RU2280537C1 - Method for producing pellets of magnesium or its alloys - Google Patents

Abstract

FIELD: non-ferrous metallurgy, namely processes for producing pellets of magnesium or its alloys.

SUBSTANCE: method comprises steps of preparing salt mixture, loading magnesium or its alloy into melt salt mixture; agitating mixture, cooling it, milling for producing mixture of salt component and pellets; further separation of salt and metallic components in the form of pellets. Novelty is feed of milled mixture of salt component and pellets in compressed air stream; twisting flow in centrifugal chamber with tangential inlet; then removing salt component out of centrifugal chamber and depositing metallic components in the form of pellets onto bottom of centrifugal chamber; discharging pellets out of chamber. Air flow speed at inlet of centrifugal chamber is in range 50 - 400 m/s. Salt component discharged from chamber is directed to cyclone. Mixture of salt component and pellets is fed to compressed air stream by injection.

EFFECT: intensified stage of separating salt phase and pellets of magnesium or its alloys, possibility for producing improved-quality product.

4 cl, 1 ex

Description

The invention relates to ferrous metallurgy, in particular to methods for producing granules of magnesium and its alloys.

Known methods for producing granules of magnesium and its alloys (A.S. USSR 384423, publ. Bull. 12, 1978; 469295, publ. Bull. 30, 1978; 1030097, bull. 27, 1983; 1451989, publ. 10.09.95) by centrifugal spraying of molten metal from a perforated glass into an air atmosphere. To prevent active oxidation (burning) of liquid magnesium droplets at the same time as metal, a molten salt is fed into the rotating perforated glass in an amount of 21-45% by weight of the metal. The essence of the method lies in the fact that the molten metal, as a result of the pressure drop due to the action of centrifugal forces, is forced through the holes of the perforated glass in the form of jets, which, when dropped, break down into drops and crystallize in the atmosphere of air. Granules of various shapes and weights are fed to receiving hoppers and then for further processing. The method allows to obtain granules of magnesium in a salt shell, suitable for use as a reagent in ferrous metallurgy (desulfurization of pig iron and modification of melts), chemistry and petrochemistry.

The disadvantage of these methods is the low quality of the resulting commercial products.

A known method of producing granules of magnesium and its alloys (US Pat. USA No. 4297641, publ. 21.07.81,), coated with a protective salt coating. To do this, initially prepare a salt mixture consisting of salts of alkali and alkaline earth metals containing by mass more than or equal to 46% of alkali metal chloride, 0-25% of calcium chloride, 0-25% of barium chloride; less than or equal to 2% of metal fluorides; less than 22% magnesium chloride; less than or equal to 25% of other salts, additives or impurities inert with respect to magnesium and its alloys and not preventing the dispersion of magnesium and its alloy in a mixture of salts. The salt is melted together with a sufficient amount of magnesium or its alloy to obtain less than or equal to 42% of the molten metal in the total salt mixture. With stirring and at a temperature of 670-820 ° C, molten magnesium or its alloy is introduced into the salt melt. The resulting dispersed magnesium particles are cooled and ground.

The disadvantage of this method is that the magnesium content in the melt cannot exceed 42% by weight. In this regard, the method has a low productivity, and the resulting product must be subjected to a complex and time-consuming operation of separating magnesium from the salt mixture.

A known method of producing granules of magnesium or its alloys (Pat. SU No. 1361835, publ. 09/20/96, bull. 26), by the number of common signs adopted for the closest analogue prototype and including the preparation of a salt mixture of chloride of magnesium, sodium, potassium , barium and calcium, heating the salt mixture to a temperature of 670-820 ° C, loading ingots of magnesium or magnesium alloy into the melt obtained, so that the metal content does not exceed 60% by weight of the mixture. When the metal was melted, a dispersing agent was introduced into the melt. Then the melt was mixed for 10-40 minutes, then it was cooled, crushed, the metal was sieved and its particle size distribution was measured. As a dispersing agent, silicon oxide is used, introduced into the melt in the form of natural minerals, for example sand, in an amount of 0.25-1.0% by weight of the melt. As the initial melt, metal-containing waste from magnesium production or an artificially prepared mixture of magnesium, potassium, sodium, barium, and calcium chlorides with magnesium or magnesium alloys can be used. In this case, the content of granules in the melt can reach 60% of its mass.

The disadvantage of this method is the complexity and duration of the separation of the salt phase from the granules of magnesium, which increases the mass of granules and reduces the output of granules of magnesium in the form of a finished product.

The technical result is aimed at eliminating the disadvantages of the prototype and allows to intensify the stage of separation of the salt phase from granules of magnesium or its alloys, to obtain a product of higher quality.

The technical result is achieved in that in the proposed method for producing granules of magnesium or its alloys, including preparing a salt mixture, loading magnesium or its alloy into a molten salt mixture, mixing, cooling, crushing to obtain a mixture of the salt component and granules and the subsequent separation of the salt component and granules , new is that after crushing, the mixture of the salt component and granules is fed into a stream of compressed air, the flow is twisted in a centrifugal chamber with a tangential inlet, then the salt The solvent is removed from the centrifugal chamber, and the granules are deposited on the bottom of the centrifugal chamber and unloaded from the chamber.

In addition, the air flow velocity at the inlet to the centrifugal chamber is 50-400 m / s.

In addition, the salt component at the exit from the centrifugal chamber is sent to the cyclone.

In addition, a mixture of the salt component and granules is injected into a stream of compressed air.

The separation of the salt phase from the granules of magnesium in a centrifugal chamber with a tangential inlet by feeding the mixture with compressed air allows you to more fully separate the salt component from the granules of magnesium and thereby improve the quality of the resulting granules and intensify the process of separation of the salt component and granules of magnesium.

An analysis of the prior art by the applicant, including a search by patent and scientific and technical sources of information and identification of sources containing information about analogues of the claimed invention, allowed to establish that the applicant did not find a source characterized by features that are identical (identical) to all the essential features of the invention. The definition from the list of identified analogues of the prototype, as the closest in the totality of the features of the analogue, made it possible to establish a set of significant distinctive features in relation to the applicant’s perceived technical result in the claimed method for producing magnesium granules or its alloys set forth in the claims.

Therefore, the claimed invention meets the condition of "novelty."

To verify the compliance of the claimed invention with the condition "inventive step", the applicant conducted an additional search for known solutions in order to identify features that match the distinctive features of the claimed method from the prototype. The claimed features are new and do not follow explicitly for the specialist, since from the prior art determined by the applicant, the effect of the transformations provided for by the essential features of the claimed invention has not been identified to achieve a technical result. Therefore, the claimed invention meets the condition of "inventive step"

An example implementation of the method.

An experimental verification of the method for producing magnesium granules or its alloys was carried out using a stationary electric resistance furnace, in which a crucible with a capacity of 30 kg of melt and an electromechanical mixer with a capacity of 900 revolutions per minute were installed. A salt mixture consisting of magnesium chloride, sodium, potassium, barium and calcium in an amount of 3-12 kg was poured into the furnace, heated to a temperature of 670-820 ° C. Magnesium or magnesium alloy ingots were loaded into the melt, so that the metal content did not exceed 60% by weight of the mixture, and melting was carried out. Then the melt was cooled, crushed. The crushed particles of the mixture of the salt component and the magnesium granules were injected into the compressed air stream (pipeline) through a funnel and injected at a speed of 50-400 m / s into a centrifugal chamber with a tangential inlet, for example, a centrifugal classifier mill in which the flow of mixture particles and air was twisted by feeding it at an angle to the wall of the chamber. Then, the salt component was removed from the centrifugal chamber, and the granules were deposited on the bottom of the centrifugal chamber and unloaded in the tank as they accumulated. When particles collide with the walls of the centrifugal chamber, the salt phase is abraded, followed by its entrainment from the swirling flow and trapping in the dust cyclone.

This allows you to almost completely separate the salt phase from the granules of magnesium, to increase the productivity of the process and improve the quality of the granules.

Claims (4)

1. A method of producing granules of magnesium or its alloys, comprising preparing a salt mixture, loading magnesium or its alloy into a molten salt mixture, mixing, cooling, crushing to obtain a mixture of the salt component and granules and the subsequent separation of the salt component and granules, characterized in that after crushing a mixture of the salt component and the granules is fed into a stream of compressed air, the flow is twisted in a centrifugal chamber with a tangential inlet, then the salt component is removed from the centrifugal chamber, and the pellets precipitate They are buried at the bottom of the centrifugal chamber and discharged from the chamber. 2. The method according to claim 1, characterized in that the air flow velocity at the entrance to the centrifugal chamber is 50-400 m / s. 3. The method according to claim 1, characterized in that the salt component at the exit from the centrifugal chamber is sent to a cyclone. 4. The method according to claim 1, characterized in that the mixture of the salt component and the granules is fed into a stream of compressed air by injection.