Analysis of Membrane Separation and Recycling Treatment Technology for Spent Acid from Acid Soaking in Quartz Sand Production

In the production process of quartz sand, acid soaking is a crucial link. Strong acids (such as hydrochloric acid, sulfuric acid, etc.) are used to remove impurities in the quartz sand, thereby improving its purity. However, the spent acid generated in this process not only contains a high concentration of acidic substances but may also contain heavy metal ions and other harmful substances. If directly discharged, it will cause serious pollution to the environment. Therefore, how to efficiently and environmentally treat these spent acids has become an urgent problem to be solved for quartz sand production enterprises. As an advanced wastewater treatment technology, membrane separation and recycling technology provides a new solution for the treatment of spent acid from acid soaking in quartz sand production.

1. Characteristics and Challenges of Spent Acid from Acid Soaking

The spent acid from acid soaking has the characteristics of high acidity, high concentration, and complex composition. Among them, the high acidity increases the difficulty of treating the spent acid, and corrosion-resistant and high-pressure-resistant equipment needs to be used; the high concentration means that the spent acid contains a large amount of valuable resources, such as the acid itself and the possible dissolved heavy metal salts; the complex composition requires the treatment technology to have a high degree of selectivity and flexibility.

2. Principles and Advantages of Membrane Separation and Recycling Technology

Membrane separation and recycling technology is a technology that separates solutes and solvents in wastewater through physical or chemical methods based on the selective permeability principle of semi-permeable membranes. In the treatment of spent acid from acid soaking in quartz sand production, membrane separation and recycling technology mainly includes several forms such as electrodialysis, reverse osmosis, and nanofiltration.

• Electrodialysis: Using the action of an electric field, the ions in the wastewater pass through the ion exchange membrane driven by the electric field force to achieve the separation and concentration of ions. The electrodialysis technology is especially suitable for treating wastewater with high salt content and high ion concentration, and can efficiently recover the acid and heavy metal salts in the spent acid.
• Reverse osmosis: Through the action of high pressure, the water molecules in the wastewater pass through the reverse osmosis membrane under the pressure difference, while the solutes, heavy metal ions, and acids are retained on one side of the membrane. The reverse osmosis technology can remove most of the solutes in the wastewater, produce high-quality recycled water, and at the same time recover the acid in the spent acid.
• Nanofiltration: The pore size of the nanofiltration membrane is between reverse osmosis and ultrafiltration, which can retain organic matters and inorganic salts with relatively large molecular weights, and at the same time allow some small molecular solutes and solvents to pass through. In the treatment of spent acid from acid soaking in quartz sand, the nanofiltration technology can be used to remove the heavy metal ions and part of the acid in the wastewater.

Membrane separation and recycling technology has the advantages of high efficiency, environmental protection, high degree of automation, and stable operation. It can not only achieve the efficient recycling of acid and heavy metal salts in the spent acid but also reduce wastewater discharge, reduce environmental pollution, and bring considerable economic benefits to the enterprise.

3. Application Cases of Membrane Separation and Recycling Technology in Quartz Sand Production

A quartz sand production enterprise uses membrane separation and recycling technology to treat the spent acid from acid soaking. Through the combined process of electrodialysis and reverse osmosis, it has successfully recycled the acid and heavy metal salts in the spent acid and produced high-quality recycled water. After implementing this technology, the enterprise's wastewater treatment cost has been reduced by more than 30%, and the recycled acid and heavy metal salts have brought additional economic benefits to the enterprise. In addition, the implementation of this technology has significantly reduced wastewater discharge, reduced environmental pollution, and enhanced the enterprise's environmental protection image and social responsibility.

4. Development Trends and Prospects of Membrane Separation and Recycling Technology

With the continuous development of membrane materials and the continuous innovation of membrane separation and recycling technology, membrane separation and recycling technology will play a more important role in the treatment of spent acid from acid soaking in quartz sand production. In the future, membrane separation and recycling technology will develop towards a more efficient, environmentally friendly, and intelligent direction. At the same time, the government and enterprises should also strengthen the research, development, and promotion of membrane separation and recycling technology to promote the sustainable development of the entire quartz sand industry.

The membrane separation and recycling treatment technology for spent acid from acid soaking in quartz sand production is an efficient and environmentally friendly wastewater treatment method. It can not only achieve the efficient recycling of acid and heavy metal salts in the spent acid but also reduce wastewater discharge, reduce environmental pollution, and bring considerable economic benefits to the enterprise. In the future, with the continuous development and improvement of membrane separation and recycling technology, it will play a more important role in quartz sand production and make greater contributions to the sustainable development of the quartz sand industry.