RU2258579C1 - Method of granulation of molten metal and device for realization of this method - Google Patents

Abstract

FIELD: powder metallurgy; production of granules from melts by impact centrifugal spraying.

SUBSTANCE: proposed method includes passing the melt through hole in refractory material and crushing in vacuum chamber of hollow head whose cavity is preliminarily filled with low-melting material at low viscosity. Crystallization of drops is performed on side surface of vacuum chamber at residual pressure of no more than 0.1 kPa; these side surfaces are cooled on the outside with water. Device proposed for realization of this method includes metal receptacle and vacuum crushing chamber whose side surface is cooled with water; vacuum chamber is provided with hermetic vacuum cover with refractory guide tube inserted in it. Working surface of hollow crushing head is conical in shape and is provided with spiral blades; it is secured for free rotation. Granule receiver is made in form of two coaxial rings and is mounted on bottom of crushing chamber.

EFFECT: improved quality of granules; increased productivity; automation of sorting-out granules.

3 cl, 2 dwg

Description

The invention relates to powder metallurgy and can be used in the manufacture of metal granules from melts by shock centrifugal spraying.

A known method and device for producing metal granules of the company "UDDEHOLM LICENCING AKTIEBOLAG", which consists in the fact that a stream of molten metal is directed through a hole in the refractory material to a firmly fixed non-rotating ceramic head, mounted with the possibility of reciprocating motion, which sprayer crushes the stream of metal on drops. Drops fall into the tank with water and solidify in the form of granules that are automatically removed from the tank. (See patent EP No. 0402665 from 12/19/90). pleasing granulation method comprises melt metal reservoir, a movable head of the melt crushing chamber (reservoir), where the metal is crushed jet filled with water to cool the falling metal droplets, wherein the collection chamber lower part of the granules is conical.

However, the granules obtained by the above method must be dried to separate the moisture, and then in the tumbling machine to clean their surface of slag (see the magazine "Foundry" No. 6, p. 36).

In its technical essence, the well-known technical solution according to EP No. 0402665 is the closest to the claimed one and is taken as a prototype.

The aim of the invention is to improve the quality of the obtained granules, as well as increasing the productivity of the device and the automation of sorting granules.

To achieve the goal in a method for granulating liquid metal, including passing the melt through an opening in a refractory material, crushing it on a special head followed by crystallization of droplets in the chamber, according to the invention, the melt is crushed in a vacuum chamber on a hollow head, the cavity of which is pre-filled with fusible material with low density, and the crystallization of droplets is carried out on the side surface of the vacuum chamber at a residual pressure of not more than 0.1 kPa, while the side stems from the outside surface of the chamber is cooled with water.

In the device for granulating liquid metal containing a metal receiver, a refractory guide tube, a crushing chamber, a crushing head mounted coaxially to the refractory guide tube and a pellet collector mounted on the bottom of the crushing chamber, according to the invention, the crushing chamber is vacuum and is equipped with a sealed vacuum cover into which refractory guide tube, the side surface of the vacuum chamber is made with the possibility of cooling with water, while the head for crushing is made polo d, and its working surface is conical with spiral blades extending from the top of the cone and fixed with the possibility of free rotation, and the pellet collector is made in the form of at least two coaxial rings.

The proposed technical solution is illustrated by drawings. Figure 1 shows a General view of the device. Figure 2 shows the working surface of the head for crushing.

A device for granulating liquid metal consists of a metal receiver 1, for example, a metallurgical ladle, with a melt 2, a vacuum chamber for crushing 3, a sealed vacuum cover 4 with a guide refractory pipe 5 for forming a jet 6 of melt 2, coaxially mounted with the head for crushing 7, on the working the conical surface 8 of the head 7 is made of spiral blades 9. The head for crushing 7 is installed with the possibility of free rotation, for example, on the shaft 10. The pellet collector is made, for example, of two compartments - the middle ring Vågå compartment 11 and distal annular chamber 12 mounted at the bottom of the vacuum chamber 2. The airtight cover 3 has an opening 13 for connection to a vacuum pump.

The inventive method is as follows.

The melt 2 from the metal receiver (metallurgical ladle) 1 under ferrostatic pressure through the guide refractory pipe 5 enters the crushing vacuum chamber 3, equipped with a sealed cover 4 with a hole 13 for connecting a vacuum wire to the vacuum pump. The residual pressure in the crushing chamber 3 is created at a level of not more than 0.1 kPa, for example, with special liquid ring fore-vacuum pumps. The jet 6 of the melt 2, leaving the guide pipe 5, opens at a certain angle and enters the head 7 for crushing. The head 7 is made hollow and filled with fusible material, which gradually, melting, does not allow it to overheat. In this case, some heating of the head 7 prevents the formation of dust on it. In addition, the core of the metal jet 6, falling at the top of the cone of the head 7, begins to unwind it (head 7) on its working surface 8 with blades 9, and it crushes itself. Since the stream 6 of the metal falls without interruption, the head 7 spins with increasing speed. For this, the head is mounted on a freely rotating shaft 10.

Drops of metal are centrifugally scattered in the vacuum chamber 3 and, hitting the massive side surface of the vacuum chamber 3, instantly crystallize into granules and fall into the granule collector. Moreover, smaller droplets, having less kinetic energy, after bouncing from the wall of the chamber 3 will accumulate in the nearby compartments 11 of the pellet collector, and larger drops - in the distant compartments 12. Thus, the resulting powder is automatically sorted by granulometric composition. The side surface of the chamber 3 is cooled with water.

The performance of the device increases with increasing energy of the outflowing jet 6, i.e. when using large volumes of melt 2 and a decrease in residual pressure. In addition, the crushing of melt 6 in vacuum does not require additional processing of the resulting powder, because it does not oxidize.

In this way, high-purity powder can be obtained practically from a melt of any chemical composition, including the use of scrap and metal waste after their remelting.

Claims (2)

1. A method of granulating liquid metal, including passing the melt through an opening in a refractory material, crushing it on a special head, followed by crystallization of droplets in the chamber, characterized in that crushing is carried out in a vacuum chamber on a hollow head, the cavity of which is pre-filled with low-melting material with low density and crystallization of the droplets is carried out on the side surface of the vacuum chamber at a residual pressure of not more than 0.1 kPa, while the side surfaces of the chamber are cooled outside Doi. 2. A device for granulating liquid metal, containing a metal receiver, a refractory guide tube, a crushing chamber, a crushing head mounted coaxially to the refractory guide tube, and a granule collector mounted at the bottom of the crushing chamber, characterized in that the crushing chamber is vacuum and is equipped with a sealed vacuum cover in which the refractory guide tube is inserted, the side surface of the vacuum chamber is made with the possibility of cooling with water, while the head for crushing is made floor minutes, and its working surface - conical spiral blades emanating from the apex of the cone and is secured in a freely rotatable and granulosbornik is in the form of at least two coaxial rings.

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