The effect of certain surfactants on the cementation of nickel from zinc sulphate solutions by suspended zinc particles in the presence of copper

The effect of surfactants nonylphenolpolyethylene glycol (D1), dinaphthylmethane-4,4′-disulphonic acid (D2) and polyethylene glycol with molecular weight 400 (D3) on both nickel-zinc dust cementation kinetics and the structure of obtained deposits was investigated. Experiments were carried out in the presence of copper to increase the low cementation rate of nickel. The reaction of nickel cementation was found not to follow first-order kinetics due to hydrogen evolution which takes place along with the cementation reaction. Two rate regions were observed. Hydrogen evolution in the presence of D1 is lower than with D2, D3 and without surfactants. D1 and D3 decrease but D2 has no effect on nickel cementation. The influence of D1 and D3 is higher at the beginning of the process. Higher temperature improves nickel cementation only in the initial period. The structure of cementation products depends on the temperature. Uniform layers of lamellar crystallites on the surface of zinc particles were observed at 65°C with and without surfactants. At 85°C the morphology changes to massive spheroid formations of lamellar crystallites. The presence of D1 and D3 decreases both the crystallite size and deposit porosity. The lowest porosity was found in the presence of D3. The inhibition effect of D1 on the hydrogen evolution contributes to decrease in zinc consumption during the cementation of nickel.     

The simultaneous electrowinning of manganese dioxide and zinc from purified neutral zinc sulphate at high current efficiencies

A process that enables electrolytic-grade manganese dioxide and zinc to be electrowon simultaneously at high anodic and cathodic current efficiencies from purified neutral leach liquor from a zinc plant is described. Experimental results that show the effects on the anodic and cathodic current efficiencies of temperature, anodic and cathodic current densities, initial sulphuric acid concentration, initial zinc-ion concentration, initial manganous-ion concentration, and addition of a polyelectrolyte smoothing agent are presented and discussed.     

用铜镉渣和锌电解废液生产硫酸锌

简要介绍了在湿法炼锌企业中,利用铜镉渣和锌电解废液为原料,生产硫酸锌,回收渣中Ｚｎ 、Ｃｄ、Ｃｕ 等有价金属,完成电解液开路排Ｍｇ 的生产工艺流程及其操作与控制,并对此工艺作了分析与讨论。生产实践证明,该工艺在湿法炼锌企业中有较好的实用价值。     

铜离子对硫酸锌溶液中钴返溶的影响及机理

本文研究了对湿法炼锌过程中钴的返溶的影响因素,对反应时间,氧化,锌粉粒度,Cu2 等因素进行了系统的研究.当锌粉量一定时,小颗粒锌粉有较高的初始置换速率,但是也更容易返溶.大颗粒锌粉置换速率慢,但是几乎不返溶.添加了铜离子,返溶明显,而没有添加铜离子的溶液,虽然除钴效果稍差,但是不会返溶或者返溶不明显.然而铜离子的存在对钴的返溶究竟起着何种作用还有待于进一步研究.在锌粉置换过程中,钴返溶的正确的反应为:Zn Co2 →Zn2 Co(s),Co(s) 2OH-→Co(OH)2 2e.     

The effect of dietary copper and zinc on cholesterol metabolism

The effects of different amounts of dietary zinc and copper on cholesterol metabolism in the rat were investigated. The levels of the minerals used were comparable to those likely to occur in a normal mixed North American diet. Although the different levels affected the serum, liver, and femur concentrations of the minerals, they had no effect on the levels of serum and liver, total, esterified or free cholesterol, or on high density lipoprotein cholesterol. It was concluded that dietary copper and zinc, at levels likely to occur in a normal mixed diet, are not significant factors in cholesterol metabolism.     

Solubility of lead and zinc compounds in ammoniacal ammonium sulphate solutions

The solubilities of lead sulphide, sulphate, chloride and oxide and zinc sulphide, sulphate and oxide in ammoniacal ammonium sulphate solutions have been determined. Solubility diagrams showing the effect of varying ammonia and ammonium sulphate concentrations are presented. The presence of high levels of zinc or copper is shown to reduce lead solubility to extremely low levels (0.1 (g/l Pb). Solutions containing lead were found to be unstable when removed from contact with the initial dissolving compound and a mechanism is postulated for the dissolution of lead compounds involving the production of a metastable intermediate complex.     

Reaction mechanism of cobalt cementation from high cobalt zinc sulphate solution by zinc dust

Abstract

The experiments in this paper were performed to research the mechanism of cobalt cementation from high cobalt zinc sulphate solution by zinc dust. The reduction potential of zinc during cementation was determined to investigate the morphology of products. Residues after the cementation process from zinc sulphate solution were analyzed by SEM and EPMA to investigate the morphology of products. Different temperature will cause different structure of particles. The reaction mechanism of cobalt removal by zinc dust is thought to be as follows: first, the Co2+ forms Co–Zn alloy with zinc particles, and the reaction reaches equilibrium quickly; second, the Co–Zn alloy continues reacting to Co with Co2+, which is the control process of the whole reaction.     

Effect of Mn ions on the electrodeposition of zinc from acidic sulphate solutions

The effect of Mn²⁺ ions on current efficiency (CE), deposit morphology and polarization behaviour during electrodeposition of zinc from acidic sulphate solutions was investigated. In the conditions studied, Mn²⁺ ions had no significant effect on CE over the concentration range of 1–10 g dm^− 3. However, a decrease in CE of more than 35% was obtained at 50 g dm^− 3. The cathodic polarization curves and the corresponding kinetics analysis demonstrated that this decrease in CE at higher concentrations of Mn²⁺ ions was due to the strong depolarizing effect of MnO₄⁻ ions and other oxidized products of manganese. Moreover, the kinetics analysis of anodic polarization suggested that the presence of Mn²⁺ ions catalyzed the oxygen evolution reaction. The addition of Mn²⁺ ions was also observed to change the surface morphology and deposit quality of the electrodeposited zinc, affecting the crystallographic orientation by significantly inhibiting the growth of (002) and (100) planes.     

The effect of aromatic and aliphatic amines on copper electrowinning from acidic sulphate electrolyte

Copper electrodeposition in the presence of various types of aromatic and aliphatic amines was studied. The effects of operating variables including organic additives concentrations and temperature on the limiting current were investigated by the potentio-dynamic polarization technique. The effects of amines on the surface tensions of the solutions were measured; the results showed that amines reduce solution surface tension. The adsorption of all inhibitors on copper cathode was found to obey Temkin, Flory-Huggin and kinetic adsorption isotherm. The calculated free energy of adsorption (ΔG_ads.) of inhibitor on copper surface indicated that the adsorption reactions were spontaneous (ΔG_ads. < 0). The thermodynamic activation parameters (E_a, ΔH*, ΔS* and ΔG*) were estimated and discussed. It was found that activation energy values for copper electrodeposition in the inhibited solutions were higher than that for the uninhibited solution. The high inhibitor efficiency was discussed in terms of the strong adsorption of inhibitor molecules on the copper surface.     

The serum zinc level in patients with tinnitus and the effect of zinc treatment

We measured the serum zinc level in patients with tinnitus and evaluated the effectiveness of zinc in the treatment of tinnitus. Blood zinc levels were measured in 121 patients with tinnitus. All patients were examined between 1995 and 1997 at the outpatient clinic of otorhinolaryngology St. Marianna University Toyoko Hospital. Forty-seven patients who had received any drug such as a calcium channel blocker and others or had been affected by any diseases were excluded and therefore 74 patients consisting of 46 females (62%) and 28 males (38%) were investigated. Twenty two healthy volunteers served as a control group. The mean age and standard deviations for the tinnitus group and the control group were 47.8 +/- 17.1 and 31.4 +/- 8.2 years, respectively. There was a significant decrease (p < 0.0001) in serum zinc levels in patients with tinnitus compared with the control group. Because there was a significant difference (p < 0.0001) in age distribution between tinnitus and control groups, patients were selected by their age in order to neglect the effect of aging. In this situation, a significant difference (p < 0.01) was noted between the tinnitus group and control group. Low blood zinc level was defined by using the mean and standard deviation for the control group (mean-1 S.D.). We treated patients with low blood zinc levels. A total dose of 34-68 mg of Zn++ was administered daily for over 2 weeks. The degree of tinnitus was expressed on a numeric scale from 0 to 10 before and after treatment. Blood zinc levels were significantly elevated (p < 0.05) after treatment. We found a significant decrease (p < 0.01) in the numeric scale. These findings suggest that zinc is useful in at least some patients suffering from tinnitus. It is possible to classify patients with tinnitus by measuring serum zinc level and this leads to improvement of the overall treatment effect.     

The inert gas effect on the rate of evaporation of zinc and cadmium

An experimental study has been made to investigate the effect of argon and helium on the rate of evaporation of zinc and cadmium under one atmosphere pressure at temperatures ranging from 500 to 850°C. The experimental results were compared with the maximum rates calculated using the effusion formula as well as with values obtained using two different types of equations based on kinetic theory, diffusion theory, and empirical data. Equations have been derived for expressing the rate of evaporation of zinc and cadmium in both argon and helium as functions of temperature of the liquid zinc and cadmium. It was found that the rates of evaporation of zinc and cadmium were higher in helium than in argon, with the difference increasing with increasing temperature. It was also found that the experimental results obtained in argon agree with the calculated values better than those obtained in helium.     

原子吸收法测定蒸馏残渣中锌含量

本文论述了在竖罐炼锌中为了指导公司回收率的工作,如何利用原子吸收光光谱仪快速、准确、及时的分析蒸馏残渣中锌的含量。选择仪器的最佳操作条件和最佳工作曲线,考察杂质元素碳以及酸度对锌元素含量的影响。通过精密度和准确度的测量,结果表明：该法操作简单,精密度高,准确度好,杂质元素对锌含量的测定无任何影响,完全满足分析要求。     

Intestinal zinc absorption after intravenous zinc injection in various amounts and after various time intervals

Beta-hydroxypropionitrile (beta-HPN) was incorporated in the drinking water of rats in order to define the toxicological effects associated with repeated daily exposure to this compound. Parameters evaluated were appearance and demeanor, mortality, body weight, food consumption, water consumption, hematology, terminal organ weights and organ to body weight ratio, and gross and microscopic pathology of tissues. No untoward effects were associated with the ingestion of beta-HPN at the dose levels utilized.     

The effect of zinc on alkaline phosphatase activity in rheumatoid synovial tissue

To examine the reported beneficial effect of zinc in rheumatoid arthritis, rheumatoid synovial tissue has been maintained in vitro in non-proliferative culture with or without zinc sulphate in the culture medium. Alkaline phosphatase activity was measured by microdensitometry of the cytochemical reaction in cryostat sections; the activity in blood vessels was measured separately from that in the supporting tissue below the synovial surface. Zinc enhanced this activity optimally at concentrations of between 10(-5) and 10(-4) mol/l.     

The effect of chlorine substitution on the dermal absorption of polychlorinated biphenyls

This study investigated the characteristics of computer-based case simulations (CCS) that may be associated with case difficulty. Difficulty was defined as the average rating by physicians of examinee performance on a nine-point scale or the passing rate on the cases. Two data sets were used, one from an administration of 18 cases, the other from an administration of 22 cases with 13 cases used on both occasions. Stepwise regression procedures were used separately for case properties and for analytic scoring of key variables to identify the best sets of predictors of case difficulty. Because of the small number of cases, regression results were evaluated for consistency across both data and both difficulty measures. For key variables, the best set of predictors included the number of different serious errors of commission, risk items, and benefit items. In general, cases were more difficult for higher values of these variables. For case variables, the only consistent variable was the length of the paragraph that provided patient history, with longer paragraphs associated with more difficult cases. Other variables were less consistent, but were often related to the structure of the simulation or the severity of the patient condition. Although the findings for case variables were limited, the analyses were very helpful in illuminating the interconnections among the variables within cases.     

The acid-base behavior of zinc sulfate electrolytes: The temperature effect

The pH of both synthetic zinc sulfate solutions of various compositions and commercial zinc plant electrolytes was measured over a range of temperatures. A model for the solution thermodynamics has been developed to predict the solution speciation, temperature, and concentration effects on the pH. It was found from both the thermodynamic predictions and the pH measurements that the pH of zinc sulfate electrolytes, in the absence of free acid, drops with increasing temperature. The pH-temperature behavior was largely dominated by zinc hydrolysis. The pH of zinc sulfate electrolytes with small amounts of free acid both increased and then decreased in the temperature range of interest. This was explained by taking into account the additional effects of bisulfate/sulfate equilibrium and/or ZnSO₄ ion pairing on the overall pH behavior. Based on the correlation between the model and pH measurements, it is evident that the dinuclear species Zn₂(OH)³⁺ exists at a much higher concentration than Zn(OH)⁺ ions and dominates the pH-temperature behavior of the solution. Speciation and the acid/base composition of a ZnSO₄ solution, against pH at 100 °C, were also predicted. The pH-temperature behavior of zinc plant electrolytes from Kidd creek (Falconbridge Limited, Timmins, Canada) and CEZinc (Noranda Limited, Valleyfield, Canada) was measured by saturating the electrolytes with ZnO at 100 °C and then allowing the solutions to cool. The pH first increased slightly and then dropped from a maximum pH of 4.2. By including species involving Al³⁺, Mg²⁺, Mn²⁺, and Na⁺ in the zinc plant electrolytes in the solution model calculation, model predictions of the pH-temperature were again correlated with the pH-temperature measurements on zinc plant electrolytes.