HENGFENG Anionic polyacrylamide emulsion is widely used in the alumina separation process. It serves as a flocculant to promote the settling of solid - liquid mixtures, improve separation efficiency, and enhance product quality. The following is a detailed introduction:

· Role in the alumina separation process: In the alumina production process, especially in the Bayer process, after bauxite is dissolved in caustic soda solution at high temperature and pressure, a large - amount of solid - liquid mixture containing red mud and aluminum - sodium solution is formed1. Anionic polyacrylamide emulsion can adsorb and bridge the fine - grained solid particles in the slurry. By adding an appropriate amount of anionic polyacrylamide emulsion to the primary thickener, the red mud particles can be aggregated into larger flocs, accelerating their sedimentation rate. This helps to obtain clear overflow liquid, reduce the loss of aluminum - sodium solution, and improve the efficiency of subsequent filtration and other operations. In addition, in the counter - current decantation process for red mud washing, anionic polyacrylamide emulsion is also used to promote the settlement of residual red mud particles, so as to recover more alumina from the solution and improve the utilization rate of resources.

· Product characteristics required:

· High molecular weight: Usually, anionic polyacrylamide emulsion with a high molecular weight is required. High - molecular - weight polymers can form longer molecular chains, which are more conducive to adsorbing and bridging between particles, and can form larger flocs.

· Adjustable hydrolysis degree: According to different bauxite qualities and process requirements, the hydrolysis degree of anionic polyacrylamide can be adjusted. Generally, the hydrolysis degree is in the range of 6% - 45%. A suitable hydrolysis degree can ensure that the product has a good charge - density, so as to better adsorb particles with opposite charges or neutral particles through electrostatic interaction.

· Good water - solubility: It can be quickly and evenly dissolved in water to form a uniform solution, so as to be effectively mixed with the alumina - containing slurry. It is usually required to be dissolved in low - hardness water, and the dissolution time is generally within 1 hour.

· Usage :

· Dispersion: Efficient dispersion is very important during use. Otherwise, agglomeration and “fish eyes” will occur, and the dissolution time will be prolonged.

· Water quality: Use low - hardness water, and avoid using tanks or pools that may affect water quality.

· Temperature: Appropriate heating can accelerate the dissolution rate, but the water temperature should not exceed 50℃.

· Stirring: Stirring can accelerate dissolution, but strong stirring will break the molecular chain of the dispersant and cause degradation. A ship - shaped agitator with a rotation speed of 200 - 500 rpm is the best.

· Concentration preparation: Usually, the product is mixed into a 0.05% - 0.5% (w/w) solution for standby.

· Dosage adjustment: The optimal dosage should be adjusted according to specific application conditions to achieve the best flocculation effect and economic benefits.