US3784115A - Process for the manufacturing of dry material, by crushing, grinding or milling - Google Patents

Process for the manufacturing of dry material, by crushing, grinding or milling Download PDF

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Publication number
US3784115A
US3784115A US00188265A US3784115DA US3784115A US 3784115 A US3784115 A US 3784115A US 00188265 A US00188265 A US 00188265A US 3784115D A US3784115D A US 3784115DA US 3784115 A US3784115 A US 3784115A
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United States
Prior art keywords
crushing
signal value
control means
fed
flow
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Expired - Lifetime
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US00188265A
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English (en)
Inventor
W Krijger
J Burger
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Koninklijke Nederlandsche Hoogoverns En Staalfabrieken Nv nl
KONINKLIJKE HOOGOVENS EN STAAL
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KONINKLIJKE HOOGOVENS EN STAAL
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B1/00—Preliminary treatment of solid materials or objects to facilitate drying, e.g. mixing or backmixing the materials to be dried with predominantly dry solids
    • F26B1/005—Preliminary treatment of solid materials or objects to facilitate drying, e.g. mixing or backmixing the materials to be dried with predominantly dry solids by means of disintegrating, e.g. crushing, shredding, milling the materials to be dried
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C25/00—Control arrangements specially adapted for crushing or disintegrating
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D7/00—Control of flow
    • G05D7/06—Control of flow characterised by the use of electric means
    • G05D7/0605—Control of flow characterised by the use of electric means specially adapted for solid materials

Definitions

  • ABSTRACT The method of controlling a process for the production of dry material on a continuous feed and discharge basis such as, for example, ore pellets, in a mill unit by the crushing, grinding or milling of the dry material is achieved by measuring the amount of material being fed and the amount of process material being discharged to obtain a first signal value and a second signal value, respectively, with each of these two signal values being thereafter fed to a first control means.
  • the degree of fill of the milling unit is electroacoustically detected to obtain a signal value therefor which is thereafter passed to a second control means.
  • the output signal of the second control means is passed to the first control means to adjust same to a constant value.
  • the output signal of the first control means adjusts the first control means so that the first and second signal values of the material being fed and the material being discharged will be substantially equal during the processing of the dry material.
  • the present invention relates to a process for the manufacture of dry material by a crushing, grinding or milling operation or the like wherein the material to be processed is fed into and out of a crushing plant on a continuous feed basis, and in which means are provided for controlling the supply of dry material to the crushing plant by controlling one of the supply or discharge flows of the dry material.
  • the present invention relates to the crushing of ore for the production of ore pellets, although the invention is not to be so limited thereto.
  • the present invention includes the measuring of the supply and discharge flows of material being carried by mechanical transport systems.
  • the measurement signals received by such measurements are adjusted in a first control device to an equal value, with the output signal of the control device being used for the correction of the supply flow which is greatest.
  • the adjustment of the first control device is thereafter corrected by the output signal of a second control device, which adjusts the rate of feeding of the dry material to the crushing plant to a constant value on the basis of a measurement signal derived from the sound pressure produced by the crushing plant.
  • control or adjustment primarily occurs in the process of the present invention in the comparing of the flows of material which are fed to and discharged from the crushing plant, whereby the feeding is prevented from departing from a selected value by reason of the fact that the zero level of the comparing control device is adjusted on the basis ofa signal which is indicative of the rate of feed of the drymaterial. This results in an accurate and quiet adjustment of the crushing operation.
  • the first control device is of the so-called sample-type, whereby the measurement signal, or signals, of the supply flow, or flows, is, or are, retarded over a period'of time either equal to or only slightly longer than the run-through time of the material from the point of measurement to the point of discharge of the crushing plant.
  • a fluctuation in the crushing operation of the crushing plant also will affect the volume of the return flow of material from the air sifter, causing, in turn, the supply of material to the crushing plant to be subjected to considerable fluctuations. Accordingly, it is preferred that the effect of the fluctuating return flow is taken up in adjustment control of the crushing process. In this respect, it will be found that it is not sufficient to add the return flow as a constant signal to the flow of the material to be crushed.
  • the measurement signal of the return flow of material is derived from a measurement taken just before return flow of material enters the crushing plant and almost simultaneously with the combining of the return flow and the main supply flow, it will be found unnecessary to delay the measurement signal of the return flow independently.
  • the main supply flow of the material to be crushed will usually not be in an absolutely dry state. Often this condition will also result from the fact that the main supply flow is drawn from a hopper which is filled, along with other things, with a slurry resulting from the subsequent manufacturing of the pellets. In this case it will be necessary to dry the contents of the crushing plant in a conventional manner, to wit, by flowing a heated drying gas in the direction of the flow of the material to be crushed through the crushing plant.
  • a commonly used drying process that may be employed consists of a combustion chamber being set up in front of the crushing plant in which fuel will be burned with combustion air to form hot flue gases. Care should be taken during such an operation to insure that the temperature of such flue gases will be kept within predetermined limits. These limits will be set on the one hand by the requirement that the structure of the mill or crushing plant must not be damaged by too intensive heating, while the flue gases in the plant must not reach a temperature which is below the dew point of said gases. Proposals have been made to achieve an adjustment of the temperature of the flue gas by adding cooling air to the combustion gases.
  • the quantity of cooling air will be selected such that there will be, at most, a partial vacuum in the mill, i.e., a pressure not much below that of atmospheric, so that there will be little trouble encountered with the leaking in of air from the surrounding area into the crushing plant.
  • pressure control can be achieved by controlling the adjustment of a chimney fan or stack fan by, for instance, a measurement of the gas pressure at the entrance of the crushing plant.
  • the uniformity of operation of the crushing process may be improved further, in accordance with the present invention, if the velocity of the gas in the crushing plant is maintained at a constant value.
  • the best means to achieve this is by insuring that the gas pressures before and after passing through the crushing plant are each maintained at a constant value independently of each other by adjusting the quantity of drying gas supplied and by the adjustment of a chimney stack fan respectively. By such adjustments it will be found that the fineness of the crushed product can be maintained at a constant level. Even if the amount of material varies, the gas velocity can be maintained at a substantially constant value due to the fact that there is a constant difference in pressure being maintained between the inlet end and the outlet end of the crushing plant.
  • FIG. 1 diagrammatically illustrates the flow path of the material passing through a mixing plant in which the process in accordance with the present invention may be carried out.
  • FIG. 2 is a diagrammatic representation of the various control circuits that may be employed in the practice illustrated in FIG. 1.
  • reference numeral 1 indicates a crushing plant in the form of a ball mill of a known and standard type and will therefore not be described in detail herein.
  • Material to be crushed is drawn from a hopper 2 by means of a metering belt feeder 3.
  • the said material is fed to the crushing plant 1 from the belt feeder 3 as a flow of material 12.
  • the greater part of the crushed material is directly passed from the crushing plant 1 into an elevator 4 and from the elevator is passed as fiow material 5 to a second elevator 6 and is thereafter passed to an air sifter 8 as flow material 7.
  • the finest material fractions from this flow 7 are discharged from the air sifter 8 as a flow of the final crushed product 11 which is to be subsequently processed to produce pellets.
  • the coarsest material fractions are laterally discharged from the air sifter 8 as a flow of material 9 which, after being passed over a curved measuring guide 10, are fed back to the crushing plant 1.
  • the measuring guide 10 is provided with a measuring system which by reason of a fluctuation in the impulse of the flow of material 9 resulting from the change of direction of movement of the material on said guide 10, can serve as a measurement for the mass flow per unit time of said flowof material 9.
  • the flow of material 12 from the metering feeder 3 may be changed by adjusting the drive motor 13 for the feeder 3.
  • the elevator 4 is driven by a motor 14, the drive torque of which is measured and serves as a measurement for the flow of material 5.
  • the degree of fill of the crushing plant 1 is determined by means of microphone 15 by which the sound emission of the jacket of the crushing plant is measured. It has been found that the electro-acoustic signal is an accurate indication for the degree of filling of the ball mill 1.
  • a combustion chamber 16 is positioned in which the fuel is burned to produce a hot drying gas for drying the material to be crushed.
  • the flow 18 of the fuel supplied to the combustion chamber can be adjusted with the aid of a control valve 17.
  • the valve 17 may be adjusted by means of the adjusting motor 19.
  • a flow of cooling air 20 is also passed into the combustion chamber 16 and is mixed therein with the burned fuel.
  • an adjustable valve 21 which can be operated by an adjusting motor 22, it will be possible to adjust the quantity of cooling air.
  • This will also effect the quantity and the temperature of the drying gas 23 which is fed to the crushing plant 1. It is to be understood that the quantity and the temperature are also functions'of the quantity of the fuel supplied.
  • the pressure of the drying gas in the proximity of the inlet of the crushing plant 1 is measured by means of the pressure gauge 24 which is constructed to produce an electric signal.
  • a similar pressure measurement is achieved in the gas flow 25 in the proximity of the outlet end of the crushing plant 1 by means of the pressure gauge 27.
  • the gas flow 25 is fed to a coarse air sifter 28 which separates the coarsest fractions of the grindings entrained by the gas flow 25.
  • the coarsest fractions separated by the air sifter 28 are fed back as a flow 26 and combined with the flow 5.
  • the material freed of the coarsest fractions is thereafter conveyed to the electrofilter 29 where the dust fractions discharged as a flow of material 30 from the electro-filter 29 are combined with the material flow 11 and are discharged from the unit as final product.
  • the temperature of the gas that leaves the electro-filter 29 as gas flow 31 is measured by instrument 32 which produces an electric control signal.
  • the vacuum which is generated in the gas flow 31 by the chimney stack fan 33 may be controlled by means of control valve 34 which is adjusted by adjusting motor 35.
  • FIG. 1 the flows of solid material are indicated by dot and dash lines, while the flows of fuel and gaseous products are indicated by dashed lines.
  • the flow of material carried from the hopper 2 by the metering belt feeder 3 is weighed by means of the belt scale 36.
  • FIG. 2 the way the electric signals produced by the various measuring devices are used to control the process is diagrammatically shown.
  • all of the measuring devices shown in FIG. 1 which produce electrical measurement signals are presented in a vertical row.
  • the variable speed driving motor 13 and the adjusting motors 22, 35 and 19 by which the entire process is finally controlled are shown in a vertical row. From this it will be seen that five control devices are used, viz., C 1 to C 5 inclusive, as well as two retarders 37 and 39 and an adding unit 38.
  • the velocity of the driving motor 13 of the metering belt feeder 3 is controlled in relationship to the signals produced by the belt scale 36, the curved measuring guide system 10, the driving motor 14, and the microphone 15.
  • the weight measurement signal of the belt scale 36 is first retarded by the retarder 37 for a period t, which corresponds to the runthrough period of the flow of material between the belt scale and the inlet station of the crushing plant 1.
  • the retarded signal is summed up with the signal produced by the measuring guide system 10 which is indicative of the return flow 9 from the air sifter 8.
  • the summed up signal is retarded for a period t by the retarder 39, which period 1 corresponds to the run-through period of the material through the crushing plant 1.
  • the combined signal which has been thus retarded indicates the mass of the delivered flow of material at the moment that the flow of material is discharged from the crushing plant 1.
  • the mass of material is compared with the mass of the flow of material 5 which is discharged with the measured power taken up by the driving motor 14 of the elevator 4 being a measure thereof.
  • Both signals are fed to the control device C with the output signal thereof adjusting the energy supply to the driving motor 13 of the metering belt feeder 3.
  • the zero point of the control device C may be adjusted by the output signal produced by control device C with the control device C reacting to the signal produced by the microphone 15. With this signal the control device C in fact controls the adjustment of control device C 1 to achieve a predetermined adjustable degree of filling of the crushing plant 1. To this end, the control device C may be adjusted to the desired degree of filling.
  • the gas pressures measured by the instruments 24 and 27 before and after passing through the crushing plant 1 respectively are employed to obtain an adjustment of the adjusting motors 22 and 35, with such gas pressures being used as input signals for the control devices C and C. respectively.
  • the gas pressure measured by instrument 24 behind the combustion chamher 16 is determinative of the quantity of added cooling air into said combustion chamber.
  • it is also possible to maintain a constant gas pressure behind the crushing plant 1 by an adjustment of the chimney stack fan 34 by an adjustment of the control device C By selecting the adjustment of the control devices C and C the difference in pressure over the crushing plant can be adjusted to any desired constant value, with which the gas velocity through the crushing plant is also adjustable.
  • the temperature of the drying gas after having been discharged from the electro-filter 29 is maintained at a constant value by means of the adjustment of control device C
  • the fuel valve 17 is adjusted through adjusting motor 19 by the control device C
  • the method of controlling the feeding of dry material to a crushing, grinding, or milling unit on a continuous feed and discharge basis comprises measuring the amount of material being fed for processing to obtain a first signal value therefor, measuring the amount of processed material discharged to obtain a second signal value therefor, passing each of said signal values to a first control means, electroacoustically detecting the degree of fill or the dry material crushing zone to obtain a signal value therefor, passing said signal value to a second control means, passing the output signal of said second control means to said first control means to adjust same to a constant value and with the output signal of said first control means thereby adjusting said first control means so that the first and second signal values of the material being fed and the material being discharged will be substantially equal during the processing,

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Food Science & Technology (AREA)
  • Drying Of Solid Materials (AREA)
  • Disintegrating Or Milling (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US00188265A 1970-10-12 1971-10-12 Process for the manufacturing of dry material, by crushing, grinding or milling Expired - Lifetime US3784115A (en)

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NL7014936A NL7014936A (de) 1970-10-12 1970-10-12

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US (1) US3784115A (de)
AU (1) AU443296B2 (de)
CA (1) CA945970A (de)
DE (1) DE2149186C3 (de)
FR (1) FR2111232A5 (de)
GB (1) GB1361418A (de)
IT (1) IT939976B (de)
NL (1) NL7014936A (de)
SE (1) SE373299B (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4026479A (en) * 1976-01-19 1977-05-31 Brenda Mines Ltd. Method and system for maintaining optimum throughput in a grinding circuit
US4225091A (en) * 1978-02-23 1980-09-30 Babcock Krauss-Maffei Industrieanlagen Gmbh Method of and apparatus for the milling of solids
US4281800A (en) * 1979-11-02 1981-08-04 Allis-Chalmers Corporation Operation of associated crushing plant and mill
US5971302A (en) * 1996-11-15 1999-10-26 Doumet; Joseph E. Method and apparatus for drying and grinding moist material
US20060060684A1 (en) * 2004-08-13 2006-03-23 Invensys Systems, Inc. Methods and systems for cement finishing mill control
US11097283B2 (en) * 2018-10-30 2021-08-24 New Planet Energy Development Llc Systems and methods for municipal solid waste recycling facility
CN115128950A (zh) * 2022-06-16 2022-09-30 矿冶科技集团有限公司 破碎筛分控制方法、装置、电子设备及存储介质

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2525922B1 (fr) * 1982-05-03 1985-10-11 Stein Industrie Procede et dispositif de reglage du fonctionnement d'un appareil de broyage
DE3462223D1 (en) * 1984-07-10 1987-03-05 Stetter Gmbh Re-treatment installation of waste concrete
CN103182341A (zh) * 2011-12-29 2013-07-03 洛阳宇航重工机械有限公司 一种开式风带物料式氧化铝结壳块破碎生产线装置

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1898086A (en) * 1930-06-12 1933-02-21 Foster Wheeler Corp Pulverizing apparatus
US2235928A (en) * 1939-01-04 1941-03-25 Hardinge Co Inc Apparatus for and method for controlling grinding devices
US2535570A (en) * 1946-12-31 1950-12-26 Comb Eng Superheater Inc Continuous batch flash drier having coordinated feed and recycling means
US2916215A (en) * 1956-09-10 1959-12-08 Weston David Air systems for dry material reduction mills and controls therefor
US3179345A (en) * 1963-07-29 1965-04-20 United States Steel Corp Method and apparatus for controlling a grinding mill
US3314614A (en) * 1964-04-15 1967-04-18 Federal Ind Ind Group Inc Analog computer grinding control
US3587980A (en) * 1968-02-28 1971-06-28 Polysius Gmbh Method of controlling the rate of feed to an extraneously energized airswept mill
US3630457A (en) * 1968-10-24 1971-12-28 Vyzk Ustav Stavebnich Hmot Regulation of the supply of raw material to a closed circuit grinding mill system

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1898086A (en) * 1930-06-12 1933-02-21 Foster Wheeler Corp Pulverizing apparatus
US2235928A (en) * 1939-01-04 1941-03-25 Hardinge Co Inc Apparatus for and method for controlling grinding devices
US2535570A (en) * 1946-12-31 1950-12-26 Comb Eng Superheater Inc Continuous batch flash drier having coordinated feed and recycling means
US2916215A (en) * 1956-09-10 1959-12-08 Weston David Air systems for dry material reduction mills and controls therefor
US3179345A (en) * 1963-07-29 1965-04-20 United States Steel Corp Method and apparatus for controlling a grinding mill
US3314614A (en) * 1964-04-15 1967-04-18 Federal Ind Ind Group Inc Analog computer grinding control
US3587980A (en) * 1968-02-28 1971-06-28 Polysius Gmbh Method of controlling the rate of feed to an extraneously energized airswept mill
US3630457A (en) * 1968-10-24 1971-12-28 Vyzk Ustav Stavebnich Hmot Regulation of the supply of raw material to a closed circuit grinding mill system

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4026479A (en) * 1976-01-19 1977-05-31 Brenda Mines Ltd. Method and system for maintaining optimum throughput in a grinding circuit
US4225091A (en) * 1978-02-23 1980-09-30 Babcock Krauss-Maffei Industrieanlagen Gmbh Method of and apparatus for the milling of solids
US4281800A (en) * 1979-11-02 1981-08-04 Allis-Chalmers Corporation Operation of associated crushing plant and mill
US5971302A (en) * 1996-11-15 1999-10-26 Doumet; Joseph E. Method and apparatus for drying and grinding moist material
US20060060684A1 (en) * 2004-08-13 2006-03-23 Invensys Systems, Inc. Methods and systems for cement finishing mill control
US7591440B2 (en) * 2004-08-13 2009-09-22 Invensys Systems, Inc. Methods and systems for cement finishing mill control
US11097283B2 (en) * 2018-10-30 2021-08-24 New Planet Energy Development Llc Systems and methods for municipal solid waste recycling facility
CN115128950A (zh) * 2022-06-16 2022-09-30 矿冶科技集团有限公司 破碎筛分控制方法、装置、电子设备及存储介质

Also Published As

Publication number Publication date
AU3444871A (en) 1973-08-30
DE2149186C3 (de) 1979-10-18
FR2111232A5 (de) 1972-06-02
SE373299B (sv) 1975-02-03
GB1361418A (en) 1974-07-24
CA945970A (en) 1974-04-23
IT939976B (it) 1973-02-10
DE2149186A1 (de) 1972-05-25
NL7014936A (de) 1972-04-14
DE2149186B2 (de) 1979-02-22
AU443296B2 (en) 1973-12-20

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