Extraction of copper

HydrometaHurgical processes for copper can be categorized as (/) acid extraction of copper from oxide ore (2) oxidation and solution of sulfides in waste rock from mining, concentrator tailings, or in situ ore bodies (J) dissolution of copper in concentrates to avoid conventional smelting and (4) extraction of copper from deep-sea manganese nodules. 

Colorimetric procedures are often used to determine copper in trace amounts. Extraction of copper using diethyldithiocarbamate can be quite selective (60,62), but the method using dithhone is preferred because of its greater sensitivity and selectivity (50—52). Atomic absorption spectroscopy, atomic emission spectroscopy, x-ray fluorescence, and polargraphy are specific and sensitive methods for the deterrnination of trace level copper. 

The etched printed circuit boards are washed out with water to dilute the concentration of the contaminants on the board surface to an acceptable level. The extraction of copper from the effluent rinse water is essential for both environmental and economic reasons since decontaminated water is returned to the rinse vessel. 

Chemical kinetics and mechanisms in solvent extraction of copper chelates. D. S. Flett, Acc. Chem. Res., 1977,10, 99-104(21). 

The above model of settler flow behaviour, combined with entrainment backmixing was used by Aly (1972) to model the unsteady-state extraction of copper from aqueous solution, using Alamine 336 solvent. An identification procedure for the relevant flow parameters showed an excellent fit to the experimental data with very realistic entrainment backmixing factors, fL = fQ = 3.5 percent, the fraction of well-mixed flow in the settlers, (XX = ay = 5 percent and an overall mass transfer capacity coefficient, Ka = 25 s->. 

A knowledge of the extraction equilibria between the organic and aqueous phases helps to identify the operational variables that can control the solvent extraction process. An example - the extraction of copper from a copper sulfate solution using a chelating reagent (HR) - is considered. This is one of the best studied examples of solvent extraction. Normally, the system would not be described as a water-hydrocarbon dual-phase system, as it is in fact the Cu2+, SO-, H+, R-, and R-, and the equation... 

The present description pertaining to copper refers to solvent extraction of copper at the Bluebird Mine, Miami. When the plant became operational in the first quarter of 1968 it used L1X 64, but L1X 64N was introduced in to its operation from late 1968. The ore consists of the oxidized minerals, chrysocolla and lesser amounts of azurite and malachite. A heap leaching process is adopted for this copper resource. Heap-leached copper solution is subjected to solvent extraction operation, the extractant being a solution of 7-8% L1X 64N incorporated in kerosene diluent. The extraction process flowsheet is shown in Figure 5.20. The extraction equilibrium diagram portrayed in Figure 5.21 (A) shows the condi-... 

Hsu J.H., Lo S.L. Charaterization and extractability of copper, manganese, and zinc in swine manure composts. J Environ Qual 2000 29 447-453. 

The soft S2 donor sets presented by these bidentate ligands lead to very strong binding of heavy metals (Table 7) which are not stripped by sulfuric acid, ensuring that these deleterious elements do not transfer to the Zn electrolyte.196 However, co-extraction of copper is accompanied by reduction to Cu1 which has proved very difficult to strip to regenerate the reagent and will lead to poisoning of the extractant unless all traces of copper are removed from the feed solution. 

Sole, K. C. Solvent extraction of copper from high concentration pressure acid leach liquors. International Solvent Extraction Conference, Cape Town, South Africa, Mar. 17-21, 2002, 1033-1038. 

Soldenhoff, K. H. Solvent extraction of copper(II) from chloride solutions by some pyridine carboxylate esters. 

Kyuchoukov, G. Szymanowski, J. Extraction of copper(II) and zinc(II) from chloride media with mixed extractants. J. Radioanal. Nucl. Chem. 2000, 246, 675-682. 

Kyuchoukov, G. Mishonov, I. On the extraction of copper and zinc from chloride media with mixed extractant. Solvent Extr. Res. Dev, Jpn. 1999, 6, 1-11. 

Borowiak-Resterna, A. Extraction of copper(II) from acid chloride solutions by N-dodecyl- and N,N-dihexylpyr-idinecarboxamides. Solvent Extr. Ion Exch. 1999, 17, 133-148. 

Mickler, W. Uhlemann, E. Liquid-Liquid extraction of copper from ammoniacal solution with 4-acylpyrazol-5-ones. Sep. Sci. Technol. 1993, 28, 1913-1921. 

Fig. 16 Two different types of reaction at liquid/liquid interfaces, the solvent extraction of copper and the transfer of NOJ.

A somewhat different liquid/liquid system is found in the solvent extraction of copper. We have studied the system using heptane/water. These solvents are so immiscible that, as shown in Fig. 15, there is probably no extensive interphase region but a more sharply defined interface. We have shown that for the oxime ligand, Acorga P50 [4], written as HL, the mechanism of the reaction is as in Scheme 2 (Albery et al., 1984 Albery and Choudhery, 1988). 

Fig. 18 Free energy profiles for the solvent extraction of copper, where L is Acorga P50. The profile shows the free energy of a site on the liquid/liquid interface. All higher-order rate constants are reduced to first-order rate constants by using the concentrations of reactants in either phase. The free energy lost in each cycle can be seen from the difference between 0 and the 10%, 50% and 80% extraction lines on the right of the diagram. The double-headed arrows indicate the rate-limiting free energy difference.

In a similar procedure [32] the sediment is wet oxidised with dilute sulphuric acid and nitric acids in an apparatus in which the vapour from the digestion is condensed into a reservoir from which it can be collected or returned to the digestion flask as required. The combined oxidised residue and condensate are diluted until the acid concentration is IN and nitrate is removed by addition of hydroxylammonium chloride with boiling. Fat is removed from the cooled solution with carbon tetrachlodithizone in carbon tetrachloride. The extract is shaken with 0.1M hydrochloric acid and sodium nitrite solution and, after treatment of the separated aqueous layer with hydroxylammonium chloride a solution of urea and then EDTA solution are added to prevent subsequent extraction of copper. The liquid is then extracted with a 0.01% solution of dithizone in carbon tetrachloride and mercury estimated in the extract spectrophotometrically at 485nm. 

It will be instructive to consider briefly the methodology employed in the development of solvent extraction processes that have become operational. The development of the Bluebird Mine operation for the extraction of copper from dump leaching liquors by solvent extraction and the subsequent recovery of copper as either copper sulfate or cathode copper is used as an example. The initial investigations [11] included the following ... 

Bench-scale batch tests to determine the characteristics of the extraction of copper from sulfuric acid liquors by LIX 64... 

Continuous bench-scale operations to study the extraction of copper and other metals present in the leach liquor effects of variables such as temperature, 0/A ratio, solvent composition, extraction kinetics, settling characteristics, etc. 

The solubility of Kelex 100 has been reported to be 4.4 (pH 0.5), 1.4 (pH 1.0), and 1.6 (pH 1.5)ppm, in tests employing 0.5moldm Kelex 100 in Solvesso 150 diluent for the extraction of copper from solutions containing about 30 g dm of metals (Cu, Ni, and Co) [21]. Furthermore, over several months no change in the Kelex concentration was found in pilot plant operations with a 0.5moldm Kelex solution [21]. At higher pH values (up to 9) Kelex solubility has been determined at < 1 ppm in ammonium sulfate solutions up to 300 g dm [22]. It would be expected that the amphoteric nature of Kelex would show increasing solubility at pH values above 7, and lower than about 1, similar to the variation in solubility of... 

Although S-diketones cannot compete with hydroxyoximes for the extraction of copper from acid media, they do have advantages for extraction from ammoniacal leach solutions because, unlike hydroxyoximes, they do not transfer ammonia. The extraction follows Eq. (11.6), and the extent of extraction depends on the concentration of ammonia and ammonium salts. 

Extraction of Copper and Zinc from Brass Miii Fiue Dust... 

Fig. 14.4 Extraction of copper and zinc from weak sulfuric acid leach solutions.

Extraction of Copper and Recycle of Ammoniacal Etch Liquors... 

More advanced semiempirical molecular orbital methods have also been used in this respect in modeling, e.g., the structure of a diphosphonium extractant in the gas phase, and then the percentage extraction of zinc ion-pair complexes was correlated with the calculated energy of association of the ion pairs [29]. Semiempirical SCF calculations, used to study structure, conformational changes and hydration of hydroxyoximes as extractants of copper, appeared helpful in interpreting their interfacial activity and the rate of extraction [30]. Similar (PM3, ZINDO) methods were also used to model the structure of some commercial extractants (pyridine dicarboxylates, pyridyloctanoates, jS-diketones, hydroxyoximes), as well as the effects of their hydration and association with modifiers (alcohols, )S-diketones) on their thermodynamic and interfacial activity [31 33]. In addition, the structure of copper complexes with these extractants was calculated [32]. 

Elemental composition Cu 33.36%, I 66.64%. Either compound or mineral copper(I) iodide is identified by x-ray diffraction or fluorescence method. Copper may be analyzed in nitric acid extract of copper(I) iodide by various instrumental techniques (see Copper). 

About a third of the hydrogen manufactured is used in mining for the hydrometallurgical extraction of copper and other metals, the extraction of the metals from their ores by reduction in aqueous solution ... 

Processes for extracting metals from their ores are generally classified as pyrometallurgical, if high temperatures are used, or hydrometallurgi-cal, if aqueous solutions are used. Copper is extracted by both methods. In the pyrometallurgical process for the extraction of copper, the enriched ore is roasted, or heated in air ... 

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