JPS6028896B2 - How to treat electric furnace dust - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating electric furnace dust, and more particularly, the present invention relates to a method for treating electric furnace dust, and more specifically, a method for treating electric furnace dust containing harmful heavy metals generated during electric furnace steelmaking by utilizing the sensible heat of molten slag. The present invention relates to a method in which a portion of the slag is recovered as a slag, reused as a useful resource, and the remaining portion is fixed in slag.

Electric furnace dust is an industrial waste that contains useful metal oxides such as iron, zinc, and lead, but because it contains a large amount of zinc, it cannot be reused as a raw material for blast furnaces, and it does not contain harmful metals. Because of the presence of such substances, they cannot be disposed of in landfills or dumped unless they are compliant with laws and regulations.

As a result of intensive research to solve this problem, the inventors of the present invention effectively utilize the sensible heat of molten slag to collect and recycle a portion of electric furnace dust, which contains a large amount of heavy metals such as zinc, into birch. This invention has completed the invention of a method for treating electric furnace dust, in which the residue is fixed in slag.

That is, the gist of the present invention is to recover metal oxides mainly containing zinc and lead which are thinned by blowing an electric furnace dust pellet containing a reducing agent into molten slag together with bubbling gas, and to collect metal oxides mainly containing zinc and lead contained in the electric furnace dust. The invention resides in a method for treating electric furnace dust, which is characterized by rendering harmful substances harmless, and the method of the present invention will be described in detail below.

The present invention effectively utilizes the sensible heat of molten slag as a method for treating electric furnace dust, without adding any additional heat.
As a method of melting and reacting the added dust, an electric furnace dust pellet containing a reducing agent is blown into the molten slag received in the ladle along with bubbling gas, and convection or bubbling of the molten slag is performed to remove zinc, lead, etc. The zinc is recovered as crude zinc.

After the reaction, the molten slag is discharged or hardened in a ladle, and after being crushed and magnetically sorted, it is effectively used for roadbed materials, etc. However, there are cases where the electric furnace dust to be added contains a lot of lead, and if only the electric furnace dust is added to the treatment, lead ions are reduced to about 0% compared to slag.
．． In some cases, about 1 leg to 0.2 leg is eluted.

Therefore, one or more of red mud, karami, masashi, slate, and blast furnace slag may be added to prevent the elution of lead ions.
On the other hand, the slag contains F・Ca○ (free lime), -Xa○
- It has disintegrability because it contains Si02, F, Mg○ (free magnesium), etc. In order to prevent this disintegration, if only electric furnace dust is added, it must be used in large quantities, and as a result, there is a risk of lead ions being leached from the slag. , blast furnace slag, etc. are blended and combined for treatment. In addition, when electric furnace slag is used as the head heat source in the present method, the amount of molten electric furnace slag generated is insufficient compared to the amount of dust generated (taking sensible heat into consideration), so the amount of dust is reduced. In actual operation, it is efficient to return some of the waste and charge it into the electric furnace again.

Since the amount of molten slag generated in converters and blast furnaces is large, it goes without saying that such consideration does not need to be taken. Examples of the present invention will be described below.

First, Table 1 shows the chemical analysis values of the raw materials used in the present invention, and Table 2 shows the results of an elution test performed on the raw materials in Table 1 according to the method notified by the Environment Agency.

Table 1 Table 2 After drying the above-mentioned raw materials in a 10,500~11,000 scale dryer for more than 24 hours, the slag is crushed into 4 or less pieces using a sample grinder, and then crushed into 0.3 or less pieces using a Seegel cone. The melting temperature was measured.

In addition, the magnetic tailings of the slag of 4 sides or less are placed in an electric heating magnesia arubbo and remelted in a siliconite electric furnace maintained at 155,000 ℃, and an electric furnace dust pellet (approximately 2 side J~3 side),
Blow this pellet together with nitrogen gas or air through a lance pipe (porcelain tube) for 1 minute (
After blowing nitrogen gas or air for 1 minute (approximately 4.3 so/min) and keeping the temperature at 152,000 to 1,510 °C for 1 minute, turn off the power switch and heat the furnace at approximately 120,000 °C. I took it outside and let it cool in the air.

This slag was subjected to a port export test (method announced by the Environment Agency), measurement of the main mineral content and disintegration rate by X-ray diffraction, and measurements of the particle size of 5 to IQ ribs using the autoclave treatment method of ASTM standards. And so.

), etc. Table 3 shows the measurement results for total overheating in the above experiments.

Next, the following measurements were performed on typical formulations.

Here, the blending ratios of the representative blended compositions are shown in Table 4 below.

The results of the elution test are shown in Table 5, the results of the formation status of the main minerals by X-ray diffraction are shown in Table 6, the chemical analysis values of the trial slag are shown in Table 7, and the percentage of remaining Zn and P in the trial slag is shown below. are shown in Table 8.

Table 3, Table 4, Table 5, Table 6 *K dustink occurs during cooling and disintegrates.
No autoclape treatment.

Table 7 Table 8 Next, an example of the present application processing method will be described.

As shown in Figure 1, a pot 2 containing molten slag 1 (
After passing the test, the dust treatment room 3 (approximately 600k9) was removed for approximately 25 minutes.
Welded iron plates on three sides to prevent dust from scattering, and closed the door on the other side (which had a small space at the bottom to introduce cooling air when the pot was put in), and connected the combreath door with a valve. Open 4 and pass it through lance 5, then insert lance 5.
was charged into the molten slag, bubbling was started, the valve 6 was opened, and an electric furnace dust pellet (approximately 5th side) 11, approximately 800 k9, containing 10% coke powder was charged from the hopper 7 for approximately 5 minutes. Valve 12 was closed, and only air was passed through to perform bubbling as an after-blow. When the thinned material was almost gone (about 6 minutes after stopping the addition of the dust pellet), the lance was pulled up from the molten slag and valve 4 was closed.

The thinned dust mainly composed of Zn and Pb oxides generated during bubbling was collected by a dust collector 6.

After cooling this slag, it was crushed, subjected to magnetic separation treatment, and subjected to elution, roadbed village tests, etc. Molten slag in this example,
The chemical analysis values of dust and slag after dust treatment are shown in Table 9, the elution test results are shown in Table 1, the chemical analysis values of the volatilized recovered material are shown in Table 11, and the results of the roadbed material test are shown in Table IZ. The tables are also shown.

Table 9 Table 10 Table 11 Table 12 As mentioned above, according to the method of the present invention, the volatilization rate of Zn and Pb is significantly increased by charging the electric furnace dust into the molten slag together with the reducing agent. For example, both Zn and Pb show a curing rate that is approximately 1.2 times higher than when treated under substantially the same conditions without adding a reducing agent.

In addition, by blowing bubbling gas, the reaction between molten slag, electric furnace dust, and reducing agent proceeds quickly and sufficiently, and the slag after treatment becomes harmless and non-degradable, making it effective for roadbed materials, etc. It has the effect of being usable.

[Brief explanation of drawings]

The drawing is a system diagram showing one embodiment of the apparatus used for treating electric furnace dust according to the present invention.

Claims (1)

[Claims] 1 Electric furnace dust pellets containing a reducing agent are blown into molten slag along with bubbling gas to recover volatilized oxides mainly consisting of zinc and lead, and to detoxify harmful substances contained in the electric furnace dust. Characteristic electric furnace dust treatment method.