JPH0120207B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating dust and sludge (hereinafter referred to as dust) generated during steelmaking operations to make them non-polluting by utilizing the sensible heat of molten slag. In general, dust generated from steel factories has iron oxide as its main component, and contains harmful metals such as zinc oxide, lead oxide, and cadmium oxide, although there are slight variations depending on the raw material iron scrap used. Since the amount of waste far exceeds the disposal standards for industrial waste, it costs a lot of money to dispose of it. On the other hand, the current situation is that slag discharged from steel factories is left to cool unnecessarily while still containing a huge amount of energy. The present invention focuses on these points and attempts to perform a pollution-free treatment of dust at low cost by using the sensible heat of the slag discharged in a high-temperature molten state, by mixing a small amount of auxiliary fuel with dust, The molten slag is placed on the slag surface in the slag pan that receives the slag and preheated, and the high temperature slag is further flowed down from above to melt the preheated dust in the slag, reducing and volatilizing harmful metals and sending it to the dust collector. The main purpose of this method is to completely prevent the elution of harmful components by collecting the remaining dust and turning it into slag. The method of the present application will be described in detail below with reference to explanatory drawings. Dust generated in a steelmaking factory is mixed with a certain proportion of coke and other fuels and stored in a hopper 1. On the other hand, high-temperature slag 3 generated from a steelmaking furnace 2 is received in a slag ladle 4 and the molten slag is When a mixture 5 of dust, fuel, etc. stored in the hopper 1 is introduced onto the surface of the slag 3 via a conveyor 6 and a chute 7, the mixture 5 of dust, fuel, etc. is heated by the sensible heat of the slag 3. The combustion of the ignited and mixed fuel preheats the dust to a red-hot state. Next, when the high-temperature slag 8 generated in the next operation of the steelmaking furnace 2 is put into the same slag pot 4, the red-hot dust 5 and the slag 8 easily react, and the dust 5 is mixed into the slag. turn into something. In order to make this reaction more effective, it is effective to stir the inside of the slag pot 4 by bubbling or the like with the high-pressure gas lance 9, so that the dust is completely turned into slag and at the same time the harmful heavy metals Zn and Pb are removed. , Cd, etc., are reduced and volatilized. In addition, the heavy metals that are partially volatilized during red-hot preheating of the dust and the heavy metals that are volatilized during the reaction with the slag are transported to the duct 1.
This collected material can be used as a raw material for non-ferrous smelting, and harmful heavy metals are rendered harmless by the treatment of the present invention. On the other hand, the dust molten in the slag is diffused into the steelmaking slag and forms stable minerals, so even the slightest remaining heavy metals become completely insoluble, which satisfies the waste standards for industrial waste. Become. The treated slag can be used as a civil engineering material such as roadbed material, and will not cause any leaching pollution when used as a landfill material. As explained above, according to the method of the present invention, when treating steelmaking dust to make it non-polluting by using the sensible heat of steelmaking slag, a small amount of fuel is mixed and preheated to a red-hot state, and then melted into the steelmaking slag. It can easily make dust completely pollution-free, and it has the advantage that it can be carried out at a low cost even in steelmaking factories where the amount of slag generated is relatively small. Examples of the present invention will be described below. Example In this example, 10 parts by weight of coke powder was added to 100 parts by weight of electric furnace dust on the slag surface in a slag ladle that had received about 3T of reduction phase slag at a steelmaking factory with a 60T electric furnace. dust pellets mixed with
Preheat for about 3 hours with 1000Kg on it, and the dust level is about 700
When the temperature reached ℃, approximately 3 T of the reduction phase slag was further allowed to flow down, bubbling was performed with high pressure air, and the slag was sufficiently stirred to cool and solidify. The results of the chemical analysis of the charged electric furnace dust and the slag after treatment and the elution test according to the notification of the Environment Agency are shown in the table below.The elution of harmful heavy metals in the dust was completely prevented, and the dust was not dissolved in the slag. Nothing could be seen, and the process was completely pollution-free. 【table】

[Brief explanation of drawings]

The drawings are schematic illustrations of the method of the present invention. In the diagram, 1...hopper, 2...steelmaking furnace, 3...
High temperature slag, 4... slag pan, 5... dust and fuel mixture, 6... conveyor, 7... chute,
8...High temperature slag generated next, 9...Lance for high pressure gas, 10...Duct.

Claims (1)

[Claims] 1. A method for treating steelmaking dust and sludge, which comprises the following steps. First step: Steelmaking dust, sludge, and a small amount of simple fuel or fuel and combustion aid are mixed. 2nd step: The mixture obtained in the 1st step is placed on the slag surface in the slag pan that has received the steelmaking slag, and the sensible heat of the slag removes moisture and causes the ignition and combustion of the fuel contained in the mixture. Preheat the rice, dust, and sludge. Third step: From above the dust and sludge preheated in the second step, the steel slag generated next is flowed down to turn the dust and sludge into molten slag. Fourth step: Volatile substances generated in the second and third steps are collected by a dust collector. 2. A patent claim characterized in that the fuel used in the first step is at least one of carbonaceous fuel, sawdust, wood bark waste, rice husk, tire waste, heavy oil, tar, pitch, waste oil, and heavy oil combustion ash. Range 1
The method described in section. 3. The method according to claim 1 or 2, wherein the combustion aid used in the first step is at least one of iron powder, aluminum powder, ferrosilicon powder, and KClO. . 4. In the third step, when the preheated dust, sludge, and molten slag are mixed to form a molten slag, the reaction is made complete by gas bubbling or mechanical stirring in the slag pot after the slag has flowed down. A method according to any one of claims 1 to 3.