Removal and Recovery of Metals from Municipal Solid Waste Incineration ashes by a Hydrometallurgical Process
Doktorsavhandling, 2017

Municipal Solid Waste Incineration (MSWI) fly ash contains significant amounts of leachable metals, and is therefore considered to be a hazardous waste. The increased amounts of fly ash generated cause environmental issues, management costs and accumulation of valuable metals in landfills. All these factors contribute to an increased interests to recognize the ash as an urban mining target of metal resources. Metals recovery, e.g. copper, zinc from fly ash, is not only beneficial for the availability of valuable metals that otherwise would be lost, but it can also decrease the amount of potentially soluble and toxic metal compounds in the ash residue,  making it possible to landfill the ash at a lower cost. A hydrometallurgical process for recovery of copper and zinc from MSWI ash is presented in this thesis. A process consisting of leaching followed by sequential solvent extraction of metals was developed. With respect to leaching efficiency and feasibility, it was found that hydrochloric acid is the best option for recovery if copper and zinc from the fly ash, in addition, efficient leaching of cadmium and lead was also achieved. LIX860N-I, a commercial extractant was chosen for the copper extraction. No third phase formations or phase separation problems were observed. The copper extraction gave a good extraction yield with high selectivity. The extracted copper in organic phase can be stripped in a one stage process using a selected sulfuric acidic solution (1.5M). Zinc extraction followed the copper extraction by extracting the raffinate using Cyanex 272, Cyanex 572 or Cyanex 923. Cyanex 923 showed the highest efficiency and no pH adjustment of the aqueous phase was needed. However, this extractant co-extracts iron, cadmium and lead with the zinc. Cyanex 572, a novel phosphorus-based chelating extractant is less effective, but more selective for zinc extraction compared to Cyanex 923.  Selective stripping processes were suggested for zinc extraction using Cyanex 572 and Cyanex 923 respectively. Laboratory pilot scale experiments using mixer-settler systems were carried out based on the batch experiment results. McCabe Thiele diagrams were used to model the processes with respect to the number of stages needed for conducting the extractions in mixer-settler systems. The solvent extraction process was then demonstrated in pilot size mixer settler equipment consisting of two stages for copper extraction and three stages for zinc extraction and gave a recovery of 90% of the copper and ~100% of the zinc in the leachate.

MSWI ash

Cyanex 572

leaching

zinc

Cyanex 923

solvent extraction

LIX860N-I

copper

mixer-settler

KC-salen, Kemigården 4, Chalmers.
Opponent: Dr. Lisbeth M. Ottosen, Department of Civil Engineering, Technical University of Denmark, Denmark.

Författare

Jinfeng Tang

Kemi och kemiteknik, Energi och material, Kärnkemi

Resource recovery from municipal solid waste ash

Abstract of Papers of the American Chemical Society,; Vol. 247(2014)

Konferensbidrag (offentliggjort, men ej förlagsutgivet)

Solvent extraction separation of copper and zinc from MSWI fly ash leachates

Waste Management,; Vol. 44(2015)p. 147-154

Artikel i vetenskaplig tidskrift

Mixer-settler system for the recovery of copper and zinc from MSWI fly ash leachates: An evaluation of a hydrometallurgical process

Journal of Cleaner Production,; Vol. 148(2017)p. 595-605

Artikel i vetenskaplig tidskrift

Comparative study of the application of traditional and novel extractants for the separation of metals from MSWI fly ash leachates

Flygaskan från avfallsbränningsanläggningar innehåller betydande mängder av lakbara metaller och måste därför deponeras på specialdeponi för farligt avfall. I denna avhandling presenteras en hydrometallurgisk process där koppar och zink återvinns från flygaska. Processen består av lakning följt av sekventiell lösningsmedelsextraktion av metaller. Med avseende på lakningens effektivitet och genomförbarhet visade det sig att saltsyra är det lämpligaste alternativet för utvinning av koppar och zink från flygaska. Dessutom har effektiv urlakning av kadmium och bly också uppnåtts. Resultat från experiment i laboratorieskala upp till test i mixer-settlers i pilotskala visar ett nästintill linjärt beroende vilket är lovande för ytterligare uppskalning till industriell skala.

Municipal Solid Waste Incineration (MSWI) fly ash contains significant amounts of leachable metals, and therefore has to be landfilled in special landfill for hazardous waste. A hydrometallurgical process for the recovery of copper and zinc from MSWI ash is presented in this thesis. The process consists of leaching followed by sequential solvent extraction of metals. With respect to leaching efficiency and feasibility, it was found that hydrochloric acid is a suitable option for recovery of copper and zinc from the fly ash. In addition, efficient leaching of cadmium and lead was also achieved. Pilot scale experiments using mixer-settler systems were carried out based on the batch experiment results, since mixer settlers show a near linear scale up behavior, these results are promising for further scale up to industrial scale.

Drivkrafter

Hållbar utveckling

Styrkeområden

Produktion

Energi

Livsvetenskaper och teknik

Ämneskategorier

Analytisk kemi

Kemiska processer

Annan kemi

ISBN

978-91-7597-538-2

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4219

Utgivare

Chalmers tekniska högskola

KC-salen, Kemigården 4, Chalmers.

Opponent: Dr. Lisbeth M. Ottosen, Department of Civil Engineering, Technical University of Denmark, Denmark.