AU775438B2

AU775438B2 - Improved ore screening panels

Info

Publication number: AU775438B2
Application number: AU55905/01A
Authority: AU
Inventors: Jeff Zubovich
Original assignee: Screenex Australia Pty Ltd
Current assignee: Sandvik Rock Processing Australia Pty Ltd
Priority date: 2000-07-25
Filing date: 2001-07-24
Publication date: 2004-07-29
Anticipated expiration: 2021-07-24
Also published as: AU5590501A

Description

AUSTRALIA

Patents Act

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: /01 Lodgement Date: 2 4 t h July 2001 Nominated Patentee: Screenex Australia Pty Ltd Invention Title: Improved Ore Screening Panels The following statement is a full description of this invention, including the best method of performing it known to the applicant.

*logo* *~e Improved Ore Screening Panels Field of the invention This invention relates to improvements in ore screening panels used in the separation and grading of materials in the mining and quarrying industries and in particular is concerned with support spacers for vertically spacing such panels in the inclined section of banana screens.

Background to the invention Screening panels of the kind described in Australian patents 482212 [headed spigot fastening] and 517319 [pin fastening) are fitted to vibrating screening machines and usually they are fitted to steel frames that are adapted to support and secure the panels.

Patent 601052 discloses a compact arrangement of mounting one set of *screening panels on a lower set. This is achieved by providing an integral spacer element along one edge of each lower panel. Double screen decks of this kind have been well accepted. However in use a number of shortcomings became apparent. The spacers being integral with the panels limits the choice of panel orientations available. This problem was overcome by the arrangement disclosed in patent application 34999/99.

Often the forward section of a screening deck has been curved as in sieve bend sections curved at 450 to increase the velocity of the ore across the screen deck.

These panels also function to dewater the ore slurry. In recent times the sieve 25 bend sections have been replaced with banana screens which are usually longer in length with staged incremental changes in the inclination of the panels.

To date it has only been possible to use a single deck of screening panels in the banana section.

It is an object of this invention to provide improved banana screens.

Brief Description of the Invention To this end the present invention provides a screening apparatus having two modular screening decks, the lower deck being mounted on a support frame and the upper deck being mounted on the lower deck wherein the leading section of the upper deck is spaced behind the leading section of the lower deck and the lower deck incorporates a ramp which abuts the leading edge of said upper deck, said ramp being inclined upwardly in the direction of travel of the ore to enable the ore flowing onto the leading section of said lower deck to be raised on to the upper deck.

This arrangement ensures that the material separated by the lower deck is kept separate from the material retained on the upper deck. The upper deck panels are sized differently to the lower deck panels to accommodate the small arc distance traversed by the upper deck relative to the lower deck.

This invention is particularly applicable to banana screens. A banana screen usually commences at an inclination of about 30 400 and changes toward the :horizontal by 2 80 increments preferably 50. The upper deck preferably :commences when the inclination is about 200. The upper and lower decks can start at the same point or the upper deck may have its leading edge behind the leading edge of the lower deck.

20 In order to lift the ore from the lower to the upper deck an inclined ramp is located on the lower deck immediately in front of the upper deck. Preferably the upper o*surface of this ramp is at or above the level of the surface of the upper deck. This S: ramp may be composed of any suitable material such as rubber but is preferably made from polyurethane.

25 The trailing edge of the lower deck is in advance of the trailing edge of the upper deck so that the material passing over the upper deck can be kept separate from -the material passing over the lower deck which in turn is kept separate from the material passing through the lower deck.

The manner of forming the two or more screening decks may be in accordance with the disclosures of patent 601052 or of patent application 34999/99 both of which are incorporated herein by reference.

In a preferred embodiment the present invention provides a banana screening apparatus which includes a) at least two screening decks and one support frame for all the decks b) each screening deck being composed of a plurality of modular rectangular screening panels c) each screening panel including an apertured screening surface bounded by four edges of the panel (ii) at least two integral, dependent, fastening spigots on the underside of at least two edges (iii) the dependent fastening spigots optionally including a groove to accommodate a pin d) spacers between each pair of screening decks, each spacer including at its lower end at least one pin adapted to fit into the grooves of said fastening spigots of the modular panels and at its upper end at least one socket axially aligned with said pin and adapted to receive said fastening spigots of said modular panels e) the upper and lower screening decks changing in inclination from at least 200 :to 00 f) wherein the leading edge of the lower deck is in advance of the leading edge e 20 of the upper deck and a ramp is mounted on said lower deck to abut the leading edge of the upper deck to enable the flowing ore to rise onto the o, ~upper screening surface.

When the leading edge of the lower deck is in advance of the leading edge of the S: upper deck a ramp is mounted on said lower deck to abut the leading edge of the upper deck to enable the flowing ore to rise onto the upper screening surface.

••The upper deck preferably commences at a point where the inclination of the lower deck is at least 200.

The utilization of separate, non integral fasteners of the kind disclosed in patent application 34999/99 means that only one type of panel is essential, namely those using a pin fastening system of the kind described in patent 517319. It is possible to use a spigot type fastening system for the top deck. Although the inventory will also require spacers these are less expensive than panels. By using non integral spacers problems with orientation of the panels is avoided.

Blinding of the sockets in the spacers is avoided by the provision of drainage holes.

The axial alignment of the fastening pins and the sockets means that the panel retention forces for all the screen decks act along the same axes.

When more than one socket and pin combination is used the spacer will take the form of a bar and it is preferred that the thickness of the bar is less in the regions between the sockets. Where only one socket and pin is used the spacer will be generally cylindrical with a maximum diameter equaling the external diameter of the socket. These arrangements mean that the amount of material used to form the spacers is reduced compared to the prior art.

The spacers are preferably formed from the same material as the panels, namely, polyurethane. If deemed necessary the bars may be reinforced to ensure that the spacers can withstand the forces during operation of the vibratory screening machines.

Both the upper and lower decks change there inclination to the horizontal over the length of the deck with the inclination decreasing in the direction of travel of the ore to be screened. The change in inclination is preferably in increments of 5 to :100 and changes from an initial inclination as high as 45 o to 00.

20 Detailed Description of the Invention Preferred embodiments of the invention will now be described with reference to the drawings in which: Figure 1 is a schematic side view showing a first twin banana screening arrangement with detail of the lower deck panels; S: 25 Figure 2 is a schematic side view showing a first twin banana screening arrangement with detail of the upper deck panels; *:***Figures 3A and 3B are an end view and a side view of the ramp used in figures 1 2; Figure 4 is a schematic side view showing a second twin banana screening arrangement with detail of the lower deck panels; Figure 5 is a schematic side view showing a second twin banana screening arrangement with detail of the upper deck panels; The actual panel and spacer configurations for the two decks are the same as those disclosed in patent application 34999/99 or in patent 601052.

The banana screen layout is shown in figures 1 and 2 or 4 5. The arrows indicate the direction of flow of the ore particles.

In figures 1 and 2 the lower deck comprises five sections 11, 12, 13, 14 and Section 11 is inclined at 300, section 12 is inclined at 22.5 0, Section 13 is inclined at 150, Section 14 is inclined at 7.50 and section 15 is horizontal.

Rows 1 and 22 are solid impact panels 16. Rows 2 to 8 are panels with 22mm slot apertures while rows 10 to 20 are 22mm panels with apertures of the self cleaning io type illustrated in patent 608392. Row 21 comprises removable panels to allow the separation of the ore that remains above the lower deck. Side impact panelsl 8 are located along the sides of the panel arrays to deflect particles back onto the screening surface.

The inclined rampl9 which deflects the ore upwardly onto the upper deck is located in row 9 immediately in front of the first row of the upper deck. This panel as °illustrated in figures 3A and 3B comprises the base portion 19 an inclined face inclined at an angle 25 of 1200 to the surface of panel 19 and having an upper shallowly inclined top surface 21. This panel has conventional fastening spigots 23 and can accommodate spigots from the panels of the upper deck in the cylindrical 20 socket 24.

In the upper deck layout shown in figure 2, the stages are inclined in the same way the lower deck. Row 1 corresponds to row 10 of the lower deck and the upper deck has one more row than the lower deck so that particles not passing through the upper deck can be separately collected off the end of the upper deck after row 23. All 25 of the panels of the upper deck are 36 mm apertures of the type illustrated in patent 608392 except that in rows 5 and 6 every second panel has 35mm square apertures.

In this layout the upper deck acts as a scalping deck and the panels and apertures used are designed for high impact heavy duty to remove the larger particles. Slot apertures are used in the higher velocity region of the lower deck. These slots are less likely to be blinded because of the higher velocity of the particles. In rows 10 to of the lower deck the screening apertures are more flexible and are designed to resist blinding.

Figures 4 and 5 show a second embodiment of the invention where the upper and bottom decks commence at the same point. The lower deck comprises five sections.

Stage 1 consisting of rows 1-5 is inclined at 300, stage 2 [rows 6-9] is inclined at 22.50, stage 3 [rows 10 to 13] is inclined at 150, stage 4 [rows14-17] is inclined at 7.50 and stage 5 [rows 18-22 is horizontal.

Rows 1 and 22 are solid impact panels 16. Rows 2 to 9 are panels with 22mm slot apertures while rows 10 to 20 are 22mm panels with apertures of the self cleaning type illustrated in patent 608392. Row 21 comprises removable panels to allow the separation of the ore that remains above the lower deck. Side impact panelsl 8 are io located along the sides of the panel arrays to deflect particles back onto the screening surface.

In the upper deck layout shown in figure 5, the stages are inclined in the same way as the lower deck. All of the panels of the upper deck are 36 mm apertures of the type illustrated in patent 608392 except that in rows 14 and 18 every second panel s15 has 35mm square apertures.

*oco S, In this layout the upper deck acts as a scalping deck and the panels and apertures used are designed for high impact heavy duty to remove the larger particles. Slot apertures are used in the higher velocity region of the lower deck. These slots are :o less likely to be blinded because of the higher velocity of the particles. In rows 10 to S 20 20 of the lower deck the screening apertures are more flexible and are designed to resist blinding.

The upper deck panels are made by moulding in the usual way then the leading and trailing edges of each panel are trimmed, so that the panels of the upper deck mate neatly together, to accommodate the smaller arc of the upper screening surface :25 relative to that of the lower screening surface.

From the above description it can be seen that the present invention improves the selectivity of the screening in the banana screen.

Claims

1. An ore screening apparatus having two modular screening decks, the lower deck being mounted on a support frame and the upper deck being mounted on the lower deck s wherein the leading section of the upper deck is spaced behind the leading section of the lower deck and the lower deck incorporates a ramp which abuts the leading edge of said upper deck, said ramp being inclined upwardly in the direction of travel of the ore to enable the ore flowing onto the leading section of said lower deck to be raised on to the upper deck. I0

2. A screening apparatus as claimed in claim 1 which is a banana section in which the lower deck is divided into sections each of which is inclined incrementally at a smaller angle to the horizontal than its preceding section until the sections are horizontal.

3. A screening apparatus as claimed in claims 1 or 2 in which the upper deck is supported on said lower deck by spacers adapted to seat on the side edges of said lower deck and adapted to support the panels of said upper deck

4. A screening apparatus as claimed in claims 2 or 3 wherein the material retained on the upper deck is collected separately from the material retained on the lower deck. S: 25

5. A screening apparatus as claimed in claim 4 wherein said upper deck extends o further than said lower deck so that the trailing edge of the lower deck is in advance of the trailing edge of said upper deck.

6. A screening apparatus as claimed inany one of claims 2 to 5 wherein the initial angle of inclination is 350 and there are 4 incremental changes of angle.

7. A banana section of a screening apparatus which includes a) at least two screening decks and one support frame for all the decks b) each screening deck being composed of a plurality of modular rectangular screening panels c) each screening panel including an apertured screening surface bounded by four edges of the panel (ii) at least two integral, dependent, fastening spigots on the underside of at least two edges (iii) the dependent fastening spigots optionally including a groove to accommodate a pin d) spacers between each pair of screening decks, each spacer including at its lower end at least one pin adapted to fit into the grooves of said fastening spigots of the modular panels and at its upper end at least one socket axially aligned with said pin and adapted to receive said fastening spigots of said modular panels e) the upper and lower screening decks changing in inclination from at least 200 to 00 0@SS g) wherein the leading edge of the lower deck is in advance of the leading edge "of the upper deck and a ramp is mounted on said lower deck to abut the 0 20 leading edge of the upper deck to enable the flowing ore to rise onto the upper screening surface.

8. A screening apparatus as claimed in claim 2 or 3 wherein the initial angle of inclination is 350 and there are 4 incremental changes of angle.

9. A screening apparatus as claimed in any one of claims 1 to 7 wherein said 6.4: upper deck extends further than said lower deck so that the trailing edge of the lower deck is in advance of the trailing edge of said upper deck.