TWI631091B - A method of modifying alkaline solid wastes as green construction materials - Google Patents

Abstract

The invention relates to an exhaust gas containing a carbon dioxide source, which is mixed with an alkaline solid waste in a liquid phase solution to reduce the activity and alkalinity of the solid waste, thereby achieving the purpose of reforming and restoring waste, and the invention is helpful The solid waste after the reaction can be directly used as a green building material. The invention comprises a liquid phase injection step, an alkaline solid waste input step, a mixing step, a carbon dioxide source injection step, a reaction step, a separation step, and a green building material step. The invention is different from the traditional stabilization method using high temperature and high pressure steam or long-time weathering procedure, and directly uses an exhaust gas containing a carbon dioxide source to reform and stabilize the alkaline solid waste to ensure the solid waste after stabilization. As a green building material, it will improve the phenomenon of avoiding the volume expansion of building materials in the future.

Description

Method for upgrading alkaline solid waste as green building materials

The invention relates to a method for upgrading alkaline solid waste as a green building material; in particular to a method for mixing and reacting with a basic solid waste in a liquid phase solution by using a gas containing a carbon dioxide source to reduce the alkalinity of the solid waste. The solid waste after the reaction can be directly used as green building materials.

Alkaline solid waste (eg, steelmaking furnaces, fly ash, etc.) is often a by-product of the plant or power plant. Because the alkaline solid waste is similar to natural sandstone, it has the characteristics of wear resistance, high temperature resistance and corrosion resistance. It is suitable to replace the natural sand used in civil engineering. It has deep resource reuse benefits and can be applied as, for example, building materials. , roadbed paving, bricks and other ingredients.

The method of preparing concrete from solid waste, the concrete produced and the method for recovering solid waste disclosed in the Republic of China Patent No. 201507990, which is disclosed in the Japanese Patent No. 201507990, the invention is a solid For the method of preparing concrete by waste, a de-alkali reagent is mixed in the test body, and a maintenance procedure is carried out to form concrete for civil engineering construction.

However, most of the alkaline solid waste contains about 1-10% of free calcium oxide (Free-CaO) and calcium hydroxide (Ca(OH) ₂ ) and other active substances, which may cause "high alkalinity" when used in resource utilization. In the case of "unstable volume" and other difficulties, it is necessary to undergo "enhanced" upgrading treatment to remove the active substances contained in it to avoid serious work safety problems such as roadbed expansion and rupture or loose foundation.

Investigating, in November 1, 2010, the "Recycling Stone Resource Recycling Method by the Wet Grinding Method" disclosed in the Republic of China Patent No. 201038741 A1, the invention is directed to an unsteady furnace It is wet-ground into a slurry to carry out the stabilization step. After the treatment, the slurry can be directly mixed and applied to concrete engineering.

Commercialized alkaline solid waste stabilization technology has been put into operation, such as: outdoor natural health method, high pressure steam regimen, atmospheric pressure steam regimen, HK water quenching granulation method, stuffing tank method, roller method, and modification The mass method and the like can remove active substances in alkaline solid waste, such as free calcium oxide and calcium hydroxide. However, taking the outdoor natural health method as an example, the furnace is directly stacked outdoors, and the carbon dioxide and water vapor (or rainwater) in the atmosphere are used to hydrate the alkaline solid waste, which takes a long time and requires a large area. Dealing with the site, and easily causing dust in the plant area, it is difficult to carry out large-scale processing. Taking the atmospheric pressure steam curing method as an example, the alkaline solid waste is placed in the storage pit and then covered with canvas, and the alkaline solid waste is made by pressurized steam (pressure is about 1 kg/cm ² and temperature is maintained above 100 ° C). Reacts with steam. The above methods still convert free calcium oxide to hydroxide, while the hydroxide is still in an unstable state and often requires additional energy or chemicals. Although such technologies contribute to the prior art, their technical means and functions still have room for improvement.

Based on the above, it has been found that the alkaline solid waste stabilization technology in the past, if it is dumped in the factory or outdoors, takes a long time or a large area, and is easy to cause dust and air pollution problems, the active material can not be completely stabilized; Technology still consumes a lot of energy resources, such as: chemical drugs Agents, water resources, pressurized steam, etc. Therefore, the cost of such alkaline solid waste treatment is high and does not meet the "green technology" principle.

The object of the present invention is to provide a novel green technology for upgrading alkaline solid waste as "green building materials", characterized in that a waste gas containing a carbon dioxide source is used to react with alkaline solid waste in a liquid medium. In order to stabilize the active substances in the alkaline solid waste, it is ensured that the solid waste after stabilization is suitable as a green building material, and the phenomenon of avoiding the volume expansion of the building materials in the future is improved. The solid product component treated by the invention is similar to natural ore, and is a stable material, which can be applied to construction engineering, as a green building material, providing environmental and economic benefits, and achieving the concept of circular economy.

The invention provides a method for upgrading an alkaline solid waste as a green building material, and referring to FIG. 1 , which comprises a liquid phase injection step (11), an alkaline solid waste input step (12), and a mixing step (13). The carbon dioxide source is injected into step (14), reaction step (15), separation step (16) and as green building step (17). The invention provides a method for upgrading alkaline solid waste as a green building material, which can be modified and stabilized for various alkaline solid wastes with wide application range, avoiding the use of high temperature and high pressure steam in the traditional stabilization program, and is effective Reduce the use of energy resources; at the same time, the solid product composition after the reaction is similar to natural ore, which can be used as a green building material in construction projects, providing additional environmental and economic benefits. Wherein, the liquid phase injection step (11) and the alkaline solid waste are introduced into the step (12), and the mixing step (13) is carried out to form a mixture having a liquid-solid weight ratio of 1:1 to 50:1. The mixture is highly alkaline. Then, a carbon dioxide source injection step (14) is performed, and the carbon dioxide source can be exhausted from a chimney, a hot blast stove, a combustion furnace, and the like to carry out a reaction step (15) to reform the stabilized alkaline solid. Waste. Finally, the liquid-solid separation is carried out by the separation step (16), and the stabilized solid waste obtained can be used for resource utilization, for example, cement blending, etc., as a green building material step (17).

The invention can carry out the stabilization of the alkaline solid waste under normal temperature and normal pressure, and is different from the traditional pressurized steam health method, and does not require additional chemical injection (for example, alkali removal reagent), and directly uses the flue. Carbon dioxide in the gas, as a reactant for the stabilization of alkaline solid waste, conforms to the principle of green chemistry. Highly active ingredients in alkaline solid waste, such as free calcium oxide, free magnesium oxide, calcium hydroxide, magnesium hydroxide, etc., can be dissolved and dissociated in liquid medium, converted into calcium or magnesium ions, and then in the exhaust The carbon dioxide component reacts to form a stable carbonate precipitate to achieve the purpose of upgrading and stabilizing the alkaline solid waste.

Therefore, the method of the invention avoids the high temperature/high pressure steam means using the traditional stabilization program, and directly uses the relatively low temperature/low pressure carbon dioxide source exhaust gas, effectively reforms the alkaline solid waste, stabilizes the active substance therein, and reacts The product can be used as a green building material to provide environmental benefits and reduce the cost of energy resources.

11‧‧‧ Liquid injection step

12‧‧‧Alkaline solid waste input steps

13‧‧‧mixing steps

14‧‧‧ Carbon dioxide source injection step

15‧‧‧Reaction steps

16‧‧‧Separation steps

17‧‧‧ as a green building step

Figure 1 is a schematic flow diagram of the present invention.

Fig. 2 is a schematic view showing the contents of free calcium oxide and calcium hydroxide contained in solid wastes of "untreated A" and "process B after treatment" according to an embodiment of the present invention.

Before the present invention is described in detail, it should be noted that in the following description, Similar elements are denoted by the same reference numerals.

The invention will be further illustrated by the following examples insofar as they are of ordinary skill in the art to which the invention pertains. It is understood that the following examples are for illustrative purposes only and are not to be construed as limiting.

Referring to FIG. 1 , the present invention relates to a method for using a carbon dioxide source-containing gas modified alkaline solid waste as a green building material, comprising the steps of: a liquid phase injection step (11), and a solid waste input step. (12), a mixing step (13), a carbon dioxide source injection step (14), a reaction step (15), a separation step (16), and a green building material step (17).

1. In the liquid phase injection step (11): the liquid medium is injected into the temporary storage tank through the pumping device. Such liquid mediums are, for example but not limited to, tap water, industrial process inorganic wastewater, concentrated brine, and the like. The temporary storage tank can be, but not limited to, a cylindrical storage tank, an aerated reaction tank, a mud reaction tank, and the like.

2. In the alkaline solid waste input step (12), the solid solid waste is put into a temporary storage tank through a solid conveying device, and the ratio of the liquid medium to the alkaline solid waste is liquid-solid ratio. 1:1 to 50:1. Such alkaline solid wastes are, for example but not limited to, steel furnaces (eg, blast furnace crucibles, converter crucibles, refining crucibles, desulfurization crucibles, electric arc furnaces, antimony oxides, reduction crucibles, etc.), furnace ash (eg, fly ash, bottom) Ash, dust, etc.).

3. In the mixing step (13): the alkaline solid waste is charged into the liquid-solid mixture obtained in the step (12), and the solid waste can be mixed with the liquid medium through the stirring device. Evenly mixed in the temporary storage tank.

In the carbon dioxide source injection step (14), the exhaust gas containing the carbon dioxide source is introduced into the slurry temporary storage tank through the air blower. Such a carbon dioxide-containing exhaust gas is a chimney exhaust, such as, but not limited to, hot air furnace exhaust, combustion furnace exhaust, incinerator exhaust, and the like. The exhaust gas temperature of such a carbon dioxide source may be between 50 ° C and 500 ° C, the gas pressure may be between 1.0 atm and 2.0 atm, and the carbon dioxide concentration in the exhaust gas may be from 3 vol. % to 50 vol. %. The gas injection device can be, but is not limited to, a gas disperser, an aeration device, a stirring device, and the like.

In the reaction step (15), the carbon dioxide source is injected into the carbon dioxide source exhaust gas of the step (14), and the uniform liquid solid mixture obtained in the mixing step (13) is dispersedly contacted in the temporary storage tank. Alkaline solid waste is upgraded.

In the separating step (16), the solid waste slurry obtained by the reaction step (15) is subjected to liquid-solid separation, wherein the solid waste should be properly stabilized after the reaction, and the active substance is, for example, not It is limited to free calcium oxide, free magnesium oxide, calcium hydroxide, magnesium hydroxide and the like which have been effectively removed.

As a green building material step (17): the obtained solid waste can be used as a green building material, for example, but not limited to aggregates, auxiliary cement bonding materials, and the like. Since the active substance in the alkaline solid waste reacts with carbon dioxide to form a carbonate precipitate, the modified solid waste is added to the building material without causing the material volume to be unstable in the future. The weight percentage of the solid waste contained in the green building materials may range from 0% to 50%.

Please refer to FIG. 2, in which the untreated A and the "alkali" of the present invention are described in the present embodiment. Comparison of the active substance composition in the solid waste treated with B as a method of green building materials. It can be found that the solid waste of untreated A contains some free calcium oxide and calcium hydroxide, and the contents are 11.4% and 3.4%, respectively; however, after treatment B of the invention, free calcium oxide and hydroxide in the solid waste The calcium content was effectively reduced to 0.1% and 0.1%, respectively. It can be seen that, in combination with the method of modifying the alkaline solid waste of the present invention as a green building material, the solid waste is reformed and stabilized, and the solid waste active material can be effectively reduced to achieve the physicochemical property improvement benefit, which is beneficial to the same. Later applied as a green building material.

Claims (3)

A method for upgrading alkaline solid waste as a green building material, characterized in that an exhaust gas containing a carbon dioxide source is used to react with an alkaline solid waste in a liquid medium to stabilize the activity in the alkaline solid waste. The substance ensures that the solid waste is suitable as a green building material after the stabilization, and the phenomenon of avoiding the volume expansion of the building materials in the future is improved. The weight percentage of the solid waste contained in the green building materials may range from 0% to 50%. As a method of green building materials as described in claim 1, the exhaust gas temperature may be between 50 ° C and 500 ° C, and the exhaust pressure may be between 1.0 atm and 2.0 atm. As a method of green building materials as described in claim 1, the concentration of carbon dioxide in such exhaust gas may be from 3 vol.% to 50 vol.%.