Polyacrylamide Specifically for Sand Washing Plants

Polyacrylamide specifically designed for sand washing plants. Anionic polyacrylamide is typically selected as the flocculant for sand washing. Anionic polyacrylamide is a water-soluble polymer. Due to the presence of a certain number of polar groups in its molecular chain, it is able to adsorb suspended solid particles in water, causing bridging between particles or, through charge neutralisation, causing the particles to aggregate and form large flocs.

It is used for flocculation and sedimentation in various industrial wastewater treatment processes, such as the clarification and treatment of wastewater from steel mills, sand washing plants, electroplating plants and coal washing plants, as well as for sludge dewatering. It can also be used for the clarification and purification of drinking water. When used in conjunction with inorganic flocculants such as polyaluminium chloride, the effect is even more pronounced.
 

The polyacrylamide-based flocculants used for sludge dewatering in sand washing plants are high-molecular-weight organic compounds. The molecular weights of the PAM produced by water treatment material companies are generally in the millions, with some even approaching 25 million. Consequently, their dissolution methods differ significantly from those of inorganic, low-molecular-weight iron salts (polyferric sulphate) and aluminium salt coagulants (poly aluminium chloride).
Particle size:

      1. Users at our sand washing plants should not add polyacrylamide flocculant directly to wastewater. It must first be dissolved in water, and the resulting aqueous solution should then be used to treat the wastewater.

      2. The water used to dissolve polyacrylamide flocculants and polyaluminium chloride coagulants should be clean water (such as tap water) and must not be wastewater; water at room temperature is sufficient. Generally, heating is not required. Dissolution is slow at water temperatures below 5°C. Higher temperatures accelerate dissolution, but temperatures above 40°C will cause the polymer to degrade more rapidly, thereby affecting performance. Tap water is generally suitable for preparing polymer solutions; however, water containing strong acids, strong alkalis or high levels of salt is not suitable for this purpose.

      3. The concentration of polyacrylamide and polyaluminium chloride solutions must be appropriate. The dissolution ratio for loading into vehicles is 0.1% to 0.3%. That is, 1–3 kg of solid polyacrylamide or polyaluminium chloride should be added to one tonne of clean water.

The following factors should be considered when selecting the concentration:

      If the chemical storage tank has a small capacity and the daily wastewater volume is high, a higher dosage is required. It is recommended to prepare a slightly more concentrated solution with a higher dosage. When the molecular weight of polyacrylamide is very high, it is recommended to prepare a slightly more dilute solution. Adding a 0.1% polyacrylamide solution to the wastewater results in a high polymer concentration. This can cause excessive load on the agitator motor and lead to poor dispersion of the polymer after the wastewater enters the system, thereby affecting the treatment efficacy.

Technical specifications for polyacrylamide used in sand washing plants
CAS Number:	9003-05-8
Product appearance:	White or slightly yellow granules
Particle size:	Granular (20–40 mesh), fine powder (40–60 mesh)
Molecular weight:	3–25 million (adjustable)
Degree of hydrolysis:	10-45%
Solid content:	≥88-90%
Water-insoluble matter:	≤0.02%
Dissolution time:	≤60MIN
Preparation concentration:	0.1% (typically) – 0.5% (higher)
Storage period:	Product (2 years), prepared solution (6–30 days)
Remaining units:	≤0.1%
Product application:	For industrial use