Urea-Protected Solid Thiosulfate Fertilizer Drying
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Solution Overview
Problem
Existing fertilizer compositions based on thiosulfates, polysulfides, and bisulfites are prone to thermal and oxidative degradation, making them difficult to dry and store effectively, especially in solid form.
Innovation Solution
The addition of urea-containing compounds to aqueous solutions of thiosulfates, polysulfides, and bisulfites prior to drying helps prevent air oxidation and degradation, allowing for the production of stable solid fertilizer-grade materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If thiosulfates, polysulfides, and bisulfites are dried to produce solid fertilizers, then solid fertilizer form is achieved, but thermal and oxidative degradation occurs during drying
Solution Approach 1:
Urea-containing compounds are added to the aqueous thiosulfate/polysulfide/bisulfite solution before drying to prevent oxidation and degradation during the drying process. This preliminary protective action ensures the compounds remain stable when converted to solid fertilizer form.
Solution Approach 2:
Urea acts as an intermediary substance that protects the thiosulfates, polysulfides, and bisulfites from oxidative degradation during drying. The urea-containing compounds interfere with the oxidation process, allowing the sulfur compounds to be dried without significant degradation.
2Quantity of substance
If conventional drying methods are used on thiosulfate solutions, then water removal is achieved, but product degradation and discoloration occur
Solution Approach 1:
Urea-containing compounds are added before the drying process to prevent oxidation and degradation. This preliminary protective measure ensures that when water is removed through conventional drying methods, the product maintains its quality and color stability without significant degradation.
3Stability of the object's composition
If thiosulfates are stored as liquid solutions, then solubility is maintained, but storage stability and shelf life are reduced
Solution Approach 1:
The invention transitions the thiosulfate/polysulfide/bisulfite compounds from liquid solution phase to solid fertilizer phase through drying. This phase transition, when performed in the presence of urea-containing compounds, results in stable solid fertilizers with extended shelf life that maintain solubility when applied.
4Ease of operation
If solid thiosulfate fertilizers are produced without protective agents, then easy handling is achieved, but hygroscopicity and instability increase
Solution Approach 1:
The invention creates a composite fertilizer material combining thiosulfates, polysulfides, or bisulfites with urea-containing compounds. This composite structure provides easy handling in solid form while the urea component protects against hygroscopicity and oxidative instability during storage.
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
This approach enables the production of stable, non-hygroscopic solid fertilizers with extended shelf life, which are compatible with standard NPK fertilizers and can be easily handled and stored.
Implementation Method 1
The addition of urea-containing compounds to aqueous solutions of thiosulfates, polysulfides, and bisulfites prior to drying helps prevent air oxidation and degradation
Data Source
AI summary
Provided in the invention are thiosulfate-urea based products (IIa) and/or a polysulfide-urea based products (IIb) and/or a (bi)sulfite-urea based products (IIc) suitable for use in fertilizers and comprising: one or more urea-containing compounds (a), one or more compounds (b), optionally, one or more urease (c1) and/or nitrification (c2) inhibitors that are different from compounds (b), and/or optionally, one or more additives (d) that are different from any of the above compounds, wherein the amount of water (e) in the product (II) is less than about 10 wt %, preferably less than about 5 wt %, wherein compounds (a) are selected from urea (a1) and/or from urea-aldehyde products (a2) and/or from urea-triazone compounds (a3), wherein compounds (b) are selected from thiosulfates (b1) and/or from polysulfides (b2) and/or from (bi)sulfites (b3). An advantage of products of the invention is that only minimal amounts of degradation products of compounds (b) are formed. Products of the invention can be made in various forms and in different ways. All of the materials of the invention are suitable for use in fertilizers and blend well with solid and liquid fertilizers standardly used.