JPH0128820B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses sensible heat possessed by high-temperature slag discharged from various metal smelting furnaces and melting furnaces as a reaction heat source,
Dust and sludge of special steel such as stainless steel,
Valuable metals contained in Ni-containing dust and sludge, especially Ni, followed by Fe,
This invention relates to a method for concentrating and recovering Cr. The dust and sludge generated during the manufacture of special steel are mainly composed of iron oxide, but a few percent of the dust and sludge are
Although it contains Ni and Cr, it is of low quality, and it also contains Pb,
Because it contains harmful components such as Zn, Cu, Cd, S, and F, it cannot be used as a raw material for Ni or Cr, and is disposed of as industrial waste at great expense. Additionally, due to its nature, nickel metal is not utilized and is disposed of as industrial waste. On the other hand, the slag discharged from various furnaces such as blast furnaces, converters, electric furnaces, and electric furnaces for ferroalloys generated in the steel industry remains at a high temperature, and a huge amount of thermal energy is wasted unused. The current situation is that it is cold. Therefore, this application focuses on the use of the above-mentioned unused thermal energy, and puts dust and sludge into these high-temperature slags, and uses the energy to regenerate and recover useful components mainly Ni, Fe, and Cr as metals. The purpose of the other components is to completely turn them into slag and make them non-polluting. As for this type of research, there is a patent application No. 111306 (Sho 48-111306) (method for recovering valuable metals from steelmaking dust and sludge using molten slag), which was previously filed by the applicant. In this method, sludge briquettes or pellets are made and placed in the bottom of the slag pot of a converter or electric furnace, and then high-temperature slag is poured over the top of the slag.This method can accommodate changes in steelmaking operations. It is not possible to adjust the appropriate amount of charged prickets or pellets.
It has been confirmed that the process sometimes has the disadvantage of remaining unreacted dust, sludge prickets or pellets. Therefore, the method of the present invention solves the above drawbacks,
Furthermore, the present invention provides a method that facilitates the recovery of valuable metals and makes the pollution-free treatment of harmful components more complete. A carbonaceous reducing agent and an alkali metal carbonate in an amount necessary to react with the metal compound in the dust or sludge are mixed and agglomerated. Second step: Dry and preheat the agglomerated product obtained in the first step. 3rd step: The dry agglomerated material obtained in the 2nd step is charged into a slag pot together with the high temperature slag, and a reduction reaction is caused by the sensible heat of the slag, mainly
Metalizes valuable metals such as Ni, Fe, and Cr. 4th step: The material in the slag pot is cooled and solidified, then crushed and metalized using normal ore beneficiation methods.
Recover Fe and Cr. This is a method of recovering valuable metals from dust and sludge using the sensible heat of the slag, which consists of each of the above steps.The carbonaceous reducing agent used in this process is usually coke powder, charcoal powder, etc. In addition, Na ₂ CO ₃ and K ₂ CO ₃ are usually inexpensive as alkali metal carbonates.
Use. In the first step, a carbonaceous reducing agent and an alkali metal carbonate are added and kneaded to dust and sludge, and agglomerated into pellets or pellets. , 1 to 5 times the theoretical amount required for Cr reduction, and the amount of alkali metal carbonate added is preferably 50% or more of the amount of carbonaceous reducing agent added when Na ₂ CO ₃ or K ₂ CO ₃ is used.
Further, the particle size of the carbonaceous reducing agent is preferably about 5 m/m or less. Next, the second step is a step of drying and removing moisture contained in the agglomerated material obtained in the first step, and is also important for preventing heat loss of sensible heat of the slag due to moisture.
Furthermore, it is also effective in preventing the agglomerated material introduced into the slag from bursting into powder. The third step is a step in which the agglomerates from the second step are introduced into the hot slag, resulting in turbulent flow of the slag falling into the slag pot or artificial turbulence of the melt caused by high-pressure gas blowing or mechanical stirring. Therefore, this is a process in which the agglomerates are introduced into the slag to promote the reduction reaction of Ni, Fe, and Cr by sensible heat, but the Ni, Fe, and Cr compounds first become carbonaceous within the agglomerates as the temperature rises. It is reduced by a reducing agent and becomes metal particles. Next, as the gangue component contained in the agglomerate is softened by sludging, the metal particles grow and are separated from the gangue component to become independent metal grains. The alkali metal carbonate added during this period generates Co through thermal decomposition, contributing to the promotion of reduction, and at the same time becomes an alkali metal oxide, lowering the melting softening point of gangue components and greatly promoting the growth of metal grains. It has the characteristic of making physical beneficiation easier in the subsequent process. However, it is important that the amount of agglomerate added is in accordance with the sensible heat of the slag, and is usually about 30% of the amount of slag.
It is as follows. Next, the first case where the present invention is applied to ferroalloy slag will be described.
The details will be explained with reference to the figures. In the figure, 1 is an electric furnace for ferroalloy metal, 2 is a ladle for ferroalloy metal, 3 is a slag ladle, 4 is a molten slag, 5 is a dry preheated pricket, 6 is a feeder for feeding the pricket, and 7 is a pricket dryer. Preheating device, 8 is a dough making machine,
9 shows the slag that has been processed, and 10 shows the ore processing device. The metal and molten slag tapped from the electric furnace 1 for ferroalloy are separated by specific gravity in the metal ladle 2, and the molten slag 4
Only the slag overflows and falls into the next slag pot 3 and is stored there. On the other hand, dust and sludge are mixed with a carbonaceous reducing agent and an alkali metal carbonate, and if necessary, a binder for making a dough is added to make a preket in a dough making machine 8. The dried and preheated pricket 5 is then prepared in the feeder 6. However, when the slag 4 falls into the slag ladle 3, the dry preheated pricket 5 is simultaneously dropped from the feeder 6 to mix well in the slag ladle 3 and sufficiently transfer the sensible heat of the slag 4 to the pricket. Medium Ni
It promotes the reduction reaction of Fe, Cr. When the temperature inside the pricket reaches about 900℃ or higher, a reduction reaction occurs inside the pricket, which is similar to a closed container, and mainly produces metals Ni, Fe, and Cr.
In reality, an Fe-Ni-Cr alloy is formed. Next, the treated slag 9 is discharged or cooled and solidified in the slag ladle 3, and then sent to the beneficiation step 10, where Ni, Ni, ore is removed by crushing, magnetic beneficiation, specific gravity beneficiation, etc.
Collect reduced metal particles mainly composed of Fe and Cr. Test examples of the present invention will be shown below. Test Example Approximately 600 kg of slag made by remelting ferrochrome slag in a 1 ton L-type electric furnace flows into an iron slag ladle 3 as shown in Figure 2, and then into the slag. Insert the lance pipe 11, and while pumping the slag with high-pressure air, add 50 kg of slag that has been thoroughly dried by pre-mixing 15 parts by weight of coke powder and 5 parts by weight of soda ash inside the stainless steel dust. After inserting it into the slag at a rate of 5 kg per minute, it was left to stand for about 3 hours, allowed to solidify by falling over, cooled to room temperature, crushed to below -3 m/m, and subjected to magnetic beneficiation. The results were as follows. .

[Table] * All percentages are by weight.
Based on the above results, we calculated the recovery rate of the magnetic metal, which is the main component of the briquettes, put into the slag. Ni recovery rate = 18Kg x 0.0535/50Kg x 0.0203 x 100 = 94.87 (
%) Fe recovery rate = 18Kg x 0.7446/50Kg x 0.3002 x 100 = 89.29 (
%) Cr recovery rate = 18Kg x 0.1407/50Kg x 0.0574 x 100 = 88.24 (
%), and the particle size distribution of the recovered metal was as shown below, indicating that the recovered metal was coarse particles.

[Table] As shown in the test examples above, dust that is currently disposed of as industrial waste and has been difficult to utilize,
According to the present invention, sludges are also extremely advantageous because Ni, Fe, and Cr can be selectively concentrated and recovered. Furthermore, it is possible to effectively utilize the sensible heat of the slag that was wasted in the past, and to decontaminate dust and sludge, which are becoming increasingly serious pollution problems, at the same time as collecting Ni, Fe, and Cr. This is extremely significant.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the process of the present method, and FIG. 2 is an explanatory diagram of a test example in which the present invention was developed. In the figure, 1: electric furnace, 2: ladle for metal, 3: slag ladle, 4: slag, 5: drying pricket, 6: pricket input feeder, 7: pricket drying preheating device, 8: slag making machine, 9: Slag after treatment, 10: Mineral beneficiation process, 11: High pressure air lance pipe.

Claims (1)

[Claims] 1. A method for recovering valuable metals from dust and sludge using the sensible heat of slag, which comprises the following steps. First step: Dust and sludge are mixed and agglomerated with a carbonaceous reducing agent and alkali metal carbonate in amounts necessary to react with the metal compounds in the dust and sludge. Second step: Dry and preheat the agglomerated product obtained in the first step. 3rd step: The dry agglomerated material obtained in the 2nd step is charged into a slag pot together with the high temperature slag, and a reduction reaction is caused by the sensible heat of the slag, mainly
Metalizes valuable metals such as Ni, Fe, and Cr. 4th step: The material in the slag pot is cooled and solidified, then crushed and metalized using normal ore beneficiation methods.
Recover Fe and Cr. 2 Alkali metal carbonate used in the first step,
The method according to claim 1, characterized in that Na ₂ CO ₃ or K ₂ CO ₃ is used. 3. According to either claim 1 or 2, wherein the dry agglomerated material and the high-temperature slag are charged simultaneously into the slag pot in the third step. Method described.