scholarly journals The Enhancement of Enargite Dissolution by Sodium Hypochlorite in Ammoniacal Solutions

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4529
Author(s):  
Lilian Velásquez-Yévenes ◽  
Hans Álvarez ◽  
Víctor Quezada ◽  
Antonio García
Keyword(s):  
Sodium Chloride ◽  
Sodium Hypochlorite ◽  
Ammonium Carbonate ◽  
Packed Bed ◽  
Ammonium Ions ◽  
Copper Concentrate ◽  
Copper Dissolution ◽  
Curing Period ◽  
Anionic Ligands ◽  
Rapid Dissolution

The dissolution of both copper and arsenic from a copper concentrate was investigated in oxidative ammonia/ammonium solutions at moderate temperatures and atmospheric pressure. The main parameters studied were temperature, pH, concentrations of different ammonia salts, the presence of sodium hypochlorite, pretreatment with sodium chloride, and curing period. In all ammoniacal solutions studied, increasing the temperature enhanced the dissolution of copper, but the dissolution of arsenic remained marginal. Mixing the copper concentrate with sodium chloride and leaving it to rest for 72 h before leaching in ammoniacal solutions significantly increased the dissolution of copper and slightly increased the dissolution of arsenic from the concentrate. A maximum of 35% of Cu and 3.3% of As were extracted when ammonium carbonate was used as the lixiviant. The results show relatively rapid dissolution of the concentrate with the addition of sodium hypochlorite in ammonium carbonate solution, achieving a dissolution of up to 50% and 25% of copper and arsenic, respectively. A copper dissolution with a non-linear regression model was proposed, considering the effect of NaClO and NH4Cl at 25 °C. These findings highlight the importance of using the correct anionic ligands for the ammonium ions and temperature to obtain a high dissolution of copper or arsenic. The results also showed that the curing time of the packed bed before the commencement of leaching appeared to be an important parameter to enhance the dissolution of copper and leave the arsenic in the residues.

In-Situ Leaching of South Texas Uranium Ores-Part 2: Oxidative Removal of Adsorbed Ammonium Ions With Sodium Hypochlorite

1983 ◽  
Vol 23 (02) ◽  
pp. 387-396 ◽  
Author(s):  
J.M. Paul ◽  
W.F. Johnson ◽  
A. Fletcher ◽  
P.B. Venuto
Keyword(s):  
Cation Exchange ◽  
Sodium Hypochlorite ◽  
Geographical Area ◽  
Ammonium Bicarbonate ◽  
South Texas ◽  
Ion Concentration ◽  
Ammonium Ion ◽  
Side Reactions ◽  
Ammonium Ions

Abstract This paper reports a laboratory study of the oxidative destruction by sodium hypochlorite (NaOCl) of ammonium ions adsorbed on relatively reduced south Texas uranium ore. Included are an assessment of reaction stoichiometry, determination of some major reaction pathways and side reactions, and identification of several pathways and side reactions, and identification of several intermediates. Adsorbed ammonium ions were completely removed by 0.5 % NaOCl, with the concentration of NH3 in the effluent falling to a very low value after 10 to 15 PV NaOCl oxidant. A small fraction (5 to 10%) of NaOCl was utilized in reacting with NH3. After the NH3 was nearly depleted, mono-, di-, and trichloramines, the expected intermediates in NaOCl oxidation of NH3, were observed. Chloramine decomposition studies showed that all three decomposed completely within 12 days. Since the ore was relatively highly reducing, the major pan of the NaOCl was, not unexpectedly, consumed in side reactions. Substantial quantities of sulfate, reflecting oxidation of sulfide minerals such as pyrite, were formed, large amounts of uranium were leached out, and substantial amounts of calcium and magnesium ions were also produced during the presaturation with NH4HCO3 preceding the oxidation stage. Introduction A leachate that has sometimes been used for in-situ leaching of uranium ores is a solution of ammonium bicarbonate (NH4HCO3) containing an oxidant-usually hydrogen peroxide (H2O2) or oxygen (O2). The ammonium ion (NH4+) introduced into the ore body upon injection of this leachate is exchanged for cations such as calcium (Ca+2 ) and sodium (Na+), which are associated with mineral species in the formation possessing available cation exchange sites. As the indigenous groundwaters reinvade the leached zone, the adsorption process is reversed with NH4+ ions being displaced from process is reversed with NH4+ ions being displaced from the cation exchange sites and returned to the ground-waters. In general, this latter process maintains the ammonia (NH3 (or NH4+ ion) concentration well above the baseline (pre-mining) value in groundwater for extended periods of time in waters produced from wells in or near the mined zone following cessation of leachate injection. Prior to abandonment of an in-situ leach-mining site by the operator, satisfactory restoration of groundwater quality must be demonstrated. Requirements for this demonstration vary with the geographical area. A summary of applicable regulations has been provided by Kasper et al. A review of the state of restoration demonstrations to Sept. 1979 has been given by Tiepel. Most of the in-situ leach operations in south Texas have been conducted in aquifers containing indigenous waters with TDS contents in the 700- to 3,000-ppm range. Ca+ 2, magnesium (Mg+2), and bicarbonate ion (HCO3 ) concentrations are high in these slightly alkaline waters. These equilibrium water compositions indicate that an appreciable fraction of the interlayer ion exchange sites of the smectite clays in the formation are occupied by Ca+2 or Mg+2 ions. SPEJ P. 387

scholarly journals Comparative Study of the Efficiency of Sodium Hydroxide, Sodium Hypochlorite and Sodium Chloride as Extractors of Residual Silver From X-Ray Plates and Graphical Effluents by the Volhard Method

2019 ◽  
Vol 6 (2) ◽  
pp. 144-151
Author(s):  
Carlos Alberto Paraguassu-Chaves ◽  
Cláudio José Pinto de Faria ◽  
Filomena Maria Minetto Brondani ◽  
Vera Lúcia Matias Gomes Geron ◽  
Nelson Pereira Silva Junior ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Comparative Study ◽  
Sodium Hydroxide ◽  
Sodium Hypochlorite ◽  
X Ray

THE EFFECT OF MAGNESIUM, POTASSIUM, AND IRON ON THE GROWTH AND MORPHOLOGY OF RED HALOPHILIG BACTERIA

1955 ◽  
Vol 1 (7) ◽  
pp. 486-494 ◽  
Author(s):  
Helen J. Brown ◽  
N. E. Gibbons
Keyword(s):  
Sodium Chloride ◽  
Halophilic Bacteria ◽  
Maximum Growth ◽  
Potassium Ion ◽  
Ferrous Ion ◽  
Magnesium Ion ◽  
Ammonium Ions ◽  
Coccoid Form ◽  
Low Concentrations

Maximum growth of the red halophilic bacteria occurs in the presence of 3.0 to 5.0 M sodium chloride, 0.1 to 0.5 M magnesium ion, 50 to 100 p.p.m. (1.3 to 2.5 × 10−3 M) potassium ion, and 0.5 to 1.0 p.p.m. (1 to 2 × 10−5 M) ferrous ion. In magnesium deficient media the rod forms become coccoid. Some strains can be adapted to grow in low concentrations of magnesium (0.01 M) and these adapted strains retain a coccoid form even when transferred to higher concentrations of magnesium. Growth does not occur when potassium is removed from the medium. The potassium requirement may be satisfied by rubidium but not by cesium, lithium, or ammonium ions. Potassium partially replaces the sodium chloride requirement of the red halophiles.

scholarly journals Leaching of Pure Chalcocite in a Chloride Media Using Sea Water and Waste Water

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 780 ◽  
Author(s):  
Norman Toro ◽  
Williams Briceño ◽  
Kevin Pérez ◽  
Manuel Cánovas ◽  
Emilio Trigueros ◽  
...  
Keyword(s):  
Sea Water ◽  
Chloride Concentration ◽  
Xrd Analysis ◽  
Quadratic Model ◽  
Copper Extraction ◽  
Copper Ore ◽  
Copper Dissolution ◽  
Rapid Dissolution ◽  
Chloride Environment ◽  
Kinetics Of

Chalcocite is the most important and abundant secondary copper ore in the world with a rapid dissolution of copper in an acid-chloride environment. In this investigation, the methodology of surface optimization will be applied to evaluate the effect of three independent variables (time, concentration of sulfuric acid and chloride concentration) in the leaching of pure chalcocite to extract the copper with the objective of obtaining a quadratic model that allows us to predict the extraction of copper. The kinetics of copper dissolution in regard to the function of temperature is also analyzed. An ANOVA indicates that the linear variables with the greatest influence are time and the chloride concentration. Also, the concentration of chloride-time exerts a significant synergic effect in the quadratic model. The ANOVA indicates that the quadratic model is representative and the R2 value of 0.92 is valid. The highest copper extraction (67.75%) was obtained at 48 h leaching under conditions of 2 mol/L H2SO4 and 100 g/L chloride. The XRD analysis shows the formation of a stable and non-polluting residue; such as elemental sulfur (S0). This residue was obtained in a leaching time of 4 h at room temperature under conditions of 0.5 mol/L H2SO4 and 50 g/L Cl−.

Sodium Hypochlorite: its Application and Stability in Bleaching

1995 ◽  
Vol 30 (2) ◽  
pp. 339-361 ◽  
Author(s):  
Tilak V. Bommaraju
Keyword(s):  
Sodium Chloride ◽  
Sodium Hydroxide ◽  
Sodium Hypochlorite ◽  
Experimental Results ◽  
Aqueous Sodium ◽  
The Stability ◽  
Selection Of ◽  
End Uses

Abstract One of the end uses of chlorine and sodium hydroxide, both produced by the electrolysis of aqueous sodium chloride, is in the manufacture of sodium hypochlorite, commonly called liquid “bleach.” This article outlines the methods of manufacturing liquid bleach, including the factors involved in the selection of materials of construction for handling chlorine, sodium hydroxide and sodium hypochlorite. Experimental results were presented addressing the stability of sodium hypochlorite as influenced by temperature and pH, and by anionic impurities such as Cl−, ClO3−, CO3− and SO4−, and cationic impurities which include Ca++, Mg++, Cu++, Ni++ and Fe++. Various techniques were also outlined to minimize the formation of chlorates during storage and bleaching and to improve the quality and stability of sodium hypochlorite.

Research on the Role of Pre-Oxidation in the Separation of Cu-Pb in the Presence of Potassium Dichromate

2011 ◽  
Vol 402 ◽  
pp. 526-528 ◽  
Author(s):  
Bao Lin Ke ◽  
Jian Hua Chen
Keyword(s):  
Sodium Hypochlorite ◽  
Potassium Dichromate ◽  
Copper Concentrate ◽  
Long Time ◽  
Short Time

It is the most effective method to use potassium dichromate to separate copper from lead when galena is oxidized. However, it needs long time to oxidize galena by potassium dichromate. The efficiency of five oxidants on potassium dichromate depressing ability to galena have been studied completely in this paper, and results suggest that separation of Cu-Pb can be carried out effectively in short time in the presence of potassium dichromate when galena is pre-oxidized by oxidants. Sodium hypochlorite is the best oxidant, and after the interaction of 15 min., the grade and the recovery of copper concentrate are 24.02% and 81.93% respectively, and the grade and the recovery of lead concentrate are 17.88% and 84.98% respectively.

Initiation of copper dissolution in sodium chloride electrolytes

2006 ◽  
Vol 51 (26) ◽  
pp. 5660-5668 ◽  
Author(s):  
D. Starosvetsky ◽  
O. Khaselev ◽  
M. Auinat ◽  
Y. Ein-Eli
Keyword(s):  
Sodium Chloride ◽  
Copper Dissolution
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