JPH0369535A - Utilizing method for dust in steel manufacture - Google Patents

Abstract

PURPOSE:To effectively utilize dust in steel manufacture as roadbed material by kneading cement, slag free from iron in steel manufacture and water with dust in steel manufacture and thereafter solidifying the kneaded substance, crushing and sieving the solidified material and blending the crushed and sieved material with slag ballast in steel manufacture and natural aggregate ballast. CONSTITUTION:Cement and slag free from iron in steel manufacture or slag in preliminary treatment of molten iron are added to dust generated in a steel manufacturing stage. The mixture is kneaded while adding water and thereafter solidified. This solidified substance is crushed and sieved. This crushed and sieved material is mixed with slag ballast in steel manufacture and natural aggregate ballast and the obtained mixture is utilized as roadbed material. Further in this case, gypsum is furthermore added. When chromium is incorporated in dust, ferrous sulfate or ferrous chloride is furthermore added and thereby effect is enhanced. Especially when these are blended with slag ballast in steel manufacture, such effect is caused that hydraulicity is imparted regardless of the following case. Aging and modifying treatment are performed so that slag ballast in steel manufacture is not expanded and broken and thereby hydraulicity is lost.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for effectively utilizing dust, which is generated in large quantities from electric furnace steel mills, casting manufacturers, etc., and which is difficult to dispose of.

<Prior art> Electric furnace dust is roughly divided into those containing mainly iron oxides and those mainly containing oxides of iron, zinc, lead, cadmium, etc., but the amount of the latter generated is There are many people.

These dusts cannot be disposed of in a landfill because harmful metal ions will be leached out by rainwater if they are disposed of in a landfill. Therefore, a method has been adopted in which reducing substances such as coke powder are blended into granules and fired in a rotary kiln to recover the volatilized zinc and lead. Zinc, lead, etc. remain without being completely volatilized, and the problem of elution still remains.

For example, there is a method of adding cement, cement and blast furnace water slag powder, or cement, blast furnace water slag powder, and ferrous sulfate or ferrous chloride to such dust, kneading it, and disposing of it in a landfill. It is disclosed in Japanese Patent Application Laid-Open No. 55-162382, and dust is added to molten steelmaking slag while bubbling together with silicate rocks, minerals, calami, etc. in order to lower the viscosity and melting point and prevent elution. For example, Japanese Patent Publication No. 60-23870 discloses a method of recovering volatile substances such as zinc and lead and fixing the remainder in slag. However, although a method for using it as a raw material for cement is shown in JP-A-63-139038, the current situation is that none of these methods has been put into practical use.

<Problems to be solved by the invention> In the present invention, as mentioned above, the steelmaking dust, which is difficult to dispose of, is effectively used by mixing it with the steelmaking slag ballast and natural aggregate ballast that are currently in practical use. The purpose is to

<Means for Solving the Problems> In order to achieve the above object, the present invention employs the following means. In other words, cement and iron-removed steelmaking slag or hot metal pretreatment slag are added to the dust generated during the steelmaking process, water is added, the mixture is solidified, crushed, and sieved to produce steelmaking slag ballast or natural aggregate. This is a method in which the mixture is mixed thoroughly and used as a roadbed material.

At this time, it is highly effective to further add gypsum or, if the dust contains chromium, to also add ferrous sulfate or ferrous chloride. Also, steelmaking dust is water,
It may also be used after washing with hot water or mineral acid solution. Furthermore, blast furnace water slag may be used instead of iron-removed steelmaking slag or hot metal pretreatment slag.

Note that cement here refers to Portland cement type (
Normal, early strength, fly ash, blast furnace, silica, super early strength)
, alumina-based raw materials such as aluminum dross and lime are added to alumina cement-based or molten steelmaking slag to cause a melting reaction and reformed so that calcium aluminate is the main component, and after cooling, it is finely pulverized. , cement it to about 20
This refers to a fast-hardening trial cement that is mixed with ~30% by weight, or finely pulverized with gypsum and mixed with cement in an amount of approximately 20~30% by weight.

<Examples and Effects> Hereinafter, experiments conducted to confirm the effects and effects of the present invention and their results will be shown.

First, Table 1 shows the chemical analysis values of the raw materials used.

The slag in Table 1 was all 0.5%, and the slag in the oxidation stage was 0.1%.

In addition, commercially available products were used for cement, gypsum (■ type anhydrous, trihydric), ferrous sulfate, and ferrous chloride.

Next, Table 2 shows the electric furnace dust in water, boiling water, 112sO
Chemical analysis values when washed with 4 and 11Cl are shown.

Table 2 Converter slag, agglomerated slag, and oxidation stage slag in Table 1 above are slags stabilized by aging treatment for six months or more. In addition, free lime (F, Ca0) is 0.0% by weight for all of the four types of slag in Table 1 above, and is 10 to 15% by weight.
Table 3 shows the elution test results for the raw materials used in the converter slag and agglomerate according to the method notified by the Environment Agency.

Blend the various raw materials mentioned above, add water and knead to form a 5cm
Place it in a JIS mold of φX10c+++ and pack it with a pie break for 10 seconds, smooth the surface with a trowel after about 5 hours, remove it from the mold after 24 hours, cure in a moist air, and check the uniaxial compressive strength at the end of the month. The results of measuring (kg/c+fl) are shown in Table 5.

Table 5 (Part 1) Next, Table 4 shows the slag used.

shows.

Table 4 Particle size distribution of dust, etc. Table 5 (Part 2) Table 5 (Part 3) 10 As can be seen from the above results, electric furnace dust mainly consists of very fine particles, so when mixing and kneading , the water-cement ratio is large, and even if about 10% by weight of cement is mixed, the unconfined compressive strength is small. Also, if the slag particles to be blended are small, the -axial compressive strength does not increase much.

However, when coarse-grained slag or anhydrite is added, the unconfined compressive strength increases. This is thought to be due to the action of coarse aggregate in concrete, or to a decrease in the water-cement ratio. Also, in the case of prototype cement, both initial and long-term strength are increased.

Table 6 shows the results of elution of several types of materials that had a considerable axial compressive strength and that could be used as a grain control material for roadbed materials by crushing them using the method notified by the Environment Agency. show.

Table 2 shows the results of roadbed material tests (JI 5
A1203.1102.1109.1110.1104
．． 1211.5015 etc.) and the results are shown in Table 7.

= 11 In Table 7 above, values for slag in the oxidation stage are also listed for comparison, but as can be seen from Table 7, the slag balance in the oxidation stage alone has a modified CBR, - axial compression, strong axial compression strength. However, the pollution-free and solidified Nα20.31°34
By blending 5 to 10% of CBR, it becomes strong in axial compression and has hydraulic properties.

<Effect of the invention> As described above, according to the present invention, electric furnace steelmaking is possible.

Steelmaking dust generated in large quantities by casting manufacturers is blended into steelmaking slag ballast and natural aggregate ballast so that it can be used effectively. It also has the effect of imparting hydraulic properties, whereas it has been subjected to a modification treatment to eliminate hydraulic properties. Furthermore, even when steelmaking dust contains chromium, it can be made non-polluting by adding ferrous sulfate or ferrous chloride.

Claims (1)

[Claims] 1. Adding cement and iron-removed steelmaking slag or hot metal pretreatment slag to the dust generated in the steelmaking process,
A method of using steelmaking dust, which is mixed with water and solidified, crushed and sieved, mixed with steelmaking slag ballast or natural aggregate ballast, and used as a roadbed material. 2. A method of utilizing steelmaking dust in the method according to claim 1, further comprising adding gypsum. 3. A method of utilizing steelmaking dust in the method according to claim 1 or 2, further comprising adding ferrous sulfate or ferrous chloride. 4. A method of utilizing steelmaking dust according to any one of claims 1 to 3, wherein the dust has been washed with water, hot water, or mineral acid solution. 5. A method of utilizing steelmaking dust in which blast furnace slag slag is used instead of iron-removed steelmaking slag or hot metal pretreatment slag in the method according to any one of claims 1 to 4.