JPH0128821B2 - - Google Patents

Description

[Detailed description of the invention]

Generally, dust and sludge generated from steel mills have iron oxide as the main component, but they also contain Zn, Pb,
Because it is a fine powder that contains harmful metal compounds such as Cd, Ni, Cr, and Cu, and also contains P, S, and Cl, it cannot be used as an iron resource, and on the other hand, it is difficult to dispose of it as industrial waste. The reality is that it costs a lot of money to dispose of it. On the other hand, the current situation is that the molten slag generated from steel factories is left to cool unnecessarily, with a huge amount of sensible heat energy. The present invention focuses on these points and utilizes the sensible heat of the slag as reaction energy, completely converts steelmaking dust and sludge into the slag, prevents the elution of harmful components, and completely eliminates pollution. It is intended for the purpose of tightening. Examples of this type of research include Japanese Patent Application No. 111306/1983 (Japanese Patent Application No. 61304/1983), which the applicant has already filed;
Japanese Patent Application No. 50-53680 (Japanese Unexamined Patent Publication No. 51-129802)
No. 50-69268 (Japanese Unexamined Patent Publication No. 51-145528), etc.
All of these methods use dust containing a reducing agent,
This process involves making sludge briquettes or pellets and reacting them directly with the slag.
It was confirmed that the temperature of the slag rapidly decreases, resulting in an incomplete reaction, and that undissolved dust and sludge remain in the slag after treatment, which is a drawback that is sometimes seen. The method of the present invention eliminates the above-mentioned drawbacks, and also provides a method for increasing the throughput of dust and sludge and making the pollution-free treatment of harmful components more complete. , dust, and sludge are put into the hot molten slag and pre-roasted to remove most of the volatile components and collected using a dust collector. A method of putting it into slag,
Volatile components such as Zn, Pb, Cd, and Cl are completely removed in a two-step process of pre-roasting and slag reaction, and dust and sludge are further removed by slag reaction at high temperatures. Its distinctive feature is that it completes the chemical reaction. The fuel used in the first step is usually coke powder, coal powder, etc., and no auxiliary agent is used, but when the content of Zn, Pb, etc. is particularly high, CaCl ₂ etc. is used, and Ni, Cr, etc. When the metal contains Mo, W, V, etc. and is recovered as a metal after the slag reaction, aluminum powder, ferrosilicon powder, etc. are used as the fuel having reducing power, and iron powder etc. are used as the auxiliary agent. The amount used varies depending on the type of dust and sludge, but at least the theoretical amount required for reactions such as volatilization of moisture and volatile substances is required. In the second step, the dust and sludge mixture filled in a roasting furnace using a normal sintering machine is ignited by the side radiation heat of the slag or by an auxiliary burner, and the inside of the packed bed is forcedly ventilated. The entire body is roasted to remove volatile substances and the temperature of the roasted product is raised, but there are no restrictions on the roasting method as long as the roasting effect is good, even if it is roasted using a rotary kiln or the like. It's not something to add. In the third step, when the high-temperature roasted product is introduced into the slag, it is preferable to add the slag while stirring it by bubbling with gas or the like, as this method can uniformly transform it into slag. Next, the method of the present invention will be described in detail with reference to explanatory diagrams shown in the drawings. In the figure, steel dust, sludge, fuel and auxiliary agents, mixer, mixture hopper, mixture, mixture feeder, mobile roasting furnace, roasting furnace packed bed, intake hood, Intake control valve, ignition burner, dust collection damper, intake duct, dust collection duct, dust collector, dust collector blower, dust collection hood, roasted products, slag, slag pot,
indicates a gas lance, and indicates a slag generation furnace. A slag pot that receives the slag from the slag generation furnace is set directly below the mobile roasting furnace, while the steelmaking dust and sludge are mixed with fuel such as coke powder by a mixer, and the mixture is The mixture enters the hopper, is then filled into a mobile roasting furnace by a feeder, is sucked in by a dust collector blower through an intake hood, is ignited at the bottom of the packed bed by an ignition burner, and is controlled by an intake control valve. The intake air volume is adjusted to roast at a high temperature. During this time, the substances volatilized by roasting are efficiently collected by the dust collector, and the packed bed that has been roasted in the mobile roasting furnace is turned over and the roasted material falls into the slag at a high temperature. throw into. In addition, the slag is bubbled and stirred by a gas lance to promote completely uniform dissolution of the roasted material. In this way, the dust completely slaged in the slag,
The sludge component becomes a constituent substance in the slag, stabilizes it, and becomes non-polluting without being eluted. In addition, the volatile substances generated when the roasted material is put into the slag are completely collected in the dust collector by operating the dust collection hood and damper, so there is no concern about environmental pollution. Examples will be described below. Example: Diameter 600mm connected to dust collection back filter
90% (by weight) of ordinary steel electric furnace dust was placed in a vertical iron roasting furnace with a diameter of 400 mm and a depth of 400 mm.
Lightly fill the mixture with 100kg of kneaded coke powder (same throughout the text) and 10% coke powder, and ignite it with a gas burner from the bottom while drawing air from the top.
Suction roasting is performed at an air flow rate of m ³ /min, and after the upper part has been thoroughly roasted, air is poured into approximately 550 kg of slag (1550°C), which was melted in a 1 ton electric furnace and received in a slag pot. While stirring by bubbling, the mixture was turned over and poured in a red-hot state to form a molten slag. Next, after the slag cooled and solidified, it was crushed into pieces of approximately 25 mm or less, subjected to magnetic beneficiation, the metals contained were recovered, the characteristics of the non-magnetic slag were measured, and the volatile matter recovered by the dust collector was analyzed. It was as follows.

[Table] Table 1 shows the chemical analysis values of treated dust and products after treatment.
This shows that Cl is concentrated. Based on the above results, the volatilization rate of Zn, Pb, and Cl in the dust is calculated as follows.
%) Roasting process Pb volatilization rate [1-78Kg×0.0052/100Kg×0.0107]×100=62.1(
%) Roasting process Cl volatilization rate [1-78Kg×0.0309/100Kg×0.0889]×100=72.9(
%) Total Zn volatilization rate including volatilization during reaction with slag [1-608Kg×0.0039+16Kg×0.0045/100Kg×0.1504
] × 100 = 83.7 (%) Total Pb volatilization rate [1-608Kg × 0.0001/100Kg × 0.0107] × 100 = 94.3
(%) Total Cl volatilization rate [1-608Kg×0.000/100Kg×0.0889]×100=100.0
(%). In addition, Table 2 shows the results of measuring the eluted ions of the non-magnetic slag after treatment using the method notified by the Environment Agency.

[Table] There was no elution of harmful components at all, and it was revealed that there would be no problem in using the treated slag as civil engineering materials such as road ballasts. As explained above, according to the method of the present invention, steelmaking dust and sludge are first subjected to preliminary roasting to remove most of the volatile components, and then directly reacted with the molten slag at a red-hot high temperature. Therefore, the reaction is reliable, there is no failure in the treatment, and the dust processing capacity per molten slag is large. Even in steelmaking plants with a relatively small amount of slag, the dust generated in-house can be used to process the dust generated in-house. This has the advantage that the slag can be treated to make it non-polluting.

[Brief explanation of drawings]

The drawing is a schematic explanatory diagram of the method of the present invention.

Claims (1)

[Claims] 1. A method for treating steelmaking dust and sludge, which comprises the following steps. First step: Steelmaking dust and sludge are mixed with fuel alone or fuel and auxiliary agent in an amount necessary for roasting the dust and sludge. 2nd step: After charging the mixture obtained in the 1st step into a roasting furnace, the fuel is ignited, and the mixture is roasted using the combustion heat of the mixed fuel, etc., to remove moisture and remove the dust and sludge. volatilizes volatile substances contained in Third step: The roasting dust and sludge obtained in the second step are poured into high-temperature slag to dissolve and turn into slag, and the remaining volatile substances are completely volatilized. 4th step: The slag obtained in the 3rd step is cooled and solidified, then crushed, and the iron particles contained therein are recovered by ordinary beneficiation means. Fifth step: The volatile substances volatilized in the second and third steps are collected by suction using a dust collector. 2 The fuel used in the first step is at least one of carbonaceous fuel, aluminum powder, and ferrosilicon powder.
The method according to claim 1, characterized in that the number of species is more than one species. 3 The auxiliary agents used in the first step are iron powder, CaCl ₂ ,
The method according to claim 1 or 2, characterized in that at least one kind of KClO ₃ is used. 4. Any one of claims 1 to 3, characterized in that when the roasting dust and sludge are introduced into the slag in the third step, the slag is uniformly introduced while bubbling the slag with gas. The method described in.