Conference Agenda

Mine Drainage Chemistry & Passive Treatment
Thursday, 15/July/2021:
9:50am - 11:55am

Session Chair: Ian Jones
Location: Meeting Room 1

9:50am - 10:15am

A Comparison Of Be And W In Mine Drainage Downstream Two Different Repositories Storing Tailings From A Skarn Ore

Lina Hällström, Lena Alakangas

Luleå University of Technology, Sweden

The geochemical behaviour of beryllium (Be) and tungsten (W) in neutral mine drainage (NMD) downstream of two skarn tailings repositories (Smaltjärnen and Morkulltjärnen) was studied. Surface water was sampled monthly during 2018, with epilithic water diatoms used as bioindicators. Smaltjärnen (1918-1963) has been open to the atmosphere for over 30 years, while Morkulltjärnen (1969-1989) was covered and water-saturated directly after closure. NMD with high concentrations of dissolved Be from Smaltjärnen and dissolved W from Morkulltjärnen had negative environmental impacts as far as 5 km from the Yxsjöberg mine site. Re-mining could be a potential remediation method.

10:15am - 10:40am

Alternative Reagents for the Treatment of Pb-Zn Mine Drainage in Wales

Joe Dean, Ban Alkhazraji, Devin Sapsford

Cardiff University, United Kingdom

This paper presents the results of a laboratory-scale dosing experiment to test the efficacy of four low-cost / alternative reagents to removed dissolved Zn, Cd, and Pb from contaminated mine water. Hydrogen phosphate (Na2HPO4) achieved >95% Pb removal, but lower Zn and Cd removal. Sodium metasilicate (Na2SiO3) and sodium bicarbonate (NaHCO3) did not achieve suitable metal removal. A 99-244 mg/L dose of sodium carbonate (Na2CO3) removed high levels of Zn (99% ±0.2), Cd (95% ±3), and Pb (88% ±3). Sodium carbonate dosing of Zn-Cd-Pb-contaminated mine water could form the basis of a new, low cost, and low input treatment process.

10:40am - 11:05am

🎓 Dewatering, Flooding and Stratification of Nikolaus-Bader small-scale Gold Mining Shaft in Austria

Elke Mugova1, Christian Wolkersdorfer2

1Technische Hochschule Georg Agricola, Germany; 2Department of Environmental, Water and Earth Sciences, Tshwane University of Technology, South Africa

To investigate density stratification in flooded underground mines, the 10 m deep Nikolaus-Bader shaft in Biberwier/Tyrol, Austria was pumped out and the subsequent flooding process was observed. After a short time, a density stratification developed which collapsed in late autumn and built up again in spring. By means of data loggers measuring pressure, temperature and electrical conductivity in four different depths of the flooded shaft, a long-term monitoring of the water body is possible, from which conclusions can be drawn about temporal factors for the formation and collapse of density stratification

11:05am - 11:30am

Justification For Modification Of The NAG Test Method To Suit Varied Mining Waste Geochemical Characteristics On A Site-Specific Basis

Andrew Barnes1, Steven Pearce2, Diana Brookshaw2, Mark Roberts1, Seth Mueller3

1Geochemic Ltd, Lower Race, Pontypool, NP4 5UH. United Kingdom; 22Mine Environmental Management Ltd, Vale Street, Denbigh, Denbighshire, LL16 3AD. United Kingdom; 3Boliden AB, Sweden

The Net Acid Generation (NAG) test is generally carried out using a consistent method, irrespective of the site or the geochemical properties of material being tested. There are significant risks posed by utilising standard methods to assess processes which are inherently site specific like AMD. This can lead to misleading interpretations of results which is particularly true where the NAG liquor is being used to give an indication of elemental mobility during sulfide oxidative weathering. Examples include an average 3 pH unit increase between pre and post boiling, and greater than 60% reduction in nickel release to the NAG liquor.

11:30am - 11:55am

Photoelectrochemical Concurrent Hydrogen Generation and Materials Recovery from Acidic Mine Water

Sudhagar Pitchaimuthu1,2, Ben Jones2, Katherine R. Davies2

1Heriot-Watt University, United Kingdom; 2Swansea University, United Kingdom

Hydrogen is a promising future energy carrier for carbon-free transport and electrification due to its high gravimetric energy density (142 MJ kg−1) and non-polluting nature. The solar hydrogen fuel generation from water using semiconductors has received profound attention since the Honda–Fujishima effect was first demonstrated in 1972.

Our results encourage AMD water as a feedstock for PEC water splitting hydrogen generation and material recovery. A simultaneous water pollutant treatment at a photoanode and solar fuel generation at the cathode along with a material recovery open new pathways beyond the water-splitting process.