Gasification of spent pot-lining from the aluminum industry

Isam Janajreh,Sherien Elagroudy,Idowu Adeyemi,Syed Shabbar Raza,Chaouki Ghenai,Konstantinos Moustakas

doi:10.1007/s42452-021-04384-z

Abstract

Aluminum production generates enormous spent pot lining (SPL) waste of around one million tons yearly, and these wastes are usually disposed in landfills. Hence, the technical feasibility of SPL gasification using both equilibrium and reactive high-fidelity modeling was evaluated in this study. Three SPL with different washing treatment, i.e., water (WWSPL), acid treated (ATSPL), and full treated (FTSPL, a combination of both water and acid washing) were used for the modeling. The equilibrium model considered twelve species, while the high-fidelity simulation was modeled with multiple species. Moreover, the high fidelity model is governed by the steady non-isothermal Navier–Stokes equation coupled with the discrete phase in Eulerian–Lagrangian scheme. The process metrics were assessed via the produced syngas fraction (CO/H2) and gasification efficiency (GE). The equilibrium analysis of WWSPL, ATSPL, FTSPL, respectively, resulted in GE of 40, 65, and 75%. The corresponding syngas molar fractions for CO and H2 were 0.804 and 0.178 at 1450 °C; 0.769 and 0.159 at 1100 °C; and 0.730 and 0.218 at 1150 °C. These results suggest the potentiality and feasibility of gasifying the treated SPL, which was considered in the high-fidelity. Although the results show different trend from equilibrium for the FTSPL gasification (i.e., small molar fraction of CO2 and H2O and high syngas fraction dominated by CO at 0.75 and 0.1 H2 at best GE of 70%), it re-emphasizes the potential of the gasification of FTSPL as recyclable/renewable energy source.Graphical abstract

Highlights

The notion of reuse, recycle, and reduce is suited for almost all streams of solid waste; including municipal solid waste as well as many streams of industrial wastes
Gasification is suited for coal, biomass, and other streams of solid waste based on consideration of the fixed carbon as well as the volatile contents of the candidate feedstock
Aluminum industry produces an alarming and increasing amount of hazardous, non-recyclable, solid waste known as spent pot lining that grew to 1Mt annually

Summary

Introduction

The notion of reuse, recycle, and reduce is suited for almost all streams of solid waste; including municipal solid waste as well as many streams of industrial wastes. Aluminum industry produces a large amount of industrial solid waste such as the pre-baking anode electrolytic bath, its impermeable silicon carbide, the electrolyzed slag of the used cathode carbon block and the insulation side of the refractory brick [3]. These waste streams are on the rise due to the massively growing aluminum industry, and they are either illegally landfilled or stockpiled. Over an operational period of 3 to 8 years, the cathode becomes polluted with fluoride salts and other process additives that halt its function This mandates the removal of the carbon cathode potlining or SPL and re-lining the shell. It is estimated that the generated amount of the SPL is between 18 and 35 kg per ton of alumina; that mounts to nearly 1Mt annually [6, 7] with large amounts stockpiled

Methods

Results

Conclusion