How to Safely Store Sulphuric Acid at a Mine Site: Tanks, Bunding and PPE
Storing sulphuric acid at a mine site is one of the highest-risk activities in any copper leach or SX-EW operation. Concentrated acid is highly corrosive, reacts violently with water and can cause severe burns in seconds. Yet many plants on the Copperbelt and in the DRC still run with ageing tanks, damaged bunds and incomplete PPE. This guide explains how to store sulphuric acid safely, from tank selection and bunding to PPE and emergency response.
Why Safe Sulphuric Acid Storage Matters
Most leach operations hold only a few days of acid on site, so storage tanks are constantly being filled and drawn down. Every transfer, valve and pipe joint is a possible leak point. A single failure can lead to:
- Serious chemical burns and eye injuries to workers
- Soil and groundwater contamination
- Regulatory penalties and plant shutdowns
- Loss of expensive acid stock
- Damage to nearby equipment and structures
Good storage design and discipline prevent almost all of these incidents.
1. Choose the Right Tank Material
The correct tank material depends on the acid concentration.
- Concentrated acid (93–98%): Carbon steel tanks are the industry standard. Concentrated acid forms a thin iron sulphate layer on the steel surface that slows further corrosion.
- Dilute acid: Carbon steel corrodes rapidly in dilute acid. Use suitable plastic tanks (such as HDPE), lined tanks or specified alloys, as recommended by your engineer.
- Avoid galvanised steel and aluminium: Acid attacks zinc and aluminium quickly.
The biggest danger for carbon steel tanks is water getting into concentrated acid. Rainwater or moisture dilutes the acid at the surface, which speeds up corrosion and produces hydrogen gas. Keep tanks sealed and fit vents with a desiccant (drying) breather where appropriate.
2. Build Proper Bunding (Secondary Containment)
Every sulphuric acid tank must sit inside a bund, which is a walled containment area that holds acid if the tank leaks or ruptures.
- Size the bund to hold at least 110% of the largest tank's volume.
- Line the floor and walls with an acid-resistant coating or lining, because plain concrete is attacked by acid.
- Do not install open drains in the bund. Remove rainwater manually after checking it for acid contamination.
- Keep the bund clean and free of rubbish, pumps that are not in use and stored materials.
- Never store incompatible chemicals, such as alkalis, cyanide or flammables, in the same bund.
3. Fit the Correct Tank Accessories
- Level indicators: Use reliable level gauges or radar level sensors to avoid overfilling during tanker offloading.
- High-level alarm: An audible alarm warns the offloading team before the tank overflows.
- Vents: Tanks need correctly sized vents to allow air in and out during filling and drawing.
- Isolation valves: Use acid-rated valves on inlets and outlets so leaks can be isolated quickly.
- Labelling: Mark tanks clearly with "Sulphuric Acid", concentration, capacity and hazard signs (UN 1830, Class 8 Corrosive).
4. Control Hydrogen Gas Risk
When acid reacts with steel, especially where water has entered, it can produce hydrogen gas. Hydrogen is flammable and can build up in the top space of a tank.
- Ban smoking, naked flames and sparks near acid tanks.
- Never carry out welding, grinding or other hot work on or near an acid tank without a hot-work permit, gas testing and a proper isolation procedure.
- Treat empty tanks as dangerous, because acid residue can still produce hydrogen.
5. Make Tanker Offloading Safe
Most acid incidents happen during transfers. Set up a dedicated, bunded offloading bay and follow a written procedure for every delivery:
- Check the delivery note and Certificate of Analysis before connecting.
- Confirm the receiving tank has enough free space.
- Inspect hoses, couplings and gaskets for damage.
- Make sure the operator and driver wear full PPE.
- Stay with the transfer at all times. Never leave an offloading unattended.
- Drain and cap hoses safely after offloading.
6. Use the Right PPE
Anyone working near sulphuric acid storage or transfer points should wear:
- Chemical splash goggles and a full face shield
- Acid-resistant gloves (PVC, neoprene or another rated material)
- Acid-resistant suit or apron
- Chemical-resistant gumboots, with trousers worn over the boots
- Respiratory protection where acid mist may be present
Inspect PPE before each use and replace it immediately if it is cracked, stiff or damaged.
7. Prepare for Emergencies
- Install a working safety shower and eyewash station close to the storage and offloading area, and test it weekly.
- Keep spill kits with neutralising agents such as lime or soda ash nearby.
- Display the Safety Data Sheet (SDS) and emergency contact numbers at the tank farm.
- Train workers on first aid: flush skin and eyes with large amounts of water for at least 15 minutes and get medical help immediately.
- Remember the golden rule: always add acid to water, never water to acid.
8. Inspect and Maintain Regularly
Create a simple inspection checklist covering tank walls, welds, valves, gaskets, bund lining, level gauges and safety equipment. Schedule periodic thickness testing of carbon steel tanks to detect corrosion before it becomes a leak. Record every inspection, because these records are also needed for regulatory audits.
Frequently Asked Questions
What type of tank is used to store 98% sulphuric acid?
Carbon steel tanks are commonly used for concentrated (93–98%) sulphuric acid. Dilute acid requires different materials, such as suitable plastics or lined tanks.
How big should a sulphuric acid bund be?
A bund should normally hold at least 110% of the volume of the largest tank inside it.
Why is water dangerous in a sulphuric acid tank?
Water dilutes concentrated acid, which speeds up corrosion of steel tanks, produces hydrogen gas and releases heat.
What should you do if sulphuric acid touches your skin?
Remove contaminated clothing, flush the area with large amounts of water for at least 15 minutes and seek medical attention immediately.
Reliable Acid Supply, Delivered Safely
Safe storage starts with a reliable supplier. G & Y Solutions Limited supplies 98% industrial-grade sulphuric acid to mining operations in Zambia and the DRC, with Certificates of Analysis, proper transport documentation and experienced delivery coordination. Learn more about the challenges of sourcing sulphuric acid in Zambia or read our buyer's guide for DRC mining operations.
📞 Call +260 975 574 784 | 💬 WhatsApp +260 966 807 585 | ✉️ sales@gandysolutions.com
Request a sulphuric acid quotation today →
This article provides general safety guidance only. Always follow the supplier's Safety Data Sheet, your site's safety procedures and applicable regulations.
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