Granular Fertilizer Hardness via Polyhalite Calcination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current fertilizers face challenges in achieving a high enough K2O level, low chloride content, and sufficient hardness, especially when combining potassium and magnesium salts like polyhalite, which are difficult to granulate and result in low K2O levels and high chloride levels in existing granulation processes.
Innovation Solution
A granular fertilizer composition comprising 15-85% potassium sulfate and 85-15% of another salt providing potassium, magnesium, and/or calcium, with a K2O level of at least 18 wt%, chloride level of at most 10 wt%, and magnesium level of at most 10 wt%, achieved through compaction or wet tumbling granulation processes, including the use of binders and calcined forms of polyhalite and schöenite to enhance hardness and flowability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polyhalite and other mixed sulfate salts are used to provide potassium, magnesium, and calcium nutrients, then nutrient balance is improved, but granulation difficulty increases and particle hardness decreases
Solution Approach 1:
The patent applies parameter changes by heating polyhalite to specific temperature ranges (100-400°C, preferably 150-300°C) to modify its physical and chemical properties. This thermal treatment reduces granulation difficulty while maintaining nutrient balance, as the heated polyhalite becomes more amenable to granulation processes without losing its nutritional value.
Solution Approach 2:
The patent uses composite materials by combining heated polyhalite with potassium sulfate in specific ratios (30-70 wt% polyhalite, 70-30 wt% potassium sulfate). This composite approach leverages the nutrient balance of polyhalite while potassium sulfate provides structural support for granulation, resolving the contradiction between nutrient versatility and manufacturing ease.
2Quantity of substance
If polyhalite is used as a coarse material, then magnesium and calcium content is improved, but deformation during granulation becomes difficult and particle hardness is too low
Solution Approach 1:
The patent applies parameter changes through thermal treatment of polyhalite at 100-400°C, which modifies the material's deformation characteristics. This heating process makes the coarse polyhalite particles more pliable during granulation while maintaining their magnesium and calcium content, thereby improving particle hardness without sacrificing nutrient quantity.
Solution Approach 2:
The patent applies preliminary action by pre-heating polyhalite before granulation. This preliminary thermal treatment prepares the material for subsequent granulation processes, making deformation easier and improving particle hardness before the actual granulation occurs, thus resolving the contradiction between maintaining nutrient content and achieving sufficient hardness.
3Quantity of substance
If KCl is used to increase potassium level, then K2O content is improved, but chloride level becomes too high for chloride sensitive crops
Solution Approach 1:
The patent applies parameter changes by substituting KCl with potassium sulfate (K2SO4) as the potassium source. This chemical parameter change eliminates chloride introduction while maintaining potassium delivery, as potassium sulfate provides K2O without the harmful chloride component, thus improving K2O content while controlling chloride levels for chloride-sensitive crops.
4Adaptability or versatility
If evaporite minerals like polyhalite and schöenite are used, then nutrient diversity is improved, but granulation becomes difficult and requires unique compacting conditions
Solution Approach 1:
The patent applies parameter changes through thermal treatment of evaporite minerals at 100-400°C, which simplifies their granulation behavior. This heating modifies the physical properties of polyhalite and schöenite, making them compatible with standard granulation equipment and processes, thereby maintaining nutrient diversity while reducing device and process complexity.
Solution Approach 2:
The patent uses composite materials by combining heated evaporite minerals with potassium sulfate in optimized ratios. This composite formulation creates a material blend that maintains the nutrient diversity of multiple evaporite minerals while potassium sulfate provides granulation-friendly properties, reducing the need for unique compacting conditions and simplifying manufacturing equipment requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides granules with improved hardness, reduced wear, and controlled particle size, ensuring better nutrient balance and flowability, making them suitable for various agricultural applications while minimizing chloride content.
Implementation Method 1
achieved through compaction or wet tumbling granulation processes
Implementation Method 2
achieved through compaction or wet tumbling granulation processes
Implementation Method 3
including the use of binders
Implementation Method 4
including the use of binders and calcined forms of polyhalite and schöenite to enhance hardness
Data Source
AI summary
The present invention relates to a fertilizer in granular form comprising within the same granule a mixture of: (A) From 15 to 85 wt % of a potassium sulfate; and (B) From 85 to 15 wt % of at least one salt that is different from (A) and that provides potassium and/or magnesium and/or calcium and/or sulfate; wherein the fertilizer in granular form has—a potassium level (expressed as K2O) of at least 18 wt %, preferably at least 20 wt %;—a chloride level of at most 10 wt %, preferably at most 5 wt %, more preferably at most 3 wt %;—a magnesium level (expressed as MgO) of at most 10 wt %, preferably at most 9.5 wt %. Materials of the invention are free flowing & combine a good nutrient balance with a good hardness and wear resistance.