Solidifying agent

Abstract

We will make effective use of discarded gypsum board. [Solution] The solidifying agent comprises 45% to 65% by weight of hemihydrate gypsum, 5% or more by weight of water purification sludge, and quicklime, slaked lime, or cement. Preferably, the hemihydrate gypsum is derived from discarded gypsum board, and the fine-grained soil is dried water purification sludge. This allows a relatively large amount of hemihydrate gypsum to be reused as part of the solidifying agent, which is expected to improve the recycling rate of gypsum board, given the current situation where the recycling of discarded gypsum board is not progressing. Furthermore, the water purification sludge can also be reused.

Description

Technical Field

[0001] The present invention relates to a solidifying agent.

Background Art

[0002] For example, in Patent Document 1, in the reuse of a waste gypsum board in which both sides of a core material of gypsum are covered with base paper for boards, the whole is pulverized and dried in a state where the base paper for boards remains integrated with the core material without separating the base paper from the core material, and a method for reusing the waste gypsum board as an improver for sludge is disclosed. Further, Patent Document 2 discloses an additive for soil granulation containing 100 parts by mass of an inorganic powder and 0.01 to 50 parts by mass of a thickening material, wherein the inorganic powder preferably has a Blaine specific surface area of 1500 g / cm 2 or more, and is one or more selected from calcium carbonate powder, hemihydrate gypsum, anhydrous gypsum, bentonite, zeolite, silica powder, coal ash, shale powder, sepiolite, activated carbon, activated clay, diatomaceous earth, and dolomite.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to effectively utilize gypsum. In particular, an object is to effectively utilize waste gypsum boards.

Means for Solving the Problems

[0005] The solidifying agent according to the present invention comprises 45% to 65% by weight of hemihydrate gypsum, 5% or more by weight of fine-grained soil, and quicklime or cement. For example, given the current situation where the recycling of discarded gypsum boards is not progressing, it is expected that the recycling rate of gypsum boards can be improved by reusing a relatively large amount of hemihydrate gypsum as part of the solidifying agent.

[0006] Preferably, the hemihydrate gypsum is derived from gypsum board.

[0007] Preferably, the hemihydrate gypsum is derived from discarded gypsum board, and the fine-grained soil is dried water treatment sludge. This allows for the reuse of not only discarded gypsum board but also water treatment sludge.

[0008] Preferably, the hemihydrate gypsum is 48 percent or more and 52 percent or less by weight, the purified water sludge is 8 percent or more and 12 percent or less by weight, and the quicklime or cement is 38 percent or more and 42 percent or less by weight.

[0009] The method for producing a solidifying agent according to the present invention comprises the steps of: generating hemihydrate gypsum by crushing and separating discarded gypsum board and heating it; and mixing the generated hemihydrate gypsum, the purified water sludge, and quicklime or cement such that the generated hemihydrate gypsum accounts for 45% to 65% by weight and the dried purified water sludge accounts for 5% or more by weight. [Effects of the Invention]

[0010] According to the present invention, discarded gypsum board can be effectively utilized. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below. The solidifying agent of this embodiment comprises 45% to 65% by weight of hemihydrate gypsum, 5% or more by weight of fine-grained soil, and quicklime or cement. More specifically, the hemihydrate gypsum accounts for 48% to 52% by weight, the fine-grained soil accounts for 8% to 12% by weight, and the quicklime or cement accounts for 38% to 42% by weight.

[0012] The hemihydrate gypsum contained in the solidifying agent is derived from gypsum board. More specifically, the hemihydrate gypsum is obtained by crushing and separating discarded gypsum board to obtain dihydrate gypsum, which is then heated in a drying oven at 100°C to 120°C for 24 hours. The hemihydrate gypsum content in the solidifying agent is 45% to 65% by weight. More specifically, it is 48% to 52% by weight.

[0013] The fine-grained soil contained in the solidifying agent is, for example, dried water treatment sludge. The content of water purification sludge in the solidification material is 5% or more by weight. More specifically, it is 8% to 12% by weight. By including water purification sludge in the above ratio, the generation or leaching of hydrogen sulfide and fluorine from hemihydrate gypsum can be suppressed.

[0014] The solidifying agent contains 38% to 42% by weight of quicklime or cement. In other words, the solidifying agent in this embodiment may be a lime-based solidifying agent with added quicklime, or a cement-based solidifying agent with added cement. Note that slaked lime may be included instead of quicklime.

[0015] [Method for manufacturing solidifying agent] The method for producing the solidifying agent in this embodiment comprises a first step of generating hemihydrate gypsum by crushing, separating, and heating discarded gypsum board, and a second step of mixing the hemihydrate gypsum, the purified water sludge, and quicklime or cement such that the generated hemihydrate gypsum accounts for 45% to 65% by weight, and the dried purified water sludge accounts for 5% or more by weight. In the first step, the discarded gypsum board is crushed and separated to obtain dihydrate gypsum. The obtained dihydrate gypsum is heated in a drying oven at 100°C to 120°C for 6 hours or more to obtain hemihydrate gypsum. For example, hemihydrate gypsum can be obtained from dihydrate gypsum by heating in a drying oven at around 110°C for 24 hours. Alternatively, the heating conditions may be adjusted by setting the drying oven temperature to around 130°C and shortening the heating time. In the second step, more specifically, hemihydrate gypsum, quicklime, and dry purified water sludge are mixed in an amount of 50% by weight, to obtain a solidifying agent.

[0016] As described above, the solidification material in this embodiment allows for the utilization of a relatively large amount of hemihydrate gypsum while suppressing the release of hydrogen sulfide and fluorine from hemihydrate gypsum, thereby promoting the recycling of discarded gypsum boards. Furthermore, the added hemihydrate gypsum not only acts as a soil substitute (bulker) to reduce moisture content, but also contributes to chemical solidification through hydration reactions with soil particles. By mixing a relatively large amount of hemihydrate gypsum with lime, a unique strength can be expected to develop.

Claims

[Claim 1] Hemihydrate gypsum in a concentration of 45% to 65% by weight, Water treatment sludge of 5% by weight or more, Quicklime, slaked lime, or cement A solidifying agent containing [this material].