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Lea Dodds writes to the sowacs list: ===8<============== Reply from Delta-T (manufacturer) The measurement of water content in contaminated land is problematical for a number of reasons mainly associated with conductivity. If this is present either in the soil or pore water, conventional techniques using TDR or FDR probes will be prone to error. The ability to measure and factor out conductivity is a prime consideration when choosing a probe for this application. The WET Sensor from Delta-T Devices is able to deliver soil moisture content and pore water conductivity independently. An added bonus is that the conductivity reading gives a good indication of the level of contamination in the land. The downside is that currently the WET Sensor is not loggable - it is comes with a 2m cable for connection to an HH2 Moisture Meter for data readout (users can store readings for later download). Also, although we say the WET Sensor is good value, even a well funded researcher wouldn't want to call them disposable! So the WET Sensor would be fine for spot measurements, and could be buried, but a different technology would be needed for wireless measurements at low cost. Lea Dodds -----Original Message----- From: Bruce at Findasensor [mailto:contact@findasensor.com] Sent: 12 March 2003 08:33 To: brooz@pobox.com Subject: SOWACS: Solids Content of Mining Waste Angela Beveridge writes to the sowacs list: ===8<============== We are currently working on a project which involves adding chemicals to various mineral processing waste streams to make them de-water more quickly. Faster dewatering means better water recovery which can go back to the mine, it also means that the area can be re-vegetated more quickly since trucks can access the area more quickly. Also the same footprint can be used to deposit more waste if dewatering is accelerated. Do you know of any apparatus that can be placed into this sort of environmentand will give an indication of decreasing water content (typically in the range of roughly 30%-70%) I would need the instrument to be precise enough to distinguish the difference between say a 50% solids content and 52% solids content. I guess the accuracy of the reading would be up to me to do some sort of calibration?? One of the problems with our project is access to the working area. Mine disposal is often like thick mud, and it's not possible towalk on the disposal area in order to take a sample,until it has dried a bit. Do youknow of any remote signal systems - i.e. the detector can be held a few metres away from thesensor. Initially I was hoping to find some almost disposablesensors that could be buried under the incoming disposal mud, but would still give off a reading which could be picked up by someone standing close by. Have been in touch with Sentek briefly, but it looks as if what they have to offer would cost in excess of $20,000 and isn't really portable. Do you know of anyone else doing work in this area? Thanks in anticipation of a response. Rgds Angela Beveridge Angela.Beveridge@cibasc.com Senior Development Chemist Ciba Specialty Chemicals 6-8 Donaldson Rd Wyong North NSW 2259 Tel 61 2 4350 3200 www.cibasc.com ===8<============== NOTE: To get off this list, send an email to list@sowacs.com with the subject line: unsubscribe_sowacs For full instructions see this page: <http://www.sowacs.com/subscribe/index.html>