PAM usage and precautions

◆ Before the formal use of a PAM product, a small test should be carried out to determine the optimum dosage and conditions of use. When used as a flocculant, the dosage is generally 0.1 to 0.5 ppm.

◆ PAM products must be dissolved into a solution before use, so that the polymer chain is fully extended and ready for use. Usually, the nonionic and cationic products are diluted to about 0.1%, and the dissolution operation is carried out in a stirred tank of plastic, ceramic or stainless steel. Because the PAM molecular chain is a random coil in solution, when it is prepared and dissolved, part of the water is wrapped in the coil, the coil is bulky and full, and the coils are easily entangled and crosslinked with each other, from the outside. Certain viscosity. If the centrifugal pump is used to rotate the macromolecular coil structure due to the high-speed rotation of the impeller, it is separated from the middle, and the volume is changed. The cross-linking between the coils is degraded and the viscosity is lowered, thereby reducing the use effect.

◆ PAM molecular chain in the solution by the shear force will lead to molecular chain breakage degradation, affecting performance, so dissolve the diluted PAM should reduce the stirring time as much as possible to reduce the stirring intensity; reduce the stirring speed should generally be controlled at 50 ~ 250 rev / min It should not be too fast. When using PAM solution, the addition point should avoid strong mechanical agitation as much as possible; when conveying PAM solution, the pipeline should be thick, the head and branch pipe should be less, and the pump should use Mono pump or diaphragm pump instead of optional. Centrifugal pump.

◆ Dry powder PAM products should pay special attention to the operation procedure when dissolving, preventing the particles from sticking to each other and causing the dissolution operation to fail. In small tests, methanol can be used. Organic reagents such as ethanol are moistened to improve the dispersibility of the particles in water. For industrial applications, it should be completely dissolved in the container for 1/2 hour, and the instant soluble product is dissolved in 0.5 to 1 hour. Heating can accelerate the dissolution of the product, but should not exceed 60 ° C.

◆ When the inorganic flocculant is mixed with PAM, the inorganic flocculant and PAM should be dissolved in two stirring equipments respectively, otherwise the interaction between the two flocculants will occur, and agglutination will occur, which will affect the effect; Order, generally speaking, when processing fine particles with particle size below 50um, first add inorganic flocculant, then add PAM solution; while processing coarse particles with diameter above 50um, first add PAM solution for adsorption bridge, then add Flocculant. When using the user, a small experiment should be performed to determine the order of addition.

◆ As a general rule, when the solution conditions are more favorable for the polymer molecular chain to stretch, the use effect is better. Therefore, cationic PAM is suitable for acidic media, anionic PAM is suitable for alkaline media, and nonionic ionic PAM is suitable for acidic or weakly alkaline media; where possible, the PAM solution is diluted to 0.01% before use. 0.05%, which is beneficial to the further extension of the molecular chain, thereby improving the use effect and saving the amount.

◆PAM products should not be stored in iron containers. The dry powder PAM generally has stable long-term storage performance, and the PAM performance dissolved in water decreases with time, and the lower the concentration, the faster the performance declines. 0.05%-0.1% non-ionic or anionic PAM solution can only be stored for about half a month. 0.1% cationic PAM solution is extremely unstable. After 1-2 days, the performance begins to decrease. Therefore, PAM products should be equipped immediately. Used as well.

◆ Due to the uneven arrangement of lattice ions on the surface of mineral particles, excessive charge is generated, which has a strong influence on PAM molecules. The bridging effect of PAM is difficult to play, and it can only act with a single particle and suspend in the slurry. Properly adjusting the pH in the slurry to eliminate some of the excess charge can increase the flocculation effect.

◆ The consumption of PAM is proportional to the surface area of solid particles. If the diameter of minerals and intangible sediments is small, there is a large surface area, and the amount of PAM required is also large.

◆ If the sediment particles are very viscous and the surface is loose and charged, such as (iron oxide rubber particles) acrylamide will be evenly distributed, which will reduce the sedimentation and flocculation effect.

◆ toxicity of PAM:

PAM itself is not toxic, and only when the feed is greater than 5000 ppm, the absorption of nutrients into the gastrointestinal mucosa of the animal is sticky and harmful.

The residual monomer acrylamide (Am) in PAM is toxic. For oilfield use and municipal wastewater treatment, residual monomers are generally allowed to be around 1%. For food, such as drinking sucrose juice clarification, manufacturing may be related to food. The amount of residual monomer must be strictly controlled, such as paper contact, generally less than 0.05%.

◆The Japanese Environmental Health Administration stipulated in 1973 that polymer flocculant should not be used for domestic water. In 1975, the AM content of wastewater treatment PAM was 0.05%. Our country stipulates that the residual monomer content of PAM for food is also below 0.5%.