Research on new beneficiation process of low-grade magnesite using vertical roller mill

We investigated whether the vertical roller mill can be efficiently used in the beneficiation of low-grade magnesite and whether it can improve upon the separation indices achieved by the ball mill.We conducted experiments involving the reverse flotation and positive flotation of low-grade magnesite to determine the optimum process parameters,and then performed closed-circuit beneficiation experiments using the vertical roller mill and ball mill.The results show that the optimum process parameters for the vertical roller mill are as follows:a grinding fineness of 81.6wt%of particles less than 0.074 mm,a dodecyl amine(DDA)dosage in magnesite reverse flotation of 100 g·t?1,and dosages of Na2CO3,(NaPO3)6,and NaOL in the positive flotation section of 1000,100,and 1000 g·t?1,respectively.Compared with the ball mill,the use of the vertical roller mill in the beneficiation of low-grade magnesite resulted in a 1.28%increase in the concentrate grade of MgO and a 5.88%increase in the recovery of MgO.The results of our causation mechanism analysis show that a higher specific surface area and greater surface roughness are the main reasons for the better flotation performance of particles ground by the vertical roller mill in the beneficiation of lowgrade magnesite.

Recent process developments in beneficiation and metallurgy of rare earths:A review

Rare earth elements(REEs)are irreplaceable materials supporting low-carbon technology and equip-ment,and their commercial demand and strategic position are becoming increasingly prominent.With the continuous depletion of rare earth(RE)resources,developing high-efficiency beneficiation and eco-friendly metallurgical processes has attracted widespread attention.This paper reviews the major minerals exploited for RE production and their deposits,as well as the beneficiation and metallurgical processes of RE minerals.Bastnaesite,monazite,mixed RE ores,and ion-adsorption clays are the main raw materials in the world to date.RE-bearing ores(except ion-adsorption minerals)are generally beneficiated by flotation,gravity and magnetic separation techniques.The mainstream metallurgical processes for bastnaesite,monazite and mixed RE concentrates are oxidation roasting-HCl leaching,caustic soda decomposition and high-temperature concentrated sulfuric acid roasting,respectively.Ion-adsorption clays are directly processed by in situ leaching-precipitation/solvent extraction.To achieve the sustainable development of RE resources,it is essential to further explore innovative techniques to achievecomprehensive utilization and cleaner production.

Deformation behaviors and processing maps of CNTs/Al alloy composite fabricated by flake powder metallurgy

Deformation behaviors of CNTs/Al alloy composite fabricated by the method of flake powder metallurgy were investigated by hot compression tests, which were performed in the temperature range of 300?550 °C and strain rate range of 0.001? 10 s?1 with Gleeble?3500 thermal simulator system. Processing maps of the CNTs/Al alloy at different strains were calculated to study the optimum processing domain. Microstructures before and after hot compressions were characterized by electron backscattered diffraction (EBSD) method. Stress?strain curves indicate that the flow stress increases with the increase of strain rate and the decrease of temperature. The processing maps of the CNTs/Al alloy at different strains show that the optimum processing domain is 500?550 °C, 10 s?1 for hot working. EBSD analysis demonstrates that fully dynamic recrystallization occurs in the optimum processing domain (high strainrate 10 s?1), whereas the main soften mechanism is dynamic recovery at low strain rate (0.001 s?1).

Hot deformation and processing maps of Al_2O_3/Al composites fabricated by flake powder metallurgy

The deformation behaviors of Al2O3/Al composites were investigated by compressive tests conducted at temperature of 300-450 °C and strain rates of 0.001-1.0 s-1 with Gleeble-1500 D thermal simulator system. The results show that the flow stress increases with increasing strain rate and decreasing temperature. The hyperbolic sine constitutive equation can describe the flow stress behavior of Al2O3/Al composites, and the deformation activation energy and constitutive equations were calculated. The processing maps of Al2O3/Al-2 μm and Al2O3/Al-1 μm composites at strain of 0.6 were obtained and the optimum processing domains are in ranges of 300-330 °C, 0.007-0.03 s-1 and 335-360 °C, 0.015-0.06 s-1 for hot working, respectively. The instability zones of flow behavior can also be recognized by the maps.

Damping capacity of high strength-damping aluminum alloys prepared by rapid solidification and powder metallurgy process

Two kinds of high strength-damping aluminum alloys （LZ7） were fabricated by rapid solidification and powder metallurgy （RS-PM） process. One material was extruded to profile aluminum directly and the other was extruded to bar and then rolled to sheet. The damping capacity over a temperature range of 25-300 ℃was studied with damping mechanical thermal analyzer （DMTA） and the microstructures were investigated by optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The experimental results show that the damping capacity increases with the test temperature elevating. Internal friction value of rolled sheet aluminum is up to 11.5×10^-2 and that of profile aluminum is as high as 6.0×10^-2 and 7.5×10^-2 at 300 ℃, respectively. Microstructure analysis shows the shape of precipitation phase of rolled alloy is more regular and the distribution is more homogeneous than that of profile alloy. Meanwhile, the interface between particulate and matrix of rolled sheet alloy is looser than that of profile alloy. Maybe the differences at interface can explain why damping capacity of rolled sheet alloy is higher than that of profile alloys at high temperature （above 120 ℃）.

Modeling, Optimization, and Control of Solution Purification Process in Zinc Hydrometallurgy

The solution purification process is an essential step in zinc hydrometallurgy. The performance of solution purification directly affects the normal functioning and economical benefits of zinc hydrometallurgy. This paper summarizes the authors' recent work on the modeling, optimization, and control of solution purification process. The online measurable property of the oxidation reduction potential(ORP) and the multiple reactors, multiple running statuses characteristic of the solution purification process are extensively utilized in this research. The absence of reliable online equipment for detecting the impurity ion concentration is circumvented by introducing the oxidationreduction potential into the kinetic model. A steady-state multiple reactors gradient optimization, unsteady-state operationalpattern adjustment strategy, and a process evaluation strategy based on the oxidation-reduction potential are proposed. The effectiveness of the proposed research is demonstrated by its industrial experiment.

Review on the study of metallurgical process engineering

After nearly one hundred years of research, metallurgy(metallurgical science and engineering) has gradually become a system with three levels of knowledge:(1) micro metallurgy at the atomic/molecular scale,(2) process metallurgy at the procedure/device, and(3) macrodynamic metallurgy at the full process/process group. Macro-dynamic metallurgy development must eliminate the concept of an "isolated system" and establish concepts of "flow," "process network," and "operating program" to study the "structure–function–efficiency" in the macrodynamic operation of metallurgical manufacturing processes. It means considering "flow" as the ontology and observing dynamic change by"flow" to solve the green and intelligent potential of metallurgical enterprises. Metallurgical process engineering is integrated metallurgy, toplevel designed metallurgy, macro-dynamic operated metallurgy, and engineering science level metallurgy. Metallurgical process engineering is a cross-level, comprehensive, and integrated study of the macro-dynamic operation of manufacturing processes. Metallurgical process engineering studies the physical nature and constitutive characteristics of the dynamic operation of steel manufacturing process, as well as the analysis-optimization of the set of procedure functions, coordination-optimization of the set of procedures' relations, and reconstruction-optimization of the set of procedures in the manufacturing process. The study establishes rules for the macro operation of the manufacturing process, as well as dynamic and precise objectives of engineering design and production operation.

Relationship between process mineralogical characterization and beneficiability of low-grade laterite nickel ore

Process mineralogy of low-grade laterite nickel ore in Indonesia was systematically characterized and the beneficiation process of mineral components such as limonite,serpentine and chromite was studied on the basis of process mineralogy.The results show that the low-grade laterite nickel ore is a typical weathering sedimentary metamorphic oxidized ore,with the main valuable elements of Ni,Co and Cr and the main mineral components of limonite,serpentine,chromite,etc.There is no independent carrier mineral of Ni and Co in the raw ore,and the occurrence states of Ni and Co are relatively dispersed.For the limonite in laterite nickel mine,the nickel bearing magnetite concentrate with nickel grade of 1.98%and recovery rate of 88.42%can be obtained by reduction roasting magnetic separation process.For the serpentine in laterite nickel mine,the cobalt bearing concentrate with Co grade of 0.17%and recovery rate of 23.17%can be obtained by positive and reverse flotation process.A chromium concentrate containing 35.17%Cr_(2)O_(3) and a recovery of 33.42%can be obtained by using the combined process of coarse and fine classification and gravity and magnetic.

Processing TiAl-Based Alloy by Elemental Powder Metallurgy

TiAI-based alloys with various compositions (including Ti-48Al, Ti-47Al-2Cr-2Nb, Ti-47Al-2Cr-2Nb-0.2B and Ti-47Al-3Cr, in mole fraction) had been prepared by elemental powder metallurgy (EPM). The results have shown that the density of the prepared Ti-48AI alloy increases with increasing hot pressing temperature up to 1300℃. The Ti-48AI alloy microstructure mainly consisted of island-like Ti3Al phase and TiAl matrix at hot pressing temperature below 1300℃, however, coarse α2/γ lamellar colonies and γ grains appeared at 1400℃. It has also indicated that the additions of elemental Cr and B can refine the alloy microstructure. The main microstructural inhomogeneity in EPM TiAI-based alloys was the island-like α2 phase or the aggregate of α2/γ lamellar colony, and such island-like structure will be inherited during subsequent heat treatment in (α＋γ) field. Only after heat treatment in a field would this structure be eliminated. The mechanical properties of EPM TiAl-based alloys with various compositions were tested, and the effect of alloy elements on the mechanical properties was closely related to that of alloy elements on the alloy microstructures. Based on the above results, TiAI-based alloy exhaust valves were fabricated by elemental powder metallurgy and diffusion joining. The automobile engine test had demonstrated that the performance of the manufactured valves was very promising for engine service.

Negative-pressure pneumatic separator:a new solution for hard-coal beneficiation

Hard coal is an important source of energy worldwide.Owing to the imperfections of excavation technology,most run-of-mine coals must be processed before they can be utilised as fuel.In this study,tests on the dry separation process were performed with numerous different raw hard coal and coal waste material samples,using a newly designed and constructed negative-pressure pneumatic separator(NPPS).The experiments revealed the effects of the feed-material properties and material processing conditions.These experiments were preceded by additional tests for evaluating the influence of each device operating parameter on the process,to determine the optimal method of supplying the feed material.The calorific value of the processed materials was improved by 5%–40%,while a minimal output yield of products(60%–70%)was maintained.The trials indicated that in coal material processing,the developed NPPS can be used for not only raw coal enrichment but also coal recovery from materials stored at coal-waste dumps.The main advantages of the device are its mobility,low material processing cost,and lack of water consumption during operation.

Synthesis of Al-SrB_6 composite via powder metallurgy processing

The potential of powder metallurgy processing for the manufacture of Al?SrB6 composites was explored. Al4Sr particles fractured extensively during the ball milling of Al?15Sr/Al?4B powder mixtures. There was no interaction between the Al4Sr and AlB2 compounds across the section of the aluminium grains in the as-milled state. SrB6 formed, when the ball milled powder blends were subsequently annealed at sufficiently high temperatures. Ball milling for 1 h was sufficient for SrB6 to become the major constituent in powder blends annealed at 700 °C while it took 2 h of ball milling for powder blends annealed at 600 °C. Higher annealing temperatures and longer ball milling time encouraged the formation of the SrB6 compound while the latter made a great impact on the microstructural features of the Al?SrB6 composite. The SrB6 compound particles were much smaller and more uniformly distributed across the aluminium matrix grains in powder grains ball milled for 2 h before the annealing treatments at 600 °C and 700 °C.

GREY DISPLACEMENT INPUT－OUTPUT MODELS OF MINERAL PROCESSING－METALLURGY SYSTEM

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影响工业还原罐内铝热法炼镁过程还原效率的因素

在工业还原罐内进行铝热还原炼镁试验,分析影响还原效率的因素。结果表明:结晶镁的氧化和燃烧以及原料混合不均匀是导致还原效率降低的主要原因;原料混合不均匀导致贫铝区和MgO剩余,促进生成12CaO·7Al_(2)O_(3)和CaO·Al_(2)O_(3);对于富铝区域,MgO和CaO同时被还原,生成Mg_(2)Ca相。辐射传热和化学反应吸热是影响还原速率的关键因素;提高加热温度能够迅速提高球团层的温度,进而使球团获得足够的反应速度;此外,球团中含镁量越高,需要的反应时间越长。

Flow behavior and processing map of PM Ti-47Al-2Cr-0.2Mo alloy

The flow stress features of PM Ti-47Al-2Cr-0.2Mo alloy were studied by isothermal compression in the temperature range from 1000 to 1150 °C with strain rates of 0.001-1 s-1 on Gleeble-1500 thermo-simulation machine.The results show that the deformation temperature and strain rate have obvious effects on the flow characteristic,and the flow stress increases with increasing strain rate and decreasing temperature.The processing maps under different deformation conditions were established.The processing maps of this alloy are sensitive to strains.The processing map at the strain of 0.5 exhibits two suitable deformation domains of 1000-1050 °C at 0.001-0.05 s-1 and 1050-1125 °C at 0.01-0.1 s-1.The optimum parameters for hot working of the alloy are deformation temperature of 1000 °C and strain rate of 0.001 s-1 according to the processing map and microstructure at true strain of 0.5.

刚果(金)地区超大型铜钴矿资源选冶工艺研究与实践

非洲铜钴矿床主要分布于赞比亚—刚果(金)铜矿带,具有储量大、品位高、矿石性质复杂等特点,这些铜钴矿石按氧化程度与脉石矿物的特性差异,可分为原生硫化铜钴矿石、低钙混合铜钴矿石、高钙混合铜钴矿石、低钙氧化铜钴矿石和高钙氧化铜钴矿石,指出应根据矿石氧化率、脉石矿物的类型(对于碱性脉石矿物必须关注Ca、Mg含量)、矿石中铜钴矿物的赋存状态、金属回收率及加工成本等因素确定其开发利用工艺,并列举了这5类代表性矿石的生产工艺及生产指标。概括说,除低钙氧化铜钴矿石宜采用直接浸出工艺外,其余各类矿石均宜采用选冶联合工艺,但浮选工艺各有特色。研究与生产实践表明,针对不同性质的矿石选用不同的选冶工艺,是获得理想分选指标的关键。

湖北省恩施某光伏玻璃用石英砂提纯制备实验

这是一篇关于矿物加工工程领域的文章。光伏玻璃用石英砂是支撑新能源行业发展必不可少的原料之一,其供应安全保障事关我国双碳政策的成功实施。本文以湖北省恩施州某大型石英砂矿为研究对象,开展了工艺矿物学与除杂提纯实验研究,发现该石英砂矿的主要杂质为斜长石、云母、褐铁矿和金红石,采用了“分级-重选-磁选-酸浸”选矿工艺流程,最终获得符合粒度要求(0.106~0.500 mm)的石英砂精矿产率为67.61%,其SiO_(2)含量由97.36%提高至99.79%,有害元素Fe_(2)O_(3)、TiO_(2)与Al_(2)O_(3)含量则分别降低至75、80、630 g/t,石英精矿产品各项指标达到了光伏玻璃用硅质原料的生产要求,实现了该石英砂矿的有效利用。

湘潭海泡石矿物学特征及提纯产物加工试验研究

为实现该海泡石矿资源的高效开发利用,采用化学多元素分析、粒度分析、光学显微镜分析、扫描电子显微镜分析等方法,进行了详细的矿物特性研究,并探究了海泡石选矿与应用建议。结果表明,随着矿物粒度的降低,海泡石含量增加。方解石和石英呈颗粒状,海泡石呈束状集合体分布,且与其他矿物结合紧密。针对矿石性质,确定了“筛分-化学分散-高速分散-分离”的原则工艺流程,选用最优参数:pH值为9,分散剂为0.8 g/L的焦磷酸钠,高速分散机分散20 min,转速为2 000 r/min;并且对矿石干燥和磨矿进行了条件试验,得出最优结果:选用喷雾干燥,最大的进料功率80 W,固液比1∶10,进口温度为250℃,从纤维形貌和分散情况来看,使用气流磨可以获得较好的海泡石产品。进而获得了完整的沉积型海泡石提纯工艺流程。综上,本研究对湘潭海泡石的矿物学特征进行了深入分析,并通过提纯产物加工试验,成功地提取出了高纯度的海泡石产品。这为湘潭海泡石的进一步开发利用提供了重要的科学依据,同时也为相关领域的生产应用提供了新的技术支持。

湖北某低品位铌钽矿选矿工艺试验研究

针对湖北某花岗伟晶岩型铌钽矿进行了选矿试验研究,确定了重磁粗选—粗精矿浮选—酸化焙烧、浸出—萃取、反萃—磁选尾矿浮选分离长石、石英的联合选矿工艺流程。试验获得的铌钽精矿产品中Nb2O5品位53.96%、Ta2O5品位21.33%,Nb2O5回收率63.48%、Ta2O5回收率53.05%。其中,在重磁粗选阶段通过粗磨分级—摇床工艺,考察了磨矿细度和磁场强度对铌钽预富集的影响,试验得到产率9.47%,可工业应用的一级绢云母产品;针对强磁精矿进行浮选,考察了捕收剂种类对浮选效果的影响,在苯乙烯膦酸与正辛醇用量比4︰1、药剂用量1500g/t的条件下进行两次精选,获得Nb2O5品位为10.578%、Ta2O5品位为4.753%的浮选精矿;在纯硫酸体系下对浮选精矿产品进行了酸化焙烧浸出试验研究,铌钽分解液在低酸条件下采用甲基异丁基甲酮(MIBK)萃取钽、在高酸条件下采用磷酸三丁酯(TBP)萃取铌,萃取液均采用纯水进行反萃,反萃后的铌、钽液用氨水沉淀后焙烧,得到高纯Nb2O5和Ta2O5产品;对磁选尾矿进行浮选获得可工业利用的长石精矿和石英精矿。试验对绝大部分有用矿物实现了富集,高效富集铌钽的同时实现了伴生矿物的综合回收。

三门峡变质石英砂岩工艺矿物学和可选性研究

以三门峡地区变质石英砂岩为对象,进行了矿石的工艺矿物学和可选性试验研究。结果表明,该矿石为变余砂状结构,致密块状构造,矿石的SiO_(2)含量(质量分数,下同)为97.60%,杂质元素主要是铝、铁、钾、钙、镁、磷等。目的矿物为石英,磨圆较好,次生加大发育(硅质胶结),杂质矿物有长石、金红石、电气石和赤褐铁矿等。石英粒径分布在0.1~0.4 mm,+0.1 mm石英的累计分布率达到94.89%;对该矿石试样采用“磨矿-分级-磁选”工艺提纯后,制备石英砂可满足JC/T 529-1994平板玻璃用I类优等品指标要求,采用“磨矿-分级-磁选-浮选”工艺后,石英砂可满足QB/T 2196-1996仪器玻璃用石英砂产品指标要求,采用“磨矿-分级-磁选-浮选-酸浸”工艺后,SiO_(2)含量提升至99.91%,杂质元素Fe_(2)O_(3)为0.0086%,Al_(2)O_(3)为0.045%,石英砂可满足JC/T 2314-2015光伏玻璃用硅质原料指标要求。

莫桑比克楠普拉省滨海型锆钛矿的选矿试验研究

莫桑比克楠普拉省锆钛砂矿资源丰富,连续十年为我国提供稳定的锆钛矿资源,现已成为我国最重要的锆钛砂矿资源供应地。本研究采用化学分析、XRF分析、物相分析、MLA(矿物定量自动检测系统)和SEM(扫描电镜)等测试手段对锆钛矿进行了工艺矿物学研究,查明了莫桑比克锆钛矿化学元素、矿物组成和产出特征及解离度等特征,在工艺矿物学研究的基础上,采用重选、磁选和电选联合工艺对原矿进行分选,有效回收了钛铁矿、锆英石金红石和独居石,四种产品相对混合粗精矿产率分别为77.48%、8.58%、3.90%和0.50%,钛精矿中TiO2含量为52.39%、回收率为79.02%,锆精矿中ZrO2含量为60.20%~65.02%(平均64.19%)、回收率为77.71%,金红石精矿中TiO2含量为85.10%~90.32%(平均88.98%)、回收率为4.65%,独居石精矿中REO含量为60.20%、回收率为78.67%。该试验有效回收了锆英石和钛铁矿,同时综合回收利用了金红石和独居石,为莫桑比克锆钛资源高效综合回收利用提供技术支撑和实践经验。