mineralogical approach on the modification of materials

Mineralogical approach on the modification of materials

M.Sc (Geol.) Pekka A Tanskanen

Process Metallurgy Research Group

Process Metallurgy Research GroupPekka A Tanskanen, 8.12.2014

Content

• Some definitions and introduction

• Mineralogical characterization of material

• Phase diagram based modification of material

• Examples: CASE 1 & CASE 2 & CASE 3


Some definitions and other introduction

Origin of inorganic raw materials

• If it isn't grown it has to be mined

• Ores exist in bedrock - not in soil

• Gravel, sand and clay exist in soil.

• Ore and wall rock

• Ore consist ore and gangue minerals

• Ore minerals will be concentrated

(not metals or components).

• Gangue minerals goes into tailings.

• Gangue is not the same as wall rock.


Bedrock

Wall rock

Wall rock

Ore

Open pit mine

Ore mineral (black)

Gangue minerals (light)

Soil

Definitions


• Mineralogy is a subject of geology specializing in the scientific study of chemistry, crystal structure physical (including optical) properties, origin and utilization of minerals.

• Petrology is the branch of geology that studies the origin, composition, distribution and structure of rocks.

• Rocks are composed of minerals.

• Mineral is a inorganic element or compound formed in a geological process. Minerals have certain chemical composition and ordered crystal structure.

• Minerals are composed of chemical components

Merikoski granite


QuartzSiO2

AlbiteNaAlSiO3O8

MicroclineKAlSiO3O8

Inorganic material

• Inorganic material is a system containing one ore more chemical components existing as one or more phases (~minerals).

• Phase is a separable region of material in which all physical properties are essentially uniform.

• Phase can have a non-ordered amorphous or crystallized (ordered) structure.

• Phases are composed of chemical components

• Chemical components are the smallest group of chemical units all the phases can be made off

- Fe, Ni, Cr in steel

- FeO, CaO, MgO, SiO2 in slag


Cr-Ca-Mg-Al-silicate glass

Spinel

Mg(Cr,Al)2O4

Forsterite

Mg2SiO4

Pyroxene

Mg2Si2O6

Metal (Cr,Fe)

Ferro chromium slag (air cooled)

Inorganic material is a system having

• Chemical composition

- whole chemical composition

• Phase composition

- existing phases

- proportion of phases

• Texture

- micro-texture (macro-texture)

- spatial interrelations of phases, grain size, morphology, orientation etc.

• Properties

- physical, chemical, mechanical, electrical, optical, magnetic etc.

• Properties of materials are dependent on the phase composition and micro-structure

• Properties can be modified by changing mineralogy and micro-structure orchemical composition and/or production conditions

Prosessimetallurgian tutkimusryhmäPekka A Tanskanen, 8.12.2014

Mineralogical characterization of materials


Methods:

• Optical microscopy

• Electron microscopy (SEM/FESEM/EPMA/TEM/EFTEM…)

• X-ray diffractometry (XRD)


Optical microscopy

• The most important tool for mineralogical research

• Polarized light microscope- Reflected light; sample: poliched section- Transmitted light; sample: polished thin section

•x•x

•x

•x

•x•x

•x•x

• Research outcome:

1. Types of existing phases- main phases, minor phases

- identification (specialists) - valuable phases

- portions of different phases

2. Micro-strucure/structures

- micro-structure type(s)

- grain size and morphology, etc.

3. Preparing sample to FESEM analysis- selecting type phase areas

- marking the areas on sample

- taking the photos


SEM/FESEM/EPMA/TEM analysis

• Chemical compositions of phases can be measured

• Morphology - magnification up to nanometry scale

• Sample: polished section (polished thin section) for element assays

- solid particles/powder - morphological research

• Carbon coating - electrical conductivity (Pd, Pt, Au coatings )

• Research outcome

1. Chemical composition phases- main phases, minor phases, valuable phases

- elemental charts, line analysis, etc.

2. Micro-strucure/structures

- micro-structure type(s)

- grain size etc.

3. Morphology of particles- nanoparticles etc.


XRD

• Identification of phases from one and multiphasesolid material samples

• Sample: fine powder

• Research outcome:

1. Phase composition of material- crystallized or amorphic material, or both

- identification (names) of different phases

2. Proportions of phases- accuracy 1-3 %

3. Special measurements- grain size of phases

- lattice parameters

- etc.

93

01-076-0918 (*) - Microcline maximum - KAlSi3O8

00-041-1480 (I) - Albite, calcian, ordered - (Na,Ca)Al(Si,Al)3O8

01-082-1690 (*) - Lime, syn - CaO

01-072-0916 (*) - Anhydrite - Ca(SO4)

01-089-0597 (I) - Hematite, syn - Fe2O3

01-071-0667 (*) - Brownmillerite - Ca2FeAlO5

01-089-4405 (I) - Hydroxylapatite, syn - Ca5(PO4)3(OH)

01-071-3699 (*) - Calcite, syn - Ca(CO3)

01-089-5917 (*) - Gehlenite - Ca2Al(AlSi)O7

01-070-7344 (*) - Quartz - SiO2

01-089-4924 (I) - Magnesioferrite, syn - Fe2MgO4

Operations: Background 1.000,1.000 | Import

File: 93-14102014.raw - Type: 2Th/Th locked - Start: 10.000 ° - End: 70.000 ° - Step: 0.040 ° - Step time:

Lin

(C

ou

nts

)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

2-Theta - Scale

10 20 30 40 50 60 70


Summary of the mineralogical characterization

Outcome:

• Nature of phases and phase associations

• Proportions of phases

• Chemical composition of phases

• Micro-structurial features of material

• What are valuable phases or components

• What are harmful phases or components

• …

➔The overall picture of the material

• What are the good and bad features

• What phases or structures have affect on these features

➔ The starting point for the material modification process


Modification of material

Phase diagram based modification


Pe+Fo Fo+En En+Tri

Phases:

Periclase= MgO

Forsterite=Mg2SiO4=2MgO∙SiO2

Enstatite=MgO∙SiO3=MgO∙SiO2

Tridymite/Cristobalite=SiO2

Pe

Fo En

Tri/Cri

Components: MgO and SiO2

En+Cri

Example of binary system: MgO-SiO2


Fa

Cri/Tri

WüCor

Her

Crd

MulHer+Crd+MulFa+Her+Crd

Chemical composition:

45 % FeO

25 % SiO2

30 % Al2O3

Phases

Components

Chemical composition vs. solid phases


Fa

Wü+Fa+Her

Tri/Cri

Wü Cor

Her

Crd

Mul

Her+Mul+Cor

Crd+Tri+Mul

Her+Fa+Crd Her+Crd+Mul

Fa+Tri+Crd

All ternary solid phase associations


CASE 1

Why high Cr2O3 content FeCr slaghas such a low Cr-solubility?

Mineralogical characterization


Chemical composition of FeCr slags

Component Cr2O3 Fe2O3 Al2O3 CaO MgO SiO2

FeCr slag SAF 1 12,1 3,8 26,5 1,3 23,2 30,7

FeCr slag SAF 2 11,48 3,8 26,8 1,4 23,1 30,5

• → Cr2O3 content > 120 000 mg/kg

• Solubility of Cr < 0,1 mg/kg


• Whysow low solubility?

Water cooled (granulated)

Air cooled

Point Phase O Mg Al Si K Ca Cr Fe

3 Mg-Cr-Al-Sp 40.1 15.6 27.6 15.2 0.3

4 Pyroxene 45.8 21.9 3.1 26.1 2.4 0.0

5 Mg-Al-Sp 43.7 17.3 38.5 0.5

7 Glass 47.1 6.8 10.2 28.8 0.9 3.5 1.6

8 Forsterite 43.1 34.0 20.3 1.6 1.0

12 Glass+px 46.4 12.2 9.2 26.3 0.7 1.2 2.1

13 Glass 47.5 5.7 11.1 28.4 1.2 3.7 1.3

KHO:2005:90"Ferrokrominäytteistä O:n yliopistossa tehty mineraloginen tutkimus on osoittanut, että pelkkä haitta-ainepitoisuus ei ole ratkaisevaa, vaan olennaista on, missä muodossa haitta-ainetta esiintyy…

(Makkonen H. ja Tanskanen P. 2005)

CASE 2

Synthesis of Li-ion battery anode chemical

Li4Ti5O12 spinel


Li4Ti5O12 synthesis – phase diagram study

2Li2CO3 (s)+ 5TiO2 (s)= 2CO2 (g)+ Li4Ti5O12(s)

Li4Ti5O12 product morphology - FESEM

Outi Kurikkala , Di-työ 2009

Li4Ti5O12 product phase identification - XRDTGA2

00-049-0207 (*) - Lithium Titanium Oxide - Li4Ti5O12

TGA2 - File: TGA2.raw - Type: 2Th/Th locked - Start: 15.000 ° - End: 68.000 ° - Step: 0.020 ° - Step time: 1. s

Lin

(C

ou

nts

)

0

100

200

300

400

2-Theta - Scale

15 20 30 40 50 60

Outi Kurikkala , Di-työ 2009

100 % Li4Ti5O12 phase

CASE 3

Dust forming autogenic regradarationof steel slag

Larnite phase transformation

Pekka A. Tanskanen 11.10.2007

Lar+Hat+Pe

Mer+Mon+Åke

After modification – no larnite – no autogenic degradation

Lar+Hat+Pe+Bre Mer+Mon+Åke+Bre

NO Larnite

Dust forming larnite

[email protected] ([email protected])

mailto:[email protected]

mailto:[email protected]

mineralogical approach on the modification of materials

Documents