Method and apparatus for solubilizing humic acid granules
Improved methods and apparatus ( 10, 74 ) for the solubilization of initially solid humic acids include a large-volume mixing/agitation tank ( 12, 76 ) for water and solid humic acids, together a recirculation assembly ( 14, 78 ) for continuously recirculating the water/humic acids mixture while reducing the size of the humic acids. Properly used, the apparatus ( 10, 74 ) is capable of providing relatively stable, solubilized humic acid solutions or dispersions.
1. A method of reconstituting humic acid in solid form as an aqueous solution, comprising the steps of:
forming a mixture comprising water and naturally occurring, solid humic acid in a fixed-dimension tank having inlet structure and an outlet, a fixed volume of at least about 300 gallons, and a lower section with said outlet being adjacent the bottom of the lower section,
said mixture-forming step comprising the steps of introducing solid, naturally occurring humic acid in the form of granules and/or powders through said inlet structure and into the confines of said tank, and also introducing water through the inlet structure into the confines of said tank;
forming said aqueous solution by continuously recirculating said mixture from said outlet and to said inlet structure using a recirculation assembly, and agitating said mixture using a motor-driven mixing shaft extending into the confines of the tank, said recirculation assembly including a pump equipped with an impeller and capable of recirculating said mixture at a rate of at least about 125 gallons per minute from said outlet to said inlet structure, and
allowing said mixture to reside within said tank for a residence time of at least about 2 minutes during said recirculation step; and
recovering a solution of humic acid which resists undue sedimentation for at least about 3 days.
2. The method of claim 1 , said pump rate being about 150 gallons per minute.
3. The method of claim 1 , said residence time being 2.3 minutes.
4. The method of claim 1 , said volume being about 345 gallons.
5. The method of claim 1 , including the step of discharging said mixture within said tank at a point so that said mixture is discharged below the level of liquid within the tank.
6. The method of claim 1 , including the step of recirculating said mixture from said tank outlet to the inlet of said pump using a reinforced conduit which prevents contraction of the conduit during operation of the apparatus.
7. The method of claim 1 , including the step of rotating said shaft at a rate of at least about 45 rpm.
8. The method of claim 1 , said solution having humic acid solids with an average size of less than about 400 microns.
9. The method of claim 1 , said aqueous solution exhibiting no more than about 10% by weight sedimentation of the humic acid content of the dispersion for at least about one week.
10. The method of claim 1 , said mixture consisting essentially of water and naturally occurring solid humic acid.
11. The method of claim 1 , said inlet structure including separate inlets for said solid humic acid and water, respectively.