FIM Cu (10)

Why is metallic copper produced?

highest electrical conductivity of all non-precious metals

best metallic heat conductor after silver

corrosion resistance (“half noble metal”)

high ductility (can be made into thin wires with high flexibility)

easy to allow

non-magnetic

recyclable

How much of produced copper is still being used?

80%

What can be used instead of copper in electrical cables?

Al

What can be used instead of Cu in heat exchangers?

Ti, steel, graphite

What can be used instead of copper in water pipes?

plastics

What can be used instead of copper in telecom applications?

optical fibres

How can copper be produced?

from sulfide ores via pyrometallurgy with electrorefining

from oxide ores hydrometallurgy with electrowinning

What is pyrometallurgy?

high temperature smeltering process

What is hydrometallurgy?

low temperature aqueous extraction route

Name the steps of pyrometallurgical refining of copper sulfide ores

mining

concentration, crushing, froth flotation

smelting

converting

fire refining in anode furnace

electrolysis

Name what is obtained after every step in pyrometallurgical refininf of copper sulfide ores

sulfide ore (0.5-2 wt.% Cu)

copper concentration (25-35 wt.% Cu)

copper matte (30-70 wt.% Cu)

blister copper (98 wt.% Cu)

copper anodes (99 wt.% Cu)

copper cathodes (99.99 wt.% Cu)

Where does crushing and grinding of sulfude ores take place?

in cylindrical ball mills

Describe the process of froth flotation

fine copper mineral particles are mixed with xanthates to make them water repellent

they are fed into the water bath with foaming agent to create a bubble bath

jets of air are forced through flotation tanks

water repellent copper mineral particles are picked up by the bubbles of foam and float to the surface making a froth

unwanted rock falls to the bottom

froth is skimmed off the surface and roasted in the air to make copper concentrate

water, xanthates and foaming agents are recycled

Wat is the purpose of converting?

reduction of copper sulphide to copper

What is the purpose of fire refining?

removal of metal impurities and dissolved oxygen from blister copper

What is the purpose of flash smelting?

elimination of unwanted Fe, S and minerals like silica, limestone and alumina

minimization of copper losses

What happens during flash smelting?

iron sulphides are converted to iron oxides and SO₂ with oxygen

copper sulphide and iron oxide are miscible —> + silica to selective absorb FeO and silica, limestone, alumina

a seaprate immiscible slag layer is formed (e.g. FeO * SiO₂)

Where does flash smelting take place?

Outokumpu flash furnace

Isasmelt

Which metals are mostly retained in copper matte?

Ni

noble metals

What happens during converting step?

liquid copper matte is oxidized with air to form blister copper in a converter

iron sulphide is eliminated by oxidation to iron oxide (slagged with SiO₂)

formation of blister copper by reduction of copper sulfide to copper with SO₂ released

How many blowing periods are in converting?

two

Where can converting take place?

Pierce-Smith converter

Which element is mostly retained after converting step?

Ni

What is the purpose of fire refining?

purification step

removal of remaining S and Fe impurities by selective oxidation with pure oxygen gas

removal of dissolved O₂ (poling) by blowing natural gas or ammonia through liquid copper phase

continuous casting into copper anodes for electrolytic refining

Which elements are converted into slag by addition of silica during fire refining?

Fe

Co

NI

As

Sb

Which elements leave as exhaust gas after fire refining?

Zn

PbO

As

Sb

Which elements are retained in the liquid phase after fire refining?

Bi

Se

Te

noble metals

What element increases in its wt.% in copper during oxidation step and decreases during reduction?

oxygen

Which element is completely removed from copper during oxidation step?

copper

Name the steps of hydrometallurgy

dump leaching of oxidic ores using sulphuric acid

solvent extraction

solvent stripping

electrowinning

Describe the steps of hydrometallurgy

copper ores are dumped on the impermeable plastic membrane

ore heap is sprayed constantly with diluted sulphuric acid

impurities (Fe) are removed by solvent extraction

metallic copper is recovered by electrowinning

What does solvent extraction step involve?

mixing of leach solution with liquid organci with extractant that can extract Cu under operating condiitons

mixing of loaded organic phases with an aqueous solution that is low in Cu to strip Cu from the loaded organic phase into aquous phase

separation of the loaded organic phase from aqueous solution depleted in Cu by gravity