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River sediment, fine sand / silt interface sensing.

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For a column of river sediment I want to measure fine sand / silt interface and perform analog control. So far I could not find a sensor to do this and resorted to density control for the moment. Density control (DT-1/DIC-1) SK-5A may work for recent tank collection? Any thoughts are greatly appreciated.  Attached is a concept to collect sediment with dissolved fertilizer returning to the river and any thoughts on this concept is also appreciated.

My site: Zero Wash-Away of Marshes in Louisiana, Roll Down 70 % Part 3 



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Hi Ken, welcome to ScienceForums.net.

You probably need something like a digital hydrometer.

The following link has 2 products that might suit your purposes but they are expensive (prices on the link).

WG-902122 - CPVC Submersible probe head only, operates on 5 vdc and provides 0-5 vdc linear output proportional to liquid density, with 10' PVC Cable

   WG-9033A   -        Optional analog output board (4-20 ma)



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Good to hear density may be good for this application.

I suspect it will work within a few minutes but over a long time silt can become more dense than sand, this should not be a concern. One mentioned even level might not work because settling is not an interface but a collection of large diameter rocks, sand, light sand, heavy silt then lighter silt... If true then density may be best measurement.

Even so, then heavy silt may hide in the sand and will drain out the bottom of the sediment tank. Not good for spreading silt out to the Louisiana marshes, will lose a certain percentage. Next I thought about a Hydrocyclone but variables such as pressure... affect its operation. Link. http://thermopedia.com/content/862/

Found an good test sonic meter but it cannot operate under pressure. Can get good graphs of collected particles and read sand and heavy silt levels independent. Even so, hiding silt would be a concern.

 Sonar Level System http://www.entechdesign.com/products/echosmart/

Summary: If Hydrocyclones can do almost a perfect silt/sand separation with control of pressure and flow ...etc., may have a perfect working system. I plan to propose a scaled down model and all measurements methods evaluated.

The problem is within a few months The CORPS plan to release an environmental impact statement for public review but the head officer said if I can get academia CRPA (Coastal Restoration and Protection Authority) to review my concept then they can stop proceeding with diversions into the Mississippi River. What I may propose to CRPA.


Edited by Ken123456

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Hi Ken,

I originally used hydrometers for manually testing the silt portion of gravel (with a flocculant) in a Geotechnical and Materials Testing Laboratory in the late 1970's but the Hydroclones are a good fit for your project.

Incidentally my father worked for a local sand mining operation, about 5km from where I live, that incorporated multiple very early Hydroclones into one of the the first floating processing plants connected to a floating sand mining dredge in the 1960/70's. The first separators filtered out the sand/silt and passed the denser particles to the other separators for further processing into 4 different mineral sands, Rutile, Ilmenite, Zircon and Titanium. The company my father worked for surveyed all areas before mining, grew native plants in nurseries during mining, and then restored the original profiles and regenerated and maintained the native vegetation after mining.

Here's a quote from Biography of Joe Pinter, who emigrated to Australia just before WWII and developed the original 'conical spinning separator' concept for mineral sand separation during WWII,  and who also founded the company my father worked for in 1946. The older separators/hydroclones were lined with hardwood and were held in place with bolted metal bands that had to be replaced regularly as it wore out. This wood was excellent for recycling as unique and unusual benches, chairs, tables and other household furniture.

Pinter designed a separator to produce pure rutile from a concentrate of rutile and ilmenite, from ore obtained from Zircon-Rutile Ltd, Byron Bay. This first commercial production of separated rutile in Australia met a strong wartime demand from firms in Australia and Britain. Seeking new sources of rutile, he then devised an electrostatic machine to separate rutile and zircon and used other suppliers, Mineral Deposits Syndicate in Queensland and Coffs Harbour Minerals Syndicate.


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