JP2008207169A - Manufacturing method of white chaff ash - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of white chaff ash from chaff. <P>SOLUTION: The manufacturing method of white chaff ash comprises a pre-treating process of treating chaff with a lignin decomposition agent, a carbonizing process of heating chaff subjected to the pre-treating process at 250-350°C for 30 minutes or more, and a calcining process of calcining the chaff subjected to the carbonizing process at 480°C or more for 30 minutes or more. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing white rice husk ash from rice husk.

  Rice husks generated during threshing of rice and the like are discharged in large quantities every year as agricultural waste, and some of them are used as fuel, but most of them have no way of effective use and are discarded as they are, or The current situation is that it is incinerated and used as rice husk ash before it is disposed of. In recent years, there has been a strong demand for effective utilization of rice husk ash in the wake of increasing use of resources and recycling.

Under such circumstances, it has been proposed to use rice husk ash obtained by firing rice husk as an alternative material for cement (see Patent Document 1).
JP-A-7-19631

  By the way, the conventional rice husk ash is black or dark gray due to unburned residual carbon. The rice husk ash obtained by the method described in Patent Document 1 also exhibits black or dark gray because carbon content still remains although unburned carbon is reduced.

  However, depending on the use for which rice husk ash is effectively used, it is not uncommon for such black or dark gray to be a major problem. For example, when using rice husk ash as a cosmetic powder, it is naturally required to have a white color, and when considering use in industrial applications, a white color is also required. There are many cases.

  This invention is made | formed in view of this technical background, Comprising: It aims at providing the method of manufacturing white type | system | group rice husk ash from a rice husk.

  In order to achieve the above object, the present invention provides the following means.

[1] a pretreatment step of treating rice husk with a lignin degrading agent;
A carbonization step of heating rice husks having undergone the pretreatment step at 250 to 350 ° C. for 30 minutes or more;
A baking step of baking the chaff after the carbonization step at a temperature of 480 ° C. or more for 30 minutes or more.

  [2] The method for producing white rice husk ash according to item 1, wherein a bleaching agent or an acid is used as the lignin decomposing agent.

[3] a pretreatment step of treating rice husk with a bleach;
A pretreatment step of treating rice husk with acid;
A carbonization step of heating rice husks having undergone the two pretreatment steps at 250 to 350 ° C. for 30 minutes or more;
A baking step of baking the chaff after the carbonization step at a temperature of 480 ° C. or more for 30 minutes or more.

[4] a pretreatment step of treating rice husk with a lignin degrading agent;
A washing step for washing rice husks that have undergone the pretreatment step;
A drying step of drying the rice husks that have undergone the washing step;
A carbonization step of heating the chaff after the drying step at 250 to 350 ° C. for 30 minutes or more;
A baking step of baking the chaff after the carbonization step at a temperature of 480 ° C. or more for 30 minutes or more.

  [5] The method for producing white rice husk ash according to item 4, wherein a bleaching agent or an acid is used as the lignin decomposing agent.

  [6] The method for producing white rice husk ash according to item 2, 3 or 5, wherein sodium hypochlorite is used as the bleaching agent.

  [7] The method for producing white husk ash according to any one of items 1 to 6, wherein a firing temperature in the firing step is set in a range of 500 to 795 ° C.

In the invention of [1], rice husk is treated with a lignin decomposing agent as a pretreatment, so that the lignin component considered to be the main cause of black coloring can be decomposed and removed. In addition, since the rice husk that has undergone this pretreatment step is heated and carbonized for 30 minutes or more at a low temperature of 250 to 350 ° C., it is possible to prevent carbon from being included in the molten salt (K ₂ O or the like). Furthermore, by burning the rice husk at a temperature of 480 ° C. or higher for 30 minutes or more, the carbonized component can be removed by baking, whereby white husk ash can be obtained. In this production method, the rice husk is treated with a lignin decomposing agent as a pretreatment, so that the lignin component is decomposed and removed at this stage, so that the residual carbon content in the rice husk ash obtained through the subsequent firing step is substantially 0%. It becomes possible to do.

  In the invention of [2], since a bleaching agent or an acid is used as a lignin decomposing agent, the lignin component considered to be the main cause of the black coloring can be sufficiently decomposed and removed, and a white husk ash that is closer to pure white is produced. it can. In comparison between the bleaching agent and the acid, the white rice husk ash closer to white can be produced by pretreatment with the bleaching agent. Moreover, when an acid is used as a lignin decomposing agent, heavy metals can be sufficiently removed.

In the invention of [3], rice husk is treated with a lignin decomposing agent as a pretreatment (pretreatment with a bleaching agent and acid pretreatment is performed), so that the lignin component considered to be the main cause of black coloring is decomposed. Can be removed. In addition, since the rice husk that has undergone this pretreatment step is heated and carbonized for 30 minutes or more at a low temperature of 250 to 350 ° C., it is possible to prevent carbon from being included in the molten salt (K ₂ O or the like). Furthermore, by burning the rice husk at a temperature of 480 ° C. or higher for 30 minutes or more, the carbonized component can be removed by baking, whereby white husk ash can be obtained. In this production method, the rice husk is treated with a lignin decomposing agent as a pretreatment, so that the lignin component is decomposed and removed at this stage, so that the residual carbon content in the rice husk ash obtained through the subsequent firing step is substantially 0%. It becomes possible to do. Moreover, since it has the process of processing rice husk with an acid, a heavy metal can fully be removed. In the invention [3], the order of execution of the pretreatment step for treatment with a bleaching agent and the pretreatment step for treatment with an acid is not particularly limited, and either may be carried out first.

In the invention of [4], rice husk is treated with a lignin decomposing agent as a pretreatment, so that the lignin component considered to be the main cause of black coloring can be decomposed and removed. In addition, since the rice husk that has undergone this pretreatment step is heated and carbonized for 30 minutes or more at a low temperature of 250 to 350 ° C., it is possible to prevent carbon from being included in the molten salt (K ₂ O or the like). Furthermore, by burning the rice husk at a temperature of 480 ° C. or higher for 30 minutes or more, the carbonized component can be removed by baking, whereby white husk ash can be obtained. In this production method, the rice husk is treated with a lignin decomposing agent as a pretreatment, so that the lignin component is decomposed and removed at this stage, so that the residual carbon content in the rice husk ash obtained through the subsequent firing step is substantially 0%. It becomes possible to do. In addition, in this production method, the rice husks that have undergone the pretreatment process are washed, so that the lignin decomposing agent used in the pretreatment can be sufficiently washed away.

  In the invention of [5], since a bleaching agent or an acid is used as a lignin decomposing agent, the lignin component considered to be the main cause of the black coloring can be sufficiently decomposed and removed, and a white husk ash that is closer to pure white is produced. it can. In comparison between the bleaching agent and the acid, the white rice husk ash closer to white can be produced by pretreatment with the bleaching agent. Moreover, when an acid is used as a lignin decomposing agent, heavy metals can be sufficiently removed.

  In the invention of [6], since sodium hypochlorite is used as the bleaching agent, white husk ash that is closer to pure white can be produced.

  In the invention of [7], since the firing temperature in the firing step is set in a range of 500 to 795 ° C., amorphous white rice husk ash can be produced.

  A method for producing white rice husk ash according to the present invention will be described. First, rice husk is treated with a lignin decomposing agent (pretreatment step).

  The rice husk as a raw material for production is not particularly limited, and examples thereof include rice husks obtained by threshing of polished rice.

  The lignin decomposing agent is not particularly limited as long as it can decompose lignin contained in rice husks, and any lignin decomposing agent can be used. Of these, bleaching agents and acids are preferably used as the lignin decomposing agent. The bleaching agent is not particularly limited, and examples thereof include sodium hypochlorite, sodium hyposulfite, hydrogen peroxide, ozone and the like. Among these, sodium hypochlorite is particularly suitable. The acid is not particularly limited, and examples thereof include hydrochloric acid, acetic acid, nitric acid, formic acid and the like.

  In addition, since the content rate of a heavy metal component can be reduced significantly when pre-processing using an acid as a lignin decomposing agent, the obtained white rice husk ash is particularly suitable as a cosmetic powder.

  The method for the treatment is not particularly limited, and examples thereof include a method of immersing rice husks in an aqueous solution of a lignin decomposing agent. The concentration of the aqueous solution of lignin decomposing agent is preferably in the range of 0.1 to 12% by mass.

  The rice husks that have undergone the pretreatment step are preferably subjected to a drying treatment after being washed with water or the like. By washing, the lignin decomposing agent used in the pretreatment can be sufficiently washed away.

  The drying treatment may be natural drying or heat drying, and the method is not particularly limited.

  Next, the rice husk is heated at 250 to 350 ° C. for 30 minutes or more (carbonization step). Especially, it is preferable to heat a rice husk at 260-340 degreeC for 30 minutes or more, and a especially preferable temperature range is 280-320 degreeC.

Thus, by heating the rice husk at a low temperature of 250 to 350 ° C. for 30 minutes or more, it is possible to sufficiently prevent carbon (carbide) from being included in the molten salt (K ₂ O or the like). That is, without performing the carbonization step of heating at 250 to 350 ° C. for 30 minutes or more, when the baking step is performed, the carbon is included in the molten salt (K ₂ O or the like) and cannot go out, As a result, black or dark gray rice husk ash is obtained. Therefore, it is important to carry out the carbonization step of heating rice husks at 250 to 350 ° C. for 30 minutes or more in order to obtain white husk ash.

  The carbonization step is preferably performed in a closed air atmosphere. In this case, there is an advantage that carbonization can be performed uniformly. Moreover, the said carbonization process is normally performed within a combustion furnace.

  Next, the rice husks that have undergone the carbonization step are baked at a temperature of 480 ° C. or higher for 30 minutes or longer (baking step). Among these, baking at 500 to 795 ° C. for 30 minutes or more is preferable. In this case, amorphous white rice husk ash is obtained. On the other hand, when baked at a temperature of 800 ° C. or higher for 30 minutes or longer, crystalline white rice husk ash is obtained.

  The firing step is preferably performed in an open air atmosphere. In this case, there is an advantage that the whitening can be performed uniformly. Moreover, the said baking process is normally performed within a combustion furnace.

  The rice husk ash obtained through the baking step can be used as it is, or may be pulverized as necessary to obtain a powder having a desired particle size.

  The rice husk ash obtained through the baking step does not contain carbon and exhibits a white color, so that it can be used, for example, as a cosmetic powder. In addition, the obtained rice husk ash has a large number of nano-sized ultrafine pores formed (see FIG. 3), and this can provide an adsorption action and moisture retention effect on moisture and fat. It is particularly preferably used as a cosmetic powder. Moreover, since the obtained rice husk ash has a large number of nano-sized ultrafine pores, the effect of improving the sustained release of components such as fragrances can also be obtained, so that it can be used for various purposes.

  Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

<Example 1>
After putting rice husk (rice husk obtained by rice threshing) in the container, an aqueous sodium hypochlorite solution (concentration 2% by mass) was further introduced into the container so that the entire rice husk was immersed. After this immersion state was continued for 2 hours at room temperature, the rice husk was taken out and the rice husk was washed three times with water. Thereafter, the rice husk is dried by ventilation, and then the dried rice husk is heated in a closed air atmosphere at 300 ° C. for 2 hours in a combustion furnace, and then is directly heated to 600 ° C. at a temperature rising rate of 50 ° C./10 minutes. The mixture was baked at 600 ° C. for 2 hours in an open air atmosphere in a combustion furnace to obtain white husk ash (powder). This white rice husk ash was a white color close to pure white.

  An electron micrograph of the white husk ash obtained in Example 1 is shown in FIG. From this, it can be seen that a number of nano-sized ultrafine pores are formed in the white husk ash.

  Table 1 shows the composition analysis result of the obtained white chaff ash by X-ray diffraction analysis. As apparent from Table 1, no carbon residue was observed in the obtained white rice husk ash.

<Example 2>
After putting rice husk (rice husk obtained by rice threshing) in the container, an aqueous sodium hypochlorite solution (concentration 2% by mass) was further introduced into the container so that the entire rice husk was immersed. After this immersion state was continued for 2 hours at room temperature, the rice husk was taken out and the rice husk was washed three times with water. Thereafter, the rice husk is dried by ventilation, and then the dried rice husk is heated in a closed air atmosphere at 300 ° C. for 2 hours in a combustion furnace, and then heated at a heating rate of 50 ° C./10 minutes at 800 ° C. over 1 hour. The mixture was baked at 800 ° C. for 2 hours in an open air atmosphere in a combustion furnace to obtain white husk ash (powder). This white rice husk ash was a white color close to pure white.

  The X-ray diffraction measurement result of the white husk ash obtained in Example 2 is shown in FIG. In the X-ray diffraction measurement graph shown in FIG. 2, since the diffraction peak of crystalline silica is strong at a diffraction angle of about 22 degrees, the white rice husk ash obtained in Example 2 is crystalline. I understand that.

  On the other hand, the X-ray diffraction measurement result of the white husk ash obtained in Example 1 is shown in FIG. In the X-ray diffraction measurement graph shown in FIG. 1, almost no diffraction peak based on crystalline silica at a diffraction angle of about 22 degrees is recognized (even if the intensity scale on the vertical axis is greatly enlarged, almost no diffraction peak is recognized). From this, it can be seen that the white rice husk ash obtained in Example 1 is amorphous.

<Example 3>
As a lignin decomposing agent, white chaff ash (as shown in Example 1) was used except that a hydrochloric acid aqueous solution (concentration 3.2% by mass) was used instead of a sodium hypochlorite aqueous solution (concentration 2% by mass). Powder). This white rice husk ash was a white color close to pure white.

  Table 1 shows the composition analysis results of the obtained white husk ash by X-ray diffraction analysis. As apparent from Table 1, no carbon residue was observed in the obtained white rice husk ash. In addition, the obtained white rice husk ash had a significantly lower content of heavy metal components such as Mn than Example 1. That is, since the pretreatment was performed using an acid as the lignin decomposing agent, the heavy metal component could be sufficiently removed.

<Example 4>
After putting rice husk (rice husk obtained by rice threshing) in the container, an aqueous sodium hypochlorite solution (concentration 2% by mass) was further introduced into the container so that the entire rice husk was immersed. After this immersion state was continued for 2 hours at room temperature, the rice husk was taken out and the rice husk was washed three times with water. Next, after the washed rice husk was placed in a container, an aqueous hydrochloric acid solution (concentration: 3.2% by mass) was further introduced into the container so that the entire rice husk was immersed. After this immersion state was continued for 2 hours at room temperature, the rice husk was taken out and the rice husk was washed three times with water. Thereafter, the rice husk is dried by ventilation, and then the dried rice husk is heated in a closed air atmosphere at 300 ° C. for 2 hours in a combustion furnace, and then is directly heated to 600 ° C. at a temperature rising rate of 50 ° C./10 minutes. The mixture was baked at 600 ° C. for 2 hours in an open air atmosphere in a combustion furnace to obtain white husk ash (powder). This white rice husk ash was a white color close to pure white.

  Table 1 shows the composition analysis results of the obtained white husk ash by X-ray diffraction analysis. As apparent from Table 1, no carbon residue was observed in the obtained white rice husk ash. In addition, the obtained white rice husk ash had a significantly lower content of heavy metal components such as Mn than Example 1. That is, since it has the process of pre-processing using an acid, the heavy metal component was fully removable.

<Example 5>
A white rice husk ash (powder) was used in the same manner as in Example 1 except that an aqueous acetic acid solution (concentration 4% by mass) was used in place of the sodium hypochlorite aqueous solution (concentration 2% by mass) as the lignin decomposing agent. ) This white rice husk ash was a white color close to pure white.

  Table 1 shows the composition analysis results of the obtained white husk ash by X-ray diffraction analysis. As apparent from Table 1, no carbon residue was observed in the obtained white rice husk ash. In addition, the obtained white rice husk ash had a significantly lower content of heavy metal components such as Mn than Example 1. That is, since the pretreatment was performed using an acid as the lignin decomposing agent, the heavy metal component could be sufficiently removed.

<Example 6>
After putting rice husk (rice husk obtained by rice threshing) in the container, an aqueous sodium hypochlorite solution (concentration 2% by mass) was further introduced into the container so that the entire rice husk was immersed. After this immersion state was continued for 2 hours at room temperature, the rice husk was taken out and the rice husk was washed three times with water. Next, after the washed rice husk was placed in a container, an aqueous acetic acid solution (concentration: 4% by mass) was further introduced into the container so that the entire rice husk was immersed. After this immersion state was continued for 2 hours at room temperature, the rice husk was taken out and the rice husk was washed three times with water. Thereafter, the rice husk is dried by ventilation, and then the dried rice husk is heated in a closed air atmosphere at 300 ° C. for 2 hours in a combustion furnace, and then is directly heated to 600 ° C. at a heating rate of 50 ° C./10 minutes. The mixture was baked at 600 ° C. for 2 hours in an open air atmosphere in a combustion furnace to obtain white husk ash (powder). This white rice husk ash was a white color close to pure white.

  Table 1 shows the composition analysis results of the obtained white husk ash by X-ray diffraction analysis. As apparent from Table 1, no carbon residue was observed in the obtained white rice husk ash. In addition, the obtained white rice husk ash had a significantly lower content of heavy metal components such as Mn than Example 1. That is, since it has the process of pre-processing using an acid, the heavy metal component was fully removable.

<Example 7>
A white rice husk ash (powder) was used in the same manner as in Example 1 except that hydrogen peroxide water (concentration 20%) was used in place of the sodium hypochlorite aqueous solution (concentration 2 mass%) as the lignin decomposing agent. Body). This white rice husk ash was a white color close to pure white.

  Table 1 shows the composition analysis results of the obtained white husk ash by X-ray diffraction analysis. As apparent from Table 1, no carbon residue was observed in the obtained white rice husk ash.

  The white rice husk ash obtained by the production method of the present invention can be used, for example, as cosmetic powder, waste gas purification catalyst carrier, adsorbent, deodorant, water purification material, etc., but is particularly limited to these uses. It is not a thing.

2 is a graph showing the results of X-ray diffraction measurement of white chaff ash obtained in Example 1. FIG. 4 is a graph showing the results of X-ray diffraction measurement of white chaff ash obtained in Example 2. 2 is a scanning electron micrograph (SEM photograph) of the white rice husk ash obtained in Example 1. FIG.

Claims (7)

A pretreatment step of treating rice husk with a lignin degrading agent;
A carbonization step of heating rice husks having undergone the pretreatment step at 250 to 350 ° C. for 30 minutes or more;
A baking step of baking the chaff after the carbonization step at a temperature of 480 ° C. or more for 30 minutes or more.   The method for producing white rice husk ash according to claim 1, wherein a bleaching agent or an acid is used as the lignin decomposing agent. A pretreatment step of treating rice husk with bleach;
A pretreatment step of treating rice husk with acid;
A carbonization step of heating rice husks having undergone the two pretreatment steps at 250 to 350 ° C. for 30 minutes or more;
A baking step of baking the chaff after the carbonization step at a temperature of 480 ° C. or more for 30 minutes or more. A pretreatment step of treating rice husk with a lignin degrading agent;
A washing step for washing rice husks that have undergone the pretreatment step;
A drying step of drying the rice husks that have undergone the washing step;
A carbonization step of heating the chaff after the drying step at 250 to 350 ° C. for 30 minutes or more;
A baking step of baking the chaff after the carbonization step at a temperature of 480 ° C. or more for 30 minutes or more.   The method for producing white chaff ash according to claim 4, wherein a bleaching agent or an acid is used as the lignin decomposing agent.   The method for producing white rice husk ash according to claim 2, 3 or 5, wherein sodium hypochlorite is used as the bleaching agent.   The manufacturing method of the white-type rice husk ash of any one of Claims 1-6 which sets the calcination temperature in the said baking process to the range of 500-795 degreeC.