KR20060102756A - A concrete admixture using waste tailing and methode of thereof - Google Patents

Abstract

The present invention relates to a concrete admixture using waste tailings, and in particular, cement used in concrete manufacturing process utilizing tailings, which are by-products generated in the process of mining ore and beneficiating metal minerals by flotation to recover metals from metal mines. The present invention relates to a concrete admixture and a method of manufacturing the same.

In the concrete admixture that admixture for concrete mixes and common cement used to cement substitute according to the present invention, and a specific surface area of 3000cm ² / g to about 5000cm ² / g of the powder in the form of an abandoned mine US 44 wt% to 66.5 wt.% With ; 10 to 20% by weight of blast furnace slag fine powder having a specific surface area of 4,000 to 8,000 m ² / g; 20% to 30% by weight fly ash having a specific surface area of 3,000 to 4,000 m ² / g; 3 wt% to 5 wt% of at least one selected from sodium hydroxide, anhydrous gypsum, sodium sulfate, sodium carbonate, aluminum sulfate, and sodium silicate powder as stimulants; It comprises 0.5 to 1% by weight of a powdered high performance water reducing agent.

Waste tailings, cement, concrete admixture, industrial by-product

Description

Concrete admixture using waste tailings and its manufacturing method {A Concrete Admixture using waste tailing and methode of

The present invention relates to a concrete admixture using waste tailings and a method of manufacturing the same. More specifically, the tailings, which are by-products generated in the process of mining ore and beneficiating metal minerals by flotation, have a predetermined size. The present invention relates to a concrete admixture that is pulverized and classified and mixed with a predetermined mixture to replace some cement, and a method for producing the same.

Although the amount of metal mining waste varies depending on the type of minerals, waste rock, tailings, and acid mine drainage (AMD) are generated by type.

These waste-rock and tailings are generated through mining and beneficiation operations. If these waste-rock and tailings are lost, they become sources of pollution in surrounding soils and stream sediments, and exposure to water and air causes acid mine wastewater.

The generation of acidic mine wastewater is known to have a greater effect on the tailings than the waste-rock, because the specific surface area of the tailings is much larger than that of the waste-rock, so most of the tailings are buried in the vicinity of the beneficiation facility or in the valley and left after the abandoned mine. As a result, contamination is known to be very serious.

The tailings generated by the beneficiation by-products from the metal mines are left in Korea's 212 waste and waste metal mines, while the Jungseok mine located in Sangdong-myeon, Yeongwol-gun, Gangwon-do has about 12 million tons buried in two tailings dams. It is becoming.

Since these substances contain heavy metals and sulfides that can be eluted by surface water and acid rain, they can contaminate surrounding cropland and water systems.

Recycling of inorganic raw materials, such as tailings, can take into account material recovery and material conversion. Material recovery can recover valuable resources, but secondary pollution can occur during the process and There is a problem that is difficult to recycle.

 Currently, the disposal of mine wastes in Korea is mainly landfilled by the installation of storage structures. This is not a method of treating by-products at the source. Not only is it necessary to manage the resources, but it also has the disadvantage of not using the useful resources effectively.

In addition, if the country is narrow and there is not a large amount of resources, there are many problems such as limited land use.Therefore, wastes from waste and waste mines scattered nationwide are analyzed for waste-rock and tailings by waste and waste mines. It is necessary to search for technical measures to evaluate physical and chemical properties and reduce them to useful resources.

In addition, the cost of restoration of mines in Korea has been estimated to have been about 330 billion won since 1980 (Korea Institute of Geoscience and Mineral Resources, 2002).

The stabilization treatment of mine by-products has been carried out in foreign countries for a long time. Currently, mines that have been abandoned are used to identify the pollution status, recover useful resources from waste, and use technologies such as blocking landfilling.

Among them, the trend of technology development that researches whether recycling is possible is the most dominant, and is trying to recycle, reduce, and harmlessly possible.

In China, for example, the use of tailings can be summarized into three major ways. First, the use of tailings as a mine filler is the main way to treat tailings. The Hungtoushan mine used about 350,000 tons per year, or 94.5% of the tailings generated from 1991, as a mine tunnel filler. The second method is to recover valuable valuables by reprocessing the tailings. Since 1991, Baiyin Corp. has processed 4.2 million tonnes of tailings to produce 1.1 million tonnes of sulfur concentrate. The recovered tailings were used as a material to fill the tunnel. Third, M & T tungsten mines have been selling tailings to brick factories for use as bulking materials since 1992. Consumption of tailings is much higher than that of current tailings. The tailings that have been stored have been used. At present, the average recycling rate of nonferrous metal mine tailings in China is reported to be around 20%.

As described above, in the case of foreign countries, researches are being conducted to recover useful resources or to appropriately treat tailings by developing a technology suitable for each mining situation, and thus, it can be seen that it contributes to the activation of mines.

The tailings are similar to fly ash with major chemicals such as silicon dioxide, aluminum oxide, ferric oxide and calcium oxide, and have already been atomized during metal beneficiation. However, this material is not activated and does not have hydraulic properties, so it does not increase strength when used alone. However, when used as a filler, it does not adversely affect the hardening process of concrete, but rather, it compensates for the shortage of fine particles due to the use of sea sand, thereby improving the material separation resistance and making the structure of concrete tight. When used as a cement substitute, the heat of hydration can be reduced.

Admixtures commonly used as cement substitutes for ready-mixed concrete, mortar, and concrete secondary products are known in the manufacture of fly ash and pig iron, which are ashes collected from flue gas from boilers that burn pulverized coal. It is blast furnace slag fine powder which is an amorphous pumice-like particle obtained by taking slag out of a furnace and quenching with water. Since the fly ash content is different according to the combustion conditions of the boiler, the fly ash reduces the amount of air contained in the unconsolidated concrete, which may adversely affect the durability of the concrete.Blast furnace slag powder is almost entirely made of slag cement. As it is being recycled and expensive, it is difficult to easily purchase and use it as an industrial cement substitute. In addition, fly ash and blast furnace slag fine powder are formulated to KS standards, and the supply of fly ash and slag is largely imported due to insufficient supply.

Overseas (Norway, Iceland, Canada, USA, etc.), the use of silica fume, an ultra-fine particle obtained as a by-product in the process of producing silicon alloys, is common, but there is no production in Korea. Since this is very expensive (500,000 won / ton) is not being used in general.

Therefore, an object of the present invention is to devise to improve the above problems, it is possible to prevent the decrease in strength of the solidified body due to the simple replacement of the waste tailings when using a suitable amount to replace the ready-mixed concrete, mortar and concrete secondary products , Concrete admixture comprising fly ash, blast furnace slag fine powder, stimulant and powdered powder type high performance water sensitizer, which is a mixed material composed of fine particles and filled with fine pores of concrete to improve durability. For the purpose of providing it.

In addition, an object of the present invention is to provide an inexpensive concrete admixture capable of exhibiting almost the same performance as the concrete using only Portland cement by adding 10 to 30% by weight compared to the cement and its manufacturing method.

The present invention for achieving the above object is 44% by weight to 66.5% by weight of the waste tailings in the form of powder having a specific surface area of 3000cm ² / g to 5000cm ² / g in the concrete admixture used as a cement substitute ; 10 to 20% by weight of blast furnace slag fine powder having a specific surface area of 4,000 to 8,000 m ² / g; 20% to 30% by weight fly ash having a specific surface area of 3,000 to 4,000 m ² / g; 3 wt% to 5 wt% of at least one selected from sodium hydroxide, anhydrous gypsum, sodium sulfate, sodium carbonate, aluminum sulfate, and sodium silicate powder as stimulants; It is made of a mixed material for concrete, characterized in that it comprises a powder type high performance water reducing agent 0.5% to 1% by weight.

The concrete admixture according to the present invention is formed by the following process.

First, the waste tailings are dried such that moisture is 1% or less at a temperature of 180 ° C to 200 ° C.

The dried waste tailings are classified and sorted for the waste tailings powder having a specific surface area of 3000 cm ² / g to 5000 cm ² / g.

From 44% to 66.5% of the classified waste tailings, from 10% to 20% by weight of blast furnace slag powder with a specific surface area of 4,000cm ² / g to 8,000m ² / g, and from 3,000cm ² / g to 4,000m ² / 20% to 30% by weight of fly ash, 3% to 5% by weight of at least one selected from sodium hydroxide, anhydrous gypsum, sodium sulfate, sodium carbonate, aluminum sulfate, and sodium silicate powder as stimulants, and a powder type high performance water reducing agent Mix 0.5% to 1% by weight.

Since the waste tailings used in the present invention are stored in the open air, they contain some moisture and cannot be used by themselves.

At this time, the drying temperature is preferably within 200 ℃, if the temperature is higher, the drying cost is slightly increased, but there is an advantage that can increase the activity of the tailings.

Since the tailings are already atomized during the beneficiation process, after drying, the tailings are in the form of a powder with a specific surface area of about 1,800 cm ² / g to 2,500 cm ² / g. Since this is impossible, the powder having 3,000cm ² / g to 5,000cm ² / g is first sorted through classification, and the coarse particles remaining in the sieve are transferred to the grinder, pulverized by a ball mill or roller mill, and then transferred to the classifier to fine particles. The waste tailings having a specific surface area of 3000 cm ² / g to 5000 cm ² / g are obtained by repeating the process of screening the coarse particles and transferring the coarse particles back to the grinder.

When the concrete admixture manufactured in this way replaces 10 wt% to 30 wt% of general cement usage, it can secure almost the same strength and fluidity as concrete using ordinary Portland cement alone, and the waste tailings particulates fill the fine pores of concrete. By the latent hydraulic and pozzolanic reaction of blast furnace slag fine powder and fly ash, the concrete structure can be made more compact to improve durability.

The tailings are similar to fly ash with the main chemicals such as silicon dioxide, aluminum oxide, ferric oxide and calcium oxide, but are already atomized in the process of metal beneficiation. Do not.

However, when used as a filler, it does not adversely affect the hardening process of concrete, but rather, it compensates for the shortage of fine particles due to the use of sea sand, thereby improving the material separation resistance and making the structure of concrete tight. When used as a cement substitute, the heat of hydration can be reduced.

Of the total composition, the tailings are suitable in the range of 44% by weight to 66.5% by weight, and less than 44% of the tailings is disadvantageous in terms of recycling rate of the waste tailings. May cause a decrease in strength.

The blast furnace slag is generally a specific surface area of 4,000cm ² / g to about 4,600cm ² / g, but it is widely used in the case to be used for ready mixed concrete to a specific surface area in order to compensate for the initial strength due to the incorporation of the tailings 6,000cm ² / By using g to 8,000m ² / g, the activity is very excellent, and it is possible to prevent the decrease in the initial strength through rapid reaction with the stimulant even at room temperature.

When used in concrete secondary products, it is acceptable to use 4,000 cm ² / g to 5,0000 m ² / g. In addition, blast furnace slag powder has latent hydraulic properties, which can increase the strength of long-term age.

The fly ash may be used after the combustion of coal in a thermal power plant or cogeneration plant, such as the loss of ignition by unburned carbon of 1% by weight to 15% by weight. It is possible to reduce the amount of air required by adsorption, so bituminous coal fly ash with less than 5% of unburned carbon content is suitable, and anthracite fly ash with more than 5% of unburned carbon powder can be used for concrete secondary products. Fly ash is also a pozzolanic substance that plays a role in promoting long-term strength.

The blast furnace slag fine powder and fly ash in the total composition are each 10 wt% to 20 wt% and 20 wt% to 30 wt%, respectively, which are disadvantageous in terms of strength when contained below and in terms of economy when exceeded.

The stimulant is sodium hydroxide, anhydrous gypsum, sodium sulfate, sodium carbonate, aluminum sulfate, sodium silicate powder, etc. are suitable as a material for activating the reaction of blast furnace slag fine powder and fly ash, and one or more of them may be selected and used.

In the total composition, the stimulant is 3% to 5% by weight, and when included in less than 3% by weight, it is insufficient to activate the blast furnace slag powder and fly ash, and when it exceeds 5% by weight, the stimulation becomes stronger but economically. It is disadvantageous.

The powder type high performance sensitizer can reduce the fluidity when incorporated into cement because the shape of the waste tailings is heterogeneous, angular and high specific surface area, it serves to prevent this.

In the total composition, the water reducing agent is 0.5% to 1% by weight, and when included in less than 0.5% by weight, the fluidity is slightly lower than that of the concrete using only Portland cement. Compared to the above, it can secure excellent liquidity, but it is disadvantageous in terms of economic efficiency.

Hereinafter, embodiments of the concrete admixture according to the present invention will be described in detail.

Example 1

Table 1 shows the mixing of the concrete admixture, Table 2 shows the mixing strength of 25MPa of the ready-mixed concrete specification, in the case of Comparative Example 1 was used ordinary Portland cement and in the case of Example 1 waste tailings, blast furnace slag fine powder, fly ash, stimulant And powdered high performance water reducing agent was mixed to prepare a concrete admixture.

Table 3 shows the test results of the general strength (25MPa) concrete.

As shown in Table 3, Comparative Example 1 is a test result of concrete using a normal cement and in the case of Example 1 50% by weight waste tailings, blast furnace slag fine powder 20% by weight, fly ash 25.5% by weight, 2 weight of aluminum sulfate as a stimulant This is the test result of concrete manufactured by replacing 20% by weight of concrete admixture prepared by mixing%, 2% by weight of sodium carbonate and 0.5% by weight of powder type high performance water reducing agent.

In the case of Example 1, the slump and the amount of air were almost similar to those of Comparative Example 1, and the compressive strength was about the same or higher than that of Comparative Example 1 on the 3rd and 7th days. You can see it.

Example 2

Table 4 shows the mix of concrete admixtures, Table 5 shows the mixing strength of 40MPa, which is a ready-mix concrete standard, and used Portland cement for Comparative Example 1, and for Example 1, tailings, blast furnace slag powder, fly ash, stimulant and The powder admixture was mixed to prepare a concrete admixture.

Table 6 shows the experimental results of slump, air volume, heat of hydration and compressive strength of high strength (40MPa) concrete. In order to measure the heat of hydration reaction, a mold with a capacity of 64ℓ (40 × 40 × 50cm) insulated with heat insulating material was manufactured, and concrete was poured right after the beams. Then, a thermocouple, a pair of thermo electrons, was settled in the center of the concrete. The temperature change in the concrete was measured using TDS-602).

As shown in Table 6, Comparative Example 2 is a test result of concrete using general cement and in the case of Example 2 55% by weight of waste tailings, 20% by weight of blast furnace slag powder, 20% of fly ash, 2% of sodium silicate powder as a stimulant It is an experimental result of concrete manufactured by replacing 20% by weight of concrete admixture prepared by mixing%, 1% by weight of sodium hydroxide and 1% by weight of powder type high performance water reducing agent.

In the case of Example 2, the slump and air volume were slightly higher than those of Comparative Example 2, and the compressive strength was about 4% lower on 3 and 7 days, but on the 28 and 90 days, it was about 7% higher than that of Comparative Example 1. It can be seen that the high strength.

In addition, in the case of Comparative Example 2, the maximum temperature was 67.6 ° C. and 58.2 ° C. in Example 2, respectively. Looking at the internal maximum temperature reached 14 hours in the comparative example, 21 hours in the case of Example 2.

That is, when the concrete is mixed with the admixture of the present invention, the internal maximum temperature shows a tendency to decrease and the maximum temperature reaching time is long. The temperature rise of concrete by the hydration heat of cement during the hardening process affects the strength of concrete and the properties of concrete. Especially in the case of high-strength concrete with high unit cement content and mass concrete where internal temperature is difficult to dissipate, Due to the temperature difference between the inside and the outside of the concrete, cracking through temperature stress is likely to occur or the strength is lowered. Therefore, the concrete admixture in the present invention is considered to be very effective if the appropriate amount is used to replace the existing ordinary portland cement as a method for reducing the heat of hydration.

When the concrete admixture according to the present invention is partially substituted for the portland cement, the equivalent slump, the air volume and the initial strength can be secured in comparison with the case of the ordinary portland cement alone, and the higher strength can be expressed in the long-term age. In addition, it is effective to reduce the heat of hydration if used in high-strength concrete with high unit cement content and mass concrete that is difficult to dissipate internal temperature.

In addition, it is possible to compensate for the shortage of fines due to the use of sea sand to enhance the material separation resistance and to keep the structure of the concrete tight.

Moreover, by using the waste tailings, the production cost is low and it is very economical, thus reducing the cost of manufacturing concrete, and by using waste such as bitumen beneficiation waste tailings, it saves resources to recycle waste resources and prevents environmental pollution. There is an effect such as.

Although the present invention has been described in detail only with respect to the embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical spirit of the present invention, and such modifications and variations belong to the appended claims.

Claims (3)

In concrete admixture mixed with ordinary cement and used as cement substitute, 44 wt% to 66.5 wt% of waste tailings in powder form having a specific surface area of 3000 cm ² / g to 5000 cm ² / g; 10 to 20% by weight of blast furnace slag fine powder having a specific surface area of 4,000 to 8,000 m ² / g; 20% to 30% by weight fly ash having a specific surface area of 3,000 to 4,000 m ² / g; 3 wt% to 5 wt% of at least one selected from sodium hydroxide, anhydrous gypsum, sodium sulfate, sodium carbonate, aluminum sulfate, and sodium silicate powder as stimulants; A mixed admixture for concrete, characterized in that the composition comprising 0.5% to 1% by weight of a powder type high performance water reducing agent.  The concrete admixture according to claim 1, wherein the ratio of the admixture with the general cement is 10% by weight to 30% by weight based on the amount of general cement. In the method of manufacturing a concrete admixture used as a cement substitute by mixing with general cement, A drying step of drying the waste tailings at a temperature of 180 ° C. to 200 ° C. such that moisture is 1% or less; The classifying step of screening the US Mine powder having a specific surface area of the dried abandoned US 3000cm ² / g to about 5000cm ² / g through and classifying; Fly ash from 44% to 66.5% of the classified waste tailings, 10% to 20% by weight of blast furnace slag powder with specific surface area of 4,000cm ² / g to 8,000m ² / g and specific surface area of 3,000 ~ 4,000m ² / g 20 wt% to 30 wt%, 3 wt% to 5 wt% of at least one selected from sodium hydroxide, anhydrous gypsum, sodium sulfate, sodium carbonate, aluminum sulfate, and sodium silicate powder as stimulants, and 0.5 wt% to a powdered high performance water reducing agent Method for producing a mixed material for concrete, characterized in that the process consisting of mixing 1% by weight.