The size range from 10-40mm will not generate significant dust ■

CDI designs chutes to reduce degradation and dust. We apply our design tolls DEM and CFD to qualify and quantify these conditions as well as reduce or eliminate spillage, material centering, power, belt wear and many other factors.

Your request has no simple answer because of the complexity of the model. Particle size distribution, density, moisture content, delivery specifications, belt geometries, and chute design are required to build a model and subject it to analysis. Then we can quantify the benefits of one design verses another.

You need to quantify the expected gas velocity and particle suspension time by size in the gas field. THis is not a simple formula.

A dust reduction of 10:1 or more can be achieved and maybe guaranteed by prudent chute design. We are able to lend assistance on such projects.

Lawrence Nordell

Conveyor Dynamics, Inc.

www.conveyor-dynamics.com ■

How will this Wollongong concept equate to a real world transfer and its dust emissions?

I am baffled on how the experiment will identify the fugitive dust by measuring fines fraction after the drop. Once the material drops and dust is expelled, it immediately begins to fall back on the material heap. Where does the liberated dust go? How long after the drop is the measurement taken?

Putting it through a sieve analysis will, on each occasion, liberate dust and generate degradation and more dust. Standard sieves (635 mesh or 20 microns) cannot classify to the necessary size fraction for dust measurement.

A typical dust measurement is made by electrical (Coulter) or laser (Malvern, PSM, et al) to obtain the particle count and size fractions in the 0.5 to 10.0 micron range. This is the dangerous or hazardous respiral range (MSHA is 0.5 to 5.0 microns).

Hopefully, your/Wollongong have conquered the above difficulties and you /Wollongong will share this wisdom. ■

Matt,

I agree with you. I suffer from loss of focus.

However, although it is not clear on what is "dust or fines", if you sieve it you break it (coal and lime) to varying degrees. Thus, what are you truly measuring? In order to obtain meaningful results, you need to back engineer to the pre-broken sample. This requires repeated sieving to obtain the sieve breakage and estimate the native sample in the unbroken state.

I had to save what's left of face. ■