RFCS-Projekt 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 aimed 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 four­fold: impro­ved uti­liza­ti­on of resi­dues, inter­nal reco­very of metals, reduc­tion of the amount of dum­ped mate­ri­als and saving of natu­ral resour­ces (e.g. lime­s­tone, dolo­mi­te and dolo­mi­tic lime). Through demons­tra­ti­on by ope­ra­tio­nal tests the tech­no­lo­gy of cement-free bricks will beco­me more accep­ta­ble for the steel works.

The approach fol­lo­wed was 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 have deve­lo­ped 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 (natu­ral) raw materials.

The pro­ject was able to show that the pro­duc­tion of cement-free bricks by stamp press is a valuable opti­on to pro­cess a wide ran­ge of resi­due mate­ri­als ari­sing in lower amounts at the EAF steel plants in an eco­no­mic way. It also con­tri­bu­tes to a reduc­tion of the use of pri­ma­ry mate­ri­als, (indi­rect) CO2 emis­si­ons and nee­ded land­fill capacity.

Work performed and results achieved

In the first report­ing peri­od, the acti­vi­ties were focu­sed on the sam­pling and cha­rac­te­riza­ti­on of mate­ri­als and the 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 the micro­wa­ve pre-tre­at­ment pro­cess as well as for the reci­pe deve­lo­p­ment and lab-sca­le brick pro­duc­tion. A micro­wa­ve pre-tre­at­ment to redu­ce the amount of mate­ri­als like Zn, Pb and vola­ti­les was inves­ti­ga­ted and com­pared to con­ven­tio­nal fur­nace tre­at­ment. Results of the work 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. As part of the reci­pe deve­lo­p­ment 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 Max Aicher Umwelt (MAU) und Mari­en­hüt­te were focu­sed on CaO and MgO con­tai­ning mate­ri­als to crea­te syn­the­tic slag for­mer bricks. The reci­pe deve­lo­p­ment for Siden­or focus­sed 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.) was inves­ti­ga­ted whe­re 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.

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)

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

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

During the second report­ing peri­od, the eva­lua­ti­on of the lab inves­ti­ga­ti­ons on pre-tre­at­ment and the lab-sca­le brick pro­duc­tion and eva­lua­ti­on were fina­li­zed. The acti­vi­ties were focu­sed on the high-tem­pe­ra­tu­re test­ing of the bricks, the pilot-sca­le brick pro­duc­tion and the indus­tri­al test­ing. The pro­ject was con­cluded by the tech­no-eco­no­mic­al eva­lua­ti­on. The eva­lua­ti­on and report­ing on the lab inves­ti­ga­ti­on of micro­wa­ve pre-tre­at­ment of the sel­ec­ted mate­ri­als was fina­li­zed. Also, the phy­si­cal eva­lua­ti­on of recipes was fina­li­zed and bricks pro­du­ced in the lab were deli­ver­ed to the respon­si­ble part­ners for high tem­pe­ra­tu­re test­ing. The deter­mi­na­ti­on of the ther­mal beha­viour of the pro­du­ced bricks was inves­ti­ga­ted by opti­cal dil­ato­me­try, by TGA-MS, by mel­ting and dis­so­lu­ti­on tri­als up to tech­ni­cal sca­le mel­ting expe­ri­ments etc. The work was main­ly con­duc­ted by POLIMI, Mon­tan­uni­ver­si­tät Leo­ben (MUL) and Uni­ver­si­ty of Oulu and fina­li­zed by an eva­lua­ti­on of the metall­ur­gi­cal per­for­mance of the tes­ted recipes. Based on the results of the lab-sca­le brick pro­duc­tion and eva­lua­ti­on and the high-tem­pe­ra­tu­re test­ing of the bricks final recipes for pilot-sca­le brick pro­duc­tion were defi­ned. The pilot-sca­le brick pro­duc­tion was set up at and con­duc­ted main­ly by MFG. Mate­ri­al from the MAU and Mari­en­hüt­te steel plants was deli­ver­ed to MFG for brick pro­duc­tion, while trans­por­ta­ti­on of Siden­or mate­ri­al was in part not pos­si­ble due to natio­nal regu­la­ti­ons. Siden­or com­mis­sio­ned a natio­nal com­pa­ny to pro­du­ce the bricks for indus­tri­al test­ing. Over­all about 81 t of bricks were pro­du­ced in Ger­ma­ny and Spain and deli­ver­ed to the steel plants and final recipes were defi­ned during brick pro­duc­tion. The fol­lo­wing indus­tri­al test­ing were con­duc­ted at the EAFs of the part­ners MAU, Mari­en­hüt­te and Siden­or and included also an exten­si­ve inves­ti­ga­ti­on on the influence of the brick use on the qua­li­ty of the EAF slag. The steel plants con­duc­ted in total 7 tri­al cam­paigns with 66 heats. The­se indus­tri­al tri­als could show, that the use of cement-free resi­due bricks can sub­sti­tu­te the use of lime/dololime but also reco­ver iron wit­hout any nega­ti­ve influence on fur­nace ope­ra­ti­on, steel or slag qua­li­ty. The pro­ject was con­cluded by a tech­no-eco­no­mic­al as well as an eco­lo­gi­cal eva­lua­ti­on and dis­se­mi­na­ti­on acti­vi­ties. The tech­ni­cal and eco­no­mic­al eva­lua­ti­on included the deve­lo­p­ment of plant con­cepts for a brick pro­duc­tion with and wit­hout pre-pro­ces­sing of the resi­dues. The over­all cos­ts of brick pro­duc­tion cal­cu­la­ted are in the ran­ge of about 60 to 105 EUR/t brick. This ran­ge is main­ly based on the need for pre-pro­ces­sing and the amount and cost of used bin­der. The­se cos­ts are off­set by the cos­ts for pri­ma­ry lime/dololime and land­fil­ling that are saved by the use of this tech­no­lo­gy. The eco­lo­gi­cal eva­lua­ti­on was based on a life cycle ana­ly­sis, which com­pared the cur­rent refe­rence prac­ti­ce with a prac­ti­ce sub­sti­tu­ting slag for­mers and sub­sti­tu­ting scrap in both cases redu­cing the need for land­fil­ling. The sub­sti­tu­ti­on of bur­ned lime by recy­cled slag for­mers show­ed a hig­her reduc­tion of the glo­bal warm­ing poten­ti­al than the sub­sti­tu­ti­on of scrap by metal bea­ring resi­dues. Dis­se­mi­na­ti­on acti­vi­ties of the pro­ject included a num­ber of publi­ca­ti­ons, the­ses and the orga­ni­sa­ti­on of a dedi­ca­ted work­shop on the “(Re)use of pri­ma­ry and secon­da­ry raw mate­ri­al fines in the EAF”. Fur­ther­mo­re, at one of the invol­ved steel plants the advan­ced plan­ning of a new area for sto­ring and hand­ling of the resi­dues and for resi­due brick pro­duc­tion is ongo­ing at the end of the project.

Progress beyond the state of the art and potential impacts

This pro­ject 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 tech­no­lo­gy brings 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 by sub­sti­tu­ting pri­ma­ry raw mate­ri­als like lime/dololime and iron, and redu­ce the envi­ron­men­tal impact of the steel plant on the sur­roun­ding again by reduc­tion of land­fil­ling and an impro­ved car­bon foot­print of the steel production.

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

Abdel­ra­him, A.; Aula, M.; Ilja­na, M.; Will­ms, T.; Ech­ter­hof, T.; Stein­lech­ner, S.; Mom­bel­li, D.; Mapel­li, C.; Omran, M.; Preiss, S.; Fabri­ti­us, T.: Sui­ta­bi­li­ty of Self-Redu­cing and Slag-Forming Bri­quet­tes for Elec­tric Arc Fur­nace Use Based on Labo­ra­to­ry Tests, steel rese­arch inter­na­tio­nal, 2100472


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