Method for preparing amorphous silicon dioxide by using baked diatomite
阅读说明：本技术 一种利用焙烧硅藻土制备非晶二氧化硅的方法 (Method for preparing amorphous silicon dioxide by using baked diatomite ) 是由 任子杰 刘宇航 安琴友 高惠民 唐腾望 于 2021-03-08 设计创作，主要内容包括：一种利用焙烧硅藻土制备非晶二氧化硅的方法,该方法包括以下步骤：S1、将焙烧硅藻土、镁粉、氯化钠均匀混合；S2、将均匀混合后的焙烧硅藻土、镁粉、氯化钠压制成片状样品；S3、先将片状样品置于管式马弗炉内,再将管式马弗炉封闭并检查其气密性,并通入惰性气体氩气以排尽管式马弗炉内空气,然后将管式马弗炉升温后保温,焙烧完成后,冷却至室温得到焙烧硅藻土样品；S4、先用盐酸去除焙烧硅藻土样品中未发生发应的镁粉,再用清水将酸洗后的焙烧硅藻土样品清洗至中性,然后烘干并粉碎得到非晶二氧化硅。本设计不仅操作简单、效率高,而且再生效果好。(A method for preparing amorphous silicon dioxide by using calcined diatomite comprises the following steps: s1, uniformly mixing the roasted diatomite, the magnesium powder and the sodium chloride; s2, pressing the uniformly mixed calcined diatomite, magnesium powder and sodium chloride into a sheet sample; s3, firstly, placing the sheet sample in a tubular muffle furnace, then sealing the tubular muffle furnace, checking the air tightness of the tubular muffle furnace, introducing inert gas argon to exhaust the air in the tubular muffle furnace, then heating the tubular muffle furnace, preserving the heat, and cooling to room temperature after roasting is completed to obtain a roasted diatomite sample; and S4, removing the magnesium powder which does not react in the roasted diatomite sample by hydrochloric acid, cleaning the roasted diatomite sample after acid washing to be neutral by clear water, and then drying and crushing to obtain the amorphous silicon dioxide. The design is simple to operate, high in efficiency and good in regeneration effect.)
1. A method for preparing amorphous silicon dioxide by using calcined diatomite is characterized by comprising the following steps:
s1, uniformly mixing the roasted diatomite, the magnesium powder and the sodium chloride;
s2, pressing the uniformly mixed calcined diatomite, magnesium powder and sodium chloride into a sheet sample;
s3, roasting the flaky sample to obtain a roasted diatomite sample;
and S4, removing the magnesium powder which does not react in the roasted diatomite sample by hydrochloric acid, cleaning the roasted diatomite sample after acid washing to be neutral by clear water, and then drying and crushing to obtain the amorphous silicon dioxide.
2. The method for preparing amorphous silicon dioxide using calcined diatomite as claimed in claim 1, wherein: in step S1, the calcined diatomite is calcined diatomite powder.
3. The method for preparing amorphous silicon dioxide using calcined diatomite as claimed in claim 1, wherein: in step S1, the magnesium powder is analytically pure, and the mass ratio of the magnesium powder to the baked diatomite is 0.8: 1-1: 1.
4. The method for preparing amorphous silicon dioxide using calcined diatomite as claimed in claim 1, wherein: in step S1, the sodium chloride is analytically pure, and the mass ratio of the sodium chloride to the baked diatomite is 3: 1-10: 1.
5. The method for preparing amorphous silicon dioxide using calcined diatomite as claimed in claim 1, wherein: in step S2, the uniformly mixed calcined diatomaceous earth, magnesium powder, and sodium chloride are placed in a mold and pressed into a sheet sample by a tablet press, the pressure of which is 0.5Mpa to 5 Mpa.
6. The method for preparing amorphous silicon dioxide using calcined diatomite as claimed in claim 1, wherein:
in step S3, placing the sheet sample in a tubular muffle furnace, heating the tubular muffle furnace, preserving heat, and cooling to room temperature after roasting to obtain a roasted diatomite sample;
the temperature rise rate of the tubular muffle furnace is 5-8 ℃/min, and the temperature of the tubular muffle furnace is raised to 500-650 ℃ and then is kept.
7. The method of claim 6, wherein the method comprises: in step S3, before the temperature is raised, the tubular muffle is closed and the airtightness is checked, and an inert gas argon is introduced to exhaust the air in the tubular muffle.
8. The method of claim 6, wherein the method comprises: in step S3, the heat preservation time is 2-3 h.
9. The method for preparing amorphous silicon dioxide using calcined diatomite as claimed in claim 1, wherein: in step S4, the mass fraction of hydrochloric acid is 5% to 10%.
10. The method for preparing amorphous silicon dioxide using calcined diatomite as claimed in claim 1, wherein: in step S4, the amorphous silicon dioxide is obtained by pulverizing to a particle size of less than 74 microns.
Technical Field
The invention belongs to the field of deep processing of nonmetallic mineral materials, and particularly relates to a method for preparing amorphous silicon dioxide by using roasted diatomite.
Background
Diatomite is a biogenic siliceous sedimentary rock, and comprises silicon dioxide as a main chemical component, and a small amount of aluminum oxide, ferric oxide and organic impurities. The surface silanol group of the silicon dioxide and the active silane bond can form hydrogen bonds with different strengths, and the silicon dioxide has the excellent characteristics of high purity, low density, high specific surface area, good dispersibility and the like, and also has good optical performance and mechanical performance. Therefore, the catalyst can be widely applied to products in various industries, such as catalyst carriers, polymer composites, electronic packaging materials, precision ceramic materials, rubber, paper, plastics, glass fiber reinforced plastics, adhesives, high-grade fillers, sealants, coatings, optical fibers, precision casting and the like.
Roasting is an economical and effective process for processing the diatomite and is also the most effective and simplest method for removing organic matters. Although the diatomite can remove impurities after being roasted, the silicon dioxide of the diatomite is converted from an amorphous state into a crystalline state after being roasted. The inhalation of crystalline silicon dioxide can cause silicosis and even cause cancer, so the diatomite filter aid containing a large amount of crystalline silicon dioxide can cause harm to the health of production personnel, transportation personnel and using personnel, and how to reduce the content of inhalable crystalline silicon dioxide in diatomite has become the key point of research of domestic and foreign scholars.
At present, researches for reducing the content of inhalable crystal silicon dioxide focus on reducing the conversion rate of the crystal silicon dioxide, and the reduction of the conversion rate can be considered from the aspects of not adding sodium salt fluxing agent, even not adding any fluxing agent, reducing the heating quantity and the like, and specifically the following are considered:
(1) flash roasting
In the process of preparing the filter aid by roasting and modifying the diatomite, in order to obtain proper permeability, high temperature of 900-1200 ℃ for agglomeration of fine particles is necessary; therefore, the researchers have proposed the idea of flash roasting, in which diatomite is kept at a high temperature ranging from 850 ℃ to 1250 ℃ for only a few tens of milliseconds to a few seconds and then is rapidly placed in an environment below 850 ℃, so that the surface of the diatomite can obtain enough heat for fusing and agglomerating the surface, and at the same time, the heat is not enough for the silica to generate crystal transformation, and a product with the content of crystal silica lower than 1% can be obtained (U.S. Pat. No. 5,5179062); the permeability range of the filter aid obtained by the method is 0.06 darcy-0.4 darcy, but the method is not reported to be related to large-scale and economic application.
(2) Addition of non-sodium fluxing agent
Bo Wang in the patent (US 2010/0126388A 1) mentions that sodium salt has a promoting effect on the conversion of crystal-form quartz, probably because sodium ions destroy a silicon dioxide network structure, the radius size of the sodium ions is suitable for entering the silicon dioxide structure, so that salts of potassium ions, rubidium ions and cesium ions with larger ionic radius are selected as a fluxing agent, the content of the crystal-form quartz in a roasting material is increased along with the increase of the addition amount of the fluxing agent, and under the condition that the addition amount is 4%, the content of the crystal-form quartz in the roasting material is respectively 23.2%, 1.6%, 0.6% and <0.1% by adding sodium carbonate, potassium carbonate, rubidium carbonate and cesium carbonate fluxing agents; roland Meyer PITTROFF also mentions in its patent (German patent DE10235866B 4) that potassium ion is an inhibitor of the formation of crystalline silica; however, the use of a potassium salt, rubidium salt or cesium salt as a flux in place of the sodium salt does not provide a filter aid having a high permeability.
(3) Adding adhesive and low-temperature roasting
The Pascal DUFOUR in the other two patents (U.S. Pat. No. 5,5710090, German patent DE4440931A 1) discloses a preparation method of a diatomite filter aid capable of controlling the conversion rate and permeability of crystal-form quartz, wherein in order to control the conversion of the crystal-form quartz, the heating temperature of diatomite is lower than 850 ℃, and simultaneously, an adhesive is added to bond diatom, so that higher permeability is obtained; the adhesive is preferably an inorganic adhesive, and since the organic adhesive needs to be added after the calcination, which causes the blocking of partial holes to reduce the permeability and increase the tap density, the alkali metal silicate or the silicic acid is selected as the adhesive, and the aqueous solution thereof is added by spraying before the calcination or kneaded with the diatomite at a high speed, and the drying and the low-temperature calcination are performed; products with different permeabilities, tap densities and crystal form quartz conversion rates are obtained by controlling the roasting temperature and the addition amount of the adhesive; similar to the above method, the method disclosed in the patent of Wangbo (Chinese patent CN 102257121A) uses a binder metal aluminate, such as sodium aluminate, potassium aluminate, calcium aluminate, magnesium aluminate, etc.
(4) Roasting of coarse particles
Peter e. Lenz et al in US patent (US patent 8084392B 2) mention a method that can strictly control the content of crystalline silica below 1% and can obtain any permeability value; crushing and grading diatomite raw ore to 100-1400 mu m, roasting at 900-980 ℃ for 10-60 min, properly crushing the obtained roasted product, and grading to obtain various products with required particle size, wherein the permeability is 0.1-20 darcy and even can reach 30 darcy; the material with the particle size of-100 mu m obtained by raw ore classification can be used for producing common filter aid without special requirements on quartz content and permeability;
the method mentioned in Bruce c. Olmsted (US 4325844) also achieves similar effect to Peter e.lenz (US 8084392B 2) by pelletizing diatomaceous earth and then calcining, i.e. large-particle diatoms are not completely burnt at high temperature, only surface melting is carried out, structural strength and permeability are ensured, and meanwhile, the conversion rate of crystal forms is not too high.
The above methods are all to improve the roasting process to reduce the crystal form conversion rate of the diatomite, but all will affect the roasting effect, so that the roasting efficiency cannot be exerted to the maximum.
Disclosure of Invention
The invention aims to overcome the defects and problems of complicated operation and low efficiency in the prior art, and provides a method for preparing amorphous silicon dioxide by using roasted diatomite, which has simple operation, high efficiency and good regeneration effect.
In order to achieve the above purpose, the technical solution of the invention is as follows: a method for preparing amorphous silicon dioxide by using calcined diatomite comprises the following steps:
s1, uniformly mixing the roasted diatomite, the magnesium powder and the sodium chloride;
s2, pressing the uniformly mixed calcined diatomite, magnesium powder and sodium chloride into a sheet sample;
s3, roasting the flaky sample to obtain a roasted diatomite sample;
and S4, removing the magnesium powder which does not react in the roasted diatomite sample by hydrochloric acid, cleaning the roasted diatomite sample after acid washing to be neutral by clear water, and then drying and crushing to obtain the amorphous silicon dioxide.
In step S1, the calcined diatomite is calcined diatomite powder.
In step S1, the magnesium powder is analytically pure, and the mass ratio of the magnesium powder to the baked diatomite is 0.8: 1-1: 1.
In step S1, the sodium chloride is analytically pure, and the mass ratio of the sodium chloride to the baked diatomite is 3: 1-10: 1.
In step S2, the uniformly mixed calcined diatomaceous earth, magnesium powder, and sodium chloride are placed in a mold and pressed into a sheet sample by a tablet press, the pressure of which is 0.5Mpa to 5 Mpa.
In step S3, placing the sheet sample in a tubular muffle furnace, heating the tubular muffle furnace, preserving heat, and cooling to room temperature after roasting to obtain a roasted diatomite sample;
the temperature rise rate of the tubular muffle furnace is 5-8 ℃/min, and the temperature of the tubular muffle furnace is raised to 500-650 ℃ and then is kept.
In step S3, before the temperature is raised, the tubular muffle is closed and the airtightness is checked, and an inert gas argon is introduced to exhaust the air in the tubular muffle.
In step S3, the heat preservation time is 2-3 h.
In step S4, the mass fraction of hydrochloric acid is 5% to 10%.
In step S4, the amorphous silicon dioxide is obtained by pulverizing to a particle size of less than 74 microns.
Compared with the prior art, the invention has the beneficial effects that:
the invention relates to a method for preparing amorphous silicon dioxide by using roasted diatomite, which is characterized in that the roasted diatomite is used as a raw material, magnesium powder and sodium chloride are added, the roasted diatomite is roasted again in a high-temperature furnace by adopting a magnesiothermic reduction method, and the roasted diatomite is reduced into an amorphous silicon dioxide form, so that the high-purity amorphous silicon dioxide is prepared. Therefore, the invention has simple operation, high efficiency and good regeneration effect.
Drawings
FIG. 1 is a flow chart of a method for preparing amorphous silicon dioxide using calcined diatomaceous earth according to the present invention.
FIG. 2 is an X-ray diffraction pattern of calcined diatomaceous earth.
FIG. 3 is an X-ray diffraction chart of amorphous silica in example 1 of the present invention.
FIG. 4 is an X-ray diffraction chart of amorphous silicon dioxide in example 2 of the present invention.
FIG. 5 is an X-ray diffraction chart of amorphous silicon dioxide in example 3 of the present invention.
FIG. 6 is an X-ray diffraction chart of amorphous silicon dioxide in example 4 of the present invention.
FIG. 7 is an X-ray diffraction pattern of the reaction of the calcined diatomaceous earth and magnesium powder in comparative example 1 of the present invention.
FIG. 8 is an X-ray diffraction pattern after the reaction of the calcined diatomaceous earth in comparative example 2 of the present invention.
FIG. 9 is an X-ray diffraction pattern after the reaction of the calcined diatomaceous earth in comparative example 3 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following description and embodiments in conjunction with the accompanying drawings.
Referring to fig. 1, a method for preparing amorphous silicon dioxide using calcined diatomite includes the steps of:
s1, uniformly mixing the roasted diatomite, the magnesium powder and the sodium chloride;
s2, pressing the uniformly mixed calcined diatomite, magnesium powder and sodium chloride into a sheet sample;
s3, roasting the flaky sample to obtain a roasted diatomite sample;
and S4, removing the magnesium powder which does not react in the roasted diatomite sample by hydrochloric acid, cleaning the roasted diatomite sample after acid washing to be neutral by clear water, and then drying and crushing to obtain the amorphous silicon dioxide.
In step S1, the calcined diatomite is calcined diatomite powder.
In step S1, the magnesium powder is analytically pure, and the mass ratio of the magnesium powder to the baked diatomite is 0.8: 1-1: 1.
In step S1, the sodium chloride is analytically pure, and the mass ratio of the sodium chloride to the baked diatomite is 3: 1-10: 1.
In step S2, the uniformly mixed calcined diatomaceous earth, magnesium powder, and sodium chloride are placed in a mold and pressed into a sheet sample by a tablet press, the pressure of which is 0.5Mpa to 5 Mpa.
In step S3, placing the sheet sample in a tubular muffle furnace, heating the tubular muffle furnace, preserving heat, and cooling to room temperature after roasting to obtain a roasted diatomite sample;
the temperature rise rate of the tubular muffle furnace is 5-8 ℃/min, and the temperature of the tubular muffle furnace is raised to 500-650 ℃ and then is kept.
In step S3, before the temperature is raised, the tubular muffle is closed and the airtightness is checked, and an inert gas argon is introduced to exhaust the air in the tubular muffle.
In step S3, the heat preservation time is 2-3 h.
In step S4, the mass fraction of hydrochloric acid is 5% to 10%.
In step S4, the amorphous silicon dioxide is obtained by pulverizing to a particle size of less than 74 microns.
The principle of the invention is illustrated as follows:
according to the design, roasted diatomite is used as a raw material, the roasted diatomite, a reducing agent (magnesium powder) and salts (sodium chloride) are uniformly mixed and then placed in a high-temperature furnace, inert gas is introduced before roasting to exhaust air in the furnace to ensure that the reaction is carried out under the inert atmosphere, the reducing agent and the salts are used for coaction roasting, after the high-temperature furnace is kept warm for a period of time, a sample is taken out, the sample is pickled to remove the excessive reducing agent, washed for 2-3 times by clear water to be neutral, dried and ground into powder to obtain amorphous silicon dioxide; the method can convert the crystal silicon dioxide of the roasted diatomite into amorphous silicon dioxide, and has simple process and low processing cost.
Example 1:
referring to fig. 1, a method for preparing amorphous silicon dioxide using calcined diatomite includes the steps of:
s1, uniformly mixing 1g of calcined diatomite (calcined diatomite powder from Jilin company), 1g of magnesium powder (analytically pure) and 3g of sodium chloride (analytically pure);
s2, placing the uniformly mixed roasted diatomite, magnesium powder and sodium chloride into a die, adjusting the pressure of a tablet press to 0.5Mpa, and pressing into a sheet sample by the tablet press;
s3, firstly placing the sheet sample in a tubular muffle furnace, then sealing the tubular muffle furnace and checking the air tightness of the tubular muffle furnace, introducing inert gas argon for 15min to exhaust the air in the tubular muffle furnace, then heating the tubular muffle furnace at a heating rate of 5-8 ℃/min to 500-650 ℃, keeping the temperature for 2-3 h, and cooling to room temperature after roasting to obtain a roasted diatomite sample;
s4, removing unreacted magnesium powder in the roasted diatomite sample by using hydrochloric acid with the mass fraction of 5% -10%, filtering, cleaning the roasted diatomite sample after acid washing to be neutral by using clear water, drying and crushing to obtain amorphous silicon dioxide with the granularity of less than 74 microns.
The amorphous silicon dioxide was sampled and subjected to X-ray diffraction analysis, and the results are shown in FIG. 3.
Example 2:
referring to fig. 1, a method for preparing amorphous silicon dioxide using calcined diatomite includes the steps of:
s1, uniformly mixing 1g of calcined diatomite (calcined diatomite powder from Jilin company), 1g of magnesium powder (analytically pure) and 5g of sodium chloride (analytically pure);
s2, placing the uniformly mixed roasted diatomite, magnesium powder and sodium chloride into a die, adjusting the pressure of a tablet press to 1Mpa, and pressing into a sheet sample through the tablet press;
s3, firstly placing the sheet sample in a tubular muffle furnace, then sealing the tubular muffle furnace and checking the air tightness of the tubular muffle furnace, introducing inert gas argon for 15min to exhaust the air in the tubular muffle furnace, then heating the tubular muffle furnace at a heating rate of 5-8 ℃/min to 500-650 ℃, keeping the temperature for 2-3 h, and cooling to room temperature after roasting to obtain a roasted diatomite sample;
s4, removing unreacted magnesium powder in the roasted diatomite sample by using hydrochloric acid with the mass fraction of 5% -10%, filtering, cleaning the roasted diatomite sample after acid washing to be neutral by using clear water, drying and crushing to obtain amorphous silicon dioxide with the granularity of less than 74 microns.
The amorphous silicon dioxide was sampled and subjected to X-ray diffraction analysis, and the results are shown in FIG. 4.
Example 3:
referring to fig. 1, a method for preparing amorphous silicon dioxide using calcined diatomite includes the steps of:
s1, uniformly mixing 1g of calcined diatomite (calcined diatomite powder from Jilin company), 1g of magnesium powder (analytically pure) and 8g of sodium chloride (analytically pure);
s2, placing the uniformly mixed roasted diatomite, magnesium powder and sodium chloride into a die, adjusting the pressure of a tablet press to 2Mpa, and pressing into a sheet sample through the tablet press;
s3, firstly placing the sheet sample in a tubular muffle furnace, then sealing the tubular muffle furnace and checking the air tightness of the tubular muffle furnace, introducing inert gas argon for 15min to exhaust the air in the tubular muffle furnace, then heating the tubular muffle furnace at a heating rate of 5-8 ℃/min to 500-650 ℃, keeping the temperature for 2-3 h, and cooling to room temperature after roasting to obtain a roasted diatomite sample;
s4, removing unreacted magnesium powder in the roasted diatomite sample by using hydrochloric acid with the mass fraction of 5% -10%, filtering, cleaning the roasted diatomite sample after acid washing to be neutral by using clear water, drying and crushing to obtain amorphous silicon dioxide with the granularity of less than 74 microns.
The amorphous silicon dioxide was sampled and subjected to X-ray diffraction analysis, and the results are shown in FIG. 5.
Example 4:
referring to fig. 1, a method for preparing amorphous silicon dioxide using calcined diatomite includes the steps of:
s1, uniformly mixing 1g of calcined diatomite (calcined diatomite powder from Jilin company), 1g of magnesium powder (analytically pure) and 10g of sodium chloride (analytically pure);
s2, placing the uniformly mixed roasted diatomite, magnesium powder and sodium chloride into a die, adjusting the pressure of a tablet press to 3Mpa, and pressing into a sheet sample through the tablet press;
s3, firstly placing the sheet sample in a tubular muffle furnace, then sealing the tubular muffle furnace and checking the air tightness of the tubular muffle furnace, introducing inert gas argon for 15min to exhaust the air in the tubular muffle furnace, then heating the tubular muffle furnace at a heating rate of 5-8 ℃/min to 500-650 ℃, keeping the temperature for 2-3 h, and cooling to room temperature after roasting to obtain a roasted diatomite sample;
s4, removing unreacted magnesium powder in the roasted diatomite sample by using hydrochloric acid with the mass fraction of 5% -10%, filtering, cleaning the roasted diatomite sample after acid washing to be neutral by using clear water, drying and crushing to obtain amorphous silicon dioxide with the granularity of less than 74 microns.
The amorphous silicon dioxide was sampled and subjected to X-ray diffraction analysis, and the results are shown in FIG. 6.
Example 5:
referring to fig. 1, a method for preparing amorphous silicon dioxide using calcined diatomite includes the steps of:
s1, uniformly mixing 1g of calcined diatomite (calcined diatomite powder from Jilin corporation), 0.8g of magnesium powder (analytically pure) and 3g of sodium chloride (analytically pure);
s2, placing the uniformly mixed roasted diatomite, magnesium powder and sodium chloride into a die, adjusting the pressure of a tablet press to 0.5Mpa, and pressing into a sheet sample by the tablet press;
s3, firstly placing the sheet sample in a tubular muffle furnace, then sealing the tubular muffle furnace and checking the air tightness of the tubular muffle furnace, introducing inert gas argon for 15min to exhaust the air in the tubular muffle furnace, then heating the tubular muffle furnace at a heating rate of 5-8 ℃/min to 500-650 ℃, keeping the temperature for 2-3 h, and cooling to room temperature after roasting to obtain a roasted diatomite sample;
s4, removing unreacted magnesium powder in the roasted diatomite sample by using hydrochloric acid with the mass fraction of 5% -10%, filtering, cleaning the roasted diatomite sample after acid washing to be neutral by using clear water, drying and crushing to obtain amorphous silicon dioxide with the granularity of less than 74 microns.
Example 6:
referring to fig. 1, a method for preparing amorphous silicon dioxide using calcined diatomite includes the steps of:
s1, uniformly mixing 1g of calcined diatomite (calcined diatomite powder from Jilin corporation), 0.9g of magnesium powder (analytically pure) and 3g of sodium chloride (analytically pure);
s2, placing the uniformly mixed roasted diatomite, magnesium powder and sodium chloride into a die, adjusting the pressure of a tablet press to 0.5Mpa, and pressing into a sheet sample by the tablet press;
s3, firstly placing the sheet sample in a tubular muffle furnace, then sealing the tubular muffle furnace and checking the air tightness of the tubular muffle furnace, introducing inert gas argon for 15min to exhaust the air in the tubular muffle furnace, then heating the tubular muffle furnace at a heating rate of 5-8 ℃/min to 500-650 ℃, keeping the temperature for 2-3 h, and cooling to room temperature after roasting to obtain a roasted diatomite sample;
s4, removing unreacted magnesium powder in the roasted diatomite sample by using hydrochloric acid with the mass fraction of 5% -10%, filtering, cleaning the roasted diatomite sample after acid washing to be neutral by using clear water, drying and crushing to obtain amorphous silicon dioxide with the granularity of less than 74 microns.
Comparative example 1:
a method for preparing amorphous silicon dioxide by using calcined diatomite comprises the following steps:
s1, uniformly mixing 1g of calcined diatomite (calcined diatomite powder from Jilin company) and 1g of magnesium powder (analytically pure);
s2, placing the uniformly mixed roasted diatomite and magnesium powder into a die, adjusting the pressure of a tablet press to 0.5Mpa, and pressing the mixture into a sheet sample through the tablet press;
s3, firstly placing the sheet sample in a tubular muffle furnace, then sealing the tubular muffle furnace and checking the air tightness of the tubular muffle furnace, introducing inert gas argon for 15min to exhaust the air in the tubular muffle furnace, then heating the tubular muffle furnace at a heating rate of 5-8 ℃/min to 500-650 ℃, keeping the temperature for 2-3 h, and cooling to room temperature after roasting to obtain a roasted diatomite sample;
and S4, removing unreacted magnesium powder in the roasted diatomite sample by using hydrochloric acid with the mass fraction of 5-10%, filtering, cleaning the roasted diatomite sample after acid washing to be neutral by using clear water, drying and crushing to obtain the product with the particle size of less than 74 microns.
The experimental product was sampled for X-ray diffraction analysis and the results are shown in fig. 7.
Comparative example 2:
referring to fig. 1, a method for preparing amorphous silicon dioxide using calcined diatomite includes the steps of:
s1, uniformly mixing 1g of calcined diatomite (calcined diatomite powder from Jilin company), 1g of magnesium powder (analytically pure) and 1g of sodium chloride (analytically pure);
s2, placing the uniformly mixed roasted diatomite, magnesium powder and sodium chloride into a die, adjusting the pressure of a tablet press to 0.5Mpa, and pressing into a sheet sample by the tablet press;
s3, firstly placing the sheet sample in a tubular muffle furnace, then sealing the tubular muffle furnace and checking the air tightness of the tubular muffle furnace, introducing inert gas argon for 15min to exhaust the air in the tubular muffle furnace, then heating the tubular muffle furnace at a heating rate of 5-8 ℃/min to 500-650 ℃, keeping the temperature for 2-3 h, and cooling to room temperature after roasting to obtain a roasted diatomite sample;
and S4, removing unreacted magnesium powder in the roasted diatomite sample by using hydrochloric acid with the mass fraction of 5-10%, filtering, cleaning the roasted diatomite sample after acid washing to be neutral by using clear water, drying and crushing to obtain the product with the particle size of less than 74 microns.
The experimental product was sampled and analyzed by X-ray diffraction, and the results are shown in fig. 8.
Comparative example 3:
referring to fig. 1, a method for preparing amorphous silicon dioxide using calcined diatomite includes the steps of:
s1, uniformly mixing 1g of calcined diatomite (calcined diatomite powder from Jilin company), 1g of magnesium powder (analytically pure) and 2g of sodium chloride (analytically pure);
s2, placing the uniformly mixed roasted diatomite, magnesium powder and sodium chloride into a die, adjusting the pressure of a tablet press to 0.5Mpa, and pressing into a sheet sample by the tablet press;
s3, firstly placing the sheet sample in a tubular muffle furnace, then sealing the tubular muffle furnace and checking the air tightness of the tubular muffle furnace, introducing inert gas argon for 15min to exhaust the air in the tubular muffle furnace, then heating the tubular muffle furnace at a heating rate of 5-8 ℃/min to 500-650 ℃, keeping the temperature for 2-3 h, and cooling to room temperature after roasting to obtain a roasted diatomite sample;
and S4, removing unreacted magnesium powder in the roasted diatomite sample by using hydrochloric acid with the mass fraction of 5-10%, filtering, cleaning the roasted diatomite sample after acid washing to be neutral by using clear water, drying and crushing to obtain the product with the particle size of less than 74 microns.
The experimental product was sampled and analyzed by X-ray diffraction, and the results are shown in fig. 9.
As can be seen from the observation of FIG. 2, the calcined diatomite has better crystallization degree, the peak of quartz is more obvious and no other impurity peak appears; when the magnesium powder and the roasted diatomite are uniformly mixed and sodium chloride is not added, as can be seen from fig. 7, the chemical reaction generated at this time is a magnesiothermic reduction reaction, silicon dioxide in the diatomite is reduced into a silicon simple substance, although a dispersed steamed bread peak appears between 20 and 30 degrees, the peak of silicon is more obvious, when sodium chloride is added under the conditions that the mass ratio of the roasted diatomite to the sodium chloride is 1:1 and 1:2, and the reaction is generated, as can be seen from the X-ray diffraction patterns of fig. 8 and 9, the reaction result is more similar to the shape of the X-ray diffraction pattern presented in fig. 7 when the sodium chloride is not added, namely the peak of silicon is more sharp; when sodium chloride is added under the condition that the mass ratio of the roasted diatomite to the sodium chloride is 1: 3-1: 10, and the three are uniformly mixed, no obvious sharp peak appears and a dispersed steamed bun peak appears between 20 and 30 degrees can be observed from figures 3 to 6, which proves that the product is amorphous silicon dioxide and has better purity.