Scale-Inhibiting Polymers for Cyanide Leaching

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Solution Overview

Problem

Scale or mineral deposit formation is a common problem in mining processes, particularly in gold and silver extraction methods like heap leaching and vat leaching, where alkaline cyanide solutions are used, leading to inefficiencies and equipment damage due to the formation of insoluble salts like calcium carbonate.

Innovation Solution

The use of scale-inhibiting polymers comprising sulfonate-containing monomers such as 2-sulfoethyl methacrylate and maleic acid, either as copolymers or terpolymers, added to aqueous alkali cyanide solutions to prevent scale formation by interfering with crystal nucleation and growth, thereby reducing mineral deposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If alkaline cyanide solutions are used for gold extraction, then metal dissolution efficiency is improved, but scale formation increases

Engineering Contradiction:
Improvemetal dissolution efficiencyVSAvoidscale formation
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

A scale-inhibiting polymer is introduced as an intermediary substance between the alkaline cyanide solution and the metal ions. The polymer contains sulfonate-containing monomer units and maleic acid units that interact with calcium and other metal ions to prevent scale formation while allowing gold dissolution to proceed efficiently

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical parameters of the leaching solution by adding specific polymers with controlled molecular weights (1,000-30,000 Daltons) and specific monomer compositions. This modification allows the solution to maintain its gold-dissolving capability while gaining scale-inhibiting properties

Inventive Principle:
Principle #35Parameter changes

2Reliability

If polymer concentration is increased to improve scale inhibition, then scale formation is reduced, but solution viscosity increases

Engineering Contradiction:
Improvescale inhibition efficacyVSAvoidsolution viscosity
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The invention optimizes the polymer concentration parameter to achieve effective scale inhibition at low dosages. By selecting polymers with specific molecular weights (1,000-30,000 Daltons) and optimizing concentration, the solution maintains low viscosity while achieving reliable scale inhibition

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The scale-inhibiting polymer is designed as a composite structure containing both sulfonate-containing monomer units (for metal ion interaction) and maleic acid units (for structural stability). This composite structure achieves high scale inhibition efficacy at low concentrations without excessive viscosity increase

Inventive Principle:
Principle #40Composite materials

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 described method effectively inhibits scale formation, as demonstrated by significant reductions in calcium carbonate deposition, maintaining system efficiency and preventing equipment damage, with the polymers showing high efficacy even at low dosages.

Implementation Method 1

The use of scale-inhibiting polymers comprising sulfonate-containing monomers such as 2-sulfoethyl methacrylate and maleic acid, either as copolymers or terpolymers, added to aqueous alkali cyanide solutions to prevent scale formation by interfering with crystal nucleation and growth

Methodology Applied
Scientific EffectCrystal nucleation inhibition: Nucleation

Implementation Method 2

The use of scale-inhibiting polymers comprising sulfonate-containing monomers such as 2-sulfoethyl methacrylate and maleic acid, either as copolymers or terpolymers, added to aqueous alkali cyanide solutions to prevent scale formation by interfering with crystal nucleation and growth

Methodology Applied
Scientific EffectCrystal growth inhibition: Crystallisation

Data Source

PatentEP2737109B1Scale-inhibiting polymers and methods for preventing scale formation
Publication Date: 2022.11.30 KEMIRA OY
  • EP2737109B1 patent drawingFigure 1
  • EP2737109B1 patent drawingFigure 2
  • EP2737109B1 patent drawingFigure 3

AI summary

Scale-inhibiting polymers, compositions comprising the scale-inhibiting polymers and methods for preventing scale formation in circulating fluid are provided. The scale- inhibiting polymers comprise two or more recurring units wherein at least one recurring unit is a sulfonate-containing monomer and at least one recurring unit is selected from the group consisting of maleic acid, itaconic acid, acrylamide, acrylic acid, methacrylic acid, polyethylene glycol monomethacrylate, maleic anhydride, t-butyl acrylamide, hydroxy propyl acrylate, hydroxy ethyl methacrylate, hydroxy propyl methacrylate, and vinyl phosphonic acid. The polymers, compositions and methods may be used in mining processes including metal extraction from mineral ores.