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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