Phase formation,structure and properties of light-weight aluminosilicate proppants based on clay-diabase and clay-granite binary mixes

One of the drawbacks of fusible clays is the narrow sintering interval due to a sharp increase in the amount of iron-silicate melt at a temperature of 1000–1100 °C, which hardens in the form of a glass phase upon cooling. This leads to a relatively low mechanical strength of the calcined samples and causes the danger of melting the granular material surface from such clays during the firing process. To increase the strength of samples of fusible clays, the influence of diabase and granitoid rocks was considered. It was found that the strengthening effect of diabase and granitoid rock additives in an amount of 20–50% in a mixture with fusible clay is due to an increase of total content of the crystalline phase (mullite, cristobalite and residual quartz) from 18–20% in clays without additives to 22–28 % - in mixtures with diabase and to 28–34% - with granitoid additives) at a temperature of 1050–1100 °C. This increase is due to the activation of synthesis processes of secondary mullite and crystallization from alkali-rich feldspar melt of amorphous silica, released from the structure of clay minerals. The established influence of the igneous rocks used made it possible to develop compositions and propose process flow sheet for producing aluminosilicate proppants based on fusible clays. The use of granitoid and diabase rocks in an amount of 20–70% with fusible clays produces lightweight aluminosilicate proppants with bulk density of 1.40–1.46 g/cm³ at temperature range of 1050–1100 °C, which can endure destructive pressures up to 34.5–52 MPa.     

Facile microwave-assisted fabrication of WC-Al2O3 composite powder from WO3-Al-C mixture

A facile and cheap method for the fabrication of WC-Al₂O₃ composite powder was proposed. Thermodynamic calculations indicate that aluminothermic reduction of WO₃ in WO₃:xAl:(4–1.5x)C mixture is accompanied by a great deal of heat, so carbothermic reduction reaction (endothermic) becomes activated in the system. By substitution of aluminum with carbon, the formation of unwanted W₂C phase can be prevented because of less thermodynamic stability at lower temperatures. For the verification of the proposed reaction mechanism, various WO₃:xAl:(4–1.5x)C mixtures (1.1≤x≤2) were heat-treated in a domestic microwave oven. The results showed that the type of reaction is self-propagating high temperature synthesis (SHS) when 1.4≤x≤2. Lower amount of Al in WO₃:xAl:(4–1.5x)C mixtures results in a higher formation of WC. A W₂C-free WC-Al₂O₃ composite was obtained by continuation of microwave heating in an isolated atmosphere, after the occurrence of SHS reaction in a mixture containing 1.4 mol of Al. Results also showed that when x≤1.3, type of reaction becomes gradual, which in turn brings about the incompleteness reaction and residue of initial reagents.     

High-temperature creep of alumosilicate concretes on phosphate binder

Results of high-temperature creep tests of alumosilicate concretes on a phosphate binder that consists of a mixture of electrocorundum, technical alumina, and pyrophillite are presented. The mixing liquid is H₃PO₄ and an alumochromophosphate binder. The creep tests have been performed using an installation created by BashNIPIstrom State Enterprise, which makes it possible to test three specimens in one cycle simultaneously. The experimental data on the deformation of the concretes as a function of the pressing pressure, the treatment temperature, and the test conditions (the time, the temperature, and the load) are presented. The present work is the first attempt to study the endurance of materials on phosphate binders under the joint action of high pressures and loads.     

Thermal explosion of a hollow cylinder

The critical conditions for thermal explosions with nonsymmetric boundary conditions of the first kind are studied in terms of the Grishin-Bostandzhiyan model for thermal explosion of a hollow cylinder. The cases in which a hot boundary lies on the inner and outer surfaces of the cylinder are studied. The results of a numerical analysis are presented and approximate functions are given for determining the critical Frank-Kamenetskii parameter. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 2, pp. 65–67, Mach–April 1999.     

Use of oxygen for the cleaning, passivation, and preservation of power-generating equipment at the Kharanorskaya SAPP

Studies conducted on two power-generating units at the Kharanorskaya SAPP relative to the steam-water-oxygen passivation, preservation, and partial cleaning of all boiler-heating surfaces, including the surfaces of the reheater, and passivation of the surfaces of the high-pressure heaters on the steam and water sides by the steam-oxygen method, as well as partial passivation, preservation, and cleaning of turbine blading are presented. __________ Translated from élektricheskie Stantsii, No. 6, pp. 56–64, May, 2006.     

胶凝砂砾石层面抗剪参数试验研究

胶凝砂砾石坝由于骨料多,水泥掺量少,本体抗剪强度很低,而且胶凝砂砾石坝采用碾压施工,水平向碾压层面的存在,会导致层间结合力的降低,影响层面的抗滑稳定及抗渗安全,因此研究胶凝砂砾石碾压层面抗剪能力具有重要意义。本文根据胶凝砂砾石碾压层面的处理措施,设计了6种试验方案进行胶凝砂砾石碾压层面的抗剪断试验,采用150mm立方体试件研究了单轴压条件下的胶凝砂砾石碾压层面抗剪断特性。并在守口堡大坝坝基不同高度的碾压层面处,采用50cm立方体试件进行了富浆胶凝砂砾石原位抗剪断试验。通过室内和原位试验研究,得到了胶凝砂砾石层面抗剪断基本参数,并通过分析揭示了胶凝砂砾石层面剪裂机理,对比了室内试验与原位试验结果的差异并揭示了其原因,对比了富浆胶凝砂砾石层面原位抗剪参数与RCC的差异。上述研究,为胶凝砂砾石大坝的结构分析提供了可靠的参数,并为碾压层面的施工提供了有益的建议。     

Molecular dynamics simulation study on the structure II clathrate-hydrates of methane + cyclic organic compounds

The ternary structure II (sII) clathrates of methane + cyclic organic compounds (COCs) are studied using molecular dynamics (MD) simulations. The results show that the COC guest molecules have a stabilizing effect on the clathrate-hydrate and stability of the unit cell decreases upon replacing more COC guest molecules in the large cages by CH₄ molecules which is confirmed by the comparison of radial distribution functions and unit cell volumes of the different occupancy cases. The maximum methane storage capacity for sII in the presence of tetrahydropyran, cyclobutanone, and cyclohexane are 11.9, 10.5, and 9.6 wt% of methane gas, respectively.     

Cyclododecene cometathesis with hexene-1 on the MoCl<Subscript>5</Subscript>/SiO<Subscript>2</Subscript>–Me<Subscript>4</Subscript>Sn catalytic system

The stereochemistry of the cometathesis of cyclododecene (CDD) with hexene-1 in the presence of the MoCl₅/SiO₂–Me₄Sn heterogeneous catalytic system has been studied. It has been established that CDD is the mixture of cis- (Z) and trans- (E) stereoisomers with the ratio of 30/70, respectively. It has been shown that the reactivity of the E-stereoisomer of CDD in the reaction of cometathesis is higher when compared to the Z-stereoisomer. Thus, when the conversion of CDD is 92%, the ratio E/Z = 6 : 94, i.e., the amount of the E-stereoisomer decreases from 70 to 7%, while the amount of the Z-stereoisomer increases from 30 to 93%, respectively.     

Application nonparametric criteria in the analysis of oil fields development

Waterflood or pressure maintenance project is considered one of several methods of enhanced oil recovery, which is widely being used in oil fields. Water injection efficiency analysis is very important for operation future plan and finds out if any opportunity is available to improve project performance. The conventional methods beside nonparametric criteria have been applied in this research in order to evaluate water injection operation. Gini coefficient analysis has been used to illustrate the water injection impact in terms of oil and water production trends over the time of injection operation.