JP2005125135A - Method for improving byproduct slaked lime - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve carbide slag so as to have sufficient strength without exerting an adverse effect on environment. <P>SOLUTION: In this improving method of byproduct slaked lime, the carbide slag being byproduct slaked lime and blast furnace slag are mixed first to obtain a mixture (step 101) and this mixture is subsequently solidified by hydration reaction to manufacture an improved object (step 102). By these steps, the carbide slag is cured by the latent hydraulicity of the blast furnace slag to be modified to the improved object having sufficient strength. Next, the cured improved body is aerially aged to be carbonated (step 103). This aerial ageing may be performed, for example, by outdoor air-drying. Next, the neutralized improved body is utilized as civil engineering material variously used as a landfilling material, a banking material, a back-filling material, a refilling material and the like (step 104). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for improving by-product slaked lime produced as a by-product when acetylene is produced mainly from carbide.

Acetylene has been used for mining underground lighting for some time, and recently, synthetic fragrances are produced using this as a starting material, and its application is wide. Such acetylene is produced by a method in which carbide (CaC ₂ ) is chemically reacted with water or a method in which methane and petroleum hydrocarbons are thermally decomposed at a high temperature. However, when acetylene is produced by the former method, A by-product called is produced.

  Carbide cake is also called by-product slaked lime because it is mainly composed of calcium hydroxide, that is, slaked lime, and can be used as a raw material for fertilizer, but it often has to be disposed of as industrial waste due to cost. However, with the decrease in waste disposal sites, disposal of by-product slaked lime has become difficult.

  On the other hand, carbide slag is a slurry containing a considerable amount of water when acetylene is produced by a wet process. Therefore, even if carbide sardine is reused as a fill material or landfill as it is, the water content ratio is high. The land development is difficult.

  For this reason, technology has been developed for reuse as a land preparation material by adding cement to carbide slag to improve strength.

JP2003-062598

  However, the addition of cement, of course, causes an increase in pH, which not only adversely affects the environment, but there is also a problem that sufficient strength cannot be obtained even if the amount of cement added is increased. In order to effectively harden or solidify and use it as a land preparation material, there was a natural limit in its scope of application.

  The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide a method for improving by-product slaked lime that can improve carbide straw with sufficient strength without adversely affecting the environment. To do.

  In order to achieve the above object, the by-product slaked lime improving method according to the present invention, as described in claim 1, mixes by-product slaked lime and blast furnace slag so as to be in a water-containing state to form a mixture. An improved product of the mixture is produced by solidifying the body by a hydration reaction.

  Moreover, the improvement method of the byproduct slaked lime which concerns on this invention makes the said product byproduct slaked lime the carbide cocoon which is a byproduct when manufacturing acetylene by wet.

  Moreover, the improvement method of the byproduct slaked lime which concerns on this invention uses the said byproduct slaked lime as a carbide paddle, and makes the said improved body the landfill material thrown into seawater.

  Moreover, the improvement method of the byproduct slaked lime according to the present invention is a method in which the manufactured improved product is cured in the air and carbonated.

  In the by-product slaked lime improving method according to the present invention, first, by-product slaked lime and blast furnace slag are mixed so as to be in a water-containing state, and then the mixture is solidified by a hydration reaction. To produce an improved mixture.

  If it does in this way, the improvement body manufactured improves the intensity | strength 10 times or more by a uniaxial compressive strength depending on the case rather than the case where the cement of the same mass is added as a solidification material.

By-product slaked lime means that slaked lime, that is, calcium hydroxide Ca (OH) ₂ is produced as a by-product in the manufacturing process when a chemical reaction is carried out for the purpose of obtaining a predetermined substance. By-product slaked lime, which is a by-product when acetylene is produced, is included in the by-product slaked lime of the present invention. By-products generated when lime nitrogen is produced using carbide as a raw material are also included in the by-product slaked lime of the present invention.

  Mixing so as to be in a water-containing state means that slaked lime, blast furnace slag and water are mixed in terms of chemical reaction, in other words, the present invention does not use slaked lime itself as a raw material for the improved body. However, since by-product slaked lime is only used as a raw material for the improved body, it means that water is added separately when the by-product slaked lime is in a dry state, and water is not added when it is in a water-containing state. . For example, when the production of acetylene is performed in a wet manner, the carbide soot is in the form of a slurry, so that it is not necessary to add water to the carbide soot.

  It has been known that blast furnace slag has potential hydraulic properties and becomes one of cement materials, but as the name of potential hydraulic properties indicates, hydration reaction does not proceed by itself. In order for the hydration reaction to occur, some kind of stimulant is necessary, and it has been conventionally known that cement becomes the stimulant.

The present applicant focused on the fact that calcium hydroxide Ca (OH) _2, which is a chemical component contained in by-product slaked lime, may serve as a stimulant for the potential hydraulic properties of this blast furnace slag. As a result of repeating these experiments, the present inventors succeeded in producing an improved body with higher strength than when cement was added without adding cement.

The main components of cement are CaO and SiO ₂ , and such chemical components form the main compounds of tricalcium silicate, dicalcium silicate, tricalcium aluminate and tetracalcium iron aluminate, and so on. Because it was known that cement stimulated the potential hydraulic properties of blast furnace slag, Ca (OH) ₂ , a compound not included in cement, could stimulate the potential hydraulic properties of blast furnace slag. The grounds of what can be easily conceived cannot be anything, and the present invention is a novel finding obtained by the applicant's foresight and a lot of experiments based on it, and the improvement according to the present invention. It is added that the body can be effectively reused as a landfill material and is an extremely useful invention in industry.

  Here, while by-product slaked lime is used as a carbide slag, the improved body manufactured by the above-described procedure can be used as a landfill material to be put into seawater. That is, when the improved product produced by the method for improving byproduct slaked lime according to the present invention is introduced into the sea, the pH in the seawater can be suppressed to about 8.5, and therefore such an improved product. Can be used as a landfill material to be put into seawater. Incidentally, when the same mass of cement is added to the carbide slag instead of blast furnace slag and solidified, the pH in seawater exceeds 10. For this reason, there is a concern that the water quality environment may be adversely affected, and it cannot be used as a landfill material.

  Furthermore, when the improved body produced is carbonized by curing in the air, there is no concern that the alkaline component will be eluted from the improved body, and therefore, in combination with the above-mentioned improvement in strength, embankment material, backfill material, backfilling It can be effectively reused as civil engineering materials for various purposes such as wood.

  Hereinafter, an embodiment of a method for improving byproduct slaked lime according to the present invention will be described with reference to the accompanying drawings. Note that components that are substantially the same as those of the prior art are assigned the same reference numerals, and descriptions thereof are omitted.

  FIG. 1 is a flowchart showing a flow of a method for improving byproduct slaked lime according to this embodiment. As can be seen from the figure, in the method for improving byproduct slaked lime according to this embodiment, first, carbide soot as byproduct slaked lime and blast furnace slag are mixed to form a mixture (step 101).

  Here, the carbide soot is produced in a manufacturing process for producing acetylene in a wet state and is in a slurry state, so that it is not necessary to add water again.

  Next, the above-mentioned mixture is solidified by a hydration reaction to produce an improved body (step 102).

  In this way, the carbide soot is hardened by the potential hydraulic properties of the blast furnace slag and transformed into an improved body having sufficient strength.

  Next, the cured improved body is cured in the air and carbonated (step 103).

  The air curing may be air-dried outdoors, for example, and the alkali content in the improved body is neutralized by carbon dioxide in the atmosphere.

  Next, the neutralized improved body is used as a civil engineering material for various purposes such as landfill material, embankment material, backfill material, and backfill material (step 104).

  As described above, according to the method for improving by-product slaked lime according to the present embodiment, as will be described in detail in the examples below, the manufactured improved product is more than the case where cement of the same mass is added as a solidifying material. Since uniaxial compressive strength improves strength more than 10 times and neutralizes by air curing, it can be effectively reused as a civil engineering material for various purposes such as landfill material, embankment material, backfill material and backfill material. It can be used.

  Although not specifically mentioned in the present embodiment, the pH in the seawater when the improved body before carbonation is added to the seawater is suppressed to about 8.5 as described later. Therefore, when using it as a landfill material, the above-described air curing step may be omitted and put into seawater. That is, in such a modified example, as shown in FIG. 2, after the mixture is solidified by a hydration reaction to produce an improved body (step 102), the improved body is thrown into seawater as a landfill (step 111). ).

  Incidentally, when the same mass of cement is added to the carbide slag instead of blast furnace slag and solidified, the pH in seawater exceeds 10. For this reason, there is a concern that the water quality environment may be adversely affected, and it cannot be used as a landfill material.

  Since the uniaxial compression test and pH test (seawater immersion test) of the improved product produced by the by-product slaked lime improvement method according to this embodiment were performed, the test outline and test results will be described.

FIG. 3 is a graph showing the uniaxial compressive strength of the improved body manufactured in steps 101 to 102 described above. In this figure, the horizontal axis indicates the age, the vertical axis indicates the uniaxial compressive strength (kN / m ² ), and the amount of blast furnace slag added to 1 m ³ of carbide rod is 100 kg, 150 kg, 200 kg, 250 kg. As it is.

As can be seen from the figure, the uniaxial compressive strength of the improved body is leveled off when the blast furnace slag addition amount is 100 kg and the uniaxial compressive strength is 300 kN / m ² , 150 kg, and 200 kg at 1,000 kN / m ² , respectively. Can be estimated to increase with the amount of blast furnace slag added. In particular, when the amount of blast furnace slag added is 250 kg, the uniaxial compressive strength increases with age, reaching 2,500 kN / m ² at the age of 6 months.

It should be noted that the uniaxial compression strength must be 200 kN / m ² or more in terms of trafficability (heavy machine travelability, uniaxial compression strength is an index), but in the case of the improved body according to the present invention It can also be seen that the target value is cleared with all the addition amounts described above.

FIG. 4 shows the result when blast furnace cement B type is added to the carbide cocoon as a solidified material instead of blast furnace slag, and the horizontal axis indicates the age and the vertical axis indicates uniaxial compression as in FIG. The strength (kN / m ² ) is taken, and the amount of cement added to 1 m ³ of carbide cocoons is 100 kg, 150 kg, 200 kg, and 250 kg.

As can be seen in the figure, unlike the case of blast furnace slag, the uniaxial compressive strength is flat at 200 kN / m ² regardless of whether the amount of blast furnace cement B added is 100 kg, 150 kg, 200 kg or 250 kg. It turns out that the target value for trafficability cannot be cleared.

  FIG. 5 is a graph showing changes in the pH of seawater when carbide slag is solidified with blast furnace cement B, and FIG. 6 is the pH of seawater in the improved body of the present invention in which carbide slag is solidified with blast furnace slag. It is the graph which investigated change.

  In this seawater immersion test, after solidifying and curing for 4 weeks each, it was molded to a diameter of 10 cm and a height of 4 cm, then immersed in 4 L of seawater and allowed to stand for a predetermined period, and then the pH of the seawater was adjusted. It was measured.

  As can be seen from these figures, when solidified with Blast Furnace Cement B, the pH of seawater is 9.5 to 10, whereas when solidified with blast furnace slag, It can be seen that the pH of is suppressed. Moreover, although not shown in these figures, the average pH of seawater at the time of 29 days after immersion in seawater is 10.1 for the conventional solidified product solidified with blast furnace cement B type. On the other hand, the improved body of the present invention solidified with blast furnace slag remained at 8.8.

  From these results, it can be seen that the improved body according to the present invention can be directly put into seawater as a landfill without adversely affecting the water quality environment without performing special air curing.

  This indicates that, in the case of the improved body according to the present invention solidified with blast furnace slag, the pH of the improved body can be lowered to a problem-free pH by the pH buffering ability of seawater. is there.

The flowchart which showed the improvement method of the byproduct slaked lime which concerns on this embodiment. The flowchart which showed the improvement method of the byproduct slaked lime which concerns on a modification. The graph which showed the effect | action of the improvement method of the byproduct slaked lime which concerns on this embodiment. The graph which showed the effect | action of the improvement method of the byproduct slaked lime which concerns on this embodiment. The graph which showed the effect | action of the improvement method of the byproduct slaked lime which concerns on this embodiment. The graph which showed the effect | action of the improvement method of the byproduct slaked lime which concerns on this embodiment.

Claims (4)

By-product slaked lime, characterized in that by-product slaked lime and blast furnace slag are mixed in a water-containing state to form a mixture, and the mixture is solidified by a hydration reaction to produce an improved product of the mixture. Improved method. The by-product slaked lime improvement method according to claim 1, wherein the by-product slaked lime is a carbide soot that is a by-product when acetylene is produced by a wet process. The method for improving by-product slaked lime according to claim 1, wherein the by-product slaked lime is a carbide slag and the improved body is a landfill material that is thrown into seawater. The method for improving by-product slaked lime according to claim 1, wherein the produced improved product is carbonized by curing in air.

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