Industrial Zinc, Lead, and Aluminum Extraction Methods

Zinc Extraction and Processing

Dry Extraction Method

The dry way is used for ore concentrations greater than 10%. If the blende and calamine are crushed and calcined to produce zinc oxide, they are effectively tested and reduced with carbon in a muffle furnace. By releasing oxygen, a wealth of 98% zinc is obtained.

Humid Extraction Method

The humid way is used for concentrations less than 10%. The blende and the ore are crushed to obtain zinc ore powder. Sulfuric acid is added to produce zinc sulfate, and impurities from other elements are dissolved. Through electrolysis, the zinc sulfate is separated, and zinc is obtained at a purity of 99.9%.

Zinc Alloys and Applications

• Shape Alloys: Brass (Cu-Zn) replaces bronze; Alpaca (Cu, Ni, and Zn) is used in cutlery; Zamak (Al, Cu, and Zn) is used for obtaining precision parts.
• Pure State: Utilized in the form of sheets for roofing, gutters, and cornices.
• Coating of Parts: Processes include electro-galvanized, hot-galvanized, and metalized sherardization.
• Other Forms: Zinc oxide is used in sunscreens and deodorants.

Lead Extraction and Refining

Enrichment and Oxidation

During enrichment, the galena is crushed and milled. The ore is separated from the gangue by flotation. In the oxidation of sulfides, the sulfides are roasted, transforming them into lead oxides. Silica and lime are then added to produce lead monoxide.

Reduction and Refining

The reduction of lead monoxide operates in a muffle furnace using coke coal and lime. Lead is obtained with impurities, known as lead bullion. Refining the lead involves two main steps:

1. Separation of other metals.
2. Electrolytic tuning.

Aluminum Production via Bayer Method

The Bayer method is utilized as it is the most economical. Bauxite is transported from the mine to the processing location. The ore is ground until it is pulverized. It is then stored until it enters a mixer where bauxite powder, caustic soda, lime, and hot water are consumed to dissolve it.

Processing and Electrolysis

In the decanter, waste materials are separated. In the heat exchanger, the solution is cooled and water is added. The alumina remains at the bottom of the tank. A filter separates the soda from the alumina, which is then heated to 1200ºC to remove moisture. It is then cooled in a refrigerator to room temperature. To obtain aluminum, the alumina is dissolved in cryolite at 1000ºC and subjected to electrolysis.

Aluminum Alloys and Uses

• Copper (Cu): Used for car tires and wheels.
• Magnesium (Mg): Used in aeronautics.
• Copper-Silicon (Cu-Si): Used for parts made by injection molding.
• Nickel-Cobalt (Ni-Co): Used for magnets.
• Aluminum Powder: Protects surfaces from weathering (intemperie).