RFCS project Fines2EAF

Cement-free brick production technology for the use of primary and secondary raw material fines in EAF steelmaking

Summary

Recent years have seen a world-wide chan­ge in the envi­ron­men­tal poli­cy towards inte­gra­ted pol­lu­ti­on pre­ven­ti­on and con­trol, taking into account all envi­ron­men­tal media. It is esti­ma­ted that steel-making acti­vi­ties in Euro­pe pro­du­ce about 80 mil­li­on ton­nes annu­al­ly of by-pro­ducts and was­te, equi­va­lent to half of the Euro­pean steel pro­duc­tion, of which more than 10 mil­li­on ton­nes is was­te for dis­po­sal. This was­te of resour­ces and land area is not sus­tainable and has to be decreased in the future.
The Fines2EAF pro­ject aims to increase the value of steel­ma­king resi­dues by inter­nal recy­cling and (re)use in the form of cement-free bricks. The bene­fit of this stra­tegy is three­fold: impro­ved uti­liza­ti­on of resi­dues, inter­nal reco­very of metals and reduc­tion of the amount of dum­ped mate­ri­als. Through demons­tra­ti­on by ope­ra­tio­nal tests the tech­no­lo­gy of cement-free bricks could beco­me more accep­ta­ble for the steel works.
The approach fol­lo­wed is the deve­lo­p­ment of an inno­va­ti­ve pro­cess to pro­du­ce cement-free bricks on the basis of pri­ma­ry and secon­da­ry raw mate­ri­al fines, alter­na­ti­ve bin­der sys­tems and a hydrau­lic stamp press. The bricks have to pos­sess suf­fi­ci­ent cold com­pres­si­on strength for low-abra­si­on hand­ling and, for self-redu­cing bricks, suf­fi­ci­ent reduc­tion beha­viour and metall­ur­gi­cal per­for­mance. To achie­ve the­se goals the fun­da­men­tal under­stan­ding of the bricks, their manu­fac­tu­ring and their sub­se­quent use in the EAF is necessary.
Pro­ject acti­vi­ties will deve­lop methods, pro­ces­ses and solu­ti­ons for:

  • eco­no­mic (re)using of low volu­me pri­ma­ry and secon­da­ry raw mate­ri­al fines in EAF steelmaking
  • clo­sing inter-sec­to­ral mate­ri­al loops within the EAF steel­ma­king rou­te by pro­duc­tion of tail­or-made high qua­li­ty char­ge mate­ri­als for the EAF
  • reco­very of metals in secon­da­ry raw mate­ri­al fines
  • redu­cing the amount of was­te mate­ri­als, envi­ron­men­tal impact and saving cos­ts of raw materials.

This pro­ject is aimed at the (re)use of pri­ma­ry and secon­da­ry raw mate­ri­al fines in EAF steel­ma­king and con­ser­va­ti­on of resour­ces by deve­lo­p­ment of cement-free brick pro­duc­tion tech­no­lo­gy, to be appli­ed direct­ly insi­de the steel plant. The deve­lo­p­ment of the pro­po­sed tech­no­lo­gy will bring the fol­lo­wing advan­ta­ges: avo­id dis­po­sal of was­tes, enhan­ce the use of pri­ma­ry raw mate­ri­al fines and the recy­cling of secon­da­ry raw mate­ri­al fines for steel pro­duc­tion, save cos­ts, and redu­ce the envi­ron­men­tal impact of the steel plant on the surrounding.

Results achieved so far

In the first half of the pro­ject, the acti­vi­ties were focu­sed on the sam­pling and cha­rac­te­riza­ti­on of mate­ri­als and lab inves­ti­ga­ti­ons on pre-tre­at­ment and brick pro­duc­tion. Resi­dues from the steel plants and from sup­pli­ers and other indus­tri­al sec­tors were sam­pled and cha­rac­te­ri­zed. The phy­si­cal and che­mi­cal cha­rac­te­ristics of the mate­ri­als were com­pi­led in an inven­to­ry of pri­ma­ry and secon­da­ry raw mate­ri­als. Data about amounts and cur­rent use of the­se mate­ri­als were also included in the inven­to­ry. Based on the inven­to­ry, mate­ri­als were sel­ec­ted for the work on a micro­wa­ve pre-tre­at­ment pro­cess as well as for the reci­pe deve­lo­p­ment and lab-sca­le brick production.

Oxy-cutting fines: picture (left) and SEM-SE micrography (right)

Oxy-cut­ting fines: pic­tu­re (left) and SEM-SE micro­gra­phy (right)

LF slag fines: picture (left) and SEM-SE micrography (right)

LF slag fines: pic­tu­re (left) and SEM-SE micro­gra­phy (right)

A micro­wa­ve pre-tre­at­ment to redu­ce the amount of mate­ri­als like Zn, Pb and vola­ti­les was inves­ti­ga­ted and com­pared to con­ven­tio­nal fur­nace tre­at­ment. First results could also show a dif­fe­rent hea­ting beha­viour of the sel­ec­ted mate­ri­als based on their com­po­si­ti­on. It could also be shown, that with the micro­wa­ve hea­ting a simi­lar de-zin­cing of EAF dust could be rea­ched at lower bulk tem­pe­ra­tu­re of the mate­ri­al and with a hig­her zinc puri­ty of the remo­ved dust.

In lab-sca­le brick pro­duc­tion initi­al­ly the prio­ri­ties of the steel plants for the reci­pe deve­lo­p­ment were defi­ned based on the available mate­ri­als and sui­ta­ble use in the steel plant. The reci­pe deve­lo­p­ment for two of the steel plants will be focu­sed on CaO and MgO con­tai­ning mate­ri­als to crea­te syn­the­tic slag for­mer bricks. The reci­pe deve­lo­p­ment for the third focus­ses on the use of oxy-cut­ting fines, metal­lic iron con­tai­ning grin­ding sludge and fines coll­ec­ted at the belt con­vey­ors. Based on this sel­ec­tion a mecha­ni­cal pre-tre­at­ment of the mate­ri­als (crus­hing, sie­ving, etc.) has been inves­ti­ga­ted were nee­ded. In the lab-sca­le brick pro­duc­tion dif­fe­rent bin­ders as well as dif­fe­rent agglo­me­ra­ti­on para­me­ters like pres­sing force, pres­sing time, dry­ing con­di­ti­ons, etc were exten­si­ve­ly tes­ted. Bricks pro­du­ced by a num­ber of pro­mi­sing recipes were for­ward­ed to the high-tem­pe­ra­tu­re test­ing. This work is curr­ent­ly ongoing.

Agglomerated grinding sludge before (left) and after (right) drop test

Agglo­me­ra­ted grin­ding sludge befo­re (left) and after (right) drop test

Publications

Ech­ter­hof, T.; Will­ms, T.; Preiß, S.; Omran, M; Fabri­ti­us, T.; Mom­bel­li, D.; Mapel­li, C.; Stein­lech­ner, S.; Unamu­no, I.; Schü­ler, S.; Muders­bach, D.; Gries­sa­cher, T.: Deve­lo­ping a new pro­cess to agglo­me­ra­te secon­da­ry raw mate­ri­al fines for recy­cling in the elec­tric arc fur­nace – the Fines2EAF pro­ject, CLEAN TECH 4 — The 4th Euro­pean Con­fe­rence on Clean Tech­no­lo­gies in the Steel Indus­try, 28.–29. Novem­ber 2018, Ber­ga­mo, Italy

Ech­ter­hof, T.; Will­ms, T.; Preiß, S.; Omran, M; Fabri­ti­us, T.; Mom­bel­li, D.; Mapel­li, C.; Stein­lech­ner, S.; Unamu­no, I.; Schü­ler, S.; Muders­bach, D.; Gries­sa­cher, T.: Deve­lo­ping a new pro­cess to agglo­me­ra­te secon­da­ry raw mate­ri­al fines for recy­cling in the elec­tric arc fur­nace – the Fines2EAF pro­ject, La Metall­ur­gia Ita­lia­na, 111 (2019), Nr. 5, S. 31–40

Ech­ter­hof, T.; Will­ms, T.; Preiß, S.; Aula, M.; Abdel­ra­him, A.; Fabri­ti­us, T.; Mom­bel­li, D.; Mapel­li, C.; Stein­lech­ner, S.; Unamu­no, I.: Fabri­ca­ti­on of Agglo­me­ra­tes from Secon­da­ry Raw Mate­ri­als Rein­forced with Paper Fibres by Stamp Pres­sing Pro­cess, Appli­ed Sci­en­ces, 9 (2019), 3946

Will­ms, T.; Ech­ter­hof, T.; Stein­lech­ner, S.; Aula, M.; Abdel­ra­him, A.; Fabri­ti­us, T.; Mom­bel­li, D.; Mapel­li, C.; Preiss, S.: Inves­ti­ga­ti­on on the Che­mi­cal and Ther­mal Beha­vi­or of Recy­cling Agglo­me­ra­tes from EAF by-Pro­ducts, Appli­ed Sci­en­ces, 10 (2020), 8309


Logo ECThis pro­ject recei­ves fun­ding from the Rese­arch Fund for Coal and Steel under grant agree­ment No 754197.