Ecological Bricks

ELSEVIER

Applied Clay Science 11 (1996) 237-249

' Ecological bricks' made with clays and steel dust
pollutants
E duardo A. Domlnguez a,., Rosa Ullmann b,l
a

Departamento de Geologfa, Universidad Nacional del Sur, San Juan 670, 8000 Bahfa Blanca, Argentina
b L osa/Techint, Casilla de Correos 50, 7400 Olavarrfa, Argentina

Received 2 April 1996; revised 3 September 1996; accepted 3September 1996

Abstract
M ore than 27,000 tons of steel dust containing Zn, Pb, Cd, Ni and Cr are generated each year
b y two steel mills in Argentina. The waste can be classified as low-zinc carbon dust and its
t reatment is governed by environmental rather than economical considerations. The aim of this
w ork was to test the use of clays in the formulation of a ceramic body that couldincorporate steel
d ust and met environmental regulations. Once the raw materials were characterised, a ceramic
b ody was prepared in the laboratory and subjected to the EP-TOXIC leaching test. The ceramic
b ody passed this test. Based on these promising results a prototype of commercial brick
i ncorporating 20% steel dust was produced. The brick meets standard commercial regulations
b eing inertto the EP-TOXIC and full TCLP leaching tests and the ceramic process has low
e mission of dangerous gases. The addition of steel dust, reduces the firing temperature of the
c eramic process meeting the recycling EPA requirements for the disposal of hazardous waste.
Keywords: steel dust; pollutants; clay; ceramics

1. Introduction
A s a result o f the m e l t i n g process in electric arcfurnaces (EAF), m o r e than 27,000
t ons o f steel dust waste are generated e a c h y e a r in two steel mills in Argentina.
A c c o r d i n g to the regulations o f the E n v i r o n m e n t a l Protection A g e n c y (EPA), this waste,
d esignated as K 061, is c o n s i d e r e d hazardous. T h e waste generated in the m e l t i n g
p rocess is about 2% o f the product mass o f fine dustscontaining a w i d e variety o f

* Corresponding author. Fax: +54-91-556756/883933; e-mail: ghcraver@criba.edu.ar
i Fax: +54-284-93041.
0 169-1317/96/$15.00 Copyright © 1996 Elsevier Science B.V. All rights reserved.
P II SO 169- 1 3 17(96)00020-8

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E.A. Domlnguez, R. Ullmann / Applied Clay Science 11 (1996)237 249

e lements, including Zn, Pb, Cd, Ni and Cr among others.Consequently the disposal of
this material in dumps and landfills would produce water contamination.
T he main purpose of this work was to test the use of clays in the formation of a
c eramic body that could incorporate steel dust and meet the Argentinean environmental
laws based on the US-EPA regulations. Although many solutions have been proposed
f or the technical treatment of the steel dusts (Barczaand Nelson, 1990), in this case the
u se of ceramic and vitrification processes seems to be useful for making the dust
e nvironmentally friendly hence meeting the recycling EPA requirements, According to
t hese authors, the Argentinean waste can be classified as low-zinc ( < 15%) carbon steel
dust. Because of the low metal content it is not worth recycling it for metal recovery,
t herefore,its treatment is governed by environmental rather than economic considerations. The first step in this work was the determination of the physical and chemical
c haracteristics of the steel dust. Taking into account physical and chemical testing
results, ceramic test bars are made mixing the dust with different types of clay. Ceramic
a nd leaching tests are performed on these bodies. If theresults will be as expected, a
b rick could be produced on a pilot scale.
P revious work (Ek et al., 1992) concluded that vitrification of steel dust (K 061) is a
p rocess that could recycle this hazardous waste into an usable commodity. Using dust
f rom Oregon Steel Mills Ek et al. (1992) made an inert product, as defined by the USA
E PA toxic characteristics leaching procedures protocols...