Abstract: Improved release profiles which can, for the first time, be customized to match requirements of systems including crop nutrient uptake are realized by providing a plurality of heterogeneous particles comprised of water-soluble constituents set in a matrix of water-insoluble materials, and further providing a continuous homogeneous barrier of same, or a different water-insoluble material, juxtaposed the peripheral surface of each such heterogeneous particle. A first alternate embodiment includes forming in situ reaction products to reduce the specific gravity of such heterogeneous particles. In a second alternate embodiment, there is substituted for all, or a portion of such water-soluble material, organic media comprised primarily of composted poultry litter wherein soluble iron values remain available for substantial periods of time without incorporating or utilizing expensive conventional synthetic chelating agents.

Abstract: The present invention teaches a technique and provides for apparatus eminently useful for the econimic recovery of Fe, Zn, and S from waste galvinizer sulfuric acid and crystals of iron sulfate and zinc sulfate. The technique or method of the instant invention involves the ammoniation of the acid or a solution prepared from such crystals followed by the partial oxidation of the resulting ammoniated suspension to a point where the desired product magnetite is formed in the separated from a marketable solution of ammoniacal zinc sulfate. The effecting of the instant technique requires only a minimal amount of relatively inexpensive equipment and is simply and easily placed into practice by, for example, sparging anhydrous ammonia into a stirred tank of waste acid until the Ph is elevated to about 10. Air can be sparged through the resulting slurry to oxidize the iron in the acid. After a proper incubation period, the desired stable product, e.g.