Acid washed quartz sand

Quartz sand pickling and pickling process detailed

In the selection of purified quartz sand and high purity quartz sand, it is difficult to meet the requirements of conventional beneficiation methods, especially for the iron oxide film on the surface of quartz sand and the iron impurities in the cracks. In order to better improve the quality and yield of quartz sand purification, combined with the characteristics of quartz sand insoluble in acid and slightly soluble in KOH solution, the acid leaching method has become a necessary means to treat quartz sand.

Quartz sand pickling treatment is to treat quartz sand with hydrochloric acid, sulfuric acid, oxalic acid or hydrofluoric acid to dissolve iron.

Basic process of quartz sand pickling

I proportioning acid lotion

Tons of sand need to be made of 7-9% oxalic acid, 1-3% hydrofluoric acid and 90% water mixture; Requires 2-3.5 tons of water, if the water is recycled, then only 0.1 tons of water is needed to clean a ton of sand, in the sand cleaning operation, will inevitably bring most of the sand up; Quartz sand pickling treatment is to treat quartz sand with hydrochloric acid, sulfuric acid, oxalic acid or hydrofluoric acid to dissolve iron.

Ⅱ Pickling mix

The pickling solution is injected into the pickling tank and added according to the proportion of hydrochloric acid content as about 5% of the sand weight to ensure that the quartz sand is soaked in the pickling solution and the hydrochloric acid content is about 5% of the sand weight.

Ⅲ Acid-washed quartz sand
① The time for quartz sand to soak the pickling solution is generally 3-5 hours, the specific need to increase or decrease the soaking time according to the yellow skin of quartz sand, or the pickling solution and quartz sand can be stirred for a period of time, followed by the use of heating equipment to heat the solution to a certain temperature, can reduce the pickling time.

② The use of oxalic acid and green alum as reducing agent pickling treatment can improve the solubility of iron, in turn, water, oxalic acid, green alum in accordance with the proportion of the solution at a certain temperature, quartz sand and solution in accordance with a certain proportion of mixing, stirring, treatment for a few minutes, the solution is filtered out and treated after recovery.

③ Hydrofluoric acid treatment: The effect is good when hydrofluoric acid treatment is applied alone, but the concentration is higher. When shared with sodium dithionite, lower concentrations of hydrofluoric acid can be used.

A certain concentration of hydrochloric acid and hydrofluoric acid solution were mixed into the quartz sand slurry at the same time according to the proportion; It can also be treated with hydrochloric acid solution first, washed and then treated with hydrofluoric acid, treated at high temperature for 2-3 hours, and then filtered and cleaned.

Note:

If hydrofluoric acid is used to acid soak quartz sand, the reaction is more complicated. In addition to the dissolution of iron in acidic media, HF can also react with quartz itself to dissolve SiO2 and other silicates of a certain thickness on the surface.

However, this is more effective for cleaning the surface of quartz sand and eliminating iron and other impurity pollution, so hydrofluoric acid is good for acid leaching of quartz. However, HF is toxic and highly corrosive, so the acid leaching wastewater needs special treatment.

Iv Acid recovery and deacidification

Rinse the acid-washed quartz sand with water 2-3 times, and then neutralize with 0.05%-0.5% of sodium hydroxide (caustic soda) alkaline solution, and the neutralization time is about 30-60 minutes, and ensure that all the quartz sand is neutralized in place. When the pH reaches alkaline, you can release lye and rinse 1-2 times until the pH is neutral.

Ⅴ Dry quartz sand

The quartz sand should be drained of water after acid withdrawal, and then the quartz sand should be dried in the drying equipment.

Ⅵ screening, color selection and packaging, etc.

The above is the basic process of quartz sand pickling and leaching treatment process, quartz sand ore has a relatively wide distribution in our country, so there are differences in the nature of quartz sand, in the purification of quartz sand also need to specific problems specific analysis, develop a suitable quartz sand purification process.