Determination of contact angle on the coal surface

The paper considers the method for determining a contact angle of coal surface prepared by pressing the coal powder into cylindrical pellets of a target size. The authors analyze the relationships between the contact angle and chemical properties of coal surface.     

落煤角与接触角对煤岩与尾梁动态响应的影响分析

综采放顶煤过程中大量的煤岩垮落会对放顶煤液压支架带来巨大冲击,甚至会导致设备损坏.为研究不同落煤方式下液压支架尾梁受冲击后的受力以及响应特性,在ADAMS中建立了放顶煤液压支架的刚柔耦合模型,利用弹簧阻尼系统等效替换平衡千斤顶,采用Hertz接触理论确定了接触参数.基于该模型,对煤岩颗粒以不同落煤角度和不同接触角度冲击...     

不同煤种接触角及润湿性规律探究

为了确定粗糙度、表面活性剂以及变质程度对煤表面疏水性和润湿性的影响,选用5种不同变质程度的煤,测定了不同表面粗糙度煤样的表面接触角。并采用OWRK法理论模型计算不同变质程度、不同粗糙度煤的表面能。结果表明,粗糙度会影响煤表面的疏水性和润湿性,试验表明所选用的砂纸目数越小,煤样表面所测得接触角值越小,疏水性越差,煤表面能越大。不同表面活性剂对不同变质程度煤表面的润湿能力不同,对于褐煤和气煤,SDBS的润湿性最好,随着变质程度的增加,OP-10的润湿性较好;同一表面活性剂的不同浓度溶液,表面张力越小,润湿性越强;表面活性剂浓度在接近临界胶束浓度(CMC)时润湿效果较好。     

煤水平衡接触角的影响因素研究

应用仪器不测定了煤与纯水间的平衡接触角，分析了煤的工业分析、元素分析及显微组分定量分析指标对煤水平衡接触角的影响。研究结果证实，煤水平衡接触角首先受煤中氢、氧元素含量影响最大，其次与煤的灰分产率有很强的线性相关关系。     

Adsorption behaviour of xanthate and dithiophosphinate from their mixtures on chalcopyrite

The beneficial effects of the synergy between two or more reagents were realized long time ago. The purpose of using a mixture of collectors was to increase both the recovery and selectivity. In this work, two thiol collectors, isopropyl xanthate (SIPX) and di-isobutyl dithiophosphinate (DTPI), having different chemical and functional properties, were used. The adsorption behaviour of these collectors from their mixtures was investigated at various SIPX:DTPI ratios and sequence of addition by cyclic voltammetry and adsorption experiments at pH 9.2. The results showed that both the ratio of collectors in these mixtures, and sequence of addition were important. The amount of total collector (SIPX and DTPI) adsorbed on chalcopyrite was measured for these various reagent mixtures and for single collectors. Two maxima were found. One was found for the 30:70 DTPI:SIPX suite in which the DTPI was added first. A second was found with the 50:50 SIPX:DTPI suite when the collectors were added together. These results revealed that the maximum synergistic effect of using mixture of SIPX and DTPI was strongly influenced by the ratio of the collectors in the mixture and particularly sequence of addition.     

单角钢、双角钢轴心受压构件的计算

单角钢、双角钢等单轴对称的截面类型构件在钢结构设计中应用非常广泛，这些构件在轴心受压失稳时有弯扭失稳和弯曲失稳两种方式。GBJ17—88钢规只是隐藏地考虑了扭曲屈曲的影响；而《钢结构设计规范》GB50017—2003则明确地考虑了扭曲屈曲的因素，并给出了相应的计算方法。论文通过对规范条文的分析和实例，说明了新规范条文应用时的不同思路。在设计中要根据情况选择恰当的构件截面形式。     

Effect of contact angle,surface tension and zeta potential on oil agglomeration of celestite

The influences of contact angle, surface tension and zeta potential on oil agglomeration recovery of celestite mineral have been investigated in the present work. Therefore, celestite mineral in methanol–water suspension was agglomerated by the use of oil (kerosene) in the presence of sodium oleate as a surfactant. The zeta potential values of celestite surfaces were measured depending on pH and sodium oleate concentration. The zeta potential values of celestite surfaces became negative even more owing to the sodium oleate adsorption. However, this phenomenon did not affect the oil agglomeration recovery at all. It was found that both increasing contact angle and surface tension raised the oil agglomeration recovery of celestite mineral. Eventually, the agglomeration degree of celestite mineral in the suspension was not lower than a particular surface tension value corresponding to the critical solution surface tension for oil agglomeration (γ_c-a). The γ_c-a values were slightly greater than the critical surface tension of wetting (γ_c) values.     

方柱微结构表面熔渣接触角的数值模拟研究

利用VOF模型对在不同本征接触角及不同尺寸方柱结构表面上熔渣的接触角进行了二维数值模拟,并对熔渣在方柱结构上的接触角进行测量.测量结果显示,熔渣在不同的本征接触角及不同方柱结构尺寸的表面上均处于Cassie润湿状态.将模拟结果与含方柱结构尺寸的Cassie润湿状态的接触角方程计算结果进行比较发现:在本征接触角大于90°的涂层表面,方柱结构的存在增大了熔渣的表观接触角;模拟结果的接触角值与接触角方程计算值较为吻合,误差在10%以下.     

Influence of operating parameters on the flotation of apatite

Flotation of apatite is complicated, owing to its physicochemical similarity with other minerals in phosphate ores. Despite this, relatively few studies have been done on the effect of operating parameters, such as the mode of milling, pulp conditions and collector dosage on the kinetics of apatite flotation. In this technical note, the results of batch flotation tests and the fitting of a first-order kinetic model to assess the influence of operating variables on the flotation kinetics are discussed. Pulp pH, collector dosage and pulp temperature affected recovery significantly, but the mode of milling (wet or dry) did not. All factors influenced the concentrate grade, except for the collector dosage, while the milling mode was the only factor that did not affect the flotation kinetics significantly.     

1831在蒙脱石上的吸附及其稳定性研究

以潍坊蒙脱石为原料,研究了十八烷基三甲氯化铵(1831)在蒙脱石上的吸附反应,建立了等温吸附模型,探讨了吸附量随时间和介质pH值的变化及机理,通过脱附反应研究了有机蒙脱石的稳定性。结果表明,Lang-muir吸附等温式和Redlich-Peterson等温吸附式能较好地拟合吸附曲线,利用表面活性剂在固液界面上的吸附公式也得到了较好地拟合。pH值较高有利于季铵盐在蒙脱石上的吸附,80℃的条件下得到的有机蒙脱石稳定性好于30℃。     

高强度调浆对微细粒磷灰石浮选效果的影响研究

为了提高微细粒磷灰石的浮选指标,需要对入浮矿浆进行高强度调浆处理。本文以承德某地的斜板浓密溢流为研究对象,展开高强度调浆工艺条件试验。以实验室30L规格的高强度调浆机和工业上2m直径的高强度调浆机为研究手段,对调浆时间、调浆转速等展开条件试验。30L调浆机结果表明最佳的浮选时间为6分钟,最佳的线速度为8.35m/s,和普通改质机叶轮和直桨叶轮相比,新型叶轮的调浆效果更好,并且能耗较低。2m高强度调浆机的工业试验表明,150rpm是最佳的转速。并且和普通调浆机相比,在相同产率（粗选产率为5%~10%）下磷灰石的回收率提高了约10%,可见高强度调浆机能显著改善细粒磷灰石的浮选环境。清水条件高速摄像和浊度测试结果表明,高强度调浆机叶轮和普通搅拌槽叶轮相比,对油滴的分散效果更显著,搅拌后形成的乳浊液体系更为稳定。     

The dependency of the critical contact angle for flotation on particle size - Modelling the limits of fine particle flotation

The flotation behaviour of fine particles is studied in this work. Fine methylated quartz particles within the size range from 0.2 to 50 μm, and with varying contact angles, were floated in a mechanical flotation cell. Results indicate that particles of a given size need to possess a minimum critical contact angle, which increases in value as particle size decreases, for flotation to be initiated. As a consequence, a non-floating component exists within a given size fraction. This is interpreted as a fraction consisting of particles below the critical contact angle for flotation for that size. The critical contact angle for flotation is explained in terms of the existence of an energy barrier for bubble-particle attachment. The flotation results are interpreted by means of [Scheludko et al., 1976] and [Drelich and Miller, 1992] models for the floatability of fine particles. The experimental data compared very well with calculations using the Drelich and Miller equation, allowing extension to the prediction of the critical contact angle for flotation down to particle sizes well below the previous limits investigated, bridging the gap existing in the literature.     

新型磷灰石常温捕收剂的浮选试验研究

在磷灰石浮选过程中传统捕收剂存在矿浆需加温及用量过多等问题。通过合成一种新型磷灰石常温捕收剂DYX,并以此为捕收剂对磷灰石单矿物进行了浮选试验研究。试验结果表明,在矿浆温度为26℃,矿浆p H值为10.0,捕收剂DYX用量为400 g/t、抑制剂水玻璃用量400 g/t的条件下,磷灰石的浮选回收率达到94.58%,说明该新合成的捕收剂具有常温下捕收作用能力强、用量少的特点。动电位和红外光谱分析结果表明,该捕收剂在磷灰石表面以氢键和化学键合吸附为主。     

Influence of surfactants on crushing of marble

Conclusions All the organic additives used in this investigation are surface-active with respect to marble. Of the series of amine and hydroxyl additives investigated, the amine ones were found to be more active; in their presence, the specific surface of marble is more than doubled. Tomsk Polytechnic Institute. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 89–91, July–August, 1978.     

白钨矿与磷灰石浮选的选择性抑制及机理研究

油酸钠为捕收剂时白钨矿和磷灰石的可浮性相近,难以实现分离。通过浮选试验、理论计算和动电位测定的方法研究了硅酸钠和焦磷酸钠对白钨矿与磷灰石的选择性抑制作用。结果表明,硅酸钠对白钨矿和磷灰石的抑制作用相似,而焦磷酸钠能够以P2O47-的形式强烈抑制磷灰石,同时对白钨矿的抑制能力较弱。机理研究表明,焦磷酸钠的基团电负性介于钨酸根和磷酸根离子之间,且磷灰石表面的钙离子密度大于白钨矿,使焦磷酸钠对磷灰石的抑制作用强于白钨矿。     

阴离子对磷灰石和白云石表面性质影响的第一性原理研究

结合密度泛函理论（DFT）计算,研究磷矿反浮选脱镁过程中,三种主要阴离子（油酸根离子、SO42-和H2PO4-）在氟磷灰石和白云石吸附特性的差异。结果显示,油酸根离子、SO42-和H2PO4-均能在氟磷灰石和白云石表面发生化学吸附。氟磷灰石表面暴露的Ca原子位于磷酸根之上,表面Ca原子活性强,SO42-和H2PO4-在Ca位点的吸附能分别为-818.74~-1058.30 kJ/mol和-572.78~-709.02 kJ/mol。白云石表面暴露Ca、Mg和O原子,但O原子活性较强,不利于阴离子在白云石表面的吸附,SO42-和H2PO4-在白云石表面Ca\Mg位点的吸附能分别为-135.92 kJ/mol \ -156.30 kJ/mol和-127.03 kJ/mol \ 146.95 kJ/mol。因此,SO42-和H2PO4-更容易吸附在氟磷灰石表面形成不溶性钙盐,屏蔽了氟磷灰石表面的活性位点,导致磷灰石被抑制;白云石表面Ca、Mg原子位点密度大于氟磷灰石,存在更多的吸附位点与捕收剂结合。     

考虑煤层倾角和钻孔倾角的钻屑量理论研究

为准确预测与预防深部开采煤与瓦斯突出,建立了考虑煤层倾角与钻孔倾角的新钻屑量理论计算公式,并分析了煤层倾角和钻孔倾角对钻屑量的影响。以平煤股份有限公司八矿为研究对象,将钻屑量理论计算值与该矿己₁₅-21030风巷现场钻屑量实测值进行对比验证,得出在煤层倾角一定时,钻屑量随钻孔倾角增大呈幂指数递减关系,减小的比率呈“V”形变化趋势,原钻屑量理论值与实测值平均误差为5.5%,在考虑煤层倾角与钻孔倾角情况下的新钻屑量理论值与实测值平均误差为3.9%。