Patent Description:
White carbon black is amorphous hydrated silica. Its research originated in Germany. It was initially prepared with silica sand as raw material by precipitation method. Since white carbon black has the characteristics of large specific surface area, porousness, high-temperature resistance, strong electrical insulation, good reinforcement and non-combustion, when it is used to replace carbon black to reinforce rubber products, it can get the same reinforcing effect as carbon black. Because of its white appearance, it is called "white carbon black". White carbon black is a very important chemical product due to its strong reinforcement, dispersibility and other properties. It is now widely used in many fields such as latex, rubber, plastics, coating, cosmetics, medicine, pesticide and food.

The preparation methods of white carbon black in the prior art include heat treatment method (e.g., gas phase method) and precipitation method (also known as liquid phase method). Among others, the precipitation method is a method currently having a relatively wide application range, and non-metallic minerals, industrial by-products, agricultural by-products (e.g., rice hull ash) and the like are respectively reported to be used as the starting materials for the preparation of white carbon black. In the study of the precipitation method, according to the different types of acidifiers, it can be divided into strong acid precipitation method, CO<NUM> precipitation method, organic acid precipitation method and the alkaline activator precipitation method. Compared with the heat treatment method, the precipitation method has the advantages of simple equipment and low cost, and white carbon black products with different properties and meeting different needs can be obtained by adding different surfactants. However, the precipitation method in the prior art usually has disadvantages such as complicated process, low product purity, and long preparation cycle. Moreover, for a long time in the prior art, the agricultural by-product derived, especially the rice hull-derived white carbon black (i.e., prepared with the rice hull ash obtained by burning rice hulls as raw materials) have many defects, e.g., its insufficient application performance, and difficulty in achieving the same or similar properties as the white carbon black derived from other minerals such as quartz sand, so that the application of the rice hull-derived white carbon black is impeded.

To solve these problems, many attempts have been made. For example, <CIT> attempts to remove metal impurities in rice hull ash raw materials and intermediate products through the washing operation with an aqueous solution of a chelating agent to increase the dissolution rate of silica in the rice hull ash, thereby improving the whiteness and the purity of the white carbon black. However, there is still a need to further develop a method for preparing a white carbon black that can effectively improve the above-mentioned shortcomings, reduce the amount of organic reagents as much as possible, or be more suitable for the large-scale production, and provide a white carbon black that is more suitable for improving the rubber properties of the biomass-derived white carbon black than the existing products.

Further, <CIT> discloses a method for immobilization of lipase by a white carbon black carrier. <CIT> discloses a method for preparing activated silica using rice husk ash as raw material.

<CIT> discloses a process for preparing a precipitated silica, in which a silicate is reacted with an acidifying agent, so as to obtain a suspension of precipitated silica, said suspension of precipitated silica is tillered, so as to obtain a filter cake, said filter cake is subjected to a liquefaction operation, after the liquefaction operation, a drying step is performed, wherein at least one polycarboxylic acid is added to the filter cake, during or after the liquefaction operation.

The present invention provides a method for preparing a white carbon black, comprising the following steps:.

According to an embodiment of the preparation method, wherein:.

According to the present invention, the above aqueous solution, for example a water glass can be obtained by adjusting the ratio of the filtrate to the washing liquor. Or alternatively, the rice hull ash can be obtained by screening the rice hull ash of the existing technology. For example, the weight percentage content of the <NUM> oversize in the rice hull ash is not higher than <NUM> wt%, for example, not higher than <NUM> wt%, e.g., <NUM>-<NUM> wt%. For example, the weight percentage content of the <NUM> oversize in the rice hull ash is <NUM> wt%, <NUM> wt%, <NUM> wt%, <NUM> wt%, <NUM> wt%, <NUM> wt%, <NUM> wt%, <NUM> wt%, <NUM> wt%, <NUM> wt%, <NUM> wt%, <NUM> wt%, <NUM> wt%, <NUM> wt%.

According to the present invention, the weight percentage content of the <NUM> oversize refers to the percentage by weight of the oversize obtained by passing the rice hull ash through a <NUM> sieve to the total weight of the rice hull ash.

Preferably, the absorbance of an extract solution of the rice hull ash, at a detection wavelength of <NUM>-<NUM>, especially at a detection wavelength of <NUM>, may be <NUM>-<NUM>, for example <NUM>-<NUM>, e.g., <NUM>-<NUM>.

As an example, the absorbance can be measured with a spectrophotometer. In one or more embodiments, the absorbance cuvette is a <NUM> cuvette.

According to the present invention, an extract solution of the rice hull ash can be obtained by contacting the rice hull ash with a solvent or a solution. As an example, it can be obtained by contacting the rice hull ash with a solvent or a solution under reflux and/or ultrasonic conditions.

In one or more embodiments, the solvent according to the present invention is selected from one or more of water and alcoholic solvents (e.g., ethanol and methanol), preferably water, ethanol or an aqueous ethanol solution. Among others, the mass percentage concentration of the aqueous ethanol solution may be <NUM>%-<NUM>%, for example <NUM>%-<NUM>%, e.g., <NUM>%-<NUM>%, <NUM>%, <NUM>%, <NUM>% or <NUM>%.

In one or more embodiments, the solution according to the present invention is selected from an aqueous alkali solution or an alcohol solution. The alcohol may be for example methanol, ethanol or a mixture thereof; the alkali may be for example sodium hydroxide, potassium hydroxide or a mixture thereof.

In one or more embodiments, the mass-volume ratio (g:mL) of the rice hull ash according to the present invention to the solvent or the solution is <NUM>:<NUM>-<NUM>, preferably <NUM>:<NUM>-<NUM>, e.g., <NUM>:<NUM>-<NUM>.

In one or more embodiments, the time for contacting the rice hull ash according to the present invention with the solvent or the solution may be <NUM>-<NUM> hours, for example <NUM>-<NUM> hours, e.g., <NUM>-<NUM> hours, e.g., <NUM>-<NUM> hours.

Preferably, the rice hull ash is contacted with water at <NUM>-<NUM> to give an extract solution of the rice hull ash.

Preferably, the rice hull ash is contacted with water at <NUM>-<NUM> atmospheric pressures to give an extract solution of the rice hull ash.

In one or more embodiments, in the method according to the present invention, the time for contacting the rice hull ash with water is <NUM>-<NUM> hour.

In one or more embodiments, the method of the present invention may also comprise a filtration step, preferably filtering with a medium-speed filter paper and/or with an organic phase microporous filter membrane.

In one or more embodiments, the method of the present invention may also comprise a centrifugation step.

In one or more embodiments, the rotation speed of the centrifugation step according to the present invention is <NUM>-<NUM> rpm, and more preferably, the rotation speed for the centrifugation is <NUM>-<NUM> rpm.

In one or more embodiments, the time for the centrifugation step according to the present invention is <NUM>-<NUM> minutes, more preferably <NUM>-<NUM> minutes.

As an example, the absorbance of an aqueous extract solution of the rice hull ash may be less than <NUM>, for example <NUM>-<NUM>, e.g., <NUM>-<NUM>.

According to the present invention, preferably, the rice hull ash has a <NUM>-coumaric acid content of <NUM>-175µg/g, preferably <NUM>-150µg/g, more preferably <NUM>-140µg/g. As an example, the content of the <NUM>-coumaric acid can be 60µg/g, 70µg/g, 80µg/g, 90µg/g, 100µg/g, 110µg/g, 120µg/g, 130µg/g, 140µg/g, 150µg/g, 160µg/g, 170µg/g, 175µg/g.

Preferably, the relative content of <NUM>-coumaric acid in the rice hull ash is determined by detecting the extract solution of the rice hull ash.

In one or more embodiments, the extract solution of the rice hull ash is obtained by the preparation method described above.

In one or more embodiments, in the method for preparing the extract solution of the rice hull ash, the solvent is ethanol having a mass percentage concentration of <NUM>% (containing <NUM> wt% of ethanol).

In one or more embodiments, the rice hull ash is contacted with ethanol having a mass percentage concentration of <NUM>% under a reflux condition to give an extract solution of the rice hull ash.

In one or more embodiments, the time for contacting the rice hull ash with the solvent is <NUM>-<NUM> hours, preferably <NUM>-<NUM> hours.

In one or more embodiments, the extract solution of the rice hull ash is subjected to centrifugation.

In one or more embodiments, the extract solution of the rice hull ash is obtained by filtering through an organic phase microporous filter membrane.

In one or more embodiments, the method further comprises drawing a standard curve of <NUM>-coumaric acid reference substance, and further performing a linear regression on the absorbance vs. the concentration to obtain a standard curve equation.

In one or more embodiments, the method further comprises calculating the relative content of <NUM>-coumaric acid in the rice hull ash according to the standard curve equation.

In one or more embodiments, the method further comprises comparing the relative content of <NUM>-coumaric acid in the sample of the extract solution of the rice hull ash with the relative content of <NUM>-coumaric acid in the qualified extract solution of the rice hull ash.

The present invention also provides the use of the rice hull ash in the preparation of water glass or soluble glass.

According to an embodiment of the present invention, there is also provided a method for preparing the rice hull ash, which comprises combusting a rice hull to obtain the rice hull ash, wherein the rice hull combustion is carried out under a controlled ratio of the oxygen-rich air volume to the oxygen-deficient air volume.

According to the present invention, the controlled ratio of the oxygen-rich air volume to the oxygen-deficient air volume refers to adjusting the ratio of the oxygen-rich air volume to the oxygen-deficient air volume, for example, the ratio of the oxygen-rich air volume to the oxygen-deficient air volume is greater than <NUM>:<NUM>, for example, <NUM>:<NUM> or more, e.g., <NUM>:<NUM>-<NUM>:<NUM>.

As an example, the rice hull can be conveyed under a positive pressure to a boiler combustion zone for combustion.

According to an embodiment of the present invention, the rice hull ash can be prepared by the following method:.

According to the present invention, the rice hull usually enters the boiler combustion zone in a projecting attitude. After entering the boiler combustion zone, the rice hull gradually undergoes drying, cracking and gasification as the temperature rises. The combusted rice hull can gradually fall into the fire grate zone rotating at the bottom of the furnace under the action of gravity, and the temperature will gradually drop. The rice hull in the fire grate zone further undergoes a series of chemical changes such as decomposition, carbonization, and gasification at a relatively high temperature, and after the heat release, it is finally converted into the rice hull ash.

Generally speaking, the temperature in the boiler combustion zone (i.e., the furnace or the furnace zone) can be, for example, <NUM>-<NUM>, e.g., <NUM>-<NUM>, <NUM>-<NUM>. The residence time of the rice hull in the furnace can be <NUM>-<NUM> minutes, e.g., <NUM>-<NUM> minutes, e.g., <NUM>-<NUM> minutes.

According to an embodiment of the present invention, the rice hull and the oxygen-rich air can be blown into the boiler combustion zone by a blower fan.

According to an embodiment of the present invention, in order to maintain the combustion state during the boiler operation, the gas introduced into the boiler is usually divided into two types, a primary air and a secondary air, wherein the primary air includes an air for blowing the fuel and a blown oxygen-deficient air; and the secondary air can include a preheated hot air.

As an example, the air flow that can be applied to the introduction into the boiler can be selected from an oxygen-rich air and/or an oxygen-deficient air.

According to the present invention, the total amount of the oxygen-rich air is the air in the boiler primary air for blowing the fuel and all the secondary air.

According to the present invention, the oxygen content in the oxygen-rich air may be <NUM> vol% or more, e.g., <NUM> vol% or more, for example, about <NUM> vol% - about <NUM> vol%, for example, about <NUM> vol%. As an example, the oxygen-rich air can be air.

According to the present invention, the oxygen content of the oxygen-deficient air is lower than that of the oxygen-rich air, for example, less than <NUM> vol%, e.g., less than <NUM> vol%, preferably <NUM>-<NUM> vol%, and its example may be a tail gas after the combustion of the rice hull.

According to the present invention, the oxygen-deficient air can undergo the processes of purification and heat exchange before being blown into the boiler. For example, the temperature of the oxygen-deficient air can be <NUM>-<NUM>.

Preferably, the preparation method further comprises controlling the ratio of the blown-in amount of the oxygen-deficient air (m<NUM>) per unit time to the mass of the rice hull (t). For example, the ratio may be <NUM>:<NUM> or more, for example <NUM>:<NUM>-<NUM>:<NUM>, e.g., <NUM>:<NUM>-<NUM>:<NUM>.

In the method for preparing the rice hull ash according to the present invention, the rice hull ash obtained by the combustion of the rice hull can be further sieved to remove impurities such as brown rice, stones and the like. For example, the sieving can be performed through a straight-line sieve of <NUM>-<NUM> (e.g., <NUM>).

Preferably, the sieved rice hull ash can also pass through a separator under a negative pressure conveying condition to separate organic substance impurities having different specific gravities, e.g. some rice grains and the like, through the inertia.

According to an embodiment of the present invention, the temperature of the fire grate zone can generally be <NUM>-<NUM>. As an example, the fire grate may be in the shape of a chain crawler belt, and drive the rice hull and/or the rice hull ash falling on the fire grate to move at a certain speed and discharge off 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 can be about <NUM>-<NUM> wt%, for example about <NUM>-<NUM> wt%, e.g., about <NUM>-<NUM> wt%.

According to the present invention, the method can be used to obtain the rice hull ash by using the existing rice hulls as raw materials. Or alternatively, the raw rice hull is also processed by sieving. For example, the weight percentage content of the rice hull oversize is <NUM>-<NUM>%; for example, <NUM>-<NUM>%, e.g., <NUM>-<NUM>%.

According to the present invention, the weight percentage content of the rice hull oversize is detected by the following method:.

Preferably, the mass ratio of the oversize in the rice hull to the total organic impurities is <NUM>-<NUM>: <NUM>, for example <NUM>-<NUM>: <NUM>, e.g., <NUM>-<NUM>: <NUM>. The mass ratio can be obtained by calculating the ratio of the weight percentage content of the oversize to the weight percentage content of the total organic impurities. Among others, the weight percentage content of the total organic impurities refers to the total of the weight percentage contents of organic impurities in terms of starch and protein.

Preferably, the starch content in the rice hull of the present invention may be <NUM>-<NUM>%, for example <NUM>-<NUM>%; the protein content may be <NUM>-<NUM>%, for example <NUM>-<NUM>%.

According to the present invention, the rice hull can be prepared by the following method:.

As an example, after the rice in the step a1) is sieved to remove impurities, it can be further separated by a hulling machine to obtain the rice hull.

The rice hull obtained in the step a1) mainly contains organic impurities such as rice hull and full grains, broken brown rice, incomplete grains, shriveled grains and rice chaffs (also called grain sprout tips), rice hairs, and bran powder, and inorganic impurities such as sand dust, soil and rock, and metal debris.

According to the present invention, the method may comprise, in the step a2), controlling the weight percentage content of the oversize in the rice hull product and/or the mass ratio of the oversize to the total organic impurities. As an example, the weight percentage content of the oversize in the rice hull product, or the mass ratio of the oversize to the total organic impurities can be adjusted by the following methods:.

According to an embodiment of the present invention, the method further comprises in the step a2), sieving the obtained rice hull through a <NUM>-mesh sieve, and then mixing the oversize and the undersize to control the weight percentage content of the oversize in the rice hull product, or the mass ratio of the oversize to the total organic impurities.

According to the present invention, the method for determining the starch can be GB/T <NUM>-<NUM> "Determination of Starch in Foods", and the method for determining the protein can be <CIT> "National Food Safety Standards Determination of Protein in Foods" First method: Kjeldahl method for nitrogen determination.

The inventors of the present invention found that during the process development, although the impurity content cannot significantly affect the performance parameters of the final white carbon black product, the white carbon black product can exhibit different performance changes in the application of rubber products. Specifically speaking, the inventors have found that the organic substances represented by coumaric acid are significantly present in the water glass in the preparation of white carbon black, if the content of the organic substances is controlled within the range of the present invention, the white carbon black product having performance parameters comparable to those of the mineral-derived white carbon black can be obtained, and at the same time, the white carbon black product can improve the application performance of the rubber product to which said white carbon black product is applied.

The inventors of the present invention have found that the content of the water-soluble impurity in the rice hull ash is associated with the application performance of the white carbon black product, in particular has a strong correlation to the rubber tensile strength, while the other parameters of the rubber almost has no correlation to the impurity content in the upstream rice hull ash raw material. The principle is not clear, but one presumption made by the inventors is as follows: in the premise of guaranteeing the stable parameters of the white carbon black and meeting the target requirements, the appropriate residual of the impurities in the white carbon black raw material improves the fat-solubility of the white carbon black and makes the carbon chains of the elastomeric polymers such as rubber more easily combine with the white carbon black, thereby improving the rubber tensile strength. Another presumption is as follows: the impurity is not directly adsorbed on the white carbon black, but during the synthesis process of the white carbon black, an appropriate impurity content affects the ζ potential of the solution, which changes the accumulation mode of the silica microparticles; although apparently the surface parameters such as BET and CTAB of the white carbon black have little change, however, on the microscopic level, it is easier for the carbon chains of the elastic polymer like the rubber and the white carbon black to be tightly entangled, leading to subtle changes in the tensile strength of the product. Of course, it is also possible that the above two theories coexist and produce the impact at the same time, or it is also possible that other theories exist and produce the impact together.

In the present invention, the contents of these organic substances can be obtained by controlling the rice hull raw material, the combustion process, the rice hull ash raw material, and the water glass, without additionally increasing the energy consumption and causing the waste of resources. At the same time, the emission of waste water and waste liquid is reduced. Thereby, extremely high economic and environmental benefits are produced.

Without wishing to be bound by existing theories, the inventors have surprisingly found that controlling the parameters of the water glass within the range of the present invention can significantly improve the characteristics of the rice hull-derived white carbon black under the same other process parameters, and thereby significantly improve the mechanical properties of the rubber prepared by using the white carbon black as a filler, especially its mechanical strength such as tensile strength, and can reach the technical indicators of mineral-derived white carbon black. The water glass can be obtained by one of mixing the filtrate and the washing liquor, adjusting raw material parameters and preparation process parameters and the like, all of which can achieve the purpose of the present invention. Moreover, the method for preparing the white carbon black according to the present invention is simple and convenient, and is very suitable for the large-scale production. The above technical effects can be achieved by controlling the parameters of the water glass that are easy to be measured.

Hereinafter, through the description of the examples of the present invention, the above-mentioned and other characteristics and advantages of the present invention are explained and described in more detail. It should be understood that the following examples are intended to exemplify the technical solutions of the present invention, but are not intended to limit the protection scope of the present invention defined by the claims and their equivalents.

Unless otherwise specified, the materials and reagents herein are all commercially available products, or can be prepared by those skilled in the art according to the prior art.

Unless otherwise specified, the raw materials, substrates or reagents in the following examples are all commercially available products, or if appropriate, they can also be prepared by methods known in the art. The percentages are all mass percentages.

The water glass sample is drawn into a <NUM> cuvette, the absorbance is measured at <NUM> wavelength with pure water as blank control.

A sample of water glass is passed through a <NUM> organic phase microporous filter membrane and left for testing.

Preparation of reference substance solutions: <NUM> of <NUM>-coumaric acid reference substance is accurately weighed, and dissolved by adding <NUM>% ethanol and diluted to a constant volume of <NUM>. The resulting solution is then diluted with <NUM>% ethanol to give reference substance solutions having the concentrations of approximately <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>µg/ml, and left for test.

The plot of the standard curve: <NUM>% ethanol is used as blank control, and the absorbance of the prepared reference substance solutions having different concentrations are measured at <NUM>, and a linear regression of the absorbance vs. the concentration is performed to obtain the standard curve equation.

The correction of curve slope: <NUM> of <NUM>-coumaric acid reference substance is accurately weighed and dissolved by adding <NUM>% NaOH solution and diluted to a constant volume of <NUM>. The resulting solution is then diluted with <NUM>% NaOH solution to give a correction solution having the concentrations of approximately <NUM>µg/ml. The absorbance is measured at <NUM> and an absorbance coefficient is calculated according to the concentration and the absorbance. The absorption coefficient is used as the slope of the standard curve equation.

Sample measurement: With pure water as blank control, the absorbance of the test sample solution is measured at <NUM>, and the relative content of <NUM>-coumaric acid in the sample is calculated according to the standard curve equation.

The rice hull ash sample is mixed evenly and crushed. <NUM> grams of rice hull ash is weighed into a <NUM> beaker. <NUM> of distilled water is added. The mixture is boiled on an electric stove for <NUM>-<NUM> minutes. The beaker is removed and cooled. The upper aqueous solution is poured into a <NUM> small beaker with medium-speed filter paper to filter. The filtrate is sucked into a <NUM> cuvette, and the absorbance is measured at a wavelength of <NUM> with pure water as blank control.

Preparation of test solution: <NUM> of the rice hull ash sample is accurately weighed, and <NUM> of <NUM>% ethanol is precisely added. The mixture is extracted under reflux <NUM> hours, and the extract is centrifuged (<NUM> rpm, <NUM>). The supernatant is passed through a <NUM> organic phase microporous filter membrane and left for test.

The plot of the standard curve: <NUM>% ethanol is used as blank control, and the absorbances of the prepared reference substance solutions having different concentrations are measured at <NUM>, and a linear regression of the absorbance vs. the concentration is performed to obtain the standard curve equation.

Sample measurement: with <NUM>% ethanol as blank control, the absorbance of the test sample solution is measured at <NUM>, and the relative content of <NUM>-coumaric acid in the sample is calculated according to the standard curve equation (µg/g).

A test sieve having a pore diameter of <NUM> and a sieve bottom are put in place, a sample spoon is used to take out <NUM> of a sample and place it on the <NUM> sieve, the sieve lid is covered and the sieved is turned clockwise and counterclockwise for <NUM> seconds respectively; then the rice hull ash on each sieve layer is weighed. Data are calculated.

The rubber mixing mode is an internal mixing in an internal mixer. For details, refer to Example <NUM> of Chinese Patent Application <CIT>, and proceed according to the formula in Table <NUM> below.

Mixing in the first stage: the rotor speed of an internal mixer was 45rpm, the ram pressure was <NUM>. 6MPa, firstly, the solution polymerized styrene-butadiene rubber and the cis-butadiene rubber were put into an internal mixing chamber of the internal mixer and mixed for <NUM> seconds, then the white carbon black and the silane coupling agent (silicone-<NUM>) were put into the internal mixing chamber and continuously mixed for <NUM> seconds, the temperature of the rubber mass reached <NUM>, the ram was lifted for <NUM> seconds, the rotor speed was adjusted to 30rpm, the rubber mass was mixed for <NUM> seconds under the ram pressure, the temperature of the rubber material was <NUM>, the rubber was discharged to give a first-stage rubber compound, and the first-stage rubber compound was cooled to the room temperature in the air.

Mixing in the second stage: the rotor speed of an internal mixer was 45rpm, the ram pressure was <NUM>. 6MPa, the first-stage rubber compound was put into an internal mixing chamber of the internal mixer, and zinc oxide, stearic acid, and antioxidants (<NUM> and DTPD) were added and mixed for <NUM> seconds under the ram pressure, the temperature of the rubber mass reached <NUM>, the ram was lifted for <NUM> seconds, the rotor speed was adjusted to 30rpm, the rubber mass was mixed for <NUM> seconds under the ram pressure, the temperature of the rubber material was <NUM>, the rubber was discharged to give a second-stage rubber compound, and the second-stage rubber compound was cooled to the room temperature in the air.

Mixing in the third stage: the rotor speed of an internal mixer was 35rpm, the ram pressure was <NUM>. 6MPa, the second-stage rubber compound, an accelerator (CBS and DPG) and sulfur were put into an internal mixing chamber of the internal mixer and mixed for <NUM> seconds, the ram was lifted for <NUM> seconds, then the rubber mass was mixed for <NUM> seconds under the ram pressure, the temperature of the rubber material was <NUM>, the rubber was discharged to give a vulcanized rubber.

Test conditions: The physical and mechanical properties of the vulcanized rubber are tested in accordance with the corresponding ASTM standards, using the XLL-<NUM> universal material testing machine (product of LLOYD Instrument Company, UK) for testing.

The following batches were respectively taken, rice hull ash (<NUM>), sodium hydroxide (<NUM>) and water (<NUM>), and then added to the a high-pressure autoclave to proceed the reaction with a temperature rise. When the pressure rose to <NUM>, the timing was started. The reaction time was <NUM> hours. After the completion of the reaction, the pressure was released by cooling. The reaction slurry was filtered using a filter press, and the filtrate was collected and counted as concentrated water glass. The filter cake was washed with <NUM> water, and the specific gravity of the washing liquor was measured during the washing process. When the specific gravity of the washing liquor was <NUM>, the washing was finished, and the washing liquor was collected and counted as diluted water glass. The modulus of the water glass was <NUM>.

According to the proportions in Table <NUM> below, the concentrated water glass and the diluted water glass of the above preparation examples were respectively taken, and thoroughly mixed to obtain the water glass mother liquor (modulus <NUM>). The concentration and the absorbance of the prepared water glass mother liquor were recorded in Table <NUM> below.

Into the reactor equipped with an agitator and a steam heating device were introduced:
<NUM> of the water glass mother liquor (modulus <NUM>), <NUM> of an aqueous sodium sulfate solution (having a Na<NUM>SO<NUM> concentration of <NUM> %), and <NUM> of soft water were mixed and used as substrate material. The substrate material had a SiO<NUM> concentration of <NUM>/L and a Na+ concentration of <NUM>. 09mol/L, and was heated to the temperature of <NUM>.

An acid pump was turned on. A dilute sulfuric acid (specific gravity <NUM>) was added into the reactor at a flow rate of <NUM>/minutes. In the acidification stage, the pH was checked once every <NUM> minutes, and the turbidity of the reaction system was detected, so that the turbidity of the reaction system reached 60FAU at <NUM> minutes. The flow rate was kept until the pH=<NUM>. The total amount of the acid used in this stage was <NUM>. The time for adding the acid is <NUM> minutes, during which when the turbidity reached 4000FAU, the temperature rise began and proceeded at a rate of <NUM>/minutes to <NUM>. During a total of <NUM> minutes of the temperature rise procedure, the temperature was raised by <NUM>. The temperature was maintained at <NUM> until the end of the final reaction. An acidified water glass was obtained.

The simultaneous feeding process was started. The above-mentioned water glass mother liquor (modulus <NUM>) was added at a flow rate of <NUM>/min. The flow rate of dilute sulfuric acid was <NUM>/min. The molar ratio of sulfuric acid to water glass was <NUM>. The pH detection was carried out and the acid flow rate was adjusted so as to keep the pH of the slurry was stable at <NUM> ± <NUM>. At this stage, the total addition amount of water glass and acid was <NUM>.

This stage was a pH-dropping stage, in which a dilute sulfuric acid was introduced to reduce the pH to <NUM>.

After curing for <NUM> minutes, the reaction slurry was filtered with a plate filter press and washed with soft water to obtain a filter cake of white carbon black (water content = <NUM>%). A colloid mill was used to change the filter cake from the solid to a liquid slurry. The pH value of the slurry was adjusted to <NUM>.

A spray drying tower was used for drying to produce a finished product of white carbon black.

Into the reactor equipped with an agitator and a steam heating device were introduced:
<NUM> of the water glass mother liquor (modulus <NUM>, specific gravity <NUM>), the substrate material having a Na<NUM>O concentration of <NUM>/L, and <NUM> of soft water, heated to a temperature of <NUM>.

The temperature was maintained at <NUM>, and the acidification stage was started. A dilute sulfuric acid (specific gravity <NUM>) was added at a flow rate of <NUM>/minutes. The acidification was carried out until the pH = <NUM>. The total amount of the acid used in this stage was <NUM>.

The simultaneous feeding stage was started, and the temperature was maintained at <NUM>. The water glass pump was turned on and the water glass was added at <NUM>/min. Dilute sulfuric acid was added at a flow rate of <NUM>/min. The molar ratio of sulfuric acid to water glass was controlled to <NUM>. The turbidity reached 30FAU within <NUM> minutes, and the pH was detected at a frequency of <NUM> time/min. The flow rate of dilute sulfuric acid was adjusted to keep the pH was stable at <NUM>±<NUM>. The temperature rise period began at <NUM> minutes after the starting of the simultaneous feeding. When the turbidity reached 4000FAU, the temperature rise proceeded at a rate of <NUM>/minutes. At <NUM> minutes, the temperature reached <NUM>. The temperature was kept at <NUM> until the final reaction was completed. The feeding ratio was <NUM>. Wherein, the feeding ratio was the mass ratio of the aqueous water glass solution added during the simultaneous feeding stage to the aqueous water glass solution added to the substrate material in the initial stage.

During the pH-dropping stage, a dilute sulfuric acid was introduced at <NUM>/min to reduce the pH to <NUM>.

The curing time was <NUM> minutes, and the total of the reaction time was <NUM> minutes.

The cured slurry was filtered with a plate filter press and washed with soft water to obtain a filter cake of white carbon black (water content = <NUM>%). A colloid mill was used to change the filter cake from the solid to a liquid slurry. The pH value of the slurry was adjusted to <NUM>-<NUM>. Then, a spray drying tower was used for drying to produce a finished product of white carbon black.

According to the method of the present invention, the white carbon black products obtained in the above examples were used to prepare the rubber, and the results were shown in Table <NUM> and Table <NUM> below.

It can be known from the above test results that the white carbon black obtained by the method of the present invention had comparable physical and mechanical properties to the white carbon black derived from minerals. By controlling the parameters of water glass within the scope of the present invention, a white carbon black product that can improve the tensile strength of rubber can be obtained.

Rice hulls were obtained by cleaning and hulling of rough rice, and the rice hulls were subjected to a winnowing step to obtain oversize (A), undersize (B) and undersize (C), the specific winnowing step was as follows:.

<NUM>) the distance between the blower fan and the rice hull was set to <NUM>, the air speed of the blower fan was adjusted to purge the rice hull raw material with a thickness of <NUM> at an air speed of <NUM><NUM>/min for <NUM> minute, and the purged rice hull was collected and recorded as an undersize (B);
<NUM>) the air speed of the blower fan was adjusted to continue the purging at an air speed of <NUM><NUM>/min until an oversize (A) free of the rice hull was obtained, and the purged rice hull was collected and recorded as an undersize (C);
<NUM>) According to the oversize content ratio described in Table <NUM> below, the oversize (A) was mixed into the undersizes (B) and (C), and the starch and protein contents in the resulting mixture were detected. The contents of the rice hull samples were summarized in Table <NUM> below.

An acid pump was turned on. A dilute sulfuric acid (specific gravity <NUM>) was added into the reactor at a flow rate of <NUM>/minutes. In the acidification stage, the pH was checked once every <NUM> minutes, and the turbidity of the reaction system was detected, so that the turbidity of the reaction system reached 60FAU at <NUM> minutes. The flow rate was kept until the pH=<NUM>. The total amount of the acid used in this stage was <NUM>. The time for adding the acid is <NUM> minutes, during which when the turbidity reached 4000FAU, the temperature rise began and proceeded at a rate of <NUM>/minutes to <NUM>. During a total of <NUM> minutes of the temperature rise procedure, the temperature was raised by <NUM>. The temperature was maintained at <NUM> until the end of the final reaction.

The simultaneous feeding process was started. The water glass water solution (modulus <NUM>) was added at a flow rate of <NUM>/min. The flow rate of dilute sulfuric acid was <NUM>/min. The molar ratio of sulfuric acid to water glass was <NUM>. The pH detection was carried out and the acid flow rate was adjusted so as to keep the pH of the slurry was stable at <NUM>± <NUM>. At this stage, the total addition amount of water glass and acid was <NUM>.

In the pH-dropping stage, a dilute sulfuric acid was introduced to reduce the pH to <NUM>.

After curing for <NUM> minutes, the reaction slurry was filtered with a plate filter press and washed with soft water to obtain a filter cake of white carbon black (water content = <NUM>%). A colloid mill was used to change the filter cake from the solid to a liquid slurry. The pH value of the slurry was adjusted to <NUM>. A spray drying tower was used for drying to produce a finished product of white carbon black. The performance test results were as follows.

<NUM>) Preparation of rice hull ash: the same batch rice hulls were sent to the boiler furnace for combustion at a rate indicated in Table <NUM> under a positive pressure. According to the parameters in Table <NUM>, the flow rates of the oxygen-rich air (air) and the oxygen-deficient air at the furnace bottom were controlled for combustion. The furnace combustion temperature was <NUM>, and the fire grate rotation speed was adjusted to control the residence time of the rice hull in the furnace to <NUM> minutes, and the rice hull ash discharged from the tail of the fire grate was collected as raw material. <NUM>) Impurity removal from rice hull ash: the rice hull ash raw material obtained in the step <NUM>) was sieved through a <NUM> straight-line sieve and an inertial separator to remove impurities and collect the obtained rice hull ash samples for use.

After curing for <NUM> minutes, the reaction slurry was filtered with a plate filter press and washed with soft water to obtain a filter cake of white carbon black (water content = <NUM>%). A colloid mill was used to change the filter cake from the solid to a liquid slurry. The pH value of the slurry was adjusted to <NUM>. A spray drying tower was used for drying to produce a finished product of white carbon black.

The above-mentioned method was used to detect the absorbance and the coumaric acid content of water glass, and the obtained white carbon black product was used to prepare rubber. The performance test results were as follows.

The same batch of rice hull ash (<NUM> oversize content of <NUM>%, the rice hull ash absorbance of <NUM>, <NUM>-coumaric acid content of <NUM>. 8335µg/g) was treated with a <NUM> straight line sieve to give a <NUM> oversize (A) and a <NUM> undersize (B), which were reformulated according to the <NUM> oversize proportion (weight ratio) in Table <NUM> below to obtain the rice hull ashes in Table <NUM> below.

The same batch of rice hull ash (<NUM> oversize content of <NUM>%, the rice hull ash absorbance of <NUM>, <NUM>-coumaric acid content of <NUM>. 8335µg/g) was treated with a <NUM> straight line sieve to give a <NUM> undersize (B), which was mixed with the non-sieved rice hull ash according to the proportions in Table <NUM> below to obtain the corresponding rice hull ashes.

The same batch of rice hull ash (<NUM> oversize content of <NUM>%, the rice hull ash absorbance of <NUM>, <NUM>-coumaric acid content of <NUM>. 8335µg/g) was treated with a <NUM> straight line sieve to give a <NUM> oversize (A), which was further mixed according to the proportion in Table <NUM> below with the rice hull ash obtained by mixing according to Preparation Example <NUM> to obtain the corresponding rice hull ash.

Rice hulls were obtained by cleaning and hulling of the same batch of rough rice, and the rice hulls were subjected to a winnowing step to obtain an oversize (A), an undersize (B) and an undersize (C), the specific winnowing step was as follows:.

According to the weight ratio in Table <NUM> below, the oversize (A), the undersize (C) and the undersize (B) were mixed, and the starch and protein contents in the resulting mixture were detected. The contents of the rice hull samples <NUM> and <NUM> were summarized in Table <NUM> below.

The rice hulls of samples <NUM>-<NUM> were sent to the boiler furnace for combustion at a rate of <NUM> tons/hour under a positive pressure. The furnace combustion temperature was <NUM>, and the fire grate rotation speed was adjusted to control the residence time of the rice hull in the furnace to <NUM> minutes, and the rice hull ashes of Preparation Examples <NUM>-<NUM> discharged from the tail of the fire grate was collected. The content of the <NUM> oversize and the water-boiled absorbance of the obtained rice hull ash were measured, and the results were recorded in Table <NUM> below:.

According to the above method, the absorbance and <NUM>-coumaric acid content of rice hull ash were detected, and the results were as follows:.

The white carbon black of Examples <NUM>-<NUM> corresponded to the rice hull ashes of Preparation Examples <NUM>-<NUM>, respectively. With the above method, the white carbon black was used to prepare the rubber, and the results were summarized below.

Claim 1:
A method for preparing a white carbon black, comprising following steps:
d1) a substrate material containing an aqueous solution containing a silicate represented by a formula M<NUM>O·nSiO<NUM> and an acid are contacted to give a slurry E;
d2) the slurry E obtained in the step d1) is subjected to a solid-liquid separation to give a solid-phase fraction, and the solid-phase fraction is dried to give a white carbon black product,
the aqueous solution containing the silicate represented by the formula M<NUM>O·nSiO<NUM> with an absorbance of <NUM>-<NUM>, preferably, the absorbance of the aqueous solution is <NUM>-<NUM>; the absorbance is measured in a <NUM> cuvette,
M is selected from alkali metal elements K and Na;
n is <NUM>-<NUM>;
a liquid fraction has a <NUM>-coumaric acid content of <NUM>-<NUM>µg/mL.