硫酸镍铵复盐结晶法分离回收铜电解液中的镍（英文）

研究采用硫酸镍铵复盐结晶从铜电解液中分离回收镍的方法。研究发现,在相同温度的溶液中,硫酸铜的溶解度小于硫酸镍的溶解度,而硫酸铜铵的溶解度大于硫酸镍铵的溶解度。因此,加入(NH₄)₂SO₄可使铜电解液中的镍选择性结晶析出。按(NH₄)₂SO₄/NiSO₄摩尔比≤0.8加入(NH₄)₂SO₄,在-15℃冷冻结晶10 h,可使其中的镍以Ni(NH₄)₂(SO₄)₂·6H₂O的形式结晶析出。将所得结晶物热解,再将热解产物加水溶解,最后将溶解液浓缩结晶得到合格的NiSO₄·6H₂O产品。复盐结晶法是一种清洁环保、经济高效的从铜电解液中分离回收镍的方法。     

Effect of electrolyte depletion on the characteristics of the anodic plasma electrolytic nitriding of a VT22 titanium alloy

Changes in the saturation capacity of an aqueous electrolyte containing ammonium chloride and ammonia during the nitriding of a VT22 two-phase titanium alloy are studied. Changes in the electrolyte composition are associated with the evaporation of water, ammonia, and ammonium chloride decomposition products and the emission of ions from the boiling solution into the envelope under the action of an electric field. It is found that the thickness of the layer exhibiting high hardness (up to 460 HV), which reaches 20 μm in the case of the treatment in a fresh electrolyte, decreases by 40% in a solution used for 5 h. It is shown that the electrolyte lifetime can be increased due to the vapors and gases from the envelope returning to the electrolyte. The use of an electrolytic cell with the possibility of the vapors and gases leaving the electrolyte during the treatment returning back to it makes it possible to maintain the saturation capacity of the electrolyte within 5 h of operation and ensuring the formation of approximately the same layer as the one formed in a fresh electrolyte. It is found that the electric conductivity of the solution and the gas–vapor envelope increases with electrolyte depletion due to the predominant loss of the dielectric components.     

Preparation of single-phase ammonium dimolybdate by combination process

A novel method for the preparation of single-phase ammonium dimolybdate with industrial ammonium molybdate was studied.Various influential factors were evaluated in the paper,including reaction temperature,reaction time,initial molybdenum concentration,initial NH3/Mo molar ratio,and stirring speed.Under the optimum experimental conditions,the crystallization rate of product is 85.23％.The X-ray diffraction (XRD) analysis and chemical analysis show that the product is single-phase ammonium dimolybdate,and no impurity phases exist.The scanning electronic microscope (SEM) image reveals uniform particle size,good particle dispersion,and no agglomeration between particles.Meanwhile,the final pH value of acidification was investigated.The total molybdenum recovery can reach up to 99.40％,and the main phases of acidification product are the same as those of raw material with the final pH value of 1.5.This determines that the acidification product can be used as a raw material to produce single-phase ammonium dimolybdate.     

Corrosion of hot-dip-galvanised steel and zinc alloy-coated steel in ammonia and ammonium chloride

There are many potential causes of corrosion in animal buildings. Animals exhale large quantities of moisture into the air creating high relative humidity in the building if the moisture is not properly vented. High humidity increases the potential for condensation. In addition, ammonia may be found in large quantities in animal buildings. Ammonia is released from manure and urine. In addition, ammonium chloride is used as a nitrogen source in fertilisers. In this study, the atmospheric corrosion of hot-dip-galvanised steel and zinc alloy-coated steel such as zinc–aluminium and zinc–aluminium–magnesium has been studied in atmospheres containing different levels of ammonia. Investigations have also been conducted at different levels of ammonium chloride. The results are discussed in view of the mechanisms of corrosion of zinc and zinc alloy-coated steel in ammonia and ammonium chloride-containing environments.     

改性J422焊条电弧焊碳钢接头在亚硫酸铵溶液中的耐蚀性

针对亚硫酸铵介质中碳钢焊接接头腐蚀严重的实际,采用向普通碳钢焊条J422药皮中添加镍的方法,以三电极电化学研究方法和金相组织分析法研究了焊缝不同含镍量情况下碳钢焊接接头在亚硫酸铵溶液中的腐蚀行为.结果表明,镍元素的加入使得焊缝组织晶粒细化,针状铁素体减少;同时提高了碳钢焊接接头的自腐蚀电位;焊接接头在亚硫酸铵溶液中的极化率增大,自腐蚀电流减小;其中焊缝Ni元素含量为1.2%的焊接接头腐蚀速率最小.     

Direct nickel electrodeposition on magnesium alloy in pyrophosphate electrolyte

Direct nickel electrodeposition on a Mg alloy, AZ31B, was conducted in an electrolyte containing potassium pyrophosphate, nickel sulfate, potassium fluoride and ammonium hydroxide. The effect of potassium fluoride on the Mg alloy in a pyrophosphate nickel electrolyte was investigated using polarization and EIS methods. The chemical state of the Mg alloy was also analyzed by XPS. The effect of added ammonium hydroxide on electroplated nickel layer was observed by FE-SEM. A magnesium fluoride film, which was formed by added potassium fluoride, inhibits the dissolution of the Mg alloy in the electrolyte. The current efficiency was increased and surface cracks on the nickel layer were also eliminated by adding ammonium hydroxide to the electrolyte. The direct nickel electrodeposited Mg alloy showed significantly improved corrosion resistance compared to the uncoated Mg alloy. A successful and protective electrodeposited nickel layer was formed on the Mg alloy in pyrophosphate nickel electrolyte due to the addition of potassium fluoride and ammonium hydroxide.     

铝电解过程对电解铝液的净化作用探讨

本文对比分析了采用长流程、短流程工艺熔铸铝合金过程中,氢和氧化铝夹杂的形成过程。分析了铝电解工艺过程对电解铝液的自净化作用。电解铝的工作介质为冰晶石熔体,对氧化铝有良好的溶解性能,通过溶解电解液-铝液界面上的氧化铝达到脱氢除杂的效果。电解铝液中存在的微量稀土具有固氢排杂的作用。现代大型铝电解槽电流强度达到350kA,存在于铝液中的不导电、不被铝液润湿的氧化铝夹杂,在强烈电磁场的耦合作用下聚集沉降在电解槽的边部、角部或铝液漩涡的交界处。     

Influence of long-term operation of electrolytes on the composition,morphology, and mechanical properties of surfaces produced at deposition of Co-W coatings from citrate solutions

A comprehensive study has been conducted on the composition of a citrate electrolyte used to produce Co-W coatings that contains (mol/l) the following: cobalt sulphate (0.2), sodium tungstate (0,2), citric acid, sodium citrate, boric acid (pH 6.5) at both its storage and long electrolysis (up to Q ≈ 17 A hour/l). The influence of the degree of operation, the electrolyte agitation, and current volume density on variations in its composition, as well as on the coating composition and microhardness is shown. The observed variations arise from the Podlaha-Landolt induced codeposition mechanism as applied to the used electrolyte composition and electrolysis modes.     

席夫碱基季铵盐型双子表面活性剂对碱性锌电极电化学性能的影响

目的选择席夫碱基季铵盐型双子表面活性剂作为电解液添加剂,改善碱性锌电极的电化学性能,提高其耐蚀性能。方法通过电化学分析法,如失重法、塔菲尔极化曲线法、交流阻抗法等分析研究三种席夫碱基季铵盐型双子表面活性剂(D1、D2、D3)对锌电极电化学性能的影响,利用X射线光电子能谱(XPS)和扫描电子显微镜(SEM)研究在6 mol/L KOH电解液(饱和ZnO)浸泡48 h后,锌片表面的成分和形貌。结果室温下,缓蚀率随席夫碱基季铵盐型表面活性剂浓度升高而增加,当浓度进一步增大,缓蚀率变化不大。三种席夫碱基表面活性剂中,D3缓蚀能力最强,缓蚀率最高达95.67%,抑制腐蚀的效果顺序为:D3D2D1,属于抑制阳极型缓蚀剂。结论 D1、D2、D3作为碱性锌电极的电解液添加剂,可以有效减缓锌电极的腐蚀、变形、钝化及枝晶形成的能力,改善了碱性锌电极的电化学性能,D1、D2、D3适合作为碱性锌电池的缓蚀添加剂。     

Enrichment of alloying elements in anodized magnesium alloys

The possibility of enrichment of alloying elements in magnesium alloys as a consequence of growth of an anodic film has been investigated for sputtering-deposited Mg-0.4 at.% W and Mg-1.0 at.% W alloys. The alloys were anodized at 10 mA cm⁻² to various voltages, up to 150 V, in 3 M ammonium hydroxide/0.05 M ammonium phosphate electrolyte at 293 K. The alloys revealed enrichments of tungsten to at least 1.7×10¹⁵ and 2.9×10¹⁵ W atoms cm⁻² for the Mg-0.4 at.% W and Mg-1.0 at.% W alloys respectively. The enrichment behaviour appears to be similar to that in dilute aluminium alloys, which occurs for alloying elements with oxides having Gibbs free energies per equivalent for formation exceeding that for formation of alumina.     

Behavior of ammonium adsorption by clay mineral halloysite

Ammonium pollution becomes severe during mining of ionic rare earth-ores in southern China. As one of the main clay minerals in soils of ionic rare earth mines, halloysite plays an important role in ammonium adsorption. In this study, the saturated adsorption capacity, factors affecting adsorption and adsorption kinetics of halloysite for ammonium were investigated. The results indicated that the ammonium adsorption of halloysite was saturated with 1.66 mg/g at 303 K, pH of 5.6 and initial ammonium concentration of 600 mg/L (about half of the actual initial in-situ leaching concentration). When the initial concentration of –N, pH values and temperatures (288 K to 313 K) increased, the ammonium adsorption capacity of halloysite increased. The ammonium isothermal adsorption of halloysite matched the Langmuir and Freundlich isotherms. The adsorption process of ionic rare earth mining soils for ammonium was favorable. And the adsorption process followed closely the pseudo-second kinetic equation.     

Comparing thermal and mechanochemical decomposition of ammonium paratungstate (APT)

In this research, the possibility of mechanochemical decomposition of ammonium paratungstate (APT) has been studied, and compared with thermal decomposition method. For this purpose, APT powders were milled using a planetary ball mill up to 36 h and under air atmosphere. For thermal decomposition, APT powders were heated for 30 minutes at 300 and 450 °C in air atmosphere. X-ray diffraction (XRD), differential scanning calorimeter (DSC), and thermo gravimetric analyzer (TGA) were used to study the decomposition progress, and products. The XRD results showed that APT completely decomposed to WO₃ by thermal decomposition, while the final product of mechanochemical decomposition was WO₃ (H₂O)_0.5. According to DSC and TGA results, during thermal decomposition, ammonia and water released in four steps, and leaved WO₃. By mechanochemical decomposition crystal water and ammonia liberated from APT structure, but structural water of APT remained. In both methods, an X-ray amorphous phase was the intermediate product of APT decomposition.     

Anodic plasma electrolytic nitrocarburising of VT22 titanium alloy in carbamide and ammonium chloride electrolyte

The structure of alpha- and beta-titanium alloy VT22, its microhardness, surface roughness, wear and corrosion resistance after anodic plasma electrolytic nitrocarburising in an electrolyte containing carbamide and ammonium chloride were investigated. An X-ray diffractometer and a scanning electron microscope were used to characterize the phase composition and structure of the modified surface. Tribological properties of the treated titanium alloy were evaluated using a ball-on-disc tribometer under lubricated testing conditions. The effect of processing temperature on corrosion resistance of the plasma electrolytic nitrocarburising samples was examined by means of potentiodynamic polarization in Ringer’s solution. It was shown that the anodic nitrocarburising provides saturation of the titanium alloy with oxygen, nitrogen and carbon and the formation of TiO₂ with a rutile structure and a nitrogen/carbon solid solution in titanium. The anodic plasma electrolytic nitrocarburising at all treatment temperatures diminishes the wear rate of the titanium alloy samples and the surface roughness. Friction coefficient of treated samples can be reduced by 4.7 times. The anodic nitrocarburising results in an enhanced corrosion resistance since the corrosion potential increases by an order of magnitude.     

Notes on the Production of Adherent Copper Deposits on Austenitic Chromium-Nickel Steels

The presence of a film upon iron after treatment in the Marshall smoothing solution has been demonstrated. The formation of the film after withdrawal of the specimen from the solution appears to be independent of the oxalate ion. The evidence indicates that the film consists of a very thin but tenacious and continuous layer of oxide. By reducing the film cathodically in an ammonium chloride electrolyte and observing the quantity of electricity involved, the thickness of the film has been estimated and found to be of the order of 60 Angstrom units (i.e. 16 molecules, assuming the film to be anhydrous Fe₂O₃).     

Oxidative electropolymerization of pyrrole from neat monomer solution

Oxidative electrochemical polymerization of pyrrole at gold, indium doped tin oxide on glass, and stainless steel type 304 was accomplished from neat monomer solution containing only supporting electrolyte (0.05–0.3 M n-tetrabutyl ammonium perchlorate, n-tetrabutyl ammonium hexafluorophosphate, or n-tetrabutyl ammonium tetrafluoroborate) by multiple scan cyclic voltammetry. The results presented demonstrate that thick (>1–14 μm), stable, highly conductive (up to 0.6 S/cm) polypyrrole films can be readily prepared on a wide range of electrode substrates using this simple electrochemical method.     

Effect of ageing in the electrolyte and water on porous anodic films on zirconium

The present study demonstrates the significant influence of ageing in the formation electrolyte on the morphology and composition of anodic films grown on zirconium in 0.35 M ammonium fluoride in glycerol. Ageing after anodizing, by immersion in the electrolyte for 1 h, is shown to promote a transition from a porous to a nanotubular morphology, due to the dissolution of the fluoride-rich intratubular material in which the nanotubes are embedded. The morphological change is accompanied by a significant loss of zirconium and fluorine from the film. In contrast, ageing in deionized water has little influence on the films.     

纳米碳酸铝铵的制备

以硫酸铝铵与碳酸氢铵为原料,在一定的搅拌条件下,沉淀反应制备碳酸铝铵。通过X-RAD、SEM对沉淀产物进行物相组成及微观结构分析,结果表明,搅拌条件,有机表面活性剂及陈化时间都对AACH粒度和微观形貌影响较大,并对AACH的生长机理进行了初步探讨。     

The Effect of Iron Precursors in an Electrolyte on the Formation,Composition, and Magnetic Properties of Oxide Coatings on Titanium

The effect of iron sulfate and citrate addition into the base alkaline phosphate-borate-tungstate electrolyte on the peculiarities of plasma-electrolytic formation of coatings on titanium, their thickness, surface morphology, composition, and magnetic characteristics has been investigated. In the first electrolyte, dispersed particles of iron hydroxides and hydroxo salts are formed, whereas the second one comprises a true solution. Numerous Fe-containing crystallites of a size of ~50 nm united into agglomerates have been found in the suspension electrolyte with FeSO₄. Such coatings manifest ferromagnetic properties: coercive force Hc of the samples is 62 and 148 Oe at 300 and 2 K, respectively. In pores of the coatings obtained in the electrolyte with FeC₆H₅O₇ (true solution), the presence of crystallites is less clearly expressed, while crystallites themselves are larger and molten to a higher degree. At room temperature, such coatings are paramagnetic; at 2 K, they manifest ferromagnetic behavior with the Н _с value of up to 200 Oe. The available data enable one to associate ferromagnetic properties of the formed coatings with metals concentrated in pores.     

Extraction of cobalt from laterite ores by citric acid in presence of ammonium bifluoride

Citric acid was used to selectively extract cobalt from limonite-type laterite ores in the presence of ammonium bifluoride. The results show that ammonium bifluoride enhances the leaching of cobalt by citric acid, and 84.5% cobalt is extracted from a laterite ore containing 0.13% Co when leached at ambient temperature for 2 h with 30 g/L citric acid and 10 g/L ammonium bifluoride. Pyrolusite is reduced by citric acid during leaching, cobalt intergrown with which is liberated and subsequently chelated by the citric acid. The extraction of cobalt is enhanced in the presence of ammonium bifluoride because the matrix of silicate minerals is destroyed by ammonium bifluoride and the adsorbed cobalt is subsequently liberated.     

低品位氧化铜矿氨-硫酸铵体系过硫酸铵氧化浸出

以过硫酸铵为氧化剂,研究低品位氧化铜矿在氨-硫酸铵体系氧化浸出工艺。讨论氨/铵离子摩尔比、总氨浓度,氨、硫酸铵和过硫酸铵的浓度,反应温度,液固比,反应时间和搅拌速度等操作条件对铜浸出的影响。结果表明:在92.8%的矿样粒径小于0.045 mm,氨、硫酸铵和过硫酸铵浓度分别为2.4、1.8和0.100 mol/L,浸出时间为90 min,温度为30℃,液固比(mL/g)为5:1,搅拌速度为500 r/min时的优化条件下,低品位铜矿的铜浸出率达87.7%。