Silica sand acid pickling beneficiation plant photovoltaic Plate quartz China

1. One time molded PE tank, capable of insulation, non corrosive, and non leaking.

 

2. Heating to 65 ° C for reaction is not affected by changes in ambient temperature and does not affect the reaction outcome.

 

3. Acid return and cleaning inside the tank save equipment and space compared to traditional processes.

 

4. The aerodynamic agitation technology has significantly improved the results compared to traditional soaking and acid washing.

 

5. Environmentally friendly chemical formula, the quartz stone after acid washing does not change color or turn yellow after drying,

 

6. Acid and water are recycled and not discharged, which meets current environmental protection requirements.

The essence of quartz / silica sand acid washing process is a process of converting insoluble impurities into soluble ions through a series of chemical reactions between acid and oxidant under heating and stirring conditions, and then separating them through repeated water washing.
It is a highly effective but also highly demanding deep purification method for cost control, technical management, and environmental protection, and is one of the irreplaceable core technologies for producing high-purity quartz sand.

 

1. Acid base neutralization reaction:
Most metal impurities (such as iron and aluminum) exist in the form of oxides (such as Fe2O3, Al2O3). These metal oxides are alkaline or amphoteric and can react with inorganic acids (such as hydrochloric acid HCl, sulfuric acid H2SO4, oxalic acid H2C2O4) to form water-soluble salts, which can be removed.

·Example:

·Fe2O3+6HCl → 2FeCl3+3H2O (iron oxide reacts with hydrochloric acid to form soluble iron chloride and water)

·Al2O3+6HCl → 2AlCl3+3H2O (aluminum oxide reacts with hydrochloric acid to form soluble aluminum chloride and water)

2. Redox reaction:
For some stubborn impurities that exist in a low valence state (such as divalent iron Fe ² ⁺, often in the form of FeO or FeS2), simple acid dissolution is not effective. At this point, a strong oxidant (such as hydrogen peroxide H2O2) needs to be added to oxidize low valence ions into high valence ions (such as Fe ³ ⁺), and the resulting oxide is more likely to react with acids and be dissolved and removed.

1. Pre processing (ore preparation and crushing)

·Purpose: To create favorable conditions for acid washing and improve acid washing efficiency.

·Steps:

·Washing/scrubbing: Remove surface impurities such as soil and dust that are prone to detachment.

·Crushing and grading: Crushing ( jaw crusher , ball mill ) the raw ore to a suitable particle size (usually 0.1-1.0mm) to allow the acid solution to fully contact impurities. And sieve to obtain uniformly sized sand particles.

2. Hot acid leaching (core step)

·Objective: To fully react with impurities using acid solution under heating conditions.

·Steps:

·Put the pre treated quartz sand into an acid resistant reaction vessel (usually made of fiberglass, PVC, or concrete lined with acid resistant bricks).

·Add a certain concentration of mixed acid (common combination: hydrochloric acid+sulfuric acid+oxalic acid+hydrogen peroxide). Different ratios target different impurities.

·Heating and stirring: usually raise the temperature to 50-80 ° C and continue mechanical stirring for several hours. Heating can greatly accelerate the chemical reaction rate, while stirring can prevent quartz sand precipitation and ensure uniform reaction.

·Reaction time: Depending on the impurity content and quartz particle size, it usually takes 4-12 hours.

3. Neutralization and washing

·Purpose: Thoroughly wash away residual acid and soluble salts generated by the reaction.

·Steps:

·Acid discharge: After the reaction is complete, the waste acid solution is first discharged and collected for treatment.

·Water washing: Inject a large amount of clean water into the reaction vessel, stir and wash, and then discharge the wastewater. This process is usually repeated multiple times until the eluent is neutral (pH ≈ 7).

·Alkali neutralization (optional): To ensure complete removal of adsorbed acid ions, sometimes dilute alkaline solution (such as NaOH) is briefly soaked for neutralization, and then washed with clean water until neutral.

4. Dehydration and drying

·Objective: To obtain a dried final product.

·Steps:

·Mechanically dehydrate the cleaned quartz sand through a centrifuge or filter press to remove most of the moisture.

·Send the dehydrated wet sand into a drying machine (such as a rotary kiln or fluidized bed dryer) for drying to obtain dry quartz sand with extremely low moisture content (<0.5%).

5. Subsequent processing (optional)

·Magnetic Separation: After acid washing, high gradient magnetic separation may also be performed to remove residual trace amounts of iron impurities.

·Flotation: Used for separating other silicate minerals (such as feldspar and mica) that coexist with quartz.

 

1. Acid base neutralization reaction:
Most metal impurities (such as iron and aluminum) exist in the form of oxides (such as Fe2O3, Al2O3). These metal oxides are alkaline or amphoteric and can react with inorganic acids (such as hydrochloric acid HCl, sulfuric acid H2SO4, oxalic acid H2C2O4) to form water-soluble salts, which can be removed.

·Example:

·Fe2O3+6HCl → 2FeCl3+3H2O (iron oxide reacts with hydrochloric acid to form soluble iron chloride and water)

·Al2O3+6HCl → 2AlCl3+3H2O (aluminum oxide reacts with hydrochloric acid to form soluble aluminum chloride and water)

2. Redox reaction:
For some stubborn impurities that exist in a low valence state (such as divalent iron Fe ² ⁺, often in the form of FeO or FeS2), simple acid dissolution is not effective. At this point, a strong oxidant (such as hydrogen peroxide H2O2) needs to be added to oxidize low valence ions into high valence ions (such as Fe ³ ⁺), and the resulting oxide is more likely to react with acids and be dissolved and removed.