Polyhalite Pelletization via HPGR and Starch Binding
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Solution Overview
Problem
Existing processes for forming pellets from evaporite minerals like Polyhalite face challenges in achieving reliable water uptake control, uniform binding, and energy-efficient crushing, particularly on an industrial scale, with issues related to the hygroscopic nature of the minerals and machinery inefficiencies.
Innovation Solution
A method involving the use of high pressure grinding rolls (HPGR) to efficiently crush Polyhalite into a fine powder, followed by air classification to separate fractions, and then mixing the powder with pre-gelled starch to form pellets using a pan pelletiser, which reduces energy consumption and ensures uniform pelletization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional crushers (cone crushers, attritor mills, ball mills) are used to form powder from raw mineral, then powder can be produced, but the crushing process is highly energy intensive
Solution Approach 1:
The patent extracts and removes the high-energy-intensity crushing stage from the conventional process by using High Pressure Grinding Rolls (HPGR) instead. HPGR technology applies compressive forces to fracture particles, achieving powder formation with significantly lower energy consumption compared to traditional mechanical crushing methods like cone crushers or ball mills.
Solution Approach 2:
The patent changes the fundamental parameter of crushing mechanism from low-pressure mechanical impact to high-pressure compression. By applying pressures in the range of 10-50 MPa through HPGR, the process achieves efficient particle size reduction with lower energy input, transforming the crushing paradigm from impact-based to compression-based particle fracture.
2Manufacturing precision
If a screen is used to separate the output of the crushing stage by size, then larger pieces can be excluded, but the screen can become clogged especially if the powder is damp
Solution Approach 1:
The patent replaces the mechanical screening system with an air classification system. An air stream is used to separate particles based on their size and aerodynamic properties, eliminating the mechanical contact between damp powder and screen surfaces that causes clogging. This substitution maintains precise size separation while avoiding operational disruptions.
Solution Approach 2:
The patent employs pneumatic principles by using a controlled air stream to achieve particle separation. The air current creates differential drag forces on particles of different sizes, allowing fine particles to be carried away while larger particles settle. This pneumatic separation method is particularly effective for damp powders that would clog mechanical screens.
3Ease of manufacture
If evaporite mineral powder is spread in raw crushed form, then processing costs are minimised, but the mineral takes time to break down delaying bioavailability
Solution Approach 1:
The patent performs preliminary size reduction and processing of the evaporite mineral before application to the soil. By pre-crushing and pelletizing the mineral into fine, uniform particles, the breakdown time in the soil is significantly reduced while maintaining cost-effectiveness through efficient HPGR technology and air classification, eliminating the need for expensive alternative processing methods.
4Ease of operation
If chipped form Polyhalite is applied, then it can be applied more easily, but it is of irregular shape and size making uniform application difficult
Solution Approach 1:
The patent changes the physical parameters of the mineral product by transforming irregular chipped material into uniform pellets through a controlled process involving HPGR crushing, air classification, and pelletization. This parameter transformation maintains ease of application while achieving uniform size and shape, eliminating the trade-off between application ease and uniformity.
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 method significantly reduces energy usage, extends HPGR roller lifespan, and achieves high throughput with efficient pelletization, resulting in uniformly sized, stable pellets with improved bioavailability for agricultural use.
Implementation Method 1
exposing starch to water at greater than 70° C. so as to at least partially gel the starch
Implementation Method 2
A method involving the use of high pressure grinding rolls (HPGR) to efficiently crush Polyhalite into a fine powder
Implementation Method 3
followed by air classification to separate fractions
Implementation Method 4
mixing the powder with pre-gelled starch to form pellets using a pan pelletiser
Data Source
AI summary
A method for forming pellets of an evaporite mineral, the method comprising: exposing starch to water at greater than 70° C. so as to at least partially gel the starch; while the gelled starch is substantially fully hydrated, mixing the starch with a powder of the evaporite mineral to form a mixture; and pelletising the mixture.