1. Overview 

Production Output

• Global Output: 2.635 million ounces (Moz) of gold produced in 2023.

• Regional Contribution (Africa): Produced 1.541 Moz of gold, the largest regional contributor to the Group.

• Operational Scale: Managed a total energy consumption of 22.63 petajoules and water withdrawal of 29,932 ML in 2023.

Operations & Infrastructure

• Facility: Full-scale Reverse Osmosis (RO) facility on an active mine site.

• Purpose: Treating mine process wastewater to recycle water and meet strict discharge limits.

• Scale: The operation manages feed waters with sulfate concentrations ranging from 500  to 10,000 mg/L

2. Problem

Highly variable water chemistry creates a significant risk of scaling (mineral precipitation), specifically gypsum, which can block and damage RO membranes

2.1 Lack of precision in reagent dosing and yield optimisation

Conventional monitoring relies on periodic laboratory sampling, which is too slow to capture sudden quality swings. Lab results are often snapshot measurements that miss diurnal fluctuations of 1,000 to 1,500  occurring within hours

2.2 Sulfate-induced scaling events lead to:

• Increased differential pressure and plant alarms.

• Unplanned downtime for membrane replacement or aggressive cleaning.

• Inefficient chemical dosing based on assumptions

3. Solution

The ABAIA® sensor system was sequentially moved across the Reverse Osmosis (RO) treatment chain to continuously monitor sulfate at critical process points. Specifically, sensors were placed to monitor the RO feed (MP2) and RO brine concentrate (MP1) to manage incoming loads and scaling risk at the point of highest saturation. The main problem areas and technical solutions are:

• Predictive Scaling Control: Continuously monitor the concentrate/brine stream (MP1) to detect scaling onset up to 12 hours before plant differential pressure alarms are triggered. This early warning system allows operators to proactively adjust recovery rates or dosing to prevent severe membrane fouling and avoid unplanned downtime.

• RO Membrane Integrity Monitoring: Provide continuous sulfate sensing at the RO permeate (MP4) to detect any breakthrough of contaminants eg., sudden spikes above the normal <300 mg/L baseline. This serves as a predictive tool for the RO units, instantly identifying system stress or membrane failure that lab tests would likely miss.

3.2 What is the business case and the ROI ?

Our use-case  is Water process monitoring for RO units.

Real-time monitoring acts as a shield for high-value membrane assets, preventing catastrophic fouling events.

• Early Warning System: The system successfully captured 4 major scaling events up to 12 hours before they occurred, preventing sudden blockages and unscheduled shutdowns.

• Membrane Longevity: Proactive maintenance extended the operational life of RO membranes, resulting in a 20% reduction in annual replacement costs and saving €58,960 per year.

3.2.2 OPEX Reduction: Chemicals & Energy

Precision data allows the plant to move away from conservative over-dosing and high-pressure compensation.

• Antiscalant Optimization: A 15.6% reduction in chemical consumption was achieved by replacing static dosing with sensor-driven automation. This translates to €227,860 in annual savings.

• Energy Efficiency: By preventing gypsum buildup, the plant avoids the over-pressurization of High-Pressure (HP) pumps. This reduction in hydraulic resistance lowered energy consumption by 6.8%, yielding €141,018 in annual savings.

3.2.3 Water Recovery & Sustainability

Dynamic sulfate monitoring allows the system to push recovery limits without risking membrane scaling.

• System Management: An estimated 2% improvement in recovery rates enables higher water reuse.

• Cost Displacement: This optimization reduces the reliance on expensive freshwater or desalinated supplies (priced at €0.84/L) and minimizes the volume of untreated water discharge.

Table 1: Total cost savings 

• Gross Annual Savings/Gains: €458,074 p.a.

• Price Watergenics ( 1 Sensor ): € 45,000  p.a.

• Annual ROI:   10.18x