KR101146690B1 - Method for prevention of sulfide mineral oxidation - Google Patents

Abstract

The present invention relates to a sulfide anti-oxidation method. The sulfide mineral oxidation prevention method according to the present invention is a sulfide mineral by coating a rock containing sulfide minerals by spraying a coating agent on a region in which the rocks containing sulfide minerals are concentrated, that is, the mining or surface layer of the waste rock stockyard. It is characterized in that it is prevented from being exposed to the outside and oxidized. The coating contains calcium, which prevents acid rock drainage through neutralization even if the sulfide mineral is partially oxidized.

Description

Method for prevention of sulfide mineral oxidation

The present invention relates to a method for preventing environmental pollution, and more particularly, to a method for preventing oxidation of sulfide minerals for preventing acid rock drainage by acidifying groundwater and the like while sulfide minerals present in mining sites of abandoned mines are exposed to the outside. .

Acid Rock Drainage (ARD), which occurs in mining areas and construction sites, is generated by the reaction of sulfide mineral rock with atmospheric oxygen and surface water, causing much damage to surrounding water systems and the environment. do.

If the drainage of pumps is stopped in mines after metal or coal mines are closed, mining, tunnels, and transport roads are gradually filled with groundwater from the surroundings. These underground spaces function as a gangway pipeline, and as time goes by, the level of the underground spaces comes into contact with the gangland water. In this way, the mine water is acidified by mining or waste-rock as it comes into contact with the strata of the unsaturated zone, causing acid drainage or leachate to generate pollution.

Pyrite is recognized as a major cause of acid rock drainage because sulfite minerals that act as a cause of acid rock drainage contain the most pyrite. In addition, sulfide minerals such as pyrrohotite, marcasite, chalcopyrite and arsennopyrite are exposed to the surface to generate acids, lowering the pH of the surrounding natural waters.Al, Mn, Zn, Cd And acid rock drainage containing heavy metals due to elution of Pb and the like. It has been reported that significant mine water pollution is expected when the total sulfur content of the strata contains more than 1%.

Acidic drainage continues to spill over long periods of time, causing serious pollution to the surrounding water system and soil environment. Accordingly, various methods for treating acid drainage have been attempted in order to prevent damage caused by acid drainage. In other words, a method of actively treating by adding neutralizing agent or the like to an acidic drainage and SAPS as a passive treatment method using limestone and organic matter were used.

However, all of these treatment methods are intended to treat acid drainage after it has been generated. Therefore, there is a demand for technology development to suppress the occurrence of acid drainage itself.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a sulfided mineral oxidation prevention method capable of inhibiting the occurrence of acidic rock drainage itself by preventing sulfided minerals from being exposed to the outside and oxidized.

The sulfide mineral oxidation prevention method according to the present invention for achieving the above object is to prevent the sulfide minerals from being exposed to the outside by spraying a coating on a region in which rocks containing sulfide minerals are concentrated. Is characterized by containing calcium.

According to the present invention, the coating agent is preferably calcium silicate.

According to the present invention, the coating agent further comprises a binder to improve the binding force between the rock containing the sulfide mineral and the calcium silicate, the binder may be used a silica sol.

According to the present invention, the coating agent may be used by mixing the silica sol in a volume ratio of 15 ~ 60ml with respect to 1000ml of the calcium silicate.

In addition, the present invention is applied to the mining or waste-rock stockyard of the abandoned mine, the coating agent is sprayed on the surface layer portion of the mining or waste-rock stockyard so that the rocks containing sulfide minerals are coated.

In the present invention, the calcium silicate coating material is sprayed onto the waste-rock storage or the mining surface layer to coat the sulfide mineral rocks that can come into contact with air to prevent oxidation.

As the coating agent used in the present invention is a natural material, secondary pollution does not occur, and the binding force with the rock including sulfide minerals can be maintained for a long time and thus has a continuous anti-oxidation ability.

In addition, in the present invention, even if oxidation proceeds in a part of rock including sulfide mineral, calcium acts as a neutralizing agent so that acid rock drainage does not occur.

In addition, even if the coating is applied only to the surface layer of the mining or waste-rock dump of the abandoned mine, the rock of the deep layer is blocked from contact with air, thereby economically preventing the rock including sulfide minerals from oxidizing.

1 is a schematic diagram illustrating a sulfide anti-oxidation method according to an embodiment of the present invention.
Figure 2 is a photograph of the four areas and samples from which waste-rock samples for testing the present invention.
3 to 5 are ABA test results for waste-rock samples, FIG. 3 is a table showing the relationship between pH and EC, FIG. 4 is a table showing the relationship between the total content of ANC and sulfur, and FIG. 5 is a NAGpH and NAPP. This table shows the relationship with.
Figure 6 is a table showing the overall ABA test results.
7 is a table showing the results of viscosity experiments after mixing silica sol with a silicate silicate.
8 to 11 are graphs showing changes in pH, FIG. 9 in Ca, FIG. 10 in Fe, and FIG. 11 in Na as a result of experiments to investigate the coating effect on the waste-rock sample collected from the forestry mine. .
12 to 15 are graphs showing changes in pH, FIG. 13 in Ca, FIG. 14 in Fe, and FIG. 15 in Na as a result of experiments to determine coating effects on waste-rock samples collected from pottery coal mines. .
16 to 19 are graphs showing changes in pH, FIG. 17 is Ca, FIG. 18 is Fe, and FIG. 19 is Na as a result of experiments to determine the coating effect on the waste-rock sample collected from the giant mine. .
20 to 23 are graphs showing changes in pH, FIG. 21 in Ca, FIG. 22 in Fe, and FIG. 23 in Na as a result of experiments to determine coating effects on waste-rock samples collected in the Geumsan region. .
FIG. 24 is a photograph taken by an electron microscope of waste-rock taken from a pottery mine after coating experiments.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a sulfide mineral oxidation prevention method according to a preferred embodiment of the present invention.

As described in the related art, the waste-rock storage in which mining of waste mines or waste rocks discharged from waste mines are stacked contains a large amount of rocks capable of generating acid, including sulfide minerals. That is, a large amount of pyrite, pyrrhotite, pyrite, brass, ubiquitous, and the like are contained.

In order to prevent oxidation of these acid-generating rocks, the above rocks should not be contacted with oxygen in the air, thereby preventing the oxidation itself or neutralizing with a neutralizing agent.

Thus, the present invention solved the above problems by coating the coating on the sulfide mineral. That is, when the coating material is sprayed onto the sulfide minerals to coat the rocks containing the sulfide minerals, the rocks are blocked from the air to prevent oxidation. In addition, the coating agent includes a neutralizing agent capable of neutralizing the acid emitted from the sulfide mineral. In the present invention, calcium acts as a neutralizing agent. Sodium or phosphate, which has been used as a conventional neutralizer, may cause secondary contamination by itself, but calcium is preferable because no problem of secondary contamination occurs.

Also important for coatings is their ability to bond with rocks containing sulfide minerals. Since rocks containing sulfide minerals are mostly siliceous, when silicate is used as a coating agent, the bonding strength can be continuously maintained due to the same type of component.

Accordingly, in the present invention, calcium silicate is used as a coating agent in consideration of the above conditions, so that calcium containing sulfide minerals are not exposed to air while calcium acts as a neutralizing agent, and silicate of the same type as the rock containing sulfide minerals is used. Thereby maintaining the bonding force.

In addition, in the present invention, a binder is used to further increase the binding strength between the calcium silicate and the rock containing sulfide minerals. Various materials can be used as the binder, but silica sol is employed in this embodiment.

Silica sol is a gel state, when the amount incorporated into calcium silicate is high, the bonding force may be increased, but there is a problem that the workability is lowered due to the fluidity is low. Appears.

As will be described later, in the present embodiment, silica sol was mixed in a volume ratio of 15 to 60 ml with respect to 1000 ml of calcium silicate by experimental consideration. That is, the volume ratio was determined in consideration of the fluidity and the binding force.

Experiments were conducted on the efficacy of the coating selected in the present invention. Hereinafter, the experimental procedure and results will be described in detail.

First, explain the whole process of the experiment.

As shown in the photograph of Figure 2, acid rock drainage for the experiment or the four geological conditions of the different geological conditions of the probable occurrence of the geological degeneracy gneiss (A, Geopung Mine), Okcheondae waste metal mines, the shale of Samcheok coal field (Gangwon-do) B, Dogye Coal Mine), Cheonmae Rock Formation (C, Geumsan Region), and Altered Ansandstone (D, Forestry Mine) in Busan Paekseok Mine.

In addition, pH1: 2 and EC1: 2 analysis, acid base accounting test (ABA), and net acid generating potential (NAPP) can be used to evaluate salt and free hydrogen ions using the collected samples. Potential) and Net Acid Generation (NAG) evaluations were performed and the results are described below.

Then, four kinds of waste-rock coated samples (1M, 0.5M, 0.1M, four kinds of distilled water) were prepared by varying the concentrations with calcium silicate solution for the calcium silicate coating experiment. Each of the waste-rock was put into 300g each of the waste-rock in the manufactured container, and the size of each waste-rock was divided into three stages (L, M, S) as follows.

L: 9.5 ~ 19.5mm, M: 2 ~ 9.5mm, S: 0.425 ~ 5mm

That is, waste rock was immersed by varying the size of each of the four waste-rock coated samples in one region. Experiments were carried out in 12 beakers in one region, and in 48 beakers because the samples were collected in four regions.

In addition, three sets (Silicasol 5ml, 15ml, 30ml mixed) were prepared in a 600ml beaker to determine the mixing ratio of the silica sol binder, and the mixing test was carried out for the concentration of each calcium silicate (1M, 0.5M, 0.1M, distilled water). And viscosity was also measured. The instrument used for the measurement used BROOKFIELD MODEL DV-Ш + (PROGRAMMABLE RHEOMETER).

In the coating test, put the prepared coating solution so that each sample is sufficiently immersed, and after 24 hours, discard the coating solution and wash it lightly with distilled water. After air drying at 70 ℃, take out after 24 hours and store at room temperature. Place a 5A filter paper into a filterable cylindrical instrument for coating testing and place each sample on it.

Put a beaker underneath to receive the filtered water. After that, distilled water was first weighed 300ml with a beaker containing each ore sample and poured into a cylindrical filter that could be filtered. After 24 hours, the water was collected, the pH and EC were measured, put into a distillation bottle, and 3-5 drops of concentrated nitric acid was added. Put it in the refrigerator. Changes in pH, EC, Ca, Fe, Mn and Na were observed for water samples that passed through waste-rock samples periodically.

The results of the experiment will be described below.

The results of the ABA test of the calcium silicate coating sample are as follows.

As shown in the table of Figs. 3 to 5, the pH1: 2 and EC1: 2 analysis showed a range of 4.04 to 5.58 and 350 to 1030 μS / cm, respectively. The total sulfur content was 0.2 ~ 2.87% with B and C below 1% and A and D above 1%. In the relationship between EC and total sulfur content, it was confirmed that the larger the total sulfur content, the larger the EC1: 2 value.

It can be seen that acid oxidation salts have been formed to some extent by oxidation of sulfide minerals. As shown in the table of FIG. 6, in Sample A having the highest Maximum Producing Acid (MPA) value, 85.68 kgH 2 SO 4 / t was estimated to generate 85.68 kg of sulfuric acid (H 2 SO 4) in one ton of the sample.

The ANC of sample A, the neutralization test result of carbonate minerals, showed a maximum of 9.96 kgH2SO4 / t. Since NAPPs all have positive values, it can be estimated that acid is likely to occur.

The reason why the samples have an acid generating ability is because they contain pyrite in the samples and relatively few minerals, especially carbonate minerals, which neutralize the acid generated by the sulfide mineral. NAGpH has a strong acidity (2.2∼2.7), so the probability of acid rock drainage is high. It is believed that the sulfide minerals contained in each sample contributed to the acid generation of acid rock drainage.

Referring to FIG. 5, all the analyzed samples were classified into potential acid forming (PAF).

The results of the coating test of the calcium silicate coating and the determination of the mixing ratio of the binder will be described.

The silica sol mixing test was performed on the concentration of calcium silicate (1M, 0.5M, 0.1M, distilled water), and the measured viscosity is shown in the table of FIG. 7. From this result, the concentration of the mixed solution for proper coating was determined to be 15 to 60 ml of silica sol based on 1000 ml of calcium silicate, and the determined mixing ratio was as follows.

-Mixing ratio of calcium silicate and silica sol to prevent oxidation

1M = 232g (CaSiO3) + 2000g (water) +50 (silicasol)

0.5M = 116g (CaSiO3)) + 2000g (water) +50 (silicasol)

0.1M = 23g (CaSiO3)) + 2000g (water) +50 (silicasol)

Referring to the table of FIGS. 8 to 11, the waste-rock was maintained at a high pH with respect to the comparative sample, and in particular, S and M samples of calcium silicate 0.5M and 1M concentrations were maintained at pH 6 and up to 3 months. In the case of Ca, it was confirmed that a large amount melted at an early stage, and after that, a small amount was continuously eluted to maintain neutralization ability. In addition, the Fe can be seen that the effect of the coating is very excellent. After elution of the initial residual Na, very little is generated.

In addition, referring to the table of Figures 12 to 15, the pulverized waste-rock was maintained at a high pH for the comparative sample, especially S samples of calcium silicate 0.5M, 1M concentration is maintained at pH 6 or more up to 3 months. In the case of Ca, it was found that a rather large amount was melted at an early stage, and since it was continuously eluted, a small amount was maintained to maintain neutralization ability. In addition, Fe can be seen that the effect of the coating is excellent except for some L, M samples compared to the comparative sample. After elution of the initial residual Na, very little is generated.

Referring to the table of FIGS. 16 to 19, the megalithic waste-rock maintained a high pH with respect to the comparative sample, and especially, S samples of calcium silicate 0.5M and 1M concentrations were maintained at pH 6 or more for 3 months. In the case of Ca, it was found that a rather large amount was melted at an early stage, and since it was continuously eluted, a small amount was maintained to maintain neutralization ability. In addition, very little is generated after the initial elution of Na.

20-23, Geumsan waste-rock maintained a high pH for the comparative sample, especially S samples of calcium silicate 0.5M, 1M concentration is maintained above pH 6 up to 3 months. In the case of Ca, it was found that a rather large amount was melted at an early stage, and since it was continuously eluted, a small amount was maintained to maintain neutralization ability. In addition, Fe can be seen that the coating effect is excellent except for some L samples compared to the comparative sample. After elution of the initial residual Na, very little is generated.

After the coating test, electron microscopic analysis was performed to evaluate the coating condition on the surface of the waste-rock samples. After drying, the specimens were observed for microscopic properties and analyzed for the composition of specific particles by FE SEM-EDX (JetJSM-7000F).

As can be seen in the scanning electron micrograph of FIG. 24, the coating on the surface of each waste-rock was confirmed through partial qualitative analysis.

In summary, as a result of the coating test, the coating effect was maintained after three months in four samples. It was confirmed that most of the samples of calcium silicate 1M and 0.5M rose from pH 3 to pH 6-7. And FE-SEM analysis confirmed the coating on the surface of the waste-rock containing sulfide minerals.

As in the present invention, it was confirmed that calcium silicate was effective as a coating agent to inhibit the source control, that is, generation of acidic rock drainage itself.

By using calcium silicate as a coating material, the above coating is applied to the area where the rock containing sulfide minerals such as waste rock deposit or abandoned mine is concentrated, and the sulfurized mineral is oxidized from the rock containing the sulfide mineral to generate acidic drainage. Can be prevented.

More specifically, as shown in FIG. 1, when the present coating is applied to a surface layer such as waste rock deposit or mining, the coating (c) is coated on the surface of rock (s) containing sulfide minerals. If the coating material is sprayed only from the surface layer portion of the mining or waste-rock pile to a certain depth, the desired effect is exerted in the present invention, and the deep layer portion of the stock pile is blocked from contact with air so that no oxidation occurs.

That is, in the present invention, the calcium silicate coating material is sprayed on the waste-rock storage or the mining surface to cover the sulfide minerals that can come into contact with air to prevent oxidation, and even though some oxidation proceeds, calcium acts as a neutralizing agent to generate acidic rocks Do not In addition, even when the coating agent is applied only to the surface layer of the mining area, the rocks in the deep portion are blocked from contact with air, thereby obtaining a desired effect in the present invention.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, it is merely an example, and those skilled in the art may realize various modifications and equivalent other embodiments therefrom. I can understand. Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.

Claims (6)

In order to prevent the sulfide minerals from being exposed to the outside by coating a rock containing the sulfide minerals by spraying a coating on a region in which rocks containing sulfide minerals are concentrated.
The coating agent is calcium silicate containing calcium,
The coating agent includes silica sol as a binder to improve the binding force between the rock containing the sulfide mineral and the calcium silicate, wherein the coating agent is a volume ratio of 15 to 60 ml relative to 1000 ml of the calcium silicate. Mix,
The area in which the rocks containing the sulfide minerals are concentrated is mined or waste-rock stock of the abandoned mine, and the coating agent is sprayed on the surface layer of the mined or waste-rock stockyard. delete delete delete delete delete

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