PROCESS FOR THE ADDUCTION OF METAL ELEMENTS IN METAL FOUNDINGS

Abstract: Process for the adduction of chemical-metal elements in metal foundings where the additive element is brought to the plasma status and, by means of an inert carrying gas, is caused to spread in the fluid mass of the metal founding. The additive element is brought to the plasma status by using an electric arc.

Description: Disclosure of the invention The present invention refers to a process for the adduction of chemical-metal elements in metal founding, particularly cast irons and steels. In the field of the cast irons three of the most important application are constituted by the spheroidizing of the graphite obtained by the adduction of the magnesium, the desulphurization and the refining or " purification " of the bath from the presence of indesired elements. In the field of the steels, beside the desulphurization and the refining, another of the most important applications is constituted by the deoxidation and by the final control of the obtained structure. The magnesium, as adduction chemical element , is utilized in large quantity as in spheroidal graphite cast irons; it is added exclusively at the solid status: pure or in alloy, powdered or greatly sized, by diping or insufflation in the melting bath of cast iron or in the flask in which the cast iron will be cast. All these methods used at present do not permit sufficient efficiencies of reaction, therefore they are economically expensive and do not permit to regulate and control opportunely, according to the various requirements the level of the reaction progress. Moreover it is required a considerable phisical effort for inserting the adduction metal element in the bath or in the flask because the operator is struck by the remarkable heat of the bath container, constantly at a high temperature. Another drawback is the considerable pollution of the working place because of the enormous uncontrolled evolution of magnesium oxides. It is the purpose of the present invention to overcome the above described drawbacks. The technical problem to be solved was to find a process for the adduction of chemical-metal elements in metal founding without the phisical intervention of the operators and to be able to control, pilot and regulate the reaction. The solution of technical problem is characterized by the fact that the chemical-metal elements of adduction are brought to a plasma status and in such a status, they are transferred by the utilization of an inert carrying gas in the metal foundings, means being provided for bringing said elements to the plasma status. Further characteristics and advantages will become more readily apparent from the following description and from the enclosed drawing in which the figure represents schematically the process object of the present invention. The process consists in bringing the adduction element to the plasma status and in such a status let it spread in the liquid mass of the metal cast . Said adduction element is brought to the plasma status by the establishment and the maintaining of an electric arc and it is transferred to the bath formed by the cast by means of an inert carrying gas. With reference to the figure, the inert carrying gas, which may be for example mitrogen, is inserted in a reactor I0 through the input II and it strikes the electric arc formed by the plasma and generated by the electrodes placed in I2 and subjected to a predetermined voltage. The metal material, by which the electrodes are formed, magnesium in the described example, is vaporized by the energy produced by the electric arc according to an energetic balance taking in account the transports of matter, charge and energy from the plasma column to the electrodes and vice versa. The material, vaporized and transported by the inert gas, crosses longitudinally the reactor I0 and it is observable through special holes I3. Said vaporized material comes out from the reactor I0 through the flange I4 which operates the connection with the column of cast metal.This is not schematized because it may be a whatever container of various type, form and size apt to receive the cast metal. The electric arc, fed in alternating current, is provided with a device able to assure the automatic regulation of the reciprocal distance of the electrodes according to their wear.

Claims: I. Process for the adduction of chemical-metal elements in metal foundings, particularly cast irons and steels, characterized by the fact that said elements are brought to the plasma status and in such a status transferred by the utilization of an inert carrying gas in said metal foundings, means being provided for bringing said elements to the plasma status. 2. Process according to the claim I, characterized by the fact that said means are constituded by an electric arc, said elements forming the electrodes, being vaporized by the energy produced by said arc according to an energetic balance taking in account the transports of matter, charge and energy from the plasma column to the electrodes and vice versa. 3. Process according to the claims I and 2, characterized by the fact that said inert gas is inserted in a reactor and strikes said electric arc, said elements are the plasma status being brought by said gas out from said reactor through a flange connected with the column of cast metal. 4. Process according to the claims I-3, characterized by the fact that one of said elements is magnesium. 5. Process according to the claims I-3, characterized by the fact that said inert carrying gas is nitrogen. 6. Process for the adduction of chemical-metal elements in metal foundings, particularly cast irons and steels, according to what above described and illustrated in the enclosed drawing.

Inventors: SOLA, GIUSEPPE, ING.
Applicants: NECCHI SOCIETA PER AZIONI
Application year: 1987
Main classification: C21C1
IPC codes: B22D27, C22B9, C21C7, C22B4, C21C1