US3923255A

US3923255A - Vertical spindle pulverisers

Info

Publication number: US3923255A
Application number: US465592A
Authority: US
Inventors: Keith W G Leonard
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-07-03
Filing date: 1974-04-30
Publication date: 1975-12-02
Anticipated expiration: 1992-12-02
Also published as: GB1419726A; CA1017311A; AU6864074A; ZA734492B; AU465291B2

Abstract

A vertical spindle pulveriser including a housing structure in which a spindle, having a grinding disc attached near one end thereof, is vertically and rotatably mounted. A complementary grinding disc is fixed in the structure above the first disc, a compartment is formed in the structure about and below the discs, a receptacle is located below the discs and a feed hopper is provided such that is communicates with a space between the discs. Provision is made for improved means for supplying air under pressure to automatically sweep the interior of the pulverizer and these means include an axial central bore through the spindle, at least one radial outlet through the spindle which emerges facing the upper fixed grinding disc and at least one radial outlet through the lower end of the spindle below the discs. Other air outlets are provided in the pulverizer for cleaning other parts thereof, and these outlets and the axial bore in the spindle are connected to a source of compressed air through a control valve which is automatically activated when the receptacle is removed after a comminuting operation.

Description

United States Patent [1 1 Leonard Dec. 2, 1975 l l VERTICAL SPINDLE PULVERISERS Keith W. G. Leonard, 4 Geneva St., Lakefield, Benoni, South Africa [22] Filed: Apr. 30, 1974 [2lj Appl. No.: 465,592

[76] Inventor:

Primary Examiner-Granville Y. Custer, Jr. Attorney, Agent, or FirmBurns, Doane, Swecker & Mathis [57] ABSTRACT A vertical spindle pulveriser including a housing structure in which a spindle, having a grinding disc attached near one end thereof, is vertically and rotatably mounted. A complementary grinding disc is fixed in the structure above the first disc, a compartment is formed in the structure about and below the discs, a receptacle is located below the discs and a feed hopper is provided such that is communicates with a space between the discs. Provision is made for improved means for supplying air under pressure to automatically sweep the interior of the pulverizer and these means include an axial central bore through the spindle, at least one radial outlet through the spindle which emerges facing the upper fixed grinding disc and at least one radial outlet through the lower end of the spindle below the discs. Other air outlets are provided in the pulverizer for cleaning other parts thereof, and these outlets and the axial bore in the spindle are connected to a source of compressed air through a control valve which is automatically activated when the receptacle is removed after a comminuting operation.

7 Claims, 1 Drawing Figure US. Patent Dec. 2, 1975 3,923,255

VERTTCAL SPENDLE PULVERISERS BACKGROUND OF THE INVENTION The present invention relates to vertical spindle pulverisers utilising grinding discs for communicating and pulverising hard materials, particularly ore samples.

One vertical spindle pulveriser of known type basi cally comprises a structure housing a vertical rotatable spindle having a grinding disc secured to the end thereof. A complementary grinding disc is fixed in the structure and a chamber is provided about and below the discs embodying a removable dish. A feed hopper communicates with a space between the discs and a fan is attached to the rotatable grinding disc below this disc to create in use, air currents below the dish. The spindle and attached disc are adapted to be moved vertically such that the discs may be brought into contact with each other. To this end, a pneumatic piston and cylinder assembly is included in the structure and, furthermore, a handwheel is provided so that the spacing between discs can be adjusted to accomodate wear of the discs.

After each grinding operation of the discs are parted and the pulveriser is swept by air under pressure which is directed into the space between the grinding discs and onto the lower, rotatable disc through a circumferentially arranged plurality of jets above the discs. Similarly the facing periphery of the discs is cleared by jets of air emitted through to peripheral plurality of jets with outlets between the discs. The feed hopper is swept by air introduced therein which carries dust down through the gap between the discs. All of the dust swept in the above three manners is extracted from the housing through an exhaust outlet connected to evacuating means. in addition, the enclosed space above the space between the discs is swept by evacuatron.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the present invention to provide a vertical spindle pulveriser with an improved and more efficient sweeping or blow-down action.

It is a further object of the invention to minimise the escape of dust from the entrance of the feed hopper, which dust is harmful to the health of the pulveriser operator.

In accordance with this invention there is provided a vertical spindle pulveriser comprising a housing structure in which is mounted a vertical rotatable spindle having a grinding disc secured near the lower end thereof, a complementary grinding disc fixed in the structure above the first disc, a chamber about and below the discs and a feed hopper communicating with a space between the discs, characterised in that the pulveriser includes means supplying air under pressure automatically to sweep the interior of the pulveriser, the means comprising an axial central bore through the rotatable vertical spindle, at least one radial outlet through the spindle to emerge facing the upper fixed grinding disc and at least one second radial outlet through the lower end of the rotatable spindle below the discs.

The invention also provides a plurality of air outlets near the exterior opening to and inside the feed hopper.

Other features of the invention provide for the means to further include an air outlet adapted to direct air onto a central concave portion of the lower rotatable 2 grinding disc and an air outlet above the upper fixed disc adapted, in use, to supply air to clean the peripheral sides of the discs and means for moving the discs toward and away from each other.

Also the invention provides for some of said outlets to be jet nozzles and for the feed hopper to have an aperture in a side thereof connecting the hopper to a partially evacuated enclosed space above the grinding discs.

DETAILED DESCRIPTION A preferred embodiment of the invention will now be described by way of example, reference being made to the accompanying drawing which is a cross-sectional elevation of part of a vertical spindle pulveriser.

In this embodiment a vertical spindle pulveriser of the type outlined above comprises a vertical rotatable spindle 1 having a rotatable grinding disc 2 attached near its lower end. The spindle is housed in a structure 3 and a fixed grinding disc 4 is secured in the structure above the rotatable disc 2. A funnel 5 is located in the structure with its wider end encircing the discs 2 and 4 and with its narrow end protruding into a container 6 supported on a base 7. This base is, in turn, pivotally mounted in the structure as at 45 about a horizontal axis and is also mounted on a pneumatic piston and cylinder assembly 8 serving as a ram which maintains the container 6 in close contact with the funnel 5. A spring 44 is provided to bias the base downwardly.

The structure 3 includes an upper and a

lower compartment

9 and 10 which are divided by a wall 11 to which the fixed grinding disc 4 is removably attached. A continuous space 12 is formed between the grinding discs by a central concave portion in the discs and be tween the spindle l and dividing wall 11. A feed hopper 13 in the form of a chute communicates between this space 12 and the exterior of the pulveriser.

The rotatable spindle 1 has an axial bore 14 therethrough which emerges at the lower end of the spindle in two jets 15. A radial passage 16 connects the central bore with the said space 12 between the grinding discs and emerges directed towards the fixed disc 4. A fan 46 is attached near the lower end of the spindle.

An air pipe 17 passes through the wall of the compartment 9 and through the dividing wall 11 into the space 12 through an aperture directed downwardly towards the rotatable lower disc 2. A further air pipe 18 communicates with appropriate outlets in the wall 11 such that, in use, air will be directed down the sides of the discs adjacent the top part of the funnel 5. An air jet indicated at 19, is located inside the hopper 13 near the exterior end thereof and the jet is directed substantially down the side walls into the hopper. This jet is formed by a perforation in an air supply pipe. An aperture 20 in the wall of the hopper connects the hopper with the interior of the upper compartment 9 of the pulveriser structure. This compartment and the lower compartment W are connected to pipes 21 which may in turn be connected to evacuating means (not shown). A butterfly or other control valve 22 can be provided to vary the suction applied to the two compartments as desired.

The spindle 1 is rotatably mounted in a housing 30 which has a piston 31 adapted to slide vertically in a closed cylinder 32 formed in the structure of the pulverisor.

In the structure above the cylinder is a socket 33 with the screwed boss 34 of a hand wheel 35 rotatable therein. Hand wheel 35 is rotated to adjust the grinding space between the grinding discs and thereby accomodate disc wear. A lock nut 36 is provided adjacent to hand wheel boss to adjust the spacing between the discs when parted as outlined below. The grinding spindle at the top has a pulley 37 which it is attached by means of a belt or the like to a driving motor 38 fixed to one side of the structure.

The piston 31 is adapted to be moved up and down in the cylinder 32 by means of compressed air supplied through pipes 40 to open and close the space between the discs during blowdown and grinding operations respectively. The space is regulated by the hand wheel 35 so that the discs are maintained in proper relation one with the other during communition of the charge.

A swivel connector housing 39 encloses the top of the centrally bored spindle and an air pipe 41 communicates with the interior of this housing such that air, under pressure, may be blown down the central bore in the spindle when the latter is rotating. This air pipe,

pipes

17, 18 and 40 further air pipes 42 connected to the pneumatic ram 8 are suitably connected to a supply source of compressed air and a blowdown valve 24 and a control valve 43 are provided for the purpose outlined below.

A complete operational cycle of the pulveriser is now described to emphasis the improved characteristics of this pulveriser.

Initially, the handwheel is rotated until the desired operative distance between the grinding discs is established. Control valve 43 is opened to allow air to pass below the piston and move the discs toward one another and the spindle is rotated by means of the motor. The hard wheel 35 is used to vary and adjust the operative grinding space by which the discs are separated during comminuting. In assaying, the average particle size of comminuted samples may need to be varied and it is operative spacing between the discs which will determine the resulting particle size. Also, the discs become worn with time and the hand wheel allows compensation for wear. The piston and cylinder assembly is included in the pulverizer to move the discs towards and away from each other at the commencement and at the end of a pulverizing operation. At commencement of a pulverizing operation, the piston 31 moves the discs toward each other until they are spaced apart by the amount determined by the hand wheel setting. The lock-nut 36, on the other hand, determined the distance by which the discs can be moved apart by the piston 31 at the end of a pulverizing operation. The pipes 21 communicating with the

compartments

9 and 10 are connected to evacuating means so that a partial vacuum is maintained in these compartments.

The pneumatic ram 8 moves the base 7 and container 6 upwardly until the latter is in form abutment with the funnel 5. The sample to be pulverised is introduced into the feed hopper 13 and falls into the space 12 between the grinding discs. Pulverised material is directed by the funnel into the container 6 where it is retained. It is to be appreciated that any dust formed which would normally escape via the feed hopper entrance is sucked through the aperture into the upper compartment 9 and out through the exhaust pipe 21.

When the sample is completely ground, the discs are parted by operating the control valve 63 and the pneumatic ram simultaneously lowers the base and container. This container is removed from the lower compartment through an aperture 23 in the compartment and this removal actuates the blow-down valve 24 which in turn activates the cleaning or blow-down system. The valve is preferably activated by an arm 47 pivotally attached to the base such that removal of the dish causes the arm to move and thereby open the valve.

Air under pressure is forced through the several apertures and airjets outlined above, and it is to be appreciated that the spindle and rotatable disc continue spinning throughout. The jets l6, and the apertures associated with

pipes

17 and 18 direct air onto the upper fixed grinding disc 2, on to the lower spinning grinding disc and around the periphery of the lower and upper discs respectively. Since jet 16 is rotating and since the lower disc continues to rotate, it is obvious that the entire facing surfaces areas of both discs are thoroughly cleaned.

The jet 19 ensures that the hopper is well cleaned and dust is blown both through the aperture 20 and down into the lower compartment 10. Air forced through the rotating jets 15 in the end of the spindle clean the walls of the funnel and the dust accumulated in the compartment is extracted through the exhaust pipe 21.

Dust from the hopper which accumulates in the upper compartment 9 is extracted through the other exhaust pipe 21.

The container 6 may now be replaced which automatically terminates the air supply to the blowdown system and another cycle commenced.

It is to be appreciated that the container 6 may not be removed while a grinding operated is in process since the pneumatic ram holds the container against the funnel and the ram is activated when the control valve is opened to move the discs towards each other.

Blowdown of the pulveriser occurs automatically on removal of the container and the pulveriser according to the present invention ensures that a strict sequence of operations is adhered to.

The formatiotn of jets in the rotating spindle obviates the necessity of having several jets circumferentially arranged in the pulveriser. The general arrangement of air jets as above described ensures that the interior of the pulveriser is thoroughly and efficiently cleaned after each cycle, and harmful dust, which normally escapes from the feed hopper, is extracted through the pulveriser.

I claim:

1. A vertical spindle pulverizer comprising a housing structure;

a spindle vertically and rotatably mounted in the structure;

means for rotating the spindle;

a first grinding disc secured to the spindle near the lower end thereof;

a second complementary grinding disc fixed in the structure above said grinding disc and with the spindle passing through a central aperture therein;

a compartment in the structure about and below said discs;

a removable receptacle located in the structure below said discs and in said compartment;

a feed hopper communicating with a space between the discs;

the pulverizer being characterized in that it includes means for supplying air under pressure automatically to sweep the interior of the pulverizer, said means comprising: an axial central bore through said spindle;

at least one radial outlet through the spindle from said bore which emerges facing said second grinding disc;

at least one radial outlet through the lower end of said spindle below said first disc;

a source of compressed air connected to said axial central bore in the spindle;

a valve controlling the supply of compressed air to said axial central bore, the valve being in cooperative relationship with said receptacle such that removal of the latter automatically opens the valve and replacement of said receptacle automaticaliy closes the valve.

2. A vertical spindle pulverizer as claimed in claim 1 in which a plurality of air outlets are mounted in said feed hopper near the exterior opening thereof, said outlets being directed toward the interior of the hopper and being connected through said valve to said source of compressed air.

3. A vertical spindle pulverizer as claimed in claim 1 in which said air supplying means includes an air outlet mounted above said first and second discs and directed in downward communication with said central aperture in said second disc to direct air through said central aperture in the second disc onto a central concave portion of the first grinding disc, said air outlet being connected through said valve to the source of compressed air.

4. A vertical spindle pulverizer as claimed in claim 1 in which said air supplying means further include an air outlet above said second disc connected through said valve to said source of compressed air, this outlet, being adapted, in use, to supply air to clean the sides of said first and second discs and the top adjacent portion of a funnel located about and below said discs and directed toward said receptacle.

5. A vertical spindle pulverizer as claimed in claim 1 in which further means are provided for moving the discs toward and away from each other.

6. A vertical spindle pulverizer as claimed in claim 5 in which said further means comprises a double acting pneumatic piston and cylinder assembly, the piston being provided on a housing for the rotatable spindle and the cylinder being formed in the pulverizer structure surrounding the piston.

7. A vertical spindle pulverizer as claimed in claim 1 in which said feed hopper has an aperture in a side thereof connecting the interior of the hopper to an enclosed space in the pulverizer structure above said grinding discs and said compartment, said space being connected by means of piping to evacuating means.

Claims

1. A vertical spindle pulverizer comprising a housing structure; a spindle vertically and rotatably mounted in the structure; means for rotating the spindle; a first grinding disc secured to the spindle near the lower end thereof; a second complementary grinding disc fixed in the structure above said grinding disc and with the spindle passing through a central aperture therein; a compartment in the structure about and below said discs; a removable receptacle located in the structure below said discs and in said compartment; a feed hopper communicating with a space between the discs; the pulverizer being characterized in that it includes means for supplying air under pressure automatically to sweep the interior of the pulverizer, said means comprising: an axial central bore through said spindle; at least one radial outlet through the spindle from said bore which emerges facing said second grinding disc; at least one radial outlet through the lower end of said spindle below said first disc; a source of compressed air connected to said axial central bore in the spindle; a valve controlling the supply of compressed air to said axial central bore, the valve being in cooperative relationship with said receptacle such that removal of the latter automatically opens the valve and replacement of said receptacle automatically closes the valve.