Short horizontal screw conveyor? ■

I second what designer has said as it is probably the only viable option due to the limitations of you installation.

The bigger design problem will be installing decking and a walkway/ladder set up for maintenance and repair. ■

Can not beleive that a standby bucket elevator is required...why??

Vibrating chute should do...could also add an air shock blaster/blower.

Make chute from Stainless steel....

Cheers

James ■

This would seem to be a long standing problem from the date of 20.04.2001 shown on the drawing. However the recent posting indicates it is still a live topic, so merits attention.

A vibrated chute would appear to be an attractive option at first sight, but a closer examination of the transfer requirements shows that the need to collect from the width of the belt constrains the top end of the chute. The requirement to change flow direction and enter the second bucket elevator at least at the top of its own infeed chute determines the height of the lower end of a transfer chute. The inclination between these two points is significantly less steep than the provision chute indicated in the drawing. A second feature against a vibrated chute is that it offers a barrier to through flow, so would have to be re-positions for each change over. Apart from limited access, this would prohibit an immediate emergency divergence should the original elevator fail.

I support the views that the best answer is a short transfer screw but would add that needs a few special features to suit the site and duty. Essentially, it should pick up at the highest level from the belt discharge, but not interfere with the normal flow route into the first elevator. A probe detecting a back up in the elevator feed chute will start the transfer screw so that, when the material level reaches the screw, it is immediately taken to the second elevator. Limited space in the pit from the second bucket elevator to the far wall dictates that the transfer screw is cantilevered in double bearings from the more 'open' end of the pit. This ensures that there is no service access required other than at the more open drive end. A large diameter, short pitch ribbon screw will keep the shaft away form the flow stream and avoid cohesive build up that is prone to occur in full bladed flights. The feed chute of the second elevator will only be narrow but can be flared to affect good collection as the material runs out of the end of the casing unencumbered by extended shaft or end bearing. It may be prudent to equip the first elevator with a cut off slide down the entry face so that it may be cleaned out without a flood feed during continued operation. This could be included in a package replacement for the existing infeed hopper and include everything from the belt conveyor discharge to the face plates for both bucket elevators

This is the type of special design application is which Ajax Equipment excels to give an individual service. Their 'Lynflow' ribbon construction is especially geared to deal with cohesive products. A more details proposal would be supplied from tech@ajax.co.uk on provision of particulars of the bucket elevator intake and belt conveyor. ■

The other respondents have already given numerous suggestions. You may also think of following alternative :

1) Flat belt conveyor with skirt board for full length and pulleys could be around 220 or 250 mm. This conveyor depth overall could be around 500 to 600 mm. Adjoining to tail pulley there would be one bypass chute. This assembly is to be made traveling type say fitted with 150 mm diameter wheel. Its travel / shifting direction will be along the displacement line of discharge. When you want to feed to an existing elevator, position it such that the present chute discharges in to the bypass section. When you want to convey to the standby elevator shift it by say 300 to 400 mm and it will discharge in to standby elevator.

2) You can also use vibrating conveyor instead of belt conveyor, and mounted as above.

3) In aforesaid arrangements, you are not disturbing any existing chute except that you are removing a segment of appropriate depth and that space is utilized by the aforesaid compact item (machine).

You may think of the aforesaid arrangement in context of your actual situation. One can also think of using track type chain conveyor of very compact type, however, this is not advised considering hygroscopic nature of gypsum.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25871916 ■