Environmental mining solutions provider FlowCentric Mining Technologies’s Rhino Evaporator dual-purpose fog cannon can suppress dust and also enhances the natural evaporation process by fracturing water into smaller size droplets.

Owing to the high concentrations of dissolved heavy metals and sulphate in mine wastewater, it may not be discharged into public streams, which presents storage and management cost issues for mine. The Rhino Evaporator can assist with wastewater removal, and ensures more efficient treatment of wastewater, thereby reducing potential storage costs, while resolving problems caused by water pollution as a result of mining activities, such as acid mine drainage.

FlowCentric Mining Technologies’ business development manager Andre Nell says it look extensive research and development to manufacture an improved misting cannon that could match and surpass its competitors.

International sales and marketing director Charles Bothma boasts that the 22 kw Rhino is anticipated to be the most popular. The machine uses a high-pressure pump with a flow rate of 45 m3/h, 24 specialised nozzles and a 22 kw motor, is about ten times more cost effective than water treatment and about 15 times faster than evaporation ponds in ideal weather conditions. Case studies have shown evaporation percentages of approximately 50% and higher percentages can be achieved in dry weather conditions.

The 22 kw pump pushes water through the nozzles to create a fine mist that is blown into the air by the pump, which, Bothma asserts, can produce similar results to a 30 kw unit, thus providing significant savings on electricity costs.

Bothma adds that the evaporator’s design offers several improvements on those of conventional misting cannons, such as the high-density aluminium impellers, which produce lower sound levels, or its improved barrel shape, which allows for higher airflow.

The 22 kw unit is relatively compact, as it is only 2.36 m wide, 2.43 m long and 2.69 m high, with a weight of about 800 kg, making it easy to transport.

Nell notes that it is available in 11 kw, 22 kw, 45 kw, and 75 kw models, and that all evaporators undergo hydrophobic treatment before leaving the factory. Hydrophobic treatment is a water repellant spray that prevents build-up of sulphates and corrosion.

FlowCentric Mining Technologies is a Level 2 black economic-empowerment contributor and uses the services of qualified water professionals; it is also in a position to design and commission a complete evaporation environment system, taking into consideration the client’s specific water analysis and on-site conditions.

The company has been involved in water treatment since its inception four years ago, and Nell says it is a market leader in water evaporation, having sold misting cannons to most of the leaders in the coal, quarry and petrochemicals industries. Six of the units sold are used by Henning Crushers for dust control in Namibia. FlowCentric Mining Technologies also offers maintenance contracts with local spares availability.

Water Treatment

FlowCentric Mining Technologies also offers several water and wastewater treatment solutions, including metal removal, neutralisation and a “patented desalination method”. This desalination method, according to FlowCentric water science project leader Tabani Mtombeni, combines reverse osmosis (RO) and freeze desalination (FD), in a complementary way.

“RO systems inherently suffer from scaling, owing to saturation, and thus precipitation of dissolved species, as more water is recovered. [Additionally,] the build-up of osmotic pressure, owing to the increased concentration of the rejected species, limits the overall water recovery,” he explains.

FD processes inherently suffer from product ice contamination by the mother liquor and, combined with the stochastic nature of the ice nucleation process, control of the whole process is a fine art, Mtombeni adds.

He asserts that FlowCentric Mining Technologies’ method manipulates the chemistry of the water to minimise scaling and drive the composition towards “well-behaved species” before using the FD stage to treat the brine produced by the RO stage.

Mtombeni adds that, while RO and FD processes are well known, it is the combination of the two that is unique and relatively new.

Dust Suppression

Another key product for the company is a water-soluble dust-suppression palliative, RDC 20, which is designed to bind fine-soil particles to form larger and heavier particles, which are less likely to become airborne.

Bothma claims that RDC 20 can be used for controlling or managing several soil conditions, including dust pollution, base failure and soil erosion. Additionally, it requires no special equipment or handling precautions, and can be easily incorporated into routine dust-suppression procedures.

It is nontoxic and biodegradable, and is more cost effective than other chemical dust suppressants. It can also be used as a road treatment solution to improve grip on dust roads.

Nell says it was developed in South Africa and tested by occupational health service consultants Associated Risk Management Services, which also compiled the material safety data sheets (MSDSs), before it was introduced to the market in 2011.

Bothma adds that, as the MSDSs have to be approved by the mines’ health and safety departments, employees and residents can be assured that the concentrate is environment friendly.

• [Editor:Juan]