Investigation on the Flotation Mechanism of Tantalite-Niobite Minerals with Styrenephosphonic Acid Collector

The flotability and mechanism of the composite tantalite-niobite minerals which have different content of the Ta, Nb. Fe,Mn with styrenephosphonic acid (SPA) as collector are investigated and discussed. Some important flotation parameters arefound as follows: SPA is a better collector for flotating niobite-tantalite mineral than other, the optimum pH value in pulp is lessthan 5, the flotability of those minerals varies with the different content of mineral composition, the flotabitity of the mineralswith higher Nb_2O_5 content is better than that with higher Ta_20_5 content. Here we emphasize that in wide range of pH in solu-tion the Fe, Mn on the mineral surfaces are the main active species for flotation of these minerals. In addition to this, some of re-search work by using Auger electron spectroscopy, infrared spectroscopy and ultraviolet spectroscopy for determining the surfaceconditions, pretreated by acid or not, has been done. The characteristics of adsorption of SPA on the mineral surfaces are exam-ined and discussed. It is indicated that the SPA interacts with Fe, Mn ions on mineral surfaces by the chemical bond force. But onthe whole outer layer of collector, which is non-uniform multilayer, it may be said that the adsorption of SPA on the mineral sur-face is both chemico-adsorption and physico-adsorption, but the chemico-adsorption is predominant.     

Studies in Bright Anodising by the Ammonium Bifluoride—Nitric Acid Process

The advantages of brightened and anodised aluminium for decorative trim are indicated; super-purity alloys are necessary to maintain the transparency of the anodic film. The especial advantage of a particular process using ammonium bifluoride and nitric acid is in avoiding much mechanical prepolishing. Experiments are described for the determination of satisfactory concentrations of nitric acid and ammonium bifluoride, the effect of lead and other additions, and of temperature. The stability, regeneration and control of the brightening solution are discussed. The post-brightening and anodising processes are briefly discussed together with the effect of the alloy composition on these processes and on the brightening process.     

Numerical Methods for Safeguarding the Performance of the Quenching Process

A new numerical technique for testing and evaluation of quenching media and quenching systems is outlined. The measured time-temperature samples as a result of cooling curve test are analyzed by the new software developed, in order to characterize quantitatively the quenchants. The method applied is based on Fourier analysis. Examples for evaluation and comparison of cooling performance of quenchants are presented the applicability of the computational technique.     

Mechanism and kinetics of discontinuous precipitation of the η phase in the 36NKhTYu alloy

A new mechanism of nucleation and growth of cells of the η phase in the deformed 36NKhTYu austenitic alloy has been found. The recrystallization nuclei are formed at the η-phase particles, which were precipitated according to the continuous mechanism. Simultaneously, they are nuclei of cells of discontinuous decomposition. Unlike the known growth mechanism, the η-phase cell grows in all directions until it collides with other cells. The Peterman-Hornbogen theory of discontinuous precipitation has been modified to describe the kinetics of the complex reaction of discontinuous precipitation of the η phase and recrystallization and also the kinetics of complex reaction of discontinuous coalescence of grains and phases. The theoretical dependences of the cell size on the aging time for these reactions are proportional to t ^1/3 and t ^1/4, respectively. A comparison of the theoretical and experimental results has been performed.     

Influence of the Discharge Voltage during Pulse-Plasma Process on the Durability of Edges coated with Superhard Coatings

FOR obtainment of different wear-resistant coatingsdeposited on cutting edges made of sintered carbides anumber of CVD and PVD methods are applied[1,2].Individual methods allow to obtain in differenttemperatures hard coatings with similar chemicalcomposition but with various morphology andexploitation properties.Differences among mentionedproperties of coatings mainly result from coatingstructure,adhesion to substrate,hardness and frictionalproperties of coating.Structure of coatings result…     

Influence of Process Variables on the Structure of Mechanically Alloyed Ti_3Al-base Intermetallics

During mechanical alloying variables such as the type of mill,milling intensity,milling time,milling at-mosphere and ball-to-powder weight ratio(BPR)affect the morphology and constitution of the product.The effect of milling time,milling atmosphere and BPR on the nature of the product formed in mechanical-ly alloyed pure Ti and blended elemental binary Ti-Al,and ternary Ti-AI-Nb alloy powders was described.Mechanical alloying of pure titanium results,after long milling times,in the formation of an fcc phase.Inthe binary alloy,a solid solution of aluminum in titanium,an amorphous phase,and a fcc phase form withincreasing milling time.The fcc phase,which is probably a result of TiN formation,occurs more rapidly inair or nitrogen than in an inert atmosphere.Formation of the B2 phase in the ternary alloys depends bothon alloy composition and the milling atmosphere,with 100％ formation in all atmospheres in Ti-25Al-25Nbbut not in Ti-24Al-11Nb,and an inert atmosphere favoring formation.The times required for the formationof the different phases decrease as the BPR increases;but their sequence is unaffected.Based on this infor-mation,“milling maps”which describe phase formation as a function of the BPR and milling time are con-structed.Contamination from the milling balls increased as the BPR was increased.     

Effect of the Application of a Mechanical Load on the Oxide-Layer Microstructure and on the Oxidation Mechanism of Ni–20Cr Foils

The effect of a tensile load on the oxidation kinetics and mechanism ofNi–20Cr was studied by comparison of the oxidation behavior ofNi–20Cr thin strips in air under classical conditions, i.e., withoutany applied mechanical load and under tensile creep, at temperatures between500 and 900°C. The study was performed mainly by comparisons of crosssections of oxidized samples observed by SEM. The results obtained clearlyindicate that applying a tensile load induces an increase in the oxidationrate, does not modify the oxide-film morphology, but promotes the formationof internal oxidation at low temperatures, 500–600°C, and notablyincreases the thickness of the intermediate NiCr₂O₄layer at 900°C. This is related to the acceleration of anionic diffusionwhen a tensile load is applied, due to the formation of fast-diffusion byshort-circuit paths.     

溴化法浸出提取金和银

讨论了溴化法提取金银的热力学条件，用高银金精矿进行溴化法浸出实验，结果表明，一次浸出焙烧矿，金的浸出率９８％，银的浸出率９４％，效果明显。     

硫脲法提金的优化工艺

提出扩散控制硫脲浸金速率表达式,求得浸出平衡时硫脲(Tu)和三价铁离子浓度之比(TF)与实验结果吻合很好。从试剂最佳匹配入手,以降低试剂总消耗及操作成本为目标而提出了优化工艺。用本工艺处理小秦岭某地区矿,在适当预处理条件下,不加氧化剂,3h内可使金浸出率达98％以上。主试剂消耗可降到常规硫脲法的1/3到1/5。     

盐酸浸出焙烧金精矿工艺研究

研究了盐酸浓度、反应温度、液固比和反应时间对盐酸浸出焙烧金精矿的影响,用正交试验优化工艺条件。单因素实验表明,盐酸浸出焙烧金精矿的浸出率与盐酸浓度、反应温度和反应时间呈正相关趋势,液固比为1.5:1时具有最大的金浸出率。正交试验表明,在所选择的因素水平范围内,盐酸浓度影响最为明显,反应温度和反应时间影响较大,液固比影响最小。在优化反应条件下(盐酸浓度8 mol/L、液固比1.5:1、90℃浸出90 min),金的浸出率达到95.53%。盐酸浸出后焙烧金精矿中大量赤铁矿被浸入溶液,释放包裹金的同时增加了Fe³⁺浓度,促进了金的浸出。     

高耐蚀性铬酸阳极氧化工艺研究

通过厚度、附着力、耐蚀性测试等研究了航空用铝合金的铬酸阳极氧化工艺.结果表明,不同铝合金成分对铬酸阳极氧化膜厚度影响很大,但各种合金的氧化膜厚均大于2 μm;2024-T3铝合金生成的铬酸阳极氧化膜层经重铬酸钾封闭处理可通过750 h的盐雾试验,且未封闭的氧化膜层与涂层具有优异的附着力;铬酸阳极氧化槽液中Cr3+的浓度...     

从锌浸出渣中回收银的方法

一般湿法炼锌厂所产出的锌浸出渣含有相当数量的银、锌及稀散金属。近２０年来，人们从这类残渣中回收银及人价金属的研究和生产方法归纳起来可分为３类；浮选富集，火法富集和直接浸出银。讨论了各种方法的基本原理，优点和缺点，以及研究方向。     

银阳极泥硝酸浸出液中铂和钯的还原富集

银阳极泥在硝酸浸出时,大部分铂和钯会进入溶液,最终返回熔炼系统,铂钯直收率因此偏低。研究了亚硫酸氢钠还原沉淀硝酸浸出脱银液中铂和钯的工艺条件。结果表明,还原剂用量、硝酸浓度、反应温度和时间均对铂和钯沉淀率有影响。在优化条件下,铂和钯的沉淀率分别可达到99.5%和99.7%,所得精矿中铂和钯含量分别为1.70%和13.59%。     

湿法磷酸中不锈钢腐蚀的电化学分析

试验以湿法磷酸为体系，以316L和904L不锈钢为研究对象，采用动电位扫描测试了不同杂质组成和温度对两种不锈钢的影响，并对两种材料不同电位下的Nyquist图谱进行了测试。试验从电化学特征参数致钝电流密度ic、维钝电流密度ip、膜的破裂电位Eb和自腐蚀电位Ecorr以及交流阻抗阻力对两种材料的耐蚀性差异进行了分析。     

高砷铅泥控制电位氯化浸出金银

考查高砷铅泥在盐酸介质控电氯化浸出过程中的若干因素（酸度、相对砷含量、液固比以及浸出电位等）。高砷铅泥在盐酸介质控电氯化过程中，金银的浸出损失会明明偏大，其损失量随砷与金（银）的含量比值的增加而增加；而浸出电位、液固比以及浸出液酸度过程也都是造成金（银）浸出损失的原因。     

生物法对提高酸性重金属废水回用率的探讨

针对铅锌冶炼行业酸性重金属废水处理系统目前常用的工艺及存在的主要问题,探讨了生物法对提高酸性重金属废水处理及回用率具有积极的意义。     

燃机旁路机构阀体装焊工艺方案研究

重型燃机旁路机构阀体主体尺寸大、结构刚性差、焊接量大。根据生产情况,不断改进和完善装焊工艺方案。通过采取增加阀体外圆加工余量、90°弧环拼焊等措施,保证了产品质量和生产周期,并力争工艺方案的最优化。