Tyre Asia – May-June 2018

86 Tyre Asia April/May 2018

One of the major concerns facing tyre recyclers is how to eliminate

environment contaminating zinc from products of waste tyre

pyrolysis. Researchers at Poland’s Nicolaus Copernicus University,

led by Prof Jerzy P Lukaszewiczhas, have found a way out

by developing a process to eliminate zinc from environmental

circulation during tyre pyrolysis. They have proposed an

alternative solution to transform pyrolytic char into activated

carbon. The researchers say that the raw post-pyrolytic chars

provide highly energetic fuel for the production of heat and/or

electrical energy, which is more competitive than converting them

into activated carbon. Such chars should be burned separately

with an excess of oxygen in heat/electricity generators. The

resulting ash, which has very high zinc content, could be saved

for metallurgical conversion to metallic zinc. This could lead to

the annual recovery of thousands of tonnes of zinc and/or its

derivatives and eliminate them from the environment. In this

interview to Tyre Asia, the research head elaborates on their work

Safe zinc recover y

from pyrolysis char

Can you explain the main

focus of your research on tyre

pyrolysis?

It is an obvious fact that the reuse of old

tyres is an emerging worldwide problem. The

annual number of old tyres, which must be

disposed of in an environment-friendly way,

is huge. Besides just burning of old tyres for

energy purposes, the pyrolysis of tyre rubber

is the second main objective of utilization.

Traditionally, old rubber from tyres is

subjected to heat treatment in a controlled

mode. Three basic products are derived out

of it: burnable gas, crude oil resembling

liquid and a solid by-product i.e. a pyrolytic

char. The gas may be utilized on the spot

as a heating medium to power the pyrolysis

process itself. The pyrolysis oil may be

converted to valuable chemicals, including

gasoline etc. But what about the char?

The char is a real problem since its mass

is ca. 40% of the mass of the rubber that is

subjected to pyrolysis. Usually, the char has

poor surface properties such as very low

specific surface area like 40-50 sq metre

per gram. Any conversion of such chars

into a carbon-type adsorbent (expected

surface area is ca. 500-1500 sq metre per

gram) is a versatile but expensive process.

To my opinion it is senseless due to these

technological and economic barriers. From

the beginning, our research was focused

on finding new recycling scenarios for this

troublesome by-product i.e. pyrolytic char.

The new pyrolysis concept was developed

at Nicolaus Copernicus University of Torun

(Poland).

As your process eliminates

zinc, a major environmental

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