US1222893A - Agglomeration of fine ores and flue-dust. - Google Patents

Description

E SAS PATENT @FFTCE WILHELM SCHUMACHEB, bF BERLIN, GERMANY, ASSIGNOR TO GENERAL BRIQUET'IING COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE.

AGGLOMERATION OF FINE ORES AND ELITE-DUST.

No Drawing.

particularly the sintering and roasting of fine ores, concentrates, fiue dust and the like and has for its object the accomplishment of such agglomeration using the said ores in the form of small, ball-like briquets, and employing ordinary furnaces, such as shaft furnaces. This and other objects as will hereinafter appear are attained in the following manner.

The fine ore or equivalent material is first molded into small briquets having substantially the form of regular solids the surfaces of which are curved; for example, the briquets may be spherical or egg-shaped. These ball-like briquets are now carefully introduced either continuously or intermittently into a suitable furnace such as a shaft furnace or kiln and subjected to a suitable temperature to accomplish roasting or agglomeration. The special advantage of employing briquets of the shape indicated is due to the fact that each briquet touches its neigh bors with contact areas of small dimensions approaching the area of a point. In other words the contacts between the briquets may be said to be point contacts rather than surface contacts; Thus the spaces between the briquets are uniform cavities connected with each other, and serve as a system of tubes of geometrical uniformity. The combustion air and the gases, such as the gaseous prod ucts of combustion, hindered through all of these channels of comparatively large cross-section, and fully bathe, so to speak, all the briquets, thereby heating them all to the same temperature. The briquets are homogeneously distributed and the gas passages between them are homogeneous in structure so that the gases will readily pass through all uniform flow and will not find, as often happens with such furnaces in which fine or irregularly shaped material is being treated, preferred channels or fines through which the bulk of the gases escapes, thus heating the material in the neighborhood of such Specification of Letters Patent.

Application filed January 26, 1916.

glomeration,

can therefore pass unof the passages in Patented. Apr. 117, 1917. Serial No. 74,518.

fiues to a temperature higher than necessary and failing to heat the other material to a sufficiently high temperature.

The briquets of the present invention, moreover, are of small diametir, say the size of a hens egg; the temperature difference between the superficial portions and the interior portions of the brique'l is therefore negligibly low so that the action is not the same as with large pieces in which case rapid heating causes the outer portions to melt while the inner cores have a temperature lower than that required to sinter the material. For this reason and on account of the facility with which the combustion gases are allowed to pass in contact with all of the briquets, the treatment, in accordance with lfny process, requires both less time and less uel.

Agglomeration, by which I include sintering and roasting, of fine ores and the like is particularly difiicult as the sintering point and the melting point are relatively close together for which reason it sometimes happens with processes used heretofore that the sintering temperature is not reached and a sintering of the material is not effected, at least not homogeneously effected, while on the other hand the melting temperature is exceeded and the material, or a part of it, is melted. In either case the purpose of agthat is the utilization of the fine ores, is not effected or is only partially effected.

Ifbriquets with large plane surfaces such as rectangular briquets, in contradistinction to the ball-like briquets of my invention, are used, as in the past, for the roasting process, large piles are produced and at the sam'e. time irregular hole-like spaces are created. The result is that the material is not uniformly heated and'in such a case the productwill not be uniform. I

The simplest and cheapest way in which my briquets may be formed is perhaps by means of egg briqueting presses such as are used in the coal briqueting industry and in some instances have been used. for the briqueting of ore with sulfite pitch as a binder; these briquets, however, are charged directly into blast furnaces and do not undergo a roasting operation. Briquets which are to be agglomerated, on the other hand. need not necessarily contain a hinder, the ores themselves being somewhat plastic, while solute uniformity; consequently the temperature isthe same" throughout the zone of combustion and the product obtained is exceptionally uniform.

Egg briquets can be used for any roasting apparatus that has been used in the past for fine ores in pulverized or lump form. The shaft furnace, however, offers special advantages in this instance as'it always has been utilized in the past for sintering fine ores that were not in lump form. The roasting operation can almost wholly be accomplished automatically by feeding-the briquets directly from the press into the top of the furnace by means of a conveyer belt while at the bottom a rotating disk can be installed with a device for discharging the briquets automatically. As the roasting operation goes on rapidly, the furnace contents are kept in continual movement which prevents the briquets from clinging to one another in the sintering or roasting zone. This beneficial result is greatly aided by the form or shape which I give to my briquets because of the fact that the contact-surfaces of the adjacent briquets are reduced to a minimum and that, therefore, the minimum fusion of the adjacent briquets to each other takesplace. The briquets will, therefore, when agitated, remain separated units and when sintering takes place without agitation a separation may be effected after the completion of the. processes with a minimum amount of difiiculty. It is obvious that in order to be' adapted for the treatment in a shaft furnace as described, the structure of the briquets'must be what I call of a permanent character, as distinguished from a briquet which has been merely shaped but is not strong enough to withstand handling.

When in ,my claims I speak of fine ores I mean, of course, to include flue dust "and other metal bearing substances which are in a finely divided state and which have the characteristic, hereinabove mentioned, of

having them sintering and melting point relatively close together.

I claim; 1. That. improvement in the art of agglomerating fine ores which consists in in- .to a temperature between the sintering and melting temperature of the ores and maintaming continual movement of the briquets While in the sintering or roasting zone.

In testimony whereof I have hereunto set myhand. 1

WILHELM SCHUMAOHER;