Ref:conveying machine, A.O. Spivakovsky and V.K. Dyachkov

N(kW)=(Q(t/h)/360)(H+Lw)

where:

H(m): vertically height

L(m): the length of machine

w: total coefficient of resistance ■

i am at a loss to understand how the power could vary inversely with the convertor length and discharge height, so the bling use of formulae without understanding is a route to disaster. No published data will provide the information requested as the sensitive feed and material conditions are not available. Capacity falls off rapidly above 20 degrees inclination in Gravity mode conveying. I would recomend that some tests were conducted or a specialist consulted for this potentially awkward applications where there are many other factors to be taken into consideration. ■

Hello,

You are handling concrete i.e. mixture of stone pieces, sand, cement and water. You have mentioned it is in diluted condition which implies water proportion more than the water just required for wetting this composition.

Screw conveyor general literature do not list this material about its factors for filling, power, etc., due to influence by water content. Therefore, we have to deduce these values by comparison of this material (as mentioned by you) to the listed materials.

Regarding fill factor, widely used materials list (about two hundred), have fill factor ranging from 15% to 45%. It seems this material may have fill factor around 25%. So using the fill factor as 15% will be quite safe for sizing the screw conveyor, or you can take this as 22% (mean of 15% and 30%) if you are confident about it.

Regarding factor for power, you can take it as for limestone crushed (dry). The friction losses for sufficiently wet material will be less compared to dry limestone, due to water lubrication, and thereby power calculation based on dry limestone will be on safer side.

The power so calculated is likely to be for horizontal conveying. You need to add for material lift power. One formula for this is as below:

Lift power hp = (Capacity British ton per hour) x (Conveyor incline length feet) x (Sine inclination) ÷ 884.One can also convert this formula in MKS units.

I have not dealt with this material for screw conveyor, and accordingly information can be considered of general nature. Those who are dealing with this material, will have more specific information.

Regarding construction feature, short pitch screw, regular trough and shroud cover is adequate for 24 deg incline conveyor. If you like and afford, you can opt for tubular construction, which is generally for steeper inclination.

Regards,

Ishwar G. Mulani

Author of Book: Engineering Science And Application Design For Belt Conveyors (new print November, 2012)

Author of Book: Belt Feeder Design And Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Pune, India.

Tel.: 0091 (0)20 25871916

Email: conveyor.ishwar.mulani@gmail.com

Website: www.conveyor.ishwarmulani.com ■

Methinks the thread is not all it seems. Why would anyone want to dilute concrete and thereby make it useless? That's why such a material isn't mentioned in any texts!

Perhaps the guy is talking about demolished hardcore. Kindly clarify: because if such is the case then maybe a large screw conveyor is needed.

I am intrigued that a power and capacity have been decided without quantitative reference to the solids/liquid ratio; lump size; abrasiveness; internal machine clearances etc.

Regarding the 24^o inclination: won't most of the dilutant try to run downhill?

Often enough in these forums very little useful or relevant information is provided with the question; the original design input is often highly suspect and then, when respondents offer some advice, extra spurious information appears in the hope of covering wonky tracks by killing off the thread or vainly trying to embarrass the advisers. ■