Dynamic modeling and analysis of the closed-circuit grinding-classification process

Mathematical models of the grinding process are the basis of analysis, simulation and control. Most existent models in- cluding theoretical models and identification models are, however, inconvenient for direct analysis. In addition, many models pay much attention to the local details in the closed-circuit grinding process while overlooking the systematic behavior of the process as a whole. From the systematic perspective, the dynamic behavior of the whole closed-circuit grinding-classification process is consid- ered and a first-order transfer function model describing the dynamic relation between the raw material and the product is established. The model proves that the time constant of the closed-circuit process is lager than that of the open-circuit process and reveals how physical parameters affect the process dynamic behavior. These are very helpful to understand, design and control the closed-circuit grinding-classification process.

Influence of microwave treatment on grinding and dissociation characteristics of vanadium titano-magnetite

The effect of microwave treatment on the grinding and dissociation characteristics of vanadium titano-magnetite(VTM) ore were investigated using scanning electron microscopy(SEM), nitrogen absorption measurements, particle size distribution measurements, X-ray diffraction(XRD) analysis, Fourier transform infrared(FT-IR) spectroscopic analysis, and magnetic separation. SEM analysis showed that microfractures appeared in the microwave-treated VTM, which is attributed to the microwaves' selective heating characteristic and the differential expansion between minerals and gangues. Nitrogen absorption showed that the microfractures were more pronounced when the microwave heating time was increased. Particle size distribution analysis showed that microwave treatment could improve the grindability of the VTM, thus increasing the weight percent of the fine-ground product. The increase in grindability was more significant with prolonged heating time. Moreover, the particle size distribution of the fine-ground product changed only slightly after the microwave treatment. XRD analysis showed that the crystallinity of the microwave-treated VTM increased with increasing microwave heating time. The magnetic separation tests revealed that the separation efficiency increased as a result of the intergranular fractures generated by microwave treatment. The Fe grade of the magnetic fraction of microwave-treated VTM was 1.72% higher than that of the raw ore. We concluded that the microwave treatment was beneficial, especially for the mineral processing characteristics.

Microwave assisted grinding of ilmenite ore

The influence of microwave heating on the grinding of Panzhihua ilmenite ore was investigated. Factors that influence the processing are： the microwave exposure time, power density and sample mass. 40 g sample was microwave heated for 30 s with 1 kW of microwave power and followed by water quenching. SEM analysis indicated that intergranular fractures occurred between ores and gangues other than transgranular fractures after microwave treatment, which would liberate minerals from each other effectively. The subsequently magnetic separation trials provided evidence that the recovery rate increased from 44% for raw ore to 72% by microwave treatment.

CONTROLLING OVERGRINDING OF VALUABLE MATERIALS USING MODIFIED AIRSPARGED HYDROCYCLONE

ＣＯＮＴＲＯＬＬＩＮＧＯＶＥＲＧＲＩＮＤＩＮＧＯＦＶＡＬＵＡＢＬＥＭＡＴＥＲＩＡＬＳＵＳＩＮＧＭＯＤＩＦＩＥＤＡＩＲＳＰＡＲＧＥＤＨＹＤＲＯＣＹＣＬＯＮＥ￥ＣｈｕＬｉａｎｇｙｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｃａｌＰｒｏｃｅｓｓｉｎｇＭａｃｈｉ...

Grinding Chatter Detection and Identication Based on BEMD and LSSVM

Grinding chatter is a self?induced vibration which is unfavorable to precision machining processes. This paper proposes a forecasting method for grinding state identification based on bivarition empirical mode decomposition(BEMD) and least squares support vector machine(LSSVM), which allows the monitoring of grinding chatter over time. BEMD is a promising technique in signal processing research which involves the decomposition of two?dimen?sional signals into a series of bivarition intrinsic mode functions(BIMFs). BEMD and the extraction criterion of its true BIMFs are investigated by processing a complex?value simulation chatter signal. Then the feature vectors which are employed as an amplification for the chatter premonition are discussed. Furthermore, the methodology is tested and validated by experimental data collected from a CNC guideway grinder KD4020 X16 in Hangzhou Hangji Machine Tool Co., Ltd. The results illustrate that the BEMD is a superior method in terms of processing non?stationary and nonlinear signals. Meanwhile, the peak to peak, real?time standard deviation and instantaneous energy are proven to be e ec?tive feature vectors which reflect the di erent grinding states. Finally, a LSSVM model is established for grinding status classification based on feature vectors, giving a prediction accuracy rate of 96%.

A New Method of Grinding Lean Magnetite-Quartz Ores*

This paper deals with the problems in grinding lean magnetite-quartz ores, and gives a new method of selective grinding. The good performance of the new method of ore-dressing is analysed, anti the application prospects of the new iron-ore dressing in industry are predicted.

Selective reduction of carbon dioxide into amorphous carbon over activated natural magnetite

Natural magnetite formed by the isomorphism substitutions of transition metals,including Fe,Ti,Co,etc.,was activated by mechanical grinding followed by H2 reduction.The temperature-programmed reduction of hydrogen(H2-TPR)and temperature-programmed surface reaction of carbon dioxide(CO2-TPSR)were carried out to investigate the processes of oxygen loss and CO2 reduction.The samples were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM),and energy-dispersive X-ray spectroscopy(EDS).The results showed that the stability of spinel phases and oxygen-deficient degree significantly increased after natural magnetite was mechanically milled and reduced in H2 atmosphere.Meanwhile,the activity and selectivity of CO2 reduction into carbon were enhanced.The deposited carbon on the activated natural magnetite was confirmed as amorphous.The amount of carbon after CO2 reduction at 300°C for 90 min over the activated natural magnetite was 2.87wt%higher than that over the natural magnetite.

南芬选矿厂北山矿石选矿工艺试验

为配合南芬铁矿绿色矿山选矿提效及高效利用北山原矿石,在工艺矿物学研究的基础上,对北山矿石进行了选矿工艺流程试验。试验结果表明:采用辊磨前干抛—高压辊磨—辊磨产品湿式抛尾—阶段磨矿—弱磁选工艺,干抛和湿抛可提前抛除合计产率23.26%的尾矿,大幅降低了后续入磨矿量,提升了入磨矿样铁品位,最终获得的铁精矿产率为30.77%,TFe和mFe含量分别为68.17%和60.22%,TFe和mFe回收率分别为66.63%和98.16%。

307滚珠轴承内圈外沟道磨削烧伤在线辨识研究

磨削表面层质量直接影响着机械零件的使用寿命和可靠性,磨削烧伤则是产生磨削表面有害变质层的主要因素。本文依据磨削中主要磨削段磨削火花温度信号是一个相关性较强的连续宽平稳随机过程,与磨削区温度具有良好的一致性,烧伤类与未烧伤类在时域和频域上都具有不同的表现特征。运用模式识别原理,在磨削火花温度样本特征统计特性分析基础上,提出了一种基于单类样本集的两类模式状态辨识方法,对磨削烧伤进行状态辨识。

纳米复合瓷球作磁铁矿细磨介质磨矿特征研究

三段磨矿工艺通常采用钢锻或钢球作为细磨介质,存在高能耗、高球耗和粒度分布特性差等问题。以尖山铁矿三段球磨机给矿作为研究对象,进行了批次磨矿试验,研究了钢锻和瓷球作为细磨介质下的磨矿动力学特征以及瓷球磨矿工艺参数对产品粒度特性的影响。结果表明:超细粒级磁铁矿磨矿动力学线性特征不明显,更倾向于一阶磨矿动力学特征,且瓷球的细磨能力优于钢锻。瓷球磨矿工业应用后,在相同溢流细度和铁精矿品位下,球耗降幅达17.52%,节电幅度达42.37%,综合磨矿成本下降32.11%。瓷球可作为新型介质完全替代钢锻磨矿。

罗河铁矿精确化磨矿试验研究

罗河铁矿为提高一段磨矿能力,针对其溢流细度不足的问题,以一段入磨产品为研究对象,进行了精确化磨矿试验研究。试验结果表明:采用球径ϕ40 mm、ϕ30 mm、ϕ20 mm配比为40%∶50%∶10%,混合球径平均33 mm的精确化磨矿装球制度,与现场一段溢流相比,闭路试验获得的产品欠磨粒级铁分布率由37.81%降低至20.78%,合格粒级铁分布率由42.32%提升至59.89%,过磨粒级铁分布率由19.87%降低至19.33%;磁选试验获得的精矿产品铁回收率为89.92%,均大于采用偏大球装球制度和偏小球装球制度获得的铁回收率;精确化磨矿制度可以改善磨矿产品的粒度分布特性,提高磨矿产品的选别指标。

高压辊磨对超微细粒嵌布磁铁矿破碎和预选的影响

针对某超微细粒嵌布贫磁铁矿开发难度大、原矿入磨品位偏低、磨矿能源消耗高的问题,本文进行高压辊磨—预选工艺试验,通过对比两种破碎产品的粒度特征、相对可磨度、Bond球磨功指数、预选指标,并结合破碎产品的表面形貌和内部微裂纹,研究高压辊磨所产生的微裂纹对于磨矿和分选的影响。结果表明:相对于常规破碎,辊压产品中<0.074 mm粒级质量分数增加了14.69个百分点,>2 mm的粗粒级质量分数降低了8.59个百分点;在160 kA/m预选磁场强度下,辊压产品的铁品位为31.96%,提高了1.46个百分点;磁性铁的回收率高达99.45%,提高了1.17个百分点,抛尾率提高了5.03个百分点。相对可磨度试验结果表明,当磨矿细度达到<0.03 mm粒级质量分数为85%时,辊压产品的耗时相对于常规破碎缩短了42.13%。辊压产品的Bond球磨功指数(目标粒度<0.15 mm)降低了27.90%。偏光显微镜和SEM扫描电镜结果表明,辊压产品结构疏松多孔、微裂纹发育充分,能产生大量的晶界裂纹,解离更充分。

某磁铁矿选矿工艺试验研究

对某磁铁矿进行工艺矿物学研究,查明了矿石的矿物组成、化学组成、嵌布特征等。结果表明:该磁铁矿主要元素为TFe、Si、Ca、Al、Mg、K、Na等,矿石中主要回收元素TFe含量为43.82%,杂质元素Si含量为11.53%,Ca含量为5.65%,Mg含量为2.01%,有害元素S含量为2.36%,P元素为0.04%;该矿石中主要含铁矿物为磁铁矿和黄铁矿。脉石矿物主要为透辉石、黑云母、钙长石和铁橄榄石;次要矿物为方解石、钾长石、绿泥石、普通辉石、钙铁橄榄石、硅灰石、黄铜矿、磁黄铁矿、白钨矿等;磁铁矿为主要的目的矿物,绝大多数属于单体解离形式,一小部分磁铁矿内部包裹无定形的透辉石,另一部分磁铁矿与钙长石相互连生,少量磁铁矿与透辉石呈相互共生关系。针对该矿石特点,采用“一段阶段磨矿—粗选—二段阶段磨矿—二次精选”的工艺流程,可获得弱磁铁精矿产率56.27%,TFe品位68.43%,mFe品位67.31%,TFe回收率91.41%,mFe回收率98.51%的精矿产品指标;总尾矿产率43.73%,TFe品位8.56%,TFe分布率8.86%的抛尾指标。该工艺流程对该磁铁矿具有一定的适应性,能得到良好的选矿指标,具有较好的应用和推广前景。

某磁铁矿瓷球精确化磨矿及工业应用

为了探究安徽某磁铁矿二段磨矿中应用瓷球磨矿代替钢球磨矿的可行性,以该磁铁矿厂二段磨矿给矿为研究对象,对瓷球磨矿球径配比、磨矿浓度和充填率进行了单因素实验,并在此基础上进行了磨矿动力学研究和工业应用。结果表明:瓷球可以替代钢球作为该磁铁矿二段磨矿介质,且瓷球磨矿可优化磨矿产品粒度分布;物料粒度大于0.092 mm时,瓷球磨矿比例系数大于钢球磨矿,物料粒度小于0.092 mm时,瓷球磨矿比例系数小于钢球磨矿;瓷球磨矿适宜条件为:直径30 mm、25 mm、20 mm的瓷球按质量比1∶3∶1配比,矿浆浓度(质量分数)74%,充填率40%;工业应用中瓷球磨矿可有效改善溢流产品粒度分布,并使磨矿单位电耗下降51.89%,球耗降低50%。

刚果(金)某选矿厂磨矿优化控制专家系统研究

磨矿是选矿流程的关键作业之一,传统选矿厂通常因矿石可磨性质波动导致磨矿工艺频繁调整,相关控制参数的调整多数依赖人工经验,刚果(金)某选矿厂磨矿作业存在类似问题。本文在深入研究传统选矿厂工艺和刚果(金)选矿智能化改造和工艺控制需求后,提出了磨矿优化控制专家系统解决方案,通过磨矿工艺流程智能化控制策略对生产流程和工艺设备进行了改造,实现了磨矿过程的智能化控制和工艺分级优化,为选矿厂工艺流程优化和智能化升级提供技术方案和建设路径。

关于减少过粉碎现象的主要措施研究

过粉碎现象普遍存在于碎矿与磨矿过程中。过粉碎既会增加磨矿过程中的能耗,又会恶化后续选别过程,造成矿物资源的浪费。为减少过粉碎现象,从磨矿介质制度和分级进行优化可以有比较显著的效果。新型磨矿介质如陶瓷球,比传统的钢球拥有更好的磨矿作用;循环负荷和分级的优化可以减少不必要的磨矿。文章主要从工程实际生产的例子,讨论通过优化上述因素,来降低过粉碎现象,从而提高企业的技术经济指标。

眼前山磁铁矿石选别试验研究

为促进眼前山铁矿的合理开发利用,以该地区矿石为研究对象在工艺矿物学分析的基础上进行了选别试验研究。结果表明:矿石含铁矿物以磁铁矿为主,主要脉石矿物为石英,并存在绿泥石、角闪石等易泥化矿物。采用阶段磨矿阶段选别工艺进行分选,各段工艺参数分别为一段-2 mm下进行磁选,磁选场强为279 kA/m;一段磨矿细度为-75μm含量80%,磁选场强为159 kA/m;二段磨矿细度为-45μm占90%,磁选场强为95 kA/m,最终可获得铁品位66.50%、铁回收率95.90%的磁选精矿。研究结果为该地区铁矿资源的开发利用提供了参考依据。

纳米陶瓷球在程潮选厂二段磨矿中的应用试验

程潮选厂为降低二段磨矿成本,引进新型纳米陶瓷球作为磨矿介质,以二段球磨给矿为研究对象,开展全陶瓷球、全钢球、陶瓷球+钢球不同磨矿介质的磨矿特性及磁选试验研究。试验结果表明:在磨矿时间3 min,介质充填率36%,磨矿浓度67%的条件下,采用质量比5∶5的纳米陶瓷球(ϕ30 mm、ϕ25 mm、ϕ20 mm球质量比为50%∶30%∶20%)与钢球(ϕ20 mm)为磨矿介质,与钢球磨矿介质相比,磨矿技术效率提高了16.65个百分点,比能耗降低13.80%,噪音值降低2.8 d B,磁选效率提高9.65个百分点。二段细磨采用纳米陶瓷球部分替换钢球,可减轻过粉碎,提高磨矿技术效率和铁矿物的解离度,优化磁选指标。

鞍山地区微细粒贫磁铁矿石磁选工艺研究

鞍山地区许东沟和哑巴岭采区的铁矿石铁品位为29.50%,铁矿物主要为磁铁矿,主要脉石为石英。为高效开发利用该矿石,在采用X荧光分析、化学成分分析、铁物相检测和扫描电子显微镜分析矿石性质基础上,进行了湿式粗粒中磁预选—阶段磨矿、阶段弱磁选—淘洗机精选条件试验和扩大连选试验。结果表明:①-2.5 mm高压辊磨产品经过筒式磁选机中磁预选,粗精矿铁品位为40.20%、铁回收率为89.76%;②预选粗精矿经过两阶段磨矿(一、二段磨矿细度分别为-0.074 mm占75%和-0.045 mm占90%)、三阶段弱磁选和一段淘洗机精选,最终获得产率35.73%、铁品位67.08%、铁回收率81.24%的铁精矿,尾矿铁品位为8.61%,研究结果可作为该矿石开发利用依据。

某铜矿伴生金银回收的试验研究

江西某铜矿伴生金银含量分别为0.10 g/t、3.45 g/t,具有一定的综合利用价值。研究结果表明,在捕收剂为丁铵黑药,磨矿细度-0.074 mm占75%,浮选时间为5 min的条件下,对Cu、Au、Ag的综合回收指标较好。在条件试验的基础上进行了闭路试验,获得了Cu、Au、Ag品位分别为8.57%、1.63 g/t、83.6 g/t的铜精矿,相对于原矿回收率分别为4.93%、5.03%、4.64%。