JP6182929B2 - Manufacturing method of steelmaking slag roadbed material - Google Patents

Description

  The present invention relates to a method for manufacturing a roadbed material using steelmaking slag generated in a steel manufacturing process such as a steelworks.

  Steelmaking slag generated in the steel manufacturing process at steelworks, etc. contains unoxidized CaO component (free CaO) that cannot be completely melted during the refining process, and this free CaO reacts with moisture (hydration reaction) Thus, it has the property of producing hydroxide and expanding.

  Moreover, steelmaking slag has many fine grains, and it is difficult to satisfy roadbed material standards (see Non-Patent Document 1, etc.) and the like with a particle size as generated from a normal steelmaking slag manufacturing process. Therefore, when it is used as civil engineering materials such as roadbed materials, the hydration reaction is promoted by atmospheric aging treatment or steam aging treatment, the slag expansion characteristics are stabilized, and the particle size is adjusted. Products that conform to standards are built in.

  The atmospheric aging treatment is a treatment in which the hydration reaction is carried out in an atmospheric exposure state, but the reaction is relatively slow and generally requires more than half a year and requires a large yard. The steam aging process is a process for forcibly promoting the hydration reaction by steam heating, and is much faster than the atmospheric aging process, and is usually completed in 1 to 2 weeks.

However, a large amount of steam is required along with a large-scale facility that has a steam pipe installed around the ground in the yard, and a steelmaking slag to be processed is stacked on top of it, and a cover for preventing steam leakage and heat insulation is provided. Become.

  Further, in general, since the fine particles obstruct the passage of steam, it may be necessary to process for a longer time or may not reach the standard expansion ratio. If the expansion ratio of the steelmaking slag after processing is not below the standard for roadbed materials, reprocessing is performed, and further, time and cost are required.

  In addition, as a treatment for stabilizing free CaO, a carbonation treatment has been proposed (see Patent Documents 1 to 5), but this method uses carbon dioxide gas for a long time in order to carbonize the inside of the slag. It must continue to flow and is even more expensive than steam treatment and is not an efficient method.

  In Patent Document 6, the amount of water added is adjusted so that the granular slag is less than the moisture value at which free water begins to exist and is in a range of 5% by mass less than the moisture value, A method of granulating slag by supplying dry ice while applying mechanical stirring is disclosed.

  The method of Patent Document 6 enables powder steelmaking slag, which is difficult to use effectively, to be granulated at a room temperature that is much shorter than before and used as a roadbed material. The cost burden for using a large amount of slag is large, the coupling between slags is relatively weak, it is difficult to secure the necessary strength as a roadbed material, and the productivity is low.

Thus, the process to stabilize the free CaO in the steelmaking slag, vast yard, or, are subjected to high costs, when containing a large amount of fine fraction, a fact is going worse.

JP-A-52-129672 JP 08-259282 A Japanese Patent Application Laid-Open No. 11-21115 JP-A-11-71160 JP 2000-140797 A JP 2007-284268 A

JIS A 5015 “Steel Slag for Roads”

  In view of the above situation, the present invention has an object to inexpensively and effectively utilize steelmaking slag containing fine particles that do not satisfy JIS standards as a material for roadbed materials, and manufacture of steelmaking slag roadbed materials that solves the problems. It aims to provide a method.

  The present inventors diligently studied a method for solving the above problems. As a result, it has been found that a hydrated solid body using steelmaking slag containing fine particles as an aggregate acts to suppress the expansion characteristics of the steelmaking slag itself.

  This invention was made | formed based on the said knowledge, and the summary is as follows.

In the manufacturing method of steelmaking slag roadbed material that kneads steelmaking slag, solidified material, water, and water reducing agent, and crushes the molded hydrated solidified material and adjusts to the required particle size, it meets JIS standards. The expansion ratio (Bs) of steelmaking slag containing unobtained fine particles × volume ratio (Vs) of steelmaking slag containing fine particles not satisfying the JIS standard in the hydrated solid body is 1. Method for producing a steel slag roadbed material, characterized in that 5 is below.

    Here, the corrected expansion ratio Bh = Bs × Vs

  According to the present invention, in effectively utilizing steelmaking slag containing fine particles as a material for roadbed materials, by solidifying the steelmaking slag itself, the steel management slag itself can be relaxed and the steelmaking slag contains fine particles. Slag can be used inexpensively and effectively.

It is a figure which shows the relationship between the expansion ratio (Bs) of steelmaking slag, and the expansion ratio (Bk) of a hydrated solidified body. It is a figure which shows the relationship between the expansion ratio (Bh) of the steelmaking slag which carried out volume correction | amendment, and the expansion ratio (Bk) of a hydrated solidified body.

  The present invention will be described in detail.

  In the present invention, when steelmaking slag containing fine particles is used as a material for roadbed materials, it is focused on the fact that expansion characteristics can be suppressed by hydrating and solidifying, and the expansion management standard of steelmaking slag itself is relaxed The basic idea is to use steelmaking slag containing fine particles inexpensively and effectively.

  In general, the hydrated solidified material using steelmaking slag is composed of blast furnace slag and steelmaking slag as aggregate, and blast furnace slag fine powder, ordinary Portland cement, fly ash, etc. are used as the solidifying material. In addition, it is kneaded and cured. In the present invention, similarly, blast furnace slag may be used as an aggregate, and ordinary Portland cement or fly ash may be used as a solidifying material.

  Table 1 shows a blending example of the hydrated solidified body, the volume ratio (Vs) of the steelmaking slag, the expansion ratio (Bs) of the steelmaking slag, the expansion ratio (Bh) of the steelmaking slag after volume correction, and the hydrated solidified body The expansion ratio (Bk) is shown. The expansion ratio (Bs) of the steelmaking slag and the expansion ratio (Bk) of the hydrated solid body are measured according to JIS standards.

FIG. 1 shows the results of investigating the relationship between the expansion ratio (Bk) of the hydrated solid product produced in the formulation example shown in Table 1 and the expansion ratio (Bs) of the steelmaking slag used as the aggregate. The equation in the figure, y = 0.50x, is a first order approximation.

  It can be seen from FIG. 1 that the expansion ratio (Bk) of the hydrated solid body is lower than the expansion ratio (Bs) of the steelmaking slag itself that is the aggregate.

  Here, it is considered that there is no expansion characteristic other than the steelmaking slag in the hydrated solidified body, and the influence of expansion by the steelmaking slag when the hydrated solidified body is formed will be considered. Generally, the composition of cement-based kneaded materials such as ready-mixed concrete is expressed by weight, and the same applies to hydrated solidified bodies. The method of correcting the expansion ratio (Bs) of steelmaking slag with the volume ratio of steelmaking slag in the body is considered appropriate, and the corrected expansion ratio (Bh) of steelmaking slag is the volume ratio (Vs) of steelmaking slag in the hydrated solidified body. And Bh = Bs × Vs based on the expansion ratio (Bs) of the steelmaking slag itself.

  FIG. 2 shows the relationship between the corrected expansion ratio (Bh) of the steelmaking slag and the expansion ratio (Bk) of the hydrated solidified body. The equation y = 0.76x in the figure is a linear approximation equation.

  Compared to the expansion ratio (Bs) of the steelmaking slag shown in FIG. 1, it approaches the expansion ratio (Bk) of the hydrated solidified body, but as shown by the approximate equation slope 0.76, it still shows a reduction of 24%. It is done.

From the above, the cause of inflation reduced due to the hydrated solidifying conjugated is primarily the dilution effect of the expansion characteristics by no expansion characteristics other than steel slag material, the second, solidification strength of hydrated solidified However, the present inventors considered that the steelmaking slag itself was superior in expansion strength and the expansion was suppressed as the whole hydrated solidified body.

  Moreover, from FIG. 2, the expansion ratio (Bk) of the hydrated solidified body does not exceed the corrected expansion ratio (Bh) of the steelmaking slag, and is reduced to 76% as indicated by the primary approximation formula.

  Based on these facts, the present inventors found that the expansion ratio (Bs) of the steelmaking slag was corrected with the corrected expansion ratio (Bh) of the steelmaking slag corrected by the volume ratio (Vs) of the steelmaking slag in the hydrated solidified body. By setting the relationship of the expansion ratio (B0) required after crushing of the hydrated solid body to Bh × 76% ≦ B0, it can be used as a hydrated solid body without problems of expansion. It was.

  As described above, the coefficient 76% of Bh is due to the development of the solidification strength, and is a coefficient α that varies depending on the type and amount of the solidified material and the particle size of the aggregate, and Bh × α ≦ B0 (α ≦ 1) is considered appropriate for understanding the phenomenon. However, in consideration of variations in the quality of the solidified material and aggregate, variation in expansion ratio, and the like, it is desirable to select steelmaking slag satisfying Bh ≦ B0 as α = 1 as an aggregate.

  That is, according to the present invention, it is possible to select a steelmaking slag applicable as an aggregate before it is hydrated and solidified. In addition, the steel slag expansion criteria are relaxed, and fine particles that are difficult to steam aging treatment, etc. They found an effective use of steelmaking slag containing a lot of water.

  In order to utilize such a hydrated solid body as a roadbed material, the expansion ratio (B0) required for the hydrated solidified body is set to 1.5% or less as defined by the JIS standard for roadbed material. do it.

  The formed hydrated solidified body is crushed, crushed, adjusted to the required particle size, and used as a roadbed material, but the fine particles generated at the time of particle size adjustment already satisfy the expansion standard, It can be used again as a hydrated solid material.

  Next, examples of the present invention will be described. The conditions in the examples are one example of conditions used for confirming the feasibility and effects of the present invention, and the present invention is based on this one example of conditions. It is not limited. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

  In Table 1, as an application example of roadbed material, the volumetric expansion ratio of steelmaking slag is used as a judgment criterion of steelmaking slag that can be used as an aggregate of a hydrated solid body that is 1.5% or less of the expansion ratio of roadbed material JIS standard. (Bh) and evaluation results are shown.

  As described above, according to the present invention, when steelmaking slag containing fine particles is effectively used as a material for roadbed materials, solidification of the steelmaking slag can ease the expansion management standard of the steelmaking slag itself, Steelmaking slag containing grains can be used inexpensively and effectively. Therefore, the present invention has high applicability in the slag recycling industry and the civil engineering and building industry.

Claims (1)

In the manufacturing method of steelmaking slag roadbed material that kneads steelmaking slag, solidified material, water, and water reducing agent, and crushes the molded hydrated solidified material and adjusts to the required particle size, it meets JIS standards. The expansion ratio (Bs) of steelmaking slag containing unobtained fine particles × volume ratio (Vs) of steelmaking slag containing fine particles not satisfying the JIS standard in the hydrated solid body is 1. Method for producing a steel slag roadbed material, characterized in that 5 is below.

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