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

• Main Authors: DE MICHELIS, IDA, FERELLA, FRANCESCO, VEGLIO, FRANCESCO, TORO, LUIGI, VARELLI, ENIO, BEOLCHINI, FRANCESCA, PAGNANELLI, FRANCESCA
• Format: Patent
• Language: English; Serbian
• Published: 31.08.2012
• Subjects: CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATERTREATMENT OR WASTE MANAGEMENT; DISPOSAL OF SOLID WASTE; FERROUS OR NON-FERROUS ALLOYS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; METALLURGY; PERFORMING OPERATIONS; PRETREATMENT OF RAW MATERIALS; PRODUCTION AND REFINING OF METALS; RECLAMATION OF CONTAMINED SOIL SOIL; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

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). I prahovi katodnih cevi (CRT) i prahovi svetiljki, nakon izdvajanja iz elektronske/električne opreme (EEE) i eventualno nakon prethodne obrade (kao prahovi katodnih cevi CRT koji zahtevaju termičku obradu za poboljšanje ponovnog dobijanja cinka) obrađuju luženjem sumpornom kiselinom. Ovi prahovi mogu se obrađivati odvojeno ili obrađivati međusobno pomešani. Itrijum rastvoren u rastvoru se ponovo dobija taloženjem sa oksalnom kiselinom, pri čemu je sušeni oksalat itrijuma prilično čist (oko 96%). Ovaj sastav se isto tako može žariri na 800-1000°C za proizvodnju itrijum oksida.Itrijum se direktno ponovno dobija iz rastvora luženja (tečna lužina) kada su u postupku prahovi fluorescentnih svetiljki obrađivani sami, pri čemu, kada su ovi prahovi pomešani sa prahovima katodbnih cevi (CRT), ili kada se prahovi poslednjeg obrađuju sami, pre ponovnog dobijanja Y potrebno je ukloniti/ponovno izdvojiti cink. Postupak ponovnog dobijanja Zn se sastoji u prvoj operaciji od bazifikacije natrijum karbonatom (soda) do vrednosti pH 4, nakon čega se Zn taloži dodavanjem natrijum sulfida (Na2S), proizvodeći cink sulfid (ZnS). Osim toga, Zn se može ponovo dobijati elektro-dobijanjem, gde prisustvo itrijuma neće dovesti do smanjenja efikasnosti postupka,Ponovno dobijanje Y i Zn može se izvršavati pokretnim (mobilnim) postrojenjem (diskontinualni, periodični proces):- 1 reaktor u kojem se izvršava glavna operacija (luženje ili neutralizacija ili taloženje);- 1 ploča i filter sa okvirom da razdvoje čvrsto od tečnosti;- 1 reaktor koji radi kao veštačka pluća da primi filtrat.