Separation and Precipitation of Nickel from Acidic Sulfate Leaching Solution of Molybdenum-Nickel Black Shale by Potassium Nickel Sulfate Hexahydrate Crystallization

Nickel was separated and precipitated with potassium nickel sulfate hexahydrate [K₂Ni(SO₄)₂·6H₂O] from acidic sulfate solution, a leach solution from molybdenum-nickel black shale. The effects of the potassium sulfate (K₂SO₄) concentration, crystallization temperature, solution pH, and crystallization time on nickel(II) recovery and iron(III) precipitation were investigated, revealing that nickel and iron were separated effectively. The optimum parameters were K₂SO₄ concentration of 200 g/L, crystallization temperature of 10°C, solution pH of 0.5, and crystallization time of 24 h. Under these conditions, 97.6% nickel(II) was recovered as K₂Ni(SO₄)₂·6H₂O crystals while only 2.0% of the total iron(III) was precipitated. After recrystallization, 98.4% pure K₂Ni(SO₄)₂·6H₂O crystals were obtained in the solids. The mother liquor was purified by hydrolysis-precipitation followed by cooling, and more than 99.0% K₂SO₄ could be crystallized. A process flowsheet was developed to separate iron(III) and nickel(II) from acidic-sulfate solution.     

Ida~（2-）-H_2O体系浸出低品位氧化锌矿

采用Ida2--H2O体系（亚氨二乙酸盐水溶液）处理高碱性脉石型低品位氧化锌矿,考察浸出时间、液固比、配体总浓度、温度及pH值对矿物中主金属Zn及杂质元素Ca、Mg、Cu、Ni、Fe、Pb、Cd的溶出影响。结果表明：在弱碱性Ida2--H2O体系中,Ca、Mg、Fe不会被大量溶出,有价金属Cu、Ni、Pb、Cd可部分随主金属Zn溶出而进入浸出液;在浸出时间4h、液固比5：1、配体总浓度0.9mol/L、温度70℃、pH8的优化条件下,锌浸出率为76.6%。     

Leaching of iron concentrate separated from kiln slag in zinc hydrometallurgy with hydrochloric acid and its mechanism

It is taken as a novel prospective process to treat iron concentrate from hydrometallurgical zinc kiln slag for comprehensive utilization of valuable metals by a hydrochloric acid leaching-spray pyrolysis method. The leaching mechanism of different valuable metals was studied. The results revealed that the leaching rates of Ag, Pb, Cu, Fe, As and Zn were 99.91%, 99.25%, 95.12%, 90.15%, 87.58% and 58.15%, respectively with 6 mol/L HCl and L/S ratio of 10:1 at 60 °C for 120 min. The action of SiO₂ in leaching solution was also studied. The results showed that the precipitation and settlement of SiO₂(amorphous) adsorbed part of metal ions in solution, which greatly inhibited the leaching of Cu, Fe, As and Zn, so it is crucial to control the precipitation of amorphous SiO₂.     

通过选择性浸出、结晶和沉积回收废重整催化剂中的镍和铝

研究和优化不同工艺条件下硫酸(3.0~5.5 mol/L)浸出回收Ni和Al的工艺。浸出实验表明,在H₂SO₄浓度5.5 mol/L、反应时间4 h、固液比0.2 g/mL、温度358 K、粒径<100μm、搅拌速度200~250 r/min、催化剂用量5.0 g的条件下,可提取98.5%的NiO和40.7%的Al₂O₃。浸出液中的Al用1.4 mol/L KOH选择性结晶分离,Ni用0.3 mol/L H₂C₂O₄选择性沉淀分离。此法可回收约97.9%的NiO,纯度达98.3%;约25%的Al₂O₃以明矾(纯度为99%)形式回收,14.7%的Al₂O₃以Al-K-C₂O₄-SO₄盐的形式回收。研究结果表明,硫酸是一种合适的选择性浸出溶剂,而且可以从硫酸盐溶液中选择性结晶出明矾。TG-DTA/DTG和XRD表征研究证明,本工艺可以有效地提取和回收镍和铝。     

Selective recovery of cobalt,nickel and lithium from sulfate leachate of cathode scrap of Li-ion batteries using liquid-liquid extraction

This paper focuses on the extractive separation and selective recovery of cobalt, nickel and lithium from the sulfate leachate of cathode scrap generated during manufacture of lithium ion batteries (LIBs). The conditions for extraction, scrubbing and stripping of cobalt from nickel and lithium are optimized with an aqueous feed containing 25.1 g·dm^?3 cobalt, 2.54 g·dm^?3 nickel and 6.2 g·dm^?3 lithium using Na-PC-88A. 99.8% Co is extracted with 60% Na-0.56 mol·dm^?3 PC-88A in two counter-current stages at an O/A phase ratio of 3/1 and an equilibrium pH of 4.5. The “crowding effect” shown for the first time provides effective scrubbing of impurities (Ni and Li) with 2.0 g·dm^?3 CoSO₄ solution. The McCabe-Thiele diagram predicts the scrubbing of 99.9% Ni and 99.9% Li at an equilibrium pH of 4.75 and O/A of 2/1 in two stages. High purity (99.9%) cobalt sulfate along with Ni and Li from the leach liquor of cathode scrap is recovered by solvent extraction. The proposed process ensures complete recycling of the waste of the manufacturing process of LIBs.     

Cyclic metallurgical process for extracting V and Cr from vanadium slag: Part II. Separation and recovery of Cr from vanadium precipitated solution

Cyclic metallurgical process for separation and recovery of Cr from vanadium precipitated solution by precipitation with PbCO₃ and leaching with Na₂CO₃ was investigated. The concentration of Cr residue in the solution decreases from 2.360 to 0.001 g/L by adding PbCO₃ into vanadium precipitated solution according to Pb/Cr molar ratio of 2.5, adjusting the pH to 3.0 and stirring for 180 min at 30 °C. Then, the precipitates were leached with hot Na₂CO₃ solution to obtain leaching solution containing Na₂CrO₄ and leaching residue containing PbCO₃. The leaching efficiency of Cr reaches 96.43% by adding the precipitates into 0.5 mol/L Na₂CO₃ solution with the mass ratio of liquid to solid (L/S) of 10:1 mL/g and stirring for 60 min under pH 9.5 at 70 °C. After filtration, leaching residue is reused in Cr precipitation and leaching solution is used to circularly leach the Cr precipitates until Na₂CrO₄ approaches the saturation. Finally, the product of Na₂CrO₄·4H₂O is obtained by evaporation and crystallization of leaching solution.     

Solubility of hemimorphite in ammonium sulfate solution at 25 °C

The solubility of natural hemimorphite in ammonium sulfate solution was measured by isothermal solution method at 25 °C and the dissolved residue of hemimorphite was investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) methods. The results show that zinc and silica in hemimorphite simultaneously dissolve in ammonium sulfate solution. The solubility of zinc in solution increases rapidly from 4.5381 mmol/kg in 0.5469 mol/kg ammonium sulfate solution to 11.5083 mmol/kg in 3.7038 mol/kg ammonium sulfate solution. The solubility of silica in solution increases slowly from 2.5509 mmol/kg in 0.5469 mol/kg ammonium sulfate solution to 7.2891 mmol/kg in 3.7038 mol/kg ammonium sulfate solution. The dissolved residue is the characteristic of hemimorphite Zn₄Si₂O₇(OH)₂·H₂O based on the results of the XRD, SEM and FTIR. Thus, no phase transition occurs in the dissolution process of hemimorphite in ammonium sulfate solution.     

Effect of electrodeposition conditions on the composition, microstructure, and corrosion resistance of Zn-Ni alloy coatings

The formation, composition, and structure of electrodeposited zinc-nickel alloys were investigated. It has been shown that both anomalous and normal codeposition of zinc and nickel can be realized by changing the bath composition and deposition conditions, with the nickel content in the resultant deposit being varied in a wide range (from 2 to 90 at.%). It has been also shown that the ammonical diphosphate electrolyte allows deposition of Zn-Ni coatings with a homogeneous phase structure (Ni₅Zn₂₁ and Ni₃Zn₂₂ intermetallides, a solid solution of Zn in Ni, or a solid solution of Ni in Ni₅Zn₂₁), whereas the weak acid chloride electrolyte produces two-phase coatings consisting of Ni₅Zn₂₁ with the admixture of polycrystalline Zn or Ni. The Zn-Ni coating with a nickel content of 19 at.% consisting of Ni₅Zn₂₁ intermetallic phase exhibits the highest corrosion resistance.     

Dissolution mechanism of solid nickel in liquid zinc saturated with Fe

The dissolution behavior of solid nickel in static liquid zinc saturated with Fe at 723 K was studied. The results show that when immersing solid Ni in liquid Zn saturated with Fe, the intermetallic compound layers consisted of γ and δ phases are formed on nickel substrate, which is the same as that in liquid pure zinc. However, some F2 particles are formed in the liquid near the solid/liquid interface. These Г2 particles can easily heterogeneously nucleate on （particles and grow fast. The dissolution process is governed by diffusion of nickel atom across a concentration boundary layer in liquid Zn saturated with Fe, and is different from a mixed control mechanism of nickel in liquid pure zinc. The participation of Г2 particles makes the dissolution of solid Ni in the liquid accelerated.     

An electrochemical study on the influence of sodium molybdate on electrodeposition process and phase composition of ternary Zn–Ni–Mo alloy coatings

Ternary Zn–Ni–Mo alloy coatings were deposited from a citrate-sulphate bath at pH 5.7 containing different amounts of sodium molybdate. The content of molybdenum in the coatings (from 0.3 to 5.2?at.-%) can be easily controlled by increasing sodium molybdate concentration in the plating bath from 0.0025 to 0.05?mol?dm^??3, which results also in deposition of smoother deposits. An increase in molybdate concentration leads to the shift of reduction potentials towards more negative values and to the decrease in current efficiency of deposition process. XRD analyses and anodic linear sweep voltammetry (ALSV) measurements demonstrated that at least two phases are formed in the Zn–Ni–Mo alloy: a hexagonal zinc phase or solid solution of nickel in zinc and Ni₅Zn₂₁ intermetallic compound. Furthermore, the XRD analyses revealed a third phase, which could be assigned to the oxidised species of molybdenum or other alloying metals.     

Extraction of arsenic from arsenic-containing cobalt and nickel slag and preparation of arsenic-bearing compounds

The arsenic extraction from the arsenic-containing cobalt and nickel slag, which came from the purification process of zinc sulfate solution in a zinc smelting factory, was investigated. The alkaline leaching method was proposed according to the mode of occurrence of arsenic in the slag and its amphoteric characteristic. The leaching experiments were conducted in the alkaline aqueous medium, with bubbling of oxygen into the solution, and the optimal conditions for leaching arsenic were determined. The results showed that the extraction rate of arsenic was maximized at 99.10% under the optimal conditions of temperature 140 °C, NaOH concentration 150 g/L, oxygen partial pressure 0.5 MPa, and a liquid-to-solid ratio 5:1. Based on the solubilities of As₂O₅, ZnO and PbO in NaOH solution at 25 °C, a method for the separation of As in the form of sodium arsenate salt from the arsenic-rich leachate via cooling crystallization was established, and the reaction medium could be fully recycled. The crystallization rate was confirmed to reach 88.9% (calculated on the basis of Na₃AsO₄) upon a direct cooling of the hot leachate down to room temperature. On the basis of redox potentials, the sodium arsenate solution could be further reduced by sulfur dioxide (SO₂) gas to arsenite, at a reduction yield of 92% under the suitable conditions. Arsenic trioxide with regular octahedron shape could be prepared successfully from the reduced solution, and further recycled to the purification process to purify the zinc sulfate solution. Also, sodium arsenite solution obtained after the reduction of arsenate could be directly used to purify the zinc sulfate solution. Therefore, the technical scheme of alkaline leaching with pressured oxygen, cooling crystallization, arsenate reduction by SO₂ gas, and arsenic trioxide preparation, provides an attractive approach to realize the resource utilization of arsenic-containing cobalt and nickel slag.     

Hydrometallurgical recovery of zinc from industrial hot dipping top ash

Top ash from hot-dip galvanizing plant was investigated as a source of secondary zinc to be returned to galvanizing bath. The waste material contained 63% Zn as metallic, oxide and hydroxychloride phases. It was leached in H₂SO₄ solutions (20% and 25%) at various bath loadings (100−300 g/L). Leaching behaviors of zinc, manganese, iron and chloride ions were investigated. A few strategies of iron elimination from leaching liquors were examined. Flocculant addition was harmful for subsequent filtration of iron precipitates due to increased viscosity of solution, while a combination of zinc oxide and calcium carbonate for rising pH resulted in the formation of dense suspension unenforceable to separate from zinc sulphate solution. Zinc electrowinning was carried out at different pH (from −0.5 to 2.8) using a range of current densities (3−10 A/dm²). Optimal conditions for pure metal recovery were: leaching in 20% H₂SO₄ solution at zinc ash content 100−150 g/L, Fe₂O₃·xH₂O precipitation using H₂O₂ and CaCO₃, zinc electrowinning at pH of 0.1−1.0 at 3−6 A/dm². Correlations between pH and free H₂SO₄ concentration in electrolyte solutions were also discussed. pH−acid concentration dependence for zinc electrolyte was between experimental and calculated curves for pure H₂SO₄ solutions, while the curve was shifted towards lower pH if ferric ions were in the solution.     

Hydrometallurgical process for recovery of Zn,Pb, Ga and Ge from Zn refinery residues

Zn, Pb, Ga and Ge were separated and recovered from zinc refinery residues by stepwise leaching. In the first stage, by leaching with H₂SO₄ media, more than 90% of Zn and 99% of Ga were dissolved, leaving 92% of Ge in the leaching residue. In the second stage, by leaching with HCl media, approximately 99% of Pb and less than 2% of Ge were selectively dissolved. Finally, the remaining 90% of Ge was extracted in 1 mol/L NaOH solution by destroying the correlation between SiO₂ and Ge. XRD pattern of the leaching residue demonstrated that ZnSO₄·H₂O, PbSO₄ and SiO₂ were removed sequentially through the stepwise leaching. The proposed process achieved high recoveries of Zn, Pb, Ga and Ge, thus presenting a potential industrial application.     

镀液组成对碱性体系Zn-Ni合金镀层性能的影响

目的 发现最优工艺条件,了解Zn-Ni电沉积机理。方法 通过场发射电镜分析、能谱分析以及电化学分析等方法,研究以一种胺羧多官能团配体为Ni²⁺络合剂的碱性锌酸盐电解液体系中,锌/镍离子物质的量之比与锌镍离子总浓度对镀层的光泽度、镍含量、耐蚀性、表观质量和微观结构的影响。结果 锌/镍离子物质的量之比增加会使得镀层镍含量降低,最后稳定在15%~19%,镀层微观结构由晶粒细致平滑型转化为粗大疏松型。物质的量之比为1.9时,镀层的腐蚀电流最小。锌镍离子总浓度增加会使得镀层镍含量缓慢减小,镀层微观结构由晶粒细致疏松型转化为细致紧密型,最后又转变为粗大疏松型,镀层的腐蚀电流先减小后急剧增大,即镀层的耐蚀性先增加后急剧降低。结论 在锌/镍离子物质的量之比为1.9、锌镍离子总浓度为0.12 mol/L时,所得镀层的综合性能最好。镀层锌/镍含量变化趋势符合Brenner吸附膜理论。     

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。     

Thermodynamic and experimental studies on removal of calcium and sulfate ions from recycling water of complex sulfide flotation operations

A chemical method for removing calcium sulfate saturated solutions (0.016 mol/L CaSO₄) using barium chloride (BaCl₂·2H₂O) and sodium phosphate (Na₃PO₄) was experimentally studied. The main interest is to remove these ions from the solution through the precipitation of two solid species: sulfate (SO₄²⁻) as barite (BaSO₄), and calcium (Ca²⁺) as hydroxyapatite (Ca₅(PO₄)₃OH). Additionally, a solid/liquid separation method (i.e., flotation) was explored, using oleic acid and dodecylamine as collectors. The results show that, the chemical treatment of saturated solutions at 60 °C, pH 11.5 and using 3.9 g/L BaCl₂·2H₂O and 1.6 g/L Na₃PO₄, promotes the precipitation of barium sulfate and calcium-deficient hydroxyapatite (Ca_10–x(HPO₄)_x(PO₄)_6–x(OH)_2–x), with residual concentrations of calcium and sulfate below 0.10 and 5 mg/L, respectively. The residual calcium concentration increases to 28 mg/L when using the same amount of reactants, at temperature and pH values below those quoted. The highest flotation recovery of hydroxyapatite with oleic acid at pH 9.5 was about 80%, while that of barite floated with dodecylamine at pH 6.5 was about 90%.     

Nickel hydroxide precipitation from aqueous sulfate media

Hydrometallurgical processing of laterite ores constitutes a major industrial and R&D activity in extractive metallurgy. In some of the process flowsheets, nickel hydroxide precipitation is incorporated. For these operations, the optimization of nickel hydroxide precipitation is important to assure efficiency and product quality. The main objective of this investigation was to study and improve the precipitation characteristics of Ni(OH)₂ in a sulfate system using supersaturation controlled precipitation. For more information, contact George P. Demopoulos, McGill University, Department of Mining, Metals and Materials Engineering, M.H. Wong Building, 3610 University, Montreal, Quebec, H4L 3Y9, Canada; (514) 398-4755, ext. 0266; fax (514) 398-4492; e-mail george@minmet.lan.mcgill.ca.     

Preparation and electrochemical performance of nano-scale Ni(OH)2 doped with zinc

Nano-scale Ni(OH)₂ doped with Zn was prepared by precipitation transformation method and characterized by XRD and TEM. The electrochemical performance was investigated by cyclic voltammetry (CV) and constant current technology. The measurement results indicate that the lattice parameters of nano-scale Ni(OH)₂ are changed and the agglomeration of particles becomes obvious with the increased Zn-doped content. Compared with un-doped one, the discharge specific capacities of nano-scale Ni(OH)₂ doped with 10% Zn are enhanced by 8% and 6%, respectively, at the discharge rate of 0.2C and 3C. After 110 cycles, the discharge specific capacity of the sample doped with 10% zinc is still above 85% of its initial capacity discharged at 0.2C. Therefore, a suitable Zn-doped content is beneficial to improving the discharge performance of nano-scale Ni(OH)₂.     

Calorimetric and magnetic determination of the interfacial enthalpy and heat of mixing in Ag(Ni) alloys

A new method for the determination of the interfacial enthalpy between unlike phases is presented. A differential scanning calorimeter was used to measure the heat released during precipitation of a superparamagnetic phase from a supersaturated solid solution. The volume distribution of the precipitated phase was determined by maximum entropy modeling of the magnetization, measured to ultra-high fields, as a linear superposition of Langevin functions. Transmission electron microscopy was used to determine the aspect ratios of the precipitates, which were combined with the volume distributions to calculate the total interfacial area in each specimen. The saturation magnetization was used to determine the total amount of the precipitated phase in each sample. The changes in enthalpy, interfacial area, and amount precipitated were used in a thermodynamic and kinetic model to calculate the interfacial enthalpy and heat of mixing. This method was applied to Ag–(5–10) at.% Ni alloys, produced in thin-film form by electron-beam co-evaporation. The average interfacial enthalpy between Ag and Ni, and the heat of mixing were found to be, respectively, 779±76 mJ/m² and 3.59±0.03 kJ/mol for the average alloy composition of 6.89 at.% Ni.     

CeO2对铝合金表面激光增材制造组织及耐蚀性影响

利用激光增材制造技术,在6063Al基体表面制备了添加不同含量CeO₂的Ni60合金层,并通过金相显微镜、XRD、SEM和电化学腐蚀测试仪等设备进行了分析和测试,研究稀土CeO₂对6063Al表面激光增材制造镍基合金层与基体结合界面处的组织结构及耐腐蚀性能的影响。结果表明,在表面形貌上,4%~5% CeO₂的合金层形貌最好,CeO₂含量低于3%时难以获得表面良好的合金层,CeO₂含量在5%~10%时,合金层表面气孔、脱落等缺陷较少;在截面形貌上,合金层中CeO₂含量在0%~2%时易出现裂纹,含量在5%~10%时主要缺陷为气孔,4% CeO₂+Ni60合金层中无明显气孔和裂纹,具有相对较好的截面形貌;添加4% CeO₂可以改善Ni60合金层的组织结构,促进合金层的晶粒细化和组织分布均匀;添加不同含量CeO₂可以改善铝合金表面Ni60合金层的组织形貌,较佳的稀土添加量是4% CeO₂;在1mol/L H₂SO₄中,CeO₂ Ni60合金层的耐腐蚀性能是Ni60合金层的4.25倍;在3.5% NaCl溶液中,CeO₂ Ni60合金层耐腐蚀性能是Ni60合金层的1.4倍;在1mol/L NaOH溶液中,CeO₂ Ni60合金层的耐腐蚀性是Ni60合金层的1.43倍。