Brief introduction of molecular sieve production process

1. Molecular sieve introduction

Molecular sieve is a silicate compound with cubic lattice. The molecular sieve has a uniform microporous structure, and its pore diameter is uniform. These pore holes can adsorb molecules smaller than its diameter to the inside of the pore cavity, and have the priority adsorption capacity for polar molecules and unsaturated molecules. Therefore, it can separate molecules with different polarity, saturation, molecular size and boiling point, which has the function of "screening" molecules, so it is called molecular sieve. Molecular sieves are widely used because of their high adsorption capacity, strong thermal stability and other advantages that other adsorbents do not have.

2. Molecular sieve production process

2.1 raw material mixing:

Pour kaolin and 4A/3A zeolite raw powder into the cone mixer according to a certain proportion, and turn on the mixer to stir for about 90min. The more uniform the mixture is, the better.

2.2 granulation:

Put the evenly stirred raw powder into the swing granulator in batches, turn on the swing granulator, and add sodium tripolyphosphate solution while stirring (the concentration of sodium tripolyphosphate solution is water: sodium tripolyphosphate = 20:1). Small grains can be screened out. This step is required for the first granulation to produce crystal grains. As long as the production is not stopped in the future, this step is no longer required to produce crystal grains.

Turn on the sugar-coated machine. Pour the produced grains into it, and slowly spray the prepared sodium tripolyphosphate solution. When the particles are wet, sprinkle the mixed raw materials into it. After a period of time, the grains will gradually increase, and this process is granulation.

2.3 screening:

When the particle size in the sugar-coated machine increases to a certain extent, take it out and screen it on a flat screen. Generally, sifting is carried out on a sieve of 1.0-1.4mm, and three kinds of particles (I .e., less than 1.0mm, between 1.0-1.4mm, more than 1.4mm) are put into different sugar-coated machines for granulation respectively. This cycle operation means granulation. When the particle size meets the required requirements, stop spraying the solution and no longer add the original powder. This process is called exposure, and it can be taken out of the pot after exposure for half an hour.

The molecular sieve out of the pot must be tested by the laboratory strength first, and it can be out of the pot only when its strength meets the standard. Otherwise, it is an unqualified product, and it can be crushed as raw powder or treated with other treatments.

2.4 drying:

The drying process of putting the molecular sieve out of the pot into the belt dryer; The belt dryer is divided into four heating zones, and the temperature is respectively set as: 50℃ in the first zone, 70℃ in the second zone, 80℃ in the third zone and 60℃ in the fourth zone. The smaller the pushing speed of the belt dryer, the better the drying effect.

2.5 roasting:

Put the dried molecular sieve into a roasting furnace for calcination to obtain the finished molecular sieve. The first use of the roasting furnace needs to be preheated for two days, and then it needs to be preheated for one day at intervals. The roasting furnace is divided into 9 heating zones, and the optimal heating temperature of molecular sieves with different particle sizes is different. If the temperature is too high or too low, it will lead to the deterioration of strength and water absorption; The temperature difference between muffle furnace used in laboratory and baking furnace used in industry is about 100℃, so the molecular sieve can be measured at the best temperature in laboratory first, and the best baking furnace calcination temperature can be obtained by adding 100℃. At present, the calcination temperatures of different particle sizes are as follows:

When the particle size is less than 1.6mm, the set temperature of each area of the roasting furnace is 450, 450, 500, 550, 600, 650, 700, 700, 600., and the flow rate V = 35 G/s.

When the particle size is less than 1.6-2.4mm, the set temperature of each area of the roasting furnace is 450, 450, 500, 550, 600, 700, 750, 750, 600, and the flow V = 35 G/s.