Method and apparatus for solubilizing humic acid granules

Abstract

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.

We claim: 
     
         1 . An apparatus for reconstituting humic acid in solid form in aqueous form, comprising:
 a fixed-dimension tank having inlet structure for water and solid humic acids in the form of granules and/or powders, and a liquid outlet, said tank having a volume of at least about 300 gallons, and a lower section with said liquid outlet being adjacent the bottom of the lower section;   a recirculation assembly operable to withdraw a water and humic acid mixture from said liquid outlet and to recirculate the mixture to said inlet structure and into the confines of said tank, said recirculation assembly including a pump equipped with an impeller and capable of moving said mixture at a rate of at least about 125 gallons per minute from said liquid outlet to said inlet structure while reducing the size of said solid humic acid,   said recirculation assembly providing a humic acids solids residence time of at least about   2 minutes within said tank for said mixture during said recirculation; and   a motor-driven mixing shaft extending into the confines of said tank and operable to agitate said mixture during recirculation thereof by the recirculation assembly.   
     
     
         2 . The apparatus of  claim 1 , said pump rate being about 150 gallons per minute. 
     
     
         3 . The apparatus of  claim 1 , said tank having a frustoconical lower section. 
     
     
         4 . The apparatus of  claim 1 , said residence time being 2.3 minutes. 
     
     
         5 . The apparatus of  claim 1 , said volume being about 345 gallons. 
     
     
         6 . The apparatus of  claim 1 , including a discharge tube within said tank and extending downwardly from said inlet structure a distance so that said mixture is discharged below the level of liquid within the tank. 
     
     
         7 . The apparatus of  claim 1 , including a reinforced conduit between said tank outlet and the inlet of said pump, which prevents contraction of the conduit during operation of the apparatus. 
     
     
         8 . The apparatus of  claim 1 , said agitation assembly including an upright shaft and mixing elements secured to said shaft, and a drive operable to rotate the shaft at a rate of at least about 45 rpm. 
     
     
         9 . The apparatus of  claim 1 , said apparatus operable to create an aqueous solution of humic acid solids having an average size of less than about 400 microns. 
     
     
         10 . The apparatus of  claim 1 , said apparatus operable to create an aqueous solution of humic acid solids which exhibits no more than about 10% by weight sedimentation of the humic acid content of the solution for at least about one week. 
     
     
         11 . The apparatus of  claim 1 , said inlet structure including separate inlets for said solid humic acid and water, respectively.