Krasimir Dimitrov

Recovery of zinc from chloride media by batch pertraction in a rotating film contactor

A liquid membrane (pertraction) process of zinc recovery from acidic chloride solutions was studied applying a pertraction in a rotating film contactor (RFC). Tri-n-octylamine (TOA or R3N) dissolved in n-octane was used as a carrier. The influence of the main process parameters, such as disc rotation velocity, hydrochloric acid concentration in the aqueous phases and carrier concentration in the membrane was investigated. Assuming the existence of two thin reaction layers in the feed and stripping solutions, adjacent to both water–oil interfaces, a mathematical model was developed to describe the zinc transport. On the basis of the experimental data obtained under various conditions and the model proposed, it was found that the extraction step is controlled mainly by the mass transfer resistance, whereas the stripping rate of zinc is controlled predominantly by the rate of zinc–carrier complex decomposition in the stripping side reaction layer.

Separation of Cobalt and Nickel by Pertraction in a Rotating Film Contactor Using Cyanex 302 as a Carrier

Abstract The extraction behavior of Cyanex 272, Cyanex 301, and Cyanex 302 for recovery of cobalt and nickel from sulphate media was studied. Cyanex 302 was found to be the most suitable reagent for extraction of both metals and for Co(II)/Ni(II) separation. Competitive pertraction of Co(II) and Ni(II) in a rotating film contactor with Cyanex 302 as a carrier was studied. At appropriately chosen operational conditions Co(II) was preferentially removed, while Ni(II) remained in the feed solution. Pertraction process using Cyanex 302 as a carrier guarantees an excellent separation of Co(II) from Ni(II): the obtained separation factors are Ksep∼1.0×104. Higher pH of the feed solution favors the recovery of both metals, but deteriorates Co(II)/Ni(II) separation ability. At neutral pH of the feed solution and strongly acidic acceptor solution, pertraction process can be used for simultaneous and complete recovery of both metals, also.

Recovery of copper from solutions by rotating film pertraction

A liquid membrane (pertraction) process of copper recovery from dilute aqueous solutions is studied applying a rotating film pertraction technique. LIX 65®N dissolved in C10–C13 normal paraffins is used as the carrier. A mathematical model describing copper transfer is proposed, assuming that (1) the chemical reactions between copper ions and carrier molecules take place in the aqueous solution layers adjacent to the membrane phase, and (2) both the reaction kinetics and the mass transfer of the solutes control the overall rate of the process. In order to evaluate the reaction rate constants and the coefficients of mass transfer, the distribution coefficients for the active oxime carrier (mHR) and the copper-oxime complex (mCuR2) are obtained independently. The effects of temperature and disc rotation velocity on the pertraction rate are studied, as well as the possibility for the selective removal of copper from a solution containing ions of several bivalent metals.

Selective recovery of silver from dilute polymetal solutions by rotating film pertraction

Recovery of silver from polymetal nitrate solution by means of rotating film pertraction technique was studied. Silver was successfully separated from the accompanying metals, viz. copper, zinc and nickel, using as a membrane phase a 0.06-M solution of tri-isobutylphosphine sulfide (TIBPS) in n-octane and an aqueous ammonia solution as a stripping phase. After 4 h of continuous contacting silver was practically completely extracted from the feed and transferred into the strip solution, while the other three metals remained unextracted.