JP2013006711A - Method for producing silica sand granulated body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for continuously producing a silica sand granulated body having the particle size handleable similarly to silica in order to replace silica which is usually used as a raw material when producing a metallic silicon.SOLUTION: When feeding the silica sand and a binder to a tumbling granulator to produce the silica sand granulated body, at least two tumbling granulators are prepared. The particle-grown intermediate granules are taken out so that the ratio of the granules having the particle size of ≥20 mm becomes ≤30 wt.% in the granules existing in a first stage tumbling granulator, and in the next stage tumbling granulator, the silica sand and binder are fed to the intermediate granule, and further particle growth is performed to obtain the silica sand granulated body.

Description

  The present invention relates to a novel method for producing a silica sand granule by rolling granulation. Specifically, the present invention provides a method for continuously and efficiently producing a quartz sand granule having a relatively large particle size of an average particle size of 20 mm or more, particularly 30 to 200 mm, and further about 30 to 100 mm. .

  In general, the production of metal silicon uses silica as a silicon source as a raw material, and charcoal, coke, coal, wood chips, etc. as a reducing material, and a mixture of these is filled as a raw material layer in an arc furnace, 2300-2800K It is performed by heating at a high temperature and reducing silica (see Non-Patent Document 1).

In order to ensure the air permeability in an arc furnace, the said silica stone normally uses a 30-200 mm average particle diameter suitably. That is, the reduction reaction of silicon dioxide (SiO ₂ ), which is the main component of silica in the arc furnace, generally proceeds according to the following equation (1), and in the course of the reduction reaction, carbon monoxide as a gas phase (CO) gas and silicon monoxide (SiO) gas are generated, and all or a part of them must be released from the exhaust port at the top of the arc furnace through the raw material layer.

SiO ₂ + 2C → Si + 2CO (1)
In fact, 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)
In general production conditions for producing metal silicon, the condensed phase in the arc furnace temperature range is SiO ₂ , C, SiC, Si, and the gas phase is CO, SiO. SiO gas is generated from the high temperature part near the tip of the electrode in the furnace by the reaction of the formula (2). In the upper raw material layer, the generated SiO gas or CO gas rises through the gap between the raw materials and is discharged. At this time, deposits adhere to the passage by the following reaction.

3SiO + CO → SiO 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 to replace quartz stone as a raw material for metallic silicon. However, when silica sand is directly used as the raw material, the space is reduced when filled in the arc furnace, compared to silica stone, and when deposits are generated by the reaction of the above formulas (10) and (11), the space is further reduced. I will let you. For this reason, it is feared that it will be difficult to escape the gas of CO or SiO that is subsequently produced. As can be seen from the above formulas (2) to (8), if the CO stays, the progress of the reaction is inhibited. That is, SiC is deposited on the bottom of the furnace and causes operational troubles.

  To solve the problem when using the silica sand as a raw material, a method of granulating the silica sand to a predetermined size and using it can be considered.

  Generally, a rolling granulation method is known as a method for producing a granulated body from powder. In this method, the liquid film existing in the gap between the powder particles is brought into contact by rolling, and the surface tension of the liquid film is attracted to the distance at which various bonding forces of the powder itself can act. A granulated body is formed by a mechanism in which a simple bond is formed. Therefore, the granulated material obtained by the rolling granulation method has a relatively high compressive strength as compared with other granulation methods such as compression granulation method, stirring granulation method, extrusion granulation method and the like. Is considered to be useful as a substitute for the silica.

  Conventionally, there is no literature that attempts to granulate silica sand by the rolling granulation method, but according to the experiments by the present inventors, in order to ensure air permeability in the arc furnace by rolling granulation. It is difficult to continuously produce a preferred size, for example, an average particle size of about 30 to 200 mm. That is, even if the silica sand and the binder are continuously supplied to the rolling granulator and the silica sand granule having the above-mentioned size is continuously taken out, the granulated body continues in the granulator. And the particle size only increased. Therefore, when the silica sand granule becomes a predetermined size, it is necessary to stop the granulator once, take out the silica sand granule, and then start granulation again. The problem was that it was extremely inefficient.

  In addition to the production of silica sand granules, when forming zirconia powder by the rolling granulation method, a granulation body having a particle size of 2 mm or less is produced in advance by stirring granulation, and this is used as a rolling granulator. It is disclosed that a zirconia sphere can be efficiently produced by forming a granulated body of 20 mm or less (see Patent Document 1).

  However, the nuclei obtained by the agitation granulation of the above method have low strength, and in the process of growing into a large particle size granule, the core may be destroyed, and the small particle size granule piece increases. In particular, the silica sand targeted by the present invention is particularly concerned about the significant destruction of the nucleus.

JP-A-6-170206

Industrial Heating, Vol. 46, No. 3, (2009), p. 1-11, “Current Status and Issues of Small Arc Furnace”, written by Ando et al.

  Accordingly, an object of the present invention is to use a tumbling granulator to include a granulated body having a particle size of more than 20 mm, and in particular, a relatively large silica sand granule having an average particle size of about 30 to 100 mm. The object is to provide a method capable of continuously producing a body.

  As a result of intensive research to solve the above-mentioned problems, the present inventors, in the rolling granulation of silica sand, after the granulated body having grown to a specific size, It was found that even when further supplying is added, it becomes difficult to produce and grow grains as cores, and only the grain growth of the existing granulated body proceeds, so that continuous production becomes difficult. And based on this knowledge, when producing a silica sand granule by rolling granulation, the granulation process is divided into two or more stages, and in the first stage rolling granulator, the grains grow to the specific size. The granulated body is taken out, the ratio of the granulated body in the rolling granulator is limited to a specific value or less, and the granulated body (intermediate granulated body) taken out above is separately prepared and subsequent stages It has been found that by growing to a desired particle size in a rolling granulator, a target silica sand granule having a relatively large particle size can be continuously produced, and the present invention has been completed.

  That is, the present invention provides at least two rolling granulators when supplying silica sand and a binder to a rolling granulator to produce a quartz sand granulated body. Take out the intermediate granulated particles so that the proportion of the granulated particles having a particle size of 20 mm or more in the granulated particles in the machine is 30% by weight or less. A method for producing a silica sand granule is characterized in that silica sand and a binder are supplied to the intermediate granule to further grow the particles to obtain a silica sand granule.

  In the present invention, the particle size of the granulated body indicates the major axis of the particle. The average particle diameter is a value calculated as an arithmetic average of the particle diameters obtained by sampling 50 randomly extracted granules.

  According to the present invention, a silica sand granule having a particle size exceeding 20 mm, in particular, a silica sand granule having an average particle size of 30 to 200 mm, and further 50 to 150 mm is continuously and stably produced by a rolling granulator. It becomes possible to do.

(Silica sand)
The silica sand used in the present invention is not particularly limited, but a powdery material having an SiO ₂ content of 90% by weight or more and an average particle diameter of 1000 μm or less is preferably used. In particular, considering that it is used as a raw material for the production of metal silicon, the smaller the impurities in the silica sand, the better. The SiO ₂ content is preferably 94% by weight or more, more preferably 99% by weight or more, and 99.5% by weight. Is most preferred. In particular, it is preferable to use high-purity silica sand that contains few impurities in the silica sand because the impurity content remaining in the obtained silicon can be effectively reduced. 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.

Silica sand is pulverized as necessary, and it is effective to increase the granulation property by using an average particle diameter of 1000 μm or less, preferably 200 μm or less, and more preferably 150 μm or less. However, excessively pulverizing silica sand not only requires a lot of energy for pulverization, but also involves contamination due to contact with the pulverizer. Therefore, it is preferable to adjust the particle size of the silica sand so that the average particle size is 5 μm or more, preferably 20 μm or more, and more preferably 50 μm or more.
Further, by reducing the particle size of the silica sand, the silanol groups on the particle surface increase, and accordingly, the interparticle bonding force in the granule structure tends to increase, but particularly preferably 5 μm or more, particularly in the present invention. When the average particle diameter of 20 μm or more, further 50 μm or more and a relatively large average particle size is set as the lower limit, if this is normally granulated with the above-described rolling granulator, the generation of nuclei, which is the subject of the present invention, Since the phenomenon that it hardly occurs is likely to occur, the present invention is particularly effective when using silica sand having such a particle size.

  In the present invention, the method for pulverizing the silica sand as necessary so as to obtain the silica sand having the average particle diameter can be carried out using a known pulverizer. For example, a powder mill handbook (powder engineering society, issued on February 28, 1986, Nikkan Kogyo Shimbun) screw mills described in Tables 1 and 10 on pages 503 to 505; represented by stamp mills High-speed rotary impact crusher such as disc mill, pin mill, screen mill, hammer mill, centrifugal classification mill; Roll rolling type such as roller mill; Ball such as ball mill, vibrating ball mill, planetary crusher Medium mill; tower-type pulverizer, stirring tank type, flow tube type, annular type, etc .; As the pulverizer specifically used, less energy is required for pulverization, and less impurities are preferably mixed during pulverization. For example, a ball media mill such as a ball mill, a vibration ball mill, a planetary pulverizer, a tower pulverizer, A pulverizer using pulverization balls such as a medium agitation pulverizer such as a stirring tank type, a flow tube type, and an annular type is suitably used.

(binder)
The binder used in the present invention is not particularly limited as long as it is a binder that can be used for rolling granulation of silica sand, and known ones can be used. Examples of such a binder include solvents such as water and organic solvents, inorganic binders, and organic binders. Each of these binders can be used alone, but it is preferable to use a solvent in combination with an inorganic binder and / or an organic binder, and it is more preferable to use water as the solvent.

  Examples of inorganic binders that can be used include Portland cement, blast furnace cement, silica cement, alumina cement, fly ash, white cement, jet cement and the like; anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, waste Gypsum such as smoke desulfurization gypsum; sodium silicate 1, 2, 3, 4; water glass such as metasilicic acid; minerals such as clay and bentonite; calcium compounds such as calcium oxide, calcium hydroxide and calcium carbonate Can be mentioned.

  Examples of organic binders that can be used include starches such as dextrin, corn starch, and starch; proteins such as glue, casein and soybean protein; natural rubbers such as latex and gum arabic; pitch, Tars such as processed tar and pavement tar; Asphalts such as straight asphalt and blown asphalt; Thermoplastic resins such as vinyl, polyvinyl alcohol, acrylic, polyamide, polyethylene, and cellulose; Yulia, melamine, phenol, furan, epoxy, polyester And thermosetting resins such as polyurethane; and elastomers such as neoprene, nitrile, styrene, butyl, and silicone.

  Among the inorganic binders and organic binders, the inorganic binder is preferable in that the effect does not disappear even in a high temperature range where the silica sand granule is required to maintain strength. Above all, the calcium compound has the function of strengthening the granule in the low temperature range based on the adhesiveness due to water absorption, and also has the function of strengthening the granule as a sintering aid by reacting with the silica by heating. The strength can be maintained, and it can be particularly preferably used in the method for producing silicon using the arc furnace.

  Hereinafter, although the aspect which uses a calcium compound as a binder is demonstrated in detail, the usage aspect can be suitably determined also about another binder based on a well-known usage method.

  The calcium compound preferably has a particle diameter of 0.001 to 20 μm. More preferably, it is 0.001-10 micrometers. Further, even if the calcium compound particles are aggregated, a part or all of the aggregates can be unraveled in the mixing process described later, so that they can be used.

  Further, the addition ratio of the calcium compound is desirably 0.1 to 5 parts by weight with respect to 100 parts by weight of silica sand, and more preferably 0.5 to 3 parts by weight. By the way, it turns out that this amount is quite small compared with the amount of calcium compounds in cement clinker. In the present invention, the purpose is to bring the calcium compound into contact with the surface of the silica sand. In other words, it is sufficient to add a calcium compound that only covers the surface of the silica sand, and the amount used can be kept low. And since the addition amount of a calcium compound can be restrained small in this way, it brings about the effect that the purity fall of the metal silicon manufactured using this as a raw material can also be suppressed.

(Rolling granulator)
In the present invention, a known rolling granulator is used as the rolling granulator used for granulation without any limitation. For example, the drum-type granulator and dish-type granulator described in Section 2, 2.6 of the granulation manual (Japan Powder Industry Association, published on May 30, 1975, Ohmsha) It can be adopted and implemented.

  Among these, a dish-type granulator is preferably used because it is easy to control the granulation process. The dish shape of the dish-type granulator includes ordinary dish type (basket type), multi-stage dish type, spherical dish type, truncated cone type, etc., but multi-stage dish type, spherical dish type, truncated cone type, etc. Since the granulator automatically classifies the granulated material according to the difference in centrifugal force because the radius of rotation differs along the rotation axis, the granulated material having a uniform particle size is grown from the outer peripheral side of the rotating dish. Suitable for selective removal.

  In the rolling granulation of the present invention, the operation of supplying the silica sand and the binder to the rolling granulation apparatus can be carried out without any particular limitation on the operation performed in the known rolling granulation. For example, the supply of silica sand is carried out using the feeders classified in Table 5.1 on page 567 of the Powder Engineering Handbook (Edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). However, it is preferable to use a vibration feeder, a shaking feeder or a screw feeder in terms of easy control of the supply amount. Similarly, it is preferable to use a vibration feeder, a shaking feeder or a screw feeder for supplying the binder. Furthermore, it is also preferable that silica sand and a binder are mixed in advance and simultaneously supplied using a vibration feeder, a shaking feeder, a screw feeder or the like. Supply of the said silica sand and a binder can be performed continuously or intermittently.

  Moreover, what is necessary is just to determine suitably the quantity of the binder used at the time of granulation according to a well-known method. For example, when water is used as the binder, the amount is classified in Table 8.3 on page 599 of Powder Engineering Handbook (Edited by Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). It is preferable to add so as to be a policy area in the structure of the solid, liquid, and gas system (hereinafter referred to as the filling area). This is because when the filling area is in the policy area, water intervenes between the particles and acts as a crosslinking liquid. The filling area is affected not only by the ratio of water added to the silica sand but also by the particle size of the silica sand. It can function as a crosslinking liquid.

  Moreover, when using solid binders other than solvents, such as water, it is suitable that the addition amount shall be 5-20 weight part with respect to 100 weight part of silica sand.

(Rolling granulation)
A feature of the method for producing a quartz sand granule according to the present invention is that at least two rolling granulators are prepared, and the ratio of the granule having a particle diameter of 20 mm or more present in the first stage rolling granulator. However, it is to take out the intermediate granulated product that has been grain-grown so as to be 30% by weight or less, preferably 20% by weight or less, more preferably 15% by weight or less.

That is, by performing granulation so that the ratio of particles of 20 mm or more existing in the first-stage rolling granulator is within the above range, the rolling granulator continuously (intermittently). (Including the operation of supplying to a new silica sand and a mixture of binders), new core formation and grain growth occur, and the number of granulated bodies can be reliably increased in the rolling granulator. .
In the first stage rolling granulator, the method of adjusting the ratio of the granulated body having a particle size of 20 mm or more present in the rolling granulator within the above range is the first stage rolling granulator. What is necessary is to carry out by selectively and continuously taking out the grains having grown more. Specifically, in the rolling granulator, the granulated body that has grown is present on the outer peripheral portion of the rotating dish, and therefore a granulated body (intermediate granulated body) of a predetermined size is provided in this portion. The method of taking out is implemented suitably.

  In addition, as above-mentioned, taking out of the intermediate granulated body from the first stage rolling granulator lowers the proportion of the granulated body having a particle size of 20 mm or more present in the rolling granulator. However, if the particle size of the granulated material present in the granulator is taken out in an excessively small state, the granulated material that has undergone grain growth is used when further grain growth is performed in the subsequent rolling granulator. There is a concern that the intermediate granule may be destroyed by the granule, and the production efficiency per unit granulator may be lowered, so that the average particle size is 10 mm or more, particularly 15 mm or more, and further 20 mm. It is preferable to take out the granulated body (intermediate granulated body) having undergone grain growth. In addition, when the particle size of the intermediate granulated material taken out from the first-stage rolling granulator is too large, the ratio of the granulated material of 20 mm or more in the granulator exceeds the above range, so the average particle size is 30 mm. Hereinafter, it is preferable to take out a granulated body of 25 mm or less.

  Incidentally, the conditions for taking out the granule of the specific size described above are the conditions for taking out the 20 mm granule in the above range by experiment in advance, preferably such that the average particle size of the intermediate granule is in the above range, For example, the inclination of the cone of the rolling granulator, the number of rotations, etc. may be set.

  In the present invention, the intermediate granule taken out from the first-stage rolling granulator is supplied to the subsequent-stage rolling granulator, where further, silica sand and a binder are added to grow grains. To obtain a silica sand granule having an average particle size of 20 mm or more, particularly 30 to 200 mm, and more preferably 30 to 100 mm.

  That is, in the present invention, the average particle diameter of the finally produced silica sand granule is less than 20 mm, the handleability is poor, and sufficient voids for the gas to pass through the raw material layer in the arc furnace cannot be secured, On the other hand, producing a granulated body having an average particle size exceeding 200 mm is disadvantageous in terms of cost and productivity.

(Heat treatment of granulated body)
The silica sand granule obtained by the production method of the present invention is preferably subjected to heat treatment in order to enhance the strength increasing effect. Such heat treatment temperature is preferably 100 to 1600 ° C, more preferably 700 to 1400 ° C. This can have two effects. The first is the action of the reaction between the calcium compound and the silanol groups on the silica sand surface. Another possibility is that the sintering reaction proceeds in addition to the surface reaction. The latter action is presumed to be exhibited in a treatment at 700 ° C. or higher. Moreover, a drying process can also be given at the temperature of 100-200 degreeC in order to evaporate a water | moisture content before heat processing.

  As the apparatus used for the heat treatment, for example, the furnace described in Section 5.1 of the ceramics operation (Ceramics Reading Book Variety Committee, published on September 20, 1973, Ceramic Industry Association) is employed. be able to. Specific examples include discontinuous kilns of flame-extinguishing type angle kilns, flame-extinguishing type round kilns, shuttle kilns and bell kilns; wheel kilns, continuous chamber kilns, continuous kilns of tunnel kilns; It is done. For drying, for example, a box-type dryer or rotary dryer classified on page 591 of the Powder Engineering Handbook (Edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun) is preferably used. it can. As for the heat treatment and drying atmosphere, an oxidizing gas such as oxygen or an inert gas such as nitrogen can be used, but an air treatment is sufficient.

  The above heat treatment can be performed in a dryer or kiln as described above, but when the rolling granulator has a heating function, granulation and heat treatment are performed simultaneously. May be.

(Use of granulated material)
The use of the silica sand granule obtained by the method of the present invention is not particularly limited and can be used for a known application. In particular, in the production of metal silicon, ferrosilicon, and silicon carbide, at least the silicon source is used. It can be suitably used as a part. Among these, it is particularly preferable to use it as a silicon source for metallic silicon.

  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. The arc furnace is thoroughly mixed so as not to segregate, and the required amount is charged. In the furnace, the tip of the electrode becomes the highest temperature due to arc discharge, and the silicon source is reduced by energizing so that the ultimate temperature is 2300-2800K, 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 with oxygen gas or the like. In the process of solidifying the metal silicon melt, impurities are separated as slag by the difference in specific gravity. By removing all or part of the slag, a high-purity metallic silicon mass can be obtained. An arc furnace having 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 limitation.

  In the case of manufacturing ferrosilicon or silicon carbide, the former requires adding a predetermined amount of iron source so as to have a desired composition. In the latter, as shown in the above formula (4), the reducing material is made of carbon. A large amount is added so that the molar equivalent is 3 times or more that of silica. Of course, the heating temperature also needs to be adjusted according to the object.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not restrict | limited to these Examples.

Example 1
99 kg of silica sand having an average particle diameter of 100 μm and 1 kg of Ca (OH) ₂ were mixed using a rotary ball mill. The produced raw material powder was supplied at a rate of 1 kg / min to the truncated cone type granulating dish type granulator (cone type granulator) of FIG. 1 by a belt conveyor. Simultaneously, water was supplied at a supply rate of 0.2 kg / min, and rolling granulation was performed under the condition of a cone rotation speed of 18 rpm.
When the granulation was performed under the condition that the ratio of the granulated body of 20 mm or more in the rolling granulator was 12% by weight by adjusting the inclination angle of the rolling granulator, the average particle size from the rolling granulator An intermediate granulated body having a diameter of 15 mm could be taken out and continuous granulation was possible.

  The granulated body (intermediate granulated body) produced by the first-stage granulator was taken out by capturing with a guide what jumped out of the apparatus by centrifugal force.

  Next, the intermediate granule taken out from the first-stage rolling granulator was guided to the second-stage granulator and supplied as a raw material.

  In the second stage rolling granulator, each raw material is supplied under the conditions of 0.1 kg / min of the intermediate granulated material, 1 kg / min of the raw material powder supply rate, and 0.2 kg / min of water, and a cone angle of 18 rpm. Rolling granulation was performed by adjusting the inclination angle to an angle at which a granulated body having a desired particle diameter was obtained. From the second-stage rolling granulator, it was confirmed that a granulated body having an average particle diameter of 30 mm could be continuously taken out and continuous granulation was possible.

Example 2
In Example 1, except that the supply speed of the intermediate granulated body in the second stage rolling granulator was 0.03 kg / min, and the inclination angle was changed to an angle at which a granulated body having a target particle diameter was obtained. Granulation was performed under the same conditions. As a result, a granulated body having an average particle diameter of 40 mm could be continuously granulated.

Example 3
In Example 1, in the second-stage rolling granulator, the supply rate of the intermediate granulated body is 0.01 kg / min, except that the inclination angle is changed to an angle at which a granulated body having a target particle diameter is obtained. Granulation was performed under the same conditions. As a result, a granulated body having an average particle diameter of 80 mm could be continuously granulated.

Example 4
Granulation was performed under the same conditions as in Example 2, except that the raw material powder was 97.5 kg of silica sand and 2.5 kg of Ca (OH) ₂ . As a result, a granulated body having an average particle diameter of 40 mm could be continuously granulated.

Example 5
Granulation was performed under the same conditions as in Example 2, except that the raw material powder was 99 kg of silica sand and 1 kg of carboxymethyl cellulose (CMC). As a result, a granulated body having an average particle diameter of 50 mm could be continuously granulated.

Comparative Example 1
In the first stage granulation of Example 1, the inclination angle of the tumbling granulator was changed, and the particle size of the granulated body taken out from the tumbling granulator was intended to be the desired size in one stage. In the tumbling granulator, the proportion of the granulated material having a particle size of 20 mm or more is 35% by weight, and even if the raw material is continuously supplied in this state, the number of particles does not increase and the granulated material has grown. However, the ratio of the granulated body of 20 mm or more was increased in the granulator without jumping out of the apparatus by centrifugal force, and continuous granulation was impossible.

Claims (2)

When supplying silica sand and binder to a rolling granulator to produce a silica sand granulated body, at least two rolling granulators are prepared, and the granulation existing in the first rolling granulator In the body, the intermediate granule that has been grain-grown is taken out so that the ratio of the granule having a particle size of 20 mm or more is 30% by weight or less, and the intermediate granulation is performed with a rolling granulator in the next stage. A method for producing a silica sand granule, characterized in that silica sand and a binder are supplied to the body to further grow the grains to obtain a silica sand granule. The method for producing a quartz sand granule according to claim 1, wherein the average of the intermediate granule taken out from the first-stage rolling granulator is 10 mm or more.