Innovation friendly minerals policy framework

Transcription

1 Innovation friendly minerals policy framework MIN-GUIDE has received funding from the European Union s Horizon 2020 research and innovation programme under grant agreement No

2 Treatment & Recovery of Wastewater Originating from Magnesite Ore Washing Facilities Jason Tsilogeorgis Environmental Engineer GRECIAN MAGNESITE S.A. 17/10/2017

3 Who is Who GRECIAN MAGNESITE (GM) is a privately owned company established in 1959 as a mining and industrial concern GM is a magnesite specialist. The company produces and commercializes: Caustic calcined magnesia (CCM) Deadburned magnesia (DBM) Magnesium carbonate (raw magnesite) Basic monolithic refractories GM s major deposits and production facilities are located in Yerakini, Chalkidiki, Northern Greece

4 General Production Flowsheet Mining Extraction of raw material Pre-Beneficiation Separation of magnesite from waste rock Beneficiation Quality separation of magnesite grades Calcination / Sintering MgCO 3 transformation into MgO Final Processing Crushing, grinding, classification Warehousing, Loading & Forwarding

5 Water Uses Ore washing Removal of dirt, clays, etc. Road wetting Dust control in internal road network Water cooling For rotary kiln rollers, centrifugal fans, etc. Water jet cutting Removal of build-up & blockages from rotary kilns Filter dust pelletization Pelletizing of dust from ESPs and bag filters Vehicle washing Washing of excavator-loaders, dumpers, etc. Tree & plant irrigation Watering of plantings and surrounding olive tree fields Personnel Toilets, showers, drinking water

6 Water Sources Surface water Collection of precipitation and surface runoff in a natural water reservoir (lagoon) Lagoon surface area ranging from 156,700 to 186,000 m 2 (completely full) Groundwater Well water used for human consumption and irrigation of olive tree fields alone

7 Surface Water Quality Extremely hard water due to high presence of Mg 2+ ions Soft: < 8.4 o dh Medium: o dh Hard: > 14 o dh

8 Well Water Quality Very hard water due to high presence of Mg 2+ ions Soft: < 8.4 o dh Medium: o dh Hard: > 14 o dh

9 Wastewater Production Large volumes of wastewater (muddy water) produced from magnesite ore washing facilities (i.e. vibrating washing screens) Pre-Beneficiation (Pre-BF) Optical sorting (lasers) Magnetic separation Beneficiation (BF) Optical sorting (cameras) Dense media / magnetic separation

10 Pre-BF & BF Stages Flowsheet

11 Settling Tanks (Thickeners) Settling tanks rely on gravity to separate a solid/liquid mixture into: Clarified water (overflow or supernatant) Thickened sludge (underflow) Performance Parameters Influent flowrate (overflow velocity) Influent TSS concentration Nature of solid particles to be separated (settleability) Retention time Thickened sludge extraction rate Water temperature Use of coagulants and/or flocculants

12 Pre-BF Thickeners Geometric Characteristics: Diameter = 25.0 m Side water depth = 2.85 m Cone depth = 1.60 m Bottom slope 1:7 Surface area = 490 m 2 Effective volume = 1400 m 3 Operating Characteristics: Influent flowrate = 300 m 3 /hr Overflow velocity = 1.63 m/hr Retention time = 4.7 hr

13 Pre-BF Thickeners Performance Dosing of polymer solution to improve solids separation (i.e. increase settling velocity) FLOCAN from SNF FLOERGER (anionic, medium charge density, very high MW) Interparticle bridging mechanism

14 Pre-BF Tailings Pond Overall storage capacity 2,500,000 m 3 Quantity of sludge wasted so far amounts to 1,350,000 m 3 Estimated filling time years

15 BF Thickener Geometric Characteristics: Diameter = 20.0 m Side water depth = 2.50 m Cone depth = 1.50 m Bottom slope 1:6 Surface area = 314 m 2 Effective volume = 785 m 3 Operating Characteristics: Influent flowrate = m 3 /hr Overflow velocity = m/hr Retention time = hr

16 BN Thickener Performance Dosing of polymer solution to improve solids separation (i.e. increase settling velocity) FLOCAN from SNF FLOERGER (anionic, medium charge density, very high MW) Interparticle bridging mechanism

17 BN Tailings Pond Physical barrier on the south, artificial barrier (dam) on the north Overall storage capacity 140,000 m 3 Estimated filling time 12 years

18 Wastewater Production & Recovery

19 Recovered Wastewater Contribution

20 Sludge Characterization (1) Typical X-ray diffraction diagram of sludge solids

21 Sludge Characterization (2) Typical XRF analysis of sludge solids Leaching test to assess heavy metals release from sludge solids

22 Thank you for your Attention