滤纸模板法制备Ag-SnO_2电接触材料

首先以纳米SnO_2粉体和Ag NO3为原料,滤纸为模板,通过浸渍、煅烧制备了Ag-SnO_2复合粉体,然后利用Ag-SnO_2粉体为原料,采用压制、烧结工艺制备了Ag-SnO_2电接触合金。进一步通过XRD和SEM等分析手段对所制备的复合粉体和合金样品进行表征,并借助TG-DSC对滤纸前躯体的分解过程进行分析,同时研究了不同纳米SnO_2含量对Ag-SnO_2电接触合金组织和性能的影响。结果表明,所制备的Ag-SnO_2复合粉体由四方相金红石型结构的SnO_2和立方相的银组成,模板去除干净,无杂质引入。由于滤纸模板的引入使得SnO_2颗粒弥散分布于银基体中。随着SnO_2含量的增加,Ag-SnO_2电接触合金的硬度有上升趋势,但高氧化物含量也导致模板的分散效果变差,使得合金的电导率和致密度逐渐降低。     

Microwave reduction of copper(II) oxide and malachite concentrate

The use of microwave radiation as an energy source in mineral processing and extractive metallurgy has demonstrated both the instantaneous generation of heat by microwaves in a number of compounds and minerals, and the achievement of high temperatures for an efficient time period enable the heating and reduction of metallic oxides and ores. In the present study, the carbothermic reduction of copper oxide (CuO) and one malachite [Cu₂CO₃(OH)₂] concentrate were investigated. To explore feasibility, the dielectric constants [real (ε′) and imaginary (ε″) permittivities] of both materials were measured at the frequencies of 2.45 GHz and 912 MHz, in the temperature range from 25 to 800 °C using the cavity perturbation method. The high ε″ values (between 1.9 and 36.3) observed in the case of CuO suggest strong microwave absorption, while the malachite concentrate values (between 0.1 and 0.4) indicate limited microwave absorption. Experiments showed the microwave heating rate of CuO was considerably higher than that of the malachite concentrate.The carbothermic reduction of CuO oxide was examined, and the effect of power supply, carbon source, carbon content and granularity of the reducing agent on the reduction rate was studied in detail. Using an 800 W power supply, and with addition of lignite as a reducing agent (with carbon content two times stoichiometric), almost complete reduction of 10 g of CuO was achieved in 4 min.The carbothermic reduction of one malachite concentrate was attempted with the same experimental procedure, but the reaction was not possible using only lignite as the reducing agent, since the poor microwave absorption of malachite concentrate-lignite mixture produced a maximum temperature of 200 °C. This difficulty was overcome by the addition of 5% by weight of graphite powder to the mixture. The rapid heating of the malachite concentrate-lignite-graphite mixture (800 °C after 2 min) resulted in sequential malachite calcination and CuO reduction reactions. After 8 min at a power supply of 800 W, the reduction degree of CuO produced by the calcination of malachite was about 90%.     

Selective flotation of cassiterite with benzohydroxamic acid

The flotation of cassiterite mineral from gangue with a collector benzohydroxamic acid (BHA), and the interactions between the BHA and cassiterite have been investigated. It is shown through microflotation that the BHA is able to flot cassiterite very well, calcite quite limitedly, and quartz not at all, so the selective separation of cassiterite–quartz mixture was readily achieved; while for the efficient separation of cassiterite–calcite mixture containing 48.94% SnO₂, sodium hexametaphosphate (SHMP) was needed as a depressant for the gangue, and under the condition of the BHA 100 mg L⁻¹, SHMP 3.5 mg L⁻¹, a cassiterite concentrate with the grade of 85.50% SnO₂ was obtained with the recovery of SnO₂ 95.5%. Batch flotation further demonstrated that for an industrial tin slime, which contained 0.42% Sn, 13.65% SiO₂, 24.14% CaO, 16.60% MgO, 4.50% Al₂O₃ and 6.58% Fe, the tin recovery of 84.5% after one separation was reached with the concentrate grade of 1.84% Sn under the condition of the BHA 178 mg L⁻¹, SHMP 27 mg L⁻¹. In terms of zeta potential and infrared spectra studies the main interactions between the collector BHA and the mineral cassiterite in a flotation system are chemisorption with the formation of Sn–BHA compounds rather than electrostatic attractions between them.     

采煤机技术发展历程(九)——环境感知技术

采煤机实现自动化或智能化运行,必须能够准确获取作业位置、周围环境、煤层状态等信息。重点介绍了采煤机运行过程中的空间障碍、瓦斯浓度、行走位置、轨迹直线度等感知技术发展。在采煤机空间避障和防撞保护方面,基于毫米波雷达、激光雷达、图像识别的机器视觉感知技术具有优势,但目前在采煤机上尚未成熟应用,亟需深入研究。在机载瓦斯监测方面,差分吸收激光雷达探测技术和可调谐二极管激光吸收光谱探测技术是具有应用前景的瓦斯探测技术,目前尚少相关研究报道。在采煤机行进轨迹定位和直线度检测方面,基于捷联惯导的多传感器定位技术成为研究和应用热点,国内技术已渐进成熟和实用化。此外,基于激光雷达的SLAM机器视觉技术值得关注,可以把空间建模、避障防撞、行走定位、轨迹跟踪、姿态监测等多项任务融为一体,为构建采煤机数字孪生运行模型奠定感知技术基础。     

Treatment of Acid Leachate from Coal Discard using Calcium Carbonate and Biological Sulphate Removal

Abstract.   An integrated approach is proposed for treating acidic coal discard leachate, consisting of CaCO₃ handling and dosing, CaCO₃-neutralization, and biological sulphate removal. It was found that: powdered CaCO₃ can be slurried to a constant density and used to neutralize the acid water, remove Fe (II), Fe (III), and Al, and partially remove the sulphate (to saturation level); biological sulphate removal can be used to lower the sulphate to less than 200 mg/L using ethanol as the carbon and energy source; CO₂ produced during calcium carbonate treatment can be used for H₂S-stripping and; H₂S gas recovered in the sulphate removal stage can be used for iron removal.     

The greenhouse gas impact of IPCC and ore-sorting technologies

In-pit crushing and conveying (IPCC) and ore sorting are two developing technologies that, in addition to providing likely economic benefits, also have the potential to reduce the greenhouse gas footprint of mining and mineral processing operations. A life cycle assessment study was carried out to provide estimates of the likely greenhouse gas reductions from the implementation of IPCC and ore sorting technologies in a hypothetical copper mining and mineral processing operation. Based on the assumed configurations and operating characteristics of the two systems, the results indicated that IPCC had 4% less (i.e. 3 kg CO₂e/t ore or 0.16 kg CO₂e/t ore.km) greenhouse gas emissions than truck haulage for the base case configuration. Using electricity generated from natural gas rather than black coal increased the greenhouse gas advantage of IPCC over truck haulage from 4% to about 22% (i.e. 14 kg CO₂e/t ore or 0.74 kg CO₂e/t ore.km). However, transport distance and annual plant feedrate affect the magnitude of these greenhouse gas reductions.A potential reduction of about 13 kg CO₂e/t ore in greenhouse gas emissions was estimated from the use of ore sorting technology based on black coal generated electricity, while with natural gas-based electricity the reduction was only 8 kg CO₂e/t ore. The mass rejection rate of the ore sorting device was the main operational variable affecting the magnitude of this reduction, although it is also affected by the specific comminution and concentration energy requirements of the ore. While the results indicate that ore sorting offers nearly four times the potential reduction in greenhouse gas emissions than IPCC did at the same annual plant feedrate for the base case configuration with black coal-based electricity, the situation was reversed with natural gas-based electricity, with IPCC offering nearly double the potential reduction in greenhouse gas emissions than ore sorting. However, it should be appreciated that due to the limited amount of publicly available data on these technologies at the present time, the results of this study should be viewed as first estimates only.     

Treatment of Mine Water for Sulphate and Metal Removal Using Barium Sulphide

Abstract.   The integrated barium sulphide process consists of: preliminary treatment with lime, sulphate precipitation as barium sulphate, H₂S-stripping, crystallization of CaCO₃, and recovery of barium sulphide. Our tests showed that during lime pre-treatment, sulphate was lowered from 2 800 mg/L to 1 250 mg/L by gypsum crystallization; metals were precipitated as hydroxides. The BaS treatment then lowered sulphate to less than 200 mg/L. Sulphide was lowered from 333 to less than 10 mg/L (as S) in the stripping stage, using CO₂ gas for stripping. The stripped H₂S-gas was contacted with Fe (III)-solution and converted quantitatively to elemental sulphur. The alkalinity of the calcium bicarbonate-rich water was reduced from 1 000 to 110 mg/L (as CaCO₃) after CO₂-stripping with air due to CaCO₃ precipitation. Fe (II), after sulphur production, was re-oxidized to Fe (III) using an electrolytic step. The running cost of the BaS process is R2.12/m³ (US$1 = SAR6.5) for the removal of 2 g/L of sulphate.     

我国页岩气资源勘探区块项目生命周期风险价值评估研究

随着我国对页岩气资源勘探开发进程的不断加快,在借鉴美国页岩气勘探区块价值评估经验的基础上,针对我国目前页岩气勘探区块项目的特点,结合我国现在的投资环境和相关财税法规,研究适合于我国页岩气勘探区块自身特点的风险价值评估的指标体系和评价模型至关重要。本文提出了基于通用的贴现现金流法建立页岩气勘探区块风险价值评估模型,并由该模型计算出的期望净现值(ENPV)作为主要评价指标,将风险期望价值(EMV)、最大负现金流(MNCF)、成本波动率以及风险贴现系数(贴现率)作为辅助性评价指标,建立了我国页岩气勘探区块风险价值评估的指标体系,实现对页岩气勘探区块在整个生命周期内主要的风险进行充分评估,客观地判断和分析页岩气勘探区块的价值,实例应用效果好。     

Determination of the gas compositions for direct coal liquefaction by gas chromatography

Via multi-dimensional gas chromatography, configured with parallel dual-channel, double detectors, valves switching and back flushing, rapid analysis of the gas compositions consisting of C₁–C₅ hydrocarbons and permanent gases, such as CO₂, H₂S, H₂, and CO, for direct coal liquefaction has been realized. With four packed chromatographic columns, which are Hayesep-Q pre-column, Hayesep-Q column, molecular sieve 5A column and one PLOT Al₂O₃ S capillary column, the gas compositions for direct coal liquefaction are analyzed qualitatively and quantitatively by the external standard method. The determination method has such advantages as excellent separation, simple operation, rapid analysis and accurate results.     

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.     

宏发煤矿低渗透性煤层CO2致裂增透技术试验研究

为了研究CO_2致裂增透技术对贵州低渗透煤层瓦斯抽采的影响,以贵州宏发煤矿1903工作面回风巷为研究对象,进行CO_2致裂增透试验研究。研究表明:煤层致裂后,其透气性系数平均为原始煤层的3.05倍,煤层的透气性显著提高;煤层瓦斯平均抽采浓度增大了4.19倍,平均抽采纯量为原始煤层的3.99倍;在钻孔瓦斯抽采率方面,单孔的瓦斯抽采效果提高了2.58~3.92倍;钻孔工作量降低了4倍,抽采达标时间缩短了55d,瓦斯涌出量降低了40%,煤层瓦斯抽采效益显著。CO_2致裂增透技术为解决贵州矿区低透煤层的瓦斯抽采技术难题提供了参考和借鉴。     

塔河油田缝洞型油藏注气提高采收率机理研究（增刊）

自2012年塔河油田开展了单井注氮气矿场试验,并取得了较好的效果。但是注气提高采收率的机理不清。通过调研,世界范围内注气提高采收率通常采用二氧化碳气体。在高温高压条件下进行了物理实验,结合理论计算,对二氧化碳及氮气在塔河油田条件下的最小混相压力,在原油中的溶解度,对原油密度、粘度的影响,以及在原油中的体积膨胀系数等进行了深入研究。由此得出了注入二氧化碳及氮气提高塔河油田缝洞型油藏采收率的机理。在塔河油田重质油条件下,二氧化碳/氮气与原油均不会发生混相。二氧化碳在原油中的溶解度大,对原油密度的改变作用更大,对原油的降粘作用更明显。因此,二氧化碳可以改善原油流动性,扩大波及体积。但是,氮气在原油中的混相压力更高,更容易形成气顶,对油水的重力分异能力强。     

我国注气驱替煤层瓦斯技术应用现状与展望

注气驱替煤层瓦斯技术的应用可以显著提高煤层瓦斯采收率,并具有环保性。基于国内外注气驱替煤层瓦斯发展状况及主要机理,从注气位置(地面和地下)、注气模式(自然涌出、负压抽采、只注不抽、边注边抽和间歇注气等)和注入气体种类(纯CO_2、纯N_2和混合气体等)等三个方面对比分析了我国注气驱替煤层瓦斯技术的应用现状。最后,结合注气驱替煤层瓦斯现阶段的发展现状,从低煤阶煤层气注气技术、多储层联合开采注气技术、深部煤层气注气技术、新型气体注气技术和多措施联合注气技术等五个方面对注气驱替煤层瓦斯技术进行了展望。     

Experimental study of enhancing coalbed methane recovery by carbon dioxide injection driving methane

In order to enhance coalbed methane recovery, taking a self-developed largecale simulation system for the platform, a modeling experiment of driving CH₄ by CO₂ gas injection was studied. The results of experiment indicates that there is a significant lag effect of adsorption and desorption on gas, the gas pressure is changed more rapidly in the process of carbon dioxide adsorption of coal than methane adsorption of coal; After the injection of carbon dioxide, compare with methane single desorption. In an early stage, speed and amount of methane single desorption are greater than the speed and amount of displacement desorption, the speed and amount of displacement desorption became greater. In the process of replacement, CH₄ concentration constantly declined, while CO₂ concentration constantly rose. In the process of CO₂ gas injection, the temperature of coal have been significantly increased, it is more beneficial to make CH₄ gas molecules become free from the adsorbed state when temperature is increased. Under the pressure step-down at the same rate, using the method of CO₂ driving CH₄, compared with the method of conventional pressure step-down, the desorption rate of CH₄ in coal can be raised about 2.13 times, at the same time, a lot of greenhouse gas CO₂ will also be buried in the ground, there is a very significant environmental benefit.     

Coal matrix deformation characteristics in the process of carbon dioxide displacing different gas saturation coal-bed methane

It is fundamental that changes in coal reservoir permeability are researched, in particular, the accurate determination of variations in the coal matrix caused by CO₂ replacing CH₄ at different gas saturation conditions. Based on the surface free energy, the extended Langmuir isothermal adsorption model, combined with CO₂ replacing CH₄ in experimental trials, and calling on the more general principles and characteristics of the field, mathematical models describing the coal matrix as it undergoes different processes such as CO₂ injection and desorption were established. Combined with laboratory data about CO₂ replacement under different methane saturation conditions, a law governing the variations in coal matrix CO₂ replacement under different methane gas saturation conditions was obtained. The results showed that: in the injection process, the coal matrix expansion rate caused by CO₂ or CH₄ was exponentially increased with the CO₂ pressure increase, the expansion caused by CO₂ was far greater than the expansion caused by CH₄ in the desorption process, the coal matrix shrinkage caused by CO₂ or CH₄ was exponentially increased with the pressure decrease, the shrinkage caused by CO₂ was larger than the shrinkage caused by CH₄ under the same pressure and different gas saturation, the total shrinkage in the desorption process in the coal matrix was greater than the total expansion in the injection process. At higher gas saturations, the total coal matrix shrinkage volume exceeded the total expansion corresponding to pressure points higher in the desorption process.     

利用NaOH溶液吸收捕集烟气中的CO2

利用NaOH溶液吸收捕集模拟烟气中的CO₂,重点考察了NaOH溶液浓度、烟气中CO₂浓度、NaOH溶液温度、烟气流量等对CO₂脱除效率的影响规律,并考察了烟气中SO₂的存在对CO₂吸收的影响。结果表明,在实验室条件下,通过鼓泡反应装置,利用NaOH溶液吸收模拟烟气中的CO₂,CO₂脱除效率随着NaOH溶液浓度、烟气流量和鼓泡气管插入深度的增加先增加后降低,随着CO₂浓度、NaOH溶液温度的增加逐渐降低。在优化工艺条件下,CO₂脱除效率可高达97%。     

粉煤灰制备高耗氯产品主反应装置能质平衡模型

探索开发新的粉煤灰有价组元高附加值提取工艺对提高大宗固废粉煤灰的资源利用效率具有现实意义。本文首先基于氯化冶金原理提出采用喷吹竖炉工艺结合精馏提纯技术,以粉煤灰与工业副产氯气为主要原料制备高耗氯产品的技术解决方案,兼顾“以废治废”。然后构建了喷吹竖炉工艺主反应装置的能质平衡模型,通过数值计算分析了经济技术指标,评估了工艺的可行性。计算结果表明,每小时处理695 kg粉煤灰可以生产具有高附加值的AlCl₃、FeCl₃及SiCl₄的理论产量分别为498.78、94.86和935.55 kg;同时消耗焦炭280.47 kg,工业副产氯气1593.74 kg,载气空气182.07 kg;提高工业副产氯气的预热温度可以减少焦炭消耗量,优化生产成本;炉气带走热量占主反应装置热量支出的74.78%,与粉煤灰中各氧化物的氯化率呈正相关;精馏提纯后的高热值炉气结合烟气炉等余热回收设备可以实现循环利用。研究内容和结果可为后续工艺仿真模拟和优化操作参数提供理论基础和数据支撑。     

Iron redox-equilibria and sulphide capacity of PGM melter-type slags

New measurements have been made on the ferric to ferrous ratio as well as the sulphide capacity for platinum group metals (PGM) melter-type slags. In South Africa, these slags are produced from the smelting of low-grade copper–nickel sulphide ores, Nell [Nell, J., 2004. Melting of platinum group metal concentrates in South Africa. The South African institute of Mining and Metallurgy 104 (7), 423–428]. The typical mass compositions are 5–10% Al₂O₃, 2–15% CaO, 5–30% FeO_x, 15–25% MgO and 40–60% SiO₂ with a molar basicity defined as (CaO + MgO)/SiO₂ of 0.6–1. The industrial furnaces operate at temperatures ranging from 1450 to 1600 °C under fairly reducing conditions (typically a pO₂ close to 10⁻⁸ atm at 1500 °C). The gas–slag equilibrium was studied by subjecting a synthetic slag to controlled atmospheres in a vertical tube-furnace using Ar–CO–CO₂ (–SO₂) gas mixtures. The ratio of ferric to ferrous was determined at 1450 °C for oxygen activities, defined as pCO₂/pCO, ranging from 0.11 to 1.75 by analysing the quenched slags using the standard titration and XRF techniques. The measured Fe³⁺/Fe²⁺ ratio increased from 0.029 to 0.110 with the increasing oxygen activity. Slight non-ideal iron redox behaviour was observed, as has been reported for low alumina and low iron-containing slags. The present results are in good agreement with the trends found in the literature for similar multi-component slag systems (mostly iron bath smelting slags). Sulphide capacity was measured at partial pressures of oxygen and sulphur of approximately 10⁻⁹ and 10⁻³ atm respectively, with total-iron contents of 8.2 and 15.6 wt%, and temperature ranging from 1450 to 1525 °C. The present sulphide capacity data ranged from 10^−4.43 to 10^−3.71. The expected increase in sulphide capacity with increasing temperature was observed, and at a given temperature, the sulphide capacity increased with an increase in iron oxide content.     

Gas diffusion coefficient in coal: calculation of tangent slope accuracy through the inflection point determination

This investigation aims to develop an accurate method to calculate the tangent slope (b) - a fundamental parameter to calculate gas diffusion coefficients under different pressures - using inflection point determinations. The authors also studied the different tangent slope behaviours depending on the experimental gas sorption used. The single Langmuir model for individual gases and the extended Langmuir model, for multicomponent gas mixtures were applied to fit experimental gas sorption isotherm data. Two coals were selected in order to minimize and/or avoid the maceral composition and vitrinite mean random reflectance effects. Samples were submitted to three different gas compositions, viz. 99.999% CH₄; 99.999% CO₂; and a gas mixture containing 74.99% CH₄ + 19.99% CO₂ + 5.02% N₂. Results showed that the first and the second derivatives calculated to define the first inflection points represent exactly the final limit of tangent slopes.     

漠河盆地冻土区天然气水合物地球化学特征及意义（增刊）

漠河盆地是我国冻土发育的主要地区,具有形成天然气水合物的良好条件,为实现天然气水合物的突破,利用地球化学方法圈定天然气水合物靶区非常必要。本文利用传统的油气地球化学勘查方法(酸解烃、顶空气、碳酸盐),在漠河盆地天然气水合物有利区开展了探索性工作。研究发现：地球化学方法在天然气水合物勘探有较好应用,并结合地质等资料圈定了地球化学异常区,划分了三级异常;在驼峰山、一字岭等地区存在明显的地球化学异常,该区烃源岩有机质成熟度高,构造发育,在此区域内也有小型煤井发现,有望形成以煤成气为烃源供给的天然气水合物。