Preparation method of double-shell hollow large granule material
Technical Field
The invention belongs to the field of environment treatment and building heat insulation materials, and also can be used for agricultural ridging materials, in particular to a preparation method of a double-shell hollow large granule material.
Background
In recent years, along with the increasing global water pollution, biofilters are widely applied in sewage treatment processes. The ceramsite is a porous substance with a rough surface as a filter material, has good microorganism adhesiveness and certain adsorption capacity, and can be widely applied to water treatment as a biological filter material and a substrate.
At present, a patent product CN 103496866B is available, and the disclosed core-shell type baking-free lightweight aggregate is used as a baking-free ceramsite and is already applied to the aspects of building heat preservation and environmental treatment, but the core-shell type baking-free lightweight aggregate has poor toughness and is easy to damage and leak the EPS core by a forklift when being used in bulk; if the porous material is used as a filter material, the total porosity of particles is low due to the existence of the inner core, and the filtering capability is insufficient. The patent product CN 102936127 a discloses a sintered lightweight hollow ceramsite, which is obtained by removing EPS nuclei in the ceramsite to be hollow by sintering, but this way of preparing the ceramsite has high energy consumption and poor toughness. The Liaoning architecture professional college Huanglihua research prepares a multi-shell baking-free ceramsite, but the baking-free ceramsite has high density, low specific strength, low porosity and water absorption, and insufficient filtering capability if used as a biological filter material.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a preparation method of a double-shell hollow large granule, and the prepared double-shell hollow large granule has the characteristics of high crack resistance, light weight, high specific strength (strength under unit density, namely high strength under the same density or low density under the same density), good toughness, good heat insulation performance, good fire resistance and the like, is hollow, has high porosity and has good filtering capacity.
The technical scheme of the invention is as follows:
a preparation method of a double-shell hollow large granule material comprises the following steps:
step 1), taking water-absorbent resin particles as a core, and carrying out pre-water saturation treatment on the water-absorbent resin particles, wherein the water saturation degree is controlled to be 75-90%;
step 2) preparing an inner shell layer strengthening solution, placing the water-absorbent resin which is saturated by water and is prepared in the step 1) into the inner shell layer strengthening solution, and stirring;
step 3) selecting a silicate cement-based material or a phosphate cement-based material as a cementing material, and wrapping the water-absorbing resin treated in the step 2) and the cementing material into a shell by adopting a balling process;
step 4) naturally curing the water-absorbing resin wrapped into the shell prepared in the step 3) for 1-4 h;
step 5) preparing a shell layer strengthening solution, and spraying the shell layer strengthening solution on the surface of the cured material prepared in the step 4);
and 6) sealing, drying and maintaining the material treated in the step 5) to obtain the material.
Preferably, the particle size of the water-absorbent resin which is saturated with water is 2-7 mm.
Preferably, the inner shell layer strengthening solution consists of the following raw materials in percentage by weight: 10-30% of sodium silicate, 0.5-5% of silicon dioxide powder, 5-30% of industrial starch, 0.5-2% of fiber material and the balance of water.
Preferably, the fiber material is polypropylene fiber with the length of 2-3 mm.
Preferably, the shell layer strengthening solution consists of the following raw materials in percentage by weight: 5-20% of sodium silicate, 0-3% of silicon dioxide powder and the balance of water.
Preferably, the drying and curing temperature in the step 6) is 100-150 ℃.
The invention has the following advantages:
(1) the water-absorbent resin is used as a core material, and the core material does not contain inflammable substances, so that the fire resistance of the aggregate is effectively improved. On one hand, the inner core of the water-absorbent resin is dehydrated by adopting a drying and maintaining mode at 100-150 ℃, so that a hollow structure is formed, and the density is reduced; on the other hand, the inside evaporated moisture can make the shell material form sufficient steam curing, which is beneficial to improving the specific strength of the large-particle material.
(2) The solution containing the reinforcing material is used as the later-stage absorption liquid of the water-absorbent resin, so that the specific strength of the aggregate can be improved, and the early-stage conveying of the aggregate is facilitated.
(3) The reinforcing material of the inner shell layer is doped with fibers, so that the characteristics of early brittleness and easy cracking of the aggregate can be obviously improved.
(4) The outer layer is also made of solution containing reinforcing material, and the solution containing penetrating material is sprayed or roll-coated on the particles to form a hard shell layer on the surfaces of the particles.
(5) The inner core is resin, if the inner core is used as a building heat-insulating material, the inner core cannot burn due to the absence of oxygen at high temperature, and the inner core needs to absorb heat when the inner core is melted, so that the propagation speed of heat is reduced, and the spreading speed of fire is relieved.
(6) The prepared double-shell hollow large-particle material has high porosity, and the high porosity can ensure good heat insulation performance, and can obviously improve the heat insulation performance of a product when being used in a heat insulation product; the water absorption rate of the material can be effectively improved, and can reach over 17% through detection, and the water filtering capacity is strong.
Drawings
FIG. 1 is a flow chart of a preparation method of a double-shell hollow large granule material;
FIG. 2 is a diagram of a finished product of a double-shell hollow large granule material;
FIG. 3 is a cross-sectional view of a double-shell hollow macroparticle;
FIG. 4 is a partially enlarged cross-sectional view of a double-shell hollow macroparticle.
Detailed Description
The invention is further illustrated with reference to the accompanying drawings and specific embodiments.
Example 1
A preparation method of a double-shell hollow large granule material is shown in figure 1, and the selected materials and steps are as follows:
(1) a water-absorbent resin having a diameter of 6mm after water absorption was used as the inner core, and the water retention level of the water-absorbent resin was controlled to 75% in advance.
(2) Preparing an inner shell layer strengthening solution, adopting a 30% sodium silicate solution, and adding 2% of silicon dioxide powder and 0.5% of polypropylene fibers (the length is 2-3 mm).
(3) Placing the water-absorbent resin which is saturated with water into the inner shell layer strengthening solution, and slowly stirring for 1 min.
(4) The Portland cement with the components of 40 percent, 20 percent of mineral powder and 40 percent of fly ash are used as cementing materials (1-1 group); or the components are 75 percent of phosphate cement and 25 percent of fly ash as the cementing material (1-2 groups).
(5) Putting the pretreated water-absorbing resin and the cementing material into a balling disc together to wrap the powder into balls.
(6) Preparing a shell layer strengthening solution by using a 5% sodium silicate solution.
(7) Naturally curing the balled material for 4h (1-1 group) or 1h (1-2 group), placing the cured material in a rotary drum, and atomizing and spraying a shell layer strengthening solution.
(8) Sealing, and curing in a 110 deg.C oven.
The properties of the prepared products are shown in groups 1-1 and 1-2 in Table 1.
Example 2
A preparation method of a double-shell hollow large granule material is shown in figure 1, and the selected materials and steps are as follows:
(1) a water-absorbent resin having a diameter of 6mm after water absorption was used as the inner core, and the water retention level of the water-absorbent resin was controlled to 75% in advance.
(2) Preparing an inner shell layer strengthening solution, adopting a 10% sodium silicate solution, and adding 5% industrial starch and 2% polypropylene fiber (the length is 2-3 mm).
(3) Placing the water-absorbent resin which is saturated with water into the inner shell layer strengthening solution, and slowly stirring for 1 min.
(4) Phosphate cement with the components of 90 percent and fly ash silica-based material with the components of 10 percent are adopted as cementing materials (group 2-1); or the components of 50 percent of Portland cement and 50 percent of fly ash silica-based material are used as the cementing material (group 2-2).
(5) Putting the pretreated water-absorbing resin and the cementing material into a balling disc together to wrap the powder into balls.
(6) Preparing a shell layer strengthening solution, adopting a 20% sodium silicate solution, and adding 3% silicon dioxide powder.
(7) Naturally curing the balled material for 1h (2-1 group) or 4h (2-2 group), placing the cured material in a screw conveyor, and atomizing and spraying a shell layer strengthening solution.
(8) Sealing, and curing in a 110 deg.C oven.
The properties of the prepared products are shown in groups 2-1 and 2-2 in Table 1.
TABLE 1 Properties of the double-shelled hollow macroparticles
As can be seen from Table 1, the successfully prepared double-shell hollow large-particle material has the advantages of light weight, large porosity, high water absorption, strong water filtration capacity and certain strength, and can be well applied to biological filter materials. The macroporosity can ensure good heat insulation performance, and when the material is used in a heat insulation product, the heat insulation performance of the product can be obviously improved; the water absorption of the material can be effectively improved and can reach more than 17% through detection. The finished product is shown in figures 2, 3 and 4.
The above description is only a part of the implementation method of the present invention, and it should be noted that: it will be apparent to those skilled in the art that several contemplated modifications and adaptations can be made without departing from the principles of the invention and these are intended to be included within the scope of the invention.