US2070531A - Apparatus for roasting ore - Google Patents

Description

INVENTOR C. A. Gad/a C. BY

Filed Aug. 13, 1934 C. A. GALLAGHER ET AL APPARATUS FOR ROASTING ORE Feb. 9, 1937.

her M. Alfie/1 ATTORNEY Patented Feb. 9, 1937- PATENT OFFlCE- 2,010,53 APPARATUS FOR ROASTING one Charles A. Gallagher and Carl M. Allen, 0511- fornia, Pasassignors to General Chemical Com- D y, New York, N. York Y., a corporation of New t Application August 13, 1934, Serial No. 739,547 3 Claims. (01. 263-21) This invention is directed to apparatus for roasting metallic sulfides, and more particularly for roasting finely divided sulfide ores to desulfurize the same and to produce sulfur dioxide for use in the manufacture of sulfuric acid, or for any other purpose desired.

To a large extent, present practice in sulfide fines roasting includes use of mechanically operated multiple hearth constructions, such, for example, as the well known MacDougal, Herreshoff, and Wedge burners, and while such burners provide effective roasting, the complicated construction and operation thereof involve considerable initial and maintenance expense. To some .degree, roasting of sulfide fines while in gaseous suspension has more or less recently displaced the bed roasting operations carried out in the above mentioned hearth burners.

Suspension roasting is best applicable when the fines are in a relatively finely divided state,

and this method presents the notable advantage A over the mechanical multiple hearth operation of considerably lowering the cost of production, by reason of the elimination of the relatively complicated and moving parts, expensive rabbling and other apparatus inherent in the construction and operation of such mechanical burners. In the practice of suspension roasting, however. and particularly as applied to roasting metallic sulfide fines, difiiculties are encountered which must be overcome before the theoretical advantages of this type of operation are practically available. v

The invention is directed generally to improvements in burners for suspension roasting of sulfide fines, and. moreespecially to feedmechanisms for injecting the fines into burner combustion chambers and for forming therein a dispersion of the fines in gaseous suspension. It is one of the objects of the invention to provide flexible and easily adjustable injector mechanisms so constructed as to permit feeding of fines in the burner combustion chamber in such a way as to substantially prevent contact of fines with the heated inner walls of the combustion I chamber to thus avoid accumulation on the walls of accretions or scar. formation, a well known difilcult'y encountered in suspension roasting. Another object of the invention is to provide feed mechanisms affording 1mproved dispersion of fines over the cross-sectional area of the combustion chamber. The invention additionally aims to provide feed injectors including mechanisms by means of which the quantity of lines drying hearth.

' ble arms framework l8, discharges from which fines are intermittently dropped onto 21 rotating with shaft 23.. i

l3, by suitable brackets downwardly sloping passages or conduits fed into the furnace may be accurately controlled and fluctuations of ore feed avoided.

The invention accordingly comprises the features of construction, combinations of elements,

and arrangement of parts, which will be exemplified in the construction hereinafter set forth. The nature of the invention and the objects and advantages thereof may be more fully understood from a consideration of the following description taken in connection with the accompanying drawing, in which Fig. l is a vertical section of a sulfide ore burner for use in connection with which the improved injectors of the invention are particularly designed;

Fig. 2 is an enlarged view, partly in section and partly in elevation, showing one preferred form of the'improved injector;

' Fig. 3 is anelevation taken substantially on the line 3-3 of Fig. 2, and

Fig. 4 is a plan taken on the line L-l of Fig. 2.

Referring particularly to Fig; 1 of the drawing, numeral l0 designates generally a shaft burner comprising a shell I I, constructed of suitable refractory material such as firebrick, defining a roasting chamber l2 of cylindrical crosssection. Surrounding shell H, is a steel casing l3 acting as a protective reinforcement for the furnace. The upper end of the combustion chamber is closed off by a crown IS, the top side of which forms a drying and preheating hearth ll. The cylindrical shellll and casing l3 project upwardly beyond the crown I5, and carrya steel framework l8 which in turn supports ore feeding and rabble mechanism for the The 1 surface of hearth I1 is' slightly coneshaped and slopes downwardly toward the shell of the burner. Lying above the hearth are rabl9- having downwardly projecting plows 20 pitched to work sulfides gradually toward the circumference of the "drying hearth. Arms I9 are rotated by a motor 22 through shaft 23 supported in bearings so as to maintain the lower ends of the plows 20 properly spaced with respect to the'surface of the drying hearth ll. An ore bin 24, mounted on ore onto a platform 25 approximately the center of hearth I1 by a sweep Attached'to steel shell not shown, are hoppers 30 covered by slopin'g screens 3|. Cut in shell l l near the uppererid are v threaded through the upper part of sleeve'38 and provides means by which the vertical position of feed regulator 36 may be adjusted. Welded or otherwise attached to the lower end of sleeve 38 is a plate 48 having an opening 42 in alignment with the axis of sleeve 38 and also having an ex-, tension 44 shown in plan in Fig. 4. Extension or bracket 44 is drilledto accommodate bolt 46 headed on the lower end and threaded on the upper end to receive winged nut 48. Adapted to rotate about bolt 46 on loosening of nut 48 is a circular plate 50 having openings H, 52, 53 and 54 of progressively increasing size, orifice 54 being 'of about the same diameter as opening 42 inplate 40. These openings are spaced from the center of plate 58 so that each opening on rotation of the plate may become axially aligned with opening 42 in plate 48. It will be seen that by loosening the clamp and rotating plate 50, the effective size of the opening in the bottom of feed regulator 36' may be changed to regulate the capacity of the burner.

The adjustable injectors of -the invention, indicated generally by reference numeral 60, are each supported by a bracket 6| attached to the steel shell I3. Referring particularly to Fig. 2, each injector. comprises a Y-fitting 63 the bottom of which is threaded to accommodate an externally threaded bushing 64 which slidably receives a gas jet 66. One branch of the Y-fitting is threaded as at 68 to provide for attachment to the fitting of the lower discharge end of the funnel I8 adapted to be positioned directly beneath the feed regulator 36. A winged bolt 12 passing through bushing 64 provides means for adjusting the end of jet 66 with reference to the axis of funnel 18. The other branch of fitting 63 is threaded to receive one end of a metallic nozzle I3 which projects through an opening 14 in the furnace wall I I and provides an ore inlet conduit 15 through which fines are injected into the combustion chamber I2. A dispersing cone I6, positioned beneath orifice 42, is supported as indicated in the drawing byv three short legs engaging the inner surface of funnel I0.

Welded tothe upper end of bolt 11 (Figs. 2 and 3) is a trough-like plate 18 to which nozzle 13 may be clamped by means of a U-bolt 88, the ends of which pass through'plate I8. Referring particularly to Fig. 3, the lower threaded end of bolt 11 is adapted to pass through an elongated slot 8I in the horizontal leg 82 of an angle bracket 83. Slot 8| permits sidewise adjustment of nozzle 13. The vertical position of bolt 'I'I with reference to bracket 83 may be adjusted by set nut 84 and winged nut 85. The lower end of vertical leg 81 of bracket 83 is drilled to accommodate a bolt 88 which may he slid back and forth in a horizontal slot 98 in bracket 6|. Bracket 83 is held tightly in any desired position with reference to bracket 6| by means of winged nut 92 threaded onto the end of bolt 88. From the foregoing, it will be seen the weight of fitting 63 and the as:

. 2,070,531 through which on: is passed from the drying sociated parts is supported by bracket 6| fixed to the furnace casing I3.

A bustle 95 having an inlet 96 provides for gas supply to injector jet 66, the bustle 95 communicating with jet 66 through pipe 91 including a control valve 98, a pressure gauge 99 and a double universal joint indicated at I88.

The burner may be provided with any suitable number of injectors. In the illustrated embodiments of the invention, the two injectors shown in Fig. 1 are diametrically opposed. In some instances it is desirable to employ say three or more injectors equally spaced about the circumference of the burner. It will be understood where three or more injectors are included in the furnace con-.

struc'tion, a hopper 30 and a feed mechanism 36 are provided for feeding ore thereto.

oxidizing gas to support the roasting operation is introduced into the chamber I2 through 'circumferentially spaced ports -I 82, positioned adjacent the ore injectors, and connected through short pipe sections, not-shown, with a bustle I03,

communicating with an air inlet connection I04,

open to the atmosphere and having a control valve I05. g

The-bottom of the combustion chamber I2 is formed by a hopper-shaped brick-faced hearth I81 terminating in an outlet I88 through whicn cinder may be continuously discharged into -a conveyor. A gas main I I0, opening into the combustionchamber, just beneath the crown I5, is connected to the suction side of a fan which effects withdrawal of gaseous combustion products from the burner.

The apparatus of the invention may be employed in connection with the roasting of finely divided metal sulfidessuch as iron pyrites, pyrrhotite, zinc sulfide or ar senopyrite. The adaptability and operating advantages of the improved apparatus may be more clearly understood from the following in which the apparatus is described in connection with the roasting of iron pyrites.

A supply of sulfide fines is maintained in'the bin 24 by suitable conveyor or elevator mechanism, not shown. Before roasting is begun, combustion chamber I2 is preheated to temperatures above the ignition point of the particular.

' heat is obtained in' the combustion chamber, the

motor 22 is started, and rabble arms I9 and sweep 2! may be rotated at a rate of, say, one revolution in two minutes. Fines run continuously out of the bin 24 onto platform 25, and on each revolution of shaft 23 a regulated quantity of fines is swept off the platform to approximately the center of hearth I'I.

During rotation of the rabble arms I9, the concentrates are gradually worked across the heated surface of hearth I! and into'passage 34. The dry or partly dry ore runs onto sloping screens 3|, which remove lumps, and then into hopper 30. The finely divided particles drop through pipe 35 into cylindrical sleeve 38 of feed.

variable size, and in accordance with the fineness of the ore, the size of the combustion chamber, the desired capacity of the burner, and other variable operating conditions, the plate 50 may be positioned by adjustment of nut 48, so as to place an orifice of the desired size beneath the opening 42 in the bottom ofsleeve 38. As will be hereinafter observed, the vertical position of funnel l may vary, and to provide for this, the position of feed regulator 35, with respect to pipe 35, may be regulated by adjustment of winged bolt 39 to insure discharge of fines into the funnel. The plate thus provides a fixed opening for accurate feed control preventing fluctuation in ore supply which may readily take place with other types of adjustable valves.

The fines accordingly flow steadily from regulator 36 into funnel l0, which conveys the ore stream directly and preferably without any decrease in velocity of the particles into Y-fittin'g 63 in which the fines are swept up by the air introduced through jet 66 and carried through pipe 13 into the combustion chamber. Conical surface 16 in funnel serves to divide the stream of ore falling from the orifice in plate 50. The inner end of jet 66 is preferably located inwardly of the axis of funnel 10 so that the fiow of air from the jet induces a slight minus pressure in the vertical leg of Y 63 and results in an actual suction drawing in air and ore through funnel Ill. Orifice plate 50 regulates the flow of ore to the feed nozzle and does not permit ore to build up in the funnel. In operation, ore and air are sucked in the throat of funnel 1!), become more or less uniformly dispersed by cone surface 76, pass through Y 63 and are given an additional impulse on passing the end of jet 66, resulting in a very homogeneous dispersion of the finely divided ore in air at the outlet of the feed nozzle.

Streaky or fluctuating feed is avoided, roasting of the ore is more complete and gas strength is more easily kept uniform by operating in this manner.

To effectively carry out the roasting process, the manner of introducing the fines into the combustion chamber is of major importance. The

fines should be fed into the chamber so that each particle is suspended in the roasting atmosphere for a maximum period of time, and also so that contact of the fines with the walls of the combustion chamber is substantially avoided. To this end, by means of the feed mechanism of the present invention, the horizontal and vertical angles of the axes of nozzles 13, theamount of fines fed into the injectors from pipes 35, and the air pressure in jets 66, adjusted by valves 98, 'may be conveniently regulated with respect to the particular size of the roasting chamber so that the ore particles from each injector rise through the combustion chamber, away from the walls thereof, to an elevation justbelow the underside of crown l5. The horizontal and vertical angular position of nozzles 13 and the rate I ber may be obtained, and contact between any substantial quantities of ore particles and the hot Walls of the roasting chamber is prevented, thus avoiding accumulation of scar on the walls.

In Fig. 1, the dotted line H5 indicates the approximate path of travel of an ore particle of average size introduced through the injector on the left side of the burner.

From the previous description, it will be understood nozzle l3 and the Y-fitting B3 are rigidly connected to the upper end of bolt Tl. By loosening the winged nut 92, the vertical angle between the axis of the nozzle and the horizontal may be adjusted, thus permitting swinging of the nozzle through an are lying in a vertical plane and extending longitudinally of and disposed at a right angle with the burner wall. loosening nut 92, by means of the horizontal slot 90, movement of the injector back and forth relative to the wall of the burner may be effected. Nozzle l3 and the Y-fitting may be moved bodily up or downby moving set nut 85 and winged nut 85 to permit vertical movement of bolt l1 through the, horizontal section 82 of bracket 83. Also by means of slot ill the nozzle may be adjusted sidewise.

Under some operating conditions, there may be instances Where it .is' desired to introduce the fines into the roasting chamber in a direction other than radially. It will also be understood that by loosening set nut 85 and winged nut 85, the injector may be moved through a horizontal angle about bolt Tl as an axis. By means of this adjustment fines may be injected into the combustion chamber radially or in a direction oil a given radius. To permit the desired movement of nozzle 13, opening 14 in the furnace Wall II is made large enough so that angle A (Fig. 2) may vary for example between 15 and 45 degrees, and so that nozzle 13 may be swung horizontally through an arc of say 45 degrees. a

The major portion of the total quantity of air, or other oxidizing gas, necessary to support roasting is drawn into the combustion chamber at the bottom thereof from bustle I03 through ports I02. Where air is employed for injecting the fines through the nozzles, not more than about 10% of the total air required for oxidation would ordinarily be introduced through air jets 66, although larger amounts may be used if desired. The position of the ends of jets 56 with respect to the axes of funnels I! may be adjusted by manipulation of tail nut 12, and if necessary bushings 64 and jets 66 may be removed from fittings 63 to permit cleaning; of the latter or of the nozzles 13.

' By suitable adjustment of the injectors, a relativcly uniform distribution of partially roasted particles is formed over the major portion of the upper end of the combustion zone. The particles thereafter drop to the bottom of the combustion chamber. The blower in gas line H0 is operated so as to draw sufficient air into the combustion chamber to supply enough oxygen to effect substantially complete oxidation of the fines, and also so that the velocity of the rising stream of air through the combustion chamber is not sufiicient to interfere with the free gravity fall of the fines. Becauseof the adjustable features of the injectors, a satisfactory dispersion of ore particles over a major portion of the top of the combustion chamberis obtained, and ore particles'during'the upward movement are not thrown against the walls of the roasting chamber, thus avoiding contact of fines with the hot walls of the combustion chamber when the fines are in a state conducive to scarring. As the downward flow of the fines is in substantially Also, by

'straight lines or at a high angle, subsequent coni tact of fines with the walls of the combustion chamber is avoided, thus further preventing conditions under which scarring might take place, the iron oxide cinder-falling on hoppershaped hearth 101 runs through opening I08 into a suitable conveyor.

We claim:

1. The combination with a reaction chamber having an opening in a wall thereof, of means for feeding into said reaction chamber finely divided material in dispersed condition, said means comprising a movable injector having a material inlet passage open to the atmosphere and a nozzle disposed in angular relation with respect to the inlet passage and extending through said opening, means in said injector inlet passage for dispersing in atmospheric air material fed into said injector inlet passage, a feed regulator for feeding material into the injector and for controlling such feed so as to prevent stopping up of said inlet passage to flow of atmospheric air, means for changing the position of the feed regulator to accommodate changes of position of the injector material inlet passage, means including an air jet in said nozzle for inducing in the inlet passage a minus pressure to form in and draw through the inlet passage preliminary dispersion of material in air and for introducing into the preliminary dispersion an additional stream of air under positive pressure to cause the material to flow through the nozzle and form at the outlet thereof a relati ely homogeneous dispersion of material in air, means for swinging the nozzle.

through an are lying in a plane extendinglongitudinally of and disposed at a right angle with the wall, means for swinging the nozzle through an are lying in a plane at a right angle with said first mentioned plane and means for holding the nozzle in a fixed position in each of said arcs.

2. The combination with a reaction chamber having an "opening in a wall thereof, of means for feeding into said reaction chamber finely divided material in dispersed condition, said means comprising a movable injector having a material inlet passage open to the atmosphere and a nozzle disposed in angular relation with respect to the inlet passage and extending through said opening, a cone in said injector inlet passage arranged to disperse in atmospheric air material fed into said injector inlet passage, a feed regulator for feeding material onto said cone and for controlling such feed so as to prevent stopping up of said inlet passage to flow of atmospheric air, means for changing the position of the feed regulator to accommodate changes of position of the injector material inlet passage, means including an air jet in said nozzle for inducing in the inlet passage a minus pressure to form in and draw through the inlet passage preliminary dispersion of material in air and for introducing into the preliminary dispersion an additional stream of air under positive pressure to cause the material to flow through the nozzle and form at the outlet thereof a relatively homogeneous dispersion of material in air, means for universally changing the position of the injector nozzle in the wall opening, and means for holding the nozzle in a fixed position.

3. The combination with a reaction chamber having an opening in a wall thereof, of means for feeding into said reaction chamber finely divided material in dispersed condition, said means comprising a movable injector having a material inlet passage open to the atmosphere and a nozzle disposed in angular relation with respect to the inlet passage and extending through said opening, a cone in said injector inlet passage'arranged to disperse in atmospheric air material fed into said injector inlet passage, a feed regulator for feeding material onto said cone and for controlling such feed so as to prevent stopping up of said inlet passage to flow of atmospheric air, means for changing the position of the feed regulator to accommodate changes of position of the injector material inlet passage, an air jet in the injector in alignment with said nozzle and having the end thereof positioned inwardly of the axis of the. material inlet passage and arranged to induce in the inlet passage a minus pressure to form in and draw through the inlet passage preliminary dispersion of material in air and to introduce into the preliminary dispersion an additional stream of air under positive pressure to cause the material to flow through the nozzle and form at the outlet thereof a relatively homogeneous dispersion of material in air, means for universally changing the position of the injector nozzle in the wall opening, means for holding the nozzle in a fixed position, means for moving the injector bodily toward and away from said opening, and means for moving the injector longitudinally with respect to said wall.

CHARLES A. GALLAGHER. CARL M. ALLEN.

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