Page 16 - Nov-Dec2017 Vol35 No5

2017 CONFERENCE TECHNICAL SESSION TENNESSEE By Tom McGill
Developing Markets for Scrap Tires

A discussion about developing markets 1 1. Solar panels & gasifier at
for scrap tires in Tennessee begins with waste water treatment basins
getting scrap tires to the processing 2 2. Rockwood Construction
facilities. Tennessee makes each county Recycling Shredder
responsible for the beneficial end use 34 3. Tire Derived Aggregate
of scrap tires generated in their county. 4. Porous rubber walkway
Tennessee counties currently have three that use these rubber products are material sample
options for their end of life tires: use becoming more prevalent; however, the 5. Cedars of Lebanon porous
Liberty Tire, use Patriot Recycling, or use rubber will require more processing and walkway installation
Rockwood Construction Recycling. at higher expense. These expenses can
be offset by increased prices per ton of 5
Tires go to the chosen processor to be processed rubber.
resold, if possible, or shredded into Tire to champion the use of scrap tires. The
Derived Fuel and/or Tire Derived Aggre- The TDA markets that incorporate tire use of TDA in civil engineering projects
gate. According to the U.S. Tire Manufac- aggregate used in civil engineering appli- has expanded in Minnesota and Vermont
turers Association, the TDF market used cations include septic field line backfill, because of engineers who are willing
117 million tires in 2015 (over 48 percent retaining wall backfill and soil stabiliza- to try new environmentally friendly
of the total annual scrap tire generation tion in road construction. To expand projects. The search is on for engineers
for the year). TDF requires a minimum these markets, engineers must be found in Tennessee who are willing to use these
amount of processing to become a prod- who trust the use of TDA and are willing proven applications for TDA.
uct for the fuel markets and TDF has a
high fuel value of approximately 12,000 Granulated rubber and ground rubber
to 16,000 BTU per pound. are two markets with the most potential
for growth in Tennessee. Porous walk-
TDF markets already exist in Tennes- ways that use rubber as a major compo-
see with at least two paper mills using nent of the construction are becoming
TDF for fuel to power their boilers as
well as one or more cement plants that
use tires as fuel for kilns. The TDF used
by the paper plants is currently obtained
from brokers that purchase specified
TDF from tire processors. Cement plants
have historically taken tires from local
vendors or municipalities.

Scrap tires are also used as alternative
fuel for the Lebanon Gasification Initia-
tive at the waste water treatment plant
located in Lebanon. The gasification
process consists of collecting and deliver-
ing waste made up of chipped wood,
treatment plant sludge, and shredded
tires to the gasifier. The waste is placed
into the gasifier and molecularly broken
down at temperatures in excess of 2,500
degrees Fahrenheit with little oxygen
present. This allows syngas to be created
and collected for use as fuel to power
the generators and as fuel for the heating
process. A byproduct of the process is
called biochar, which is all that remains
of the waste and is collected for use in
other areas.

The tire markets that have the most
potential for growth in Tennessee are
TDA products that include tire chips or
aggregate, granulated rubber and ground
rubber. The products and applications

16 TPW November/December 2017