WELCOME TO EXTRACTIVE

METALLURGY PRESENTATION ON:

MANGANESE

MANGANESE DEPOSITS – South Africa

EXTRACTIVE METALLURGY:

MANGANESE

PYROLUSITE MANGANESE METAL

Soumya Sobhan Dash

Department of Metallurgy and Material Engineering

National Institute of Technology,

ROURKELA, INDIA

PRESENTED BY:

INTRODUCTION MANGANESE is an Important Metal (Mn – 25) with many Metal Alloys , in particular Stainless Steel. The major Mineral Ore for Mn is Pyrolusite – MnO2( Manganese Dioxide). J G Gahn (1774) was First to isolate Manganese metal by Reducing MnO2 with Carbon. Manganese is the 12th most abundant Earth element. Manganese Ores in nature are Pyrolusite(MnO2), Braunite, Psilomelane, Rhodocrosite etc. South Africa produces 80% of World Manganese output. Manganese Nodules on the Ocean floor are yet to be Harvested commercially profitably . Ferro-Manganese Alloys are produced with MnO2 ore, iron ore &Carbon smelting in a Blast

Furnace/ Electric Arc Furnace. Iron free Manganese Alloys are produced by Leaching MnO2 Ores with H2SO4 soln. & subsequent

Electrowinning process . Heap Leaching of MnO2 Ores with Natural Gas at 850 ̊C & in presence of CO results in formation of

MnO which is easily leached with H2SO4 & Fe(II) Iron to produce Iron Hydroxide & Elemental Manganese, to be Electrowinned into Manganese Metal.

Manganese is essential to Steel production by virtue of it’s Sulfur fixing, Deoxidizing &Alloying properties.

Steel containing 8-15% of Manganese results in High Tensile strength Aluminium –Manganese Alloy (0.8-1.5% Mn) results in Galvanic Corrosion free Alloy used in

Beverage cans. Organo-metallic Manganese Tricarbonyl compound added to Unleaded Gasoline boosts Octane

rating of Fuel.

History:

Metallic manganese was first isolated in 1774 by Johan Gottlieb Gahn, a Swedish mineralogist who reduced Pyrolusite, a manganese dioxide ore, with carbon. In 1856 Robert Forester Mushet, a British steelmaker, used manganese to improve the ability of steel produced by the Bessemer process to withstand rolling and forging at elevated temperatures. A tough wear-resistant steel containing approximately 12 percent manganese was developed in Sheffield, England, by Robert Abbott Hadfield in 1882. Ferromanganese was first smelted commercially in a blast furnace in 1875; electric-furnace production began in 1890. Pure manganese was not available commercially until 1941, following work on electrolysis conducted in the 1930s under S.M. Shelton at the U.S. Bureau of Mines. By the early 21st century, manganese production had expanded to several locations throughout the world, and Australia, South Africa, China, Gabon, and Brazil became the largest producers.

Johan Gottlieb Gahn

WORLD MANGANESE SCENARIO

WORLD MANGANESE RESERVES & PRODUCTION

Manganese Reserves

Manganese Deposits – South Africa Pyrolusite – MnO2

South African Manganese Deposits World Manganese Production

Manganese Mine – North Cape, South Africa

Manganese Mine -China Manganese Mine - India

Manganese Mines - BRAZIL

INDIAN MANGANESE SCENARIO:

India is the Sixth largest producer of Manganese in the world ; the South Africa being the largest and China the second largest. The Ore deposits presently being worked in India are located in Singhbhum(Jharkhand), Panchmahals (Gujarat) , Balaghat (Madhya Pradesh), Vishakpatnam (Andhra Pradesh), Sandur & Shimoga (Karnataka) , Bhandara and Nagpur (Maharashtra), Bonai, Keonjhar and Koraput (Odisha), and Banswara(Rajasthan).

The Total Manganese reserves according to Indian Bureau of Mines are estimated to be 108 million tons. The total production of Manganese ores in India was 1,774,000 tons; Odisha, Madhya Pradesh,Karnataka,and Maharashtra accounting for 90 per cent of the production.

The Manganese ores found in India are generally mixtures of psilomelane[Mn,Ba,Mn8O16(OH)2], braunite(MnSiO2),pyrolusite(MnO2),hollandite(Mn,Ba,Mn6O14).

MANGANESE ORE CATEGORIES:

Manganese ores can be classified into four categories , namely:

• SIMPLE ORES:These ores contain small quantities of gangue materials that are amenable to concentration by simple methods involving only ore treatments ,i.e. gravity separation, magnetic separation ,or floatation.• FERRUGINOUS ORES:These ores not only contain iron minerals which can be removed by magnetizingreduction roasting followed by magnetic separation.• GARNETIFERROUS ORES:These ores contain only garnets and quartz as the chief gangue minerals and can be upgraded either by an electro-static separation method or by floatation.• COMPLEX ORES:These ores contain different type of gangue minerals in intimate association with manganese minerals, and complicated treatment is required for their extraction.

VARIOUS MANGANESE MINERALS FOUND IN THE WORLD• Borates: Sussexite ,Tusionite,

• Carbonates: Ankerite ,Kutnohorite ,Rhodochrosite ,Manganoan ,Calcite,

• Oxides:

1. Simple: Hausmannite ,Manganite ,Manganosite, Nsutite, Pyrolusite,2. Mixed: Birnessite ,Bixbyite ,Ferrocolumbite ,Ferrotantalite ,Galaxite, Jacobsite, Manganotantalite, Psilomelane

,Romanèchite ,Tantalite ,Todorokite ,Umber.

• Phosphates: Childrenite ,Graftonite, Lithiophilite ,Natrophilite, Purpurite ,Triplite ,Triploidite, Zanazziite.

• Silicates:Babingtonite Bixbite ,Braunite, Brownleeite ,Calderite, Chloritoid ,Eudialyte ,Glaucochroite ,Jeffersonite Knebelite

,Ottrelite ,Piemontite Pyroxferroite, Rhodonite, Spessartine ,Sugilite, Tephroite, Zakharovite Zircophyllite.

• Sulfides: Alabandite, Hauerite, Rambergite.

• Others: Axinite (borosilicate), Geigerite (arsenate), Manganese nodule (various) ,Samsonite (Sulfosalt) Zincobotryogen(sulfate), Wolframite Hübnerite

PYROLUSITE (MnO2)

PRODUCT Fe Mn SiO2 Al2O3 P S MOISTURE

LUMP 15-17 35-38 3.5-4.5 3-4 0.06-0.07 0.007-0.009 5-7

LUMP 13-15 38-40 2.5-3.5 2.5-3 0.06-0.07 0.007-0.008 5-7

LUMP 11-13 40-42 1.5-2.5 2-2.5 0.06-0.07 0.007-0.008 3-5

CHEMICAL COMPOSITION (in %) SIZE SPECIFICATION (in %)

PYROLUSITE ORE SPECIFICATIONS IN ODISHA, INDIA

MANGANITE

PSILOMELANE ()

PSILOMELANE JWELLERYPSILOMELANE ORE

BRAUNITE

HOLLANDITE (Ba(Mn4+6Mn3+

2)O16) ORE CONTAINING 35% Mn

RHODOCHROSITE (MnCO3) RHODONITE ((Mn2+,Fe2+,Mg,Ca)SiO3)

RHODONITE

SEDIMENTARY MANGANESE ORE

SEDIMENTARY MANGANESE CARBONATE

VOLCANIC MANGANESE ORES

POLYMETALIC MANGANESE OCEAN NODULES DISTRBN.

Manganese Nodule

MANGANESE OCEAN NODULES HARVESTING TECHNOLOGIES

MAGANESE ORE PROCESSING

Beneficiation Processes Adopted vis-à-vis Impurities In Ores

Methods of Beneficiation:• INTRODUCTION:

->Mechanical beneficiation of manganese ores is a must before metal extraction .

-> The various metallic ,non- metallic and volatile Impurities ,etc. are removed during the beneficiation

processes.

METALLIC IMPURITIES Fe,Pb,Cu,Zn,Ag

NON- METALLIC IMPURITIES Sulphur , Phosphorous

VOLATILE IMPURITIES H2O,CO2,Organic Matters

GANGUE SiO2,AL2O3,CaO,MgO,BaO

• PROCESSES: HAND SORTING & PICKING:The various Ore Impurities from the water - washed ores are hand-picked from the moving Conveyor

belt in the processing plants. JIGGING:

Mechanically operated ,Air pulsating Jigs remove the gangue in a rising current of air from the valuable heavier minerals which settle at the bottom ,used for beneficiating low grade Mn ores.

TABLING:The heavier mineral particles settling along the riffles are collected along the diagonal line of the table and the lighter gangue particles are washed away with the effluent.

HEAVY MEDIA SEPARATION:When the fine ore particles are mixed to a heavy ferrosilicon in a water medium the lighter gangue floats on the top and are separated from the heavier mineral particles settling at the bottom, which is further washed to remove the adhering ferrosilicon from it.

MAGNETIC SEPARATION:The magnetic separator works by varying the magnetic field which separates the mineral particles of different magnetic susceptibilities .

ELECTROSTATIC SEPARATION:The electro -static separator, separates the conducting and non-conducting particles ,where the conducting particles remain unaffected in the electric field and follow the tangential path whereas the non- conducting particle remain pinned down to the rotor.

• Hydrometallurgical Process Of Beneficiation:This process generally involves the dissolution of manganese ore with gaseous sulphur

dioxide in water( Sulphurus acid ) , sulphuric acid and ferrous sulphate, ammonium

sulphate with nitric acid or concentrated hydrochloric acid in order to remove iron, silica,

phosphorous and other impurities.

• Pyrometallurgical Process Of Beneficiation:In this process, the low grade manganese ores are broken down by the action of heat.Here the ores are agglomerated initially in order to make the size receptible for the blast furnace.Agglomeration process can be achieved by :1. Briquetting2. Sintering3. Pelletising 4. Nodulising.

Agglomeration in brief:

Briquetting:

Here the fine particles are agglomerated by application of pressure , at temperature of 100 ̊C and pressureof 4000 lb per square inch.The most common machine used for this process is Double roll machine.

Sintering:Sintering technique involves bonding of mineral particles by incipient fusion. This technique is commonly applied for manganese ore fines having size of (-) 6mm. The sintering process follows three main steps viz, (i) Preparation of feed, (ii) Fusion of the prepared layer of the raw materials on the sintering machine and (iii) Cooling of the agglomerated mass.

MANGANESE ORE BRIQUETTE MAKING UNIT

Pelletising:It is an advanced method of sintering where pellets instead of loose mix are fire and heat hardened, by rolling them to form small spheres, known as the pellets.Pelletising involves two basic steps, Balling and Firing. Pellets are proved to offer betterperformance than sinters in the blast furnace. The usual pellet size varies from10 mm to 25 mm.

Nodulising:This processes involves incipient fusion of particles. This method requires continuous movement between the charge and the equipment and is generally carried out in a rotarykiln at a temperature of 1250 ̊C to 1370 ̊C.Nodulising process is used for practically any fine size but the process nowadays is replacedcompletely by pelletisation and sintering.

Manganese Ore Handling

MANGANESE ORE PROCESSING UNITS

MANGANESE MINE Manganese Ore Beneficiation unit

MANGANESE ORE TRUCKING & SHIPMENT

MANGANESE ORE HANDLING CONVEYER UNIT

MANGANESE METAL EXTRACTION:

90% of Manganese metal production is consumed by the iron and steel industries (10 kg of Mn per metric ton of steel,13 million metric ton of Mn per year consumed for steel production).

High grade Mn ore ( >35% Mn by wt.) is processed conventionally by high temperature roasting (800-1000 ̊ C) of Mn(III), Mn(IV) ores to MnO for leaching with Sulphuric acid and subsequent Electrowinning to recover Manganese metal .

Low grade ( < 35% Mn by wt.) Mn ores of Pyrolusite , Psilomelane, Wad (MnO2) etc. are treated with dissolved SO2 in water (Sulphurous acid) leading to formation Manganese Sulphate (MnSO4) and Manganese Dithionate (MnS2O6) known as REDUCTIVE LEACHING (American Manganese Process).

MnO2 + SO2 → MnSO4 ……………………..(1)MnO2 + 2SO2 → MnS2O6 ……………………..(2)

Leachate solution pregnant with Mn salts are separated from the tailings in a Leach thickener tank .

Impurities like Al, As, SiO2, Zn are precipitated from the leachate by adjusting the pH of the solution to about 6 and sparging air , to be polished in a sand filter to remove the precipitated impurities .

Manganese carbonate (MnCO3) precipitation is achieved by treating the leachate solution with sodium carbonate.MnSO4 + Na2CO3 → MnCO3 + Na2SO4 …………………… (3) MnS2O6 + Na2CO3 → MnCO3 + Na2S2O6 ………..…………(4)

HYDROMETALLURGY AND ELECTROWINNING OF MANGANESE METAL

MANGANESE ORE LEACHING UNITS

Solid, precipitated MnCO3 is further filtered and rinsed (from Na2SO4 and Na2S2O6) to produce clean MnCO3 to feed the electrolytic solution.

The purified MnCO3 solution is fed into the cathode compartment of the divided Electrowinning cell along with recycled electrolyte containing MnSO4 and Sulphuric Acid , pH buffer (Ammonium Sulphate) and Sodium sulphite as reducing agents to prevent any further oxidation of manganese.

The spent Catholyte with lower Mn concentration is fed into the anode compartment of the Electrowinning cell.

The main electrochemical reactions are as follows:Main Cathode Reaction:

Mn2+ + 2e- → Mn Anode Reaction:

H2O → ½ O2 + 2H+ + 2e-Net Reaction:

MnSO4 + H2O → Mn + H2SO4 + ½ O2

Side Cathodic Reaction:2H2O + 2e- → H2 + 2OH-

MnCO3 CAKE & POWDER

MANGANESE ELECTROWINNING CELL

The cathodic hydroxide (OH ̄)ion can cause manganese hydroxide precipitation on the cathode surface which is prevented by pH buffer ammonium sulphate and proper concentration of MnCO3 in the Catholyte .

H2SO4 generated in the process is recycled to dissolve MnCO3.

Electrowinning of Mn metal proceeds at about 60-70% of current efficiency.

Anhydrous Na2SO4 from the leachate solution along with Na2S2O6 is recovered by crystallization on cooling the solution , Nano -filtration and heating the precipitate at 40 ̊C for Na2SO4, 267 ̊C for Na2S2O6and the recovered sulphur dioxide gas is recycled back to the leach tank.

On Electrowinning 99.5% pure Manganese metal is deposited in layers of few millimetres thick on the stainless steel cathode sheet.

The Manganese metal coated cathodes are extracted from the Electrowinning cell periodically , and flakesof Manganese metal deposits are removed by hammering.

The Manganese metal flakes are heated to 500 ̊C to remove Hydrogen gas and produce 99.9% pure Manganese metal.

MANGANESE METAL POWDER FROM ELECTRO WINNING

MANGANESE METAL FLAKES

PYROMETALLURGY OF MANGANESE METAL Smelting of high grade (> 35% Mn by wt.) ores in a Blast furnace / Electric arc furnace , along with coke

reduces the Manganese oxides(MnO2,Mn2O3,Mn3O4) by Carbon into Manganous oxide(MnO) which is further reduced by carbon at higher temperature to manganese metal and carbon dioxide.

Silicon dioxide combining with MNO can prevent metal production which is avoided by adding Basic Fluxes in regulated manner like roasted limestone. The smelting temperature and the pH of the slag is controlled to prevent formation of Silicon metal.

High carbon Ferro-manganese alloys is produced containing upto 76 to 80 percent manganese, 12 to 15percent Iron, up to 7.5 percent Carbon, and up to 1.2 percent Silicon.

SilicoManganese alloy , containing 65 to 68 percent Manganese, 16 to 21 percent Silicon, and 1.5 to 2percent Carbon, is produced by the smelting of slag from high-carbon ferromanganese or of manganese ore with coke and a quartz flux.

Medium and Low Carbon Ferromanganese is produced by Smelting Manganese ore , lime flux and coal along with Silicomanganese in a furnace. The low carbon content of Silicomanganese is transferred to the final ferromanganese product.

PLANT LAYOUT OF MANGANESE SMELTER

Manganese Ore Smelting –Blast Furnace Pouring of Hot Metal into Crucible

SMELTER EXHAUST FILTERING

ELECTRIC ARC FURNACE SCHEMA

MANGANESE SMELTING UNIT - SUBMERGED ARC FURNACE

MANGANESE SMELTING IN OPERATION IN SUBMERGED ARC FURNACE

MANGANESEALLOY MAKING

High carbon ferromanganese is used for making Carbon steels. For low carbon steel making medium or low carbon ferromanganese or electrolytic manganese are employed.

Manganese metal desulphurizes the high melting sulphide particles i.e. preventing “the hot shortness – low heat withstanding capacity” of carbon steels.

As a Deoxidiser Silicomanganese is added to steel making.

Manganese metal as an alloying agent to Carbon steel increases the metal strength , hardness , hardenability and abrasion resistance (Hadfield steel- 10-14% Manganese ,wear- resistant).

Low alloy (1.2% Mn) steel has increased tensile strength and increased steel yield.

FERROUS ALLOYS:

NON-FERROUS ALLOYS:

Aluminium –manganese(2 %) alloy has greater tensile strength , wear resistance , corrosion resistance than pure aluminium metal.

Nickel, Zinc, Copper alloys with Manganese (Deoxidiser) , which lowers the Liquidus & Solidus of the alloy metal thereby improving castability, improving strengthening effect, increasing electrical resistivity and thermal expansion of the Alloy metal.

WORLD -WIDE MANGANESE - FERRO ALLOYS PRODUCTION

Ferro –Manganese Alloy Making

FERRO –MANGANESE ALLOY PRODUCTION AT A GLANCE

Ferro- Manganese Smelting Ferro –Manganese Metal Alloy

MANGANESE CHEMICALS:

oMANGANOUS OXIDE (MnO) is used as a Fertilizerand in speciality Ceramics.

oMnO2 is used as a Depolarizer in Dry -cell Batteries which is produced by electrolysis.

oPotassium Permanganate (KMnO4) finds wide usage as an Oxidising Agent, which is produced by alkaline fusion and electrolysis.

CONCLUSION:MANGANESE is a Steel –Grey Metal ,Hard but Brittle .After IRON it is the next most Abundant Transition Metal on Earth.SouthAfrica, China, Brazil, Australia, Gabon, India are the major Manganese

producer currently.Pyrolusite is major Manganese Ore worldwide.Manganese Ore Beneficiation is done regularly before Metal Extraction.High grade ores are subjected to PyroMetallurgical & than HydroMetallurgical

process, ElectroWinning before Smelting for Metal extraction.Low grade ores are subjected to HydroMetallurgical(American Manganese

Process) ,ElectroWinning & Smelting for Metal extraction.Manganese is the most important ingredient in Carbon –Steel making of various

specifications.Ferro-Manganese,Silico-Manganese, Ni,Cu, Zn, Al -Manganese Alloys of different

specifications are made to improve the Material properties of Alloy Metals to a great deal for Modern requirements.

Manganese based Chemicals are widely used in various sectors of daily usage.

BIBILIOGRAPHY:

Wikipedia – the free Encyclopedia, Internet resources.

Indian Bureau of Mines Survey Reports on Manganese Mining & Extraction.

Indian Ocean Maganese Nodule field Geology Reports.

Manganese Beneficiation at M O I L, MP.Manganese Processing – Encyclopedia Britannica.HydroMetallurgical Processing of Manganese Ores –

American Manganese Process Reports.