CN108483450B

CN108483450B - Preparation method of biomass white carbon black raw material rice hull ash

Info

Publication number: CN108483450B
Application number: CN201810242645.4A
Authority: CN
Inventors: 孙志刚; 吴宇; 姜博; 袁振海; 鹿宇飞; 杜鹏举; 况冲
Original assignee: Yihai Jiamusi Bio Cogeneration Co Ltd
Current assignee: Yihai Jiamusi Bio Cogeneration Co Ltd
Priority date: 2018-03-22
Filing date: 2018-03-22
Publication date: 2020-01-07
Anticipated expiration: 2038-03-22
Also published as: CN108483450A

Abstract

The invention relates to a preparation method of biomass white carbon black raw material rice hull ash, belonging to the technical field of chemical materials. The invention provides a preparation method of rice hull ash, which comprises the step of burning rice hulls to obtain the rice hull ash, wherein the rice hull burning is carried out under the controlled volume ratio of aerobic wind to anoxic wind. By controlling one or more parameters and process conditions in the invention, the content of organic impurities in the rice hull ash can be obviously reduced under the condition of the same other process parameters, the application performance of the white carbon black from the rice hull is improved, and the performance of the white carbon black can be comparable to that of the white carbon black from the ore sand. When the white carbon black of the invention is used as a reinforcing filler for preparing rubber, the mechanical properties of rubber products, such as tensile strength, can be obviously improved.

Description

Preparation method of biomass white carbon black raw material rice hull ash

Technical Field

The invention relates to a preparation method of biomass white carbon black raw material rice hull ash, belonging to the technical field of chemical materials.

Background

White carbon black is amorphous hydrated silicon dioxide, the research of which originates from Germany, and the white carbon black is prepared by taking silica sand as a raw material and adopting a precipitation method. The white carbon black has the characteristics of large specific surface area, porosity, high temperature resistance, strong electrical insulation, good reinforcing effect, no combustion and the like, so when the white carbon black is used for replacing carbon black to reinforce rubber products, the same reinforcing effect as the carbon black can be obtained. And is also called "white carbon" because its appearance is white. White carbon black is a very important chemical product because of its various properties such as strong repair property, dispersibility and the like, and is now widely used in various fields such as latex, rubber, plastics, paints, cosmetics, medicines, pesticides and foods.

The prior art methods for preparing silica include heat treatment (such as gas phase method) and precipitation (also called liquid phase method). Among them, the precipitation method is a method having a wide application range at present, and it has been reported that the white carbon black is prepared by using non-metallic ore, industrial by-products, agricultural by-products (such as rice hull ash) and the like as raw materials. In the research on the precipitation method, the precipitation method may be classified into a strong acid precipitation method and CO method according to the kind of the acidifying agent₂Precipitation, organic acid precipitation and alkaline activator precipitation. Compared with a heat treatment method, the precipitation method has the advantages of simple equipment, low cost and the like, and white carbon black products with different performances and meeting different requirements can be obtained by adding different surfactants. However, the precipitation process in the prior art generally has the disadvantages of complex process, low product purity, long preparation period and the like. Various attempts have been made to solve these problems. For example, chinese patent application 201410020643.2 attempts to remove metal impurities from rice hull ash raw materials and intermediate products by a washing operation with an aqueous solution of a chelating agent to increase the dissolution rate of silica in rice hull ash, thereby improving the whiteness and purity of white carbon black. In addition, the chinese patent application 201380045728.X also discloses a preparation method of white carbon black, wherein polycarboxylic acid such as methylglutaric acid is added in a post-treatment stage, i.e. a pulping and washing stage of white carbon black, so as to improve the application performance of white carbon black. However, the above method mainly improves the performance of the white carbon black by using a high-cost auxiliary agent, and increases the complexity of the process. Moreover, such additives may cause secondary pollution to the white carbon black product, introducing new impurities. For this reason, there is still a need for further development of a method for effectively improving the above-mentioned disadvantages and more suitable for mass production of rice hull ash, improving the properties of rice hull ash, and using it for preparing white carbon and improving the properties of downstream products of white carbon, such as rubber.

Disclosure of Invention

In order to solve the above technical problems, the present invention provides a method for preparing rice hull ash, comprising the steps of mixing rice hull ashCombusting the hulls in the presence of aerobic and anoxic wind to obtain rice hull ash, wherein the rice hulls are combusted in a unit time at a controlled ratio of the volume of the aerobic wind to the volume of the anoxic wind, and/or wherein the rice hulls are blown in at a controlled amount of anoxic wind (m)³) Burning at a ratio to the mass (t) of the rice hulls.

According to the invention, wherein the controlled volume ratio of aerobic wind to anoxic wind per unit time is an adjustment of the volume ratio of aerobic wind to anoxic wind, for example such that the volume ratio of aerobic wind to anoxic wind is greater than 5.1: 1, such as above 5.5: 1, such as 6:1 to 10: 1 or 6:1 to 8: 1.

According to the invention, the controlled blast volume (m) of the anoxic wind³) Ratio to the mass (t) of rice husk, e.g. the amount of oxygen-deficient air blown in per unit time (m)³) The ratio of the mass (t) of the rice husk to the mass (t) of the rice husk is more than 600:1, for example 600:1 to 1000:1, such as 650:1 to 900: 1.

According to the invention, the gas introduced into the boiler per unit time can be divided into two types: primary air and secondary air; wherein the primary air includes air for blowing fuel (such as rice hull) and oxygen-deficient air, and the secondary air may include preheated hot air.

Preferably, the aerobic air includes air for blowing fuel in the primary air introduced into the boiler per unit time and secondary air introduced into the boiler per unit time.

According to the invention, the temperature of the anoxic air can be 100-200 ℃; for example, the anoxic air undergoes purification and heat exchange processes before being blown into the boiler;

preferably, the oxygen content in the aerobic wind may be above 10 vol-%, such as above 15 vol-%, e.g. from about 20 vol-% to about 25 vol-%, examples of which may be air;

preferably, the oxygen content of the anoxic gas is lower than that of the aerobic gas, for example less than 10% by volume, such as less than 5% by volume, such as 3-5% by volume, examples of which may be fuels, such as tail gas from the combustion of rice hulls;

preferably, the aerobic wind and the anoxic wind are simultaneously blown into the boiler through different passages, thereby being mixed in the boiler.

As an example, the rice hulls may be conveyed to a boiler combustion zone for combustion by positive pressure.

According to an embodiment of the present invention, the rice hull ash may be prepared by:

b1) putting the rice hulls into a boiler combustion area for combustion to obtain a rice hull ash primary material;

b2) screening the rice hull ash primary material obtained in the step b1), and removing impurities to obtain the rice hull ash.

According to the present invention, the hulls are normally fed into the boiler combustion zone in a thrown position. After entering the combustion zone of the boiler, the rice hulls are gradually dried, cracked and gasified along with the rise of the temperature. The rice husk after burning can fall into on the pivoted grate zone in furnace bottom gradually under the action of gravity, and the temperature descends gradually. The rice hulls in the grate area are further decomposed, carbonized, gasified and the like at relatively high temperature, and are finally converted into rice hull ash after heat is released.

According to embodiments of the present invention, the temperature of the combustion zone (i.e., the furnace or furnace zone) of the boiler may be, for example, 600-. The retention time of the rice hull in the hearth can be 10-60min, such as 10-30min, such as 15-20 min.

According to an embodiment of the present invention, the hulls are blown into the boiler combustion zone by a blower together with aerobic air. Preferably, an aerobic blast can be used to agitate and/or agitate the hulls and provide an aerobic environment for combustion to promote combustion thereof.

By way of example, by blowing anoxic air from another path into the boiler combustion zone, in addition to blowing and/or agitating the hulls, full utilization of the tail gas may be achieved.

According to the method for preparing rice hull ash of the present invention, the rice hull ash obtained by burning rice hulls may be further sieved to remove impurities such as brown rice, pebbles, etc. For example, the sieving may be performed by a 1-Smm (e.g., 2mm) linear sieve.

Preferably, the screened rice hull ash can also pass through a separator under the condition of negative pressure conveying, and organic impurities with different specific gravities, such as part of rice grains and the like, are separated through inertia.

The temperature of the grate zone may be typically 400-500 c according to embodiments of the present invention. As an example, the grate may be in the form of a chain track and move the rice hulls and/or rice hull ash falling onto the grate at a rate to exit the boiler.

The invention also provides the rice hull ash obtained by the preparation method. Preferably, the carbon content of the rice hull ash product may be about 10-40 wt%, for example about 15-30 wt%, such as about 15-25 wt%.

According to an embodiment of the present invention, there is also provided a method for preparing white carbon black, in particular white carbon black for rubber reinforcement, comprising the steps of:

f1) providing a substrate comprising said compound containing formula M₂O·nSiO₂Aqueous solutions of the indicated silicates in SiO₂The expressed concentration is 65-85g/L, preferably 70-80g/L, and further preferably 74-78 g/L;

f2) adding an aqueous sulfuric acid solution, controlling the flow rate of the acid so that the turbidity is 15 to 100FAU for 20 to 26 minutes, preferably 25 to 60FAU for 22 to 25 minutes, and maintaining the flow rate of the aqueous sulfuric acid solution at pH 7.0 to 9.0, preferably 7.5 to 8.5, and more preferably 7.8 to 8.2;

f3) acidification to pH 4-5.5, preferably 4.2-5, further preferably 4.5-4.9, gives slurry F1.

Preferably, in the step f1, the temperature of the substrate is 70-90 ℃, preferably 73-89 ℃, and further preferably 75-87 ℃;

preferably, in the step f1, the base material contains 2-20g/L of sodium sulfate, preferably 4.4-18.5g/L of sodium sulfate;

preferably, in the step f1, the base material contains sodium sulfate aqueous solution;

preferably, in the step f1, the mass percentage concentration of the sodium sulfate aqueous solution is 3-5%;

alternatively, the aqueous sodium sulfate solution may be derived from a solution recovered for reuse;

preferably, in step f1, the base material contains alkali metal ion, such as Na⁺The ion concentration is 0.8 to 1.5mol/L, preferably 0.9 to 1.2mol/L, and more preferably1-1.3mol/L；

Preferably, in step f2, the temperature is raised to 90-98, preferably 93-96 ℃ when the turbidity reaches 3500FAU, for example 3800FAU or 4000 FAU;

preferably, in the step f2, the temperature rising speed is 0.5-1.5 ℃/min;

preferably, the step f2 further comprises adding sodium silicate and the aqueous solution of sulfuric acid after the temperature raising operation reaches the temperature;

preferably, in the step f2, the molar ratio of the sulfuric acid to the sodium silicate is controlled to be 1.04-1.07, preferably 1.05-1.06;

preferably, in the step f2, the time for simultaneously adding the sodium silicate and the sulfuric acid aqueous solution is 10-30min, preferably 15-25 min;

preferably, in step f2, the sodium silicate contains the compound of formula M₂O·nSiO₂An aqueous solution of said silicate, or an aqueous solution of said silicate containing formula M₂O·nSiO₂The aqueous solution composition of the silicate;

preferably, the rice hull ash obtained by the method of the present invention is subjected to alkali dissolution to obtain the fertilizer containing formula M₂O·nSiO₂An aqueous solution of the silicate;

preferably, in step f3, the acid used for acidification is sulfuric acid or its aqueous solution;

preferably, in the step f3, the flow rate of the aqueous solution of sulfuric acid is controlled to make the reaction system reach the pH within 3-10min, preferably 4-8min, and further preferably 5-7 min;

preferably, the mass percentage concentration of the sulfuric acid is 5-10%;

preferably, said step f3 further comprises a curing step;

preferably, the curing time is 5-15min, more preferably 7-13min, and even more preferably 8-12 min;

preferably, the preparation method further comprises the steps of filtering, washing and drying the slurry;

preferably, the filter cake is liquefied by a colloid mill before the drying step to obtain a slurry F2;

preferably, the pH of the slurry F2 is adjusted to 5 to 7, preferably 5.5 to 6.5, further preferably 5.8 to 6.2 before the drying step;

preferably, the drying is spray drying.

According to the invention, the specific gravity of the dilute sulfuric acid may be 1.010-1.100, for example 1.030-1.070.

The invention also provides the white carbon black prepared from the rice hull ash.

Advantageous effects

Without being bound by any theory, the inventors believe that the rice hulls are mainly subjected to aerobic oxidative decomposition in the combustion zone; while the grate zone is primarily subjected to oxygen-free cracking. Because the oxygen content is sufficient in the combustion zone, organic matters such as cellulose, starch, protein and the like can be quickly converted into substances such as carbon dioxide and the like through oxidation reaction and are discharged along with the smoke; in the combustion area, the rice hulls cannot be completely and fully combusted, and when the rice hulls which are not fully combusted enter the fire grate area, due to insufficient oxygen content and high temperature, pyrolysis reaction mainly occurs, and macromolecules are converted into small molecules which are dissipated to the combustion area for further combustion and heat release. The pyrolysis reaction in the grate area often leads to insufficient combustion, so that the rice hulls keep a certain physical structure, the cellulose is carbonized into active carbon, and the silicon dioxide still keeps an amorphous state, thereby being beneficial to the subsequent alkali treatment process.

The invention discovers that the rice hulls not only carbonize in the grate area, but also form small molecular organic impurities. Further, by controlling the volume ratio of the oxygen-rich wind/the anoxic wind, or controlling the blowing amount (m) of the anoxic wind per unit time³) The ratio of the mass (t) of the white carbon black to the mass (t) of the rice hulls can influence the formation of organic impurities in the rice hull ash, and further influence the application performance of the white carbon black derived from the rice hull ash and the mechanical performance of rubber. Surprisingly, by controlling one or more parameters and process conditions in the invention within the range of the invention, the application performance of the white carbon black derived from rice hulls can be improved, and the performance can be compared with that of white carbon black derived from ore sand. When the white carbon black of the invention is used as a reinforcing filler for preparing rubber, the mechanical properties of rubber products, such as tensile strength, can be obviously improved.

Detailed Description

The above and other features and advantages of the present invention will be explained and illustrated in more detail hereinafter with reference to the description of embodiments of the invention. It should be understood that the following examples are intended to illustrate the technical solutions of the present invention, and are not intended to limit the scope of the present invention defined by the claims and their equivalents in any way.

Unless otherwise indicated, the materials and reagents herein are either commercially available or can be prepared by one skilled in the art according to the prior art.

Instruments and reagents

Rice hull: yihai (Jia Musi) grain and oil industry Co., Ltd provides, wherein the content of oversize material (weight%) of the rice hull is 2.1; protein content (% by weight) 2.22%; starch content (% by weight) 1.17; the winnowing oversize/total organic impurities (protein content + starch content) was 0.9.

Caustic soda, concentration 32%, manufacturer: heilongjiang Haohua chemical Co., Ltd;

sulfuric acid, concentration 93%, manufacturer: jilinlong Yuan Qi chemical industry, Inc.;

the model of the filter press is as follows: XAZG224/1250-UK, manufacturer: jianhua group Filter Co., Ltd;

the type of the drying tower: VG6500, manufacturer: tin-free sperper drier plant.

Examples 1-6 preparation of Rice Hull Ash

1) Preparing rice hull ash: respectively conveying the rice hulls of the same batch to a hearth of a boiler at positive pressure according to the flow rate of table 1 for combustion, controlling the flow rates of aerobic air (air) and anoxic air (tail gas after the rice hulls are combusted, the oxygen content is 4 volume percent) at the bottom of the boiler according to the parameters of table 1 for combustion, wherein the aerobic air and the anoxic air are simultaneously blown into the boiler through different channels, the combustion temperature of the hearth is 800 ℃, the retention time of the rice hulls in the hearth is adjusted and controlled to be 15 minutes by regulating the rotating speed of a grate, other operations are carried out in a known mode, and rice hull ash discharged from the tail part of the grate is collected as a raw.

2) Removing impurities from rice hull ash: removing impurities from the raw material rice hull ash prepared in the step 1) through a 2mm linear sieve and an inertial separator, and collecting 1-6 obtained rice hull ash samples for later use.

Examples 7-12 preparation of white carbon

1) Preparing sodium silicate: 2000g of each of the rice hull ash samples 1 to 6 obtained in examples 1 to 6, 904.3g of sodium hydroxide and 9940g of water are respectively weighed, then the materials are added into a high-pressure reaction kettle for reaction and temperature rise, when the pressure rises to 3kg, timing is started, the reaction time is 4h, cooling and pressure relief are carried out after the reaction is finished, reaction slurry is filtered by a filter press and washed by warm water at 60 ℃, washing liquid is taken in the washing process for detecting the specific gravity, when the specific gravity of the washing liquid is 1.030, the washing is finished, and the collected filtering liquid is dense paulite and the washing liquid is weak paulite.

2) Mixing the concentrated sodium silicate and the diluted sodium silicate obtained in the step 1) to obtain a sodium silicate raw material with the specific gravity of 1.140 for later use.

3)

The initial stage is as follows:

introducing, in a reactor equipped with a stirrer and a steam heating device:

5700g of sodium silicate mother liquor (modulus 2.6), 2335g of sodium sulfate aqueous solution (Na)₂SO₄3.8 percent) and 398g of soft water as a base material, wherein the base material is SiO₂The measured concentration is 76g/L, Na⁺The concentration was 1.09mol/L and the mixture was heated to a temperature of 79 ℃.

Acidification stage

Starting an acid pump, adding dilute sulfuric acid (with the specific gravity of 1.050) into a reactor at the flow rate of 92.4g/min, detecting the pH once in 5 minutes in an acidification stage, detecting the turbidity of a reaction system, enabling the turbidity of the reaction system to reach 60FAU in 23 minutes, keeping the flow rate until the pH is 8, using 4623g of acid in total in the stage, adding acid for 50 minutes, starting to heat up when the turbidity reaches 4000FAU, heating up to 94 ℃ at the speed of 1 ℃/min, taking 15min to heat up to 15 ℃ in total, and keeping the temperature at 94 ℃ until the final reaction is finished to obtain acidified sodium silicate.

Simultaneous feeding stage

Starting the simultaneous feeding process, adding the sodium silicate mother liquor (modulus 2.6) at the flow rate of 68.8g/min, carrying out pH detection on the dilute sulfuric acid at the flow rate of 64g/min and the molar ratio of the sulfuric acid to the sodium silicate of 1.055, and adjusting the acid flow rate to keep the pH of the slurry stable at 8 +/-0.05. The total adding amount of the sodium silicate and the acid in the stage is 3984 g.

Post-treatment stage

The stage is a pH reduction stage, and dilute sulfuric acid is introduced to reduce the pH value to 4.5.

After curing for ten minutes, the reaction slurry was filtered using a plate filter press and washed with soft water to obtain a white carbon black filter cake (water content 81%), the filter cake was changed from solid to liquid slurry using a colloid mill, and the slurry pH was adjusted to 6. And drying by using a spray drying tower to produce the finished white carbon black products of the examples 1 to 6.

Example 13 rubber Property testing

The mixing method is banburying by an internal mixer, and specifically refers to the Chinese patent application CN201210423251.1 example 1, and is carried out according to the formula in the following table 2.

TABLE 2

Components	Parts by weight
		Solution polymerized styrene-butadiene	144
Cis-polybutadiene rubber	36
		Zinc oxide	4.8
Stearic acid	3.6
		White carbon samples 1-6	100.8
Si-69 (bis- [ gamma- (triethoxysilyl) propyl)]Tetrasulfide)	4.8
		CBS (N-cyclohexyl-2-benzothiazole sulfenamide)	2.88
DPG (diphenylguanidine)	2.7
		4020(N- (1, 3-dimethyl) butyl-N' -phenyl-p-phenylenediamine)	3.6
DTPD (N, N' -xylyl-p-phenylenediamine (mixture))	1.35
		Sulfur	2.7
Total of	308.43

Banburying process:

mixing in the first stage: the rotor speed of an internal mixer is 45rpm, the ram pressure is 0.6MPa, firstly, the solution polymerized styrene-butadiene rubber and the butadiene rubber are put into an internal mixing chamber of the internal mixer and mixed for 30s, then, the white carbon black and the silane coupling agent (silicon-69) are put into the internal mixing chamber and continuously mixed for 100 s, the temperature of the rubber material reaches 120 ℃, the ram is lifted for 5 s, the rotor speed is adjusted to be 30rpm, the ram is mixed for 90 s, the temperature of the rubber material is 150 ℃, the rubber is discharged, a section of rubber compound is obtained, and the section of rubber compound is cooled to the room temperature in the air.

And (3) second-stage mixing: the rotor speed of an internal mixer is 45rpm, the ram pressure is 0.6MPa, the first-stage rubber compound is put into a mixing chamber of the internal mixer, zinc oxide, stearic acid and anti-aging agents (4020 and DTPD) are added, the ram is mixed for 110 seconds, the temperature of rubber materials reaches 130 ℃, the ram is lifted for 5 seconds, the rotor speed is adjusted to be 30rpm, the ram is mixed for 90 seconds, the temperature of the rubber materials is 150 ℃, rubber is discharged, the second-stage rubber compound is obtained, and the second-stage rubber compound is cooled to room temperature in the air.

And (3) third-stage mixing: and (2) putting the two-stage rubber compound, the accelerator (CBS and DPG) and sulfur into a mixing chamber of the internal mixer at the rotor speed of 35rpm and the ram pressure of 0.6MPa, mixing for 60 seconds, lifting the ram for 10 seconds, mixing for 50 seconds by the ram, and discharging rubber at the rubber material temperature of 85 ℃ to obtain the vulcanized rubber.

Physical and mechanical properties:

and (3) testing conditions are as follows: the physical and mechanical properties of the vulcanizates were measured according to the corresponding ASTM standards using an XLL-250 Universal materials tester (LLOYD instruments, UK), and the results are summarized in Table 3.

TABLE 3

Rice husk ash sample	White carbon black sample	Tensile strength of rubber
			Example 1	White carbon sample 1	17.6
Example 2	White carbon sample 2	18.8
			Example 3	White carbon sample 3	17.8
Example 4	White carbon sample 4	16.2
			Example 5	White carbon sample 5	14.3
Example 6	White carbon sample 6	15.6

From the above table, it can be seen that the high-dispersion and high-structure white carbon black product prepared by controlling the parameters in the rice hull combustion process within the range of the present invention can make rubber have higher tensile strength, and has the same application performance as the white carbon black product prepared by using quartz sand as the raw material. Therefore, the rice hull ash prepared by the preparation method of the invention and the white carbon black product further prepared by the rice hull ash can enable rubber to have excellent tensile strength, and even can have the same or similar application performance with the white carbon black prepared by taking quartz sand as a raw material.

It should be understood that the scope of the present invention is not limited to the above embodiments. Those skilled in the art can change or modify the above examples and embodiments according to the disclosure of the present invention to achieve the object of the present invention. Such changes and modifications are intended to be included within the scope of the present invention as defined by the appended claims.

Claims

1. A method for preparing rice hull ash comprises burning rice hull to obtain rice hull ash, wherein the rice hull is burned in the presence of aerobic wind and anoxic windBurning rice hulls in a controlled ratio of aerobic to anoxic wind volume per unit time, and/or controlled blast volume (m) of anoxic wind³) Burning at a ratio to the mass (t) of the rice hulls;

the controlled ratio of the volume of the aerobic wind to the volume of the anoxic wind means that the ratio of the volume of the aerobic wind to the volume of the anoxic wind is more than 6:1 and not more than 8:1 in unit time; the controlled blast volume (m) of the anoxic wind³) The ratio of the mass (t) of the husk to the mass (t) of the husk means the amount (m) of the oxygen-deficient air blown in per unit time³) The mass ratio of the rice husk to the rice husk (t) is 600:1-1000: 1;

the aerobic air comprises air which is introduced into the boiler in unit time and is used for blowing fuel and hot air which is introduced into the boiler in unit time and is subjected to preheating treatment;

the oxygen content of the anoxic wind is lower than that of the aerobic wind.

2. The method according to claim 1, wherein the amount of the oxygen-deficient wind blown per unit time (m) is³) The mass ratio of the rice husk to the rice husk (t) is 650:1-900: 1.

3. The method of claim 1, wherein the anoxic wind has an oxygen content of less than 10 vol.%.

4. The method of claim 1, wherein the anoxic wind has an oxygen content of less than or equal to 5 vol.%.

5. The method of claim 1, wherein the anoxic wind has an oxygen content of 3-5 vol.%.

6. The method of claim 1 wherein said anoxic zone is an offgas from the combustion of rice hulls.

7. The method as claimed in claim 1, wherein the temperature of the anoxic wind is 100-200 ℃.

8. The method of claim 1, wherein the anoxic air is subjected to a purification and heat exchange process before being blown into the boiler.

9. The method according to claim 1, wherein the oxygen content in the aerobic wind is 10 vol% or more.

10. The method according to claim 1, wherein the oxygen content in the aerobic wind is 15 vol% or more.

11. The method of claim 1, wherein the oxygen content of the aerobic wind is 20% to 25% by volume.

12. The method of claim 1, wherein the aerobic wind is air.

13. The method of claim 1, wherein the aerobic wind and the anoxic wind are simultaneously blown into the boiler through different channels.

14. The production method according to any one of claims 1 to 13, wherein the rice husk ash is produced by a method comprising:

15. The method as claimed in claim 14, wherein the temperature of the combustion zone of the boiler is 600-900 ℃; the retention time of the rice hull in the hearth is 10-60 min.

16. The method as claimed in claim 14, wherein the temperature of the combustion zone of the boiler is 600-800 ℃; the retention time of the rice hull in the hearth is 10-30 min.

17. The method as claimed in claim 14, wherein the temperature of the combustion zone of the boiler is 600-700 ℃; the retention time of the rice hulls in the hearth is 15-20 min.

18. A process according to claim 1 wherein the rice hull ash from the combustion of the rice hulls is further sieved.

19. The method of claim 18, wherein the sieving is performed by a 1-5mm linear sieve.

20. The method of claim 18, wherein the sieving is performed by a 2mm linear sieve.

21. The method of claim 18, wherein the screened rice hull ash is subjected to inertial separation under negative pressure conveying conditions to separate organic impurities having different specific gravities.

22. A production method as claimed in any one of claims 1 to 21, wherein the obtained rice husk ash product has a carbon content of 10 to 15% by weight.