(1-2) Extractive Metallurgy | Hydrometallurgy

HYDROMETALLURGY

selective reaction of valuable metals using aqueous reagents.

PYROMETALLURGY

involves heat

ELECTROMETALLURGY

electrolysis is used

LAW OF CONSERVATION OF ELEMENTS

The quantity of element is neither decreased nor increased

BLACK BOX REACTION

• Steady-state assumption

• Time is not a factor

• What comes in also comes out

PRINCIPLES OF COMBINING VOLUMES

• Atoms combine to form molecule

• Expressed by the product of atomic weight and small whole

LAW OF COMBINING VOLUMES

When gases react, the volume consumed and produced

GAY-LUSSAC’S LAW

• Fixed amount of gas

• Pressure is proportional to temperature (k)

GAY-LUSSAC’S LAW (formula)

P₁/T₁ = P₂/T₂

CHARLES’ LAW

• Volume is proportional to temperature

CHARLES’ LAW (formula)

V₁/T₁ = V₂/T₂

BOYLE’S LAW

• Pressure and volume are inversely proportional

• High pressure, Low Volume

• Low Pressure, High Volume

BOYLE’S LAW (formula)

P₁V₁ = P₂V₂

IDEAL GAS LAW

The state of an ideal gas is determined by the macroscopic and microscopic parameters like pressure, volume, temperature.

IDEAL GAS LAW (formula)

PV = nRT

COMBINED GAS LAW

• Pressure is inversely proportional to volume, or higher volume equals lower pressure

• Pressure is directly proportional to temperature, or higher temperature equals higher pressure.

COMBINED GAS LAW (formula)

P₁V₁/n₁T₁ = P₂V₂/n₂T₂

HYDROMETALLURGY

involves chemical reactions carried out in aqueous solutions

• To recover metals from low-grade ores

• Form high-grade concentrates that are roasted

• Preliminary operation to mineral processing

ADVANTAGES OF HYDROMETALLURGY (3)

1. Mineral Beneficiations (optional)

2. Roasting (optional)

3. Leaching

4. Solid-liquid separation

5. Metal recovery

6. Solid/waste treatment

GENERAL STEPS IN HYDROMETALLURGY (6)

MINERAL BENEFICIATION

Control the fineness of the feed material

ROASTING

Conversion of valuable minerals into soluble forms

LEACHING

To dissolve the valuable mineral/metal into the liquor

SOLID-LIQUID SEPARATION

Separation of leach liquor from undissolved residue

METAL RECOVERY

Final extraction of metal from the solution

SOLID/WASTER TREATMENT

Neutralization for recycling or prior to disposal

LEACHING

• Selective dissolution of the valuable metal in the suitable reagent or leachant (usually sulfuric acid)

• Process of dissolving in a suitable reagent or leachant

LIXIVIANTS

Liquid or reagent used to selectively extract metals

• water

• acids

• bases

• aqueous salts

Common Lixiviants (4)

1. Readily available in quantity

2. Relatively cheap

3. Does not react unduly with gangue minerals

4. Non-corrosive

5. Amenability of regeneration/recycling

Requirements of Lixiviants (5)

• DUMP LEACHING

• HEAD LEACHING

• IN-SITU LEACHING

• VAT/PERCOLATION LEACHING

• PRESSURE LEACHING

5 DIFFERENT LEACHING METHODS

DUMP LEACHING

• Actual ore in the specific part of the site

• Feed of lixiviant is downward

PREGNANT LEACH SOLUTION

term given for the product of dump leaching

HEAP LEACHING

• We construct reaps

• Lixiviant are sprinkled from the top-most part

• Inclined position

IN-SITU LEACHING

• “In-place” leaching

• On site or in site leaching

VAT/PERCOLATION LEACHING

• Composed of series of tanks

• Ore is fed on every tanks

• Lixiviant is fed on the side

PRESSURE LEACHING

• Uses autoclase

• Big tanks

• High pressure at 10 atm

• ION EXCHANGE

• SOLVENT EXTRACTION

• ADSORPTION

3 Methods of Solution Purification/Concentration

ION EXCHANGE

• Exchange of ions in a polymeric resin with significant ions present in solution

• Functionalized resin

• SORPTION

• ELUTION

2 Methods of Ion Exchange

SORPTION

Resin is contained in a column

ELLUTION

• Retained ions are displaced from resin

• We feed eluant (organic) for metals to leave the resin

SOLVENT EXTRACTION

• Involved a distributive reaction wherein metals is allowed to partition

• Uses solvents to extract metals

• Organic solution

ADSORPTION

• Activated carbon – most important

• Adherence to the surface of another particle

CARBON-IN-PULP

• Leaching → Adsorption

• cyanidation leaching first and then adding the activated carbon in the slurry

CARBON-IN-LEACH

• simultaneously leaching and adsorbing

• activated carbon is added to the leaching tank, the leaching and adsorption are carried out at the same time

METAL SEPARATION AND RECOVERY

• Also known as metal winning

• Final step of hydrometallurgy

• Precipitation

• Electrometallurgy

Methods of Metal Winning (2)

PRECIPITATION

• Formation of a solid product from solution as a result of addition of a reagent

• Single-replacement method

• Metal is recovered as salt or oxide

ELECTROMETALLURGY

• Also known as Also known as ELECTROWINNING

• Recovery and purification of metals using electrode position of metals at a cathode

• Employs redox reaction

ELECTROREFINING

Improves the purity of metal

• Copper Leaching

  • Bacterial Leaching

  • Solvent Extraction

• Gold Leaching

  • Cyanidation

  • Adsorption

• Cobalt

  • HPAL

  • Moa-Bay Process

• Aluminum

  • Bayer Process

Hydrometallurgical Processes

• Bacterial Leaching

• Solvent Extraction

Hydrometallurgical Process in Copper Leaching

• Cyanidation

• Adsorption

Hydrometallurgical Process in Gold Leaching

• High Pressure Acid Leaching (HPAL)

• Moa-Bay Process

Hydrometallurgical Process in Cobalt Extraction

• Bayer Process

Hydrometallurgical Process in Aluminum Extraction