SU1766999A1 - Furnace for metallic melt filtration - Google Patents

Abstract

Essence: the chamber is made with loading and drain openings, heaters and a lid. In front of the drain hole, there is a filtering wall mounted inclined to the bottom. Under is made with a slope to the filter wall. The angle between the bottom and the filter wall is 50-65 °. The size of the openings of the filter wall is 1-2 mm. The invention allows the filtration of dross at low temperatures and the use of filters with a minimum amount of filter holes, which reduces the iron content in the filtrate. 1 h. apt. 3 il.

Description

The invention relates to metallurgy, in particular, to the extraction of metals from waste generated during the deposition of metallic coatings on rolled steel by the method of immersion into a melt.

During the coating process, solid particles of iron-containing and oxygen-containing compounds, dross, which contaminate the molten metal of the coating and impair the quality of the coating, are formed as a result of the interaction of the steel base, metal coating and oxygen of the air. The resulting dross is periodically removed from the surface of the melt, but with it the melt is also partially removed, which increases the consumption of metal-coating per unit of production. To reduce its consumption, it is advisable to remove it from the dross and return it to the bath with the melt.

A filtering device for molten metals, mainly aluminum, is known, equipped with a horizontal separating wall-filter mounted on a frame. The molten part of the mass passes through the filter into the lower part of the device, from where it flows out through an opening (application no. OC.3.151 434. Germany, MKI C 22 9/02).

A disadvantage of this device is the incomplete separation of the melt, since Filtration of the melt with a high content of solid particles (about 50%) is slow. As a result, the cooling takes place and the filter holes are plugged. In addition, the lower layers of solid particles are sealed and the filter holes are also blocked.

Known installation for the extraction of zinc melt from dross, forming-H

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Yu Yu

when galvanizing, including a double receiving plate with a hole of 5-25 mm in the bottom of the upper plate where the dross is loaded (for No. 58-26, Japan. From 22 to 19/30). At the end of filtration, the plates are subjected to vibrations with a frequency of 100–5000 vibrations per minute with an amplitude of vibrations of 1.0–0.1 mm.

The disadvantage of this setup is the slow filtration rate and the partial passage of the fine particles of the dross along with the melt through the filter hole, which contaminates the filtered melt.

The closest in technical essence and the achieved positive result to the proposed one is a dross oven. including a housing with a drain hole in the end wall, under, made with an inclination to the filter hole, heaters placed in the walls of the housing and the bottom, a cover. The furnace is used in the method of filtering zinc dross formed during continuous galvanizing (US Pat. No. 4.221.591, C 22 B 19/02, C 22 B 19/30). This furnace allows you to maintain the Dross placed in it at 460-850 ° C -

The disadvantages of the design of this furnace are the high content of harmful impurities of iron in the filter section. The solid particles of the dross are fine-crystalline and when they are filtered through small holes, the process proceeds at a low speed, especially at the end, when the flow of the liquid phase slows down. An increase in the slit width or an increase in the process temperature leads to contamination of the filtrate with iron due to the ingestion of crystals of iron-zinc compounds and dissolved iron (as the temperature increases, the solubility of iron in the melt rises), which, once again, enters the bath from the melts.

The aim of the invention is to improve the quality of the filtrate.

This goal is achieved by the fact that the known device for filtering zinc dross, comprising a housing with a drain hole in the end wall, a filtering element, underneath, tilted to the filtration opening, heaters placed in the walls of the housing and a hearth, a cover according to the invention. additionally equipped with a filter element made in the form of a perforated wall mounted in front of the filter hole at an angle of 50-65 ° to the hearth.

In addition, the perforation size of the filter element is 1-2 mm,

FIG. 1-3 shows a general view of a melt filtration furnace.

The furnace for filtering metal melt includes a housing 1 with a drain hole 2 in the end wall 3, a filtering element 4, under 5, inclined to the filtering hole, heaters 6 placed in the walls of the housing and the floor, and a cover 7.

The furnace works as follows.

The dross removed by the scoop from the surface of the molten bath of the metal coating unit based on zinc and aluminum is loaded into the furnace, closed by the lid 7, maintained at the temperature of the molten metal until the liquid metal is completely drained. Then the lid 7 opens and the solid phase of the dross is removed from the furnace.

Installing the filter element inside the oven prevents frostbite of the filter holes. This contributes to the most complete extraction of the liquid phase at low (460 ° C) temperatures, which ensures a reduction in the concentration of iron in the filtered zinc. Installing it at an angle of 50-65 ° to the hearth allows you to partially prevent clogging of the filter holes due to spontaneous falling of solid particles from the surface under the action of gravity.

Example. For experimental verification of the advantages of the proposed furnace design, an electric furnace was used, the internal dimensions of which were: width 200 mm, length 200 mm, height 200 mm. The hole formed by the inclined hearth and the front wall had a height of 8 mm. To filter the dross in the furnace of the proposed construction, a vertical filter with holes of 1-2 mm in size made of fiberglass was installed into it at a distance of 10 mm from the front wall. In all cases, 53 kg of dross was loaded immediately from the zinc bath.

The results of filtering dross in the furnace of the prototype construction and using a vertical filter are presented in the table.

As follows from the table, an equal amount of the liquid phase is achieved in the prototype only when the dross is overheated to 600 ° C. When this occurs, a significant increase in the concentration of dissolved iron, which leads to a further re-release of particles of dross.

Claims (1)

The use of a furnace of the proposed design allows the liquid phase to be extracted without overheating the dross and, therefore, without contamination of the filtrate with dissolved iron. Claim 1. The furnace for filtering a metallic melt, preferably zinc dross, comprising a housing with a drain hole in the end wall, a filter element under, made with a slope to the filter hole heaters, placed in the walls of the casing and the bottom, the boot device and the cover, characterized in that, in order to improve the quality of the filtrate, it is equipped with an additional filter element made in the form of a perforated wall mounted in front of the filter hole with an inclination to the bottom at an angle of 50-65 ° . 2 A furnace according to claim 1, characterized in that the size of the perforation of the wall is 1-2 mm. // S. /////, Fig.C ± vwbv, J;: VbVbqf / 7 / / / / // / / / tЈ  P Jm / //. / ", FIG. five