Gold Processing: Reagent Roles (High-Level)

How to use this guide

This is a procurement-oriented overview of what reagents do in common gold flowsheets and what should be specified on RFQs (strength, purity, delivery form, documentation, and supply controls). It is intentionally high-level: site design, operating parameters, and emergency response must follow your mine’s engineering standards, EHS program, and supplier SDS.

Where it fits (the flowsheet map)

Gold plants vary, but most processing routes include a subset of these stages:

• Comminution: crushing & grinding (sets liberation and downstream reagent demand).
• Pre-concentration (optional): gravity recovery and/or flotation (reduces mass to leach and changes reagent suite).
• Leaching: dissolution of gold into solution (often followed by adsorption).
• Recovery: adsorption on carbon (CIP/CIL), elution, electrowinning, and refining.
• Solid–liquid separation: thickening/filtration, tailings management, and water recycle.
• Detoxification: treatment of tailings/solutions to meet discharge or storage requirements.

Key decision factors (what changes the reagent plan)

• Ore mineralogy: free-milling vs refractory; sulfides; clay content; preg-robbing carbonaceous material.
• Process route: gravity / flotation / direct leach; CIP vs CIL; heap vs tank leach (different logistics and dosing stability needs).
• Water chemistry: recycle ratios, hardness/alkalinity, dissolved metals, suspended solids (affects reagent consumption and scaling).
• EHS & compliance constraints: permitted discharge criteria, transport restrictions, on-site storage limits, and stewardship requirements.
• Reliability needs: remote location, winterization, lead times, and critical spares (dosing, containment, monitoring).

Reagent roles (high-level)

The table below maps common reagent families to their typical role and what procurement should verify. Not every plant uses every item.

What procurement should specify (buyer checklist)

Regardless of which reagent family is being purchased, strong RFQs include information you can verify on receipt and in audits.

• Identity & traceability: product name/grade, manufacturer, country of origin (if required), and batch/lot traceability.
• Strength / assay basis: how concentration is defined (mass %, active basis, purity basis) and acceptable tolerance.
• Impurity controls: impurities that matter to your process (e.g., insolubles, metals, carbonate/chloride where relevant), plus a clear COA list.
• Delivery form: solid vs solution, packaging (drum/IBC/bulk/ISO), temperature constraints, and unloading interface (pumps/hoses/couplings).
• Documentation: current SDS, COA per lot, transport documentation, and any site-required statements (quality, stewardship, compliance).
• Shelf life & storage: storage temperature range, segregation notes, and what constitutes “expired” for acceptance.
• Supply & resilience: lead time, safety stock plan, alternate origins, and critical spares for associated dosing hardware.

Acceptance checks (chemicals + packaging)

On receipt, verify what you can objectively verify — before the product enters storage tanks.

• Seals & labeling: intact closures, correct hazard labeling, readable batch/lot info.
• Packaging condition: no bulging, corrosion, leakage, or contamination signs; correct liner type where applicable.
• COA match: batch/lot on COA matches the delivered lot; verify assay/strength and key impurities listed on your RFQ.
• Basic receiving tests: density, appearance, and other simple checks where appropriate (per your QA plan).
• Documentation completeness: current SDS (revision date), transport papers, and any site gate-entry requirements.

Handling & storage (high-level EHS considerations)

• Segregation: store incompatibles separately; follow site chemical segregation rules and SDS guidance.
• Secondary containment: bunding sized for credible spill scenarios; compatible lining materials.
• Transfer controls: closed transfer where feasible, splash control, drip trays, and clearly labeled transfer points.
• Training & access control: restricted access for high-hazard materials; trained operators and documented procedures.
• Emergency readiness: site-specific emergency response plan, communication protocol, and medical response pathway per your site policy.

Troubleshooting signals (what to check first)

If metallurgical performance or compliance indicators drift, these are common early signals and procurement-relevant checks.

1) Higher-than-expected reagent consumption

• Common drivers: ore change, recycle water change, poor dosing calibration, concentration drift, or increased losses to solids.
• First checks: verify delivered assay vs spec, confirm dosing calibration records, review any recent packaging/handling changes that could affect concentration.

2) Lower recovery / slower kinetics

• Common drivers: mineralogy shift, competing reactions, insufficient mass transfer, adsorption media condition, or solution chemistry drift.
• First checks: confirm supply consistency (same grade/source), verify COA impurities, check that storage and make-up practices match supplier guidance.

3) Thickener or tailings upsets (cloudy overflow, poor settling)

• Common drivers: polymer make-up quality, water chemistry changes, solids PSD changes, or mixing/aging issues.
• First checks: confirm polymer grade/lot, storage condition, and make-up procedure; verify receiving QA is consistent across deliveries.

4) Scaling/plugging in lines or injection points

• Common drivers: recycle chemistry, incompatible dilution order, dead legs, or underperforming scale-control program.
• First checks: review impurity changes, confirm correct product grade, and validate packaging integrity (no contamination).

RFQ notes (what to include)

• Process route (gravity/flotation/leach/CIP-CIL), basic ore type, and major constraints (water recycle, climate, remote location).
• Reagent family + required delivery form (solid/solution), expected monthly volume, and storage limits.
• Required documentation: COA per lot, current SDS, traceability, and any site stewardship/compliance requirements.
• Acceptance checks: assay tolerance, impurity list, packaging/liner expectations, and labeling requirements.
• Logistics: destination, Incoterms, lead time, safety stock expectations, and unloading interface details.
• Service expectations: technical support for receiving QA, storage guidance, and supply continuity planning.

Educational content only. Always follow site EHS rules and the supplier SDS for safe use. This guide does not replace engineering design, operator training, or site emergency response procedures.