Iwona JONCZY, PhD Eng.

Silesian University of TechnologyFaculty of Mining and GeologyInstitute of Applied GeologyGliwice, Poland

Oulu, 15.05.2014

Mineral and chemical composition of metallurgical slags

Upper Silesia is one of the best developed regions in Poland.

Rich deposits of metal ores and hard coal have contributed to the extensive development of metallurgy and coal mine industry which started as early as in the

Middle Ages.

Metallurgy became especially problematic, mainly because of considerable amounts of

wastes coming into being during production.

The extensive mining and metallurgical activity carried out over years has brought about changes of the

environment.

For many years metallurgical slags were collected on the dumps.

There are propositions: to apply slag for the production of road

aggregate, aggregate for the production of concrete mixtures, as raw material for the production of mineral wool,

to return slags to metallurgical processes, to liquidate waste dumps to reclaim the land

used for the dumps and to effect their subsequent revitalization.

That is why it is important to carry out research on their mineral and chemical composition, which may deliver some information during an economic exploitation of slags, e.g.:

connected with new phases forming in metallurgical processes,

forms of metal occurrence in slag components, possibilities of metals release from slag components

and their migration to the environment.

Each type of the slag should be taken individually, we can not make too many generalizations of mineral and chemical composition of the slag.

Due to the phase composition, metallurgical slags are one of the most diverse groups of waste materials.

Phases, which crystallized in a furnace can be identified with the minerals forming as a result of geological processes.

However, their chemical compositions usually are much richer than their natural counterparts.

SLAGS AFTER ZINC AND LEAD PRODUCTION

SLAGS AFTER STEEL PRODUCTION

Research methods

Chemical analysis Electron probe microanalysis Microscopic analysis in transmitted and reflected

light Scanning microscopy X-ray analysis

Al As Ca Fe K Mg

1,99-3,742,49

0,20-1,700,70

1,83-7,756,32

13,40-20,6016,94

0,22-0,550,40

0,73-1,481,16

Mn P Pb S Ti Zn

0,05-0,200,10

0,03-0,100,09

0,50-2,901,55

0,98-7,065,49

0,14-0,330,21

0,62-8,43,14

Ranges and mean values are shown for 20 samples of the wastes

Concentration of the elements [Mass%]

CHEMICAL COMPOSITION OF SLAGS AFTER ZINC AND LEAD PRODUCTION

Ag Ba Bi Cd Co Cr Cs Cu Ge

113 480 0,2 84 19 53 9 506 2

Hf In Ir Mo Ni Rb Sb Sc Se

2 40 3 10 110 39 19 7 20

Sn Sr Ta Te Th Tl U W V

3 250 1 0,1 7 1 5 1 58

La Ce Eu Lu Nd Sm Tb Yb Au [ppb]

24 38 1 0,5 9 3 0,9 2 47

Concentration of the elements [ppm]

Mean values are shown for 20 samples of the wastes

CHEMICAL COMPOSITION OF SLAGS AFTER ZINC AND LEAD PRODUCTION

CHEMICAL COMPOSITION OF SLAGS AFTER IRON AND STEEL

PRODUCTION

Al [%] As [ppm] Ba [ppm] Ca [% ] Cd [ppm] Ce [ppm] Co [ppm]

0,86-10,00 0,1-30,2 169-2380 0,08-32,70 0,1-7,9 6,1-152,0 0,8-89,6

Cr [ppm] Cu [ppm] Fe [%] K [%] La [ppm] Li [ppm] Mg [% ]

279-3020 19,1-626,0 0,39-11,30 0,03-2,16 3,1-69,4 6,6-154,0 0,05-4,85

Mn [ppm] Mo [ppm] Na [% ] Ni [ppm] P [%] Pb [ppm] S [%]

136-10000 0,5-21,9 0,04-0,70 6-278 0,007-0,756 1,5-634,0 0,06-0,23

Sb [ppm] Sn [ppm] Sr [ppm] Ti [%] W [ppm] V [ppm] Zn [ppm]

0,1-19,6 1-104 18-1000 0,024-0,585 0,6-200,0 1-1000 6,6-10000,0

Mineral composition of metallurgical slag

Components formed during the metallurgical processes: glaze, metallic aggregates, oxides and silicates.

Secondary phases, which are connected with the crystallization on the dump: calcite, gypsum.

Akermanite Ca2Mg[Si2O7]Alite Ca3[O|SiO4]Anorthite Ca[Al2Si2O8]Augite (Ca,Mg,Fe2+,Fe3+,Ti,Al)2[(Si,Al)2O6]Bredigite γ-Ca2[SiO4]Brownmillerite Ca2(Al,Fe)2O5

Calcioolivine α-Ca2[SiO4]Cristobalite SiO2

Diopside CaMg[Si2O6 ]

Fajalite Fe2[SiO4]Ferrites CaO-FeO-Fe2O3

Forsterite Mg2[SiO4]Gehlenite Ca2Al[(Si,Al)2O7]Gypsum CaSO4·2H2OGoethite FeOOHHematite α-Fe2O3

Calcite CaCO3

Quartz SiO2

Larnite β-Ca2[SiO4]Magnetite Fe3O4

Melilite (Ca,Na)2(Al,Mg)[(Si,Al)2O7]Merwinite Ca3Mg[SiO4]2

Monticellite CaMg[SiO4]Periclase MgO Lime CaOWustite FeO

Electron probe microanalysis

It is a kind of spectroscopy methods. That method permits to observe a small area of the sample and shows a qualitative and quantitative composition of a sample.

That analysis shows also distribution of the elements.

No.[%]

Al2O3 SiO2 MgO CaO FeO MnO TiO2 Cr2O3 ZnO V2O5 SO3 P2O5

1 0,03 0,03 59,04 1,01 12,22 27,00 - 0,49 0,02 0,10 - -

2 - 0,06 60,61 0,86 11,40 26,47 0,02 0,43 0,02 0,10 0,03 -

5 0,84 39,81 0,02 57,73 0,05 0,10 0,16 - 0,02 0,07 - 1,20

6 0,95 39,95 0,02 56,85 0,07 0,11 0,16 - 0,03 0,12 - 1,72

7 0,03 2,94 - 53,80 0,43 - 0,02 0,23 0,02 1,59 0,03 40,92

8 48,90 1,35 0,04 41,45 0,11 0,11 0,14 0,09 - 0,39 0,15 7,23

9 62,85 1,24 0,08 35,17 0,36 0,27 - - - - - 0,03

10 62,03 0,95 0,04 35,59 0,19 0,13 0,06 - 0,03 0,02 - 0,96

Mg K50 µm

Al K50 µm

Zn K50 µm

Ca K50 µm

P K50 µm

Si K50 µmMn K50 µm Cr K50 µm

V K50 µm

Fe K50 µm

S K50 µmTi K50 µmMg K50 µm Mn K50 µm

Fe K50 µm

Fe K20 µm

Drop of iron surrounded by glaze

Metallurgical slag is a byproduct of the smelting process, which could be compared to magmatic processes.

Under high temperature minerals crystallize in the correct order. The same order is in magma and in the metallurgical alloy.

It should be noted, however, that the minerals in the earth were formed over thousands and millions of years, minerals from metallurgical alloy had short time to formed their structure.

Process of their crystallization is often interrupted by the rapid cooling of the slag melt. Therefore, the composition of the slag is dominated by small crystals surrounded by glaze.

Well formed crystals, which identification by microscopic examination is possible, are present in small amounts.

The chemical composition of phase crystallizing from the slag is often richer than the chemical composition of their natural counterparts.

Mineral composition of slagsin transmitted and reflected

light during microscopic analysis