CS249906B1 - Continuous method of producing silicate gels - Google Patents

Abstract

The solution concerns a continuous method of producing silicate gels in a system of at least two mixers. The essence of the solution lies in the fact that the raw materials are first brought into contact in a liquid state in a screw mixer, in which the initial gel is prevented from adhering to the reactor walls and the formation of larger lumps is prevented. The screw mixer simultaneously acts as a means of transporting the initial gel to a second mixer, equipped with a high-shear mixer, in which a gel suitable for further processing is formed - ripening, crystallization. In the case of large-scale production of silicate gels, it is advantageous to include a third mixing element in the mixer system, equipped with, for example, paddle mixers and high-shear mixers. In this third stage of mixing, the gel is homogenized.

Description

249906

The present invention relates to a continuous process for producing silicate gels from raw materials in a liquid state in a mixer system.

In the process of preparing the gels, the sapo coupling of the liquid reactants produces a gel which cannot be mixed with the high shear mixers in combination with the high shear mixers over a period of a few minutes to a few minutes. As a result, relatively large lumps of unmixed gel causing, for example, the formation of undesirable crystal-zeolite molecular sieves are formed in the reactor compartments with low mixing intensity. The lumps of unmixed gel remain unreacted and strongly adhere to the reactor walls and require constant purification. At the same time, they cause a change in the chemical composition of the reacting gel and thereby the S102 module to Al2O3.

The aforementioned drawbacks are not due to the production of silicate gels, the principle of which is to bring the starting materials in liquid state into a mixture of mixers, initially in a screw mixer, then in a mixer with a stirrer. with large shearing screens and / or in a mixer provided with either bladed stirrers or with a high shear mixer, or a combination of these stirrers. In the first stage of gel formation and the formation of lumps of high adhesion to the walls of the reactor, it is prevented by mixing in the screw mixer. It produces a gel that is capable of being transported by screw to the second stage of gel formation, namely a large shear mixer, in which a gel suitable for further processing is formed. In the case of high-volume production of silicate gels, it is advantageous to include a third mixer, provided with, for example, paddle mixers and high shear mixers, in the mixer system. At this third stage of mixing, the gel is homogenized. As a rule, this third barge mixer is volume-friendly. Its dimensions are chosen so that there is a minimum of half an hour of delay in the gel. In this way, it is possible to prepare gels of the types of zeolite molecular sieves.

By means of a mixer system, an easy transition of silicate gel production from small capacity to large-scale production is achieved in a continuous manner. In the low volume mixing system, a relatively high performance of silicate gel production is achieved.

The process of the present invention makes it possible to produce high quality gels. The equipment is not labor-intensive and does not require cleaning except for repairs.

It allows the gels to be prepared, for example, by a high modulus of S102 to Ο2Ο3, resulting in the use of raw materials for high percentages, increasing the specific power, for example, crystallisers to three to four times the need to increase the number of workers, allowing the application of large capacity crystallizers and reducing specific consumption. energy and raw materials. It provides a uniform high quality of gels which do not give rise to parasitic crystals. The continuous production of silicate gels according to the invention makes it possible to improve the economics of their production.

According to the invention, it is possible to prepare starting gels for the preparation of polymorphamorphic and crystalline aluminosilicates.

The schematic diagram of a two- and three-stage mixing system is shown in Figures 1, 2 and 3.

In Figure 1, A, B means the planar feed, 1 screw mixer, 2 mixer equipped with a large shear mixer, 3 mixer mixer paddle mixer and high shear mixer, C silicate gel.

In Figure 2, A, B means feedstock feed, 1 screw mixer, 2 mixer, 0-packed with a large shear mixer, C silicate gel.

In Figure 3, A, B means feedstock feed, 1 screw mixer, 3 mixer by combining vane stirrers and large shear stirrers, C silicate gel.

By way of illustration, examples are given but are not intended to limit the scope of the invention. Example 1 910 parts by volume of silicic acid salt containing 25.0% by weight of silicate. S1O2, 0.3% by weight. Na2O and 74.7 wt. water and 600 parts by weight of sodium aluminate containing 5, 4% by weight. Al2O3, 13.3 wt. Na 2 O and 81.3% wt. water is pumped by separate pumps and pipes in 1 hour at 18 ° C and contacted in a first stage of a mixing system consisting of a screw mixer, and the resulting gel is transported at 25 ° C to the second stage of the mixing system by high shear forces. The second mixer gel is fed to the third stage of the mixing system provided with bladder agitators and one high shear mixer. The three-part mixing system has a size of 1,500 volume parts. The gel temperature is 25 ° C. The gel coming out of the third mixing knot is collected in a crystallizer containing 12,000 parts by volume. At 25 degrees Celsius, it is left for 24 hours then warmed to 95 ° C. After 48 hours of crystallization, a faujasite is obtained with modulus of SiO2: Al2O3 '5.1.

Claims (3)

A continuous process for producing silicate gels, characterized in that the raw materials are brought into contact in the liquid state in a system of at least two mixers, first in a screw mixer, then in a mixer equipped with high shear mixers and / or in a mixer equipped with a paddle. or high shear mixers or a combination of these.