Abstract: A method of coating a calcium carbonate film. In one aspect, the method includes preparing a calcium aqueous solution by adding a calcium-containing material to distilled water; forming a calcium carbonate film on a surface of the calcium aqueous solution by leaving the calcium aqueous solution; placing the calcium carbonate film on a substrate; and forming a calcium carbonate coating film by leaving the calcium carbonate film on the substrate.

Abstract: Provided is a surface modification method of calcite powder prepared from desulfurized gypsum and heat-treated at a high temperature. According to the surface modification method, hydrophilic calcite powder having polarity may be changed into hydrophobic non-polar calcite powder by safely adsorbing a surface modifier onto a surface of the calcite powder and coating the surface with non-polar fatty acid. Particularly, in the case in which calcite powder heat-treated at a high temperature is hydrophobized, a significantly excellent hydrophobic surface property may be implemented.

Abstract: Disclosed is a method of preparing calcium carbonate using a direct carbonation reaction. The method includes dissolving fuel gas desulfurization gypsum into an ammonia solution, performing a filtering process after making a carbonation reaction by feeding carbon dioxide into the ammonia solution in which the fuel gas desulfurization gypsum is dissolved, and performing a filtering process after precipitating the calcium carbonate by maintaining a filtered solution in a stationary state.

Abstract: A method of coating a calcium carbonate film. In one aspect, the method includes preparing a calcium aqueous solution by adding a calcium-containing material to distilled water; forming a calcium carbonate film on a surface of the calcium aqueous solution by leaving the calcium aqueous solution; placing the calcium carbonate film on a substrate; and forming a calcium carbonate coating film by leaving the calcium carbonate film on the substrate.

Abstract: Disclosed is a method of detoxifying asbestos of waste slate. The method includes concentrating the asbestos by introducing hydrochloric acid aqueous solution into waste slate powder to dissolve and remove a limestone component contained in the waste slate; and mixing the concentrated asbestos with oxalic acid and performing a low-temperature heat treatment. The waste slate is crushed and pulverized and powder of the crushed and pulverized waste slate is formed in a size in a range of 100 meshes to 300 meshes. The detoxified asbestos includes re-crystallized magnesium oxalate having a rhombohedral or amorphous shape.

Abstract: Disclosed is a method of detoxifying asbestos by using a room-temperature recrystallization scheme. The method includes heat-treating a rock or slate containing asbestos; and putting the heat-treated rock or slate in an aqueous solution, to which organic acid is added, to allow the heat-treated rock or slate to react with the aqueous solution having the organic acid.

Abstract: Provided is a method of recycling a high purity ammonium sulfate aqueous solution including: adding slurry obtained by mixing water, aqueous ammonia, and gypsum with each other and a predetermined amount of carbon dioxide to a reactor to performing a carbonation reaction, wherein an ammonium sulfate aqueous solution produced in the reactor is circulated in the reactor.

Abstract: Disclosed is a method of removing asbestos from an asbestos-containing material by 99% through low temperature heat treatment. The method includes mixing an asbestos-containing material with an oxalic acid at a weight ratio in a range of 1:0.002 to 1:1 and performing heat treatment with respect to a mixture at a temperature of 90° C. to 110° C. to remove asbestos from the asbestos-containing material by 99% or more.

Abstract: Provided is a method of synthesizing high-purity calcite capable of controlling a grain size thereof, by reacting an aqueous calcium chloride solution with CO2 gas under strong alkaline condition, to crystallize into white and ultra-fine grain calcite. The method of synthesizing fine-grain calcite according to the present disclosure can decrease super-saturation by producing calcite under the strong alkaline conditions, thereby suppressing generation and growth of grain, resulting in controlling the grain size. Therefore, the above method is useful in producing high-purity ultra-fine grain calcite and can control the grain size of calcite from several hundreds of nanometers to several tens of nanometers by regulating the concentration of an aqueous caustic soda solution.

Abstract: Disclosed is a method of detoxifying asbestos by using a room-temperature recrystallization scheme. The method includes heat-treating a rock or slate containing asbestos; and putting the heat-treated rock or slate in an aqueous solution, to which organic acid is added, to allow the heat-treated rock or slate to react with the aqueous solution having the organic acid.

Abstract: Disclosed is a method of preparing calcium carbonate using a direct carbonation reaction. The method includes dissolving fuel gas desulfurization gypsum into an ammonia solution, performing a filtering process after making a carbonation reaction by feeding carbon dioxide into the ammonia solution in which the fuel gas desulfurization gypsum is dissolved, and performing a filtering process after precipitating the calcium carbonate by maintaining a filtered solution in a stationary state.

Abstract: Disclosed is a method of detoxifying asbestos of waste slate. The method includes concentrating the asbestos by introducing hydrochloric acid aqueous solution into waste slate powder to dissolve and remove a limestone component contained in the waste slate; and mixing the concentrated asbestos with oxalic acid and performing a low-temperature heat treatment. The waste slate is crushed and pulverized and powder of the crushed and pulverized waste slate is formed in a size in a range of 100 meshes to 300 meshes. The detoxified asbestos includes re-crystallized magnesium oxalate having a rhombohedral or amorphous shape.

Abstract: Disclosed is a method of removing asbestos from an asbestos-containing material by 99% through low temperature heat treatment. The method includes mixing an asbestos-containing material with an oxalic acid at a weight ratio in a range of 1:0.002 to 1:1 and performing heat treatment with respect to a mixture at a temperature of 90° C. to 110° C. to remove asbestos from the asbestos-containing material by 99% or more.

Abstract: Provided is a method for fixing carbon dioxide, the method includding: pulverizing furnace slag; mixing water and the furnace slag such that the furnace slag is present in a concentration of 5˜15 parts by weight based on 100 parts by weight of water; adding NaOH to the mixture; and supplying carbon dioxide to the decomposed mixture, and then carrying out a hydrothermal reaction, so that carbon dioxide can be stably fixed; the treatment of the furnace slag can lead to ecofriendly effects; and the use of the furnace slag can lead to production of carbonate minerals as the final product.

Abstract: A method for extracting rare earth elements from monazite is disclosed. The method includes milling a mixture of monazite including phosphates and rare earth elements and sodium hydroxides inside a mill containing a plurality of balls to form powder by colliding the mixture into balls with each other, converting the mixture into rare earth hydroxides and sodium phosphates through the reaction occurring in the process of repeated collision, and extracting rare earth elements from the powder.

Abstract: Provided is a method of synthesizing high-purity calcite capable of controlling a grain size thereof, by reacting an aqueous calcium chloride solution with CO2 gas under strong alkaline condition, to crystallize into white and ultra-fine grain calcite. The method of synthesizing fine-grain calcite according to the present disclosure can decrease super-saturation by producing calcite under the strong alkaline conditions, thereby suppressing generation and growth of grain, resulting in controlling the grain size. Therefore, the above method is useful in producing high-purity ultra-fine grain calcite and can control the grain size of calcite from several hundreds of nanometers to several tens of nanometers by regulating the concentration of an aqueous caustic soda solution.

Abstract: A method for extracting rare earth elements from monazite is disclosed. The method includes milling a mixture of monazite including phosphates and rare earth elements and sodium hydroxides inside a mill containing a plurality of balls to form powder by colliding the mixture into balls with each other, converting the mixture into rare earth hydroxides and sodium phosphates through the reaction occurring in the process of repeated collision, and extracting rare earth elements from the powder.

Abstract: A method is developed for fabrication of an ammonia gas adsorbent using Fe-zeolite. This method uses Fe-zeolite obtained from municipal waste slag to prepare a gas adsorbent, thereby reusing molten slag as a specified waste so as to improve the value of the waste. To achieve the purpose, the method includes mixing Fe-zeolite powder with a forming adjuvant to prepare a mixture; adding a forming agent to the mixture to obtain a granular Fe-zeolite product; and drying and calcining the obtained granular Fe-zeolite product. Therefore, Fe-zeolite obtained from molten slag as a waste product can be reused as an ammonia gas adsorbent.