The effect of switchable water additives on clay settling.

Area of Science:

• Environmental Engineering
• Materials Science
• Chemical Engineering

Background:

• Process water recycling in strip mining is crucial for environmental and industrial sustainability.
• Sedimentation of fine tailings often requires long settling times or difficult-to-recycle flocculants.
• Existing methods for water treatment can be inefficient or hinder subsequent water reuse.

Purpose of the Study:

• To introduce and evaluate switchable water additives as reversible flocculants for clay/water suspensions.
• To demonstrate the reversible control of ionic strength using CO(2) for efficient tailings management.
• To assess the effectiveness of these additives in improving water clarity and recyclability.

Main Methods:

• Utilized diamine-based switchable water additives to reversibly alter the ionic strength of aqueous solutions.
• Introduced CO(2) to induce flocculation and aggregation of clay tailings (kaolinite and montmorillonite).
• Measured water turbidity and settling times, and assessed the recyclability of the switchable water supernatant.

Main Results:

• Switchable water additives effectively promoted clay aggregation and reduced settling times.
• The process significantly increased the clarity of liberated process water compared to inorganic salts or CO(2) alone.
• Switchable water supernatant demonstrated recyclability over three cycles for enhanced kaolinite settling.

Conclusions:

• Switchable water additives offer a novel, reversible flocculation method for mining process water.
• This technology enhances water clarity and settling efficiency while enabling sustainable water recycling.
• The reversible nature of the additives is particularly beneficial for applications like oil sands separations.