One step forward and two steps back - An industrial perspective of chromite pre-oxidation

Question 1

Die okaidasie van die Fe in die pellets, ekso of endotermies

Answer 1

Eksotermies

Question 2

Formula of pure Chromite

Answer 2

FeO.Cr2O3

Question 3

Wat is n beter chemiese voorstelling van ons erts?

Answer 3

(Fe2+,Mg2+)[Cr3+,Al3+,Fe3+]2O4

Question 4

The oxidation process in simplified chemical form:

Answer 4

Spinel + O2 = M2O3 (sesquioxide) + altered spinel

Question 5

Beweging van die ione tussen die spinel and sesquioxide

Answer 5

So jy ontrek yster en vorm dan n yster ryk sesquioxide fase (Fe,Cr,Al)2O3. Die spinel wat oorbly het dan n hoer konsentrasie Mg2+ ione

Question 6

So as jy na die spinel kyk wat oorbly, watter Fe atome is verwyder?

Answer 6

Meestal die Fe2+ ione. Die Fe3+ in oktahedriese posisies bly

Question 7

Proximate analysis

Answer 7

Includes moisture, volatiles, ash and fixed carbon

Question 8

First step in analysing coals are? And for what purpose?

Answer 8

Drying at temperatures not exceeding 40C to determine free moisture content

Question 9

How is the inherent moisture determined?

Answer 9

The dried sample is now prepared, milled etc and dried at 105C, the mass loss is associated with the inherent moisture

Question 10

Kam daar nog water wees buiten die free moisture en inherent moisture?

Answer 10

Jip, by hoer temperature kan daar kristalwater vrygestel word, maar word dan beskou as deel van die volatiles

Question 11

Hoe word die fixed carbon bereken?

Answer 11

100 - (Moisture + Volatiles + Ash)

Question 12

Na die inherent moisture, hoe word die volatile content bereken?

Answer 12

Mass loss by 900C vir 7min

Question 13

Hoe word die ash content bepaal.

Answer 13

By 850 grade word daar dan n oksiderende omgewing geskep. Die minerale wat oorbly staan bekend as die as

Question 14

Vir modellering, wat is beter, die proximate of die ultimate analysis?

Answer 14

Ultimate - want die fixed carbon kan ook nog ander elemente bevat

Question 15

Op watter beginsel werk die ultimate analysis?

Answer 15

Daar werk jy die persentasie suurstof uit: O2% = 100-inherent moisture-ash-C- H - N - S

Question 16

Watter steenkool het meer inertiniet, Vrystaant of Mpumulanga?

Answer 16

Vrystaat

Question 17

Sulphur in coal can exist in three forms?

Answer 17

Pyritic (bond to Fe)
Sulphatic
Organic