LIX 984N Research Articles

Extraction separation of Cu(II) and Co(II) from sulfuric solutions by hollow fiber renewal liquid membrane

Extraction separation of Cu(II) and Co(II) from sulfuric wastewater is studied with hollow fiber renewal liquid membrane (HFRLM) technique. The organic solution of LIX 984N in kerosene is used as the liquid membrane phase to selectively separate and concentrate Cu(II) from aqueous solution; and the extractant of CYANEX 272 is used as carrier to remove and concentrate Co(II) from aqueous solution. In the selective separation process, LIX 984N has good selectivity on Cu(II); the interactions among metal ions can be negligible; the pH in the feed aqueous solution has significant influence, while the influence of hydrogen ion concentration in the stripping phase is slight. The removal efficiency of Cu(II) increases with the increasing flow rate on lumen side, while decreases with the increasing flow rate on shell side. The results of lab-scale cascade experiments show that the HFRLM technique is a promising treatment method for simulated sulfuric wastewater containing copper and cobalt with separation factor higher than 100. The Cu(II) and Co(II) concentrations in the raffinate are lower than 0.50 mg L −1 and 1.0 mg L −1, respectively, which are both below the standard of wastewater discharge in China. Based on the surface renewal theory, resistance-in-series model and mass balance law, a corresponding mass transfer mathematical model is developed; and the calculated results are in good agreement with experimental data.

Selective separation of copper and nickel by solvent extraction using LIX 984N

Selective separation of copper and nickel from ammoniacal/ammonium carbonate medium was carried out by using LIX 984N diluted with deodourised kerosene. The study of the influence of equilibration time, equilibrium pH, extractant concentration and selective stripping of copper and nickel has been optimized. It was found that both the metal extractions were unaffected by the changes in pH. Nickel extraction equilibrium was reached at a longer contact time than that for copper and nickel extraction depends greatly on the extractant concentration in the organic phase. Co-extraction, ammonia scrubbing and selective stripping of copper and nickel were performed for a solution containing 3 g dm − 3 each of copper and nickel and 60 g dm − 3 ammonium carbonate. The extraction and the percentage of stripping for nickel and copper were almost quantitative.

Construction of isotherms in solvent extraction of copper

The aim of this work is construction of equilibrium isotherms in solvent extraction. Technological parameters have been predicted for treatment of mine water by solvent extraction and electrowining. Two stages of extractions and one stage of stripping have been predicted for copper recovery by analyzing the equilibrium isotherms. The process was performed on mine water with 2,5 g/dm3 Cu2+, 3 g/dm Fe2+, pH 1,8, using 9 vol% LIX 984N in kerosene (organic solvent), with 95 and 98% stages efficiencies, respectively. This course produced an advanced electrolyte solution, suitable for electrowining and cathodic copper recovery, containing 51 g/dm3 Cu2+ and 160g/dm3 H2SO4 from a 30 g/dm3 Cu and 190 g/dm3 H2SO4.

Optimization of separation processing of copper and iron of dump bioleaching solution by Lix 984N in Dexing Copper Mine

The effects of the concentration of Lix 984N, phase ratio, initial pH value of aqueous phase and extraction time on the extraction of copper and iron under the condition of low Cu 2+/Fe 3+ ratio in dump bioleaching solution of Dexing Copper Mine were explored. The optimal conditions of extraction are as follows: the concentration of Lix 984N 10%; the phase ratio (O/A) 1:1; the initial pH value of aqueous phase 1.5 and the mixing time 2 min. The stripping experiments show that H 2SO 4 solution could efficiently recover copper from the organic phase under the optimal conditions.

Impact of the copper solvent extraction reagent LIX 984N on the growth and activity of selected acidophiles

The effects of the copper extractant LIX 984N 20% v/v in Shellsol 2046 on the abilities of Acidithiobacillus ferrooxidans and Sulfobacillus thermosulfidooxidans to catalyse copper extraction from a chalcopyrite concentrate and to oxidise ferrous ion to ferric ion were compared and the possible role of Acidiphilium cryptum in ameliorating the effects of the SX reagent was examined. The SX reagent up to 250 mg/L was found to have little impact on the extraction of copper from a chalcopyrite concentrate using At. ferrooxidans. In contrast, with S. thermosulfidooxidans, copper extraction was reduced to about one third in the presence of 50 mg/L SX reagent and at 250 mg/L SX reagent, was barely more than for an abiotic test. The SX reagent strongly inhibited ferrous ion biooxidation by several bacterial species in contrast to At. ferrooxidans. The presence of 50 mg/L SX reagent caused oxidation rates to drop to between 0 and 12% of those in controls in approximately 40-hour tests. The most toxic component of the SX reagent was found to be 4-nonylphenol. A. cryptum tolerated 250 mg/L SX reagent but did not utilise it as an energy source. Bioleaching of chalcopyrite concentrate was not enhanced significantly when A. cryptum was added to test inocula. It is proposed that A. cryptum utilises fungal biomass as an energy source in managed heaps with solution recycle via solvent extraction plants. While it shares the environment with iron- and sulfur-oxidising acidophiles, it does not contribute directly to copper extraction from sulfide minerals.

Selective separation of Cu(II), Zn(II), and Cd(II) by solvent extraction

An experimental investigation was presented on the separation of Cu(II), Zn(II), and Cd(II) from a rich sulfate leachate of zinc slag by solvent extraction. The results of orthogonal experiments indicate that LIX 984N is highly selective and very efficient in the extraction of Cu(II), and the analysis of variance indicates that the sequence of parameters according to their influence on the separation efficiency is phase ratio > LIX 984N concentration > pH value > extraction time. The optimal condition for copper extraction is obtained as 25% of LIX 984N concentration, 7 min of extraction time, 3:2 of phase ratio O/A, and pH = 1.7. The separation of Zn(II) and Cd(II) was performed after the copper extraction from the raffinate. Comparative analysis of the separation with di-2-ethylhexyl phosphoric acid (D2EHPA), D2EHPA- tributylphosophate (TBP) synergistic extracting system, and 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester (HEHEHP) was made at pH = 2.0. It is demonstrated that the extraction efficiency with D2EHPA is improved after being saponified by sodium hydroxide, and D2EHPA-TBP synergistic extracting, as well as HEHEHP, has a superior selectivity to Zn(II) over Cd(II).

Facilitated transport of copper through bulk liquid membranes containing different carriers: compared kinetic study

The discharge of heavy metals into the environment is a serious problem facing numerous industries. Heavy metals tend to accumulate in living organisms causing various diseases and disorders. So the search for extraction techniques to remove those heavy metals are of increasing interest. Liquid membranes have shown great potential in this way, especially in cases where metal concentrations are relatively low and other techniques cannot be applied efficiently. A comparative kinetic study of the facilitated counter transport of copper ion through bulk liquid membranes containing D2EHPA, CYANEX 272 and LIX 984N as carriers and protons as counter ions is carried out is this paper. The transport kinetic was analysed by means of a kinetic model involving two consecutive irreversible first-order reactions. The rate constants of the extraction and stripping reactions and the maximum transport fluxes of copper(II) through the bulk liquid membrane were determined for the three carriers.

Kinetic Aspects of Copper‐LIX ® Extraction from Nitrate/Nitric Acid Aqueous Solutions

A comparative kinetic study of the extraction of copper from nitrate/nitric acid aqueous solutions by different classes of LIX ® reagents (LIX 984N, LIX 860N‐I, LIX 84‐I, LIX 65N) was performed. Using a Rotating Diffusion Cell, the rate constants of the chemical reactions (forward and reverse) were estimated and compared. In the case of the mixed extractant LIX 984N, a synergistic effect was observed. The values of the forward reaction constants of all the extractants were found to be an order of magnitude higher than those of the reverse reaction. The relatively low E a ‐values prove the substantial influence of the diffusion on the extraction kinetics under the experimental conditions studied.

Stabilization of supported liquid membranes by plasma polymerization surface coating

Plasma polymerization coating is shown to be an effective method for improving the stability of supported liquid membranes (SLM) containing LIX 984N for copper transport. Hexamethyldisiloxane and heptylamine were employed as monomers and hydrophobic microporous microfiltration membranes with pore sizes of 0.05–0.2 μm were used as substrates. Electronmicroscopy revealed that the plasma polymerization film mainly occurred on the surface of the microporous membranes. Preliminary results show that either coating can improve the stability of the polypropylene Accurel SLMs with a thickness of 150 μm. For a thin membrane such as the polypropylene Celgard 2500 with a thickness of 25 μm, the heptylamine coating on the stripping side provides better stability than on the feed side.

Performance and stability of supported liquid membranes using LIX 984N for copper transport

The transport of copper through supported liquid membranes (SLM) using Celgard and Accurel membranes as supports and a novel commercial extractant LIX 984N as a carrier was investigated. LIX 984N provides good overall transport performance for copper from the acidic and dilute solution to the concentrated copper sulfuric acid. The instability of the supported liquid membranes using Celgard 2500 as the membrane support has been studied. It has been demonstrated that initially the surface shear forces due to stirring are a main cause for membrane liquid loss leading to SLM instability. However, during long term permeation no single instability mechanism dominants. The instability of long term operation involves a complex interaction of a number of factors, including surface shear forces, Marangoni effects, changes to membrane morphology, Bernard instabilities and membrane preparation protocal.