JPS6045260B2 - Zinc recovery equipment for zinc dust - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zinc recovery device for recovering zinc from zinc dust generated during the process of galvanizing steel materials at a steelworks.

Zinc plays an extremely important role in anticorrosion coating methods for steel materials, and hot-dip galvanizing or electrolytic galvanizing is currently widely used.

A large amount of zinc dust is generated during the galvanizing process. Occur. Since this zinc dust contains a large amount of zinc, it has traditionally been collected using cyclones or bag filters and sold to zinc recyclers.

Zinc recyclers use a molding recovery method in which zinc dust is solidified using a briquette machine, tablet machine, press, etc., and then remelted in a melting tank to recover the zinc, and zinc dust is purified and recovered by dissolving it in a sulfuric acid solution. Metallic zinc has been remanufactured using either a wet recovery method, or an electrolytic recovery method, in which zinc dust is placed in an electrolytic solution and electrolyzed to recover zinc.

However, the former has a poor recovery rate, and because it is molded with impurities still in it, it has a low specific gravity and floats up in the plating bath when it is reused, making it difficult to dissolve. Although the latter can recover high quality zinc, it has the disadvantage of high cost. This invention proposes a zinc recovery device for zinc dust that eliminates these drawbacks and reduces the cost of galvanizing by refining and recovering the zinc dust in-house and reusing it for galvanizing. That is, this invention consists of a rotary furnace body which is equipped with a combustible separation device such as a cyclone, is rotatably supported by a hollow shaft and rotated by a drive device, and a heating device provided along the outer circumferential surface of the furnace body. Airtightly connect the tip of the supply pipe connected to the above-mentioned mixer of the zinc dust supply device, which consists of a zinc dust collection device and a mixer of zinc dust and inert gas, to the hollow shaft of the rotary melting furnace on the side that does not have a molten zinc outlet. and the other hollow shaft.
The gist of this invention is a zinc recovery device for zinc dust, in which the tip of a discharge pipe connected to the middle of the piping of a zinc dust collection duct connected to the zinc dust collection device is airtightly inserted. This invention transfers the zinc gas generated in the galvanizing process using an inert gas such as nitrogen or argon, and fills the furnace with the inert gas to generate zinc dust in a non-oxidizing atmosphere. Since the purpose is to recover zinc by melting, it is desirable that the piping and rotary melting furnace be connected in a closed circuit.

Further, it is desirable that the zinc dust collecting device uses a cyclone, a bag filter, etc., and a plurality of them are connected in series to be able to sufficiently collect fine dust. Next, a case in which the present invention is applied to steel pipe galvanizing treatment will be explained with reference to the drawings.

The rotary melting furnace 1 rotatably supports hollow shafts 2 to 2 protruding from the centers of both end faces of a horizontally placed cylindrical body, and a gear 3 is externally fitted to one of the hollow shafts 2. A rotary furnace body 6 is meshed with a gear 4 provided on the main shaft of the rotary furnace body 6 and rotates by the operation of a drive device 5, and a burner etc. provided on an outer cylinder 7 that is placed over the outer peripheral surface of the furnace body at intervals is inserted. Consisting of a heating device 8,
A solid-gas separator 9 consisting of a cyclone is installed inside the furnace body, and a molten zinc outlet 10 is provided on one end face.

The rotary melting furnace 1 is installed close to the galvanizing tank 24 [2, so that recovered molten zinc can be directly charged into the tank from the outlet 10.

Then, an inner surface blowing device 25 for the galvanized steel pipe 30 is provided near the galvanizing tank 24, and the inner surface of the pipe is cleaned with steam or inert gas sent from the steam or inert gas accumulator 26. . On the other hand, zinc dust collection devices 11 and 12 consisting of cyclones or bag filters are connected in series and connected to the inner surface blowing device 25 through a zinc dust collection duct 22, so that zinc dust can be collected by the suction action of an exhaust fan 13. Zinc dust collection device 11
, 12 have mixers 14 and 15 for mixing with inert gas, respectively. A zinc dust supply device 16 is configured by being connected. A bifurcated branch of the feed pipe 17 is connected to the bottom of each mixer 14, 15, and the tip of the pipe is airtightly inserted into the furnace from the hollow shaft 2 on the side that does not have the outlet 10. Active gas accumulator 18 and each mixture/aiki 14, 15
and a supply pipe 2 having an on-off valve 19 between each pipe branch part.
Connect with 0,21. On the other hand, the tip of a discharge pipe 23 connected to a zinc dust collection duct 22 is airtightly inserted into the hollow shaft 2 on the side having the outlet 10. In the figure, 31 is a blower, 2
7 is a zinc dust collection device 11, 12 and a mixer 14, 15
28 is a stop valve provided at each branch of the feed pipe 17, 29 is a stop valve provided in the discharge pipe 23, and 30 is a fitted steel pipe. Now, in the above-mentioned apparatus, the plated steel pipe 30 is attached to the internal blowing device 25, and the exhaust fan 13 and the internal blowing device 25 are operated to blow steam into the pipe.

Then, the generated zinc dust is sucked and reaches the zinc dust collection devices 11 and 12. In this step, most of the zinc dust is first captured by the cyclone, and the remaining fine particles of zinc dust are captured by the next bag filter, and almost all of the zinc dust is collected. When the collected zinc dust is concentrated in quantity, the stop valve 27 is opened to cut it into the mixers 14 and 15, and the on-off valve 19 is opened to feed inert gas and mix it.

Then, the stop valve 28 is opened to feed the mixture of inert gas and zinc dust into the rotary melting furnace 1. Zinc dust is heated in advance by a heating device 8 and fed into the rotary melting furnace 1, which is rotated by the drive of a drive device, and is separated by a solid-gas separator 9 and rotated in an inert gas atmosphere. It is rapidly heated and melted while frequently contacting the furnace wall and the already melted zinc bath.

It is preferable that the rotary melting furnace rotates in a reciprocating manner of about 90 to 180 degrees. Although the supply of zinc dust from the zinc dust supply device 16 to the rotary melting furnace 1 is performed intermittently,
While the stop valve 28 is closed and the supply of zinc dust is stopped, the stop valve 19 of the supply pipe 21 is opened and inert gas is fed into the furnace from the accumulator, and the furnace is operated while maintaining a non-oxidizing atmosphere. Also, in the furnace, molten zinc accumulates as it progresses from the inlet side to the outlet side, and when it accumulates appropriately, the outlet 1
0 reaches the phantom line shown in the figure, the furnace is stopped, the outlet 10 is opened, and molten zinc is charged into the galvanizing tank 24.

When undissolved zinc dust exists in the furnace, the stop valve 29 is opened and the zinc dust collection duct 2 is discharged from the discharge pipe 23.
2 and then returned to the zinc dust supply device 16.

This invention consists of a rotary melting furnace having a solid-gas separator and a zinc dust supply device that mixes zinc dust with an inert gas and supplies it continuously or intermittently. Since it can be efficiently recovered in a non-oxidizing atmosphere and charged into the galvanizing tank as molten zinc, the cost of galvanizing can also be reduced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an outline of an apparatus in an embodiment of the present invention. In the figure, 1...Rotary melting furnace, 2...Hollow shaft, 5...Drive device, 6...Rotary furnace body, 7
...Outer cylinder, 8...Heating device, 9...
・Solid-gas separator, 10... Outlet, 11, 1
2... Zinc dust collection device, 14, 15...
...Mixer, 16...Zinc dust supply device, 1
7...Inlet piping, 18...Inert gas accumulator, 23...Discharge piping, 25...
. . . Internal blowing device, 26 . . . Steam or inert gas accumulator.

Claims (1)

[Claims] 1. Melting in a rotary melting furnace consisting of a rotary furnace body equipped with a solid-gas separator consisting of a cyclone, supported by a hollow shaft and rotated by a drive device, and a heating device installed along the outer circumferential surface of the furnace body. The tip of the supply pipe connected to the mixer of the zinc dust supply device consisting of a zinc dust collection device and a mixer of zinc dust and inert gas is airtightly inserted into the hollow shaft on the side that does not have a zinc outlet, A zinc recovery device for zinc dust, in which the tip of a discharge pipe connected to the middle of the piping of a zinc dust collection duct connected to the zinc dust collection device is airtightly inserted into the other hollow shaft.