Insufficient initial hydration of GCLs from some subgrades: Factors and causes

Water retention and hydration tests are reported for three needle punched geosynthetic clay liners (GCLs). GCLs hydration and their maximum hydration capacity were assessed against subgrade soils prepared at different initial gravimetric water contents. The subgrade soil mineralogy and particle size distribution, as well as the carrier geotextiles used in GCLs, are shown to have a significant impact on the GCLs hydration behaviour. This work highlights the need to consider the unsaturated properties of both the GCLs and the subgrade soil when assessing the hydration of the GCLs. At gravimetric water contents above the GCL water entry value (≈30%), some forms of GCL configuration may be better than others with respect to ability to hydrate from a given soil. However, the partial hydration of GCL is mostly controlled by the bentonite microstructure for gravimetric water contents below the water entry value of the GCLs.     

矿物学因素对黄铜矿微生物浸出影响的研究现状

黄铜矿微生物浸出一直是近年来的研究热点,研究者们主要从化学、矿物学及生物化学等角度展开对黄铜矿与细菌相互作用的研究。本文综述了影响黄铜矿微生物浸出的矿物学因素方面的研究,指出晶格能、晶格缺陷和同质多像等是影响微生物浸出黄铜矿的重要因素,并对未来的研究趋势进行了展望,这对日后黄铜矿微生物浸出工作的发展具有重要的意义。     

Tropical Soils–Acid Mine Drainage Interactions: Breakthrough Curves and Some Transport Parameters

The interactions between acid mine drainage (AMD) and three tropical clayey soils have been studied through hydraulic conductivity and batch sorption/dissolution testing. After 19–24 pore volumes of AMD flow through the soils, the measured final hydraulic conductivity ranged between 1.1×10?11 and 3.3×10?11?m/s. The pH, electrical conductivity, and solute breakthrough curves obtained suggested the soils had low acid-buffering capacities. Also, several chemical species were released from the soils due to AMD attack of soil grains and mineral. The batch tests revealed high dissolution of species such as sodium, cobalt, and sulfate from the soils by AMD. The results also indicated dissolution of metals from soil constituents, desorption of chemical species, and transformation and dissolution of soil minerals due to AMD attack. The results of the study showed that, in general, the soils were not effective in attenuating contaminants present in the AMD. Thus, they may not be used alone to construct liners for acid-generating waste mine containment facilities.     

MANTLE: a program to calculate A 30 kbar norm assemblage

MANTLE is a FORTRAN IV code to calculate mineral assemblages which would be expected at a pressure of 30 kbars from a bulk composition given in nine oxide components. The program also calculates the theoretical STP bulk density of the assemblages, and has been used for modeling mantles of the terrestrial planets. With some improvements it may prove useful in modeling the upper mantle of the earth.     

Reactivity of waste generated during lead recycling: an integrated study

Lead consumption in Europe is 2.054 M tonnes/year, more than 70% of which is produced by recycling and, more specifically, the recycling of car batteries. This industry is jeopardised by the method employed so far, recycling by alkaline fusion, because the treatment produces 200,000 tonnes of toxic and unstable slag. The study presented here attempts to clarify the approach and the combined tools employed (mineralogy, chemistry, leaching, thermodynamics), to construct a coherent physicochemical model of slag behaviour. The model was then used to carry out sensitivity analyses with various landfill scenarios, and to propose adjustments to the process to recover the residual heavy metals and to upgrade as secondary raw products the co-products generated by the inerting of the slag.     

Effect of synthetic Beishan site water and cement solutions on the mineralogy and microstructure of compacted Gaomiaozi(GMZ) bentonite

The mineral alteration and microstructure evolution of compacted GMZ bentonite was investigated during the long-term in the Beishan area, a candidate for a high-level radioactive waste repository in China. The compacted GMZ bentonite samples at initial dry densities of 1.5 and 1.7 Mg/m³ were infiltrated by synthetic Beishan Site Water (BSW) and two synthetic cement solutions (Young Cement Water -YCW and Evolved Cement Water - ECW) under constant volume conditions for about 2 months in this study. X-Ray diffractometry (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM-EDS) tests were carried out to observe the mineralogy and microstructure of the specimens after experiencing the three types of pore solutions.There is evidence of cation exchange reactions, some zeolites and C-S-H in the GMZ bentonite after the infiltration of alkaline solutions. The hydration of alkaline solutions and mineralogy alteration result in changes to the microstructure of compacted GMZ bentonite. The generated secondary mineral on the surface of montmorillonite leads to the clogging of inter-aggregate pores. In the case of high dry density, this resulted in pore occlusion.     

Mineralogical and petrographic analysis on the flake graphite ore from Saba Boru area in Ethiopia

The mineralogy and petrography of natural graphite in Saba Boru of Ethiopia indicate that there exists flake graphite with a slightly oval structured fine size according to our study on thin and polished sections. Herein, for estimating the carbon content in graphite, the ASTM-C561, the test method for ash in a graphite sample, was used. For characterizing graphite, x-ray diffraction, x-ray fluorescence, inductively coupled plasma mass spectroscopy, and scanning electron microscopy were also used. Chemical analysis of ore samples determined that the average compositions are 63.35% SiO₂, 15.45% Al₂O₃, 2.36% Fe₂O₃, 2.07% K₂O, less than1% others, and loss-on-ignition (LOI) in the range of ~4.74%–37.42%. The total carbon content of graphitic ore ranged from 4.11% to 33.14%. Importantly, when graphite is concentrated through floatation, its average purity and recovery are 92.97% and 90.82%, respectively. Furthermore, once the graphite concentrates are treated with hydrofluoric acid, the average value attains a high grade of 96.48% C. Moreover, the average ash content is 81.93% (pre-flotation) and 3.1% (post-flotation), respectively. Finally, after beneficiation, a silica is identified as a major gangue (85.88%), usable as a raw material for other purposes such as cement. Hence, these graphite-bearing rocks seem to be worth exploring for commercialization opportunities.     

白云鄂博尾矿稀土的工艺矿物学研究

通过偏光显微镜,矿物自动定量分析系统(AMICS)、扫描电子显微镜,能谱分析仪结合化学分析等分析手段对白云鄂博尾矿的物质组成,稀土矿物嵌布特征、稀土元素赋存状态等进行研究。结果表明：尾矿中稀土的含量(REO)为6.42%,稀土矿物主要为氟碳铈矿和独居石,脉石矿物主要有白云石、方解石、石英、长石、闪石、辉石、云母、重晶石和磷灰石等;稀土矿物嵌布粒度细小,氟碳铈矿与独居石单体解离度分别为55.07%、50.47%,与脉石矿物嵌布关系极为复杂。约95%的稀土元素赋存于稀土独立矿物中,约百分之五的稀土以类质同象或细小包裹体分散在其它矿物中。基于上述稀土矿物的嵌布特征及稀土元素的赋存特点,推荐采用分级一磨矿一浮选流程进行试验,以实现稀土矿物的有效回收。     

攀钢含钛高炉渣的综合利用

通过调整渣的组成,控制热处理温度等因素可以使攀钢含钛高炉渣中的钛组分以钙钛矿为主要存在,实现了选择性析出,研究了选择性析出的凝渣的工艺矿物学性质,初步探讨了钙钛矿相选矿分离的工艺流程。     

影响深海多金属硫化物选冶的矿物学因素

某深海多金属硫化物中锌、铜、金、银的品位分别为20.44%、0.41%、6.89g/t和141g/t,有价元素含量高,综合利用价值大。通过矿物组成、重要矿物的嵌布特征、嵌布粒度及磨矿产品中解离特征的研究,对影响选冶回收的矿物学因素进行了系统的分析。研究表明:闪锌矿是含量最多的矿物,具有含铁量变化较大、铁含量普遍较低、嵌布粒度不均、与自然硫和黄铁矿密切共生的特点,通过选矿可以获得高品质的锌精矿。自然硫的粒度细、与闪锌矿和黄铁矿共生紧密,但其浮游性能好,对铜、锌的选别影响较大,可以考虑优先浮选自然硫,以减少其对后续分选的影响。金、银矿物主要为自然金、银金矿和辉银矿,嵌布粒度细,基本都在0.005mm以下,与黄铁矿、闪锌矿的共生关系密切,由于闪锌矿和黄铁矿含量高,难以直接通过浮选的方式获得高品位的金、银精矿。