KR102283099B1 - Method for manufacturing brick using mine drainage sludge - Google Patents

Abstract

The present invention relates to a method for manufacturing bricks using mine drainage sludge. The method for manufacturing bricks using mine drainage sludge according to the present invention includes the steps of: (a) drying the mine drainage sludge; (b) mixing the dried sludge with pumice stone and cement to form a mixture; (c) adding water to the mixture; (d) compressing and molding the mixture to which water is added to manufacture a brick molded body; and (e) drying the brick molded body.

Description

{Method for manufacturing brick using mine drainage sludge}

The present invention relates to a technology for recycling waste, and more particularly, to a method for manufacturing bricks using sludge generated in the process of purifying mine drainage.

Mine wastewater discharged from the mine shafts of abandoned and abandoned mines is acidic and has a high concentration of heavy metals, so purification treatment is required. Purification treatment is divided into active treatment and passive treatment. Active treatment methods include pH control using a neutralizing agent, ion exchange, adsorption, coagulation, filtration, and the like, and include reverse osmosis, ion exchange, and electrodialysis. As a passive treatment method, neutralization treatment using limestone such as ALDs (anoxic limestone drains) and OLD (oxic limestone drains), aerobic and anaerobic artificial marshes, and SAPS (successive alkalinity-producing systems) or RAPS, etc. there is.

In Korea, passive processing using SAPS is mainly used. Recently, the semi-active method, which introduced the concept of active treatment at the level of adding a neutralizing agent to the passive treatment method, is gradually being applied, and active treatment is continuously increasing for mine drainage with a high pollution load. is the trend

The purification treatment goes through several processes, one of which is to oxidize and precipitate metals in the mine drainage to remove them. For this purpose, most treatment facilities are provided with sedimentation tanks. 1 shows an actual photograph of the settling tank. The photo-acid drainage stays in the sedimentation tank for a certain period of time, and the metal ions dissolved in the acid-acid drainage are precipitated in the sedimentation tank in the form of oxides and hydroxides. In addition, the soil components that have moved along with the mine drainage are also precipitated in the sedimentation tank to form sludge.

In the sedimentation tank, solid-liquid separation is performed by its own weight, so that sludge is accumulated at the bottom and water floats at the top. Sludge is pumped and discharged through a dewatering process. Some are recycled as auxiliary materials for cement, but most are disposed of in landfills. There is a problem that reclamation itself is not only an environmental burden, but also the cost of reclamation is gradually increasing due to the lack of a landfill space.

The present invention is to solve the above problems, and an object of the present invention is to provide a method for recycling the mine drainage sludge as a material for bricks.

On the other hand, other objects not specified in the present invention will be additionally considered within the range that can be easily inferred from the following detailed description and effects thereof.

Brick manufacturing method using the mine drainage sludge according to the present invention for achieving the above object comprises the steps of: (a) drying the mine drainage sludge; (b) mixing the dried sludge with pumice and cement to form a mixture; (c) adding water to the mixture; (d) preparing a brick molded body by compressing and molding the mixture to which water is added; and (e) drying the brick molded body; It is characterized by including

According to the present invention, the mine drainage sludge is dried until the moisture content is formed in the range of 20 to 30%.

In one example of the present invention, the mixture may be formulated in the range of 30-50 wt% of acid mine drainage sludge, 20-30 wt% of pumice, and 30-40 wt% of cement. The water added to the mixture ranges from 5 to 15% by weight in total.

In one example of the present invention, the particle size of the mine drainage sludge and the pumice stone through the sieve is preferably formed to be 5mm (4mesh) or less.

On the other hand, in another example of the present invention (a) drying the mine drainage sludge; (b) mixing the dried sludge with pumice and cement to form a mixture; (c) adding water and an organic binder to the mixture; (d) preparing a brick molded body by compressing and molding the mixture; (e) heating and calcining the brick molded body at 1100-1300°C; and (f) cooling the fired brick compact.

The brick according to the present invention has the advantage of being eco-friendly as well as improving the economic feasibility of manufacturing bricks by recycling by-products that must be disposed of as using mine drainage sludge.

Above all, it is expected that the bricks made by the present invention can be applied to buildings by exhibiting physical properties that far exceed the KS standards in terms of compressive strength and water absorption.

On the other hand, even if it is an effect not explicitly mentioned herein, it is added that the effects described in the following specification expected by the technical features of the present invention and their potential effects are treated as described in the specification of the present invention.

1 is an actual photograph of a sedimentation tank of a mine drainage treatment facility.
2a and 2b are schematic flowcharts of a brick manufacturing method using the mine drainage sludge according to an example of the present invention, respectively.
3 is an actual photograph of a brick manufactured by the present invention.
Figure 4 is a surface electron micrograph of the brick manufactured by the present invention.
5 is a cross-sectional electron micrograph of the brick manufactured by the present invention.
6 is a compressive strength test report of the brick manufactured by the present invention.
7 is a water absorption test report of the brick manufactured by the present invention.
※ It is revealed that the accompanying drawings are exemplified as a reference for understanding the technical idea of the present invention, and the scope of the present invention is not limited thereby.

In the description of the present invention, if it is determined that the subject matter of the present invention may be unnecessarily obscured as it is obvious to those skilled in the art with respect to related known functions, the detailed description will be omitted.

Hereinafter, with reference to the accompanying drawings, the brick manufacturing method using the mine drainage sludge according to an example of the present invention will be described in more detail.

2a and 2b are schematic flowcharts of a brick manufacturing method using the mine drainage sludge according to an example of the present invention, respectively.

The object to be recycled in the present invention is sludge generated from a mine drainage purification treatment facility. Mine wastewater purification and treatment facilities are very diverse, and the sludge used as the material of the present invention can use all sludge generated from the purification treatment facility regardless of treatment methods such as active treatment, passive treatment, and semi-active treatment. That is, the treatment method of the purification treatment facility itself is not important, but rather the property of the sludge.

The mine drainage sludge subject to the present invention has a metal as a main component, and in particular, the content of iron (mainly iron hydroxide) exceeds 40% by weight. For example, the sludge used in this embodiment contains Fe 51.2%, Ca 22.7%, Al 8.7%, and Mg 6.9% as main components, and the balance contains Mn, Cu and other impurities in an amount of 10 wt% or less.

Most of the mine drainage sludge is pumped from what is accumulated in the lower part of the settling tank.

Accordingly, in the present invention, the water content is lowered by first dewatering and drying the sludge. In this example, the drying process is continued until the moisture content of the sludge is 20-30% (wt%). The drying process is either natural drying or using a hot air agitator, and the moisture content of the sludge after drying is very important. Conversely, if the moisture content is less than 20%, the amount of water supplied for proper agglomeration increases during the mixing process, and thus it may re-agglomerate. In addition, when the moisture content is low, it is not preferable because secondary environmental problems caused by fine dust occur.

After drying, the sludge, pumice and cement are mixed to form a mixture.

In this example, the blending ratio of the mixture is in the range of 30 to 50% by weight of sludge, 20 to 30% by weight of pumice, and 30 to 40% by weight of cement. More specifically, in this example, 45% by weight of sludge, 20% by weight of pumice, and 35% by weight of cement were used.

The pumice stone used in this example is fine powder or gravel generated during tailing in a mine, and is very similar to the raw material of general cement. The pumice stone used in this example contains Fe 60.4%, Al 23.6%, Ca 7.3%, and Mg 5.6% as main components, and the remaining 3wt% or less of Mn, Cu and other impurities, and pores are developed. Cement is usually Portland cement.

Pumice forms the basic matrix of the final manufactured brick, and cement functions as a binder to unite the pumice particles, and, like sludge, it fills the pores of the pumice stone. Sludge is generally formed into much smaller particles than pumice. The mine drainage sludge is filled in the pores developed in the pumice stone to seal the finally manufactured bricks, thereby improving the mechanical strength.

If the sludge is used more than the above range, the content of pumice is reduced, which is not desirable for the expression of mechanical strength of bricks, the strength of the molded body is reduced, and the shape stability during brick molding is reduced. Conversely, if the content of sludge is less than the above range, it is not desirable for mechanical strength expression because it is insufficient to fill the pores of the pumice stone.

After mixing the sludge, pumice stone and cement as described above, they are pulverized and sieved to control the particle size. Of course, the sludge and pumice stone may be mixed with other materials after grinding and sieving in advance, and grinding and sieving may be performed after making the mixture as in this example. Filter the mixture using a 4 mesh sieve and use only those with a particle size of 5 mm or less. Since sludge has a very small particle size, the main reason for sieving is to adjust the particle size of pumice. If the particle size of the pumice stone is made larger, the specific surface area becomes rather small and the pores exposed to the outside are limited, so the filling by the sludge is also reduced, and there is a limit in improving the mechanical strength. In addition, if the particle size is not uniform, the quality of the brick is deteriorated because water absorption increases. Therefore, in this example, the particle size of the mixture including pumice is adjusted to 5 mm or less.

After the mixture is complete, add water to form a dough, and prepare bricks. Water is formulated at a level of 10% by weight in total based on after addition. When it is kneaded through water, the above mixture is put into a press mold and press-molded to form a brick. By drying the molded body in the air, the brick is finally completed. Curing is approximately 7 days or more.

3 is an actual photograph of the finally completed brick, FIG. 4 is a surface electron micrograph of the brick manufactured by the present invention, and FIG. 5 is a cross-sectional electron microscope photograph of the brick manufactured by the present invention. Referring to the electron micrographs of FIGS. 4 and 5 , it can be seen that the material is tightly filled without pores on the surface and fracture surfaces of the bricks.

Meanwhile, in order to increase the hardness according to the intended use of the brick, a firing process is additionally required as in the embodiment of FIG. 2B . That is, after the mixture is completed, water and an organic binder (ex: clay-based binder) are added to form a dough, prepare bricks, put the mixture in a press mold, and press mold to make bricks. After that, the temperature is gradually raised to below 5°C per minute, calcined at a temperature of 1100°C to 1300°C for 0.5 to 1 hour, and then air-cooled to complete the bricks.

Hereinafter, bricks were manufactured according to the present invention and physical properties were tested.

The raw material, mine drainage sludge, was generated at the Hamtae water purification facility in Taebaek-si, Gangwon-do. The sludge has a moisture content of about 80%, and is dried using a mechanical device and wind in a state of agglomeration similar to the clay component, and the moisture content is made into a state of 20-30%. Prepare pumice that has been processed to a particle size of 4 mesh or less. After making a mixture by mixing 45wt% of sludge, 20wt% of pumice, and 35wt% of cement, add about 10wt% of water to make a dough. After uniaxial pressure molding at a pressure of 15 MPa and dried, a molded article was prepared. At this time, the size of the molded body is 250 × 100 × 150 mm. After curing the molded article for 10 days, it was air-cooled, and finally bricks were manufactured as shown in the photo of FIG. 3 .

For the bricks made in this way, the compressive strength and water absorption required for the physical properties of the bricks were tested according to the KS standard.

- Compressive strength

For bricks, the compressive strength was tested according to the test method specified and specified in the Korean Industrial Standard KS L 8510. Compressive strength can be obtained as C=W/A(N/mm2), C is compressive strength (N/mm2), pressurized shear area (mm2), and W is the maximum load (N), respectively. The specimen was smooth finished so that both sides of the pressurized surface were perpendicular to the longitudinal axis of the specimen brick, and the entire surface was evenly pressurized, followed by a compressive strength test. As a result of measuring five specimens through an authorized analysis institute, as shown in FIG. 6 , the compressive strength was much higher than the standard compressive strength (8N/㎟) of the by-lime brick in KS L 8510, and was 10 to 17N/㎟. It was confirmed that the compressive strength was very good.

- Absorption rate

The water absorption rate can be calculated as M = (m0-m1)/m1 (%), where M is the water absorption rate (%), m0 is the surface water mass of the specimen (g), and m1 is the dry mass of the specimen. The test specimen is tested by smoothing both sides of the pressurized side so that it is perpendicular to the vertical axis of the specimen brick, and immersing it in clear water for 2 hours or more for absorption. As a result of measuring the five specimens by an authorized analytical institution in this way, as shown in FIG. 7 , the absorption rate was 5 to 9%, which was much lower than the absorption rate (10% or less) based on the by-product lime brick.

The above is the test result for bricks that have not undergone firing. Naturally, the compressive strength is expected to increase further when fired, and the absorption rate is expected to be formed at a level similar to that of the above experiment.

That is, it was confirmed that the bricks made by the present invention can be applied to buildings by exhibiting physical properties that far exceed the KS standards in terms of compressive strength and water absorption. In addition, the brick according to the present invention has the advantage that it can be manufactured very economically by using a by-product of a mine.

The protection scope of the present invention is not limited to the description and expression of the embodiments explicitly described above. In addition, it is added once again that the protection scope of the present invention cannot be limited due to obvious changes or substitutions in the technical field to which the present invention pertains.

Claims (6)

(a) drying the mine drainage sludge;
(b) mixing the dried sludge with pumice stone and cement to form a mixture;
(c) adding water to the mixture;
(d) preparing a brick molded body by compressing and molding the mixture to which water is added; and
(e) drying the brick molded body; including,
The mixture is 30 to 50% by weight of the mine drainage sludge, 20 to 30% by weight of pumice, and 30 to 40% by weight of cement. According to claim 1,
The method for manufacturing bricks using the mine drainage sludge, characterized in that the mine drainage sludge is dried until the moisture content is formed in the range of 20 to 30%. delete According to claim 1,
A method for manufacturing bricks using mine drainage sludge, characterized in that the particle size of the mine drainage sludge and pumice stone is formed to be 5 mm (4 mesh) or less through a sieve. According to claim 1,
Brick manufacturing method using the mine drainage sludge, characterized in that the water added to the mixture is in the range of 5 to 15% by weight of the total. (a) drying the mine drainage sludge;
(b) mixing the dried sludge with pumice stone and cement to form a mixture;
(c) adding water and an organic binder to the mixture;
(d) preparing a brick molded body by compressing and molding the mixture;
(e) heating and calcining the brick molded body at 1100-1300°C; and
(f) cooling the fired brick compact;
The mixture is 30 to 50% by weight of the mine drainage sludge, 20 to 30% by weight of pumice, and 30 to 40% by weight of cement.

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