MECHANISM AND APPLICATION OF COAL DRY BENEFICIATION WITH AIR-DENSE MEDIUM FLUIDIZED BED

Ｃｏａｌｄｒｙｂｅｎｅｆｉｃｉａｔｉｏｎｗｉｔｈａｉｒ－ｄｅｎｓｅｍｅｄｉｕｍｆｌｕｉｄｉｚｅｄｂｅｄｈａｓｂｅｅｎｅｓｔａｂｌｉｓｈｅｄａｓａｈｉｇｈｅｆｉ－ｃｉｅｎｃｙｄｒｙｓｅｐａｒａｔｉｏｎｔｅｃｈｎｉｑｕｅｗｈｉｃｈａｐｐｌｉｅｓｆｌｕ－ｉ...

The Forming-Mechanism and Role of Creativity Thinking in Dry Coal Beneficiation of Coal with Air-Dense Medium Fluidized Bed

In this paper, the authors point out that the Creativity is an inevitable request in solving engineering and technological problems and that the coal beneficiation technology with air dense medium fluidized bed is a result of reversal thinking, and its forming mechanism is the use of other things for reference and the transplantation.

Research on numerical simulation of flow field in shallow-bath dense-medium separator

介绍了浅槽重介分选机的结构、工作原理和技术特点，并采用Fluent软件，对浅槽重介分选机内部的流场进行了分析和研究，得出了各主要位置的速度和速度变化规律。揭示了浅槽重介分选机在分选过程中的悬浮液体流场形态及运动规律，以为其结构设计和改进提供理论依据。

Numerical simulation and experimental verification of bubble size distribution in an air dense medium fluidized bed

Bubble size distribution is the basic apparent performance and obvious characteristics in the air dense medium fluidized bed (ADMFB). The approaches of numerical simulation and experimental verification were combined to conduct the further research on the bubble generation and movement behavior. The results show that ADMFB could display favorable expanded characteristics after steady fluidization. With different particle size distributions of magnetite powder as medium solids, we selected an appropriate prediction model for the mean bubble diameter in ADMFB. The comparison results indicate that the mean bubble diameters along the bed heights are 35 mm < D b < 66 mm and 40 mm < D b < 69 mm with the magnetite powder of 0.3 mm+0.15mm and 0.15mm+0.074mm, respectively. The prediction model provides good agreements with the experimental and simulation data. Based on the optimal operating gas velocity distribution, the mixture of magnetite powder and <1mm fine coal as medium solids were utilized to carry out the separation experiment on 6-50mm raw coal. The results show that an optimal separation density d P of 1.73g/cm 3 with a probable error E of 0.07g/cm 3 and a recovery efficiency of 99.97% is achieved, which indicates good separation performance by applying ADMFB.

Occurrence characteristics of mercury in high-mercury coal and distribution rule of mercury in products of an air dense medium fluidized bed

Mercury emitted from direct combustion of high-mercury coal does great harm to the environment. To make good use of high-mercury coal, it is necessary to study the occurrence characteristics of mercury in coal and high-efficient methods of mercury removal. In this paper, high-mercury coal of Guizhou Province of China was taken as an object to study the nature of mercury in coal and the rule of mercury removal by dry preparation method. Mercury mainly distributes in the medium and high density fractions, and has a good affinity with silicon, aluminum, iron, titanium, potassium, calcium, zinc, sodium and magnesium. It exists in minerals formed by these elements and presents significant correlation with ash in coal. After the high-mercury coal is separated by air dense medium fluidized bed, mercury content of clean coal is reduced to 1/10 of raw coal, while mercury content of gangue is increased to 3 times that of raw coal. This indicates that mercury in raw coal is rejected greatly by ADMFB and enriched in highdensity fractions. The rates of ash removal and mercury removal decrease with the density and present a very high correlation.

Effects of sintered metal distributor on fluidization quality of the air dense medium fluidized bed

Dry coal beneficiation using an air dense medium fluidized bed (ADMFB) requires the formation of a sta- ble and uniform bed from the dense medium. Others have shown that the structure and geometric parameters of the air distributor have a significant influence on the experimentally observed fluidization quality. In this study we used a sintered metal distributor (SMD) in the ADMFB separator and study its effect on the fluidization quality. The results show that for the same open area ratio (OAR), a smaller aper- ture in the SMD will provide improved fluidization quality. If aperture size is held constant bigger open area ratios result in improved fluidization quality. And, the fluidization quality also improves when the pressure drop across the SMD increases. A model relating distributor pressure drop and the geometric parameters of the SMD is also proposed.

Analysis and evaluation on pressure fluctuations in air dense medium fluidized bed

Pressure fluctuations contribute to the instability of separation process in air dense medium fluidized bed, which provides a high motivation for further study of underlying mechanisms. Reasons for generation and propagation of pressure fluctuations in the air dense medium fluidized bed have been discussed.Drift rate and collision rate of particles were employed to deduce the correlation between voidage and pressure fluctuations. Simultaneously, a dynamic pressure fluctuation measuring and analysis system was established. Based on frequency domain analysis and wavelet analysis, collected signals were disassembled and analyzed. Results show gradually intensive motion of particles increases magnitudes of signal components with lower frequencies. As a result of violent particle motion, the magnitude of real pressure signal's frequency experienced an increase as air velocity increased moderately. Wavelet analysis keeps edge features of the real signal and eliminates the noise efficaciously. The frequency of denoised signal is closed to that of pressure signal identified in frequency domain analysis.

RESEARCH ON DENSITY STABILITY OF AIRDENSE MEDIUM FLUIDIZED BED

In this paper on the basis of studying the distribution of fine Coal in the dense medAn fluidised bed. the optimai size range of fine coal, which constitutes a fluidized bed together with the dense medium, has been found. In the separating process the fine coal will continuously aeeumulate in fluidized bed, thus inevitably reducing the density of the bed.In order to keep bed density stable, the authors adopted such measures as split-now of used medium and complement of fresb dense medium.The experiment results in both lab and pilot systems of the air-dense medium fluidized bed show that these measures are effective and satisfactory. Then authors also have estabinbed some relative dynamic mathematical models for it.

DRY CLEANING OF COAL WITH AIR DENSE MEDIUM FLUIDIZED BED

This paper deals with the experimental study of dry cleaning of coal with air dense medium fluidized bed. This technique opens up an efficient way of coal separation for vast areas in the country where water resources are in short supply or coals tend to slime seriously in wet process. Tests show that it can separate any kind of coal (6--50mm) efficiently. The probable error E, can reach 0.05--0.08. The separating density can be adjusted in the range of 1.0--2.0 g/cm^3. This technique brings about enormous economic benifits.

Dense Pellicular Agarose-Glass Beads for Expanded Bed Application: Flow Hydrodynamics and Solid Phase Classifications

Two dense pellicular agarose-glass matrices of different sizes and densities, i.e., AG-S and AG-L, have been characterized for their bed expansion behavior, flow hydrodynamics and particle classifications in an expanded bed system. A 26 mm ID column with side ports was used for sampling the liquid-solid suspension during expanded bed operations. Measurements of the collected solid phase at different column positions yielded the particle size and density distribution data. It was found that the composite matrices showed particle size as well as density classifications along the column axis, i.e., both the size and density of each matrix decreased with increasing the axial bed height. Their axial classifications were expressed by a correlation related to both the particle size and density as a function of the dimensionless axial bed height. The correlation was found to fairly describe the solid phase classifications in the expanded bed system. Moreover, it can also be applied to other two commercial solid matrices designed for expanded bed applications.

重介分选密度智能控制系统在济二煤矿选煤厂的应用

阐述了济宁二号煤矿选煤厂针对重介分选密度控制问题,以数字化建设为基础,依托人工智能技术进行了智能化建设的探索。基于完善的生产传感器,采集原煤灰分、入洗煤量、磁性物含量、精煤灰分等生产数据入库保存,作为智能控制系统的数据基础。基于盘古大模型和优化求解技术构建重介分选密度设定值的智能推荐系统,并将推荐的分选密度自动下发到PLC系统执行,形成完整的生产闭环。生产实践表明,该系统控制得到的精煤产品灰分稳定性更高,精煤理论产率相比人工控制提升0.334%。

高含量重密度组分煤重介质旋流器分选特性研究

为了提高重介质旋流器对高含量重密度组分难选原煤的分选效率,设计了新型重介质旋流器模型装置,建立了颗粒在离心旋转流场中沉降分离数学模型,采用试验与理论分析相结合的方法研究新型重介质旋流器的分选特性,揭示高含量重密度组分难选煤分选特性随工艺参数的变化规律,探索影响新型重介质旋流器流场工作悬浮液动态稳定性的因素及重产物排料输运机制。研究结果表明,新型重介质旋流器分选高含量重密度组分煤时,底流重产物排料能力强、处理量大;离心旋流场中的悬浮液密度梯度分布小、密度相对均匀,底流与溢流密度差值较低,流场中悬浮液稳定性更强;入料的压力与悬浮液动态稳定性、分选精度及重产物排料效率直接相关,随着入料的压力增大,底流、溢流口排出悬浮液密度差值增大,可能偏差E值降低,分选精度提高,重产物排出量升高;当入料的压力为25 kPa时,实际分选密度为1.666 g/cm^(3),可能偏差E值为0.09 g/cm^(3),重产物产率为75.23%。本研究为高含量重密度组分煤的分选提供了新的思路。

基于时间序列对齐和TCNformer的重介精煤灰分多步预测

由于在重介分选过程中各个传感器位置不同,导致重介分选主要工艺参数与灰分存在时间滞后,影响了精煤灰分结果。基于回归模型的灰分预测方法缺乏对时间序列信息的利用,无法捕捉重介生产过程随时间变化的动态特性;基于时间序列的灰分预测方法未能充分考虑灰分和重介分选主要工艺参数之间的时间依赖关系。针对上述问题,提出了一种基于时间序列对齐和TCNformer的重介精煤灰分多步预测方法。通过滞后相关性分析来量化灰分与重介分选主要工艺参数之间的滞后步长,依此对重介分选主要工艺参数在时间维度上进行移动,使得灰分和重介分选主要工艺参数时间序列对齐,消除灰分和重介分选主要工艺参数之间的时间滞后。在Transformer模型的基础上,引入时间卷积网络(TCN)提取特征,并将单向编码器扩展为双向编码器,构建了TCNformer模型来实现精煤灰分多步预测。将时间序列对齐得到的与未来时刻灰分数据对应的过程变量序列作为解码器的输入,以提升模型预测精度。实验结果表明:该方法的平均绝对误差为0.1579%,均方根误差为0.2152%,平均皮尔逊相关系数为0.5051,能有效提升精煤灰分预测精度。

基于机器学习的Geldart A类加重质流化床的床层膨胀特性研究

为了预测Geldart A类加重质的膨胀特征,通过床层塌落试验,研究了床层流化过程中的气泡相和乳化相的组成与操作因素之间的关联,构建了操作气速、静止床高以及床层膨胀高度的数据集,进行了数据统计分布和相关性分析,利用具有最佳超参数的GBDT模型成功模拟了膨胀高度和影响变量之间的非线性关系,分析了特征变量的敏感性。结果表明,随着气速的逐渐增加,乳化相与气泡相的膨胀呈现先增加并略有减小的规律。对于不同的初始床高与床层膨胀高度,气泡相组成不受其变化的影响且组成比例相对稳定。操作气速的重要性得分是0.68,是膨胀高度最敏感的变量。而静止床高的重要得分仅为0.32,表明此变量对床层膨胀的影响较小。此外,由部分相关性分析可知,床层的膨胀高度对操作气速的依赖性具有一定的敏感性区间。

磁场对重介质旋流器分选精度的影响

为了研究径向向内磁场力对旋流器分选精度的影响,构建了实验室磁力调控型重介质旋流器分选系统,通过进行重介质旋流器分选单因素试验,发现增加电流强度和线圈匝数,可以有效地提高重介质旋流器分选精度,降低分选密度。以可能偏差Ep作为正交试验响应值,应用软件Design-expert进行正交试验设计,基于响应面法研究了入料压力、电流强度和线圈匝数的协同作用,深入探究外加磁场对分选精度的影响规律。结果表明:在正交区间内,Ep与入料压力、电流强度和线圈匝数均呈负线性相关,各因素间相互独立;对可能偏差Ep影响程度按大小排序为线圈匝数>电流强度>入料压力;当在入料压力0.04 MPa,电流强度3 A,线圈匝数1 000匝时,可能偏差Ep=0.026 8 g/cm^(3),相较于无磁场状态时重介质旋流器分选精度提高了51.71%。

中主应力对输电线路地基土强度影响研究

在静动荷载联合作用下,输电线路地基土所受到的应力路径十分复杂,同时在不同的输电线路路基上外界荷载或地形等因素也会对土体强度产生影响。为研究应力路径对土体的强度影响,文章采用空心圆柱扭剪仪(HCA)进行了一系列控制中主应力系数的定向剪切单元体试验。通过施加轴力和扭转模拟现实中的复杂路径,控制围压和中主应力系数b模拟现实中的复杂荷载情况,借此研究了不同中主应力系数和剪切角度对砂土的沉降和剪切强度的影响。研究表明:砂土的轴向破坏应力随角度的增大而减小;破坏广义剪应力随角度的增大而减小,并表现出明显的硬化;砂土的破坏广义剪应力与b值呈现负相关。

某稀有稀土多金属矿的预先抛尾工艺研究

内蒙古某稀有稀土多金属矿有用元素品位低、矿物组成极为复杂且嵌布粒度细小,导致现有选矿工艺中矿物解离成本高。为了减少进入细磨流程的矿石量,开展了粗粒预先抛尾工艺研究。通过重液浮沉试验,获得了原矿预先抛尾的理论分选指标。在系统的条件试验基础上,研发了原矿“重介质旋流器分选—摇床重选”的粗粒抛尾工艺,即矿石破碎至-1.25 mm后进行粒度分级,0.5~1.25、0.1~0.5 mm两个粒级的矿石分别利用重介质旋流器、摇床预先抛尾,抛尾粗精矿与-0.1 mm粒级的矿石合并为精矿产品。结果表明,该工艺可以实现入磨前抛弃30.72%的尾矿,获得REO、ZrO_(2)、Nb_(2)O_(5)回收率分别为94.03%、93.99%和91.04%的精矿,显著减少了需要细磨的矿石量,有助于节省磨矿成本,提升矿床开发经济效益。

哈尔滨地区锤击PHC管桩竖向承载力研究

文中通过对哈尔滨松花江漫滩区以中密-密实粗砂为持力层、采用锤击成桩工艺的PHC管桩承载力实测值普遍高于规范计算值的原因进行分析,利用置于中密-密实粗砂层上锤击施工的PHC管桩静载荷试验、高应变等测试成果,研究了PHC管桩单桩极限承载力、桩侧阻力及桩端阻力的大小、分布规律及各自的贡献比例,通过数据总结得到了砂土地区锤击施工PHC管桩极限端阻力提高系数,为哈尔滨地区PHC管桩单桩极限承载力的确定和研究提供了参考。

干法重介质流化床压力多尺度分析与流化质量表征

选煤是煤炭清洁加工利用的源头技术,干法选煤是干旱缺水地区与易泥化煤炭高效分选提质的重要途径。干法重介质流化床通过上升气流驱动加重质颗粒流化形成一定密度的气固流态化床层,实现对煤炭按密度分选,床层密度均匀稳定性即床层流化质量是决定分选精度的关键。受到气流、气泡、运动内构件、入料等多因素扰动,床层流化行为复杂多变,压力信号呈现出非均匀性、非线性、多尺度特征。基于干法重介质流化床压力信号的轴向差异传递与横向等效扩散特性,着重研究了床层轴向压差波动特征,提出流化质量定量表征方法。结果表明:基于时域分析可知,Geldart A类加重质颗粒床层总压降概率密度分布接近于正态分布;当床层散式膨胀时,由于颗粒间接触力的分布不均,概率密度呈现右偏且尖峰的偏离正态分布。通过频域分析发现,在床层膨胀区间的中末期,气泡主频主导了流化床的整个轴向区间;完全流化后的流化床,气泡主频仅控制着床层中部区域,床层浓度信号主频沿床层轴向分布变化明显。结合时域和频域信号分析结果,提出以轴向床层浓度主频为子区间波动标准差权重值的流化质量表征模型,可以综合评估干法重介质流化床的密度分布均匀性和稳定性,为干法重介质流化床分选密度稳态调控与精准分选提供有力支撑。

磁场对重介质旋流器介质稳定性的影响

重介质悬浮液具有非均相性,在离心浓缩作用下极易降低悬浮液的稳定性,继而直接影响重介质旋流器的分选精度。为削弱重悬浮液浓缩的影响并提高其稳定性,根据重介质磁铁矿粉具有顺磁性的特点,引入径向向内的磁场力以调节重介质颗粒在旋流器中的分布状态。采用理论计算、单因素试验以及三因素三水平的Box-Behnken正交试验方法,解释了磁力复合场中颗粒的运动规律;分析了入料压力、电流强度和线圈匝数对重介质分配以及悬浮液稳定性的影响规律;探究了各因素对重悬浮液浓缩效率E_(th)的影响规律,给出了各因素与响应值E_(th)的数学模型及其极小值。结果表明:在离心力场中引入径向向内的磁场力使重介质颗粒拥有更低的离心沉降末速v_(ro)^(m),改变了重介质分配规律,使溢流悬浮液密度升高,底流密度降低;随入料压力增大,重悬浮液浓缩度C_(1)、澄清度C_(2)、分层度C_(3)以及浓缩效率E_(th)均呈相似增加的趋势;随电流强度和线圈匝数增加,均呈相似降低的趋势;在正交区间内,浓缩效率E_(th)与入料压力正线性相关,与电流强度和线圈匝数负线性相关,影响程度按大小排序:入料压力>线圈匝数>电流强度;最终得到E_(th)的线性模型和极小值,即当入料压力为0.03 MPa,电流强度为3 A,线圈匝数为1 000时,E_(th)=0.067,相较于无磁场状态下的浓缩效率0.37,重悬浮液稳定性提高了81.89%。