MechChem Africa January-February 2022

StitchWise and ZebraTube: a local dewatering success story

MechChem Africa visits the manufacturing facilities of ZebraTube and StitchWise in Carletonville, South Africa, and talks to StitchWise managing director, Vincent Prior (right) and Carien Spagnuolo (left), the general manager of ZebraTube.

ZebraTube. Describing typical aboveground use of these bags, Spagnuolo says that most projects tend to be emergencies. “The ma- terials we use are specifically designed for retaining solids such as silt and sand while enabling water to filter through. They are now widely used for dredging the wastewa- ter storage dams at mining facilities, which get silted up over time and generally require cleaning every year to restore their water storage capacity. “Mixed slurries from slimes and waste- water dams are pumped into our ZebraTube geotextile tubes, which hold the solids while slowly, over a few weeks, allowing the water to drain back into the dam. Once filled and dry, the tubes are broken open so the dry solids can be loaded onto trucks for safe disposal,” she explains. “Sometimes, the slurry hasmineral value,” continues Prior, “in which case geotextile bags will be used which, once dry, can be lifted into trucks and easily transported to a reprocessingplant,” he says, adding that these bags are certified to be able to contain 5.0 t. of solids while being lifted. Using geotextiles for dewatering is a pas- sive alternative tomechanical solutions such as filter or belt presses, horizontal belt filters or centrifuges. “Mechanical solutions all use much more energy and are far more capital intensive. Since a lot of our work is for tem - porary dewatering applications, clients are reluctant to invest in permanent mechanical

S titchWise has its origins in themanu- facture of geotextile dewatering and backfill bags that support thehanging walls of some of the deepest mines in the world. “We have more than two decades of experience in retaining solids andpercolat- ing liquids through our woven and stitched geotextile bags,” begins Vincent Prior, MD of StitchWise and a director of ZebraTube. These backfill dewatering bags and tubes are manufactured from woven geotextile sheets locallymanufactured by Spilo in Cape Town. “Spilofirst extrudes polypropylene pel - lets into different grades of tape. The tape is thenwoven into continuous lengths of sheet-

ing for use in agriculture, mining, civil and outdoor applications. Many different weave patterns, strengths and widths are available, whichmakes thismaterial ideal for manufac - turingour extensive rangeof dewateringbags and tubes,” he tells MechChem Africa. While StitchWise’s focus remains mostly on the manufacture of bags for the un- derground mining and backfill market, ZebraTube ® was formed back in 2016 with a strong focus on above-ground dewatering. “We are a sister company formed as a 50- 50 partnership between Spilo, our textile manufacturer, and StitchWise, our bag and tubemanufacturer,” saysCarienSpagnuoloof

Currently, 4.0-million m 2 of geotextile material goes through StitchWise’s Carletonville factory every year.

14 ¦ MechChem Africa • January-February 2022