NL2022564A

NL2022564A - Method for improving expansion property of vermiculite

Info

Publication number: NL2022564A
Application number: NL2022564A
Authority: NL
Inventors: Tian Weiliang; Ge Zhenhong; Liu Xiaojing
Original assignee: Univ Tarim
Priority date: 2018-07-28
Filing date: 2019-02-13
Publication date: 2020-01-31
Also published as: NL2022564B1; CN108793178A; CN108793178B

Abstract

A method for improving expansion property of vermiculite is provided. The method includes: performing hydrothermal modiﬁcation of raw ore of vermiculite and water or a salt solution by heating and magnetic stirring under a high temperature and a high 5 pressure, and expanding the materials after hydrothermal modiﬁcation to obtain expanded vermiculite. In the present disclosure, water molecules and ions between layers of the vermiculite are regulated With a high temperature and a high pressure, thereby regulating the expansion rate or the peeling degree of the vermiculite. Therefore, the present disclosure has such advantages as simple and effective regulation, high lO expansion rate, easy peeling, simple devices, improved productivity, less pollutants, apparent economic value and the like.

Description

METHOD FOR IMPROVING EXPANSION PROPERTY OF VERMICULITE

FIELD OF THE INVENTION [001] The present disclosure relates to the technical field of vermiculite, and in particular to a method for improving expansion property of vermiculite.

BACKGROUND OF THE INVENTION [002] Vermiculite is one of important non-metallic minerals with good resource prospects and potential advantages in China, and is a magnesium-containing hydroaluminosilicate secondary metamorphic mineral with a layered structure. It is a layered silicate which is cheap and easy to obtain. Vermiculite is high temperature resistant, a poor conductor of heat and has good electrical insulation property. Expanded vermiculite can easily absorb water and moisture. Vermiculite expands at a high temperature and then can be easily peeled off Vermiculite has advantages such as good exchange capacity of interlayer cations, good expansion ability, good adsorption capacity, good sound insulation, good thermal insulation, good fire resistance and good freezing resistance. In addition, vermiculite has a stable chemical property, is insoluble in water, non-toxic, tasteless, and has no side effects. In the industry, based on its good adsorption performance and ion exchange performance, vermiculite is mainly used to treat wastewater containing heavy metals and organic cations, and to prepare antibacterial materials and thermal insulation materials, vermiculite filter aids, cleaning agents, organic vermiculite and the like.

[003] Vermiculite is a kind of layered material, and a key to the industrial application thereof is to expand it to obtain the layered material before using. Actually, the peeling degree is improved as the expansion rate increases, thus the performance of the vermiculite is improved. Therefore, a key problem in expanding the application of vermiculite is how to effectively increase the expansion rate or peeling degree of vermiculite. Therefore, it is of important practical significance to research on the peeling and expansion rate of vermiculite.

[004] Chinese Publication No. CN101172802A discloses a method for preparing expanded vermiculite based on microwave. In the method, vermiculite is expanded by means of microwave, and the microwave interacts with the vermiculite. In this way, a microwave effect results in a violent vibration of water between layers of the vermiculite, a local temperature between the layers increases rapidly, the water between the layers rapidly vaporizes, and a local pressure generated by water vaporization separates the layers of the vermiculite. This is expressed macroscopically as rapid expansion of vermiculite. In this way, a process of high temperature expansion is avoided, thereby preventing the expanded vermiculite from becoming brittle. Moreover, since the vermiculite is cleaned and impurity-removed before the expansion, the impurity content is reduced, and the quality of the expanded vermiculite is improved. The high-quality expanded vermiculite prepared by this method can be used for preparing high-quality expanded vermiculite powder for using in thermal barrier coating of high temperature mechanical component, preparing filler for synthesizing organic clay composite material, preparing filling material for energy-saving thermal insulation wall, preparing raw materials for high-quality thermally insulative vermiculite plates, and the like. However, the expansion rate of the vermiculite obtained with this method is not high enough.

SUMMARY OF THE INVENTION [005] A method for improving expansion property of vermiculite is provided according to the present disclosure, with which an expansion rate and a peeling degree of the vermiculite can be improved.

[006] In order to achieve the above object, a method for improving expansion property of vermiculite is provided according to the present disclosure. The method includes: placing raw ore of vermiculite and water or salt solution in a high-pressure resistant container, wherein a magnetic stirrer is placed in the high-pressure resistant container, magnetic stirring is provided at the bottom of the high-pressure resistant container, and a heating device is provided outside the high-pressure resistant container; heating the raw ore for hydrothermal modification; removing the solution by filtration after the hydrothermal modification; and performing expansion to obtain expanded vermiculite, wherein the expansion is performed by means of microwave, ultrasonic or heating.

[007] Optionally, a weight ratio of the raw ore of vermiculite to the water or the salt solution is 1: (0.1-100), a stirring rate is l-1000rpm, a microwave power is 1001800W, and a rotating speed of the magnetic stirring is l-500rpm.

[008] Optionally, a temperature for the hydrothermal modification is 101-450°C, and a duration of the hydrothermal modification is 0.5-72 hours.

[009] Optionally, the method further includes: before the hydrothermal modification, pulverizing the raw ore of vermiculite to obtain vermiculite particles, wherein a particle size of the vermiculite particles is 1-120 mesh.

[010] Optionally, the method further includes: performing hydrothermal modification on the raw ore of vermiculite, the water and an inorganic salt altogether, wherein a weight ratio of the raw ore of vermiculite to the inorganic salt is 1: (0.01-10), and a solid/liquid volume ratio is 1:1-10.

[011] Optionally, the inorganic salt is one or more of sodium chloride, potassium bromide, potassium chloride, potassium nitrate, magnesium chloride, ferric chloride, aluminium chloride or ammonium chloride.

[012] Optionally, the method further includes: performing hydrothermal modification on the raw ore of vermiculite, the water and an organic cationic surfactant altogether, wherein a weight ratio of the raw ore of vermiculite to the organic cationic surfactant is 1: (0.01-5).

[013] Optionally, the organic cationic surfactant includes cetyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, cetylpyridinium bromide or tetramethylammonium bromide.

[014] Optionally, the hydrothermal modification is carried out by means of microwave, infrared ray, heating by an oven or a high temperature furnace.

[015] The present disclosure has the following advantages.

[016] In the present disclosure, water molecules and ions between the layers of the vermiculite are regulated with a high temperature and a high pressure, thereby the goal of regulating the expansion rate or the peeling degree of the vermiculite is achieved. Therefore, the present disclosure has such advantages as simple and effective regulation, high expansion rate, easy peeling, simple devices, improved productivity, less pollutants, apparent economic value and the like.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE DIVENTION [017] The following embodiments are only provided for illustrating the present disclosure, and are not intended to limit the scope of the present disclosure.

[018] A method for improving expansion property of vermiculite is provided according to the present disclosure. The method includes: placing raw ore of vermiculite and water or salt solution in a high-pressure resistant container, wherein a magnetic stirrer (a magnetic stirring bar) is placed in the high-pressure resistant container, magnetic stirring is provided at the bottom of the high-pressure resistant container, and a heating device is provided outside the high-pressure resistant container; heating the raw ore for hydrothermal modification; removing the solution by filtration after the hydrothermal modification; and performing expansion to obtain expanded vermiculite, wherein the expansion is performed by means of microwave, ultrasonic or heating. In the present disclosure, an expansion rate and a peeling degree of the vermiculite are improved, and an effective peeling is achieved. Hence, the present disclosure has a simple process, is easy to promote, and has apparent economic value.

[019] In the present disclosure, the hydrothermal modification contributes to an adjustment of water molecules between the layers of the vermiculite at a high temperature and a high pressure, thus improving the water content. The temperature for the hydrothermal modification is preferably 101-450°C, and a duration of the hydrothermal modification is preferably 0.5-72 hours.

[020] In the present disclosure, in order to increase the contact area between the water and the raw ore of vermiculite, the method may further include: before the hydrothermal modification, pulverizing the raw ore of vermiculite to obtain vermiculite particles, wherein a particle size of the vermiculite particles is 1-120 mesh, and the pulverization may be carried out by shearing or grinding, etc.

[021] In the present disclosure, in order to regulate cations between the layers of the vermiculite, the method may further include: performing hydrothermal modification on the raw ore of vermiculite, the water and an inorganic salt altogether, wherein a weight ratio of the raw ore of vermiculite to the inorganic salt is 1: (0.01-10), and a solid/liquid volume ratio is 1:1-10. The inorganic salt may be one or more of sodium chloride, potassium bromide, potassium chloride, potassium nitrate, magnesium chloride, ferric chloride, aluminium chloride or ammonium chloride. In addition, the inorganic salt can be vaporized or decomposed at a high temperature to improve the gas pressure in reaction kettle, thereby improving expansion efficiency and expansion uniformity.

[022] Further, in order to improve the expansion rate, the method may further include: performing hydrothermal modification on the raw ore of vermiculite, the water and an organic cationic surfactant altogether, wherein a weight ratio of the raw ore of vermiculite to the organic cationic surfactant is 1: (0.01-5). The organic cationic surfactant may be cetyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, cetylpyridinium bromide or tetramethylammonium bromide.

[023] In the present disclosure, the hydrothermal modification may be carried out by means of microwave, infrared ray, heating by an oven or a high temperature furnace.

[024] Below, the present disclosure is further described in connection with embodiments which, however, do not limit the present disclosure in any way.

[025] The expansion rate of the vermiculite can be determined by measuring the volumes of the vermiculite before and after the expansion.

[026] Embodiment 1 [027] 2 grams of raw ore of vermiculite and 10 grams of water are placed into a 20 mL hydrothermal reaction kettle, and then a hydrothermal modification at a high temperature and a high pressure is performed for 24 hours at 180°C under magnetic stirring at 50rpm. After the hydrothermal modification, expanded vermiculite is obtained by expanding under a microwave of 1500W after filtration, and the expansion rate of the expanded vermiculite is 800%.

[028] Comparison example 1 [029] Without performing a hydrothermal treatment, the raw ore of vermiculite is directly expanded under a microwave of 1500W to obtain the expanded vermiculite. In this way, the expansion rate of the expanded vermiculite is 600%.

[030] Embodiment 2 [031] 2 grams of raw ore of vermiculite, 3.5 grams of potassium nitrate and 8 grams of water are placed into a 20mL hydrothermal reaction kettle, and then a hydrothermal modification at a high temperature and high pressure is performed for 24 hours at 180°C under magnetic stirring at 80rpm. After the hydrothermal modification, expanded vermiculite is obtained by expanding at 850°C after filtration, and the expansion 10 rate of the expanded vermiculite is 1920%.

[032] Comparison example 2 [033] The raw ore of vermiculite is expanded at 850°C to obtain expanded vermiculite, and the expansion rate of the expanded vermiculite is 700%.

[034] While the present disclosure has been described above in detail with 15 general description and specific embodiments, it is obvious that some modifications or improvements can be made to the present disclosure by those skilled in the art. Therefore, all these modifications or improvements made without departing from the spirit of the present disclosure will fall within the scope of protection of the present disclosure.

Claims

Conclusions:

A method for improving the expansion property of vermiculite, comprising the following steps:

placing crude vermiculation ore and water or saline in a high-pressure resistant vessel, with a magnetic stirrer placed in the high-pressure resistant vessel, magnetic stirring at the bottom of the high-pressure resistant vessel being provided, and a heating device outside the vessel is provided with high pressure resistance;

heating the raw ore for hydrothermal modification;

removing the solution by filtration after the hydrothermal change; and performing an expansion to obtain expanded vermiculite, wherein the expansion is carried out by means of microwaves, ultrasonic waves or by heating.

A method according to claim 1, wherein a weight ratio of the raw vermiculation ore on the water or water solution is 1: (0.1 - 100), a stirring speed of 1 1000 revolutions per minute, a microwave power of 100 - 1800 W, and a speed of rotation of magnetic stirring is 1 to 500 revolutions per minute.

3.. Method according to claim 1, wherein a temperature for the hydrothermal change,

101 - 450 ° C, and a duration of the hydrothermal change is 0.5 - 72 hours.

The method of claim 1, comprising an additional step:

before the hydrothermal modification, pulverize the crude vermiculite ore to obtain vermiculite particles whose particle size of the vermiculite particles is 1 120 mesh.

The method of claim 1, comprising an additional step: performing a hydrothermal change on the whole of crude vermiculite ore, of the water and of an inorganic salt, wherein a weight ratio of the crude vermiculite ore to the inorganic salt 1: (0.01 - 10); and a solid / liquid volume ratio is 1: 1-10.

The method of claim 5, wherein the inorganic salt is one or more salts belonging to the group of sodium chloride, potassium bromide, potassium chloride, potassium nitrate, magnesium chloride, iron III chloride, aluminum chloride and ammonium chloride.

The method of claim 1, comprising the additional step:

performing a hydrothermal change on the whole of the raw vermiculite ore, of the water and of an organic cationic surfactant, wherein a weight ratio of the raw vermiculite ore to the organic cationic surfactant 1: (0.01-5) amounts.

The method of claim 7, wherein the organic cationic surfactant belongs to the group of cetyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, cetyl pyridinium bromide, and tetramethylammonium bromide.

The method of claim 1, wherein the hydrothermal modification is carried out by means of microwaves, infrared rays, heating by means of an oven or a high-temperature oven.