KR20010078419A - Reproduction method of zinc dross - Google Patents

Abstract

PURPOSE: A method for recovering/recycling Zn-dross from a zinc bath is provided to enhance the degree of recovery in recycling while enhancing recycling efficiency by removing Al or Al alloys existing as impurity in Zn-dross by the addition of Fe and separation accelerant. CONSTITUTION: Zn-dross is weighed and its constituents are analysed. Zn-dross is inputted into a furnace and heated at 600 to 700deg.C. Fe powder with particle size distribution ranging from 50 to 120 mesh is added and stirred for 1 to 3 hours for chemical reaction into FeAl3 and FeAl2. Separation accelerant is uniformly poured in the surface of a melted substance to accelerate separation of the melted substance, FeAl3 and oxides. Fixation is carried out for 20 to 40 minutes for separation due to the difference in specific gravity. The oxides, FeAl3, FeAl2 and the like rising to the surface of the melted substance is collected by a thin sieve. The melted substance is stirred for 5 to 10 minutes to make the specific gravity of the Zn melted substance uniform. The melted substance is poured into a forming mold to obtain a final product.

Description

Reproduction method of zinc dross

The present invention relates to a method for regenerating zinc dross that regenerates zinc dross (Zn-Dross) generated as a by-product when zinc is plated, and more particularly, by dissolving zinc dross and separately adding Fe and a separation promoter. The zinc dross regeneration method improves the recovery rate while improving the regeneration efficiency by shortening the processing time and reducing the variation of purity by removing the Al or Al oxides present as impurities in the zinc dross by chemical reaction. It is about.

In general, during the galvanizing process of a steelmaking company or a general plating company, molten zinc forms by-products at the same time as the surface to be coated, and when the content of these by-products exceeds the standard value, it is attached to the surface of the steel sheet to improve the appearance of the product. By harming, by-products must be removed.

At this time, what is generated as a by-product is called Top Dross, or ZnDross, and zinc dross is made of pure zinc as a large amount is generated during the zinc plating process such as hot plating or cold rolling. There is a demand for recycling and recycling.

Since zinc dross contains impurities such as Al, Fe, etc. above a prescribed value, it can be recycled as pure zinc only when it is removed, and this zinc regeneration method has been proposed and applied in the past.

Looking at the conventional zinc dross regeneration method as an example.

In other words, the recovered lumped zinc dross is introduced into a crucible in a predetermined amount, heated to a temperature of about 600-700 ° C., dissolved therein, and then sufficiently stirred with a stirrer and left to stand for about 12-15 hours at the same temperature.

While still standing, the oxides, Al, and Fe, which have relatively low specific gravity, rise to the upper layer, and continue to remove them until a clear zinc melt is formed.Then, the remaining zinc melt is separated into upper, middle and lower layers according to purity. The product was put into a mold and molded by cooling.

The purity of zinc regenerated in this manner is about 98.0-98.4% by experiment, and the recovery rate is about 79.0-82.0%.

However, the conventional zinc regeneration method dissolves zinc dross and then separates various suspended solids and AL, Fe, Zn, and Pb contained therein by using only a simple physical specific gravity difference. There is no choice but to.

Therefore, it takes a lot of time according to the regeneration treatment, it is inefficient and requires a lot of attention even in the process of removing impurities, workability is not good.

In addition, when the molten zinc is regenerated, it is difficult to expect a certain level of purity in each operation because the purity of the melt is formed according to the difference in specific gravity.

In addition, since the heating and settling time after melting is long, fuel consumption is high and the amount of recovery per unit time is uneconomical.

In particular, the conventional method is to remove the suspended solids suspended on the upper surface with a simple specific gravity difference, so that a large amount is removed along with the pure zinc also suspended matter in the process of removing the suspended solids. .

The present invention has been made in consideration of the above-mentioned conventional problems, and its object is to provide FeAl ₂ or Fe by an amount of Al that is difficult to remove from impurities that can not be added or contained in the plating process, and is appropriately added together with a separation promoter. The present invention provides a zinc dross regeneration method for regenerating pure zinc by causing a chemical reaction with a compound of FeAl ₃ to be recovered in an ash state.

The present invention for achieving this purpose is zinc de After analyzing a metering and component Los was placed in a crucible, dissolved by heating to a high temperature, sufficiently stirring Sikkim as well as FeAl _2, or by introducing a suitable amount of Fe according to the weight ratio of Al A chemical reaction is carried out with the compound of FeAl ₃ and carbonaceous separation accelerator is added to promote the separation of the compound and the melt, which is then settled for a certain period of time to remove the suspended ash in the suspended state to regenerate pure zinc. It is characterized by.

Figure is a block diagram showing the process sequence of the present invention

Hereinafter, the present invention will be described in detail according to the attached process sequence.

Zinc dross used in the present invention is generated after the plating process in steelmaking and plating companies, the zinc dross may have various forms, but the zinc purity is about 94-96%, among which the impurities Al is 1.5-3. %, Fe is 0.5 to 0.9%, Pb is 0.05 to 0.1%, and other various impurities are contained in a small amount.

The main principle of the present invention is to regenerate pure zinc by dissolving and stirring zinc dross, adding an appropriate amount of Fe, and adding a separate separation promoter to remove impurities by a chemical reaction method.

This regeneration method is described in detail according to the process sequence as follows.

First Step (Measurement and Component Analysis)

In steel mills and plating companies, zinc dross recovered in the form of mass is accurately weighed, and samples are taken for analysis.

Sampling for component analysis should be taken by stirring in the state of molten zinc dross, but in consideration of the efficiency of the operation, the sample is collected by site in the ingot state in which zinc dross is recovered. Analysis will be more efficient.

This process is intended to accurately estimate the amount of addition of Fe to cause the separation accelerator and chemical reaction to be added in a later process.

2nd process (melting)

After completion of the metering and component analysis, the zinc dross is sufficiently heated and dissolved with a conventional heater so that the temperature of the melt can be about 600-700 ° C.

When dissolving, zinc dross may be heated in a known reflection furnace or crucible furnace, but heating in a crucible furnace may increase dissolution efficiency.

3rd process (chemical reaction and stirring)

Depending on the weight of Al in the melt, the weight of Fe, which is about 50 to 120 mesh (powder) in powder state, is calculated and added in an appropriate amount, followed by stirring sufficiently using a stirrer to cause a chemical reaction between Fe and Al.

The chemical reaction of Fe and Al is shown in the following equation (1).

Fe (55.85) + 3Al (26.97) → FeAl ₃ (136.76). … … (One)

Naturally, the amount of Fe added to the melt should be varied depending on the Fe and Al content in the zinc dross.

For example, if the weight of zinc dross is 1000 kg and the impurities contained are 0.7% (7kg) of Fe and 3.0% (30kg) of Al,

Total Fe (kg) = 30kg ÷ 26.97 (Al) × 55.85 (Fe) / 3

= 20.7 kg.

However, since 7.0Kg of Fe is present as an impurity in zinc dross

Actual Fe (kg) = 20.7kg-7.0kg

= 13.0 kg of Fe will be injected.

After the Fe is added as described above using a randomly prepared stirrer and sufficiently stirred for 1-3 hours.

At this time, it is required that the upper and lower layers should be evenly mixed and maintain the optimum stirring state in which air can flow into the center.

The stirrer may be a general known stirrer, but it can be seen that it is most preferable to use a stirrer having the specifications as shown in Table 1 by experiment.

Table 1

division Contents Length of stirring blade 250 mm Wing and distance 3 at 120 ° intervals Wing structure Multilayer structure R. P. M 50- 80 times / min Wing angle 45 ° Side wing 3 angles 45 ° at 120 ° intervals

When sufficient stirring is performed, Al, which is an impurity in zinc dross, may be smoothly substituted with Fe. Accordingly, impurities substituted with FeAl ₃ or FeAl ₂ are floated to the upper layer in the ash state because of low specific gravity.

4th process (separation accelerator)

After sufficient stirring for 1-3 hours in the previous process, separate separation promoter is added to the melt.

At this time, the separation promoter should be sprayed evenly on the surface as a powder state to fully function in the upper and lower stirring state to promote the separation of the melt and FeAl ₃ and oxide.

The main component of the separation accelerator is carbon-based, and they are mixed in a low specific gravity state with a multi-step process. They are strongly adsorbable with oxides, so that they are suspended in the upper portion by adsorbing the oxides in the melt to lower specific gravity, thereby helping to obtain pure molten zinc. Will be.

Components of the separation accelerator are shown in Table 2 below.

Table 2)

ingredient content(%) ingredient content(%) Na 14-18 F 0.5-1.0 Cl 25-30 Ca 0.5-1.0 Zn 3.8-7.5 Si 0.1-0.4 Mg 0.5-0.8 C 41.3-55.6

5th process (finishing process)

In the previous process, the melt after the chemical reaction is in the form of a mixture having various specific gravity, which is allowed to stand for 20 to 40 minutes so that separation due to physical specific gravity difference occurs.

After standing, the oxide, FeAl _3, FeAl _2, etc., which float to the upper part of the melt, are rolled out thinly to clean the melt, and then stirred with a stirrer for 5-10 minutes to uniform the specific gravity of the zinc melt in the molten metal.

Subsequently, the molten material was put into a mold and cooled to be commercialized to complete all the regeneration processes. The regenerated zinc was found to have a purity of 99.0-99.4% by its own experiment, and the regeneration yield was about 88-92%. .

As used in this process, it has a structure that can easily remove the impurities floating in the upper part of the melt, and it is preferable to use a hole having about 8-10 mm holes perforated at equal intervals. As long as the recycled zinc can be molded into a size and shape for easy storage and handing.

Looking at the embodiment according to the regeneration process of the zinc dross as described above are as follows.

Example 1

As a result of analyzing the raw materials to be regenerated, 950 kg of zinc dross consisting of 96.2% of Zn, 2.9% of Al, 0.8% of Fe, 0.01% of Pb, and 0.8% of other materials was placed in a crucible furnace, and heated to 690 ° C ± 10 ° C to dissolve.

Into the melt dissolved as described above, 11.4 kg of Fe of 50 meshes was added and stirred by a stirrer for 2 hours to cause a chemical reaction. Then, 2.9 kg of a separation promoter was added and stirred for 20 minutes.

After stirring, the mixture is allowed to stand for 30 minutes to allow impurities to float to the upper part of the melt, and then the impurities are removed and the pure melt is stirred again for 10 minutes.

The process of evenly stirring the pure melt from which impurities have been removed is to maintain a constant purity, and after stirring, zinc dross could be regenerated by cooling into a mold and cooling.

At this time, as a result of analyzing the recycled zinc it was found that 99.3% pure zinc, 0.35% Al, 0.26% Fe, 0.01% Pb, 0.08% other, so that 865kg (91.0% recovery recovery) was obtained.

Example 2

In another embodiment, 860 kg of zinc dross having Zn 95.7%, Al 3.2%, Fe 1.0%, and other 0.1% is placed in a crucible and heated to 650 ° C. ± 10 ° C. for melting.

10.4 kg of Fe of 120 mesh was added to the melt, followed by stirring for 2 hours by stirring with a stirrer, and 1.7 kg of a separation promoter was added thereto, followed by stirring for 30 minutes.

After stirring sufficiently, the mixture is allowed to stand for 30 minutes to remove impurities floating on the upper part of the melt, and the pure molten metal is stirred and molded again for 10 minutes to form 99.2% pure zinc, 0.39% Al, 0.35% Fe, and other 0.06% recycled zinc 598 kg ( Recovery rate 88.9%).

Example 3

As another example, 680 kg of zinc dross containing 96.1% of Zn, 2.7% of Al, 1.0% of Fe, and other 0.2% is placed in a crucible, heated to 620 ° C ± 10 ° C, and melted, and 80 meshes of 5.8kg are added. Stir for 30 minutes and let stand for 20 minutes.

When it is settled, it removes the impurity floating on the upper part of the melt and stirs the pure melt again for 10 minutes to form it.99.2% pure zinc, 0.40% Al, 0.37% Fe, 0.03% other recycled zinc 598kg Could get

As in the above embodiment, by regenerating zinc dross according to the method according to the present invention, it can be recycled to pure zinc in which impurities are removed to the maximum.

As described in detail above, the present invention is easy to regenerate by dissolving zinc dross and adding Al and Fe promoters with an appropriate amount of Fe to react with Al and Fe contained in the zinc dross as a compound of FeAl ₃ or FeAl ₂ . By removing it, it has the effect of being able to reproduce with pure zinc.

In addition, it is an advantage that the treatment time is shortened by the separation method by chemical reaction rather than the method using the physical specific gravity difference as in the prior art, and the heating time due to dissolution is shortened, the fuel consumption is low, economical, pure zinc As the maximum recovery is possible, the recovery rate is also improved.

Claims (3)

In melting zinc dross to regenerate pure zinc, Metering and component analysis to measure zinc dross and to collect a sample and analyze the components; Dissolving by injecting zinc dross into a crucible furnace and heating it to melt the temperature of the melt to be 600-700 ° C .; Depending on the Al content in the melt, about 50 to 120 mesh of powdered Fe is added and stirred for 1-3 hours with a stirrer to cause Al and Fe to react with FeAl ₃ and FeAl ₂ compounds. Chemical reaction and stirring process; A separation accelerator injecting step of spreading the powder-based separation accelerator made of carbon-based evenly on the surface of the melt to be stirred to promote separation of the melt, FeAl ₃ and oxide; The melt is allowed to stand for 20 to 40 minutes to allow separation due to physical specific gravity difference, and the oxides, FeAl _3, FeAl _2, etc., which float to the upper part of the melt, are thinned out to clean the melt, and then 5 to 10 with a stirrer. A post-treatment step of uniformizing the specific gravity of the molten zinc in the molten metal by stirring for a minute, and putting it in a forming mold and cooling the product to produce a zinc dross regeneration method. The method of claim 1, The chemical reaction of Fe (55.85) + 3Al (26.97) → FeAl ₃ (136.76) is performed by adding Fe to remove AL or AL oxide present in zinc dross to be recycled in the chemical reaction process. Zinc dross regeneration method characterized by. The method of claim 1, Separation promoter in the above process is Na 14-18%, Cl 25-30%, Zn3.8-7.5%, Mg 0.5-0.8%, F 0.5-1.0%, Ca 0.5-1.0, Si 0.1-0.4%, C A method for regenerating zinc dross, characterized by forming 41.3-55.6% of the compound as a compound.