Surface Chemical Studies on Sphalerite and Galena Using Bacillus polymyxa

Area of Science:

• Mineral processing
• Biomining
• Surface chemistry

Background:

• Understanding microbial-mineral interactions is crucial for biomining applications.
• Bacillus polymyxa's interaction with sulfide minerals like sphalerite and galena requires detailed investigation.

Purpose of the Study:

• To investigate the interaction mechanisms between Bacillus polymyxa cells and sphalerite/galena.
• To evaluate the potential of using Bacillus polymyxa for selective flotation and flocculation of these minerals.

Main Methods:

• Adsorption studies to quantify cell attachment.
• Electrokinetic measurements (electrophoretic mobility) to assess surface charge changes.
• Flotation tests (single mineral and selective) to evaluate mineral recovery.
• Flocculation tests to assess aggregation behavior.

Main Results:

• Higher Bacillus polymyxa cell adsorption on galena than sphalerite.
• pH-dependent adsorption on sphalerite, but not galena.
• Reduced electrophoretic mobilities for both minerals and cells after interaction, more pronounced for galena.
• Galena depression and sphalerite floatability restoration with collector/activator after bacterial interaction.
• Selective flotation of sphalerite from galena and selective flocculation of galena from sphalerite were achieved.

Conclusions:

• Bacillus polymyxa cells exhibit selective interaction with galena and sphalerite.
• The differential interaction allows for selective separation of sphalerite from galena using flotation and flocculation techniques.
• This study demonstrates the potential of Bacillus polymyxa as a bio-reagent for selective mineral processing.