Mining Backfill Binder Composition for Acidic Sulfur-Rich Tailings
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Solution Overview
Problem
The existing binders used in backfill materials for underground mines, such as CEM I and CEM II/B cements, are not suitable for sulfur-rich tailings due to their poor resistance to acidic conditions and high energy consumption, leading to reduced mechanical strength and increased CO2 emissions.
Innovation Solution
A binder comprising Portland clinker, calcium sulfate, and blast furnace slag, with a portion replaced by biomass ash, which maintains or improves mechanical properties and reduces energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If CEM I type cement is used as binder, then good mechanical properties are achieved, but resistance to acidic conditions deteriorates
Solution Approach 1:
The patent uses a composite binder system combining CEM I cement with ground granulated blastfurnace slag (GGBS) and calcium sulfate. This composite approach leverages the high early strength of CEM I while the GGBS provides acid resistance through its lower calcium/silica ratio hydrates and reduced calcium hydroxide content, thus resolving the contradiction between mechanical strength and acid resistance.
Solution Approach 2:
The patent modifies the chemical composition parameters of the binder by controlling the proportions of CEM I cement (30-70% by mass), GGBS (20-60% by mass), and calcium sulfate (10-30% by mass). By adjusting these parameters, the binder achieves both adequate mechanical strength from CEM I and improved acid resistance from the modified composition with less calcium hydroxide.
2Ease of manufacture
If CEM II/B type cement is used to reduce cost, then economic efficiency improves, but mechanical strength deteriorates
Solution Approach 1:
The patent creates a composite binder that combines the cost advantages of CEM II/B cement with the strength-enhancing properties of GGBS and calcium sulfate. The synergistic interaction between these components allows the use of more economical cement types while maintaining or improving mechanical strength through the contribution of GGBS and calcium sulfate hydrates.
Solution Approach 2:
The patent optimizes the mass proportions of binder components (CEM I or CEM II/B cement, GGBS, and calcium sulfate) to achieve the desired balance between cost efficiency and mechanical strength. By controlling these composition parameters, the binder formulation attains competitive pricing while meeting mechanical performance requirements for backfill materials.
3Reliability
If Portland clinker and blast furnace slag are used extensively, then binder performance improves, but CO2 emissions and energy consumption increase
Solution Approach 1:
The patent modifies the binder composition by incorporating calcium sulfate (10-30% by mass) alongside optimized proportions of Portland clinker (30-70% CEM I or CEM II/B) and GGBS (20-60% by mass). This parameter adjustment reduces the total clinker content required while maintaining binder performance through the contributing hydrates of GGBS and calcium sulfate, thereby lowering CO2 emissions and energy consumption associated with clinker production.
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 new binder achieves improved compressive strength and lower CO2 emissions, making it suitable for sulfur-rich tailings while reducing the need for blast furnace slag and Portland clinker.
Implementation Method 1
hydrates of blast furnace slag-rich binders
Implementation Method 2
association of Portland clinker, calcium sulfate, blast furnace slag and a biomass ash
Implementation Method 3
hydrates of blast furnace slag-rich binders are well known to resist far better to these conditions thanks to the lower calcium / silica ratio of their calcium silicate hydrates
Data Source
AI summary
The disclosure relates to a binder comprising from 3% to 15% w/w of Portland clinker, from 7% to 20% w/w of calcium sulfate, from 5% to 35% w/w of a biomass ash, and from 40% to 80% w/w of blast furnace slag. The disclosure further relates to a composition comprising said binder and to a process of preparing a backfill material, comprising mixing mine tailings, the binder according to the disclosure and water.