1111 E. Airline Hwy, Gramercy, LA 70052
Calcined Alumina

What is Calcined Alumina?

Atlantic Alumina Calcined Alumina

Chemical Properties and their Importance

Three types of alumina are produced at the Gramercy plant: calcined alumina (Al2O3) as reduction grade ore (RGO),
dried alumina trihydrate (Al2O3 • 3H2O), and wet hydrate or wet cake. The current specifications for these products follow.

  • %Na2O (Precipitation Conditions and hydrate filter operation) Smelter Bath Generation and Bath Chemistry
  • %SiO2 (Liquor Silica Control) Affects metal conductivity, ductility, formability (high purity Al)
  • %Fe2O3 (Bauxite Dependence or press filter performance) Metal purity need for end-use
  • %CaO (Liquor Causticity and press filter operation) Bath Chemistry
  • %TiO2 (Liquor Causticity/Lime addition rate) Metal Conductivity
  • %P2O5 (Digestion and Security Filtration Dependent) Smelter Current Efficiency, Metal Porosity and Brittleness
  • %V2O5 (Calcination Fuel Dependent) Metal Conductivity
  • %ZnO (Bauxite Dependent, sulfide control) Metal Grainy Surface Finish - spangling (Foil, Extrusions)
  • % CuO (Bauxite Dependent) Metal Conductivity
  • %Cr2O3 Metal Conductivity
  • %MnO (Bauxite Dependent) Metal Conductivity
  • % BeO (Bauxite Dependent) Environmental

Chemical Properties and their Importance

%Na2O (Precipitation Conditions and hydrate filter operation) Smelter Bath Generation and Bath Chemistry

%SiO2 (Liquor Silica Control) Affects metal conductivity, ductility, formability (high purity Al)

%Fe2O3 (Bauxite Dependence or press filter performance) Metal purity need for end-use

%CaO (Liquor Causticity and press filter operation) Bath Chemistry

%TiO2 (Liquor Causticity/Lime addition rate) Metal Conductivity

%P2O5 (Digestion and Security Filtration Dependent) Smelter Current Efficiency, Metal Porosity and Brittleness

%V2O5 (Calcination Fuel Dependent) Metal Conductivity

%ZnO (Bauxite Dependent, sulfide control) Metal Grainy Surface Finish - spangling (Foil, Extrusions)

% CuO (Bauxite Dependent) Metal Conductivity

%Cr2O3 Metal Conductivity

%MnO (Bauxite Dependent) Metal Conductivity

% BeO (Bauxite Dependent) Environmental

Size (Precipitation Control Dependent)
– +150 microns

  • – Alumina Dissolution in Smelter Bath

– -45 Microns and -20 Microns

  • – Smelter Operation
    • Current Efficiency and Anode Effects
    • Alumina Flowability, Particle Segregation
    • Emissions and Dust Control
    • Fines Generation – Attrition Index

• Attrition Index (Precipitation and Calcination Technology) – Fines Generation

• BET Surface Area, m2/gm (Calcination Operation Dependent) – Fluoride Absorption - Environmental and Safety

• LOI % (300 – 1000 oC) (Calcination Operation Dependent) – Related to Surface Area and Alpha Alumina Phase Content

Bulk Density, kg/m3 (Precipitation Control Dependent)
– Smelter Pot Feeding Rates

Alpha Phase Content, % (Calcination Operation Dependent) – Alumina Solubility in Smelter Bath, Free Heat of Reaction

Moisture Content, % (Atmospheric Condition Dependent)
– Economics of Shipping
– Bath Effects

Alumina Quality Consistency Is Important In Refineries and Smelters because of:
– Process Stability
– Process Efficiency
– Improved Economics