‘Ecological bricks’ made with clays and steel dust pollutants

More than 27,000 tons of steel dust containing Zn, Pb, Cd, Ni and Cr are generated each year by two steel mills in Argentina. The waste can be classified as low-zinc carbon dust and its treatment is governed by environmental rather than economical considerations. The aim of this work was to test the use of clays in the formulation of a ceramic body that could incorporate steel dust and met environmental regulations. Once the raw materials were characterised, a ceramic body was prepared in the laboratory and subjected to the EP-TOXIC leaching test. The ceramic body passed this test. Based on these promising results a prototype of commercial brick incorporating 20% steel dust was produced. The brick meets standard commercial regulations being inert to the EP-TOXIC and full TCLP leaching tests and the ceramic process has low emission of dangerous gases. The addition of steel dust, reduces the firing temperature of the ceramic process meeting the recycling EPA requirements for the disposal of hazardous waste.