Changes in underflow solid fraction and yield stress in paste thickeners by circulation

The trouble-free and efficient operation of paste thickeners requires an optimal design and the cooperation of each component.When underflow discharging is suspended, alleviating the vast torque that the remaining solids within the thickeners may place on rakes mainly lies in the circulation unit. The mechanism of this unit was analyzed, and a mathematical model was developed to describe the changes in underflow solid content and yield stress. The key parameters of the circulation unit, namely, the height and flow rate, were varied to test its performance in the experiments with a self-designed laboratorial thickening system. Results show that the circulation unit is valid in reducing underflow solid fraction and yield stress to a reasonable extent, and the model could be used to describe its efficiency at different heights and flow rates. A suitable design and application of the circulation unit contributes to a cost-effective operation of paste thickeners.     

基于循环系统的膏体浓密机底流调控及其数学模型

为了保证浓密机在高料位下不压耙,一般通过增设循环系统使料浆始终处于活化状态,降低耙架运行阻力.然而,目前循环参数对底流的影响规律不明确,造成系统的设计及应用缺乏科学依据,为此开展了循环参数对底流的调控研究.分析循环系统的作用原理,将循环系统作用范围划分为两大区域,揭示循环参数对底流的调控机制,运用微积分原理对区域内的底流体积分数变化进行求解,最终建立浓密机底流调控数学模型.最后,利用该模型对底流循环实验参数进行验证.研究结果表明:开启底流循环后,底流体积分数开始降低并最终趋于稳定,底流体积分数差随着循环流量及循环高度增大而增大,体积分数变化幅度为0.7%~2.2%,稳定所需时间随流量及高度增加而减小.该理论模型完全吻合验证结果函数,为循环系统的设计及运行提供理论依据.     

膏体增稠剂底流固相分数和屈服应力的循环变化行为

The trouble-free and efficient operation of paste thickeners requires an optimal design and the cooperation of each component. When underflow discharging is suspended, alleviating the vast torque that the remaining solids within the thickeners may place on rakes mainly lies in the circulation unit. The mechanism of this unit was analyzed, and a mathematical model was developed to describe the changes in underflow solid content and yield stress. The key parameters of the circulation unit, namely, the height and flow rate, were varied to test its performance in the experiments with a self-designed laboratorial thickening system. Results show that the circulation unit is valid in reducing underflow solid fraction and yield stress to a reasonable extent, and the model could be used to describe its efficiency at different heights and flow rates. A suitable design and application of the circulation unit contributes to a cost-effective operation of paste thickeners.     

深锥浓密机底流浓度模型及动态压密机理分析

泥层高度和底流浓度是深锥浓密机最为重要的两个参数,因此有必要研究底流浓度随泥层高度的变化规律.采用自制小型深锥浓密机,对尾矿非连续/连续动态压密过程进行了物理实验;借助于有效孔隙比与泥层压强间遵循的Power函数关系,结合对尾矿颗粒的受力分析,推导出了底流浓度与泥层高度的数学模型,揭示了浓密机底流浓度与泥层高度的内在关系,并从尾矿颗粒空间结构的角度解释了该模型的变化规律;结合矿山生产对于底流浓度的要求,应用该数学模型,为其推荐了泥层高度的合理范围,验证了底流浓度数学模型的可靠性.该模型为深锥浓密机的设计和运行提供了理论依据.     

全尾砂浓密特性研究及其在浓密机设计中的应用

在实验装置中添加了转子导流系统,使模型装置更接近于现场高效浓密机.采用均匀设计方法,以单位面积固体处理量和底流体积分数作为尾砂浓密效果的评价指标,考察各因素对尾砂浓密效果的影响.结果表明:单位面积固体处理量与絮凝剂单耗正相关,最佳入料体积分数为6·56%;底流体积分数与入料体积分数、停留时间和絮凝剂单耗均正相关.最后通过凯奇沉降模型对沉降曲线进行分析,速度限制层一般为过渡区与压缩区的交界处,根据实验结果和尾砂日处理量计算得出浓密机的最小直径为14m.     

深锥浓密机底流浓度预测与外部结构参数优化

针对困扰支持向量机(SVM)模型参数选择问题,结合遗传算法(GA),建立了深锥浓密机底流放砂浓度的GA-SVM预测模型,研究了不同结构参数状态下底流浓度的变化规律,进行了深锥浓密机的外部结构参数优化选择。以司家营铁矿为例,在最优底流放砂浓度为72%的条件下,经外部结构参数优化后的深锥浓密机锥高10m、锥角为30°,系统稳定可靠、底流连续均匀,动力荷载较同类矿山降低约15%,压耙停机故障降低80%。     

Effect of reduction roasting by using bio-char derived from empty fruit bunch on the magnetic properties of Malaysian iron ore

Beneficiation of Malaysian iron ore is becoming necessary as iron resources are depleting. However, the upgrading process is challenging because of the weak magnetic properties of Malaysian iron ore. In this study, bio-char derived from oil palm empty fruit bunch (EFB) was utilized as an energy source for reduction roasting. Mixtures of Malaysian iron ore and the bio-char were pressed into briquettes and subjected to reduction roasting processes at 873–1173 K. The extent of reduction was estimated on the basis of mass loss, and the magnetization of samples was measured using a vibrating sample magnetometer (VSM). When reduced at 873 K, the original goethite-rich ore was converted into hematite. An increase in temperature to 1073 K caused a significant conversion of hematite into magnetite and enhanced the magnetic susceptibility and saturation magnetization of samples. The magnetic properties diminished at 1173 K as the iron ore was partially reduced to wustite. This reduction roasting by using the bio-char can assist in upgrading the iron ore by improving its magnetic properties.     

Bakken油藏注气方式的模拟与预测

Bakken储层是一种极致密油藏,具有低孔隙度、低渗透率的特点。以加拿大萨斯喀彻温省东南部地区Viewfield油田为例,利用Bakken致密储层及裂缝特征,通过建立10口相关油井的地质模型并进行数值模拟实验,来确定有效的注气方式对提高致密油采收率的可靠性和可行性。历史拟合的结果验证了数值模型与试验区实际生产数据和压力变化保持一致,确保了模型的有效性。同时,模拟研究评估了多种采收方案,如水驱法、二氧化碳气驱、水气交替法（CO₂-WAG）以及甲烷气驱对采收率的影响。目前研究结果表明,对累计产油量最敏感的两个参数是相对油水渗透率（K_row）和原生水饱和度（S_wcon）。其他对采收率影响较大的参数分别是二氧化碳的注入速率、水气交替循环次数、总注入次数和吸收时间。通过对比不同的采收方式,循环周期为两年的水气交替注入法对提高采收率的效果最好,其原油采收增产率可达5.033%。本次研究基于历史拟合的结果,预测、比较了不同注气方式对提高Bakken地区致密油藏采收率及经济效益的影响,可以有助于优化设计萨斯喀彻温省东南部致密油藏区块的开发及开采方案。     

钛氧化物还原与钛渣变稠

采用攀钢高炉现场渣经过还原,获得具有一定钛氧化物还原度的炉渣试样,进一步测定样品的粘度和熔化性温度。随着钛氧化物还原度的提高,炉渣的粘度和熔化性温度总体呈上升趋势。用矿相显微镜研究了炉渣的显微结构前用图象分析仪对渣中TiC、TiN进行了定量研究。结果表明,高钛型高炉渣的变稠还与钛氧化物还原生成的TiC、TiN数量有关。因此高炉冶炼过程中用钛氧化物还原度作为判断和控制钛渣变稠的指标能更准确地反映高炉过程特点。     

邦德功指数试验的模型化及仿真

本文用数学模型方法和计算机仿真技术,系统地分析、研究了测定邦德功指数的可磨度试验,成功地提出了一种快速、准确的测定邦德功指数的计算机仿真方法。六种标准矿样的对比实验结果表明:这些矿样的功指数的计算机仿真值与实测值非常接近,由计算机打印出的仿真过程与实际可磨度试验过程是一致的。在计算机上完成测定功指数的仿真过程一般为2分钟左右,它不仅提高了测定精度,而且大大减少了测定功指数的试验时间和工作量。     

基于随机森林模型判别矿井涌(突)水水源

快速准确判别矿井涌(突)水水源对保障矿井安全生产有重要意义。近年来人类的活动对不同含水层的影响与日俱增,为提高矿井涌(突)水水源判别的准确性,提出选取地下水中7种常见离子浓度,和能够充分反映人类活动痕迹的硝酸根离子浓度及化学需氧量作为水化学判别指标,采用随机森林模型进行矿井涌(突)水水源判别。为验证选取指标和判别方法的有效性,以大孤山铁矿为例,将数据输入随机森林模型进行100次交叉验证,并将验证结果与支持向量机模型和极限学习机模型进行比较。结果表明,随机森林模型预测结果稳定性较强,预测正确率不容易波动;随机森林在建模过程中参数拥有宽广的适应范围。树的棵数为50时,训练误差趋于稳定,改变树的棵数对预测结果没有实际影响,而其余二者对参数选取较为敏感;随机森林的参数可以通过袋外数据(OOB)错误率简单地得到,而其余二者参数调整时需要通过交叉验证的方式才可以取得;随机森林对训练样本进行验证,正确率可达100%,对测试样本进行验证,正确率可达97.38%,两项精度均优于支持向量机与极限学习机;随机森林模型拥有更高的预测精度和鲁棒性,在矿井涌(突)水水源判定方面有较好的应用前景。     

竖炉焙烧磁选管回收率智能预报模型

针对竖炉焙烧过程衡量焙烧矿质量好坏的磁选管回收率化验滞后和难以建立其机理模型的问题,基于智能技术提出了由数据采集与处理模块、决策支持模块、预报模块、在线校正模块以及效果评价模块组成的磁选管回收率智能预报模型.介绍了模型的结构及各个模块的主要功能,并将建立的智能预报模型用于竖炉焙烧过程的优化控制与决策之中,为选矿厂综合自动化系统的优化控制与优化运行奠定了良好的基础,并且其维护费用低,实时性好,可靠性及精度高,取得了明显的成效.     

基于不同粒级硫化铜矿石生物浸出的动力学

西藏甲玛地区的硫化铜矿石中含铜矿物以次生硫化铜矿物为主,且含量较低.采用氧化亚铁硫杆菌柱浸的方法对该矿石进行了生物浸出并研究了浸出动力学.基于不同粒级矿石,考察了粒级对铜浸出速率和浸出率的影响,并对浸出率与收缩核模型中的控制方程进行了拟合,确定了浸出过程的控速环节.试验结果表明,铜的浸出速率和浸出率随粒级的减小而增加.矿石表面形貌的SEM表明,浸出过程中矿石表面形成了包含黄钾铁矾的产物层,阻碍了浸出反应的进行.浸出动力学表明,该矿石的浸出过程符合收缩核模型,且浸出应主要受固体产物层内扩散控制.     

Slag formation path during dephosphorization process in a converter

The slag formation path is important for efficient dephosphorization in steelmaking processes. The phosphorus capacity and the melting properties of the slag are critical parameters for optimizing the slag formation path. Regarding these two factors, the phosphorus par-tition ratio was calculated using the regular solution model (RSM), whereas the liquidus diagrams of the slag systems were estimated using the FactSage thermodynamic package. A slag formation path that satisfies the different requirements of dephosphorization at different stages of dephosphorization in a converter was thus established through a combination of these two aspects. The composition of the initial slag was considered to be approximately 15wt%CaO–44wt%SiO2–41wt%FeO. During the dephosphorization process, a slag formation path that fol-lows a high-iron route would facilitate efficient dephosphorization. The composition of the final dephosphorization slag should be approxi-mately 53wt%CaO–25.5wt%SiO2–21.5wt%FeO. The composition of the final solid slag after dephosphorization is approximately 63.6wt%CaO–30.3wt%SiO2–6.1wt%FeO.     

丙烯酸系交联缔合型增稠剂的制备及表征

以甲基丙烯酸（MAA）、丙烯酸乙酯（EA）和亲水性聚氧化乙烯长链末端连有疏水性烷基长链的功能单体（BEM）为原料,采用半连续乳液聚合方法,合成交联剂邻苯二甲酸二烯丙酯（DAP）的质量分数不同的憎水改性交联缔合型增稠剂乳液。测定乳液基本性能,对其碱溶液黏度和透光率随 pH 值的变化进行表征。结果表明,随 NaOH 溶液的加入,乳液的 pH 值升高,其透光率迅速增大达到最大值后基本不变;而其黏度随 pH 值的变化趋势是先迅速升高后缓慢下降;交联剂用量对增稠剂碱溶液的以上行为有明显影响;聚合时加入少量交联剂可提高增稠剂的增稠效果及其抗剪切性能,但其使用量超过单体质量 0. 1%时则会明显降低其增稠效果。     

无底柱分段崩落法结构参数研究

为减少矿石生产成本,提高矿山经济效益,对无底柱分段崩落法结构参数进行研究.以大间距结构参数理论为基础,通过正交试验法确定9组不同的结构参数,利用多分段立体放矿模型,分别进行实验室放矿试验和计算机放矿数值模拟,然后,将2种不同方法所获得的实验数据采用直接分析法和Matlab回归分析法对比研究,分析无底柱分段崩落法各结构参数对矿石回收率等的影响,并最终确定合理的无底柱分段崩落法采场结构参数.     

Artificial neural network approach to assess selective flocculation on hematite and kaolinite

Because of the current depletion of high grade reserves, beneficiation of low grade ore, tailings produced and tailings stored in tailing ponds is needed to fulfill the market demand. Selective flocculation is one alternative process that could be used for the beneficiation of ultra-fine material. This process has not been extensively used commercially because of its complex dependency on process parameters. In this paper, a selective flocculation process, using synthetic mixtures of hematite and kaolinite in different ratios, was attempted, and the adsorption mechanism was investigated by Fourier transform infrared (FTIR) spectroscopy. A three-layer artificial neural network (ANN) model (4-4-3) was used to predict the separation performance of the process in terms of grade, Fe recovery, and separation efficiency. The model values were in good agreement with experimental values.     

浓香型白酒固形物超标原因及解决方法的研究

介绍了浓香型白酒固形物超标的原因主要有加浆水、调香添加剂等.解决方法是保证加浆水勾兑用水质量、选用高质量添加剂;使用软化水硬度在质量浓度0.04mg/L以下的加浆水,浓香型白酒固形物含量与自来水比较减少25倍,使用高质量的添加香料固形物可减少30%.     

Structure and Properties of Polytetrafluorethylene and Polyurethane Layered Membrane for Protective Clothing

IntroductionProtective clothing articles used for wear in wetconditions ; in outdoor activities ; in handling hazardouschemicals , in preventing contamination, in avoidinginfection, should in each instance protect the wearer bypreventing leakage of water or other fluids andmicroorganisms into the article while keeping the wearercomfortable by allowing perspiration to evaporate from thewearer to the outside of the article .In additionto the above ,the amount of stretch and its recovery and the …     

分支载体浮选的理论与实践

分支载体浮选(RCF)是一种处理细粒低品位矿石的革新工艺。该工艺采用分支浮选流程并用自身的粗粒精矿取代了常规载体浮选中的外加异类载体矿物。本文研究了黑钨矿、红铁矿、难溶铜、氧化铅锌、铜钼矿和锑砷硫化矿等七种不同矿物的分支载体浮选。和常规方法相比较,分支载体浮选除了可以显著降低药剂消耗,避免载体与超细粒之间的再分离,不需回收载体等,从而解决了常规法中存在的技术问题以外,还能够得到更高的回收率与分选效果。通过浮选试验、动电位测定和电子显微镜观察,进行了分支载体浮选过程机理的研究,结果表明矿泥罩盖的机理已经不适用,提出了新的“碰撞-粘附”模型。在这一模型中,将影响分支载体浮选的因素分为几何、物理、化学三大类并根据实验现象进行了详细的讨论。