A record-shattering achievement
By addressing issues of sensitivity and shear, AECI Mining Explosives has successfully delivered a record-breaking 980m Emulsion Vertical Drop System (EVDS) which is 277% deeper than the previous best of 260m. This has been done for Non-Ferrous China Africa’s (NFCA) Chambishi mine in Zambia’s Copperbelt Province, one of the largest underground mines in the country.
The EVDS delivers emulsion to an underground storage facility via a borehole piping system. At 980m, there were two key issues:
The products are shear sensitive and deteriorate when exposed to shear. Pumping over long distances introduces shear which can reduce the product’s useability and lead to pipe blockages
In the event of a pipe blockage in a vertical line, there is a possibility that hydrostatic pressure exceeding the minimum burning pressure will build up, increasing the product’s sensitivity (Shear sensitive liquids change viscosity when under stress or pressure. Some liquids become less viscous with increased force (called shear thinning) and others become more viscous with increased force (called shear thickening).)
AECI Mining Explosives developed a new emulsion that minimises the effects of shear and rheology models that predict flow under specific conditions.
The EVDS was chosen as a means of improving the mine’s cost-effectiveness, particularly in freeing up cage time for increased lifting capacity and more seamless inventory management. Previously, the mine used bulk emulsion cassettes that were loaded on the surface and transported via the cage network to each level. This compromised quality and was costly and time-consuming. Delays caused by cage times, double handling and spillages were commonplace.
The process design and product testing were managed by AECI Mining Explosives and ELB Engineering, the business’s EVDS technology partner, while the Zambian team paved the way for a successful installation and project outcome. To get the ball rolling, AECI Mining Explosives analysed NFCA’s blasting schedule, product demand and space available to provide optimal surface and underground storage capacity and a tailor-made delivery system. Various installation options were considered to meet the mine’s requirements and, importantly, to ensure that the system could be operated safely and sustainably.
The NFCA contract was signed at the end of July 2018 and work commenced on 1 January 2019. The project scope included the supply and delivery of all plant and equipment, the preparation of the site, drilling the borehole, blasting the underground cavities, installation and commissioning. The installation was finalised at the end of January 2020, on time and within budget. On 5 February 2020, the first emulsion was dropped to the 680m mining level followed by a drop to 980m the next day. The system was available at full capacity immediately and continues to operate the same way.
The key benefits for NFCA are:
Improved safety
Seamless inventory control
Reduced interface with explosives
Optimised ordering, delivery and refilling of charging units
Reduced asset wear, maintenance and fuel
Reduced risk of theft
Reduced labour resources and time