7 Methods and Equipment for Removing Iron from Quartz ...

The purification of quartz sand presents various challenges, primarily due to the presence of impurities, particularly iron-bearing minerals such as goethite, hematite, limonite, ilmenite, pyrrhotite, tourmaline, amphibole, and biotite. These impurities significantly decrease the usability of quartz sand, making the process of iron removal crucial. Below is an overview of seven methods and equipment designed for effectively removing iron from quartz sand.

1. Gravity Separation Method

Gravity separation serves as an effective means across the entire particle size spectrum of quartz sand. This method is particularly efficient when the iron exists predominantly as heavy minerals (density > 2.9). However, it has limitations when dealing with mixed, flaky, light mineral particles, and medium-density minerals. The effectiveness of gravity separation can be measured using the formula: E = (heavy mineral density - medium density) / (light mineral density - medium density). Generally, gravity separation is straightforward when E > 2.5; however, as E decreases, the efficiency marginally decreases, and it becomes ineffective when E < 1.25. Commonly used equipment includes spiral chutes and shaking tables.

Spiral Chute

Spiral chutes can be utilized to separate quartz sand when the proportion of heavy mineral impurities is minimal. The degree of separation improves with the specific gravity difference among various minerals.

Shaking Table

The shaking table is a practical piece of gravity separation equipment valued for its cost-effectiveness. It effectively decreases the mica content in quartz sand, boasting benefits such as straightforward operation and high separation efficiency.

2. Magnetic Separation Method

Quartz itself is a non-magnetic mineral; however, the iron-containing impurities found within it, such as hematite and limonite, possess magnetic properties. The magnetic separation process exploits these differences to eliminate iron-containing impurities from quartz sand.

Magnetic Separator

High concentrate recovery rates and a permanent magnetic system characterize magnetic separators, contributing to effective separation without loss of concentrate.

3. Flotation Method

This method primarily targets the removal of iron-containing mineral impurities like mica and feldspar. The flotation process follows a three-stage approach to accurately remove iron-containing minerals.

Flotation Machine

This machine simplifies operation through automatic controls while maintaining a high handling capacity per unit volume.

4. Acid Leaching Method

For instances where quartz sand presents reddish hues and the iron content does not meet quality standards, the acid leaching method proves effective. This process requires washing with water to eliminate impurities before proceeding with acid treatment.

5. Stirring and Scrubbing

Friction among particles through vigorous agitation aids in this method, though the removal of thin iron oxide films may still be complex. Additionally, chemical reagents can enhance efficacy.

6. Ultrasonic Cleaning Method

This method effectively removes secondary iron films on quartz particles, achieving removal rates ranging from 46% to 70% when treated properly.

7. Microbial Iron Removal

This new technology harnesses the capabilities of microorganisms to leach thin-film iron from quartz surfaces. Early research indicates that using fungi such as Aspergillus niger can achieve remarkable iron removal rates.

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