Method for the production of high-concentration manganese mini-tablets for alloying aluminum baths and device for implementing said method

Abstract

The method has the aim of obtaining Mn mini-tablets with a concentration of the metal ranging between 90 and 98%, Al particles being the binding element. The method is based on the use of ground electrolytic Mn from shales with a chemical purity of 99.7% or higher. The product is screened with a mesh of less than 450 micra, wherein the fine powder content should be less than 15%. Moreover, atomized powder Al obtained by mechanical processes with a granulometry of between 100 and 800 micra and with over 80% of the powder being between 350 and 720 micra should be used in the method. The method is carried out in a device having a storage hopper ( 1 ), a diffuser ( 4 ) of the product in the hopper ( 1 ), a hopper for compacting and shaping the mini-tablets in molds ( 9 ) in combination with pressing punches ( 7 and 8 ) and with the aid of an alveolar and dosing valve ( 10 ) mounted between the feed chamber ( 5 ) and the compacting chamber ( 6 ).

1 . A method for the manufacture of high concentration manganese minitablets for aluminum bath alloying which, having as its object the production of Mn minitablets or tablets with a concentration between 90 and 98% of said metal, starting from a mixture of powdered Mn Al, for the alloying of aluminum and other metal baths, which comprises using electrolytic Mn ground from flakes of a chemical purity of 99.7% or more, and Al powder atomized by mechanical means, with a controlled grain size distribution between 100 and 800 microns, and with over 80% powder between 350 and 720 microns, while a check is made on the Mn grinding such that a content of fine Mn powder with a size of less than 100 microns, is not more than 15%.  
     
     
         2 . The method for the manufacture of high concentration manganese minitablets for aluminum bath alloying, according to  claim 1 , characterized in that the ground electrolytic Mn is subjected to a screening process with a sieve with a mesh of less than 450 microns.  
     
     
         3 . The method for the manufacture of high concentration manganese minitablets for aluminum bath alloying, according to  claim 1 , characterized in that the level of the Mn and Al, mix in the corresponding compacting means monitored by respective sensors to keep this mix level between limits that assure the execution of the actual compacting.  
     
     
         4 . A device for the manufacture of high concentration Mn minitablets for aluminum bath alloying, designed for the execution of the procedure of  claim 1  starting from a mixture of ground electrolytic Mn powder and atomized Al powder, said device comprising: 
 a mix storage and reception hopper;    a compacting means in a suitable compaction chamber with dies in which the minitablets are formed, comprising punches both for pressing and ejecting the formed tablets, wherein the storage hopper is provided with a central diffuser that diverts the product towards the sides of the hopper, thereby preventing said product from passing directly to the respective feeder and compacting chambers, including between the feeder hopper and the compacting hopper; and    a honeycomb valve for dispensing product to the respective dies forming part of the compacting chamber in which the minitablets are formed; said honeycomb valve being designed to be divided sectorally so as to go on supplying the doses of product to the compacting chamber individually, with the result that each of the dies is filled for subsequent compacting, formation of the tablets and their ejection by means of the respective fixed punches, which act in combination with other moving punches to carry out the compacting and pressing of the product in the dies.    
     
     
         5 . The device for the manufacture of high concentration Mn minitablets for aluminum bath alloying, according to  claim 4 , further comprising three electrical product level sensors in the compacting chamber to monitor the maximum level A, the minimum level B and the safety level S, which determine the correct compacting of the product in the dies.