Modification of pore size in activated carbon by benzene deposition and its effects on CH<Subscript>4</Subscript>/N<Subscript>2</Subscript> separation

Anthracite coal was used as raw material to prepare activated carbons as the carbon support in the carbonization-activation process. Modification of the pore size of the activated carbon by chemical vapor deposition of carbon from benzene was examined. These samples were characterized by adsorption of N₂ at 77 K and CH₄ and N₂ at 303 K. The microporosity of these samples was evaluated by the Dubinin-Astakhov Equation. The pore size distribution was obtained by the DFT method applied to the N₂ adsorption data at 77 K. The separation selectivity was obtained by the Langmuir Equation. The surface morphology was characterized by an environmental scanning electron microscope. It was observed that all samples of carbon molecular sieves studied were microporous carbonaceous materials. CMS-2 prepared in the present study has a better N₂/CH₄ separation performance; it can satisfy the requirements of the pressure swing adsorption for concentrating CH₄ from the N₂/CH₄ mixture gas.     

Mechanical activation of MoS2 + Na2O2 mixtures

A study of the mechanochemical activation of molybdenum ore concentrate (MoS₂) with sodium peroxide (Na₂O₂) shows that sodium molybdate dihydrate (Na₂MoO₄ · 2H₂O) is the final crystalline product. The mechanochemical formation of sodium molybdate dihydrate is evidenced by XRD, ²³Na MAS NMR and the increasing solubility of the molybdenum in water as the oxidative reaction proceeds.     

Electrochemical treatment of COD in biologically pretreated coking wastewater using Ti/RuO<Subscript>2</Subscript>-IrO<Subscript>2</Subscript> electrodes combined with modified coke

The electrochemical treatment of COD contained in biologically pretreated coking wastewater treated by a three-dimensional electrode system with modified coke as the particle electrode was investigated. And the electrochemical perfomance of the coke modified with various active components was studied. The results show that the coke modified with Fe(NO₃)₂ has the lowest energy consumption and higher COD removal rate under the same condition, and the modified coke has better surface characteristics for the purpose of this study. In addition, the kinetic constant was also calculated. The study shows that the three-dimensional electrode system with Fe (NO₃)₂-modified coke can give a satisfactory solution in biologically pretreated coking wastewater.     

堆焊工艺参数与碳化钨含量对镍基碳化钨涂层性能的影响研究

以Ni35复合WC粉末为原料,采用等离子堆焊工艺在Q235A低碳钢表面制备了镍基复合碳化钨涂层,研究了焊接电流、WC含量对复合涂层性能的影响。结果表明,降低堆焊电流,减少热量输入,可以有效防止WC沉积。在研究范围内,WC含量低的样品WC沉积明显,而WC含量高的样品中WC分布较均匀。Ni35复合WC涂层相组成主要为γ-Ni(Cr,Fe)相、γ-(Ni,Fe)基体相,第二相WC,弥散相Cr₃C₂、Cr₇C₃、FeNi₃和W₂C。在焊接电流一定时,随着WC含量增加,堆焊涂层硬度增大;涂层中WC含量相同时,随着堆焊电流降低,涂层硬度上升。在大焊接电流(210 A)下,随着镍基涂层中WC含量增加,样品磨损量逐渐增大;在小焊接电流(195 A)下,随着WC含量增加,样品磨损量降低;当涂层中WC含量相同时,随着堆焊电流降低,样品磨损量降低。     

Er对7075铝合金微弧氧化层特性的影响

对含Er量为0%、0.2%、0.4%的7075铝合金在相同工艺下进行微弧氧化,利用X射线衍射(XRD)、扫描电子显微镜(SEM)分别研究了微弧氧化膜层的相组成和表面形貌,同时也研究了氧化层的显微硬度、厚度及耐蚀性。结果表明,不同Er含量的7075铝合金微弧氧化层都由γ-Al_2O_3相构成,且随含Er量增加,γ-Al_2O_3相峰值增加,Er在微弧氧化过程中形成了Al_(17)Er_2相进入膜层;随含Er量的增加,氧化膜表面平整度先增加后下降,当Er含量为0.2%时,表面堆积物细小均匀、孔隙直径小,粗糙度最低;含Er量由0%增加到0.4%,显微硬度及厚度也随之增加,耐蚀性明显增加,自腐蚀电流密度由4.280×10~(-6) A/cm~2降至2.405×10~(-9) A/cm~2。     

Development and Validation of a Spectrophotometric Method to Measure Sulfate Concentrations in Mine Water without Interference

Sulfate concentrations are determined in mine water by gravimetric, titrimetric, colorimetric, turbidometric, ion chromatographic, inductively coupled plasma absorption spectrophotometric, and other methods. Accurate sulfate measurement of mine water can be difficult due to interfering groups, cations, and anions, mainly arsenate (AsO₄ ³⁻) and phosphate (PO₄ ³⁻). In this paper, a simple and effective spectrophotometric method is described for the determination of sulfate in mine water. When the SO₄ ²⁻ reacts with barium chloranilate at pH 4.5 in aqueous ethyl alcohol solution, it releases acid-chloranilate, which shows maximum absorption at 350 nm and obeys Beer’s law over the concentration range of 10–1,000 mg/L. Results show that the proposed method was significantly more accurate than a conventional method. Absorbance was found to increase linearly with increasing concentration of sulfate, which is corroborated by the calculated correlation coefficient value of 0.999 (n = 7). The slope and intercept of the equation of the regression line were 0.00091 and 0.00778, respectively. The limit of detection and limit of quantification were found to be 0.03861 and 0.06774 mg/L, respectively. The validity of the described procedure was assessed. Statistical analysis of the result indicated high accuracy and good precision. The proposed method was successfully applied in mine water without interference from common groups like AsO₄ ³⁻ and PO₄ ³⁻. The relative standard deviations of the proposed method ranged from 0.03 to 0.26%, with recoveries of 99.79–101.57%.     

Alkalinity generation and metals retention in a successive alkalinity producing system

Alkalinity generation and metals retention were evaluated during the initial year of operation of a treatment wetland, consisting of four 185 m² inseries cells comprised of alternating vertical-flow anaerobic substrate wetlands (VFs) and surface-flow aerobic settling ponds (SFs). The substrate in the VFs consists of spent mushroom substrate (SMS) and limestone gravel, supplemented with hydrated fly ash in a 20∶10∶1 ratio by volume. Approximately 15±4 L/min of acid mine drainage (AMD) from an abandoned underground coal mine in southeastern Oklahoma, USA, was directed to the system in October 1998 (mean influent water quality: 660 mg L⁻¹ net acidity as CaCO₃ eq., pH 3.4, 215 mg L⁻¹ total Fe, 36 mg L⁻¹ Al, 14 mg L⁻¹ Mn, and 1000 mg L⁻¹ SO₄ ⁻²). Flow through the first VF resulted in substantial increases in alkalinity, decreased metal concentrations and circumneutral pH. 258±84 mg L⁻¹ of alkalinity was produced in the first VF by a combination of processes. Final discharge waters were net alkaline on all sampling dates (mean net alkalinity=136 mg L⁻¹). Total Fe and Al concentrations decreased significantly from 216±45 to 44±28 mg L⁻¹ and 36±6.9 to 1.29±4.4 mg L⁻¹, respectively. Manganese concentrations did not change significantly in the first two cells, but decreased significantly in the second two cells. Mean acidity removal rates in the first VF (51 g m⁻² day⁻¹) were similar to those previously reported.     

Delineating the Origin of Groundwater in the Golgohar Mine Area of Iran Using Stable Isotopes of <Superscript>2</Superscript>H and <Superscript>18</Superscript>O and Hydrochemistry

The Golgohar iron ore mine in southern Iran is a large open pit that uses dewatering (≈4000–5000 m³/day) to prevent flooding. A vast cone of depression has formed, and water from a large area flows into the pit. A study of the different sources of this water was necessary to plan a proper dewatering project. Moreover, the discharged water is saline and contains high levels of contaminants. Based on hydrochemical and isotope (¹⁸O and ²H) analysis, it was concluded that the area’s deep saline groundwater is coming from the Sirjan (Kheirabad) salt playa (north of the mine) by saltwater intrusion while the chemistry of more distant groundwater was due to dissolved minerals.     

石墨对碳毡/水泥复合材料摩擦性能的影响

以水泥为黏结剂,碳(纤维)毡为增强材料,石墨为摩擦性能调节剂,用浸渍法制备了碳毡/水泥复合材料。在AG-10k N万能试验机上测试了复合材料的抗弯和抗压性能;按照GB 5763-2008,使用MMUD-10B型摩擦试验机在100 N载荷下测试复合材料在不同石墨掺量下的摩擦因数和磨损量,研究了三维针刺碳毡/水泥复合材料的摩擦性能,并结合其磨损面和摩擦碎屑形貌研究了摩擦磨损机理。结果表明:随着石墨掺量的增加,摩擦因数不断减小,磨损率先减小后增大,抗弯强度和抗压强度均出现逐渐降低的趋势;当石墨掺量为12%时,摩擦因数为0.37,并有最低磨损率为4.4×10~(-7) cm~3/(N·m)。     

Hydrogeochemistry,Elemental Flux,and Quality Assessment of Mine Water in the Pootkee-Balihari Mining Area,Jharia Coalfield,India

Ninety nine mine water discharge samples were collected and analyzed for pH, electrical conductivity (EC), major cations, anions, and trace metals in the Pootkee-Balihari coal mining area of the Jharia coalfield. The mines of the area annually discharge 34.80 × 10⁶ m³ of mine water and 39,099 t of solute loads. The pH of the analyzed mine waters ranged from 6.97 to 8.62. EC values ranged from 711 μS cm⁻¹ to 1862 μS cm⁻¹, and reflect variations in lithology, geochemical processes, and hydrological regimes in the mines. The cation and anion chemistry indicate the general ionic abundance as: Mg²⁺ > Ca²⁺ > Na⁺ > K⁺ and HCO₃ ⁻ > SO₄ ²⁻ > Cl⁻ > NO₃ ⁻ > F⁻, respectively. Elevated SO₄ ²⁻ concentrations in the Gopalichuck, Kendwadih, and Kachhi-Balihari mine waters are attributed to pyrite weathering. The water quality assessment indicated that TDS, hardness, Mg²⁺, and SO₄ ²⁻ are the major parameters of concern in the study area. Except for Fe, all of the measured metals in the mine water were well within the levels recommended for drinking water. With only a few exceptions, the mine water is of good to permissible quality and suitable for irrigation.     

Study on structural and compositional transitions of coal ash by using NMR

Structural and compositional transitions of Datong coal ash and its CaCO₃ additional effects were carefully examined at a temperature range of 300 to 1 600 °C by using XRD and solid state NMR. The quantitative estimation of amorphous structures of ashes can be successfully obtained through the analyses of solid state NMR spectra. Viscosity of molten ash and its changes with CaCO₃ addition were also evaluated up to 1 700 °C by using a rotary type viscometer. Glasses with poor crystalline and amorphous phase were continuously formed through the eutectic reaction of silica above fusing temperature (FT>1 500 °C) that caused broadening and shift of ²⁹Si and ²⁷Al peaks in NMR results. With the additional amount of CaCO₃ increasing, the peaks shifted to downfield obviously; the fraction of Si(OAl)₀(OSi)₄ decreased, while that of Si(OAl)₁(OSi)₁ at −84.3×10⁻⁶ increased apparently. These transitions indicated the destruction of large alumina-silicate framework into small segments by the addition of Ca ion.     

等离子喷涂Al_2O_3涂层/GCr15干摩擦磨损性能研究

氧化铝陶瓷涂层因具有良好的耐磨、耐蚀性能而得到广泛的应用.本文利用销-盘式摩擦磨损试验机研究了大气等离子喷涂Al2O3涂层与GCr15摩擦副的室温干滑动摩擦磨损特性,用扫描电镜和能谱仪对磨损区域进行了分析.结果表明:在室温干摩擦条件下,Al2O3陶瓷涂层的磨损量随载荷的增加而增加,当载荷大于50 N时,涂层的磨损量随载荷的增加而降低,随线速度的提高而增加.在摩擦过程中,陶瓷涂层表面产生的表面膜,使涂层的磨损量减小.Al2O3涂层的磨损机理是脆性微剥落和粘着磨损共同作用.     

罐道超音速喷涂316L不锈钢涂层的腐蚀磨损行为

研究了超音速喷涂316L不锈钢涂层在pH=2.97,pH=6.97,pH=9.98三种煤矿地下水和5%NaCl盐水环境下的腐蚀磨损行为.利用ZAHNER IM6e电化学系统实验涂层的腐蚀电位和阻抗特征、MM-2000型实验机研究涂层的摩擦因数、磨损量与载荷和时间的变化关系.利用kykyS-3000N型显微镜对腐蚀磨损后的形貌进行观察,借助D/Max-3B 型X射线衍射仪对316L喷涂前后物相分析.实验结果表明:超音速喷涂316L不锈钢涂层的腐蚀电位较碳钢基体上升300 mV;不锈钢涂层在5%NaCl和pH＝2.97矿井水的强腐蚀性环境下的界面腐蚀主要为浓差腐蚀,在pH=6.97和pH=9.98矿井水的弱腐蚀环境下的界面腐蚀主要为电荷传质腐蚀;XRD结果显示,超音速喷涂不锈钢涂层和不锈钢喷涂材料的物相主要为γ-（Fe, Ni）, γ-（Fe, Cr）, 合金元素烧损较少,超音速喷涂316L不锈钢涂层的摩擦因数随加载载荷增加而减小,磨损失效方式为轻微黏着磨损.     

减摩组元对树脂基闸片摩擦磨损性能的影响

研究了在树脂基摩擦材料中添加固体润滑剂石墨、二硫化钼、焦炭粉,以适当调整其摩擦系数,并改善摩擦磨损性能.结果表明:树脂基摩擦材料中添加石墨可有效降低摩擦系数,大幅度提高复合材料及其摩擦副的耐磨性.树脂基摩擦材料中的二硫化钼在摩擦过程中,发生氧化转变为MoO3,失去了层状结构,因而不能使摩擦系数降低.焦炭粉的加入,也可降低树脂基摩擦材料的摩擦系数.     

The concentration of fluorine in coals and gangue of China

A detailed comparison was done between the data about the F in coals published at home and abroad, and associated with the special situation in China. An introduction also was made to illuminate the forming, occurrence and accumulation of the F in coals and its potential hazard to human and environment. Analytical data of coal samples were referred to study the great difference of the F content between coals and gangue. The results show that the average value of the F in the coal samples collected in different coalfields of China is 304×10⁻⁶, while that of gangue samples is surprisingly 1 319×10⁻⁶, especially the F content of coal ash from Bangmai in Yunnan Province reaches 4 800×10⁻⁶. It has been proved in many provinces of China that burning the coal and clay mixture can produce F contamination. Supported by “973 Program” (2006CB202202); The National Natural Science Foundation of China(40572090, 40272124)     

Application of carbon dioxide (CO<Subscript>2</Subscript>) for controlling subsurface fire area: Indian context

In bord and pillar method of mining, the panels are sealed off after depillaring. Depending upon the site specific condition, 40 to 45 % coal are left in depillared panel as stook, loose coal left in goaf, hard coal on floor and roof of the panel. The left out coals in goaf area start oxidation, and this leads to spontaneous heating in side sealed off area. For assessment of fire in underground coal mines, thermo-compositional monitoring plays an important role. This paper presents scientific relevance and selective criteria for use of inert gas for control of subsurface fire. Finally the paper discusses spontaneous heating problem in sealed off area and application of inertisation technology by using CO₂ to prevent and control sealed off fire at Haripur Colliery, Kenda Area, ECL, India.     

CBM geology conditions study of Gemudi syncline,Western Guizhou Province

Through the analysis of the surrounding rock, coal seam burial depth, coal quality and hydrologic geological condition, the methane-bearing property characteristics of the coal reservoir in the Gemudi syncline were elucidated. Most of the wall rock of the coal reservoir is mudstone and silt, which is a favourable enclosing terrane. Burial depth of the main excavating coal seam is moderate. The groundwater activity is thin, and there are absolute groundwater systems between each coal seam, which make poor interconnections to accelerate CBM enrichment. In our research, the area coal reservoir metamorphosis is high, CBM content is high, hole-cranny system development degree is high, and permeability of the great mass of the main coal seam exceeds 0.1×10⁻³ μm². The result demonstrates that the southeast of the Gemudi syncline has the best conditions for prospecting and exploiting CBM.     

Stability of Coatings on Sulfide Minerals in Acidic and Low-Temperature Environments

The effectiveness of silicate- and phosphate-based surface coating agents (Na₂SiO₃, CaSiO₃, and KH₂PO₄) in inhibiting the oxidation of sulfide minerals in acidic and low temperature conditions was studied. Rock samples were coated using two oxidation methods: H₂O₂ was mixed with the coating agents in one, whereas in the second, H₂O₂ was applied to the rock surface prior to the coating agent. The second approach was ineffective, but with Method 1, the pH (5) was above the pH (3.6) of the uncoated control sample. Oxidation, calculated after 14 weeks, had been suppressed by up to 96 and 65%, as indicated by the release of Fe²⁺ and SO₄ ^2?, respectively. All three coating agents (at concentrations of 0.1 and 0.3 M) suppressed the release of Fe²⁺ (<3 mg L^??1). Na₂SiO₃ inhibited Fe²⁺ and SO₄ ^2? release by 94 and 65%, respectively. Surface protection (or oxidation inhibition) efficiencies of KH₂PO₄ (in terms of Fe²⁺ release) were 67, 94, and 96% with 0.05, 0.1, and 0.3 M, respectively. The Na₂SiO₃ and CaSiO₃ coatings, irrespective of their concentrations, reduced iron oxidation by 94 and 84%, respectively. Fourier transform infrared spectroscopy analysis of the Na₂SiO₃ treated samples showed the presence of iron silicate coatings. Based on this work, coating of rock samples with silicate or phosphate can reduce the oxidation rate of sulfide minerals in acidic and low temperature conditions.     

新型干式永磁筒式磁选机风力因素分析

为了探究风力因素对分选腔流场特性、磁选机分选性能的影响,将借助计算流体力学软件ANSYS fluent对新型干式永磁筒式磁选机分选腔进行流场特性研究,并通过整机试验研究风力因素对分选性能的影响.研究结果表明,随着风速的增加,精矿铁品位由17.78％提升到19.63％,尾矿磁性铁品位由1.09％降低到0.77％,精矿产能...     

Reaction mechanism between ＂memory effect＂ and induction time of gas hydrate formation

Using visual experimental apparatus, one system (T40, 1×10⁻³ mol/L, non-added with coal) and another system (T40, 2×10⁻³ mol/L, added with coal) were experimented with for three times and two times, respectively. Five groups of P-T experimental parameters were obtained using the data logger system and analyzed combined with the video information of the experiments. Major conclustions show that the induction time is shortened by 10∼20 times in the experimental system containing residual pentahedral ring structures; “memory effect” can accelerate the dynamic progress and improve the thermodynamic conditions of gas hydrate formation.