Hydrophobic Liquid Agglomeration for Ultrafine Coal Dewatering
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Solution Overview
Problem
Existing methods for cleaning fine coal particles are inefficient below 10-15 μm in size, and dewatering processes result in high moisture content, making it difficult to handle and increasing shipping and energy costs.
Innovation Solution
A hydrophobic liquid is added to an aqueous medium under high-shear agitation to form agglomerates with hydrophobic particles, followed by a second hydrophobic liquid to release entrapped water, allowing for efficient separation of hydrophobic and hydrophilic particles and significant moisture reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If flotation is used to clean fine coal particles, then separation of hydrophobic coal from hydrophilic mineral matter is achieved, but efficiency deteriorates rapidly below 10-15 μm particle size
Solution Approach 1:
The invention changes the physical-chemical parameters of the separation process by using oil agglomeration instead of traditional flotation. Oil droplets are introduced to coat hydrophobic coal particles, fundamentally altering the separation mechanism from air-bubble attachment to oil-coating and agglomeration, enabling effective separation of ultrafine particles below 10-15 μm that are too fine for conventional flotation
Solution Approach 2:
Oil acts as an intermediary substance between the hydrophobic coal particles and the hydrophilic mineral matter. The oil selectively coats the coal particles, creating agglomerates that can be easily separated from the mineral matter through density differences or filtration, serving as a mediating agent that enables separation at ultrafine particle sizes
2Quantity of substance
If dewatering processes are applied to remove process water from clean coal product, then moisture content is reduced, but handling difficulty and shipping costs increase due to high-capillary pressure of trapped water
Solution Approach 1:
The invention extracts process water from the coal product during the separation process itself rather than requiring subsequent dewatering operations. The oil-coated agglomerates are separated in a manner that naturally drains trapped water, extracting the harmful moisture component before the coal needs to be handled or shipped
Solution Approach 2:
The separation process is designed to perform dewatering as a preliminary action before the coal product enters handling and shipping stages. By removing the majority of process water during the agglomeration and separation steps, the coal product is delivered in a lower-moisture state that is easier to handle and ship without requiring additional dewatering equipment or operations
3Quantity of substance
If thermal drying is used to achieve low moisture levels in coal product, then moisture content is reduced to acceptable levels, but energy consumption increases due to high shipping costs and combustion efficiency losses
Solution Approach 1:
The invention performs moisture removal as a preliminary action during the separation process, delivering a lower-moisture coal product that requires minimal or no thermal drying. By extracting process water during agglomeration and separation rather than relying on post-processing thermal drying, the method eliminates the high energy consumption associated with heating and evaporating large amounts of water
Solution Approach 2:
The invention replaces thermal drying (a thermal process) with mechanical separation methods. Oil-coated coal agglomerates are separated from mineral matter using density differences, filtration, or other mechanical means that naturally drain trapped water, substituting high-energy thermal processing with low-energy mechanical separation to achieve the same dewatering objective
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 process achieves over 90% removal of hydrophilic particles and 95% of water from hydrophobic particles, reducing moisture levels and enabling energy-efficient drying without excessive heat.
Implementation Method 1
Hydrophobic coal particles are selectively collected by a rising stream of air bubbles and form a froth phase on the surface of the aqueous phase, leaving the hydrophilic mineral matter behind. Higher-rank coal particles are usually hydrophobic and, therefore, can be attracted to air bubbles that are also hydrophobic via a mechanism known as hydrophobic interaction.
Implementation Method 2
Under conditions of high-shear agitation, the oil breaks up into small droplets, collide with particles, adsorb selectively on coal by hydrophobic interaction, form pendular bridges with neighboring coal particles, and form agglomerates.
Implementation Method 3
In flotation, air bubbles are dispersed in water in which fine coal and mineral matter are suspended. Hydrophobic coal particles are selectively collected by a rising stream of air bubbles and form a froth phase on the surface of the aqueous phase
Implementation Method 4
The agglomerates formed by these processes are usually large enough to be separated from the mineral matter dispersed in water by simple screening.
Data Source
AI summary
A process for cleaning and dewatering hydrophobic particulate materials is presented. The process is performed in two steps: 1) agglomeration of the hydrophobic particles in a first hydrophobic liquid/aqueous mixture; followed by 2) dispersion of the agglomerates in a second hydrophobic liquid to release the water trapped within the agglomerates along with the entrained hydrophilic particles.