Primerjava učinkovitosti kemijske in metalurške metode za izločanje plemenitih kovin iz elektronskih odpadkov

Špec, Luka (author), Pevec, Andrej (mentor)

V svoji diplomski nalogi sem primerjal dve metodi izločanja plemenitih kovin iz elektronskih odpadkov z namenom ugotovitve, katera je bolj primerna za urbano rudarjenje, v kontekstu majhne predelovalne operacije. Prva metoda je kemijska metoda, pri kateri vzorec tretiramo s klorovodikovo kislino, dušikovo kislino in zlatotopko in iz pridobljenih raztopin izločimo željene produkte. Druga metoda je metalurška metoda, pri kateri vzorec zmešamo z boraksom, natrijevim karbonatom in bizmutovim prahom ter ga stalimo v električni peči, pri čemer dobimo sistem kovina- steklo, ki povzroči, da plemenite kovine v vzorcu preidejo v kovinsko fazo. Talino se nato prelije v kalup, loči kovino od žlindre in iz kovine izloči plemenite kovine s kupelacijo. Pridobljene produkte sem analiziral z metodo SEM/EDS. Želel sem pridobiti mase in sestave produktov, na podlagi katerih bi nato primerjal učinkovitost kemijske in metalurške metode. Poleg tega sem želel pridobiti odgovore na vprašanji, kako učinkovito je obarjanje kationov s specifičnimi reagenti in kako se porazdelijo elementi v sistemu kovina-steklo, ki nastane med taljenjem vzorca. Ugotovil sem, da obe metodi potrebujeta nadaljnje optimiziranje, da jih bo mogoče uporabiti, kot sem prvotno načrtoval. Pri kemijski metodi pridobljeni produkti niso dosegali zadovoljive čistoče, da bi lahko uporabil njihove mase za izračun izkoristkov, pri metalurški metodi pa mi ni uspelo uspešno izpeljati kupelacije, ki je ključen del te metode. Kljub tem neuspehom, sem prišel do številnih uporabnih ugotovitev, s pomočjo katerih menim, da bi bilo mogoče optimizirati oba postopka. Obarjanje kationov plemenitih kovin s specifičnimi reagenti obori veliko večino ciljnih ionov. S cementacijo lahko v ugodnih pogojih pridobimo produkt visoke čistoče. Talilo, sestavljeno iz boraksa in natrijevega karbonata in bizmut, kot zbiralna kovina, so primerni za moj tip vzorca.

• Language: Slovenian
• Keywords: elektronski odpadki, reciklaža, kemijska metoda, metalurška metoda
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2024
• PID: 20.500.12556/RUL-160223
• COBISS.SI-ID: 206024451
• Publication date in RUL: 23.08.2024

Secondary language

• Language: English
• Title: Performance comparison of chemical and metallurgical method of extraction of noble metals from electronic waste

Abstract

In my thesis, I compared two methods of extracting precious metals from electronic waste in order to determine which is more suitable for urban mining in the context of a small-scale processing operation. The first method is a chemical method in which the sample is treated with hydrochloric acid, nitric acid and aqua regia and the desired products are extracted from the obtained solutions. The second method is a metallurgical method in which the sample is mixed with borax, sodium carbonate and bismuth powder and melted in an electric furnace to produce a metal-glass system which causes the precious metals in the sample to pass into the metallic phase. The melt is then poured into the mold, separating the metal from the slag and extracting the precious metals from the metal by cupellation. The resulting products were analyzed using the SEM/EDS method. I wanted to obtain the masses and compositions of the products on the basis of which I could then compare the performance of the chemical and metallurgical methods. In addition, I wanted to obtain answers to the questions of how effective is the precipitation of cations with specific reagents and how the elements are distributed in the metal-glass system formed during the melting of the sample. I found that both methods needed further optimization in order to be able to use them as I originally planned. In the chemical method, the products obtained did not reach a sufficient purity to be able to use their masses for the calculation of recoveries, and in the metallurgical method, I failed to successfully perform the cupellation, which is a key part of this method. Despite these failures, I have come to a number of useful conclusions that I believe could be used to optimise both processes. Precipitation of precious metal cations with specific reagents precipitates the vast majority of target ions. Cementation under favourable conditions can yield a high purity product. A flux composed of borax and sodium carbonate with bismuth as a collector metal are suitable for my type of sample.

• Keywords: electronic waste, recycling, chemical metod, metalurgical metod