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EP-4353703-B1 - AGGLOMERATED DISPERSIBLE GRANULES INCLUDING ACTIVATED ALUMINA, AND METHODS FOR AMENDING SOIL

EP4353703B1EP 4353703 B1EP4353703 B1EP 4353703B1EP-4353703-B1

Inventors

  • SWISHER, Hunter R.
  • WALTZ, Aaron

Dates

Publication Date
20260506
Application Date
20210309

Claims (15)

  1. Agglomerated dispersible granules, comprising: 10-80%, by weight, activated alumina particles having: a porous structure; and a plurality of electrically-charged binding sites disposed within the porous structure; and 10-80%, by weight, phosphate particles, and 10-50%, by weight, water-soluble binder, wherein the activated alumina particles and the phosphate particles are present in the agglomerated dispersible granules as distinct phases agglomerated together.
  2. The agglomerated dispersible granules of claim 1, wherein the activated alumina particles are free of phosphate disposed within the porous structure.
  3. The agglomerated dispersible granules of claim 1, wherein the activated alumina particles and the phosphate particles are homogenously distributed in the agglomerated dispersible granules.
  4. The agglomerated dispersible granules of claim 1, having a weight ratio of alumina to phosphate of 10:1 to 1:10.
  5. The agglomerated dispersible granules of claim 1, further including additional nutrient particles present as distinct phases and agglomerated with the activated alumina particles and the phosphate particles, preferably the additional nutrient particles includes at least one nutrient selected from the group consisting of bioavailable species of molybdenum, selenium, zinc, copper, cobalt, iron, nickel, manganese, vanadium, calcium, potassium, sulfur, chlorine, silicon, magnesium, sodium, nitrogen, boron, and combinations thereof.
  6. The agglomerated dispersible granules of claim 1, wherein the activated alumina particles are free of the at least one nutrient within the porous structure.
  7. The agglomerated dispersible granules of claim 1, wherein the agglomerated dispersible granules are coated with an additional nutrient layer, the additional nutrient layer including at least one nutrient selected from the group consisting of bioavailable species of molybdenum, selenium, zinc, copper, cobalt, iron, nickel, manganese, vanadium, calcium, potassium, sulfur, chlorine, silicon, magnesium, sodium, nitrogen, boron, and combinations thereof.
  8. The agglomerated dispersible granules of claim 1, further including pesticide particles present as distinct phases and agglomerated with the activated alumina particles and the phosphate particles.
  9. The agglomerated dispersible granules of claim 1, wherein the agglomerated dispersible granules are coated with a pesticide layer.
  10. The agglomerated dispersible granules of claim 1, further including biological additive particles present as distinct phases and agglomerated with the activated alumina particles and the phosphate particles.
  11. The agglomerated dispersible granules of claim 10, wherein the biological additive particles include at least one additive selected from the group consisting of humics, fulvics, living microbes, microbial metabolites, plant extracts, exogenous plant hormones, and combinations thereof.
  12. The agglomerated dispersible granules of claim 1, wherein the agglomerated dispersible granules are coated with a biological additive layer, the biological additive layer including at least one additive selected from the group consisting of humics, fulvics, living microbes, microbial metabolites, plant extracts, exogenous plant hormones, and combinations thereof.
  13. The agglomerated dispersible granules of claim 1, further including at least one of a water-soluble binder, a suspension agent, or an emulsifying agent.
  14. The agglomerated dispersible granules of claim 1, wherein the activated alumina particles are less than 200 µm in size as measured by largest particle dimension.
  15. A method for amending soil with buffered phosphorus, comprising: physically blending activated alumina particles with phosphate particles, the activated alumina particles having: a porous structure; and a plurality of electrically-charged binding sites disposed within the porous structure; and then agglomerating the alumina particles with the phosphate particles to form agglomerated dispersible granules according to any of claims 1 to 14; and applying the agglomerated dispersible granules to soil, preferably the agglomerated dispersible granules are applied to the soil without tilling the soil, wherein the activated alumina particles and the phosphate particles are present in the agglomerated dispersible granules as distinct phases agglomerated together and the activated alumina particles are free of phosphate disposed within the porous structure when applied to the soil.

Description

RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Prov. App. No. 62/987,461, filed March 10, 2020, entitled "Improved Methods for Making and Applying Buffered Phosphorus". FIELD OF THE INVENTION This application is directed to agglomerated dispersible granules, methods for amending soil, and activated alumina suspensions. In particular, this application is directed to agglomerated dispersible granules having alumina particles and phosphate particles present as distinct phases, methods for amending soil with buffered phosphorus in the form of the agglomerated dispersible granules, and activated alumina suspensions wherein the activated alumina particles constitute a dispersed phase suspended in a continuous phase. BACKGROUND OF THE INVENTION Phosphorus is a key nutrient for plant growth. Metal oxides, including activated alumina, kaolin, bauxite, iron oxide, calcium oxide, and magnesium oxide, have been used as a buffer to apply phosphorus as a fertilizer. Activated alumina, in particular, has been used in buffered-release activated alumina and phosphorus soil amendments ("BRAAPSA"). Traditionally, BRAAPSA has been made by loading liquid phosphorus (e.g., phosphoric acid) onto activated alumina to create a BRAAPSA which may be physically put into the soil as a soil amendment for plants. Lynch et al. in U.S. Patent No. 6,287,357 describe a method for forming BRAAPSA, which method is dependent on a phosphorous source being reversibly bound to acid-activated alumina prior to soil application. BRAAPSA has significantly reduced unwanted phosphorus loss due to leaching which may cause ground water contamination as well as increasing the amount of phosphorus required for soil applications. Additionally, BRAAPSA may positively improve plant growth for various plant species (e.g., by improving root growth, etc.) because the buffered-release mechanism of BRAAPSA provides a chemical gradient release of nutrients. In contrast, existing coated fertilizer technologies rely upon environmental conditions and thus lead to more phosphorus being leached (i.e., lost) into the ground water. CA 2 384 966 A1 discloses a process for the production of granules of a phosphorus doped activated alumina comprising the steps of a) compacting a mixture of an aluminium hydroxide and a phosphorus source, b) size reducing the compacted material, c) activating the size reduced material at a temperature of at least 300 °C and, optionally, d) classifying the obtained granules. Activating a metal oxide may be done in a variety of ways. Activated alumina adsorbents are often produced by agglomerating and heat processing (i.e., calcining) aluminum trihydrate powder. Spherical alumina is formed, then crushed (e.g., mechanical fracturing), then followed by a screening process to produce granular activated alumina of various sizes (often referred to as mesh sizes due to the size of the mesh sieves used to separate particles based on size). The adsorptive capacity of an activated metal oxide such as activated alumina is determined in large part by the surface area. Because of the porous nature of activated alumina, a majority of the surface area exists in the pore spaces which are produced by the calcination process (i.e., a more porous compound has more surface area than a similarly-sized particle with less porous surface). The capacity for chemi-adsorbing orthophosphate is high compared to other plant nutrients such as nitrogen and potassium due to the high anionic exchange capacity of the material, making activated alumina a preferable substrate for buffering the release of phosphate fertilizers. However, a variety of metal oxides may be activated and used in a similar manner. Although applying to the soil a BRAAPSA soil amendment is somewhat more efficient than conventional methods of applying phosphorus-containing fertilizer directly to the soil (i.e., either directly or via a coated fertilizer), BRAAPSA may be difficult, expensive, and time-consuming to make. The process of loading a granular activated alumina with a liquid source of phosphorus (e.g., phosphoric acid) does have problems. By way of example, liquid phosphorus compounds (e.g., phosphoric acid, orthophosphoric acid, phosphoric (V) acid) are acids which require careful handling and use of personal protective equipment because acids such as phosphoric acid may cause severe irritation of the skin and eyes. Additionally, liquid phosphorus (e.g., phosphoric acid) requires specific equipment to handle because equipment may be degraded from contact with acid. Additionally, activated alumina has insoluble characteristics which can give it limited application opportunities. For example, activated alumina must be physically and/or mechanically incorporated into the soil (e.g., applied to small holes of a certain depth). Physical and/or mechanical application to the soil may prove to be a time-consuming and laborious process for farmers. Additionally, physical an