What acid is used for quartz sand pickling?

For the production of high purity quartz sand, the removal of iron film is a very important problem. Scrubbing, ultrasonic cleaning and pickling are the main methods to remove film iron, and pickling is the most common and effective method.

The purpose of pickling is to eliminate impurities such as metal oxides or fine silicate minerals, which are difficult to dissolve in water and soluble in acid. Generally, the mixed acid composed of hydrochloric acid, nitric acid, sulfuric acid and hydrofluoric acid should be determined according to the surface pollution of raw materials and determined by experiments. The acid treatment also has a certain effect on eliminating inclusions on the surface of powder, and the effect is better when the temperature is raised.
So what is the most commonly used acid in pickling quartz sand washing plant?
1. Hydrochloric acid (HCL)
Hydrochloric acid molecular formula: HCl, properties: colorless transparent liquid, hydrochloric acid with impurities is yellowish. Specific gravity: 1.19, strong irritant and corrosive, toxic.
Hydrogen chloride does not react with water, but it is soluble in water. It often exists in the form of hydrochloric acid smoke in the air. Dry hydrogen chloride can not react with active metals such as zinc, magnesium, iron and most metal oxides. However, the chemical properties of wet hydrogen chloride gas are quite active and can react with the above metals and oxides.

2. Oxalic acid
Oxalic acid molecular formula: H2C2O4, molecular weight: 90.04, colorless monoclinic flake or prism crystal or white powder. It can be used as a complexing agent, masking agent, precipitant or reducing agent. It can be used to precipitate calcium, magnesium, thorium and rare earth elements. The common oxalates are sodium oxalate, potassium oxalate, calcium oxalate, ferrous oxalate, antimony oxalate and ammonium hydrogen oxalate.