Zero-waste mining; closed water loops in flotation

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1 Zero-waste mining; closed water loops in flotation Päivi Kinnunen, VTT Technical Research Centre of Finland Ltd VTT beyond the obvious 1

2 VTT Technical Research Centre of Finland Ltd 75 years experience in supporting our clients growth with top-level research and sciencebased results. Learn more: VTT is one of the leading R&D&I organisations in Northern Europe. We provide expert services for our domestic and international customers and partners, both in private and public sectors. * Loikkanen, T. et al. Roles, effectiveness, and impact of VTT. Towards broad-based impact monitoring of a research and technology organisation VTT, Espoo. VTT Technology p. + app. 5 p. Net turnover and other operating income 269 M (VTT Group 2016) Personnel 2,414 (VTT Group 2016) Unique research and testing infrastructure Wide national and international cooperation network 12/11/2018 2

3 VTT services for mineral sector PROCESS MINE WASTE WATER MANAGEMENT MINE MANAGEMENT Leaching and recovery Precipitation, extraction and electrochemical methods Bioleaching of low grade ores and wastes Microbiology and corrosion Recovery of scarce metals from mine waste Waste characterization Safe utilization and disposal of waste residues Optimization of water use, recycling Water treatment technologies e.g. membranes, biological and chemical AMD treatment with sulfate reducing bacteria On-line monitoring Material management for extreme conditions Safe closure Sustainability assessment and tools Risk and asset management Sustainable energy Societal impacts 12/11/2018 3

4 VTT services for water intensive industries RAW MATERIALS Sourcing of natural polymers Biomass availability and selection Separation technologies Fractionation Membrane filtration Purification CONVERSION Thermomechanical Chemical Biotechnological Products Flocculants Adsorbents and chelating agents Biodegradable anti-scalants Fixatives Surfactants, dispersants, stabilizers Rheology & viscosity modifiers CHARACTERIZA- TION AND APPLICATION TESTING Chemical characterization of monomers and polymers NMR GPC DSC Py-GC/MS Application testing Scaling Adsorption Flocculation FEASIBILITY & SUSTAINABILITY Techno-economical feasibility Dewatering concepts Mixing recipes Flocculation delay Floc strength Filter cloth studies Sustainability assessments Water footprint Handprint 4

5 Zero-Waste mining concept and main current jointly funded R&D portfolio EU SCRREEN 190 k EU MSP- REFRAM 65 k EIT SOLVOFLEX 180 k EIT BIOFLEX 4 k EU METGROW+ 7.9 M Academy of Finland EcoTail 300 k EU BioMOre 8 M EU NEMO 15 M EU ITERAMS 7.9 M Challenge Finland SECO-MIM 700k Academy of Finland CERATAIL 370k 12/11/2018 5

6 NEW ROLE OF WATER AND WASTE IN MINING From water handling cost minimization to taking care of water properties and optimizing these properties for each process step. New water reuse concepts. From depositing waste rock and tailings to utilizing waste rock and tailings for added revenue as hardening mine fill or products. New ways of safe depositing of remaining tailings.

7 CHALLENGE Complete closure of water loops increases thermodynamical and kinetic unstability and process disturbance ITERAMS creates capabilities via laboratory experiments, modelling and validation at mine sites to tackle this complexicity GANGUE SOLIDS IONIC STRENTGH MICROBES TEMPERATURE CLOSED WATER AND WASTE LOOPS DISSOLVED CHEMICAL SPECIES COLLOIDAL SPECIES ORGANICS ph MATERIAL REACTIVITY REAGENT INTERACTIONS Eh

8 Laboratory and pilot testing 12/11/2018 8

9 Virtual laboratory as a tool to bring theory in practise: Sulphate reduction in process water Customer: Terrafame Group High sulphate concentrations in discharged water at the metals production in Terrafame Mine. Numerical simulations: 1. Prior to lab scale experimental work to reduce work load in expensive testing. 2. After the lab experiments to evaluate effects of possible changes in complex process environment. Evaluation of alternative process solutions by simulation results in faster evaluation cycle and lower R&D cost. Simulation enables quick and reliable feasibility check of alternative chemical routes to reduce sulphate in discharged process water. Data for decision-making for next steps in process development. Result Updated model for cost efficient evaluation of new process solutions 12/11/2018 9

10 Example: CFD modelling of flotation Mineral separation by flotation Fluid flow in flotation cells, three phases: liquid, solid, gas Slurry flow: water + minerals Gas behaviour: water + air Population balances of bubble sizes (break-up and coalescence of bubbles) Three phase model: under development x/h Exp. Simulation r/r = Effects of slurry and gas to the flow field and power draw 0.2 P (W) Mittaus Meas. Laskettu CFD P (W) CFD Meas. x/h Volume fraction (%) r/r = 0.47 Exp. Simulation RPM Water Jg (cm/s) Water + air Volume fraction (%) 10

11 Artificial intelligence assists in process development: Example of design of processes for gold ore The uniqueness of each ore deposit makes gold extraction process development challenging. The amount of knowledge concerning the processing of gold ores is large and continuously increasing. Case-based reasoning (CBR) system recommends flowsheet alternatives 1. Knowledge from public sources regarding the gold extraction processes are externalized and formalised 2. Similarity of relevant entities is modelled and a case-base is built Suggestions of the CBR system provide useful information and direction for processing a potential gold ore deposit Pilot scale experiments are achieved sooner System performed well compared to the human experts Result System aids in defining the needed experiments 12/11/

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