JP6198272B2 - Method for producing silica sand granule - Google Patents

Description

  The present invention relates to a novel method for producing a quartz sand granule. Specifically, it has the properties that can be handled in the same way as silica, which is normally used as a raw material when producing metallic silicon, and produces quartz sand granulate that can replace silica in the production of metallic silicon at low temperature. A method is provided.

  In general, metallic silicon uses silica as a raw material and charcoal, coke, coal, wood chips, etc. as a reducing material, and the mixture is heated at about 2000 ° C. in an arc furnace to reduce the silica. can get. As the silica stone, those having a size of 5 mm to 200 mm are usually used. This is to ensure air permeability in the furnace. That is, in the arc furnace, carbon monoxide (CO) gas and silicon monoxide (SiO) gas are generated as a gas phase in the process of the reduction reaction of the silica, so that all or a part of them is used as the raw material layer. Need to escape through.

The reduction reaction of silicon dioxide (SiO ₂ ), which is the main component of the silica, generally proceeds according to the following formula (1).
SiO ₂ + 2C → Si + 2CO (1)
However, in reality, the reaction is complicated and is decomposed into the following elementary reactions, and these elementary reactions are considered to occur in parallel.
SiO ₂ + C → SiO + CO (2)
SiO + 2C → SiC + CO (3)
SiO ₂ + 3C → SiC + 2CO (4)
SiO + SiC → 2Si + CO (5)
SiO ₂ + 2SiC → 3Si + 2CO (6)
SiO + C → Si + CO (7)
SiC + SiO ₂ → Si + SiO + CO (8)
Si + SiO ₂ → 2SiO (9)
Thus, the condensed phase in the arc furnace temperature range is SiO ₂ , C, SiC, Si, and the gas phase is CO, SiO. In addition, SiO gas is generated from the high temperature portion near the tip of the in-furnace electrode by the reaction of the formula (2). In the upper part of the raw material layer, when the SiO gas or CO gas that generated the gap between the layers rises and is discharged, precipitates adhere to the wall surface of the gap that is the passage by the following reaction.
3SiO + CO → 2SiO ₂ + SiC (10)
2SiO → Si + SiO ₂ (11)
On the other hand, quartz sand has abundant resources compared to quartz stone, and in addition, it is easy to mine, so it can be a great advantage if quartz stone can be substituted as a raw material for metallic silicon.

  However, when silica sand is used as a raw material, the number of voids is smaller than that of silica stone, and when deposits are deposited due to the reactions of the above-described formulas (10) and (11), the voids are significantly reduced compared with the above-mentioned silica stone. It is feared that it is difficult to escape the gas of CO and SiO generated in the reaction.

  Further, as can be seen from the formulas (2) to (8), if the CO stays, the progress of the reaction is hindered. That is, SiC is deposited on the bottom of the furnace and causes operational troubles.

  Therefore, it is necessary to form silica sand as a raw material for metal silicon to be supplied to the arc furnace to have a property and size equivalent to those of silica.

  In response to the above requirements, Patent Document 1 describes a manufacturing method in which silica sand is pulverized, an alkaline earth metal compound as a binder is mixed and hardened, and this is heated to increase the strength. However, when the present inventors used the silica sand granule produced by the production method of Patent Document 1 for the production of metal silicon, when the temperature during the heat treatment is 1000 ° C. or less, the silica sand granule is produced during the production of metal silicon. It was found that the body could collapse and there was room for improvement in the strength of the silica sand granule. In order to prevent the silica sand granule from collapsing during the production of metallic silicon, it is necessary to heat to a high temperature of 1000 ° C. or higher during the heat treatment, and a large amount of energy such as electricity or heat is used during the production of the silica sand granule. There was a problem that was necessary.

International Publication No. 2012/060285 Pamphlet

  An object of this invention is to provide the method of manufacturing the quartz sand granule which has high intensity | strength which can substitute for the quartzite normally used as a raw material when manufacturing a metallic silicon at low temperature.

  As a result of intensive studies on the above problems, the present inventors have added an alkaline earth metal compound as a binder to silica sand, and by containing a saccharide, the dispersibility of the alkaline earth metal compound is improved. It has been found that a silica sand granule having improved strength that does not collapse in an arc furnace can be obtained, and the present invention has been completed.

  That is, this invention granulates the mixture containing 2-6 mass parts of saccharides, 0.1-10 mass parts of alkaline-earth metal compounds, and water with respect to 100 mass parts of quartz sand, It is a manufacturing method of a body.

  In addition, as the silica sand, the particle size of all particles is 1400 μm or less, the relative particle amount (weight) of particle size 75 μm or less is 25 to 85%, the particle size is more than 150 μm, and the relative particle amount (weight) is 1400 μm or less. ) Is preferably from 0% to 50% (however, the relative particle amount of 1400 μm or less is 100%) in order to further increase the strength of the resulting silica sand granule.

  The saccharide is preferably selected from monosaccharides and oligosaccharides.

  Moreover, it is preferable that the mixing amount of the said water is a ratio of 10-20 weight part with respect to 100 weight part of silica sand.

  Furthermore, it is preferable to mix the saccharide with other components in a state of being previously dissolved in water in order to improve the dispersibility of the alkaline earth metal compound and further increase the strength of the silica sand granule.

  According to the production method of the present invention, by adding an alkaline earth metal compound as a binder to silica sand and containing saccharides as a dispersant, metal silicon is produced even when heat treatment is performed at a temperature lower than conventional. In this case, a silica sand granule having a high strength that can be substituted for the silica usually used as a raw material is provided.

(Manufacturing method of silica sand granule)
In the present invention, the quartz sand granule is produced by molding and drying a quartz sand mixture containing quartz sand, an alkaline earth metal compound, a saccharide and water.

(Cotton sand)
The cinnabar used in the present invention is not particularly limited, but considering that the resulting silica sand granule is used as a raw material for metallic silicon, the purity is such that the SiO ₂ content is 97 wt% or more. In particular, it is preferably 98% by weight or more, more preferably 99% by weight or more, and particularly preferably 99.5% by weight or more. When metal silicon is produced from silica sand granules, some impurities other than SiO ₂ components are separated when the metal silicon reduced and melted in the arc furnace is discharged from the furnace and solidifies, but the impurity content As the amount increases, the amount remaining in the metal silicon also increases, and the quality of the metal silicon tends to deteriorate. That is, the impurity content remaining in the obtained silicon can be effectively reduced by using high-purity silica sand with few impurities in the silica sand. In addition, it is possible to prevent the problem that the evaporated impurities adhere to the peripheral wall of the furnace and the wall of the piping due to heating in the arc furnace, and it is easy to deposit, and the arc furnace should be used stably for a long time. Can do.

  In particular, when an alkali metal atom is contained as the impurity, cristobalite progresses at a relatively low temperature, and the granulated body tends to be self-destructed due to expansion due to the density difference. Therefore, the ratio (M1 / Si) of alkali metal atoms to Si atoms contained in the silica sand granule is preferably less than 0.01.

  In order to further improve the strength of the silica sand granule, the silica sand used in the present invention has a total particle size of 1400 μm or less and a relative particle amount (hereinafter also referred to as “fine particle amount”) having a particle size of 75 μm or less. ) Is 25% to 85%, preferably 40% to 60%, and the relative particle amount (hereinafter also referred to as “coarse particle amount”) in the range of particle diameters greater than 150 μm and 1400 μm or less is 0% to 50%. Preferably, it is preferable to use silica sand of 20% to 35% (however, the relative particle amount of 1400 μm or less is 100%).

  In the present invention, the average particle size of the silica sand is the average particle size of the particle size distribution obtained on a volume basis by laser diffraction / scattering particle size analysis measurement. Moreover, the relative particle amount and particle size distribution of the silica sand were determined by sieving as shown in the examples.

  When using the silica sand having the above particle size distribution, the total of the fine particle amount and the coarse particle amount is 60% or more, particularly 70% or more, which is more effective in expressing the strength of the resulting silica sand granule. Moreover, it is more preferable to adjust the particle size distribution so that the ratio of fine particle amount / coarse particle amount is 2 to 1.2.

  In the present invention, in order to obtain silica sand having the specific particle size distribution as silica sand, the particle size of all particles is 1400 μm or less, silica sand containing silica sand having a particle size of 75 μm or less, and a particle size of more than 150 μm and 1400 μm or less. A method of mixing silica sand containing silica sand so as to be in the above range is most preferable.

  Further, the silica sand having the above respective particle size distributions, particularly the silica sand containing silica sand having a particle size of 75 μm or less, is generally obtained by pulverizing the silica sand. The pulverization of the silica sand can be carried out using a known pulverizer. Examples of the pulverizer include a screw mill described in Tables 1 and 10 on pages 503 to 505 of the powder engineering manual (edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). Powder layer striking crushers such as stamp mills, high speed rotary impact crushers such as disc mills, pin mills, screen mills, hammer mills, centrifugal classification mills, roll rolling crushers such as roller mills, ball mills, vibrations Ball mills such as ball mills and planetary pulverizers; tower pulverizers, stirred tank pulverizers, flow-tube pulverizers, annular pulverizers and other medium agitation pulverizers, and jet pulverizers. Among the above pulverizers, a pulverizer that requires less energy for pulverization and contains fewer impurities during pulverization is preferable. Examples of such a pulverizer include a medium agitating pulverizer, a ball ball mill such as a vibration ball mill, a rotary ball mill, and a planetary pulverizer, and a roll rolling pulverizer such as a roller mill. The ball medium mill can be finely pulverized and is suitable for mass processing, and the roll-rolling pulverizer has little contamination and a large processing capacity. Therefore, each pulverizer may be used in accordance with the intended pulverized product.

  In addition, if possible, you may obtain the silica sand which has the particle size distribution in which the said fine particle amount and the coarse particle amount were adjusted by grinding | pulverization, without mixing the silica sand from which a particle size distribution differs as mentioned above.

(Alkaline earth metal compounds)
In the present invention, known alkaline earth metal compounds that act as a binder for silica sand can be used without particular limitation. For example, a calcium compound or a magnesium compound is mentioned.

Examples of the calcium compound include calcium hydroxide, calcium carbonate, calcium oxide, calcium sulfate, and mixtures thereof. Among these, calcium hydroxide, calcium oxide or a mixture thereof is preferably used. These exhibit alkalinity upon contact with water, increase the reactivity with SiO _2, and contribute to increasing the strength of the granulated body.

Examples of the magnesium compound include magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium sulfate, and a mixture thereof. Among these, magnesium hydroxide, magnesium oxide or a mixture thereof is preferably used. These exhibit alkalinity upon contact with water, increase the reactivity with SiO _2, and contribute to increasing the strength of the granulated body.

  Among the alkaline earth metal compounds, calcium hydroxide and calcium oxide are preferably used in consideration of the above characteristics and industrial use.

  In the present invention, the particle size of the alkaline earth metal compound used for the production of the silica sand is preferably 0.001 μm to 40 μm, more preferably 0.001 μm to 10 μm.

  The addition ratio of the alkaline earth metal compound to the silica sand is 0.1 to 10 parts by weight with respect to 100 parts by weight of the silica sand, and the strength of the resulting silica sand granule is increased and the silica sand granulation is performed. It is preferable from the point which makes the metal silicon manufactured from a body highly purified. More preferably, it is 0.3 to 3 parts by weight. Most preferably, it is 0.5 to 1.5 parts by weight. That is, it is sufficient that the alkaline earth metal compound is added in an amount sufficient to cover the surface of the silica sand, and use of an amount larger than that may cause an increase in the amount of impurities.

(Sugar)
The silica sand granule obtained by the production method of the present invention contains a saccharide that functions to enhance the dispersibility of an alkaline earth metal that acts as a binder for silica sand, thereby providing an extremely high strength silica sand granule. Can be configured.

In the silica sand granule obtained by the production method of the present invention, any known saccharide that acts as a dispersant for an alkaline earth metal compound can be used without particular limitation. Examples of saccharides that can be suitably used include monosaccharides, oligosaccharides, and sugar alcohols. Specific examples include monosaccharides such as glucose and fructose, oligosaccharides such as sucrose, maltose and lactose, and sugar alcohols such as glycerin and mannitol. Since alkaline earth metal compounds are easily dissolved in an aqueous solution of monosaccharides and oligosaccharides, the saccharides are more preferably monosaccharides and oligosaccharides. Among these, in consideration of industrial use, sucrose that is inexpensive and easy to handle is particularly preferably used. These improve the dispersibility of the alkaline earth metal compound, increase the reactivity between the alkaline earth metal compound and SiO _2, and contribute significantly to increasing the strength of the granulated body.

  Further, it is important that the saccharide content is 2 parts by weight or more, preferably 4 parts by weight or more. That is, when saccharides are smaller than 2 weight part, the dispersibility of the alkaline-earth metal compound as a binder falls, and it becomes difficult to obtain the quartz sand granule which has high intensity | strength. In order to increase the strength of the silica sand granule, the content of saccharide is preferably 6 parts by weight or less. This is because the content of saccharides exceeding 6 parts by weight increases viscosity, leads to poor granulation, and is often unsuitable for use as a raw material for metallic silicon. A suitable amount of such saccharides varies slightly depending on the molding method, but is generally 2 to 6 parts by weight with respect to 100 parts by weight of silica sand. The above ratio is determined by ease of molding, but sufficiently satisfies the amount necessary for dispersing the alkaline earth metal compound.

(water)
The amount of water is an amount necessary for curing the alkaline earth metal compound, and is appropriately determined in consideration of moldability in the molding method described later. A suitable amount of water varies depending on the molding method, but is generally 10 to 20 parts by weight with respect to 100 parts by weight of silica sand. The said ratio is determined by the ease of shaping | molding. If the amount of water is 10 parts by weight or more, it is sufficient for curing, and if it is 20 parts by weight or less, the fluidity of the mixture when molding a mixture containing cinnabar, saccharides, alkaline earth metal compound and water. Can be suppressed and leakage from the mold can be prevented.

(Mixing method)
In the method for producing a silica sand granule according to the present invention, the mixing order of the silica sand, alkaline earth metal compound, saccharide, and water is not particularly limited as long as they are uniformly mixed. However, it is more preferable to mix with other components in a state in which the saccharide is previously dissolved in water. By using water in which saccharides are dissolved, the dispersibility of the alkaline earth metal compound is remarkably improved, and it becomes possible to obtain a silica sand granule having a higher strength. Examples of a general mixing order are: a method in which silica sand and an alkaline earth metal compound are mixed, and then water in which the saccharide is dissolved by a method such as spraying or dripping is added to the resulting mixture; an alkaline earth metal compound and a saccharide Examples include a method of mixing slurry in which water dissolved in water and silica sand, a method in which three components of water in which silica sand, an alkaline earth metal compound, and saccharide are dissolved are mixed at the same time.

  The mixing method is shown in FIG. 9.1 on page 610 of a known mixing apparatus, for example, Powder Engineering Handbook (Edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). , Horizontal cylindrical mixer (with internal blades) V-type mixer (with stirring blades), double-conical mixer, and other container rotating mixers; ribbon mixer, conical screw mixer, high-speed fluid mixing Examples thereof include a container-fixed type mixer such as a mixing machine, a rotating disk type mixer, an airflow stirring type mixer, and a non-stirring type mixer; Further, when water is added and mixing is performed in a wet state, a kneading machine such as a powder engineering manual (edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun) 644 Various kneaders listed in Table 13.6 on page can also be used.

(Organic binder)
In addition, an organic binder can be added to the mixture of water in which the silica sand, the alkaline earth metal compound, and the saccharide are dissolved in order to improve the moldability within a range that does not significantly impair the effects of the present invention. Examples of the organic binder include carboxymethyl cellulose (CMC) and polyvinyl alcohol described in Tables 1, 3, and 4 of the granulation manual (edited by Japan Powder Industry Association, published on May 30, 1975, Ohmsha). (PVA), dextrose, corn syrup and the like. In addition to the above, binders made of organic materials that can be used include starches such as dextrin and corn starch; proteins such as glue, casein and soybean protein; natural rubbers such as gum arabic; Tars such as tar: Asphalts such as straight asphalt and blown asphalt; Thermoplastic resins such as acrylic polymer, polyamide, polyethylene, and other cellulose; Urea resin, melamine resin, phenol resin, furan resin, epoxy resin, thermosetting And thermosetting resins such as curable polyester and thermosetting polyurethane; and elastomers such as neoprene, nitrile rubber, styrene butadiene rubber, butyl rubber, and silicone rubber.

(Molding)
In the method for producing a silica sand granule according to the present invention, the molding method of the mixture containing the silica sand, alkaline earth metal compound, saccharide, and water is not particularly limited, and a known granulation method can be employed without limitation. . For example, among the methods classified in Part 1 and Sections 1 and 4 of Granulation Handbook (Edited by Japan Powder Industry Association, published on May 30, 1975, Ohmsha), compression mold, rolling mold, A general method of an extrusion mold can be suitably employed.

  Further, the shape of the granulated body obtained by molding is not particularly limited, but a cylinder, a polygon, and a polygonal column are more difficult to roll than a spherical shape, and are advantageous in terms of work. Also, in order to secure escape routes for CO and SiO gas generated in the arc furnace, the indefinite shape of the polygon is better than the spherical shape.

(Curing)
In the method for producing a silica sand granule according to the present invention, a molded body of a mixture containing silica sand, an alkaline earth metal compound, a saccharide, and water is cured by reacting the silica sand and the alkaline earth metal compound in the presence of water. By doing so, a silica sand granule can be obtained.

  In the curing, the curing temperature is preferably a temperature at which water can exist. In addition, the curing time varies somewhat depending on the type of alkaline earth metal compound and the curing temperature, and cannot be determined in general. For example, in the case of calcium hydroxide, it is preferable that the curing time be about several minutes to 7 days, and about several hours to 4 days is more preferable in order to obtain a stronger silica sand granule. Moreover, in curing, since the strength can be increased by maintaining the moisture content contained in the silica sand granule so as not to be lost more than necessary, curing in a humid atmosphere or in a sealed atmosphere It is also mentioned as a preferred embodiment that the curing is performed.

(Dry)
The silica sand granule obtained by curing the alkaline earth metal compound is capable of removing water contained as much as possible by a drying process. It is preferable because collapse due to rapid expansion can be prevented. Specifically, it is preferable to perform the drying at 1300 ° C. until the loss on ignition becomes 0.1 wt% to 3 wt%, particularly 0.1 wt% to 1 wt%.

  The drying treatment is preferably performed at a temperature of 70 ° C. or more, particularly 100 ° C. or more, and the upper limit of the temperature in the heat treatment is preferably a temperature in a range that does not significantly deteriorate the strength of the alkaline earth metal compound cured body. is there. In general, it is preferable to carry out so as to be 300 ° C. or lower, particularly 200 ° C. or lower.

  In addition, the said drying process can also perform this hardening reaction simultaneously, if the water required for hardening of an alkaline-earth metal compound can be ensured. And when water exists when performing the said drying process under the said heating, the hardening reaction by the said alkaline-earth metal compound is accelerated | stimulated, and the further improvement of the intensity | strength of the obtained granulated body can also be aimed at.

(Cotton sand granule)
When the silica sand granule obtained by the production method of the present invention is used as a raw material for metal silicon production, for example, as a raw material for metal silicon in an arc furnace, a cylinder or a polygon (rectangle) is used. Preferably, the longest side is 5 mm to 200 mm. That is, in use in the arc furnace, when one side of the quartz sand granule is less than 5 mm, a sufficient gap for gas to pass through the raw material layer in the arc furnace cannot be ensured, while granulation exceeding 200 mm. Manufacturing the body is disadvantageous in terms of cost and productivity. The above is preferably 5 mm to 150 mm, more preferably 30 mm to 150 mm, and still more preferably 50 mm to 150 mm.

  In addition, the silica sand granule is an extremely high silica sand granule by containing a saccharide that functions to enhance the dispersibility of the alkaline earth metal in the curing reaction with the alkaline earth metal that acts as a binder for the silica sand. Configured. The crushing load of the cinnabar granule is preferably 2000 N or more, and more preferably 3000 N or more. If it has a strength of 2000 N or more, it can be sufficiently used as a substitute for silica stone in the arc furnace.

(Manufacture of metal silicon, etc.)
The silica sand granule obtained by the production method of the present invention can be used for the production of silicon alloys such as metal silicon, ferrosilicon and silicomanganese, and silicon carbide, particularly for the production of metal silicon by an arc furnace. Preferably used.

  In the production of metallic silicon, for example, a silica sand granule, which is a silicon source, is used alone or in combination with silica stone, and charcoal, coke, coal, wood chips, etc. are mixed as a reducing material in an arc furnace. A method of reducing and melting is mentioned. In the arc furnace, the silicon source and the reducing material are sufficiently mixed so as not to segregate, and the necessary amount is charged. In the furnace, the vicinity of the tip of the electrode becomes the highest temperature due to arc discharge, and the silicon source is reduced by energizing so that the reached temperature is 1900 ° C. to 2000 ° C., and the metal silicon melt is collected at the bottom of the furnace. The metal silicon melt collected at the bottom of the arc furnace is extracted into a ladle by opening the spout by arc discharge or the like. By bubbling oxygen gas into the metal silicon melt, impurities such as calcium compounds are separated as slag (oxide) by the difference in specific gravity. Then, by removing all or part of the slag, a metallic silicon lump can be obtained.

  The arc furnace has a known structure and material as described in, for example, pages 47 to 55 of the silicon raw material research report (March 1983, Japan Electronics Industry Promotion Association). Used without any particular restrictions.

  In addition, as a manufacturing method of the said metallic silicon, the process which shape | molds silica sand and produces the silica sand granule whose average particle diameter is 5 mm-200 mm, and the siliceous sand granule are made into an arc as at least one part of a silicon source. An embodiment in which the step of supplying to the furnace and performing the reduction reaction is performed on site is also preferable.

  On the other hand, in the production of silicon alloys such as ferrosilicon and silicomanganese and silicon carbide, it is necessary to add a predetermined amount of a metal source other than silicon in the silicon alloy so as to have a desired composition. What is necessary is just to adjust suitably the quantity of carbon used as a reducing material and raw material, and to adjust suitably the injection | throwing-in method and reaction temperature of the raw material to the conditions suitable for manufacture of silicon carbide.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not restrict | limited to these Examples. In addition, the numerical value in an Example and a comparative example was measured by the method shown next.

(1) Strength of cinnabar granule From a columnar cinnabar granule obtained by the methods of Examples and Comparative Examples described later, a sample having a height of 1.9 cm to 2.3 cm is extracted. The crushing load (N) was measured with an autograph (Shimadzu precision universal testing machine AG-Xplus 50 kN). Cylindrical granules were placed vertically on the compressor and loaded in the vertical direction. The load was set to a speed of dropping 0.2 mm per minute.

  Furthermore, when using the obtained cinnabar granule for the production of metal silicon, assuming that it is heated in an arc furnace, a part of the granule obtained by the method of each Example and Comparative Example, It heated with the electric furnace and the crushing load (N) was measured by the above-mentioned method after a heating. Heating was performed in air and the heating temperature was 300 ° C or 800 ° C.

(2) Apparent density of cinnabar granule The height h (cm) and diameter 2r (cm) of the cylindrical cinnabar granule measured with calipers, and the weight of the cylindrical cinnabar granule weighed with an electronic balance The apparent density ρ was calculated from m (g) by the following formula.
ρ = m / (π · r ² · h)
(3) Average particle size of silica sand The particle size distribution (volume reference distribution) was measured in the range of 10 nm to 3000 μm with a laser diffraction / scattering particle size distribution measuring apparatus LA-950V2 manufactured by HORIBA, and the average particle size of silica sand was calculated. .

(4) SiO ₂ content and Na ₂ O content of silica sand Silica sand is mounted on a measurement jig, and elemental analysis is performed with fluorescent X-rays (fluorescence X-ray analyzer ZSX Primus II manufactured by Rigaku Corporation) to obtain SiO ₂ and Na _2. The O content was calculated.

(5) Relative Particle Amount of Silica Sand Using a decoration with an opening of 75 μm, an opening of 150 μm, and an opening of 1400 μm based on ISO 3301-1, the relative particle amount of 100 g of silica sand was determined. After confirming that the relative particle amount completely passes through the decoration of 1400 μm, the weight of the particles that passed through the 75 μm opening, and the weight of the particles that passed through the 150 μm opening and did not pass through the 75 μm opening, The weight of the particles that do not pass through the decoration having an opening of 150 μm was measured, and the weight was measured as a ratio (% by weight) when the whole was 100% by weight.

Example 1
Silica sand (average particle size 250 μm, SiO ₂ content 99.4 wt%, Na ₂ O content 0.0 wt%) was pulverized to an average particle size of 30 μm with a planetary ball mill. The crushed silica sand (average particle size 30 μm) and the unground crushed silica sand (average particle size 250 μm) were mixed in a weight ratio of 6: 4. The relative particle amount of the obtained cinnabar was as shown in Table 1. 1.0 part by weight of calcium hydroxide, 11.7 parts by weight of water, and 5.0 parts by weight of sucrose were mixed well in a mortar with 100 parts by weight of the silica sand whose particle size was controlled. The mixing was performed in the order of first preparing a sucrose aqueous solution of sucrose and water, then adding calcium hydroxide to the sucrose aqueous solution, and finally adding cinnabar sand. About 15 g of this mixture of cinnabar sand, calcium hydroxide, sucrose and water was weighed, put into a mold having an inner diameter of 20 mm, and pressure-molded at a pressure of about 6 MPa. The height after molding was 20 mm ± 2 mm. The cylindrical cinnabar molded body taken out from the mold was kept in a wet state and left at room temperature of 20 ° C. for about 1 day. Then, the drying process was performed for 2 hours at 150 degreeC using the ventilation dryer. The weight of the cylindrical cinnabar granule obtained was weighed, and the diameter and height were measured. Then, the apparent density was calculated from these values. Furthermore, the crushing load was measured. Moreover, after performing heat processing at 300 degreeC and 800 degreeC, the apparent density and the crushing load were measured similarly. The results are summarized in Table 2.

Example 2
A cinnabar granule was produced in the same manner as in Example 1 except that the amount of sucrose added was 2.5 parts by weight and the amount of water added was 14.2 parts by weight. The apparent density and crushing load of the obtained cinnabar granule are shown in Table 2.

Example 3
A cinnabar granule was produced in the same manner as in Example 1 except that the amount of sucrose added was 3.3 parts by weight and the amount of water added was 13.3 parts by weight. The apparent density and crushing load of the obtained cinnabar granule are shown in Table 2.

Comparative Example 1
By the same method as in Example 1, cinnabar sand having the relative particle amounts shown in Table 1 was obtained. 1.0 part by weight of calcium hydroxide and 16.7 parts by weight of water were mixed well in a mortar with 100 parts by weight of the silica sand whose particle size was controlled. The mixing order was such that calcium hydroxide and cinnabar sand were first mixed and then water was added. About 15 g of this mixture of cinnabar sand, calcium hydroxide and water was weighed, put into a mold having an inner diameter of 20 mm, and pressure-molded at a pressure of about 6 MPa. The height after molding was 20 mm ± 2 mm. The cylindrical cinnabar molded body taken out from the mold was kept in a wet state and left at room temperature of 20 ° C. for about 1 day. Then, the drying process was performed for 2 hours at 150 degreeC using the ventilation dryer. The apparent density and crushing load of the obtained cinnabar granule were measured. Moreover, after performing heat processing at 300 degreeC and 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 2.

  In Comparative Example 1, sucrose is not added.

  Example 1 and Example 2 in which sucrose was added as a saccharide showed higher strength than the comparative example in which no saccharide was added, and the crushing load was 2000 N or more, which is sufficient for substitution for meteorite. Moreover, when sucrose was added, even if it heated at high temperature of 300 degreeC or 800 degreeC, the crushing load was 2000 N or more, and it has confirmed that it was possible enough for substitution of a meteorite.

Example 4
By the same method as in Example 1, cinnabar sand having the relative particle amounts shown in Table 1 was obtained. 1.0 part by weight of calcium hydroxide, 14.2 parts by weight of water, and 2.5 parts by weight of glucose were mixed well in a mortar with 100 parts by weight of cinnabar with controlled particle size. The mixing order was as follows: first, an aqueous glucose solution of glucose and water was prepared, then calcium hydroxide was added, and finally, cinnabar was added. About 15 g of this mixture of cinnabar sand, calcium hydroxide, glucose and water was weighed, put into a mold having an inner diameter of 20 mm, and pressure-molded at a pressure of about 6 MPa. The height after molding was 20 mm ± 2 mm. The columnar granule taken out from the mold was kept in a wet state and left at room temperature of 20 ° C. for about 1 day. Then, the drying process was performed for 2 hours at 150 degreeC using the ventilation dryer, and the apparent density and crushing load of the obtained cinnabar granule were measured. Moreover, after performing heat processing at 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 3.

Example 5
A cinnabar granule was prepared in the same manner as in Example 4 except that the amount of glucose added was 5.0 parts by weight and the amount of water added was 11.7 parts by weight. Density and crush load were measured. Moreover, after performing heat processing at 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 3.

Example 6
A cinnabar granule was produced in the same manner as in Example 4 except that the saccharide was changed to fructose, and the apparent density and crushing load of the obtained cinnabar granule were measured. Moreover, after performing heat processing at 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 3.

Example 7
A cinnabar granule was produced in the same manner as in Example 5 except that the saccharide was fructose, and the apparent density and crushing load of the obtained cinnabar granule were measured. Moreover, after performing heat processing at 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 3.

Example 8
A cinnabar granule was produced in the same manner as in Example 4 except that the saccharide was maltose, and the apparent density and crushing load of the obtained cinnabar granule were measured. Moreover, after performing heat processing at 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 3.

Example 9
A cinnabar granule was produced in the same manner as in Example 5 except that the saccharide was changed to maltose, and the apparent density and crushing load of the obtained cinnabar granule were measured. Moreover, after performing heat processing at 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 3.

Example 10
A cinnabar granule was produced in the same manner as in Example 4 except that the saccharide was changed to lactose, and the apparent density and crushing load of the obtained cinnabar granule were measured. Moreover, after performing heat processing at 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 3.

Example 11
A cinnabar granule was produced in the same manner as in Example 5 except that the saccharide was changed to lactose, and the apparent density and crushing load of the obtained cinnabar granule were measured. Moreover, after performing heat processing at 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 3.

Example 12
A cinnabar granule was produced in the same manner as in Example 4 except that the saccharide was changed to glycerin, and the apparent density and crushing load of the obtained cinnabar granule were measured. Moreover, after performing heat processing at 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 3.

Example 13
A cinnabar granule was produced in the same manner as in Example 5 except that the saccharide was changed to glycerin, and the apparent density and crushing load of the obtained cinnabar granule were measured. Moreover, after performing heat processing at 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 3.

Example 14
A cinnabar granule was produced in the same manner as in Example 4 except that the saccharide was changed to mannitol, and the apparent density and crushing load of the obtained cinnabar granule were measured. Moreover, after performing heat processing at 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 3.

Example 15
A cinnabar granule was produced in the same manner as in Example 5 except that the saccharide was changed to mannitol, and the apparent density and crushing load of the obtained cinnabar granule were measured. Moreover, after performing heat processing at 800 degreeC, the apparent density and the crushing load were measured similarly. The results are shown in Table 3.

  The silica sand granule of the present invention can be effectively used for the production of metal silicon, silicon alloys such as ferrosilicon and silicomanganese, and silicon carbide as an alternative to silica.

Claims (4)

  Silica sand granule characterized by granulating a mixture containing 2-6 parts by weight of saccharide, 0.1-10 parts by weight of alkaline earth metal compound and 10-20 parts by weight of water with respect to 100 parts by weight of silica sand Manufacturing method.   As the silica sand, the particle size of all particles is 1400 μm or less, the relative particle amount (weight) having a particle size of 75 μm or less is 25 to 85%, the particle size is over 150 μm, and the relative particle amount (weight) is in the range of 1400 μm or less. The method for producing a quartz sand granule according to claim 1, wherein the silica sand is 0% to 50% (however, the relative particle amount of 1400 µm or less is 100%).   The method for producing a quartz sand granule according to claim 1 or 2, wherein the saccharide is selected from monosaccharides and oligosaccharides.   The method for producing a quartz sand granule according to any one of claims 1 to 3, wherein the saccharide is mixed in advance with other components in a state of being dissolved in water.