A. A. Blokhin

Ion-exchange recovery of palladium(II) from multicomponent chloride solutions

Ion-exchange sorption of palladium(II) from both concentrated aqueous hydrochloric acid solution containing Fe(III), Sn(II), Zn(II), and Cu(II) and weakly acidic concentrated aqueous ammonium chloride solution containing Zn(II) and Cu(II) was studied. The Purolite S920, Purolite S924, and Purolite S984 macroporous resins with the thiourea, thiol, and polyethylenepolyamine functional groups, respectively, were used as sorbents. Strongly basic Purolite A500 anion exchanger was also tested. The desorption of palladium(II) with aqueous ammonia, hydrochloric acid, and acidified aqueous thiourea was examined.

Specific features of rhenium desorption from weakly basic anion exchangers Purolite A170 and Purolite A172 with ammonia solutions

Equilibrium, kinetics, and dynamics of rhenium desorption from weakly basic macroporous (Purolite A170) and gel anion (Purolite A172) exchangers with ammonia solutions were studied. The effective diffusion coefficients of rhenium in its desorption from these anion exchangers and the activation energy of rhenium desorption from the gel anion exchanger were estimated.

Use of Ion-Exchange Resins To Deal with the Effect of Preg-Robbing of Gold in the Course of Cyanide Leaching

Possibility of using strongly basic anion exchange resin of MINIX brand and weakly basic anion exchange resin Purogold S992 brand in the high-temperature- caustic conditioning (HiTeCC) technological process for diminishing the loss of gold via adsorption on natural organic carbon-containing substances (pregrobbing phenomenon) in the course of cyanide leaching was studied. It was shown that the strongly basic anion exchanger MINIX has a higher affinity for the anion [Au(CN)2]−, compared with the microporous activated carbon WSC-207C-GR. As a result, the adsorbed dicyanoaurate(I) anion is transferred from the activated carbon to the ion-exchange resin. Reasons for binding of the dicyanoaurate(I) anion with active centers of activated carbons are considered, based on the fact that the adsorbent contains carbene-like carbon atoms. The existence of paramagnetic centers belonging to carbon atoms in the activated carbon was demonstrated by the EPR method. The suggested concept was used to diminish the loss of gold via partial oxidation of metallic gold in autoclave processing of pyrite- and arsenopyrite-containing concentrates.

Kinetics of rhenium sorption from weakly basic macroporous and gel anion exchangers Purolite A170 and Purolite A172 from sulfuric acid solutions

Effect of the grain size of anion exchangers, agitation intensity, and temperature on the kinetics of rhenium sorption on weakly basic macroporous and gel anion exchangers Purolite A170 and Purolite A172 from a 1 M H2SO4 solution was studied.

Kinetics of platinum(II) and platinum(IV) sorption from hydrochloric acid solutions with a complexing ion exchanger containing thiourea functional groups and with a strongly basic anion exchanger

The kinetics of platinum(II) and platinum(IV) sorption from 2 M HCl with Purolite S920 complexing ion exchanger containing thiourea functional groups and Purolite A500 strongly basic anion exchanger was studied in relation to the resin granule size, stirring intensity, and temperature.

An increase in purity of ammonium perrhenate solutions with respect to molybdenum(IV) with the sorption recovery of rhenium(VII) from Mo-containing solutions

The possibility of the additional purification of ammonia rhenium desorbates with respect to molybdenum in the course of the sorption recovery of rhenium from Mo-containing solutions with the help of Purolite A170 and Purolite A172 weak base anion-exchange resins is considered. The pH-dependence of sorption of Re(VII) and Mo(VI) on these anion-exchange resins is investigated in static conditions with the 1 M (NH4)2SO4 background in the solution. It is shown that the range of pH, in which anion-exchange resins retain the ability to sorb Re(VII), is also spread to a weakly basic region. A substantial decrease in the adsorption of Re(VII) starts already with an increase in pH above 7.5. The capacity of anion-exchange resins with respect to Mo(VI) starts to decrease noticeably with an increase in pH of solutions above 5.0, and molybdenum almost ceases to sorb by both anion-exchange resins upon reaching pH ~ 7.0. In order to decrease the Mo(VI) content in rhenium desorbates with the sorption recovery of Re(VII) from Mo-containing solutions on weak base anion-exchange resins, the following flowsheet is suggested. Initially, the main amount of sorbed Mo(VI) is desorbed by contacting the saturated anion-exchange resin with the ammonium sulfate solution upon mixture stirring and holding constant pH of the solution in limits of 7.0–7.5 due to the addition of dosed amounts of ammonia solution. Then anion-exchange resin is separated from the ammonium sulfate solution containing Mo(VI), washed with water, and Re(VII) is desorbed by ammonium solution in dynamic conditions. The verification of the proposed method for the resins saturated by sorption from the model solution of the composition, g/L, 98 H2SO4, 4 Mo(VI), and 0.5 Re(VII) showed the occurrence of desorption of no less than 90% sorbed molybdenum during the treatment of anion-exchange resins with ammonium sulfate solution. Herewith, concentration ratio Re(VII) : Mo(VI) in ammoniacal rhenium desorbates when using A170 anion-exchange resin increases 11-fold and when using A172 anion-exchange resin, it increases 20-fold compared with that attained without the additional washing of Mo(VI). Losses of Re(VII) with the Mo-containing desorbate (reversible) do not exceed 5.2% of the amount of sorbed Re(VII).

Sorptive separation of molybdenum(VI) from rhenium-containing solutions

It is shown that Purolite S957 cation-exchange resin containing phosphonic-acid and sulfonic groups is capable of selectively sorbing molybdenum(VI) in the presence of rhenium(VII) in solution.

PURITY UPGRADE OF AMMONIUM PERRHENATE SOLUTIONS IN RESPECT OF MOLYBDENUM (VI) AT SORPTION RECOVERY OF RHENIUM (VII) FROM SOLUTIONS CONTAINING MOLYBDENUM (VI)

The study covers the method of additional cleaning of ammonium perrhenate desorbates from molybdenum through sorption recovery of rhenium from Mo-containing solutions with Purolite A170 and A172 weak base anion exchange resins. The dependence of Re(VII) and Mo(VI) sorption using these resins on solution pH was studied under static conditions with the 1 M (NH 4 ) 2 SO 4 solution. It was found that the pH range at which the resins retain the ability of Re(VII) sorption extends to a weak-alkaline area. A significant decrease in Re(VII) adsorption begins when pH exceeds 7,5 Mo(VI) capacity of the resins decreases significantly when solution pH exceeds 5,0, and both anion exchange resins practically stop molybdenum sorption at above pH ~ 7,0. Reduction of Mo(VI) content in rhenium desorbates obtained in sorption recovery of Re(VII) from Mo-containing solutions with weak base anion exchange resins can be achieved as follows. First, major quantity of adsorbed Mo(VI) is desorbed from the loaded resin by ammonium sulfate solution when stirring the mixture and keeping pH constant in the 7,0–7,5 range by dosing the ammonia solution. Then the resin is separated from the Mo(VI)-containing ammonia solution, washed with water, and Re(VII) is desorbed by the ammonia solution in dynamic conditions. The proposed method was verified with anion exchangers loaded in sorption from the model solution with the following composition, g/L: 98 H 2 SO 4 , 4 Mo(VI), 0,5 Re(VII). It was shown that resin treatment with the ammonium sulfate solution removes at least 90 % of adsorbed molybdenum. A ratio of Re(VII) to Mo(VI) concentrations in ammonium perrhenate desorbates increases by 11 times with Purolite A170 resin, and by 20 times with Purolite A172 resin compared to the results obtained without an additional Mo(VI) washing. Re(VII) losses (reversible) with the Mo-containing desorbate are below 5,2 % of the adsorbed Re(VII) amount.

Sorption purification of sodium molybdate solutions to remove vanadium(V) impurity

Possibility of performing deep purification of concentrated sodium molybdate solutions to remove vanadium(V) impurity by selective sorption of vanadium(V) from the solutions with fixed pH values on a strong base anion exchange resin Purolite A500/2788 was demonstrated.