CN109231228B - High-expansion-rate expanded vermiculite based on low-hydration phlogopite intercalation and preparation method thereof - Google Patents

Abstract

The invention discloses a high-expansion-rate expanded vermiculite based on a weakly hydrated phlogopite intercalation and a preparation method thereof, and the preparation method comprises the following steps: grinding and stripping, impurity removal and grading are carried out on the raw ore of the low-hydration phlogopite to obtain low-hydration phlogopite fine pieces; adding the raw materials of the composite intercalator into an acid-resistant reaction vessel according to the proportion, and uniformly mixing to obtain a composite intercalator solution; placing the low-hydration phlogopite flakes into an acid-resistant reaction container filled with a composite intercalator to be stirred until the low-hydration phlogopite flakes uniformly absorb the composite intercalator without residual solution, standing and aging to ensure that the intercalator is fully inserted into the interlamination region of the vermiculite crystal layer and part of the phlogopite crystal layer to obtain the composite intercalated low-hydration phlogopite flakes; and heating the obtained compound intercalated weakly hydrated phlogopite flakes to obtain the high-expansion-rate expanded vermiculite product. The method is green and environment-friendly, and the prepared expanded vermiculite has high expansion rate and low density, and is beneficial to further development and utilization of the weakly hydrated phlogopite.

Description

A kind of high expansion rate expanded vermiculite based on weakly hydrated phlogopite intercalation and preparation method thereof

technical field

The invention belongs to the technical field of inorganic non-metallic functional materials and mineral functional materials, and in particular relates to a high expansion rate expanded vermiculite based on weakly hydrated phlogopite intercalation and a preparation method thereof.

Background technique

Phlogopite is a trioctahedral layered silicate mineral. It can be hydrated and eroded into vermiculite under the action of hydrothermal fluid or surface water. Vermiculite has good heating expansion, when heated rapidly, its volume will rapidly expand dozens of times to form expanded vermiculite. Expanded vermiculite is widely used in construction, agriculture, forestry, environmental protection, gardening and chemical industry due to its low density, large specific surface area, stable chemical properties, thermal insulation, sound absorption and sound insulation and good fire resistance. Industrial vermiculite includes vermiculite and hydrated phlogopite (or hydrated biotite) whose expansion ratio meets industrial requirements. Phlogopite has no heating and rapid expansion performance, and weakly hydrated phlogopite is usually difficult to be used as an industrial vermiculite raw material for the production of expanded vermiculite due to its low expansion rate.

At present, the field of industrial vermiculite processing and production of expanded vermiculite generally has shortcomings such as low expansion rate, insufficient layering, low strength and high brittleness. The preparation of vermiculite has been difficult to break through the limit of 40 times the collective expansion rate without destroying the properties of its structural layer, which greatly limits the application field of expanded vermiculite products.

Existing preparation methods of expanded vermiculite mainly include direct heating expansion method, chemical auxiliary heating expansion method and ultrasonic heating expansion method. The chemical additives used in the chemically assisted heating expansion method include potassium nitrate, potassium chloride, magnesium nitrate, magnesium chloride, hydrogen peroxide, oxalic acid, etc., and the heating methods include roasting method, microwave method and burning method. Qian Yupeng et al. in "Preparation of Expanded Vermiculite with High Expansion Ratio by Composite Method" (Silicate Bulletin, 2017, 36(9):2875-2879) used chemical-assisted heating expansion method to prepare expanded vermiculite for vermiculite samples. Hydrogen peroxide with a concentration of 25% and a solid-to-liquid ratio of 1:4 is soaked in vermiculite and roasted at 300°C. The method has large loss of hydrogen peroxide and high production cost. The patented vermiculite expansion process (application number: 00101332.7, application date: 2000-01-06, publication number: 1302778A, publication date: 2001-07-11) adds 2% to 10% of vegetable oil, potassium nitrate, etc. Soaking treatment, soaking time is 12h ~ 24h, and then heating to 300 ~ 400 ℃, so as to obtain expanded vermiculite products, the maximum expansion ratio of the product is 14 times, there are still vermiculite expansion effect is poor, the expansion ratio is low, etc. shortcoming. Patent a kind of vermiculite modified expansion preparation method (application number: CN201610907607.7, application date: 20161018, publication number: CN106431046A, publication date: 20170222) Put vermiculite into a certain concentration of chemical reagents (potassium nitrate or potassium chloride) , magnesium nitrate or magnesium chloride, hydrogen peroxide, oxalic acid, etc.) for 4 to 24 hours, and heated at 90 to 550 ° C for 3 to 10 minutes to obtain an expanded vermiculite product. The expansion effect of the vermiculite treated by this method is too poor, and the expansion ratio is only 3 to 6 times.

The patented flexible expansion vermiculite microwave continuous expansion method and special equipment (application number: CN201010244821.1, application date: 20100804, publication number: CN101893377A, publication date: 20101124) announced the use of continuous microwave expansion equipment for continuous microwave expansion of vermiculite ore. , the vermiculite expansion temperature does not exceed 300 ℃. Although the preparation method consumes less energy, the produced expanded vermiculite is not easy to be pulverized, and has high strength, but the expansion ratio is only 20-30 times, which is not ideal for the treatment of poor-quality vermiculite ore and requires special equipment. Patent a method for preparing expanded vermiculite by ultrasonic pretreatment (application number: CN201110053693.7, application date: 20110307, publication number: CN102167531A, publication date: 20110831) The vermiculite ore is screened and impurity removed, and then soaked The soaked vermiculite was pretreated by ultrasonic wave for 10-60min in the concentration of 5%-30% hydrogen peroxide for 1-14h, and then placed in a microwave device for microwave expansion treatment for 0.5-4min after standing for 1-2h. Expanded vermiculite, the minimum bulk density of the produced expanded vermiculite is 46kg/m ³ , and the maximum expansion ratio still does not reach 40 times.

The specific steps of the patented vermiculite expansion production process (application number: CN201710813535.4, application date: 20170911, publication number: CN107500590A, publication date: 20171222) include coarse screening, lifting feed, drying preheating, high temperature expansion, Winning, screening, feeding bins and bagging. Among them, the preheating temperature is about 500 °C, and the heating temperature of the high-temperature expansion furnace is about 1000 °C. The expansion ratio of the prepared expanded vermiculite product is still low, only 7 to 8 times, and it needs to be heated twice, which consumes a lot of energy. , the process is complicated.

To sum up, in order to improve the expansion rate of vermiculite, chemical additives are often selected to pre-modify vermiculite ore, and then heat-treated by roasting or microwave to obtain expanded vermiculite. However, the current production process generally has low expansion rate, large energy consumption, high water consumption, toxic and harmful chemical additives used, and the waste water and waste gas produced are difficult to handle. The disadvantages of low strength and unsatisfactory expansion effect on vermiculite with poor quality limit the utilization rate of vermiculite resources and the application range of expanded vermiculite, while the weakly hydrated phlogopite which is often discarded in the process of industrial vermiculite mining has not been developed. Technologies and methods to achieve high expansion rate processing.

SUMMARY OF THE INVENTION

In view of this, the present invention is aimed at the existing processes and technologies in the above-mentioned vermiculite expansion process that the expansion ratio is small, the layered structure layer is destroyed, the strength is low and the brittleness is large, or the production process energy consumption is large, water consumption is high, The chemical additives used are toxic and harmful, the waste water produced is difficult to handle, and the expansion effect of poor-quality industrial vermiculite is not ideal or the weakly hydrated phlogopite is difficult to use. High-expansion rate expanded vermiculite layer and a preparation method thereof, by using a compound intercalating agent to perform compound intercalation treatment on the weakly hydrated phlogopite, and then heating the weakly hydrated phlogopite after the composite intercalation to obtain a high expansion rate Expanded Vermiculite.

In order to solve the above-mentioned technical problems, the present invention discloses a preparation method of high expansion rate expanded vermiculite based on weakly hydrated phlogopite intercalation,

Include the following steps:

1) take weakly hydrated phlogopite ore and carry out grinding and peeling, impurity removal and classification to obtain weakly hydrated phlogopite fine flakes;

2) mixing the oxidizing agent with industrial water to prepare an oxidizing agent solution, and adding the reducing organic acid to the acid-resistant reaction vessel and mixing to obtain a composite intercalating agent;

3) Pour the weakly hydrated phlogopite fine flakes obtained in step 1) into the acid-resistant reaction vessel equipped with the composite intercalating agent in step 2) and stir, until the weakly hydrated phlogopite fine flakes evenly absorb the composite intercalating agent. The remaining solution is left to stand for aging, so that the intercalating agent is fully inserted into the interlayer domain of the vermiculite crystal layer and part of the phlogopite crystal layer to obtain a composite intercalated weakly hydrated phlogopite fine piece;

4) heating the composite intercalated weakly hydrated phlogopite flakes obtained in step 3) to obtain a high expansion rate expanded vermiculite product.

Optionally, the weakly hydrated phlogopite flakes described in step 1) have a sheet diameter of 3-10 mm.

Optionally, the oxidant in step 2) is one of hydrogen peroxide or calcium peroxide; the reducing organic acid is one of malic acid, gluconic acid or citric acid.

Optionally, the concentration of the oxidant solution in step 2) is 5-30 wt%; the volume-to-mass ratio (L/Kg) of the oxidant solution and the reducing organic acid is 15:1-240:1.

Optionally, the mass volume ratio of the weakly hydrated phlogopite flakes and the composite intercalating agent in the acid-resistant reactor described in step 3) is 1:1.2～1:2.4 (Kg/L), and the described In the process of standing and aging, the temperature is 10～30℃, and the time is 5h～24h.

Optionally, the heating treatment in step 4) is microwave heating treatment or electric heating treatment.

Optionally, the heating temperature of the heating treatment in step 4) is 200-750° C., and the heating time is 1-5 min.

The invention also discloses a high expansion rate expanded vermiculite obtained by the above preparation method.

Optionally, the high expansion rate expanded vermiculite has an aggregate expansion rate of 40 to 80 times and a density of 15 to 30 kg/m ³ .

Compared with the prior art, the present invention can obtain the following technical effects:

1) After intercalation pretreatment of weakly hydrated phlogopite, expanded vermiculite with high expansion rate is obtained, which effectively utilizes low-value resources and processes high-performance and high-value-added materials;

2) The composite intercalating agent and related technical parameters are used, which reduces the consumption of water and chemical additives and reduces the production cost;

3) The process of stirring and standing still promotes the insertion of the composite intercalant into the interlayer domain of the vermiculite crystal layer and part of the phlogopite crystal layer, effectively increasing the water absorption of the interlayer domain, and expanding the interlayer domain and the crystal. The material basis is laid for the high gas pressure generation required for layer peeling;

4) There is no waste liquid and toxic and harmful gas discharge in the process, avoiding the cost of waste liquid and waste gas treatment, and it is a green processing technology;

5) The expanded vermiculite prepared by this technology has a maximum aggregate expansion rate of up to 80 times, thin sheets, large specific surface area and no damage to the structural layer after expansion, higher mechanical strength, and a minimum density as low as 15kg/m ³ , while The maximum aggregate expansion ratio of the expanded vermiculite material prepared according to the technology in the existing literature and patents does not exceed 37.8;

6) In this method, the weakly hydrated phlogopite with poor quality is subjected to heat treatment after being intercalated with a composite intercalating agent, and its aggregate expansion rate and density can not only meet the high standard requirements of the expansion rate of high-quality industrial vermiculite, but also will The expansion rate is increased to a higher level, which is of great technical significance for promoting the high expansion rate processing of industrial vermiculite, and at the same time, it can develop low-value weakly hydrated phlogopite, which is also of great significance for the protection and comprehensive utilization of resources;

7) The high expansion rate expanded vermiculite product prepared by the application of the present invention has a uniform delamination effect, and can be prepared into nano-scale flakes after proper treatment, which lays a foundation for expanding the application field of expanded vermiculite.

Of course, any product implementing the present invention does not necessarily need to achieve all the above-mentioned technical effects at the same time.

Description of drawings

The accompanying drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the attached image:

Fig. 1 is the production flow chart of high expansion rate expanded vermiculite of the present invention;

Fig. 2 is the weak hydration phlogopite fine piece sample figure of the present invention;

Fig. 3 is the weak hydration phlogopite fine sheet X-ray diffraction diagram of the present invention;

Fig. 4 is the X-ray diffractogram of high expansion rate expanded vermiculite product of the present invention;

Fig. 5 is the expanded vermiculite product figure of embodiment 1 of the present invention;

Fig. 6 is the product diagram of the single expanded vermiculite of the embodiment of the present invention 1;

Fig. 7 is the expanded vermiculite product figure of embodiment 2 of the present invention;

Fig. 8 is the expanded vermiculite product figure of embodiment 3 of the present invention;

Fig. 9 is the expanded vermiculite product figure of embodiment 4 of the present invention;

Fig. 10 is the product figure of the single expanded vermiculite of embodiment 4 of the present invention;

Fig. 11 is the expanded vermiculite product figure of embodiment 5 of the present invention;

Fig. 12 is the scanning electron microscope picture (300 times) of high expansion rate expanded vermiculite product of the present invention;

Figure 13 is a scanning electron microscope image (50000 times) of the high expansion rate expanded vermiculite product of the present invention.

Detailed ways

The embodiments of the present invention will be described in detail with the following examples, so as to fully understand and implement the implementation process of how to apply technical means to solve technical problems and achieve technical effects of the present invention.

The invention discloses a preparation method of high expansion rate expanded vermiculite based on weakly hydrated phlogopite intercalation.

1) Take the weakly hydrated phlogopite ore for grinding, peeling, impurity removal and grading to obtain weakly hydrated phlogopite fine flakes (see Figure 2) with a diameter of 3-10 mm and a thickness of 0.3-1.2 mm (see Figure 2). Phlogopite flakes are weak to vitreous luster, and some particles are oily luster;

水金云母间层矿物的衍射峰

蛭石的衍射峰

各仅出现了一个最强峰，且强度很弱。筛分粒级分别为3～5mm、5～8mm、8～10mm；破碎设备可选用颚式破碎机、圆锥破碎机、对辊破碎机等；除杂设备可选用风选机、色选机等；筛分设备可选用各类高频振动筛；In the weakly hydrated phlogopite raw material, the relative intensity of the vermiculite crystal layer or the water phlogopite interlayer mineral diffraction peak is not greater than 3/10 of that of phlogopite (see Fig. 3); Diffraction peaks of phlogopite in the ray diffraction pattern

Diffraction peaks of hydrophlogopite interlayer minerals

Diffraction peaks of vermiculite

Only one strongest peak appears in each, and the intensity is very weak. The sieving size is 3~5mm, 5~8mm, 8~10mm; jaw crusher, cone crusher, roller crusher, etc. can be used for crushing equipment; air sorter, color sorter, etc. can be used for impurity removal equipment ; Various types of high-frequency vibrating screens can be selected for screening equipment;

2) Mix the oxidizing agent with industrial water to prepare a 5-30 wt% oxidizing agent solution, and add the reducing organic acid to the acid-resistant reaction vessel in a volume-to-mass ratio of 15:1-240:1 (L/Kg) and mix to obtain composite intercalating agent;

Wherein, the oxidant in the composite intercalating agent is one of hydrogen peroxide or calcium peroxide; the reducing organic acid includes one of malic acid, gluconic acid and citric acid.

3) Pour the weakly hydrated phlogopite flakes obtained in step 1) into an acid-resistant reaction vessel equipped with a composite intercalant in step 2) at a mass volume ratio of 1:1.2～1:2.4 (Kg/L) and stir, Until the weakly hydrated phlogopite flakes absorb the composite intercalating agent evenly and there is no remaining solution, let it stand at 10℃～30℃ for 5h～24h, so that the intercalating agent can be fully inserted into the vermiculite crystal layer and part of the phlogopite mica. In the interlayer domain of the crystal layer, the composite intercalated weakly hydrated phlogopite flakes were obtained;

4) microwave or electric heating treatment is performed on the composite intercalated weakly hydrated phlogopite flakes obtained in step 3), wherein the heating temperature is 200° C. to 750° C., and the heating time is 1 to 5 minutes to obtain high expansion rate expanded vermiculite. product. The heating equipment can choose vertical kiln, rotary kiln, tube kiln or other industrial microwave ovens;

等。图12表明，原相互平行的结构片层膨胀后呈放射状膨大，膨胀后的结构片层表面较为平整，无破裂现象；图13表明，经膨胀剥离后，结构片层层解充分，单层厚度最薄可达20nm左右，疏松多孔，孔洞横截面呈宽度不等的柳叶形，微尺寸宽度在50nm～200nm。The X-ray diffraction pattern of the high expansion rate expanded vermiculite product is shown in Figure 4, and the scanning electron microscope picture is shown in Figure 12 and Figure 13. Figure 4 shows that the X-ray diffraction pattern of the expanded vermiculite product has only phlogopite phase, the diffraction peaks are sharp, and the structure is intact. The main diffraction peaks are:

Wait. Figure 12 shows that the original parallel structure sheets expand radially after expansion, and the surface of the expanded structure sheets is relatively smooth and has no cracking phenomenon; The thinnest can reach about 20nm, loose and porous, the cross-section of the holes is willow-shaped with different widths, and the micro-size width is 50nm-200nm.

Example 1

The specific preparation method of the high expansion rate expanded vermiculite based on weakly hydrated phlogopite intercalation is as follows:

1) Take weakly hydrated phlogopite raw ore for grinding and peeling, removing impurities and grading to obtain weakly hydrated phlogopite fine flakes with a sheet diameter of 3 to 5 mm;

2) hydrogen peroxide is mixed with industrial water to prepare a 15wt% hydrogen peroxide solution, and with malic acid by volume mass ratio 15:1 (L/Kg) is added in the acid-resistant reaction vessel and mixed to obtain a composite intercalating agent ;

3) Pour the weakly hydrated phlogopite flakes obtained in step 1) into the acid-resistant reaction vessel containing the composite intercalating agent in step 2) at a mass-to-volume ratio of 1:2.4 (Kg/L) and stir, until the weakly hydrated The phlogopite flakes uniformly absorb the composite intercalating agent without remaining solution, and then stand for 24 hours at 20 °C, so that the intercalating agent is fully inserted into the interlayer domain of the vermiculite crystal layer and part of the phlogopite crystal layer to obtain a composite intercalating agent. Intercalated weakly hydrated phlogopite flakes;

4) The composite intercalated weakly hydrated phlogopite flakes obtained in step 3) are subjected to electric heating treatment, the heating temperature is 700° C., and the heating time is 3 min to obtain a high expansion rate expanded vermiculite product.

The density is tested according to the technical specification of the national building materials industry standard "Expanded Vermiculite" (JCT441-2009). The aggregate expansion ratio K (K=density of the raw material of weakly hydrated phlogopite/density after expansion of the weakly hydrated phlogopite) is measured by the change in density. The density of the expanded vermiculite was measured to be 16 kg/m ³ , and the aggregate expansion ratio was 75 times. In line with the national building materials standard "expanded vermiculite" (JCT441-2009) medium density requirements. See Figure 5 and Figure 6 for details.

Figure 5 and Figure 6 show that the expanded vermiculite product prepared by the method of Example 1 is in the shape of beige long worms, most of which are in a curved state, loose and porous, and the pore distribution is relatively uniform; the length of the expanded vermiculite after single expansion is about 40mm .

Example 2

1) Take weakly hydrated phlogopite raw ore for grinding and peeling, removing impurities and grading to obtain weakly hydrated phlogopite fine flakes with a sheet diameter of 3 to 5 mm;

2) calcium peroxide is mixed with industrial water to prepare a calcium peroxide solution of 15wt%, and is added to the acid-resistant reaction vessel with malic acid in a volume-to-mass ratio of 15:1 (L/Kg) and mixed to obtain a composite intercalating agent ;

3) Pour the weakly hydrated phlogopite flakes obtained in step 1) into the acid-resistant reaction vessel containing the composite intercalating agent in step 2) at a mass-to-volume ratio of 1:2.4 (Kg/L) and stir, until the weakly hydrated The phlogopite flakes uniformly absorb the composite intercalating agent without remaining solution, and then stand for 24 hours at 20 °C, so that the intercalating agent is fully inserted into the interlayer domain of the vermiculite crystal layer and part of the phlogopite crystal layer to obtain a composite intercalating agent. Intercalated weakly hydrated phlogopite flakes;

4) The composite intercalated weakly hydrated phlogopite flakes obtained in step 3) are subjected to electric heating treatment, the heating temperature is 700° C., and the heating time is 3 min to obtain a high expansion rate expanded vermiculite product.

The performance test is carried out to the expanded vermiculite prepared by the above-mentioned method, and the method is basically the same as that of Example ¹ , and no further description is given here. 53 times. In line with the national building materials standard "expanded vermiculite" (JCT441-2009) medium density requirements. See Figure 7 for details.

Figure 7 shows that the expanded vermiculite product prepared by the method of Example 2 is in the shape of a long golden yellow worm, most of which are in a curved state, loose and porous, and uniform in pore distribution.

Example 3

1) Take weakly hydrated phlogopite raw ore for grinding and peeling, removing impurities and grading to obtain weakly hydrated phlogopite fine flakes with a sheet diameter of 3 to 5 mm;

2) hydrogen peroxide is mixed with industrial water to prepare a 15wt% hydrogen peroxide solution, and is added to the acid-resistant reaction vessel with citric acid in a volume-to-mass ratio of 15:1 (L/Kg) and mixed to obtain a composite intercalating agent ;

3) Pour the weakly hydrated phlogopite flakes obtained in step 1) into the acid-resistant reaction vessel containing the composite intercalating agent in step 2) at a mass-to-volume ratio of 1:2.4 (Kg/L) and stir, until the weakly hydrated The phlogopite flakes uniformly absorb the composite intercalating agent without remaining solution, and then stand for 24 hours at 20 °C, so that the intercalating agent is fully inserted into the interlayer domain of the vermiculite crystal layer and part of the phlogopite crystal layer to obtain a composite intercalating agent. Intercalated weakly hydrated phlogopite flakes;

4) The composite intercalated weakly hydrated phlogopite flakes obtained in step 3) are subjected to electric heating treatment, the heating temperature is 700° C., and the heating time is 3 min to obtain a high expansion rate expanded vermiculite product.

The performance test is carried out to the expanded vermiculite prepared by the above ^- mentioned method. 80 times. In line with the national building materials standard "expanded vermiculite" (JCT441-2009) medium density requirements. See Figure 8 for details.

Figure 8 shows that the expanded vermiculite product prepared by the method of Example 3 is in the shape of golden yellow long worms, most of which are in a curved state, loose and porous, and the pore distribution is relatively uniform.

Example 4

1) Take weakly hydrated phlogopite raw ore for grinding and peeling, impurity removal and classification to obtain weakly hydrated phlogopite fine flakes with a sheet diameter of 5-8 mm;

2) calcium peroxide and industrial water are mixed to prepare the calcium peroxide solution of 15wt%, and join with gluconic acid by volume mass ratio 240:1 (L/Kg) in the acid-resistant reaction vessel and mix to obtain a composite intercalating agent ;

3) Pour the weakly hydrated phlogopite flakes obtained in step 1) into the acid-resistant reaction vessel containing the composite intercalating agent in step 2) at a mass-to-volume ratio of 1:2.4 (Kg/L) and stir, until the weakly hydrated The phlogopite flakes uniformly absorb the composite intercalating agent without remaining solution, and then stand for 5 hours at 20 °C, so that the intercalating agent is fully inserted into the interlayer domain of the vermiculite crystal layer and part of the phlogopite crystal layer to obtain a composite intercalating agent. Intercalated weakly hydrated phlogopite flakes;

4) The composite intercalated weakly hydrated phlogopite flakes obtained in step 3) are subjected to microwave heating treatment, the heating temperature is 200° C., and the heating time is 4 min to obtain a high expansion rate expanded vermiculite product.

The performance test is carried out to the expanded vermiculite prepared by the above ^- mentioned method, and the method is basically the same as that in Example 1, and will not be repeated here. 40 times. In line with the national building materials standard "expanded vermiculite" (JCT441-2009) medium density requirements. See Figure 9 and Figure 10 for details.

Fig. 9 shows that the expanded vermiculite product prepared by the method of Example 4 is in the shape of short yellowish worms, most of which are in a curved state, loose and porous, and the pores are evenly distributed; About 50mm, easily broken into short strips after expansion and curling.

Example 5

1) Take weakly hydrated phlogopite raw ore for grinding and peeling, impurity removal and classification to obtain weakly hydrated phlogopite fine flakes with a sheet diameter of 5-8 mm;

2) hydrogen peroxide is mixed with industrial water to prepare a 15wt% hydrogen peroxide solution, and is added to the acid-resistant reaction vessel with citric acid in a volume-to-mass ratio of 15:1 (L/Kg) and mixed to obtain a composite intercalating agent ;

3) Pour the weakly hydrated phlogopite flakes obtained in step 1) into the acid-resistant reaction vessel containing the composite intercalating agent in step 2) at a mass-to-volume ratio of 1:2.4 (Kg/L) and stir, until the weakly hydrated The phlogopite flakes uniformly absorb the composite intercalating agent without remaining solution, and then stand for 24 hours at 20 °C, so that the intercalating agent is fully inserted into the interlayer domain of the vermiculite crystal layer and part of the phlogopite crystal layer to obtain a composite intercalating agent. Intercalated weakly hydrated phlogopite flakes;

4) The composite intercalated weakly hydrated phlogopite flakes obtained in step 3) are subjected to microwave heating treatment, the heating temperature is 300° C., and the heating time is 3 min to obtain a high expansion rate expanded vermiculite product.

The expanded vermiculite prepared by the above-mentioned method is tested for performance, and the method is basically the same as that in Example 1, and will not be repeated here. The difference is: the density of the expanded vermiculite obtained by measuring is 21kg/m ³ , and the aggregate expansion rate is 21 kg/m . 58 times. In line with the national building materials standard "expanded vermiculite" (JCT441-2009) medium density requirements. See Figure 11 for details.

Figure 11 shows that the expanded vermiculite product prepared by the method of Example 5 is in the shape of yellow-gray short worms, most of which are in a curved state, loose and porous, and the distribution of pores is relatively uniform.

Example 6

1) Take weakly hydrated phlogopite raw ore for grinding, peeling, impurity removal and grading to obtain weakly hydrated phlogopite fine flakes with a sheet diameter of 8 to 10 mm;

2) hydrogen peroxide is mixed with industrial water to prepare a 5wt% hydrogen peroxide solution, and 150:1 (L/Kg) of gluconic acid is added to the acid-resistant reaction vessel and mixed to obtain a composite intercalating agent. ;

3) Pour the weakly hydrated phlogopite flakes obtained in step 1) into the acid-resistant reaction vessel containing the composite intercalating agent in step 2) at a mass-to-volume ratio of 1:1.2 (Kg/L) and stir, until the weakly hydrated The phlogopite fine flakes absorb the composite intercalating agent evenly without remaining solution, and then stand for 15 hours at 10 °C, so that the intercalating agent is fully inserted into the interlayer domain of the vermiculite crystal layer and part of the phlogopite crystal layer, and the composite intercalating agent is obtained. Intercalated weakly hydrated phlogopite flakes;

4) microwave treatment of the composite intercalated weakly hydrated phlogopite flakes obtained in step 3), wherein the heating temperature is 750° C., and the heating time is 1 min, to obtain a high expansion rate expanded vermiculite product.

The performance test of the expanded vermiculite prepared by the above method shows that the density of the expanded vermiculite is 27kg/m ³ and the aggregate expansion rate is 44 times. It complies with the density requirements of the national building materials standard "Expanded Vermiculite" (JCT441-2009), and other characteristics are the same as those in Example 2.

Example 7

1) Take weakly hydrated phlogopite raw ore for grinding, peeling, impurity removal and grading to obtain weakly hydrated phlogopite fine flakes with a sheet diameter of 8 to 10 mm;

2) Calcium peroxide and industrial water are mixed to prepare a 30wt% calcium peroxide solution, and 100:1 (L/Kg) is added to the acid-resistant reaction vessel with citric acid in a volume-to-mass ratio and mixed to obtain a composite intercalating agent ;

3) Pour the weakly hydrated phlogopite flakes obtained in step 1) into the acid-resistant reaction vessel containing the composite intercalating agent in step 2) at a mass-to-volume ratio of 1:1.8 (Kg/L) and stir, until the weakly hydrated The phlogopite flakes uniformly absorb the composite intercalating agent without remaining solution, and then stand at 30 °C for 20 hours, so that the intercalating agent is fully inserted into the interlayer domain of the vermiculite crystal layer and part of the phlogopite crystal layer, and the composite intercalating agent is obtained. Intercalated weakly hydrated phlogopite flakes;

4) The composite intercalated weakly hydrated phlogopite fine sheet obtained in step 3) is subjected to electric heating treatment, wherein the heating temperature is 500° C., and the heating time is 5 min to obtain a high expansion rate expanded vermiculite product.

The performance test of the expanded vermiculite prepared by the above method shows that the density of the expanded vermiculite is 24kg/m ³ and the aggregate expansion rate is 50 times. It complies with the density requirements of the national building materials standard "Expanded Vermiculite" (JCT441-2009), and other characteristics are the same as those in Example 2.

The foregoing specification illustrates and describes several preferred embodiments of the invention, but as previously mentioned, it should be understood that the invention is not limited to the form disclosed herein and should not be construed as an exclusion of other embodiments, but may be used in a variety of other Combinations, modifications and environments are possible within the scope of the inventive concepts described herein, from the above teachings or from skill or knowledge in the relevant fields. However, modifications and changes made by those skilled in the art do not depart from the spirit and scope of the invention, and should all fall within the protection scope of the appended claims of the invention.

Claims (5)

1. A preparation method of high-expansion-rate expanded vermiculite based on weak hydration phlogopite intercalation is characterized by comprising the following steps:

1) grinding and stripping, impurity removal and classification are carried out on the raw ore of the weakly hydrated phlogopite to obtain a weakly hydrated phlogopite fine sheet with the sheet diameter of 3-10 mm and the sheet thickness of 0.3-1.2 mm;

2) mixing an oxidant and industrial water to prepare an oxidant solution with the concentration of 5-30 wt%, and adding the oxidant solution and reductive organic acid into an acid-resistant reaction container to be uniformly mixed to obtain a composite intercalation agent, wherein the oxidant is one of hydrogen peroxide or calcium peroxide; the reducing organic acid is one of malic acid, gluconic acid or citric acid, and the L/Kg (volume to mass ratio) of the oxidant solution to the reducing organic acid is 15: 1-240: 1;

3) pouring the low-hydration phlogopite flakes obtained in the step 1) into an acid-resistant reaction container filled with the composite intercalator in the step 2) for stirring, wherein the mass-to-volume ratio Kg/L of the low-hydration phlogopite flakes to the composite intercalator is 1: 1.2-1: 2.4, standing and aging after the low-hydration phlogopite flakes uniformly absorb the composite intercalator without residual solution, wherein the aging temperature is 10-30 ℃, and the aging time is 5-24 hours, so that the intercalator is fully inserted into the interlamination region of the vermiculite crystal layer and part of the phlogopite crystal layer to obtain the composite intercalated low-hydration phlogopite flakes;

4) and (3) heating the compound intercalation weak hydration phlogopite flakes obtained in the step 3), wherein the heating temperature of the heating treatment is 200-750 ℃, and the heating time is 1-5 min, so that a high-expansion-rate expanded vermiculite product with a phlogopite phase is obtained.

2. The method for preparing the low-hydration phlogopite flakes according to claim 1), wherein the low-hydration phlogopite flakes in the step 1) have a low to glass luster, and the main minerals of the contained phases are phlogopite and contain small amounts of vermiculite and hydrophlogopite.

3. The production method according to claim 1, wherein the heating treatment in step 4) is a microwave heating treatment or an electric heating treatment.

4. A high expansion expanded vermiculite prepared by the method of any one of claims 1 to 3.

5. The high expansion rate expanded vermiculite according to claim 4, wherein the high expansion rate expanded vermiculite has an aggregate expansion rate of 40 to 80 times and a density of 15 to 30kg/m³。

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