PYROMETALLURGY
Extraction or production of metals with
chemical reactions at
high temperatures
Solids (advantages)
Cheap, good combination of
physical and chemical properties
Solids (disadvantages)
Formation of ash, difficult to
control during operation
Liquids (advantages)
Ease of handling, highest
calorific value
Liquids (disadvantages)
Expensive
Gaseous (advantages)
Ease of handling, good
combustion, no ash
Gaseous (disadvantages)
Low calorific value per volume of
fuel
Hydrocarbon Fuels
• Can come in solid, liquid, or gaseous forms
• Liquid:
petroleum, oil. Alcohol
• Gaseous: natural gas
• Solid:
coal, coke
Coal
natural or primary fuel formed in the
earth by the prolonged
action of
geologic forces and conditions on
accumulation of
plants and vegetal
matter
Coke
manufactured fuel from the
destructive distillation of coal in
the
absence of air (pyrolysis)
REFRACTORIES
Non-metallic materials that have properties which allows them to
be
exposed in environments above 538 °C
• Used as linings
for furnaces, kilns, reactors, etc
• Common refractories
Alumina (Al2O3), silica (SiO2), dolomite (CaMg(CO3)2), and magnesia (MgO)
Calcination
Heating of ore in the absence of air
Roasting
Heating of ore with excess air
Smelting
Separation by melting
Smelting separates two immiscible liquids
matte and slag
Converting
Refining and purifying of metal after smelting
Immsicible product layers top to bottom
Dross
Slag
Speiss
Matte
Dross
Solid impurities (metal oxides, metal sulfides, inorganic impurities) floating on the product
Slag
Molten solution of oxides found on the top portion (low density)
Speiss
Unwanted molten solution of arsenides (Fe, Co, Ni, Cu arsenides) formed during smelting
Matte
Molten solution of sulfides formed during smelting of Cu, Ni and Pb
SLAGS | Functions
• Collect and contain undesirable constituents
• Solvent for
additives
• Protective cover for molten metal from
oxidation
• Heating resistor for electric arc furnace
Heat Exchangers
Recycles heat from sources (hot product gases from furnaces, etc.) to be used for other processes (electricity generation, preheating feed, etc.)
Heat Exchangers Types
Heat Recuperators
Heat Regenerators
Heat Recuperators
Continuous transfer of heat from hot fluid to cold fluid by a heat transfer wall
Heat Regenerators
Contains heat storage element that absorbs heat from hot fluid and gives up heat to cold fluid
Furnaces based on
energy source
Fuel combination
Electricity
Fuel combination
Crucible
Hearth
Shaft
Crucible Furnace
Crucible is heated by fire and transfers heat to the bath
Hearth Furnace
Heats the bath directly by heat and by radiation
Shaft Furnace
Continuous melting; solid flows down by gravity and product is collected at the bottom
Electricity
Electric Arc
Induction
Induction Furnace
• Indirectly heats charge by using induction
coils
Electric Arc Furnace
Electrodes deliver the electrical charge
• Electric arc + slag
resistance provides
heating
Special
Converter
Retorts
Converter
• Gas is blown through the liquid metal
Retorts
• Recovery of volatile products