内蒙古呼伦贝尔早中生代花岗岩的年代学和岩石地球化学研究：对岩石成因和地球动力学机制的制约

微细粒钛铁矿的回收制约着我国攀西地区钛资源的高效开发利用。四川某矿业公司的斜板溢流原矿属辉石、橄榄石混合型钛铁矿，且粒度极细，-19 μm产率为79.22％，其中TiO2分布率为87.54％。研究结果表明，预先采用强磁选可有效消除部分超微细粒钛辉石、橄榄石等易浮杂质对浮选分离的不利影响，磁选精矿通过一次粗选五次精选一次精扫选流程，可获得钛精矿产率为21.85％，TiO2品位为47.44％，回收率为62.89％的良好指标，为矿山高效利用钛资源提供了合理的技术方案。     

Crystallization behavior and mechanical properties of high strength mica-containing glass-ceramics from granite wastes

The high-strength mica-containing glass-ceramics were prepared from granite wastes by bulk crystallization. The influences of SiO₂/Al₂O₃ molar ratio (S/A = 7.72, 9.62, 12.58, 17.82 and 29.67) on the crystallization behavior, microstructure, mechanical properties and machinability of glass-ceramics were investigated. The results demonstrated that the polymerization degree of the glass network decreased with the S/A ratio increasing, which further caused the decrease in glass transition temperature and crystallization temperatures. The increase in the S/A ratio promoted the precipitation of diopside, hectorite, kalsilite and tainiolite in glass-ceramics when the samples were heated at 750 °C, while inhibiting the precipitation of forsterite. For the glass-ceramics crystallized at 800 and 900 °C, the main crystalline phases transformed from diopside, forsterite, and nepheline to diopside, kalsilite, and tainiolite, with the S/A ratio increasing. As the SiO₂ gradually replaced Al₂O₃, the morphology of crystals changed from lamellar to granular, while the mean size of crystals reduced. The Vickers-Hardness values of glass-ceramics crystallized at 800 and 900 °C ascended with S/A ratio rising, and the values were above 6.30 GPa. The bending strength of most glass-ceramics is stable between 90 and 140 MPa, among which the maximum bending strength is 133.28 ± 14.81 MPa. The fracture toughness of the glass-ceramic crystallized at 800 and 900 °C declined, while that at 700 °C increased with a larger S/A ratio. Glass-ceramics after heat-treated at 900 °C with S/A ratio of 9.62 had the largest fracture toughness of 3.28 ± 0.15 MPa m^1/2. In preliminary tests of machinability, glass-ceramic after heat-treated at 900 °C with S/A ratio of 9.62 showed better results.     

分级循环加卸载作用下花岗岩变形破坏研究

以地下深部花岗岩为试验材料,利用GAW-2000微机控制电液伺服岩石单轴试验机进行分级循环加卸载试验,研究在同一递增荷载幅度条件下,试件的抗压强度、变形、破坏特征、残余应变以及弹性模量的变化趋势。结果表明：在单轴分级循环加卸载试验作用下,岩样的峰值强度随着每级循环次数的增加呈现递减趋势,且单调荷载应力-应变曲线包络住循环荷载应力-应变曲线；岩样破坏特征主要以剪切破坏为主,随着循环次数增加,破坏裂纹更加分散；岩样在加载过程中,岩体内部的结构在不断地调整,导致结构面变得密集与裂隙间更加闭合,卸载时回弹变形有滞后现象,加载起点与卸载终点不重合；轴向弹性、残余应变与环向弹性、残余应变随循环次数变化的规律具有相似性,岩样弹性模量曲线的趋势以“波浪形”的规律交替变化。     

利用废塑制餐盒复合花岗石等饰面保护膜

花岗石坚硬致密、强度高、磨光面色彩亮丽，所以大量用作饰面材料。但花岗石中也经常含有少量铁的硫化物和氧化物，这些含铁矿物在水、水蒸气、氧的作用下会演变为Ｆｅ（ＯＨ）３，使花岗石饰面染上污斑。利用白色垃圾———一次性塑制餐具研制的防腐剂处理花岗石和易受腐蚀的各种材料的饰面后，均可形成一层保护膜。此种保护膜无色透明、无毒无味，既防腐蚀又提高了饰面光洁度。     

Triaxial unloading test of rocks and its implication for rock burst

 The behaviour of rock deformation and its failure characteristics under loading and unloading conditions are substantially different. In this paper, triaxial unloading tests have been designed to simulate the unloading process during tunnel excavation in three kinds of rock (granite, migmatitic granite and limestone). The results show that elastic moduli obtained under unloading conditions are generally less than under loading conditions. The strength of the rock samples also decreases with an increasing rate of unloading. This study reveals that rock bursts during tunnelling in a high in-situ stress area could be controlled or reduced by lowering the excavation speed or applying precautionary measures to control the displacement of surrounding rocks. Received: 25 February 1999 · Accepted: 20 June 2000     

The relationship between physical and chemical weathering indices of granites around Seoul,Korea

In order to assess the relationship between chemical weathering indices and physical properties of granite, physical and chemical analyses were performed on both natural and artificially weathered granite samples from the Seoul area, where the pH of the rainfall occasionally drops to below 5. The results suggest that slake durability, uniaxial compressive strength, Ruxton ratio, Parker index, modified weathering potential index, chemical alteration index and loss on ignition effectively revealed changes of the degree of chemical weathering. However, the study showed no such good correlation between chemical and physical properties except dry density against loss on ignition and modified weathering potential index against uniaxial compressive strength. It is recommended that both physical and chemical indices should be used for the classification of weathering grade for the granites in the Seoul area.

---

     

Modeling of geochemical processes related to uranium mobilization in the groundwater of a uranium mine

This paper describes the processes leading to uranium distribution in the groundwater of five boreholes near a restored uranium mine (dug in granite), and the environmental impact of restoration work in the discharge area. The groundwater uranium content varied from <1 microg/L in reduced water far from the area of influence of the uranium ore-containing dyke, to 104 microg/L in a borehole hydraulically connected to the mine. These values, however, fail to reflect a chemical equilibrium between the water and the pure mineral phases. A model for the mobilization of uranium in this groundwater is therefore proposed. This involves the percolation of oxidized waters through the fractured granite, leading to the oxidation of pyrite and arsenopyrite and the precipitation of iron oxyhydroxides. This in turn leads to the dissolution of the primary pitchblende and, subsequently, the release of U(VI) species to the groundwater. These U(VI) species are retained by iron hydroxides. Secondary uranium species are eventually formed as reducing conditions are re-established due to water-rock interactions.     

福建地区花岗岩风化体渗透系数研究

以福建华东船厂修造船项目帷幕灌浆检测试验为工程依托,对比分析钻孔注水原位试验、室内土工试验、以及经验公式取得的渗透系数,通过研究粗细粒土的含量对渗透系数的影响,提出适用于初期判断渗透系数的快速经验公式,能较好地应用于福建地区花岗岩风化体,并得到相关工程的验证。     

Cobalt powdersintering industry (stone cutting diamond wheels): a study of environmental-biological monitoring, workplace improvement and health surveillance

This communication deals with an aspect of occupational hygiene in a factory producing granite cutting diamond wheels by sintering, in moulds, of fine cobalt powder. The factory has been studied between 1988 and 1991; the Department of Preventive and Occupational Medicine of the Local Sanitary Unit of Reggio Emilia has followed the evolution of the local exhaust ventilation equipment supplied by the employer in that period. At the same time, the following measurements and observations were carried out: (a) cobalt exposure by personal sampling, (b) airborne cobalt measurements by area sampling, (c) biological monitoring of cobalt in urine, (d) health surveillance.     

A methodology to determine the elastic properties of anisotropic rocks from a single uniaxial compression test

This paper introduces a new methodology to measure the elastic constants of transversely isotropic rocks from a single uniaxial compression test. We first give the mathematical proof that a uniaxial compression test provides only four independent strain equations. As a result, the exact determination of all five independent elastic constants from only one test is not possible. An approximate determination of the Young's moduli and the Poisson's ratios is however practical and efficient when adding the Saint–Venant relation as the fifth equation. Explicit formulae are then developed to calculate both secant and tangent definitions of the five elastic constants from a minimum of four strain measurements. The results of this new methodology applied on three granitic samples demonstrate a significant stress-induced nonlinear behavior, where the tangent moduli increase by a factor of three to four when the rock is loaded up to 20 MPa. The static elastic constants obtained from the uniaxial compression test are also found to be significantly smaller than the dynamic ones obtained from the ultrasonic measurements.