US2854171A - Material feed control means for handling granulated slag and similar materials - Google Patents

Description

Sept 3Q, N58

. M. TRIEF' 2,854,171 MATERIAL FEED CONTROL MEANS FOR HANDLING GRANULATED SLAG AND SIMILAR MATERIALS Filed NOV. 9, 1954 Evil WW M Patented Sept. 30, 1958 MATERIAL FEED CONTROL MEANS FOR HAN- DLING GRANULATED SLAG AND SIMILAR MATERIALS Marcel Trief, Erusseis, Belgium, assignor of one-half to Leon Trief, Brussels, Belgium Application November 9, 1954, Serial No. 467,826

Claims priority application France November 10, 1953 6 Claims. (Cl. 22247) United States Patent 2,767,926 granted October 23, 1956 to Leon Trief and Marcel Trief entitled Method of and Apparatus for Automatically Proportioning Granulated Material To Be Fed to a Grinding Mill provides a method and a device for continuously and automatically adjusting the weight of the slag or similar material that runs out from a tank in a given unit of time. The hardness (resistance to grinding) and specific gravity, i. e., the Weight per unit of volume, vary according to a law or relation which is known or has been established by experiment or in any other manner. This adjustment is effected in such a way that the weight of the material discharged per unit of time varies at least substantially inversely as the hardness of the material. In this way, the slag fed to a particular grinding mill and Whose amount in weight has thus been adjusted will be ground at all times to a practically constant degree of fineness.

To achieve the objective aimed at, the apparatus in accordance with United States Patent 2,767,926 feeds the material in two portions or component flows to the grinding mill that is one flow of constant weight per unit of time and one flow of variable weight under the control of the variation in volume of the said portion of constant weight. This is done in such a way that the total weight of the two components will vary substantially in reverse proportion to the hardness.

As a practical way of carrying out the invention, the apparatus in accordance with United States Patent 2,767,926 provides a device which discharges the slag or the like, from a tank, through two apertures delivering the material separately to two conveying means which feed the material, practically in synchronism, to the place of use, the said apertures cooperating with a closure member adapted to adjust the free area of the said apertures as a result of variation in specific gravity. Thisis done in such a way that one of the apertures will at all times deliver a weight which Will be constant, though adjustable at will, while the shape of the other aperture will be determined upon considering the relationship existing between the specific gravity and the hardness of the material and in such a manner that whatever he the position of the closure member, the additional weight required in order that the total weight fed per time unit varies as above described.

Patent 2,767,926 may also be used if the weight of the material fed shall be adjusted not in accordance with the variation in hardness but with that of a different factor whose law of variation as a function of the specific gravity is known. This applies also to the present improvement, though, for the sake of facility, solely the use in connection with material of variable hardness will be described herein.

Discharging the slag through two apertures has the disadvantage-especially when relatively small deliveries are concernedthat the apertures become quite small, particularly when the material is of high specific gravity.

The present improvement provides that the two discharge apertures shall be combined into a single aperture.

The single aperture may be formed by juxtapositioni-ng the apertures side by side. The slag passing through this single aperture is divided into two components as specified above by means of a partition wall arranged under the single aperture. This wall is so arranged that it follows the theoretical juxtaposition line of the two apertures. The partition wall is conveniently formed by a part of the chute wall which chute therein receives the component of variable weight, while the component of constant weight falls outside the chute, landing upon a conveyor belt, or the like, suspended on the arm of a scale provided with a constant, though adjustable weight. Any suitable means for controlling the delivery of a constant weight of material per time unit may be provided.

Further features and advantages will appear from the disclosure. One example of carrying out the invention is given hereinafter with reference to the accompanying diagrammatic drawings, in which:

Fig. 1 is a general view of a device for proportioning granulated slag;

Fig. 2 is a fragmentary sectional view on line IIII of Fig. 1;

Fig. 3 is a fragmentary sectional view according to line IIIIII of Fig. 1;

Figs. 4 and 5 illustrate the shape of two separate delivery apertures as used in accordance with the copending application;

Fig. 6 illustrates the combined shape of the single aperture, together with the partition wall cooperating therewith.

Referring to the drawings, 1 indicates a hopper fed with the material to be proportioned, delivery from which is controlled by a closure member 2 actuated by means of a rod 3 operated e. g. from a servo-motor 4. A vibrator 5 is adapted to loosen the contents of the hopper, which latter is suspended e. g. on shock-absorbing supports 6, 7. Underneath the hopper there is arranged a conveyor belt 8 passing around rollers 9, 10 supported upon a frame which also carries the drive means (not.

shown) for the conveyor belt. One end of the frame rests on a stationary knife edge 12, while its other end is suspended on one end of .a lever arm of a scale 13 the other end of which supports an adjustable weight 14. Above and below the lever arm there are provided two spring contacts 15, 16 cooperating in turn with the contact 17 carried by the said lever arm, so as to set up operation of the servo-motor 4 in the one or the other way and to cause the closure member 2 to shift under the effect of the movements of the said lever arm, with the object of maintaining a practically constant weight of material on the belt 8.

The bottom wall of the hopper is provided with a single aperture 18 formed as a result of the combination of two apertures A and B, such as those disclosed in Patent 2,767,926 and illustrated in Figs. 4 and 5.

The example chosen relates to slag the hardness D of which varies as a function of the specific gravity P. S, according to the relation If, in practice, the RS varies from 1.5 to 0.5, the hardness will vary from 1.25 to 0.75. -If the output per hour is fixed to be of 2 (metric) tons, the specific gravity being 1.5, the total weight, which varies in reverse proportion to the hardness, will have to vary from 2 to 3.33 tons per hour. the conveyor belt 8 has been fixed at 2 tons per hour, it will be necessary to deliver an additional weight varying from O to 1.33 T. P. H. and to convey the latter weight separately to the place of use. This is performed If the constant weight to be delivered to by means of a chute such as 19 which intercepts part of the material following through aperture 18. The two components delivered through the devices 8 and 19 are received inlacollector 20'whence they are carried away together to the-place of use, a grinding mill for instance. In the case of apparatus in accordance with Patent 2,767,926 two :separate apertures A and B have been provided, -'one-for delivering a constant Weight and the other for delivering the required additional weight in any one ofthe positions of the closure member 2 indicated by. the horizontalrIines in Figs. 4-5. In this applicationitwo apertures are juxtaposed, asshown in Fig. 6. The delivery from the composite aperture is divided into ztwo'compo'nents. which are separated from each otherby the walls of :chute .19 and more particularly that partzof'ithe-schute wall which extends alongthe line of juxtapos'itionrofthe twov apertures Aand B. r

If the apertures were sheerly juxtaposed, while maintaining the :rectangular shape of the aperture A, the aperture 18 would-show an irregular outline.- 'By extending the curve corresponding to one side of the aperture B so as to define the areas S 'and S of equal size, the result will be a-continuous outline of the single aperture, thus securing a more regular flow of ,the material.

It will be seen that it would be practically'impossible to use an aperture intended to be reduced to zero in the course of adjustment during operation; it follows that, in the case of the apparatus in accordance with Patent 2,767,926 the aperture B had to be extended upwards in.

order to keep up a certain minimum delivery in theposition corresponding to P.S=l.5. As a result, the aperture A delivering-a constant weight had to becorrespondingly reduced. Now, it is convenient to maintain a larger component of constant weight, whichwill improve the accuracy and the fineness of adjustment. This purpose is readily attained with the single aperture, in which case the component of variable weight received by 'the chute may be reduced tozero in an extreme position of adjustment, without any inconvenience resulting.

The continuous outline -shown in Fig. 6 has the further advantage that the shape of the aperture remains approximately similar in every position of the closure member, which is effective in promoting even operation.

One essential advantage of providing .a single aperture as compared with the provision of two apertures in accordance with the copending application lies of course in the largefree area available for an equal total delivery, with the result that the etiect of the edges, which has always been detrimental to the discharge of material, is thus greatly minimized.

It will be understood that the shape of the aperture illustrated is merely one possible example of carrying out the invention. Moreover, various changes may be made in the construction of the apparatus. The arrangement including a conveyor belt carried by a scale arm may be substituted by any other arrangement which maintains a constant Weight delivery per unit of time. The servo-motor 4 may be substituted by any other device adapted to cause the displacements of the closure member as a'function of the variation in the specific gravity of the material.

The closure member 2 may be a slidably mounted flat plate. In this instance, the bottom wall of the hopper defining aperture 18 is also flat.

The bottom wall of the hopper may be a removable, slidably mounted plate, of fiat or curved shape and is so arranged that it may be replaced by a plate provided with another aperture 18 of a shape made to suit adifferent hourly delivery, as may be required. Such substitution may also .be needed when. it is desired to handle a material of a different character.

It will-be understood that delivery per unit of time is calculated as a function of the free area and of therate of fiowof the material. In the caseof .a granulated material loosened by vibration, the rate of flow will depend upon the intensity of vibration. In order to enableeasy checking of operating conditions, one improvement consists in providing means adjacent the aperture 18 with scale divisions indicating specific gravity values (from 0.5 to 1.5 as shown in Figs. 4, 5 and 6). Then,.for particular positions of the closure member all that need be done is to 'weigh 'onelitre of material issuing from the hole, in order to check whether or not the specific gravity thereof corresponds to the mark indicated by the closure member. In case the rate of flow is not correct, all that need be done is to increase or decrease the intensity of vibration.

What I claimis:

l. A device for continuously and automatically adjusting the Weight of a granulated material of varying specific gravity discharged from a tank and whose hardness varies in a known relation with-respect to its specific gravity comprising a tank, said tank being provided with a single but variable width aperture for delivering the material therethroug'h, a movable closure member for controlling the opening of said aperture, said closure member being movable lengthwise of the .openingto conarranged underneath said aperture for subdividing the flow 'of material delivered through said apertureiinto first and second component parts, first and second conveyor means each arranged for receiving a different one of said component parts of said flow and each delivering said difierent one of said component parts of said flow to a common'destination, control means for setting'the aperture closing position of said closure member, weight responsive means having operative connection with said first conveyor means and with said control means and being responsive to the variation of the specificgravity ofthe material delivered through said aperture in such a 'way that the first of said componentparts of said flow will at 'all times deliver a substantially constant weight of thematerial per unitof time to said first conveyor means, said second component part of said flow being delivered to said second conveyor means, said aperture being divided into two portions by animaginary line coinciding with said partition means, said two portions of said aperture having a predetermined areal interrelationship in each'of the various positions of said closure member, said interrelationship being such that in any position of said closure membersaid second component part of said flow provides an additional weight of material per unit of time such that the total weight delivered per unit of time by said two component parts of said flow to said common destination varies substantially in reverse proportion to the hardness of the material.

2. The combination set forth in claim 1 wherein said partition means comprises at least a part of a chute for receiving said second component part of said flow.

3. The combination set forth in claim 1 wherein said closure member when moved to its closed position re-, duces to zero said second component part of said flow.

4. The combination set forth in claim 1 wherein said aperture has a curvilinear triangular form andsaid partition means has two substantially perpendicular sides which extend adjacent said aperture at a distance from the apex of-said triangular form.

5. A device for continuously automatically adjusting the weight of a granulated material of varyin specific gravity discharged from a tank and whose hardness varies in a known relation with respect to its specific gravity comprising a tank, a removable plate forming one wall of saidtank, said plate being provided with a single .but variable width aperture for delivering the materialtherethrough, a movable closuremember for controlling the a tive length of said aperture, a partition means oriented mainly lengthwise of said aperture and arranged underneath said aperture for subdividing the flow of material delivered through said aperture into first and second component parts, first and second conveyor means each arranged for receiving a difierent one of said component parts of said flow and each delivering said different one of said component parts of said flow to a common destination, control means for setting the aperture closing position of said closure member, Weight responsive means having operative connection with said first conveyor means and with said control means and being responsive to the variation of the specific gravity of the material delivered through said aperture in such a Way that the first of said component parts of said flow will at all times deliver a substantially constant weight of material per unit of time to said first conveyor means, said second component part of said flow being delivered to said second conveyor means, said aperture being divided into two portions by an imaginary line coinciding with said partition means, said two portions of said aperture having a predetermined areal interrelationship in each of the various positions of said closure member, said interrelationship being such that in any position of said closure member said second component part of said flow provides an additional weight of material per unit of time such that the total Weight delivered per unit of time by said two component parts of said flow to said common destination varies substantially in reverse proportion to the hardness of the material.

6. The combination set forth in claim 5 in further combination with scale division provided adjacent said aperture for indicating the specific gravity of the material for a particular position of said closure member.

References Cited in the file of this patent FOREIGN PATENTS 824,175 Germany Dec. 10, 1951

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