Contents
How to use this guide
This is a practical decision aid for mining & minerals processing teams. Use it to align procurement, EHS, and operations on selection criteria, acceptance checks, and monitoring signals. When you have site-specific constraints (recycle ratio, pH window, temperature, evaporation/concentration steps), share them so we can propose compliant, supply-ready options.
Mining reality: scale issues rarely come from a single number. They usually come from where chemistry changes (pH shifts, CO2 stripping, heating, evaporation, mixing streams) and where solids concentrate (recycle loops, filters, heat exchangers, RO/NF membranes, spray systems).
Where it fits
- Process goal: protect uptime, maintain flow/heat transfer, reduce cleanup downtime, stabilize reagent consumption.
- Operating window: pH setpoints, temperature, residence time, and shear (pipes, pumps, cyclones, sprays).
- Interfaces: pipelines, valves, heat exchangers, spray nozzles, clarifiers/thickeners, filters, membranes.
- Constraints: recycle water quality limits, discharge limits, product quality/spec, site restricted substances list.
Common scale types in mining water
A quick way to avoid wrong chemistry: match the deposit type to the operating condition that triggers it.
| Scale type (common) | Typical trigger | Where it shows up | Program levers |
|---|---|---|---|
| Calcium carbonate | Higher pH, CO2 stripping, heating | Warm surfaces, spray systems, recycle loops | pH/alkalinity control, threshold inhibitors, dispersants, softening upstream |
| Calcium sulfate (gypsum) | High sulfate + concentration (evaporation/recycle) | Pipes, filters, RO/NF pretreatment, evaporative systems | Antiscalants tuned for sulfate, manage concentration factor, upstream precipitation where possible |
| Barium/strontium sulfate | Mixing incompatible waters (barite risk), concentration | Injection points, mixing zones, membranes | Specialized antiscalants, control mixing, remove Ba/Sr upstream if feasible |
| Silica / magnesium silicate | High silica, high pH, high Mg, heating/concentration | Heat exchangers, membranes, high-recycle circuits | Silica-focused antiscalants, pH management, avoid high-pH Mg + silica zones, solids control |
| Iron scale / mixed mineral deposits | Oxidation, pH shifts, carryover solids | Dead legs, low-flow zones, equipment with oxygen ingress | Redox/pH control, dispersants, solids management, filtration |
Fast diagnostic: If scale forms mainly after a pH increase or CO2 stripping → think carbonate.
If it worsens with recycle/concentration factor → think sulfate/silica risk.
If it appears right at a mixing tee → think incompatible water blending (Ba/Sr sulfate or local supersaturation).
Quick selection map (antiscalant vs pH vs precipitation)
| Your constraint | Primary lever | Why | Watch-outs |
|---|---|---|---|
| Process requires a fixed pH window (metallurgy or reagent performance) | Antiscalant + dispersant | Lets you keep pH while reducing precipitation tendency and deposit adhesion | Choose chemistry compatible with flocculants and downstream solids handling |
| You can adjust pH without harming recovery/quality | pH control | Often the lowest-cost way to reduce carbonate/silicate precipitation risk | Local high-pH zones at injection points can still precipitate—mixing matters |
| High hardness / high alkalinity makeup and you can treat upstream | Precipitation/softening upstream | Remove scale-formers before they enter recycle-heavy circuits | Sludge handling, solids carryover, and polymer compatibility become critical |
| Sulfate scaling under high concentration factor | Sulfate-focused antiscalant + manage concentration factor | Gypsum/barite risks are strongly concentration-driven | Confirm mixing points and temperature effects; watch membrane differential pressure |
| Silica-limited circuit (membranes / hot surfaces) | Silica program (antiscalant + pH discipline) | Silica behavior is sensitive to pH, temperature, and Mg | Avoid “hidden” high-pH zones and Mg pickup; ensure solids control is stable |
Program building blocks
1) Know the “problem stream” and the “trigger step”
- Problem stream: the exact water feeding the fouling surface (not just makeup or pond water).
- Trigger step: the moment chemistry changes (pH adjust, heating, evaporation, CO2 loss, blending).
- Concentration factor: where dissolved ions concentrate (recycle loops, thickeners, RO, evaporation).
2) Choose the chemistry “family” by risk profile
| Need | Common approach | Best fit examples |
|---|---|---|
| Threshold inhibition | Antiscalant blends (polymer / phosphonate programs) | Carbonate and sulfate control in recycle-heavy circuits |
| Dispersion (keep fines/deposit precursors suspended) | Dispersants (often polymeric) | Mixed mineral deposits, iron/silt-related fouling, sticky scale precursors |
| Precipitation management | Softening / controlled precipitation upstream | Very hard makeup, high alkalinity, limited tolerance for scaling in sensitive equipment |
| pH discipline | pH optimization + mixing best practices | Carbonate & silicate risks where process allows pH movement |
Compatibility check that saves projects: make sure the scale-control chemistry is compatible with your flocculant/coagulant program (settling and clarity KPIs) and does not create downstream filter/membrane fouling.
Monitoring plan (practical)
The best program is the one you can measure and trend. In mining, trending a few signals by stream is usually more valuable than occasional full lab panels.
| What to monitor | Where | Why it matters | Typical cadence |
|---|---|---|---|
| pH + temperature | Before/after pH adjustment; near hot/evaporative units | Scale risk is extremely sensitive to these two parameters | Per shift (or continuous) |
| Hardness + alkalinity | Key recycle streams and makeup | Primary drivers for carbonate scaling and precipitation | Daily to weekly |
| Sulfate + (Ba/Sr if relevant) | Streams impacted by evaporation/recycle or blending | Gypsum/barite risk often increases with concentration factor | Weekly (more during changes) |
| Silica (and Mg) | Membrane feed/hot surfaces/recycle-heavy circuits | Silica scaling and Mg-silicate risk in high-pH or high-T systems | Weekly (more if silica-limited) |
| Differential pressure / flow / energy | Filters, exchangers, membranes, critical lines | Early warning of deposition and fouling | Continuous or daily trend |
| Solids carryover (turbidity/clarity) | Thickener overflow / clarified water | Solids accelerate deposition and consume chemicals | Per shift to daily |
Commissioning tip: pick 2–3 “sentinel points” (e.g., thickener overflow, a recycle header, and the membrane/exchanger inlet)
and trend the same set of parameters for 2–4 weeks before and after changes. This makes root cause obvious.
Troubleshooting signals
If performance drops, these are common early indicators and what to check first:
| Signal | What it often suggests | First checks |
|---|---|---|
| Poor settling / cloudy overflow | Polymer incompatibility, solids carryover, pH drift | Coag/floc doses, pH at mixing points, antiscalant dose vs clarity trend |
| High reagent consumption | Uncontrolled precipitation, poor mixing, changing water blend | Water source changes, recycle ratio, injection location and mixing energy |
| Scaling in lines / nozzle plugging | Local supersaturation at injection points or high-T zones | pH “hot spots,” CO2 stripping zones, heat input, antiscalant feed point |
| Rising differential pressure (filters/membranes/exchangers) | Scale deposition or solids fouling | Compare DP vs turbidity; check sulfate/silica/hardness; validate dose pump and dilution water |
| Frequent cleaning / shorter runtime | Wrong chemistry family, underfeed, or process shift | Deposit analysis, confirm actual stream chemistry at foulant surface, review recent pH/recycle shifts |
Best “one test” if you can do it: deposit analysis from the fouled surface. Even a simple characterization (carbonate vs sulfate vs silica vs mixed) prevents weeks of trial-and-error.
Specification & acceptance checks
When comparing products, ask for the data you can verify on receipt:
| Category | What to request | Why it matters |
|---|---|---|
| Identity | Product name/grade, manufacturer, batch/lot traceability | Consistency and easier troubleshooting when water sources change |
| Quality (COA) | Active % / assay, appearance, density, pH, viscosity (as supplied) | Dose control depends on concentration and physical properties |
| Compatibility statement | Compatibility with common flocculants/coagulants and typical materials of construction | Avoids clarity failures and equipment compatibility surprises |
| Safety | Up-to-date SDS, handling precautions, PPE, storage segregation | Aligns with EHS review and site controls |
| Logistics | Lead time, Incoterms, shelf life, storage temperature range | Prevents degraded product performance due to storage or delays |
| Packaging | Drum/IBC/bulk, closures, liner type (if applicable), labeling compliance | Safe transfers and receiving acceptance checks |
Handling & storage
- Store in original, sealed packaging, away from incompatible materials (follow SDS guidance).
- Use secondary containment and clear labeling in the operating area.
- For transfers: verify hose/seal compatibility; use dedicated transfer equipment where practical.
- For dilution: add product to water per supplier guidance; avoid poor mixing that can create local precipitation zones.
RFQ notes (what to include)
- Water sources and blending: makeup, recycled tailings water, thickener overflow, RO permeate/concentrate, etc.
- Operating pH window(s) by unit operation and any planned pH adjustments (locations + setpoints).
- Temperature profile and any heat exchange/evaporation/concentration steps.
- Key water chemistry: hardness, alkalinity, sulfate, silica (and Mg), TDS/conductivity, suspended solids/turbidity.
- Where scaling occurs (exact equipment/line) and the runtime to failure; any deposit photos or analysis.
- Current reagents in the circuit (coag/floc, collectors, frothers, biocides, corrosion inhibitors).
- Estimated monthly volume, packaging preference, delivery country, and documentation requirements (COA/SDS).
- Any compliance constraints (restricted substances list, discharge limits, site rules).
Need a compliant alternative?
Send your constraints and target performance. We’ll propose options with SDS/COA expectations and procurement-ready specs.
Educational content only. Always follow site EHS rules and the supplier SDS for safe use.