RECOVERY OF BASIC AND PRECIOUS METALS FROM THE FLUORESCENT POWDERS AND PLANT FOR RECOVERY THEREOF

摘要

Invention herewith described refers to the recovery of basic and precious metals from the fluorescent powders and plant for recovery thereof. The powders from the cathode ray tube (CRT) and powders from lights, after separation from the electronic/electrical equipment (EEE) and possibly after a pre-treatment (as a cathode ray tube CRT powders that require heat treatment for the improvement of zinc recovery) are processed by the sulphuric acid leaching. These powders can be processed either separately or mixed together. Yttrium dissolved in the solution is again obtained by precipitation with oxalic acid; whereat the dried yttrium oxalate is fairly clean (about 96%). This composition can also be annealed at the temperature of 800-1000°C for the production of yttrium oxide.Yttrium is again obtained directly from the leaching solution (liquid lye) when in the process the fluorescent light powders are processed alone, whereat, when these powders are mixed with the cathode ray tube (CRT) powders or when the powders of the latter are processed alone, prior to reobtaining Y, it is necessary to remove/recover zinc. The process of Zn recovering in the first operation includes basification of sodium carbonate (sodium) to pH 4, after which Zn is precipitated by adding sodium sulphide (Na2S), produces zinc sulphide (ZnS). Besides, Zn may be reobtained by electro-acquisition, where the presence of yttrium will not lead to a reduced effectiveness of the procedure,The recovery of Zn and Y can be done by the movable plant:- 1 reactor, in which the main process (leaching or neutralization or precipitation) is executed;- 1 plate and filter with the frame for separation of solid components from the liquid;- 1 reactor to receive filtrate operating as the reservoir of the apparatus for artificial respiration (so-called artificial lung).