Pozzolanic Salt Cover Layer for Rainwater Infiltration

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Solution Overview

Problem

Existing methods for covering tailings salt heaps are inefficient in preventing rainwater infiltration, require large quantities of materials, and struggle with maintaining stability and self-regeneration, leading to accumulation of water and deformation issues.

Innovation Solution

A mixture of tailings salts with a mineral additive having hydraulic and/or pozzolanic setting properties is applied to the heap, which absorbs rainwater, forms an insoluble infiltration-inhibiting layer that regenerates over time, and maintains stability and shape.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a thick cover layer is applied to prevent rainwater infiltration, then infiltration prevention is improved, but the quantity of material required increases significantly

Engineering Contradiction:
Improverainwater infiltrationVSAvoidcover material quantity
Core Design Contradiction:
Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The invention changes the chemical composition parameters of the cover layer by incorporating pozzolanic materials (such as fly ash, silica fume, or natural pozzolana) mixed with cement. This chemical modification enables the formation of a dense, low-permeability matrix that achieves effective infiltration prevention at much thinner layer thicknesses (5-20 cm) compared to conventional covers, thereby reducing the quantity of cover material required while maintaining or improving infiltration protection

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses composite materials consisting of cementitious binders combined with pozzolanic additives and potentially supplementary materials like crushed brick or slag. This composite approach creates a cover layer with optimized properties: the cement provides initial binding strength, while the pozzolanic materials react over time to form additional binding compounds that reduce permeability. The composite structure achieves superior infiltration resistance with reduced material thickness and quantity

Inventive Principle:
Principle #40Composite materials

2Stability of the object's composition

If conventional cover materials are used, then initial covering is achieved, but the cover lacks self-regeneration capability and stability over time

Engineering Contradiction:
Improvecover stabilityVSAvoidcover longevity
Core Design Contradiction:
Stability of the object's compositionVSDuration of action of stationary object

Solution Approach 1:

The invention implements self-service through the pozzolanic reaction mechanism. The pozzolanic materials in the cover layer react with calcium hydroxide (produced by cement hydration) over time to form additional calcium silicate hydrate and calcium aluminate hydrate compounds. This ongoing chemical reaction continuously densifies the cover matrix, reduces permeability, and self-repairs minor defects without external intervention, enabling the cover to maintain and even improve its protective properties throughout its service life

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention ensures continuity of useful action through the prolonged pozzolanic reaction process that continues for years after cover application. Unlike conventional covers that reach their performance plateau quickly, the pozzolanic-based cover continuously develops binding compounds, progressively reducing water infiltration and maintaining structural integrity. This continuous chemical action ensures long-term stability and durability of the cover layer

Inventive Principle:
Principle #20Continuity of useful action

3Area of stationary object

If steep slopes are used to minimize land area, then land area requirement is reduced, but heap stability and deformation resistance deteriorate

Engineering Contradiction:
Improveland areaVSAvoidheap stability
Core Design Contradiction:
Area of stationary objectVSStability of the object's composition

Solution Approach 1:

The invention applies a thin-film approach by using the low-permeability pozzolanic-cement cover layer (5-20 cm thick) as a protective shell on the heap surface. This thin film provides effective rainwater infiltration prevention without adding significant weight or volume, allowing the heap to maintain steep slopes. The cover acts as a protective membrane that prevents water-induced softening and deformation while minimizing land area requirements

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The invention changes the mechanical parameters of the cover layer through the pozzolanic reaction products, which create a dense, cohesive matrix with high shear strength. This modified material property allows the cover to adhere firmly to steep slope surfaces and resist gravitational sliding forces. The chemical bonding developed through pozzolanic reactions provides enhanced cohesion that maintains stability even on steeply sloped heaps with minimal land footprint

Inventive Principle:
Principle #35Parameter changes

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 effectively reduces tailings water accumulation, allows for continuous regeneration of the cover, maintains heap stability, and enables greening, while requiring minimal additional materials and area, ensuring long-term effectiveness and adaptability.

Implementation Method 1

the pozzolanically and/or hydraulically setting properties of the additive bind a portion of the water

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

mineral additive, sparingly soluble to insoluble, with hydraulically and/or pozzolanically setting properties

Methodology Applied
Scientific EffectHydraulic setting:

Implementation Method 3

mineral additive, sparingly soluble to insoluble, with hydraulically and/or pozzolanically setting properties

Methodology Applied
Scientific EffectPozzolanic setting:

Implementation Method 4

Over time, leaching processes occur at the surface of the spoil heap, resulting in the formation of a surface layer (infiltration barrier layer) consisting primarily of insoluble components

Methodology Applied
Scientific EffectLeaching:

Data Source

PatentEP2576091B1Residue salt dump with a cover layer
Publication Date: 2020.11.25 KS MINERALS & AGRI GMBH
  • EP2576091B1 patent drawingFigure 1~4

AI summary

The invention relates to a mixture to be applied onto a dump of residue salt as an infiltration-inhibiting layer for reducing the occurrence of pile waste water caused by precipitation, wherein the mixture comprises residue salt and a mineral additive which is poorly soluble to insoluble and has hydraulically and/or pozzolanically setting properties.