Leaching kinetics of a Nigerian complex covellite ore by the ammonia-ammonium sulfate solution

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−.

Section: Introductionmentioning

confidence: 99%

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

Toro

Briceño

Pérez

et al. 2019

“…An R 2 value lower than 0.9 implies that the application of the surface-reaction controlled Equation (2) may be inadequate for analyzing the kinetics of leaching for the as-received CuS at 50 °C. The unsound coefficient may be caused by the extremely low leachabilities, which is an effect that has been reported in previous research [10,49]. Except for this condition, the leaching data were fitted well by Equation (2), with a coefficient between 0.9208 and 0.9627 for the as-received CuS, 0.9538 and 0.9858 for the CuS ground at 300 rpm and 0.9556 and 0.9968 for the CuS ground at 700 rpm.…”

Section: Kinetics Of Copper Leaching For the Mechanically Activated Cusmentioning

confidence: 62%

Effect of Mechanical Activation on the Kinetics of Copper Leaching from Copper Sulfide (CuS)

Lee

Kim

et al. 2018

Abstract:The effect of mechanical activation on the copper leaching of copper sulfide, CuS, in 1 M HNO 3 (slurry density: 10 g/L) was investigated by analysis of the leachability and the apparent activation energy. Mechanical activation produced an increase in the leachability and a decrease of the activation energy in this leaching reaction. The leachability increased proportionally to the degree of mechanical activation, reaching 96.6% leaching within 60 min at 80 • C from CuS ground at 700 rpm for 15 min. This leaching process was controlled by surface chemical reaction following the shrinking-core model. The apparent activation energy of leaching for CuS (71.5 kJ/mol) in the range of 50 to 80 • C decreased with an increase of the degree of mechanical activation, reaching 44.3 kJ/mol for Cu leaching from CuS ground at 700 rpm for 15 min.

“…This has led to increasingly stringent environmental controls. In contrast, the recovery of complex low-grade copper minerals is based on the hydrometallurgical method, which is preferred due to its low cost of treatment, short construction time, operational simplicity, and functional recovery performance [16]. Additionally, this strategy has environmental benefits by producing non-hazardous solid waste [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…Research studies on covellite leaching have been varied, evaluating alternatives that contemplate different dissolution media, such as ammonia [16,20], nitrates [21,22], and chlorides [4,[23][24][25]. Bioleaching has also been considered, including bacteria such as thiobacillus ferrooxidans, acidithiobacillus ferrooxidans, and acidithiobacillus thiooxidans, which can grow under anaerobic conditions where ferric ions are used as electron receptors [26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Statistical Study for Leaching of Covellite in a Chloride Media

Pérez

Toro

Saldaña

et al. 2020

Covellite is a secondary copper sulfide, and it is not abundant. There are few investigations on this mineral in spite of it being formed during the leaching of chalcocite or digenite; the other investigations on covellite are with the use of mineraloids, copper concentrates, and synthetic covellite. The present investigation applied the surface optimization methodology using a central composite face design to evaluate the effect of leaching time, chloride concentration, and sulfuric acid concentration on the level of copper extraction from covellite (84.3% of purity). Copper is dissolved from a sample of pure covellite without the application of temperature or pressure; the importance of its purity is that the behavior of the parameters is analyzed, isolating the impurities that affect leaching. The chloride came from NaCl, and it was effectuated in a size range from –150 to +106 μm. An ANOVA indicated that the leaching time and chloride concentration have the most significant influence, while the copper extraction was independent of sulfuric acid concentration. The experimental data were described by a highly representative quadratic model obtained by linear regression (R2 = 0.99).