US1684006A - Treatment of ores - Google Patents

Description

Sept. l1', 1928.

Q BENT ET AL. TREATMENT oF CRES Filed oct. 4. 1920 im? ezz, z

, to pack when Patented Sept. 11, 1928.

UNITED STATES PATENT OFFICE.A

QUINCY' BENT, OF BETIEILEI-IEM, PENNSYLVANIA; EDWIN BARNHART, OIESPARROW'S POINT, MARYLAND;

AND FREDERICK W. WOOD, OF PHILADELPHIA, PENNSYL- VANIA, ASSIGNORS TO BETHLEHEM STEEL COMPANY, QF BETHLEHEM, PENNSYL- VANIA, A CORPORATION OF PENNSYLVANIA.

TREATMENT OF CRES.

Appicaton filed October 4, 1920. Serial No. 414,705.

Fig, 1 shows an elevation of apparatus suitable for employment in carrying out our invention; Fig. 2 is a partial longitudinal section thereof; and Figs. 3 and 4 are sections on lines III- III and IV-IV, respectively, of Fig. l.

Our invention relates to the. treatment of ores, particularly those forms of 'ores which, in their natural state, occur in a finely divid- 'cd condition, and, because of their liability wet, or blow out with the blast when dry, require treatment preparatory to sintering or other reduction in a fui.'- iiace. Wie have found that our invention is particularly useful with ores, such as ariv iron ore, which, because of its clay-like consistency when wet, prevents the passage of air or gas uniformly through the liiiiass, and thereby renders sintering or other treatment dificult. By the employment o-f our invention, however, the ore is brought into such condition that it may be readily sintered or otherwise treated In the drawings we have of a character which may be suitably. employed in carrying out our invention, and which consists in a rotary cylinder, preferably set at a. slight angle to the horizontal, so that,as the material is picked up and let fall by lifting blades 2 with each revolution of the cylinder, lt will be advanced toward the discharge end thereof. At. the intake end 3 is a chuteA, through which the mashown apparatus terial is admitted into the cylinder, whilel the discharge end 5 is equipped with a screen 6, through which the smaller sizes of material will escape and thus be separated ,from the larger sizes. The discharge end 5 may be open, as shown, to permit the discharge of the larger agglomerations of the material. Beneath the screen 6 and open end 5 of the cylinder are arranged the pockets 7 and 8 for the'reception, respectively, of the smaller and larger agglomerations of material, and from which the material is carried away by the conveyerbelts 9 and 10. The cylinder y.is heated at its discharge end by a gas buiner 11, or by any other suitable means. y

As a typical example of carrying out our invention, we will describe its application to the treatment of M ayar ore from Cuba in Mayf the apparatus. just described. `It is well known that the free moisture content of `Mayar ore mentioned is muchy higher than required to produce the same physical consistency. with other ores different in character.

The ore, in ay form which'normallv contains from 25 to 30per cent of free moisture. is introduced into the agglomerating zone of the cylinder through the chute 4, and at the same time a charge of coke in pulverized form is fed in with the ore, the coke charge heilig preferably about 5 per cent of theaniount of t-lie ore. As the interior o the cylinder atl its intake eiid. which is remote from the burner l1. is cold, the ore will adhere to it between the lifting blades l, whiclrserve to pick up the material and assist in agglomerating it. As the cylinder revolves, the material drops oft" in large chunks, which are beaten and lpicked up again and again by the blades 1 as the cylinder revolves, and which at the same time pick up additional globules of the material',

which forms into balls and pellets. The balling action also assists in bringing a portion ofthe moisture of t-he material to the surface so that it is readily carried off. by the heated air when the drying zone'is reached. yBecause of the downward inclination of the cylinder toward its discharge end, the material advanced toward that end with each revolution of the cylinder. The balling action is assisted in the drying zone B by the blades 2` which .serve to roll the material and shapeit in the forni of balls or spheres.. The material is preferably subjected as it approaches the discharge end to a' comparatively low heat from thc burner ll, andthe moisture released thereby is carried oit with the air by means of a fan l2, which is arranged at the intake ond of the cylinder. vVe have found that, where the material as it is introduced into the cylinder contains a free mois- -ture content of from 25 to30 per cent, that The temperature at the discharge end of the kiln should be kept to a moderate degree, so that only a portion of the total moisture may be removed. The amount of residual moisture to be left in the balls or pellets will somewhat depend on the nature and physical characteristics of the material under treatment. If insufficient moisture be removed, the balls tend to adhere one to another and form sticky agglomerates of substantial size. If, on the other hand, a higher degree of heat be applied, so as to almost reduce the material to dryness, the cohesi've and plastic character of the balls is destroyed in such a manner that they may disintegrate to a more or less pulverulentcondition.

The agglomerating and drying processus continued until the larger globules roll out at 'the discharge end 5 of the cylinder and the liner globules sift through the screen G at such end, thus effecting an automatic sorting of the material. I

An important feature of our invention is the fact that, the partial removal of moisture at low temperatures does not cause any substantial slirin-kage of the masses, so that the material composingr the balls leaves the rotating cylinder in a porous condition, emiently suitable for subsequent furnace treatment.

The material, when agglomerated into 'the form of balls or pellets by the process pist described, is sufficiently hard to stand ordinary handling.4 Even when the balls are of considerable size the material offers little resistance to the uniform passage of air or gas therethrough, and is therefore in condition for.treatment by any of the wellknownsintering or roasting processes. 'Ifhe crushed fuel, which is added at the beginning of the balling or agglomerating process, is gathered up and embedded in the balls during their formation, and thereby insures a uniform'and intimate mixture between the ore and fuel, which is highly desirable in the subsequent reducing operations. The use of an additional agent, as for example carbonaceous material, though a convenience to certain further operations, is not, however, essential to the process.

The terms land expressions which we have employed are used as terms of descriptionl and not of limitation, and we have no intention, in the use of such terms and expressions, of excluding any equivalents of the features described, but recognize that various `modifications are possible within the scope of the invention claimed.

What we cla-im is:

1. A process for rendering wet ores of plastic characterv suitablel for al subsequent furnacing operation which consists in, feeding the ore into the cool end of an internally and longitudinally ribbed rotary kiln, whereby the plastic ore mass may be divided llongitudinally of the kiln,

into a plurality of integral masses disposed longitudinally of the kiln, said kiln having its axis inclined to the horizontal and being rotated soas to carry the masses to a point at which they may become gravimetrically detached and fall downwardly and forwardly iii the kiln, causing said detached masses to` be individually carried upward and dropped forwardly in the kiln by the continued rotation of the latter, whereby the ore may be formed into masses of the size desired and submitting said masses during their downward tumbling passage through the kiln to a` moderate degree of heat so as to effect a partial re'moval of their contained moisture. y

2. A process for rendering wet ores of plastic character suitable for a subsequent furnacing operation which consists in, feeding the ore together with carbonaceous material into the cool end of an internally and longitudinally ribbed rotary kiln, whereby the plastic ore maybe divided into a plurality of integral masses disposed longitudinally of the kiln, the kiln having its axis inclined-to the horizontal and being rotated so as to carry the masses to a point at which they may become gravimetrically detached and fall downwardly and forwardly in the kiln, causing said detached masses to be individually carried upwardly and dropped forwardly in the kiln by the continued rotation of the latter, whereby the ore may be 4certain components of the ore, feeding the mixture into the cool end of an internally and longitudinally ribbed rotary kiln, whereby the plastic ore may be divided into a plurality of integral masses disposed the kiln having its axis inclined to the horizontal and being rotated so as to carry the masses lto a point at which they may become gravimetrically detached and fall` wardly in the kiln, causing said detached masses to be individually carried upwardly and dropped forwardly in the kiln by the continued rotation of the latter, whereby the ore may be formed into mases of the size desired, and submitting said masses during their downward tumbling passage through the kiln to a moderate` degree of heat so as to effect the partial removal of their contained moisture.

4. A process for converting a plastic addownwardly and forhesive conglomerate into a plurality of nonaforesaid.

adhesive units suitable for subsequentl furnace treatment, `which consists in, feeding the material into the charging end of an inclined rotary kiln internally and longitudinally ribbed so as tosub-divide the conglomerate into a plurality of integral masses, raising, inverting and dropping said masses in repeating sequence by the continued rota.- tion of the kiln, the inclination ofthe latter being such as to causel the masses to move gradually forward into a zone of moderate 4heat disposed towards its discharge end, said heat being of a degree sullicient to effect a partial removal of moisture from the separateintegral masses,"balled by their tumbling movement into the zonexof heatv 5. A process for forming an impervious conglomerate into a pluralit of substantially porous units suitable for subsequent furnace treatment, which consists in, feeding the conglomerate and carbonaceous materiah into the charging end of an inclined rotary kiln internally and longitudinally ribbed so as to sub-divide the conglomerate into a plurality of integral masses, raising, inverting and dropping said masses in repeating sequence by the continued rotation of the kiln, the inclination of the latter being such as. tofcause the masses to move gradually into a zone of moderate heat disposed towards its discharge end, and limiting said temperature so that the -separate integral masses ballad by their tumbling movement into the zone 'of heat, may be rendered porous by the partial evaporation of their contained moisture.

6. A processl for renderin Wet ores of lastic character suitable or subsequent urnace treatment, whlch conslstsln, forming integral slabs of the ore on the internal periphery'of an inclined rotating kiln, havmg a zone of moderate' heat disposed at its discharge end, causing said slabs to be repeatedly tumbled and carried forwardly into the zone of heat by the rotation of'the kiln, whereby the slabs ma be formed into substantially ball-like mem ers, limiting the temperature of said zone so asto effect only a partial evaporation of the 'moist-ure contained in the members, and finally gradingyt-he members by a process of screening.

a partial evaporation of the moisture contained in the members, and finally grading the members by a process: of screening.

' QUINCY BENT. l

EDWIN BARNHART. FREDERICK W. WOOD.

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