Explosives and initiating systems supplier AEL Mining Services has upgraded its portable emulsion charging unit (PCU) 010 pneumatic stope pump, primarily for use in narrow-reef stopes and tunnels.

The new pump is the tenth iteration in the PCU series, and consists mostly of steel components, whereas, previously, most of the parts in the PCU008 were plastic. The pump’s steel casing, which replaced the plastic one, has improved maintenance turnaround times significantly, according to AEL.

In April, Mining Weekly reported on AEL’s implementation of its underground bulk systems (UBS), which was developed specifically for the challenging deep-level gold mining sector. The PCU010 forms an integral part of this system.

AEL UBS product manager Mark Cross explains that the upgraded unit took about two years to develop and works through the combination of emulsions and sensitisers produced by AEL, which are loaded into separate tanks in the pump, whereafter it is combined in the pumping action to form a sensitised explosive product in the blasthole.

A static mixer at the end of the charging hose and lance ensures that the final product is well mixed, producing an explosive of consistent quality to improve blast performance.

Cross adds that the PCU010 has a built-in bursting disc as an additional safety feature to protect the emulsion matrix from overpressurisation. The pump has fewer working parts, compared with other products on the market, resulting in minimal spares being required and substantially reduced lead time for manufacturing and maintenance.

He notes that the pump is well suited for use in mining tunnels that are smaller than 4 m by 4 m and shorter than 2 m in length.

The PCU010 weighs about 30 kg, is 1 054 mm long, 521 mm wide and 388 mm high, with a flow rate of 20 kg/min. The emulsion tank has a capacity of
15 kg and the sensitiser tank has a capacity of 2 kg. The unit includes a 5 m hose, a static mixer and a lance, which are available in various lengths.

“The product’s development is a result of mines requiring smaller units to operate in narrow reef spaces,” explains Cross, adding that this posed a challenge to engineers, who had to design smaller units that are more robust than previous models and that can operate more effectively in narrow and harsh conditions.

He says the pump has been well received since its initial launch at the 2012 Electra Mining Africa exhibition, which took place at the Nasrec Expo Centre, in Johannesburg.

The pump is being used at gold mines in the Free State; on the West Rand, in Gauteng; and at platinum mines on the eastern limb of the Bushveld Igneous Complex, near the town of Steelpoort, in Mpumalanga.

It is also widely used at mines in Botswana, Zimbabwe and Namibia.

Improving Safety

Cross points out that the mining industry is shifting from using traditional explosives to using chemicals in the form of bagged emulsions. The ammonium nitrate chemical emulsion presents properties, namely a mixer, sensitising agent and a pump, for which detonation in a controlled environment is essential.

“Unlike traditional cartridge explosives, these emulsions require all three items to work in unison to create a detonative product, which helps eliminate many problems, such as pilferage of mine explosives and illegal mining activities,” he says.

Cross adds that use of the emulsions can also assist in preventing automatic teller machine (ATM) bombings, which often are carried out using traditional cartridge explosives that are stolen from mines.

The bright-green emulsion produced by the pump, with its high-visibilty shock tube, is now produced using a bright-yellow dye, which ensures that miners can easily spot the emulsions, thus reducing the risk of harm to mineworkers handling the explosives.

Cross notes that stealing all three items is incredibly difficult, as they are not easy to work with and they also have a limited life span, which will discourage many would-be ATM bombers.

Opencast Uses

Although the pump is primarily used in deep-level operations, it has been used in opencast mining operations where the mine has small orebodies that need to be blasted. It can also be used for trenching, quarrying and civil blasting on opencast mines as a replacement for package explosives.