well,when working dredge/highbanker cleanups,this has already been accomplished for the most part.high pressure blaster nozzle,hopper spray bars do most of this.with samples now,these are often mostly clay/root mixtures.easiest way,throw each sample bucket,singly of course,into my marlex drum cement mixer.add a few rocks,turns it into a slurry.stop mixer,let it settle out.then slowly rinse till overflow clear.put sample #1 back in clean bucket,while #2 being done,#1 in bucket stripped of oils,lye,muriatic,or even simply green.after carefully rinsing that,time to classify.(screen)1/2 inch,1/4 inch,12 mesh,20,30,50.70 and100 if feasible.especially if the sample came off my impact attrition mill.that always goes at least 100 fine.yeah theres that clay be gone stuff,but would need a drum of it..others have had success drying the clay stuff out,then pulverising it.sounds like an option,time permitting.if only a small sample or two, just a bucket plus elbow grease.