scholarly journals Reducing-Effect of Chloride for the Dissolution of Black Copper

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 123 ◽  
Author(s):  
David Torres ◽  
Kevin Pérez ◽  
Emilio Trigueros ◽  
Ricardo I. Jeldres ◽  
Eleazar Salinas-Rodríguez ◽  
...  
Keyword(s):  
Standard Condition ◽  
Amorphous Structure ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Copper Mineral ◽  
Conventional Methods ◽  
Pre Treatment ◽  
High Concentrations ◽  
Copper Ores

Oxidized black copper ores are known for their difficulty in dissolving their components of interest through conventional methods. This is due to its non-crystalline and amorphous structure. Among these minerals, copper pitch and copper wad are of great interest because of their considerable concentrations of copper and manganese. Currently, these minerals are not incorporated into the extraction circuits or left untreated, whether in stock, leach pads, or waste. For the recovery of its main elements of interest (Cu and Mn), it is necessary to use reducing agents that dissolve the present MnO2, while allowing the recovery of Cu. In this research, the results for the dissolution of Mn and Cu from a black copper mineral are exposed, evaluating the reducing effect of NaCl for MnO2 through pre-treatment of agglomerate and curing, and subsequently leaching in standard condition with the use of a reducing agent (Fe2+). High concentrations of chloride in the agglomerate process and prolonged curing times would favor the reduction of MnO2, increasing the dissolution of Mn, while the addition of NaCl did not benefit Cu extractions. Under standard conditions, low Mn extractions were obtained, while in an acid-reducing medium, a significant dissolution of MnO2 was achieved, which supports the removal of Cu.

scholarly journals Extraction of Mn from Black Copper Using Iron Oxides from Tailings and Fe2+ as Reducing Agents in Acid Medium

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1112 ◽  
Author(s):  
Kevin Pérez ◽  
Norman Toro ◽  
Eduardo Campos ◽  
Javier González ◽  
Ricardo I. Jeldres ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Iron Oxides ◽  
Acidic Medium ◽  
Amorphous Structure ◽  
Reducing Agents ◽  
Copper Sample ◽  
Low Grade ◽  
Ferrous Ions ◽  
Two Samples ◽  
Copper Ores

Exotic type deposits include several species of minerals, such as atacamite, chrysocolla, copper pitch, and copper wad. Among these, copper pitch and copper wad have considerable concentrations of manganese. However, their non-crystalline and amorphous structure makes it challenging to recover the elements of interest (like Cu or Mn) by conventional hydrometallurgical methods. For this reason, black copper ores are generally not incorporated into the extraction circuits or left unprocessed, whether in stock, leach pads, or waste. Therefore, to dilute MnO2, the use of reducing agents is essential. In the present research, agitated leaching was performed to dissolve Mn of black copper in an acidic medium, comparing the use of ferrous ions and tailings as reducing agents. Two samples of black copper were studied, of high and low grade of Mn, respectively, the latter with a high content of clays. The effect on the reducing agent/black copper ratio and the concentration of sulfuric acid in the system were evaluated. Better results in removing Mn were achieved using the highest-grade black copper sample when working with ferrous ions at a ratio of Fe2+/black copper of 2/1 and 1 mol/L of sulfuric acid. Besides, the low-grade sample induced a significant consumption of H2SO4 due to the high presence of gangue and clays.

Molten ceramic solidification during molten state processing of HLW

2006 ◽  
Vol 932 ◽  
Author(s):  
Hajime Kinoshita ◽  
Masayoshi Uno ◽  
Shinsuke Yamanaka ◽  
William E. Lee
Keyword(s):  
Standard Condition ◽  
Solidification Process ◽  
Reducing Agents ◽  
Reducing Agent ◽  
High Level Waste ◽  
Molten State ◽  
Cooling Rates ◽  
High Level ◽  
State Processing

ABSTRACTSolidification of molten ceramics during molten state processing of High-Level Waste (HLW) was studied to investigate a possibility of a simpler and flexible process for immobilisation of HLW. Simulated HLW was heated together with different reducing agents (TiN with AlN or TiO2) either at 1673 K or 1873K for 1 to 3 hours under Ar atmosphere. Cooling rates of 5 K/min and 10 K/min did not result in any obvious differences in the products obtained under the standard condition used in the present study. The composition and quantity of the reducing agent had a significant effect on the melting and solidifying behaviour of the simulated HLW. The results suggest the possible further studies to improve the solidification process and the final product.

scholarly journals The Influence of Water Reducing Agents on Early Hydration Property of Ferrite Aluminate Cement Paste

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 731
Author(s):  
Chunlong Huang ◽  
Zirui Cheng ◽  
Jihui Zhao ◽  
Yiren Wang ◽  
Jie Pang
Keyword(s):  
Setting Time ◽  
Critical Role ◽  
Hydration Product ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Hydration Process ◽  
Early Hydration ◽  
Cement Pastes ◽  
Hydration Rate ◽  
Aluminate Cement

The ferrite aluminate cement (FAC) could rapidly lose fluidity or workability due to its excessive hydration rate, and greatly reduce the construction performance. Chemical admixtures are commonly used to provide the workability of cement-based materials. In this study, to ensure required fluidity of FAC, chemically different water reducing agents are incorporated into the FAC pastes. The experiments are performed with aliphatic water reducing agent (AP), polycarboxylic acid water reducing agent (PC) and melamine water reducing agent (MA), respectively. Influence of the water reducing agents on fluidity, setting time, hydration process, hydration product and zeta potential of the fresh cement pastes is investigated. The results show that PC has a better dispersion capacity compared to AP and MA. Besides decreasing water dosage, PC also acts as a retarder, significantly increasing the setting times, delaying the hydration rate and leading to less ettringite in the hydration process of FAC particles. The water reducing agents molecules are adsorbed on the surface of positively charged minerals and hydration products, however, for PC, steric hindrance from the long side chain of PC plays a critical role in dispersing cement particles, whereas AP and MA acting through an electrostatic repulsion force.

Characterization of Industrial Wastes, Glass and Ceramic Wool

2012 ◽  
Vol 727-728 ◽  
pp. 1585-1590
Author(s):  
Neuza Evangelista ◽  
Jorge Alberto Soares Tenório ◽  
José Roberto Oliveira ◽  
Paulo R. Borges ◽  
Taiany Coura M. Ferreira
Keyword(s):  
Average Particle Size ◽  
Amorphous Structure ◽  
Glass Wool ◽  
Industrial Wastes ◽  
Average Particle ◽  
X Rays ◽  
Ceramic Fibers ◽  
High Concentrations ◽  
Reduction Of Energy Consumption ◽  
Superior Corrosion Resistance

Ceramic fibers are characterized by their light weight, high degree of purity, low heat storage, low thermal conductivity, thermal shock resistance and superior corrosion resistance in high-temperature environments. In addition, they can be produced extensively in substitution to all materials used in the coating of almost all heating equipment as well as contributing to the reduction of energy consumption. Such characteristics make them ideal in the coating of distributors, mufflers, heating ovens, among others, as highly demanded by the mining and metallurgical industries, among others. After use in the process of industrial production, generated waste will lose their insulation capacity and thus require safe disposal. The present work focuses specifically on ceramic and glass wools aiming at an evaluation of their recycling prospect of incorporation into cement mortars and concrete. This residues were pulverized and displayed ~30µm average particle size. The scan electronic microscopy (SEM) presented elongated, thin and straight particles, which is very different than flocular structure of cement. The X-rays diffraction revealed amorphous structure for glass wool and crystalline structure for ceramics wool. The chemical analysis showed high concentrations of Al2O3 and silica in both residues, with higher percentage of calcium oxide in glass wool.

scholarly journals Synthesis of Gold Nanoparticles Using p-Aminobenzoic Acid and p-Aminosalicylic Acid as Reducing Agent

2019 ◽  
Vol 19 (1) ◽  
pp. 68
Author(s):  
Abdul Aji ◽  
Eko Sri Kunarti ◽  
Sri Juari Santosa
Keyword(s):  
Gold Nanoparticles ◽  
Optimum Condition ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Hydroxyl Group ◽  
Synthesis Process ◽  
Aminobenzoic Acid ◽  
Aminosalicylic Acid ◽  
Amino Groups ◽  
Transmission Electron

Synthesis of gold nanoparticles (AuNPs) by reduction of HAuCl4 with p-aminobenzoic acid and p-aminosalicylic acid as a reducing agent was investigated. This work was conducted in order to determine the optimum condition of AuNPs synthesis and examine the effect of the hydroxyl group in p-aminosalicylic acid towards the size, shape, and stability of the synthesized gold nanoparticles (AuNPs). The optimum condition of the gold nanoparticles synthesis was determined by UV/Vis spectrophotometer, the shape and size of gold nanoparticles were measured by Transmission Electron Microscope (TEM). The synthesis process was started by reacting HAuCl4 and the reducing agents in an aqueous solution at 86 ºC. The initial gold concentration, reducing agents concentration and pH were varied in order to obtain the optimum condition. In the optimum condition, the results showed that p-aminosalicylic acid containing both hydroxyl and amino groups performed higher reduction ability compared to p-aminobenzoic acid that only containing an amino group. Reducing agents which have a hydroxyl group (p-aminosalicylic acid) could produce AuNPs with a smaller concentration of HAuCl4 than p-aminobenzoic acid. Gold nanoparticles that were synthesized with p-aminosalicylic acid were more stable and had a smaller particle size compared to its counterpart that is synthesized with p-aminobenzoic acid.

scholarly journals Effects of reducing reagents and temperature on conversion of nitrite and nitrate to nitric oxide and detection of NO by chemiluminescence

1997 ◽  
Vol 43 (4) ◽  
pp. 657-662 ◽  
Author(s):  
Fan Yang ◽  
Eric Troncy ◽  
Martin Francœur ◽  
Bernard Vinet ◽  
Patrick Vinay ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Effect Of Temperature ◽  
Fixed Amount ◽  
Increased Temperature

Abstract To measure the concentration of nitrites and nitrates by chemiluminescence, we examined the efficiency of five reducing agents [V(III), Mo(VI) + Fe(II), NaI, Ti(III), and Cr(III)] to reduce nitrite (NO2−) and (or) nitrate (NO3−) to nitric oxide (NO). The effect of each reducing agent on the conversion of different amounts of NO2− and (or) NO3−(100–500 pmol, representing concentrations of 0.4 to 2 μmolar) to NO was determined at 20 °C for NO2− and at 80 °C for NO3−. The effect of temperature from 20 to 90 °C on the conversion of a fixed amount of NO2− or NO3− (400 pmol or 1.6 μmolar) to NO was also determined. These five reducing agents are similarly efficient for the conversion of NO2− to NO at 20 °C. V(III) and Mo(VI) + Fe(II) can completely reduce NO3− to NO at 80 °C. NaI and Cr(III) were unable to convert NO3− to NO. Increased temperature facilitated the conversion of NO3− to NO, rather than that of NO2− to NO. We evaluated the recovery of NO2− and NO3− from plasmas of pig and of dog. Recovery from plasma of both animals was reproducible and near quantitative.

New insights into the formation mechanism of Ag, Au and AgAu nanoparticles in aqueous alkaline media: alkoxides from alcohols, aldehydes and ketones as universal reducing agents

2015 ◽  
Vol 17 (33) ◽  
pp. 21683-21693 ◽  
Author(s):  
Janaina F. Gomes ◽  
Amanda C. Garcia ◽  
Eduardo B. Ferreira ◽  
Cleiton Pires ◽  
Vanessa L. Oliveira ◽  
...  
Keyword(s):  
Alkaline Medium ◽  
Formation Mechanism ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Alkaline Media ◽  
Aldehydes And Ketones

Alkoxide from alcohols, aldehydes and ketones in alkaline medium is the actual and universal reducing agent of silver and gold ions.

Adaptation by sheep to isoflavones in clover

1969 ◽  
Vol 9 (41) ◽  
pp. 569 ◽  
Author(s):  
FHW Morley ◽  
D Bennett ◽  
A Axelsen
Keyword(s):  
Subterranean Clover ◽  
Biochanin A ◽  
Uterine Weight ◽  
Pre Treatment ◽  
High Concentrations

Vaginal mucus scores and uterine weights of ovariectomized ewes that grazed subterranean clover for 13 days prior to tests were similar to those from ewes fed non-oestrogenic rations during this pre-treatment, if the leaves of test clovers contained high concentrations of formononetin (F) (Yarloop and Dinninup). No responses were obtained from subterranean clovers low in F, but high in genistein (G) or biochanin A (BA) (Clare and Bacchus Marsh) except for a group which was fed a non-oestrogenic diet during pre-treatment, and which gave a positive mucus test, but not a stgnificant uterine weight response. These results indicate that ewes can become non-responsive to G and BA, but not to F, and offer an explanation for some inconsistencies among bioassays of subterranean clovers. The task of selection and breeding of subterranean clover seems to be simplified since G and BA are unlikely to be harmful.

scholarly journals Mechanism of copper-mediated inactivation of herpes simplex virus.

1997 ◽  
Vol 41 (4) ◽  
pp. 812-817 ◽  
Author(s):  
J L Sagripanti ◽  
L B Routson ◽  
A C Bonifacino ◽  
C D Lytle
Keyword(s):  
Hydrogen Peroxide ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Mammalian Cells ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Free Radical Scavengers ◽  
Protective Effects ◽  
Relative Level ◽  
Simplex Virus

The inactivation of herpes simplex virus (HSV) by copper was enhanced by the following reducing agents at the indicated relative level: ascorbic acid > hydrogen peroxide > cysteine. Treatment of HSV-infected cells with combinations of Cu(II) and ascorbate completely inhibited virus plaque formation to below 0.006% of the infectious virus input, while it maintained 30% viability for the host mammalian cells. The logarithm of the surviving fraction of HSV mediated by 1 mg of Cu(II) per liter and 100 mg of reducing agent per liter followed a linear relationship with the reaction time, in which the kinetic rate constant for each reducing agent was -0.87 min(-1) (r = 0.93) for ascorbate, -0.10 min(-1) (r = 0.97) for hydrogen peroxide, and -0.04 min(-1) (r = 0.97) for cysteine. The protective effects of metal chelators and catalase, the lack of effect of superoxide dismutase, and the partial protection conferred by free-radical scavengers suggest that the mechanism of copper-mediated HSV inactivation is similar to that previously reported for copper-mediated DNA damage. The sensitivity exhibited by HSV to Cu(II) and reducing agents, particularly ascorbate, might be useful in the development of therapeutic antiviral agents.

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