Internal Task Force Tom Rtjer, Head of Internal Task Force 9 April, - PowerPoint PPT Presentation

Internal Task Force Tom Røtjer, Head of Internal Task Force 9 April, 2018

The refining process to extract alumina The input factors, processes and output at the Alunorte alumina refinery The refining process Bauxite Caustic Water soda Bauxite residue Pressure Crystall- Rotating Bauxite vessel Filtering ization oven 170-180 o C Bauxite Alumina Crushing Bauxite Milling residue Alumina • 2.4 kilo bauxite is turned into 1 kilo alumina and 1.4 kilo bauxite residue • Stored in bauxite residue deposits • Process water treated before release 2

The bauxite residue deposits (1 and 2)

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DRS1 Albras (primary (Bauxite residue aluminium plant) Pará river deposit 1) Alunorte bauxite and coal storage area Alunorte alumina refinery area Mixing box Canal Novo and Area 45 Canal Velho Effluent water treatment plant (Area 82) 24 February, 2018 5

Rainfall volumes The event of intense rainfall 16-17 February 2018 Daily rainfall in mm resulted in 231mm in 12hr and 239mm in 24hr. Total February rainfall was 901mm Key findings 319.4mm 6 days • Extreme rainfall resulting in large amounts of water needing treatment upon release • Internal power outage due to lightning reducing water treatment capacity • External power voltage dip into refinery caused a spill of process water containing caustic soda inside the process area, that impacted the effluent water treatment plant capacity 6

Alunorte Effluent Water Treatment System Measurements in Pará River within average pH and Suspended Solids limits DRS1 effluent concrete pipe DRS1 effluent concrete pipe Return to DRS2 effluent steel pipe process area X Gate • Process area water Mixing box • Stormwater Gate X Canal Velho Effluent water treatment plant Canal Novo X Measurement point X Measurement point Alunorte/Albras Outlet from Pará River Alunorte 7

Area 45 storm water flooding Flooding contained within the walls of the surrounding pipe channels • Used for contractors and laydown area. • As part of the Alunorte Water Management improvement project that is already sanctioned, a new storm water system including new holding pond and sufficient pumping system will be constructed in Area 45 8

No overflow from DRS1 Freeboard development during event • Water retained in DRS1 in order to let Effluent Treatment Plant prioritize plant area 9

No overflow from DRS2 Freeboard development during event Borda livre DRS2 (m) Real Previsão chuva extrema Previsão base chuvas clima tempo Alvo 5,00 4,50 4,09 4,01 3,89 4,00 3,38 3,26 3,50 3,03 2,83 2,83 2,79 2,73 3,00 2,70 Borda livre m 2,55 2,41 2,31 2,50 2,20 2,14 2,11 1,98 1,86 1,76 2,00 1,66 1,63 1,60 1,60 1,40 1,40 1,50 1,00 0,50 0,00 15-fev 16-fev 17-fev 18-fev 19-fev 20-fev 21-fev 22-fev 23-fev 24-fev 25-fev 26-fev 27-fev 28-fev 1-mar 2-mar 3-mar 4-mar 5-mar 6-mar 7-mar 8-mar 9-mar 10-mar 11-mar 12-mar 13-mar 14-mar 15-mar 16-mar 17-mar 18-mar 19-mar 20-mar 21-mar 22-mar 23-mar 24-mar 25-mar 26-mar 27-mar 28-mar 29-mar 30-mar 31-mar • DRS2 had good capacity, and DRS2 basins contributed to relieving pressure on DRS1 Alleged «overflow» - photo «evidence» The same «overflow» showing that water used in media to «prove» spillover from moves from a dry zone to a wet zone DRS2. within the deposit, as it is supposed to. 10

Summary No overflow from the Bauxite residue deposits • The operational integrity of the bauxite residue deposits 1 and 2 was maintained during the event, and there were no overflow from the deposits • In order to avoid risks of harm to the environment, not fully treated effluent was released through Canal Velho into the Para River − Average effluent concentration in the river was within the prescribed limits between pH 6-9 • Recommendations have been identified to increase capacity and improve the integrity of the overall effluent water treatment system of Alunorte 11

Recommendations Plant improvements Environmental improvements Increase effluent treatment capacity: Initiate and perform an environmental baseline and effect study as basis for • By 50% before next rainy season future monitoring • Holding basin and pump capacity Area 45 • New transfer pipes and pumping facilities Invite academia in Pará Brazil/Norway to (DRS1 to ETP) high quality environmental R&D program • Integrate holding basins at the Bauxite Residue deposits Review and improve the environmental • Upgrade mixing box system monitoring • Better separation of clean storm water from Reduce external water consumption water needing treatment through reuse of internal water New Water Balance Study Update emergency plans and training Finalize closure of DRS1 Ensure good dialogue with authorities 12

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