Rice Hull Silica, A Silicon Carbide Precursor For Collagen, Lignin And Silicon Metal Powder Bindered Anthracite Briquettes
Open Access
- Author:
- Jiles, Allura Marie
- Graduate Program:
- Environmental Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- February 04, 2013
- Committee Members:
- Fred Scott Cannon, Thesis Advisor/Co-Advisor
Sridhar Komarneni, Thesis Advisor/Co-Advisor - Keywords:
- Anthracite
Lignin
Rice hull
Silicon Carbide
Nanowire
Silica rod - Abstract:
- Foundry coke is currently the primary energy source of U.S. iron foundries employing cupolas to produce iron. The availability, cost and environmental impact of this fuel usage limit the production of iron. The replacement of foundry coke with bindered anthracite fines reduces costs and negative environmental impact while allowing for the increase in iron production. Others have shown that anthracite fines bindered with collagen (which provides strength from ambient temperatures to 400oC), lignin (which provides strength between 400oC and 1200oC) and silicon metal (which provides strength at temperatures in excess of 1200oC) can serve as a partial foundry coke substitute. Silicon metal provides strength at high temperature by reacting with carbon present in the briquette to form interlocking networks of silicon carbide nanowires that originate on the surface of anthracite grains. Whereas others have shown that silicon metal could serve as a precursor for silicon carbide in bindered anthracite briquettes, the aim of this work was to determine whether rice hull derived silica offered potential as a silicon carbide precursor for collagen and lignin bindered anthracite briquettes. Rice hulls and rice hull char, waste products of the rice industry, are inexpensive and abundant resources of oxidized silicon. Upon pyrolysis in a tube furnace at 1550oC, silicon carbide formation occurred in samples via vapor phase reactions involving silicon monoxide gas. Silicon carbide nanowires readily formed during the pyrolysis of rice hulls and rice hull char when anthracite was employed as an oxygen scavenger. Silicon carbide nanowires also formed during the pyrolysis of rice hull char without an oxygen scavenger. Rice hull char yielded more silicon carbide than rice hulls, per unit mass, under the same pyrolysis conditions. Silicon carbide also formed during the pyrolysis of anthracite bindered briquettes containing collagen, lignin, rice hulls and rice hull char, when anthracite was employed as an oxygen scavenger. Silicon carbide product formations predominantly occurred on the external surface of the briquettes and this external product formation increased with increasing compression force and silica concentration, as well as decreasing anthracite grain size. White rice hull ash served as a poor sole silicon carbide precursor for collagen and lignin bindered anthracite briquettes, yielding minimal silicon monoxide gas; but its use resulted in the formation of a variety of silica rods on the surfaces of internal anthracite grains.