Ash Detection of Coal Slime Flotation Tailings Based on Chromatographic Filter Paper Sampling and Multi-Scale Residual Network

The detection of ash content in coal slime flotation tailings using deep learning can be hindered by various factors such as foam,impurities,and changing lighting conditions that disrupt the collection of tailings images.To address this challenge,we present a method for ash content detection in coal slime flotation tailings.This method utilizes chromatographic filter paper sampling and a multi-scale residual network,which we refer to as MRCN.Initially,tailings are sampled using chromatographic filter paper to obtain static tailings images,effectively isolating interference factors at the flotation site.Subsequently,the MRCN,consisting of a multi-scale residual network,is employed to extract image features and compute ash content.Within the MRCN structure,tailings images undergo convolution operations through two parallel branches that utilize convolution kernels of different sizes,enabling the extraction of image features at various scales and capturing a more comprehensive representation of the ash content information.Furthermore,a channel attention mechanism is integrated to enhance the performance of the model.The combination of the multi-scale residual structure and the channel attention mechanism within MRCN results in robust capabilities for image feature extraction and ash content detection.Comparative experiments demonstrate that this proposed approach,based on chromatographic filter paper sampling and the multi-scale residual network,exhibits significantly superior performance in the detection of ash content in coal slime flotation tailings.

Rheological behaviors of coal slime produced by filter-pressing

It is an effective way to use coal slime as fuel for circulating fluidized bed boilers, which will not only solve its pollution to the environment, but also turn waste to treasure. In order to provide basic technical information for transportation of coal slime from the coal preparation plant to the boiler, this paper experimentally studied the rheological behaviors of coal slime produced by filter-pressing. By using a rotational viscometer, the influences of water content, temperature, and shear time on the rheological behaviors of coal slime were investigated. Experimental results show that the coal slime will behave like Bingham plastics with low water content and like Bingham pseudo-plastics with 37.5% water content,while like pseudo-plastics with 40% water content. This indicates that the water content of coal slime must be controlled in consideration of both transportation resistance and combustion efficiency. Study results also show that, the apparent viscosity of coal slime at 5℃ is about 1.5–1.7 times of that at 40℃ for water contents 32%–37.5%, while the influence of temperature can be neglected when the water content is 40%. With increasing of water content, the influences of shear time on the apparent viscosity of coal slime becomes less. When the water content is more than 30%, the effect of shear time is negligible. It indicates that water content has the most important influence on the rheological behaviors of coal slime. There must be an optimal water content in considering conveying resistance and combustion efficiency. The environmental temperature must also be considered in coal slime transportation.

Extended DLVO theory applied to coal slime-water suspensions

Coal slimes are mainly composed of coal and clay particles.The interaction energies among these particles were calculated using extended DLVO(DERJAGUIN-LANDAU-VERWEY-OVERBEEK)theory and the aggregation mechanisms were analyzed based on the settling experiments for coal-kaolinite and coal-montmorillonite suspensions,respectively,under different conditions of water hardness.The results indicate that for coal-kaolinite suspensions,as the water hardness reaches 10.0mol/L,the coal particles aggregate with each other easily,and then,the coal particles may aggregate with kaolinite particles.However,no aggregation occurs between kaolinite particles.A clay platelet network is formed in coal-montmorillonite suspensions by montmorillonite particles and coal particles are captured into the network.Coal and montmorillonite particles settle completely.

Insights in active pulsing air separation technology for coarse coal slime by DEM-CFD approach

To research a novel technology for dry coarse coal slime beneficiation and extend its application, active pulsing air separation technology was investigated by DEM-CFD coupling simulation approach. The results show that the ash content of feed is reduced by 10% 15% and the organic efficiency is up to 91.78% by using the active pulsing air separation technology. The gas solid flow in the active pulsing air classifier was simulated. Meanwhile, the characteristics of particle motion and the separation process of different particles were analyzed, and the mechanical structure of the classifier was also modified to achieve high separation efficiency. Therefore, a novel high-efficiency dry beneficiation technique was advanced for coarse coal slime.

Mechanical Property and Microstructure of Alkali-activated Yellow River Sediment-Coal Slime Ash Composites

This work focuses on the production of a new composite material using Yellow River sediment and coal slime ash via alkali-activating method. XRD, FTIR and SEM/EDS were used to characterize the alkali-activated products and microstructure of the composite material. Compressive strength was tested to characterize the mechanical property of the composite material. It is found that the compressive strength of the Yellow River sediment-coal slime ash composites increases as the added Ca（OH）_2 content grows. The compressive strength increases fast in the early stage but slowly after 28 days. The strength of the composites can be significantly improved via the addition of small amount of Na OH and gypsum. The products（C-S-H, ettringite and CaCO_3）, especially C-S-H, make much contribution to the enhancement of strength. The highest strength of the composites can reach 14.4 MPa after 90 days curing with 5% Ca（OH）_2, 0.2% NaOH and 7.5% gypsum. The improved properties of the composites show great potential of utilizing Yellow River sediment for inexpensive construction materials.

Effect of Moisture on Combustion Characteristics of High⁃Moisture⁃Content Coal Slime

The effects of moisture content on the combustion characteristics and pore structure change of coal slime are studied in this paper.The effect of moisture content on the bed temperature change,combustion efficiency,and NO_(x)and SO_(2)emission were obtained in a bench⁃scale fluidized bed reactor,revealing that the lowest bed temperature decreases with the increase in moisture content,but the effect on the highest bed temperature is not the same.Moreover,with the increase in moisture content,the observed degree of blackening of the flue gas increased,and more CO was produced,which in turn leads to a lower combustion efficiency of the coal slime.However,the presence of moisture plays a positive role in the reduction of NO_(x)and SO_(2).With the increase in moisture content,the amount of NO_(x)and SO_(2)produced tends to decrease.The effect of water on the combustion process of slime is mostly the impact of the severe vaporization process in the early stage to form a large water vapor channel,which is beneficial to the evaporation and loss of water,conducive to the reaction of water and coal combustion products,such as the formation of CO,reduction of NO_(x),SO_(2),etc.The large holes formed by the impact of water vapor decreased with the decrease of moisture content,and the nanoscale pores are mostly caused by the combustion process of volatilization and coke formation after the end of vaporization,and increase with the decrease of moisture content.

The influence of discharge style on the separation of coarse coal slime by a hindered fluidized bed

Two kinds of liquid distributor, a central discharge or a peripheral discharge, were designed into a hindered fluid- ized bed separator. The beneficiation performance of the fluidized bed was investigated using 0.25-1.00 mm coarse coal slime and the two different distributors. The experimental results show that the heterogeneity of axial particle velocity in the radial direction of the bed can be reduced by a distributor that has a central discharge. The beneficiation performance for this dis- tributor is improved relative to the distributor with the peripheral discharge. This indicates that it is necessary to eliminate or suppress the core-annulus structure within a hindered fluidized bed. Increasing superficial water velocity causes the clean coal ash content, the railings ash content, and the combustible recovery to increase. Additionally, increasing the bed height decreases all of these three indexes. The optimum superficial water velocity and bed height for a 0.25-1.00 mm coal feed were deter- mined to be 3 mm/s and 800 mm, respectively. This work provides a foundation for the scale-up of the bed.

煤泥基充填材料流动性与强度特性试验研究

为研究煤泥基充填材料的流动与强度特性,运用正交试验设计了以煤泥、高水、水泥、粉煤灰为组合的胶结充填材料,采用极差、方差分析及多元回归分析等方法,研究了煤泥水百分浓度(A)、高水添加比例(B)、水泥添加比例(C)、粉煤灰添加比例(D)等4个关键因素对充填材料的初凝时间、扩散度及抗压强度、抗剪强度的影响机制。试验结果表明:①煤泥基充填材料的初凝时间为52~67 min,扩散度为42.0~76.5 cm,抗压强度为0.076~0.247 MPa,抗剪强度为0.033~0.139 MPa。对于初凝时间,影响显著性有B>C>A>D;对于扩散度,有A>D>B>C;对于抗压强度,有D>C>A>B;对于抗剪强度,有C>D>A>B。②拟合出了A、B、C、D与流动性指标及强度指标的数学关系式,初凝时间与A、B成二次函数关系、与C、D均呈指数关系;扩散度与A、B、C均呈指数关系,与D呈三角函数关系;抗压强度与A、D均呈指数关系,与B、C呈二次多项式关系;抗剪强度与A、B呈二次多项式关系、与C、D均呈指数关系;在A、B、C、D等4个因素与4个参数独立拟合方程的基础上,建立4因素共同影响下煤泥基充填材料流动性及强度特性参数预计模型,并进行了验证。

微乳液的制备及煤泥浮选应用研究

采取Schulman法制备煤油微乳液,从不同表面活性剂、亲水亲油平衡值(HLB值)、助表面活性剂中筛选最佳组分以确定煤油微乳液的体系组成。利用煤油/Tween 80-Span 80/正丁醇/水微乳液作为浮选捕收剂,对陕西南梁煤矿煤泥进行了系列浮选实验对比研究,结果表明,Span 80-Tween 80为复合乳化剂,正丁醇为助乳化剂,油水比为4∶1,HLB为9时,所制备的微乳液性能最稳定;制备微乳液为油包水型(W/O),整体粒径大小分布在10~100 nm,并且低含量状态下可以降低水的表面张力,从而实现良好的浮选效果。与煤油相比,在精煤灰分基本保持不变的情况下,精煤产率提高至65.12%,可燃体回收率达到94.78%,浮选完善指标达到72.45%,为选煤厂提高精煤产率,降低药剂消耗提供了思路。

吕家坨选煤厂粗煤泥分选回收工艺改造

阐述了吕家坨选煤厂为解决原有粗煤泥分选与回收系统分选效果差、回收效率低的问题,采用超级煤泥重介质旋流器+两段弧形筛+煤泥离心机回收工艺,对原有粗煤泥分选系统进行技术改造。改造后超级煤泥重介质旋流器对0.25~0.10 mm粒级分选可能偏差E pm低至0.087 kg/L,分选下限低至0.10 mm,两段精煤泥弧形筛筛分效率高达80.55%,增加精煤产率约0.6%,每年可给选煤厂增加税前利润3600万元。

煤泥深度浮选脱灰提质增值化利用试验研究

炼焦煤煤泥经深度脱灰提质后的高品质精煤产品可作为1种优质的炼焦原料,从而有效实现对炼焦煤煤泥的增值化利用。拟以内蒙古某洗煤厂的炼焦煤煤泥为试验对象并进行浮选试验研究,探究不同磨矿细度、捕收剂和抑制剂对浮选试验结果的影响规律,以期优化浮选流程结构。结果表明,控制磨矿细度为<0.074 mm占97.12%,以M231作为捕收剂、D8211作为抑制剂,采用带有精扫选的“一粗-一扫-三精”浮选试验流程,针对煤泥特点与性质进行全流程闭路浮选试验而得到精煤和尾煤产品,其精煤灰分在12%以内,尾煤灰分在82%以上。精煤产品达到炼焦原料的要求,尾煤可以用作建材原料,可实现炼焦煤煤泥深度脱灰提质的增值化利用与高效回收。

金属离子对蒙脱石颗粒水化作用影响及机理

这是一篇矿业工程领域的论文。蒙脱石是对煤泥水沉降影响显著的黏土矿物,其表面带电和易发生水化作用等特性阻碍颗粒间的聚团,使悬浮液保持分散性,恶化煤泥水沉降。基于沉降实验,考查了煤泥水中常见金属离子Na^(+)、K^(+)、Mg^(2+)、Ca^(2+)及Al^(3+)对蒙脱石沉降特性的影响,并采用微量热仪、Zeta电位分析仪及红外光谱仪等表征手段揭示金属离子对蒙脱石水化作用及沉降行为的影响机理。结果表明,与Na^(+)、K^(+)、Mg^(2+)相比,蒙脱石悬浮液或含蒙脱石煤泥水在加入Al^(3+)、Ca^(2+)后,可获得较小的沉降压缩层体积和上清液浊度,沉降效果较好。机理分析表明,加入金属离子可压缩蒙脱石表面双电层厚度,抑制蒙脱石水化作用,有利于蒙脱石聚团沉降。研究结果对处理含蒙脱石煤泥水具有一定指导意义。

超声处理对煤泥组分沉降速度的影响

这是一篇矿业工程领域的论文。高岭石与蒙脱石是煤泥中存在的主要黏土矿物,而黏土矿物是影响煤泥沉降的主要因素。本文以精煤、高岭石和蒙脱石作为研究对象,首先探索了超声强度、作用时间、超声脉冲间隔三类超声条件对其沉降效果以及絮团直径的影响,实验结果表明:当超声密度为0.4 W/cm^(3),超声作用时间为2 min时,高岭石和蒙脱石的沉降速度都得到了改善,选择合适的超声脉冲间隔时间对样品进行间断超声可以进一步提高其的沉降效果,但是超声处理反而不利于精煤沉降。将精煤、高岭石和蒙脱石试样按2∶1∶1的比例混合制样,改变超声脉冲间隔时间对其进行超声处理,结果表明:对于混合试样,未经超声处理时沉降速度为2.67 cm/min,在超声密度为0.2 W/cm^(3),超声脉冲间隔时间为4 s时作用2 min,沉降速度提高到5.41 cm/min。图像分析与电位表征显示,适当的超声脉冲间隔时间使药剂作用发挥更充分,进而双电层得到最大程度压缩,最终提高了颗粒凝聚和絮团生长效果。

粗糙度对贫瘦煤表面润湿性的影响

表面粗糙度对煤的可浮性起着重要作用。为了研究捕收剂和粗糙度协同作用对煤表面润湿性的影响,采用四种不同目数的砂纸对煤表面进行粗糙化处理,并使用粗糙度测量仪表征其表面特性。采用接触角与相互作用测量仪分析表面粗糙度对煤天然润湿性和油酸钠改性后润湿性的影响。结果表明,随着天然煤表面粗糙度的增加,接触角减小。由于接触线的增加,水滴与煤表面之间的扩散力增大。当粗糙度分别为0.32、1.02、1.82、2.38μm时,水与煤表面之间的扩散力分别为159.00、177.82、200.99、209.60μN。而经低浓度(120 mg/L)油酸钠改性后,随着粗糙度的增加,煤表面的接触角增大,扩散力减小,扩散力分别为149.11、146.40、134.06、124.27μN。但当油酸钠浓度达到320 mg/L时,随着粗糙度的增加,接触角反而迅速减小,扩散力迅速增大,扩散力分别为174.21、211.05、244.37、288.51μN。粗糙度的增大会增加天然煤表面的润湿性,低浓度的油酸钠改性和表面粗糙化可提高煤表面疏水性,然而,过量的药剂会增强煤表面的润湿性。

太阳能干化煤泥实验研究

针对煤泥热值低、干化成本高且污染严重等问题,利用太阳能为热源,进行了煤泥干化实验研究,考察了太阳光辐照度、煤泥层厚度等因素对煤泥干化效果的影响;探究了煤泥层厚度、太阳光辐照度对干化室内温度的影响规律。研究结果表明:太阳光辐照度为500 W/m^(2)即能达到理想的干化效果;提高煤泥层厚度对煤泥的干化有利。

旋流微泡浮选柱处理难浮煤泥的研究现状

旋流微泡浮选柱气泡尺寸小、泡沫二次富集作用强,在微细煤泥浮选时比传统浮选设备具有更好的分选效果。但对于其他难浮煤泥,如固体浓度高、粒度组成宽的浮选入料,尤其是很多配煤入选的选煤厂出现煤质波动时,旋流微泡浮选柱的浮选效果并不理想,这些问题限制了旋流微泡浮选柱的应用。因此,综述了旋流微泡浮选柱结构改进方面的研究进展,分析了不同结构的旋流微泡浮选柱针对三种难浮煤泥(微细煤泥、高浓度煤泥和宽粒级煤泥)的分选效果,并针对不同难浮煤泥提出了结构优化措施,以指导旋流微泡浮选柱有效分选多变的浮选入料。

煤泥热解和燃烧过程的行为特性研究

为了研究煤泥的热化学转化特性,本文利用热重分析仪进行了不同升温速率(10℃/min、20℃/min、30℃/min)下的热解和燃烧试验,采用Flynn Wall Ozawa(FWO)和Kissinger Akahira Sunose(KAS)2种动力学计算方法对煤泥热解和燃烧过程的动力学参数进行计算并比较。结果表明:随升温速率的提高,煤泥的热解和燃烧过程的热重(TG)与微商热重(DTG)曲线向高温方向偏移。煤泥热解过程的DTG曲线主要呈现两个明显的失重峰。而燃烧过程中,由于挥发物和固定碳燃烧过程的重叠,在300~580℃范围内其DTG曲线出现一个明显的失重峰,燃尽时间随升温速率的增大而减小。FWO法和KAS法计算得到的煤泥热解第一阶段活化能分别为175.78 kJ/mol和163.40 kJ/mol,第二阶段活化能分别为225.37 kJ/mol和209.51 kJ/mol。FWO法和KAS法计算得到的煤泥燃烧过程活化能分别为109.12 kJ/mol和102.65 kJ/mol,2种计算方法的结果具有较好的一致性,2种动力学计算方法综合使用有利于对煤泥的热解和燃烧过程形成更为全面的认识。

起泡剂对高灰尾煤泥浮选的影响及机理研究

以贵州某焦煤选厂浮选尾煤泥为研究对象,考察了甲基异丁基甲醇(MIBC)、仲辛醇、2号油、正戊醇等起泡剂对浮选尾煤泥再选提质的影响及作用机理。结果表明,用量相近时,MIBC为起泡剂所获得的浮选指标优于其他3种起泡剂。煤油用量1000 g/t、MIBC用量350 g/t时,灰分56.90%的原煤经一粗一精一扫浮选可获得灰分11.47%、产率32.03%的合格炼焦精煤产品。利用充气法研究了4种起泡剂的起泡能力及泡沫稳定性,发现2号油起泡能力和气泡稳定性均较强,正戊醇起泡能力和气泡稳定性均较弱,MIBC和仲辛醇表现适中。利用气泡-颗粒包覆角及诱导时间测量仪进一步分析了不同起泡剂作用下气泡与煤粒黏附作用过程,发现MIBC可以提升气泡的载矿能力,缩短颗粒与气泡间的诱导时间,从而获得较好的浮选效果。

动力煤选煤厂煤泥梯级提质及无量化研究

为了适应煤泥减量化的需求,以淮北桃园选煤厂动力煤为研究对象,基于煤泥粒度、密度和矿物组成分析,提出了三阶段煤泥减量化的技术路线,确定了粗煤泥重选和尾煤泥深度浮选的梯级降灰提质以及细煤泥新型压滤机降水提质方案。研究结果表明:粗煤泥分别采用干扰床分选机和螺旋分选机进行分选试验,以螺旋分选粗精煤产率更高,产率为88.82%,灰分为23.05%;尾煤泥采用一次浮选回收,当药剂用量为0.45kg/t,入料浓度为90g/L时,精煤产率为41.31%,灰分为15.74%,发热量可提高到20.97MJ/kg。经过粗煤泥分选、尾煤泥浮选以及细煤泥脱水,粗精煤和精煤泥的发热量分别提高了23.50%,65.30%,煤泥经降水后可全部回掺,其掺混后商品煤发热量为21.32MJ/kg,实现了动力煤选煤厂的煤泥无量化。

预热空气当量比对循环流化床掺混煤泥预热燃烧的影响

煤泥灰含量大、颗粒细、热值低,煤泥的高效清洁燃烧是固废资源化利用的重要方式之一。采用煤粉流态化预热耦合循环流化床燃烧技术,在30 kW预热燃烧综合评价试验台上,控制煤泥掺混比、给料量、还原区当量比、二/三次风比例及过剩空气系数等参数不变,并借助煤气分析仪和烟气分析仪等测量仪器,开展了循环流化床烟煤掺混煤泥的预热燃烧试验。结果表明,循环流化床预热燃烧系统运行稳定可靠,预热温度800℃以上,预热燃料可持续稳定输送到循环流化床中;烟煤掺混高灰分的煤泥,循环灰量增加,循环流化床燃烧室温差小,温度均匀;预热空气当量比由0.36增至0.51时,预热器内温度增加,预热煤气中CO_(2)、HCN体积分数增加,CO、H_(2)、CH_(4)及NH_(3)体积分数降低,煤气热值由2.02 MJ/m^(3)降至1.49 MJ/m^(3);且随着预热空气当量比的增加,循环流化床燃烧室沿程NO体积分数增加,CO体积分数底部高、上部低,NO_(x)排放量由172 mg/m^(3)增至242 mg/m^(3)(6%O_(2)),可见,较低预热当量比有利于烟煤掺混煤泥的高效清洁燃烧。研究结果可为煤泥的高效燃烧利用提供新型技术路线和数据支持。