US3900293A - Controlling admixture of aqueous liquid to ball rolling of powdery iron ore - Google Patents

Controlling admixture of aqueous liquid to ball rolling of powdery iron ore Download PDF

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Publication number
US3900293A
US3900293A US319467A US31946772A US3900293A US 3900293 A US3900293 A US 3900293A US 319467 A US319467 A US 319467A US 31946772 A US31946772 A US 31946772A US 3900293 A US3900293 A US 3900293A
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United States
Prior art keywords
drum
rate
supply
liquid
balls
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Expired - Lifetime
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US319467A
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English (en)
Inventor
Borje Gustav Sjoberg
Rolf Ragnar Odman
Arne Belstad
Nils Clov Allan Lofgren
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Luossavaara Kiirunavaara AB LKAB
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Luossavaara Kiirunavaara AB LKAB
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24—Binding; Briquetting ; Granulating
    • C22B1/2406—Binding; Briquetting ; Granulating pelletizing

Definitions

  • ABSTRACT A method of and a device for controlling admission of material consistency adjusting liquid to a powdery moist material to be shaped into balls by treatment in a ball rolling machine comprising an open ended ball rolling drum having an entrance end for the supply of said material and an exit end.
  • a sieve is provided for separating balls of a prescribed size and the rest of material leaving the drum at the exit end thereof, a conveyor for conveying material passing through the sieve as return material back to the entrance end of the drum, means for supply of water to material charged into the drum at the entrance end thereof, means for controlling said supply of said material consistency adjusting liquid, and means for measuring the rate at which said return material is conveyed to the entrance end of the drum.
  • a rate sensing governor senses variations in said rate of return material and provides an indication whether amplitude of oscillations in said rate is above or below a predetermined amplitude limit, the governor being arranged to in dependence of indication whether amplitudes are above or below said predetermined limit actuate a servomotor to adjust to liquid supply control means so as to increase or decrease, respectively, the supply of liquid.
  • ball sintering machines irrespective of type, are to be fed with an even flow of raw balls, wherefore the rather high variations in feeding rate which in the present practice arise by so called pulsing" in the delivery of raw balls from a ball rolling machine is very inconvenient.
  • An ideal when producing raw balls would be a production of raw balls in such a manner that the quantity of raw balls produced per time unit and fed to the sintering machine remains substantially constant at a desired level, an ideal situation which can at present not be reached to a desired degree for the following reasons:
  • the pulsing in the delivery of raw balls which are ready for being transported to the sintering machine is dependent of a large number of facts. Important such facts are, for instance, variations in the grain size distribution and moisture content of the slick which is fed to the ball rolling machine, the slope and rotational speed of the ball rolling drum, etc. Further, the so called rolling circuit is individual to each ball rolling machine due to possibly different drum length of the machine, different rotational speed, different circulation time in the rolling circuit, wear of sieve bars, and the like, to the effect that characteristics of one rolling circuit can not be immediately adapted to another one.
  • the rolling circuit of a ball rolling machine broadly appears from the following:
  • a slick is fed to the drum, said slick having a content of granulate or powdery material and liquid which by experience is considered as suitable for the rolling, and material which has already passed the rotating drum but which has as yet not got the size of raw balls ready to be passed on to the sintering oven.
  • a sieve comprising parallel rods or bars is arranged at the other, lower, end of the drum, this sieve letting such material, which after having passed the drum has as yet not obtained a prescribed size, to pass through the sieve, while balls which have obtained the prescribed size do not pass through the sieve, but are instead conveyed to a machine for sintering the balls.
  • the material passing the sieve and representing balls which have as yet not reached a prescribed size, fragments of crushed and other material passing the sieve is returned by means of a conveyor to the upper end of the drum and fed into the drum to again pass through the drum together with fresh slick.
  • the highest quality raw balls are obtained during an intermediary state in which a small pulsing in the feed rate of return goods is present and the amplitude of the variations is still small as compared with the average feed rate of return goods.
  • Obtaining such a state of running the rolling machine is however in practice considered as strokes of luck, this with respect to the fact that a systematic adaption to a pulsing amplitude at which the ball quality is at an optimum can not be made by guidance of information obtained simply by observing the rolling process.
  • the present invention which is based on the experience explained above, that the raw ball quality has an initimate, although secondary, connection with oscillation or pulsing of the rate at which material leaving the rolling drum passes the sieve and is returned to the inlet of the drum relates to a method of controlling addition of liquid in a ball rolling device, said method having characteristics as appearing from the appended claims.
  • the invention is in respect of a device to execute the method, said device having characteristics as appearing from appended claims in respect of a device.
  • the invention is based on the rather peculiar and not yet explained fact that the quantity of return material varies not only with the ball quality or liquid content of the slick (which is, as such, obvious), but that as well the quantity of return material is exposed to oscillation or pulsing having an amplitude which is intimately associated with the ball quality and which is small or none when the balls contain too much liquid and large when the balls contain too little liquid.
  • the period of the oscillations is, as far as have been hitherto stated, substantially individual of a particular ball rolling device and independent of the amplitude of the variations in quantity of the returned material.
  • the quantity of return material continuously varies with the frequency one-seventh period per minute irrespective of the amplitude, while for a second particular rolling machine the frequency was oneeighth period per minute.
  • the average rate of recirculated return material has, in these measurements, been between 150 and 200 percent of the rate of slick fed to the rolling machine.
  • the amplitudes of the variations of return goods during the oscillations superimposed on the average feed rate was about percent of the rate at which the ore slick is fed into the rollingdrum when the produced balls have shown the desired quality (that is, the added quantity liquid has been the correct one for the actually treated slick material), while the amplitudes during periods with too large ad dition of water (leading to wet plastic balls) have been less than fi percent about the average level.
  • the amplitudes in the rate of transport of the return material can, according to the invention, be utilized for a fully automatic control of the ball rolling, aiming at a high and invariable quality of the raw balls delivered by the rolling machine, such quality of the balls being, as described above, being a condition for obtaining a high-qualitative ball sinter product.
  • FIG. 1 is a schematic plan of the rolling circuit of a ball rolling machine
  • FIG. 2 is a schematic control circuit diagram of a circuit for controlling addition of liquid to the slick mate rial to be treated in the rotatable drum of the ball rolling machine, and
  • FIG. 3 is a diagram showing. by way of example, the variations in the rate of return material as a function of time.
  • FIG. I it shows, as a skeleton sketch, a ball rolling machine having a rotational rolling drum 1 to one of the ends of which, the inlet end 2, a slick, such as iron ore slick, containing a quantity of liquid calculated to be substantially adapted for the proper ball rolling, being, as represented by arrow 3, supplied by means of a conveyor of arbitrary construction suitable for the purpose as well known to the art.
  • the rotational axis of the drum is sloping downwardly towards the exit end 4 of the drum, at which ready made rolled balls, balls not yet ready for sintering, and remaining slick material leaves the drum to pass a sieve 5, usually consisting of bars extending in the axial direction of the drum.
  • Material passing through the sieve 5 said material thus consisting of balls which have as yet not reached a prescribed size, fragments of crushed balls and remaining loose slick material, is conveyed by a conveyor 8 as indicated by arrow 9 to a return material conveyor 10, by which the material passing through the sieve is returned to the entrance of the drum for being treated anew in the drum.
  • the ball rolling apparatus is, according to the invention, provided with a control equipment, by means of which the amplitude of oscillations in the quantity per time unit of return material returned to the drum is being kept at or adjacent a level, with which the quality of the finished balls, that is, the balls delivered by the sieve 5 to the conveyor 6, have adopted a strength desired and required for the following treatment thereof in a sintering machine.
  • Said control equipment comprises a conveyor weighing machine 1 1, a governor 12 controlled by weight information received from the conveyor weighing machine, said governor 12 in the embodiment described below having two measuring limits for an input signal received from the weighing machine 11, said measuring limits representing values of rate of return material, that is, quantity per time unit, on both sides of the average value of the rate of return material, said two values representing amplitudes in the vicinity of which the largest and smallest quantity of return material during the oscillations in said quantity are to be to obtain balls with the desired properties during rolling.
  • governor 12 constitutes a feeler which states whether the oscillations are between two predetermined limits which are located such a distance from on both sides of the average rate of return material that the total amplitude between the limits corresponds to the optimal ball quality.
  • the governor 12 has three output terminals, namely one, 15, by which a signal is delivered to a time relay 16 when the regulator senses a rate of return material above the higher limit.
  • an output terminal 17 delivering a signal to a time relay 18 when the rate of return material is between the two predetermined limits, and an output terminal 19 for a signal to a time relay 20 when the rate of return material is lower than the lowest predetermined limit.
  • the stepwise change of rate of added liquid is provided for by means of a servomotor 21, controlled by excitation pulses from one of the relays 16, 18, 20, the servomotor actuating a valve 22 to control the quantity of water added to adjust the liquid content of the slick by means ofa conduit 23, by which the water is fed to the slick in a manner as such well known to the art for controlling the moisture content of the material treated in the rolling drum.
  • the governor is, as intimated by contacts 13 and 14, made so as to actuate relay 16 when the amplitude of the oscillations in the rate of return material increases above the highest limit and to actuate relay 20 when the amplitude decreases below the lowest limit, the time relay 16 or 20 after said predetermined delay and if then the rate of return material has not returned to within the limits generating a signal for the stepwise increase of addition of water to the servomotor 21.
  • FIG. 3 shows a typical control scheme when using the devices illustrated by FIGS. 1 and 2.
  • Curve represents quantity of return material per time unit as mea sured by the weighing machine 11. In practice, the period of the oscillation may be in the order of 7 to 8 minutes.
  • Lines 31 and 32 represent the upper and the lower limit, respectively, of the amplitude of the oscillations to obtain a desired quality of the balls.
  • the position of governor 12 in dependence of the input signal from the weighing machine 11 is shown, the marking of the surfaces during sampling and valve action being indicated in the figure.
  • the rate of water added under the control of valve 22 of FIGS. 1 and 2 is illustrated by the lowermost curve 34 (drawn in an enlarged ordinate scale as compared with the ordinate scale of curve 30).
  • the period of time [T1] represents a sampling time at the expiry of which relay 18 emits a decreasepulse to the servomotor 21, the servomotor then clos- -A signal is emitted by the governor 12 to the time relay 16, the time relay however, in the same way as relays l6 and 20, being such that it reacts only when the signal has reached a predetermined lowest duration. Consequently, the valve is not actuated.
  • a control of the water content of the slick may, as a principle, as well be provided for by other means than the ones described] by reference to FIGS. 1 and 2, as, for instance, by aid of electronic or other integration apparatus which during predetermined sampling times, the length of which are, obviously, to be selected with due respect to the period of the oscillations and larger than this period, measured time during which the oscillations are above or below a predetermined limit, or establish that they do not do so, and in dependence of the result provides for an increase of rate of added water, a decrease of said rate. or maintains the rate uneffected.
  • the device in dependence of the way within the scope of the invention in which it is stated that the variation amplitude is within, at or outside a predetermined limit, calling for a decrease, maintaining or increase, respectively, of the addition of water, the device has a number of obvious auxiliary means which may be necessary for obtaining the desired result.
  • a clock signal generator 24 is present, providing for clock signals with a periodicity selected with respect to the periodicity of the rate variations and the circulating time for the material in the rolling circuit.
  • the clock pulse generator 24 generates a signal applied to governor l2 and defining the above mentioned sampling time at the end of which an increasesignal is sent to the servomotor, should the amplitude not touch a predetermined limit during the sampling period.
  • a control signal is supplied to the servomotor with a predetermined to prevent a valve motion caused by occasional variations in the rate of return material independently of the water content of the slick and the balls, to provide for a back signal indicating the completion of a control motion of the servomotor 21 or valve 22, respectively, said signal being applied to the governor 12 via a back signal conductor 25 to zero-positioning it, this to obtain that the state present prior to the control motion of servomotor or valve does not, due to the time constant valid for the rolling circuit, gives rise to a control signal for a control in the same direction and before the control already provided for has been stated by observation of a change in the oscillation amplitude of the return material.
  • the average quantity per time unit of the return material measured by the measuring machine 11 has, according to experience, a determined relation to the quantity of fresh material supplied to the rolling machine for a particular ball rolling circulation circuit, to the effect that an adjustment or change of amplitude limits in the governor 12 may be provided for by guidance of a weighing machine 26 which provides for a signal indicating rate of fresh material supplied to the machine. Normally, such a weighing machine 26 is present in the equipment of conventional ball rolling machines of the kind.
  • a method of controlling a supply of liquid to a material composition adapted to be formed into balls for sintering, said composition being constituted of a slick consisting of a mixture of powdery iron ore material and aqueous liquid in a ball rolling machine comprising an open ended rotary ball rolling drum to an entrance end of which is supplied a supply of fresh slick and a supply of said ore material which has already passed through the rotary drum and which after having left the drum at an exit end remote from said entrance end, has passed through a sieve separating material which upon passing the drum is below a size of balls of a prescribed size to be passed on as a final product of the machine, said separated smaller-sized material passing through the sieve being reconveyed from said exit end back to said entrance end of the drum at a rate corresponding substantially to the rate of which said reconveyed material passes through the sieve, the liquid content of the material being treated in the drum being adjusted by varying a supply of aqueous liquid being added to the material so as to change the consistency of the

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Environmental & Geological Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Glanulating (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
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US319467A 1971-12-30 1972-12-29 Controlling admixture of aqueous liquid to ball rolling of powdery iron ore Expired - Lifetime US3900293A (en)

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SE16944/71A SE359315B (de) 1971-12-30 1971-12-30

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JP (1) JPS4880472A (de)
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4091060A (en) * 1975-07-29 1978-05-23 British Steel Corporation Balling process
US5102586A (en) * 1988-10-27 1992-04-07 Kawasaki Steel Corporation Agglomerating process of sinter mix and apparatus therefor
US20170010221A1 (en) * 2014-04-22 2017-01-12 Halliburton Energy Services, Inc. Systems and Methods for Analyzing Contaminants in Flowing Bulk Powder Compositions

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5343038U (de) * 1976-09-17 1978-04-13

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2699381A (en) * 1953-08-28 1955-01-11 Phillips Petroleum Co Oil pelleting of carbon black
US2800399A (en) * 1954-08-09 1957-07-23 Phillips Petroleum Co Process for controlling feed rate to pellet mill
US2867513A (en) * 1956-01-19 1959-01-06 Phillips Petroleum Co Process and apparatus for pelleting
US2872300A (en) * 1954-10-18 1959-02-03 Phillips Petroleum Co Process and apparatus for simultaneously pelleting powdered materials and classifying same
US2948918A (en) * 1953-10-16 1960-08-16 Phillips Petroleum Co Water spray in pellet mills
US3017662A (en) * 1959-05-06 1962-01-23 Phillips Petroleum Co Process control system
US3036737A (en) * 1959-02-24 1962-05-29 Phillips Petroleum Co Surge tank for feeding finely divided flocculent solids
US3293003A (en) * 1963-06-03 1966-12-20 Cabot Corp Controlling water and carbon black feed responsive to weight of feed to pelletizer
US3390424A (en) * 1966-10-06 1968-07-02 Continental Carbon Co Apparatus for pelletizing finely divided solids

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2699381A (en) * 1953-08-28 1955-01-11 Phillips Petroleum Co Oil pelleting of carbon black
US2948918A (en) * 1953-10-16 1960-08-16 Phillips Petroleum Co Water spray in pellet mills
US2800399A (en) * 1954-08-09 1957-07-23 Phillips Petroleum Co Process for controlling feed rate to pellet mill
US2872300A (en) * 1954-10-18 1959-02-03 Phillips Petroleum Co Process and apparatus for simultaneously pelleting powdered materials and classifying same
US2867513A (en) * 1956-01-19 1959-01-06 Phillips Petroleum Co Process and apparatus for pelleting
US3036737A (en) * 1959-02-24 1962-05-29 Phillips Petroleum Co Surge tank for feeding finely divided flocculent solids
US3017662A (en) * 1959-05-06 1962-01-23 Phillips Petroleum Co Process control system
US3293003A (en) * 1963-06-03 1966-12-20 Cabot Corp Controlling water and carbon black feed responsive to weight of feed to pelletizer
US3390424A (en) * 1966-10-06 1968-07-02 Continental Carbon Co Apparatus for pelletizing finely divided solids

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4091060A (en) * 1975-07-29 1978-05-23 British Steel Corporation Balling process
US5102586A (en) * 1988-10-27 1992-04-07 Kawasaki Steel Corporation Agglomerating process of sinter mix and apparatus therefor
US20170010221A1 (en) * 2014-04-22 2017-01-12 Halliburton Energy Services, Inc. Systems and Methods for Analyzing Contaminants in Flowing Bulk Powder Compositions

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Publication number Publication date
DE2263722B2 (de) 1977-12-01
DE2263722A1 (de) 1973-07-05
SE359315B (de) 1973-08-27
JPS4880472A (de) 1973-10-27
DE2263722C3 (de) 1978-07-20

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