KR20130060890A - Method for stabilizing mine waste aggregate yard using coal ash - Google Patents

Abstract

PURPOSE: A method for stabilizing mine waste aggregate yard is provided to prevent loss of a waste stone, elution of heavy metal, and flowability, by using a fly ash as a stabilizing material. CONSTITUTION: A method for stabilizing mine waste aggregate yard comprises a step of forming a stabilizing layer by spraying a mixed stabilizer of waste stone and fly ash, a fly ash stabilizer, or a composite stabilizer mixed of fly ash and covering material, on a waste stone layer. The particle diameter of the fly ash is 10-100 micron. The mixed stabilizer of waste stone and fly ash comprises 60-80 wt% of the waste stone, and 20-40 wt% of the fly ash. The composite stabilizer comprises 60-80 wt% of the covering material and 20-40 wt% of the fly ash. [Reference numerals] (AA) Waste stone + Fly ash mixing and stabilizing layer; (BB) Waste stone layer

Description

METHOD FOR STABILIZING MINE WASTE AGGREGATE YARD USING COAL ASH}

The present invention relates to a method for stabilizing waste-rock stockyards, and more particularly, waste-rock stockyards using coal ash, which can suppress the loss of waste-rock and the dissolution and flow of heavy metals by using it as a stabilizing material for waste-rock without disposing of coal ash generated in a power plant. It relates to a stabilization method.

In general, there are many small and small abandoned mines that have been mined in mining activities such as mining, mining, beneficiation, and smelting. In addition to such abandoned mines, mine waste (mine tailings, Mine wastewater, mine waste water, etc.) and heavy metal contamination.

Heavy metals such as lead, arsenic, lead, cadmium, copper, and zinc leak out and pollute the soil to a wide range of farmland around the mine.

When these heavy metals accumulate in the human body, they are not excreted well and are very dangerous because they accumulate in proteins in our body and cause side effects over a long period of time. For example, hemoglobin, which carries oxygen throughout our body, has a form of iron that binds to a protein called globin, but when mercury enters our body and attaches to globin instead of iron,

Loss of carrying capacity. Lead can also paralyze nerves and muscles, cadmium can cause lung cancer, soften bones, and manganese can accumulate in the brain and liver, causing growth and decreased fertility. The fluidity of contaminated soils containing heavy metals is determined by the presence of products due to changes in the binding conditions of the heavy metals, weathering, etc., soil clay and water content, soil water pH, microbial activity, and acid mine drainage. Due to the physical and chemical properties of the soil such as acid mine drainage and the surrounding environment, heavy metal transitions and distribution of heavy metal-contaminated crops during the growth of crops planted in contaminated farmland due to the fluidity of heavy metals in the contaminated soil As a serious social problem, it is urgent to take measures to restore heavy metal contaminated soils in order to reduce the damage caused by the widespread contaminated soils.

Since the present invention is intended for stabilization of the waste-rock yard, the following description will be limited to the waste-rock yard.

During mine development, a considerable amount of waste-rock is generated during mine excavation and mineral selection. The waste-rock is usually deposited through the waste-rock stockyard, and because of the large transportation costs for transporting the waste-rock, the waste-rock is deposited on suitable terrain near the mine.

Since the waste-rock itself does not have added value, it does not cost a great deal of money and is naturally loaded. That is, it does not take into account the loss of the waste-rock dump and does not take ground reinforcement or safety structures.

The waste-rock stockyards generally form steep slopes, and if the waste-rock stockyards do not have rainwater-excluded structures such as waterways, the waste-rock may be lost to the bottom due to heavy rainfall. In addition, even in the case of constructing a structure for preventing the loss of waste-rock, if left for a long time after the abandoned mine, there is a fear that the structure collapses and the waste-rock may be lost. When the waste-rock is lost to the lower farmland or rivers, secondary damages such as soil and water pollution can be caused by the heavy metal minerals remaining in the waste-rock.

Therefore, if the waste-rock can be treated to prevent the loss of waste-rock and prevent the fluidity of heavy metals, it is not necessary to construct a safety structure at a high cost and prevent secondary pollution due to the loss. .

On the other hand, in coal-fired power plants using coal as an energy source, since coal, which is a raw material, contains mineral powder, mineral powder remains as ash after combustion. Currently, much of Korea's power supply is relied on thermal power plants, and as a result, the amount of coal ash produced after combustion increases according to the use of coal used in thermal power plants. In view of this, various treatment methods for using coal ash have been proposed. Since coal ash has properties similar to clay, it has been applied to cement additives, building bricks, zeolite manufacturing, pigments, insulating materials, and polymer fillers. Of course, recycling techniques for avoiding landfilling of coal ash have been proposed, but a lot of landfills are being disposed because they require a lot of costs.

Republic of Korea Patent No. 10-1016790 Republic of Korea Patent Publication No. 10-1998-0047616

The present invention is to solve the problems described above, stabilizing waste-rock storage using coal ash that can suppress the loss of waste stone and the dissolution and fluidity of heavy metals by using as a stabilizing material of the waste-rock without discarding the coal ash generated in the power plant The purpose is to provide a method.

The method for stabilizing waste-rock stockyards using coal ash according to the present invention is a stabilization layer by spraying any one of a mixed stabilizer mixed with waste-rock and coal ash or a complex stabilizer mixed with coal ash and cover material on the waste-rock layer of the waste-rock stockyard. It characterized in that to form.

According to the method for stabilizing waste-rock stockyards using coal ash according to the present invention, coal ash generated from a power plant is mixed with the waste-rock stockpiles with waste-rock or implemented in a layered structure to prevent the loss of the waste-rock stock-pit slope even when the slope of the waste-rock stockpiles is steeply inclined. Since it is possible to suppress the elution and fluidity of the heavy metal contained in the can prevent secondary pollution around the waste-rock stockyard, it is possible to reduce the cost of the construction of the safety structure to prevent loss.

In addition, since coal ash is generated in a coal-fired power plant and can secure coal ash without incurring high costs, it is possible to stabilize the waste-rock storage site at a low cost, and to reduce the cost (such as site securing cost) due to the reclamation of coal ash. The use of can be greatly expanded.

1 is a graph showing the particle size of coal ash.
2a to 2c is a graph showing the pollutant removal efficiency according to the mixing ratio of coal ash according to the present invention.
3A and 3B are graphs showing changes in pH and EC according to the present invention.
4 to 7 is a tomogram of the waste-rock stockyard by the waste-rock stockyard stabilization method using coal ash according to the present invention, respectively.

The method for stabilizing waste-rock stockyards using coal ash according to the present invention uses coal ash (fly ash) mixed with waste-rock in the waste-rock stockyard, or is used as a stratified structure on the waste-rock stockyard, or mixed with cover material to cover the waste-rock stockyard or implement a separate cover layer on the upper layer. By preventing the loss of the waste-rock storage, the elution and fluidity of the heavy metals are inhibited and the specific stabilization method will be described through the following examples, first, the reaction of coal ash and waste-rock will be described.

There are prior arts that use coal ash for stabilization of the soil, and even if there are no prior arts used for stabilization of the waste-rock stockyard, it is judged that the patentability is weak by simply using coal ash in the waste-rock stockyard without special processing. Preventing the loss of waste-rock is due to physical action, and elution of heavy metals seems to be due to chemical action, and whether or not physical and chemical action is possible through coal ash. I believe it is desirable.

1. Characteristics of waste-rock.

Generally, the waste-rock pile is composed of granulated to granulated rocks (shale, sandstone, etc.) and is a porous medium partially saturated with water. There are various sulfide minerals in the rock constituting the waste-rock pile, and pyrite is recognized as the main cause of acid mine drainage because pyrite is the largest distribution among the sulfide minerals. Ep. Below. The chemical reaction of 1 is commonly known as the oxidation of pyrite.

O₂ + H₂O → Fe^{2 +}+ 2SO₄ ^{2 -}+ 2H⁺ Eq. 1
FeS ₂ +

O _{2 ^{+ H 2 O → Fe 2 +}} + 2SO 4 2 - + 2H + Eq. One

Sulfide minerals in the waste-rock generate acid mine drainage through the above reaction, and the acid mine drainage characteristics of Dongwon-dominant coal mine are shown in Table 1 below.

Sample Sampling date Temp.
(℃) pH Fe
(mg / l) Al
(mg / l) Mn
(mg / l) SO ₄ ^2-
(mg / l) Acidity
(mg / l as CaCO ₃ ) Acid mine drainage August 2002 16.1 1.69 454.30 123.00 1.44 9,017.01 2,518.07 April
2005 5.2 2.25 166.30 100.90 5.01 1,741.22 1,147.80

2. Characteristics of Fly Ash

Fly ash is classified into two types by size of particle size. It is divided into floor ash that falls under the boiler due to its large particle size and fly ash that is collected from the dust collector because the particle size is smaller than that of the floor material.The treatment efficiency is determined by the difference in surface area and elemental composition difference according to the two particle sizes. In order to determine the optimum ash ash for stabilizing the waste-rock stockyard, a comparative experiment was conducted for each sample.

Chemical properties of the flooring material and fly ash are shown in Table 2 below.

More than 70% of floor and fly ash consisted of SiO2 and Al2O3, and floor ash was SiO2> Al2O3> Fe2O3> CaO> K2O> TiO2> MgO and fly ash was SiO2> Al2O3> K2O> Fe2O3> CaO> TiO2 > MgO.

The particle size analysis result of the landfill coal ash mixed with the bottom ash and fly ash is as shown in Figure 1, in the present invention is preferably 10 ~ 100㎛. It is difficult to neutralize the acid mine drainage in the waste-rock stockyard at a particle size of 10 μm or less, and the supply and demand of 100 μm or more is not smooth and there is no significant difference in the neutralization of the acid mine drainage.

The mixing ratio of the bottom ash and fly ash was treated with distilled water and treated with distilled water, and the samples were taken by date, and the heavy metals were extracted according to the soil pollution process test method. Experimental results showed that fly ash was better than flooring in comparison with control, and the treatment efficiency of flooring was 20-30% and fly ash was 30-40%. . The treatment efficiencies of heavy metals were examined in the order of Pb> Cu> Zn> Cd. Fly ash was more efficient than flooring due to its small particle size and large surface area.

In addition, both fly ash and bottom ash react with carbon dioxide and water present in coal waste-rock under the influence of large amounts of calcium and magnesium to produce bicarbonate to increase pH and induce heavy metal stabilization by neutralization. In addition, pH correction by alkaline substances such as CaCO3, CaO and MgO contained in coal ash, and CaCO3 contained in a large amount of coal ash, stabilizes mechanism in which heavy metal ions are adsorbed and precipitated on the surface of coal ash in the form of a compound.

As described above, as a result of comparing the treatment efficiency of the bottom ash and fly ash in the coal ash, the fly ash was found to have better treatment efficiency than the bottom ash, and the fly ash was determined as a stabilizer, and the optimum mixing ratio of the fly ash was derived through experiments.

Experiments were performed with fly ash 5%, 10%, 20%, 40% mixing and stratification. Experimental results showed that the treatment efficiency according to the mixing ratio was 40%> 20%> 10%> 5% in order (Fig. 2a to 2c, the control was treated only waste-rock), and the efficiency according to the treatment method was Mixture treatment of fly ash was better than pollutant removal.

When coal ash is used as a stabilizer for waste-rock, the most important effect of stabilization of heavy metals is the neutralization ability by pH calibration. After incubation for 48 hours, the pH and EC were measured by filtering. 3A and 3B show the neutralization power test results of coal ash. When neutralizing waste rock and leachate generated from coal mines using coal ash, pH (acidity) and EC (electric conductivity) are treated at 20-40% of the result, so that the pH can be stabilized at an appropriate level. When satisfactory and the introduction of the vegetation on the surface treated with stabilization was determined to satisfy the EC does not impede the growth of the plant was determined to be the most appropriate stabilizer throughput. In the mixing ratio used for the test, the throughput of 20% or less did not satisfy the appropriate level of acidity, and the throughput of 40% or more was similar to that of 40%.

4 to 7 is a tomogram showing an example of the method for stabilizing waste-rock stockyard according to the present invention.

Figure 3 is to form a mixed stabilization layer by spraying a stabilizer mixed with the waste-rock and coal ash to a certain thickness on the waste-rock layer of the waste-rock stockyard.

The stabilizer is made of 60 to 80% by weight of waste-rock and 20 to 40% by weight of coal ash. As described above, when the coal ash is mixed to 20% by weight or less, the loss of waste stone and the neutralization effect of the heavy metal is weak, and when mixed to 40% by weight or more, there is no significant difference in neutralization of the heavy metal.

The thickness of the mixed stabilization layer is a depth useful for applying to the waste-rock deposit of the waste coal mine, and is not limited to a specific value as a thickness for economically restoring a large amount of waste-rock without moving.

Stabilization layer (mixed pebbles and coal ash) is a layered structure on the pebbles layer, which is composed of waste rocks and coal ash to stabilize heavy metals in the acid mine drainage generated from waste rocks. Precipitation, adsorption, and co-precipitation are carried out using the high pH and neutralizing substances that have.

Although not shown in the drawings, the mixed stabilization layer of waste-rock and coal ash may be formed in a multi-layered structure alternately with the waste-rock layer, provided that the mixed stabilization layer of waste-rock and coal ash is formed on the top layer.

4 is a coal ash stabilization layer formed on the waste-rock layer of the waste-rock storage. That is, the waste-rock storage is formed of a layered structure of the waste-rock layer and the coal ash stabilization layer.

The action according to the layered structure of the waste-rock layer and the coal ash stabilization layer is the same reaction as the stabilization method by mixing, and the reason why it is applied in the layered form is that it can be applied to a running mine. In other words, this is to apply a method of simultaneously stacking coal ash that can be used as a neutralizing material when the waste rock is deposited in a running mine.

Although not shown in the drawings, the coal ash stabilization layer may be formed in a multilayered structure alternately with the waste-rock layer, provided that the coal ash stabilization layer is formed on the top layer.

The thickness of the coal ash stabilization layer in which the waste-rock is not mixed may be 10CM and 20CM, and the amount that can induce the neutralization of acid mine drainage generated by the waste-rock in the lower portion and the amount that the slope does not collapse. Since the thickness can vary, the thickness can vary.

5 is sprayed to a certain thickness of the stabilizer mixed with the waste-rock and coal ash on the effluent layer of the waste-rock stockyard to form a mixed stabilization layer, and by applying a cover material on the mixed stabilization layer to form a cover layer. The cover material is, for example, it is preferable that the soil quality of the seed can be germinated so that the greening of the waste-rock stockyard.

The stabilizer is made of 60 to 80% by weight of waste-rock and 20 to 40% by weight of coal ash.

As in the above-described example, the mixed stabilization layer of waste rock and coal ash may be formed in a multi-layered structure alternately with the waste rock layer.

Cover soils are intended to facilitate vegetation, but because the supply of cover materials is difficult, the minimum thickness is required for vegetation.

6 is sprayed on the waste-rock layer of the waste-rock storage to form a complex stabilization layer by spraying a stabilizer mixed with coal ash and cover material.

In addition, it is also possible to form a cover layer by spraying only the pure cover material on the composite stabilization layer of coal ash and cover material.

The combined use of coal ash and cover ash will have the advantage of neutralizing acid mine drainage and allowing vegetation.

Claims (5)

The stabilization layer is formed by spraying any one of a mixed stabilizer mixed with waste rock and coal ash or a complex stabilizer mixed with coal ash and cover material on the waste-rock layer of the waste-rock stockyard, and the coal ash has a particle size of 10-100 μm. A method for stabilizing waste-rock stockyards using coal ash. The method for stabilizing waste-rock stockpiles using coal ash according to claim 1, wherein the cover layer is sprayed onto the stabilization layer to form a cover layer. The method of claim 1, wherein the stabilizing layer is alternately repeated with the waste-rock layer to form a multi-layered layered structure, the method for stabilizing waste-rock storage using coal ash. The waste stabilizer using coal ash according to any one of claims 1 to 3, wherein the mixed stabilizer in which the waste rock and coal ash are mixed is sprayed with 60 to 80 wt% of waste rock and 20 to 40 wt% of coal ash. Stabilization method. The waste stabilizer using coal ash according to any one of claims 1 to 3, wherein the complex stabilizer mixed with the coal ash and the cover material is sprayed with 60 to 80% by weight of the cover material and 20 to 40% by weight of the ash. Stabilization method.

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