On the Role of Dilution on Selective Hydrolytic Precipitation from Bimetallic Solutions: Zn–Ni Sulfate Solution

2016 ◽  
Vol 70 (7) ◽  
pp. 1697-1705 ◽  
Author(s):  
Mostafa Aghazadeh Ghomi ◽  
Javad Moghaddam ◽  
Naghi Parvini Ahmadi
Keyword(s):  
Sulfate Solution ◽  
Hydrolytic Precipitation

Role of sodium citrate in leaching of low-grade and multiphase zinc oxide ore in ammonia–ammonium sulfate solution

2017 ◽  
Vol 169 ◽  
pp. 534-541 ◽  
Author(s):  
Kun Yang ◽  
Libo Zhang ◽  
Chao Lv ◽  
Jinhui Peng ◽  
Shiwei Li ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Ammonium Sulfate ◽  
Sodium Citrate ◽  
Sulfate Solution ◽  
Low Grade ◽  
Ammonium Sulfate Solution

Mitigating effect of chloride ions on sulfate attack of cement mortars with or without silica fume

2008 ◽  
Vol 35 (11) ◽  
pp. 1210-1220 ◽  
Author(s):  
Seung-Tae Lee ◽  
Dae-Wook Park ◽  
Ki-Yong Ann
Keyword(s):  
Silica Fume ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Chloride Ions ◽  
X Ray Diffraction ◽  
Friedel’S Salt ◽  
Cement Mortars ◽  
Binder Ratio ◽  
Change Of Porosity

This paper presents a detailed experimental study on the sulfate attack of mortar specimens with or without silica fume exposed to sulfate and sulfate–chloride solutions (with the same concentration of SO42– ions) up to 510 d. The overall aim of the study is to investigate the beneficial effect of chloride ions on sulfate attack. In addition, the role of silica fume and water–binder ratio (w/b) in resisting sulfate attack is also reported. To qualitatively assess the performance of mortar specimens exposed to test solutions, visual examination and compressive strength and expansion tests were carried out. X-ray diffraction (XRD) and mercury intrusion porosimetry (MIP) techniques were also used to evaluate the products formed by hydration and chemical reaction and the change of porosity for paste samples. Results indicated that the presence of chloride ions in sulfate environments mitigated the deterioration of ordinary Portland cement mortar specimens, especially with a higher w/b, due to sulfate attack. It seems that the mitigating effect of chloride ions on sulfate attack is attributable to the increased solubility of sulfate products in the chloride-bearing sulfate solution, and the chemical binding of the ions to form Friedel’s salt.

Chemical vs. Biological Crystals, all the Same?

2017 ◽  
Vol 262 ◽  
pp. 559-562
Author(s):  
Jan Weijma ◽  
Paula Gonzàles-Contreras ◽  
Cees N.J. Buisman
Keyword(s):  
Crystal Growth ◽  
Ferrous Iron ◽  
Sulfate Solution ◽  
Bulk Solution ◽  
Saturation State ◽  
Sulfate Reducing ◽  
Continuous Bioreactor ◽  
Bioreactor Experiment ◽  
Sulfate Reducing Bioreactor

Using microorganisms to mediate crystallisation of metals and minerals in open-culture bioreactors has potential to recover recyclable materials from dilute aqueous streams, but also to prevent their emission to the environment. Although this potential is already exploited in practice to some extent, biological crystallization for metal recovery is still largely a black box technology with limited understanding of the role of the microorganisms in the crystallization, and the differences with chemical crystallisation. Using biocrystallisation of scorodite (FeAsO4.2H2O) and sphalerite (ZnS) as examples we propose that the role of microorganisms strongly depends on established saturation state of the solution. For scorodite, microorganisms are used to exert control over the crystallization as their ferrous iron-oxidizing activity keeps the solution slightly oversaturated. Also, the oversaturation level is kept homogeneous because of continuous biological formation of the reactant ferrous iron throughout the solution. In continuous bioreactor experiments on which we reported previously, scorodite crystal sizes still increased after 72 days of bioreactor operation indicating that indeed crystal growth was favored over nucleation. On the other hand, in our experiments with zinc sulfide, crystallization proceeded in highly oversaturated solutions in a continuous sulfate reducing bioreactor fed with a zinc sulfate solution and H2/CO2 as electron donor and carbon source. The high oversaturation likely resulted in dominant primary nucleation in the bulk solution, with little or no control over crystal growth, even though agglomeration may still have occurred. This was exemplified by particle sizes which decreased in the bioreactor experiment and remained stable after already about 2 weeks of operation.

Role of organics on the purification process of zinc sulfate solution and inhibition mechanism

2019 ◽  
Vol 6 (10) ◽  
pp. 106588
Author(s):  
Tian Wang ◽  
Guo Lin ◽  
Likun Gu ◽  
Tu Hu ◽  
Tingfang Xie ◽  
...  
Keyword(s):  
Zinc Sulfate ◽  
Sulfate Solution ◽  
Inhibition Mechanism ◽  
Purification Process ◽  
Zinc Sulfate Solution

The role of temperature in the thaumasite formation under the immersion of magnesium sulfate solution

2021 ◽  
pp. 1-28
Author(s):  
Surong Luo ◽  
Zhen Wang ◽  
Qingnan Gong ◽  
Dehui Wang
Keyword(s):  
Magnesium Sulfate ◽  
Cement Mortar ◽  
Energy Dispersive Spectrometer ◽  
Sulfate Solution ◽  
Corrosion Products ◽  
Limestone Powder ◽  
Direct Reaction ◽  
X Ray Diffraction ◽  
Magnesium Sulfate Solution

To clarify the role of temperature in the thaumasite formation of cement mortar under magnesium sulfate solution at two different temperature, the corrosion products and microstructure of cement-based materials with different amounts and particle sizes of limestone powder (LP) were quantitatively analyzed by Fourier Transform Infra-Red (FTIR), thermogravimetric analysis (TGA), X-ray Diffraction (XRD), Scanning Electronic Microscopy (SEM) and Energy Dispersive Spectrometer (EDS). At 5oC, the main corrosion product of cement mortar was gypsum and thaumasite. At 20°C, the main corrosion products of cement mortar were gypsum and ettringite. When the temperature increased from 5°C to 20°C, the contents of ettringite, thaumasite and gypsum changed from 0.3%, 12.3% and 64.6% to 4.6%, 0% and 57.0%, respectively. The formation of thaumasite was the combination of direct reaction with ettringite transformation. The incorporation of LP accelerated the corrosion of mortars, and the change coefficient of compressive strength of mortars decreased from 100% to 47.3% when its content increased from 0% to 30%. Low temperature and incorporation of finer limestone powder enhanced the corrosion of magnesium sulfate solution.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

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