27L/kg.相同实验条件下,随着pH、盐度和温度的增大或升高,矿质颗粒对氨氮的平衡吸附量均有不同程度的减小趋势,pH的影响较显著.随着悬浮颗粒物浓度在1000mg/L以下范围增大,固相氨氮平衡吸附量显著减小.

SO2在矿质颗粒物表面非均相反应研究进展

我国秋冬季雾霾频发,对人类健康造成巨大威胁。大气中SO2经系列物理化学反应产生的硫酸盐气溶胶是雾霾产生的元凶,其中矿质颗粒物参与的SO2表面非均相反应尤为重要,因此,厘清矿质颗粒物表面硫酸盐的形成机制是解析大气雾霾形成的关键科学问题。本文综述了SO2在不同类型氧化型矿质颗粒物表面非均相反应的研究进展,讨论了多污染物共存体系、湿度和光照对SO2非均相反应的影响,并对目前矿质颗粒物表面非均相反应研究中存在的问题进行了评述,旨在加深对矿质颗粒物促进硫酸盐形成机制的认识,助力揭示我国雾霾的成因,进而为雾霾治理提供理论指导。

Pore structure of ore granular media by computerized tomography image processing

The pore structure images of ore particles located at different heights of leaching column were scanned with X-ray computerized tomography (CT) scanner, the porosity and pore size distribution were calculated and the geometrical shape and connectivity of pores were analyzed based on image process method, and the three dimensional reconstruction of pore structure images was realized. The results show that the porosity of ore particles bed in leaching column is 42.92%, 41.72%, 39.34% at top, middle and bottom zone, respectively. Obviously it has spatial variability and decreases appreciably along the height of the column. The overall average porosity obtained by image processing is 41.33% while the porosity gotten from general measurement method in laboratory is 42.77% showing the results of both methods are consistent well. The pore structure of ore granular media is characterized as a dynamical space network composed of interconnected pore bodies and pore throats. The ratio of throats with equivalent diameter less than 1.91 mm to the total pores is 29.31%, and that of the large pores with equivalent diameter more than 5.73 mm is 2.90%.

Simulation of pore scale fluid flow of granular ore media in heap leaching based on realistic model

Two-dimensional images of the granular ore media with different grain sizes were obtained from the X-ray computed tomography.Combined with the digital image processing and finite element techniques,the original grayscale images were transformed into the finite element models directly.By using these models,the simulations of pore scale fluid flow among particles were conducted with the COMSOL Multiphysics,and the distribution characteristics of fluid flow velocity and pressure were analyzed.The simulation results show that there exist obvious preferential flow and leaching blind zone in each granular medium.The flow velocity at pore throat is larger than that of pore body and the largest velocity reaches 0.22 m/s.The velocity decreases gradually from the center of pore throat and body to the surface of particles.The flow paths of granular media with larger grain size distribute equally,while the fluid flow velocities in most of areas of granular media with smaller grain size are lower,and some of them approach to zero,so the permeability is very low.There exist some pore clusters with different pressures,which is the basic reason for the uneven flow velocity distribution.

Solid state synthesis of nano-mineral particles

Many researchers in academia and industries are interested in reducing particle sizes from few submicrometers to nano-meter levels.These nano-particles find application in several areas including ceramics,paints,cosmetics,microelectronics,sensors,textiles and biomedical,etc.This article reviews the present state of the art for solid state synthesis of mineral nano-particles by wet milling,including their operating variables such as ball size,solid mass fraction and suspension stability.This article concludes and recommends with a critical discussion of nano-particles synthesis and a few common strategies to overcome stability issues.

Effect of solids on pulp and froth properties in flotation

Froth flotation is a widely used process of particle separation exploiting differences in surface properties. It is important to point out that overall flotation performance(grade and recovery) is a consequence of the quality and quantity of the solid particles collected from the pulp phase, transported into the froth phase, and surviving as bubble-particle aggregates into the overflow. This work will focus on studying these phenomena and will incorporate the effects of particle hydrophobicities in the 3-phase system. Solids are classed as either hydrophilic non-sulphide gangue(e.g. silica, talc), hydrophilic sulphide(e.g. pyrite), or hydrophobic sulphide(e.g. sphalerite). Talc is a surface-active species of gangue that has been shown to behave differently from silica(frother adsorbs on the surface of talc particles). Both are common components of ores and will be studied in detail. The focus of this work is to investigate the role of solids on pulp hydrodynamics, froth bubble coalescence intensity, water overflow rate with solids present, and in particular, the interactions between solids, frother and gas on the gas dispersion parameters. The results show that in the pulp zone there is no effect of solids on bubble size and gas holdup; in the froth zone, although hydrophilic particles solely do not effect on the water overflow rate, hydrophobic particles produce higher intensity of rates on water overflow and bubble coalescence, and many be attributed to the water reattachment.

光照对SO_2在矿质氧化物表面非均相反应的影响

使用原位漫反射红外傅里叶变换光谱(DRIFTS)研究了SO_2在α-Al_2O_3、TiO_2、CaO和α-Fe_2O_3颗粒物表面的非均相反应,考察了紫外光光照(波长约365 nm)对SO_2在不同氧化物表面反应的影响.结果表明,无紫外光照射条件下,SO_2在TiO_2、α-Al_2O_3、CaO颗粒物表面反应的主要产物为亚硫酸盐;有紫外光照射条件下,SO_2在TiO_2、α-Al_2O_3、CaO颗粒物表面反应的主要产物为硫酸盐;但紫外光照射对SO_2在α-Fe_2O_3表面的反应并没有明显的影响.推测机理可能是光照促进了颗粒物表面的亚硫酸盐向硫酸盐的转化.