Supplementary cementitious material and method for disposing of electric-arc furnace dust (EAFD)

A cementitious additive containing electric-arc furnace dust (EAFD) and a precursor as a replacement for up to 30% of the cement in concrete without adversely affecting the setting time of the concrete, said additive consisting of:

• about 50 wgt. % EAFD and about 50 wgt. % of precursor and wherein said precursor consists of 65 wgt. % silica, about 15 wgt. % lime, about 3.5 wgt. % soda, about 10.5 wgt. % potash, about 4 wgt. % alumina and about 2 wgt. % magnesia.

A method for disposing of electric-arc furnace dust (EAFD) comprising the steps of forming a mixture of about 50 wgt. % electric-arc furnace dust (EAFD) and 50 wgt. % of a precursor and wherein said precursor contains at least about 55 wgt. % silica, about 10 to 20 wgt. % lime, about 2 to 5 wgt. % soda, about 5 to 15 wgt. % potash, about 2 to 6 wgt. % alumina and about 1 to 3 wgt. % magnesia;

• homogenizing said EAFD and said precursor by grinding one of said EAFD and said precursor having larger particles than the other until said EAFD and said precursor have about equal size particles;
• and
• feeding said homogenized EAFD and said precursor into a kiln at about 1000° C. and rotating for about 30 minutes to form a new insoluble phase of zinc and lead and adding about 5 wgt. % of the resulting mixture to about 16.5 wgt. % of cement and about 72 wgt.% of coarse and fine aggregates and 6.5 wgt. % water and mixing to form concrete without adversely effecting the setting time.

A method for disposing of electric-arc furnace dust (EAFD) consisting of the steps of forming a mixture of about 50 wgt. % electric-arc furnace dust (EAFD) and 50 wgt. % of a precursor and wherein said precursor contains about 55 wgt. % silica, about 10 to 20 wgt. % lime, about 2 to 5 wgt. % soda, about 5 to 15 wgt. % potash, about 2 to 6 wgt. % alumina and about 1 to 3 wgt. % magnesia;

• homogenizing said EAFD and said precursor by grinding one of said EAFD and said precursor having larger particles than the other until said EAFD and said precursor have about equal size particles;
• and
• feeding said homogenized EAFD and said precursor into a kiln at about 1000° C. and rotating for about 30 minutes to form a new insoluble phase of zinc and lead and adding about 5 wgt. % of the resulting mixture to about 16.5 wgt. % of cement and about 72 wgt. % of coarse and fine aggregates and 6.5 wgt. % water and mixing to form concrete without adversely effecting the setting time.