| 摘要 |
Peats, mucks, soils, anaerobic sludges, lignites and other humus materials containing humic substances are slurried in the natural wet state with additional water at low pH to free humic acid from salts it may have formed in the natural state and to disperse the humic acid as a fine suspension in the water. The resulting slurry is then screened to remove coarse material such as stones, fibers and cellulosic materials that may be present, and the liquid phase compromising a dispersion of humic acid is settled or otherwise treated to remove heavy inorganic fines if present. The dispersion is then filtered to yield a relatively pure and dry filter cake, comprising crude humic acid. This product may be converted to soluble humate salts by adding a solubilizing agent such as sodium hydroxide, separating residual insolubles and drying the concentrated solution. In the alternative, the solution before drying may be converted to relatively pure humic acid by acidifying the solution, separating and drying the insoluble humic acid. The same solution may be converted to humates of limited solubility by reaction with suitable metal salts, and again separating and drying the product.
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