An environment-friendly product for the disposal of used oil generated by quarries and other mining operations, developed by commercial explosives and blasting solutions developer AEL Mining Services, is expected to help the mining industry prepare for the carbon tax that is expected to be implemented in South Africa on January 1, 2017.

The company has developed a blasting product, the core ingredient of which is manufactured by converting used oil from various industrial processes, machinery and vehicles into eco-emulsions using a chemical process. The inclusion of used oil was officially launched in April 2008. These eco-emulsions become explosive only when mixed with a sensitiser, making the product extremely stable.

The company notes that the development work on evaluating alternative sources of used oil started in 2000. “Identifying a reliable source of used oil was the biggest challenge initially,” says AEL product manager for surface bulk and packaged explosives Hendrik Botha. Establishing a basic understanding of the nature of recycled (used) oils and the various contaminants that will affect emulsion stability was one of the main reasons why the roll-out of the project took some time to finalise.

He adds that the biggest challenge of this project was including a used material in the emulsion formulation, while ensuring that a good-quality product is supplied to AEL customers.

The development of a detailed quality plan and verification procedure was thus essential in reaching this goal and took a number of years to put in place. This plan is constantly being monitored and evaluated to timeously identify contaminants in the used oil to ensure that downstream customers get the best possible emulsion product at the most cost-effective price offering, he adds.

Recent development work, which started in 2014, has enabled AEL to introduce used oils into the emulsions in a number of ways. The company is able to implement limited refining to remove volatiles, a process which entails removing volatile elements from used oil in an energy efficient manner and introducing it into the fuel phase as part of the emulsion manufacturing process. This produces a stable eco-emulsion with properties similar to the virgin oil emulsions.

A settlement process, which occurs on the mining site where sediments are settled, further enables AEL to clean up the used oil produced to make an eco-emulsion that is used within a shortened period after plant manufacture. The company can also use used oil generated on site, and introduce it into the emulsion through an inline injection point on the mobile manufacturing unit as the blast holes are charged. Alternatively, oil can be introduced onto the ammonium nitrate porous prill by means of a dosing nozzle as the blast holes are charged. All these methods provide flexibility for the customer in disposing of used oil effectively and in an environment-friendly manner.

Botha states that companies can dispose of used oil in a number of ways, but he points out that none of these are as environment friendly as AEL’s solution. He notes that the used oil can be dumped, burned or refined for reintroduction into vehicles. However, harmful gases are released into the atmosphere by burning this oil and the refinery process is expensive and has its own carbon emissions.

“ The best way to get rid of this used oil is through chemical destruction. We use the oil in explosives that are oxygen negative; therefore, the noxious fumes released by the blast are also consumed by the blast, rather than emitted into the atmosphere. In addition, employees are not exposed to dangerous gases during the process,” he explains.

Botha elaborates that AEL’s original formulation used virgin oil and, as a result, the impurities in the used oil need to be neutralised by an emulsifier, making the product as stable and sensitive to the detonation process as it was when using the original formulation.

AEL can, thus, reuse a significant amount of oil that would otherwise have been discarded, while helping mines and quarries reduce the carbon emissions associated with transporting and safely disposing of the oil. Botha notes that AEL’s solution to used oil disposal is not only environmentally sustainable but will also be cost effective when South Africa’s proposed carbon tax comes into effect.

The draft Carbon Tax Bill was published on November 2, 2015, and aims to put a price on the environmental and economic damages caused by excessive greenhouse-gas (GHG) emissions, thereby encouraging firms and consumers to use cleaner technologies.

The Bill forms part of a system for implementing government policy on climate change as outlined in the 2011 National Climate Change Response Policy and the National Development Plan. The Bill has been designed to ensure that its overall impact will be revenue neutral up to 2020 and demonstrates South Africa’s commitment to reducing GHG emissions by 34% by 2020 and by 42% by 2025.

To date, the draft Bill has received 90 comments that are being taken into consideration for its revision.