Non-Ferrous Metal Smelting

8/3/2019 Non-Ferrous Metal Smelting

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3F03

Lecture 11

Non Ferrous Smelting



Non-Ferrous Ores

• Sulphides

– Zinc, Lead, Copper, Nickel

• Oxides – Aluminum, Magnesium, Nickel (laterites), Tin,

Titaniumn Niobium, Vanadium



Sulphide Ores

• Want to Smelt Directly

– Makes use of heat of reaction

– “Single” stage process• Complications

– Solution behaviour( Lead/Lead Sulphide)

– Major impurities (Copper/Iron)

• Sometimes Thermodynamics say no



MS

MO2

M





Can We Smelt Directly?

• Copper? Yes!

• Lead? Maybe

• Nickel? No• Zinc? Absolutely Not!



Copper Smelting

• Can smelt directly

• Major Impurity Iron

– Cannot be removed by Mineral Dressing – Can be removed by Oxidation

– Oxidation product magnetite (solid)

– Flux with Silica (fayalite slag)

• Seems straight forward

– Oxidise iron to slag, copper to metal ? But!----



Complications

• Iron Sulphide Soluble in Matte

• Copper Oxide Soluble Slag

• Lines on Diagram Move• As you make Richer Copper Matte More

Copper Oxide Dissolved in Slag

• Solution?



Multi Stage Process

• Ore Smelted to Produce High Copper

Matte with Some Iron Remaining

• Slag Removed Matte Charged toConverting Vessel

• Oxidise Remaining Iron

• Remove Slag

• Oxidise to Copper





MS

MO2M

Me

MeS

MeO



MS

MO2

M

Me

MeS

MeO

A

B

C



MS

MO2

M

Me

MeS

MeO

A

B

C

2 %M O2



Care Over Losses!

• AC lose 2% MO2

• AB use flux to absorb MeO deslag then

send matte to convertor.



Copper Making

• Matte Smelting

– Concentrates Cu2S

– Makes Richer Matte

– Use SiO2 to absorb FeO inhibit Fe3O4

• Converting

– Get Rid of Last Fe make pure Cu2S(white

metal) – Deslag

– Make Cu(blister copper)



Thermodynamics of Copper

Smelting• Initial process gradual oxidation of FeS

FeS(matte)+3/2O2=FeO(slag)+SO2

Below certain temperature will ppt solidmagnetite

3FeS+5O2= Fe3O4(solid)+3SO2

Undesireable interferes with furnace

performance



Thermodynamics of Copper

Smelting• Coexistence of Magnetite, Slag and Matte

3Fe3O4+ FeS(matte)=10FeO(slag)+ SO2

• Silica saturated fayalite slag aFeO=~0.3• See Figure 12.5 Rosenquist for Equilibria





Thermodynamics of Copper Losses

• (%Cu)=30(aCu2O)1/2

– For medium copper matte 0.3wt%Cu in slag

– For converting white metal to blister 7%Cu inslag

• Don’t convert with high slag volumes



Inustrial Copper Smelting

• Feedstock

– Chalcopyrite (FeCuS2)

– Bornite(Cu5FeS4)

– Also FeS and FeS2

• Quartz (flux to form a slag with FeO)

• Matte; 30-70% Cu

Largely decided by concentrate grade and

economics.



Industrial Furnaces

• Reverberatory Furnace

– Long Flat bath

– ~12000C

– Charged one end

– Heated by burner at one end

– Slag tapped from opposite end

– Matte tapped from sides

• Electric Furnace

– Similar to reverberatory heated by submerged

electrodes







Industrial Furnaces

• Flash Smelting

– Inco

– Outokumpo

– Sulphide oxidation supplies heat

– Use fine grained concentrate



Flash Smelting

• Problem: N2 in air absorbs heat, can’t

reach 1200-1300 needed

• Two Solutions• Inco

– Pure Oxygen

• Outokumpo

– Preheated air

– Still requires some Fuel



Flash Smelting

• Inco

– Pure Oxygen

– Higher SO2 concentration easier to scrub

• Outokumpo

– Preheated air/sometimes oxygen enriched

– Still requires some Fuel

– Very versatile



Flash Smelting

• Inco

– Matte 55-60%Cu

– Slag 1% Cu

– Off-gas 70-80%SO2

• Outokumpo

– Matte up to 65%Cu

– Slag –2.5%Cu



Noranda and Teniente Furnace

• Furnace: Cylinder 5 mdia x 20m long

• Charge: Solid through end-wall or blown in

through tuyeres• Oxidant:40%O2 enriched air

• Matte: 70-75%Cu( originally designed to

make copper!)

• Slag: 3-7% Cu (need slag cleaning!)

• Off gas:~15% SO2



Noranda and Teniente Furnace

• Energy – From Sulphur augmented by coal or molten matte

• Productivity

– ~2000t/day• Process

– Continuous charging coal & pelletized conc – Blow O2 enriched air

– Intermittent tapping of slag at one end

– Matte tapped from bottom



Copper Converting

• Matte 99%Cu

• Oxidise S from matte using air (sometimes

O2 enriched)• Product: Blister Copper (requires fire-

refining)



Pierce Smith Converter

• Cylinder 4m dia by 10m long

• Productivity: – 200-500 t matte/day

– 150-250t blister

– 200-300t slag

• Tuyeres: – 50 along one side

– 4-cm dia,

– 500-700Nm3 air/min total.

– Must be punched! To remove magnetite

• Rotated 1200 about axis for charging and deslagging!




• Slag: 2-15% Cu, 20-30%SiO2, 37-45%Fe

• Process:

– Charge 160t matte – 50t SiO2

– 40-50t cold scrap

– Blow 12 hrs g

– Get 65t blister copper

– Done in stages




• Stages of Blow

– Charge

– Blow to white metal

– Deslag

– Charge more matte

– Blow again

– Repeat till converter full of Cu2S

– Blow to “pure” copper











Continuous Blister Prduction

• Originally two processes

– Noranda(no longer makes copper)

– Mitsibushi(not strictly continuous)





Continuous Blister Prduction

Mitsibushi

Three linked reactors:

1/ Matte Production

2/ Converting

3/ Electric slag cleaning furnace





Mitsubishi Process

• Smelting Furnace

– Autogenous

– 8.5m dia x1.1m deep

– Charge: dried conc, silica and recycled

converter slag, blown with oxygen enriched air

via vertical lances

– Produce 65%Cu matte and slag – Slag matte emulsion flows to electric slag

cleaning furnace



Mitsubishi Process

• Slag Cleaning Furnace

– Heated by three pre-baked graphite

electrodes

– Slag separated (0.5-0.6%Cu) discarded

– Coke plus FeS charged

– C+Cu2O(slag)+FeS=Cu2S(matte)+CO

– Matte flows to converting furnace



Mitsubishi Process

• Converter

– Oxygen Enriched Air (26%O2)

– Limestone flux

– Slag 15% CaO, 15-20% Cu recycled to

smelting furnace.

– Only copper making furnace using a lime flux.



Fire Refining

• Final Refining of Copper Electrolytic

• Before Casting Anodes Must Refine Blister Copper(0.5%O 0.03-0.05%S)

• Refining in Anode Furnace(reverberatoryor rotary ) with one or two small tuyeres for air injection

– S+O=SO2 , k=90 at 11000C

– Other oxidisable elements also removed

– Precious metals remain



Poling-Deoxidation

• Final stage of refining

– Bubble hydrocarbons through melt

– Produce CO, CO2

and H2O

– Source used to be green-wood poles, hence

the name

– Some dissolved H2 in final product (0.1%O,

2*10-6

H) – Cast into 300-400kg anodes



Electro-Refining

• Impure Anodes

• Pure Cathodes

• Electrolyte:H2SO4(170-200kg m-3

)

Documents

Non-Ferrous Metal Smelting