Methods for manufacturing phosphate-containing fertilizers with in SITU activated bauxite

Abstract

A method for the manufacture of a phosphate-based fertilizer is disclosed including: (a) exposing a bauxite to an acid to form a mixture, the mixture including a phosphate source; (b) activating the bauxite in situ by removal of crystalline water from the bauxite; (c) binding phosphate from the phosphate source to the bauxite; and (d) recycling the mixture in a mixer to form the phosphate-based fertilizer as a plurality of granules, wherein there is an increased throughput of at least 5% relative to a comparative fertilizer production process that is an otherwise identical fertilizer production process lacking in situ activation of the bauxite, and the increased throughput is independent of recycle:product ratio.

Description

Atorney Docket No.: 40688-0015-PCTMETHODS FOR MANUFACTURING PHOSPHATE-CONTAINING FERTILIZERS WITH IN SITU ACTIVATED BAUXITE RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 552,226, filed February 12, 2024, entitled “Methods for Manufacturing Phosphate-Containing Fertilizers,” and U.S. Provisional Patent Application No. 63 / 556,582, filed February 22, 2024, entitled “Methods for Manufacturing Phosphate-Containing Fertilizers,” which are hereby incorporated by reference in their entirety.FIELD OF THE INVENTION

[0002] This application is directed to methods of manufacturing phosphorous containing fertilizers with enhanced efficiency. In particular, this application is directed to methods maintaining a high production rate independent of recycle:product ratio, promoting greater flexibility with process conditions such as volume of material in the system, and size distribution out of the dryer.BACKGROUND OF THE INVENTION

[0003] While aluminum oxide materials may be produced from a variety of raw materials, aluminum oxide materials are most commonly derived from bauxite ore for production at a commercial scale. The aluminum oxide materials produced from bauxite sources may be manufactured through a variety of methods, yet nearly all involve some form of calcination and / or chemical activation, especially at commercial scale. In the conventional process, bauxite ore is typically dried to a desired moisture content and crushed or milled to desired size. Then, the fine bauxite powder is modified by the Bayer Process, which involves pressure heating between 150— 200 °C in caustic soda. Through filtering, bauxite residue (also referred to as red mud, red sludge, bauxite tailings, or alumina refinery residues) is removed and sodium aluminate remains. The sodium aluminate is then treated with aluminum hydroxide and water, which promotes the removal of sodium hydroxide, and the resulting product is aluminum trihydrate. For commercial production, the aluminum trihydrate is generally calcined at defined temperatures and durations to achieve proper surface area and porosity characteristics for the desired application. The calcinationAtorney Docket No.: 40688-0015-PCTprocedure promotes expulsion of crystalline water and leads to atomic rearrangement. The activated alumina with highest surface area is usually obtained with calcination temperatures between 250-550 °C.

[0004] Besides traditional calcination procedures, some level of activation of alumina trihydrate may occur via acid treatment, including partial acid dissolution and subsequent precipitation, which leads to a high porosity pseudoboehmite structure. Though not often performed at commercial scale, acid treatments and calcination procedures may be performed simultaneously with often synergistic activation impacts (e.g., acid treatment lowers the necessary calcination temperature to achieve desired characteristics).

[0005] Bauxite, not yet converted to aluminum trihydrate, may also be activated via temperature and pH treatments without undergoing the purifying Bayer Process. However, such activated bauxites contain considerable amounts of many other components besides aluminum oxide / oxyhydroxide / hydrate materials. For this reason, most applications (e.g., catalysts and water treatments) opt for activated alumina materials over activated bauxites, despite properly activated bauxites being able to achieve similar surface area and porosity characteristics with less energy input and reduced environmental waste.

[0006] It has been well-established that alumina-based materials may beneficially promote sorption of orthophosphates in agricultural soils, alleviating nutrient runoff effects while still providing sufficient crop fertility. Additional benefits have been observed when the alumina-based materials are pre-treated with phosphoric acid. This treatment effectively leads to “loading” of the alumina surface with adsorbed orthophosphate, and the loaded material may serve as the sole source of added phosphate to soils. This treatment essentially eliminates the need for the alumina amendment to capture phosphates in the soil environment and may lead to greater buffering capacity in the soils.

[0007] In agricultural applications, soil amendments and fertilizers are often derived from various ores with high concentrations of desired mineral components. Since purification and filtration practices are not always performed to minimize production costs, agricultural standard practice already supports inclusion of undesired or inert ore components in plant fertility programs. Provided that the inactive filler materials do not contain high levels of certain heavy metals orAtorney Docket No.: 40688-0015-PCTradioactive materials, these inactive materials are well-tolerated by crop systems.

[0008] Many fertilizers are formulated into granules to improve the ability to spread the nutrients over large areas. Granulation processes typically rely on either agglomeration or accretion to achieve size growth. In large-scale granule production, drum granulators are most commonly used as they may be engineered to handle both binder-based agglomeration and chemical reaction-based accretion processes. Most often, excess moisture in the granules is removed via rotary dryer as part of the production process.

[0009] Globally, 90% of phosphoric acid produced is utilized in some capacity as a fertilizer (38% diammonium phosphate (“DAP”), 29% monoammonium phosphate (“MAP”), 8% triple superphosphate (“TSP”), 15% other fertilizers such as single superphosphate (“SSP”) and double superphosphate (“DSP”)). In the United States, MAP usage exceeds that of DAP, and its market share is expanding. Nearly all phosphoric acid for fertilizer applications is produced via a multi-step process that involves the mining of phosphate rock, beneficiation, and a concentrated sulfuric acid treatment. Following the production of phosphoric acid of suitable purity, the phosphoric acid may be subjected to a variety of other processing treatments to produce liquid fertilizers, solid fertilizers, animal feed products, and more.

[0010] While the production processes differ for each solid fertilizer type (e.g., MAP, DAP, granulated TSP, granulated DSP, and granulated SSP), several process similarities exist as well. For example, with phosphate ammoniation-granulation plants (those that produce MAP and DAP), the only significant difference is the input ratio of ammonia to phosphoric acid. Otherwise, all equipment and instrumentation for MAP and DAP production may essentially remain the same in the two processes. While manufacturing processes may also differ between locales, the essential process is largely standardized across the industry. Indeed, a majority of all ammoniationgranulation plants in the U.S. use a specific type of rotary drum mixer that was developed and patented by the Tennessee Valley Authority (“TV A”), either including a pre-neutralization step or a pipe cross reactor. The basic rotary drum ammoniator-granulator is designed with an open-end rotary cylinder which houses the rolling bed of recycled solids.

[0011] In the TVA phosphoric acid ammoniation-granulation process, phosphoric acid is mixed with about 93 wt% sulfuric acid in an acid surge tank (see FIG. 1). The mixed acids areAttorney Docket No.: 40688-0015-PCTthen fed into a brick-lined acid reactor, where they are partially neutralized with liquid or gaseous anhydrous ammonia. About 70 wt% of all ammonia is introduced into this reactor vessel, producing a slurry of ammonium phosphate and about 22 wt% water that is transported into the rotary drum ammoniator- granulator and distributed along the bed. The remaining about 30 wt% of ammonia is sparged from underneath the slurry. Agglomeration occurs in the rotating drum and is terminated in the dryer. The moist granules then pass through the rotary concurrent dryer before being brought to ambient temperatures in the cooler.

[0012] Ammoniation granulation may also be performed with additional acids besides phosphoric acid, including sulfuric acid and nitric acid, producing ammonium sulfate and ammonium nitrate, respectively.

[0013] In contrast, for granulated TSP, the majority is produced with the Dorr-Oliver granulation process (see FIG. 3), which involves acid-controlled phosphoric acid and ground phosphate rock being fed into a reactor, with the ground rock and phosphoric acid slurry being fed into a granulator and subsequently dried in a generally continuous fashion. Granulated SSP follows a similar process; however, the ground phosphate rock is reacted with sulfuric acid in lieu of phosphoric acid. Granulated nitrophosphate may follow a similar process; ground phosphate rock is reacted with nitric acid in lieu of phosphoric acid.BRIEF DESCRIPTION OF THE INVENTION

[0014] In one exemplary embodiment, a method for the manufacture of a phosphate-based fertilizer includes: (a) exposing a bauxite to an acid to form a mixture, the mixture including a phosphate source; (b) activating the bauxite in situ by removal of crystalline water from the bauxite; (c) binding phosphate from the phosphate source to the bauxite; and (d) recycling the mixture in a mixer to form the phosphate-based fertilizer as a plurality of granules, wherein there is an increased throughput of at least 5% relative to a comparative fertilizer production process that is an otherwise identical fertilizer production process lacking in situ activation of the bauxite, and the increased throughput is independent of recycle:product ratio.

[0015] Further aspects of the subject matter of the present disclosure are provided by the following clauses:Atorney Docket No.: 40688-0015-PCT

[0016] A method for the manufacture of a phosphate-based fertilizer includes: (a) exposing a bauxite to an acid to form a mixture, the mixture including a phosphate source; (b) activating the bauxite in situ by removal of crystalline water from the bauxite; (c) binding phosphate from the phosphate source to the bauxite; and (d) recycling the mixture in a mixer to form the phosphate-based fertilizer as a plurality of granules, wherein there is an increased throughput of at least 5% relative to a comparative fertilizer production process that is an otherwise identical fertilizer production process lacking in situ activation of the bauxite, and the increased throughput is independent of recycleiproduct ratio.

[0017] The method of any preceding clause, wherein the activating of the bauxite in situ includes an activation technique selected from the group consisting of calcining the bauxite in a dryer burner above 375 °C, acidifying the mixture to a pH below 5.5, increasing water content of the mixture during granulation to at least about 13.5 wt%, steaming the mixture during granulation, and combinations thereof.

[0018] The method of any preceding clause, wherein acidifying the mixture to a pH below 5.5 includes adding a strong acid to the mixture.

[0019] The method of any preceding clause, wherein increasing the water content of the mixture during granulation to at least about 13.5 wt% increases the increased throughput of at least 5% increases to at least 7%.

[0020] The method of any preceding clause, wherein the phosphate source is the acid.

[0021] The method of any preceding clause, wherein binding the phosphate to the bauxite includes chemisorbing the phosphate to the bauxite.

[0022] The method of any preceding clause, wherein the phosphate-based fertilizer is selected from the group selected from single super phosphate, double super phosphate, triple super phosphate, or combinations thereof.

[0023] The method of any preceding clause, wherein the acid is selected from the group consisting of phosphoric, sulfuric, nitric, boric acid, and combinations thereof.

[0024] The method of any preceding clause, wherein the phosphate-based fertilizer is aAttorney Docket No.: 40688-0015-PCTnitrogen-phosphorous-potassium or nitrogen-phosphorous fertilizer, the acid includes phosphoric acid and exposing the bauxite to the acid to form the mixture further includes exposing the bauxite to a base along with the acid to form the mixture.

[0025] The method of any preceding clause, wherein the phosphate-based fertilizer is selected from the group consisting of monoammonium phosphate, diammonium phosphate, nitrophosphate, or combinations thereof.

[0026] The method of any preceding clause, wherein the nitrogen-phosphorous-potassium or nitrogen-phosphorous fertilizer has anN:P ratio of between 0.5:1 to 2.5:1.

[0027] The method of any preceding clause, wherein the nitrogen-phosphorous-potassium or nitrogen-phosphorous fertilizer has an N:P ratio of about 0.9: 1

[0028] The method of any preceding clause, wherein the acid and the base are added into a pre-neutralizer, the pre-neutralizer having an N:P ratio from about 0.4:1 to about 0.8:1, and the nitrogen-phosphorous-potassium or nitrogen-phosphorous fertilizer has an N:P ratio from about 0.7:1 to about 1.2:1.

[0029] The method of any preceding clause, wherein the base is ammonia.

[0030] The method of any preceding clause, wherein the phosphoric acid mixed with the bauxite to form the mixture is at least 10% less than the comparative fertilizer production process lacking in situ activation of the bauxite.

[0031] The method of any preceding clause, wherein the phosphate-based fertilizer has increased citrate-soluble P2O5 relative to the comparative fertilizer production process.

[0032] The method of any preceding clause, wherein the phosphate-based fertilizer has a lower viscosity relative to the comparative phosphate-based fertilizer produced by the comparative fertilizer production process.

[0033] The method of any preceding clause, wherein the bauxite has an initial moisture content prior to activation of about 12 wt% to about 19 wt%.Atorney Docket No.: 40688-0015-PCT

[0034] The method of any preceding clause, wherein shutdown events are reduced by at least about one-third relative to the comparative fertilizer production process.

[0035] The method of any preceding clause, wherein the method has reduced attrition of the plurality of granules relative to the comparative fertilizer production process.

[0036] The method of any preceding clause, wherein the bauxite is a pre-activated bauxite prior to the further in situ activating of the bauxite by the removal of crystalline water from the bauxite.

[0037] The method of any preceding clause, wherein recycling the mixture in the mixer exerts a force of impact of a granule of the mixture on the mixer sufficient to sever loosely held material on that granule such that granule size is increased through accretion.

[0038] The method of any preceding clause, wherein the force of impact of the granule of the mixture on the mixer is generated by a velocity of impact of about 6 m / s to about 9 m / s.BRIEF DESCRIPTION OF THE DRAWINGS

[0039] These and other features, aspects, and advantages of the present subject matter will become better understood when the following detailed description is read with reference to the accompanying drawings in which:

[0040] FIG. 1 is a production schematic for MAP and DAP from phosphoric acid when using a pre-neutralization step, as known and presently used.

[0041] FIG. 2 is a production schematic for coherent dispersible activated bauxite granules, according to an embodiment of the present disclosure.

[0042] FIG. 3 is a production schematic for granulated TSP and granulated SSP from at least one of phosphoric acid or sulfuric acid and phosphate rock, as known and presently used. A production schematic for nitrophosphate would be identical other than replacing sulfuric acid or phosphoric acid with nitric acid.

[0043] FIG. 4 is a production schematic for coherent dispersible activated bauxite granules,Atorney Docket No.: 40688-0015-PCTaccording to an embodiment of the present disclosure.

[0044] FIG. 5 is a cross-sectional schematic view of a dispersible activated bauxite granule, according to an embodiment of the present disclosure.

[0045] FIG.6 is a graph comparing available P2O5 predicted from inputs versus experimentally determined P2O5 in granules, according to an embodiment of the present disclosure. The slope statistically differs from m = 1 , which indicates that P2O5 is preferentially located in the finished granule compared to other inputs.

[0046] FIG. 7 is a thermogravimetric analysis of bauxite, bauxite-embedded ammonium phosphate granules, and produced monoammonium phosphate, according to an embodiment of the present disclosure. The addition of bauxite leads to a retention of MAP components within the granules upon heating, showing that at least one MAP component binds to bauxite during production.

[0047] FIG. 8 is a plot comparing measured total nitrogen content of granules versus P2O5 content, according to an embodiment of the present disclosure. The Total N-to-Total P2O5 slopes are significantly lower than ideal slopes based on material inputs into the process. This difference indicates phosphate was preferentially retained in the granule compared to nitrogen due to phosphate binding to bauxite during production.

[0048] FIG. 9 is a graph comparing ammonia input reduction versus activated bauxite content in granules, according to an embodiment of the present disclosure. The achievement of proper granulation while needing to reduce ammonia inputs into the system shows that bauxite was serving as a binder for phosphate during manufacturing.

[0049] FIG. 10 is a graph comparing reduction in granular nitrogen content with activated bauxite content in granules, according to an embodiment of the present disclosure. The nitrogen reduction was observed in granule analyses in addition to manufacturing inputs.

[0050] FIG. 11 is a graph comparing reduction in nitrogen content from projected nitrogen content with activated bauxite content in granules, according to an embodiment of the present disclosure. The strong correlation suggests that bauxite was actively replacing the role of ammoniaAtorney Docket No.: 40688-0015-PCTas a binder to phosphate during manufacturing.

[0051] FIG. 12 is a graph showing the effect of calcination-based methods on P2O5 adsorption of bauxite (Bauxite #1), according to an embodiment of the present disclosure.

[0052] FIG. 13 is a graph comparing P2O5 availability with activated bauxite content in granules, according to an embodiment of the present disclosure. The transition from water-soluble P2Osto citrate-soluble P2O5 indicates a stronger binding of phosphate within the granule with increasing activated bauxite content.

[0053] FIG. 14 is a graph comparing P2O5 availability with activated bauxite content in granules, according to an embodiment of the present disclosure.

[0054] FIG. 15 is a plot of phosphate release from various granules over time, according to an embodiment of the present disclosure. As bauxite concentrations increase, P release becomes more controlled.

[0055] FIG. 16 is a graph showing calculated crystalline water loss during granulation, according to an embodiment of the present disclosure.

[0056] FIG. 17 is a graph showing calculated loss-on- ignition of bauxites during granulation, according to an embodiment of the present disclosure.

[0057] FIG. 18 is a graph comparing propensity to volatilize crystalline water from lattices for different bauxites, according to an embodiment of the present disclosure.

[0058] FIG. 19 is a plot correlating activated bauxite content and reduction in ammonia input during granulation, according to an embodiment of the present disclosure.

[0059] FIG. 20 is a graph comparing calculated ammonia reduction based on ammoniaphosphoric acid imbalance as determined via titration of granules exiting a granulator with activated bauxite content of the granules, according to an embodiment of the present disclosure.

[0060] FIG. 21 is a graph comparing ammonia reduction versus activated bauxite content for different bauxites, according to an embodiment of the present disclosure.Attorney Docket No.: 40688-0015-PCT

[0061] FIG. 22 is a graph comparing water-soluble, citrate-soluble, and citrate-insoluble P2O5 with activated bauxite content for a first bauxite, according to an embodiment of the present disclosure.

[0062] FIG. 23 is a graph comparing water-soluble, citrate-soluble, and citrate-insoluble P2O5 with activated bauxite content for a second bauxite, according to an embodiment of the present disclosure.

[0063] FIG. 24 is a graph comparing water-soluble, citrate-soluble, and citrate-insoluble P2O5 with activated bauxite content for a third bauxite, according to an embodiment of the present disclosure.

[0064] FIG. 25 is a graph comparing granules produced by size versus bauxite inclusion rate, according to an embodiment of the present disclosure.

[0065] FIG. 26 is a graph of production rate versus bauxite inclusion at pilot scale (at the IFDC).

[0066] FIG. 27 is a graph of production rate versus bauxite type at pilot scale (at the IFDC).

[0067] FIG. 28 is a graph of production rate versus bauxite type at commercial scale (excluding shutdowns) for the production of MAP.

[0068] FIG. 29 is a graph of shutdown events comparing bauxite with no bauxite at commercial scale.

[0069] FIG. 30 is a graph of production rate versus bauxite type at commercial scale (including shutdowns) for the production of MAP. It is generally accepted in the industry that lower recycle:product ratios lead to higher production rates.

[0070] FIG. 31 is a graph of production rate versus recycleiproduct ratio.

[0071] FIG. 32 is a graph comparing crystalline water loss versus dryer burner temperature.

[0072] FIG. 33 is a graph comparing production rate versus dryer burner temperature.Atorney Docket No.: 40688-0015-PCT

[0073] FIG. 34 is a graph comparing crystalline water loss versus pH.

[0074] FIG. 35 is a graph comparing production rate versus pH.

[0075] FIG. 36 is a graph comparing crystalline water loss versus water input.

[0076] FIG. 37 is a graph comparing production rate versus water input.

[0077] FIG. 38 is a graph comparing crystalline water loss versus sulfuric acid input.

[0078] FIG. 39 is a graph comparing crystalline water loss versus pre-neutralizer N:P ratio at commercial scale for the production of MAP.

[0079] FIG. 40 is a graph comparing production rate versus pre-neutralizer N:P ratio at commercial scale for the production of MAP.

[0080] FIG. 41 is a graph of production rate versus bauxite inclusion at pilot scale (at the IFDC) for production of TSP.

[0081] FIG. 42 is a graph of production rate versus bauxite inclusion at laboratory scale for production of TSP.

[0082] FIG. 43 is a graph of production rate versus bauxite inclusion at laboratory scale for the production of TSP.

[0083] Wherever possible, the same reference numbers will be used throughout the drawings to represent the same features.DETAILED DESCRIPTION OF THE INVENTION

[0084] Disclosed herein are methods of manufacturing phosphorous containing fertilizers with enhanced efficiency, including methods that maintain a high production rate independent of recycle:product ratio, promoting greater flexibility with process conditions such as volume of material in the system, and size distribution out of the dryer. Embodiments of the present disclosure, in contrast to methods lacking one or more of the features disclosed herein, have greater production efficiency, faster production rate, decreased costs, greater flexibility in productionAtorney Docket No.: 40688-0015-PCTparameters due to independence of production rate from recycle :product ratio, decreased manufacturing stops, quicker agglomeration of granules in granulator, decreased granule attrition, increased citrate-soluble P2O5, lower water-soluble P2O5, or combinations thereof.

[0085] As used herein, “about” indicates a variance of up to 10% from the value being so modified. All values modified with “about” are also intended to convey the unmodified value as an alternative, so that “about 10 gm,” by way of examples, discloses both a range of 9-11 gm as well as specifically 10 gm.

[0086] As used herein, “coherent” dispersible granules are differentiated from “agglomerated” dispersible granules in that “agglomerated” refers to granules formed by mechanically agglomerating at least two types of preformed particles together, whereas “coherent” refers to granules formed by agglomerating one type of preformed particle with a second domain of material which is being simultaneously formed. Structural distinctions between coherent dispersible granules and agglomerated dispersible granules include, but are not limited to, greater granule crush strength, improved resistance to attrition, reduced moisture content, greater hygroscopic stability, less intergranular variability in bauxite:supplemental weight ratio, greater contact surface area between bauxite domains 2 and phosphate domains 3 resulting in tighter adhesion, increased bauxite surface area, reduced binder incorporation, a greater degree of intermixed domains, or combinations thereof.

[0087] As used herein, “activated” indicates a material which has reduced crystalline water than the same material in un-activated form.

[0088] The term “accretion,” as used herein, means the process of growth increase by gradual accumulation of additional layers or matter.

[0089] “Acid,” as used herein, includes, but is not limited to, boric acid, phosphoric acid, sulfuric acid, nitric acid, or combinations thereof, granulation processes with phosphoric acid, sulfuric acid, nitric acid, or combinations thereof, and ground alkaline rock, or granulation processes with liquid acidic borate, liquid acidic phosphate, liquid acidic sulfate, liquid acidic nitrate, or combinations thereof melted from a solid state.

[0090] “Caking,” as is used herein, refers to a product’s affinity for itself (i.e., stickiness toAtorney Docket No.: 40688-0015-PCTitself).

[0091] “Base,” as used herein, includes ammonia and all suitable alternatives.

[0092] “NPK or NP” fertilizers encompass all phosphorous based fertilizers.

[0093] “Recycle:product ratio,” as used herein, refers to weight ratio of granules recycled back through the mixer versus granules removed from the mixer having a predetermined size and sent to the product line.

[0094] “Throughput,” as used herein, means the rate at which volume or mass moves through the production system.

[0095] “Viscosity,” as used herein, refers to the thickness of the reduced slurry when entering the mixer system.

[0096] All percentages presented herein are weight percent on the basis of the entire composition, unless indicated to the contrary.

[0097] In one embodiment, methods for manufacture of phosphate-based fertilizer may form coherent dispersible activated bauxite granules 1 include ammoniation-granulation processes with any suitable acid, including, but not limited to, boric acid, phosphoric acid, sulfuric acid, nitric acid, or combinations thereof, granulation processes with any suitable acid, including, but not limited to, boric acid, phosphoric acid, sulfuric acid, nitric acid, or combinations thereof, granulation processes with phosphoric acid, sulfuric acid, nitric acid, or combinations thereof and ground alkaline rock, or granulation processes with liquid acidic borate, liquid acidic phosphate, liquid acidic sulfate, liquid acidic nitrate, or combinations thereof melted from a solid state. In another embodiment, methods for forming agglomerated dispersible activated bauxite granules include physically blending bauxite particles with supplemental particles and at least one water-soluble binder and then drying at a temperature of at least 250 °F.

[0098] Referring to FIG. 2, in one embodiment, methods for manufacture of phosphate-based fertilizer that forms coherent dispersible activated bauxite granules 1 includes disposing at least one acid, such as, but not limited to, boric acid, phosphoric acid, sulfuric acid, nitric acid, or combinations thereof in an acid surge tank 10, reacting the at least one acid with ammonia in aAtorney Docket No.: 40688-0015-PCTreactor vessel 20 to form at least one ammonium salt, including, but not limited to, ammonium pcntaboratc, ammonium phosphate, ammonium sulfate, ammonium nitrate, or combinations thereof, introducing bauxite particles into the presence of the at least one ammonium salt, coagglomerating the at least one ammonium salt and the bauxite particles in a rotary drum ammoniator-granulator 30 to form coherent dispersible granules, and drying the coherent dispersible granules. At least one of the introducing bauxite particles into the presence of the at least one ammonium salt and the drying the coherent dispersible granules activates the bauxite particles so as to form the coherent dispersible activated bauxite granules 1 having a coherent dispersible activated bauxite granule crush strength of at least 5 Ibf. The at least one activated bauxite domain 2 and the at least one phosphate, sulfate, or nitrate domain 3 are present in the coherent dispersible activated bauxite granules 1 as distinct domains coherently agglomerated together.

[0099] Introducing the bauxite particles into the presence of the at least one ammonium salt may include premixing the bauxite particles with the at least one acid prior to reacting the at least one acid with the ammonia. Introducing the bauxite particles into the presence of the at least one ammonium salt may include adding the bauxite particles into at least one of the acid surge tank 10, the reactor vessel 20, or the rotary drum ammoniator-granulator 30.

[0100] Tn one embodiment, the granulating drum is 92 cm in diameter, 180 cm long, has a 1.5 degree slope and rotates at 21 rpm. In another embodiment the granulator is 300 cm in diameter, 700 cm in length, has a 1.5 degree slope, and rotates at rotates at 9 rpm. The force of impact of the granule within the granulator varies by size, as shown in Table 1.

[0101] Table 1: Granulating Drum Forces (values in N)> &<<& &Atorney Docket No.: 40688-0015-PCT

[0102] The reactor vessel 20 may be a pipe cross reactor. In one embodiment, introducing the bauxite particles into the presence of the at least one of the ammonium salt includes feeding the bauxite particles through the pipe cross reactor.

[0103] Drying the coherent dispersible granules 1 may include drying the coherent dispersible granules 10 in a rotary dryer 40. In one embodiment, the bauxite particles may be introduced into the rotary dryer 40. Optionally, the coherent dispersible granules 1 may be introduced into a rotary cooler 50 following the rotary dryer 40.

[0104] In one embodiment the dryer is 92 cm in diameter, 730 cm long, has a 2 degree slope, and rotates at 12 rpm. In another embodiment, the dryer is 360 cm in diameter, 3,050 cm in length, has a 1.5 degree slope and rotates at 3.85 rpm. The force of the granule in the dryer varies based on size, as shown in Table 2.

[0105] Table 2: Drying Drum Forces (values in N)

[0106] In one embodiment a coating drum is used. The force on the granule therein varies based on size and as shown in Table 3.

[0107] Table 3: Coating Drum Forces (values in N)Atorney Docket No.: 40688-0015-PCT

[0108] Referring to FIG. 4, in one embodiment, methods for manufacture of phosphate-based fertilizer that forms coherent dispersible activated bauxite granules 1 includes mixing at least one of phosphoric acid, sulfuric acid, or nitric acid and ground alkaline rock in a reactor 20, feeding the slurry into a granulator 30, introducing bauxite particles into the presence of the agglomerating superphosphate or nitrophosphate, co-agglomerating the superphosphate or nitrophosphate and the bauxite particles in the granulator 30 to form the coherent dispersible granules 1, and drying the coherent dispersible granules 1 , wherein at least one of the introducing bauxite particles into the presence of the at least one of the superphosphate slurry or the nitrophosphate slurry and the drying the coherent dispersible granules 1 activates the bauxite particles so as to form the coherent dispersible activated bauxite granules 1 having a coherent dispersible activated bauxite granule crush strength of at least 5 Ibf. The at least one bauxite domain 2 and the at least one phosphate, sulfate, or nitrate domain 3 are present in the coherent dispersible activated bauxite granules 1 as distinct domains coherently agglomerated together. The ground alkaline rock may be ground phosphate rock.

[0109] Introducing the bauxite particles into the presence of the at least one of the superphosphate slurry or the nitrophosphate slurry may include premixing the bauxite particles with the at least one of the phosphoric acid, the sulfuric acid, or the nitric acid prior to mixing the at least one of the phosphoric acid, the sulfuric acid, or the nitric acid with the ground alkaline rock. Introducing the bauxite particles into the presence of the at least one of the superphosphate slurry or the nitrophosphate slurry may include adding the bauxite particles into at least one of an acid control tank upstream of the reactor, an alkaline rock weigher feeder upstream of the reactor, the reactor, or the rotary drum granulator 30.

[0110] Drying the coherent dispersible granules 1 may include drying the coherent dispersibleAtorney Docket No.: 40688-0015-PCTgranules 10 in a rotary dryer 40. Tn one embodiment, the bauxite particles may be introduced into the rotary dryer 40.

[0111] In another embodiment, a method for forming coherent dispersible activated bauxite granules 1 includes disposing at least one acid, such as, but not limited to, boric acid, phosphoric acid, sulfuric acid, nitric acid, or combinations thereof, in a reactor, introducing bauxite particles into the presence of the at least one acid, co-agglomerating the at least one of the at least one acid and the bauxite particles in a rotary drum granulator 30 to form coherent dispersible granules, and drying the coherent dispersible granules. At least one of the introducing bauxite particles into the presence of the at least one acid or the drying the coherent dispersible granules 1 activates the bauxite particles so as to form the coherent dispersible activated bauxite granules 1 having a coherent dispersible activated bauxite granule crush strength of at least 5 Ibf. The at least one bauxite domain 2 and the at least one phosphate domain 3 are present in the coherent dispersible activated bauxite granules 1 as distinct domains coherently agglomerated together.

[0112] Drying the coherent dispersible granules 1 may include drying the coherent dispersible granules 10 in a rotary dryer 40. In one embodiment, the bauxite particles may be introduced into the rotary dryer 40.

[0113] Referring to FIG. 5, in one embodiment, the coherent dispersible activated bauxite granules 1 include at least one activated bauxite domain 2, and at least one supplemental domain 3, wherein the at least one activated bauxite domain 2 and the at least one supplemental domain 3 are present in the coherent dispersible activated bauxite granules 1 as distinct domains coherently agglomerated together. The at least one supplemental domain 3 may be a phosphate domain 3 as the at least one nutrient domain 3. The at least one phosphate domain 3 may include, but is not limited to, MAP, DAP, granulated TSP, granulated DSP, granulated SSP, or combinations thereof.

[0114] The at least one activated bauxite domain 2 and the at least one phosphate domain 3 may be intragranularly homogenously or heterogeneously distributed in the coherent dispersible activated bauxite granules 1. The at least one activated bauxite domain 2 and the at least one phosphate domain 3 may be intergranularly homogenously or heterogeneously distributed in the coherent dispersible activated bauxite granules 1.Atorney Docket No.: 40688-0015-PCT

[0115] In one embodiment, each of the at least one activated bauxite domain 2 is at least 50% surrounded by the at least one supplemental domain 3, alternatively at least 60% surrounded, alternatively at least 70% surrounded, alternatively at least 80% surrounded, alternatively at least 90% surrounded, alternatively at least 95% surrounded, alternatively at least 99% surrounded, alternatively entirely surrounded.

[0116] The dispersible activated bauxite granules 1 may have any suitable weight ratio of bauxite to phosphate, including, but not limited to, a weight ratio of 10:1 to 1:10, alternatively 8:1 to 1:8, alternatively 7:1 to 1:7, alternatively 6:1 to 1:6, alternatively 5:1 to 1:5, alternatively 4:1 to 1:4, alternatively 3:1 to 1:3, alternatively 2:1 to 1:2, alternatively 3:1 to 1:1, alternatively 1:1 to 1:3, alternative about 2:1, alternatively about 1:1, alternatively about 1:2, or any sub-range or combination of ranges thereof.

[0117] The dispersible activated bauxite granules 1 may further include at least one of a water-soluble binder, a suspension agent, or an emulsifying agent. In one embodiment, the dispersible activated bauxite granules 1 include, by weight, 1-40% water-soluble binder, alternatively 5-35%, alternatively 5-15%, alternatively 10-20%, alternatively 15-25%, alternatively 20-30%, alternatively 25-35%, or any sub-range or combination thereof. Suitable water-soluble binders include, but are not limited to, calcium lignosulfonate, ammonium lignosulfonate, or combinations thereof. Suitable suspension agents include, but are not limited to, polysaccharides, inorganic salts, carbomers, or combinations thereof. Suitable emulsifying agents include, but are not limited to, vegetable derivatives such as acacia, tragacanth, agar, pectin, carrageenan, or lecithin, animal derivatives such as gelatin, lanolin, or cholesterol, semi-synthetic agents such as methylcellulose, or carboxymethylcellulose, synthetics such as benzalkonium chloride, benzethonium chloride, alkali soaps (including sodium or potassium oleate), amine soaps (including triethanolamine stearate), detergents (including sodium lauryl sulfate, sodium dioctyl sulfosuccinate, or sodium docusate), sorbitan esters, polyoxyethylene derivatives of sorbitan esters, glyceryl esters, or combinations thereof. In another embodiment, the dispersible activated bauxite granules 1 are free of water-soluble binders, suspension agents, emulsifying agents, any two of the foregoing, or all of the foregoing.

[0118] The dispersible activated bauxite granules 1 may further include at least one additionalAttorney Docket No.: 40688-0015-PCTdomain present as a distinct domain. Suitable additional domains include, but are not limited to, at least one nutrient domain, at least one pesticide domain, at least one biological additive domain, at least one sorbent domain, or combinations thereof. The at least one additional domain may be coherently agglomerated with the at least one activated bauxite domain 2 and the at least one supplemental domain 3 in the dispersible activated bauxite granules 1 , the at least one additional domain may be agglomerated with the agglomerated at least one activated bauxite domain 2 and at least one supplemental domain 3, the at least one additional domain may be coated onto the at least one activated bauxite domain 2 and at least one supplemental domain 3, individually or as clustered together in a dispersible activated bauxite granule 1 , the at least one additional domain may be intermixed with the dispersible activated bauxite granules 1, or combinations thereof. By way of non-limiting example, in one embodiment, a coherent dispersible activated bauxite granule 1 could include at least one nutrient domain coherently agglomerated with the at least one bauxite domain 2 and the at least one phosphate domain 3, at least one pesticide domain agglomerated with the coherently agglomerated at least one nutrient domain, at least one activated bauxite domain 2, and at least one phosphate domain 3, and at least biological additive domain coated onto the at least one pesticide domain agglomerated with the coherently agglomerated at least one nutrient domain, at least one activated bauxite domain 2, and at least one supplemental domain 3.

[0119] The bauxite particles constituting the activated bauxite domain 2 may have any suitable size. In one embodiment, to maintain adsorptive capacity for phosphate and optimizing the bauxite particle size for penetrating the soil profile through a surface application, a preferred particle size for activated bauxite particles is smaller than about 300 pm, alternatively smaller than about 150 gm, alternatively smaller than about 100 pm, alternatively smaller than about 75 pm, alternatively smaller than about 50 pm, alternatively smaller than about 25 pm, or smaller, or any sub-range or combination thereof.

[0120] In one embodiment, the dispersible activated bauxite granules 1 include by weight, 5-80% activated bauxite domain 2, 10-95% supplemental domain 3, and, optionally, 1-50% water-soluble binder, alternatively 5-50% activated bauxite domain 2, 10-95% supplemental domain 3, and, optionally, 1-50% water-soluble binder, alternatively 30-40% activated bauxite domain 2, 30-40% supplemental domain 3, and 20-40% water-soluble binder, alternatively 35% activated bauxite domain 2, 35% supplemental domain 3, and 30% water-soluble binder. In a furtherAtorney Docket No.: 40688-0015-PCTembodiment, the dispersible activated bauxite granules 1 include by weight, 5-50% activated bauxite domain 2, 10-70% supplemental domain 3, up to 50% water-soluble binder, and up to 20% surfactants and emulsifiers combined, alternatively consist of, by weight, 5-50% activated bauxite domain 2, 10-50% supplemental domain 3, up to 50% water-soluble binder, and up to 5% surfactants and emulsifiers combined.

[0121] The dispersible activated bauxite granules 1 may have any suitable size (as measured by diameter based upon the median within the sample). Suitable sizing for the dispersible activated bauxite granules 1 may include, but is not limited to, about 0.4 mm to about 4.0 mm, alternatively about 0.4 mm to about 1.2 mm, alternatively about 0.9 mm to about 1.5 mm, alternatively about 1.2 mm to about 1.8 mm, alternatively about 1.5 mm to about 2.1 mm, alternatively about 1.8 mm to about 2.4 mm, alternatively about 2.1 mm to about 2.7 mm, alternatively about 2.4 mm to about 3.0 mm, alternatively about 2.7 mm to about 3.3 mm, alternatively about 3.0 mm to about 3.6 mm, alternatively about 3.3 mm to about 4.0 mm, alternatively about 0.4 mm, alternatively about 0.5 mm, alternatively about 0.6 mm, alternatively about 0.7 mm, alternatively about 0.8 mm, alternatively about 0.9 mm, alternatively about 1.0 mm, alternatively about 1.1 mm, alternatively about 1.2 mm, alternatively about 1.3 mm, alternatively about 1.4 mm, alternatively about 1.5 mm, alternatively about 1.6 mm, alternatively about 1.7 mm, alternatively about 1.8 mm, alternatively about 1.9 mm, alternatively about 2.0 mm, alternatively about 2.1 mm, alternatively about 2.2 mm, alternatively about 2.3 mm, alternatively about 2.4 mm, alternatively about 2.5 mm, alternatively about 2.6 mm, alternatively about 2.7 mm, alternatively about 2.8 mm, alternatively about 2.9 mm, alternatively about 3.0 mm, alternatively about 3.1 mm, alternatively about 3.2 mm, alternatively about 3.3 mm, alternatively about 3.4 mm, alternatively about 3.5 mm, alternatively about 3.6 mm, alternatively about 3.7 mm, alternatively about 3.8 mm, alternatively about 3.9 mm, alternatively about 4.0 mm, alternatively more than about 4.0 mm, or any sub-range or combination thereof. In one non-limiting example, golf greens may use dispersible activated bauxite granules 1 of about 0.5 mm to about 0.8 mm. In another non-limiting example, com may use dispersible activated bauxite granules 1 via a broadcast application of about 2.4 mm. In a third non-limiting example, any crop with a strip-till machine application may use dispersible activated bauxite granules 1 of about 1.5 mm. In one embodiment, suitable, for example, for application as a suspension, the dispersible activated bauxite granules 1 are micronized, and have a particle size less than about 200 pm, alternatively less than about 150 pm, alternatively less than about 100 pm, alternativelyAttorney Docket No.: 40688-0015-PCTless than about 75 gm, alternatively less than about 1 pim, alternatively less than about 1 gm, alternatively less than about 50 gm, alternatively less than about 25 pm, alternatively less than about 10 pm, alternatively less than about 5 pm, alternatively less than about 2 pm, alternatively less than about 1 pm, alternatively less than about 0.75 pm, alternatively less than about 0.5 pirn, alternatively less than about 0.25 pim, alternatively less than about 0.1 pm, alternatively less than about 0.05 pim, alternatively less than about 0.01 pim, as measured by largest particle dimension.

[0122] The at least one activated bauxite domain 2 may have an alumina content of at least 35 wt% based on the total weight of the at least one activated bauxite domain 2, alternatively at least 40 wt%, alternatively at least 45 wt%, alternatively at least 50 wt%, alternatively at least 55 wt%. The at least one activated bauxite domain 2 may have a combined alumina and iron oxide content of at least 55 wt% based on the total weight of the at least one activated bauxite domain 2, alternatively at least 60 wt%, alternatively at least 65 wt%, alternatively at least 70 wt%, alternatively at least 75 wt%. The at least one activated bauxite domain 2 may include activated mineral bauxite free of chemical modification with NaOH. The at least one activated bauxite domain 2 may include at least one of activated lateritic bauxite or activated karst bauxite.

[0123] In one embodiment, dispersible activated bauxite granules 1 include activated bauxite particles and water-soluble binder agglomerating the plurality of activated bauxite particles into the dispersible activated bauxite granules 1. The activated bauxite particles are free of chemical modification with NaOH.

[0124] The activated bauxite particles may have an alumina content of at least 35 wt% based on the total weight of the activated bauxite particles, alternatively at least 40 wt%, alternatively at least 45 wt%, alternatively at least 50 wt%, alternatively at least 55 wt%. The activated bauxite particles may have a combined alumina and iron oxide content of at least 55 wt% based on the total weight of the activated bauxite particles, alternatively at least 60 wt%, alternatively at least 65 wt%, alternatively at least 70 wt%, alternatively at least 75 wt%. The activated bauxite particles may include at least one of activated lateritic bauxite or activated karst bauxite. The dispersible bauxite granules 1 may further include at least one of a suspension agent or an emulsifying agent. The dispersible bauxite granules 1 may have a moisture content, by weight, of less than 10%, alternatively less than 8%, alternatively less than 6%, alternatively less than 5%, alternatively lessAttorney Docket No.: 40688-0015-PCTthan 4%, alternatively less than 3%, alternatively less than 2%, alternatively less than 1%. The dispersible bauxite granule 1 may have any suitable size, including, but not limited to, a size of less than 0.6 mm, alternatively less than 0.5 mm, alternatively less than 0.4 mm, alternatively less than 0.3 mm, alternatively less than 0.2 mm, alternatively less than 0.1 mm.

[0125] Referring to FIGS. 1-4, in one embodiment, a method for the manufacture of a phosphate-based fertilizer includes: (a) exposing a bauxite to an acid to form a mixture, the mixture including a phosphate source; (b) activating the bauxite in situ by removal of crystalline water from the bauxite; (c) binding phosphate from the phosphate source to the bauxite; and (d) recycling the mixture in a mixer to form the phosphate-based fertilizer as a plurality of granules, wherein there is an increased throughput of at least 5% relative to a comparative fertilizer production process that is an otherwise identical fertilizer production process lacking in situ activation of the bauxite, and the increased throughput is independent of recycleiproduct ratio.

[0126] The fact that increased throughput was achieved independent of recycle:product ratio is an unexpected result. Typically, process conditions must be optimized to narrow ranges to increase production throughput, including in particulal selecting particular recycle:product ranges, with lower recycle to product ranges typically resulting in higher production throughput. Secondary process conditions must further be optimized to narrow, and sometimes undesirable ranges in order to achieve necessary recycle:product ratio ranges to support the higher production throughput. Here, however, it has been surprisingly discovered that in situ activation of the bauxite in the described processes promotes high production throughput regardless of the recycle:product ratio, which further permits greater flexibility in the secondary process conditions. This result in not only unexpected, but counterintuitive. Further, the binding of the phosphate from the phosphate source to the bauxite may yield more citrate-soluble P2O5 and less water-soluble P2O5.

[0127] The increased throughput relative to the comparative fertilizer production process lacking in situ activation of the bauxite may be any suitable increase, including, but not limited to, an increased throughput of at least 5%, alternatively an increased throughput of at least 6%, alternatively an increased throughput of at least 7%, alternatively an increased throughput of at least 8%, alternatively an increased throughput of at least 9%, alternatively an increased throughput of at least 10%, alternatively an increased throughput of at least 12.5%, alternativelyAtorney Docket No.: 40688-0015-PCTan increased throughput of at least 15%, alternatively an increased throughput of at least 17.5%, alternatively an increased throughput of at least 20%, alternatively an increased throughput of at least 25%, alternatively an increased throughput of at least 30%, alternatively an increased throughput of at least 35%, alternatively an increased throughput of at least 40%, alternatively an increased throughput of 5-50%, alternatively an increased throughput of 5-15%, alternatively an increased throughput of 10-20%, alternatively an increased throughput of 15-25%, alternatively an increased throughput of 20-30%, alternatively an increased throughput of 25-35%, alternatively an increased throughput of 30-40%, alternatively an increased throughput of 35-45%, alternatively an increased throughput of 40-50%, alternatively an increased throughput of 5-45%, alternatively an increased throughput of 5-40%, or sub-ranges or combinations thereof.

[0128] The activating of the bauxite in situ may include any suitable activation technique, including, but not limited to, calcining the bauxite in a dryer burner above 375 °C, acidifying the mixture to a pH below 5.5, increasing water content of the mixture during granulation to at least about 13.5 wt%, steaming the mixture during granulation, or combinations thereof.

[0129] Calcining the bauxite in the dryer burner may be performed at any suitable temperature, including, but not limited to, a temperature of at least 375 °C, alternatively at least 400 °C, alternatively at least 425 °C, alternatively at least 450 °C, alternatively at least 475 °C, alternatively at least 500 °C, alternatively at least 525 °C, alternatively at least 550 °C, alternatively at least 575 °C, alternatively at least 600 °C.

[0130] Acidifying the mixture may include acidifying the mixture to any suitable pH, including, but not limited to, a pH below 5.5, alternatively a pH below 5.25, alternatively a pH below 5, alternatively a pH below 4.75, alternatively a pH below 4.5, alternatively a pH below 4.25, alternatively a pH below 4 alternatively a pH below 3.75, alternatively a pH below 3.5, alternatively a pH below 3.25, alternatively a pH below 3 alternatively a pH below 2.75, alternatively a pH below 2.5, alternatively a pH below 2.25, alternatively a pH below 2. Acidifying the mixture may include adding any suitable acid to the mixture, including, but not limited to, a strong acid. Suitable strong acids include, but are not limited to, sulfuric acid.

[0131] Increasing the water content of the mixture during granulation may including increasing the water content to any suitable concentration, including, but not limited to, aAttorney Docket No.: 40688-0015-PCTconcentration of at least about 13.5 wt%, alternatively at least about 13.75 wt%, alternatively at least about 14 wt%, alternatively at least about 14.25 wt%, alternatively at least about 14.5 wt%, alternatively at least about 14.75 wt%, alternatively at least about 15 wt%, alternatively at least about 15.5 wt%, alternatively at least about 15.75 wt%, alternatively at least about 16 wt%, alternatively at least about 16.25 wt%, alternatively at least about 16.5 wt%, alternatively at least about 16.75 wt%, alternatively at least about 17 wt%, alternatively at least about 17.25 wt%, alternatively at least about 17.5 wt%, alternatively at least about 17.75 wt%, alternatively at least about 18 wt%, alternatively at least about 18.25 wt%, alternatively at least about 18.5 wt%, alternatively at least about 18.75 wt%, alternatively at least about 19 wt%, alternatively at least about 19.25 wt%, alternatively at least about 19.5 wt%, alternatively at least about 19.75 wt%, alternatively at least about 20 wt%, alternatively at least about 20.25 wt%, alternatively at least about 20.5 wt%, alternatively at least about 20.75 wt%, alternatively at least about 21 wt%, alternatively at least about 21.25 wt%, alternatively at least about 21.5 wt%, alternatively at least about 21.75 wt%, alternatively at least about 22 wt%. Increasing the water content of the mixture may include adding water by any suitable method, including, but not limited, adding liquid water directly to the mixture, steaming the mixture or the plurality of granules, or combinations thereof.

[0132] Increasing the water content of the mixture during granulation may increase the increased throughput of at least 5% to at least at least 5.5%, alternatively at least 6%, alternatively at least 6.5%, alternatively at least 7%, alternatively at least 7.5%.

[0133] The mixer may be any suitable mixing apparatus, including, but not limited to, a tumbler, a granulator, a paddle mixer, a pin mixer, a rotating pan, an intensive mixer system (such as those manufactured by Eirich Machines), or combinations thereof.

[0134] The phosphate source may be any suitable source, including, but not limited to, the acid, such as, but not limited to, including phosphoric acid in the acid.

[0135] Binding the phosphate to the bauxite may include any suitable binding mechanism, including, but not limited to, physisorbing the phosphate to the bauxite, chemisorbing the phosphate to the bauxite, or combinations thereof.

[0136] The phosphate -based fertilizer may be any suitable fertilizer, including, but not limitedAtorney Docket No.: 40688-0015-PCTto, monoammonium phosphate, diammonium phosphate, nitrophosphate, single super phosphate, double super phosphate, triple super phosphate, or combinations thereof.

[0137] The acid may be any suitable acid, including, but not limited to, phosphoric, sulfuric, nitric, boric acid, or combinations thereof.

[0138] In one embodiment wherein the phosphate-based fertilizer is a nitrogen-phosphorous-potassium or nitrogen-phosphorous fertilizer, the acid includes phosphoric acid and exposing the bauxite to the acid to form the mixture further includes exposing the bauxite to a base along with the acid to form the mixture. The nitrogen-phosphorous-potassium or nitrogen-phosphorous fertilizer may have any suitable N:P ratio, including a ratio between 0.1:1 to 2.5:1, alternatively a ratio of between 0.2:1 to 2.5:1, alternatively a ratio of between 0.3:1 to 2.5:1, alternatively a ratio of between 0.4:1 to 2.5:1, alternatively a ratio of between 0.5:1 to 2.5:1, alternatively a ratio of between 0.1 : 1 to 1 : 1 , alternatively a ratio of between 0.5:1 to 1.5:1, alternatively a ratio of between 1:1 to 2:1, alternatively a ratio of between 1.5:1 to 2.5:1, alternatively a ratio of between 0.4:1 to 0.8:1, alternatively a ratio of between 0.7:1 to 1.2:1, alternatively a ratio of about 0.9:1, or combinations or sub-ranges thereof. In a further embodiment, the acid and the base are added into a pre-neutralizer, the pre -neutralizer having an N:P ratio from about 0.4:1 to about 0.8:1, and the nitrogen-phosphorous-potassium or nitrogen-phosphorous fertilizer has an N:P ratio from about 0.7:1 to about 1.2:1. Maintaining the N:P ratio from about 0.7:1 to about 1.2:1 in combination with mixing the acid and the base into a pre-neutralizer may reduce clogging of the nozzle in comparison to an otherwise identical process lacking the pre-neutralizer or having a higher N:P ratio, including a reduction of clogging of at least 5%, alternatively at least 10%, alternatively at least 15%, alternatively at least 20%.

[0139] The base may be any suitable base, including, but not limited to, ammonia.

[0140] In one embodiment, wherein the phosphate-based fertilizer is a nitrogen-phosphorous-potassium or nitrogen-phosphorous fertilizer, the phosphoric acid mixed with the bauxite to form the mixture is at least 5% less than the comparative fertilizer production process lacking in situ activation of the bauxite, alternatively at least 7.5% less, alternatively at least 10% less, alternatively at least 12.5% less, alternatively at least 15% less, alternatively at least 17.5% less, alternatively at least 19% less, alternatively at least 20% less, alternatively at least 25% less.Atorney Docket No.: 40688-0015-PCT

[0141] In one embodiment, wherein the phosphate-based fertilizer is a nitrogen-phosphorous-potassium or nitrogen-phosphorous fertilizer, the nitrogcn-phosphorous-potassium or nitrogenphosphorous fertilizer has a lower angle of repose relative to a comparative nitrogen-phosphorous-potassium or nitrogen-phosphorous fertilizer produced by the otherwise identical fertilizer production process lacking in situ activation of the bauxite.

[0142] In one embodiment, the phosphate-based fertilizer has increased citrate-soluble P2O5 relative to the comparative fertilizer production process. In a further embodiment, the phosphate-based fertilizer has decreased water-soluble P2O5 relative to the comparative fertilizer production process.

[0143] The phosphate-based fertilizer may have a lower viscosity relative to the comparative phosphate-based fertilizer produced by the comparative fertilizer production process.

[0144] The bauxite may have any suitable initial moisture content prior to activation, including, but not limited to, an initial moisture content of about 12 wt% to about 19 wt%.

[0145] In one embodiment, shutdown events, such as, but not limited to, nozzle blockages, are reduced by at least about one-third relative to the comparative fertilizer production process, alternatively by at least about one-half relative to the comparative fertilizer production process, alternatively by at least about two-thirds relative to the comparative fertilizer production process.

[0146] In one embodiment, the method has reduced attrition of the plurality of granules relative to the comparative fertilizer production process.

[0147] In one embodiment, the bauxite is a pre-activated bauxite prior to the further in situ activating of the bauxite by the removal of crystalline water from the bauxite described herein. The pre-activated bauxite may have been preactivated by any suitable activation process, including, but not limited to, calcining the bauxite, exposing the bauxite to an acid, steaming the bauxite, or combinations thereof.

[0148] In one embodiment, recycling the mixture in the mixer exerts a force of impact of a granule of the mixture on the mixer sufficient to sever loosely held material on that granule such that granule size is increased through accretion. The force of impact of the granule of the mixtureAtorney Docket No.: 40688-0015-PCTon the mixer is generated by a velocity of impact. The velocity of impact may be any suitable velocity, including, but not limited to, a velocity of impact of about 6 m / s to about 9 m / s.EXAMPLES

[0149] Experimental Methods

[0150] Three granulation studies were performed at the International Fertilizer Development Center (“IFDC”) in a large-scale pilot plant (“LSPP”) to obtain the data. A generic configuration of the plant is represented in FIG. 1, as a pre-neutralization step utilized for chemical granulation. Steam granulation was also accomplished on the same system, though use of the pre-neutralizer was not necessary.

[0151] Phosphoric acid was stored in two 4,150 L stainless steel cone-bottomed tanks (Hall tanks). The phosphoric acid in the storage tanks was recirculated using a centrifugal pump for homogenization prior to transfer to a 1,300 L stainless steel feed tank. The phosphoric acid in the feed tank was recirculated to prevent settling of solids. A centrifugal pump was used to transfer the phosphoric acid from the feed tank to the reactor.

[0152] During the first two tests, phosphoric acid and ammonia were chemically reacted to produce an ammonium phosphate slurry with an NIHuHtPCfi mole ratio of approximately 0.55:1. The flow rate of the phosphoric acid to the pre-neutralizer was controlled using a magnetic flow meter. The flow rate was measured every 30 minutes using a stopwatch, a beaker, and a scale. The phosphoric acid was fed through a 1.27 cm diameter pipe discharging into the pre-neutralizer through a funnel located on the pre-neutralizer cover. Ammonia was fed through a drilled pipe sparger located at the bottom of the pre-neutralizer. The ammonia sparger had 10 holes, each having a 4.76 mm diameter, drilled in the pipe facing downward toward the bottom of the vessel. The ammonia flow was measured using an armored rotameter. When needed, tap water was fed through a 1.27 cm diameter tubing monitored through the rotameter; however, the flow rate was manually checked every 30 minutes.

[0153] The pre-neutralizer was 61 cm in diameter and 201 cm high with a 9 cm shallow cone bottom. The pre-neutralizer was equipped with a variable speed agitator fitted with three axial-flow thrust turbines. From the pre-neutralizer, the ammonium phosphate slurry was transferred toAtorney Docket No.: 40688-0015-PCTthe drum granulator using a progressive-cavity variable speed pump. The pump speed was varied to maintain, as closely as possible, the calculated slurry flow rate. The slurry was sprayed using a Spraying Systems Whirljet #15 hollow-cone nozzle and discharged 51 cm from the feed end of the granulator.

[0154] An exhaust fan was used to pull the pre -neutralizer vent gases through a spray-type scrubber to clean the gases before exhausting them to the atmosphere. Water was used as the scrubbing medium. The exhaust fan and the scrubber system were coated with fluorine-resistant reinforced polyester. The scrubber liquor was discharged to a holding pond.

[0155] In both granulation studies, the various bauxite materials were fed to the granulator using an ACCURATE® solids feeder that discharged the bauxite materials into the boot of the granulator elevator, where it mixed with the recycle material before entering the granulator. The flow rate was manually checked every 30 minutes. Three different bauxite materials were used, sourced from three different geographic regions, and identified as “Bauxite #1,” “Bauxite #2,” and “Bauxite #3.”

[0156] The granulator was a rotary drum-type granulator, 92 cm in diameter and 180 cm long and rotated at 21 rpm. A 15 cm retaining dam was located 25.4 cm from the discharge end of the granulator. The granulator was operated at a 1.5-degree angle of inclination from horizontal. Gaseous ammonia was fed to the granulator through a drilled stainless steel distributor (sparger) submerged under the rolling bed of the material. The targeted NHaiHsPCh mole ratio was about 1:1. Steam and / or water were optionally added to the granulator through the drilled sparger to control granule population.

[0157] Gases drawn from the granulator were treated in a once-through venturi -type scrubber before being exhausted into the atmosphere. The scrubbing system used water as the scrubbing media and was a reinforced polyester venturi-type scrubber with a reinforced polyester recirculation seal tank having a capacity of approximately 227 liters, a recirculating pump, and a 316L stainless steel fan. The scrubber liquor was not returned to the process; it was sent to an effluent pond after each test.

[0158] Moist granular material from the granulator was discharged by gravity into a rotaryAtorney Docket No.: 40688-0015-PCTdrum-type dryer, measuring 92 cm in diameter by 730 cm in length and rotating at 12 rpm. The rotating and cascading bed of material in the dryer was dried using co-currcnt airflow. A natural gas-fired direct-flame combustion chamber was located at the inlet (material feed end) of the dryer. The operating temperature of the dryer was controlled indirectly by measuring the temperature of the dryer discharge material and adjusting for the air-to-gas ratio of the combustion chamber to maintain the desired operating temperature, though the temperature settings were able to be modified manually. The dryer was operated at a 2.0-degree angle of inclination from horizontal and equipped with a band for vibration-inducing hammers.

[0159] The dryer exhaust air / gases duct was equipped with a cyclone-type dust collector located between the dryer discharge and the dryer fan. Dust collected in the dryer cyclone was not returned to the process and was weighed before being disposed. Gases drawn from the dryer were treated in a wet scrubber before being exhausted into the atmosphere. The scrubbing system used water as the scrubbing media and included a 316 L stainless steel recirculation tank with a capacity of approximately 4,200 L, a stainless steel recirculating pump, and a 316 L stainless steel fan. Airflow through the dryer ranged from 3,000 to 4,000 cubic meters per hour. The resulting scrubber liquor was not returned to the process but was sent to an effluent pond.

[0160] A centrifugal bucket elevator was used to transfer the material from the dryer to an inclined double-deck mechanically vibrated screening system. The screen housing was fitted with a Ty-Rod 4.75 mm oversize screen and a Ty-Rod 2.36 mm undersize screen to yield a product in the 2.36 mm to 4.75 mm size range. Oversize material from the screening system was routed to a chain mill.

[0161] The crushed material discharging from the chain mill was returned to the screening system. Undersize material from the screening system was returned (recycled) to the granulator along with a controlled fraction of the product-size material to maintain granulation control, when appropriate. The product-size material from the screening system was transferred to a product cooler that was operated with co-current airflow vented to the fugitive dust collection system. Product-size material was collected in 1 metric-ton bags.

[0162] Dust from the elevators, screening system, product cooler, and conveyors was collected by the fugitive dust collection system. The fugitive dust collection system included a network ofAtorney Docket No.: 40688-0015-PCTpickup ducts that combined prior to entering a cyclone-type dust collector before being exhausted into the atmosphere by a 316 L stainless steel fan. Airflow through the fugitive dust system ranged from 1 ,000 to 1 ,200 cubic meters per hour. Dust collected in the cyclone was not returned to the process, but was weighed before being disposed.

[0163] Process data from each test was collected every 30 minutes. When possible, depending on the operating conditions, a mid-day product sample, a composite end-of-day product sample, and selected half-hour samples were collected and evaluated in IFDC’s chemical laboratories to determine their chemical composition.

[0164] Examples were prepared via a standard granulated monoammonium phosphate production method in which phosphoric acid was disposed in an acid surge tank 10 and then reacted with ammonia in a reactor vessel 20 to form monoammonium phosphate. The process was performed in trials using a pre-neutralizer setup. To achieve steam granulation, steam was injected into the rolling bed of the granulator. All material feeds were monitored and used to calculate feed material ratios. Aluminum oxide was mixed with the recycle feeds and fed into the granulator 30 at desired ratios, except for in two trials where the aluminum oxide was directly fed into the pre-neutralizer vessel and was granulated as part of the slurry feed into the granulator 30.

[0165] Viscosity was determined using Brookfield Ametek Dial Reading Viscometer, Model LVT.

[0166] All product samples collected at the end of each testing period were analyzed for total nitrogen, total P2O5, water-soluble P2O5, citrate-soluble P2O5, aluminum oxide (AI2O3), and moisture content. All chemical analyses were performed according to the AOAC International methods, except for total nitrogen which was determined using a combustion analyzer. Moisture content was determined using the vacuum desiccator method.

[0167] Coherent dispersible granules 1 were characterized by size analysis, crush strength, abrasion resistance, and impact resistance, as summarized in Table 7. Granule size analysis was performed using the sieve method outlined in Procedure IFDC S- 107-1 in the Manual for Determining Physical Properties of Fertilizer (IFDC R-10). This method determined Size Guide Number (SGN) and Uniformity Index (U.I.). Granule crush strength was determined using a forceAtorney Docket No.: 40688-0015-PCTsensor following the Procedure IFDC S-l 15 in the Manual for Determining Physical Properties of Fertilizer (IFDC R-10). Abrasion resistance was determined by rolling granules alongside steel balls as outlined in the Procedure IFDC S- 116 in the Manual for Determining Physical Properties of Fertilizer (IFDC R-10). Impact resistance was determined by impacting the granules within a bagged system as outlined in the Procedure IFDC S-l 18 in the Manual for Determining Physical Properties of Fertilizer (IFDC R- 10).

[0168] Study 1

[0169] Monoammonium phosphate (MAP) was produced on the system via chemical granulation to standardize production parameters. Bauxite #1 was introduced into the system at varying input inclusion rates (10.31%, 20.63%, 30%, 40%, and 50%).

[0170] Study 2

[0171] Granulated MAP was milled to a powder with size distribution ranging from -100 mesh to 4 mm. The powdered MAP was re-granulated via steam granulation in the IFDC LSPP system to standardize production parameters. Bauxite #1 was then introduced into the system at varying input inclusion rates (10.31%, 20.63%, 30%, 40%, and 50%).

[0172] Study 3

[0173] Monoammonium phosphate (MAP) was produced on the system via chemical granulation to standardize production parameters. Bauxite #1 was introduced into the system at varying input inclusion rates (20.63%, 30%, and 40%). The remaining material within the system was bled out, and Bauxite #2 was introduced at the same input inclusion rates. Again, the material within the system was bled out, and Bauxite #3 was introduced at the same input inclusion rates.

[0174] Phosphate Release Study

[0175] The granulated materials from Study 1 were evaluated for their phosphate release characteristics in water. The phosphate release curves were obtained by placing a designated weight of granules (0.3 g of phosphate) into 50 mL of deionized water and monitoring phosphate concentrations in the water reservoir at designated time points. Aliquots of liquid were removed and replaced from the liquid reservoir at periodic time points. Filtrate phosphate concentrationsAtorney Docket No.: 40688-0015-PCTwere analyzed colorimetricaly by the Murphy and Riley (1962) procedure using a SEAL AQ 400 autoanalyzer, Method EPA-118-A Rcv.5 (SEAL Analytical, 2004).

[0176] Referring to FIG. 6, the predicted available P2O5 is compared to the measured available P2O5 of the produced granules. The predicted available P2O5 was based on an input bauxite material inclusion being equal to the output bauxite inclusion in the finished granule. Since the slope of m = 1.455 is statistically greater than a slope of m = 1, it was demonstrated that a mass loss was observed from the input bauxite. Since bauxite “activation” is defined as a loss of bound water from the bauxite crystalline structure, this change evidences that crystalline water was removed from the bauxite during the granulation process.

[0177] Referring to FIG. 7, thermogravimetric analysis (“TGA”) curves over a temperature range of 25 °C to 1,000 °C of the produced bauxite-embedded ammonium phosphate granules, produced monoammonium phosphate, and bauxite are shown (Bauxite #1). The bauxite curve clearly demonstrates that trihydrate water is removed over a temperature range of 250 °C to 375 °C and monohydrate water is removed over a range of 375 °C to 550 °C. The granule TGA curve does not show the proper proportion of trihydrate or monohydrate water loss at the appropriate temperature range, indicating that the bound water had already been lost prior to testing, evidencing that the bound water was removed during the granulation process.

[0178] As shown in Table 4, the type of Granulation had an impact on the degree of bauxite activation. Chemical granulation shows greater crystalline water loss from bauxite than steam granulation. As shown in Table 5, the combustion chamber temperature of the dryer also had an impact on activation, indicating that some of the crystalline water loss occurs in the rotary dryer.

[0179] Table 4. Effect of Granulation on Bauxite Activation

[0180] Table 5. Effect of Drying Temperature on Bauxite ActivationAtorney Docket No.: 40688-0015-PCT

[0181] Referring to FIG. 8, the measured total nitrogen content of the granules was compared to the total P2O5 content. Since monoammonium phosphate is designed to be produced at a 1:1 mole ratio, the slope should remain consistent based on the mole ratio regardless of additional inputs (in this case, the slope was expected to be m = 4.94, based on the total P2O5 mass input divided by the total nitrogen mass input (53.3 / 10.8)). However, the slopes for both chemical and steam granulation are statistically lower than m = 4.94 when bauxite is introduced at varying concentrations, indicating that ammonia requirements were lessened compared to phosphoric acid during manufacturing. This indicates that the phosphoric acid interacts chemically with the bauxite and outcompetes ammonia molecules for reaction sites. The introduction of bauxite lowers ammonia requirements to achieve granulation.

[0182] Referring to FIG. 9, inclusion of bauxite reduced ammonia requirements to achieve granulation. During manufacturing, material inputs are adjusted periodically by the plant operators to maintain adequate granulatability. As greater amounts of bauxite are included as material inputs, the ammonia requirements were reduced below projected input rates in tandem with bauxite input.

[0183] Referring to FIG. 10, the reduction in granular nitrogen content from the projected amount is plotted as a function of activated bauxite content present in the granule for granules produced via chemical granulation. The reduction in ammonia inputs carries over to the final granular nitrogen content, further evidencing that bauxite reduces nitrogen requirements in manufacturing.

[0184] Referring to FIG. 11, the reduction in granular nitrogen content from the projected amount is plotted as a function of activated bauxite content present in the granule for granules produced via steam granulation. While a nitrogen reduction was observed, the rate of reduction was lower than that for granules produced via chemical granulation, indicating that the level of bauxite activation had effect on the effectiveness of the bauxite to interact with the phosphoricAtorney Docket No.: 40688-0015-PCTacid.

[0185] Referring to FIG. 12, it is shown that greater activation of bauxite resulted in greater phosphate adsorption.

[0186] Referring to FIG. 13, P2O5 availability was compared to activated bauxite content for granules produced via chemical granulation. Granular P2O5 transitioned from water-soluble to citrate-soluble when greater amounts of bauxite were included in the granule. This transition demonstrates that phosphate molecules are interacting with the solid bauxite particles in a controlled fashion.

[0187] Referring to FIG. 14, P2O5 availability was compared with activated bauxite content for granules produced via steam granulation. Granular P2O5 transitioned from water-soluble to citrate-soluble when greater amounts of bauxite were included in the granule. This transition demonstrates that phosphate molecules are interacting with the solid bauxite particles in a controlled fashion. However, this transition occurs more slowly when granules are produced via steam granulation rather than chemical granulation, further demonstrating that the quantity of crystalline water removed from the bauxite lattice plays a significant role in the quantity of phosphate that will be interacted with.

[0188] Referring to FIG. 15, a comparison of the percent of phosphate release from granules produced via chemical granulation with different bauxite inclusion rates over a 66-day period showed that as bauxite inclusion increased within the granules, the rate of phosphate release was slowed.

[0189] Table 6. Select Characteristics of Tested Bauxites

[0190] Referring to FIG. 16, the crystalline water loss during chemical granulation of each of the evaluated bauxites was calculated. To standardize manufacturing, dryer temperatures were allAtorney Docket No.: 40688-0015-PCTtargeted at 450 °C, and bauxites were input at 30% on a dry manufacturing basis.

[0191] Referring to FIG. 17, the loss-on-ignition of each of the bauxites present in the granules following chemical granulation was calculated. The differences suggest that different bauxites will be “activated” to different levels while undergoing the same process due primarily to bauxite physicochemical characteristics.

[0192] Referring to FIG. 18, the differences in the propensity to volatilize crystalline water from lattices for the various evaluated bauxites were measured. Bauxite #1 exhibits a lower loss-on-ignition (“LOI”) at temperatures lower than those for Bauxite #2 and Bauxite #3, indicating an increased propensity for activation. These differences suggest that iron oxide content may play a role in the propensity of bauxite to activate.

[0193] Referring to FIG. 19, activated bauxite content and the reduction in ammonia input into the chemical granulation process from the expected were correlated. Granulation was achievable without substantially reducing ammonia input in this experiment.

[0194] Referring to FIG. 20, the calculated ammonia reduction based on the ammoniaphosphoric acid imbalance as determined via titration of granules exiting the granulator was compared to the activated bauxite content of the granules. Despite no reduction in ammonia input (FIG. 18), a clear trend of increasing ammonia reduction is apparent as activated bauxite content increased for all three tested bauxites. This trend indicates that greater amounts of free unreacted ammonia must be present in the granules as greater amounts of bauxite are included, suggesting that the bauxites are outcompeting the ammonia molecules for phosphoric acid sites. Ultimately, this result indicates that ammonia levels should non-intuitively be reduced when co-granulating with bauxites.

[0195] Referring to FIG. 21, the calculated ammonia reduction based on the ammoniaphosphoric acid imbalance was determined by total P2O5 and total nitrogen analyses in comparison to the activated bauxite content in the finished granules. Despite no reduction in ammonia input (FIG. 18), a clear trend of increasing ammonia reduction was apparent as activated bauxite content increased for all three tested bauxites. Since the trend of maintaining free unreacted ammonia within the granules remained immediately following granulation (FIG. 19), this suggests that aAttorney Docket No.: 40688-0015-PCTconsiderable proportion of the unreacted ammonia was volatilized throughout the manufacturing process. Due to the environmental consequences of this ammonia volatilization, reduction of ammonia inputs proportionally to bauxite inputs would be desirable, contrary to what would be expected.

[0196] Referring to FIGS. 22-24, the percentage of water-soluble P2O5, citrate-soluble P2O5, and citrate-insoluble P2O5 present out of total P2O5 in the granules produced via chemical granulation of (FIG. 22) Bauxite #1, (FIG. 23) Bauxite #2, and (FIG. 24) Bauxite #3 were measured. Bauxite #1 showed the greatest propensity to transition from water-soluble to citrate-soluble P2O5 as bauxite content increased, indicating that the level of bauxite activation played a role in the controlled-release properties of phosphate.

[0197] Table 7 presents a comparison of the characteristics of each of the produced granules. There were no deleterious effects on granule quality from the inclusion of any of the three evaluated bauxites.

[0198] Table 7. Characteristics of the Produced GranulesAtorney Docket No.: 40688-0015-PCT

[0199] Referring to FIG. 25, the granulation efficiency of Bauxite #1-MAP, Bauxite 1-MAP, and Bauxite # 1 -MAP were measured by the proportion of oversize, on-size, and undersize granules that were produced upon exiting the rotary dryer. These results suggest that achieving granulatability above 50% bauxite inclusion may present scalability issues under the examined conditions.

[0200] Following the three studies described above, four additional granulation studies were performed (studies 4-6), three at a large commercial plant and one at the IFDC on a small-scale pilot plant (“SSPP”) (Study 7). The generic configuration for these plants is represented in FIG. 1 , as well. The granulation studies performed at the large commercial plant were performed on a similar-style setup, though the facility was much larger. The system was designed to handle approximately 100 times the capacity and throughput of the IFDC LSPP._The granulation Study performed at the IFDC SSPP was also performed on a similar-style setup, though the facility was smaller than the LSPP. The system was designed to handle approximately 20 times less capacity and throughput than the IFDC LSPP.

[0201] Studies 4-6

[0202] Bauxite was introduced into a commercial ammoniation-granulation process similar to that performed in Study 1 at a rate that allowed the citrate-available P2O5 measurement to be approximately 39% (between 20-30% input). All three of these studies were performed as manufacturing runs, and technicians were constantly adjusting inputs and other manufacturing parameters to achieve the desired P2O5 levels. The time-dependent parameter variations allowed for post-analysis of the run to determine product quality and effect of parameters on product characteristics.

[0203] Study 7

[0204] Triple superphosphate (TSP) was produced on the system via phosphate rock acidulation from phosphoric acid in a pre-mixing tank. Bauxite was co-fed alongside the phosphate rock into the pre-acidulation tank at varying input inclusion rates (20%, 30%, 40%).

[0205] Analysis of Studies 1-7Atorney Docket No.: 40688-0015-PCT

[0206] Referring to FIG. 26, in Study 1 , it was demonstrated that adding bauxite increased the production rate when manufactured at pilot scale (at the IFDC). It appears that there is a general trend that more bauxite causes greater increases in production rate.

[0207] Referring to FIG. 27, and in reference to Table 6, testing of three different bauxites (tests performed at 20.6% bauxite inclusion) demonstrated increased production rate of ammonium phosphate fertilizer at pilot-scale (at the IFDC), with Bauxite #1 showing the greatest increase. This suggests, in reference to FIGS. 16-24, that even though some bauxites may activate more easily than other bauxites, the effect on the production rate is the same.

[0208] Referring to FIG. 28 and Table 8, Studies 4-6 demonstrated the production rate increases for ammonium phosphate fertilizers upon addition of bauxite at production-scale.

[0209] Table 8: Production Scale MAP formation with Bauxite #1 at an inclusion of about 30%.

[0210] Referring to FIG. 29, during Studies 4-6 it was demonstrated that bauxite addition reduced the number and duration of manufacturing shutdown events for ammonium phosphate fertilizer production.

[0211] Referring to FIG. 30, during Studies 4-6 manufacturing production rate benefits were compounded when considering the reduction of manufacturing shutdown events.

[0212] Referring to FIG. 31 and Table 8, lower recycle: product ratios during manufacturing typically lead to increased production rates; however, as demonstrated, production rates wereAtorney Docket No.: 40688-0015-PCTinstead independent of recycle:product ratios.

[0213] Referring to Table 9, the production rate increases decreased as N:P ratios increased, but production rate increases are still seen all the way until N:P ratios are greater 2.50, since 25.7 MT / hr since was the production rate of MAP.

[0214] Table 9. Production Rate versus N:P Ratio>

[0215] Table 10 demonstrates that granule product quality was maintained with the addition of bauxite.

[0216] Table 10: Granule Characteristics.

[0217] Tabic 11 demonstrates that increase in production rate was attributable to an effect of the crystalline water loss from the bauxite structure during manufacturing. In cases where no crystalline water loss was observed, production rates were similar to MAP. In cases whereAtorney Docket No.: 40688-0015-PCTcrystalline water loss (activation) was observed, production rates increased substantially.

[0218] Table 11. Production Rate relative to Crystalline Water

[0219] Referring to FIG. 32, higher burner temperatures led to greater crystalline water loss during manufacturing. This indicates that manufacturing conditions may be leveraged to better improve production rate.

[0220] Referring to FIGS. 33-38, manufacturing conditions may exploit “bauxite activation” to improve production rate. Theoretically, this means that all conditions that improved “activation” should improve production rate (e.g., lower pH, higher manufacturing temperature, increased water, the use of steam, addition of sulfuric acid, lower pre-neutralizer N:P ratio).

[0221] Referring to FIGS. 39 and 40, unexpectedly it was discovered that during commercial scale production of MAP when using a pre-neutralizer, lowering the N:P ratio increased the rate of production.

[0222] Referring to Table 12, increasing sulfuric acid input led to an increase in production rate, likely due to the increase in bauxite crystalline water loss.

[0223] Table 12: Sulfuric Acid Input versus Production Rate.<<

[0224] Referring to FIG. 41, pilot-scale production of TSP with Bauxite #1 (inclusion at 20.6%) demonstrated that increased production rate also occurred when manufacturing tripleAtorney Docket No.: 40688-0015-PCTsuperphosphate (not only ammonium phosphates) at pilot scale.

[0225] Referring to FIGS. 42 and 43, laboratory-scale production of TSP with Bauxite #1 (inclusion at 0-40%) demonstrated that increased production rate also occurred when manufacturing triple superphosphate at laboratory scale.

[0226] While the foregoing specification illustrates and describes exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

Atorney Docket No.: 40688-0015-PCTCLAIMSWhat is claimed is:

1. A method for the manufacture of a phosphate-based fertilizer, comprising:(a) exposing a bauxite to an acid to form a mixture, the mixture including a phosphate source;(b) activating the bauxite in situ by removal of crystalline water from the bauxite; (c) binding phosphate from the phosphate source to the bauxite; and(d) recycling the mixture in a mixer to form the phosphate-based fertilizer as a plurality of granules,wherein there is an increased throughput of at least 5% relative to a comparative fertilizer production process that is an otherwise identical fertilizer production process lacking in situ activation of the bauxite, and the increased throughput is independent of recycle:product ratio.

2. The method of claim 1, wherein the activating of the bauxite in situ includes an activation technique selected from the group consisting of calcining the bauxite in a dryer burner above 375 °C, acidifying the mixture to a pH below 5.5, increasing water content of the mixture during granulation to at least about 13.5 wt%, steaming the mixture during granulation, and combinations thereof.

3. The method of claim 2, wherein increasing the water content of the mixture during granulation to at least about 13.5 wt% increases the increased throughput of at least 5% increases to at least 7%.

4. The method of claim 1, wherein the phosphate source is the acid.

5. The method of claim 1 , wherein binding the phosphate to the bauxite includes chemisorbing the phosphate to the bauxite.

6. The method of claim 1, wherein the phosphate-based fertilizer is selected from the group selected from single super phosphate, double super phosphate, triple super phosphate, or combinations thereof.

7. The method of claim 1, wherein the acid is selected from the group consisting of phosphoric, sulfuric, nitric, boric acid, and combinations thereof.Atorney Docket No.: 40688-0015-PCT8. The method of claim 1, wherein the phosphate-based fertilizer is a nitrogen-phosphorous- potassium or nitrogen-phosphorous fertilizer, the acid includes phosphoric acid and exposing the bauxite to the acid to form the mixture further includes exposing the bauxite to a base along with the acid to form the mixture.

9. The method of claim 8, wherein the phosphate-based fertilizer is selected from the group consisting of monoammonium phosphate, diammonium phosphate, nitrophosphate, or combinations thereof.

10. The method of claim 8, wherein the nitrogen-phosphorous-potassium or nitrogen-phosphorous fertilizer has anN:P ratio ofbetween 0.5:1 to 2.5:1.

11. The method of claim 10, wherein the acid and the base arc added into a prc-ncutralizcr, the pre-neutralizer having an N:P ratio from about 0.4:1 to about 0.8:1, and the nitrogen- phosphorous-potassium or nitrogen-phosphorous fertilizer has an N:P ratio from about 0.7:1 to about 1.2:1.

12. The method of claim 8, wherein the base is ammonia.

13. The method of claim 8, wherein the phosphoric acid mixed with the bauxite to form the mixture is at least 10% less than the comparative fertilizer production process lacking in situ activation of the bauxite.

14. The method of claim 1, wherein the phosphate -based fertilizer has increased citrate-soluble P2O5 relative to the comparative fertilizer production process.

15. The method of claim 1, wherein the phosphate-based fertilizer has a lower viscosity relative to the comparative phosphate -based fertilizer produced by the comparative fertilizer production process.

16. The method of claim 1, wherein the bauxite has an initial moisture content prior to activation of about 12 wt% to about 19 wt%.

17. The method of claim 1, wherein shutdown events are reduced by at least about one-third relative to the comparative fertilizer production process.

18. The method of claim 1, wherein the method has reduced attrition of the plurality of granules relative to the comparative fertilizer production process.Atorney Docket No.: 40688-0015-PCT19. The method of claim 1, wherein the bauxite is a pre-activated bauxite prior to the further in situ activating of the bauxite by the removal of crystalline water from the bauxite.

20. The method of claim 1, wherein recycling the mixture in the mixer exerts a force of impact of a granule of the mixture on the mixer sufficient to sever loosely held material on that granule such that granule size is increased through accretion, and the force of impact of the granule of the mixture on the mixer is generated by a velocity of impact of about 6 m / s to about 9 ni / s.

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