Chromite ore beneficiation

Prepared by Mukesh Ranjan Behera

Contents Introduction Steel scenario Physical and chemical properties Occurrences Classification and uses World chromite production Global reserves and demand List of companies engaged Potential of India Mining methods Beneficiation Cost variation

ObjectivesTo gain the basic knowledge of chromite Its formation Global presence Uses Mining methods Beneficiation practice

IntroductionChromite occurs as a chromium spinel, a complex mineral containing magnesium, iron, aluminum and chromium in varying proportions depending upon the deposit. Chromium is replaced by ferric iron & aluminum to form hercynite(FeAl2O4)and iron is replaced by magnesium to form magnesio chromite(MgCr2O4).

It is this replacement that improves the Cr/Fe ratio in chromite. Chromium ore occurs exclusively in ultramafic igneous rocks.

Steel Scenario

4 tons Stainless steel

1 Ton Ferro chrome

2.5 Tons of chromite ore

Indian steel production is likely to grow over 250-300 MTPA from its current 86 MTPA by 2025-30

Properties of Chromite

Chemical Classification oxide

Color dark gray to black, rarely brownish black

Streak dark brownLuster metallic to submetallic

Diaphaneity opaqueCleavage none

Mohs Hardness 5.5 to 6Specific Gravity 4.0 to 5.1 (variable)

Diagnostic Properties luster, streak

Chemical CompositionFeCr2O4 with magnesium substituting for iron in

significant amounts

Crystal System isometricUses an ore of chromium

Physical and chemical properties

Occurrences/ DepositsCommercial chromite deposits are found in two forms :stratiform seams and irregular podiform/lenticular deposits.

Continue….

Classification and uses

World chromite reserves and production graphsSource: Industrial Minerals 2011

Country Production 2011 ('000 metric tons)

Production 2012 ('000 metric tons)

Reserves('000 metric tons)

South Africa 10,200 11,000 200,000

Kazakhstan 3,800 3,800 210,000

India 3,850 3,800 54,000Others 5,450 5,300 N/A

World Total 23,300 24,000 >460,000

Demand

• African Consolidated Resources Plc• Anglo Pacific Group plc• ASA Metals (Pty) Ltd• Chrometco Limited• Chromex Mining• Consolidated Minerals Limited• Eurasian Natural Resources Corporation• International Ferro Metals South Africa (Pty) Limited• Kefid Machinery• Kemai Machinery & Equipment Co Ltd• Kermas Group Limited• Mas Minerals• Merafe Resources Ltd• Metal Bulletin Events• Southbridge International Trade Corporation• vpr Mining Infrastructure Suarl• Zimbabwe Alloys Chrome Limited• Zimbabwe Mining & Smelting Co. (Pvt) Ltd

List of Company

CHROMITE ORE POTENTIAL OF INDIA

India

1st IN EXPORT

OF CHROME

ORE

5th IN TERMS OF CHROME

ORE RESERVE

3rd in chromite

production

CHROMITE ORE POTENTIAL IN INDIA

POSSIBLE RESERVE (69%) (31%)

TOTAL RESOURCE ─ 213 Mt

EASTERN INDIAN STATE OF ORISSA

(OVER 95% OF TOTAL)

SUKINDA ULTRAMAFIC

BELT

BAULA-NAUSAHI IGNEOUS COMPLEX

CHROMITE ORE POTENTIAL IN INDIA

“CHEMISTRY” OF CLEAN CHROME SPINELS FROM ORISSA

Location Cr/Fe Cr2O3% MgO% FeO% Al2O3%

Sukinda 3.35 57.5 14.01 15.12 12.603.30 58.7 12.57 15.57 11.823.86 58.9 16.10 13.40 10.703.30 56.6 11.70 15.60 11.10

Boula-Nausahi

2.04 54.9 11.64 23.70 9.821.80 52.8 10.50 25.65 9.801.67 49.4 8.89 26.08 14.40

INDIA COMES UNDER HIGH-GRADE GROUP WITH COUNTRIES HAVING AVERAGE Cr2O3 GRADE OF 39%.

Rock containing chromite ore

Mining Method

Extraction of the Chromite OreBoth surface and underground mining methods will be used to mine the chromite. Mining produces both ore and waste rock. Waste rock consists of all other non-chromite bearing rock excavated during mining.

Surface Mining Chromite ore is mined by surface methods. This includes an open pit from which surf ace material, non-chromite bearing overburden and chromite ore,will be excavated. The chromite ore containing rock will be drilled, blasted, removed and loaded onto large trucks for hauling to the crusher and ore processing facility

Underground Mining The transition to underground mining will beconsidered once it is necessary to extract rock fromgreater depths. The underground mine will bereached from the bottom of the open pit. Blast hole stopping methods will be used for underground mining. Stopping occurs in underground mineral mining when the surrounding rock is strong enough to allow the drilling, blasting, and removal of ore without caving

EVOLUTION OF CHROMITE BENEFICIATION IN INDIA

CHROMITE BENEFICIATION IN INDIA

PAST SCENARIO

MINING OF HIGH GRADE

ORE

LEAVING LOW AND MEDIUM GRADE ORES

STACKED AS WASTE

USE OF MANUAL METHODS FOR

DRESSING

ClassificationGenerally Chrome ore deposits are classified as Siliceous type (silica rich) Ferruginous type (iron rich)

Associated gangue minerals are Talc Quartz Hematite Goethite Limonite Serpentine Pyroxinite

Comminution(to prepare the ore for subsequent unit operations) and concentration. The feed unit incorporates screening of the ROM ore to 75mm from -220mm followed by two stage crushing(primary& secondary crusher) and screening to produce less than 3mm size fraction. This fraction is further ground to less than 1mm and then upgraded utilizing conventional gravity techniques like spiral concentrator and shaking table in the concentration section.Low grade chrome ore with Cr2O3 of about 20-30% of sukinda region of India ,can be beneficiated to a marketable grade of 45% Cr2O3 with 45-50% recovery, by grinding the chrome ore(d80 passing size 260 microns).

Circuit descriptionCircuit description

CHALLENGES IN BENEFICIATION

LOSS INTAILINGS

UTILISATIONOF

LATERITIC WASTE

ORE CHARACTERISTICS

CHALLENGES IN

BENEFICIATION

MAJOR CHROMITE BENEFICIATION PLANTS IN INDIA

OPERATOR LOCATIONRATED THROUGHPUT CAPACITY (tpy)

FACOR Boula 200 000

Ostapal 80 000

TATA STEEL Bhimatnagar(Sukinda)

1 100 000

OMC Kaliapani 1 65 000 64 000;50 ± 2%Cr/Fe: 2.4-3.00<38

65 000; 50 ± 2Cr/Fe: 2.4-3.0<38

30000; 46-4825-30

44 000; 42-45 Cr/Fe = 1.4-4.713-21

PROJECTED OUTPUT (tpy); (% Cr2O3)

FEED GRADE (% Cr2O3)

Price variation