HomeBase MetalsWater scarcity: Chemical reagents an effective solution

Water scarcity: Chemical reagents an effective solution

The growing need to conserve water and preserve the environment are quickly becoming priorities for the mining industry.

This has seen an increase in demand for chemical manufacturer and supplier Axis House’s niche brand of water treatment reagents which effectively enable water recycling and in so doing, offer the added benefit of increasing the lifespan of tailing dam facilities, writes LAURA CORNISH.

This article first appeared in Mining Review Africa Issue 6, 2019
Read the full digimag here or subscribe to receive a print copy here

Axis House has effectively been assisting mining companies recycle their water thanks to its Brontë specialised brand of flocculants. 

The Brontë polyacylamide range of flocculants can be used in various dewatering applications from pre-leach to post-leach and as a filter aid for tailings thickeners.

These products ensure the optimum balance between settling velocity, underflow compaction and clarity of the overflow water. They are tailored to suit each operation based on a series of test work.

“The steady increase seen by mines to conserve and reuse their water has more recently resulted in an increase in demand for Brontë – which enables the industry to recycle their water and in doing so reduce their fresh water consumption,” says Axis House technical manager Bernard Oostendorp.

“Recycling water has the added benefit of increasing the lifespan of tailings dams, which has also become a priority for mines following the recent spate of catastrophic tailings dam failures,” he continues.

Explaining how the Brontë range of flocculants works, Oostendorp outlines that charged or uncharged polyacrylamides are added to the pulp after the valuable minerals have been removed. 

These polyacrylamides physically bind with fine particles, creating larger agglomerates. 

“These then settle due to gravity as their size increases. Most of the solids (including fine particles) will settle at the bottom of the thickener leaving the top levels in the tank with clean water, of which 90% is drained out and pumped back into the process.”

So confident is Oostendorp in the Brontë range, that he confirms that after use, water can appear crystal clear, with a count of up to less than 10 nephelometric turbidity units (NTU) than that of solids. (NTU measures the clarity or solids content of the overflow water.

The lower the value, the lower the solids content and the aim is to have minimal NTU units). If water is poorly treated, it can reduce the efficiency of the flotation process and the demand for excess amounts of reagents will consequently increase as well.

“In most cases, with a count of less than 10 NTU, our recycled water is often cleaner than fresh water found underground,” Oostendorp highlights.

With 18 years of experience in the industry, and the company’s professional approach to logistics management, Axis House has reduced stock cover for its clients from 120 days down to 21 days across Africa – and this applies to Brontë as well.

As such the company has become a household name in ‘difficult to reach’ countries such as the DRC which have a high demand for water preservation techniques and technologies.

“Our products are used extensively across most of the base metals mines in the region,” Oostendorp confirms.  

Did you know?

In addition to having a fully equipped laboratory, with milling, flotation, sedimentation, leaching and analytical equipment, situated in South Africa, that enables the company to accurately benchmark alternate reagent suites against each other, Axis House is also constantly monitoring the world chemical market to bring the newest reagents to its clients as soon as they become economically viable.