CASE STUDY

ESTABLISHING 6 VAT LEACHING TANKS FOR GOLD PROCESSING PLANT

Scaling up a gold VAT leaching operation into a small-scale plant with 6 leaching tanks requires translating lab/pilot test knowledge into a fully functional, compliant, and profitable gold recovery operation.

Below is a detailed breakdown of key steps with examples, specifically for someone starting their own gold VAT leaching plant.

1) Review Lab & Pilot Test Results

Objective: To Confirm that your ore is economically leachable using cyanide and determine optimal conditions.

DATA

Conduct laboratory leach tests (using 1–5 kg ore samples) to determine:

- Gold recovery % (e.g., 80–90%)

- Optimal particle size (e.g., -6 mm crushed)

- Leach time (e.g., 48–72 hours)

- Cyanide & lime dosage

- Ore behavior (oxidized or refractory)

RESULT (Assumed):

- Recovery: 88%

- Retention time: 72 hrs

- Cyanide: 0.5 kg/ton

- pH: Maintain at 10.5 (with lime)

- Crushed ore size: 80% passing 6 mm

2) Process Design

Objective: Design a system that replicates and scales up lab results.

Key Areas:

- Tank size: Decide based on daily ore throughput.

- Number of tanks: You chose 6 tanks.

- Tank material: Concrete (lined) or steel

- Flow design: Use batch or semi-continuous loading

RESULT

- Ore processed per batch: 10 tons per vat

- Each tank holds: 10 tons → 60 tons total

- Retention: 3 days per batch

- Process 20 tons/day (2 tanks loaded daily)

3) Infrastructure Setup

Objective: Build physical and utility infrastructure.

Site Requirements:

- Secure land (safe from flooding, near ore source)

- Water source (for mixing and washing)

- Power (for pumps, lighting, possibly crushing)

Structures to Build:

- 6 leaching tanks (1.5 m deep, 3 m diameter)

- Ore yard

- Crushing area

- Sluice or vibrating screen

- Solution tanks (pregnant & barren)

- Recovery room (carbon columns or zinc box)

4) Reagent Management

Objective: Ensure correct chemical usage and safety.

What You Need:

- Cyanide (NaCN)

- Hydrated lime (Ca(OH)₂) to maintain pH

- Safety storage containers (labelled)

- Spill kits and PPE

DATA

- For 10 tons ore:

- Cyanide: 5 kg

- Lime: 10–15 kg

- Mixed with water in a dosing tank and pumped into vats

5) Health, Safety & Environment (HSE)

Objective: Meet safety standards to avoid legal, environmental, or health issues.

What to Do:

- Train workers in cyanide handling

- Use PPE: gloves, goggles, boots, masks

- Construct bund walls around tanks to prevent spillage

- Build tailings pit for safe discharge

- Install emergency showers

6) Operational Planning

Objective: Establish daily routines, staffing, and processes.

Manpower:

- 1 Plant Supervisor

- 3–5 Operators (feeding, mixing, cleaning)

- 1 Chemist or Lab Technician (even basic testing)

- 1 Security Guard

Operation Steps:

1. Crush ore to -6 mm

2. Load 10 tons into each vat

3. Add lime and cyanide solution

4. Wait 3 days (leaching)

5. Drain pregnant solution

6. Recover gold (carbon or zinc)

7. Wash and discharge tailings

7) Monitoring & Optimization

Objective: Adjust processes to improve performance over time.

Key Monitoring Parameters:

- pH (Target: 10.5–11)

- Cyanide concentration (0.05–0.1%)

- Gold in solution (check every 24 hrs)

- Recovery rate

DATA

After first cycle:

- Gold recovery: 75%

- Adjust retention to 84 hours

- Use finer crush to -4 mm next batch

8) Recovery Method

- Carbon in Column (CIC): Good for small operations

- Zinc Precipitation: If you use Merrill-Crowe type system

9) Gold Smelting:

After recovery, smelt gold into dore bars using:

- Smelting furnace

- Flux (borax, soda ash)

- Crucibles

Estimated Budget

NOTE:

- Work with a metallurgist or experienced consultant at the start

- Keep detailed records

- Recycle barren solution where possible

- Consider licensing and environmental permits with local authorities (Tanzania: TMAA, NEMC, etc.)

PLANT OPERATION AND ESTIMATED BUDGET

Process Flow Diagram

Crushing → Screening → Vat Leaching → Solution Collection → Gold Recovery → Smelting → Dore Bars

Preparation

1. Ore Receiving Yard

2. Crushing Unit → Reduce ore to -6 mm

3. Screening (optional)→ Remove oversize

4. Loading into Vats (6 Tanks)

5. Add Lime & Cyanide Solution

6. Leaching (72 hrs per vat)

7. Collect Pregnant Solution

8. Gold Recovery (Carbon or Zinc)

9. Smelting → Dore Bars

10. Tailings Disposal

Business Plan

❖ Executive Summary

- Establish a 6-Vat gold leaching plant in site

- Target: 60 tons crushed ore per cycle (10 tons per tank)

- Recovery method: Vat leaching + Carbon

❖ Business Objectives

- Recover gold from oxidized ore at small scale

- Operate legally with environmental compliance

- Scale production within 2 years

❖ Market Opportunity

- Availability of artisanal ore

- Growing demand for gold in local & international markets

❖ Technical Plan

- Technology: Manual crushing, vat leaching, basic lab

- Inputs: Crushed ore, lime, cyanide, water, carbon

- Skilled labor: Metallurgist (consultant), operators, technician

❖ Financial Plan (Assumed)

❖ Revenue Forecast

- Gold grade: 5 g/t

- Recovery: 80%

- Gold per batch: ~24 grams

- Monthly production: ~240g

- Revenue (240g @ TZS 160,000/g): TZS 38.4M

THANK YOU