Production of High Purity Metals: A Review on Zone Refining Process

Purification is a primary application of zone melting, in which the improvement of efficiency, production yield and minimum achievable impurity level are always the research focus due to the increasing demand for high purity metals. This paper has systematically outlined the whole development of related research on zone refining of metals including basic theories, variants of zone refining, parametric optimization, numerical models, and high purity analytical methods. The collection of this information could be of good value to improve the refining efficiency and the production of high purity metals by zone refining.

Corrosion resistance evaluation of highly dispersed MgO–MgAl2O4–ZrO2 composite and analysis of its corrosion mechanism: A chromium-free refractory for RH refining kilns

The corrosion resistance behavior of a highly dispersed MgO-MgAl2O4-ZrO2 composite refractory material is examined by testing with high-basicity and low-basicity RH(Ruhrstahl-Hereaeus)slags.The composite material exhibits greater resistance to the RH slags than the traditional MgO-Cr2O3 composite,MgO-ZrO2 composite,and MgO-MgAl2O4-ZrO2 composite.On the basis of the microstructural analysis and mechanisms calculations,the corrosion resistance behavior of the MgO-MgAl2O4-ZrO2 composite is attributable to its highly dispersed structure,which helps protect the high activity of ZrO2.When in contact with the slag,ZrO2 reacts with CaO to form the stable phase CaZrO3,which protects MgAl2O4 against corrosion,thereby enhancing the corrosion resistance of the composite.

Preparation and Application of Polymer Silicate Phosphate Ferric Sulfate Used in High-Viscosity Oil Refining Wastewater Treatment

A new kind of flocculants, named Polymer Silicate Phosphate Ferric Sulfate(PSPFS), was synthesized by ferrous sulfate used as the main material and activated silicic acid as additive. In this paper, High-Viscosity Oil Refining wastewater from Liaohe Petrochemical Corporation was the treatment object. Overall, the in-fluencing factors and synthesis technology conditions of PSPFS were determined by experiments. First of all, the conditions of influencing factors were showed as follows: the mass percent concentration of ferrous sulfate 55%,concentration of sodium silicate 15% , the molar ratio of ferrous sulfate and hydrogen peroxide 1.2:1, oxidation temperature 40 degree Celsius, oxidation time 4 hours, polymerization temperature 60 de-gree Celsius and polymerization time 2 hours. Secondly, the optimal ratios of components were determined by uniform design method. The molar ratio of Fe/Si is 5.0:1, Fe/H2SO4 is 3.2:1, and Fe/P is 18.0:1. At last, the optimal experimental condition was determined as follows: the dosing quantity 200mg/L, pH value 5.5~9, temperature 25~45℃, stirring time 2 min, and standing time 3 min, according to the result of floc-culation experiments with PSPFS. Besides, the result of the comparative experiments showed that the effi-ciency of PSPFS was much better than the reference flocculants.

Toward the development of Mg alloys with simultaneously improved strength and ductility by refining grain size via the deformation process

Magnesium(Mg) alloys, as the lightest metal engineering materials, have broad application prospects.However, the strength and ductility of traditional Mg alloys are still relativity low and difficult to improve simultaneously.Refining grain size via the deformation process based on the grain boundary strengthening and the transition of deformation mechanisms is one of the feasible strategies to prepare Mg alloys with high strength and high ductility.In this review, the effects of grain size on the strength and ductility of Mg alloys are summarized, and fine-grained Mg alloys with high strength and high ductility developed by various severe plastic deformation technologies and improved traditional deformation technologies are introduced.Although some achievements have been made, the effects of grain size on various Mg alloys are rarely discussed systematically and some key mechanisms are unclear or lack direct microscopic evidence.This review can be used as a reference for further development of high-performance fine-grained Mg alloys.

Study on non-metallic inclusions in Al killed high strength alloy steel refined by high basicity and high Al_2O_3 content slag

Laboratory and industrial studies were carried out to investigate non-metallic inclusions in high strength alloy steel refined by high basicity and high Al_2O_3 slag.It was found that the steel/slag reaction time largely affected non-metallic inclusions.With the reaction time increased from 30 min to 90 min in laboratory study,MgO-Al_2O_3 spinels were gradually changed into CaO-MgO-Al_2O_3 system inclusions surrounded by softer CaO-Al_2O_3 surface layers.By using high basicity slag which contained as much as 41%Al_2O_3 in the laboratory study,ratio of low melting temperature CaO-MgO-Al_2O_3 system inclusions was remarkably increased to above 80%.In the industrial experiment,during the secondary refining,the inclusions changed in order of 'Al_2O_3→MgO-Al_2O_3→CaO-MgO-Al_2O_3'.Through the LF and RH refining,most inclusions could be transferred to lower melting temperature CaO-Al_2O_3 and CaO-MgO-Al_2O_3 system inclusions.

TAYLOR POLYNOMIAL STEPWISE REFINEMENTALGORITHM FOR LIE AND HIGH SYMMETRIES OF PARTIAL DIFFERENTIAL EQUATIONS

In this article, based on the Taylor expansions of generating functions and stepwise refinement procedure, authors suggest a algorithm for finding the Lie and high (generalized) symmetries of partial differential equations (PDEs). This algorithm transforms the problem having to solve over-determining PDEs commonly encountered and difficulty part in standard methods into one solving to algebraic equations to which one easy obtain solution. so, it reduces significantly the difficulties of the problem and raise computing efficiency. The whole procedure of the algorithm is carried out automatically by using any computer algebra system. In general, this algorithm can yields many more important symmetries for PDEs.

Identification of denatured and normal biological tissues based on compressed sensing and refined composite multi-scale fuzzy entropy during high intensity focused ultrasound treatment

In high intensity focused ultrasound(HIFU)treatment,it is crucial to accurately identify denatured and normal biological tissues.In this paper,a novel method based on compressed sensing(CS)and refined composite multi-scale fuzzy entropy(RCMFE)is proposed.First,CS is used to denoise the HIFU echo signals.Then the multi-scale fuzzy entropy(MFE)and RCMFE of the denoised HIFU echo signals are calculated.This study analyzed 90 cases of HIFU echo signals,including 45 cases in normal status and 45 cases in denatured status,and the results show that although both MFE and RCMFE can be used to identify denatured tissues,the intra-class distance of RCMFE on each scale factor is smaller than MFE,and the inter-class distance is larger than MFE.Compared with MFE,RCMFE can calculate the complexity of the signal more accurately and improve the stability,compactness,and separability.When RCMFE is selected as the characteristic parameter,the RCMFE difference between denatured and normal biological tissues is more evident than that of MFE,which helps doctors evaluate the treatment effect more accurately.When the scale factor is selected as 16,the best distinguishing effect can be obtained.

Performance comparison of AlTiC and AlTiB master alloys in grain refinement of commercial and high purity aluminum

For further knowledge about the refining performance of AlTiC master alloys, Al5.5Ti0.25C and Al6.5Ti0.5C master alloys containing high Ti and C content were prepared and used in grain refining experiments of 99.8% commercial pure aluminum(CPAl). Their performance was compared with two types of Al5Ti1B refiners whose performance was nowadays considered to be the best. These two types of master alloys show similar refining efficiency at the addition level of 0.2%. However, at the addition level of 0.5%, there still exists great performance difference between AlTiC and Al5TiB alloys in grain refinement of 99.98% and 99.995% high purity aluminum(HPAl). The growth of columnar grains is fully suppressed due to the refinement of AlTiC at the addition level of 0.5%. Also, at the same addition level, the grain refining experiments of Al3Ti0.15C and Al5Ti0.2C master alloys which have found initial commercial applications are conducted in the above-mentioned three types of pure aluminum. According to the experimental results, these two refiners of different compositions are both nonideal. The second phase particles extracted from each refiner were observed through TEM, while the nuclei of grains after grain refinement were observed through SEM. The results were analyzed through computation and comparison of the constitutional-supercooling parameter and the growth-restriction parameter whose values were determined by solute element in aluminum melt with different purity. Apparently, AlTiC master alloys with high content of Ti and C element have great refining potential.

Desulfurization ability of refining slag with medium basicity

The desulfurization ability of refining slag with relative lower basicity （B） and Al2O3 content （B = 3.5-5.0; 20wt%-25wt% Al2O3） was studied. Firstly, the component activities and sulfide capacity （Cs） of the slag were calculated. Then slag-metal equilibrium experiments were carried out to measure the equilibrium sulfur distribution （Ls）. Based on the laboratorial experiments, slag composition was optimized for a better desulfurization ability, which was verified by industrial trials in a steel plant. The obtained results indicated that an MgO-saturated CaO-Al2O3-SiO2-MgO system with the basicity of about 3.5-5.0 and the Al2O3 content in the range of 20wt%-25wt% has high activity of CaO （αCaO）, with no deterioration of Cs compared with conventional desulfurization slag. The measured Ls between high-strength low-alloyed （HSLA） steel and slag with a basicity of about 3.5 and an Al2O3 content of about 20wt% and between HSLA steel and slag with a basicity of about 5.0 and an Al2O3 content of about 25wt% is 350 and 275, respectively. The new slag with a basicity of about 3.5-5.0 and an Al2O3 content of about 20wt% has strong desulfurization ability. In particular, the key for high-efficiency desulfurization is to keep oxygen potential in the reaction system as low as possible, which was also verified by industrial trials.

Al、Ti、V和Cr促进高熵合金BCC相形成能力的研究

定量研究了Al、Ti、V和Cr促进CoFeMnNi基高熵合金形成BCC相的添加量,结合元素周期表分析了相关规律。使用真空熔炼炉炼制了CoFeMnNi基高熵合金,使用扫描电子显微镜、X射线衍射仪、显微硬度计分析了合金的组织结构和硬度。结果表明,CoFeMnNi合金为单一FCC相结构,Al、Ti、V和Cr四种元素单独添加到合金中出现BCC相的添加量分别是0.6、0.6、1和2 mol;促进BCC相形成能力的顺序是Al>Ti>V>Cr;对于元素周期表第4周期的过渡族元素,序号小于25的元素是BCC形成元素,序号越小越有利于在高熵合金中形成BCC相。当合金有BCC相形成时,合金的硬度升高;随BCC相的增加,硬度增加,合金脆性变大。合金含钛2 mol后,合金抗腐蚀能力提升明显,即使在王水腐蚀120 s仍然没有明显的腐蚀痕迹。

大国智造的“器”质:机器人驱动工业高质量发展的机理与效能

工业机器人是大国制造的新引擎,驱动着制造业智能化、高端化、绿色化发展。本文以工业机器人应用为出发点,以人员精简化、技能高级化、分工精细化、产业多样化为衔接点,以工业高质量发展战略目标为落脚点,阐释机器人驱动工业高质量发展的机理并评估效能。基准回归结果表明,机器人应用显著地促进了工业高质量发展。经内生性矫正和稳健性检验后发现,机器人应用产生的工业提质效应依然显著。机制检验结果显示,机器人应用正是通过促进人员精简化、技能高级化、分工精细化、产业多样化4重渠道,驱动了工业高质量发展。异质性分析结果进一步发现,机器人应用产生的工业提质效应在大城市、西部地区以及超老龄社会阶段更为强劲。研究结论为理解工业机器人何以赋能工业高质量发展提供了理论逻辑和经验证据,为加速迈向“中国智造”提出了新思路和新抓手。

东北三省“专精特新”企业研发创新对企业高质量发展的影响研究

在新经济时代,经济结构正在发生深刻的变革。传统产业面临挑战,而知识经济和创新驱动的产业则呈现出快速增长的势头。选取东北三省2015年第一季度至2022年第四季度的相关企业作为研究样本,并借助固定效应回归方法展开实证研究。研究结果显示:“专精特新”企业的研发创新能够正向促进企业高质量发展;国有企业属性能够发挥正向调节效应;在东北三省区域内,长春市“专精特新”企业研发创新更能够促进企业高质量发展。

企业高质量发展组态路径研究 ——以长江经济带专精特新“小巨人”企业为例

基于TOE理论框架,以长江经济带173家专精特新“小巨人”企业为样本,从技术、组织和环境三个层面提取了六个影响因素,使用fsQCA方法探讨其产生高与非高质量发展的组态路径。研究发现,单个要素并不构成实现专精特新“小巨人”企业高质量发展的必要条件,不同变量组合对企业实现高质量发展有显著影响。产生高质量发展的路径有3条,非高质量发展的路径有5条。其中高质量发展存在2种不同的实现方式,即三层面驱动型和规模-补贴驱动型。在实现专精特新“小巨人”企业高质量发展中,企业规模和政府补贴发挥着重要的作用。

专精特新企业与ESG表现的经济关系研究

在“十四五”规划以及国家双碳目标下,ESG和绿色发展成为国家重要议题,引导经济向高质量发展转型。本文将ESG理念融入投资决策和经营战略,能够提高企业竞争力,实现可持续发展。文章选取2019—2022年A股上市公司中的部分专精特新企业为样本,实证考察ESG体系对专精特新企业的影响。研究表明:总体上专精特新企业的企业价值与ESG表现呈现正向关系,但非国有企业与ESG表现呈反向关系,年龄较小、规模较小的企业同样呈反向关系,国有企业以及年龄较大、规模较大的企业与ESG表现之间并未呈现类似关系。最后,文章基于研究结论针对各类专精特新企业、金融机构及政府部门提出战略和政策建议,以供参考。

基于精细化管理的大型建筑企业工程项目管理研究

精细化管理是有别于常规管理的一种现代化管理模式,其主要目标在于实现资源的优化配置和最大限度地降低运营成本。在大型建筑企业工程项目管理实践中系统性运用精细化管控措施,可促进工程项目优质高效实施,提高项目盈利能力和企业运行效率,推动企业实现高质量发展。

基于黏性蒸馏-气相分离的冶金级粗碲提纯方法

开发一种基于黏性蒸馏-气相分离的高纯碲材料制备方法。通过调节冷凝器结构和冷凝温度,达到黏性蒸馏、控制碲优势冷凝区的目的,使挥发性差的物质留在残留物中,而硒在气相中与碲分离,实现冶金级粗碲的提纯。研究饱和蒸气压、碲分子平均自由程、不同冷凝位置的杂质分布特征以及冷凝物形貌。500 g级的实验结果表明,在5 Pa、773 K和90 min的最佳实验条件下,碲的直收率为83.40%,纯度高于99.9996%,碲优势冷凝区冷凝物中硒含量降低至2.76×10^(-4)%(质量分数)。

高速冲击载荷下AMPCO■18铜合金力学性能及本构模型

为了研究高速冲击载荷下AMPCO■18铜合金的力学性能及变形行为,采用霍普金森压杆技术对该铜合金进行应变速率分别为3409,3564,4285 s^(-1)的高速冲击实验.结果表明:随着冲击载荷的增大,应变速率增加,合金发生动态再结晶,晶粒得到显著细化,合金强度也随之提高;在应变速率为4285 s^(-1)的条件下,组织中未发现剪切带等特征,合金具备较强的抗冲击能力;AMPCO■18铜合金的Johnson-Cook模型预测值与实验值具有较高的一致性,相关系数R为0.94346,该模型可以较好地预测该合金在高速冲击过程中的流变行为.

钛合金随焊超声辅助TIG焊接接头组织及疲劳性能

基于TC4钛合金超声辅助TIG(U-TIG)与常规TIG焊接试验,采用金相显微镜、电子背散射衍射等测试技术分析了焊接接头的显微组织和织构,对焊接接头进行了显微硬度测试。之后,利用高频疲劳试验机,对2种试样开展应力比为-1下轴向加载疲劳测试。结果表明,常规TIG焊接接头初生β晶粒以联生结晶的方式跨越焊层生长,容易形成粗大弯曲的柱状晶,且α′相具有明显生长取向;而在U-TIG焊接工艺下,初生β柱状晶发生破碎,联生结晶趋势被遏制,针状α′马氏体尺寸得到细化,焊缝平均晶粒尺寸减小,晶粒尺寸梯度分布降低且平均显微硬度得到提升;施加超声后,晶粒沿散热方向生长得到遏制,其中α′马氏体在<0001>面取向强度显著降低;此外,应力比为-1下的疲劳极限由360 MPa增加至387 MPa,接头疲劳强度提升约7.5%。