Improving the quality of waste-derived char by removing ash

Abstract

This study characterized and removed ash from waste-derived char to improve the quality of char as fuel. Municipal solid waste (MSW) and automobile shredder residue (ASR) were carbonized at 450 o C and at 500 o C respectively in a rotary kiln with a nitrogen atmosphere for 1 h. MSW and ASR char were subjected to sieving and pulverization-sieving to screen incombustibles and the ash-rich fraction, after which float-sink separation, froth floatation, and oil agglomeration were applied to remove ash from the char. The established target quality was less than 30% ash content and more than 20000 kJ/kg heating value. However, the rate of combustibles recovery had to be lowered to produce a good quality of char along with a high heating value. MSW char attained the targeted quality level using froth floatation or oil agglomeration whereas neither separation method was able to make ASR-derived char satisfy the target.Based on the assumption that particle properties of char are determined by the weight ratio of combustibles and ash, the densities of combustibles and ash in char were estimated using the results of float-sink separation, X-ray diffraction (XRD) analysis, and elemental content. To verify the above assumption, an energy dispersive X-ray/scanning electron microscope (EDX/SEM) analyzer was used to observe char particles.

Biosorption of heavy metals by lignocellulosic biomass and chemical analysis

“…Biochar can be produced from a variety of feedstock materials, such as industrial by-products, and agricultural and forest residues, but even from unconventional materials, such as municipal solid waste (Hwang et al 2008), food waste (Rhee and Park 2010), newspapers (Li and Zhang 2004), and bones (Dimović et al 2011). Additionally, biochar can be produced from animal waste, such as poultry litter and dairy manure (Duku et al 2011).…”

Opportunities and constraints for biochar technology in Australian agriculture: looking beyond carbon sequestration

“…Large-scale production of biochar from urban waste may be helpful in reducing the cost of biochar production; however, because of the presence of potential contaminants, a proper regulatory framework is required to avoid possible risks of soil contamination. Toxic metal loadings in urban feedstocks may be manipulated through selective removal of ash (Hwang et al 2008). Similarly, biochar from urban greenwaste (lignocellulose) has been evaluated and has shown promising effects on: soil physical properties in glasshouse experiments with radish (Chan et al 2007), reductions in N 2 O emissions in field experiments (Felber et al 2014), and chemical properties similar to activated C through slow pyrolysis of a variety of municipal wastes at 4808C (Mitchell et al 2013).…”

Recovering molybdenite from ultrafine waste tailings by oil agglomerate flotation

“…The basic principles of oil agglomeration and effects of various operating parameters have been investigated by many researchers, and the technique has been used in the mineral industry for the purification of coal from sulphur and ashes (Mehrotra et al, 1983;Laskowski and Yu, 2000;Gray et al, 2001;Aktas, 2002;Alonso et al, 2002;Cebeci andSönmez, 2002, 2006;Sahinoglu and Uslu, 2008), recovery of fine sized gold from ores (Moses and Petersen, 2000;Sen et al, 2005;Valderrama and Rubio, 2008), agglomeration of oxide such as barite Cebeci, 2003a, 2004), calcite (Sönmez and Cebeci, 2003b;Cebeci and Sönmez, 2004a) and celestite (Cebeci and Sönmez, 2004b) for the separation process, improving the quality of waste-derived char (Hwang et al, 2008), removal of impurities from wastewater (Huang and Fang, 2001;Kang and Shin, 2006) and de-inking of paper (Azevedo and Miller, 2000).…”