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Overview Nyrstar project


During zinc production Nyrstar - a global, integrated mining and Zn processing company - produces residual products 'goethite' and ‘neutra’, which is released in sediment form. The goethite and neutra sediments were stored in basins at its site in Balen, Belgium. However, the company no longer had the capacity to store the sludge, therefore another solution had to be found.

At a production level of 260,000 tonnes of zinc a year at the time, Nyrstar Balen produces some 75,000 tonnes of goethite per year. The process also yields 40,000 tonnes of neutralised flotation sludge a year. Based on a Build, Own, Operate, Transfer (BOOT) contract, Nyrstar wanted to tackle this problem.

Detail Nyrstar project


After an extensive selection procedure, DEME in a joint venture partnership, was awarded the contract for the outsourcing of the investment and the operation of a system for the compact stocking of goethite and the neutralisation of the sludge. We built a new mechanical dewatering system, where both residual flows are compacted. The solid filter cakes are then disposed of in the landfill on the site. To make maximum use of the existing dump capacity, historic sludge was also excavated and compacted in the dewatering system.

In several landfill capping projects, our scope consisted of:

  • Design, stability calculations, concept for capping work
  • Consolidation work
  • Processing filler materials in accordance with the remediation work at the site
  • Supply and construction of a full capping and drainage system with separate drainage of surface water and consolidation water
  • Dyke reinforcement work
  • Delivery and installation of bentonite mats (> 500.000 m²)
  • Delivery and installation of HDPE membrane liners (> 500.000 m²)

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