US1478215A - Process for making agglomerates of fine ores - Google Patents

Description

CARL GIESEOKE, BAD HARZBURG, GERMANY.

PROCESS FOR MAKING AGGLOMERATES OF FINE ORES No Drawing.

Application filed February 17, 1921. Serial No. 445,828.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF IM IARCH 3, 1921, 41 STAT. L., 1313.)

To all whom it may concern.

Be it known' that I, CARL GmsnoKn, enineer, residing at Bad Harzburg, Free btate of Brunswick, Germany, have invented certain new and useful Improvements in Processes for Making Agglomerates of Fine Ores (for which I have filed applications in Germany Dec. 20, 1917; Luxemburg, Aug. 23, 1918), of which the following is a specification.

My invention relates to improvements in the process of making within blast furnaces sintered agglomerates of fine ores, flue dust, residues obtained from pyrites when roasting the same, and the like, and more particularly to the process in which the said matter is mouldedby pressure and brought into a blast furnace for being sintered therein by heat. In the practice of this process it has been found that a large proportion of the fuel distributed within the blast furnace and divided between the previously formed pieces of ore and the like is carried off by the current of the gases, which is particularly objectionable because the fuel is not uniformly carried off all over the crosssectional area of the furnace, so that the advance of the fire is irregular and the running of the furnace is interfered with. By using coke in the form of pieces better results are obtained in this respect, but such fuel is objectional in other respects particularly as far as the quality of the sintered matter is concerned.

For this reason it has been suggested to mix the matter to be agglomerated with the finely divided fuel required for sintering prior to moulding and supplying the same to the blast furnace. However, also this modification of the old process has proved to be unsatisfactory in various respects whereby a regular operation of the furnace is practically impossible.

The object of the improvements is to provide a'process which is satisfactory in the practical operation.

. In order to produce blocks or bricks of sufficient strength which can be brought into the blast furnace and do not burst prior to or during sintering it has been proposed to mould the matter under high pressure and in suitable presses, in which case a small amount of water has been added to the raw material, the operation being in this respect a dry pressin process which has been successful for ot 1er purposes for treating fine ore or cement. However, when applied to the object in view the said process has proved unsatisfactory, the moulded blocks consisting of fine ore and fine coke being decomposed within the blast furnace to such an extent that the fire is frequently extinguished or the flame burns only at one side of the furnace. The process can be improved to some extent by adding suitable binding media to the ore. But thereby the process loses its simplicity, and itis hardly more economical than the process in which a greater amount of the binding medium is added to the fine ore and sintering is entirely dispensed with before charging the blast furnace.

I have found the reason for this ObjQCtlOllable feature to reside in the fact that in a blast furnace the temperature rises too suddenly, so that a large volume of steam is suddenly developed, which tends to break up the moulded bricks. Though the amount of water within the bricks is small, yet the steam can escape only through minute passages, because by the pressing operation the particles are brought in close contact.

I have discovered that when adding a large amount of water the bricks are not burst by the steam if care is taken that the pores and passages are suificient to permit an unimpeded escape of the steam. However, when adding much water to the matter and moulding the same in the presses used in the dry pressing process no satisfactory re sults havebeen obtained. But when further increasing the volume of water and mixing the fine ore and fine coke in a press of the extrusion type in which the moulded matter is forced in the form of a continuous band through a nozzle, and thus moulding the matter by a wetpressing process, the moulded bricks cut from the band can be charged into th blast furnace without being pre viously dried, and they do not burst when being sintered.

In the wet pressing process the volume of water is considerably higher than in the dry pressing process; but I have found that an increased volume of Water in the bricks favors the ready escape of the steam. On the one hand theinnermost pores of the fine fuel (coke dust)- are permeated with water.

rig I 1 ,478,9 1 3 vaporization are sufficient to allow of aready escape of the steam. The volume of water forms so to speak a body of water which is gradually vaporized from'without and inwards so as be gradually reduced in diameter. I y

In this operation the fuel and the fine ore are mixed-in a most elfectiv'e Way, and the rigidity of the brick as against grinding in the blast furnace is increased, as compared to a process in which exclusively the fine ore is moulded in a wet pressing plant and charged into the blast furnace together with more or less coarse fuel. The improvement obtained by my process will be. understood from the following: If, for example, 8% of line coke are used for sintering, the volumetric ratio between ore and fine coke is In other words, the volume of the porous coke in the mixture is about I and as the ratio of the water absorbed respectively by the coke and by the ore is even higher, the capacity of the passages produced by the vaporization of the Water is considerably increased as compared to bricks having no admixture of coke.

As compared tothe process heretofore in use my improved process is preferable also in this respect that by vaporizing a large volume of water and burning the fuel admixed to the orc agglomerates of a high degree of porosity are obtained.

ln the practice of the invention I mix for example measured amounts of fine ore and powdered iokc or other suitable fine fuel or waste fuel at the ratio of 12:1 by weight together with a large amount of water withmm clay cutter or pug mill and I charge If now the temperature separate pieces. The short pieces produced thereby fall on a charging a paratus connected'with a blast furnace. 'Ehe blast furnace is run with a high flame, whereby the bricks are speedily heated to sintering temperature, as is desirable for various reasons in order to obtainthe best results. In some cases I add suitable reaction substances or bindingmedia to the fine ore before supplying the same into the mixer or pressing apparatus.

An important feature of m improved process consists in charging tlie moulded bricks into the blast furnace without previously drying the same.

I claim:

1. The process of utilizing finely-divided ore which consists in mixing the fine ore with powdered fuel and as much water as is necessary for moulding the mixture when the latter is extruded through a suitable die,

cutting said moulded material into separate pieces, and introducing said pieces into a blast furnace. a

2. The process of agglomerating matter containing ore which consists in mixing said matter with fine fuel and sufiicient Water for moulding in an extrusion press, moulding the mixture, and charging the moulded matter in a wet state into a blast furnace.

3. The process of utilizing finely-divided ore which consists in mixin the line ore with a binding media, fine fuel and sulficient water for moulding in an extrusion press, moulding the mixture, and charging the moulded matter in a wet state into a blast furnace.

4. The process of agglomerating matter containing ore, which consists in mixing said matter with fine fuel in the'proportion by weight of substantially twelve parts of ore to one part of fu l and a relatively large amount of water, charging the resulting plastic mass into an extrusion press, and in troducing the briquets thus formed in a Wet state into a blast furnace.

ln testimony whereof I have affixed my signature in presence of two witnesses.

CARL (HESECKE. Witnesses:

E. H. LAMBACH,

KARL FLorr.