US1631423A - Method of purifying iron scale - Google Patents

Description

June 7, 1927.. 1,631,423

A. LUCAS METHOD OF PURIFYING IRON SCALE 7 Filed May 16, l925 INVENTOR /7/770/7 Z (/6451 BY ATTOR N EY Patented June 7, 1927.

UNITED s'TATEs' i 1 its 1,423-

ANTON LUCAS, or KANSAS cIrY, mssoun'r.

mrrnon or runrr mc moi: scans.

' Applicati olifiled n'ovember 1c, 1925. Serial no. 69,333.- j

My invention relates to a method of purifying iron scale as a step 111 the manufacture of an aluminothermic mixture, of a character particularly adapted for use in,

5 welding car rails and making heavy repairs, as of iron or steel beams, girders or the like, the principal object of the invention being the separation of sand, dirt or other foreign matter from the scale, to provide a mechanically pure product and insure against variability in chemical reaction due to unbalanced oxide content in the mixture.

A mixture of the character described consists of calcined ferroso-ferric oxide and a powder of aluminum or other metal or alloy capable of reducing the oxide. For convenience, only aluminum will be hereinafter mentioned as the reducing agent, with the understanding that other metals or alloys capable of performing the reduction may be employed as .well, without departing from the invention.

may be secured from different sources, as

- from magnetic iron stone or otherore, the

what-large quantities, has been fed bacli tothe blast furnace as an addition to the charge, but considered of inferior value,

partly because of its impurities, principally mechanical, due to the presence with the scale of mill dust and frequently small -pieces of iron. Scale of this kind before mixture with the aluminum element is'calcined or roasted, preferably with an om'dizing flame to drive off any liquid content or chemical impurities, oxidize any particles of iron present with the scale, and make the oxygen content uniform. 7

When so treated the roasted product is screened, and. in some instances attempt is made to separate the scale from its impuri ties by magnetic treatment. I- have found, however, that screening or sifting is ineffectual, as any mesh coarse enough to pass the scale flakes or particles will also pass solid impurities such as sand, brick or iron particles of such size and in sufficient quantities to affect reaction in the reducing crucible. The scaleflake is quite brittle and may be pulverized in a crusher under a the .one yieldably and the other fixedly, and

hopper 5 and cascaded from the rolls screen 7.

While oxide desirable for the macbiiief pressure which will not affect the harder particles constituting the impurities, V I have, therefore, added toth e customary process of purifying the scale, a mechanical step consisting of crushing -the scale between relatively soft rollers, having suflicient tension to pulverize the scale, but yieldable to the harder particles, and then separating product by airblast or, fine screening or both. I

The accompanying drawing illustratesa' form of crusher which maybe employed for the purpose, consisting of rubber or like rolls 1, on shafts 2, journalled in a frame 3,

driven by a belt l-to rotate the rollers in the opposite directions and feed the mixture 7 therethrough as in an ordinary mangle. The materlal may be fed t6 the rolls from a through an air blast, indicated by 6, onto a The loose roller is urged to contact with the fixed one by springs 8, sufficiently strong to press and crush the scale, but yieldable-to allow the loose'roller .tospread upon the passage of an excessively large solid particle I therethrough, the material of which the rolls are composed being sufliciently soft to 1 embed the usual run of hard material during the feeding travel. M

The drawing also illustrates thematerial and the methodof treatment, 9 designating the material coming tothe crusher, compristies, 10 a piece of brick,sand, iron or other 7 hard material'embedded in" the soft rollers,

ingthe scale flakes and commingled impuri-' 11, light dirt and dust separated fiom the heavier particles by the air blast, 12-the pure pulverized iron scale which is passed through the fine screen tohe collected in a 4 storage-receptacle and 13 the heavier im-f purities" which have been rejected by the screen. p v

I have found that by so treating the iron scale I eliminate impurities .which, if 31- lowed to remain in the scale, would upon the reaction produce gases that would remain in the solidified metal, causing blow holes and other defects, and a'nmch more effectivematerial may he produced with which a surer and more effective weld may be made. Inasmuch as mixture of the purified scale with proper reducing agents and the method of use of the mixture is well known, I

will not describe the same in detail, as neither the generic mixture, the welding process nor any specific apparatus for crushing the scale is claimed as my invention, the

5 invention including only the method of treating the scalefor purification.

What I claimjand desire to secure by Letters-Patent is 1. The method of purifying iron scale,

10 consisting of crushing the scale between crushing elements yieldable to s bstances of greater hardness than the sea e and then separating the light crushed substances from the other substances, and then separating the scale from the remaining substances. 2. The 'method of purifying iron scale,

consisting of passing mill scale between feeding rolls of a material sufficiently resistant to crush the scale, but yieldable to substances less brittle thanthescale, and then separating the light crushed substances from

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