JP4251723B2 - Crushed stone by-product processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In a crushed stone plant, muddy water cake and stone powder are generated as a crushed stone by-product containing silica (SiO ₂ ), and it is necessary to treat and dispose of them. The present invention is capable of obtaining a high-quality solidified product by treating a muddy water cake and stone powder, both of which are crushed stone byproducts, and a raw material mixture mixed with a calcium compound, and a muddy water cake and dry powder having too much water. By using together with this stone powder, it is possible to effectively reduce the waste, and it is possible to reduce the manufacturing cost by eliminating the cost of adjusting the water content of the muddy water cake. The present invention relates to a method for treating crushed stone by-products.
[0002]
[Background Art and Problems to be Solved by the Invention]
As is well known, a crushed stone plant produces crushed stone and crushed sand for roads and buildings, and is mostly constructed in mountainous areas. In general, in a crushed stone plant, stones of about 1m size blasted at a quarry are put into a raw material factory (crushing chamber) in the upstream part of the plant, crushed by a crusher, and sieved according to the particle size of the crushed stone. For non-standard large crushed stones, crushing and sieving and sorting are repeated, and finally crushed stones and crushed sand that have been crushed and sorted by standard particle size are shipped as products. Fine aggregates with a particle size of 5 mm or less ( Sand production facilities that produce (crushed sand) are installed in the downstream part of the plant.
[0003]
In the sand making facility of the crushed stone plant, the crushed product is washed with water in order to remove adhering mud and unnecessary fine stone particles for the purpose of improving product quality. In particular, in concrete fine aggregate (crushed sand), the content of fine stone particles of 75 μm or less contained in the product is limited. For the production of fine aggregate, the fine stone particles are removed. The crushed product having a particle size of 5 mm or less is washed with water. Wash water after use in a wet facility for performing this water wash is muddy water containing about 5 to 10% by weight of fine stone particles or / and mud of about 75 μm or less, and is called “turbid water”. . Then, the muddy water is concentrated and dehydrated from the water and the separated mud using a thickener and filter press or other mechanical or dehydrating machinery or settling basin equipment to form a dehydrated cake containing moisture. Such dewatered cake by muddy water treatment is called “turbid water cake”. For example, when producing fine aggregate (crushed sand) for concrete, about 10% of sand production is generated by weight.
[0004]
Next, stone powder (dry stone powder) will be described. In the sand making facility, a crushed product having a particle size of 5 mm or less is classified by a dry classifier such as an air separator in order to remove the fine stone particles of 75 μm or less, and then the fine stone particles remaining without separation are removed. Some facilities employ a sand making process in which removal is performed by washing with water. In such a sand making process, fine stone particles of 75 μm or less are mainly generated as a by-product by classification with the air separator or the like. These fine stone particles are called stone powder (dry stone powder).
[0005]
In addition, the upstream part of the sandmaking facility in the crushed stone plant is equipped with a crusher and a sieve device for producing crushed stone according to particle size as described above, and in these devices, the dust collection collected by the dust collector. Stone powder (dry stone powder) that is fine stone particles (particle size: average 15 μm) is generated as a by-product as dust.
[0006]
In this way, the crushed stone plant generates muddy water cake and stone powder which are crushed stone by-products. In order to reduce waste from the viewpoint of environmental conservation, muddy water cakes are conventionally used (utilized) as low-strength materials such as landfill materials and embankment materials by simply mixing them with quicklime and cement. . However, in this muddy water cake processing method, the product strength (uniaxial compressive strength) obtained is as low as about 10 kg / cm ² or less, and the use is limited to low-strength materials such as landfill materials and embankment materials, and is always stable. In fact, there is no large amount of demand, and the expansion of usage cannot be expected. In addition, stone powder has been developed to be used (utilized) as a substitute for limestone powder, which is a mixture of high-fluidity concrete, but it has no other use and is essentially waste. It is the actual situation.
[0007]
For this reason, it is conceivable to develop a high-quality solidified product that can be used as a raw material such as a fine aggregate for concrete, which uses a muddy water cake or stone powder as a starting material, and whose demand is constantly stable. In this case, it is necessary to adjust the moisture for reducing the moisture of the muddy water cake with excess moisture supplied from the crushed stone plant. To adjust the water content of a muddy water cake with too much water, (1) a method using a dehydrator such as a filter press and / or a dryer such as a drum dryer, (2) a method using sun drying (sun drying), etc. Although it can be considered, the former method requires a large amount of equipment and operating costs for the dehydrator or dryer, and the latter method requires a long time to dry the muddy water cake. There is a problem that it is costly to maintain. In such a background, the present inventors have devised the present invention by paying attention to using a muddy water cake having too much water and stone powder as dry powder together.
[0008]
The present invention provides a turbid water cake and stone powder, both of which are crushed stone by-products, and a raw material mixture in which a calcium compound is mixed, whereby a high-quality solidified product can be obtained, and a turbid water cake and dry powder having too much water. By using together with this stone powder, it is possible to effectively reduce the waste, eliminate the need to adjust the water content of the muddy water cake, and reduce the manufacturing cost. The object is to provide a by-product processing method.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the method for treating crushed stone by-products according to the present invention includes a raw material mixing step for obtaining a raw material mixture obtained by mixing muddy water cake and stone powder, both of which are crushed stone by-products, and a calcium compound, and press-molding the raw material mixture. And a hydroforming step of obtaining a solidified product by solidifying the solidified product base by hydrothermal treatment.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the crushed stone by-product processing method according to the present invention having the above-described features, first, a raw material mixing step for forming a raw material mixture is performed. The raw material mixture produced in this step is a solidified product through a pressure molding step and a hydrothermal solidification step, which will be described later, and has a water content of 5 to 35 weight from the viewpoint of pressure moldability and solidified product strength. % Thing is good. The reason for this is that when the moisture content exceeds 35% by weight, the properties of the raw material mixture are too weak, and in the next pressure molding step, the pressure moldability is poor, such as escaping from the mold, and pressure cannot be applied. This is because a dense molding effect cannot be obtained, and a high-strength solidified product cannot be obtained even by hydrothermal treatment. On the other hand, if it is less than 5% by weight, the strength of the solidified product obtained by hydrothermal treatment in the subsequent process is low, and the strength generally required for fine aggregates for concrete and building blocks that are promising high-strength materials for use. This is because (uniaxial compressive strength: 150 kg / cm ² (14.7 MPa) or more) cannot be achieved.
[0011]
Therefore, in the raw material mixing step, if the water content of the muddy water cake from the crushed stone plant is too much and the water content of the mixture supplied to the pressure forming step as it is exceeds the upper limit of 35% by weight, By using, moisture adjustment is performed so that the moisture content of the raw material mixture obtained by mixing muddy water cake, stone powder and calcium compound satisfies the range of 5 to 35% by weight. Moreover, although the said range of 5 to 35% by weight is satisfied, when the muddy water cake from the crushed stone plant has too much moisture and the workability is poor at the time of mixing, it is difficult to mix them, so the work at the time of mixing can be performed by using stone powder. Property can be improved.
[0012]
Examples of the calcium compound used in the raw material mixing step include calcium oxide (quick lime), calcium hydroxide (slaked lime), and cement. The addition of such a calcium compound is to generate calcium silicate (calcium silicate) such as tobermorite (5CaO · 6SiO ₂ · 5H ₂ O) in the hydrothermal solidification step described later. And since the Ca / Si weight ratio of the tobermorite crystal | crystallization is 5/6, a calcium compound should just be added so that the Ca / Si weight ratio of a raw material mixture may be 5/6 or less. Even if it exceeds this value, it will be extra and wasted. The lower limit of the Ca / Si weight ratio depends on the strength of the solidified product to be obtained, but 1/6 is appropriate for obtaining a high-strength solidified product having a uniaxial compressive strength of 200 kg / cm ² or more. is there.
[0013]
Next, the raw material mixture is subjected to pressure molding by a molding machine to obtain a solidified product base which is a molded product (pressure molding process). For example, a briquetting machine is used to make a solid body like bean charcoal. By performing this pressure forming prior to the hydrothermal treatment, a solidified product base having a densified property can be obtained by increasing the adhesion between particles and decreasing the porosity. In this case, the pressure molding pressure is suitably in the range of 40 to 1000 kg / cm ² (3.92 to 98.1 MPa). If the pressure molding pressure is less than 40 kg / cm ² , the dense molding effect is not sufficient, and it is difficult to obtain a solid product with high strength and low water absorption rate in the hydrothermal solidification step described later. On the other hand, the strength and water absorption rate of the solidified product are saturated and are not improved even if pressure molding is performed at a pressure exceeding 1000 kg / cm ² , and molding at a higher molding pressure is wasted.
[0014]
Next, the solidified product base is subjected to an autoclave curing which is a hydrothermal treatment (hydrothermal solidification step). By this autoclave curing under saturated vapor pressure, calcium silicate (calcium silicate) is generated by the reaction of SiO ₂ in the solidified substrate with a calcium compound such as CaO. As a result, the particles firmly adhere to each other and become a solidified product with a low porosity, thereby obtaining a solidified product with high strength and low water absorption that can be used as a raw material for building materials such as fine aggregate for concrete and building blocks. be able to. In this hydrothermal treatment, among calcium silicates, it is preferable that crystals grow at a relatively low temperature of about 130 to 300 ° C. to produce high strength tobermorite. As hydrothermal treatment conditions, reaction temperature (autoclave curing temperature): 130 to 300 ° C., reaction time (curing time): 1 to 24 hours are appropriate. Typical conditions are 5 hours at a temperature of 180 ° C. The reaction temperature of 130 to 300 ° C. is a temperature range in which the crystal growth of tobermorite is well promoted, and the higher the reaction temperature, the higher the reaction rate. I'm sorry.
[0015]
In this way, by processing the raw material mixture mixed with turbid water cake and stone powder, both of which are crushed stone by-products, and calcium compounds, it has high strength and can be used as a raw material for building materials such as fine aggregate for concrete and building blocks. A high-quality solidified product with a low water absorption rate can be obtained, and waste water can be effectively reduced by using a muddy water cake with too much water and stone powder that is dry powder together. The cost for adjusting the water content of the muddy water cake by a dehydrator, a dryer, or a sun drying yard can be reduced, and the manufacturing cost can be reduced.
[0016]
【Example】
Examples of the present invention will be described below. FIG. 1 is a diagram showing the steps of a method for treating crushed stone by-products according to the present invention.
[0017]
As shown in FIG. 1, first, a muddy water cake and stone powder, which are crushed stone by-products, and a calcium compound are mixed to form a raw material mixture having a predetermined water content (raw material mixing step 11). In the present embodiment, the case where the turbid water cake from the crushed stone plant has too much water and the moisture content of the mixture supplied to the pressure forming step 12 described later exceeds 35% by weight, which is the upper limit, will be described. A predetermined amount of turbid water cake and stone powder having a moisture content of about 45%, whose moisture content has been measured in advance, is cut out from each storage tank and put into a mixer, and these are mixed for a predetermined time to have a moisture content of about 18%. A premix was obtained. Next, calcium compounds were added to the preliminary mixture, and these were mixed with the mixer over a predetermined time to obtain a raw material mixture having a water content of about 15%.
[0018]
In this example, a twin screw paddle type mixer was used as the mixer. In addition, calcium oxide fine powder was used as the calcium compound, and the amount added was such that the Ca / Si weight ratio of the raw material mixture was 1/4. About the typical particle size distribution of each material, muddy water cake: 75 μm under, stone powder: under 75 μm, fine calcium oxide powder: under 150 μm.
[0019]
About the implementation procedure in this raw material mixing process 11, although the said preliminary mixture was obtained and the raw material mixture was obtained after an appropriate time in a present Example, it is not limited to this. For example, a predetermined amount of turbid water cake, stone powder and calcium oxide fine powder having a moisture content of about 45%, whose moisture content has been measured in advance, is cut out from each storage tank and put into a mixer, and these are mixed to have a moisture content of about 15 % Of the raw material mixture may be made, and may be determined as appropriate according to the purpose and amount of addition of the stone powder.
[0020]
In addition, when the water content of the muddy water cake to be supplied is high and the stone powder is used for moisture adjustment to improve the workability at the time of mixing, for example, the water content is about 30% in which the water content is measured in advance. A predetermined amount of muddy water cake and stone powder are cut out from each storage tank and put into a mixer. These are mixed for a predetermined time to obtain a premix with a moisture content of about 13%. An example can be given in which powder is added and mixed with the mixer over a predetermined time to obtain a raw material mixture having a water content of about 10%.
[0021]
As described above, in the raw material mixing step 11, the dehydrator, the dryer or the sun drying yard is not required by adjusting the water content by using the turbid water cake having too much water and the stone powder as the dry powder together. , You don't have to spend money to adjust the water content of the muddy water cake.
[0022]
Next, the obtained raw material mixture having a water content of about 15% is pressure-molded into a solidified product base with a molding machine at a pressure molding pressure of 100 kg / cm ² (pressure molding step 12). In the examples, a briquetting machine was used as a molding machine, and a solidified product base in the form of bean charcoal was molded. The approximate dimension of one bean-charcoal solidified product base is 30 × 40 × 25 mm. The solidified product substrate thus pressure-molded was densified with high adhesion between particles and low porosity.
[0023]
Subsequently, these bean-charcoal solidified product bodies are hydrothermally reacted in a hydrothermal treatment reaction vessel to be solidified (hydrothermal solidification step 13). Hydrothermal treatment conditions were a reaction temperature of 180 ° C. and a reaction time of 5 hours. As a result, SiO ₂ and CaO in the solidified product substrate react to produce tobermorite, and the particles are firmly fixed to each other to become a solidified product having a small porosity, uniaxial compressive strength: 200 kg / cm ² or more, specific gravity: A bean-charcoal solidified product having a quality of 2.0 or more and water absorption: 15% or less could be obtained. The solidified product thus obtained can be used (utilized) as a raw material for building materials that are widely used, such as fine aggregate for concrete and building blocks. For example, the solidified product is crushed and classified to produce an artificial fine aggregate having a particle size of 5 mm or less, and the artificial fine aggregate is mixed with the natural fine aggregate in a weight ratio to the natural fine aggregate produced by the sand making facility of the crushed stone plant. By mixing at a ratio of material: artificial fine aggregate = 10: 1, it is possible to obtain a fine aggregate for concrete that satisfies the JIS standard.
[0024]
【The invention's effect】
As described above, according to the method for treating crushed stone by-products according to the present invention, by treating the mixture of muddy water cake and stone powder, both of which are crushed stone by-products, and a calcium compound, fine aggregate for concrete, building blocks, etc. High-strength, low-water-absorption high-quality solidified product that can be used as a raw material for building materials that are widely used and demanded, together with turbid water cake with too much moisture and stone powder that is dry powder It is possible to effectively reduce the waste by using it in the wastewater, and also reduce the cost for adjusting the moisture of the muddy water cake using a dehydrator, dryer, sun drying yard, etc. Can be achieved.
[Brief description of the drawings]
FIG. 1 is a diagram showing the steps of a method for treating crushed stone by-products according to the present invention.
[Explanation of symbols]
11 ... Raw material mixing process 12 ... Pressure molding process 13 ... Hydrothermal solidification process

Claims (2)

Both raw material mixing weight ratio of calcium to silicon calcium compound to a turbid water cake and stone powder is crushed stone products were mixed and added to a 1/6 or water content to obtain a 5 to 35 wt% of the raw material mixture A pressure forming step of obtaining a solidified product base by pressure-molding the raw material mixture at 3.9 to 98 MPa, and a hydrothermal solidifying step of solidifying the solidified product base by hydrothermal treatment to obtain a solidified product. A method for treating crushed stone by-products, comprising: 2. The method for treating crushed stone by-products according to claim 1, wherein the hydrothermal treatment is performed in a range of 130 to 300 [deg.] C. for autoclave curing.

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