The handover certificate validated that, with regard to reducing the boiler flue gas emissions, the plant, which is believed to be the first of its kind in Africa, meets the stringent requirements of the National Environment Management Air Quality Act (NEMAQA).
Given the complexity of the project and in order to minimize stoppages of the operating plant, the project was carried out in two phases. The first phase comprised the Particulate Matter/Sulphur Dioxide (PM/SOx) reduction plant that was handed over in July 2016, whilst the second and final phase of the project comprised the Nitrogen Oxides (NOx) plant handed over in May 2019.
In addition, TAKRAF Africa recorded an exceptional safety record of zero Lost Time Injuries (LTIs). This was achieved despite the significant challenges posed by the overall construction of, in particular, the NOx plant, which was built in a brownfields area. The project was awarded to TAKRAF Africa in June 2013, with the objective of providing a facility that would significantly reduce boiler flue gas emissions generated by the six coal-fired boilers at the Base Metals Refinery (BMR), and at the same time provide the most economical solution with the minimum of technical risk.
Ensuring full compliance with the Occupational Health and Safety (OHS) Act, ISO 9001 and ISO 14001, the first phase was designed to reduce PM and SOx emissions from the boiler flue gas to levels of less than 25 mg/Nm3 and less than 200 mg/Nm3, respectively, using a Tenova-Simatek Dry Flue Gas Cleaning System (DFGCS).
The second phase was designed to reduce emissions of NOx from the boiler flue gas from 450 mg/Nm3 to less than 150 mg/Nm3, using a Tenova-ELEX De-NOx Selective Catalytic Reaction (SCR) System.
The BEA plant, which is fully integrated with the existing utilities plant and boiler flue gas installation, produces a minimal amount of waste residual from plant operations, minimising the environmental impact from waste handling and disposal, as well as the associated costs of waste disposal.
In line with TAKRAF Africa and the client’s commitment to local manufacture, more than 80% of the BEA plant’s components were locally sourced.
According to TAKRAF Africa Project Manager, Theo Nkisimane, design challenges on the De-NOx plant called for innovative approaches, including addressing the impact of the operating temperature of the SCR reactor on the boiler feed water temperature, as well as on the bag filter inlet temperature.
“We are proud to have been able to develop this innovative and ground breaking solution that has assisted Impala Platinum Refineries to become one of the first in the industry to institute measures to ensure that it fully complies with the latest requirements of the National Environment Management Air Quality Act” notes Nkisimane.