Device and method for enhancing zinc yield from bottom dross

Abstract

A device for removing dross from the bottom of a molten metal bath comprises a perforated basket assembly for receiving said dross, pumping means for pumping said bottom dross and molten metal from the bottom of the molten metal bath into the perforated basket assembly when the perforated basket assembly is in a pumping position, lifting and / or rotating means for moving said perforated basket assembly from its pumping position out of said molten metal bath in a separation position and in a disposal position and separation means for separating said bottom dross from said molten metal, wherein the separation means comprise a paddle assembly capable of contacting said dross inside the perforated basket assembly with a cutting action in a first position followed by a cutting action in at least one adjacent second position, when the perforated basket assembly is in the separation position.

Description

[0001] The present invention generally relates to the recycling of bottom dross formed in molten metal baths, such as during hot dipped galvanizing processes, and particularly to a device and process for removing bottom dross from a kettle of molten metal. BACKGROUND ART [0002] In the hot dipped galvanizing art, practitioners have long combated the formations of dross at the bottom of the galvanizing kettles. Bottom dross is a slushy mixture of pure zinc and iron / zinc crystals. The bottom dross is frequently removed for processing to prevent fouling of the surface of the galvanized metal products and to recover the zinc retained in the dross. [0003] Even most contemporary procedures for removing bottom dross in hot dipped galvanizing kettles are relatively crude, generally labor intensive and dangerous for the operators using the removal equipment. The current removal processes generally consists of one of four methods. [0004] The first method involves the use of a drag bucket in wh...

AI Technical Summary

Benefits of technology

The present invention proposes a device for removing dross from the bottom of a molten metal bath. The device includes a perforated basket assembly for receiving the dross and pumping it out of the bath. It also includes lifting and / or rotating means for moving the basket assembly to a separation position where the dross can be separated from the molten metal. The device has several advantages, including reducing the risk of bodily injury, minimizing the amount of usable metal in the dross, and saving labor and material costs. The invention also provides a method for efficiently coalescing the molten metal and a recycle bin for the separated dross. The device can be used in a continuous or batch-like manner and can be controlled to prevent the dross from returning to the bath.

Problems solved by technology

Even most contemporary procedures for removing bottom dross in hot dipped galvanizing kettles are relatively crude, generally labor intensive and dangerous for the operators using the removal equipment.

The process is lengthy due to the fact that the spoon is only several inches wide and the kettle is several feet long.

The positioning mechanism does not allow to reach the entire surface of the bottom of the pot and no mention is made about how this mechanism is operated.

This device does not enable the removal of bottom dross and the document is not concerned with problems arising from the higher density of the bottom dross, such as the higher initial content of molten metal in the bottom dross or the contamination of the bath with sinking particles of dross, the resultant risk of surface fouling or even of extended interruptions of the normal galvanizing operation needed for the settlement of such resuspended particles.

Furthermore, the agitation action of the dross is limited to an up and down reciprocating motion (chopping) due to the movement of the chopping blades alone or to a combined reciprocal movement of the blades and the basket.

Finally, dumping problems and perforation obstruction may arise when the dross chills out too fast in the basket.

Accordingly, a number of problems and disadvantages remain in the removal of bottom dross from molten metal baths, such as an insufficient separation of the dross from the molten metal, insufficient reliability and safety, compulsory interruptions of the galvanizing process, product quality problems due to surface fouling, solidification and obstruction problems, etc.

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