Fly Ash Proppant Sintering for Low Density High Strength
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Solution Overview
Problem
Existing proppant materials face challenges in achieving a balance between crush resistance and low specific gravity, often resulting in high density and costly nano-scale raw materials, with irregular particle shapes reducing effectiveness in hydraulic fracturing operations.
Innovation Solution
A method of manufacturing proppant materials using a core comprising fly ash, bauxite, and clay, where the granules are coated with bauxite to prevent stickiness during sintering, allowing for high-strength, low-density ceramic proppants with spherical shapes and improved adherence, eliminating the need for reducing and oxidizing heat treatments and nano-scale materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If sintered bauxite is used as proppant material to achieve high crush resistance, then the proppant particles become hard and crush resistant, but the specific gravity increases to 2.5-3.5 making it heavy and expensive
Solution Approach 1:
The patent uses composite materials by combining fly ash (60-95 wt%), bauxite (5-30 wt%), and clay (5-20 wt%) to create a proppant that achieves high crush resistance while maintaining low specific gravity (2.0-2.5). The composite structure allows the material to benefit from the strength-providing bauxite while the bulk volume is filled with lighter fly ash, resolving the contradiction between strength and weight.
Solution Approach 2:
The patent changes the compositional parameters of the proppant material by substituting heavy bauxite with lighter fly ash as the primary component. This parameter change in material composition allows achieving the required crush resistance through optimized formulation rather than relying on heavy materials, thus reducing specific gravity while maintaining strength.
2Weight of moving object
If fly ash is used as the primary component to reduce density, then the specific gravity decreases to 2.0-2.5, but the granules become sticky during sintering
Solution Approach 1:
The patent introduces bauxite and clay as intermediary materials that act as binders and coating agents for the fly ash granules. These intermediaries prevent the stickiness problem during sintering by providing a stable surface and controlling the sintering behavior, allowing fly ash to be used as the primary low-density component without manufacturing defects.
Solution Approach 2:
The patent optimizes the compositional parameters by precisely controlling the ratios of fly ash (60-95%), bauxite (5-30%), and clay (5-20%). This parameter optimization ensures the mixture has adequate flowability and reduced stickiness during sintering while maintaining the low density benefit of high fly ash content.
3Strength
If bauxite content is increased to improve crush resistance, then the strength increases, but the cost increases due to strict quality requirements and limited sources
Solution Approach 1:
The patent replaces expensive, high-quality bauxite with cheaper, more readily available fly ash as the primary proppant material. Fly ash is a waste product from coal combustion that is abundant and low-cost, allowing the formulation to achieve required strength at lower material cost while reducing dependence on limited high-quality bauxite sources.
Solution Approach 2:
The patent creates a composite formulation where fly ash serves as the bulk filler providing volume at low cost, while controlled amounts of bauxite (5-30%) and clay (5-20%) provide the necessary strength enhancement. This composite approach reduces overall material cost compared to using high-quality bauxite alone while achieving comparable or superior performance.
4Ease of operation
If proppant particles are made spherical to maximize flow and spacing, then fluid flow improves, but maintaining spherical shape with high crush resistance requires complex manufacturing processes
Solution Approach 1:
The patent employs spheroidality by forming the proppant particles as spherical granules during the mixing and sintering process. The spherical shape maximizes particle spacing in the fracture and improves fluid flow characteristics, while the sintering process naturally maintains this shape without requiring complex post-processing equipment.
Solution Approach 2:
The patent optimizes sintering parameters (temperature, time, atmosphere) to achieve complete sintering of spherical granules without deformation. By controlling these parameters, the process maintains the simple spherical geometry while achieving the required crush resistance, avoiding the need for complex manufacturing steps to preserve shape.
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 method produces proppant materials with high crush resistance and low density, reducing environmental waste by recycling fly ash, and achieving compressive strengths exceeding 10,000 psi, while being cost-effective and environmentally friendly.
Implementation Method 1
the granules are sintered to form high-strength, low-density ceramic proppant particles
Data Source
AI summary
A relatively low density, high strength round proppant material having (i) a round core made of a sintered mixture of fly ash and clay or, in some instances, fly ash, clay, and bauxite; and (ii) an outer shell made of sintered bauxite, and a method of making the same.