Modern Mining October 2019

GEOTECHNICAL ENGINEERING

Rockfall protection solution proves itself at open-pit mine

and potentially leading to production stoppages. A fall of ground occurred in May 2017 in the main pit of the mine. Although there were no effects on operations, no injuries and no equipment damage, the hazard remained alarming and required the nec- essary attention. Solution Pro-active management by Foskor identified the need for rockfall protection along the permanent ramp as a long-term solution, and areas where the jointing and geological disturbances were intense were identified. Foskor subsequently indicated which solution it would require on two identified areas. The solutions proposed were a simple drapery mesh (4 500 m²) on the one area and a 500 kJ rockfall barrier kit (150 m) on the other. Marshall Developments was appointed to implement the pro- posed solutions and approached Maccaferri SA to submit a proposal for rockfall mitigation measures. With geological and topographic information and properties provided by the client, the slope to be covered with a simple drapery mesh was modelled

Specialised geotechnical services contractor Marshall Developments, with the assistance of Maccaferri, was recently instrumental in designing and installing a rockfall protection solution at Foskor’s open-pit mine in Phalaborwa. The system was put to the test earlier this year when it successfully handled a fall of ground incident involving about 20 tons of material.

F oskor was founded by the Industrial Development Corporation (IDC) in 1951 and is currently the only vertically integrated producer of phosphate ore, phosphoric acid and granular fertiliser in South Africa. As one of the world’s largest producers of phos- phate and phosphoric acid, unceasing production is key and any disruption to mine productivity results in significant financial loss. This means the mine must constantly monitor the open-pit slopes for activity or movement to provide warning of poten- tial rockfall events. When these events do occur, loose debris or rocks can detach and fall from the face of the slopes, posing a risk to infrastructure, plant and employees,

RMC050 ICAT/2 Plus rockfall barrier kit installed to protect the main haul road.

26  MODERN MINING  October 2019